GB1444800A - - Google Patents

Abstract

1444800 Helical compression springs R L BURCHETTE 7 Dec 1973 [21 Dec 1972] 56934/73 Heading F2S [Also in Division B8] An axially compressible tubular element e.g. a dye spring comprises a pair of end rings 12, 13, a helical lead 20 between the rings 12, 13 and connected thereto, and a plurality of members 30 perpendicular to the rings 12, 13 and secured at opposite ends to the adjacent portions of the lead 20, the members 30 being spaced from all adjacent members both axially and helically and serving to limit axial compression of said element. The members 30 may be provided with slots and the helical lead 20 with mating projections whereby radial distortion is avoided. A plurality of helical leads with the same pitch may extend between the rings 12, 13. As an alternative at least one intermediate ring may be provided with the helical lead extending between an end ring and an adjacent intermediate ring and between adjacent intermediate rings where there are more than one. As a further alternative, a plurality of helical leads may extend between the end rings or between an end ring and an intermediate ring, the leads being of opposite pitch, and posts 328 being provided at the crossing points to limit the axial compression (Fig. 8). The tubular element is preferably integrally moulded from plastics material, e.g. polypropylene. The helical lead 20 is preferably of trapezium-shaped cross-section and the lead 20 may be provided with a thickened cross-section adjacent the members 30. In the case that a filter paper is placed on the dye spring prior to winding of the yarn thereon, means, e.g. projections 27 may be provided to prevent the paper from slipping. The tubular element may be used as a spring or shock-absorber.