| 摘要 |
<p>1,171,153. Moulding P.T.F.E. linings. DURIRON CO. Inc. 19 Oct., 1966 [19 Oct., 1965], No. 46824/66. Heading B5A. [Also in Division F2] A one-piece corrosion resistant liner for a rotatable disc or butterfly valve (Fig. 1, not shown), which liner is adapted to cover the internal fluid flow bore (62) of the valve, the radial flanges (40) formed at the bore ends as well as to embrace the innermost portions of the disc shafts (46, 47), is formed from a cylindrical tube 115 of polytetrafluoroethylene. The tube is inserted into the cavity of a mould having the same internal configuration as the valve, or into the valve 15 itself in which case plugs 117 and 118 are fitted into the shaft receiving bores and a ring 119, corresponding to a sealing ring (22) of the valve, into the flow bore. A cylindrical mandrel 122 is then placed within the tube 115 and clamped in place between end caps 124 and 125 which are secured to the valve by studs and bolts 127 and 128, respectively, cylindrical grooves 126 being provided in the cap for receiving the tube end portions. With the tube assembled in the mould or valve, the unit is heated until the tube 115 reaches a temperature of 620‹ F. at which stage air, supplied at a pressure of 300-400 p.s.i. through a cap opening 134 into a central bore in the mandrel, is directed, via mandrel radial passages 132, against the inner surface of the tube thereby deforming it into the desired configuration (Fig. 6, not shown). The pressure and temperature are held for approximately 4 minutes, after which the unit is quenched in cold water until the internal pressure drops to 100 p.s.i. Upon this lower pressure being reached, it is maintained by an additional supply of air until the unit temperature drops to around 80‹ to 90‹ F., subsequent to which the unit is disassembled for trimming of the liner.</p> |
