The present disclosure relates to a splicing device and a method for splicing sheets of material.

In manufacturing processes of consumables, for example heat-not-burn articles where an aerosol generating substrate is heated rather than combusted, the articles or elements of these articles are manufactured in a continuous process. Often, a band of material is unwound from a bobbin and spliced to a band of the same material unwound from a new bobbin. Such a process should be automatic in order to keep production machines continuously running. Known splicing devices are adapted for splicing a specific material used for the manufacture of a specific element. However, in particular heat-not-burn articles comprise elements of materials having different physical and chemical characteristics and known splicing devices do not work properly with such different materials.

Thus, there is need for a splicing device suitable for splicing different kinds of sheets of materials. In particular, there is need for a splicing device that is suitable for splicing tobacco containing sheet material, as well as suitable for splicing paper and plastic sheets.

According to an aspect of the present invention, there is provided a splicing device comprising a punch plate and a counter plate, wherein the punch plate and the counter plate are relatively movable versus each other for splicing two sheets of material arrangeable in between the punch plate and the counter plate. The punch plate comprises an array of splicing protrusions and the oppositely arranged counter plate comprises an array of splicing holes. The array of splicing holes comprises a number of splicing holes and the array of splicing protrusions comprises a number of splicing protrusions, wherein the number of splicing holes is at least the same as the number of splicing protrusions, and wherein a position of the splicing protrusions in the array of splicing protrusions corresponds to a position of the splicing holes in the array of splicing holes.

The use of splicing protrusions and corresponding splicing holes allows to possibly perforate one or even both sheets of material to be spliced, in addition to a mechanical deformation of the two sheets of materials in the region of the splicing protrusions and corresponding splicing holes. Thus, a very expressed interpenetration of the two sheets of material is achieved and leads to a very strong splice. The splice may be even stronger if the material to be spliced is prone to plastic deformation or partial melting.

The splicing device according to the invention is available, for example, for conventional paper sheets, for plastic sheets, but also for specially fibrous sheets as the splicing protrusions may penetrate the fibers in a fibrous sheet material, or also for metal sheets that are not easily spliced all.

Preferably, the punch plate comprises all splicing protrusions and the counter plate comprises all splicing holes. However, splicing protrusions and splicing holes may also be provided on both, the punch plate and the counter plate. In some embodiments of the splicing device, both the punch plate and the counterplate comprise an array of splicing protrusions and an array of splicing holes. In these embodiments, preferably the positions of each of the splicing protrusions of the punch plate correspond with the positions of a splicing hole in the counter plate and vice versa.

In embodiments where splicing protrusions and splicing holes are provided on the punch plate and on the counter plate, preferably, splicing protrusions and splicing holes are arranged in an alternating manner on each of the punch plate and the counter plate.

In the splicing device, the positions of splicing protrusions correspond to positions of splicing holes when the splicing device is in a closed splicing position. Preferably, the positions of splicing protrusions also correspond to positions of splicing holes when the splicing device is in an open position, thus when the punch plate and the counter plate are arranged distanced from each other.

Preferably, a splicing protrusion may be inserted in a splicing hole when punch plate and counter plate are closed for splicing the sheets of material.

Preferably, splicing protrusions and splicing holes are arranged along a straight line corresponding to a linear direction of movement of the punch plate and counter plate versus and away from each other.

Preferably, the punch plate and the counter plate are arranged parallel to each other, in an open and in a closed position of the splicing device. Splicing may then be performed with a linear movement of one or both plates toward the other plate or toward each other.

Punch plate and counter plate may have individual shapes and sizes. For example, a counter plate may be an integrated part of a transport surface for the sheets of material.

Preferably, punch plate and counter plate have same dimensions in length and width. A width of a plate may correspond to a transport direction of a sheet material, while a length of a plate may then correspond to a direction perpendicular to the transport direction in a plane of the sheet material. Same dimensions in length and width provide the advantage of a symmetric set-up of the splicing device. The splicing device is preferably arranged parallel or perpendicular to a transport direction of the sheets of material. Accordingly, a length or width of a punch plate is arranged parallel or perpendicular to a transport direction of the sheets of material. This may keep a spliced portion as small as possible. However, a splicing device may also be arranged at an angle to the transport direction of the sheets of material.

The splicing protrusions may have any form that allows to deform and preferably penetrate and perforate at least one of the sheets of material arranged above each other for splicing. Preferably, the splicing protrusions have a shape and size that allows to deform and preferably penetrate and perforate both of the sheets of material arranged above each other for splicing. Preferable, the splicing protrusions have an elongate shape.

Preferably, the splicing protrusions have a tip end arranged most distantly from the punch plate, when the splicing protrusion is provided at the punch plate.

Preferably, the splicing protrusions have a tip end arranged most distantly from the counter plate, when the splicing protrusion is provided at the counter plate.

Preferably, the splicing protrusions are splicing pins.

Preferably, the splicing protrusions have a pointed tip, a rounded tip or a tip provided with cutting edges. Pointed and rounded tips are reliable means in splicing processes of a wide range of sheets of material. The use of splicing protrusions, in particular splicing pins, provided with cutting edges, is advantageous for strong materials, such as for example metal sheets, or for elastic materials, such as for example plastic sheets.

As used herein with reference to the invention, the term “sheet” describes a laminar element having a width and length substantially greater than the thickness thereof.

The splicing protrusions may, for example, have a round, circular, triangular, polygonal, square or star-shaped cross-section. The cross sections of the splicing protrusions may be the same over a length of a splicing protrusion or may vary over a length of a splicing protrusion. The length of a splicing protrusion corresponds to the extension of the splicing protrusion from the surface of the plate the splicing protrusion is provided.

Corresponding splicing holes may have a same or a different size than a splicing protrusion. In particular, a splicing hole may have a same cross section than a corresponding splicing protrusion. A cross section and depth of a splicing hole is at least as large as a corresponding splicing protrusion in order for a splicing protrusion to fit into the splicing hole. However, a cross section of a splicing hole does not have to be the same as the cross section of a splicing protrusion. In particular, a splicing hole may be a circular hole receiving various forms of splicing protrusions.

Preferably, splicing holes have a circular, polygonal or triangular or square cross section.

Preferably, splicing holes are drill holes.

A length of a splicing protrusion may be in a range between 1 millimeter and 50 millimeter. Preferably, a length of a splicing protrusion is in a range between 3 millimeter and 20 millimeter. More preferably, a length of a splicing protrusion is in a range between 4 millimeter and 10 millimeter, for example 6 millimeter.

A cross section area, for example a diameter, of a splicing protrusion may, for example, be in a range between 0.5 millimeter and 20 millimeter. Preferably, a cross section area, in particular a diameter, of a splicing protrusion is in a range between 1 millimeter and 10 millimeter. More preferably, a cross section area in particular a diameter, of a splicing protrusion is in a range between 2 millimeter and 5 millimeter, for example 3 millimeter. A cross section area, in particular a diameter, of a splicing hole may, for example, be in a range between 0.5 millimeter and 20 millimeter. Preferably, a cross section area, in particular a diameter, of a splicing hole is in a range between 1 millimeter and 10 millimeter. More preferably, a cross section area, in particular a diameter of a splicing hole is in a range between 2 millimeter and 5 millimeter, for example 3 millimeter.

Dimension and sizes in these rages have provided good splicing results for a large variety of sheet materials to be spliced, for example fibrous sheets, sheets of tobacco material, plastic sheets and also metal foils.

Preferably, all splicing protrusions of an array of splicing protrusions have a same length and a cross section area. Preferably, all splicing protrusions on a punch plate and on a counter plate have a same length and a same cross section area.

Preferably, all splicing holes of an array of splicing holes have a same cross section area.

Preferably, all splicing holes have a same shape.

Identical forms of splicing protrusions and identical forms of splicing holes of arrays or in total, may provide a homogenous spliced portion. However, parts of an array of splicing protrusions and corresponding splicing holes may have different forms or sizes than other parts of the same array, in order to vary a splice. For example, a stronger splice or a weaker splice may be manufactured in some areas of a spliced portion than in other areas of the spliced portion.

A total number of splicing protrusions and corresponding splicing holes may be chosen according to the size of one or more spliced portions to be manufactured, the size of the material to be spliced, or may be adapted to a material to be spliced.

A total number of splicing protrusions may, for example, be between 2 and 250. Preferably, a total number of splicing protrusions is between 10 and 200. More preferably, a total number of splicing protrusions is between 20 and 100, for example 70.

The total number of splicing holes is at least the same as the total number of splicing protrusions. Preferably, the total number of splicing holes corresponds to the total number of splicing protrusions.

Splicing protrusions may be formed integrally with a plate or may be attached to the plate. Splicing protrusions may comprise or may be made of a same material as a plate the protrusion is extending from.

Splicing protrusion may comprise, for example, steel, preferably stainless steel, polycarbonate, ceramic, thermoset material such as for example Bakelite®, or silicone.

Splicing protrusions may be made, for example, of steel, preferably, stainless steel, polycarbonate, ceramic, thermoset materials such as for example Bakelite®, or silicone. The splicing device, in particular the punch plate and the counter plate, more particularly the splicing protrusions, may be specifically treated, for example to enhance endurance or to prevent adhesion of the sheet material to the splicing parts.

For example, the splicing protrusions may be coated or thermochemically treated.

The splicing device may comprise a liquid supply for supplying a liquid to a sheet of material to be spliced. To enhance the strength of a splice, a liquid may be applied to one or to both sheets of material.

Some materials are tacky as such, for example, tobacco containing cast leaf, get tacky or tackier when provided with a liquid.

Preferably, a liquid is a liquid as used in the food industries.

Preferably, a liquid is water or a liquid natural adhesive such as, for example, fish glue or egg white.

Preferable, a liquid supply is adapted for supplying water or a liquid natural adhesive such as, for example, fish glue or egg white.

Some materials get tacky or more easily deformed when heated. For example, some plastic materials have a low melting temperature or a low glass temperature, for example polylactic acid. Polylactic acid sheets are used, for example, in the manufacture of filters for smoking articles or heat-not-burn articles.

Upon heating the sheets of material while splicing may enhance the strength of a splice.

The splicing device may comprise a heater for heating parts of at least one of the punch plate and the counter plate.

Preferably, a heater is adapted to heat at least some of the splicing protrusions, which splicing protrusions are provided on either of the punch plate and the counter plate of the splicing device. More preferably, the heater is adapted to heat all splicing protrusions. A heater may be an electric heater provided in the splicing device. A heater may also be an infrared heater or any other suitable heater, internal or external to the splicing device.

In preferred embodiments of the splicing device, the splicing device comprises a detacher for detaching sheet of material from the punch plate or from the counter plate. A detacher allows to detach a sheet of material, in particular a spliced portion, from the splicing device.

Preferably, a detacher is adapted to detach sheet of material from splicing protrusions.

With the provision of a detacher, also tacky materials or materials that tend to tack to a surface before or after having been spliced, may preferably automatically be released from the splicing device. This allows for an in-line splicing process without having to interrupt product manufacturing machines or processes arranged further downstream of the splicing device. In addition, with a detacher, materials otherwise not accessible to known splicing devices may be spliced with the splicing device according to the invention. This applies to the above-mentioned tacky materials but also, for example, sheets of material that can hardly be spliced without additional materials, such as for example adhesives or adhesive tapes. For example, metal sheets cannot securely be spliced by the simple provision of an array of dents in the sheets. Thus, with the provision of forming an interlocking portion in metal sheets, these may be spliced. However, spliced metal sheets also tend to stay on the splicing protrusions.

Thus, by the provision of a detacher the splicing device according to the invention is basically a universal splicing device usable for all different kinds of sheets of material.

Preferably, a detacher is provided at least at one of the punch plate and the counter plate.

Preferably, a detacher is provided at the punch plate, as the punch plate is always provided with splicing protrusions. A detacher provided at the punch plate preferably releases the spliced sheets of material from the splicing protrusions provided at the punch plate.

A detacher may be provided at the punch plate and at the counter plate. This is particularly advantageous, if punch plate and counter plate are provided with splicing protrusions. However, a detacher provided at the counter plate may also be advantageous if the counter plate is not provided with splicing protrusions. A splicing process firmly presses sheet material against the counter plate and usually also into the splicing holes. A detacher provided at the counter plate may secure a safe detaching of the sheet material out of splicing holes and from the counter plate.

Preferably, a detacher is elastically mounted and thus actuated by elastic means, for example spring means such as leaf springs or coil springs. Other elastic means suitable as detacher actuation are, for example, reversibly compressible materials arranged between a punch plate, or possibly also a counter plate, and a detacher.

Preferably, a detacher comprises an elastically mounted detacher plate. A detacher plate is preferably arranged parallel to the punch plate. The detacher plate may be connected to the punch plate and may be spring biased against the punch plate.

The detacher may comprise a single plate or several plate strips arranged parallel and next to each other, preferably in one plane.

Preferably, a detacher plate is a spring biased detacher plate, for example spring biased with one or more leaf springs or one of more coil springs. For example, a spring may be provided at both longitudinal ends of a detacher plate or alternatively, at each of four corners of a detacher plate. In an open position of the splicing device, punch plate and counter plate are separated and distanced from each other and elastic means, in particular springs, are relaxed. The detacher plate is arranged distanced from the punch plate such that two sheets of material may be arranged in between punch plate and counter plate for splicing. Upon splicing, punch plate and counter plate are moved towards each other into a closed state of the splicing device. Elastic means are compressed and the sheets of material in the spicing device are spliced. Upon release of punch plate and counter plate, the elastic force, in particular spring force, of the elastic means, push the detacher plate away from the punch plate. Thereby, the spliced sheet material is pushed away from the punch plate and thus freed from the spicing protrusions arranged on the punch plate.

Preferably, in an open position of the splicing device the detacher plate is moved away from the punch plate to tip ends of splicing protrusions. Preferably, a detacher plate in an open position of the splicing device is arranged flush with tip ends of splicing protrusions or even goes beyond the tip ends. This bears the advantage that a compete release of sheets of material or of a spliced portion from the splicing protrusions after splicing may be achieved. A transport of the spliced sheet material out of the splicing device may then be performed unhindered and preferably without damaging the sheets of material by still being caught at splicing protrusions.

In some embodiments of the splicing device, a first elastically mounted detacher plate is connected to the punch plate and a second elastically mounted detacher plate is connected to the counter plate. These embodiments are particularly advantageous when both, punch plate as well as counter plate are provided with splicing protrusions. Individual detacher plates provided for each of the plates of the splicing device improve the manufacture of a clean splicing portion and safe transport of the spliced sheets of material out of the splicing device.

Preferably, a detacher plate comprises an array of through holes. The array of through holes corresponds to the array of splicing protrusions provided in the corresponding plate the detacher plate is in operation with or mounted to, respectively. Thus, the array of through holes in particular corresponds to the array of splicing protrusions of the punch plate. In particular, the array of through holes in the detacher plate corresponds in position, number and size to the array of splicing protrusions in the punch plate and optionally also to an array of splicing protrusions of the counter plate if the counter plate is also provided with splicing protrusions.

When a detacher comprises several plate strips arranged in one plane, the plate strips preferably are full plate strips and comprise no holes. The manufacturing of such full plate strips is very cost efficient.

The provision of a detacher plate with through holes corresponding to splicing protrusions of a punch plate allows for a complete and precise detaching of a spliced sheet from the splicing protrusions as the spliced sheet is guided by the through holes of the detacher plate along and off the splicing protrusions. This of course also applies if the counter plate is provided with spicing protrusions.

Preferably, a detacher plate has a same dimension in length and width as the punch plate. If a detacher plate is provided at the counter plate, then preferably, a detacher plate has a same dimension in length and width as the counter plate.

A thickness of a detacher plate is preferably as small as possible to reduce material cost and weight and to minimize force needed to move the detacher plate. According to another aspect of the present invention, there is provided a method for splicing sheets of material using an apparatus according to the present invention and as described herein. The method comprises: providing a first sheet of material from a first bobbin and providing a second sheet of material from a second bobbin; positioning the first sheet of material the second sheet of material in a splicing location and overlapping the first sheet of material and the second sheet of material in the splicing location; splicing the first sheet of material and the second sheet of material in the splicing location by interpenetration of the first sheet of material and the second sheet of material by an array of splicing protrusions and a corresponding array of splicing holes, thereby moving the array of splicing protrusions and the array of splicing holes versus each other and pressing at least one of the two sheets of material into the array of splicing holes by the array of splicing protrusions, thereby forming a spliced portion of the first and second sheet of material.

With the method according to the invention, two sheets of material to be spliced are made to interpenetrate each other in a splicing location by allowing splicing protrusions to deform and push the sheets of material perpendicular to the plane of the sheets out of a transport plane of the sheets by forcing and allowing at least one of the sheets, preferably both sheets, to be pushed into splicing holes with the splicing protrusions. By this, an interpenetration of the two sheets extends over a length which is longer than for example a splice performed by pressing two sheets together with a stamp pushed against a counter plate as known in the art. Thus, a spliced portion may be made stronger and thus the risk that a spliced portion ruptures is minimized. In addition, splicing of sheets hard to be spliced is made available with the method according to the invention.

Preferably, the method comprises moving splicing protrusions and corresponding splicing holes along a same straight line for splicing the sheets of material. While the method may be embodied, for example, by using a punch roller and a corresponding counter plate, preferably, sheets of material are spliced using a punch plate and corresponding counter plate, which are arranged parallel to each other.

The method may comprise applying a pressure in a range between 0.1 bar and 30 bar to form a spliced portion. A variation of a splicing pressure in these ranges have shown to provide good results for a wide variety of materials and thicknesses of sheets of material to be spliced.

Preferably, the sheets of materials are kept stationary for splicing.

The method may comprise slightly moving a punch plate and a counter plate in an opposite direction and perpendicular to a splicing direction. By this, a strength of the spliced portion may be enhanced. The splicing direction corresponds to the preferably linear movement of punch plate and counter plate towards each other. By slightly moving the plates in opposite direction and perpendicular to the splicing direction, the sheets of material are basically further pressed in and with the splicing protrusions and splicing holes.

The first or the second sheet of material may basically be any sheet of material that needs to be spliced. In particular, the sheets of material are materials that are used in the tobacco industries, in particular in the manufacture of heat-not-burn articles, thus articles where a tobacco material or another aerosol-generating material is heated rather than combusted.

Thus, the first or the second sheet of material may, for example, be any one of a cellulose containing sheet material, a tobacco material containing sheet material, an aerosol-generating sheet material, a polylactic acid sheet or a metal sheet such as for example, an aluminium sheet or a susceptor sheet, in particular a magnetic material comprising sheet material.

Preferably, the first or the second sheet of material is any one of a paper sheet, a laminated paper sheet, a homogenized tobacco material containing sheet, a tobacco material containing cast leaf or a susceptor sheet.

Examples of paper or plastic sheets to be spliced are wrappers for circumscribing an aerosol-generating rod or elements of such a rod. These may be paper wrappers or non-paper wrappers. Paper wrappers include, but are not limited to cigarette papers, tipping paper and filter plug wraps.

Non-paper wrappers include, but are not limited to sheets of homogenised tobacco material.

Paper wrappers may have a grammage from 15 gsm to 35 gsm, preferably from 20 gsm to 30 gsm.

Paper wrappers may have a thickness from 25 micrometres to 55 micrometres, preferably from 30 micrometres to 50 micrometres, more preferably from 35 micrometres to 45 micrometres.

A wrapper may be formed of a single layer or a laminate material comprising a plurality of layers. A wrapper may be formed of an aluminium co-laminated sheet.

The paper layer of the co-laminated sheet may have a grammage from 35 gsm to 55 gsm, preferably from 40 gsm to 50 gsm.

The paper layer of the co-laminated sheet may have a thickness from 50 micrometres to 80 micrometres, preferably from 55 micrometres to 75 micrometres, more preferably from 60 micrometres to 70 micrometres.

The metallic layer of the co-laminated sheet may have a grammage from 12 gsm to 25 gsm, preferably from 15 gsm to 20 gsm.

The metallic layer of the co-laminated sheet may have a thickness from 2 micrometres to 15 micrometres, preferably from 3 micrometres to 12 micrometres, more preferably from 5 micrometres to 10 micrometres. A paper wrapper may comprise PVOH (polyvinyl alcohol) or silicone (or polysiloxane) (or polysiloxane). Addition of PVOH (polyvinyl alcohol) or silicone (or polysiloxane) may improve the grease barrier properties of the wrapper.

The paper wrapper comprising PVOH or silicone (or polysiloxane) may have a grammage from 20 gsm to 50 gsm, preferably from 25 gsm to 45 gsm, more preferably from 30 gsm to 40 gsm.

The paper wrapper comprising PVOH or silicone (or polysiloxane) may have a thickness from 25 micrometres to 50 micrometres, preferably from 30 micrometres to 45 micrometres, more preferably from 35 micrometres to 40 micrometres.

Paper sheets but in particular also plastic sheets are commonly used in filters or cooling segments of aerosol-generating articles, for examples articles as used in electronic heating devices.

Filters may be formed of a bioplastic material, preferably a starch-based bioplastic material. Filters may be formed of a polylactic acid based material.

Other examples of sheet materials used for example in heat-not-burn articles, are coated paper layers, in particular polymer coated paper layers. Polymer-coated papers may in particular be used in cooling segments for heat-not-burn articles.

A polymer-coated paper includes a paper and a polymer layer that contains a polymer and that is provided on the paper.

The polymer layer may be provided only on either surface of the polymer-coated paper or may be provided on both surfaces of the polymer-coated paper.

A polymer-coated paper has better formability than a polymer sheet. Specifically, different from a polymer sheet (film), the polymer-coated paper even in a small amount can be folded into a desirable shape since the polymer layer is formed on a paper base having predetermined hardness and thickness. Furthermore, even a material that is excellent in heat absorption but cannot be formed into a sheet (film) by itself is usable by thinly applying a polymer to a paper.

The paper is not particularly limited provided that the paper functions as a support. However, in view of feasibility of filter wrapping, the basis weight of the paper is preferably 35 g/m<2> or more and more preferably 35 to 70 g/m<2>. Moreover, the paper preferably has a low air per permeability and more preferably has an air permeability of zero. The thickness of the paper is not particularly limited and may be 30 to 70 pm, for example.

The polymer layer contains a polymer. The types of the polymer are not particularly limited but are preferably biodegradable polymers or edible polymers. From a viewpoint of allowing the polymer to undergo the phase transition and to absorb heat at a temperature inside a cooling segment, the polymer has a glass transition temperature (Tg) of preferably 400°C or lower, more preferably 200°C or lower, and further preferably 100°C or lower. The lower limit of Tg of the polymer is not particularly limited and may be 40°C or higher, for example. Herein, the Tg of a polymer is specifically a value measured with a differential scanning calorimeter (trade name: "DSC7000" from Hitachi High-Tech Science Corporation). Specific examples of the polymer include polyvinyl alcohol (PVA), cellulose acetate, trehalose, maltose, sucrose, maltitol, glucose, waxes, and hardened oils. These may be used alone or in combination. Among these, PVA or polyvinyl alcohol-acrylic acid-methyl methacrylate copolymer (POVACOAT) is preferable as a polymer in view of satisfactory coating properties of paper. Particularly by PVA, heat absorbing effects through phase transition are readily obtained due to its low Tg. In addition, cooling effects are also readily obtained through adsorption of water vapor in an aerosol due to its high affinity with water.

When the polymer is PVA, the PVA preferably has an average degree of polymerization of 1 ,500 or less. When PVA has an average degree of polymerization of 1 ,500 or less, it is possible to improve coating properties of paper and uniformly form a polymer layer on paper. The average degree of polymerization of PVA is more preferably 100 or more and 1,300 or less, further preferably 300 or more and 1,200 or less, and particularly preferably 500 or more and 1 ,000 or less. Herein, the average degree of polymerization of PVA is a value measured in accordance with the testing methods for polyvinyl alcohol in JIS K 6726-1994.

Moreover, when the polymer is PVA, the PVA preferably has a degree of saponification of 70 mol% or more and 99 mol% or less. As describe hereinafter, when the polymer layer contains a volatile component, PVA having a degree of saponification of 99 mol% or less improves solubility in water, thereby enhancing the release performance of the volatile component. The degree of saponification of PVA is more preferably 75 mol% or more and 99 mol% or less and further preferably 80 mol% or more and 99 mol% or less. Herein, the degree of saponification of PVA is a value measured in accordance with the testing methods for polyvinyl alcohol in JIS K 6726-1994.

Aerosol-generating articles typically comprise an aerosol-generating element comprising or being made of an aerosol-generating sheet. An aerosol-generating sheet is an aerosolgenerating substrate that denotes a substrate capable of releasing volatile compounds upon heating to generate an aerosol.

Aerosol-generating sheets typically comprise an aerosol former. Suitable aerosol formers for inclusion in an aerosol-generating substrate are known in the art and include, but are not limited to: polyhydric alcohols, such as triethylene glycol, propylene glycol, 1 ,3-butanediol and glycerol; esters of polyhydric alcohols, such as glycerol mono-, di- or triacetate; and aliphatic esters of mono-, di- or polycarboxylic acids, such as dimethyl dodecanedioate and dimethyl tetradecanedioate.

Preferably, an aerosol-generating substrate comprises tobacco material.

Preferably, the aerosol-generating substrate comprises homogenised plant material, preferably a homogenised tobacco material. As used herein, the term “homogenised plant material” encompasses any plant material formed by the agglomeration of particles of plant. For example, sheets or webs of homogenised tobacco material for the aerosol-generating substrates of the present invention may be formed by agglomerating particles of tobacco material obtained by pulverising, grinding or comminuting plant material and optionally one or more of tobacco leaf lamina and tobacco leaf stems. The homogenised plant material may be produced by casting, extrusion, paper making processes or other any other suitable processes known in the art.

Sheets of homogenised plant material may be produced by a casting process. Alternatively, sheets of homogenised plant material may be produced by a paper-making process.

Sheets comprising homogenized plant material, in particular homogenized tobacco material, may have a thickness of between 100 micrometres and 600 micrometres, preferably between 150 micrometres and 300 micrometres, and most preferably between 200 micrometres and 250 micrometres.

The sheets of homogenised plant material may have a grammage of between 100 grams per square metre and 600 grams per square metre.

The sheets of homogenised plant material may have a density of from 0.3 grams per cubic centimetre to 1.3 grams per cubic centimetre, and preferably from 0.7 grams per cubic centimetre to 1.0 gram per cubic centimetre.

The homogenised plant material may comprise between 2.5 percent and 95 percent by weight of plant particles, or between 5 percent and 90 percent by weight of plant particles, or between 10 percent and 80 percent by weight of plant particles, or between 15 percent and 70 percent by weight of plant particles, or between 20 percent and 60 percent by weight of plant particles, or between 30 percent and 50 percent by weight of plant particles, on a dry weight basis.

In some examples, the homogenised plant material is a homogenised tobacco material comprising tobacco particles. Sheets of homogenised tobacco material may have a tobacco content of at least about 40 percent by weight on a dry weight basis, more preferably of at least about 50 percent by weight on a dry weight basis more preferably at least about 70 percent by weight on a dry weight basis and most preferably at least about 90 percent by weight on a dry weight basis.

An aerosol-generating substrate may be in the form of an aerosol-generating film comprising a cellulosic based film forming agent, for example nicotine and preferably also an aerosol former. The aerosol-generating film may further comprise a cellulose-based strengthening agent. The aerosol-generating film may further comprise water, preferably 30 percent by weight of less of water. As used herein, the term “film” is used to describe a solid laminar element having a thickness that is less than the width or length thereof. The film may be self-supporting. In other words, a film may have cohesion and mechanical properties such that the film, even if obtained by casting a film-forming formulation on a support surface, can be separated from the support surface. Alternatively, the film may be disposed on a support or sandwiched between other materials. This may enhance the mechanical stability of the film.

The aerosol former content of the aerosol-generating film is within the ranges defined above for the aerosol-generating substrate.

In the context of the present invention the term “cellulose based film-forming agent” is used to describe a cellulosic polymer capable, by itself or in the presence of an auxiliary thickening agent, of forming a continuous film.

Preferably, the cellulose based film-forming agent is selected from the group consisting of hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), ethylcellulose (EC), hydroxyethyl methyl cellulose (HEMC), hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), and combinations thereof.

More preferably, the cellulose based film-forming agent is selected from the group consisting of hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), ethylcellulose (EC), and combinations thereof.

In particularly preferred embodiments, the cellulose based film-forming agent is HPMC.

The aerosol-generating film may have a cellulose based film-forming agent content of between 10 percent and 40 percent by weight, or between 15 percent and 35 percent by weight, or between 20 percent and 30 percent by weight, on a dry weight basis.

Preferably, the aerosol-generating film further comprises a cellulose based strengthening agent. Preferably, the cellulose based strengthening agent is selected from the group consisting of cellulose fibres, microcrystalline cellulose (MCC), cellulose powder, and combinations thereof.

The aerosol-generating film may have a cellulose based strengthening agent content of between 0.5 percent and 40 percent by weight on a dry weight basis, or between 5 percent and 30 percent by weight on a dry weight basis, or between 10 percent and 25 percent by weight on a dry weight basis.

The aerosol-generating film may further comprise a carboxymethyl cellulose, preferably sodium carboxymethyl cellulose.

The aerosol-generating film may have a carboxymethyl cellulose content of between 1 percent and 15 percent by weight, or between 2 percent and 12 percent by weight, or between 5 percent and 10 percent by weight on a dry weight basis.

The aerosol-generating film preferably comprises nicotine.

The aerosol-generating film may be a substantially tobacco-free aerosol-generating film. The aerosol-generating film may comprise an acid. The aerosol-generating film may comprise one or more organic acids. The aerosol-generating film may comprise one or more carboxylic acids. The acid may, for example, be lactic acid, benzoic acid, fumaric acid or levulinic acid.

Preferably, the aerosol-generating film comprises between 0.25 percent and 3.5 percent by weight of an acid, or between 0.5 percent and 3 percent by weight of an acid, or between 1 percent and 2.5 percent by weight of an acid, on a dry weight basis.

The aerosol-generating film may have a thickness from about 0.1 millimetres to about 1 millimetre, more preferably from about 0.1 millimetres to about 0.75 millimetres, even more preferably from about 0.1 millimetres to about 0.5 millimetres. In particularly preferred embodiments, a layer of the film-forming composition is formed that has a thickness from about 50 micrometres to 400 micrometres, more preferably from about 100 micrometres to 200 micrometres.

Sheets of material to be spliced and preferably used in heat-not-burn articles, may also be metal sheet, such as, for example thermally conductive metal sheets or inductively heatable metals sheets, such as for example susceptor sheets.

Herein, the term “susceptor” refers to a material that can convert electromagnetic energy into heat. When located within a fluctuating electromagnetic field, eddy currents induced in the susceptor element cause heating of the susceptor element. In magnetic materials, heating may also be induced by hysteresis losses.

A susceptor sheet may generally have a thickness from 0.01 millimetres to 2 millimetres, for example from 0.5 millimetres to 2 millimetres. In some embodiments, the susceptor sheet preferably has a thickness from 10 micrometres to 500 micrometres, more preferably from 10 micrometres to 100 micrometres.

Preferred susceptor sheets may comprise or consist of a ferromagnetic material, for example a ferromagnetic alloy, ferritic iron, or a ferromagnetic steel or stainless steel. A suitable susceptor sheet or heat conductive layer may be, or comprise, aluminium.

The method according to the invention may further comprise applying a liquid to at least one of the first and the second sheet of material before splicing the sheets of material. The liquid may be a natural liquid. The liquid may, for example, be water, egg white or fish glue. In particular, a tackiness of cast leaf may be improved by the application of water to the area of the sheet of cast leaf to be spliced.

The method may comprise applying an amount of liquid up to 25 milliliter per square centimeter (ml/cm<2>).

The method may further comprise heating a punch plate or a counter plate. Preferably, the method comprises heating a punch plate or a counter plate to a temperature of up to 300 degree Celsius. Preferably, the method comprises heating a punch plate or a counter plate to a temperature between 50 degree Celsius and 200 degree Celsius. Both plates may be heated. In particular, preferably splicing protrusions provided on a punch plate are heated. If the counter plate is provided with splicing protrusions, preferably, the splicing protrusions of the counter plate are heated.

The method may further comprise detaching the spliced portion of the two sheets of material from the array of splicing protrusions by lifting the spliced portion off the splicing protrusions.

Preferably, the method comprises arranging a detacher plate parallel to a punch plate and moving the detacher plate away from the punch plate parallel to a longitudinal extension of the splicing protrusions. By this, one or both sheets of material, in particular a spliced portion of the two sheets of material, are lifted off the splicing protrusions. Typically, a longitudinal extension of the splicing protrusions corresponds to a direction perpendicular to the plane of the punch plate, or in other words a longitudinal extension of the splicing protrusions is parallel to a moving direction of the punch plate and/or the counter plate for the splicing.

Preferably, the method comprises moving the detacher plate until a tip end of the splicing protrusions is reached. Typically, a tip end of the splicing protrusion corresponds to a longitudinal end of the splicing protrusion.

Preferably, the method comprises providing a detacher plate with an array of through holes, the array of through holes corresponding to an array of splicing protrusions.

Preferably, the method comprises detaching the spliced portion by means of springs.

Advantages and further features of the method have been described related to the splicing device.

The invention is defined in the claims. However, below there is provided a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein.

Example Ex1 : A splicing device comprising a punch plate and a counter plate, wherein the punch plate and the counter plate are relatively movable versus each other for splicing two sheets of material arrangeable in between the punch plate and the counter plate, wherein the punch plate comprises an array of splicing protrusions and the oppositely arranged counter plate comprises an array of splicing holes, wherein the array of splicing holes comprises a number of splicing holes and the array of splicing protrusions comprises a number of splicing protrusions, wherein the number of splicing holes is at least the same as the number of splicing protrusions, and wherein a position of the splicing protrusions in the array of splicing protrusions corresponds to a position of the splicing holes in the array of splicing holes. Example Ex2: The splicing device according to example Ex1 , wherein both the punch plate and the counter plate comprise an array of splicing protrusions and an array of splicing holes.

Example Ex3: The splicing device according to example Ex2, wherein splicing protrusions and splicing holes are arranged in an alternating manner on each of the punch plate and the counter plate.

Example Ex4: The splicing device according to any one of the preceding examples, wherein the punch plate and the counter plate are arranged parallel to each other.

Example Ex5: The splicing device according to any one of the preceding examples, wherein the punch plate and the counter plate have same dimensions in length and width.

Example Ex6: The splicing device according to any one of the preceding examples, wherein the splicing protrusions are splicing pins.

Example Ex7: The splicing device according to any one of the preceding examples, wherein the splicing protrusions have a pointed tip, a rounded tip or a tip provided with cutting edges.

Example Ex8: The splicing device according to any one of the preceding examples, wherein the splicing protrusions have a round, circular, triangular, polygonal, square or starshaped cross-section.

Example Ex9: The splicing device according to any one of the preceding examples, wherein the splicing holes have a circular, polygonal or triangular or square cross section.

Example Ex10: The splicing device according to any one of the preceding examples, wherein the splicing holes are drill holes.

Example Ex11 : The splicing device according to any one of the preceding examples, wherein a length of a splicing protrusion is in a range between 1 millimeter and 50 millimeter.

Example Ex12: The splicing device according to example Ex11, wherein the length of a splicing protrusion is in a range between 3 millimeter and 20 millimeter.

Example Ex13: The splicing device according to example Ex12, wherein the length of a splicing protrusion is in a range between 4 millimeter and 10 millimeter.

Example Ex14: The splicing device according to any one of the preceding examples, wherein a diameter of a splicing protrusion is in a range between 0.5 millimeter and 20 millimeter.

Example Ex15: The splicing device according to example Ex14, wherein the diameter of a splicing protrusion is in a range between 1 millimeter and 10 millimeter.

Example Ex16: The splicing device according to example Ex15, wherein the diameter of a splicing protrusion is in a range between 2 millimeter and 5 millimeter.

Example Ex17: The splicing device according to any one of the preceding examples, wherein a diameter of a splicing hole is in a range between 0.5 millimeter and 20 millimeter. Example Ex18: The splicing device according to example Ex17, wherein the diameter of a splicing hole is in a range between 1 millimeter and 10 millimeter.

Example Ex19: The splicing device according to example Ex18, wherein the diameter of a splicing hole is in a range between 2 millimeter and 5 millimeter.

Example Ex20: The splicing device according to any one of the preceding examples, wherein all splicing protrusions of an array of splicing protrusions have a same length and a same cross section area.

Example Ex21 : The splicing device according to any one of the preceding examples, wherein all splicing holes of an array of splicing holes have a same cross section area.

Example Ex22: The splicing device according to any one of the preceding examples, wherein all splicing holes have a same shape.

Example Ex23: The splicing device according to any one of the preceding examples, wherein a total number of splicing protrusions is between 2 and 250.

Example Ex24: The splicing device according to example Ex23, wherein the total number of splicing protrusions is between 10 and 200.

Example Ex25: The splicing device according to example Ex24, wherein the total number of splicing protrusions is between 20 and 100.

Example Ex26: The splicing device according to any one of the preceding examples, wherein the splicing protrusions comprise steel, polycarbonate, ceramic, thermoset materials such as Bakelite®, or silicone.

Example Ex27: The splicing device according to example Ex26, wherein the splicing protrusions are made of steel, polycarbonate, ceramic, thermoset materials such as Bakelite®, or silicone.

Example Ex28: The splicing device according to any one of examples Ex26 to Ex27, wherein the splicing protrusions are coated or thermochemically treated.

Example Ex29: The splicing device according to any one of the preceding examples, comprising a liquid supply for supplying a liquid to a sheet of material to be spliced.

Example Ex30: The splicing device according to example Ex29, wherein the liquid supply is adapted for supplying water or a liquid natural adhesive such as fish glue or egg white.

Example Ex31 : The splicing device according to any one of the preceding examples, comprising a heater for heating parts of at least one of the punch plate and the counter plate.

Example Ex32: The splicing device according to example Ex31 , wherein the heater is adapted to heat at least some of the splicing protrusions.

Example Ex33: The splicing device according to any one of the preceding examples, comprising a detacher for detaching sheet of material from the punch plate or from the counter plate. Example Ex34: The splicing device according to example Ex33, wherein the detacher is adapted to detach sheet of material from splicing protrusions.

Example Ex35: The splicing device according to any one of examples Ex33 to Ex34, wherein the detacher is provided at least at one of the punch plate and the counter plate.

Example Ex36: The splicing device according to example Ex35, wherein the detacher is provided at the punch plate and at the counter plate.

Example Ex37: The splicing device according to any one of examples Ex33 to Ex36, wherein the detacher comprises an elastically mounted detacher plate.

Example Ex38: The splicing device according to example Ex37, wherein the detacher plate is a spring biased detacher plate.

Example Ex39: The splicing device according to any one of examples Ex37 to Ex38, wherein a first elastically mounted detacher plate is connected to the punch plate and a second elastically mounted detacher plate is connected to the counter plate.

Example Ex40: The splicing device according to any one of examples Ex37 to Ex39, wherein the detacher plate comprises an array of through holes, the array of through holes corresponding to the array of splicing protrusions.

Example Ex41 : The splicing device according to any one of examples Ex37 to Ex40, wherein the detacher plate has a same dimension in length and width as the punch plate.

Example Ex42: A method for splicing sheets of material using an apparatus according to any one of the preceding claims, the method comprising: providing a first sheet of material from a first bobbin and providing a second sheet of material from a second bobbin; positioning the first sheet of material and the second sheet of material in a splicing location and overlapping the first sheet and the second sheet in the splicing location; splicing the first sheet of material and the second sheet of material in the splicing location by interpenetration of the first sheet of material and the second sheet of material by an array of splicing protrusions and a corresponding array of splicing holes, thereby moving the array of splicing protrusions and the array of splicing holes versus each other and pressing at least one of the two sheets of material into the array of splicing holes by the array of splicing protrusions, thereby forming a spliced portion of the first and second sheet of material.

Example Ex43: The method according to example Ex42, therein moving splicing protrusions and corresponding splicing holes along a same straight line for splicing the sheets of material.

Example Ex44: The method according to any one of examples Ex42 to Ex43, therein applying a pressure in a range between 0.1 bar and 30 bar to form the spliced portion. Example Ex45: The method according to any one of examples Ex42 to Ex44, therein moving a punch plate and a counter plate in an opposite direction and perpendicular to a splicing direction, thereby enhancing a strength of the spliced portion.

Example Ex46: The method according to any one of examples Ex42 to Ex45, therein keeping the sheets of materials stationary for splicing.

Example Ex47: The method according to any one of examples Ex42 to Ex46, wherein the first or the second sheet of material is any one of a cellulose containing sheet material, a tobacco material containing sheet, an aerosol-generating sheet material, a polylactic acid sheet or a metal sheet.

Example Ex48: The method according to example Ex47, wherein the first or the second sheet of material is any one of a paper sheet, a laminated paper sheet, a tobacco material containing cast leaf or a metal sheet.

Example Ex49: The method according to any one of examples Ex42 to Ex48, therein applying a liquid to at least one of the first and the second sheet of material before splicing the sheets of material.

Example Ex50: The method according to example Ex49, wherein the liquid is a natural liquid.

Example Ex51 : The method according to examples Ex49 or Ex50, wherein the liquid is water, egg white or fish glue.

Example Ex52: The method according to examples Ex49 or Ex51 , therein applying an amount of liquid up to 25 milliliter per squarecentimeter (ml/cm<2>).

Example Ex53: The method according to any one of examples Ex42 to Ex52, therein heating a punch plate or a counter plate.

Example Ex54: The method according to example Ex53, therein heating the punch plate or the counter plate to a temperature of up to 300 degree Celsius.

Example Ex55: The method according to any one of examples Ex53 to Ex54, therein heating the punch plate or the counter plate to a temperature between 50 degree Celsius and 200 degree Celsius.

Example Ex56: The method according to any one of examples Ex42 to Ex55, therein detaching the spliced portion from the array of splicing protrusions by lifting the spliced portion off the splicing protrusions.

Example Ex57: The method according to any one of examples Ex42 to Ex56, comprising arranging a detacher plate parallel to a punch plate and moving the detacher plate away from the punch plate parallel to a longitudinal extension of the splicing protrusions.

Example Ex58: The method according to example Ex57, therein moving the detacher plate until a tip end of the splicing protrusions is reached. Example Ex59: The method according to any one of examples Ex57 to Ex58, providing the detacher plate with an array of through holes, the array of through holes corresponding to the array of splicing protrusions.

Example Ex60: The method according to any one of examples Ex56 to Ex59, therein detaching the spliced portion by means of springs.

Examples will now be further described with reference to the figures in which:

Figure 1 shows a schematic lateral view of a system to splice a first sheet and a second sheet;

Figure 2 shows a lateral view of a detail of an embodiment of the system of Fig. 1 ;

Figure 3 shows a perspective view of a punch plate;

Figure 4 shows a longitudinal cross section of the punch plate of Fig. 3;

Figure 5 shows a top view of the punch plate of Fig. 3;

Figure 6 shows a perspective view of a counter plate;

Figure 7 shows a longitudinal cross section of the counter plate of Fig. 6;

Figure 8 shows a top view of the counter plate of Fig. 6;

Figure 9 shows a splicing device with detacher;

Figure 10 shows a perspective view of a detacher plate;

Figure 11 shows a longitudinal cross section of the detacher plate of Fig. 10;

Figure 12 shows top view of the detacher plate of Fig.10;

Figure 13 shows another embodiment of splicing device with detacher; and

Figure 14 shows two side views and a front view of splicing protrusions.

With reference to Fig. 1 and Fig. 2, an exemplary system to splice a first sheet and a second sheet of material is globally indicated with reference sign 1. The system 1 is described specifically adapted for the splicing of sheet material being tobacco material containing sheets, in particular homogenized tobacco material containing sheets such as cast leaf but also adapted for splicing fibrous paper sheets.

The system 1 comprises a first shaft 41 and a second shaft 31 , on which a first bobbin 40 and a second bobbin 30 are inserted. The first shaft 41 and second shaft 31 are rotatable around their respective axis. The first bobbin 40 supplies the first sheet of material 4 and the second bobbin 30 supplies the second sheet 3 of material. Preferably, the first sheet 4 and the second sheet 3 are homogenised tobacco sheets.

The system 1 further comprises a splicing device 2, schematically indicated with a rectangle in Fig. 1. The first sheet 4, which in Fig. 1 is the sheet in use, is supplied to the splicing device 2. The unwinding of the first sheet 4 from the first bobbin 40 and its supply to the splicing device 2 takes place via guide pulley 22. The first sheet 4 is transported towards the splicing device 2 and in the further processing stages along a transport direction which is indicated by the arrow 50. Downstream of the splicing device 2, the system 1 comprise an acceleration unit, for example in the form of two acceleration rollers (not shown in Fig. 1). The first sheet and second sheet being passed through the splicing device 2 may be accelerated or slowed down by the acceleration unit. The first sheet 4 or second sheet 3 may be continuously accelerated upon passing the acceleration unit in order to secure a continuous velocity of the sheet. Preferably, for the splicing process, the sheet is stopped by the acceleration unit. After a splicing process, the spliced sheet may be accelerated again to a process velocity.

Downstream of such an acceleration unit, the system 1 comprises a buffer system 6. The buffer system 6 comprises a plurality of rollers 7, such as a series of idler pulleys, where the first sheet 4 or the second sheet 3 is guided around and forms loops. Some of the idler pulleys 7 are arranged in a movable manner such as to enlarge or shorten a sheet loop in order to be able to further provide sheet material in a downstream direction, even when a supply from the splicing device 2 or from the first bobbin 40 or second bobbin 30 is interrupted or reduced.

Downstream of the buffer system 6 a pulling unit may be provided to pull the first sheet 4 or the second sheet 3 out of the buffer system 6 to pass the sheet preferably at a constant velocity to further downstream arranged sheet processing units (not visible).

Further elements and units may be included in the system 1, such as a crimper and a rod former (not shown in the drawings), both located downstream the buffer system 6.

Between the first shaft 41 and the splicing device 2, along the path taken by the first sheet 4 along the transport direction 50, at least a first sheet sensor 9 is located in the system 1. Sensor 9 is schematically depicted as a rectangle in Fig. 1. The sensor 9 may be a thickness sensor. The sensor 9 may be a width sensor. The sensor 9 may be a moisture sensor. The sensor 9 may be stickiness sensor. The sensor 9 may be a detector for the presence or absence of holes or tears in the first sheet 4.

Between the second shaft 31 and the splicing device 2, along the path taken by the second sheet 3, at least a second sheet sensor 10 is located in the system 1 , schematically depicted as a rectangle in Fig. 1. The sensor 10 may be a thickness sensor. The sensor 10 may be a width sensor. The sensor 10 may be a moisture sensor. The sensor 10 may be stickiness sensor. The sensor 10 may be a detector for the presence or absence of holes or tears in the second sheet 3. First sheet sensor 9 and second sheet sensor 10 may be the same type of sensor. First sheet sensor 9 and second sheet sensor 10 may measure the same integrity parameter of the first sheet 4 and second sheet 3, respectively.

System 1 further includes a control unit 100. Control unit 100 is connected to first sheet sensor 9, second sheet sensor 10 and the splicing device 2. Preferably, control unit 100 is also connected to a bobbin holder (not shown), buffer system 6, and acceleration unit to command the same. Some of the connections are visible in the figures as dotted lines. Not all connections are depicted for clarity of the figures. In Fig. 2, the splicing device 2 is shown in more detail. Some parts of the system 1 , such as the optional buffer system 6, are not shown in Fig. 2. Splicing device 2 includes a cutting knife 20 to cut the first sheet 4 or the second sheet 3 or both. The splicing device 2 further includes a dispensing unit 23 adapted to dispense water onto the first sheet 4 or second sheet 3. The splicing device 2 also includes a splicer head 24 comprising a punch plate 240 and an oppositely arranged counter plate 250 to perform the actual splicing of the first sheet 4 and the second sheet 3. The splicing device 2 preferably also comprises a heater integrated into the splicer head 24 for heating either the punch plate 240 or counter plate 241 or both. A further heating unit 25, for example a hot air source or a heat radiating source, is arranged downstream adjacent the splicer head 24.

The functioning of the system 1 is as follow.

In Fig. 1 and Fig. 2 the first tobacco sheet 4, unwound from the first bobbin 40, is in use and is passing in a substantially straight direction through the splicing device 2. No processing takes place in the splicing device. The first sheet 4 is then buffered for a given length in the buffer system 6 and it is further transported to sheet processing units arranged further downstream (not shown). Such processing units may for example be a crimping unit or a rod forming unit.

While travelling towards the splicing device 2, the sensor 9 evaluates one or more integrity parameters of the first sheet 4, at a given frequency, checking the surface of the first sheet while the first sheet 4 travels along the transport direction 50. Signals representative of the integrity parameters are sent to the control unit 100 where they are elaborated, for example compared to a threshold.

In this situation, the buffer system 6 is buffering a length of the first sheet 4, when the rollers 7 are distanced at the maximum distance one from the other. This distance can be along a horizontal direction as shown in Fig. 1 but also in a vertical direction.

For example, the sensor 9 is a thickness sensor. The sensor 9 measures the thickness of the first sheet 4 at a given frequency. The thickness is then compared by the control unit 100 with a threshold. For example, it is found that the results are not within the acceptable range. This is considered to be a non-acceptable defect of the first sheet 4 and the control unit 100 commands the splicing device 2 to start the splicing. Typically, the control unit 100 receives a signal from a diameter sensor (not shown) signalling that the first bobbin is going to be depleted soon in order to start the splicing process.

Upon start of the splicing, the second sheet 3 from the second bobbin 30 is guided via guide pulley 22 and supplied to the splicing device 2 (in Fig. 2, the second sheet 3 is supplied from below first sheet 4 in use). Both sheets 3,4 are arranged on top of each other and aligned on a support surface 21 of the splicing device 2. They are then cut by cutting knife 20. The first sheet 4 and second sheet 3 travelling along the transport direction 50 are cut along a same or at different cut lines. Cut lines may be congruent when the first sheet and second sheet are overlapping. By the cut lines, a clearly defined end portion of the first sheet 4, a waste portion of the first sheet and a clearly defined waste portion of the second sheet 3 and a head portion of the second sheet 3 are defined.

Waste portions may be removed after cutting the sheets 3,4. While the cutting does not necessarily have to be performed with aligned sheets, the splicing process does. The sheets 4, 3 that have been cut are positioned such that the end portion of the first sheet 4 and the head portion of the second sheet 3 overlie each other and form an overlapping portion. In the overlapping portions, two surfaces belonging to the first sheet and second sheet, respectively, are in contact with each other. Water is dispensed onto the lower lying sheet 3, preferably in the overlapping portion only by the dispensing unit 23. By a thin water layer applied to one sheet only, such as the second sheet 3, the water may soften the material of the sheets 3,4 at least in the overlapping portion to support a splicing of the sheets 3,4. However, the amount of water is small enough to not disintegrate the sheets. Alternatively, a liquid adhesive, in particular a liquid natural glue may be applied to one or both sheets.

The so overlying and wetted sheets 3,4 are then guided through the splicing head 24.

The sheets are spliced upon passing between punch plate 240 and counter plate 241 , which securely splice the two sheets 3,4 to each other. For the splicing, the two sheets 4,3, are kept stationary. The pressure direction applied by the splicing head 24 and moving direction of the punch plate 240 and counter plate 241 is indicated by arrows 51. A short but firm connection is formed upon moving punch plate 240 and counter plate 241 toward each other. For the splicing, only one plate or both plates 240,241 may be moved.

When the splicing has taken place, the punch plate 240 and the counter plate 241 are moved away from each other and the spliced sheet may continue to move into the transport direction 50. A detacher (not shown in Fig. 2) may be provided to support a release of a spliced portion from the punch plate 240 and optionally also of the counter plate 241.

A heating unit 25 is provided that heats the spliced sheets. By the heat, the connection is quickly dried such that the spliced tobacco sheet may continue to be provided to further downstream arranged processing units.

While the splicing takes place, due to the fact that the first sheet needs to be stopped in order to perform the splicing, the first sheet 4 buffered in the buffer system 6 is used in the further processing steps. During the splicing therefore, the first sheet 4 in the buffer system 6 is used and the rollers 7 get closer to each other reaching a minimum distance, as depicted in Fig. 1.

When the splicing is commanded, the second tobacco sheet 3 from the second bobbin 30 is guided into the splicing device 2. After cutting in the splicing device, the then cut off first tobacco sheet 4 may be removed together with the first bobbin 40 from the first shaft 41. It may be replaced by a new bobbin. As soon as the second bobbin 30 comes to an end, the process may be started again.

By this process, a new bobbin is provided and prepared for the tobacco sheet on the new bobbin to being spliced with the tobacco sheet in use, while the tobacco sheet is continuously provided to the tobacco processing line.

In Figs. 3 to 5 a punch plate 240 provided with an array of splicing protrusions in the form of splicing pins 70 is shown.

The punch plate 240 is a rectangular plate having a length 52, a width 53 and a thickness 54. The length 52 of the plate is several times larger than its width 53. The punch plate 240 in collaboration with a counter plate 241 as described in Figs. 6 to 8 below, is capable to generate a small splicing area along a length of a sheet of material to be spliced and over an entire width or a major part of a width of a sheet of material to be spliced.

The splicing pins 70 are circular tubular pins with a pointed tip. The splicing pins 70 are arranged in three equally distant rows arranged along the length 52 of the punch plate 240. Splicing pins 70 are arranged equidistantly in a row at a pin distance 73. Pins 70 in neighbouring rows are displaced with respect to the length of the punch plate.

All pins 70 in the embodiment shown in Figs. 3 to 5 have a same shape and a same size, in particular all pins 70 on the punch plate 240 have a same diameter 76 and same height 71.

The punch plate 240 comprises a through hole 75 at each of its longitudinal ends. The through holes 75 serve as attachments for a detacher plate (see below).

Exemplary values of a punch plate 240 are: length 52: 255mm, width 53: 20mm and thickness 54: 10mm; diameter of through holes 75: 6 mm;

Exemplary values for splicing pins 70 are: height 71 : 5 mm, diameter (or extension of cross section) 3 mm;

Exemplary value of a distance 72 between 1 ^st and 3 ^rd row of pins 70 (or lateral extension of array of splicing pins 70): 10 mm;

Exemplary value of a distance 73 between neighbouring pins 70 in a row: 10 mm;

A counter plate 241 forming a splicing head with the punch plate 240 as shown in Figs. 3 to 5 is shown in Figs. 6 to 8. The counter plate 241 is a rectangular plate having a length 62, a width 63 and a thickness 64. The length 62 of the plate is several times larger than its width 63.

The counter plate 241 is provided with an array of splicing holes 80 in the form of through holes as may be best seen in Fig. 7.

The splicing holes 80 are circular drillholes. The splicing holes 80 are arranged in three equally distant rows arranged along the length 62 of the counter plate 241. Splicing holes 80 are arranged equidistantly in a row at a hole distance 83. Splicing holes 80 in neighbouring rows are displaced with respect to the length 62 of the counter plate 241. All splicing holes 80 in the embodiment shown in Figs. 6 to 8 have a same shape and a same size, in particular all splicing holes 80 in the counter plate 241 are circular holes and have a same diameter 86.

Exemplary values of a counter plate 241 are: length 52: 255mm, width 53: 20mm and thickness 54: 10mm; diameter (or extension of cross sectional) of splicing holes 3 mm;

Exemplary value of a distance 82 between 1 ^st and 3 ^rd row of splicing holes 80 (or lateral extension of array of splicing holes 80): 10 mm;

Exemplary value of a distance 83 between neighbouring splicing holes 80 in a row: 10 mm;

In the embodiments shown in Figs 3 to 8, the punch plate 240 and counter plate 241 have a same length 52,62, width 53,63 and thickness 54,64. These dimensions may also be different, as long as the array of splicing pins 70 in the punch plate 240 have a correspondingly arranged array of splicing holes 80 in the counter plate 241.

Fig. 9 shows a splicing head with lower punch plate 240 and upper counter plate 241 , for example as described in Figs. 3 to 8.

Punch plate 240 and counter plate 241 are arranged opposite and distanced from each other in the open position as shown in Fig. 9.

Splicing holes 80 are only provided in the counter plate 241. Splicing pins 70 are only provided in the punch plate 240.

A detacher plate 90 is arranged parallel to the punch plate 240. The detacher plate 90 is connected to the punch plate via springs 91. A coil spring 91 each is arranged at opposite ends of the counter plate 90 and punch plate 240. Preferably, the springs 91 are attached to the punch plate 240 via through holes 75 (see Fig. 3 above). When a splicing action is to be performed, counter plate 241 and punch plate 240 are moved towards each other. The detacher plate 90 is pushed towards the punch plate 240 and the springs 91 are compressed. When the splicing has been performed, punch plate 240 and counter plate 241 are moved away from each other to the open position again, for example upon release of a clamp. The springs 91 expand and push the detacher plate 90 away from the punch plate 240. Thereby, a spliced sheet (not shown in Fig. 9) possibly not detached from either part of the splicing head upon opening of the same, is now detached from the punch plate 240, in particular detached from the splicing pins 70 by the detacher plate 90. Preferably, a movement of the detacher plate 90 away from the punch plate 240 equals to a length of the splicing pins 70. This guarantees a complete detaching of a spliced sheet of material from the splicing pins 70.

Figs. 10 to 12 show a detacher plate 90 as may be used in the embodiment of a splicing head as for example shown in Fig. 9 with punch plate as shown and described in Fig. 3 to 5.

The detacher plate 90 is a rectangular plate having a length 92, a width 93 and a thickness 94. The length 92 of the plate is several times larger than its width 93. The detacher plate 90 is provided with an array of detacher holes 95 in the form of through holes, for example drill holes.

The detacher holes 95 are circular holes. The detacher holes 95 are arranged in a same array as the splicing pins 70 of the corresponding punch plate 240 shown in Figs. 3 to 5. The detacher holes 95 are arranged in three equally distant rows arranged along the length 92 of the detacher plate 90. Detacher holes 95 are arranged equidistantly in a row at a hole distance 96. Detacher holes 95 in neighbouring rows are displaced with respect to the length of the detacher plate 90.

All detacher holes 95 in the embodiment shown in Figs. 10 to 12 have a same shape and a same size, in particular all detacher holes 95 in the detacher plate 90 are circular holes and have a same diameter 97.

A spring 91, for example a coils spring, is provided at both longitudinal ends of the detacher plate 90.

Exemplary values of a detacher plate 90 are: length 92: 255mm, width 93: 20mm and thickness 94: 2mm; diameter 97 of detacher holes 95: 3 mm;

Exemplary value of a distance 98 between 1 ^st and 3 ^rd row of detacher holes 95 (or lateral extension of array of detacher holes 95): 10 mm;

Exemplary value of a distance 96 between neighbouring detacher holes 95 in a row: 10 mm;

Exemplary value of a diameter of a spring 91 : 6 mm; height 99 of a spring 98 in a released position 10 mm.

In the embodiment shown in Figs. 10 to 12, the detacher plate 90 has a same length 92 and width 93 as the punch plate 240. These dimensions may also be different, as long as the array of detacher holes 95 corresponds in its position to the correspondingly arranged array of splicing pins 70 in the punch plate 240.

In Fig. 13, a punch plate 240 and a counter plate 241 are both embodied as male and female part at the same time. Thus, punch plate 240 and counter plate 241 are both provided with splicing pins 70 and splicing holes 80.

The splicing head is shown in its open position and a first sheet of material 3 and a second sheet of material 4 are arranged in between the punch plate 240 and the counter plate 241.

Each of the splicing pins 70 of the counter plate 241 has a corresponding splicing hole 80 in the punch plate 240 and vice versa.

In the example shown in Fig. 13, slicing pins 70 and splicing holes 80 are arranged in alternating manner in rows along the length 52,62 of the punch plate 240 and counter plate 241 , respectively. A detacher plate 90 is assigned to each of the counter plate 241 and the punch plate 240. The detacher plates 90 are provided each with an array of detacher holes 95 corresponding to the combination of the splicing holes 80 in the counter plate 241 and the splicing holes 80 punch plate 240, or rather detacher holes 80 correposnding to the array of splicing pins 70 in of the punch plate 240 as well as of the counter plate 241.

A spring 91 each is arranged between the longitudinal ends of the counter plate 241 and corresponding detacher plate 90.

A spring 91 each is arranged between the longitudinal ends of the punch plate 240 and corresponding detacher plate 90.

Indicated in Fig. 13 with arrows 55 is a longitudinal movement of counter plate 240 and punch plate 240 in opposite directions in the length directions of counter plate 240 and punch plate 240. Such a slight transverse movement relative to the (vertical) splicing direction may reinforce the splicing.

In Fig. 14 a variety of shapes of splicing pins 770-775 is shown. Vertical rows 77, 78, 79 show a splicing pin in the respective longitudinal side view 77 (when seen from the length side of a punch plate 240), front view (78 view onto a tip of a pin) and width side view 79 (when seen from a width of a punch plate 240; view onto side of pin 79 is rotated by 90 degree compared to side view 77).

Examples show pins with pointed tips 770,772-774, rounded tips 771 or flat tips 775.

Pins are shown with triangular 770, circular 771,772, 775, and square cross sections 773 at a pin’s base.

Some pins are provided with cutting edges 770,772,773,774, for example four cutting edges.

Depending on the type of sheet material to be spliced and the desired splice to be achieved, for example a weak or strong splice, a splice by material deformation or rather by perforations, a pin shape and pin size may be chosen.

Different forms of pins may be provided for a splice of two sheet materials. In particular, different forms of splicing pins may be provided on a punch plate 240 and a corresponding counter plate 241. In particular, different forms of splicing pins may be provided to form an array of splicing pins on a punch plate 240 or on a counter plate, respectively.

For the purpose of the present description and of the appended claims, except where otherwise indicated, all numbers expressing amounts, quantities, percentages, and so forth, are to be understood as being modified in all instances by the term "about". Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein. In this context, therefore, a number A is understood as A ± 10% of A. Within this context, a number A may be considered to include numerical values that are within general standard error for the measurement of the property that the number A modifies. The number A, in some instances as used in the appended claims, may deviate by the percentages enumerated above provided that the amount by which A deviates does not materially affect the basic and novel characteristic(s) of the claimed invention. Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein.