EP0908384B1 - Apparatus for strapping an article or a group of articles with a thermoplastic strap - Google Patents

Abstract

Part of the first head (1) has two parallel plates (4, 5) in planes perpendicular to head (1, 2) motion. Each has a recess at the centers of the end edges, allowing the strap (F) to pass. The second head has two parallel plates (7, 8), coplanar with the others. During head approach, terminal edges lodge in the plate recesses, blocking the strap. Each plate of the second head (2) comprises two superposed elements, each hinged on the head about an axis perpendicular to head motion, with similar arrangements for the second strap (F'). The recesses come into mutual contact. During approach the housing covers a support (26) against which the strap is flattened. The elements are similarly moveable in the head, under resilient separation force. Preferred features: Each of the elements of the plates of the second head swings on a ring which can move longitudinally to the end of the head, and is pushed back against the end by a spring. A spur, projecting laterally from each of these elements, is engaged in a slot, made in a plate mounted to slide longitudinally in the head, and driven by an actuator. The equipment is further detailed, including the system of levers and the welding unit.

Description

The present invention relates to a device for strapping an object or a group of objects using a strip of thermoplastic material.

We mainly know two categories of devices for strapping an object or a group of objects.

The former implement a process which consists of passing a strip around the object to strapping, then cutting said strip and welding the two ends of it.

They usually have at least one strip packaged in a reel, the end of which is routed around the object to be strapped passing in a tunnel whose internal wall can open to leave pass said strip which, by means of a means tension, is pressed against said object, the strip then being cut and its ends welded.

These devices, which are of simple design and robust, allow a solid strapping with a significant tension, however, they present the downside of needing to change many parts elements when passing a strip of a certain width to another of different width.

In addition, if these devices work for the most automatically, however, they require frequent manual interventions, especially to reboot the passage of the strip through the tunnel.

The second method is to move the object to strapping on a conveyor, or the like, across which is stretched a strip, then, after the passage of said object, to close the loop by cutting and welding said strip.

In practice, two strips are used, the coils are arranged on either side of the conveyor, and whose ends are previously welded, while that after the strapping of the object, two cuts are made and two welds, so as to simultaneously realize the closing the loop and welding the straps for the next strapping. Note that the cutting operation intervenes before the welding operation so that the the two strips are joined together by covering the end of one with the end of the other.

The devices implementing this process usually have two heads, one for each strips, movable in approach and in distance one relative to each other along a transverse axis perpendicular to the axis of movement of the object to be circled.

Maintaining the straps, to be able make cuts and welds while maintaining certain tension, is achieved through a hollow moving part which is inserted between the heads on the end of each of which passes a strip, the cuts and welds being made inside said moving part.

Such devices are notably described in GB-A-1.502.822, EP-A-0.061.805 and US-A-4.209.958, corresponding to the preamble of claim 1.

These devices make it possible to overcome the disadvantages of those implementing the first method, on the other hand they do not allow sufficient tension of the strip.

On the other hand, the device described in the document US-A-4,209.958 does not allow strapping by means straps of different thicknesses, and those described in documents GB-A-1.502.822 and EP-A-0.061.805 show disadvantages in terms of cutting temperatures and welding, which should preferably be different to avoid degradation of the strip, which is not the case for these devices.

The object of the present invention is to provide a device for strapping an object or group objects by means of a strip of thermoplastic material, allowing these various drawbacks to be remedied, allowing in particular strapping with tension important.

The device which is the subject of the present invention allows the strapping of an object or a group objects by the method of moving the object or the group of objects in the direction of two strips, previously welded, stretched transversely in the direction of displacement, and to form a loop around the object or group of objects after the passage of it then to realize a cut and two welds, it has for this purpose at at least two strip reels each incorporating a means strap tension, arranged on either side of a conveyor on which the object or group of objects moves to be strapped, as well as two moving heads in alignment or away from each other along an axis transverse to direction of movement of the object or group of objects to to circle, and who are likely to come into contact with one on the other to achieve, thanks to a welding set and a set of pressing, cutting and welding of said straps, which are also each held by the front face of said heads, namely that of the side where arrives the object or group of objects, and it is characterized basically in that on the one hand the first head comprises at the end two parallel plates arranged in vertical planes parallel to the directions of movement of said heads, and each having in the middle region from their extreme edge a notch for the passage of the strip; and on the other hand the second head has two parallel plates each coplanar with one of the plates the first head, the extreme edge of each of which is likely, when bringing together said heads, come and lodge in the notch of the facing plate so block the strip that passes there, each of the plates the second head being made up of two elements superimposed, each pivoted on said head around an axis perpendicular to the direction of movement of the tjte, so that their opening allows the passage between them the second strip, which takes place in a housing formed, when said elements are brought together one from the other, from two recesses each made in a of said elements, in their edges coming into contact with one of the other when they are brought together, said housing housing a support piece against which an edge of said housing clamps said strip, said elements also being movable in movement in the head in the direction of movement of this, while being elastically pushed back in distance from said head.

According to an additional characteristic of the device according to the invention, the parts of the plates and supporting parts intended to pinch the strips are bevelled.

According to another additional characteristic of the device according to the invention, the parts cut at a bevel present on the surface means capable of catching the straps.

According to another additional characteristic of the device according to the invention, the pressing assembly comprises two levers articulated in pivoting by one of their ends, each around an axis parallel to the face front of the head, recalled to each other by means of a spring, capable of moving to position between the parallel plates of said head, each carrying pivotally at their other end a plate of pressing folded from the outer side against said lever, and kept away from it by means of a spring, while that a means, movable in movement between said levers, allows you to rotate these at different angles so to approximate said pressing plates more or less of said parallel plates for pressing against them the ends of the strips to be welded.

According to another additional characteristic of the device according to the invention, the welding assembly is mobile in movement under the action of a jack to come place between the parallel plates of the head, and there has three heating blades, a central blade and two side blades, which are parallel to the front face of said head, said lateral blades being movable in displacement in the transverse direction, in spacing by relative to said central blade, towards which they are recalled by means of a spring.

The advantages and features of the present invention will emerge more clearly from the description which follows and which relates to the appended drawing, which represents a non-limiting embodiment thereof.

• les figures 1a, 1b et 1c représentent des vues schématiques de dessus illustrant différentes phases du procédé de cerclage mis en oeuvre au moyen du dispositif selon l'invention.
• la figure 2a représente une vue de côté d'une partie du dispositif selon l'invention.
• la figure 2b représente une vue de dessus de la même partie.
• la figure 3a représente une vue de côte d'une autre partie du dispositif selon l'invention.
• la figure 3b représente une vue de dessus de la même partie.
• la figure 3c représente une vue de côté de la même partie lors dans une position différente.
• la figure 4 représente une vue partielle en perspective d'un détail de la partie représentée à la figure 2a.
• la figure 5 représente une vue partielle en perspective d'un détail de la partie représentée à la figure 3c.
• les figures 6a, 6b, 6c, 6d, 6e et 6f représente des vues partielles de dessus du dispositif selon l'invention lors de différentes étapes d'un cerclage.

In the attached drawing:

• Figures 1a, 1b and 1c show schematic views from above illustrating different phases of the strapping process implemented using the device according to the invention.
• Figure 2a shows a side view of part of the device according to the invention.
• Figure 2b shows a top view of the same part.
• FIG. 3a represents a side view of another part of the device according to the invention.
• Figure 3b shows a top view of the same part.
• Figure 3c shows a side view of the same part when in a different position.
• 4 shows a partial perspective view of a detail of the part shown in Figure 2a.
• 5 shows a partial perspective view of a detail of the part shown in Figure 3c.
• Figures 6a, 6b, 6c, 6d, 6e and 6f show partial top views of the device according to the invention during different stages of strapping.

If we refer to Figures 1a, 1b and 1c, we can see different phases of the strapping process of a object A according to the known method implemented by the device object of the present invention.

Object A is placed on a conveyor B moves in the direction of arrow C, it goes under a gantry, not shown, which carries two welding heads 1 and 2 mobiles moving on the gantry, perpendicular to the direction of movement of the conveyor B, in the direction of the arrows R and R 'respectively.

Head 1 is fed by a strip F from of a coil D, while the head 2 is supplied by a strip F 'from a coil E.

As can be seen in Figure 1a, the strips F and F 'have been previously welded so as to to make only one, which extends between the two heads 1 and 2 transversely to the direction of movement of object A on the conveyor B.

The strips F and F 'are kept centered on the front faces, respectively 10 and 20, of the heads 1 and 2, namely the faces opposite which the object A arrives, by means of holding means, respectively 11 and 21, each arranged near the end of each heads 1 and 2.

Note that the coils D and E are each equipped with a tensioning means, respectively G and H, of the strips F and F ', arranged on the gantry, not shown, upstream of heads 1 and 2.

In FIG. 1b, the object A comes into contact with the strip consisting of the welding of strips F and F ′, then, figure 1c, when it has passed beyond heads 1 and 2, the conveyor B stops, heads 1 and 2 move closer along R and R 'to come into contact with each other, to form loop around object A and cut the strips F and F 'as well as two welds, one for maintain the strapping and the other to weld the straps F and F 'for the next strapping.

If we now refer to Figures 2a and 2b, we can see that the welding head 1 has a wall tubular 12 of substantially square section, containing a longitudinal cylinder 13 allowing the displacement of a welding set 3.

The welding assembly 3 comprises three blades of heater, a central blade 30 and two side blades 31 and 32, which consist of plates parallel to the front face 10.

As we can see more precisely on the Figure 2b, the side blades 37 and 32 are movable in displacement in the transverse direction, in spacing by relative to the central blade 30, towards which they are recalled by means of a spring 33.

In a particular embodiment, the side blades 31 and 32 are each integral with a piece U-shaped engaged on a block carrying the central blade 30.

The end 15 of the head 1 has two identical plates 4 and 5, parallel to the front face 10, the plate 4 also being an extension of this last.

As we can see more precisely on the Figure 4, the plates 4 and 5 are square, and their extreme edge, respectively 40 and 50, has a notch, 41 and 51 respectively, substantially V-shaped, having three edges, a central edge, respectively 42 and 52, parallel to the extreme edge 40, 50, and two edges lateral, respectively 43 and 44, and 53 and 54, going in widening towards the extreme edge 40, 50.

The edges 43, 44, 53 and 54 are bevelled from the inner side of plates 4 and 5, while the edges central 42 and 52 are bevelled on the outside, and that they have transverse streaks, respectively 45 and 55, it will be noted that preferably these streaks are practiced on wearing parts, not shown, reported on edges 42 and 52.

If we now refer to Figures 3a, 3b and 3c, it can be seen that the head 2 has a tubular wall 22 of square section, containing a longitudinal cylinder 23 for moving a pressing assembly 6.

Head 2 has two plates at its end 7 and 8 identical, parallel to the front face 20, the plate 7 is also an extension of the latter.

Plate 7, respectively 8, is divided into two elements 70, respectively 80, each articulated in swiveling on the head 2 so as to take two positions, each shown in Figures 3a and 3c, to know respectively, an open position and a position closed.

If we also refer to Figure 5, we can see plate 8 when the elements 80 are in the closed position.

The elements 80 each have an edge straight 81, a front edge 82 perpendicular to the edge straight 81 and bevelled on the internal side of the plate 8, and a side edge 83 bevelled on the outer side of the plate 8 and making an angle with the straight edge 81.

The straight edges 81 have at a certain distance from the ends of the elements 80, a recess 84 comprising on the side of the front edge 82 and parallel to this, a beveled edge 85 on the side internal, symmetrical with respect to the edge bevel frontal 82.

In the closed position, the straight edges 81 come into contact with each other, and the recesses 84 create housing 86, while the general shape of the plate 8 thus formed allows the embedding thereof in the notch 51 of the plate 5 of the head 1, so that the bevels of the front edges 82 can come in close contact with the beveled central edge 52 of the notch 51 and which forms the basis thereof, while the bevelled side edges 83 come into contact with edges 53 and 54 which hold the plates 80 firmly.

Note that the front edge 82 and the edge 85 have transverse ridges, 820 and 850, which can also be practiced on wear parts reported.

Note also that plate 7, not represented in FIG. 5, is identical to plate 8, only visible in FIG. 3b is a front edge beveled 72 and the beveled edge 75 of a housing 76 shown in broken lines.

In Figures 3a and 3c, we can see the means for rotating the elements 80, knowing that these means are identical to those allowing the pivoting of the elements 70, not visible in these figures.

Each of the elements 80 is pivotally mounted on a ring 87 capable of moving longitudinally at the end of the head 2, and pushed into abutment towards this end by a spring 88, while a lug 89, making laterally projecting from each of the elements 80, is engaged in a non-rectilinear slot 24, formed in a plate 25 slidably mounted longitudinally in the head 2 and driven by the jack 23.

When the actuator 23 is pushed, plate 25 moves towards the end of the head 2, and the lug 89 guided by the slot 24, drives the element 80 which carries it.

Head 2 also has at its end two support pieces 26, only one of which is visible on the Figure 3a, each arranged between the elements 7 and the elements 8, having a beveled edge 27 on the external side, not visible, same inclination as that of the edges bevelled 75 and 85 of the housings 76 and 86 respectively, and with transverse streaks.

When elements 7 and elements 8 are in closed position, the bevelled edges 27 of the support pieces 26 are each opposite one of the bevelled edges 75 and 85, parallel to these and at a certain distance this the latter being maintained under the effect of the springs 88.

If we now refer more specifically to the Figure 3b, we can see that the pressing assembly 6 comprises between the plates 7 and 8 two levers 60 and 61 pivotally articulated by one of their ends each around an axis, not visible, parallel to plates 7 and 8, and called back to each other by means of a spring 62, while on their other end is articulated a plate of pressing, respectively 63 and 64, folded outwardly against the lever, respectively 60 and 61, and held separated from it by a spring, respectively 65 and 66.

On the other hand, the end of the rod 230 of the cylinder 23 carries a cam 67 for controlling the pivoting of levers 60 and 61, which each have for this purpose a bearing, respectively 600 and 610, which remains in contact of cam 67, which has three parts of width different, an extreme part 670, a part intermediate 671 narrower than part 670, and a part 672 wider than part 670.

Note that head 2 also has a block 231 secured to the rod 230 of the jack 23, and a block 250 carrying the plates 25, which are integral with the axes of pivoting of the levers 60 and 61, and mounted sliding on the rod 230, the blocks 231 and 250 being capable of sliding in the head 2, the displacement of the block 250, in view the closure of elements 7 and 8, being provided by two springs 251 interposed between blocks 231 and 250, the stroke of the block 250 being limited by a stop, not visible.

If we now refer to Figures 6a, 6b, 6c, 6d, 6e and 6f, we can see how the device according to the invention.

Before the heads 1 and 2 are brought together, elements 70 and elements 80 have come together to form the plates 7 and 8, the strip F 'is thus engaged in housings 76 and 86, against support pieces 26 without being kept there, while the strip F goes into the notches 41 and 51 against the central edges 42 and 52.

When plates 7 and 8 fit into the notches, 41 and 51 respectively, the bevelled edges 72 and 82 tighten the strip F against the beveled edges 42 and 52, while the springs 88 are compressed so that the strip F 'is squeezed between the edges bevelled 27 support pieces 26 and bevelled edges 75 and 85, as can be seen in FIG. 6a.

The blocking of the strips F and F 'is thus realized while these are kept energized by the tensioning means G and F, not visible.

If we refer to Figure 6b, we can see that under the action of the jack 13, not visible, all of welding 3 moves between plates 4 and 5 and the plates 7 and 8, while the heating blade 30 cuts successively the strip F and the strip F ', and that the heating blades 31 and 32 each fold down when heated one end of the strip F against the plates, 7 and 8 respectively.

In FIG. 6c, under the action of the jack 23, not visible, the pressing assembly 6 moves to come stop, so that the pressing plates 63 and 64 fold each end of the strap F 'on the heating blades 31 and 32 respectively, while made by the thrust of the jack 23, the cam 67 moves and its part 670 is inserted between bearings 600 and 610, causing the spacing of the levers 60 and 61, so that the pressing plates 63 and 64 press the ends of the strip F 'against the heating blades 31 and 32 which, under push, move away from each other and tighten the ends of the strip F against the plates 7 and 8, while also heating the ends of the strip F '.

In FIG. 6d, the jack 23 continues its thrust, cam 67 moves and bearings 600 and 610 engage in part 671 thereof, under the effect of spring 62 the levers 60 and 61 approach one of the other and the support plates 63 and 64 deviate from the end of the strap F ', which allows the retraction of the welding assembly 3, under the action of the cylinder 13, FIG. 6th.

In FIG. 6f, the jack 23 continues its thrust, cam 67 moves and bearings 600 and 601 roll on the 672 part of it, so that the levers 60 and 61 move away from each other and that the support plates 63 and 64 crush the ends of the strip F 'on those of strip F against the plates 7 and 8, while the welds can be cooled by compressed air distributed by means not shown.

Heads 1 and 2 can then move apart on the other, and plates 7 and 8 open, object A is then circled and the strips F and F 'welded, ready for the following strapping operation.

Note that the welding assembly 3 can also be housed in head 2 while the entire pressing 6 is housed in head 1.

On the other hand, the welding operation by temperature rise can be replaced an operation ultrasonic bonding or friction welding.

According to another embodiment, not shown, of the device according to the invention, the head 2 has two cylinders, a first to control closing plates 7 and 8, and a second to control the assembly 6. The second cylinder has at the end of its rod a cam having a body whose end is bevelled, so that the pressing phase shown on Figure 6c is obtained when the bearings 600 and 601 roll on said beveled end during a push partial of the second cylinder, while the following phase, shown in Figure 6d is achieved by a decline in the cam, and that the last phase, shown in Figure 6e is achieved by a new advance of said cam under the action of a complete push of the second cylinder which engages the cam body between bearings 600 and 601.

The device which is the subject of the present invention has many advantages over devices existing. In addition to the great tension obtained due to the locking means used and constant tension before blocking, all types of straps can be used, not only whatever their width, but also whatever their thickness. Indeed, the means of blocking of strips adapt to the thickness of these, while the pressing plates 63 and 64 allow, made of springs 65 and 66, of varying thicknesses.

On the other hand, the heating blades 30, 31 and 32 are independent, so their temperatures can be different.

Claims (10)

1. Device for the strapping of an object or group of objects using a strap of thermoplastic material, according to the process consisting of moving the object or group of objects (A) in the direction of two straps (F, F'), welded beforehand, stretched transversally to the direction of movement (C), and of forming a loop around the object or group of objects (A), after the latter passes through, then of making a cut and two welded joints. It includes for this purpose at least two reels (D, E) of strap (F, F'), each incorporating a means (G, H) of tightening the strap (F, F'), placed on either side of a conveyor (B), on which the object or group of objects (A) to be strapped is moving, as well as two heads (1, 2), which are able to move away from or towards each other according to an axis transverse to the direction of movement (C) of the object or group of objects (A) to be strapped, and which are liable to come into contact with each other in order to carry out, thanks to a welding unit and a pressing unit, the cutting and the welding of the said straps (F, F'), which are each held by the front (10, 20) of the said heads (1,2), namely that on the side where the object or group of objects (A) arrives, characterised in that on the one hand, the first head (1) includes at its end two parallel plates (4, 5) placed in vertical planes parallel to the direction of movement (R, R') of the said heads (1, 2), and each presenting in the middle region of their outside edge (40, 50) a notch for the strap to pass through (F) ; and on the other hand, the second head (2) includes two parallel plates (7, 8), each coplanar to one of the plates (4, 5) of the first head (1), the outer edge (72, 82) of each of which is liable, when the said heads (1, 2) move towards each other, to come to rest in the notch (41, 51) in the plate (4, 5) opposite in order to block the strap which passes through it, each of the plates (7, 8) of the second head (2) being made up of two superposed elements (70, 80), each articulated to pivot on the said head (2) around an axis (87) perpendicular to the direction of movement of the head (2), so that their opening allows the passage between them of the second strap (F'), which lodges itself in a recess (76, 86) constituted, when the said elements (70, 80) are brought towards each other, of two cut-outs made in each of the said elements (70, 80) in their edges coming into contact with each other when they approach each other, the said recess (76, 86) containing a backing piece (26) against which one edge of the said recess (76, 86) comes to grip the said strap (F'), the said elements (70, 80) also being mobile and moving inside the head (2) in the direction of the movement of the latter, whilst at the same time being elastically pushed away from the said head (2).
2. Device according to claim 1 characterised in that each of the elements (70, 80) of the plates (7, 8) of the second head (2) is mounted to pivot on a ring (87) liable to move longitudinally to the end of the said head (2) and forced back at the stop towards this end by a spring (88), whilst a pin (89) protruding laterally from each of the said elements (70, 80) is engaged in a slot (24) which is not straight, made in a plate mounted to slide longitudinally in the said head (2) and controlled by a jack (23).
3. Device according to claim 1 or claim 2 characterised in that the parts (42, 82, 75, 85, 27) of the plates (4, 5, 7, 8) and the backing pieces (26) intended to come and grip the strap s (F, F') are cut with a bevel.
4. Device according to claim 2 characterised in that the parts cut with a bevel (42, 82, 75, 85, 27) have on the surface means (45, 820) of gripping the straps (F, F').
5. Device according to claim 4 characterised in that the means (45, 820, 850) are liable to grip the straps (F, F').
6. Device according to any one of the preceding claims characterised in that the welding unit (3) is mobile and moves under the action of the jack (13) to come to place itself between the parallel plates of the head (1), and it includes three heating plates, one central plate (30) and two lateral plates (31, 32), which are parallel to the front (10) of the said head (1), the said side plates (31, 32) being mobile and moving in the transverse direction, moving away from the central blade (30), towards which they are brought back by means of a spring (33).
7. Device according to any one of the preceding claims characterised in that the pressing unit (6) includes two levers (60, 61) each articulated to pivot by one of its ends around an axis parallel to the front of the head (2), brought back one towards the other by means of a spring (62), liable to move to position themselves between the parallel plates (7, 8) of the said head (2), each of them bearing a pivoting pressing plate (63, 64) at other its end, folded on the outer side against the said lever (60, 61) and held away from the latter by means of a spring (65), whilst a means (67), mobile and moving between the said levers (60, 61) allows the latter to pivot at different angles in order to move the said pressing plates (63, 64) more or less closer to the parallel plates (7, 8) with a view to pressing against the latter the ends of the straps (F, F') to be welded.
8. Device according to claim 7, characterised in that the levers (60, 61), each of them including a bearing (600, 610) between which and against which moves a cam (67) with parts (670, 671, 672) of different widths allowing the said levers (60, 610) to pivot at different amplitudes.
9. Device according to claim 8 characterised in that the levers (60, 61) each including a bearing (600, 610) between which and against which moves a cam with a bevelled end, allowing the pivoting of the said levers (60, 61) according to three different amplitudes, namely that either the said bearings (600, 610) are not in contact with the said cam, or that they are in contact with the said bevelled edge or with the body of the said cam, whereas the jack which moves the latter is liable to move forwards and backwards.
10. Device according to any one of the preceding claims from 7 to 9 characterised in that the pressing unit (6) fits between the lateral heating plates (31, 32) when the welding unit (3) moves between the parallel plates (4, 5, 7, 8) of the heads (1, 2) whilst the movement of the pressing plates (63, 64) under the pivoting action of the levers (60, 61) causes the said lateral heating plates (31, 32) to move apart.

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