WO2002066329A1

WO2002066329A1 - Automatic machine for the packaging of products inside bags of plastics

Info

Publication number: WO2002066329A1
Application number: PCT/EP2002/001551
Authority: WO
Inventors: Renato Rimondi; Angelo Cappi
Original assignee: A.W.A.X. Progettazione E Ricerca S.R.I.
Priority date: 2001-02-19
Filing date: 2002-02-14
Publication date: 2002-08-29
Also published as: ITBO20010091A0; ITBO20010091A1

Abstract

The machine is provided with means (6, 8, 9, 11', 13) for the controlled feeding of the plastics film to the forming head (17) which forms with the said film a continuous and descending tubular winding, in which are inserted the products to be packaged by means of a hopper (18). A heat-sealing unit (22) performs a longitudinal and continuous sealing (Z) upon the longitudinal and reciprocally superimposed edges fo the said tubular winding and downstream of the forming device (17) sealing and transversal cutting means (23) perform upon the same tubular winding at least a double transversal continuous tight-sealing, for the head-closing of the filled bag and for the sealing of the bottom of the following bag, while a cut between the two sealing, separates the consecutive bags between them. These means can also comprise an incision device to facilitate the following tear-opening of the bag. The closing of the sealing and cutting means is commanded in advance by the stop of the unwinding of the film of the bobbin, while the elevator platform raises suitably the bag to be closed, to avoid that the edges of the film to be transversally sealed result under stress. When the translation presser (34) discharges the filled and closed bag from the elevator platform (29) arrived at the end of its descending stroke, the same platform immediately returns in the high working position, to ensure to the machine a high working speed. An anti-overturning barrier (43) is provided in the tunnel for the discharge of the filled and closed bags, to avoid that the same overturn toward the discharging pusher, so that this one can freely return in the rest position.

Description

TITLE: "Automatic machine for the packaging of products inside bags of plastics"

DESCRIPTION The invention relates to an automatic machine for the quick packaging of the products inside of bags of plastics formed at the moment, having a proportioned measure with respect to the quantity and/or the quality of the said products and tight- sealed.

A method and a machine for the packaging of articles with different shapes and dimensions inside of plastics bags, are for example described in the US patent 5.313.766. This patent describes a machine to be placed in correspondence of the counters of the supermarkets or to be integrated in these, to obtain from a continuous film unwound from a bobbin, bags having a height proportioned to the dimensions and/or to the quantity of the products to be packaged, which at the end of the cycle are closed also on the upper end.

Currently is spreading the so called "e-commerce" which allows to the consumer to contact via Internet a dealer, to choose the desired products, to effect the transaction in real time with the electronic money and to wait comfortably at home the delivering of the packet with the acquired products. In this type of commerce, the rapidity of the supplying, in addition to the comfort, represents a determinant factor for the success. For these reasons it has been developed in the present days a more wide research concerning the means and the processes suitable to reduce to the maximum the delivery times and between these, the times of the packaging of the products, which are the most negatively influential.

Object of the present invention is to provide a machine for the automatic and quick packaging of the products with various shapes and dimensions in bags formed at the instant and having the dimensions of the products to be packaged. This object is achieved with an apparatus similar to the one described in the US patent above mentioned, but independent from the counter of the supermarket, therefore self- contained and improved to increase the speed and the security of the working cycle and to realise tight-sealed bags, in which preferably remains trapped a correct quantity of air, suitable to form a cushion which protects the packaged products during the phase of the transport to the house of the customer.

Further features of the invention, and the advantages deriving therefrom, will appear better evident from the following description of a preferred embodiment of the same, made by way of non-limiting example, with reference to the figures of the attached sheets of drawings, in which:

Figure 1 is a perspective view of the machine, taken from the side near which is placed the operator and which evidences the upper portion and the bag discharging front from the same machine; - Figure 2 shows the machine sectioned transversally at the level of the introduction pit of the products inside the bag during the construction phase,

Figure 2a shows laterally and with portions in section constructive details of the inferior portion of the charging hopper of the products;

Figure 3 is a perspective view of the group which performs the continuous tight-seal longitudinal welding of the superimposed edges of the tubular winding from which results the packaging bags;

Figures 4 and 5 show other details of the welder of Figure 3, taken along the respective section lines IV - IV and V - V;

Figure 6 shows details taken along the section line VI - VI of Figure 2 and relative to the guide pit of the bag in the construction phase and to the expulsion means of the formed bag;

Figure 7 is a perspective view of the discharging means of the formed bag.

From Figures 1 and 2 it is note that the machine is contained inside a shaped parallelepiped structure 1 , having a rectangular base, which bears upon the ground with feet 3 and wheels 4 in order to be, if requested, easily moved and it is superiorly provided, in central position, with a raised portion 101 upon which there opens the mouth of the pit P for the introduction of the products to be packed, which is provided laterally to the said raised portion 101 , with bearing planes 201 with the small switchboard 2. The side having greater dimension of the structure 1at which is disposed the operator, is closed by doors 301 having the shape of an overturned L, and it is provided in its centre with a further door 401 , if necessary made of transparent material in order to allow the control of the functionality of the machine and above all useful to allow the removal of a possible trapped bag or to predispose in the correct manner in the formation means of the tubular film wrapping from which the bags are obtained, the same film during the initial phase of pre-arrangement of the machine to the automatic working. On the other side having greater dimensions of the structure 1 , is fixed at the bottom and projecting a structure having a rectangular plan 5 which supports, in rotatable manner a couple of rollers 6 parallel between each other and with respect to the greater dimension of the same structure 1 , upon which rests the bobbin 7 of the plastics film, guided at the ends by means of housing appendices 105 integral to said structure 5. At least one of the rollers 6 is connected at one end, by means of a positive drive transmission 8, to an electric motor 9 having suitable characteristics, which provides for the rotation of the bobbin 7 in the useful direction for the unwinding of the film 107, to allow to the machine a high working speed (see further).

Over the structure 5, upon the upper end of the structure 1 , is fixed in a projecting manner a rectangular structure 10 which supports a correct number of idle rollers 11 and a pair of oscillating rollers 11', 11", all of them parallel to the inferior rollers 6 and the last of which acts as tightening pulley, being provided upon its oscillation fulcrum 12, with a transducer 13 which gives out an electric signal proportional to the angular position of the structure which carries the said tightening pulley and by means of which is controlled the rotation with a proportional speed of the motor 9 for the unwinding of the bobbin 7, the whole in such a manner to ensure a feeding of the film without tensions. The first oscillating roller 11' is instead controlled by a traction spring 14 placed in such a manner to place on the right or on the left side of the oscillation fulcrum 15 of said roller, to stabilise this latter in the normal operating position indicated in Figure 2 with the continuous line or in that indicated with the dotted line which sees the same rolling which is in rest against the first roller 11 , to retain with this the tail of the film of the bobbin which terminates, in order to facilitate the connection by means of an adhesive strip, with the head of the film unwound from a new bobbin. A suitable outer body 501 covers the structure 10 and it can be used as a working surface.

The film 107 which comes out from the last transmission roller 11 , passes through the transmission structure 16 fixed in projecting manner to the vertical an known type tubular forming device 17, which is fixed at its time with external appendices to the frame of the machine and which, together with said structure realises the forming head, inside of which passes the film from above downwards, in order to form a continuous tubular winding, with longitudinal and superimposed edges which are turned in the opposite portion with respect to the one for the entering of the film, thus on the side of the operator.

Inside the forming device 17 is placed with correct clearance the hopper 18, the upper edge of which is supported by means of the upper structure 101 of the machine. Both the portions 17 and 18 have a quadrangular section and against the sides of the inferior portion of the hopper act transversal rollers 20 kinetically connected between them and that by means and of a electric motor 21 are actuated upon command to rotate at the same speed, in order to draw downwardly the tubular winding of the film formed in the forming device 17 and with which the same rollers act with contact, in contrast with the support provided by means of little and sprung idle rollers 102 (Fig. 2a) supported by the lower sides of the hopper 18 by means of flat springs 220.

Before leaving the unit of the forming device and the hopper 17, 18 the longitudinal and superimposed edges of the tubular winding of the film 107, are reciprocally secured each other with a longitudinal continuous heat-sealing operation, realised by means of a device 22 which has been expressly planned for the improved machine which is referred to and that will be further described in the constructive details.

Below the same unit 17, 18 is placed with the possibility of self centering closure with respect to the vertical center line axis Y of the said unit, the known group 23 which realises upon the film tubular envelope 107, at least a double transverse sealing for the head closing of the filled bag and for the bottom closing of the following bag and which realises a transversal cut upon the portion of envelope which lies between the two consecutive transversal sealings, in such a manner to separate the filled bag from the one which is following.

Between the unit 23 and the superior unit 17, 18, is provided the horizontal and known support plate 24, connected to the relative screw-nut screw translation system 25, with the motor 26 by means of which the same plate 24 can pass from the position illustrated with continuous line in Figure 2, in the rest position illustrated with dotted line, and vice-versa. When the plate 24 is in the working position, it supports temporarily the bottom of the forming bag, before the filled bag is discharged from the forming pit.

Upwardly and downwardly from the sealing and transversal cutting unit 23, there are provided the lateral and opposite folders 27, of the known type, which derive the movement from the unit 23 which carries them from the rest position to a self centering closure position upon the tubular envelope, in correct phase with the intervention of the same group 23, in order to form upon the same envelope lateral and re-entering folds, like a bellows.

When one bag has been discharged from the forming station, the bag the formation of which has been started in the unit 17, 18 and which has been abandoned by the sealing and transversal cutting unit 23, is left by the inferior plate 24 of temporary support and the bottom of the same bag is supported by means of the elevator platform 29 connected to a screw - nut screw linear actuator 30, supported by the frame of the machine and actuated by the electric motor 31. Upon the platform 29 can be provided known devices to detect the weight of the bag during the filling phase. Known barriers with opto-electronic sensors 32, 32' are provided above and under the forming unit 17, to detect the level of the products inside of the bag at first during the filling phase and later in the phase of closing of the bag. As the bag is gradually filled, the superior optical barrier 32, obscured by the products, controls the descent of the platform 29 up to a predetermined maximum value and controlled by devices which detect the downward travel of the platform 29. When such value is reached, the machine emits a signal which advises the operator of the necessity to command the closure of the filled bag. The operator will complete the filling of the bag avoiding to obscure the upper barrier 32 and then he will command the start of the closing phase of the filled bag. It is also provided for a phase of manual operation of the machine according to which the same machine predisposed the empty bag with the maximum height or with the intermediate height required and proportionate to the dimensions of the product to be packaged, without the descent of the platform 29 until the pre-fixed maximum level, then the operator introduces the product in the bag and at last activates the closure phase of the same bag.

Following the actuation of the closure command of the bag (according to a variant, this phase can be if necessary solved in an autonomous and automatic manner by the machine), the platform 29 descends and stops when the top of the packaged products has gone beyond the optical barrier 32' with a suitable end stroke. In sequence there intervene the folders 27 for the lateral bellows and then intervenes the welding and transversal cutting unit 23 in order to close superiorly the formed bag, to close inferiorly the following bag and for the reciprocal separation of the two bags.

A heat-sealing results as more weak as more the edges of the film to be welded to each other are under stress. In order to avoid this drawback, during the transversal sealing phase it is necessary to carefully control the feeding of the film which must not be under stress and which not results too slack because there could be formed folds that could compromise the success of the sealing. To reach these objects it is foreseen that the intervention of the sealing and transversal cut unit 23 begins even prior than that the unwinding motor 9 of the bobbin 7 stops. Together with this solution it is also foreseen that in correct phase the platform 29 which has reached the end stroke position for the upper closure of the filled bag, performs a little stroke in order to ensure the correct slackening of the film also on the lower portion of the unit 23 which in the closing phase has the need to recover the film both upwardly and downwardly. All the above mentioned movements must be synchronised and the whole must occur within times which are in the order of tenths or hundredths milliseconds and if this should not occur, there is no certainty that the sealing is done correctly.

In order to reach these scopes (see Figure 2), the movement of the sheet- presser sprung bars 123, upwardly and downwardly assembled with respect to the unit 23, not shown in details because are known in the art of heat-sealing, also for the possible delivery of the cooling air jets for the heat-sealed portions, is controlled by means of sensors 62. If the film is too much under stress during the closing of the unit 23, even before that the components of said unit are in reciprocal contact, the said sensors 62 intervene to signal to the microprocessor the necessity to reestablish the correct functioning of the machine. These same means intervene to stop the closing of the group 23 if due to accidental circumstances, during the travel downwardly of the bag, a product should move inside the said bag and should place itself in the way of said unit 23. If this situation occurs, the unit 23 immediately stops the closure movement, re-opens, the platform 29 descends until the upper level of the product is descended adequately under the optical barrier 32', while a corresponding quantity of film is unwind from the bobbin 7 driven into rotation by the motor 9. Only in a next phase the sealing and cutting unit 23 is carried back in the active working-stroke. The formed and closed bag, rests upon the platform 29 and is contained in a pit having a quadrangular section, formed laterally by means of lateral and fixed walls 33, 33' (see Fig. 6) and formed frontally by a vertical pusher 34 and by a door 35 hinged on a vertical axis 36, pushed in the active position by means of elastic means 37 and which is maintained closed by the co-operation with a lock 38 with which co- operates with its inferior side and which presents an appendix 138 on the plan overall dimensions of the platform 29.

The pusher 34 is connected to the moving element of a linear and horizontal actuator 39 fixed to the frame of the machine and driven by the electric motor 40. The wall 33 presents a horizontal cut 139 through which passes the connecting bracket of the pusher 34 to the actuator 39, while the wall 33 presents a vertical cut 130 through which passes the connecting bracket of the platform 29 to the actuator 30.

When the group 23 has finished its phase of sealing and cutting, the platform 29 completes its lowering stroke and disposes itself as shown in the Figures 2 and 6, coplanarly or with preference at a level slightly superior to the bottom wall 141 of a horizontal tunnel 41 , near to the actuator 39. In the descent end stroke position, the platform 29 co-operates with the appendix 138 of the lock 38 which is opened and pre-disposes the door 35 in the opening phase. In correct phase the actuator 39 is activated and with the pusher 34 pushes the filled and closed bag S to leave the formation pit and to translate in the discharging tunnel 41 , while the same bag pushes the door 35 in the opening phase.

In Figure 6, with the numeral references 34', 34" is indicated the pusher in two successive positions of its expulsion stroke of the bag S and it can be noted that even when the pusher has passed the door 35, this latter is maintained opened by the co-operation with a linear cam 42 made, for example, of "Polyzene" (trademark), fixed in a projecting manner upon the posterior front of the pusher 34. This condition allows the pusher to effect the inverse return stroke in the rest position, without interferences with said door 35. With numeral references 42' and 42" is indicated the cam 42 with the pusher in the corresponding positions 34" and 34".

From Figures 6 and 7 is noticed that during the phase of expulsion of the filled and closed bag S, the same bag interferes with the rounded arms 143 of a barrier 43, placed transversally in the tunnel 41 , which pass through horizontal slots 44 of a lateral wall of the same tunnel 41 , which are fixed upon a vertical shaft 243 rotatably supported by means of a fixed structure 343 and that by means of elastic means 443 are usually held in the interception position of the bags being discharged, but that under the pressure of the bag can oscillate toward the lateral wall of the tunnel and disappear in said slots 44.

The pusher 34 pushes the bag S beyond the barrier 43 and in order to not interfere with the arms 143 of this component, the same pusher is provided with transversal slits 45. When the pusher 34 has gone beyond the barrier 43, this latter elastically comes back in the rest position posteriorly to the bag, preventing the same to fall backwards when said pusher inverts its run to come back in the rest position. Before this phase, immediately after being abandoned by the pusher 24 in its active working stroke, the platform 29 has risen up and pre-arranged for the rest of the new bag in phase of formation and filling, in a manner which allows a high speed of production of the machine.

During the return of the pusher in the rest position, the elastic means 37 which control the door 35, carry back this component in the position of co-operation with the lock 38 and in a parallel position to the same presser. The details of the lock 38 and of the stop closing rabbets of the door 35 are not shown here, because the same are easily perceivable and realisable by persons skilled in the art.

At the exit of the machine, the bags filled and closed arrange themselves in single file in a rectilinear channel aligned and in prosecution of the tunnel 41 and from this channel the same bags can be easily taken and carried away by an operator. A sensor, not illustrated, detects the filling situation of the channel 46 and prevents the translation of the pusher to avoid the squashing of the packaged products. According to an embodiment not illustrated, instead of the channel 46 may be provided a conveyer system for the moving away of the bags, particularly suitable when several machines of the kind which is referred to operate in a same place and when the bags must be quickly transferred to the shipping place. From Figures 2, 3, 4 and 5 it is noted that in the superimposition zone of the longitudinal edges of the film for the bags formation, the hopper 18 is provided with a rectilinear and vertical slit 47 which starts before the superimposition of said edges, in order to allow the entrance inside of the same hopper and then inside of the tubular envelope formed by said film 107, of a small arm 148 downwardly oriented and that with the lower extremity supports a small rectangular base having the role of counter-welder, made of rubber, having a correct thickness, with suitable elastic features and sheathed with "Teflon" (trademark) or equivalent material 248 at least upon the face intended to the contact with the film. With the upper end, the small arm 148 is connected to the fix support 49 with the interposition of vibration-damping member 50 in metal-rubber. In contrast to the small base 48 acts the sealing head 51 formed by a metallic rectangular plate, which is covered upon the front toward the film with ceramic material and is provided with vertical and spaced rectilinear projecting parts 151 , which touch the same film to form corresponding rectilinear and continuous sealing lines Z. The welder 51 is heated by means of heating resistors housed in the same together with a thermostatic probe and the same welder is fixed upon the edge of a horizontal rod 52 sliding inside a guide block 53 made of suitable material having a low coefficient of friction, on its turn fixed upon the end plate 154 of an arm 54 fulcrumed on a vertical axis 55 supported by means of the fixed support structure 56 provided with an appendix 156 which extends toward the welder and which supports an electromagnet 57 the moving element of which is anchored to an appendix 254 of the arm 54. A helical spring 58 is assembled upon the fulcrum 55 to urge the arm 54 backwards from the counter-welder and to maintain the welder 51 in non-interference position with the film to be sealed when said electromagnet 57 is de-energised. The plate 154 supports upon the face opposite to the one which supports the guide block 53, an electric motor 59 with electronic speed control, upon the shaft of which is mounted an eccentric 60 connected by means of the connecting rod 61 to a fork 152 integral to the rod 52 with the welder, which because of said connection is moved with a rectilinear alternate movement to and from the counter-welder 58. When the electromagnet 57 is activated and when the welder 51 is in the position of maximum approach to the counter-welder 48, if between these two components should be not present the film, the same components would touch each other, so that the interposed film is subjected to the required compression to ensure a perfect execution of the heat-sealing of the superimposed edges of the film. Against this pressure react with correct rates of elasticity the counter-welder 48, the arm 148 which support it and the vibration dampings 50, in such a manner to avoid breakage of the heat-sealed material.

When, on the other hand, the welder 51 is in the position of maximum distance from the counter-welder 48, between the two components there is a distance equal or slightly superior to the thickness of the superimposed edges of the film 107 that the same components must seal.

Good results have been obtained giving to the eccentric 60 a speed rotation of about 1500 revolutions per minute when the tubular envelope of the film to be sealed advances with the maximum speed. The master microprocessor of the machine will provide for the automatic variation of the vibration frequency of the welder in connection with the longitudinal advancement movement of the film, according to laws which can be easily experimented on the machine. All the variables of the longitudinal sealing process, among which the unwinding speed of the bobbin, the instantaneous working temperature of the welder, the vibration frequency of the welder, the approach and removal speed of the welder by means of the electromagnet 57, are controlled and modified automatically by the main control processor of the machine, which ensures the performance of a continuous, uniform and with a perfect seal, also in unexpected working conditions. Only under these conditions it is possible to trap inside the closed bags a quantity of air which is sufficient to ensure a correct protection to the packaged products during the manipulation and the transport of the same bags.

As shown in Figure 2, the sealing and transversal cutting unit 23 can be provided under the cutting blade 223 and parallel with this one, with an ancillary and toothed-blade 323, to obtain in the closed bag, under the superior sealing and parallel to this one, some incisions which facilitate the tear opening, also to reutilize the same bag for the household waste collection.

The machine can be completed with means not shown, in order to carry back upon the bags in formation or already formed, the data relative to the serial number, to the nominative of the client, to the address and/or other, by example with a direct print with ink jet or with an adhesive label, the whole in a manner conceivable and easily realisable by a person skilled in the art.

Claims

1 ) A machine for forming bags from a continuos film of thermoplastic material and for the introduction of products inside the same bags during their formation, characterised by comprising in combination: - At least one pairs of rollers (6) parallel and powered (9), for supporting a bobbin (7) of the heat sealing film for the formation of the bags, placed in the lower and lateral portion of the parallelepipedal structure (1 ) of the base of the machine;

Rollers (11 - 11' - 11" - 13) for the transmission and for the buffer of the film (107) unwound by said bobbin (7), placed over this latter and laterally to the high portion of said base structure (1 );

A forming head unit (17) placed in the high portion of said base structure, to form a tubular and descending winding with the film (107) unwound by said bobbin, in said unit being inserted with clearance a hopper (18) useful for the insertion of the products in said tubular winding; - Means (20, 21 ) for drawing downwardly of said film tubular winding formed by means of said forming head unit (17);

Means (22) to obtain a continuous longitudinal and preferably tight sealing (Z) upon the longitudinal edges and reciprocally superimposed of the tubular winding of the film; - Means (23) to obtain upon the longitudinal winding, at least two transversal, parallel, continuous and preferably tight seals, and an intermediate cut, to close the head of the bag filled with products, to close the bottom of the following bag and to separate between them the same two bags;

A lifting platform (29) which inferiorly supports the bag during the formation phase;

A horizontal pusher (34) to discharge from said platform the filled and closed bag;

Anti-overturning means (43) to avoid the bags discharged from the platform (29) to fall backwards. 2) Machine according to claim 1 ) characterised by comprising means which allow the platform (29) to come back in the high position for the support of a new bag, immediately after that the pusher (34) has taken the bag away, even before the same pusher has done its reversal rest stroke;

3) Machine according to claim 1 ), in which the sealing and transversal cutting means (23) comprise means (323) to obtain upon the top of the cyclically filled and closed bag, weakening notches capable to facilitate the correct tear opening of the same bag and its reutilization for other purposes.

4) Machine according to claim 1 ), in which the buffer means of the film unwound from the bobbin (7), comprise a dancer roller (11") the oscillation of which is controlled by means of a selsyn (13) which in connection with the processor of the machine controls the motor (9) for the actioning of the unwinding rollers (6) of the bobbin, in correct phase with the longitudinal travel to which the tubular envelope is subjected by means of motorised drawing rollers (20, 21) which operate upon the four sides of the terminal inferior portion having a quadrangular section of the hopper (18) sustained by the upper edge of the covering (101 ) of the frame and inserted with clearance in the forming head unit (17), in contrast with said drawing rollers (20) being provided idle and parallel rollers (120) supported by means of flat springs (220) fixed to the walls of said hopper.

5) Machine according to claim 1 ) in which upstream of the transmission rollers of the film unwound from the bobbin, is provided an oscillating roller (11 ') which because of the connection to an elastic device (14) can be firmly placed in a rest position for the transmission of the film, or in the active contact position with a near neutral (idle) roller, to retain the tail of the same film in the phase in which this one is secured by means of a adhesive tape to the head of the film unwound from a new bobbin.

6) Machine according to claim 1 ), in which the hopper (18) for the loading of the products inside the bag in formation is provided in correspondence of the superimposed edges of the tubular winding which forms the same bag, with a vertical slot (47) which begins even before of the reciprocal superimposition of the said edges, so that inside of the winding can enter the arm (148) downwardly oriented, which carries on its lower end the longitudinal counter-welder (48) formed by means of a base of suitable thickness of a suitable elastomeric material with a Teflon coating (248) at least on the face in contact with the film, the superior end of said arm being placed outside of the winding, connected to a support (49) with the interposition of vibration dampers (50).

7) Machine according to claim 1 ), in which the welder for the sealing of the longitudinal and superimposed edges of the tubular winding of film, which run upon said counter-welder (48), comprises a metallic head (51 ) having a parallepipedal shape, provided with rectilinear and vertical ribs and opportunely displaced between them (151 ) upon the front destined to the contact with the film, which is treated to not adhere to the same film, said head being heated by resistors controlled by a thermostat and by suitable means carried in vibratory movement with a correct approach and displacement frequency with respect to the counter-welder.

8) Machine according to claim 7), in which at least the active surface of the sealer head (51 ) is provided with a coating of ceramic material which renders the same antiadherent to the film to be sealed.

9) Machine according to claim 7) in which there are provided means to vary the vibration frequency of the welder (51 ) as a function of the longitudinal travel speed of the tubular winding of the film, so that the longitudinal edges of said winding result provided with rectilinear, continuous and tight seals (Z).

10) Machine according to claim 7), in which the longitudinal welder (51 ) is driven to vibrate with a frequency of about 1500 cycles per minute when the winding travels with the maximum speed.

11) Machine according to claim 7), in which the welder (51 ) is fixed upon the end of a horizontal rod (52) which runs inside a guide (53) having a low coefficient of friction and that with the other end is connected by means of the connecting rod 61 to an eccentric (60) keyed on the shaft of a small electric motor (59) controlled by the processor of the machine to transmit to the welder the necessary working vibration. 12) Machine according to claim 7), in which the vibration stroke of the welder is such that in the forward stroke the same will reach substantially in contact with the counter-welder (48) if between the two portions there would not interposed the double layer of film to be sealed (107), while in the backward stroke the welder moves back from the counter-welder (48) in an equal or slightly superior manner to the thickness of the double layer of the film to be sealed, to allow the displacement of the tubular winding of the film.

13) Machine according to claim 7) in which the longitudinal welder (51 ) with its vibration means (52, 53, 59-61 ) is assembled upon a horizontal arm (54) predisposed to oscillate on a vertical axis (55) and that by means of elastic means (58) is normally pushed away from the film to be sealed, to carry away from this one said welder when the same film does not advance, the same arm being connected to an actuator (57) for example of the electromagnetic type, which upon command transfers said welder in the working position.

14) Machine according to claim 1 ), in which the transversal sealing and cutting means (23) are provided with sensors (62) which detect the movement of the sheet presser bar (123) during the closing phase of the same means for the sealing and cutting and means are provided to loosen the longitudinal stress on the section of tubular winding upon which act said sealing and cutting means and/or to invert the stroke of these same means if said sheet presser bar move before reciprocal touching.

15) Machine according to claim 14), in which means are provided for the start of the closing stroke of the sealing and cutting means (23) before the stop of the motor (9) which control the unwinding of the film (107) from the relative bobbin (7).

16) Machine according to claim 14) in which means are provided for the drive of the elevator platform (29) in a correct lifting stroke of the bag to be closed in correct phase with the closing of the sealing and transversal cutting means (23).

17) Machine according to claim 1 ), in which upstream and downstream of the sealing and transversal cutting means (23), are provided folders (27) which in correct phase with the intervention of said means, from which derive their movement, operate on the edges of the tubular winding to be sealed to form on these re-entering bellows plies.

18) Machine according to claim 1) in which on the superior portion of the tubular winding placed inside of the forming device (17) and under the lateral and inferior folder (27) are provided optoelectronic barriers (32, 32') the superior of which detects the presence of the product in the filling phase and can control the longitudinal movement of the film winding which forms the same bag, until the formation of a bag with a pre-arranged maximum height, while the inferior barrier is used to control the stop, with correct overstroke, of the descent of the filled bag, to ensure its correct positioning with respect to the sealing and transversal cutting means (23) so that the packaged products result positioned with security under these latter means (23).

19) Machine according to claim 1 ), characterised by the fact that the bag inferiorly supported by the elevator platform (29) when is pre-arranged for the superior closing by the sealing and transversal cutting means (23), is inserted for a large portion in a pit having a quadrangular shape, formed by lateral walls, fixed and parallel (33, 33') and formed on the other sides by the motorised pusher (34) that will eject the filled and closed bag from a door (35) pushed in closing position by means of elastic means co-operating with the inferior side of a lock (38) which maintains the same normally closed and parallel to said pusher (34). 20) Machine according to claim 19) characterised by the fact that when the elevator platform (29) is in the position of lower end-stroke, the same co-operates with an appendix (138) of the lock (38) which predisposes the door (35) in opening, so that the filled and closed bag, supported by said elevator platform (29) can be removed by the pusher in a near discharging tunnel (41) in which said door is maintained open by a linear cam (42) fixed backward to the same pusher (34) which can push the bag further out of the same door.

21 ) Machine according to claim 20) characterised by the fact that in the discharging tunnel (41 ) for the filled and closed bags (S), immediately downwardly of the door (35) in the opening position, are provided horizontal and rounded arms (143) of an oscillating barrier (43) which by means of elastic devices (443) are normally maintained in transversal position inside said tunnel, but that in the co-operation with the discharged bag, withdraw inside slits (44) provided in a lateral wall of the same tunnel and that when are surpassed by the bag, come back in the rest position, passing through suitable horizontal slits (45) of the pusher, the whole in such a manner that when this latter component comes back in the rest position, the arms of the barrier (43) retain the discharged bag and prevent the same to fall backwards, allowing to the door (35) and to the various operating means of the machine to come back in the working position.

22) Machine according to claim 20) characterised by comprising a guide channel (46) aligned and in prosecution with the discharging tunnel (41 ), to receive the filled and closed bags (S) cyclically discharged from the machine and by comprising sensors which detect the situation of said channel and which de-activate the functioning of the pusher (34) if the same channel results filled with bags.

23) Machine according to claim 20), characterised by comprising conveyer means to collect the filled and closed bags which come out from the discharging tunnel (41 ) and to convey the same bags in places distant from the machine.

24) Machine according to claim 20), characterised by comprising a door (401 ) made if necessary of transparent material, lateral to the inferior end stroke position of the elevator platform (29) to permit the displacement from this of bags trapped and useful in the first phases of the pre-arrangement of the machine to the automatic working, to correctly pre-arrange the film (107) in the forming head device