TECHNICAL FIELD

The present invention concerns size reduction of a central bore of a roll. The roll may be a paper roll or similar sheet products supplied in large rolls. Such a roll comprises an inner core upon which web material such as paper, film and the like are wound . More precisely the invention concerns an adapter for making possible larger diameter cores to be mounted on winding machines and other machines having smaller diameter spindles or chucks. Especially the invention concerns an adapter for application inside the core by which adapter the inside diameter of the roll is reduced.

BACKGROUND OF THE INVENTION

Within paper industries sheet products are provided on large heavy and bulky rolls having an inner core. The core on which the sheet material is wound has a suitable inner diameter to fit the machine on which the roll is mounted . Heavy grades of material require winding upon a core having a large internal diameter. However, these rolls must be usable on available printing or processing machinery having a smaller diameter capability. Thus it is desirable to adapt to a small diameter even before the material is wound upon the core.

Long cylindrical cores made of plastic or spirally wound paperboard are commonly used to wind large quantities of web material such as, for example, paper or film into rolls for storage and transport. Some cores have an inner diameter that is larger than those of other cores.

Common such inner diameter is 150 mm, which correspond to six inches, and 76 mm, corresponding to 3 inches. It is desirable to mount rolls with cores of both large and small inner diameter on existing winding machines. One such machine is double drum winders that have spindles or chucks configured to accept cores with smaller inner diameter only. It is thus known to install core adapters that have central bores that can be mounted on the smaller inner diameter spindles or core chucks of winding or other machine. Traditional core adapters take many forms such as, for instance, leaf adapters with leafs that can expand to lock the adapter in the end of the core, rubber air or pneumatic adapters that are inserted in the core ends and inflated to lock them in place, and others. Core adapters made of wound paper in the form of one or multiple concentrically arranged components are also known. Several known devices and methods are used in the industry to adapt the inside diameter to a usable size. However, most of these known methods and devices have drawbacks and are limited in scope.

From US 2006/0196990 (Wallace) a paper roll adapter is previously known. The adapter is capable of handling a variety of sizes for both outside and inside diameter cores. It is economical to manufacture and is recyclable with other waste generated by the printing process.

The adapter includes an outer tube and an inner tube with the annulus filled with a polymer based adhesive such as a thermoplastic adhesive material that becomes solid at normal environmental temperatures or a thermosetting resin. The outer tube is perforated and the inner tube is counter-drilled . This arrangement of holes and counter-drills allows the adhesive to enter and form sections that increase the strength of the device. From US 2012/0111990 (Kervinen et al) a self centering adapter is previously known. The object of the adapter is to ensure a precisely centered smaller central opening and ensure precise concentricity of the smaller opening of the adapter with the larger opening of the core.

The adapter is made of wound paper and includes a generally

cylindrical or annular body having walls that surround a central bore sized to receive a spindle or chuck. The body has an outer diameter sized to fit into the end of a core having a larger inner diameter and the central bore is sized to receive a spindle or chuck having a smaller inner diameter. An axially extending discontinuity in the form of a slit is formed and extends completely along the length of the body and also extends completely through the wall of the body from the central bore to the outer surface of the body. In one embodiment, a series of attachment holes is drilled either at an angle through the end of the adapter or through the walls of the core at its ends. Attachment holes also need not be drilled.

To install the core adapter of this embodiment in a larger inner diameter core, the adapter is slid into the ends of a core and attached with screws or other fasteners. In the embodiment with attachment holes drilled through the end of the adapter, screws may be inserted through the attachment holes and treaded into the core. In the embodiment with attachment holes formed in the core, screws may be inserted through the attachment holes and threaded into the body of the adapter. When no attachment holes are present, screws may simply be threaded through the core and into the adapter or vice versa. In either case, the screws preferably are installed in a

predetermined sequence that causes the adapter to expand

progressively outwardly facilitated by a widening of the axially extending slit in the adapter. When all the screws are installed, the adapter is lodged tightly in the end of the core, the slit is widened from its normal or rest width, and the central bore of the core adapter is precisely centered within the core.

SUMMARY OF THE INVENTION

A primary object of the present invention is to seek ways to improve the mounting of a roll on a spindle, where the inner diameter of the roll core is larger than the outer diameter of the spind le.

This object is achieved accord ing to the invention by an adapter characterized by the features in the independent claim 1 or by a method characterized by the steps in the independent claim 5.

Preferred embod iments are described in the dependent claims.

According to the invention the adapter comprises two interacting cylindrical parts. The two parts are coaxially arranged inside the core of the roll. A first adapter part comprises a central body having a cylindrical inner surface and an outer conical surface forming a wedge- shaped cross section. The inner surface is defining a bore arranged to fit the spind le on which the roll is to be mounted . A second adapter part comprises a coaxial outer body having an outer cylindrical surface and an inner conical surface forming a wedge-shaped long itud inal cross section. The outer cylindrical surface is arranged to fit the inner surface of the core. The inner surface of the second adapter part is arranged to fit and interact with the wedge-shaped outer surface of the first adapter part. The first and second adapter parts thus have a common conical surface. When pressed against each other inside the core the two wedge-shaped surfaces interact in a concentric manner. Further pressing makes the outer adapter part expand and thus interlock firmly with the inside of the core. When in position the inner diameter of the core is replaced by the adapter bore. In an embodiment of the invention the adapter parts have the same length as the core. In an embodiment the common conical surface extend along the whole length of the adapter. In one embodiment a tool is used to press the two adapter parts together. The tool

comprises two gripping elements and a common threaded rod passing through the bore. In an embodiment the gripping means comprises two gable plates. Thus when turning the rod the two gripping elements are narrowing each other and pressing the two adapter parts to interact. There is no need for any hydraulic equipment, compressed air or external presses.

In an embodiment of the invention two adapters are used one at each end of the core. The two adapter parts and the tool are loosely assembled before being stuck into one end of the core. In this embodiment the inner gripping means of the tool is replaced by an umbrella construction having a plurality of hocks or claws grabbing the inner side of the first adapter part. By turning the rod the two adapter part are pressed towards each other. The outer conical surface of the first adapter part thus will excite a radial force on the second part that will expand and interact with the core.

By pressing two conical adapter parts together the concentricity is confirmed which will avoid out-of-balances-forces. High contact forces are achieved by the wedge forces between adapter and core for sufficient torque transmission. Application of the adapter in the core is optional before winding or after winding . With the corresponding tool the application by hand is quick and easy. Since the extension of the gable plates are smaller than the core there will be no deformations of the wound paper. In a first aspect of the invention the object is achieved by an adapter for reducing the inner diameter of a core of a roll comprising a first part and a second part arranged coaxially inside the core. The first adapter part comprises an inner bore for receiving a spindle of a machine. The second part comprises an outer cylindrical surface for fitting on the inside of the core. The first and second adapter part comprises a common conical surface along which the first and second adapter part is guided when pressed against each other. In an

embodiment the bore comprises a diameter of 76 mm. In an

embodiment the outer surface of the second adapter part comprises 150 mm. In an embodiment the common surface comprises a stepped shape.

In a second aspect of the invention the objects are achieved by a method for reducing the inner diameter of a core of a roll using an adapter having a first adapter part and a second adapter part, wherein the first adapter part is formed to comprise an inner bore for receiving a spindle of a machine, the second part is formed to comprise an outer cylindrical surface for fitting on the inside of the core, the first and second adapter part are inserted from opposite sides into the core, and the first and second adapter part are axially pressed against each other guided by a common conical surface such that the second adapter part expands and make a firm joint with the core. In an embodiment the pressing step is achieved by using a tool comprising a first gable plate abutting the first adapter part, a second gable plate abutting the second adapter part, and a threaded rod by which rotation the first and second adapter parts are pressed against each other. In an

embodiment the surfaces are covered with glue.

BRIEF DESCRIPTION OF THE DRAWINGS Other features and advantages of the present invention will become more apparent to a person skilled in the art from the following detailed description in conjunction with the appended drawings in which :

Fig 1 is a plan and a cross section of an adapter according to the invention,

Fig 2 is a cross section of an adapter being mounted with a hand operated tool, and

Fig 3 is a cross section of adapter being mounted at one end of a core.

DESCRIPTION OF PREFERRED EMBODIMENTS

An adapter according to the invention is shown in fig 1. The adapter comprises a first part 1 and second part 2 coaxially arranged in a cylindrical core 3 of a roll . The first part 1 has an inner cylindrical bore 4 defined by an inner cylind rical surface 5 and an outer conical surface 6. The second part has an outer cylindrical surface 7 and an inner conical surface 8. The inner cylindrical bore 4 defined by the inner cylind rical surface 5 is arranged to receive a not shown spindle of a machine to which the roll is to be mounted . The outer cylind rical surface 7 of the second adapter part is adapted to interlock with the inner surface of the core 3. The outer conical surface 6 of the first adapter part and the inner conical surface 8 of the second adapter part are aligned with each other along a common conical surface.

In a longitud inal cross section of the adapter the first and second adapter part form two interacting symmetrical wedges. Thus when pressed together the wedge forces will make the second adapter part expanding and thus making a firm joint with the core. To achieve a sufficient expansion the second adapter part is made of an elastic or plastic material. In an embodiment the material comprises a board material. In an embodiment the material is wound paper. In an embodiment the material includes cellulose or wood pulp.

When applying the adapter to a core the first and second adapter part is inserted into the inside of the core from opposite sides. As the parts are pressed together the central bore of the first adapter part will be aligned coaxial with the core axle. In an embodiment two adapters are mounted one at each end of a core. In an embodiment the adapter is dispersible and may thus be reused. In an embodiment glue is used between the surfaces thus working as a lubricant when mounting and making an indispensible adapter when the glue has cured. In any case the adapter is recyclable.

When mounting the adapter any of the two adapter parts may be inserted first into to core. In fig 2 the first adapter part is inserted into the core. A tool comprising a threaded rod 9 and first 10 and second 11 gripping means is inserted through the bore of the core. In the embodiment shown the gripping means comprise gable plates. The second adapter part is then inserted from the opposite side. The tool plates are preferably circular and in the embodiment shown the first plate somewhat bigger than the second plate. The two plates may however have the same size. Preferably the size of the plates should be the same as the core in order to abut the core. However the plates should not be greater than the core in order to not damage the paper wound on the core. As the tool rod is screwed the plates presses the two adapter parts together. When pressed together the wedge forces will make the second adapter part expand and thus interact firmly with the inner surface of the core. A joint with high strength and a

cylindrical bore concentric with the core will be formed . The tool is remover after assembly. When using two adapters, one at each end of the core, the adapter parts and the tool may be loosely assembled in advance. In fig 3 the package of adapter parts and the tool is inserted into the core. The second gripping means 11 comprises in this embodiment a plurality of hooks including claws 12 on moveable links 13 and a joint 14 hold ing the links. The assembled adapter parts are stuck into the core. The first gable plate 10 rests on the second adapter part 2 and on the core 3. The claws 12 of the tool are resiliently forced to grab onto the inner part of the first adapter part. By turning the threaded rod the claws will put the first adapter part into the second adapter part. Since the two adapter parts have a common conical surface they will approach each other in concentric manner. Thus when fully assembled the adapter will replace the core d iameter by the bore 4.

Reel weight and core length will vary from case to case. For instance the core length may vary from 20 cm to 3 m. Web speed of printing presses may be up to 17 m/s. The adapter may be used with cores and spind les of d ifferent diameters. For instance the bore may be 45 mm in a core of 100 mm diameter. For instance the bore may be 125 mm in a core of 200 mm diameter. Thus the bore may vary between 40 to 125 mm and the wall thickness may vary between 25 to 40 mm. The length of the adapter should be adjusted according to the chuck length. Commonly used chucks in the market have a length between 100 mm and 280 mm.

Although favorable the scope of the invention must not be limited by the embodiments presented but contain also embodiments obvious to a person skilled in the art. For instance a plurality of adapters may be arranged inside the core. Likewise the common conical surface of the two adapter parts may be arranged in steps or in a prog ressive shape. The tool may comprise any mechanical device capable of pulling the gripping means together. The tool may comprise a lever construction. Also the second gripping means may comprise any construction capable of being folded together and drawn back through the bore.