GB1168275A - Resilient Units - Google Patents

Abstract

1,168,275. Springs. H. D. GORDON. 30 Nov., 1966, No. 53695/66. Heading F2S. A volute spring unit, formed of a continuous, uniformly wide, ribbon of resilient material, e.g. steel or plastics, coiled upon itself approximately in the form of a general frustum of a hollow cone and used e.g. as a guard to protect machine parts, has one, or both, end turns of the coiled ribbon formed substantially into a cylinder with the substantially circular. edges of each end turn located in planes substantially normal to the longitudinal axis of the cylinder successive helical turns of the ribbon being in overlapping relationship. In this way end turn distortion, or bulging, is stated to be avoided. As shown in Fig. 1 one end turn 21 is cylindrical the spring being fully extended so that the turns, whose sides form progressively greater angles with the axis of the spring from top to bottom, frictionally engage each other. The spring has a substantially constant rate over the greater part, and stiffens appreciably at the beginning and end, of its characteristic. In a modification. Fig. 6 (not shown), some part of each turn, which diverges upwardly, lies on a straight line instead of on an irregular curve as shown in Fig. 1 and each turn is cylindrical, the characteristic of the spring being linear except for the end portions. In a further modification, Fig. 11 (not shown), in which the characteristic on compression differs from that on expansion, both end turns are cylindrical the intermediate turns, which converge upwardly, frictionally engaging to increase the resistance to compression when they have to be forced into parallel relationship. A substantial initial force is required to unlock the collapsed ribbon the characteristic then rising sharply and subsequently falling away rapidly the whole characteristic being in the form of a hump.