VACUUM ADVANCE SYSTEM FOR HIGH SPEED CONTACT SEALER FOR FORMING A FLAT FILM INTO A TUBE

Abstract: Apparatus for the manufacture of a length of closed film product from a length of flexible, flat film (12) is arranged on a support frame which supports a film forming collar (10) that is connected to a tubular member (24) for receipt of the formed tubular film. A heat sealer (26) engages overlapping elongate edges of the film are provided along the tubular member and a vacuum transport assembly is positioned on each side of the tubular member for moving and transporting the tubular film along the tubular member.

Description: VACUUM ADVANCE SYSTEM FOR HIGH SPEED CONTACT SEALER FOR FORMING A FLAT FILM INTO A TUBE BACKGROUND OF THE INVENTION This invention relates to an improved mechanism for transporting flexible film which is formed from a flat sheet into a tubular form. More specifically, the invention relates to the apparatus for transporting the formed tube of film when the edges of the tube are overlapped are being and sealed by a heating mechanism for example. In U.S. Patent No. 5,085,036, applicant's assignee disclosed a mechanism which is used to form a flat sheet of flexible film into a tubular shape and for transporting that tubular shape along a cylindrical tube as the overlapping edges of the film are sealed or adhered one to the other. The mechanism is especially useful in the food packaging arts wherein the tubular flexible film, upon being formed and sealed, is filled with a food product in a continuous operation. Patent No. 5,085,036 is therefore incorporated herewith by reference. In Patent No. 5,085,036, the formed film is transported along a tubular mandrel by means of an endless belt or endless series of belts which f rictionally engage the film and transport it along the tubular member as another endless belt which is heated, heat seals the overlapping edges of the film. The described apparatus is extremely useful and can operate at very high speeds. However, even higher speeds are often necessary in the food packaging arts. Thus, there has remained the need to develop a system for transporting the film which has been formed into the shape of a tube rapidly. The present invention provides a mechanism to accomplish this goal and objective. SUMMARY OF THE INVENTION Briefly the present invention comprises improved apparatus for the manufacture of a length of closed, tubular film from a length of flexible, flat film. The apparatus is supported on a support frame. The frame supports a film forming collar having an inlet side for receipt of a length or sheet of flat, flexible ilm. The collar is designed to fold the film into a tubular shape with opposite elongate edges of the film overlapping one another when discharged from the collar at the discharge end thereof. The tubular formed film is then guided onto a tubular member which is also supported by the frame. The tubular member preferably includes an elongated rib extending along the length thereof in the direction of film travel and aligned to support the overlapping edges. Means for adhering the overlapping, elongate edges of the film positioned on the rib are provided. In a preferred embodiment, the means for adhering the overlapping elongate edges comprise a heated, endless band which engages the film as it slides over the described rib. Vacuum transport means are also supported on the frame and are mounted parallel to the tubular member. The vacuum transport means are designed to grip the film as it is discharged from the forming collar and to transport that film along the generally cylindrical tubular member. Preferably a first vacuum assembly is positioned on one side of the rib and a second vacuum assembly is positioned on the opposite side of the rib so that the formed tubular film may be uniformly and easily transported. Thus, the vacuum transport means are preferably separated by approximately 180 degrees about the circumference of the tubular member. In the most preferred embodiment, the vacuum transport means comprise an endless belt with apertures therethrough. The apertures slide over a manifold and, in particular, manifold passages which are connected to a source of vacuum. The film is thus gripped effectively by the endless belt which attaches itself to the film by virtue of the vacuum and transports the film as the belt moves synchronously with the means for adhering the overlapping edges defining the seam of the formed film tube. Thus is it is an object of the invention to provide an improved apparatus for high speed formation of a flat, flexible film into a tubular form. A further object of the invention is provide a mechanism for transport of the formed tubular film more quickly than prior art mechanisms. Yet another object of the invention is to provide an improved vacuum transport means which easily adheres and grips the formed film and transports the formed film in a manner which tends to preserve the integrity of the formed film. Yet a further object of the invention is to provide an improved apparatus for the manufacture of a length of closed film product from a length of flexible, flat film which is economical, easy to manufacture and repair, and which has a high degree of efficiency with respect to manufacture of the closed film product. These and other objects, advantages and features of the invention will be set forth in the detailed description which follows. BRIEF DESCRIPTION OF THE DRAWING In the detailed description which follows, reference will be made to the drawing comprised of the following figures: FIGURE 1 is a perspective view illustrating the improved construction of the present invention; and FIGURE 2 is a cross-sectional view illustrating the manner of operation of the improved construction of the present invention and further illustrating the particular construction of the manifold block and endless belt which provide a vacuum transport of the tubular film product. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the figures and in particular Figure 1, there is illustrated the apparatus of the present invention which is a variation of the apparatus depicted in U.S. Patent No. 5,085,036. Thus, as in U.S. Patent No. 5,085,036, the assembly is mounted on a frame which supports a film forming collar 10. A flexible sheet of film 12 is provided from a roll and is guided by various adjustable rollers 14, for example, over the film forming collar 10. The film 12 then is formed from the flat sheet into a tubular shape with edges 16 and 18 of the film which extend in the elongate direction overlapping one another. The film 12 thus enters an inlet side 20 of the collar 10 and is discharged at an outlet side 22 where it fits over an elongate tube 24. The assembly is, of course,' supported on a frame. The formed film 12, in the tubular shape, passes over the cylinder or tube 24, and the overlapping edges 16 and 18, which define a seam, are engaged by " a heated endless band 26 which passes over a heater bar 28 and rollers 30 and 32 at each end thereof. The band 26 is impinged directly against the seam defined by the overlapping edges 16 and 18 shown in Figure 2. The heater bar 28 thus effects sealing of the seam. Other means such as an adhesive applicator and roller or other means may be utilized to effect sealing of the overlapping edges 16 and 18. Note, as shown in Figure 2, that the tubular member 24 includes a generally planar elongate rib 34 which extends along the length of the tube 24 and defines a platform upon which the overlapping edges 16 and 18 of the film 12 will ride. The heated band 26 thus impinges against the rib 34 with the overlapping edges 16 and 18 therebetween to more efficiently effect a heat seal. The rib 34 may be made from a polytetrachloroethylene material or some other similar material to enhance the sealing operation. Preferably the rib 34 has a flat surface which cooperates with the flat surface associated with the band 26 to further enhance the sealing operation. The heated band 26 engages the overlapping edges 16 and 18 upstream from the transport apparatus which is described in more detail below. Positioned on opposite sides of the tube 24, approximately 180 degrees from each other and 90 degrees from the heated band 26 are vacuum advance mechanisms 36, 38. The vacuum advance mechanism 36 is positioned on one side of the tube 26 is substantially and is identical in function and operation to the vacuum advance system 38 on the opposite side of the tube 24. Vacuum advance mecahnism 36 includes an endless flexible belt 40 which fits over end spools or rollers 42 and 44 mounted on a frame or support. One of the rollers 42 or 44 is a driven roller and may include sprocket teeth which fit through spaced apertures 46 in the endless flexible belt 40. Alternatively the belt 40 fictionally engages the spools 42 and 44 and is driven thereby. A manifold block 48 is positioned and supported on the frame intermediate the spools 42 and 44. A vacuum source 50 connects via a line 52 with an internal vacuum chamber 54 associated with the manifold block 48. The vacuum chamber 54 includes an elongate slot 56 in the block 48. The slot 56 is in opposed relation to the apertures 46 which pass over the chamber 54 and provide for a passageway to the chamber 54. The apertures 46 thus define vacuum passages which are in opposed relation to film 12 which slides over the tube or tubular member 24. As shown in Figure 2, the passages 46 thus cause the" film 12 to effectively be gripped by or adhere to the belt 40 and to be moved or transported by movement of the belt 40 on the rollers 42 and 44. Importantly the rollers 42, 44 associated with the transport assembly 36 are synchronized with sprockets 62 and 64 associated with the transport assembly 38. Further, the heated band 26 is synchronized with the transport assemblies 36 and 38 so that all the band 26 and belts 40 move at substantially the same speed. In this manner, the transport assemblies 36 and 38 move to transport the film 12 over the tubular member 34. The band 26 moves to effect the sealing operation of the overlapped edges 16 and 18. The transport assemblies 36 and 38 provide for engagement of the film 12 downstream from engagement of the band 26 with the overlapping edges 16 and 18. This is the preferred arrangement; however, the invention contemplates that the heated band 26 may engage the overlapped edges 16 and 18 at the same time as the vacuum manifold transport assemblies 36, 38, prior thereto or subsequent thereto. With the construction of the invention as depicted in the drawings and as described, the speed of movement of the film over the tubular member 24 may be significantly increased and the output of the apparatus may thus be significantly increased compared, for example, to the construction depicted in U.S. Patent No.5,085,636. Additionally, with the construction of the invention, it is possible to shorten the length or run associated with the assemblies 36 and 38 as well as the run associated with the heater band 26. Further, the heater band 26 may be operated at a higher temperature since the duration of the band 26 in contact with the overlapping edges 16 and 18 is shortened. With the subject matter of the invention, therefore, a fewer number of parts having a smaller configuration is possible relative to the prior art construction. Further, with the present invention it is possible to adjust the vacuum derived from the vacuum source 50 and thereby adjust and accommodate various types of flexible film material moving at various speeds and having various overlapping configurations. Because there is no frictional engagement of the endless belt 40, the likelihood of a tear in the formed tubular material is greatly reduced. The improved construction of the present invention therefore enables the manufacture of an improved product having a higher degree of manufacturing acceptance. Rejected tubular material is less likely with the construction of the invention. Thus, while there has been set forth a preferred embodiment of the invention, it is to be understood that the invention is to be limited only by the following claims and their equivalents.

Claims: CLAIMS WHAT IS CLAIMED IS: 1. Apparatus for the manufacture of a length of closed film product from a length of a flexible flat film comprising, in combination: (a) a support frame; (b) a film forming collar having an inlet side for receipt of a length of flat, flexible film and for folding the film into a tubular shape with opposite elongate edges of the film overlapping, said collar also having a discharge end; (c) a tubular member supported by the frame for receiving the tubular shaped film with overlapping edges f om the discharge end of the collar; (d) means for adhering the overlapping elongate edges positioned along the tubular member by engaging the seam defined by the overlapping edges as the film traverses the tubular member; and- (e) vacuum transport means for transporting the tubular film along the tubular member, said vacuum transport means including at least one continuously moving suction means in opposed relation to the tubular member and moveable along a length of the member to thereby attach to the film and transport the film coincident with operation of the means for adhering, said suction means comprising a suction manifold extending along the tubular member, rollers at the opposite ends of the manifold, and an endless belt having apertures therethrough fitted over the rollers and slidable over the mani old, said belt positioned in opposed relation to the pathway of the film along the tubular member between the manifold and the tubular member, said manifold having a vacuum passage in communication therewith, one of said rollers de ining a drive sprocket which engages the said apertures of the belt in sequential order as the belt passes over the drive sprocket to thereby drive the belt along the manifold while vacuum effected through the said apertures opposed to the manifold simultaneously holds ilm against the belt whereby the film is transported along the tubular member. 2. The apparatus of claim 1 wherein the vacuum transport means comprise first and second transport assemblies on opposite sides of the tubular member. 3. The apparatus of claim 1 wherein the means for adhering includes heating means positioned in opposed relation to the tubular member, and wherein the tubular member includes a longitudinal rib projecting from the tubular member and aligned with the seam and the means for adhering. 4. The apparatus of claim 2 wherein the manifold block includes an elongate slot vacuum passage along a partial run of the belt opposed to the tube. 5. The apparatus of claim 1 wherein the heating means comprise an endless band synchronized to move substantially simultaneously at the speed of the endless vacuum advance belt.

Inventors: CHEN KUO-RAID GRANT, MISNER RAYMOND H, RICHARDSON BERNARD D, WINDHAM ELBERT P, CHEN, KUO-RAID, GRANT, MISNER, RAYMOND, H., RICHARDSON, BERNARD, D., WINDHAM, ELBERT, P.
Applicants: CAPITAL FORMATION INC, DELAWARE CAPITAL FORMATION, INC.
Application year: 1993
Main classification: B29C53
IPC codes: B29C31, B29C53, B29L23, B65G15, B65G21