FR2625945A1 - DEVICE FOR STACKING BAGS IN A SYSTEM FOR MANUFACTURING BAGS OR BAGS, ETC. IN THERMOPLASTIC MATTER - Google Patents

Abstract

Device for stacking bags in an installation for manufacturing bags in thermoplastic material, comprising a table 40 distant from the welding jaws 29, 30 at the upstream end 41 of which hang the upstream ends 51 of the bags 2, a device 50 for separating the upstream end 51 of the latter bags 2 cut out while the weld lines 5 are cooling, consisting of rods 52 for separating bags 2 sliding in endless lateral guide paths 54, driven in a part of the path 58 by means of their own weight and raised in the other part of the path 57 by a mechanism 64, 65, and comprising a device for holding the bags 2 on the stacking table 40 including a flap 43 and a holding bar 45.

Description

Device for stacking bags in an installation for manufacturing bags or sachets, etc. in thermoplastic material.

 The present invention relates to a device for stacking bags in an installation for manufacturing bags from a flattened thermoplastic sheath, installation in which the bag is welded at both ends.

 Installations of this kind are known and include two pairs of welding jaws arranged on either side of the cutting mechanism, the pair of jaws located upstream serving to make the bottom welding of the bag and the pair of jaws downstream used to weld the top of the bag.

 French document 2,519,902 describes such an installation capable of making double welds or bottom line welds as desired, but it does not explain the operation of the bag stacking device during the production of bags having welds double.

 French document 2,150,165 also shows an apparatus intended to constitute bags welded at both ends in which the stacking is done by welding the upper end of the last bag made with the bag located immediately above the stack.

 The disadvantage of the solutions known to date is that, after cutting, the bags are stacked with their weld lines which overlap perfectly. The bags tend to weld together at the right of these weld lines, which have not had time to cool. This is particularly true of the downstream welding line of the cut bag which undergoes a very slight movement after cutting and the phenomenon is accentuated with the production rate obtained today.

 The object of the present invention is to eliminate this drawback and to propose a device for stacking bags welded at both ends in which the upstream ends of the last cut bags are separated from each other for the time necessary for cooling # the upstream weld line of the bag.

According to the invention, the object is achieved because the stacking device comprises
- a fixed stacking table located under the travel path of the sheath and disposed upstream of the second pair of welding jaws and, at a certain distance from said second pair of jaws, so that the upstream end of the last cut bag is likely to fall and hang at the upstream end of said table,
- a system for separating the upstream ends of the last cut bags, disposed upstream of the second lower sealing jaw, below the path of travel of the sheath and partially below the upstream end of the table and capable of separate the weld lines from the upstream ends of the last cut bags for the time necessary for the cooling of these weld lines, and
- a device for holding the stack of bags already made up on the table.

 According to a feature of the invention, the separation system of the upstream ends of the last cut bags consists of parallel sticks and arranged transversely, the lateral ends of which are provided with rollers guided by two endless parallel guide paths and arranged laterally to the installation, said guide paths having two parts, a first part of a path located downstream in which the sticks can move by gravity and a second part of a path located upstream in which the sticks are raised to said first part by at least one pair of parallel fingers fixed laterally on a transverse shaft synchronized with the operating cycle of the installation, all the sticks except one at least being held in the upper part of the first part of the path by a stop stop which releases the nearest stick when said fingers raise the stick released in the previous cycle, the b rods located in the upper part being positioned in such a way that they are likely to separate the upstream ends of the last cut bags, the upstream ends of the other bags of the pile resting on the stick closest to the stop stop.

According to another characteristic of the invention, the device for holding the stack of bags already formed on the table consists, on the one hand, of a flap pivotable around a trjnsversal -inférieur shaft controlled by a second control member , flap located downstream of the second lower welding jaw, dimensioned in such a way that it does not hinder the movement of the sheath and the movement of the sticks and that
the upper end of said flap is capable of pressing the stack of bags against the upstream end of the table, said flap being able to take two positions, a first position during the travel of the sheath in which it holds the stack of bags already formed against the upstream end of the table, and a second position during the drawdown of the upstream end of the last cut bag in which the flap does not hinder the movement of drawdown of this upstream end of the bag, and on the other hand, d '' a movable transverse retaining bar located above the table and above the path of the sheath, controlled by a first control member and intended to press the stack of bags and the sheath against the table when cutting the bag and the folding of the upstream end of the last cut bag until said end is maintained by said flap.

 Thanks to this design, the upstream ends of the last cut bags are separated from each other and kept free for the time necessary for the cooling of the weld line. On the other hand, the stack of bags is always correctly positioned on the stacking table by the holding device.

Other characteristics and advantages of the invention will appear in the following description of an embodiment given by way of example and illustrated by the appended drawings in which
FIG. 1 shows a bag provided with carrying handles, front view,
FIG. 2 shows a stack of bags from the installation, seen from the front,
FIG. 3 shows in perspective a stack of bags,
- Figures 4 and 5 are schematic elevation views of vertical longitudinal sections of the installation from the pair of transport rollers, these figures illustrating different working positions of the welding jaws, the cutting device and the device d 'stacking.

 FIG. 1 represents a bag 2 produced in a flattened thermoplastic sheath which comprises a bottom weld line 3, handles 4a and 4b formed by the two faces of the flattened thermoplastic sheath welded together according to the weld lines Sa and 5b . The bag 2 of FIG. 1 comes from a stack (6) of unopened bags (FIGS. 2 and 3) welded at both ends by weld lines 3 and 5, by removing the parts 7, 8 and 9 according to known methods which are not the subject of the present invention. It is advantageous that the bags of a stack are welded to each other according to a weld segment 10 situated at the level of the part 8 intended to be removed during the final construction of the bag, and that on the contrary the neighboring unopened bags do not weld together along the weld lines 3 and 5. In what follows we will call bag the unopened bag basic element of the stack 6 of bags.

 An installation for manufacturing bags 2 welded at both ends, from a flattened thermoplastic sheath 20, comprises from upstream to downstream in the direction of travel of the sheath 2 and in a known manner a guide track 21 of the sheath 20 , a pair of step-by-step transport rollers 22, 23 of the sheath 20, a first pair of welding jaws 24, 25, intended to make the bottom weld 3 of the bag 2, a system of cutting 26 of the sheath comprising an upper knife 27 and a lower counter blade 28, a second pair of welding jaws 29, 30, intended to weld the top 5 of the bag 2 and a stacking device 31 of the made-up bags.

 During the first phase of the installation operating cycle, which corresponds to the supply phase of the sheath 20, the upper welding jaws 25, 30 are separated from the lower welding jaws 24, 29, so as to free the path. the sheath 20, and the latter is pinched by the transport rollers 22, 23. During the second phase of the operating cycle, the transport rollers 22, 23 are separated from one other and no longer entrain the sheath 20, the upper jaws 25, 30 press the sheath 20 against the lower jaws 24, 29, so as to make the top weld line 5 of the bag 2 and the bottom line 3 of the bag following during the cutting of the sheath 20 by the knife 27.

 The design of a bag manufacturing installation having a single welding line is described in French patent 2,597,401 and in a patent application filed today by the same author entitled "Bag manufacturing and stacking installation, sachets, etc ... of thermoplastic material ", which can be referred to for more details since the present description will remain limited to the elements necessary for the present invention.

 The second upper weld jaw 30, which corresponds to the blocking pad # described in patent 2,597,401, has on its lower face a transverse weld line 32 constituted in known manner by an electrical resistance wire and the second lower jaw of weld 29 has in the same way a weld line 33 on its upper face, located in the same vertical plane as the weld line 32. These two weld lines 32 and 33 will form the weld line from the top 5 of the bag when the two jaws 29 and 30 will be in contact with each other during the cutting of the bag. The second upper jaw 30 is driven by the first upper jaw 25 with the interposition of a return spring 34. The second lower jaw 29 is movable vertically under the action of the upper jaw 30 and is urged upwards by a spring of reminder not shown. However, since the invention relates only to the stacking device 31, it is not important that the upper jaws and the lower jaws are mobile or fixed and that the cutting knife is horizontal, oblique or vertical.

 As can be seen in FIGS. 4 and 5, the device 31 for stacking the bags 2 comprises a table 40 fixed to the frame of the installation, arranged at a certain distance downstream from the second pair of welds 29, 30, and below the path of the sheath 20. On the upstream end 41 of this table, can come to rest the upper end 42 of a flap 43 keyed on a transverse shaft 44 movably mounted on the frame of the installation by bearings not shown. The pivot shaft 44 of the flap 43 is located slightly downstream of the second lower jaw 29 and in the lower part thereof. The flap 43 is likely to take two extreme positions, a first oblique position (FIG. 4 ) in which the upper end 42 of the flap 43 presses the stack of bags 6 already formed against the upstream end 41 of the table 40, and a second position, practically vertical (Figure 5) in which the space between the flap 43 and the upstream end 41 of the table 40 is free or open so as to allow the upstream end of the last bag 2 being cut to fall and fold around the end 41 of the table 40.

 Above the upstream part of the table 40, in the vicinity of the upstream end 41 thereof and above the sheath 20, there is provided a transverse retaining bar 45 fixed to the free ends of two lever arms parallel 46 extending longitudinally and laterally keyed sur.un shaft 48 located downstream of the installation and mounted movably on the frame by bearings not shown. The retaining bar 45 can take two extreme positions, a first high position (FIG. 4) in which the bar 45 is moved away from the table 40 and frees the travel path of the sheath 20 and a second position (FIG. 5) in which the bar presses the stack of bags and the downstream end of the sheath against the upstream end 41 of the table 40. The flap 43 and the retaining bar 45 constitute the device for holding the stack of bags 6 on the table 40.

 Below the flap 43 and the upstream end 41 of the table 40 is arranged the separation system 50 of the upstream ends 51 of the last cut bags.

 The separation system 50 consists of a plurality of sticks 52 all having the same length, provided at each of their ends with round rollers 53 forcibly mounted on the sticks 52. The sticks 52 and the rollers 53 are preferably manufactured in rigid plastic material. The end rollers 53 of the sticks 52 are intended to roll or slide in two endless and parallel guide tracks 54 arranged on each side of the installation. These guide tracks 54 are constituted in a known manner with U-shaped angles reversed 90 degrees which are fixed to the frame and which have their open face directed transversely towards the median plane of the installation.

When the sticks are in place between the guide tracks 54, they are mutually parallel in the transverse direction of the installation. The length of the sticks is such that their end rollers are arranged in the angles of the two guide tracks 54 and can roll or slide without excessive friction.

 The guide path 54 has an upper point 55 and a lower point 56 which delimit two path parts, the upstream part 57 and the downstream part 58. The upstream part 57 has an almost semi-circular shape and the downstream part 58 has a part upper rectilinear 59 and slightly inclined downstream in which the sticks 52 are intended to separate the upstream ends 51 of the cut bags as seen in Figures 4 and 5, and a lower part called exhaust 60 which comprises downstream an almost vertical portion which is extended by a sloping part directed upstream which joins the upstream part 57 at point 56.

 A shaft 61 driven by the drive shaft 62 of the installation using a toothed belt 63 and pulleys is arranged transversely and mounted on bearings not shown attached to the frame. This shaft is positioned substantially at the center of the circle of the upstream part 57 of the guide path 54. Two parallel pairs of opposite fingers 64 and 65 are fixed perpendicular and laterally to the shaft 61 in the vicinity of the open face of the angles forming the path 54. These fingers 64, 65 have a length slightly greater than the radius of the circle of the upstream part 57 of the guide path.

 A stop stop 70 constituted in a known manner by a ball 70 and a return spring 71 is provided between the rectilinear part 59 and the exhaust part 60 of each of the guide tracks 54. These stop stops are intended to hold the sticks 52 in the rectilinear part 59 and to let escape the stick 52 located furthest downstream under the action of a force exerted by the fingers 64, 65 in a manner described below.

 The shutter control device 43 is constituted in a known manner by a cam not shown in the form of a butterfly keyed laterally on the shaft 61 of the separation device 50 and driving a roller arranged at the end of a lever arm fixed to shaft 44 against a return spring. Likewise, the control device for the retaining bar 45 is composed of a second butterfly-shaped cam keyed laterally on the shaft 61 and driving a roller arranged at the end of a lever arm fixed to tree 48.

 The device operates as follows. At each operating cycle, that is to say at each revolution of the drive shaft 62 of the installation, the shaft 61 makes a U-turn as seen in FIG. 4 during the scrolling of the sheath 20, the lower fingers 64 drive upwards the stick 52a located at point 56 of the guide path 54, in the upstream circular part 57 in the clockwise direction. At the same time, the upper fingers 65 press the stick 52b against the line of sticks 52c to 52f located in the rectilinear upper part 59 of the guide path. The stick 52f compresses, the ball 70 and the spring 71 which has the effect of releasing it. The stick 52f descends into the exhaust part of the guide path 54 and comes to assume the position that the stick 52a had at the start of the operating cycle. Meanwhile, the end 42 of the flap 43 holds the stack 6 of bags already formed against the upstream end 41 of the table 40, and the retaining bar 45 is moved away from the table 40 and lets the sheath 20 run freely.

 As can be clearly seen in FIG. 5 during the cutting of the next bag, the holding bar presses the stack of bags and the upstream end of the bag being cut and the flap 43 is folded against the upstream lower jaw 51. in order to allow the end of the bag 2 during cutting to fall, after cutting and during the raising of the upper jaws of welding under Inaction of its own weight and of an air flow coming from a nozzle 80 disposed above and downstream of the upper jaws and come to rest on the stick 52b. After the last cut bag is folded down, the stick 52a comes to take the place occupied previously by the stick 52, the flap 43 folds down again on the end 41 of table 40, the holding arm is raised, the stick 52f takes the place occupied at the start of the cycle by the stick 52a and the fingers 64 and 65 have reversed positions. The system is ready for the next cycle.

 As is easily understood, the upstream end 51 of the cut bag 2 is between the two sticks 52a and 52b. As the latter have diameters smaller than the end rollers 53, the upstream end 51 of the bag 2 is not clamped between the sticks 52a and 52b.

 The separation device 50 is positioned at a height such that the distance between the rectilinear part 59 and the upstream end 41 of the table 40 is less than the distance between the upstream end 41 of the table 40 and the cutting position of the bag, and is positioned horizontally so that the position of the stick 52b is vertical to the upstream end 41 of the table 40 or slightly upstream of this vertical.

 It should be noted that the position of the pivot axis of the flap 43 is calculated in such a way that it does not hinder the movement of the sticks 52, and of the fingers 64 and 65 and that the end 42 of the flap 43 does not hinder scrolling of the sheath and does not touch the sheath during its tilting.

 The number of sticks 52 is such that when the sheath 20 is scrolled as shown in FIG. 4, there is only one stick 52 outside of the path part 59, and the length of the fingers 64 and 65 is such that when the upper finger 65 presses the stick 52b against the stick line 52c to 52f, there is only one stick which escapes in the exhaust part of the guide path 53.

The number of sticks 52 defines the number of bags 2 of which
The upstream ends 51 do not touch, thus avoiding contact of the weld lines 5 of these bags during the cooling of their weld lines 5.

 The drawing shows an embodiment comprising six sticks 52 allowing 4 bag ends 2 to be separated for the duration of four operating cycles, the upstream ends of the other bags coming to rest on the downstream part of the stick 52f.

 It goes without saying that this number can be increased or decreased depending on the size of the raceway 54, the size of the rollers 54 and the length of the fingers 64 and 65.

 Likewise, the number of pairs of fingers can be increased or decreased. What matters is that they are regularly distributed on the tree 61.

 The resistor 81 can be installed on the upper end of the flap 43 which presses on the stack of bags. The advantage is that the heating time being longer, the intensity of the current can be reduced.

 The retaining bar can be provided transversely and over a certain length with a resistor 81 intended to form the partial weld line 10 shown in FIGS. 2 and 3. These weld lines being intended to glue the bags of the stack together .

 The invention is not limited to the embodiment described by way of example and it is possible to make various modifications to it without departing from the protective framework defined by the appended claims.

Claims (9)

 1. Device for stacking bags in a plant for manufacturing bags from a thermoplastic sheath, device provided downstream of the welding jaws (29, 30) and of the cutting mechanism (20) and characterized in that it includes: - a fixed stacking table (40) located under the travel path of the sheath (20) and disposed upstream of the second pair of welding jaws and at a certain distance from said second pair of jaws of such so that the upstream end (51) of the last cut bag (2) is capable of falling and hanging from the upstream end (41) of said table (40), - a system for separating (50) the upstream ends ( 51) of the last cut bags (2), disposed upstream of the second lower welding jaw (29) below the path of travel of the sheath (20) and partLlement below the upstream end (51) of the table (40) and capable of separating the weld lines (5) from the upstream ends (51) of the last dec bags oupés (2) for the time necessary for the cooling of these weld lines (5) and, - a holding system (43,45) of the stack of bags (6) already formed on the table (40).  2. Bag stacking device according to claim 1, characterized in that the separation system (50) of the upstream ends (51) of the last cut bags (2) consists of sticks (52) parallel arranged transversely whose ends side are provided with rollers (53) guided by two endless guide paths (54) parallel and arranged laterally at installation, said guide paths (54) having two parts, a first part of path (58) located downstream in which the sticks (52) can move by gravity and a second part (57) located upstream in which the sticks (52) are raised towards said first part (58) by at least one pair of parallel fingers (64,65 ) fixed laterally on a transverse shaft- (61) # synchronized with the operating cycle of the installation, all the sticks (52) to  with the exception of at least one (52a) being retained in the game  upper (59) of the first part (58) -way by a stop stop (70) which releases the nearest stick (52f) when said fingers (64) raise the stick (52a) released in the previous cycle, sticks (52b, 52f) located in the upper part  (59) being positioned in such a way that they are capable of separating the upstream ends (51) of the last cut bags  (2), the upstream ends of the other bags resting on the stick closest to the stop stop (70).  3. Bag stacking device according to claim 1 or 2, characterized in that the holding device (43,45) of the stack of bags (6) already formed on the table comprises: - on the one hand, a flap (43) pivotable around a lower transverse shaft (44) controlled by a second control member, flap (43) located downstream of the second lower welding jaw (29), dimensioned in such a way that it does not interfere not the scrolling of the sheath (20) and the displacement of the sticks (52) and that the upper end (41) of said flap (43) is capable of pressing the stack of bags (6) against the upstream end (41) of the table (40), said flap (43) being able to take two positions, a first position during the travel of the sheath (20) in which it holds the stack of bags (6) already formed against the upstream end (41) of the table (40), and a second position during the folding down of the upstream end (51) of the last cut bag (2) in which the flap (43) does not does not interfere with the folding movement of this upstream end (51) of the bag, and - on the other hand, a transverse bar (45) for movable holding located above the table (40) and the path of travel of the sheath (20), controlled by a first control member and intended to press the stack of bags (6) and the sheath (20) against the table (40) when cutting the bag (2) and folding the end upstream (51) of the last cut bag (2) until said end (51) is held by said flap (43).  4. Bag stacking device according to claim 3, characterized in that the holding bar (45) is provided transversely and over a certain length with a resistance (81) intended to weld the bags (2) of the stack bags (6) between them.  5. Bag stacking device according to claim 2, characterized in that the second part (57) of the guide path (54) has the shape of a semicircle, the transverse shaft (61) is positioned at center of this circle and the fingers (64,65) have a length greater than the radius of the circle.  6. Bag stacking device according to claim 2, characterized in that the upper part (59) of the first part of the path is rectilinear and slightly inclined downstream.  7. Bag stacking device according to claim 6, characterized in that the distance between the rectilinear part (59) and the upstream end (41) of the table (40) is less than the distance between the end upstream (41) of said table (40) and the bag cutting position.  8. A stacking device according to claim 3, characterized in that the upper end of the flap (43) comprises a resistance intended to weld the bags together.  9. Stacking device according to claim 2, characterized in that the number of pairs of fingers is equal to 2.