FR2493802A1 - Automatic wrapping feed for pallets - has cold stretch plastics film applied by thrust shoe and welded closed - Google Patents

Abstract

The feed automatically wraps pallets of merchandise in films of cold stretch plastics. The film (15) is wound around a pallet on a rotating platform (6), and the film end is welded and cut and the pallet is moved on. Film application is by a thrust shoe (18). Air is blown on the film, above the shoe when it is pressed against the pallet. Film is applied by a positioning arm (4) between two consecutive cycles. A film holder carries a roll of film (2), moving along a support column. It rotates on a vertical axis.

Description

 The subject of the present invention is a process for automatically packaging pallets of goods in cold-stretch plastic films, as well as a machine intended for carrying out this process.

 The packaging of the goods transported on wooden pallets (all the goods and the wooden pallet being called hereafter "pallet"), is carried out either by strapping, or by wrapping of the whole of the pallet under plastic films, generally transparent.

 We thus sounded a packaging process according to which a heat-shrinkable film is used, which requires installations consuming up to 50 KW / h or their thermal equivalent in gas.

 Another packaging process derived from the previous one is currently undergoing considerable development: this process uses a plastic film which can be stretched when cold, and therefore has elasticity properties, the plastics generally used being polyethylene and polyvinyl chloride (PVC). .

 According to this process, a strip of film is unwound around a pallet placed on a rotary plate from its lower edge to its upper edge, so as to completely envelop in the film the load of goods forming the pallet, after which the end of the film is welded to itself and cut, then the pallet thus wrapped is removed and the cycle is repeated with the following pallet.

The advantages of the process for packaging goods under cold stretch plastic films are numerous:
- it is more economical than the wooden or cardboard box, and even than kraft paper; the cost of packaging is less than half the cost of packaging in a retractable cover, and equal to the cost of the straps,
- packaging in stretch film does not require heating and therefore saves energy, there is also no risk of product deterioration by heat
- a simple programming of the packaging machine guarantees a minimum consumption of material and a satisfactory result, the palletized loads in transparent film being less exposed to theft and allowing a quick and easy control;
- finally the stretch film does not adhere to the shrink film of palletized bundles, and it can be used for the packaging of frozen or flammable products.

 To implement the cold stretch film packaging method, an automatic machine is known which comprises a carriage carrying a reel of transparent film, movable vertically along a support column and from which the film is unwound. , a conveyor plate placed in front of the reel-carrying carriage and capable of being driven in rotation about a vertical axis, this plate supporting the palletized load and therefore making it pivot on itself during the unwinding of the film and the application of the latter around the pallet of the control means is further provided for rotating the plate carrying the pallet, for unwinding the film and for automatically raising and then lowering the reel-carrying carriage according to a succession of cycles programmed in accordance with dimensions of the pallets.

 In this known embodiment, the rotary conveyor carrying the palletized burden is provided with a pair of jacks which each form an arm of a clamp for holding and clamping the end of the film streamer, during the rotation of the plate. This machine is also provided with other cylinders to allow the proper execution of a packaging cycle.

 The presence of several hydraulic cylinders makes this machine complex, heavy and bulky, causing adjustment difficulties and therefore a lack of reliability.

 The object of the invention is to provide a method and a machine for the execution of this method which does not have the above drawbacks, and which therefore comprise simpler and more reliable means for the execution of series of cycles of automatic packaging.

According to the process according to the invention, at the start of each packaging cycle, the start of the film is applied to the pallet by means of a presser pad, while the plate rotates around a vertical axis, then it is moved aside. the pad after covering the beginning of the film with the next loop when the plate performs its second turn, and packaging continues, applying around the load successive inclined film loops. This pad presser advantageously replaces the pair of hydraulic cylinders of the known machine mentioned above: in effect the presser pad applies the film against the pallet to be wrapped, while the clamp constituted by the two cylinders of the prior machine maintains this end at a certain distance from the load, by necessity of construction, which necessarily results in unsatisfactory packaging at the base of the pallet. In this regard, it is understood that the presser shoe provided by the invention works exactly like the hand of an operator who would maintain the
Beginning of the film against the pallet, as long as this film is not covered by the next loop and thus held against the load. In fact, taking into account the dimensions of the skater relative to the hand of an operator, the implementation of the skate is much more effective than a possible manual intervention.

 According to another important characteristic of the invention, air is blown on the film above the pad during the time of application of the latter against the pallet, in order to press the part of the film projecting beyond the pad.

 In fact, since the height of the pad can hardly reach the height of the film strip in practice, the latter would tend to fall around the pad in the absence of air blowing as long as the pad is kept pressed against the pallet. When the next loop of the film has covered the upper part of the start of the film, kept applied by the pad, the latter is moved aside and the blowing is simultaneously stopped, these operations being programmed automatically by appropriate means.

 The automatic packaging machine provided for carrying out this process is characterized, in accordance with the invention, by the fact that the conveyor plate is equipped with a movable presser pad, suitable for applying the start of the film against the lower edge of the pallet at the start of each packaging cycle, and an automatic maneuvering mechanism for this pad, capable of retracting it after partial covering of the start of the film with the next film loop.

 The presser shoe comprises a plate of flexible material, for example of foam rubber, fixed to the end of an arm articulated around a horizontal axis.

 According to another characteristic of the invention, the machine comprises an air blowing nozzle on the film above the presser shoe, in order to press the film on the pallet to be conditioned during the start of the rotation of the plate, this nozzle being supplied by a blowing member such as a turbine, mounted under the plate, and the machine is provided with means for automatically controlling the start and stop of the blowing.

 According to another particular feature of the machine, the rotary film laying arm is provided with a device for sucking the film unwound from the supply reel.

 This suction rail connected to vacuum pumps keeps the end of the film in place conveniently and simply and efficiently between two consecutive packaging cycles.

 Other features and advantages of the invention will become apparent from the description which follows. In the accompanying drawings, there is shown by way of nonlimiting example an embodiment of the method and the machine according to the invention.

 - Figure 1 is a front elevation view of an embodiment of the automatic packaging machine for palletized loads according to the invention.

 - Figure 2 is a top view of the machine of Figure 1.

 FIG. 3 is a partial perspective view on an enlarged scale showing the presser shoe and the blowing nozzle mounted on the rotary conveyor plate of the machine of FIGS. 1 and 2.

 - Figure 4 is a half-sectional, mid-elevation view on an enlarged scale of the presser shoe, the associated blowing nozzle and the actuation mechanism of these two members, the nozzle and the shoe being in the low position, separated of the load to be wrapped.

 - Figure 5 is a view similar to Figure 4, showing the shoe and the blowing nozzle in the closed position, to apply the film on the base of the pallet, with the actuating mechanism in the corresponding position.

 - Figure 6 is a partial elevational view showing the holding ramp of the film by suction provided on the film laying arm.

 - Figures 7 to 9 are simplified partial perspective views showing the successive phases of implementation of the clamp constituted by the presser shoe, first applied without blowing on the start of the film (Figure 7), then with blowing (figure 8), then opened with blowing stop when the beginning of the film is covered by the upper film loop (figure 9).

 - Figure10 is a simplified perspective view showing the position of the film and the film laying arm when the latter reaches the top of the palletized load.

 - Figures 11 to 17 are top plan views illustrating the successive phases of an automatic packaging cycle of a pallet using the method and the machine according to the invention.

 The machine shown in the drawings is intended for the automatic packaging of pallet goods in cold-stretch plastic films.

This machine has
- A carriage 1 carrying a film reel 2 of vertical axis, vertically movable along a support column 3 and provided with. rotary arm 4 for laying film around a pallet such as 5 (FIG. 1) of goods, constituted by stacking a number of packages, for example cardboard on a wooden base 10.

- a conveyor plate 6 disposed in front of the carriage 1 reel holder, and capable of being driven in rotation about a vertical axis; this plate is intended to support the pallet 5 and rotate it on itself during the unwinding of the film and the application thereof around the pallet;
- control means comprising suitable motors and drive members, known per se and not shown, with the exception of a cabinet 7, for rotating the plate 6, for unwinding the film and for raising, then automatically lower the carriage 1 following a succession of cycles programmed as a function of the dimensions of the pallets.

 The machine also comprises, in known manner, a supply conveyor 8 placed immediately upstream of the rotary plate 6, and an output conveyor 9 placed immediately downstream of the plate 6. These three conveyors are fitted with motorized rollers 11.

 The carriage 1 comprises, in addition to the reel 2 of cold-stretch plastic film intended for packaging the pallet 5, several rollers 12, 13, 14 (FIGS. 1 and 2) making it possible to bring the film 15 into position and under tension , in front of the palletized load to be packed. The reel holder arm 4 is provided, at its end opposite to the rollers 12-14, with a vertical heating yoke 16 intended to cut the film at the end of a packaging cycle, and with a solder pad 17 from the end of the film on itself at the end of the packaging of a pallet.

 Column 3 supports a slide 20, movable vertically and to which is fixed a horizontal arm 30 carrying an end plate 50, intended to come to be applied on top of the pallet 5 during the packaging thereof on the plate 6.

 According to the invention, the conveyor plate 6 is equipped with a movable presser pad 18 associated with an air blowing nozzle 19, which are controlled by an automatic operating mechanism at the start of a packaging cycle.

These members will now be described with particular reference to Figures 3 to 5.

 The shoe 18 comprises a lining of flexible material 21, for example rubber of a suitable thickness, fixed on a part 22 secured to the end of an arm 23 articulated on a horizontal pivot 24 by means of an extension 25 secured to arm 23.

 The arm 23 is constituted by a tube fitted with flexible tubing 26 connected to an air supply member (not shown), located under the rotary plate 6 and constituted for example by a turbine, which makes it possible to blow air at above the shoe by the nozzle -erminal 19.

 The part 22 supporting the actual shoe 21 is solFdarsée with the arm 23 by two cheeks 28 fixed on the latter by means of bolts.

 The pivot 24 is integral with a first cam 27 which carries a roller 29 cooperating with a second cam 31 capable of being rotated by a geared motor 32. A first elastic member formed by a traction spring 33 connects the extension 25 from the arm 23 to the first cama 27; a second similar resilient member formed by a spring 34 at one of its ends fixed to a fixed support 35 of the whole of the mechanism for operating the shoe 18, while its opposite end is made integral with the first cam 27, in a point located on the other side of the pivot 24 relative to the point of attachment of the spring 33. The positioning of the ends of the springs 33 and 34 on the extension 25, the cam 27 and the support 35 are determined so that a pivoting of the cam 27 tending to move the latter away from the arm 23 drives the latter in rotation by means of the spring 33 drawn by the cam 27. On the other hand, when the latter is not stressed by the cam 31, the spring 34 tends to rotate it around the pivot 24 counterclockwise to bring it into the position shown in FIG. 4, the arm 23, the pad 18 and the nozzle 19 being therefore placed in the open position, spaced from the pallet to pack.

 The second cam 31 is integral in rotation with the axis 36 of the geared motor 32, and has at its periphery a flat surface 31a connected at its ends to a convex surface 31b, The flat surface 31a is supported on the free roller 29 integral of the cam 27, when the shoe 18 and the nozzle 19 are in the open position, retracted (FIG. 4).

 The mechanism which has just been described operates in the following manner.

 When the pressure shoe 18 and the nozzle 19 are not used, they are in the position shown in FIGS. 3 and 4, spaced from the conveyor 6 and from the wooden pallet 10 on which the boxes of goods forming the pallet 5 are stacked. The spring 33 is tensioned by the extension 25 and exerts a bias on the cam 27 tending to keep the roller 29 in contact with the flat surface 31 a of the cam 31.

 The start-up of the geared motor 32 rotates the shaft 36 and the cam 31 in a clockwise direction (arrow R in FIG. 4). The cam 31 presses on the roller 29 by its surface 31a and makes the cam 27 pivot in the counterclockwise direction indicated by the arrow S. The spring 34 is progressively compressed while the rotation of the cam 24 tightens the spring 33 which drives in rotation the whole of the extension 25, of the arm 23 and of the shoe 18 upwards, up to the active position shown in FIG. 5, in which the aforementioned members have pivoted by approximately 900 relative to their initial position. At this time, the flexible lining 21 of the shoe 18 is applied to the base 10 and the lower edge of the goods, or more precisely to the end of the film 15 which is thus pressed against the base 10 and the goods.

Then, as will be explained in more detail below, the whole of the pallet 5 rotates about a vertical axis on the conveyor 6, and the cam 31 continues its rotation while maintaining its pressure on the roller 29 by its surface convex 31b. When the cam 31 has pivoted until it reaches the position shown in FIG. 5, the roller 29 escapes from the cam 31 and the cam 27 is returned by the springs 33 and 34 to its initial position in FIG. 4. causes the arm 23, the shoe 18 and the nozzle 19 to tilt back to their open position in FIG. 4.

 At this moment, the spring 33 is compressed, while the spring 34 is maintained tensioned by the opposing bias of the arm 23. The stopping of the geared motor 32 is controlled by contacts C1 and C2 located on the axis 26 driving the cam 31 It will be noted that the flexible tubing 26 connecting the turbine to the blowing nozzle 19 allows the air supply of the latter during the alternating rotations of the arm 23.

 FIGS. 7 to 9 diagrammatically illustrate the successive phases of implementation of the shoe 18 and of the nozzle 19: in FIG. 7, the clamp formed by the shoe 18 is applied against the start of the transparent film 15, before the start of the blowing air, so that the film 15 falls behind the shoe 18.

 In FIG. 8, the blowing by the nozzle 19 has started and the air jet 37 presses against the lower edge of the goods to be wrapped in the film 15, this air jet being blown above the shoe 18.

 In FIG. 9, the arm 23 has been moved apart and the shoe 18 as well as the nozzle 19 are therefore in the inactive position, after the upper edge 15a of the start of the film 15 has been covered by the following loop 15b of the film, during the second turn of pallet 5 on itself. In fact, once this covering has been ensured, the application of the pad 18 and the blowing of air onto the film are no longer necessary, and these elements can be retracted.

 According to a feature of the invention, the arm 4 for placing the film 15 is provided with a film suction device, constituted by a vertical ramp 38 (FIGS. 1 and 6). The ramp 38 for taking the film 15 is formed of two independent squeegees 39, arranged one above the other, supported by a vertical bar 41 secured to the frame constituting the arm 4, by means of pipes42 of connection with vacuum pumps not shown. Each squeegee 39 is connected separately to a variable-flow vacuum pump, adjusted to maintain by suction.

the film 15 on the squeegees 39, between two successive packaging cycles, in order to present it suitably in front of the pallet to be packaged.

 We will now describe, with reference to Figures 11 to 17, the execution of a packaging cycle of a pallet 5 of goods according to the process according to the invention.

 The pallet 5 is brought by the input conveyor 8 to the central plate 6, the presser shoe 18 being in the open position and the film laying arm 4 being retracted.

The squeegees 39 hold the end of the film 15 in the position illustrated in FIG. 6, ready to be applied against the lower edge of the pallet 5, the carriage 4 being in the low position on the column 3.

 The film laying arm 4 is then pivoted around the axis of the roller 14 (FIG. 12) while simultaneously the gearmotor 32 is started and the arm 23 and the shoe 18 are pivoted until that -this has its flexible lining 21 applied to the start of the film 15. Then the air blowing turbine is triggered, and the air is blown by the nozzle 19 above the pad 18 to apply the film against the palletized load, as illustrated in Figure 8.

The arm 4 is e-nsuite brought back (FIG. 13), the pad 18 remaining applied to the film, the plate 6 is rotated at low speed, in the direction of the arrow carried in FIG. 13, and the s- rceurs 39 are stopped
At the same time, the carriage 4 progressively rises along the column 3, in order to wind around the pallet 5 a film banner slightly inclined upwards.

FIG. 14 shows the situation of the film and the pallet when the plate 6 has rotated approximately 3/4 of a turn.

 When the plate 6 begins its second turn, the film strip partially covers the end held by the shoe 18 and the air blowing on the pallet 10, as explained above with reference to FIG. 9. When the starting end of the film 15 is thus firmly held against the palletized burden, the clamp 18 can be moved aside and the blowing by the nozzle 19 can be stopped.

This situation is illustrated in Figure 15, in which we see that the clamp is spread while the plate 6 and the pallet 5 have made a little less than a revolution and a half.

 The rotation of the plate 6 is then accelerated, while the laying arm 4 rises more quickly along the column 3, and this up to the top of the palletized load. This latter situation is illustrated in FIG. 10, in which it can be seen that the film 15 is being wound around the upper edge of the pallet 5.

The stop of the rise of the carriage 4 is automatically controlled by a cam 30, or by an infrared cell not shown.

 Then the carriage 4 descends so as to complete the winding of the film.

 When the arm 4 has returned to its low position, it pivots until it comes back into contact with the pallet 5 (FIG. 16) and the unwinding of the film is stopped. The pad 17 is applied against the end of the film in order to weld the latter on itself, then the heating rod 16 cuts the film. The latter is maintained in the correct position by the nozzles 39 which are restarted.

The arm 4 is moved back (FIG. 7), while the motorized rollers of the plate 6 are actuated to pass the pallet thus packed on the output conveyor 9.

 The machine is then ready for the execution of the next conditioning cycle with the next palletized load.

 The method and the packaging machine according to the invention have the following advantages, in addition to those already mentioned.

 Maintaining the beginning of the film on the burden at the beginning of the packaging thereof by means of a flexible pad and a jet of air ventilated under pressure, is much more effective and satisfactory than the means used until now. and recalled previously.

 The suction bar 38 used to keep the film in good position between two conditioning cycles is also simple and effective, compared to the device used previously.

 The electro-mechanical assembly constituted by this machine is considerably lighter, complex and more expensive than the machines used until now, and its adjustment is also less delicate, so that this fully automatic machine has a particularly reliable operation.

 The invention is not limited to the embodiment described and may have numerous variants. Thus, it is obvious that one can replace the opening and closing mechanism of the shoe 1 8 by any other equivalent device. Likewise, the blowing of air above the pad 18 can be provided in any way, and the number of film holding nozzles between two conditioning cycles can be variable. On this last point, it will be noted that the fact of separately connecting the two suckers 39 to two vacuum pumps with variable flow rate, has the advantage of avoiding, during a prolonged film intake, that the depression does not cause an implosion of the film. 15, the outcome of which would be its relaxation.

Claims (10)

 1 - Method for automatically packaging pallets (5) of goods in films (15) of cold-stretch plastic, according to which a strip of film (15) is unwound around a pallet (5) placed on a rotating plate (6), from its lower edge to its upper edge so as to completely wrap in the film (15) the load of goods forming the pallet (5), after which the end of the film (15) is welded on itself and it is cut, then the pallet (5) thus wrapped is removed and the cycle is repeated with the following pallet, characterized in that at the start of each cycle, the start of the film is applied - (15) on the pallet (5) by means of a pressing pad (18) while the plate (6) rotates about a vertical axis, then the pad (18) is moved aside after covering the start of the film (15) with the following loop when the plate (6) performs its second turn, and the packaging is continued by applying film loops (15) inclined around the load successive.  2 - Method according to claim 1, characterized in that air is blown on the film (15) above the shoe (18) during the time of application thereof against the pallet (5), to press the beginning of the film (15) against it.  3 - Method according to one of claims 1 and 2, characterized in that the film (15) is maintained by suction in a suitable position on the laying arm (4) between two consecutive packaging cycles.  4 - Machine for the automatic packaging of pallets (5) of goods in films (15) of cold stretch plastic S intended for carrying out the process according to one of claims 1 to 3, comprising  - a carriage (1) carrying a reel (2) of film, movable vertically along a support column (3) and provided with a rotary arm (4) for laying the film (15) around the pallets (5 ) merchandise,  - a conveyor plate (6) disposed in front of the spool holder carriage (1) and capable of being rotated about a vertical axis, this conveyor plate (6) being intended to support the pallet (5) and to rotate on itself during the unwinding of the film (15) and the application of it around the pallet (5),  - control means for rotating the plate (6) carrying the pallet (5), for unwinding the film (15) and for automatically raising and lowering the reel-carrying carriage (1) according to a succession of cycles programmed in function of the dimensions of the pallets (5), characterized in that the conveyor plate (6) is equipped with a movable pressure pad (18), suitable for applying the start of the film (15) against the lower edge of the pallet (5 ) at the start of each packaging cycle, and an automatic operating mechanism (23, 27, 31, 32) of this pad (18), capable of retracting it after partial covering of the start of the film (15) by the next loop of the film.  5 - Machine according to claim 4, characterized in that the pressure pad (18) comprises a lining of flexible material (21), for example of foam rubber, fixed to the end of an arm (23) articulated around of a horizontal axis.  6 - Machine according to one of claims 4 and 5, characterized in that it comprises a nozzle - (19) for blowing air - on the film (15) around the pressure pad (18) in order to press the film (15) on the pallet (5) to be packaged during the first turn of the rotary table (on), this nozzle (19) being supplied by a blowing member such as a turbine, mounted under the table (6), and the machine is provided with means for automatically controlling the start and stop of the blowing.  7 - Machine according to one of claims 4 to 6, characterized in that the rotary arm (4) for laying the film (15) is provided with a suction device (38, 39, 41, 42) dufilm (15) unwound from the supply reel (2).  8 - Machine according to claim 7, characterized in that the film gripping device consists of two independent squeegees (39) arranged one above the other, each connected separately to a variable speed vacuum pump.  9 - Machine according to one of claims 4 to 8, characterized in that the operating mechanism of the pressure shoe (18) comprises an arm (23) supporting this shoe, articulated on a pivot (24) integral with a first cam (27) which carries a roller (29) cooperating with a second cam (31) driven in rotation by an electric motor (32), while a first elastic traction member (33) connects the arm (23) to the first cam (27) and a second elastic member (34), one end of which is fixed to a fixed support (35) of the entire mechanism and the other end of which is fixed to the first cam (27), ensures the return of the latter and the presser shoe (18) in the separated position when the second cam (31) has rotated by an angle sufficient for the roller (29) to escape, the cams (27, 31) and the associated elastic members ( 33, 34) being arranged so that the rotation of the second cam (31) over a predetermined angular sector causes a corresponding pivoting of the first (27), of the arm (23) and of the shoe (18) from the spread position to the position of application of the shoe (18) against the pallet (5), the arm (23) being driven by the first elastic member ( 33).  10 - Machine according to claim 9, characterized in that the arm (23) supporting the pressure shoe (18) also carries the blowing nozzle (19), which is connected to its air supply member by flexible tubing ( 26) authorizing the successive pivoting of the nozzle (19) with the shoe (18).