GB2337507A

GB2337507A - Interconnected block of bags and their manufacture

Info

Publication number: GB2337507A
Application number: GB9911443A
Authority: GB
Inventors: Jakob Schneider
Original assignee: Lemo Maschinenbau GmbH
Current assignee: Lemo Maschinenbau GmbH
Priority date: 1998-05-18
Filing date: 1999-05-17
Publication date: 1999-11-24
Anticipated expiration: 2019-05-17
Also published as: GB9911443D0; GB2337507B; DE19822269A1

Abstract

The rear wall 10 of a thermoplastics film bag has a blocking section 34 in the vicinity of its mouth for detachable adhesive-free connection to the front wall 20 of an adjacent such bag, and a recess or aperture 32 associated with that section 34 into which fingers can be inserted to open the bag. Joining of adjacent bags at section 34 is effected by heat or pressure, and perforations 33 around section 34 enable the bag to be torn away from the rest of the block. Each wall 10, 20 may have a respective connection section and aperture in interchanged positions, so that they alternate through the block. A connection section and aperture may be adjacent in the direction from top to bottom of the bag, as shown, or transversely of the bag, Figure 5. The bags are formed from a flattened tubular web, the top and bottom layers of which are held apart during punching to form the apertures 32 and perforations 33.

Description

41903pb.doc t 1 TITLE 2337507 Thermoplastic Foil Bag and Method and

Apparatus for the Manufacture Thereof.

This invention relates to a bag of thermoplastic foil with an opening arrangement, a rear and a front wall and a filling aperture with successive bags being joined together in the form of a stack of bags by means of a connection provided between the rear and front walls of adjacent bags and detachable from lo adjacent bags on the removal of the foremost bag from the stack.

Bags or sets of bags of the above kind combined in a stack and suspended from a supporting frame are disclosed for example in EP 0 401 950 B1. As regards matters of detail and the said patent publication describes a bag opening system in which the rear wall of the first bag in the stack in each case is connected with the front wall of the subsequent bags by an adhesive pad. The purpose is to ensure that when the first bag mounted on supporting bars of a supporting frame is pulled forward the next bag is caused to accompany the movement over a short distance, so that when the first bag is filled and detached the subsequent one has already been opened to some extent and can 20 thus be grasped and filled without difficulty.

It is known from practical experience that the use of adhesives in connection with delicate plastic foils is extremely undesirable, as any careless handling of the adhesive material not only prevents smooth operation but frequently leads to soiling and to the tedious task of cleaning the apparatus.

2 is An object of this invention is to provide a bag of the kind herein referred to and also to propose a method for the production of such a bag, enabling individual bags in a stack to be opened easily without recourse to adhesives. This invention also provides an apparatus for forming a bag provided with an opening system which is easy to operate and which is constructionally simple using a continuously running web of tubiform foil.

According to this invention there is provided a bag of thermoplastic film with an opening system, the bag having a rear wall and a front wall integrally connected and a mouth, the bag being adapted to form part of a stack of such bags with a detachable connection provided for each bag between a rear wall of one bag being the foremost in the stack and the front wall of an adjacent bag in the stack wherein the said connection is formed by an adhesive free blocking section located adjacent the mouth, each blocking section having an associated aperture facilitating the opening of a bag.

The adhesive-free blocking section and the opening recess can be positioned in accordance with the type of bag, for example one above the other in the case of a T-shirt type carrier bag, while for a different kind of bag, for example one having a bottom seam, they may be adjacent to one another.

Whatever the type of bag it may be of advantage if both the front wall and 20 the rear wall are provided with a blocking section and with an opening recess. In such cases it has proved advantageous for the blocking section and opening recess in the front wall to be offset with respect to those in the rear wall. In the case of bags blocked in the stack the position of the blocking section and that of the opening recess of successive bags are alternately staggered in relation to 3 each other.

The blocked bags can be tom off the stack of bags without difficulty, particularly if the blocking section takes the form of a mainly circular or semicircular separating line such as a perforation line of delimited separable s protuberances. The opening recess can be designed to enable the fingers to be inserted as required.

According to this invention there is also provided a method for the continuous production of a stack of bags from successive sections of a web of material formed by transverse separable welded connections produced on a lo web of thermoplastic tubiform film laid flat, in which method the two layers of material of the web in flat form are spaced apart in a processing zone and at least one blocking section is punched into at least one layer of the material while at least one opening recess suitable for the insertion of the fingers is punched into the other layer.

is in the method proposed by this invention a bag or stack of bags of this type is particularly easy to produce if the two layers of the web of tubiform film laid flat are spaced a certain distance in the zone of a processing station and at least one layer is perforated with at least one blocking section while at least one opening recess suitable for the insertion of the fingers is punched into the other layer. If both layers are provided with blocking sections and opening recesses it is of advantage for the operation to be carried out synchronously with the speed of movement of the web.

An apparatus according to this invention for the production of a bag of the type described in the foregoing is characterized by the fact that the punching 4 device takes the form of a hole punch positioned in a zone adjacent the upper film layer with the lower layer of the web of film spaced a certain distance away. The device may be provided, for example, with two cutting devices, one being associated with the upper layer and other with the lower layer of the web.

Each cutting device may have at least one tool carrier rotating about a shaft, a punching tool and a perforating tool being mounted on the free end of the shaft.

A simpler construction is provided if the cutting tool has two tool carriers which are mounted diametrically opposite on a hollow shaft rotatably mounted on a shaft support and on which the respective pairs of punching tools and perforating tools are offset in relation to one another. The said tools can preferably be removable and replaceable so that they can be adjusted for different hole punching and perforating operations which may be required for different types of bag.

To enable the process according to the invention to be applied in particular to continuous web of tubiform foil the cutting devices may be positioned by a control system actuated by signals, derived from a photocell with indexing marks printed on the web of material, which effect synchronization during the cutting process with the speed of movement of the latter.

Preferred embodiments according to this invention are described by way of examples and with reference to the drawings, wherein:

Figure 1 shows schematically a device for the production of bags provided with an opening system according to this invention, Figure 2 Figure 3 shows a stack of bags in a preferred version of the invention and to a larger scale, shows part of the production process shown in Figure 1, being the punching and perforating apparatus and to a larger scale, shows a plan view of a bag produced in accordance with this invention being in the form of a so-called T-shirt carder bag, shows a plan top view of a bottom seam bag, shows an alternative version of a bag, and Figure 7 shows an assembly of bags of the type shown in Figure Refening to the drawings a web of tubiform foil 1, produced in a known manner, either from an originally seamless tube of from a single web of foil folded over, is fed by a pair of forward-feed rollers 2 to a punching device 3, is which is further explained hereinafter with reference to Figure 3. On the output side of the punching device 3 the web of tubiform foil is if necessary, fed by a pair of draw-off rollers 4 to a folding device 5. The web of tubular foil then enters the zone of a pair of forward-feed rollers 6, followed by a cross cutting separating device 7. After the operation of cutters 8 of the cross cutting device 7 disposable or re-usable bags 9 are obtained and are conveyed by a transport device 11 to a stacking device 12. On the stacking device 12, which has a transport device 13, a number of single bags 9 are combined to form a stack 14. By the use of the transport device 13, comprising for example a conveyor belt, the stack can be moved to be positioned underneath a blocking device 15 by Figure 4 Figure 5 Figure 6 6 is means of which the single bags 9 are interlocked, welded or sealed together in the stack 14 in a manner to be described. After the blocking operation the stacks of bags are conveyed by the conveyor belt 13 until they finally arrive, if necessary, underneath a punching device 16 by means of which suspension holes are made therein, for example, andlor parts are punched out to form the carrying handle zone for a T-shirt-type carrier bag. The stacks of bags are then removed.

The punching and perforating apparatus 3 shown in Figure 3 is turned through 900 in relation to the illustration of Figure 1 for clarity. As may be seen lo in the drawing, an upper layer 1' and a lower layer 1 " of the double layer web of tubular foil 1 are fed in through a pair of feed rollers 2 and divided by means of a wedge-shaped separating and punch plate 17. For the accurate guiding of the upper layer 1' and the lower layer 1 " internal supporting rollers 18 are provided carried on the punch plate 17 operating in conjunction with external rollers 19.

The punch plate 17 has a centrally located aperture 21 after which the upper layer Vand the lower layer 1 " of the web of tube foil 1 are again brought together over a wedge-shaped end piece of the punch plate 17, from where they are conveyed onward as a flat web by means of the draw-off rollers 4. The actual punching and perforating unit 3 has on each side corresponding to the upper layer 11' and the lower layer 1 " of the web of tube foil, cutting devices 22 and 22' respectively, of identical construction only one such device being described in detail hereinafter.

Each cutting device 22 has a fixed hollow support 23 connected with a vacuum source in a manner not shown in the drawing. In the direction facing 7 the upper layer and the lower layer the hollow support has an aperture 24. A hollow shaft 25 is rotatably mounted on the hollow support 23. Diametrically positioned on opposite sides of the hollow shaft 25 are likewise hollow tool carriers 26, 27, which become operative in a manner described in more detail hereinafter after a rotation of the hollow shaft in the direction shown by the arrow 28 on the left-hand side of Figure 3 and that shown by the arrow 28' on the right hand side of Figure 3. On the free ends of the tool carriers 26, 27 are mounted by a mounting plate 30 a punching tool 29 and a perforating tool 31 respectively. These tools are so arranged that in the position illustrated, for example for the lo tool carrier 27, the punching tool 29 cutting into the upper layer 1' is positioned before the perforating tool 31 relative to the direction of rotation, while in the case of the tool-carrier 26, when acting on the upper layer V, the perforating tool 31 is positioned before the punching tool 29. A similar offset position results in respect of the cutting device 22' situated on the other side, that is for a punching tool 29'of the cutting apparatus 2Zin each case a perforating tool 31, is associated with cutting device 2Zand a punching tool 29'with the perforating tool 31. The pieces cut out of the web of foil in question by the punching tools 29, 29'can be removed by a vacuum source acting through an internal channel in the tool carriers 26 as well as via the aperture 24 in the hollow support 23.

With the use of the device described a hole 32 or a perforation 33, as shown in Figures 2 and 4, can be produced in the upper layer Vand lower layer 1 " in a bag. With the T-shirt type carrier bag shown in these drawings, the two holes 32, 33, are situated in succession. The individual holes 32 and perforations 33 of the bags are situated at the front and at the rear in altemate 8 configuration in the stack of bags, as may be seen more cieady in Figure 2.

In the case of a bottom-seam bag such as that shown in Figure 5, there is a semicircular delimited recess 32'or perforation 33' InFigures4and5the blocking points are marked 34 and 34' respectively. With reference to Figure 2 the holes 32 and perforations 33 of successive bags are offset in respect of one another, so that the blocking points between any two successive bags are likewise offset. As already mentioned, the blocking process is effected using two heating devices producing a readily separable connection between the adjacent bags, and by means of the blocking apparatus 15 indicated on purely lo schematic lines in Figure 1.

is In order to produce the holes and perforations on a successive basis in the continuously moving web of the tube foil 1, the rotation rate of the cutting devices is controlled by a system (not shown) and which is actuated by signals for example from a photocell and markings produced on the said web. This then effects synchronization with the speed of the web duriing the cutting process. Using a computer-controlled servomotor with a regulated rotation speed the peripheral speed of the drive of the cutting system can be adjusted in accordance with the said web speed. The holes and perforations can be produced regardless of the web speed and the register length of the product, 20 that is of the bag.

Figure 6 shows a single bag with an opening recess 32'which can be produced therein if the tool provided on the punching and perforating apparatus is designed accordingly. Bags of this type can then be joined together in stacks, as shown in Figure 7. Bottom-seam bags of this kind can be combined 9 in a stack, for example, by means of a linear blocking seam 35. An individual bag can then be separated from the rest of the stack by means of a stack perforation 36.

Claims

1. A bag of thermoplastic film with an opening system, the bag having a rear wall and a front wall integrally connected and a mouth, the bag being adapted to s form part of a stack of such bags with a detachable connection provided for each bag between a rear wall of one bag being the foremost in the stack and the front wall of an adjacent bag in the stack wherein the said connection is formed by an adhesive free blocking section located adjacent the mouth, each blocking section having an associated aperture facilitating the opening of a bag.

2. A bag in accordance with Claim 1, wherein the blocking section and the opening aperture are situated in succession lengthwise of the bag, the mouth being transversally aligned forming a top edge of the bag.

is 3. A bag in accordance with Claim 1, wherein the blocking section and the opening aperture are adjacent widthwise with the mouth extending widthwise across a top edge of the bag.

4. A bag in accordance with any one of Claims 1 to 3, wherein each bag has a 2o blocking section and an opening recess in both a front wall and a rear wall.

5. A bag in accordance with Claim 4, wherein the blocking section and the opening recess are offset in relation to one another in respect of the position in the front wall and rear wall of each bag.

11 6. A bag in accordance with Claim 4, wherein the offset position of the blocking section and opening recess in the front wall and rear wall of each bag are arranged in alternation in adjacent bags.

7. A bag in accordance with any one of Claims 1 to 6, wherein the blocking section takes the form of a substantially circular or semicircular zone of breakable connections such as perforations or protuberances.

lo 8. A bag in accordance with any one of Claims 1 to 6, wherein the opening recess is substantially circular or semicircular.

9. A method for the continuous production of a stack of bags from successive sections of a web of material formed by transverse separable welded connections produced on a web of thermoplastic tubiform film laid flat, in which method the two layers of matehal of the web in flat form are spaced apart in a processing zone and at least one blocking section is punched into at least one layer of the matedal while at least one opening recess suitable for the insertion of the fingers is punched into the other layer.

10. A method in accordance with Claim 9, wherein an opening recess is provided in one layer opposite to the blocking section in the other layer and a blocking section is provided opposite the opening recess.

12 11. A method in accordance with Claims 9 or 10, wherein the pairs of blocking sections and an opening recess are produced in both layers of material.

12. A method in accordance with Claim 11, wherein the blocking sections and the opening recesses are offset in relation to one another in the two layers of material.

13. A method in accordance with Claim 12, wherein the operation of producing the blocking sections and the opening recesses is effected synchronously with lo the speed of movement of the web.

14. A method in accordance with any one of Claims 9 to 13, wherein the punched out portions forming the opening recess are removed by suction during the punching operation.

is 15. A method in accordance with Claim 14, wherein in the zone of the blocking sections the bags separated from the web are welded together individually or in stacks by the application of pressure or heat.

16. Apparatus for the production of stackable bags having an opening system and produced from a web of thermoplastic foil laid flat and using a punching device, using a welding apparatus for transverse separation and a stacking device with a blocking device, wherein a punch unit comprises a punching and perforating device with means to separate the upper layer and lower layer of the 13 web by a defined distance.

17. Apparatus in accordance with Claim 16, wherein the punching and perforating device has two cutting devices, the one associated with the upper s layer and the other associated with the lower layer of the web.

18. Apparatus in accordance with Claim 16 or 17, wherein each cutting device is provided with at least one tool carrier rotatable about a shaft and carrying punch tools and perforating tools arranged in pairs and relatively offset.

19. Apparatus in accordance with any one of Claims 16 to 18, wherein the cutting device is provided with two tool carriers which are mounted diametrically on a hollow shaft rotatable about a pivot support and on which the punch tools and perforating tools are arranged in pairs in each case staggered in relation to 15 each other.

20. Apparatus in accordance with Claim 19, wherein the punch and perforating tools are mounted on the tool carrier in such a way as to be removable and replaceable.

21. Apparatus in accordance with any one of Claims 16 to 20, wherein at least the punch tool which is operative at a given instant can be connected to a vacuum source through apertures, channels andlor slits in the tool carder, the hollow shaft and in an axial support being a fixed support.

14 22. Apparatus in accordance with any one of Claims 16 to 21, wherein cutting devices are located on both sides of the web and driven in opposite rotational directions.

23. Apparatus in accordance with Claim 22, wherein the cutting devices are positioned by a control system actuated by signals derived from a photocell and indexing marks on the web, the cutting devices being synchronized to the speed of the web during the cutting process.

24. Apparatus in accordance with Claim 16, wherein a guide zone for the web is provided with a wedge-shaped punch plate with internal supporting rollers which are positioned between the upper and the lower sides of the web and with which are associated external guiding rollers.

is 25. Apparatus in accordance with Claim 16, wherein two blocking units are located in succession or adjacent each other in the zone of the stacking device.

26. A bag or interconnected stack of such bags substantially as described 2o herein and exemplified with reference to the drawings.

27. A method of producing a bag as described herein and exemplified with reference to the drawings.

28. Apparatus for the production of bags as described herein and exemplified with reference to the drawings.