DE1147379B - Device for producing flat bags from thermoplastic plastic webs - Google Patents

Description

Device for the production of flat bags from thermoplastic Plastic Sheets The invention relates to an apparatus for manufacturing of flat bags made of thermoplastic plastic webs, in which the welds of a reciprocating welding device consisting of a lower part and an upper part are generated whose movements are controlled so that the uninterrupted continuous web can be provided with transverse welds at any desired spacing can.

The invention is based on a known device for manufacturing of flap bags made of thermoplastically coated material webs.

The flap bags are made in such a way that the uninterrupted Continuous web of material around a tube former except for an intermediate space Is folded towards the middle, the width of which is equal to twice the length of the desired Closing flap is. The tube, which is closed except for the space in between, is then at a distance of the desired bag width with transverse strip-shaped heat seals provided and then in the middle of the space along and within the Cross welds are cross-cut, so that with each cross-cut two cross-sections Bags with flaps are incurred. The cross welds are made by means of a two-part reciprocating welder which creates the web grasped between themselves and themselves on their passage to carry out the weld stands out on its decline from the uninterrupted trajectory. The welding device is occupied with heating strips that are continuously heated.

This type of heating is unsuitable for plastic sheeting because on the one hand the relatively large mass of the heating strips that has to be kept at a constant temperature too cumbersome temperature control and on the other hand a cooling of the Weld seam within the welding device is excluded. But this is essential so that the weld seam has acquired a certain strength when it is the welding device leaves so that no undesirable deformations of the weld seam occur.

Nacli. According to the invention, therefore, the plastic sheet is welded by the well-known impulse welding, which allows instant temperature control and allowing the weld seam to cool within the welding device. at the use of impulse welding with a heating and cooling period every time However, there is the problem of achieving sufficient cooling in a short time, as large a number as possible of welds to be carried out in the unit of time can. Since a slow heating of the pulse welding device with a fast The welding sequence cannot be avoided, the cooling of the weld seam within the device slowed down more and more. The supply of a special coolant in the welder makes great for a reciprocating welding tool Difficulties and complicates the device in itself.

The purpose of the invention is therefore to solve the problem in a different way to solve. According to the invention this is achieved in that on the rotatable upper part the welding device arranged several pulse welding tools distributed on the circumference which are brought into effect one after the other to produce a transverse weld by turning the upper part intermittently so that for each individual pulse welding tool several work cycles are available as a cooling time. Cooler by inflating If necessary, the cooling can be additionally intensified with air. thanks to the Invention, the heating of the welding device is avoided, so that sufficient Cooling of the weld seam within the same ensured in a relatively short time is.

The device according to the invention can also be used for the production of Workpieces of a similar type are applied and is therefore not used in the manufacture limited by transverse flat pouches.

An embodiment of the device according to the invention is on Hand of the drawing described below. In the drawing, Fig. 1 shows a Side view of the device with the most important drive elements, Fig. 2 the Top view of the device according to FIG. 1, 3 shows a section A-B in Fig. 2 on an enlarged scale, Fig. 4 is a view in the direction of the arrow C in Fig. 2 on an enlarged scale, which refers to the drive parts for rotating the upper part of the welding device is limited, and FIG. 5 is a plan view of the drive parts corresponding to the side view in FIG. 4.

The plastic web 1 is due to the advance movement of the advance rollers 2, 3 withdrawn from a supply roll, not shown, and known per se Way guided over a hose former 4 partially shown. To the hose builder 4, the side edges 57 6 of the plastic web 1 are folded over towards the center, with a tube is formed. However, the hose must not be completely closed, d. that is, the side edges 5, 6 must not collide in the middle; it has to be Keep the space free. The width of the gap can be adjusted accordingly broadly selected hose former 4 or by changing the width of the initial web can be reduced or enlarged.

The width of the space depends on the length of the closure flap of the transverse flat bag to be produced, the length of the closure flap of a bag is equal to half the width of the gap.

A welding device closes behind the feed rollers 2, 3 on, which welds the parts of the tubular web la that lie on top of one another.

The weld seam consists, depending on the design of the welding element, from a wider one or - as shown - two narrow ones lying close together Seams 7, 8, which run across the web at equal intervals. The so in the same Distance welded web is again detected by a preferred pair 9, 10 and further promoted to the required remaining processing stations, of which the Slitting device 11, 12 is shown behind the pair of feed rollers 9, 10 is arranged. The longitudinal cutting device consists of a rotating Upper knife 11 and a likewise rotating lower knife 12. It generates the Separation cut 13, which is in the middle of the gap, and the hose web 1 separates a in half. In a manner not shown, the finished are then Two flap bags each through cross cuts within the cross welds separated and then filed.

The welding device consists of an upper and a lower part, which is arranged in each case above and below the hose web 1 a. The top is composed of two circular disks 14, which in a certain Are arranged at a distance from one another on a shaft 15. The shaft 15 is on both Pages each rotatably mounted in a square piece 16, the outside of the discs 14 are arranged. On the circumference of the circular disks 14 are in uniform Welding elements 17, 18, 19 connecting the panes are arranged at a distance from one another, in the exemplary embodiment four pieces. The welding elements are identical to one another and consist of a base 17 on which one or two heating elements 18 are attached are. The heating elements 18 are made of a sticking-preventing fabric web 19, for example made of teflon silk, which also covers part of the pad 17 covered.

The shaft 15 is on both sides over the bearing points in the square pieces 16 also extended and carries the drive parts on one of the shaft journals Rotation and on the other extended shaft journal a collector 20, which over a sliding contact 21 is connected to the power source. The collector is divided into four equal sectors when four welding elements are arranged, which are separated from one another and each of which has a sector with a welding element communicates.

The sliding contact 21 is arranged so that he each with that Sector of the collector 20 is connected, the associated welding element 17, 18, 19 is currently in the lowest position on the hose web 1 a. When a sector touches the sliding contact 21, no current flows, only a connection is established. The duration of the current flow is specially regulated in a manner known per se and extends to the implementation of impulse welding only for a fraction of the contact time of the sector the sliding contact 21.

The total duration of action of the welding device is a multiple the time span of the actual pulse welding, so that the The weld seam enters the welding device and the weld seam therefore exits has gained a certain strength from the welding device.

The lower part of the welding device consists of a wide rail 22, which are arranged exactly in the center of the shaft 15 and parallel to it under the hose web la is.

A plate 23 is attached to each end of the rail 22. The rail 22, together with the plates 23, forms a movable slide, the by means of rollers 24 which are rotatably mounted on the outer ends of the plates 23, can slide back and forth in a U-shaped rail 25.

The upper part of the welding device is fastened with studs 26, which are screwed into the underside of the square pieces 16 and through the rail 22 protrude, pressed onto the surface of the rail 22 of the lower carriage, whereby the hose path between the two is detected. The contact pressure is through Compression springs 27 are created between the lower surface of the rail 22 and washers 28 are arranged, which are held adjustable by nuts 29 on the studs 26 will.

The U-shaped rails 25 are on the side frames 30 of the machine attached so that the surface of the rail 22 with the underside of the hose web 1 a is at the same level.

In the welding position, a welding element 17, 18, 19 of the rotatable Upper part under the pressure of the springs 27, the hose web 1 a on the surface on the rail 22. When the power is switched on, the hose web la is through the heating elements 18 are heated and welded. In the surface of the rail 22 is an insert 32 made of flexible and heat-resistant material, for example Silicone sponge rubber, used to remove any unevenness in the hose path la and ensures a good fit of the same to the heating elements 18. In addition, by covering the insert 32 with a length of fabric 33, for example made of teflon silk, an adhesive the hose track 1 a avoided during the welding process.

Since the hose web 1 a uninterrupted at a constant speed moved, the welding device must also move during the welding process Move the web speed evenly. This is done in a manner known per se achieved by a rotating at a constant speed about the axis 34 Crank 35, which with a roller 36 attached to its end back in a loop and slides away. The loop is located in a lever arm of a double lever 37, which is rotatably mounted on a shaft 38.

By the rotating crank 35, the double lever 37 is swinging Movement brought and transmits this reciprocating movement by means of a Connecting rod 39, which is adjustably fastened in a guide 40, on a Lever 41, which in turn is firmly connected to a rotatable shaft 42.

The reciprocating partial rotary motion of the shaft 42 becomes transferred to two levers 43 that are firmly attached to it and close to the insides the side frames 30 of the machine are arranged. These levers 43 are cranked Connecting pieces 44 pivoted to the plates 23 of the lower carriage and thus transfer a back and forth movement to it.

The loop in the double lever 37 is designed so that the movement in the direction of arrow 45, in which the hose path la also moves the uniform speed of the hose web 1 a coincides. The return movement opposite to the direction of arrow 45 takes place very quickly, so the idle time is kept as small as possible.

The length of the distance in the direction of arrow 45 is equal to that each desired bag width, reduced by that of the tubular web during distance covered by the return of the welding device.

To change the bag width, the attachment of the connecting rod 39 released on the double lever 37 and the connecting rod 39 in the guide 40 either moved in the direction of the axis 38 or away from it. This reduced the size or the deflection of the connecting rod 39 and thus also the bag width increases.

A particular advantage is that the guide 40 is circular is formed, the radius of the circular guide 40 being the length of the connecting rod 39 corresponds. As a result, when the bag width is changed, that this can be carried out without changing the position of the other parts. what a straight line Guide 40 would not be possible and an impermissible adjustment of the slide 22, 23 would lead to the crank position.

In order to allow the hose web 1 a to continue unimpeded when returning To achieve the welding device, the upper part 14, 15, 16, 17, 18, 19 of lifted off the web, with a vertical guidance of the square pieces 16 through angular shaped rails 31 takes place, which is attached to the rail 22 of the lower carriage are. By means of the rails 31, the upper part is also carried along by the lower part when going back and forth parallel to the hose path. After the return has ended will the upper part 14, 15, 16, 17, 18, 19 is lowered back onto the hose web 1 a.

This movement is controlled by an adjustable cam 47 a roller 47, which is attached to a lever 48, is transmitted to a rotatable shaft 49. On this axis 49 levers 50 are attached to the inside of the side frames 30, which are hinged to flat iron 51 so that they can rotate. This flat iron 51 run parallel to the hose path past the square pieces 16 and are at their other end hinged to levers 52, which are attached to bolts 52 in the side frames 30 a are rotatably mounted.

The levers 50 and 52 are of equal length, so that there is always a parallel one Displacement of the flat iron 51 is achieved.

On the square pieces 16 51 rollers 53 are rotatable via the flat iron stored that a rolling of the upper part 14, 15, 16, 17, 18, 19 on the flat iron 51 enable.

The rollers 53 are arranged so that they are not during the welding process rest on the flat iron 51 and do not counteract the contact pressure.

The cam 46 must be set so that it is at the beginning of the return, the flat iron 51 lifts and the upper part 14, 15, 16, 17, 18, 19 is lifted from the tubular web la, the lower carriage 22, 23 its Retains position and only the springs 27 are compressed. At the end of the return the flat iron 51 is lowered and the upper part 14, 15, 16, 17, 18, 19 be through Its own weight and the spring pressure are pressed again against the tubular web 1a.

During the return movement, the Welding device carried out by drive steep, which extended on the front Shaft journal of the shaft 15 are arranged.

With the arrangement of four welding elements on the circumference of the discs 14 the shaft must be turned a quarter turn clockwise with each return so that at the beginning of each new work cycle, the next following welding element the welding takes over and the one just used during the three following work cycles can cool down. By arranging several welding elements on the circumference of the Disks 14 naturally increase the number of idle cycles for each welding element and thus increases its cooling time, which results in a quick welding sequence and still a good cooling of the tools is achieved.

The switching movement of the shaft 15 is carried out by a rod 54 which formed fork-shaped at one end and pushed onto the axle 34 with the fork is.

A roller 55, which is at the end of the fork-shaped formation of the pull rod 54 is attached, is in a curved recess 56 of a disk 57 out, which is firmly connected to the shaft 34. Due to the even turning movement the shaft 34 and the uneven course of the cutout 56 is on the pull rod 54 exerted a reciprocating motion. This movement is via an angle lever 58, which is rotatably mounted on an axle 59, is transferred to a rod 60.

This rod 60 is rotatable at its other end on a lever 61 hinged on the extension of the shaft 15 between a fixed disc 62 and a fixed ratchet wheel 63 (Fig. 4 and 5) is rotatably mounted. on a pawl 64 is rotatably attached to the lever 61 by means of a screw bolt 65, which is brought into contact with the ratchet wheel by the pressure of a torsion spring 66 will. If there is now a lifting movement on the rod 60, the lever 61 with the The pawl 64 is raised, the pawl 64 presses against the teeth of the ratchet wheel 63 and rotates it one tooth further according to the stroke movement, whereby the number of teeth corresponds to the number of welding elements. So that the adjustment is exactly the same Angle takes place, are on the circumference of the disc 62 obtuse-angled locking recesses 67, the number of which corresponds to the number of welding elements present. In these Latching recesses 67, an index bolt 68 engages, which is guided in a holder 69, which is arranged above the disk 62 and with screws 70 on a square piece 16 is attached. A compression spring 71 between the holder 69 and the index bolt 68 is arranged, causes a constant pressing of the index bolt 68. On the protruding A locking ring 72 is attached to the end of the index bolt 68 from the holder 69, which prevents it from falling out.

If a rotation of z. B. 900, the elements required for four welding is, by the lever 61 by different inclinations for different bag widths of the rod 60 reciprocating with the welding device is not fully executed and therefore the index bolt 68 does not lock in the middle of one of the locking recesses, see above the index bolt 68 slips under the pressure of the spring 71 into the central position and rotates while the disk 62 continues with the shaft 15 by the amount that is still missing.

The shaft is precisely locked in place by the index bolt 68 15 and thus the welding elements.

Cooling air can be added to intensify and accelerate the cooling process the cooling section of the weld seam located in the welding device and on the welding elements in the cooling position are inflated.

It is also possible to have two or more welding jig tops at a distance of the bag width to be produced a correspondingly elongated lower part to be assigned, whereby a tandem version is created, with each corresponding extended working stroke, two or more welds can be carried out, whereby the output of finished bags is increased.

Claims (12)

PATENT CLAIMS: 1. Device for producing flat bags from thermoplastic plastic sheets, in which the welds from a back and forth generated, consisting of a lower and upper part welding device whose movements are controlled so that the uninterrupted continuous Web can be provided with transverse welds at any desired spacing, thereby characterized in that on the rotatable upper part (14, 15, 16) several pulse welding tools (17, 18, 19) are arranged distributed on the circumference, one after the other for generating a transverse weld can be brought into effect by the upper part intermittently is rotated so that for each individual pulse welding tool (17, 18, 19) several Work cycles are available as cooling times. 2. Apparatus according to claim 1, characterized by a back and forth Proceeding two-part welding device, the rotatable upper part of which is made of circular Discs (14) are made on a shaft (15) rotatable in square pieces (16) is mounted, spaced apart from one another and on the circumference of the disks (14) connecting pulse welding tools (17, 18, 19) are arranged distributed, and the lower part of which consists of a rail (22) which is supported on the front by plates (23) is limited, the back by means of rotatably mounted rollers (24) in guides (25) and slide, and with studs (26) fastened in the square pieces (16) protrude through the rail (22) and the upper part by means of springs (27) press against the lower part, the square pieces (16) in guides (31), which are attached to the rail (22) can slide up and down. 3. Apparatus according to claim 2, characterized in that when Return of the welding device through the upper part by means of two levers (50, 52) parallel flat iron (51) acting on rollers (53) attached to the Square pieces (16) are attached, is raised, the lifting movement through a cam disk (46) via a roller (47) which is rotatably mounted on a lever (48) is transmitted to an axle (49) that controls the lifting movement of the levers (50), which are fixedly arranged on the axis (49), transferred. 4. Apparatus according to claim 1 and 2, characterized in that a ratchet wheel (63) is fixedly arranged on the shaft (15), via which the shaft (15) is rotated gradually. 5. Apparatus according to claim 4, characterized in that a In the work cycle rotating cam (57) via a roller (55) a lifting movement on a rod (54) which exerts the lifting movement via an angle lever (58) and a rod (60) transmits to a lever (61) which by means of a mounted on it The pawl (64), which rests against the teeth of the ratchet wheel (63) by spring pressure, transmits the lifting movement to the ratchet wheel (63). 6. Apparatus according to claim 5, characterized in that on the Perimeter of a disc (62) fixedly arranged on the shaft (15), obtuse-angled locking recesses (67) are attached, the number of which corresponds to the number of teeth of the ratchet wheel (63) and into which an index bolt (68) engages due to the pressure of a spring element (71), whereby an exact partial rotation of the shaft (15) is guaranteed. 7. Apparatus according to claim 1, 2, 4, 5 and 6, characterized in that that the number of teeth of the ratchet wheel (63) and the number of locking recesses (67) of the disc (62) match the number of pulse welding tools (17, 18, 19). 8. Apparatus according to claim 1 and 2, characterized in that the reciprocating drive of the two-part welding device via a crank loop drive (35, 36), a double lever (37), a connecting rod (39) and a lever (41) on a shaft (42) and from this on lever (43), which by means of Connectors (44) exert a stroke movement on the welding device, the stroke being adjusted the connecting rod (39) changed in a guide (40) of the double lever (37) can be. 9. Apparatus according to claim 8, characterized in that the guide (40) in the double lever (37) is designed as an arc piece, with its radius the length of the connecting rod (39) and an adjustment of the stroke the welding device by means of the connecting rod (39) without a change in position the remaining parts. 10. Apparatus according to claim 4 and 8, characterized in that the crank loop drive (35, 36) and the cam disk (57) in common sam on one Drive shaft (34) are arranged so that the stroke movements at a changed speed always run synchronously with each other. 11. Device according to the preceding claims, characterized in that that an additional cooling on the cooling section in the welding device located weld seam and / or on the pulse welding tools located in the cooling position is provided by inflated cooling air. 12. Device according to the preceding claims, characterized in that that two or more welding device upper parts at a distance of the bag width to be produced are assigned to a correspondingly extended lower part in tandem design.