Self-Closing Grips for Rubber

Abstract

The provision of satisfactory grips for holding dumb-bell specimens in tensile testing machines has always presented a number of difficulties. Several styles of self-closing grips are available, but none has been regarded as entirely satisfactory. Thus, the cam type is clumsy and often fails to hold the test-piece at very high extension or when the surface of the rubber is covered with a wax bloom, as sometimes happens. Another type, the bar grip, illustrated in Figure 1, has very much better holding power, but requires the specimen to have undersirably long end tabs.

Review - Natural and Synthetic Rubbers

“…It enables a complete calibration under actual operating conditions. Stubbs (218) devised self-closing grips of the wedge type, w-hich are used for holding rubber specimens in tension-testing instruments. Eller, Gondek, and Chatten (60) modified and improved their earlier machine for buffing vulcanized rubber specimens to uniform thickness before testing.…”

Elastomers

“…A new method of self-closing grips for rubber is described, which easily manipulates all types of rubber dumbbell test piece (136).…”