JPH0212172B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is particularly useful for forming transverse seam welds or separate transverse seam welds in tubular or semi-tubular plastic film webs for making bags. Regarding the device. The apparatus consists of a transverse welder having a jaw adapted to open and close periodically, and when the jaw is open, the film web is advanced intermittently between the jaws. and held in place during the welding time. The lateral welding device further includes a rocker lever;
This rocker lever transmits the same or opposite movement obtained from the rotating eccentric cam wheel to the lateral welding device or film web via the cam slot and slide block.

West German Patent No. 931629 discloses an apparatus for producing heat-sealed flat bags;
In this device, the sealing carriage is actuated by a rotating crank pin of a crank and reciprocates with respect to a continuously advanced film web. For this purpose, the crankpin extends into a cam slot formed in the pivoted lever;
This lever is connected at its free end to the sealing carriage via a link. This drive transmits a sinusoidal reciprocating motion to the sealing carriage at a speed approximately equal to the speed of the web for only a short period of time and is therefore only effective for welding the web for a short period of time. That short period of time is often not sufficient to form a satisfactory, sealed seam.

West German Patent No. 1147379 discloses a device of the type first described above, in which a sealing carriage is connected to a film web and
Attempts are being made to extend synchronized movement time. For this purpose, the pin of the rotating crank is
The pivoted double arm lever is guided by a cam slot formed in one arm, the other arm being connected to the sealing carriage by a link and a connecting lever. A cam slot formed in one arm of the lever allows the sealing carriage to
It is designed to be moved at the same speed as the film web for as long as possible, without a sinusoidal motion, and where the link is pivoted to the other arm, the bag has different widths. must be adjusted to be produced by this device. This device has the disadvantage that the curvature of the cam slot formed by one lever arm is chosen optimally for the synchronous movement of the sealing carriage and film web only for a single bag width. are doing. This is because, for all other bag widths, where the link for transmitting the pivoting movement is pivoted to the other lever arm, the pivoting connection of the link to the pivoting joint of the double-arm lever This is because, depending on the distance to the axis, it must be adjusted to perform different angular, rotational movements, and because of the rotational axes of these different double-arm levers, and these different rotational movements of the links. Due to the movement, the movements transmitted to the sealing carriage are different from each other. The time during which the sealing carriage is synchronized to the film web decreases as the pivot connection of the link is moved away from the location of the lever arm where the cam slot provides the best synchronization.

The object of the invention is initially to provide a device of the type described above, in which the relative movement of the welding tool and the film web is proportional, independent of the dimensions of the bag to which the machine is adjusted. The aim is to provide a device in which the welding tool and the film web are synchronized for the longest possible time.

This object is achieved by the present invention in the following ways. The lever has a straight radial track, and the first slide block has a straight radial track, and the first slide block has a straight radial track.
guided longitudinally and also connected to a second
connected to the slide block. This second slide block can move along a straight slide path that forms the base of the triangle, and the sides of the triangle are
Determined by levers at both ends. The slide track can move parallel to itself,
It is designed to be fixed in place on the machine frame. And one of the slide blocks is
It has a lever connected to it, and this lever is
It remains parallel to itself and is adapted to transmit the motion to the welding device or film web.

This is because the second sliding block is guided along a linear trajectory, and by the pivoting movement of the lever, the second sliding block performs a radial movement, so that through the pivoting movement the second sliding block performs a radial movement. The rise in the arc is corrected.

As a result, the two slide blocks are guided along a substantially straight trajectory, which straight trajectory is
It is represented by the chord of an arc traversed through a rotational motion. Since the straight trajectory according to the invention compensates for the rise of the circular arc, the characteristic curve of the cam slot is correctly adjusted to any movement required to produce bags of different dimensions.

A lever connected to one of the sliding blocks constitutes a link and may be connected to a carriage which supports the welding device and which is parallel to the track for the second sliding block and which is connected to the frame. It is designed to move back and forth within a fixed orbit via links.

The welding or sealing device may be mounted on a transportable carriage, but in practice stationary sealing devices may also be used. In that case, the film web is moved intermittently adjacent to the sealing device to provide a lateral seam weld. Intermittent motion is obtained using a web storage device which ensures that the web does not move during welding in the sealing device. The web storage device precedes and follows the sealing device and is controlled by continuously rotating pinch rollers in such a way that the web does not undergo any other stress-causing movements.
For this reason, the web storage device is controlled so that a portion of the web is held in place during the welding operation and accelerated to the peripheral speed of the pinch roller as quickly as possible and without increasing the stresses in the web. It must be. This can be achieved with the use of dancer rollers, such as toothed belts, which move in mutually opposite directions, the toothed belts being stopped by said dancer rollers, It is driven to precisely hold the web. For this purpose, the drive of the toothed belt is preferably derived from a lever connected to one of the slide blocks.

According to another proposal, the stated objective is achieved for the following reasons. the lever has a straight radial track on which the slide block is longitudinally slidable; the axle of the slide block is mounted in a carrier; the carrier is guided in the machine frame; It is free to slide longitudinally while remaining parallel to itself.
For said axle, a mounting provided in the carrier is adapted to be movable transversely to the direction of movement of the carrier and to be fixed in position. Said attachment is possible along the base of a triangle with sides defined by levers at both end positions, the carrier having a lever connected thereto, which lever itself remains parallel to the welding device or the film web. For transmission motion,
The lever may be connected to a carriage supporting the welding device or to a toothed belt or the like for raising or lowering the dancer rollers in mutually opposite directions.

In the device according to the invention, the influence of known fixed slider crank mechanisms is eliminated. This is because the path of the shaft pin of the slider crank is designed to be a straight line, and this straight line constitutes the base of the above-mentioned triangle. As a result of this, the motion and speed ratios required to produce bags of different dimensions are proportional to each other.

Further advantageous developments of the invention are set out in the independent patent claims.

Two embodiments of the device according to the invention will be explained more fully below in conjunction with the drawings.

In the embodiment shown in FIGS. 1 and 2, the cam wheel 1 is provided with a cam rib 2. In the embodiment shown in FIGS. The cam wheel 1 is supported by a timing shaft 3 which is rotatably mounted on a side wall 4 of the housing. The cam wheel is
Driven by gear 5, this gear is driven by cam wheel 1
and is non-rotationally connected to the cam wheel. A pair of cam driven rollers 6
is rotatably attached to the cam driven lever 7 and rolls on the cam rib 2. The cam driven lever 7 is keyed to a shaft 8, and the shaft 8, like the timing shaft 3, is rotatably attached to the side wall 4 of the housing. The cam slot lever 9 is the cam driven lever 7
It is keyed to the shaft 8 at a distance from the shaft 8 and has a cam slot in which the slide block 10 is guided. The slide block 10 has a through hole 11 from which a shaft portion 12 projects at one end of a shaft 13. Shaft 13 serves only for synchronization. This is because another cam slot lever is
This is because it is attached to a continuous shaft 8 in the side wall of the housing opposite the side wall 4 of the housing.

A shaft 12 projecting from the bore 11 supports a connecting rod 14 and a driven roller 15. Since the cam driven roller 15 is held within the linear track 16, the swing of the cam slot lever 9 causes
Only linear movement is possible via the cam driven roller 15.
It is transmitted to the connecting rod 14, and also connected to the connecting rod 1.
4 remains parallel to itself in all phases of its motion. This construction therefore eliminates any irregular movement that would occur if the slide block and/or cam follower rollers were not guided in a straight trajectory.

As is especially clear in Figure 1, the straight trajectory is
supported by two carriers 17 and 18;
These carriers can be raised and lowered along tracks 19 and 20 by a hydraulic piston-cylinder arrangement (not shown) when it is desired to change the dimensions of the bags being produced. . The cam follower roller 15 moves in a straight line regardless of the selected bag size, so that the ratio of motion to the connecting rod 14 and the sealing carriage 1, which is only shown schematically, is
The ratio of motion to 4' will always be proportional.
This would not be the case if the straight track 16 were omitted and the cam follower roller moved along an arc. In that case, cams with different degrees of elevation are required for different bag sizes and therefore for each bag size if an optimum movement of the sealing carriage 14' is to be obtained. A different cam rib must be used.

In the embodiment shown in FIGS. 3 and 4, the movement is not transmitted to the sealing carriage, but to the mounting of the dancer roller or correction roller. These mountings move along tracks 51, 52 of the roller frame 43 of the web storage device. As in the embodiment shown in FIGS. 1 and 2,
The cam slot lever 24 is oscillated periodically by a cam wheel 21 having a cam rib 22 and a cam follower roller 23 rolling on said rib. The cam follower roller 25 is guided by a cam slot of the cam slot lever 24 and is mounted on an axle 26 whose free end is fixed to a slide block 27.
is supported. The slide block 27 is guided in another cam slot and can be moved along the cam slot 30 by means of a screw 28.
The screw 28 is used to adjust the size of the bag.
It is driven by a motor 29. Cam slot 30 is
It consists of two machined slots in opposed plates 31 and 32 which are secured to opposite sides of carriers 33 and 34. The carriers 33 and 34 each have a through hole.
A screw 28 for adjusting the slide block 27 is guided and attached to these through holes. A motor 29 for driving screw 28 is secured to a bracket 35, which is welded to plate 31.

As is particularly clear from Figure 3, the carrier 3
3 and 34 are upper lugs 36 and 37, respectively;
and lower lugs 38 and 39 by which the carriers are guided on vertical guide rods as the carriers 33 and 34 move up and down. The guide rod 42 is attached to the side wall 4 by means of a bracket 41.
It is fixed at 0. To transmit the motion to the roller frame 43, the arm 44 is connected to the bracket 3.
5 and is pressed against an endless toothed belt 46 by a clip 45. This endless toothed belt is wrapped around four toothed pulleys 47 and two reversing pulleys 48. As is clear from FIG. 3, the axes of the two dancer rollers 49 and 50 are also on the toothed belt 46 and are provided on the tracks 51 and 52,
These tracks allow the two dancer rollers to move up and down.

The web 54 is continuously advanced by the pinch roller 53 so as to move continuously at the same speed before the pinch roller 53 and after the feed roller 55 when viewed in the direction of travel, and then by the roller 50. It is continuously stored by the rollers 49, and at the same time, it is intermittently sent out by the rollers 49. When roller 50 is lowered and roller 49 is raised, sealing carriage 56 can be operated to weld the web, which is now in position between reversing pulley 57 and reversing pulley 58. is maintained.

[Brief explanation of drawings]

FIG. 1 is a schematic side view showing a slider crank mechanism for reciprocating the sealing carriage. FIG. 2 is a sectional view taken along the line -- in FIG. 1. FIG. 3 is a schematic side view showing a cam wheel mechanism for reciprocating a toothed belt for controlling a dancer roller. FIG. 4 is a sectional view taken along the line - - in FIG. 3. 1, 21...Cam wheel, 2, 22...Cam rib, 4...Side wall of housing, 6, 15, 2
3, 25...Cam driven roller, 7...Cam driven lever, 9, 24...Cam slot lever, 10,
27...Slide block, 11...Bore, 14
... Connection rod, 14', 56 ... Sealing carriage, 16 ... Straight track, 17, 18, 33,
34...Cariya, 19, 20, 51, 52...
Track, 26... Axle, 28... Screw, 30
...Cam slot, 35, 41...Bracket,
42...Guide rod, 43...Roller frame,
44...Arm, 46...Toothed belt, 49,5
0... Dancer Laura, 54... Web.

Claims (1)

[Claims] 1. Apparatus for forming transverse seam welds or separate transverse seam welds in tubular or semi-tubular plastic film webs for application also in making bags. The device comprises a transverse welding device, the welding device having a jaw adapted to open and close periodically, and the film web being attached to the jaw when the jaw is open. The transverse welding device further includes a rocker lever, which is obtained from a rotating eccentric cam wheel by means of a cam slot and a slide block. In the seam welding device for transmitting motions in the same or opposite directions to the transverse welding device or film web, the lever is provided with a straight radial track, and the first sliding block is arranged in a longitudinal direction in the track. guided laterally and connected by a common axial pin to a second sliding block, said second sliding block being able to move in a straight sliding track forming the base of a triangle, the sides of said triangle being Defined by the lever in its end positions, the slide track is adapted to be able to move parallel to itself and to be fixed in position on the frame of the machine, one of the slide blocks has a lever connected thereto, which lever remains parallel to itself and is adapted to transmit movement to said welding device or to the film web. Device. 2. An apparatus for forming transverse seam welds or separate transverse seam welds in tubular or semi-tubular plastic film webs, for application also in making bags, the apparatus comprising: comprises a lateral welding device, the lateral welding device having a jaw adapted to open and close periodically, the film web being moved intermittently between the jaws when the jaw is open. The transverse welding device further includes a rocker lever which, by means of a cam slot and a slide block, provides a co-directional or The seam weld forming device transmits a movement in the opposite direction to the transverse welding device or the film web, wherein the lever has a straight radial track on which a sliding block is slidable longitudinally. , the axle of said sliding block is mounted in a carrier, said carrier guided in a machine frame and slidable longitudinally while remaining parallel to itself; A mounting part provided therein is adapted to be movable transversely with respect to the direction of movement of the carrier and fixed in position, and the mounting part is arranged at both end positions of the lever. The carrier is movable along the base of a triangle with sides defined by levers, said carrier having a lever connected thereto which remains parallel to itself and directs the movement to said welding device or A seam weld forming device characterized in that it is configured to transmit information to a film web. 3. The device according to claim 1 or 2, wherein the triangle defined by the levers at both end positions thereof is isosceles. 4. said lever consists of a link, via which an axle supporting said sliding block is connected to a carriage, which carriage is movable along said web and supporting said welding device; An apparatus according to claim 1 or 3, characterized in that: 5. The slide track has guide holes and is slidably attached to and fixed to the rods, and these rods pass through the guide holes of the slide track and are fixed to the machine frame. The first claim characterized in that
3. The device according to paragraph 3, paragraph 4. 6. A drive device is provided to replace the slide track along the guide rod,
or the device according to any one of paragraphs 3 to 5. 7. Any one of claims 1 or 3 to 6, characterized in that the length of the link is increased or decreased depending on the position of the slide track. Apparatus according to paragraph 1. 8 said lever is connected to a toothed belt or similar element adapted to move the two dancer rollers up and down in opposite directions;
Two dancer rollers are mounted on the roller frame in two mutually parallel tracks for vertical movement, and the toothed belt is attached to the film so as to form the transverse seam weld. 3. The apparatus of claim 2, wherein the web is intermittently held in a predetermined position between the dancer rollers. 9. A screw operable by a drive device,
9. Device according to claim 2, characterized in that it is provided for adjusting a mounting in a bracket. 10. The bracket is slidably mounted on guide rods, the guide rods being parallel to each other.
9. The apparatus according to any one of the following paragraphs. 11 The lever consists of a two-armed lever, one arm equipped with cam driven rollers, which are adapted to be rotated by a cam, and the other arm equipped with a cam driven roller. 11. Apparatus according to any one of claims 1 to 10, characterized in that the device comprises the slide track for the purpose of the invention. 12. One arm supports two cam follower rollers which engage the rotating eccentric cam rib on opposite sides of the cam rib. 11th
Apparatus according to any one of the clauses.