| 摘要 |
1,133,436. Plastics tubes. RAYCHEM CORP. 21 Oct., 1966 [22 Oct., 1965], No. 47292/66. Heading F2P. [Also in Division C3] Heat unstable tubing capable of changing dimension upon the application of heat alone to assume a predetermined dimension and heat-stable condition may be prepared by mixing a thermoplastic polyurethane with N,N<SP>1</SP>- methylene - bis - acrylamide, extruding the mixture to produce tubing having an average wall of 0À016 inch and an average internal diameter of 0À113 inch, irradiating the tubing to two different doses of 10 and 20 megarads to cross-link the polyurethane and expanding the tubing to an external diameter of 0À25 inch to 0À255 inch. The expanded tubing, when heated to 170‹ C., returns to substantially its original dimensions. ring 39, Fig. 2 (not shown) on a snap-action spring 33 which moves, on contraction of the thermostat, to open the auxiliary valve. On continued movement the spring bears against the main valve member and opens it. This member is connected to a sealing bellows 25. The auxiliary valve carries an adjustable abutment nut 34 engaged by the snap spring. This nut is adjustable by a tool inserted from below. In a modification, the plunger (11<SP>1</SP>), Fig. 4 (not shown), has a conical depression in its end, engaged by a conical end of a disc (39<SP>1</SP>). The point of engagement is arranged in the plane of the main valve closure surface so that the valve member can tilt to give a welldefined opening even if the lift is small. |
