US3161002A

US3161002A - Packaging machines

Info

Publication number: US3161002A
Application number: US162005A
Authority: US
Inventors: Duns John
Original assignee: Smith and Nephew Plastics Ltd
Current assignee: Smith and Nephew Extruded Films Ltd
Priority date: 1961-12-26
Filing date: 1961-12-26
Publication date: 1964-12-15
Anticipated expiration: 1981-12-15

Description

Dec. 15, 1964 J. DUNS PACKAGING MACHINES Filed Dec. 26. 1961 5 Sheets-Sheet 1 Dec. 15, 1964 u s 3,161,002

PACKAGING MACHINES Filed Dec. 26. 1961 s Sheets-Sheet 2 Dec. 15, 1964 Filed Dec. 26. 1961 J. DUNS 3,161,002

PACKAGING MACHINES 3 Sheets-Sheet 3 United States Patent 3,161,002 lAiIKAGING MAQHEIE John Duns, Weiwyn Garden Qity, England, assignor to Smith & Nephew Plastics Limited, Hull, England, a hritish company Filed Dec. 26, 196i, Ser. No. 162395 8 Qlaims. (Cl. Sit-#186) This invention relates to packaging machines of the kind which utilise for the packaging material a roll of thin plastic film such, for example, as polyethylene, formed as a flattened tube (which in some cases may have side gussets), and which material from the roll in the machine is adapted to be drawn oif by hand and its open end passed over the goods to be packed so that the portion of the tube adjacent the end encloses said goods, said portion still enclosing the goods being cut off from the tube immediately after the two thicknesses are heat-sealed together and which will be close to the line of the said cut, and has for its object to provide such machines of simple and efiicient form adapted to have mounted therein rolls of various widths of the plastic material, and to be utilised for the packaging of a wide variety of goods.

In accordance with a primary feature of the present invention, such a packaging machine comprises a pair of gripping devices which, at the end of the sealing and cutting operations, hold the flattened tubular plastic gripped between them in a position slightly spaced from the end from which the bag has just been cut, and which gripping devices, when the cutting and heat-sealing members are moved from their operative to their inoperative positions, are caused to move and draw off a preliminary,

portion of the material from the roll so as to feed the cut end of the material through the sealing and cutting positions to a position where it can readily be taken hold of by the hands of the operator, for the remainder of the full amount of the material (which will vary with the particular goods being packed) to be drawn off, by the hands of the operator, and then passed around to enclose said goods, ready for another heat-sealing and cutting operation.

Another feature of the present invention consists in so arranging the machine that the material from the roll passes to and over a horizontal platform, from the front of which the said material is led to the heat-sealing and cutting position.

In preferred forms the two shorter sides of this platform are mounted for horizontal movement in the side frames or the like of themachine, and the platform carries the pair of gripping devices hereinbefore referred to.

After the material has been pulled forwards by the hands of the operator sufficiently to fully enclose the goods and is held enwrapped around the goods, however, when the machine is operated to effect the heat-sealing and cutting-off of a bag, as a first step of the operation the platform is moved towards the rear, with the gripping devices out of gripping action with the material and moving freely in relation to the material, and towards the end of this time the heat-sealing and cutting are effected as hereinafter explained. After this the movement of the platform is automatically reversed and during this reversed and forward movement the preliminary feeding of the material is effected as previously set forth.

The movements of the platform, according to a still further feature of the invention, are imparted, through suitable mechanism, to the co-operating devices which effect the heat sealing, so that they are brought into and out of operation in timed relation with the movements of the platform. I

The co-operating devices for effecting the heat sealing which comprise the electrical heater and the pad on which the heater presses, according to an important feature of 3, i h l ,WZ hatented Dec. 1 5, 1 96d ice the present invention consists in making'the heater and pad as two separate units extending from side to side of the machine and mutually moving them together to grip the material between them for the heat sealing operation, or mutually moving them apart to free the material after such operation. For this purpose the mechanism is such that, especially when operated from the movable platform, the heater and pad work in more or less vertical guideways in the side frames of the machine or the like, so as to be brought together or moved apart in the manner of a pair of jaws.

The knife for cutting the material immediately after the heat-sealing is preferably of the pointed saw-tooth type, operates in guideways and has co-operating therewith a grooved transversely extending presser bar which may be of metal. When the actual cutting takes place the material is held taut against the presser so that the portion extending over the groove is first punctured by the points of the teeth and then severed; the groove, of course, has such depth that the knife edge can be accommodated therein for the instant after the cutting and before the return action of the knife.

According to a still further feature of the invention, any suitable lost-motion device may be employed for vp'ostponing the operation of the knife until after the heatsealing.

The operating means in machines according to the invention may be wholly manual, or power (hydraulic, pneumatic or electric) brought into action manually. When manual, a lever action (against spring return) effects the heat sealing, cutting and preliminary feed of the material. This lever action in most cases is a pedal or treadle mechanism, to leave the hands of the operator free to manipulate the tubular plastic material;

. in order that the invention may be better understood, it will now be described with reference to the accompanying somewhat diagrammatic drawings which are given by way of example only, and in which:

FIG. 1 is a front elevation of one embodiment of a machine made in accordance with the invention.

FIG. 2 is a side elevation of FIG. 1.

FIG. 3 is a plan of FIG. 1.

FIG. 4 is a diagrammatic perspective view, to illustrate the action of the machine shown in FIGS. 1 to 3.

FIG. 5 is a cross-section of the material used in the machine.

MG. 6 is a diagrammatic elevation to illustrate the operation of the means-for gripping the material.

FIG. 7 is a sectional side elevatiorrlwith parts removed for clearness), to a larger scale, of the upper portion of the machine shown in FIG. 1, with the parts in the rest position.

FIG. 8 is a similar view to FIG. 7 but with the parts in the position mid-way through the operating stroke, that is, just after the sealing and cutting and ready for the automatic return of the parts to the position shown in FIG. 7.

FIG. 9 is a fragmentary view, partly in section, to illustrate the mounting and operation of the table, and with the parts in the position shown in FIG. 8.

FIG. 10 is a front elevation (with parts removed for clearness) of a side of the upper part of the machine such as shown in FIG. 7, seen from the front of the machine, and

FIG. 11 is a similar view to FIG. 10 with parts in section and as seen from the direction of the rear of the machine.

in FIGS. 1 to 6 the machine is formed as a cabinet made from an interior lower framework (not shown) bounded by outer panels of sheet metal. The latter, at the lower part, comprise a front panel 12 and side panels one of which, 13, is shown in FIG. 2; the rear panel (not 3 shown) is made readily removable. The upper portion of the machine comprises two similar but handed side frames one of which, 14, is shown in FIGS. 7 to 11 to be hereafter referred to; these are interconnected and fixed to the lower framework. The panelling for the upper part of the machine comprises a ventilated front 15, with a wide horizontal slot 16 for the outlet of the-material. It also has a top, the portion 17 of which is ventilated and the portion 18 formed as a cover which is hinged at 19 to the portion 17.

As represented diagrammatically in FIGS. 1, 2 and 3, but chiefly in FIG. 2, the lower framework has supporting spindles for

rolls

20 and 21 of the material, which may be gusseted as shown in FIG. 5. The width of the material on one roll 20 may be different from that on the other roll 21. The material 22 from either ro-ll can be passed around a distancing bar 23 connecting the upper side frames 14. These upper side frames 14 (as hereafter described) support a reciprocating sliding table 24, shown in its forward position in FIG. 2, and this carries the spindles of two

gripping rollers

25 and 26 so that the material passes from the cross bar 23 on to the upper surface of the table 24, then between the

rollers

25 and 26, and then out through the opening 16 at the front of the machine. As shown in FIG. 2, in the forward position of the table 24, which is the rest position, the material 22 has an end 27 at the front which projects ready to be gripped and pulled outwardly by the hands of the operator. This allows him to draw off a sufficient amount to pull over and enclose the next goods it is desired to enwrap, and this before the machine is operated.

The table 24 is moved by a pedal 28 at the front of the machine. This is fixed on a cross spindle 29 and has an arm 30 connected by a push bar 31 to one end of a lever 32 fixed to a cross shaft 33 mounted in bearings and extending between the two side frames 14. Adjacent each side frame 14 on the interior of the machine, the shaft 33 has secured thereto a lever 34 having a shaped slot 35 therein which engages a projecting roller 36 at the side of the table 24. Although only one lever 34 is to be seen in FIG. 2, it will be appreciated that there are two such levers, one at each side of the table 24, which table has a roller 36 at each side.

With the parts in the position shown in FIG. 2, when the pedal 28 is depressed the slot 35 is so shaped that at first the table 24 is brought to its rear position, where it stops, and then the slot 35 moves over its engaged roller 36 by lost motion. When the pedal is released, the table 24 moves back automatically to its forward position under the action of two tension springs, one of which, 37, appears in FIG. 2. One end of a spring 37 engages an arm 38 of the associated lever 34, and the other a fixed pin 39 on the corresponding side frame 14.

The table has two other projecting rollers at its two sides; one of these, 40, appears in FIG. 2 and engages in a slot in one arm of a bell-crank lever 41 mounted to turn on a bearing on the inside of a side frame 14. The roller 40 also engages in a slot in an arm of another bell-crank lever 42 mounted to turn in another bearing in the inside of the side frame 14. The upper bell-crank lever 41 controls the up and down movements of an electric sealing heater 43 which extends from side to side of the machine and is carried by a frame which works in guides in the side frames 14. The other bell-crank lever 42 controls the cooperating down and up movements of a presser pad 44 which co-operates with the sealing heater 43.

The arrangement is such that as the table 24 moves rearwardly, without moving the material rearwardly (by the means to be described hereafter) the heater 43 and pad 44 are moved each towards the other, to grip between them the material 22 which lies in this position, to effect the sealing operation.

The cutting of the material takes place immediately after the sealing, by the continued depression of the pedal, and will be hereafter particularly described.

As soon as the cutting is effected, the pedal is released so that the two springs 37 (one at each side of the machine) effects the return stroke and cause the table to be pushed to the forward position, which automatically raises the heater 43 and lowers the pad 44 and again brings the parts to the rest position shown in FIG. 2.

The manner in which the

gripping rollers

25 and 26 operate will be seen from FIG. 6. As to be hereafter described, the lower roller 26 is carried by a spindle on the underside of the table and passes through a gap in the table to contact the upper roller 25 which is carried between two arms pivoted in bearings on the upper side of the table and kept pressed downwardly with a slight pressure by spring means. Each roller is carried by a fixed spindle with a fixed ratchet wheel or its equivalent thereon, and each roller has slipping pawl means engaging the ratchet. Thus, the upper fixed spindle 45 has a ratchet wheel 46 secured thereto, and the roller 25, which freely rotates on the fixed spindle 45, has a slipping pawl 47. As a consequence, when the material 22 is pulled forwardly in the direction of the arrow 48, this is permitted by the upper roller rotating in the direction of the arrow 49, the pawl 47 slipping over the teeth of the ratchet wheel 45. Similarly, when the fixed spindle 45 is moved rearwardly in the direction of the arrow 50, the roller 25 can turn in the direction of the arrow 49, that is, move over the surface of the material 22.

The action is similar for the lower roller 26 which has a fixed spindle 51 and a fixed ratchet wheel 52, the roller itself being free to rotate on the spindle 51 and having a slipping pawl 53. Here again, where the material is moved in the direction of the arrow 48 the roller is rotated in the direction of the arrow 54, and when the fixed spindle 51 is moved in the direction of the arrow 55 the roller also rotates in the direction of the arrow 54. V In other words, if the table 24 is in the forward position, then it is possible to pull upon the end 27 of the material and pull out as much material as desired, this action being permitted by the

rollers

25 and 26 as they both are free to rotate on the surface of the material 22. Similarly, when the parts are in the position shown in FIG. 2 and it is desired to move the table rearwardly, this can be done without moving the material rearwardly as the rollers are free to turn whilst pressed on to the surfaces of the material when the table moves rearwardly.

However, when the table is in the rearmost position, the material is still gripped between the

rollers

25 and 26, and upon the forward movement of the table, that is to say, for the present purpose the

spindles

45 and 51 in the forward direction, that is, in the direction of the arrows 56, then the pawl and ratchet engagements do not permit the

rollers

25 and 26 to rotate on their spindles, but only to continue gripping the material between them, so that this forward movement of the table causes the rollers to pull the material from the

main roller

20 or 21, as the case may be, in order that a length thereof is fed forward on every return movement of the table 24 from the rear to the front, to bring said material to the exterior and constitute the end such as 27 ready to be pulled upon by the operator to enwrap around the goods to be packaged and before the next operation of the machine.

Any suitable table or like device may be provided to assist in packaging the goods. That shown in FIGS. 1 to 4 comprises two telescopic arms spaced apart one above the other. Each of these arms comprises a tube 57, one end of which is fixed to the lower framework of the machine, and a rod 58 telescoping therein. The outer ends of the rods 58 are fixed to a vertically bored bearing 59 in which a. vertical post 60 is adjustably positioned. The adjustment is effected by spaced horizontal bores 61 across the rod, any one of which is adapted to receive a pin 62 which normally rests on the top of the omitted for the sake of clearness.

bearing 59, which may be diametrically grooved for the purpose. The upper end of the post has a fixed head 63 from which project laterally two

horizontal arms

64 and 65 one spaced above the other. The upper, 64, forms a fixed spindle for the spaced-apart bearings 66 on the underside of a plate 67 forming a table. These bearings at their lower ends are formed as stops 68 which abut against the lower arm 65 to hold the table 67' with its upper surface in a horizontal plane. However, the table 67 can be turned up about the axis of the upper arm 64 in the direction of the arrow 69 (FIG. 2), and the table 67, with the bearings 66 and

arms

64 and 65, can be turned about the vertical axis of the rod 6% in the direction of the arrow 70 (FIG. 3).

It will be appreciated that the table fitted is of a size and has dimensions to suit the goods to be packaged and, further, that its normal position is adjustably set to this end. Then, for enwrapping the particular goods, such as the goods 71 (FIG. 4), which may be a folded ciderdown, folded blanket, or such similar goods, these goods 71 are placed on the table 67 and the end 27 of the material pulled out so that (see FIG. 6) the lower part passes beneath the table 67 and the sides and upper part come around the goods. The amount of the material 22 pulled out must come well beyond the outer end of the goods,

and then the pedal 28 is depressed. This efifects the heat sealing-together of the thicknesses of the material at the dotted line 72. Immediately, by further depression of the pedal, the material is cut along the lines 73.

The bag or envelope has now been made and separated from the material 22 in the machine, so that the table 67 can be turned in the direction of either one or both of the

arrows

69, 70 for the operator to disengage the goods and their envelope from the table and to finish the closingin of the open end of the envelope, which may be by heatsealing as hereafter explained.

In FIGS. 7 to 10, the upper portion of the machine is shown to a larger scale, somewhat diagrammatically, with the inclusion of essential parts but other parts being More particularly, only one side frame 14 is shown with the parts operating therewith, but it is only necessary to show this as the machine is generally symmetrical about the centre line XX, FIG. 10.

As will be seen from the plan FIG. 9, the table 24 formed from a casting, at the side is slotted at 74, and across this slot theiroller 36 is mounted so that the upper end of the lever 34 can pass upwards through the slot for its shaped slot 35, which engages the roller 36, to impart the reciprocating movements to the table. The shaping of the slott35 includes a lower portionwhich is radial and actually effects the movements of the table 24 and an upper portion which is circumferential about the axis of the shaft 33; this permits the necessary lost motion.

The upper side of the table 24 has a bearing 75 for a two-armed lever 76, the lower arm having fixedthereto one end of the spindle 45 for the upper gripping roller 25,a similar lever mounted at the other side of the table having aflixed thereto the other end of the spindle 45. The other arm of the lever 76 is connected to its equivalent member on the other side of the table by a cross bar 77. The pivotal mounting in each of the bearings 76 is spring-stressed (not shown) so that the roller 25 normally is kept pressed towards the table 24, but, for setting up the machine, by pressing down on the cross bar 77 the end of the material 22 can be passed between the

rollers

25 and 26; the latter is mounted on its fixed spindle 51 which is secured'in bearings on the underside of the table, and the roller projects upwardly through a slot 7 8 in the table, to cooperate with the upper roller 25.

As shown particularly in FIG. 9, the outer side extremity of the table 24 has pairs of downwardly extendspaced-apart rollers. One of these is the roller 40 which is atthe front, and the other at therear is an additional roller 79. These operate in a horizontal guiding slot in the side frame 14. The guideways 8b in each side I 81 is for the two spaced-apart rollers 83 and 84- of a yoke $5 formed integrally with a cross frame member 86, the other end of which is integral with the corresponding yoke member of the other side frame 14. The portion of the lower roller 84 adjacent the inner surface of the frame 14- is engaged by the more or less horizontally projecting arnr of the bell-crank lever 41, so that when the bell-crank levers 41 are operated by the table 24, the yokes 35 and frame 86 are caused to move.

Similarly, the lower vertical slot 82 is for the two spaced-apart

rollers

87 and 88 of a yoke 89 formed integrally with a cross frame member 90, the other end of which is integral with the corresponding yoke member of the other side frame 14. The portion of the upper roller 87 adjacent the inner surface of the side frame E4, is engaged by the more or less horizontal arm of the bell-crank lever 42, so that when the bell-crank levers 42 are operated by the table 24 the yoke 89 and frame 90 are caused to move.

The upper cross frame 86 has downwardly projecting brackets 91 by which the electrical resistance heater 43 for effecting the sealing is adjustably secured in position. This heater 43 is only generally indicated in the drawings (particularly FIG. 7) but is extends across the machine at the front just behind the outer front panelling 15 and has the usual lower sealing blade portion 92 which is parallel with the surface of the table 24. Moreover, the heater is in an electrical circuit in the machine (not shown) adapted to be connected to and disconnected from an exterior source of supply, in the usual manner. Further, and again in any usual manner, the circuit may include any usual tell-tale light and thermostatic control device. 7

The lower cross frame 90 adjustably carries the presser pad 44 by screws 93. The adjustments of the heat sealer 43 and presser pad 44- are such that they mutually move towards each other when the table 24 moves rearwardly from the rest position shown in FIG. 7, so that as the front edge of the table (moving rearwardly) frees itself from the material 22- (which is not moving) the presser pad rises to support the under surface of this freed part of the material, on its upper surface, and simultaneously the heat sealing blade 92 is pressed on to the upper surface of the material. The scaling is effected during the lost-motion movement of the circumferential part of the slot 35 overthe roller 36 of the table 24, which latter is now not moving in its rear position.

During this lost-motion period, which takes place during the last portion of the pressing-down action upon the pedal 28, the cutting is effected along the line 73 (FIG. 4). For this purpose the presser pad is divided vertically from end to end, and in the space between the divisions is arranged a vertical cutting knife blade 94 with an upper toothed cutting edge. The lower edge of the blade 94 is secured to two spaced-apart vertical sliding posts 95, one of which is seen in FIGS. 10 and 11, another being in a symmetrical position towards the other side of the machine. The post 95 passes through a bearing% in the cross frame 96, and the portion below the bearing 96 has a helical compression spring 97 thereon (omitted in FIG. 8 for the sake of clearness) which abuts a pin at the lower end. The arrangement is such that in the rest position of the machine (FIGS. 7 and 10) the knife 94 is kept in its lowermost position in which the upper cutting edge is below the upper surface of the presser pad 44. It continues in this position in relation to the surface of the presser pad 44, even when the latter is raised to its upper position by the bell-crank levers 42, and as long as the radial parts of the slots 35 of the levers 34 are operating upon the rollers 36 of the table 24.

When the circumferential parts of the slots 35, however start to move over the rollers 36, then the shaft 33 is still being turned from the pedal 28. This shaft 33 has secured thereto in the appropriate positions, to operate the spring-pressed sliding posts, two lifting levers, one 98 of which only appears in FIGS. 7, 8 and 11. The end of the lever 98 makes contact with the lower end of its co-operating post 95 as the heat sealing operation commences. Then immediately the continued pressure on the pedal 28 causes the levers 98 to press the posts 95 upwardly through the bearings 96 to raise the knife 94 and cause it to move upwards through the presser pad 44. This movement causes the cutting edge to cut through the material 22 held gripped between the heated sealer 91/92 and the presser pad 44, and then to rise a slight distance and into the longitudinally extending division of a supplementary presser pad 99, which is brought into action just before the cutting operation and out of action immediately the cutting has been effected. The upward movement of the lever 98 is limited by an adjustable stop 100 carried by screw means from the cross frame 90.

The supplementary presser pad 99 extends across the machine and is carried by bent lever arms 101 secured to a shaft 102 mounted in bearing brackets integral with the upper cross frame 96. At the ends this shaft 102 has other levers 103 secured thereto, the outer ends of which are pivoted to links one of which 104 appears in FIGS. 7, 8 and 11; the link 104 is pivoted in a bearing lug at the 'upper end of the side frame 14. The shaft 102 is encircled by a number of torsion springs 105 the ends of which are so anchored or secured that the action of the springs always tends to bring the presser pad 99 into the operative position, which is immediately adjacent the heater 43. On the other hand, when the parts are in the rest position (FIG. 7) the links 104 cause the presser pad 99 to be held up and away from the heater, thus minimising any deterioration of the presser pad due to the heat.

When it is desired also to seal the remaining open side of the bag with the goods enclosed inside, that is to say, to seal the open end of the tube which was first drawn over the goods, then in the first place care must be taken that sufficient length of unoccupied tube is left at this end. For the supplementary purposes, an additional heat-sealing component is provided on the machine which is suitably disposed at one or either side, or other position, so that this open end of the bag, in a flattened condition, is passed thereinto. That is to say, it is passed between a heater proper and a co-operating presser pad.

These are brought together to effect the necessary sealing by levers, power or other means, as will be readily appreciated, to effect the purpose of sealing this last open end of the bag.

In some cases the heat sealing means of the machine may be employed for the purpose. That is to say, the end 27 of the material projecting from the machine is not drawn out, but the remaining open side, in flattened condition, is passed into the opening 16 in the front panel 15, when the machine is in the rest position, so that this flattened open side is brought to the sealing and cutting zone. The pedal 28 is then operated, which will effect the necessary sealing and cutting and bring a fresh end portion 27 into position.

Although as shown the machine can accommodate two rolls of material of different widths, either of which can be used at choice, in some cases both rolls may have their ends guided to the table 24 and then be held vertically apart by a horizontal dividing pivoting tray or the like located over the table, leaving either of the two ends to be gripped between the rollers at choice. This may be done from the front of the machine by suitably forming and enlarging the opening 16 and having the gripping rollers moved and held apart at the end of their forward feeding movement.

If necessary braking means may be provided in connection with the roll of material, or in the length of the material, between the roll and the table, to hold the material from movement, except when pulled upon for the preliminary feed, or when drawn off by hand, such braking means also limiting the amount drawn off to that caused by these movements, without over-running.

The invention is not limited to the precise forms or details of construction herein described, as these may be varied to suit particular requirements.

What I claim is:

1. A packaging machine, comprising spaced parallel side frames, horizontal guideways in said frames arranged in opposed relation, a horizontal table supported on said guides for forward and rearward horizontal reciprocating movement, a supply roll in said machine for feeding a flattened tubular plastic film to said table, a work station in front of said machine toward which said table is adapted to feed said tubular film, means for reciprocating the table toward and away from said work station, a pair of gripping rollers on said table between which the tubular plastic film is positioned for holding said film in a rest position adjacent the work station and for drawing off the film from the supply roll during movement of the table toward said work station and feeding the same toward said Work station so that its front edge is presented thereto in a filling position, a free-wheel device associated with each gripping roller to permit the rollers to rotate when the desired length of material at the filling position is manually pulled by its front edge toward said work station, and when said rollers move rearwardly from the work station but which hold the rollers from rotation and in gripping relation with the tubular plastic film upon the return movement of the table to the work station position, said side frames being provided with vertical guideways adjacent the work station and positioned between the front of the table when the same is in the work station position, heat sealing means extending between the upper portion of said vertical guideways and movable between said guideways, a presser pad adapted to cooperate with said sealing means slidably guided in the lower portion of said vertical guideways, mechanical connecting means between the heat sealing means and said table and between the presser pad and the table operable such that when the table is in the work station position at the front of the machine the heat sealing means and presser pad will be held in spaced apart relation, but will be moved together to hold the portion of the tubular film which has been moved to the front of the table and to the filling position when the table is moved to the rear to effectively heat seal the tubular material, a knife blade having an upper cutting edge carried by the presser pad, and operating means to move the blade upwardly and sever the tubular film while it is held between the heat sealing means and the presser pad, said blade being movable to a cutting position while the table is in a rearmost position, and a support located at the work station to receive the outer open end of the tubular film after the same has been pulled by hand from the machine to receive the package prior to the actuation of said operating means to move the table from the work station position rearwardly which automatically actuates the heat sealing cutting means, and thereby free the package goods in the front severed part of the tubular film with one end of said tubular film heat sealed.

2. A packaging machine as set forth in claim 1 in which the means for operating the machine is operatively connected to the knife blade through a lost motion means which becomes operative immediately after heat sealing by the heat sealing means and the presser pad.

3. A packaging machine as set forth in claim 1 in which the lower gripping roller is positioned so that its periphery projects into an elongated slot in the table to cooperate with the upper roller and frictionally engage the plastic film which passes over and in contact with the table surface.

4. A packaging machine as set forth in claim 1 in which bell-crank levers are pivoted to the frame sides and are operatively connected to the sides of the movable table, and guide rollers on said heat sealing means and presser pad for guiding the same into said vertical guideways.

5. A packaging machine as claimed in claim 4, in which a cross frame member carrying the heat-sealing means interconnects two yokes, each yoke working over the vertical end of a side frame, and in which each yoke has two spaced-apart guide rollers Working in a vertical slot of a side frame, the lower of which rollers is operatively connected to the upper bell-crank lever, and another cross frame member carrying the presser pad and knife interconnecting two other yokes, each yoke working over the vertical end of a side frame, each said yoke having two spaced-apart guide rollers working in another vertical slot of the side frame, the upper of which rollers 'is operatively connected to the lower bell-crank lever.

6. A packaging machine as claimed in claim 1, in which the movable table is reciprocated by levers located at the two parallel edges thereof, which levers have slots, rollers at said edges, said levers having spring return means and being on a cross shaft operated from a pedal, the shaped slots permitting said levers and the cross shaft to continue to be moved by the pedal after the table has tical movements of the knife blade with its upper cutting edge, said blade being carried by spring-controlled posts sliding in bearings on the cross frame and the lower ends of which are adapted to be abutted by the lever means on a cross shaft, to raise the knife in relation to the presser pad and cut the material while the same is gripped between the heat-sealing means and the presser pad and to the rear of said heat sealing grip.

8. A packaging machine as claimed in claim 7, in i which a supplementary presser pad is provided to cooperate with the cutting blade, said supplementary presser pad being divided to receive the upper edge of said blade after it has severed the material, and being carried by spring-biased levers from a cross shaft mounted in bearings integral with the cross frame supporting the heatsealing means and guided to work in vertical slots of the side frames, and which cross shaft is connected by lever and link means to the side frames, to hold the supplementary presser pad in operative position for the cutting action and to swing and hold it out of contact from the heat-sealing means in the rest position.

References Cited in the file of this patent UNITED STATES PATENTS Wang Aug. 19, 1958