VALVE SEALS WITH HEAT-STRESSED TEFLON.

The authors explored the possibilities for improving the operational characteristics of Teflon used in seals of pneumatic systems by developing designs in which Teflon would have been in a heat-stressed state, i. e. , it would have been submitted to heat-hardening in a prestressed state (throughout the hardening process the slide valve with a Teflon lining remained in a mold where a contact pressure of 300 MPa developed on the packing surface). An analysis of the experimental data showed that in all the investigated designs of valve seals the loads distributed along a line or across an area and required for leak-proofing of the working medium are smaller than the loads needed for packings made of Teflon not stressed by heat. It can be concluded that heat-hardening of Teflon packings in prestressed state makes it possible to reduce the tightening pressure by improving their physicomechanical properties (by lowering the degree of crystallinity).