Patent GB-1271852-A (GB)
Title: Improvements in or relating to necked tubes
Inventor: HABERHAUER KARL
IPC: B29D23/20
Filed: 1969-07-18
Abstract: 1,271,852. Seaming non-metallic sheet material. D. SPIESS [trading as C. F. SPIESS & SOHN]. 18 July, 1969, No. 36349/69. Heading B5K. [Also in Division B8] In a method of making a thin-walled tube body from a multi-layer laminate in sheet or tube form, the laminate comprising at least one metal layer disposed between plastics layers, a welded joint is produced between parts of the tube body or between the tube body and a nozzle, by pressing together the respective parts and inductively heating the or each metal layer to provide the heat needed for welding, the areas of the parts adjacent the joints being cooled during welding.  The tube body may be produced from a polyethylene-aluminium-paper-polyethylene laminate on sheet or tube form. Instead of one or both polyethylene layers, polypropylene or polyester may be provided. In one construction of tube, Fig. 1, the tube body 1 is welded to an injection moulded plastics nozzle 2 having a nipple 4 and a shoulder part 5. An additional shoulder part 3 comprising a frusto-conical ring is positioned to overlie the part 5 and the upper part 6 of the body 1. In modification, Fig. 3 (not shown), the part (6) extends over the entire outer surface of the part (5). In a further modification, Fig. 4 (not shown), the additional shoulder part (12) lies within the part (6) which is within the shoulder part (14) of the nozzle. In another construction, Fig. 2, the additional shoulder part is omitted and the body 1 has a long upper region 8 comprising the tube shoulder and nipple which can be formed with a mandrel inside the body 1. The nozzle 9 lies outside the region 8. In a further construction, Fig. 5, the body 1 is formed with a long end region 15 which is inserted into the nozzle 17 having a strengthening ring 20 at the upper end thereof. A bush 16 is disposed within the nipple 18 of the nozzle 17. If the tube body is formed from a sheet, the sheet is formed with a narrow fold 22, Fig. 6, along one longitudinal edge and this fold is placed in a groove 23 in a mandrel 21 made of a good heat conducting material, e.g. aluminium, and having a high heat capacity so that the parts adjacent to the joint are cooled during welding. The laminate is wrapped around the mandrel 21 and its other longitudinal edge is placed over the fold 22. Welding is effected by a single hollow induction loop 24 filled with cooling water and mounted in a ceramic or polytetrafluoroethylene body 24 pressed against the tube parts. To join a nozzle to the body 1 to form the construction of Fig. 1, the mandrel 21, Fig. 7, is formed at one end with a polytetrafluoroethylene head 26 upon which a nozzle 2 is superimposed. The part 6 of the body 1 is pushed in the direction of arrows 28 on to the shoulder 5 and the part 3 is placed on the nozzle 2 and the part 6. A press tool 30 of ceramic or heat resisting plastics material is lowered to press the tube parts together and an induction loop 32 is energized to effect welding. In a modification (not shown), the loop 32 is formed separately from the tool 30 above a guideway for the mandrel 21 so that the assembled tube parts on the mandrel are moved with the tool 30 through the induction field, the loop 32 remaining stationary. For the tube construction of Fig. 2, the head 26 has a longer nipple part. To close the lower end of the tube body with a transverse welded seam, Fig. 10, pressure is applied between a ceramic or polytetrafluoroethylene tool 34 having a water-cooled induction coil 33 and a block 37 of good heat conducting material, e.g. aluminium, and of high heat capacity. A thin rubber coating 38 may be provided on the block 37 and a copper foil 39 may be inserted between the coating 38 and the body 1 to ensure uniform distribution of heat.