Patent Publication Number: US-3875726-A

Title: In-feed device and method

Description:
United States Patent Harris et al.  
 [ 1 lN-FEED DEVICE AND METHOD [75] Inventors: Thomas Charles Harris, Monroe;  
 Doyle Rayford Hudson, West Monroe, both of La.  
 [73] Assignee: Olinkraft, Inc., West Monroe. La.  
 [22] Filed: Oct. 23. 1973 [2i] Appl. No.: 408.310  
 [52] U.S. Cl 53/44; 53/371 [51] Int. Cl B65b 7/06 [58] Field 01&#39; Search 53/39. 38, 40. I88, 44, 53/139. 371, 372, 373  
 [56] References Cited UNITED STATES PATENTS 2.097.447 ll/l937 Cundall et al. 53/371 X 2.362.462 l 1/1944 Belcher et ul 53/139 X 2.725.168 11/1955 Lindstaedt Et L11. 53/188 3.236.433 11/1966 Johnson et al 53/373 X 3.420.034 H1969 Saraisky et a1 53/372 X 3.559.372 2/1971 Cerioni 53/37l X [57] ABSTRACT An improved in-feed device and method for, for ex- Apr. 8, 1975 ample, the final closing stage of a bag filling machine of the type wherein a plurality of bags are filled in a rapid sequence and the bags are subsequently closed. The novel in-feed device is located at the entrance to the bag closing station and includes an in-feed mechanism having a pivoted, movable inlet portion which initially presents open, tapered contact surfaces (FIG. 1 to the entering bar and subsequently. after the bag enters the device. presents closed, parallel contact surfaces (FIG. 2), the contact surfaces continuously moving in a longitudinal direction along the machine. The inlet portion. made up of two pivot arms. is moved from its tapered configuration to its parallel configuration and back again for each bag by means of a horizontally disposed yoke having diverging. slotted arms and being driven by a single centrally located. in-line air cylinder. Vertical pins fixed to the pivot arms and riding in the slots of the diverging yoke arms, cause the pivots arms to move in and out as the yoke is reciprocally driven by the air cylinder. The longitudinally moving contact surfaces, formed by moving belts. position, hold and guide the top of the bag (whose gussets have previously been reformed after the bag has been filled) preliminarily to its being closed by heat sealing or. alternatively, by sewing. Retarding finger straps are included at the inlet portion to initially apply pressure to certain types of bags to prevent the formation of wrinkles therein.  
 12 Claims, 4 Drawing Figures PATENTEDAPR 8l975 SHEET 1 or 4 PATENTEUAPR&#39; 3x915 3,875,726  
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 lN-FEED DEVICE AND METHOD CROSS-REFERENCES TO RELATED APPLICATIONS US. Pat. No. 3.698.45l. issued Oct. l7. l972 (filed Feb. 8, I97 I to Doyle R. Hudson and entitled Automatic Bag Opening and Filling Apparatus.  
  U.S. Pat. No. 3,750,72l, issued Aug. 7. I973 (filed Aug. [8, 1971) to Doyle R. Hudson and entitled Expanding Fill Spout for Bag Filling Machine.  
  U.S. Pat. No. 3.755.986. issued Sept. 4. I973, (filed Sept. 30. 1971 to Doyle R. Hudson and entitled Gusset Reformer.  
  U.S. Pat. No. 3.796.300. issued Mar. 12. I974 (filed July 17. l972)to Doyle R. Hudson and entitled Multiple Finger Pushers.  
  Patent application Ser. No. 344.l20. filed July 10, I973 by Doyle R. Hudson and entitled Drop-Down Fill Spout For Bag Filling Machine.  
  The foregoing related patents and patent application are all assigned to Olinkraft, Inc.. the assignee of the present application. and are directed to various elements or sections of a fully automatic filling machine for bags including the bag opening, filling, moving and reforming portions thereof; while the preferred embodiment of the present invention is directed to the infeed device used in the final closing and sealing portion of the machine.  
 BACKGROUND OF THE INVENTION The present invention relates to an in-feed device and method for grasping, positioning and guiding a structure comprised of two facing sheets of flat material. as for example the top ofa bag, as it is being introduced into a machine, as for example a bag closing station utilizing sewing or heat sealing means. The present invention has been found to be particularly useful in the bag handling art. especially as the mechanism for transferring the bag from a bag reforming station to the final bag closing station. and hence will be discussed with particular reference thereto.  
  Several types of in-feed devices and methods have been known and used before. and typical examples thereof in the bag handling art are shown in U.S. Pat. No. 3,687.790, issued Aug. 29. I972 to T. Wehren et a], and U.S. Pat. No. 3,69l,968, issued Sept. 19. I972 to Schnepf, U.S. Pat. No. 2,097.447, issued Nov. 2. I937 to Cundall et a], and U.S. Pat. No. 2,725,168. issued Nov. 29, 1955 to Lindstaedt et al. The Wehren infeed device. as shown particularly in FIGS. 2 and 3, constitutes a dual. opposing set of parallel belts moving in a longitudinal direction. the belts being run around supports which are static or fixed in relationship to one another and hence cause the belts to remain parallel at all times during operation. The Schnepf in-feed device, as shown particularly in FIG. 2, utilizes a dual, opposing set of moving belts which at its inlet portion have a tapered or slanted or diagonal disposition before becoming parallel. but whose supports remain static throughout operation insofar as their relative positions are concerned and hence the belts follow the same path throughout the machine&#39;s operation. The Cundall infeed device. noting particularly FIGS. 3 and 4, includes dual, opposed moving belts mounted on rollers carried on opposing swinging supports which move from a closed. parallel disposition to an open. diagonal disposition and back again, but whose support rollers ae all equal in diameter and hence the moving belts do not have a tapered entry when closed.  
  However, it has been found that the bags in being processed through the in-feed devices of the prior art often or at least on occasion became misaligned or wrinkled, so that when they were closed in the sewing or sealing station, the closures were improperly and/or inaccurately made or made askew. It is further noted that a Wehren type device. that is. one in which the bag is fed in between static rails with parallel conveyor belts. does not work reliably. Moreover. as the the Schnepf device. that is, one in which the bag is fed initially into a tapered but fixed inlet and then through static. parallel conveyors. although it does work better. it still suffers from the problems referred to above. Indeed a special operator was often needed in the prior art to perform manual or hand feeding of the bags to the closing station. Finally, as to the Cundall and Lindstaedt devices. although in using pivoting support arms they may have worked still better, they. it is believed. suffer from at least some of the same problems referred to above.  
  In contrast to the prior art. the present invention utilizes an in-feed mechanism utilizing not only dual, opposed. moving belts whose supports are not static but instead, initially present a tapered configuration at the inlet portion as the bag enters it and subsequently. after the bag enters the device. presents in part a closed. parallel configuration as the supports are pivoted together. but also includes a slightly tapered portion at its distal end even when the supports are pivoted together. Thus. dual pivot supports or arms movable in and out into and away from the center-line of the machine are utilized in combination with longitudinally moving contact belts on the relatively moving pivot supports to initially present an open, tapered inlet configuration and thereafter to present a closed. parallel configuration but still having a slightly tapered distal portion. Such a combination causes the moving belts to initially but positively contact the bag with a point contact and then later. in a continuous. smooth flowing fashion. contact the bag with full line, face-to-face engagement. This combined. staged action allows the in-feed device to properly guide, align and hold the bag in preparation for the closing operation.  
  Additionally. retarding pressure fingers are positioned in the front entry portion of the device which bear against the bag at a point removed from the initial contact point with the belts. The pressure fingers serve to retard the bag. removing any wrinkles or preventing the formation of any wrinkles.  
  The staged (point to line) but positive contact action of the belts on the movable pivot arms and the pressure retarding action of the fingers acting in combination on the bag eliminate all the problems of the prior art. However. it should be noted that. although the combined action is believed to be synergistic or at least preferred. the two mechanisms can operate independently of one another and have independent value.  
  Furthermore. the present invention provides the solution to the prior art problems with a straight-forward, reliable and relatively simple device without any need for hand labor.  
  Additionally, as explained more fully below, besides serving as a simple in-feed device, the present invention can also be used to perform the final reforming step for the gusseted bag top, eliminating the structure heretofore used for that step.  
  Finally, the in-feeding operation is performed without the need of doing it at an unreasonably high speed because of combining the final reforming, in-feeding and initially closing functions in a single operation, further enhancing the reliability of performance.  
 BRIEF DESCRIPTION OF THE DRAWINGS For a further understanding of the nature and objects of the present invention, reference should be had to the following detailed description, taken in conjunction with the accompanying drawings, in which like parts are given like reference numerals and wherein:  
  FIG. I is a top, plan view of the preferred embodiment of the in-feed device of the present invention, showing the inlet portion thereof in its open, tapered disposition, with the bag just beginning to enter into the in-feed device; while FIG. 2 is a top, plan view of the preferred embodiment of the in-feed device of the present invention with the inlet portion in its closed, parallel disposition, with the bag almost fully into the in-feed device.  
  FIG. 3 is a side, partial view of the preferred embodiment with the inlet portion being in its closed configuration, as illustrated in FIG. 2.  
  FIG. 4 is an end. cross-sectional view of the preferred embodiment, taken along section lines 4-4 of FIG. 3.  
 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Introduction The in-feed device of the present invention can be utilized as the in-feed device for any sort of bag opera tion station wherein it is important that wrinkles not be present in the top of the bag and the top of the bag be properly aligned and positioned as it is being operated on. or for that matter for other types of structures which include two sheets of flat material in face-toface engagement wherein their relative alignment is important. A particularly important area of application of the present invention is in the in-feed portion of the bag closure station which forms the final step of reestablishing the preformed gussets in a paper bag after it has been filled, and therefore the preferred embodiment of the present invention will be described with respect to such an application. Also. the present invention is especially suitable for use with the pinch style bag and the preferred embodiment will be described with respect thereto, but the present invention could be applied to almost any bag where the elimination of wrinkles in the closure area and the proper positioning of the bag are important. In the preferred application of the present invention, the final closure of the pinch Style bag is accomplished through the reactivation of a pre-applied hot melt and the folding over and securing of a top flap which is manufactured on the bag itself and the preferred embodiment will be described with respect thereto, but the present invention is of course equally applicable to the closing of a bag by oth means such as for example a sewing process.  
  As generally referred to in the Cross-References to Related Applications&#34; supra. the preferred embodiment ofthe present invention is used in a bag filling machine in the very final step of reestablishing the preformed gussets in the paper bag after it has been filled and prior to it being sealed or sewn closed. For a general understanding of the relationship of the final closing station, with the in-feed device of the present invention, to the other stations which preceed it in the fully automatic bag filling machine of which it is a part, reference is had to U.S. Pat. No. 3,755,986 entitled Gusset Reformer, and particularly to its FIG. 1 and its column 3, lines I9-50. In the over-all machine, a bag to be filled is first opened, filled and then reformed, all as it is being conveyed down the machine. Finally, with the use of the in-feed device of the present invention, the bag is moved from the bag reforming station to the closing station for final sealing or sewing. The prime function of the in-feed device and method of the present invention is to grasp, guide and hold the top of the reformed bag top and properly position it for final closing. Secondarily it serves as the final reforming element for the bag top by bringing together in face-to-face engagement the reformed gussets and the face and back of the bag.  
 STRUCTURE &amp; ITS METHOD OF USE With reference particularly to FIGS. 1 and 2, the preferred embodiment of the in-feed device of the present invention includes two pivoted, opposed, in-feed arms 1 and 2, which pivot about axes 3 and 4, respectively. The in-feed pivot arms 1 and 2 are driven from their open/tapered disposition (FIG. 1) to their closed/parallel disposition (FIG. 2) and back again by means of a reciprocating yoke 5 driven by air cylinder 6.  
  The yoke 5 has two diverging arms 7 and 8 with slots 9 and 10 therein. Vertical pins II and 12 are fixedly attached to the pivot arms 1, 2 and ride in the slots 9, 10. The yoke 5 and the air cylinder 6, which are connected together by drive arm 13, are positioned horizontally in-line, along the center-line of the machine. Guide arm 14 serves to keep the yoke 5 in proper horizontal and lateral alignment as the yoke assembly moves longitudinally under the action of the air cylinder 6. As air cylinder 6 causes the yoke assembly to reciprocate forward (to the right in FIG. 1) and back (to the left in FIG. 2) in a longitudinal direction, vertical pins 11 and 12 riding in yoke slots 9, 10 cause the pivot arms 1, 2 to go from the open, tapered, inlet disposition of FIG. I to the closed, parallel, holding disposition of FIG. 2 and back open again.  
  The pivot arms I, 2 carry dual, opposed conveyor belts l5 and 16, respectively, which provide moving contact surfaces for holding the tops of the bags as they are conveyed to the closing station. The belts l5, 16, which are rubber V-belts, are endless and are each mounted on three vertically disposed rollers 17-19 and 20-22, respectively. The vertical axes of rotation of the back, exit rollers 17, 20, of the central rollers 18, 21 and of the front, entry rollers 19, 22 are fixedly mounted on the pivot arms I, 2, respectively, and are in-line with each other on each arm.  
  However, in the most preferred embodiment the diameters of the entry rollers 19, 22 are a little less than that of the other rollers so that, although the belts l5, l6 are substantially parallel to each other in the closed disposition of the pivot arms I, 2 (FIG. 2) as they contact the bags, there is still a slight entry taper or gap in the forward, entry portion. This gap allows room for retarding finger straps 23 and 24 to contact the bag at the entry portion of the device to apply retarding pressure toward the rear of the bag which tends to stretch the top of the bag and eliminate any wrinkling that may occur when the sides (face and back) of the top of the bag are forced together by the belts 15, 16. The retarding finger straps 23, 24 are made of resilient, springy material and are so mounted on the front, curved inlet portions 25, 26, respectively, of the device that they have an inherent tendency or bias to move away from the bag or outwardly toward the sides of the machines so as to bear against the tips of adjusting or set screws 27 and 28. The adjusting screws 27, 28 adjust the pressure applied on the bags and, when fully backed off, eliminate the retarding action as the finger straps 23, 24 will then lay flat against the sides of the pivot arm extensions 29, 30 out of contact with the bags. The retarding finger straps 23, 24 need not be used with all types of bags, but should be used with those bags that are relatively flimsy with a substantial tendency to wrinkle.  
  The pivot arm extensions 29, 30 and the horizontal support plates 31 and 32 are fixedly attached to the pivot posts 33 and 34, and all move together and form the pivot arms 1, 2. The vertical pins 11, 12 are mounted on and attached to the pivot posts 33, 34, respectively, by means of brackets 35 and 36. The brackets 35, 36 are longitudinally adjustable with respect to the pivot posts 33, 34 by means of adjusting slots 37 and 38 included therein and the co-operating locking screws 39 and 40, and 41 and 42. (It is noted that the adjusting slots in pivot post 34 can not be seen in the figures but are substantially identical to slots 37, 38.)  
  The pivot arm extensions 29, 30 are made of channel iron and present opposing flat surfaces (note FIG. 4) to each other when the pivot arms 1, 2 are closed. These flat surfaces are of course static when the pivot arms 1, 2 are closed and serve to further but only generally guide and position the top of the bag as the bag is moved through the in-feed device and into the closing station. In contrast to the static flat surfaces of the pivot arm extensions 29, 30 with only little or light contact with the bag top, the belts l5, l6 serve as moving contact surfaces in full face-to-face, compressive engagement with the bag top.  
  At the exit end of the belts 15, 16 at the back, exit rollers 17, 20, there is included a second set of contact belts 43 and 44 mounted on supports which are static or fixed with respect to one another during operation. These parallel feed belts 43, 44 are in contact with the bag top as it moves through the closing station (not specifically shown).  
  The bag as it approaches the in-feed device is supported on a static support pan 45 (identical to the trough-shaped plate of FIG. 1 of the Hudson 986 patent) and is being pushed forward in cycles by means of the multiple finger pushers 46 (shown in phantom line in FIGS. I3 and which are the subject matter of the Hudson 300 patent).  
  As best shown in FIG. 3, the bag is pushed on to the horizontally disposed conveyor belt 47 which supports the bag and conveys it into the in-feed device and through the closing station. The belts 15, 16 and 43, 44 all move at the same linear speed as the conveyor belt 47 and maintain a griping contact pressure on the top of the bag as it is moved and supported by the bottom conveyor 47 through the in-feed device and closing station.  
  As generally shown in FIGS. 1 and 2, the bag is pushed by the multiple finger pushers 46 down the support tray 45 into the throat or entry of the in-feed device, while it is in its open, tapered disposition. In the actual position of the multiple finger pushers 46 illustrated in FIG. 1, the pushers 46 are in the position of being longitudinally retracted back (to the right in the figure) to begin a new pushing cycle, and reference should be had to the Hudson 300 patent for a further understanding of this operation.  
  At the point the bag is in the position shown in FIGS. 2 and 3, the multiple finger pushers 46 have reached their extreme forward position (to the left in the figures), leaving the bag partially on the tray 45 and partially on the bottom conveyor 47. At this point the air cylinder 6 is actuated through line 48 to close the pivot arms 1, 2 by means of the yoke/pin assembly 5/] l-l2 to the parallel disposition shown in FIG. 2. As best seen in FIG. 2, when the pivot arms 1, 2 close. the leading edge of the bag is between the two central rollers 18, 2I, the belts 15, 16 are in griping contact with the bag top, and the retarding finger straps 23, 24 are applying retarding pressure to the central portions of the bag top. The co-operative action which is produced on the bag by the moving belts 15, 16, the static finger straps 23, 24 and the bottom conveyor 47 prevents any wrinkles from occurring in the bag top and properly posi tions and aligns the bag top for closing. It should be further noted that the initial contact between the belts l5, l6 and the bag top is a point contact (because of the pivoting action) rather than an immediate face-to-face contact and that this point contact occurs at or in close proximity to the leasing edge of the bag. With the pivot arms 1, 2 closed and the bag being conveyed by the bottom conveyor 47, the initial point contact then in a continuous manner becomes a full line, face-to-face contact throughout the bag length. This action plays an important role in the superior results achieved by the present invention.  
  After the pivot arms 1, 2 close and the conveyor belt 47 moves the bag through the in-feed device and into the closing station where the belts 43, 44 are then in contact with the bag top, the pivot arms 1, 2 are reopened by the air cylinder 6 being actuated through air line 49. In the meantime, multiple finger pushers 46 have retracted, engaged the next bag, and moved back again to its most forward position, bringing another bag into the throat or entry of the in-feed device, and the cycle is repeated.  
  It should be noted that with the preferred embodiment of the in-feed device, the bag gusset reformer (such as the one which is the subject matter of the Hudson &#34;986 patent) can be operating on the bag in reform ing the bag gussets right up to its entry into the in-feed device. Indeed, the infeed device can serve as the final element in the reforming operation by bringing together the gussets (which have been reformed) and the face and the back of the bag when the pivot arms 1, 2 are closed and the top of the bag is passed through the parallel contact portions of the moving belts 15, 16. Thus the in-feed device of the present invention can be substituted for the guide rail holding means (enumerated as element 30 in the Hudson 986 patent). Indeed, with such a preferred substitution, an over-all superior closing operation is achieved. The gradual closing of the bag (with an adequate amount of bag material above the bag fill line of the product) and sufficient time provided for the work to be done upon the upper portion of the bag by the various components of these devices enhances the uniform wrinkle free closure obtained with the use of the present invention.  
  In summary then, in the present invention, the bag is fed from static rails and supports to a movable tapered in feed conveyor wherein the conveyors grab the bag in a point contact when the bag is about one-half into the in-feed device. When the transfer is made to the closed, parallel conveyors and a bag is about one-third into the fixed, parallel conveyors for the closing station. the pivot arms open up to accept the next bag. It is noted that in the preferred embodiment illustrated the bags are approximately l inches apart. moving at about 32 feet per minute. and the bags have a face width of approximately 16 inches and a height of approximately 24 inches and are to be sealed with a plastic resin by being passed through a heating element in the closing station. Thus. in the present invention. the in-feed device grasps a leading portion of the bag with tapered. pivotable conveyor belts while the bottom of the bag is being moved on a moving bottom conveyor off the dead plate. and finally completely closes the bag after the pivot arms close and the bag is passed through the in-feed device.  
  Although the mechanism described in detail supra has found to be most satisfactory and preferred. many variations in its structure are of course possible. For example. rather than use the single air cylinder 6 and yoke/pin assembly /1 ll 2. two separate opposed. diagonally disposed air cylinders could be used. one on each pivot arm. Also. because the belts 15. 16 do not come into contact with the bag until the belts pass over the central rollers 18, 21 the lead or entry rollers 19, 22 could be positioned further back on the support plates 31, 32 closer to the central rollers 18, 21. Indeed. the entry rollers conceivably could be eliminated. but their presence produces a better. more graduated taper or angular contact in the initial contact between the belts and the bag. Additionally, other detailed mechanisms can be added to the in-feed device. such as for example a belt tensioning system. etc. Moreover. it is conceivable that one of the pivot arms could be static or fixed while the other one is the only one that is moved or pivoted to present the open and closed configurations. and such an approach. although considered inferior. would be within the broadest concept of the present invention as an equivalent variation.  
  The above are of course merely exemplary of the possible changes or variations.  
  Because many varying and different embodiments may be made within the scope of the inventive concept herein taught. and because many modifications may be made in the embodiment herein detailed in accordance with the descriptive requirements of the law, it is to be understood that the details herein are to be interpreted as illustrative and not in a limiting sense.  
 We claim:  
  1. An in-feed device for a machine for structures comprised of facing sheets of flat. flexible material which need to be properly aligned for further processing. such as for example the top of a bag needing to be closed. comprising:  
 a basic machine support structure;  
 two. opposed. elongated pivot arms pivotably mounted on said support structure for pivoting about axes which are located on opposite sides of. but in proximity to, the center-line of the machine;  
 drive means mounted on said support structure for pivoting said pivot arms about said axes from a closed disposition wherein said pivot arms are parallel to said centerline to an open disposition wherein said pivot arms are diagonal to said centerline and back again;  
 moving means mounted on each one of said pivot arms for providing moving contact surfaces on the inner sides of said pivot arms. said moving contact surfaces being at least in substantial part parallel and in opposing face-to-face relationship to each other when said pivot arms are parallel and presenting a tapered or angular disposition when said pivot arms are diagonal;  
 conveyor means for conveying the structures on a one-by-one basis into the distal ends of said pivot arms removed from said axes;  
 control means for actuating said drive means to dispose said pivot arms in their open disposition for entry of each structure and to dispose said pivot arms in their closed disposition when each structure is substantially into and between the open pivot arms; whereby, when said pivot arms are driven to their closed disposition, the contact surfaces initially contact the structure with point contact and then will full line. face-to-face contact as the structure is conveyed through the in-feed device; and  
 opposed retarding pressure finger means mounted on said distal entry ends projecting inwardly toward said center-line and angularly back toward the proximal ends of said pivot arms to a point intermediate to said distal and said proximal ends for bearing against the structure only at points removed from the initial Contact point of the moving surfaces with the structure when said pivot arms are in their closed disposition for retarding the immediate and following portions of the structure against the advancing force of the contact surfaces in Contact with the structure; whereby wrinkles in the material are eliminated or prevented from formingv 2. The device of claim 1 wherein said pivot arms. when in their closed disposition, are parallel to each other along a first facing portion and then diverge slightly from one another at their distal entry ends forming a gap there between; thereby forming a tapered entry portion even when said pivot arms are in their closed disposition.  
  3. The device of claim 1 wherein said pressure finger means are made of straps of resilient. springy material and have inherent bias to move away from said centerline, and wherein there is further included:  
 set screw adjusting means mounted on said pivot arms and bearing against the operative ends of said straps for adjusting the physical location of the dista]. operative ends of said straps with respect to said center-line; whereby the retarding pressure of the straps can be varied or the straps moved away from the center-line to such an extent that the straps are rendered inoperative.  
  4. The device of claim 1 wherein said moving contact surfaces are belts. each one mounted on at least two rollers attached to the pivot arm.  
  5. The device of claim 1 wherein there is included at least three rollers an entry roller located toward the distal end of each said pivot arms. a central roller located centrally on each said pivot arms. and an exit roller located toward the proximal end of each said pivot arms, said entry roller having a diameter less than that of the other two rollers which are equal. whereby, when the contact surfaces become parallel between said cen tral and exit rollers when said pivot arms are parallel. the contact surfaces as they approach the central rollers do so with a relatively gradual taper.  
  6. The device of claim 1 wherein there is further included:  
 bottom conveying means associated with said con veyor means for supporting and conveying the structure through the in-feed device and into the next processing station of the machine.  
 7. The device of claim 1 wherein there is further included:  
 a supplemental. opposed set of parallel. moving contact surfaces mounted on supports which are fixed with respect to one another during operation and which bridge between the proximal ends of said pivot arms and the next processing station of the machine. the exit portion of said moving belt means leading into said supplemental set of moving contact surfaces.  
  8. The method of feeding structures on a one-by-one basis into a machine wherein the structures are comprised of facing sheets of flat, flexible material which need to be properly aligned for further processing, such as for example the top of a bag needing to be closed, comprising the following steps:  
 a. providing an in-feed device having an inlet portion comprised of two movable, opposed support arms mounted on opposite sides of the center-line of the machine and carrying on their inward, opposed sides longitudinally moving contact surfaces, and also carrying on their inward. opposed sides pressure finger means located at the distal. entry ends of said support arms and projecting inwardly toward said center-line and angularly back toward the proximal ends of said support arms to a point intermediate to said distal and said proximal ends, said support arms initially having an open, angular disposition with respect to the center-line of the machine, and providing appropriate conveying means in association with said in-feed device;  
 b. conveying the structures into the inlet portion of the in-feed device so that the leading edge of said structure is past the ends of said pressure fingers and the structure is substantially into and between said opposed support arms;  
 c. positively grasping the leading edge of the structure with the longitudinally moving contact surfaces by moving the support structures angularly in from their initial, open. angular disposition and toward the center-line of the machine so that the contact surfaces initially strike the leading edge of the structure at an angle with only opposed. point contacts. and closing at least an opposed portion of the support structures together so that the moving contact surfaces come together after initially striking the structures changing the point contacts to continuing. face-to-face, in line and opposed contacts;  
 (1. conveying the structure through the in-feed device to the next processing station of the machine; and  
 e. applying a retarding force on the structure by means of said pressure finger means bearing against only the intermediate portions, at an area located between the distal and proximal ends of said support arms, and subsequentially the trailing edges of the structure in a direction opposite to the advancing action of the conveying means while the structure is being conveyed through the in-feed device; whereby wrinkles are removed from, or prevented from forming in, the material. 9. An in-feed device for a machine for structures comprised of facing sheets of flat, flexible material which need to be properly aligned for further processing, such as for example the top of a bag needing to be closed, comprising:  
 a basic machine support structure; two. opposed. elongated pivot arms pivotably mounted on said support structure for pivoting about axes which are located on opposite sides of. but in proximity to. the center-line of the machine, each said pivot arms including at least three roller sections, an entry roller section located toward the distal end of each said pivotal arms. a central roller section located centrally on each said pivot arms. and an exit roller section located toward the proximal end of each said pivot arms, said entry roller section having a diameter or width less than that of the other two roller sections which are equal;  
 drive means mounted on said support structure for pivoting said pivot arms about said axes from a closed disposition, wherein said pivot arms are parallel to each other and to said center-line along a first facing portion and then diverge slightly from one another at their distal entry ends forming a gap therebetween due to the difference in diameter or width of said roller sections. to an open disposition wherein said pivot arms are diagonal to said centerline. and back again;  
 moving means mounted on each one of said pivot arms about said roller sections for providing moving contact surfaces on the inner sides of said pivot arms, said moving contact surfaces being at least in substantial part parallel and in opposing face-toface relationship to each other when said pivot arms are parallel, although still then presenting a tapered or angular disposition at the entry roller section, and presenting a completely tapered or angular disposition when said pivot arms are diagonal;  
 conveyor means for conveying the structures on a one-by-one basis into the distal ends of said pivot arms removed from said axes; and  
 control means for actuating said drive means to dispose said pivot arms in their open disposition for entry of each structure and to dispose said pivot arms in their closed disposition when each structure is substantially into and between the open pivot arms; whereby. when said pivot arms are driven to their closed disposition. the contact surfaces initially contact the structure with point contact and then with full line, face-to-face contact as the structure is conveyed through the in-feed device, and whereby, when the contact surfaces become parallel between said central and exit rollers when said pivot arms are parallel, the contact surfaces as they approach the central rollers do so with a relatively gradual taper.  
  10. The device of claim 9, wherein there is further in cluded:  
  1 1 v 1 2 opposed retarding pressure finger means mounted on straps for adjusting the physical location of the dis said distal entry ends projecting inwardly toward tal, operative ends of said straps with respect to said center-line and angularly back toward the said center-line; whereby the retarding pressure of proximal ends of said pivot arms for bearing against the straps can be varied or the straps moved away only the intermediate and end portions of the struc- 5 from the center-line to such an extent that the ture at points removed from the initial contact straps are rendered inoperative point of the moving surfaces with the structure 12. The device of claim 9 wherein said drive means when said pivot arms are in their closed disposition comprise: for retarding the structure against the advancing a reciprocating yoke located along the center-line of force of the contact surfaces in contact with the 10 the device having two slots therein which angularly structure; whereby wrinkles in the material are diverge on opposite sides of said center-line, and eliminated or prevented from forming. wherein said pivot arms includes: 11. The device of claim 10 wherein said pressure finvertical pins which ride in said slots; whereby. ger means are made of straps of resilient, springy matewhen said yoke is reciprocated back and forth along rial and have inherent bias to move away from said censaid center-line, said pivot arms are caused to move tenline, and wherein there is further included: back and forth between their closed and open disset screw adjusting means mounted on said pivot positions.  
 arms and bearing against the operative ends of said