Patent GB-816931-A (GB)
Title: Method and apparatus for producing tubing
IPC: B65B51/30
Filed: 1957-03-29
Abstract: 816,931. Making tubes. UNION CARBIDE CORPORATION. March 29, 1957 [April 18, 1956], No. 10316/57. Class 99(2). [Also in Group VIII] In a method of producing tubing from thermoplastic material by heat-sealing two coextensive plies of the material along parallel axes, the heat seals are disposed so as to define a number of parallel unobstructed pockets and have an unsealed portion defining the mid-portion of each of the seams; if desired, the plies are slit at substantially the mid-point of the unsealed portion of the seam so as to provide a number of thermoplastic tubes of predetermined width. The thermoplastic material may be cellulose acetate, cellulose acetate butyrate, ethyl cellulose, methyl methacrylate polymer, nylon, polystyrene, polyvinyl formal-acetate butyral, copnlvmers of vinyl chloride and vinyl acetate such as Vinylite (Registered Trade Mark), polyvinyl chloride such as Geon (Registered Trade Mark), copolymers of vinyl chloride and vinylidene chloride such as Saran (Registered Trade Mark), or polyethylene. The properties of the material may be modified by incorporating plasticizers, fillers, colouring agents, heat stabilizers or anti-oxidents. As shown, the annular die 6 of an extruder 4 forms a seamless tube 8 which is inflated by air and withdrawn in a vertical direction from the die by rotatable squeeze rolls 10, 12 either or both of which are driven, the collapsed 2-ply ribbon 24 passing over a guide roll 26, which may be heated, or heating means may be disposed between that roll and the rolls 10, 12, to a sealing station 28. The latter comprises a number of horizontally aligned pads 30, Figs. 4, 5, over which the ribbon 24 slidably moves, and a number of cooperating heat-sealing units 32. The pads are formed from micarta, steel, wood or Bakelite (Registered Trade Mark) and are adjustable transversely of the path of travel of the ribbon, there being pins 52, projecting from the rear of the pads, which slidably engage in a slot 54 in a channel 46; the pads are secured in position by spring-loaded bolts 56 screwed into the pads. Each heat-sealing unit is of aluminium, brass or stainless steel and provided with an aperture 42 for reception of a cartridge heater 44 wired in series with a rheostat whereby the temperature of a pair of projecting arcuate runners 38 is regulated ; the runners are disposed opposite concave recesses 36 in the pads 30. The units are fixed to heat-resistant mountings 62 provided with pins 70 slidably engageable with a slot 72 in a support channel 48 and adjustable transversely of the path of travel of the ribbon, the units being secured in position by spring-loaded bolts 76 screwed into the mountings. The channel 48 is movable relative to the channel 46 and is secured to a frame 80 pivoted on a shaft 82 and pulled towards the channel 46 by a spring 86, the desired spacing between the channels being obtained by screws 92. Upon emergence from the station 28, the ribbon has a number of longitudinally extending pockets defined by seams each comprising double seals 98, Fig. 11, and the ribbon may be engaged by blades 102 secured on a shaft 106 so as to be slit into a number of separate tubing members as shown in Fig. 12. The tubing or tubings, after engagement with a roll 119 and guide rolls 120, 122, are wound onto torque-compensated reels 128, 130. Specifications 654,550 and 716,160 [both in Group IV(a)] are referred to.