DESCRIPTION

The present invention relates to a device for conveying protective packagings made of air cushions.

It is known that such packaging material is substantially made by a series of cushions filled with air, which are joined together by transverse welding lines that in general are separable by tearing along pre-cut lines suitably provided to allow the use of a variable number of cushions depending on the needs. Each cushion is formed by a tubular chamber obtained by advancing two films of plastic material along a predetermined direction and providing the side welding of the two films in the longitudinal direction and the front and rear transverse welding at predetermined intervals. In phase with the said welding air is insufflated in the tubular chambers. Alternatively, it can be used a single-fold film, that is already folded on one side and, consequently, does not require welding, so that the welds interesting each cushion are three in number. For this reason, in general, a machine for the production of air cushions forming a protective packaging material comprises: means for supplying two films of plastic material or a single-fold film along a predetermined longitudinal feeding direction, means for blowing air through the two films or the two pages of the folded film, means to realize longitudinal welds on the two films or on the free edges of the folded film so as to delimit laterally a succession of tubular chambers in which air is fed, means for transversely welding the tubular chambers forming a succession of cushions with air contained within the four or three lines of longitudinal and transverse welding, and means for providing pre- incised tearing lines on the cushions in correspondence with two transverse welds.

The finished product is conveyed to a collection point by means of a pneumatic conveyor consisting of a duct in which is maintained an air stream dragging the finished product along the same conduit. Such a conveying system the construction of expensive pipes made of metal or plastic material and the adoption of appropriate systems for blowing air and maintenance of the pneumatic flow into the conveying conduits. All this is incompatible with the current production requirements, both from the economic and the plant design points of view.

EP1632765, EP540148, US2006/010835 and EP1563987 disclose devices for conveying packaging cushions comprising motorized dragging elements that are in contact with the same cushions and guide them along a conveying direction. The devices disclosed in

EP1632765, EP540148, US2006/010835 and EP1563987 require means for controlling the position of the dragging elements in relation to the cushions. The control means involve higher production costs and require periodical maintenance.

The main aim of the present invention is to provide a device for conveying packaging air cushions allowing conveying of differently sized packaging air cushions without requiring control means for controlling the position of the dragging elements in relation to the air cushions.

This result has been achieved by adopting the idea of making a device having the features indicated in claim 1. Other features of the present invention are the subject of the dependent claims. Thanks to the present invention, it is possible to provide a system for conveying the finished product that is simpler, cheaper and more flexible. In addition, a device in accordance with the present invention can be easily installed in correspondence of the machines destined to produce protective packaging air cushions of the type available on the market without any obligation to change their working cycle .

These and other advantages and features of the present invention will be best understood by anyone skilled in the art thanks to the following description and the accompanying drawings, given by way of illustration, in which:

- Fig.lA is a schematic side view with parts in transparency of a conveying device according to the present invention placed in correspondence of a machine for producing air cushions in a first possible use condition;

- Fig. IB is an enlarged detail of Fig.lA;

- Fig.lC is a schematic top plan view of the machine shown in Fig.lA

- Fig.2 schematically represents the finished product exiting the machine;

- Fig.3 schematically represents a single-fold plastic film that can be used for feeding a machine producing packaging air cushions;

- Fig.4 is an enlarged detail of the conveying device shown in Fig.lA;

- Fig.5 is a schematic side view with parts in transparency of a conveying device according to the present invention placed in correspondence of a machine for producing air cushions in a second possible use condition.

Reduced to its basic structure and with reference to the attached drawings, a machine that can be equipped with a device according to the present invention is of the type comprising:

- means for supplying two films or a single-fold film of plastic material along a predetermined longitudinal feeding direction;

means for blowing air through the two films or the two pages of the folded film;

means to realize longitudinal welds on the two films or on the free edges of the folded film so as to delimit laterally a succession of tubular chambers in which air is fed;

- means for transversely welding the tubular chambers forming a succession of cushions with air contained within the four or three lines of longitudinal and transverse welding;

means for providing pre-incised tearing lines on the cushions in correspondence with two consecutive transverse welds.

According to the example shown in the drawings, the machine makes use of a single-fold or center-folded film (M) , and therefore it is provided with means for welding the film in the longitudinal direction on one side (L) only: the other side, being constituted by the fold (P) of the film, does not require welding. The folded film (M) is unwound from a reel (BM) positioned on the top of the housing (100) of the machine .

Said single longitudinal welding can be executed, for example, by a pair of welding bars (1,2) suitably positioned in a corresponding operating station (SL) along the path of the film (M) upstream of the station (ST) in which the transverse seals or welds are executed. The side (L) of the film (M) passes between the bars (1,2) while the same film advances toward the transverse welding or sealing station (ST). In Fig.2 the longitudinal welding in correspondence of each cushion (6) is marked by the reference "61".

The transverse seals may be performed, for example, by means of two bars (3,4) placed transversely to the direction (A) along which the film advances, downstream with respect to the longitudinal sealing bars (1,2). A transverse welding bar (3) is fixed, positioned above the feed path of the film (M) , while the other (4a, 4b) is movable to and from the fixed bar (3): during welding, the movable lower bar (4a, 4b) is approached to the fixed upper bar and, when welding is performed, i.e. after a predetermined time, it is moved back to its original position, as indicated by the double arrow "F" in Fig IB. The mobile transverse welding bar is in two parts (4a, 4b) disposed side by side and spaced apart to allow to perform simultaneously two lines of transverse sealing (62) that are consecutive and spaced by a predetermined amount and to enable a blade (5) to pass between them in order to perform a pre-incision line (620) which allows to manually separate the individual air cushions (6) from each other.

In a preliminary step of preparing the start of the production cycle of the machine, the lower side (1M) of the film (M) is placed below the nozzle (8) blowing air, while the top side (2M) is located above the latter, so that the nozzle (8) is between the two sides (1M, 2M) of the film (M) . Such positioning of the nozzle (8) does not hinder the advancement (A) of the film (M) .

In phase with the execution of the longitudinal and transverse sealings, air is blown into the tubular chambers delimited by the longitudinal and transverse sealings on the film (M) .

The product exiting the station (ST) where the transverse seals are made is a series of cushions that are delimited laterally by the fold (P) and the longitudinal seal (L) and, on the front and . rear sides, by the transverse seals (62) with the pre-cut (620) resulting between the rear transverse seal of a cushion (6) and the front transverse seal of the consecutive cushion (6).

The longitudinal and the transverse weldings for delimiting the chambers into which the air is blown can be executed in any way known to the technicians of this field and therefore are not disclosed in further details.

With reference to the example shown in Fig.lA, the series (60) of air cushions (6) exiting from the transverse sealing station (ST) is conveyed inside the housing (100), reversing their advancing direction, and exits from the rear side of the machine. According to this example, the housing (100) has a section (101) through which the product (60) is re-entered inside the machine, said product reentering section (101) being at a lower level than the front section (102) from which the product passes after having treated in the transverse welding station (ST) . The finished product (60) fed back into the machine is free from any further treatment and, running along a space (103) inside the housing (100), comes out from the rear side of the latter and passes into a conveyor (7) that guides it towards a collecting station (R) placed at a predetermined distance from the machine, or in a collection point that does not obstruct nor limit the operator's movements in the machine area.

in correspondence of the said front section (102) there is mounted a plate (103) for supporting and guiding the finished product, inclined downwards, below which there is mounted a motorized roller

(104) with radial appendixes which protrude- through a slot of the same plate (103) and acts on the product by pushing it forward. The reference (105) indicates a protective plate placed in front of the section

(102) crossed by the product (60) exiting the transverse sealing station (ST) , said protective plate preventing the access to said station. In this way, the operator's hands cannot reach the transverse sealing bars. To allow access to the front parts of the machine during maintenance or repair, the plate

(105) can be removed.

With reference to the example shown in Fig.5, the finished product (60) comes out from the front side of the machine, i.e. from the same side of said section (102) .

Advantageously, in accordance with the present invention, the said conveyor (7) is constituted by two superposed pairs of rollers (71a, 71b) with horizontal axes, with a plurality of ring-closed belts (70a, 70b) on each pair of rollers and in which a roller (71a, 71b) of each pair is motorized.

The conveyor (7) has an input side (I) and an exit side (U) for the finished product (60) .

In practice, the set of rollers (71a, 71b) and of the belts (70a, 70b) constitutes a mechanism for mechanically dragging the finished product (60) along a conveying direction.

This mechanism forces the finished product (60) to follow a predetermined path along the conveying direction (T) set by the belts (70a, 70b) that are wound on the rollers (71a, 71b) . The belts (70a, 70b) delimit the top and bottom parts of the path that the finished product (60) follows along the direction (T) .

In the example shown in Fig.4, each pair of rollers (71a, 71b) is mounted on a corresponding frame (72a, 72b) : the lower rollers (71a) are mounted on the lower frame (72a) which is fixed, while the upper rollers (71b) are mounted on the upper frame (72b) which is free to swing about the axis of the motorized upper roller (71b).

As shown in Fig.6, the axes of the rollers (71a, 71b) on the input side (I) of the conveyor (7) are connected to an electric motor (73) through a gear train (74) and the upper frame (72b) is mounted on the shaft of the motorized roller (71b) by means of bearings (75) .

Therefore, the upper frame (72b) is free to rotate about the axis of the motorized upper roller (71b) . The rotation, i.e. swinging or tilting, implies tilting of the driven upper roller (71b), i.e. of the upper roller in correspondence of the output side (U) of the conveyor, and then the tilting of the upper belts (70b) .

This feature of the conveyor allows its self- adaptation to the size and shape of the cushions exiting the production machine to conveyed to the collection point (R) .

Since the upper frame (72b) is free to rotate around the axis of the upper driven roller (71b) which is placed forwardly of the other roller carried by the same frame (72b) , the weight of the pivoting part

(70b, 71b, 72b) always guarantees proper contact of the belts with the surface of the cushions (6).

The double circular arrow in Fig.6 shows the tilting of the upper pivoting part (70b, 71b, 72b) of the conveyor by effect of the passage of the air cushions through the space delimitated by the said lower and upper belts (70a, 70b) . The tilting or swinging of the upper pivoting part (70b, 71b, 72b) of the conveyor is determined by the thrust that each air cushion exerts on the same upper pivoting part (70b, 71b, 72b) when dragged by the lower and upper belts (70a, 70b) along the conveying direction (T) , thus permitting the self-adaptation of the conveyor to the variable shape and size of the air cushions without requiring any further device for controlling the position of the dragging belts (70a, 70b) in relation to the air cushions.

According to the schematic view in fig.4, the said belts (70a, 70b) can have an external toothing that can be improve the dragging of the finished product. The belts (70a, 70b) can be substituted by web-shaped dragging elements.

It is understood that the means of longitudinal welding (SL) , the means of transverse seal (ST) , the air blowing means (8) and the means (5) for forming the pre-incision lines can be of any suitable type. In the accompanying drawings the finished product (60) is represented as a continuous succession of pillows (6) aligned along a single row but it is understood that the described invention is equally applicable to the case of the production of packaging material consisting of pillows aligned along multiple files side by side.

By summarizing, a device for conveying protective packagings (60) made of air cushions (6) according to the present inventyion comprises an input side (I) and an output side (U) for the packagings (60) which are conveyed through the device itself along a predetermined conveying direction (T) ; the device comprises motorized dragging means to drag the packagings (60) with dragging elements that are in contact with the same packagings (60) and guide them along said conveying direction (T) ; the dragging means comprise two superimposed pairs of rollers with horizontal axis (71a, 71b) with belts or webs (70a, 70b) wound on each pair of rollers, wherein a roller (71a, 71b) of each pair of rollers is motorized; the belts or webs (70a, 70b) delimit the top and the bottom of a path along which the protective packagings (60) must run; the dragging means are subdivided in an upper group and a lower group of dragging means, respectively supported by an upper frame (72b) and a lower frame (72a) ; the upper frame (72b) is free to rotate about a horizontal tilting or swinging axis such that it can freely rotate about said tilting or swinging axis by effect of a thrust exerted by the air cushions dragged by the dragging means along the conveying direction (T) .

In practice, the construction details may vary in any equivalent way as regards the single described and illustrated elements, without nevertheless departing from the scope of the adopted solution and thereby remaining within the limits of the protection granted to the present patent.