CA2161833A1

CA2161833A1 - Device for welding carrying handles onto a semitubular plastic film web

Info

Publication number: CA2161833A1
Application number: CA002161833A
Authority: CA
Inventors: Konrad Tetenborg; Friedhelm Mundus; Hans-Ludwig Vos
Original assignee: Individual
Current assignee: Windmoeller and Hoelscher KG
Priority date: 1994-11-03
Filing date: 1995-10-31
Publication date: 1996-05-04
Also published as: ITBZ950069A1; ES2127668B1; ES2127668A1; ITBZ950069A0; IT1282446B1; JPH08207139A; BE1010535A3; DK119995A

Abstract

The invention pertains to a device for welding carrying handles onto a semitubular plastic film web, with a carrying handle forming station and a welding station that is provided with welding jaws that can be moved against the semitubular plastic film web from the outside in order to weld together the ends of the carrying handle and the semitubular plastic film web. In order to attain the objective of additionally developing a device of this type in such a way that the welding time is reduced and the production capacity is correspondingly increased, additional welding jaws that lie inside of the semitubular plastic film web and cooperate with the externally arranged welding jaws are arranged in the welding station.

Description

216183~

DEVICE FOR WELDING CARRYING HANDLES ONTO A SEMITUBULAR
PLASTIC FILM WEB

The invention pertains to a device for welding carrying handles onto a semitubular plastic film web.
One device of this type is already known. This known device comprises a carrying handle forming station and a welding station with welding jaws that can be moved against the semitubular plastic film web from the outside in order to weld together the ends of the carrying handle and the semitubular plastic film web. In this known device, the welding process is carried out exclusively from the outside, i.e., from the top and the bottom by means of welding jaws. This means that the pairs of carrying handles need to be treated with a separating agent so as to prevent the pairs of carrying handles from being welded together during the welding process. In addition, a comparatively long time is required for each welding process.
The invention is based on the objective of further developing a device of the initially mentioned type in such a way that the welding time is reduced and the production capacity can be correspondingly increased. In addition, the invention intends to eliminate the utilization of a separating agent.
According to the invention, this objective is attained by providing the welding station with additional welding jaws that lie inside of the semitubular plastic film web and cooperate with the externally arranged welding jaws. Due to this measure, each end of the carrying handle can be welded together with the corresponding wall of the tubular plastic film web in a significantly shorter time because the heat required for the welding process is introduced on both sides. In addition, the application of a separating agent is eliminated because the respective welding jaws lie between the corresponding ends of the carrying handles.

In a first preferred embodiment, the additional welding jaws are arranged on a plate that can be positioned inside of the semitubular web by means of a holder and an arm.
In a second preferred embodiment, the plate on which the additional elements are arranged carries an additional winding and unwinding mechanism for a strip, for example of Teflon (trade mark) that can be arranged over the additional welding jaws. Two reversing rods are provided to guide the strip, and are arranged above the plate and the additional welding jaws.
In a third preferred embodiment two superimposed film reels are provided in a frame in the carrying handle forming station. Two superimposed plastic film webs are unwound from these reels by means of a pair of advancing rollers. A cutting station cuts the advanced plastic film from the superimposed rollers into strips, and a carriage, provided in a frame which is longitudinally guided and also accommodates rotatable and moveable plungers which take hold of the plastic strips, thereby to form the strips into a handle, and to guide this handle into the welding station.
In these preferred embodiments, it is simultaneously ensured that both free ends of the pair of carrying handles are conveyed over the additional inner welding jaws in such a way that the respective parts of the carrying handle can be securely welded together with the side walls of the semitubular film.
To this end, laterally protruding arms can be provided fitted with fork elements which are longitudinally guided in the frame, the fork elements being arranged to position the leading end of the unwound plastic film web in the cutting station. Further, a transfer strap connected to one of the plungers can be pivoted in the fork elements, with the plastic strips lying on both sides of the transfer strap after the fork element is retracted, and after the plastic strips are cut.
Additionally, additional guide plates can be provided, arranged laterally of the plate that carries the additional welding jaws, which guide plates are attached to the holder.

One side of the additional guide plates ends in the shape of a wedge, such that they are able to engage with the transfer straps that are provided with a corresponding slot so that when the corresponding rotary plunger is pivoted, the free ends of the plastic film webs are displaced from the transfer strap to the guide plate, and from the guide plate to the welding jaw by additional rotation of the rotary plunger.
Additional details and advantages of the invention are described below with reference to one embodiment that is illustrated in the figures. The figures show:
Figure 1: a partial top view of one embodiment of the device according to the invention which shows the main section of the carrying handle forming station, Figure 2: a top view of an additional part of the described embodiment of the device which primarily shows the welding station, Figure 3: a section along the line III-III in Figure 1, Figure 4: a partial top view of the welding station illustrated in Figure 2 (view IV in Figure 6), Figure 5: the detail according to Figure 4 in the form of a bottom view (view V in Figure 6), Figure 6: a section through Figure 2 along the line VI-VI, Figure 7: a section along the line VII-VII in Figure 2, Figure 8: a section along the line VIII-VIII in Figure 2, Figure 9: a section along the line IX-IX in Figure 1, Figure 10: a detailed representation of the lower rotary plunger of the carrying handle forming station in the form of a slde v1ew, Figure 11: a view of the detail viewed in the direction of the arrow XI in Figure 10, Figure 12: a section along the line XII-XII in Figure 10, and Figure 13: a side view of the upper rotary plunger of the carrying handle forming station of the embodiment illustrated in the figures.

Figure 2 shows a semitubular plastic film web 10 with a bottom fold 12 which has two folded edges 14, 16 and is transported in the direction of the arrow A. In the illustration according to Figure 2, the upper side wall of the semitubular film 10 was partially omitted such that part of a welding station 18 is visible. This part of the welding station 18 is situated between the side walls of the semitubular film 10. This part of the welding device 18 is carried by an arm 20 that is laterally guided on a lateral frame 22 in a guidance 24 as shown in Figure 1 and can be displaced via a piston/cylinder unit 26. A holder 28 that is aligned parallel to the lateral end of the semitubular film 10 is welded perpendicularly onto the arm 20. A plate 30 is attached perpendicularly onto said holder in a plane that extends between the side walls of the semitubular film. The heated opposing welding jaws 32 and 34 are attached onto the plate 30, with the welding contours 36 and 38 being visible on said welding jaws. Guide plates 40 and 42 are arranged on the holder 28 adjacent to the plate 30 and the welding jaws 32 and 34. The free ends of these guide plates comprise respective guide ramps 44 and 46, the function of which is described below. In Figure

2, the upper carrying handle 48 of a pair of carrying handles is illustrated in a position in which said carrying handle is welded together with the semitubular film 10 inside of the welding station 18 by the cooperation between the welding jaws 32 or 34 and the welding jaws, not shown, that are situated on the outside.
Figure 1 shows the part of the device that is situated adjacent to the part illustrated in Figure 2. The pair of carrying handles is essentially formed and transferred to the welding station 18 in this part of the device. In Figure 1, the lateral frame 22 is connected to the lateral frame 52 via a crossbeam 50. Mechanically driven cam plates 54, 56 or 58, 60 revolve in the lateral frames 22 and 52. Two respective superimposed guidances 62 and 64 are arranged parallel to the lateral frames 22 and 52. Protruding arms 66 and 68, the free ends of which respectively end in a fork element 70, 72, are arranged in a movable fashion in said guidances 62 and 64. The displacement of the protruding arms along the two superimposed guidances is realized via the driven cam plates 54 and 56.
In addition, carriages are guided on the superimposed guidances 62 and 64 that lie on top of one another, with this figure showing the upper carriage 74 that can be moved back and forth via the cam plates 58 and 60.
Two superimposed film reels are arranged inside of the frame, with only the film reel 76 being illustrated in this figure. Two superimposed films 80 are unwound from these film reels via a pair of advancing rollers, of which only the upper advancing roller 78 is illustrated in this figure. These films are respectively conveyed over the fork elements 70 and 72 such that the two superimposed films cover the fork elements 70 and 72 in a sandwich-like fashion. When advancing the film webs 80, the fork elements 70 and 72 are also moved forward until the leading end of the film webs 80 is situated in a cutting station 82. This cutting station 82 consists of a lower knife 84 that is rigidly connected with the frame, and an upper knife 86, that can be moved relative to the aforementioned lower knife 84, is guided in guidances 88 and can be displaced via piston/cylinder units 90.
Upper rotary plungers 92 are arranged in the carriage 74 such that they can be moved along the dot-dash lines 94--the guidance along the dot-dash lines 94 are described below. In this case, the rotary plungers are simultaneously displaced inside of grooves 96 that are machined into the carriage 74 shown in Figure 2. During the displacement of the upper rotary plungers 92 which, due to the displacement of the carriage and the corresponding restricted guidance, move along the curved path 94, corresponding toothed wheels 98 of the upper rotary plungers 92 roll along a toothed rack 100 that is rigidly connected with the carriage 74 via a holder 102 such that the upper rotary plungers are pivoted in the direction of the arrow during a movement of the upper carriage 74. The same also applies to the lower rotary plungers that are not illustrated in detail in this figure.
The design of the upper and lower rotary plungers is elucidated below with reference to Figures 10-13. The design of the upper rotary plunger 92 is illustrated in detail in Figure 13. This upper rotary plunger runs in a groove 96 of the upper carriage 74. The toothed wheel 98 meshes with a toothed rack 100. The upper free end of the upper rotary plunger 92 is guided in a plate 104 in which the curved path 94 is defined.
The opposite end of the rotary plunger 92 is provided with a rubber coating 106.
One lower rotary plunger 108 is illustrated in Figure 10.
This rotary plunger 108 also extends in a groove 110 of a carriage 112. It comprises a toothed wheel 114 that meshes with a toothed rack 116. The lower free end of the lower rotary plungers 108 is guided in a guide groove 118 of a rail 120 that is rigidly connected to the lateral frame. The progression of this guide groove 118 is illustrated in Figure 12 which represents a view in the direction XII-XII of Figure 10. The progression of the guide groove 118 corresponds to the dot-dash line 94 in Figure 2. A transfer strap 122 that comprises a stop pin 124 is connected with the rotary plunger in a rotatable fashion. A stop pin 128 is also arranged on the head 126 of the lower rotary plunger 108. The transfer strap is spring-loaded via a flat spiral spring 130 such that the pin 124 adjoins the pin 128. This measure makes it possible to move the transfer strap 122 in one rotating direction against the force of the spiral spring 130. Figure 11 shows a view of the lower rotary plunger 108 in the direction of the arrow XI in Figure 10. In this case, identical components are identified by identical reference numerals. Figure 11 shows that the upper limb of the transfer strap 122 is provided with a slot 132, the function of which is elucidated below. Figures 10 and 11 show both plastic film webs 80 that are unwound from the supply reels 76.

The cooperation between the fork elements 70, 72 and the rotary plungers 92, 108 is explained in detail below with reference to Figure 3. This figure shows a pair of advancing rollers 78, 78'. These two advancing rollers unwind two plastic film webs 80 from the two supply reels 76 that are not illustrated in detail in this figure. These unwound plastic film webs 80 move the fork elements 70, 72, of which only the fork element 72 is illustrated in the figure, forward until the fork of the fork element 72 overlaps the upper limb of the transfer strap 122 as shown in Figure 3. We refer to the description of Figures 10 and 11 with respect to the design of the lower rotary plunger 108. Figure 10 represents a view in the direction of the arrow X in Figure 3. Figure 13 represents a view in the direction of the arrow XIII in Figure 3. This figure shows the upper rotary plunger 92. Figure 3 also shows the rigid lower knife 84 of the cutting station as well as the movable upper knife 86 of said cutting station. After the film webs 80 and the fork element 70 or 72 were moved into the position shown in Figure 3, the fork element 70 or 72 is retracted such that the position illustrated in Figures 8 and 9 is attained. The upper knife 86 is now moved downward inside of the cutting station such that two strips are cut off from the front end of the film webs 80 in cooperation with the lower knife 84 that is rigidly connected with the frame. These two strips are subsequently deposited onto the upper limb of the transfer strap 122. Figure 8 corresponds to the line XIII-XIII
in Figure 1 and Figure 9 corresponds to the line IX-IX in Figure 1. Figure 9 shows that the strips that were cut off from the plastic film webs 80 are clamped between the upper rotary plunger 92 and the lower rotary plunger 108 within the region in which said strips do not lie on the upper limb of the transfer strap 122.
The carrying handle 48 illustrated in Figure 2 is formed of the strip that was cut off from the plastic films 80 and is aligned in a straight fashion by turning the upper rotary plunger 92 and the lower rotary plunger 108. During this turning motion, the free ends of the carrying handle lie on the upper limbs of the transfer straps 122 which are turned simultaneously with the lower rotary plunger 108. When turning the transfer straps 122, an incision 132 in said transfer straps comes in contact with the wedge 44 or 46 of the guide plates 40 and 42 such that they are prevented from turning additionally and retained against the force of the spring 130 while the rotary plunger 108 continues to turn. Due to the fact that the plastic strips 80 are clamped between the rotary plungers 92 and 108, said plastic strips are pivoted additionally, namely over the guide plates 40 and 42 until they come in contact with the welding contours 36 and 38 of the welding jaws 32 and 34. The free ends of the pairs of carrying handles 48 can be welded together with the semitubular film 10 in this position. In this case, the welding jaws 130 and 132 are moved toward the plastic film webs from the outside as shown in Figure 6. After the welding process, the rotary plungers 92 and 108 are turned back again, with the transfer straps 122 also being returned via the respective limit stops 128 and 124.
Figure 7 once again illustrates in detail how a transfer strap 122 comes in contact with the wedge 44 of the guide plate 40, wherein the slot 132 overlaps the tip of the wedge. In the illustration according to Figure 7, the rotary plungers 92 or 108 have already been turned additionally such that the plastic strips 80 are pushed onto the wedge 44.
Figure 6 shows a section along the line VI-VI in Figure 2. This figure shows a sectional representation of the semitubular film 10 with its bottom fold 12. It can be easily ascertained that the additional welding jaws 36 are arranged on the plate 30 between the folded hem regions 14 and 16 of the semitubular film 10. The additional welding jaws 36 or 38 which are not illustrated in this figure are heated via heating cartridges 134. A Teflon strip 136 is conveyed over the welding jaws. This Teflon strip is unwound from a reel 138 and wound onto a reel 140. The reel 138 and the reel 140 are fastened onto the plate 30 via a holder 142.
The progression of the Teflon strip 136 can be explained with reference to Figures 4 and 5. Figure 4 shows a view in the direction of the arrow IV in Figure 6. The Teflon strip 136 is unwound from the reel 138 in the direction of the arrow and guided around a reversing rod 144 that is arranged on top of the plate 30 in such a way that the Teflon strip is angled by 90 and conveyed over the welding contour 36 of the welding jaw 32 in the direction of the arrow. The Teflon strip is reversed at this location and guided underneath the plate 30 in the direction of the arrow as shown in Figure 5 (Figure 5 represents a view in the direction of the arrow V in Figure 6).
The Teflon strip is conveyed over the lower welding contour 38' of the welding jaw 34, subsequently deflected such that it is conveyed over the welding jaw 34, namely over the contour 38 as shown in Figure 4. The Teflon strip subsequently extends in the direction of the arrow until it reaches the reversing rod 146 where its direction is again changed by 90 such that it wraps around the plate 30 in the direction of the arrow and subsequently to the reel 140 as shown in Figure 5.

Claims

1. Device for welding carrying handles onto a semitubular plastic film web, with a carrying handle forming station and a welding station that is provided with welding jaws that can be moved against the semitubular plastic film web from the outside in order to weld together the ends of the carrying handle and the semitubular plastic film web, characterized by the fact that additional welding jaws which lie inside of the semitubular plastic film web and cooperate with the externally arranged welding jaws are provided in the welding station.

2. Device according to Claim 1, characterized by the fact that the additional welding jaws are arranged on a plate which can be positioned inside of the semitubular web via a holder and an arm.

3. Device according to Claim 2, characterized by the fact that the plate on which the additional elements are arranged carries an additional winding and unwinding mechanism for a Teflon strip that can be conveyed over the additional heated welding jaws, and that two reversing rods, by means of which the Teflon strip can be guided correspondingly, are arranged above the plate between the additional welding jaws.

4. Device according to one of Claims 1-3, characterized by the fact that two superimposed film reels in a frame are provided in the carrying handle forming station, with two superimposed plastic film webs being unwound from said film reels via a subsequently arranged pair of advancing rollers, that a cutting station which cuts the advanced plastic film web into strips is provided, and that a carriage is longitudinally guided in a frame that also accommodates rotatable and movable rotary plungers which take hold of the separated superimposed plastic strips, form said strips into a handle and guide this handle into the welding station.

5. Device according to Claim 4, characterized by the fact that laterally protruding arms with fork elements are longitudinally guided in the frame, with said fork elements being arranged between the plastic film webs that are advanced by means of the advancing rollers and moved forward simultaneously with said plastic film webs in order to position the leading end of the unwound plastic film webs in a cutting station, and that a transfer strap that is connected to one of the rotary plungers can be pivoted into the cutouts of the fork elements, with the plastic strips lying on both sides of said transfer strap after the fork element was retracted and after the plastic strips were cut by the cutting device.

6. Device according to Claim 5, characterized by the fact that additional guide plates are respectively arranged laterally of the plate that carries the additional welding jaws and is attached onto the holder, with one side of said additional guide plates ending in the shape of a wedge such that they are able to engage with the transfer straps that are provided with a corresponding slot when the corresponding rotary plunger is pivoted, with the free ends of the plastic film webs being displaced from the transfer strap to the guide plate and from the guide plate to the welding jaw by turning the rotary plunger additionally.