| 摘要 |
856,681. Expansion joints. DUNLOP RUBBER CO. Ltd. Aug. 29, 1957 [Sept. 15, 1956], No. 28274/56. Class 99(1). Bellows, e.g. for expansion joints in pipe lines conveying corrosive fluids, comprise preformed sections of a fluorine-containing polymer which are joined together at their edges. As shown, discs are cut from a centrally-bored block of polytetrafluoroethylene or polytrifluorochloroethylene, each disc being split to within a short distance of the central hole therein and metal rings 1 being fitted between adjacent faces of the outer edge of each disc. A number of discs are assembled and clamped together by a screw-threaded rod carrying metal end plates, the latter being larger in diameter than the rings and tightened by nuts screwed on to the rod to thereby exert pressure on the outer edges of the discs. The assembly is placed in an oven at a temperature of 360‹C. for 90 minutes to fuse the edges of the discs together after which the assembly is cooled and the clamping means and rings are removed. In a modification, metal spacing rings are disposed at the inner and outer peripheries of each disc and on opposite sides thereof. The bellows may be circular, triangular, rectilinear, trapezoidal or polygonal in cross-section. To assist in the welding together of the discs a fluorocarbon paste or unsintered polytetrafluoroethylene tape may be used. |
