Roller manufacture involves determination of the running surface shape and accuracy by injection of material between a body and a shell which forms the running surface

摘要

The roller comprises an annular body (5) and bearings (2,10) inside a sleeve-like shell (17) which forms a rolling surface (27). The rolling surface is formed into a desired curve by injection of a material into a chamber (25) between the annular body and the shell. The roller is initially preassembled by mounting the bearings (2,10) and annular body on an axle (1) and holding in position. A shell is then pushed onto the annular body and fixed by a press fit. The preassembled roller is then placed in the tool where one tool part (22) is aligned with one bearing and a second tool part (23) is aligned with an area of the shell pressed onto the second bearing. Shell expansion during injection is such that the recovery force in the shell is greater than shrinkage of the injection molded body. The contor of the outer surface of the shell is determined by an injection molding tool cavity in which the roller assembly is placed. Tool cavity dimensions are slightly less than those of the intended shell contor to allow for body shrinkage on cooling. Tool parting is along the axial plane. A radial bulge (29) on the first tool part produces a depression (31) in the injected body which aids axial securement of the roller when removing the second tool part. The shell is pot-shaped, has a stepped base (19) and a rounded outer running surface. An Independent claim is also included for the roller which comprises an injection molded body between the annular body (5) and outer shell (17) to resist loads applied onto the outer shell.