Holding down bolt for plastics - has shank with two radial necked step reductions and coarse thread on upper two zones, to be pressed into heated bore

摘要

The holding down bolt is for plastics material (9), with an embedded shank (2) with radial steps reducing the diameter towards the foot of a preliminary bore. A cylindrical body (1) projects above the plastics, defined by a circumferential flange (7). The flange (7), a top shank zone (5), an intermediate shank zone (4), and a basal shank zone (3) are separated by rectangular section grooves (6). The top two zones (5,4) have inverse coarse spiral threads. The base zone diameter corresponds to that of the bore, and a flat (8) on the shank zone is tangential to the base zone (3). Longitudinal grooves may be used in lieu of flats (8), and the bolt may be forced into place as heat is applied to the plastics material.