Abstract:
A method and apparatus for the automatic manufacture of flat bottom bags from a substantially continuous supply of a sealable material whereby the material is formed as a bag having a reinforced sealed flat bottom formed by an interior bag forming assembly that is cooperable with a relatively movable bottom platform with sealers and a movable folder assembly that folds the bottom of the bag and removes it from the bag former assembly after a length of the bag is severed from the remainder of the material.

Description:
RELATED APPLICATION 
   This application is an improvement of U.S. Pat. No. 4,230,030, U.S. Pat. No. 4,892,511, U.S. Pat. No. 4,929,224, and U.S. Provisional Patent Application No. 60/715,451. 
   BACKGROUND OF THE INVENTION 
   The present invention relates to a method and apparatus for the high speed manufacture of folded reinforced flat bottom bags of the kind disclosed in U.S. Pat. No. 3,970,241. 
   SUMMARY OF THE INVENTION 
   In U.S. Pat. No. 4,230,030, U.S. Pat. No. 4,929,224, and U.S. Pat. No. 4,892,511 and U.S. Provisional Patent Application No. 60/715,451, there is disclosed an apparatus and method for the manufacture of the reinforced flat bottom bag. The present invention is an improvement upon such prior disclosed method and apparatus in that it teaches a method and apparatus by which the same kind of bags may be manufactured in rapid production manner inexpensively and finished in a folded condition with a more precise arrangement of constructural details that enable the manufacture of bags that are stronger than heretofore made and more attractive in appearance. 
   In the manufacture of the reinforced flat bottom bags, the bottom of the bag is creased and flattened with greater precision and sharpness to produce folds and seals of greater strength than capable of being made heretofore. The present invention is an improvement upon such prior patented disclosures in that it teaches for the first time, a method and apparatus that uses a forming assembly that shapes the flat bottom bag over substantially its whole planar extent by cooperating with bottom platform containing seals and a folder assembly that clamps the bag bottom between them. The cooperation between the former assembly, the bottom platform assembly and the folder assembly produces reinforcing seals of greater strength and extent and further serves to flatten the bottom of the bag into a stronger and more attractive appearance. 
   The above description, as well as further objects, features and advantages of the present invention, will be more fully appreciated by reference to the following detailed description of a presently preferred, but nonetheless illustrative, embodiment in accordance with the present invention when taken in conjunction with the accompanying drawings wherein: 

   
     DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a machine for manufacturing folded flat bottom bags constructed according to the present invention; 
       FIG. 2  is an exploded elevational and schematic view of the machine of  FIG. 1 ; 
       FIGS. 3 ,  3   a .  3   b ,  3   c ,  3   d ,  3   e ,  3   f  are schematic views of the new mandrel for forming the bag as used in the present invention; 
       FIGS. 4 ,  4   a  are views of the bag bottom showing the sealing seams and sealing means thereof; 
       FIG. 5  is a partial perspective view of the details of the bag sealing and cutting mechanism used in the present invention to make a transverse seal; 
       FIG. 6  is a side elevation, partially sectioned of the sealing mechanism shown in  FIG. 5 ; 
       FIG. 7  illustrates schematically, another embodiment of the mechanism; 
       FIG. 8  illustrates the sequence of steps in sealing and cutting the bag; 
       FIGS. 9 and 10  are electrical circuit diagnosis showing the control system for heating and cutting mechanism; 
       FIG. 11  is a side elevational view of the device and cam transmission used in the present invention; 
       FIGS. 12 and 13  are detailed views of the bag ejector assembly employed to remove the completed bag from the machine; 
       FIG. 14  is a view similar to  FIG. 1  showing a modified version of the bag forming apparatus; 
       FIG. 15  is a vertical perspective of the bag forming assemblies and heater-cutter mechanism employed in the apparatus of  FIG. 14 ; 
       FIG. 16  is an enlarged view downwardly into the apparatus showing the detail of  FIG. 15 ; 
       FIG. 17  is an enlarged view of the lower portion of the apparatus of  FIG. 14 ; 
       FIG. 18  a view of the bottom platform with scissors method of operation to draw the bag down to the folding station along with notation of the sealing sections; 
       FIG. 19  a view of mandrel gusset side guides. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to the drawings and more particularly to  FIG. 1 , the apparatus there shown is generally identified by the numeral  10 . It depicts a machine making and folding reinforced flat bottom bags, such as bags of the kind substantially as disclosed in U.S. Pat. No. 3,970,241. The apparatus or machine  10  for making and folding flat bottom bags requires a relatively small floor area because it is disposed generally vertically, extending upwardly from a base  12 . The frame of the apparatus  10  includes a pair of front corner posts  13 , corner posts  14 , intermediate crossbars  15 , and header beams  16 . 
   Integral with the header beam  16  are a pair of pillow blocks  17  providing a journal for a rod  18  on which is a freely rotatably held supply roll of bag material  19  from which the flat bottom bags are to be formed. The supply roll of bag material  19  is substantially continuous in length and may be supplied in the form of a closed sleeve bag material to supply the same with flat faces and inwardly gussetted sides as seen in  FIG. 2 . Hence, it is possible to utilize a supply of bag material  19  that has a sleeve shape and that may or may not be pre-gussetted to eliminate the need to form such gussets at a later time in the present bag forming machine  10 . The supply roll of bag material  19  may be of a heat sealable material. 
   Although it is not necessary that the sides or faces of the machine or apparatus  10  need be denominated as such, it is convenient for purposes of description that the space between the front posts  13  be denominated as the front and that the space between the rear posts  14  be referred to as the rear, while the front to rear spaces between posts  13  and  14  on each side be referred to as the sides left and right, respectively as seen in  FIG. 1 . 
   Mounted also, on the header beams  16 , is a second pair of pillow blocks  20  in which journalled an idler roll rod  21 , Preferably, the roller rod  21  is located slightly to the rear of the center line between the front and rear posts  13  and  14  respectively, so that the bag material  19  can roll therein and depend vertically therefrom. In this manner, the bag material  19  be made to freely pass sleeve-like over a bag forming assembly generally depicted by  22 , wherein, in a cyclic and continuous manner, the material is pulled down, its leading section formed into a flat bottomed bag, sealed, cut and removed. 
   The bag forming assembly  22  as seen more fully in  FIGS. 3 ,  3   a ,  3   b ,  3   c ,  3   d ,  3   e ,  3   f  comprises an upper mandrel, generally depicted by the numeral  23  adapted to guide and at the same time pre-open and shape the tubular supply of bag material  19 , and a lower mandrel generally depicted by the number  24  which is caused to move between a raised inoperative position and a lower operative position in which the bottom of the bag is formed. The upper and lower mandrel sections are mounted on opposite sides of a central post  25 , the upper mandrel section  23  being non-movable, while the lower mandrel section  24  is raiseable and lowerable as will be seen hereinafter. To insure additional guidance for the material and mandrel, right and left hand guide plates  27  are provided. 
   The upper mandrel section  23  as seen in  FIGS. 2 and 3  include a pair of flat plates, hinged to the center post  25 , generally parallel to the central plane of the vertically depending bag material  19 . The longer front and back flat plates  26 , and side portions  120  have cutout sections to allow the sealers mounted in the bottom platform to incorporate into the bag itself and seal the bag at these sections. The plates  26  are slightly sprung outward along their lower edges to cause the material to correspondingly spread out. Mounted in the plane of the vertically depending bag material  19  to either side of the material are a pair of gusset mandrel side plates  27  adapted to enter into the gussets of the bag and thus stabilize the bag material as the flat plates  26  spring the material outward. 
   The lower mandrel section comprises a sleeve  28  slidably mounted over a central post  25 . Fixed on the sleeve  28  is a collar  29  against which a pair of lateral extending arms  30  hinged at their upper end  31  movably slide. At the lowered end of each of the arms  30  there is a pivotably mounted rectangular plate  32 . As the collar  29  is caused to be raised or lowered relative to the center post  25  by movement, the arms  30  cause the plates  32  to move between a vertical inoperative position shown in dotted lines, the horizontal operative position shown in full lines and extending perpendicular to the plane of the drawing paper  FIG. 3   a  by which it fully stretches the bag outward transverse to its width to form the partially completed flat bottom. 
   Serving to raise and lower movable section  24  of the mandrel and simultaneous pull or draw down the bag material  19  are an upper roller system, generally depicted by  33  and a lower roller system generally depicted by  34 . Each roller set  33  and  34  comprises two pairs of inner rollers  35  and a pair of outer rollers  36  so that the flat sides of the bag material  19  is capable of being threaded therebetween as seen in  FIGS. 2 and 3   c  so as to be firmly held for the bag forming process yet being capable of being pulled down through the upper roller set  33  by the lower roller set  34 . 
   The lower mandrel  24  consists of two longer plates  26  one of each side and two side plates  120 . The two longer plates and the two side plates, one group on each side, have sections cut-out to accommodate the sealers  135  mounted on the bottom platform  130  that allows for the sealing of the face and bottom of the bag on each face and back at the edges as well as sealing the side gusset bottom to the edge of the bottom of the bag as it is joined at this juncture, see  54  in  FIG. 4 . Therein the bag is sealed at the side edge juncture where the gusset side meets the bottom fabric, rather than the bag bottom, as previous described in said prior related patents. 
   The upper mandrel  23  incorporates a pair of flat disc guides  27  to accommodate the separate guides mounted on frame  41  generally parallel to the external plane of the bag material  19 . These separate external guides can be adjusted so as to keep the bag material  19  and mandrel  24  in place during the manufacturing cycle. 
   As seen in  FIGS. 1 and 2 , the roller  35  and  36  of the upper roller set  33  are journalled on a transverse carriage  37  slideably guided over a pair of vertical rods  38  respectively fixed between the base  12  and cross beams  15  on the left and right side of the apparatus. The carriage  37  is fixed at each of its ends on a piston rod  39  actuable by a hydraulic/pneumatic cylinder  40 . The transverse carriage  37  is adapted to be raised and lowered by the hydraulic/pneumatic cylinder  40  fixed at one end of the base  12 . The piston rod  39  is secured by a bolt  41  to the carriage  37 . Although two such piston cylinder arrangements are shown, only one may be really essential and thus used. 
   The lower roller set  34  is connected to the carriage  37  for relative movement therewith, by a second set of hydraulic/pneumatic cylinders  40  and extending piston rods  43 . The piston rods  43  are each fixed to a box journal  44  to which only the outer rollers  36  of the lower roller set  34  are journalled. The inner set of rollers  35  is fixed to the sleeve  28 , to be conjointly moveable along the post  25 . 
   It will thus be apparent that the entire lower section of the mandrel assembly  24  including the upper rollers  33  and the lower rollers  34  is movable by actuation of the piston rods  39  while the lower roller section  34  is movable relative to the upper roller section  33  by the independent actuation of the cylinders  42 . Operation of the cylinder  40  and  42  in timed cylindrical sequence can be readily effected by known techniques combining suitable connection to a source of hydraulic/pneumatic fluid from the source to the cylinders and in return, as well as timers, relays and the like, to effect the necessary sequence. Such known techniques may be conventionally adopted here. 
   By lowering the entire mandrel assembly  24 , the roller sets  33  and  34  pull down the bag material  19  from the supply roll. The degree of pull-down can be varied by modifying the piston strokes of cylinders  40  and  42 , thus the ultimate size of the bag is determined. Further, by separate and independent lowering of the lower roller assembly  34 , the sleeve  28  on which the collar  29  is fixed, will cause the hinged arms  30  and plates  32  shown in  FIG. 3 , to flair outwardly into the horizontal position to thereby open the bag material and initiate the formation of the flat bottom. 
   Located at a position below the lower mandrel assembly  24  and above the extreme position wherein the mandrel mechanism may be lowered by actuation of both cylinders  40  and  42  is a heat sealer/cutter mechanism  50 . Prior to the flaring of the bag by operation of the cylinders  40  and  42  the mechanism shown in  FIG. 3 , this sealer/cutter mechanism  50  is caused to be operated to form as seen in  FIGS. 4   a  and  4   b , a transverse seal  51  in the bag material  19  and to cut any preceding excess material or precedingly formed bag from the supply of material. The transverse seal  51  thus closes the bag material  19  just below the plates  26  prior to forming the flat bottom, so that upon further movement of the lower roller assembly  34 , the plates  26  push against the closed bottom. 
   It is this closure of the bag material that, in fact, the cylinders  40  and  42  are sequentially operated. Because the bag is thus sealed, the plates  26  of the movable mandrel section cause the material not only to flare but also to move further downwardly. Spaced below the sealer/cutter assembly  50  by a distance equal to the distance of the ultimate bag height is a platform  130  against which the flared mandrel plates  26  push the closed end of the bag material, producing folded portions  131 . Simultaneously, the bottom platform has risen up to meet the sealed open bag where the side sealers and long transverse seals are activated to produce the seals as described in the above paragraphs. The sealing mechanism is hinged and pivots to press against the sealing spaces and is well known in the art and is not described here. In this manner, the bag is completed. Immediately thereafter the completed bag is released at its upper end from the bag material  19  by activation of the sealer/cutter mechanism  50 , which has been completed, but simultaneously form the closure seal  51  for the next succeeding bag. The bottom platform  130 , mounted on a scissors like mechanism  125 , see  FIG. 18  returns to the bottom station grasping or pulling the bag and sealing the bag down to the bottom platform original position. The longer transverse and side sealers  135  release their pressure. The mandrel  24  returns to its upward station ready for the operation of cutting, sealing and opening the next bag. 
   The completed bag is removed from the platform  130  by an ejector assembly generally depicted by numeral,  56  as shown in  FIG. 1  and in detail, in  FIG. 12  comprising two pair of articulated arms  57  and  57   a  pivoted at the their upper ends  58  to a header beam  16  and depending downward at the rear of the frame. The ejector assembly  115  is provided with a frame  59  having a pivotable bottom plate  59   a  extending forwardly and adapted to enter below the flat bottom bag remaining on platform  130 , and an upper plate  60  pivotally mounted on the frame  59  which closes jaw-like over the flat bottom plate  59   a . The completed bag bottom lying flat against the plate  130  is thereby capable of being grasped between plates  59   a  and  60  which thus flattens due to the action of the plates. Rubber gripping bumpers are located on the upper plate  60  to insure holding of the bag. The plates  59   a  and  60  are pivoted by operation of hydraulic/pneumatic actuators  59   b  and  60   b  respectively. The arms  57  are then swung outwardly from the machine frame carrying with it the bag, which then slides in the direction of the arrow between the plates  130  and a roller  61   FIG. 1  to flatten itself as it is withdrawn. The plates  59   a  and  60  are then opened allowing bag to be stacked one on top of the other on a pallet to the rear of the frame. Because of the arms  57  and  57   a , the frame  59  remains horizontal during its entire movement. 
   The ejector assembly is actuated via vertical lever arm  62  extending from the upper end of the ejector arm  57  to the base  12  where it is provided, as seen in  FIG. 11 , with a cam follower C 1  riding on a cam C rotatable by connection to a power transmission shaft S connected to a motor M. The cam C also functions to operate several micro switches capable of regulating the function of the solenoids and valves operating the actuators  59   b  and  60   b  respectively. 
   The heat sealer/cutter mechanism  50  as seen in detail in  FIGS. 5 and 6  comprises a back-up assembly  63  and a heater assembly  64 . Both of these assemblies are mounted on side support rails  65  (or cylindrical bars) fastened to the machine frame so as to be easily slideable inwardly and outwardly relative to each other on either side of the plane of the bag material  19 , see  FIGS. 1 and 2 . Each of the back-up assembly  63  and heater assembly  64  are actuated by piston cylinder actuators  66  and  67  respectively, the cylinders being fixed to the frame of the housing on opposite sides of the machine frame. Each of the cylinders is provided with a return spring  68 ,  FIG. 6  to insure immediate return of the associated piston upon release of the cylinder actuation. While each of the assemblies  63  and  64  are shown here with two actuators, it will be clear from the later description, that only one may be necessary. Both the back-up assembly  63  and the heater assembly  64  are formed of rectilinear box-like hollow members. The back-up assembly  63  is provided with a hard rubber face  69  to dampen the shock when it meets and abuts the heater assembly  64  and to resiliently squeeze the folded bag material together. The heater assembly  64  contains one or more heating elements  70 ,  FIG. 6  arranged along the length of the face thereof connected in a conventional manner through terminal  71  to a source of electrical current. Preferably the heating elements  70  are mounted on or are constituted by elongated bar  72 . In any event, they are reciprocable perpendicularly to the plane of the face so that the elements may be moved into and out of engagement with the faces of the bag material  19 , independent of the movement of the back-up member  63  or the heater assembly  64  as a whole. The heater elements  70  or the bar  72  as whole, is moveable by hydraulic/pneumatic piston cylinder actuators  73 , the cylinder being mounted on the heater assembly  64  and the piston passing into and through the heater assembly  64 . 
   Passing through the heater assembly  64  from the rear toward the front, are a plurality of air lines  74 ,  FIG. 5  connected by a manifold (not shown) via one or more air lines  75  to a source of air, preferably under pressure, regulated by one or more valves  76 ,  FIG. 5 . The air lines  74  communicate with vertical air holes  77 ,  FIG. 6 , set back from the face of the heater assembly. The vertical air holes  77  are open at each end to the atmosphere. Small bleeder holes  78  may also be made in the face. Application of air into the heater assembly is made simultaneously with the heating operation, as well as before and after the elements are provided with current. In this manner, the face of the heater assembly is constantly cooled; avoiding overheating, burning of the bag material, sticking of the bag material to the heater assembly, or the rubber back up pad, or burning of the rubber pad itself. As a result, the closing of the bag can be cycled at a very high rate. 
   The forward thrust of the back-up member and the heater assembly is sensed by a limit switch  79  which also initiates the cycle return of the heater assembly, etc. 
   Mounted below the forward edge of the heater assembly  64  is a cutter blade  80  having its sharp edge along its lower face. A counter blade  81  is similarly mounted below the forward edge of the back-up member  63 . The counter has its sharp edge on its upper face and is adapted to slide below the cutter blade  80 . Thus, the bag material can be simultaneously cut and severed from the material roll together with the formation of the bottom seal  51  by action of movement of the back-up and heater assemblies  63  and  64 . 
   A modified version of the heater/cutter mechanism  50  is schematically shown in  FIG. 7  using the same reference numerals for similarly functioning elements. It is this construction of, the heater assembly  64  comprising of a hollow rectilinear chamber  82  open at its forward face  83  and having vertical bleed holes  78  in its upper wall only. The air is fed via a nozzle  84  directly into the chamber  82 . The heater elements  70  are mounted on a solid strip  85 , which is actuated by the piston in cylinder  73 . 
     FIG. 8  illustrates schematically the sequence of five steps necessary to simultaneously heat, seal and sever the completed bag using the embodiment of the heater/cutter mechanism  50 . Step  1  shows the position of the back-up member  63  and the heating assembly  64  at rest. In Step  2  the back-up assembly  63  and the heating assembly  64  are moved into abutment by operation of their actuators  66  and  67 , thus clamping the bag material firmly therebetween. Thereafter, in Step  3 , the actuator  73  is operated causing the heating element  70  to move forwardly and engage the bag material, thus forming the seal. In Step  4 , the heating element  70  is withdrawn followed by Step  5  which returns the back-up assembly and heating assembly to the initial rest position, whereupon, simultaneously the bottom platform  130  with its sealing members  135  has risen to meet the open squared-off long transverse sealed bag. The sealing members on the bottom platform are engaged, seal, and grasp the bag pulling it down to the folding station. The art of sealing procedure is previously described by the aforementioned sealing apparatus. The bottom platform returns to its original base  12  position. The sealers  135  are released and the bag folding mechanism  FIG. 12  is engaged to fold the bag and make the bag ready for release. At the same time, the mandrel has already returned to its upward position ready to cut and seal and present the next bag for sealing. 
     FIGS. 9 and 10  show the electric circuit and hydraulic/pneumatic circuits for accomplishing the steps as shown in  FIG. 8 . In  FIG. 11  the drive motor and belt and cam transmission is illustrated. The cam C and separate micro switches following this cam are arranged so as to provide the pull down cutting and heating as well as the control of the remaining elements of the machine. During operation the position of the heating and sealing assemblies are such that they are spaced from each other, allowing the bag material to be pulled down between them, and flared by operation of the lower forming mandrel  24  which also passes within the back-up and heating assemblies  63  and  64 . Once the bag bottom is flattened against the bottom risen platform  130  the side gusset fingers  55  engage the bag and edge clamp means  55   a ,  FIG. 2  engage the bag bottom, thus holding the bag firming to allow the lower mandrel  24  with its cut-out plates to be raised. Once the lower mandrel is raised, the heater assembly  135  is free to seal the next bag bottom and sever the bag. In essence, the forming assembly comprising the upper and lower mandrels is actuated to create the succeeding bag. 
   The high speed at which the heater apparatus works and the fact that the air flows over the heating strip negates the requirement to use Teflon covers or other cover means for the back-up assembly. Both the back up and the heater assembly move toward the center. The bag material is immediately cut by the cutting blades and held and gripped generally between the two assemblies. When the heating element brought into contact with the gussetted bag material by the extension of the cylinder, this contact is a very short duration, and with the pressure of the cooling air on deactivation of the cylinder, the sealing element is easily withdrawn from the bag material and does not stick to it. 
   In the modified apparatus shown in  FIGS. 14 and 17 , like elements are depicted with the same numerals as heretofore and unless specified, function in the same way. 
   Differing from the earlier version, in that of  FIG. 14 , the bag material  19  supply roll is mounted on a roller  18  journalled at each end in a rearwardly extending bracket arm  100 , integral with the cross bars  15 . This permits easier loading of new bag material rolls. The headers  16  extend pyramidally upward and the bag material  19  passes over and idler roller  101  journalled on a vertical standard  102  integrally fix to the headers  16 . The material passes downwardly over the bag forming apparatus  22 , which in general, comprises the upper and lower mandrel assemblies  23  and  24  as described earlier. Here, however, the roller sets  33  and  34  are mounted on associated carriage blocks  103  and  104  respectively, on each of the lateral sides of the machine. The lower blocks  104  holding roller sets  34  slides reciprocally on a pair of vertical rods  105  and is actuated to move upwardly and downwardly through the articulated linkage  106  connected to the cam shaft mounted on base  12 , being the cam shaft shown in  FIG. 11 . 
   The upper carriage block  103  carrying the roller set  33  rests on the lower carriage block  104 , but is slightly offset inwardly therefrom. In this manner, movement of the lower carriage block  104  conjointly moves the upper carriage block  103 . The necessary relative movement between the two roller sets  33  and  34 , required to permit the lower mandrel to move the bag material down, is effected by providing a vertical post  107  beneath the upper carriage block  103 . The post  107  is mounted on an adjustable arm  108  so that the upper end  109  of the post  107  can be located and given height to arrest the downward movement of the upper carriage block  103  to meet the upward traveling bottom platform station  12 . Then, adjustable arm  108  will rotate and cause bottom platform to return to its original position. Another difference seen in  FIG. 14  as well as in  FIGS. 15 and 16 , is the flaring plate of the lower mandrel assembly, which is shown here as an elongated member  110 . 
   Turning to  FIG. 17 , additional detail is shown with regard to the platform  130 , see  FIG. 18 , and the clamping members for holding the bag in place, allowing the lower mandrel assembly to be raised before the bottom platform lowers the bag to the ejector assembly  115  removing the bag. Here, a transversely extending arm  111  fixed at each end to a pivoted arm  112 , is mounted on the side of the platform  130  adjacent to the ejector assembly  115 . The arm  112  is pivoted at its center  113  and fixed to a horizontal strip  114  which is connected to a vertical rod riding on a cam connected to the drive cam C described earlier so that as the horizontal strip  114  is raised and lowered, arm  112  is swung toward or away from the platform  130 . The rod  111  is thus caused to clamp and release the bag bottom to the platform, functioning as the clamp  55   a  shown in  FIG. 2 , which it can easily replace, if desired. On the opposite side of the platform, there is similarly mounted an elongated transverse roller  115  on a pair of end arms  116  articulately connected to follow another cam connected to the drive cam, in a conventional manner. The clamp arm  111  is held against the bag until such time as the ejector assembly  115  grasps the bag as previously described and pulls the bag causing the bag to fall on to platform  130  being pulled beneath the clamp arm  111 . Once this occurs, the arm  111  raises slightly and the roller  115  is caused to swing onto the fallen bag exerting sufficient roller pressure to flatten the entire bag, as it is being pulled. Once the bag is removed from the platform  130 , the arm  111  and roller  115  are withdrawn, preparing the platform for receipt of the next bag in the cycle. 
   As seen also in  FIG. 17 , the gusset fingers  55  are articulately connected to a scissors-like linkage  117  operated also by connection to cam so that it will, in the necessary timed sequence of operation, cause the tucking inward of the gusset and its hold-down prior to removal of the lower mandrel  24 . 
   Each of these modifications and elements shown in  FIGS. 14-17  could be equally adopted and used in the embodiment of  FIGS. 1-13  replacing or augmenting the similarly functioning elements. 
   Various modifications, changes, and embodiments have been disclosed, and others will be apparent to those skilled in the art. Accordingly, it is intended that the disclosure be taken as illustrative and not limiting of the scope of the invention.