Patent GB-800842-A (GB)
Title: Improvements in and relating to embossing apparatus
Inventor: SUPITILOV MICHAEL CHARLES
IPC: B29D17/00
Filed: 1955-11-30
Abstract: 800,842. Moulding screw threads on polyamide sleeves &c. DUKANE CORPORATION. Nov. 30, 1955, No. 34290/55. Class 87(2). [Also in Group XVI] An apparatus for seaming and embossing a strip or embossing a sleeve of thermoplastic material to form an embossed sleeve, comprises a pair of opposed cylindrical surfaces, one of the surfaces being a rigid cylindrical die surface while the other surface is deformable under pressure so as to be capable of urging the thermoplastic material against the die surface, means for applying pressure to the other surface to deform same and means for heating the thermoplastic material to soften it during seaming and embossing or embossing and means for cooling the same after such operations, the other surface being formed of polytetrafluoroethylene, polytrifluoro-chloroethylene or silicone rubber. As shown a strip or sleeve 43, Fig. 2, of plastic material, e.g., nylon, surrounds a resilient cylindrical plug 34 of natural or synthetic rubber, e.g., copolymers of butadiene and acrylonitrile or butadiene and styrene. Alternatively, the plug may be of synthetic plastic material, e.g., polytetrafluoroethylene or polytrifluorochloroethylene or a silicone rubber. A cylindrical member 20 surrounding the plug 34 has a bore formed as a die of the pattern to be embossed, e.g., a shallow thread. Pipes 26 and 27 supply steam and water respectively to an annular space formed by the member 20 and a spaced apart sleeve 19 fitted between plates 16 and 17. A plunger 38 is pressed downwardly by a steel block 11 guided by a post 32 and carried by a ram 10 to cause the plug to expand radially towards the die surface. The plastic strip or sleeve 43 surrounding the plug, having been heated by steam in the space 24, is forced into engagement with the die and thereby embossed. The steam supply to the pipe 26 is then turned off and water is supplied to the space 24 to. cool the strip or sleeve 43 before separation from the die, pressure being maintained on the plunger 38. The embossed sleeve 43 may then be detached from the die surface, after raising the ram 10 and plunger 38. If desired, a thin sleeve 40 of polytetrafluoroethylene, polytrifluorochloroethylene or silicone rubber may be provided between the sleeve 43 and plug 34 to to prevent the sleeve 43 adhering to the plug during embossing. When the material to be embossed is in strip form the ends of the strip are welded during the embossing operation to form a sleeve. As shown in Fig. 4, the sleeve is embossed with a square thread 45 which is subsequently coated with magnetic material and used for sound recording. In a modification, Fig. 5, the die surface is formed on the exterior of a sleeve and is surrounded by an annular sleeve which forces the plastic material into contact with the die surface when the annular sleeve is axially compressed ; the inside of the sleeve carrying the die is heated by steam and then cooled by water. In a further modification, the resilient plug, Fig. 7, is secured to a vertically reciprocable ram such that the plug is expanded radially upon engagement with a plate equivalent to the plate 16, Fig. 2. In a further embodiment, Fig. 9, the resilient plug is hollow and is expanded by fluid pressure to force a surrounding plastic strip into engagement with a surrounding die. In a further embodiment a flexible sleeve 112, Fig. 10, is secured to plates 100, 101 by clamping plates 117, 118 and 107, 108 respectively. A flexible hose 124 supplies liquid or gas under pressure to the interior of the sleeve 112, such that the sleeve presses the plastic sleeve 43 into engagement with a die 103 heated and then cooled by steam and water supplied to a surrounding annular chamber. In a further modification, Fig. 11, the flexible sleeve surrounds the die. Specification 800,841 [Group VIII] is referred to.