EP0620087B1 - Apparatus and method for perforating films - Google Patents

Abstract

Method for perforating films, characterised in that it consists mainly in the fact that successive series of perforations are made by means of heated sleeve tubes (10); the small discs (32) cut out are grasped; and these small discs (32) are moved away from the film (2) in this way, so that they are actually cut away. <IMAGE>

Description

The present invention relates to a method for perforation of a film, according to which successive series of perforations are made by means for cut, parts of the film thus perforated are seized and remote by means that can grab and, if necessary, removed from the latter means by blowing.

The present invention relates more particularly to such a process for perforating films, more specifically plastic films, such as all types possible from so-called stretch films, high density films, polyethylene films, polypropylene, etc.

More specifically still, the present invention relates a method for practicing, effectively and rational, relatively dimensional perforations big in movies for example in the case of circular perforations of the order of 6 to 60 mm.

A process of this kind is described in FR-A-2,392,916. According to this known method, strips are cut by cutting assemblies mounted on a drum and comprising two knives parallel to each other which are spaced one of each other by a distance corresponding to the width of this strip and which protrude outside the wall of the drum.

The film is guided between this drum and a second driven in the opposite direction and serving as a support when cutting and used to distance the cut strips. These bands are indeed sucked against this drum by channels crossing this second drum and connected successively a vacuum pump and a source of pressurized air.

The present invention relates to a method which allows to obtain a film material provided with large perforations, which can be done very simply and fast and which is primarily intended to become a packaging material for flowers, plants, vegetables, fruit, food, in general for example foods that need to be frozen, in other words products for which packaging must be obtained efficient which allows, at the same time, a very aeration effective and important products.

In accordance with the invention, a method is proposed which allows to provide relatively large perforations all possible packaging materials, up to and including an extremely thin film material which has good heard a very high elasticity, as well as what we calls shrink films, which is impossible with known methods.

For this purpose we use as means for cutting, sleeves that are heated so that these sleeves cross the film like a heated knife and cut small discs from the film, discs that we grab using sockets provided with a passage which is put successively in contact with a vacuum pump, respectively pressurized air.

A method for perforating a thermoplastic film by heated elements is known from FR-A-2,378,623, but in this case holes are made by local fusion of the matter. This material is not cut but melted, and driven back radially, which has the desired result that the hole is surrounded by a thickened edge.

Preferably, according to the invention, the film is transported between two cylinders which one turns against the other, one of which is provided with heated sleeves which protrude outside the cylinder wall, while the second cylinder is provided with holes in which come lodge the sleeves during the rotation of the cylinders and in which the sockets are placed, each socket being connected to a tube, the passage in this socket is finding in connection with a channel made in this tube, this tube extending to a terminal flange of the cylinder, the canal located in connection with a passage practiced in this cylinder end flange.

The invention also relates to an advantageous device, to implement the above method according to the invention.

The invention thus relates to a device for the perforation of films, which is mainly formed by two cylinders turning against each other, one of which is provided means for cutting parts out of the film, while that the second cylinder is provided with means which can grasp the cut parts, characterized in that the means for cutting parts are sleeves heated through the outer wall of the first cylinder and cutting out small discs, while the second cylinder has holes in which can come accommodate the sleeves during the rotation of the cylinders, means for grasping the cut parts and therefore the small cut discs including sockets which are placed in these holes and which can be successively put in connection with a vacuum pump, respectively air under pressure, each socket being connected to a tube and presenting a passage which is linked to a channel formed in this tube, this tube extending to a cylinder end flange, the channel being in connection with a passage made in this terminal flange of the cylinder.

la figure 1 est une représentation schématique d'un dispositif qui met en oeuvre le procédé conformément à l'invention;

la figure 2 est une vue en perspective selon la flèche F2 en figure 1;

la figure 3 est une coupe transversale à plus grande échelle, prise le long de la ligne III-III de la figure 2;

la figure 4 est une coupe transversale prise le long de la ligne IV-IV de la figure 3.

In order to better highlight the characteristics of the invention, below, there is described, by way of example, without any limitation, a preferred embodiment with reference to the accompanying drawings in which;

Figure 1 is a schematic representation of a device which implements the method according to the invention;

Figure 2 is a perspective view along arrow F2 in Figure 1;

Figure 3 is an enlarged cross-section taken along the line III-III of Figure 2;

Figure 4 is a cross section taken along line IV-IV of Figure 3.

In FIG. 1, a device is schematically represented for implementing the method according to the invention, by which the main elements of this device are formed by a feed roller 1 on which is arranged the film material 2 to be treated, a cylinder of braking 3 for tensioning the film material 2, rollers 4-5 cooperating mutually to practice in the subject of film 2 relatively large perforations, respectively, to move away from the film material 2 the small cut discs, whereby the film material 2 scrolls around roller 5 and finally a roller drive 6 for the film material 2, which has task of keeping the latter tense in cooperation with the brake cylinder 3 until the material of perforated film is wound on a roll supply 7.

Of course, the different cylinders are driven each appropriately to ensure that the different cylinders work synchronously.

The cylinder 4 is constituted, in accordance with the invention, mainly by a thick-walled sleeve 8 in which are made several holes 9 which are arranged according to a well-defined configuration, for example in this case, in parallel rows, the holes 9 being placed in a zigzag.

Through each hole 9 formed in this way, is placed a sleeve 10 whose diameter is less than the diameter from hole 9 so that there is no contact between this sleeve 10 and the hole 9.

Preferably, the sleeves 10 are made of copper and are fixed for example by welding on a batten 11, by example also in copper, in which is installed an electrical resistor 12 which, suitably, for example by electrical conduits 13-14, is connected to an electrical circuit.

On each slat 11, a strip of material is applied insulation 15 in which holes have been hollowed out for the sleeves 10 so that when the slats 11 are fixed with appropriate screws 16 with the nut clamping 17 against the inner wall of the tube 8, it does not form no thermal contact between the slats 11 and the cylinder 4.

The cylinder 5 according to the invention is also formed by a thick-walled tube 18 in which are made holes 19 whose diameter is preferably equal to diameter of the holes 9 made in the tube 8 and by which these holes 19 are made in the tube 18, according to the same configuration as the configuration holes 9 in the tube 8.

Through each hole 19 in the tube 18, a socket 20 whose free end coincides with the periphery of the tube 18 and through which the sockets of a one and the same row are fixed to a common channel 21 which can be formed by a suitable tube whose passage 22 is in connection with the passages 23 practiced in the corresponding sockets 20.

This channel 21 gives, at one end of the cylinder 5, on a passage 24 made in the flange 25 of the cylinder 5, in which are also housed the ends of the tubes 21.

The other ends of the tubes 21 are housed in a identically in a flange 26, these flanges 25 and 26 being fixed with the tube 18 by means of screws or the like, not shown.

The same goes for cylinder 4 which is fitted with flanges 27-28 at each of its ends.

Against the flange 25 of the cylinder 5, is still applied a fixed flange 29 in which two notches are made circulars 30 and 31.

The aforementioned circular notches 30 and 31 extend at an angle of 90 ° and are placed diametrically to each other, the notch suction 30 being disposed above.

The implementation of the device as described above is very simple and takes place as follows.

The film material 2 which, by the cooperation of the cylinders 3 and 6, is placed taut across the device, scrolls between cylinders 4 and 5 where the first comes into contact with a defined row sleeves 10 which are heated to a temperature appropriate so that they can penetrate to through the film material 2.

During this movement, a corresponding row of sockets 20 came to settle against the notch 30 by through which cylinder 5 is connected to a vacuum pump or the like, so that when the corresponding sockets 20 come against the film material, the small discs 32 released by means corresponding sleeves 10 are sucked against the sockets 20.

During the displacement of cylinders 4 and 5, the sleeves 10 will cross film 2 like a knife reheated; after which, these sleeves 10 come arrange in the holes 19 made in the tube 18 of the cylinder 5 and, in this way, film 2 plus specifically the small disks 32 come into place contact with sockets 20.

During the subsequent rotation of cylinders 4 and 5, the sleeves 10 will again leave the holes 19, making the small disks 32 far apart of film 2 with great security by the fact that these small discs 32 remain attached to the sockets 20 for one quite long time.

When cylinder 5 continues to rotate, the passage 24 in the flange 25 will pass in front notch 30, so that the suction of the small discs 32 disappears and that the latter, from that moment, can fall freely down into a non-collecting container represented.

In case these small discs remain stuck despite all against the sockets 20 in question, we plan the notch 31 via which air is conveyed under pressure along passage 24 to reach the sockets in question 20, the small discs 32 thus being blown apart with great safety.

It is clear that in this way we provide a device by which it becomes possible to practice relatively large perforations in film material very thin, regardless of characteristics specific to the latter, with absolute certainty that these perforations are correctly arranged and that the small discs pushed apart are pushed away of film 2 with great security.

It is also obvious that one can modify the size of the perforations by choosing other cylinders 4, respectively 5, of which the sleeves 10 show the shape and dimensions of the perforation desired.

The electrical connection of the resistors 12 and the connection of devices to cause pressure lower and higher pressure is not shown in the drawing, since they can be made this any known ways in oneself.

Claims (8)

1. Method for perforating films whereby successive series of perforations are made by cutting means (10), whereby parts of the thus perforated film are caught and removed by gripping means (20) and, if necessary, are blown away from said means (20), characterized in that sleeves are used as cutting means (10) which are heated, such that these sleeves go through the film like a heated knife and cut small slices out of the film which are caught by means of bushes (20) provided with a passage (23) that is Successively put into contact with a vacuum pump, with compressed air respectively.
2. Method according to claim 1, characterized in that the film is carried between two cylinders (4-5) that are made to turn against one another, one of which (4) is provided with the heated sleeves (10) which protrude out of the cylinder wall (4), whereas the second cylinder (5) is provided with holes (19) in which the sleeves (10) enter during the rotation of the cylinders (4-5) and in which the bushes (20) are placed, whereby each bush (20) is connected to a tube (21), the passage (23) in said bush being linked to a groove (22) provided in said tube (21), whereby the tube (21) extends to an end flange (25) of the cylinder (5), the groove (22) being connected to a passage (24) provided in said end flange (25) of the cylinder (5).
3. Device for perforating films which mainly consists of two cylinders (4-5) which turn against one another, one of which (4) is equipped with means (10) to cut out parts of the film (2), whereas the second cylinder (5) is equipped with means (20) which can catch the cut-out parts, characterized in that the means for cutting out parts are heated sleeves (10) which go through the external wall of the first cylinder (4) and cut out small slices (32), whereas the second cylinder (5) is provided with holes (19) in which the sleeves (10) enter during the rotation of the cylinders (4-5), whereby the means to catch the cut-out parts and thus the small cut-out slices (32) are provided with bushes (20) placed in said holes (19) which can be successively connected to a vacuum pump, compressed air respectively, each bush (20) being connected to a tube (21) and having a passage (23) which is linked to a groove (22) provided in said tube (21), whereby the tube (21) extends to an end flange (25) of the cylinder (5), the groove (22) being connected to a passage (24) provided in said end flange (25) of the cylinder (5).
4. Device according to claim 3, characterized in that the sleeves (10) are placed in holes (9) provided in the wall (8), whereby these holes (9) are larger than the corresponding dimensions of the sleeves (10) and whereby the sleeves (10) of one and the same row are fixed on a common lath (11) in which is provided a heating element (12).
5. Device according to claim 3 or 4, characterized in that the sleeves (10) are fixed in the tubular cylinder (4) by means of screws (16) and nuts (17), in which is provided a feeble thermal isolation material (15) between the internal wall of the tube (8) and each lath (11).
6. Device according to any of claims 3 to 5, characterized in that the dimensions of a bush (20) are significantly smaller than the internal dimensions of a sleeve (10).
7. Device according to any of claims 3 to 6, characterized in that the above-mentioned end flange (25) in which are provided passages (24), rests against a fixed flange (29) in which are provided two circular notches (30) and (31), one of which works in conjunction with a suction mechanism, for example a vacuum pump, whereas the other works in conjunction with a compressed air supply mechanism.
8. Device according to claim 7, characterized in that the circular notches (30) and (31) form an angle of 90° and are placed diametrically in relation to one another, the suction notch being placed on top.

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