US3586577A

US3586577A - Bag sealing machine

Info

Publication number: US3586577A
Application number: US773769A
Authority: US
Inventors: Italo Della Bella
Original assignee: Individual
Current assignee: Individual
Priority date: 1967-11-11
Filing date: 1968-11-06
Publication date: 1971-06-22
Anticipated expiration: 1988-06-22
Also published as: FR1573348A; GB1195764A

Abstract

A MACHINE FOR FORMING BAGS FROM THERMOPLASTIC LONGITUDINALLY FOLDED FOIL IN WHICH THE FOIL IS INTERMITTENTLY FED TO A SEALING DEVICE IN PREDETERMINED LENGTHS CORRESPONDING TO THE DESIRED WIDITH OF THE BAGS, WITH THE SEALING DEVICE SEVERING THE FOIL AND SIMULTANEOUSLY SEALING THE SEVERED EDGES THEREOF.

Description

I. D. BELLA BAG SEALING MACHINE June 22, 1971 9 Sheets-Sheet 1 Filed Nov. v6, 1968 Inventor ITALO DELLA BELLA aygbmwu )MWMQE June 22, 1971 BELLA 3,586,577

v BAG SEALING MACHINE Filed Nov. 6, 1968 9 Sheets-Sheet 2 Inventor ITALO DELLA BELLA Y g kmlukFEM nNMmLJun a June 22, 1971 I. D. BELLA 3,586,577

BAG SEALING MACHINE Filed Nov. 6 1968 9 Sheets-Sheet 5 Fig. A

Inventor ITALO DELLA BELLA June 22, 1971 D. BELLA BAG SEALING MACHINE 9 Sheets-Sheet 4 Filed Nov. 6, 1968 Inventor ITALO DELLA BELLA June 22, 1971 L DBELLA 3,586,577

BAG SEALING MACHINE Filed Nov. 6, 1968 9 Sheets-Sheet 5 Fig. 7

Inventor ITALO DELLA BELLA June 22, 1971 l. D. BELLA BAG SEALING MACHINE 9 Sheets-Sheet 6 Filed Nov. 6, 1968 Inventor ITALo DELLA BELLA By SQ'fi Ou L ki n (MK uh" MAW b June 22, 1971 BELLA 3,586,577

BAG SEALING MACHINE Filed Nov. 6, 1968 9 Sheets-Sheet 7 LA 69 1 L 68 b5 A6 32 2Q 110 L? .2 1?: wgk

b3 4'? m Mn 70 Fig.1!

Inventor ITALO DELLA BELLA June 22, 1971 l. D. BELLA 3,585,577

BAG SEALING MACHINE Filed Nov. 6, 1968 9 Sheets-Sheet 8 Inventor ITALO DELLA BELLA By \bdCl/n M sh" (U m; y Lu/J June 22, 1971 DQQELLA 3,586,577

BAG SEALING MACHINE Filed Nov. 6, 1968 9 Sheets-Sheet 9 1 5 Fig. 7h

3O nu Inventor ITALO DELLA BELLA United States Patent @ffiC6 Patented June 22., 1971 US. Cl. 156-351 33 Claims ABSTRACT OF THE DISCLOSURE A machine for forming bags from thermoplastic longitudinally folded foil in which the foil is intermittently fed to a sealing device in predetermined lengths corresponding to the desired width of the bags, with the sealing device severing the foil and simultaneously sealing the severed edges thereof.

BACKGROUND OF THE INVENTION The invention relates to a machine for forming bags from a thermoplastic semi-tubular foil or a foil previously folded in a longitudinal direction, where the foil is fed to a sealing device intermittently in proper lengths corresponding to the desired width of the bag, with the sealing device operating to simultaneously separate and seal the foil at the resulting separated edges.

Known bag sealing machines of this type have the disadvantage that in the feeding device for the foil and in the ejection device for the sealed bags, there must be considerable play or free motion provided to guarantee an easy running, smooth operating process. However, this clearance or free motion produces considerable differences in the width of the bags prepared, which in practice may amount to as much as two to three centimeters.

SUMMARY OF THE INVENTION Accordingly, the primary object of the invention is to provide a bag sealing machine capable of producing bags in which the differences in width of the bags produced is unnoticeably small. In any event, any differences in width of the plastic bags produced will be so small that such bags can be used without any difficulty in automatic vending machines or other machine installations.

The primary object as set forth is accomplished by the invention in which the feeding arrangement for the foil located immediately before the sealing device comprises a pair of rollers with a reverse stop mechanism, while the device for taking-up and ejecting the formed bags, located immediately after the sealing device, is provided with a driving arrangement of its own, controlled, however, by the drive mechanism for feeding the device. As a result, one predetermined length of foil once delivered to the sealing device cannot be pulled back in the reverse direction by the tension device for the foil or other machine parts as was the case in known bag sealing machines. The predetermined length of foil assigned at one time to the sealing device will thus actually determine and correspond to the final width of the bag.

Another object of the invention is to provide a bag sealing machine in which the feeding arrangement for the foil, locked against return movement, will hold the foil in constant tension between the tensioning device and the feeding device when the feed rollers are stationary, so that the feeding device operates even at the beginning of the feeding process against the tension of the foil and tensioning device, and thus will become effective only after any play in its drive mechanism has been taken up or neutralized.

Still another object of the invention is to provide a bag sealing machine in which any kind of jerk at the beginning of the foil feeding step will be avoided through the maintenance of the constant foil tension between successive feeding steps so that no momentary sliding of the feed elements across the foil and no stretching of the foil by such a jerk can occur.

A related object of the invention is to provide a bag sealing machine in which the clearance or play motion in the drive for the feeding device will be avoided without any excessively large expenditure of money required for this purpose.

A further object of the invention is to provide a bag sealing machine of the above described type where the driving arrangement for the feeding device for the foil contains a crank assembly including a free-wheeling rocking lever drive, which is adjustable to permit adjustment of the desired width of the bag to be formed.

Still a further object of the invention is to provide a bag sealing machine of the above described type where the driving arrangement for the feed device contains an electrically controlled coupling element for the timely interruption of the driving connection and where electric probing devices are arranged in the path of movement of the foil or of the bags, the probing devices controlling the coupling element to interrupt the drive connection, with the probing devices being adjustable along the path of movement of the foil or of the finished bags to set the desired width of the bags.

Another object of the invention is to provide a machine for forming bags from thermoplastic synthetic semitubular foil or foil previously folded in a longitudinal direction, the machine comprising a device which simultaneously separates and seals the foil at the proper separated edges with a heated separating-welding element guided essentially perpendicularly from top to bottom through the foil and subsequently returned between the welded edges to its raised rest position. An arrangement is provided to lift at least the welded edge of the finished bag from the area of movement of the separating-welding element as it is returned to its raised position. Finally, a related object of the invention is to provide a bag sealing machine of this type in which both welded edges are lifted from the area of movement of the separating-welding element as it returns to its rest position.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation view illustrating a first embodiment of the bag sealing machine of the invention;

FIG. 2 is an enlarged fragmentary view of the section IIII of FIG. 1;

FIG. 3 is an enlarged fragmentary view of the section III-III of FIG. 1;

FIG. 4 illustrates an electric control circuit for the bag sealing machine embodiment of FIGS. 1 to 3;

FIG. 5 is a view similar to FIG. 1 but illustrating a second embodiment of the bag sealing machine;

FIG. 6 is an enlarged fragmentary view of the section VIVI of FIG. 5;

FIG. 7 illustrates an electric control circuit for the bag sealing machine of FIGS. 5 and 6;

FIG. 8 is a schematic fragmentary illustration of the foil feeding device, of the separating-welding device and of the take-up and ejection device for the bags of a bag sealing machine, with structural arrangements at the feed side of the foil and at the departure side of the finished bags for lifting the welded edges from the path of movement of the separating-welding element;

FIG. 9 is a fragmentary illustration of the cam control mechanism for the device of FIG. 8;

FIG. is a fragmentary illustration similar to FIG. 8 with the parts positioned at the beginning of the separating-welding processs;

FIG. 11 is a fragmentary illustration similar to FIG. 8 with the parts positioned after completion of the separating-welding process;

FIG. 12 is a view similar to that of FIG. 8 illustrating however only one structural arrangement at the departure side of the bags to lift the welded edge from the path of movement of the separating-welding element;

FIG. 13 is a view similar to FIG. 12, with the parts positioned after completion of the separating-welding process;

FIG. 14 illustrates a third embodiment of the lifting arrangements at the foil intake side and the departure side of the bags, in which the welded edges may be lifted from the path of movement of the separating-welding element in the shape of flaps which can be swung upwardly, with the parts positioned shortly before commencement of the separating-welding process, and

FIG. illustrates the device according to FIG. 14 with the parts of positioned during the return of the separating-welding elements to its rest position.

PREFERRED EMBODIMENTS OF INVENTION Referring to FIGS. 1-3, a machine frame 1 has two upper lateral carrier and mounting plates 2 facing each other and carrying a roll of foil 3, a foil feeding device 4, a welding device 5 and a take-up and ejection device 6 for the bags. Between the roll of foil 3 and feeding device 4, and a foil tension and guide device has been arranged which is formed by a foil tensioning device 7 pivotally mounted on the machine frame 1 and

guide rollers

8a, 8b and 8c mounted on plates 2.

The foil feeding device 4 comprises two counter rotating rubber feed rollers (see FIG. 2) contacting opposite sides of the foil web 10. These

rubber rollers

11 and 12 are formed with peripheral grooves 13 with which stripper elements 14 engage, in order to guide the foil safely into the operational area of the welding device 5.

An electric motor 15 with a built-in automatic locking gear system is provided for the drive of the foil feeding device 4. Motor 15 through chain drive 16 drives a control shaft 17, from which, as will be explained later, the cam mechanism for reciprocating the welding device 5 is driven, with shaft 17 also being provided with electric control elements for the machine.

In FIGS. 1 to 4, crank 18 is fixed on one end of control shaft 17. The crank pin 19 is adjustable radially of shaft 17 as shown in FIG. 3. A connecting rod 20 is attached to

crank

18, 19 and drives a freely running pivoted lever drive 21 on shaft 22 so that every revolution of the

crank

18, 19 causes a partial revolution of shaft 22 as determined by the adjustment of the crank element 19. Lever 21 only drives shaft 22 when it is pivoting in the direction of the arrow, and when it pivots in the opposite direction, it is free running on shaft 22. This partial revolution of shaft 22 is transferred to the axis 24 of lower rubber roller 12 by a chain drive 23. Intermeshing spur gears 26a and 26b are attached on driving shaft 24 of the lower rubber roller 12 and driving shaft of the upper rubber roller 11. On shaft 25 a one-way freely running drive 27 locks against return revolution of shaft 25, so that a unidirectional drive is provided between

shafts

24 and 25. Thus upper rubber roller 11 is driven in a counter direction to but at equal speed relative to roller 12.

The Welding arrangement 5, as shown in FIG. 2 contains two relatively stationary lower clamping girders 28 which can be provided with a coating on their top side, on which coating the foil 10 that is to be finished will not slip. Opposite to and above the fixed clamping girders 28, perpendicularly movable clamping strips 29 are arranged. These clamping strips 29 are each perpendicularly movably mounted on and with respect to guide arms 30 which in turn are perpendicularly movably mounted at each side of the machine. Strips 29 are biased downwardly by springs 31. Between the guide arms 30 extends the transverse severing separating and welding wire 32. The two guide arms 30 are secured at their upper ends to a guide girder 33 extending transversely across the machine, and guide rods 34 at each side of the machine are secured at their upper ends to girder 33. The guide rods 34 each slide perpendicularly in a guide pedestal 35 attached at the outside of the machine frame 1, and the holding and mounting plates 2 and operating springs 36 bias the rods 34 downwardly. Each guide rod 34 carries at its lower end a probing roller 37, running on a rotating cam 38. These cams 38, arranged at each machine side, are fixed on a common cam shaft 39 driven by a chain drive 40 from control shaft 17. The cams 38 simultaneously act to hold the welding device 5 against action of the springs 36 in its rest or inactive position. Cams 38 release springs 36 during their rotational movement, and then the springs displace the welding device 5 downwardly, whereby at first the clamping strips 29 will press the foil 10 firmly against the clamping girders 28 and then, upon continued downward movement of arm 30, the hot wire 32 contacts and passes through the foil 10 and, in doing so, cuts it and welds it at along the two edges that develop at opposite sides of the cut as a result of the cut. Thus the adjacent bag sides are welded shut at this point. Upon further revolution of the cams 38 Welding device 5 is again lifted into its rest position shown in FIG. 1.

The take-up and ejection device 6 is arranged forwardly of the welding device and contains lower conveying belts 41 driven by a peripherally grooved driving roller 42 and passing over tension and guide rollers 43. In preferred embodiment shown, several, for example four, conveying belts 41 are provided at a mutual lateral distance apart and running parallel to each other. Above conveying belts 41, pressing belts 44 are provided and these are similarly driven by a peripherally grooved driving roller 45 and pass over tension and guide rollers 46. The pressing belts 44 are provided in the same number and arrangement as belts 41, one pressing belt 44 being above each conveying belt 41 in the assembly. For the drive of take-up and ejection device 6, a special driving motor 47 is provided controlled by switches 50* (FIG. 3) arranged on the control shaft 17. For uniform drive of conveying belts 41 and pressing belts 44, the driving shafts of driving

rollers

42 and 45 carry intermeshing

spur gears

48a and 48b at one of their ends. A cam drive is provided between driving motor 47 on the shaft of driving roller 42 by chain drive 49. The driving motor 47 is such that the linear running speed of both the conveying belts 41 and the pressing belts 44 is higher in each case than the peripheral speed of the

rubber feed rollers

11 and 12 of the feeding device 4.

The method of operation of the machine shown in FIGS. 1 to 3 will now be explained in detail with reference also to FIG. 4.

Upon switching on main supply switch HS, the heating circuit of the separating and welding wire 32 is immediately energized through a transformer Tr or a series resistance. Also, upon closing of main switch HS, a voltage control instrument SG is activated immediately, which supplies the various control circuits of the machine. The main control circuit of the machine extends from control voltage device SG to a safety and time switch T, which is controlled by the heating circuit of the separating and welding wire 32. When the heating current is cut off, this safety switch opens and thus interrupts the main control circuit. Upon supplying the heating current to the separating and welding wire, first a time element contained in the safety and time switch T will act, which allows the main control circuit to be closed only after a certain amount of time has elapsed after switching on the heating current, which is sufficient to heat the separating and welding wire to the required temperature before the main control circuit is energized.

In the embodiment shown, the main control circuit runs from safety and thime switch T via two apparatus switches G51 and GS2 connected in parallel and one of which is to be operated by hand and the other one may be operated automatically by a bag finishing device (not shown). For operation of the machine, closure of one of these switches GS13 or GS2 is necessary, but both switches may also be closed at the same time. The main control circuit runs from the switches G51 and GS2 to the switch-on winding of a switch relay S1 for motor 15 of the drive for the foil feeding device 4 and welding device 5. The energized motor 15 causes a revolution of the control shaft 17 on which cams 51 for the control switches 50 have been arranged. Furthermore, the revolving movement of shaft 17 drives the feed device 4, so that the

rubber rollers

11 and 12 will take up a length of foil from roll 3 corresponding to the radial adjustment of the

crank drive

18, 19, via the tensioning device 7 and the guide rolls 8a and 8b, 8c. At the same time, when the foil 10 if a semi-tubular type foil, especially one with sides of varying length, the

guide rollers

8a, 8b and 8c are made of metal and are in electrically conductive connection with the machine frame, which itself will be grounded via the Zero conductor of the main supply grid connection. Therefore, the

guide rollers

8a, 8b and 80 will bleed any accumulated electrostatic charge from the semi-tubular foil 10. The length of foil delivered by the rubber rollers is guided via the strippers 14 through the area of the welding device 5 and is grasped by the take-up and ejection device 6. For control of the motor 47 of the take-up and ejection device 6, a switch m3 is provided in the cam and switch set 50, 51 on the control shaft 17, and applies control voltage from the control voltage device SG to the switch-on winding of the -switching relay S2 of motor 47. The take-up and ejection device 6, therefore, is switched on via this secondary control circuit immediately after conclusion of the movement of the welding device 5 in order to eject the bag which has just been welded and separated, and to grasp and take up the next length of foil delivered and guided by the rubber rollers 11 and 12and to pre-tension it for the next welding process. The time required for the operation of welding device 5 is provided when the crank and the

free running drive

18, 19, 20, 21 initially move through a no-load stroke cycle as lever 21 moves freely on shaft 22 in a direction opposite to that of the arrow. The effective driving stroke will move

rubber rollers

11 and 12 to deliver a length of foil to welding device 5 during the second half of the revolution of the control shaft 17 when lever 21 moves in the direction of the arrow.

At the conclusion of the revolution of the control shaft 17, the switches m1 and m2 contained in the set of cams and switches '50, 51 are operated. The switch m1 switches the control voltage from the control voltage instrument SG to the shut-off winding of the relay S1, so that motor is switched off. The switch m2 switches the control voltage from the control voltage instrument SG to the charge winding of the relay S2, so that motor 47 is also switched off. The relays S1 and S2 can be provided in a known manner with mechanical or electrical automatic holding arrangements which will keep the motor switches closed in the time between actuating the switching-on winding and actuating the switching-off winding.

A predetermined tension is maintained on foil 10 between the roll 3 and the pair of

rollers

11 and 12 up when they are not feeding foil by the lock pinion 27 on the upper rubber roller 11 and the brake provided in the customary manner at the roll of foil 3. Through use of a self-locking geared motor 47 in the drive of the takeup and ejection device 6, the tension on the length of foil extending from the

feed rollers

11, 12 through the area of welding device 5 and taken up by the take-up and ejection effective only when the welding process has been completed and the welding device 5 is again in its rest position and the take-up and ejection device 6 has already started the ejection process of the finished bag. Because tension is constantly applied on the foil 10, any clearance or play in the drive of the

rubber rollers

11 and 12 is taken up before the feed device becomes effective.

In the example of FIGS. 5 to 7, the basic structure of the bag sealing machine is the same as that in the example of FIGS. 1 to 4, therefore the same reference numbers are used for the same elements.

The bag sealing machine according to FIGS. 5 to 7 differs from the first embodiment given by way of example of FIGS. 1-4 in that it includes a second small sprocket wheel 11 attached on one end of the control shaft 17, from which a driving chain 112 leading from wheel 111 to a sprocket wheel 113, which in disposed via an electrically controlled coupling 114 on intermediate shaft 22. The electric coupling 114 is of a known type and operates in such a way that it establishes a driving connection between the sprocket wheel 113 and shaft 22, as long as electric current flows through it. Whenever the flow of electric current is interrupted, the electrically controlled coupling 114 will interrupt the driving connection between sprocket wheel 113 and shaft 22. The remaining parts of the driving arrangement, that is to say the driving motor 15, the chain drive 16 to the chain wheel 18 on the control shaft 17, and the chain drive 23 on the shaft 24 of the lower rubber roller 12, are the same as in the embodiment of FIGS. 1 to 4.

Photoelectric control assemblies

115 and 116 are provided for the control of the electrically controlled coupling 114. These

assemblies

115 and 116 will be used alternatively and one of them must always be attached in the machine and must be in operation in order 0 operate the electrically controlled coupling 114. As illustrated in FIG. 6, one of the photoelectric probing and control devices 115 is arranged along the path of movement of foil 10 before the pair of

feed rollers

11 and 12. This probing and control device 115 includes a lower part 117 containing a source of light, and of an upper part 118 containing the photoelectric element, e.g. a photoelectric cell, a photoelement or a photoresistance. The two parts 117 and 118 are attached to a common support 119, which is supported from and guided along the inside of one of the lateral carrying and mounting plates 2 in a slot 120. The probing and control arrangement 115 can be adjusted by support element 119 along the path of movement of foil 10 to provide a desired width of the foil, so that the cut produced by the separating and welding wire 32 is properly positioned to produce a bag of proper width. The probing and control device 115 operates in such a manner that the source of light illuminates from the lower part 117 through the foil 10 and corresponding to arrow 121, into the upper part 118. As long as the photoelectric element 118 is illuminated, it maintains the circuit for the coupling 114 in a closed state, so that transmission of driving power from the motor 15 up to feed

rollers

11 and 12 occurs. As soon as a special marking imprint provided on foil 10, e.g. a control marking, comes into the area between the light source in the lower part 117 and the photoelectric element in the upper part 118 of the probing and controlling device 115, the illumination of the photoelectric element is interrupted and, as a result, the coupling 114 is deenergized so that the drive between the motor 15 and the

feed rollers

11 and 12 is interrupted, and the

feed rollers

11 and 12 stop and cannot rotate backwards because of the stop mechanism 27 that is built in. Foil 10 provided with the proper marking imprints will thus be brought into the precise welding position in order to seal a bag of predetermined width.

When the foil 10 is not provided with such marking imprints the second probing and control device 116 is utilized instead of assembly 115 and is attached to the machine in the area of the bag take-up and ejection device 6. The probing and control device 116 consists of a light source 122 directing a focused ray of light 123 on the sector 110 of the foil passed or threaded into the bag take-up and ejection device 6, and of a part 124 containing the photoelectric element which receives the rays of light 125 reflected by sector 110 of the foil. This probing and control device 116 operates in such a manner that it will keep the circuit for the operation of the coupling 114 in a closed energized state as long as no light is reflected to the part 124, i.e., the sector 110 of the foil has not come into the region of the light rays 123, so that the light rays 123 will move forwardly along the direction of broken arrow 123. As soon as the leading edge of sector 110 of the foil gets within the area of light rays 123 and reflects the rays along arrow 125 into the part 124 of the probing and control device 116, the circuit for the operation of the coupling 114 will be interrupted and the coupling will be deenergized. As a result, the driving connection between motor 15 and

feed rollers

11 and 12 of the foil is interrupted, and the rollers will then stop and be locked against backward reverse movement by the stop mechanism. Thus, the length of foil 110 will be measured precisely to correspond to the desired width of the bag, and will be positioned between the separating-welding device and the bag take-up and ejection device 6. For a precise adjustment of the desired width of the bag, the two

parts

122 and 124 are attached on a carrier plate 126, which can be adjusted along the path of movement of the foil in a slot 127 on the inside surface of one of the lateral carrier and mounting plates 2.

The method of operation of the bag sealing machine in this embodiment is substantially the same in its essential parts to the method of operation of the embodiment according to FIGS. 1 to 4, with like reference symbols applied to like element in FIG. 7.

A bag forming process is initiated upon closure of one of the switches G81 and GS2' which closes switch S1 to energize motor 15 and drive control shaft 17 and cam shaft 39. The separating-welding process and the control of the bag take-up and ejection device 6, therefore, run their course in the same manner as described in connection with FIG. 4. However, the control shaft 17 in its cam and switch set 50", 51 has an additional control cam m4 and its cooperating controlled contacts. This cam m4- has been set up in such a manner that it will close its contacts as soon as the separating-welding device 5 has again been lifted or raised to its rest position through its cams 38. When this occurs, the exciter coil of switch S3 is fed current via the contacts of cam m4. A coupling 114, designated with C in FIG. 7, is then excited via the rectifier G and is coupled so that the driving connection from the motor 15 to the

feed rollers

11 and 12 is established. The

feed rollers

11 and 12 will then deliver a length to foil 110' past the separatingwelding device 5 into the bag take-up and ejection device 6.

As FIG. 7 shows, an operator may selectively introduce one of the probing and controlling

devices

115 and 116 into operation by means of

plugs

130, 131 and 132. If, for example, the probing and control device 115 is to be used, the foil 10 provided with marking imprints 133 is moved and delivered through

feed rollers

11 and 12 until an imprint 133 is positioned in the path of the light passing from the light source 134 to the photoelectric device 13-5. The imprint 133 blocks passage of the light between

elements

134 and 135, which generates a control impulse which is carried to the release winding of the switch S3 to open switch 8-3. As a result, coupling 114 is uncoupled and the driving connection between motor 15 and

feed rollers

11 and 12 is interrupted.

Since the feed rollers 11 and 1'2 must constantly operate against the pull created by the tension device 7 on the foil 10, the rollers upon interruption of the driving connection by clutch 114 will immediately stop, so that the length of foil which has been delivered corresponds precisely to the distance between successive imprints 133.

When the probing and control device 116 is to be used the light rays 123, produced by the light source 122, will initially pass in the direction of arrow 123. As s o as the leading edge of foil sector 1-10 reaches the region of light rays 123, the light is reflected in the direction of arrow 125 to the photoelectric device 124 to produce an impulse which is fed to the release coil of switch S3. This causes switch S3 to open and the coupling 114 to be released thereby immediately stopping the

feed rollers

11 and 12.

In both cases the transmission ratio of chain drives 112, 113, 23, 24 is such that the drive of the

feed rollers

11 and 12 corresponds to only a relatively small fraction, e.g. one-fourth of a revolution of the control shaft 17. The coupling 11'4 therefore, is released before the control shaft 17 has executed or completed one full revolution. Motor 15 then continues to run in order to drive the control shaft 17 through a complete revolution of 360". During the last part of this revolving movement of the control shaft 17, the switch 1112 for stopping the bag take-up and ejection device 6 and the switch ml for stopping motor 15 are operated in the same manner as described above with reference to FIG. 4. The two

light sources

134 and 122, according to the arrangement of FIG. 7, are switched on continuously during the operation of the machine via the transformer Tr2. However, it is also possible to connect the

light sources

134 and 122 from the transformer TrZ via the

plugs

130, 131 and 132, so that only the

light source

134 or 122 of the selected probing and control device or 116 which is in operation will receive current.

:FIGS. 8 to 15 show additional embodiments of bag sealing machines where a semi-tubular foil 10 made of thermoplastic synthetic material or a thermoplastic foil previously folded in longitudinal direction is fed intermittently in lengths corresponding to the desired width of the bag to a separating-welding arrangement. The separating-welding arrangement in the case of the bag seal ing machines in FIGS. 8 to 15, for a simultaneous separation and welding of the foil 10, operates at the proper separating edges with a heated separating-welding element 32, which for this purpose is guided essentially perpendicularly from above to below through the foil 10 and subsequently between the welded edges from below to above back into the rest position.

The device shown in FIGS. 8 to 15 form an especially complement for the bag sealing machines described above but they can also be used with bag sealing machines whose foil feeding arrangements differ from those described above.

'In the embodiment illustrated in FIGS. 8 to 11, additional structure is provided at both sides of the separating and welding wire to lift the welded bag edges from the area of movement of the wire 32. For this purpose on one s1de of wire 32 a flap 61 is attached inside the lower clamping girder 28, and is mounted on a horizontal rotatable shaft extending parallel to the lower clamping girder .2 8, the shaft having lever 62 extending obliquely downwardly therefrom. The plunger 63 of an electromagnetic coil 64 is connected to lever 62, so that upon energlzation of coil to pull plunger 63, the flap 61 will swing upwardly into the position shown in a broken line in FIG. 8 and full line of FIG. 11. For the purpose of receiving the flap, both clamping girders 28 and 2-9 have an L-shaped profile 'as shown in FIGS. 8 to 11.

A pair of

brackets

65, 66 are arranged on the other side of the separating and welding wire 32 between the wire and the take-up and ejection device 6 as a second device to lift the welded edge from the area of movement of the separating and welding element 32. The upper bracket 65 is held similarly to the upper clamping girder 29 perpendicularly slidably on the guide and bearing arm 30 against the action of a spring 67. The lower bracket 66 is guided axially slidably by at least one, preferably two, rods 70 at point 71 between holding and mounting plates 2 and at

points

72 and 73 inside the machine frame 1. A spring 75 which urges the bracket rod 70 downwardly is positioned between the upper guide 71 and a collar 74 attached to the rod 70. Each bracket rod 70 carries at its lower end a follower roller 76, which runs on a cam 77. The cams 77 are attached on the same shaft 39 as are the operating cams 38 for the separating-welding device 5, so that the lower bracket 66 is controlled positively together with the separating-welding device 5.

The operation of the embodiment shown in FIGS. 8 to 11 will now be described.

If, as shown in FIG. 8 a length of foil corresponding to the predetermined desired width of the bag is positioned between

feed rollers

11 and 12 and conveying belts '41 and the pressing belts 44, the cam shaft 39 controlling sealing device is rotated by operation of the control system described above. As shaft 39 and

cams

38 and 77 rotate counterclockwise from the position of FIG. 9 roller 37 will ride onto the flat area of cam 38 thereby causing spring 36 to pull the guide and carrying arms 30 together with the separating and welding wire 32, the upper clamping girder 29 and the upper bracket 65 downwardly. In the position shown in FIG. the upper clamping girder 29 rests on the foil 10 and the upper bracket 65 with its bracket carrier 68 rests against a stop 69 attached to the guide and mounting plates 2. In this position of the device, the foil 10 is clamped firmly between

girders

28 and 29 on one side of wire 32 in the direction of the

feed rollers

11 and 12. The upper bracket 65 has progressed with its lower edge to below the plane of the foil 10 and has, as a result of that somewhat pulled back the length of foil 110 between the conveying belts 41 and the pressing belts 44 and clamped and tensioned them across the upper edge of the lower bracket 66. As a result, the

brackets

65,66 function as a pair of smoothing strips, which produce a fold-free stretching of the foil 10 in the operational region of the separating-welding device 5. Upon continued downward movement of the guide and carrying arms 30, the upper clamping girder 29 and the upper bracket 65 will stop, so that the

springs

31 and 67 will be compressed. The separating and welding wire 32 will pass through the foil and sever the latter, whereby each of the two severed edges of the foil i welded as to form the lateral seams or side edges of adjacent bags. As cam shaft 39 continues to rotate, roller 37 again runs onto a raised part of the cam 38 to initiate upward movement of the guide and carrying arms 30. Simultaneously, the following rollers 76 run up on the raised part of cam 77, so that the lower bracket 66 is lifted vertically to a position horizontally aligned with the upper bracket 65. With that, the second lateral edge of the length 110 of the bag, which has just been produced, is lifted, as FIG. 11 shows, from the path of movement of the separating and welding wire 32. At the same time, the relay 64 is activated from the main control, so that it will pull its plunger 63 and thus deflect the flap 61 upwardly in the free space formed by the L-profile of the two clamping

girders

28 and 29 and, as a result, will lift the first welded edge of the next foil length upwardly out of the area of movement of the separating and welding wire 32. The separating and welding device 5 can thus move back upwardly into its rest position, without the separating and welding wire 32 coming into contact with the previously formed welded edges. The cam shaft 39 will revolve back to its normal position, shown in FIG. 9 in which the roller 37 rests on the highest projection of cam 38 and the probing roller 76 on the flat part of cam 77, thereby returning the lower bracket 66 to its normal position, shown in FIG. 8 under the action of the spring 75. In addition the main circuit control will run up to its normal position, in which the relay 64 is deenergized and the operating bar 63 has returned again into its extended position, shown in FIG. 8 under the action of built-in spring, and the flap 61 will again be pivoted back into the flat rest position. The described operation will then be repeated to form a desired quantity of bags.

In the embodiment illustrated in FIGS. 12 and 13, the basic structure of the device is substantially the same as that shown in the example of FIG. 11 with like parts being designated by like numerals.

In the embodiment of FIGS. 12 and 13, only the upper bracket 65 and the lower bracket 66 have been provided to lift the welded edge of the formed bag'from the area of movement of the separating welding wire 32 and to function as a pair of smoothing elements. The construction of these

brackets

65 and 66, as well as their method of operation, are the same as those in the embodiment of FIGS. 8 to 11.

In the embodiment of FIGS. 14 and 15, the same structure of the bag sealing machine and its separating-welding device 5 are assumed to exist as in the example of FIGS. 8 to 13 so that like parts again are indicated by like reference numerals. However, in the example of FIGS. 14 and 15, the foil smoothing function and the finished bag edge lifting function are performed by separate apparatus. To accomplish this the guide and carrying arms 30 at the side facing the take-up and ejection device 6 carry an upper smoothing strip 81, which is attached to the guide and carrier arms 30 and is slidable therealong against the action of springs 82. This upper smoothing strip 81 acts together with the lower smoothing strip 83 attached firmly to the machine frame. In addition, the lower fixed smoothing strip is provided on its topside with a bevel 84 directed backwardly and downwardly, while the upper smoothing strip 81 has a lower edge 85 formed by two bevels, which settles at a distance behind the bevel 84. Upon downward movement of the guide and carrier arms 30, the upper smoothing strip will reach its lowest position when its projection 86 abuts stop 87 fixed to the frame. In this position the lower edge 85 of the upper smoothing strip 81 lies at a horizontal distance behind bevel 84. At the same time, the upper smoothing strip 81 through its lower edge 85 will pull the foil length 110 back somewhat between the conveying belts 41 and the pressing belts 44. As a result, the foil 10 will be held without jamming, as can be seen in FIG. 14, between the smoothing strips 81 and 83 and is stretched smooth in the area of the separating-welding device 5.

In the example of FIGS. 14 and 15, two

flaps

91 and 92 are provided to lift the just welded edges from the path of movement of the separating and welding wire 32. The flap 91, lying in the direction toward the

feed rollers

11 and 12 are pivotally mounted in the lower clamping girder 28, as in the example of FIGS. 8 to 11. It is held in its normal position shown in FIG. 14 by means of a spring not shown here. For the purpose of swinging flap 91 upwards, at least one of the guide and carrying arms 30 carries a driver hook 93, which is pivotally mounted around an axis 95 at the upper part of the hook shaft counter to the action of a spring 94. The flap 92, arranged between the separating and welding wire 32 and the takeup and ejection device 6, as shown in FIGS. 14 and 15, has a swiveling lever 96, which is connected to the shaft 97 of an electromagnetic relay 98. The shaft 97 is held in its rest position, shown in FIG. 14, by means of a spring 99, whenever the relay 98 is deenergized and upon excitation of the relay 98, it is pulled into the position shown in FIG. 15, in which the flap 92 is pivoted upwardly by lever 96 as shown in FIG. 15.

Starting from the position of FIG. 14, if the guide and carrier arms 30 are moved downwardly in the direction of the arrow during the separating and welding process, the heated separating and welding wire 32 passes through the foil to sever it and simultaneously to form and weld two edges of successive bags. During this downward movement, the driver hook 93 passes around the free edge of flap 91 and at the same time, the driver hook 93 will stop under the effect of the spring 94 behind the free edge of the flap. The downward movement in the direction of arrow 100 and the subsequent movement upward in the direction of arrow 101 is produced in the same manner as explained in connection with the example according to FIGS. 8 to 11. Upon beginning the upward movement in the direction of arrow 101, the relay 98 is energized by the main circuit control, so that it will pull shaft 97 against the action of spring 99 and will pivot flap 92 upwardly. As a result, as shown in FIG. 15, the severed end of the bag length 110 provided with the welded edge is pulled back between the smoothing strips 81 and 83 and out of the area of movement of the separating and welding wire 32. In the case of the upward movement of the guide and carrier arms 30, the driving hook 93 also carries the free edge of flap 91 upwardly, so that this flap 91 is similarly swung upwardly, and, in doing so, will lift the just formed, welded edge of foil 10 from the area of movement of the separating and welding wire 32. Toward the end of the upward movement in the direction of arrow 101, the fiow of current through relay 98 is switched off, so that its plunger 97 returns to its rest position as in FIG. 14, under the action of spring 99 and pivots flap 92 back to its starting position. During the upward movement in the direction of arrow 101, the driver hook 93 runs oi the free edge of the flap 91, so that flap 91 too will return to its rest position, shown in FIG. 14, through its return spring or at least because of its own weight. The return of

flaps

91 and 92 into their rest position, however, takes place at a time when the separating and welding wire 32 has already been lifted to a point where it can no longer come into contact with the previously formed welded edges.

What is claimed is:

1. A machine for forming bags from a continuous Web of semi-tubular foil of thermoplastic synthetic material or a previously longitudinally folded foil of such material comprising intermittent feed means for periodically advancing said Web in a predetermined direction and comprising a pair of rotatable feed rollers defining a pass between which said foil is received and drive mechanism for intermittently rotating said rollers, stop mechanism permitting rotation of said rollers only in the foil feeding direction, foil severing and welding means in the path of said web operated in synchronism with said intermittent feed means for severing the web into succes sive sections of predetermined length corresponding to the desired bag width and Welding together the severed edges of the web and the severed section lying at opposite sides of said severing and welding means, bag feed and ejection means for moving the formed bags in succession away from said severing and welding means, drive means for said bag feed and ejection means, and means for controlling actuation of said bag feed and ejection means in timed relation with said intermittent feed means and said severing and welding means.

2. Bag forming machine according to claim 1, wherein said rollers are mutually driven through cooperating spur gears, and said stop mechanism acts between a shaft casing one of said rollers and the frame of said machine.

3. Bag forming machine according to claim 1, wherein the drive mechanism for said foil feeding rollers includes a crank assembly with an attached free-wheeling rocking lever drive, said crank assembly being adjustable to vary the foil lengths fed toward said severing and welding means.

4. Bag forming machine according to claim 1, wherein said drive mechanism for said foil feeding rollers includes an electrically controlled coupling element for interrupting the drive connection to said feed rollers, and probing means arranged along the path of movement of the foil for controlling said coupling element.

5. Bag forming means according to claim 4, wherein said probing means is adjustable along the path of movement of the foil for selecting a desired width of the finished bag.

6. Bag forming machine according to claim 4, wherein said probing means comprises a photoelectric probing device which responds to marking imprints aflixed on said 12 foil at regular intervals corresponding to the desired width of a bag, said photoelectric device being operative to deenergize said coupling element in response to sensing one of said imprints, thereby interrupting the driving connection for said foil feeding rollers.

7. Bag forming machine according to claim 4, wherein said probing means comprises a photoelectric probing device which responds to the positioning of the leading edge of said foil in said bag feed and ejection device, said photoelectric device being operative to deenergize said coupling element to interrupt the driving connection to said foil feeding rollers.

8. Machine for forming bags made from a semi-tubular foil of thermoplastic synthetic material or a foil folded previously in longitudinal direction, comprising a feed de vice for feeding a predetermined length of foil corresponding to the desired width of the bag intermittently to a welding device which simultaneously severs the foil and welds the foil along the adjacent severed edges with a heated severing-welding element, means for moving and guiding said severing and welding element for movement from a rest position through said foil during which time it severs and welds said severed edges of said foil and for subsequently moving said element back to said rest position, and means positioned adjacent at least one side of said welding element for lifting the welded edge lying on that side from the area of return movement of said severing-welding element.

9. Machine according to claim 8, wherein said welded edge lifting means is on the side adjacent said bag take-up and ejection device.

10. Machine according to claim 8, wherein said welded edge lifting means is provided on both sides of said severing-welding element.

11. Machine according to claim 8, wherein said lifting means comprises a narrow flap positioned below said foil and transversely across its width and controlled to pivot upwardly upon upward movement of said severing-welding element.

12. Machine according to claim 11, wherein said flap is operated by a driver hook attached to said welding device, said hook pivots said flap upwardly upon upward movement of said severing-welding element and upon downward movement of said severing-welding element resiliently engages under the free edge of said flap,

13. Machine according to claim 11, wherein said flap 1s operated by a rocking lever connected to an electromagnetic relay controlled from a main circuit control.

14. Machine according to claim 8, wherein said lifting means comprises a pair of brackets acting against each other from above and below and against the welded edge area of said foil and lifting the welded edge from the area of movement of the severing-welding element, one of said brackets being resiliently and slidably arranged and guided for movement relative to said foil on guide and carrier arms for the severing-Welding element, the other of said brackets being movable relative to said foil and operated by a suitably driven cam mechanism.

15. Machine according to claim 14, wherein said upper bracket is spaced a longitudinal distance from the severing-welding element on one side of said foil and said lower bracket is positioned to be moved within said space from the other side of said foil.

16. Machine according to claim 8, wherein a pair of girders clamp the foil at the feed side of said severingwelding element and a pair of smoothing strips tension the foil without clamping it on the exit side of said separating element.

17. Machine according to claim 16, wherein said smoothing strips comprise a pair of brackets which lift a welded edge from the area of movement of said severingwelding element.

18. A machine for forming bags according to claim 1, wherein said means for controlling actuation of said bag feed and ejection means is operated by said roller drive mechanism.

19. A machine for forming bags according to claim 1, wherein said feed rollers drive mechanism is adjustable to determine the length of each said section and thereby the width of the formed bag.

20. A machine for forming bags according to claim 1, wherein said roller drive mechanism comprises power means connected to intermittently rotate one of said rollers, said one roller is connected to positively drive the other roller, and said stop mechanism is operatively effective upon said other roller.

21. A machine for forming bags according to claim 1, wherein a first motor is connected to drive both said feed rollers and said severing and welding means, and a second motor is connected to drive said bag feed and ejection means, and a control circuit is provided to synchronize actuation of said second motor with said first motor.

22. A machine for forming bags according to claim 1, wherein said feed roller drive mechanism comprises an electric motor drive connected to a rotatable control shaft, means is provided connecting said control shaft to intermittently rotate said rollers, an electric motor is drive connected to said bag feed and ejection means, and means is provided on said control shaft for timed actuation of switches in a main circuit containing both of said motors.

23. A machine for forming bags according to claim 22 wherein said severing and welding means comprising an electrically heated element and said main circuit contains timing means that delays operation of said motors until said element has reached foil fusing temperature.

24. A machine for forming bags according to claim 23, whereincam means is provided for periodically operating said severing and welding means and a drive connection is provided between said control shaft and said cam means.

25. A machine for forming bags according to claim 24, wherein means actuated by said cam means is provided for displacing at least one of said welded foil edges out of the path of the severing and welding means upon conclusion of a severing and welding operation.

26. Bag forming machine according to claim 1, wherein means is provided for maintaining the foil under tension between the feed rollers and said bag feed and ejection means whereby to accurately determine the location of the severing and welding operation.

27. Bag forming machine according to claim 1, wherein said bag feed and ejection means comprises a plurality of 14 laterally spaced lower conveying belts and a corresponding plurality of aligned upper pressing belts, said belts having common driving means.

28. Bag forming machine according to claim 27, wherein the conveyor and pressing belts are controlled for intermittent operation so that they will move only during a bag ejection process following welding.

29. Bag sealing machine according to claim 27, Wherein at least the outside conveyor belt running at the open side of the bag and the pressing belt aligned with it are set back against the opening edge of the bag.

30. Bag forming machine according to claim 27 wherein said belts are non-metallic plastic, and said feed rollers are rubber covered.

31. Bag forming machine according to claim 1, wherein said roller drive mechanism and said foil severing and welding means are driven from a common first motor, and said bag feed and ejection means is driven from a second motor.

32. Bag forming machine as defined in claim 1 wherein said bag feed and ejection means moves said formed bags at a higher linear speed than said web is advanced by said feed rollers.

33. Bag forming machine according to claim 1, wherei in said severing and welding means comprises a vertically reciprocable electrically heated element, cam means is provided to lift said element against the action of biasing spring means to a rest position above the path of movement of the foil and then release the element to descend for the severing and welding process under the action of said spring means.

References Cited UNITED STATES PATENTS 2,683,401 7/1954 Smith 156-583 2,749,817 6/1956 Piazze et al. 156-583 2,947,345 8/1960 Schjeldahl 156-361 3,053,723 9/1962 Plach et al. 156-511 3,185,609 5/1965 Merithew et al. 156-583 3,192,095 6/1965 Doyen et al. 156-583 3,330,716 7/1967 Zelnick 156-499 3,481,376 12/1969 Keller 156-583 ROBERT F. STAHL, Primary Examiner US Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OPT/CORRECTION Patent No. 3, 586, 577 Dated June 22, 1971 Inventor(s) ITALO DELLA BELLA It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 5, line 2, change "thime" to --time-.

Column 5, line 7, change "13" to -l--.

Column 5, line 74, before "effective" insert --device 6 is maintained. The drive of the feed device 4 becomes-.

Column 6, line 15, change "in" to -is--.

Column 6, line 33, change "0" to --to-- Claim 2, column 11, lines 55 and 56, "casing" should be -carrying.

Claim 24, column 13, line 32, change "23" to --22.

Signed and sealed this 28th day of December 1971 (SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Acting Commissioner of Patents FORM P0-1o50 (10-69) USCOMM-DC G037G-F'69 9 U S GOVERNMENY PRINTING OFFICE: I969 0-365-334