Improvements in the means of feeding of sheets of film to wrapping machines

Abstract

 A film (9) unwound from a reel by means (24,25) of a contact maker is fed to belts (3) for further transport to a wrapping center (17) assisted by means (4, 5) for an efficient grip to the opposite edges of the film (10). This gripping effect lasts during feeding of a suitable length of the film and during cutting (11,12,14) producing a seperated sheet (13) for wrapping.
Whilst wrapping last the contact maker feeds a further part of the film and the whole cycle is repeated.

Description

[0001] SECTOR OF THE TECHNIQUE to which the invention belongs.

[0002] To the sector of wrapping machines.

[0003] These improvements are meant to be applied to any type of machine in which plastic film is used as a wrapping element.

[0004] STATE OF THE TECHNIQUE before the application date.

[0005] Efficient manipulation of the film is intended in all cases. Since machines are concerned whose production is increasing day by day, the problems that arise in the treat­ment and manipulation of wrapping film are increasingly dif­ficult, so any modification in the feeding of the film into these machines that redounds to greater efficiency and greater safety at the working speeds, comprises an evident advantage both of a practical as well as of an economical nature. In the case we are concerned with, the invention is intended for the machines that use sheets of film which have been freed from the bobbin and in which both the feeding, freeing and treatment in the transportation of the sheet and during its manipulation in the wrapping operation is found to be perfect­ly coordinated in an efficient manner.

[0006] The arrangement of the elements that comprise the invention is basically the following:
    - A contact maker to bring the film near to the belts that have to carry out transportation of the sheet of film, and this contact maker has an arrangement which is suitable to initiate placement of the film in the contin­uous feeding position.

[0007] The said contact maker must likewise permit the film to be held to make the cut that frees the sheets of film in a suitable manner.
    - Conveyor belts, by means of which is obtained: Intake of the film by one of its ends.

[0008] Transportation of the film, to a suitable degree, so that the cut can be produced which frees the sheet of film.

[0009] Efficient grip of the film along its opposite sides, which permits transportation and successive phases of the wrapping.

[0010] All of this coordinated in an efficient manner in suitable times.

[0011] A more concrete idea of the way these elements work in an independent manner, is set out below:

OPERATION OF THE CONTACT MAKER THAT BRINGS THE FILM NEAR TO THE CONVEYOR BELTS.

[0012] The contact maker that brings the film near to the conveyor belts, has independent movement, although it is perfectly synchronized with the dragging movement that is produced by means of the conveyor belts. The aforesaid contact maker for bringing the film near, is comprised of the following elements:
    - A main body -24- which is capable of shifting on the guides -26- both in direction -40- as per figure 16, as well as in -23- direction as per figure 18.
    - This main body has a turning point -34- on which the piece -25- can rotate.
    - Both the main body -24- as well as the body -25- that complements it, have the pieces -32- and -31- respectively, between which the film -33- passes which arrives from the input place of the film -9-.

[0013] In such a way that the pieces -32- and -31- are supplied with windows -39- through which the belts -3- pass which have then to transport the film.

[0014] Precisely thanks to these windows -39- the film can be taken up in the places -33-, when the rollers -1- and -2- of the belts, approach and by simple pressure take, hold the film, and then by this pressure can carry out the operation of transporting the film.
    - The main body -24- has a loose roller, -27- on which the film that arrives by -9- rests.
    - In the complementary body -25-, another rol­ ler -28- which has the following characteristics:
    - By its own weight, and with the pressure de­vice -29-, the aforementioned roller fluctuates and always rests on the film, which arrives by -9- and facing the loose roller -27-.
    - The roller -28- can only turn in one direc­tion -30-.
    - For this reason the said roller, takes a grip on the film, making it impossible for the film to return in the opposite direction from the direction of arrival -9-.
    - On the contrary, any traction brought to bear on the film in the arrival direction -9-, does not present any difficulty for the film to shift.
    - Main body -24- experiences the movements due to a connecting rod -20- which is held at the point -35- of the said body, and on the other hand, the connect­ing rod moves thanks to the eccentric -18-.

[0015] The performance cycles of the contact maker that brings the film near to the conveyor belts are the following:

Initiation. When the film has to be positioned for the first time.

[0016] The contact maker has the layout which can be observed in figure 11.

[0017] In this layout, the film is made to pass for the first time from -9- over the roller -27- and the film -33- is left between the pieces -31- and -32-.

[0018] The end of the film -37- is made to arrive at the zone -36- between the rollers -2- and -22-, which is as much as placing the end of the film -37- between the belts -3- that have to transport it.

[0019] When this first positioning has been carried out, the body -25- is made to turn and the whole is left in the manner seen in figure 12.

[0020] In this first operation any traction on the film -37- is possible, thanks to the fact that the roller -28- permits it.

[0021] Therefore in figure 14, the rollers -1- and -2- are shown turning according to (A) in such a way that the film is found to be pulled by the belts -3- which hold it and therefore move it.

First movement of the contact maker.

[0022] Observing figure 15, it can be seen that the turning of the piece -18- is begun as per -42-. By this turning of the piece -18- on the axle -19- shifting as per -40- is begun which can be observed in figure 16.

Second cycle.

[0023] It corresponds to the one represented in figure 16.

[0024] The head now shifts as per -40-.

[0025] The two pieces -31- and -32- hold the film bet­ween them and consequently they also pull it as per -40-, which operation is assured by the roller -28- whcih can only turn in direction -30-, for which reason this film is found to be held and all advances of the contact maker mean advances of the film.

Third cycle.

[0026] On continuing the turning of the piece -18-, as per -42- in the manner seen in figure 17, the movement -40- reaches the end -41- and then the movement of the contact maker is inverted, as per the direction -23- indicated in figure 18.

[0027] In the position of figure 17, two situations are observed:

1. That the pieces which carry the film -31- and -32- are between the rollers -1- and -2-.

2. That since the said rollers are brought together, the belts that both have, hold the film between then, and therefore the latter is held by pressure of the two belts.

Fourth cycle.

[0028] The contact maker (as per figure 18), moves in the direction -23-.

[0029] But the film has been held, between the belts -3- by the weight of the roller -1- itself aided by the pressure that a spring brings to bear on it.

[0030] This cycle which is represented in figure 18 finishes at the starting position represented in figure 15.

[0031] The movement of this contact maker is as des­cribed; the driving action of the journeys is given by the connecting rod -20-, which moves by turning of the piece -18- which will receive the movement in a conventional way which is most appropriate in each case. The said piece -18- rotates through the axle -19-, but it must be pointed out that in spite of the fact that the roller -2- also has the same axle -19- it does not move at the same time for this reason, since the roller -2- has its own movement, indep­endent of that which the piece -18- may have.

Functioning of the conveyor belts.

[0032] The arrangement proposed comprises two pairs of conveyor belts. In figure 13, the existence of two zones -38- can be observed in which the said belts appear, in such a way that each one comprises the set of two opposite belts.

[0033] Likewise in the aforesaid figure 13 it can be seen that each set or pair of belts, takes the film at its parts -33- and holding it by its edges, transfers it held in a suitable way to the centre -17- of the wrapping machine. The film is therefore held and transported by the belts, that act on two of its opposite edges.

[0034] What is done next it to show the working of a pair of these belts, which as we have pointed out can hold the film along one of their edges.

[0035] A pair of belts -3- are concerned which are moved simultaneously in such a way that the rollers, or at least some of them rotate conveniently.

[0036] The upper belt moves by the rollers -1- and -7- and the opposite belts moves by the rollers -2- and -8-. At both sides of the belts are the sheets -4- and -5- which by mechanical, pneumatic or electric means, whichever is suit­able in each case, can be brought together, in such a way that this bringing of them together makes the belts that pass between them, undergo pressure, in such a way that due to the movement of the belts, there is then effective gripping of the film, which is found to be situated between the belts and consequently there will be effective transportation of the film, due to this; there is dragging of the film which is between the belts -3- whenever the sheets -4- and -5-, undergo pressure as per -6- which permits effective gripping of the film by the belts -3-.

[0037] Whilst the pressure -6- exists to draw the sheets -4- and -5- there is gripping of the film. The belts -3- move or are at rest.

[0038] If the belts do not move there is only holding of the film; if the belts move transportation of the film occurs.

[0039] The rollers -2-, -7- and -8- can rotate without their rotating axis shifting.

[0040] Roller -1- however, which at the ends of its axle has pulley wheels -21- that lean permanently on the edges of the eccentric -18-, which with its rotation can make a shift of the turning axle of the rollers -1- to positions such as the one indicated by -22- in figures 11, 12 and 16 in such a way that when the rollers -2- and -22- are in the said separ­ated position, the film can be placed between the said rollers at its end -37-, in such a way that when approximation is per­mitted between the rollers -2- and -22- the film's retention is assured.

[0041] So the functioning of each pair of belts -3- as regards their simple displacement, depends on the rotation their rollers have. As regards the retention of what exists between the belts, it depends on the pressure as per -6- that the interposed sheets -4- and -5- receive and finally as re­gards the mobility of the roller -1- to pass to the position -22-, this depends on the position that the cam -18- has push­ing -21-.

[0042] To get a clear idea of the workings of this con­tinuous input of film in wrapping machines, the complete work­ing operation has been split up into 10 cycles, of which a series of figures are supplied successively, by means of which the general working description is made, bearing in mind that the action of the elements that make up the unit have already been described separately.

[0043] Bearing in mind that the objects of the invention are some improvements in the input of sheets of film, now that the objects of the invention have been described in­dependently of the mechanisms that make up this unit, we now proceed to describe the whole film feed following the success­ive steps according to the working as a whole:

Figure 1.

[0044] We start from the position represented diagram­matically in this figure, as a possible initiation of the pro­cess but undoubtedly we could have started from any other posi­tion.

[0045] In this position the cam -18-, when the whole of the same is as represented in figure 15, the cam -18- does not rotate, it stays still.
    - The contact maker unit -24- -25- and its elem­ents -31- -32- have the film between them and its end -37- is held by the rollers -1- and -2-. Contact maker at rest.
    - There is approximation of the sheets -4- and -5- by pressure as per -6-.
    - Under these conditions movement of the belts commences as per (A) and consequently the dragging movement of the film is begun as per -15-.
    - This dragging of the film as per -15- is done directly from its arrival by -9- from the corresponding bobbin and this traction and subsequent displacement of the film is possible, thanks to the fact that the roller -28- permits it, since in -30- direction it can rotate freely.

Figure 2.

[0046] When the film has been shifted for a suitable len­gth, which depends on the size of the sheet of film to be used in the wrapping machine and which depends on the type of pack­aging one wants to make for the wrapper.
    - The pulling belts stop.
    - There is no transfer of film.
    - But the film is held by its two opposite edges by the pressure brought to bear on these by the belts -3- thanks to the fact that the pressure of the sheets -4- and -5- is maintained by the pressure as per -6-.
    - The contact maker unit -24- -25- also remains static.
    - Everything is as rest, in the representation of this figure.

Figure 3.

[0047]     - While everything remains at rest, according to figure 2, the cutting device -12- ascends, due to an impulse it receives from -11-, by a suitable procedure.
    - The cut is made along the whole width of the film, in the manner seen in the plan view in figure 13.
    - Precisely at the moment represented in this fig­ure, the sheet -13- represented in the following figure is freed by this cut.
    - During cutting, everything has remained still.

[0048] The film is held on both sides:
    - By the pressure of the roller -28- on -27- pre­venting return of the film.
    - By the pressure of the belts -3- on the opposite edges of the film, therefore the cut is clean.

Figure 4.

[0049] Shows the culmination of the action produced in figure 3, it serves to point out the existence of a sheet of film -13-, completely freed and with the whole set of mechan­isms at rest.

Figure 5.

[0050] Immediately after the cut has been made and conse­quently a sheet of film -13- freed:
    - The belts -3- are started up.
    - The sheet -13- is pulled by the belts -3-.
    - The pulling is effective since the pressure of the plates -4- -5- is firm due to action -6-.
    - This sheet ends up situated at -16- which cor­responds with the centre of the wrapping machine -17-.
    - When the centering of the sheet -16- has been accomplished the rotation of the rollers as per (A) will stop rotation, the movement of the sheet as per -15- will stop being done.
    - But the sheet of film -16- will continue to be held on its edges, since the pressure action -6- will be maintained.

Figure 6.

[0051]     - When the sheet of film -16- has been left at rest, but held by its edges, the following operations com­mence:
    - The wrapping machine, strictly speaking, be­gins to function:

[0052] The product to be wrapped ascends.

[0053] It pushes the film which is still held along its edges etc. etc.
    - The piece 18 represented by figure 15, begins to rotate as per -42-.
    - This rotation determines the following:
    - That the contact maker -24- -25- begins to shift as per -40-, as represented in figure 16.
    - Producing dragging of the film which arrives by -9- when it shifts.
    - The cam -18- in its rotation causes a thrust, by means of its edge, onto the piece or roller -21- result­ing in shifting of the roller -1- which passes to the posi­tion -22-.
    - This opening or separation between the rol­lers -22- and -2-, or, if it is wished, between the convey­or belt at its end part, is done without there being rota­tion of these.

[0054] Since the belt is at rest.

Figure 7.

[0055]     - The sheet of film -16- continues to be held at its edges.

[0056] The work of the wrapping machine also contin­ues, the folding blades will already have begun to function.

[0057] The belt -3- remains at rest.
    - The cam -18- will continue to rotate and will pass its position from figure 16 to the one represented in figure 17, in which we can see that the whole contact maker unit has now arrived at the end of its journey and commences return to the initial position.

[0058] In this position of start up of the return of the contact maker we can see that the separated rollers -2- -22- will already have come together and will there­fore have held the film.

Figure 8.

[0059]     - The sheet of film -16- will continue to be held at its edges, for as long as the good working of the folding of the wrapping machine advises this.
    - As we have already said, when the above cycle ends, the rollers -1- and -2- are already found to be holding the film.
    - The contact maker unit -24- -25- moves in -23- direction.
    - This journey is possible, thanks to the grip that the film has at the end and thanks to the fact that the roller -28- can rotate freely as per -30-.
    - Shifting of the contact maker is possible, since it continues to be driven forward by the connecting rod -20- and because rotation of the cam -18- continues as per -42-.

[0060] The cam -18- is rotating continuously from the position described at the time of figure 6.

Figure 9.

[0061]     - The sheet of film -16- which was held along its edges has stopped being held. The pressure -6- that meant bringing together of the sheets -4- and -5- has dis­appeared.
    - The package will have been wrapped and the wrapping machine on its part will continue to carry out the successive operations of withdrawal of the wrapped package, etc.
    - The belts remain at rest, but holding the film along its end between -1- and -2-.
    - Under these conditions the contact maker draws near the rest position with its movement as per -23-.

[0062] This is possible thanks to the connecting rod -20- which moves by rotation of the cam, which can be obser­ved by the position seen in figure 18.

Figure 10.

[0063]     - The contact maker -24- -25- reaches the end of the journey.
    - The contact maker will stay still.
    - Because the cam -18- also stays still.
    - The rollers -1- and -2- will continue to hold the film. On the other hand the tension as per 6 will re­appear. In this way we find ourselves once again with repet­ition of the cycle.
    - In connection with the state of the previous technique, the invention presents the following advantages:
    - Direct feeding to the wrapping machine from a reel of film.
    - Transportation of the film by gripping of the film by means of conveyor belts.
    - This grip is guaranteed by sheets that put pressure on the belts along great length, holding both for transportation of the film as well as:
    - Before cutting of the film is produced.
    - During transportation of the freed sheet of film.
    - During cutting of the film.
    - During the whole wrapping operation.

[0064] The hold of the film is of great stability, last­ing long even though the operations that the film is subjected to are different.
    - The contact maker for input of the film, to pre­sent the film to the conveyor belts, as well as to facilitate cutting has complete independence of movement, even though they are suitably coordinated with the movement of the belts.

[0065] This permits easy arrangement of cycles, in reply to the different film demands by the wrapping machine.
    - The cut is produced cleanly and with the film completely at rest.

[0066] In the enclosed drawings the figures used repre­sent:

Figure 1 to 10 both inclusive- serve to - represent the different working cycles in the input diagrammatically.

Figure 11 - shows the contact maker to move the film to the belts that have to transport it.
      But fundamentally it shows the way the contact maker is formed, with the upper part foldable to facilitate position­ing of the film when initiating positioning of a new reel of film.
      - It shows the rollers -2- -22- separated to say that gripping of the film by its end is simple.

Figure 12 - is the sample of the contact maker when the film has already been positioned in the new reel operation.

Figure 13 - shows a plan view of the whole unit, in the place of convergence of the following elements:
      - form that the contact maker has, with the windows -39- that facilitate intake of the film.
      - form of arranging the two pairs of dragging belts -38- that show precisely how the film will be held along the side edges of the sheet of film.
      - arrangement of the cutting element -12- all along the film.
      - arrangement of the roller -28- with rotation in one direction only that impedes all possible backward movement of the film -9-

Figure 14 - Position of the contact maker when the dragging movement of the film is begun, to take a specific length of it, to then produce the cut that frees the sheet.

Figure 15 - A figure that shows the same as figure 14 positionwise, but in this case the outside part of the cam is shown, that gives rise to shifting of the contact maker.

Figure 16 - represents the movement of the cam, at the position when a quarter turn has been produced, in which a shift of the contact maker has been produced bringing the film towards the place in which it has to be taken by the belts that have to transport it.
      Simultaneously it shows us the fact that by the eccentricity of the cam, a separation has already been pro­duced between the rollers, which prepares the unit to be able to trap the film along its end.

Figure 17 - This is in the position in which the cam, in its continuous rotation has made it possible to bring the film near to the rollers and gripping of the film by these.

Figure 18 - Return of the contact maker is begun, and the film held. A position which will take us to complete rest of all the elements, so that ascent of the cutting element -12- can be produced by impulse as per -11-.

[0067] Reference is made below to the different signs that have been used in the enclosed drawings, likewise the relation­ship existing between one and all is pointed out, both as re­gards functioning as well as assembly.

1. Roller that drives the belt -3-, to one of the belts -3-. This roller has the possibility that the thrust of the cam -18- in its rotation, pushing the element -21- it can shift the roller we are concerned with to the position of the same that is indicated by -22-.

2. Roller facing -1-. Between both rollers, better between the belts that they drive, the retention of the end of the film is made.

3. Pair of belts which when driven by the corres­ponding rollers, lead the film from one place to another.
      These belts can be brought nearer to each other by the action of the plates -4- and -5- and by the impulse sustained as per -6-. In this manner the retention of the film is effective.

4. Upper plate, that leans on the upper belt -3- A plate that is opposite -5- which has equal effects.
      The conveyor belts -3- are positioned between both plates, and the edges of the sheet of film or the film that has to be cut should be held between both belts.

5- Plate of equal characteristics as -4- together with -4-, it produces the effects pointed out.

6. Pressure that is caused by the bringing together of the plates -4-5- for effective gripping of the film by means of the aforesaid belt -3-.

7. Rollers that guide the belt -3- and comple­ment the action of the rollers -1-.

8. Rollers that complement the action of the rollers -2-, due to this, a belt is moved by the rollers -7- and -1-.
      The belt that is opposed to the previous one, is moved by the rollers -8- and -2-.
      The part of the belts -3-, is brought near by the plates -4- and -5- by the pressure on these as per -6-.
      All of this assures effective retention by means of the belts -3- to the edges of the film that there may be between then.

9. Arrival of the film from the reel.
      With its arrow it indicates the movement as the film is separated from the reel, when the latter is sought in any way.

10. Film that is pulled along by the belts -3-, for the length that is best suited to each case, so that a stoppage of the belts can be produced straight afterwards and the action of the cutter -12- can be pro­ceeded with, which will free the sheet of film -13-.

11. Impulse that the cutting element will receive, so that ascent will be produced and the conseq­uent cut by means of -12- all along the width of the film.

12. Cutting element, which will only act when the film is stopped. The cut produces the freeing of the sheet that is already held by the conveyor belts -3- and in position to be transferred to a suitable place.

13. Sheet of film, totally freed, which immediately after it is freed, begins to be pulled along by the belts -3- that hold it along its opposite edges.

14. Place where the cut has been produced.

15. Movement that the film -13- in the form of a sheet takes. This movement is caused, when the rol­lers -1- and -2- move as per (A).

16. The sheet occupies the suitable place in the wrapping machine.
      The film, will continue to be held.
      This hold was begun during the intake and ten­sioning of the film to have a new length of film available.
      This hold continued during the cutting to free the sheet -13-.
      This hold continues during the transfer of the sheet to the -16- position.
      This hold will continue until such times as it is considered to be necessary, for the wrapping machine to continue to work well.

17. Supposed centre of the wrapping machine, to which sheets of film are being supplied for wrapping.

18. Cam that rotates on the axle -19-. It will rotate in -42- direction when this is advisable.
      It rotates around the axle -19- but completely independent of the roller -2- that also rotates on this same axle, but independently as we have already said.

19. Rotation axle of the cam -18-.

20. Connecting rod that is moved by the piece -18- and the whole contact maker moves and shifts with it.

21. Pulley wheel that rests on the edge of the cam -18-. Due to the eccentricity of the cam, it checks the pertinent shift of the roller -22-.

22. Position that the roller -1- takes when due to the position of the cam -18-, this means that the eccentricity of the same obliges shifting.

23. Return movement that the contact maker undergoes after intake and retention of the film has been produced by the rollers -1- and -2-.

24. Lower part of the contact maker that brings the film near to the place to be taken by the belts.

25. Upper part of the contact maker than can tilt at -34-. This tilting permits positioning of the film when a new reel is positioned.

26. Guides that permit shifting of the contact maker -24- -25-.

27. Roller that can rotate freely and is inte­gral with the contact maker -24-. The film that arrives from -9- rests on the aforesaid roller.

28. Roller, that has a device, that only per­mits rotation as per -30-.
      Thanks to this arrangement all movement of the film is impeded, in a direction other than that of arrival -9-.
      Then in fact, it means a retention of the same, which avoids return.

29. Devices that permit effective pressure of the roller -28- on its opposite number -27-, which, besides its own weight assures effective hold of the film.

30.Only rotation direction that the roller -28- has.

31. Upper lip of the contact maker, that is provided with the windows -39-, so that the belts -38- can take, hold and therefore transport the film.

32. Lower lips, that are opposite those of -31- having a similar arrangement and permitting the same effects.

33. Film that remains between the lips -31- and -32- of the contact maker.

34. Rotation point of the upper contact maker -25-.

34. Point where the connecting rod -20- is fixed to the body of the contact maker -24- so that shifting of the aforesaid contact maker is possible.

36. Place between the rollers, better between the belts -3- where the film that has to be held is position­ed, and this thanks to the shifting of the contact maker -24- 25.-

[0068] It will be readily understood, after observing the drawings and the above description, that the present idea pro­vides a simple and effective construction, that can be put into practice very easily, assuring relatively cheap manufac­turing.

[0069] It is reiterated that in the object that com­prises the present Invention, all those modifications of detail advised by circumstances and practice can be intro­duced, whenever the variations introduced, do not change, alter or modify the essence of the invention described.

Claims

1. Improvements in the means of feeding of sheets of film to wrapping machines, in accordance with these improvements the aforesaid machines are provided with a contact maker comprised of two pieces, the first of which (24) comprises the lower part of the contact maker that brings the film near to the place in which it is taken by the corresponding belts, and the second piece (25) com­prises the upper part of the contact maker that can tilt, which permits postiioning of the film when a new reel is provided.

2. Improvements in the means of feeding the sheets of film to wrapping machines, as per note 1, that is characteristic due to the arrangement of a contact maker that can be shifted by means of a connecting rod (20) moved by a cam (18) that at prefixed times produces separation between the ends of the belts that have to take the film again.

3. Improvements in the means of feeding the sheets of film to wrapping machines, as per the preceeding notes, that is characteristic because the contact maker has a pair of elements, one up and the other down (31-32) in the manner of lips with the corresponding windows (39) that per­mit the film to be taken up by the belts (3), and the afore­said contact maker is also characteristics because it has a wheel (28) that rotates in one direction only avoiding back­ ward movement of the film.

4. Improvements in the means of feeding of sheets of film to wrapping machines, as per the previous claims, that is characteristic because the contact maker and arrangements that form it carry out:
      - The intake of the film by belts (3) that hold it at its edges thanks to runners (4-5) that exercise suit­able pressure on the said belts, which is tensioned straight away for a fixed amount that corresponds to the length of the wrapping sheet.

5. Improvement in the means of feeding of sheets of film to wrapping machines, as per the previous claims, that is characteristic because the contact maker and arrangements that collaborate with it, keep the film completely at rest when it is introduced to produce cutting at prefixed measure­ments forming a freed sheet of film that is transferred later to the central sector of the wrapping machine and the film is kept held during the wrapping operation.

6. Improvements in the means of feeding of sheets of film to wrapping machines, as per note 5, that is character­istic, because with the belts (3) at rest and during the opera­tion of the wrapping machine itself, the cam (18) is put into movement producing the nearing of the film to the place in which it will be trapped between the belts (3), that have pre­viously been separated from each other by the action of the cam -18- on which a pulley (21) rests that is fixed on the axle of the roller (1) that drives one of the belts (3) pro­ducing withdrawal of the contact maker straight away to initiate a new cycle of work.

Drawing