US 3915787 A
A bag machine attachment by which opposite edges of a web of heat sealable material are hemmed or capped prior to longitudinal folding and feeding the web to a conventional bag machine. The attachment includes an upstanding frame to support supply rolls of web material folding and heat sealing components as well as adjustment and control means by which a wide range of bag mouth edge structures may be formed without modification to an existing bag forming machine.
Claims available in
Description (OCR text may contain errors)
United States Patent [1 1 Vetter Oct. 28, 1975 1 1 EDGE CAPPING AND FOLDING ATTACHMENT FOR BAG MACHINES  Inventor: Erich Vetter, Huntington, NY.
 Assignee: Uniflex, Inc., Westbury, NY.
 Filed: Apr. 16, 1974 21 Appl. No.: 461,276
 US. Cl. 156/359; 93/1 P; 93/13',
93/35 R; 156/461; 156/467  Int. Cl. B32B 31/00  Field of Search 156/202, 216, 461, 467,
156/463, 359; 93/8 N, 8 WK, 35 R, 35 H, 82 R, 35 DS, 1 E, 1 F, 13
 References Cited UNITED STATES PATENTS 2,237,537 4/1941 Yeates et a1, 156/461 X 3,058,402 10/1962 Kugler 93/8 WA 3,381,592 5/1968 Raue] 93/8 WA 3,431,561 3/1969 I-Iommel et al..... 93/8 WA X 3,458,965 8/1969 Shuffrey et a1. 156/461 X 3,488,244 1/1970 Lepisto 156/359 3,749,631 7/1973 Batchelder et a1 156/359 UX 3,779,139 12/1973 White 93/35 DS X FOREIGN PATENTS OR APPLICATIONS 106,320 5/1917 United Kingdom 156/461 Primary Examiner-Doug1as J. Drummond Assistant ExaminerDavid A. Simmons Attorney, Agent, or Firm-Lane, Aitken, Dunner & Ziems [5 7] ABSTRACT A bag machine attachment by which opposite edges of a web of heat sealable material are hemmed or capped prior to longitudinal folding and feeding the web to a conventional bag machine. The attachment includes an upstanding frame to support supply rolls of web material folding and heat sealing components as well as adjustment and control means by which a wide range of bag mouth edge structures may be formed without modification to an existing bag forming machine.
12 Claims, 12 Drawing Figures Sheet 1 of 5 3,915,787
US. Patent 0052s, 1975 U.S. Patent Oct.28, 1975 Sheet2 of5 3,915,787
Im m? Sheet 4 0f 5 3,915,787
U.S. Patent Oct. 28, 1975 wrl US. Patent Oct. 28, 1975 SheetS 0f5 3,915,787
EDGE CAPPING AND FOLDING ATTACHMENT FOR BAG MACHINES BACKGROUND OF THE INVENTION This invention relates to machinery for making bags from webs of heat sealable material and more particularly, it concerns an edge capping and folding attachment for such machinery and which is adaptable to the formation of numerous specific bag designs without modification to the existing bag forming machine with which the attachment is used. f
The manufacture of bags from heat sealable sheet material is conventionally carried out by longitudinally folding an essentially continuous supply of a preprinted heat sealable web to provide what will ultimately be the front and back panels joined at a bottom fold line in each bag formed. The folded continuous web is advanced longitudinally in a bag making machine in increments corresponding to the width of each bag to be formed past a series of forming stations at which some operation incident to the formation of the completed bag is performed; for example, the securement of carrying handles, punching of hand hold openings and the like. Near the end of folded web travel incrementally in this manner, the superimposed layers of the longitudinally folded web are simultaneously heat sealed and severed tranversely to form the side seams or edges of each bag and also to separate each formed bag from the continuous web.
Machines to form bags in this manner are commercially available and typically include a relatively heavy elongated bed or frame capable of supporting forming components at the respective forming stations spaced longitudinally by a distance corresponding to the width of the widest bag to be formed. The bed additionally supports various guide rollers for the longitudinally advanced web, drive capstans and compensator roll assemblies and control systems by which printed indicia on the web can be indexed with the forming station operations.
Although such bag forming machines offer some measure of versatility with respect to the specific operation to be performed at any one of the successive stations along its length merely by substituting operating components at the respective stations, the number of stations is limited by the fixed length of the machine bed assuming that extensive modification of the basic machine is to be avoided. The manufacture of bags provided with additional layers of web material in the form of a hem or cap along opposite sides of the ultimate bag opening, for example, presents problems in this latter respect, particularly where such bags are provided with other formations such as carrying handles, or carrying handle cut-outs or the like. For example, the securement of such a hem or capping to the edges of the web material in the bag making machine requires a reciprocating heat sealing assembly which will occupy longitudinal space in the machine at least equal the entire width of the bag to be sealed and must be changed for each different width of bag to be formed. In addition, because two superimposed but discrete longitudinal heat welds or seals must be formed to secure hems or caps to the now superposed front and back panels, some shielding means must be provided between the dividing layers of the heat sealable web in the formation of a hem or capping of this type. Also the length of material travel required to achieve a fold in the bag making machine will occupy at least the space of a complete operative forming station.
In the past, these problems have caused bag manufacturers significant expense either for the purchase of specialized bag making machines to accommodate relatively narrow ranges of different bag structures, to make extensivemodifications in a basic bag making machine, to make double runs of the web through the bag making machine or combinations of these costly and time consuming solutions. It is apparent therefore that there is considerable need in the art for a relatively inexpensive solution to the problem of adapting existing bag forming machines to a wider range of bag styles and structural designs.
SUMMARY THE PRESENT INVENTION In accordance with the present invention, a highly effective and relatively inexpensive attachment is provided for conventional bag forming machines of the type mentioned and by which any one of numerous bag mouth edge structures may be manufactured without more than routine modification of the bag forming machine. Essentially, the attachment is constituted by a frame supported structure with appropriate guide rollers to form a loop-like series of flight portions in the unfolded web passing between a web supply roll or rolls and the longitudinal folding anvil conventionally employed in the delivery of the web to the bag forming machine. As the web is continually advanced through the loop-like flight portions, an additional capping layer of heat sealable material is applied to one or both of the opposite edges of the web and immediately heat sealed in a successive flight portion of the loop prior to passage of the web over the folding mandrel toeffect the longitudinal web fold prior to entry into the bag forming machine. The additional capping layer may be in the form of an unfolded separate strip, a folded hem in the continuous web itself or an independent capping strip folded about the edge of the web, the choice of any particular capping form requiring only the appropriate initial threading of material and adjustment of the attachment to correspond with the lateral dimensions of material used,
The frame structure of the attachment is in the nature of a pair of a pedestral supported upstanding standards having crossbeams or ways extending between the standards and adjustably supporting the various supply roll mounts of heat sealable material, capfolding means and heat sealing means. The heat sealing means employed in the machine is in the form of a pair of elongated heating wires on each side of the unfolded web, each heating element being pivotally supported to facilitate movement to a closed position in which the wires are in close proximity to the web in operation or pivoted away from the web so as to have no heating effect on the web. A control system is employed by which the heating elements are automatically withdrawn from a heating position in relation to the web in the event of web stoppage for any reason.
Among the objects of the present invention are: the provision of a novel, highly effective and versatile capping and web folding attachment for bag making machines; the provision of a bag forming machine attachment in which all operating components are readily accessible for adjustment, maintenance and threading of web material; the provision of such a bag forming machine attachment by which floor space required for its use is minimized; and the provision of such a bag forming machine attachment which is inexpensive and adaptable to forming a wide range of specific bag structural designs.
Other objects and further scope of applicability of 4 the present invention will become apparent from the detailed description to follow taken in conjunction with the accompanying drawings in which like reference numerals designate like parts.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of the edge capping and web folding attachment of the present invention;
FIG. 2 is a front elevation of the machine attachment illustrated in FIG. 1;
FIG. 3 is a rear elevation of the attachment shown in relation to the feed end of a conventional bag forming machine;
FIG. 4 is an enlarged fragmentary cross-section taken on line 44 of FIG. 2;
FIG. 5 is an enlarged fragmentary cross-section taken on line 5-5 of FIG. 2;
FIG. 6 is an enlarged fragmentary perspective view illustrating a capping strip folding arbor in the attachment of the invention;
FIG. 7 is an enlarged fragmentary cross-section taken on line 77 of FIG. 4;
FIG. 8 is a fragmentary cross-section taken on line 88 of FIG. 7; and
FIGS. 9-12 are fragmentary perspective views illustrating the various types of bag mouth structures to which the attachment is adaptable.
DETAILED DESCRIPTION OF THE PREFERED EMBODIMENT In FIGS. 2-3 of the drawing, the edge capping and web folding attachment of the present invention is shown to include a frame structure generally designated by the reference numeral 10 formed by a base or pedestal 12 and a pair of essentially vertical or upstanding standards 14 and 16. The standards 14 and 16 are structurally interconnected by transverse beam-like components to be identified and described below and in connection with operating components supported thereon.
Cantilevered forwardly from the standards 14 and 16 are vertically spaced sets of roll supporting brackets 18, 20 and 22 respectively, each such set of brackets providing at least two points of support for rolls of thermoplastic web material to be used in bag forming operations. In the illustrated embodiment and as shown in FIGS. 1 and 2, the bracket sets 18 and 20 each support a web supply roll 24 and 26, respectively and carried on central shafts 28 of identical construction. It should be noted that two supply rolls of web material are commonly used to form bags with double thicknesses of plastic material, the web forming the outer layer and printed with appropriate designs being supplied from the roll 26 whereas an inner or lining layer is provided by the web supplied from the roll 24. In practice, the two webs are superimposed one on the other and thereafter treated as a single web in terms of the operations performed both by the attachment on the present invention and in the bag forming machine. Quite obviously, the formation of a bag without a double thickness of plastic material or without a liner would involve using only one of the bracket sets 18 or 20 to supply a single thickness web of material.
Each of the roll supporting shafts 28 project axially of the respective roll 24 and 26 supported thereon so that opposite ends of each shaft 28 are cradled for rotation on a pair of spaced roller pairs 30 journalled near the upper edge surface of the supporting brackets. To one end of each shaft 28 projecting beyond the brackets supported by the standard 16 is fixed a double flanged spool-like collar 32 to be engaged by an axially adjustable positioning carriage 34 supported on cylindrical ways 36 secured to the standard 16. Each carriage 34 is connected to a hydraulic ram 37 operated under the control of an electrically operated valve 38. The function of the carriages 34 and associated components is to position each of the rolls 24 and 26 in relation to a preestablished vertical reference plane between the standards 14 and 16 under the control of conventional edge position sensors or detectors (not shown) and positioned downstream from the rolls 24 and 26 in terms of web travel.
The bracket set 22 similarly supports a pair of capping strip supply rolls 40 and 42. Inasmuch as two independent capping strip supply rolls may be used, each roll is supported on an independent shaft 44 supported rotatably at its outer end by the brackets 22 and at its inner end by brackets 22a in turn supported by a beam member 46 extending between the standards 14 and 16 (see FIG. 2). The outboard end of each of the shafts 44, like the shafts 28 described above, receive axially fixed double flanged collars 48 engaged for axial movement with carriages 50 which function in the manner of a travelling nut on an adjusting screw 52. It will be appreciated that in light of this arrangement, rotation of the screw 52 will determine the axial or transverse position of the collar 48 and thus of the roll 40. The roll 42 is equipped with identical means for adjusting its axial or transverse position in relation to a central vertical plane between the standards 14 and 16.
In order to provide a clear understanding of the structure and operation of the present invention, it is noted that conventional bag forming operations involve the continuous pulling of a web from a supply roll such as either one or both of the supply rolls 24 and 26 over a longitudinal folding mandrel into the bag forming machinery at which continuous longitudinal feed of the longitudinally folded web is converted to an intermittent longitudinal feed operation. Thus in FIG. 3 of the drawings, the feed end of a conventional bag forming machine 54 is shown to include an electric motor 56 or other suitable form of rotatable drive connected to a continuously rotatable capstan 58 about which a loop or bit of the longitudinally folded web W is trained for continuous longitudinal advance at velocities corresponding to the production rate of the bag forming machines. Downstream in the machine in relation to web travel, are located one or more intermittently driven capstans (not shown) by which the web is advanced in increments to successive bag forming stations mounted on the machine. The conversion of continuous feed by the capstan 58 to intermittent feed in this manner is accommodated by a set of compensator rolls 60 mounted on a spring or weight biased arm 62 for oscillation about a point of support 64. As is well known in the art, the compensator rolls serve to take up a longitudinal increment of the continuously fed web portion during dwell periods in the intermittently fed web portion downstream from the compensator rolls. Also in accordance with conventional practice, longitudinal folding of the web W is achieved by pulling a web from a horizontally oriented supply roll downwardly over a V- shaped folding anvil. As shown in FIGS. 1 and 3 of the drawings, the longitudinal web folding anvil in the illustrated apparatus is provided by a pair of circular rods 66 supported between the rear of the pedestal l2 and the standards 14 and 16. The rods 66 are oriented to lie in a plane inclined at approximately 45 with respect to the standards 14 and 16 and converge at their lower ends near a guide roller 68 from which the now folded web is passed to the capstan 58. Because the composite and longitudinally folded web W is pulled from the supply rolls 24 and 26, a measure of tension is maintained in the web by drag strips 70 supported from rods 72 and draped over each roll of web material. The drag strips are formed of any suitable textile material such as canvas or the like and are weighted by bars 74 at their hanging end to assure the appropriate amount of drag.
The flight path through which the web material is drawn in the attachment of the present invention is established in substantial measure by a series of freely rotatable, parallel guide rollers extending transversely between the standards 14 and 16. Hence the web material from the lowermost supply roll 24, as may be seen in FIG. 1 of the drawings, passes about a guide roller 76 upwardly about a guide roller 78 about which the web from the supply roll 26 is also trained to be superimposed on the web from the supply roll 24. The superimposed or double layer web passes upwardly from the roller 78 past a guide roller 80 over a cap folding anvil 82 to be described in more detail below and then to a guide roller 84 positioned near the top of the standards 14 and 16. In passing from the guide roller 78 to the cap folding anvil 82 over the guide roller 80, a slight reverse bend is effected in the web so that edge strips, if used, passing from the supply rolls 40 and 42 will be superimposed and pressed against opposite edges of the double web layer passing from the rolls 24 and 26. The composite web W is then fed from the guide roller 84 over the top of the attachment to a guide roller 86 then downwardly in a straight run to a guide roller 88. After passing the guide roller 88, the web is directed inwardly and downwardly about a pair of guide rollers 90 and 92 and then over the folding mandrel rods 66 as described above. Thus it will be seen that in passing from the supply rolls 24, 26, 40 and 42 to the folding mandrel rods 66, the web material is constrained to a vertically oriented loop formation establishing an upwardly traveling and generally vertical run between the guide rollers 80 and 84 and a horizontally spaced downwardly traveling vertical run between the rollers 86 and 88. It should be noted further that because of the arrangement of guide rollers, the web material may be passed from either or both of the supply rolls 24 and 26 directly over the guide rollers 90 and 92 and then downwardly over the folding anvil rods 66. This path might be used in bag forming operations where no capping layer is required.
The organization of the structural components in the cap folding anvil 82 may be understood by reference to FIGS. 4-6 of the drawings. As shown, support for the cap folding anvil is provided by a transverse plate-like beam or way 94 secured to the front surface of the standards l4 and 16. Supported on the way 94 by two pairs of runners 96 and 98 are a pair of overlapping or telescopic plate-like carriages 100 and 102 respectively. The front edge of the plates 100 and 102 overlie each other in coextensive relation and are appropriately rounded or otherwise formed so as to provide no appreciable drag on the web material passing thereover through the flight path between the guide rolls and 84 as illustrated most clearly in FIG. 4 of the drawings. Each of the carriage plates and 102 is provided with a plate-like weldment 104 having a threaded aperture for receiving in running nut fashion hand screws 106 secured against axial displacement with respect to the standards 14 and 16. Thus adjustment of the hand screws 106 will effect transverse adjustment of either one or both of the carriage plates 100 and 102.
Near the outboard end of each of the carriage plates 100 and 102, a cap folding slot 108 is formed. Each of the folding slots opens to the rounded leading edge of the respective carriage plates 100 and 102 and extends inwardly of the plate at an acute angle with respect to the rounded leading edge to engage the web Also mounted on each of the plate carriages 100 and 102 inwardly adjacent to the slots 108 are plate anvils or shoes 110 inclined upwardly at an angle approximating the inclination of the web flight portion passing between the cap folding anvil and the guide roller 84. A pair of retractable press rollers 112 and 114 are also supported on each plate carriage upwardly of the slots to exert a slight pressure of web material against the anvils or shoes 110. In light of this organization, it will be appreciated particularly by reference to FIGS. 4 and 5 of the drawings that capping strips passing from the supply rolls 40 and 42, after being superimposed against the edge of the double layer web of material passing from the rolls 24 and 26, need only be threaded into the slots 108 with the result that each capping layer will be folded continuously and neatly about the corresponding edge of the web. Moreover, by appropriate adjustment of the screws 52 to adjust the position of the rolls 40 and 42 and by adjustment of the hand wheels 106 to position the plate carriges 100 and 102, the cap folding function may be oriented with respect to the web irrespective of its width or lateral position between the standards 14 and 16.
As shown in FIGS. 1, 3-5, 7 and 8 of the drawings, two pairs of elongated heat fusion members 116 and 118 are supported for operation near the opposite edges of the web W in the flight portion thereof extending between the guide rollers 86 and 88. Each of the heat fusion member pairs 116 and 118 is identically constructed and mounted in a manner very similar to the manner in which the above described plate carriages 100 and 102 are mounted. Specifically, each heat fusion member pair 116 and 118 is supported by a C-shaped bracket 120 secured to a carrige 122 in turn slidably mounted on a transverse plate-like way or beam 124 extending transversely between the standards 14 and 16 and fixed to the rear edges thereof. Each of the carriages 122 are operably connected in running nut fashion with axially fixed hand screws 126 as shown most clearly in FIGS. 4 and 5 of the drawings The construction of the heat fusion member pair: 116 and 118 is illustrated most clearly in FIG. 5 of the drawing to include in each pair, two identically constructed plate assemblies 128 fixed for rotation with 1 pair of vertically oriented rotatable shafts 130 coupler for simultaneous rotation in opposite directions by pair of meshed pinion gears 132, at least one of whicl is adapted to be rotated or oscillated by a ram-type fluid motor 134. In light of this organization it will be apprecited that the plate assemblies 128 in each heat fusion member pair 116 and 118 may be moved between an operative position as shown in solid lines in FIG. in which the plate assemblies 128 overlie the edge portion of the web W in essentially parallel relation, and an inoperative position illustrated in phantom lines in FIG. 5 wherein both plate assemblies 128 are simultaneously pivoted outwardly away from the web.
The mutually facing surfaces of the plate assemblies 128 are provided with an elongated vertical groove 136 in which a nichrome heating wire 138 is situated out of contact with any of the surfaces of the plate assembly. Vertically oriented cooling passages 140 are arranged in each of the assemblies 128 on opposite sides of the wire 138 and through which an appropriate cooling medium such as water may be circulated by appropriate flexible conduits 142 (see FIG. 7).
It should be noted in connection with each of the heat fusion member pairs 116 and 118, that the length of the plate members 128 and correspondingly of the heating wires 138 may extend to approximately eighteen inches in practice. Also it is noted that in their operative position, little or no pressure is exerted on the web by the heat fusion member pairs. The result of this organization is the achievement of extremely uniform and relatively low temperature heating over the length of the nichrome wires 138 with a uniform fusion of all layers of the thermoplastic material passing between the two nichrome wires of each pair. Moreover, because of the length of web material subject to heating by the nichrome wires, and correspondingly low fusion temperatures required, control over fusion temperature's is greatly facilitated to a point where complicated thermostatic control circuitry is not needed. In other words, the temperature of the nichrome wires is merely regulated to account for the combined thickness of layers to be fused and the linear velocity of the web in passing between the guide rollers 86 and 88.
It is important however that any cessation of web movement be accompanied by movement of the heat fusion member pairs 1 16 and 118 immediately to an inoperative position. This is accomplished in accordance with the invention by a control organization illustrated schematically in FIG. 3 of the drawings. In particular at the feed end of a conventional bag making machine 54, drive for the capstan 58 is terminated automatically after cessation of intermittent feed of the web W downstream in the bag machine when the length of material in the compensator rolls 60 is sufficient to allow the arm 62 to to pivot to its lowermost position as shown in phantom lines in FIG. 3, for example. At that point, the arm 62 opens a switch 144 to interrupt the circuit to the drive motor 56 for the capstan 58. A control unit 146 is provided for the attachment of the present invention and is connected also in series with the switch 144 so that upon opening the switch to terminate rotation of the capstan 58, a signal is simultaneously directed by conventional means to the ram 134 of each of the fusion member pairs 116 and 118 so that the plate assemblies 128 and the heating wires 138 will be moved to their inoperative position. Similarly, closure of the switch 144 as the operation is started up will effect a reversal of this operation. It should be noted also that the control unit 146 is operably connected to each of the valves 38 operating the rams 36 to control lateral or alignment positioning of the rolls 26. This interconnection is provided so that the switch 144, when opened due to the end of a web being readied, will operate the valves 38 so that the carriages 34 will remain in a neutral position. Otherwise, the edge detectors (not shown) would effect operation of the rams moving the carriages 34 to an extreme end position unnecessarily.
To provide an understanding of the various bag types which may be accommodated by the attachment of the present invention, reference is made to FIGS. 9-12 of the drawings. As shown in FIG. 9, for example, the top bag 150 is shown provided with edge caps 152 formed merely by a hem in a single web of material which might be supplied from one of the rolls 24 or 26. In the formation of this bag, the rolls 40 and 42 would be eliminated and the opposite edges of the web merely threaded into the folding slots 108. The folded over edges of the web material would be fused along a fusion line 154 established by the location of the heating wires 138.
In FIG. 10, a bag 156 is shown in which a separate capping strip 158 is folded over opposite edges of the initial web in the manner directly correlated to the de scription of the disclosed apparatus given above. Punched hand gripping apertures 160 would of course be formed in the bag making machine 54 during the intermittent feed of the web material and in accordance with conventional practice. In FIG. 11, a bag structure 162 similar to that illustrated in FIG. 10 is shown except that the web of material to form this bag is folded off the longitudinal center line thereof so that the edge caps 164 and 166 of the front and rear panels of the bag are offset accordingly. In this type of bag, a closure is provided by folding the capped lip or flap 166 over the offset cap 164 of the other lip.
in FIG. 12, a handle bag structure 168 is illustrated in which a capping on one side of the bag is folded over and heat fused in place whereas on the other or front panel of the bag, an unfolded strip 172 is provided for the attachment of a single handle 174. In the ultimate bag formed, the unfolded flap 172 is designed to be inserted in the folded over cap 170 on the other panel of the bag so that the handle will project through a slot 176 therein. Although the attachment of the handle 174 as well as other non-continuous operations is formed using conventional attachments in the bag making machine 54, the fusion of the capping strips to the bag material is effected very simply in accordance with the present invention. Specifically, the capping strip 170 used to form the folded edge of the bag is threaded through the folding slot 108 whereas the capping strip 172 on the other side of the bag is merely superimposed against the opposite edge of the web without folding.
Thus it will be appreciated that by the presentinvention a highly effective edge capping and folding attachment is provided for bag making machines and by which the above stated objectives are completely fulfilled. It is contemplated that various modifications may be made in the embodiment of the invention illus trated and described herein without departure from the essence of the invention. It is expressly intended therefore that the foregoing description is illustrative of a preferred embodiment only, not limiting, and that the true spirit and scope of the present invention be determined by reference to the appended claims.
1. An edge capping and web folding attachment for bag forming machines including types in which a longitudinally folded web of heat sealable sheet material is advanced continuously to a compensating roll assembly and thereafter intermittently for the performance of bag forming operations during correspondingly intermittent dwell periods, said attachment comprising in combination:
a supporting frame;
means on said frame to support at least one supply roll of heat sealable web material;
means for continuously folding the web longitudinally and for guiding the longitudinally folded web to the bag forming machine;
a plurality of parallel guide roller means supported by said frame and located thereon to establish a looplike path for the web in passing from the supply roll to said folding means, said loop-like path defining first and second spaced flights of web material;
edge capping means supported on said frame operable along said first flight of web material for superimposing at least one additional thickness of heat sealable sheet material on and along at least one side edge of said web;
heating means movably supported on said frame and operable along said second flight to fuse said additional thickness of sheet material to said web during continuous movement of said web and said thickness in said second flight; and
automatic means for withdrawing said heat sealing means away from the web upon interruption of web movement through said loop-like path.
2. The apparatus recited in claim 1 wherein said frame comprises a pedestal and a pair of upright standards, the transverse spacing between said standards being greater than the width of said heat sealable web material before it is longitudinally folded, said guide roller means extending between said standards and wherein said web material passes upwardly from said supply roll about said guide rollers and downwardly to said longitudinal folding means to establish said looplike path and orient said first and second flights of web material in generally vertical orientation on opposite sides of said standards, said edge capping means comprising a cap folding anvil supported on said standards between a pair of said guide rollers defining said first flight of web material.
3. The apparatus recited in claim 2 wherein said edge capping means includes a supporting bracket for mounting a capping strip supply roll in operative relation to said cap folding anvil and the edge of said web.
4. The apparatus recited in claim 2 wherein said edge capping means comprises a pair of plate-like carriages supported between said standards for independent transverse adjustability with respect to each other in telescopic fashion and with respect to said standards, said plate-like carriages establishing a common guiding edge for said web in traveling between said pair of guide rollers defining said first flight, each of said platelike carriages having a folding slot extending rearwardly and inwardly from said common edge at an acute angle thereto.
5. The apparatus recited in claim 2 wherein said second flight of web material is linear and wherein said heating means comprises at least one pair of elongated parallel heating wires supported on opposite sides of said web near one edge thereof.
6. The apparatus recited in claim 5 wherein said heating means comprises plate assemblies having mutually facing surfaces along which said heating wires are supported, said plate assemblies being movable between an operative position in which said mutually facing surfaces are disposed in essentially parallel relation on opposite sides of said web and an inoperative position in which said surfaces are swung away in diverging fashion from said web.
7. The apparatus recited in claim 6 wherein said plate assemblies include means for circulating a cooling medium therethrough on opposite sides of said heating wires.
8. The apparatus recited in claim 6 wherein said heating means comprises two pairs of said plate assemblies and independently movable carriages for supporting each pair whereby said heating means can be adjusted to accommodate the width and location of said web be tween said standards.
9. The apparatus recited in claim 6 including power means for pivoting said plate assemblies and said heating wires between said operative and inoperative positions, said automatic means including means responsive to cessation of web movement and operative to actuate said power means.
10. An edge capping and web folding attachment for bag forming machines including types in which a longitudinally folded web of heat sealable sheet material is advanced continuously to a compensating roll assembly and thereafter intermittently for the performance of bag forming operations during correspondingly intermittent dwell periods, said attachment comprising in combination:
an upright supporting frame;
a plurality of vertically spaced web supply roll supporting brackets mounted on one side of said frame to support one or more supply rolls of heat sealable web material;
means at the lower portion of the other side of said frame for continuously advancing and folding the web longitudinally and for guiding the longitudinally folded web to the bag forming machine;
a plurality of parallel guide roller means supported by said frame and located thereon to establish a vertically oriented loop-like path for the web in passing from a supply roll on one side of said supporting brackets to said folding means, said loop-like path defining first and second vertically oriented spaced flights of web material about the upper portion of and on opposite sides of said frame,
edge capping means supported on the one side of said frame operable along said first flight of web material for superimposing at least one additional thickness of heat sealable sheet material on and along at least one side edge of said web;
heating means movably supported on the other side of said frame and operable along said second flight to fuse said additional thickness of sheet material to said web during continuous movement of said web and said thickness in said second flight; and
automatic means for withdrawing said heat sealing means away from the web upon interruption of web movement through said loop-like path.
1 1. The apparatus recited in claim 10 wherein at least one of said roll supporting brackets is adapted to support a capping strip supply roll and including means for adjustably positioning the caping strip supply roll in opthe longitudinally folded web delivered to the bag forming machine, and means for adjustably positioning said edge capping means and said heating means also transversely to be in operative relation with the side edges of the web.