GB1031032A - Improvements in or relating to bearings - Google Patents

Abstract

1,031,032. Grinding. BRITISH AIRCRAFT CORPORATION (OPERATING) Ltd. Jan. 22, 1964 [Jan. 22, 1963], No. 2731/63. Heading B3D. [Also in Division F2] A method of making a bearing having two elements 11, 12, Fig. 1, each of which has at least three coaxial circular raceways 16, 17 of different diameters, and a multiplicity of balls or rollers distributed round and co-operating with the raceways, comprises forming the raceways to a high degree of accuracy and then bringing them to an even higher degree of accuracy by a lapping operation, whereby irregularities of the individual raceways are worn away. Preferably each element has four to six raceways each of part-circular crosssection and initially machined to an accuracy of 0À0002 inch. Lapping of the grooves is then effected by placing pumice and industrial grade balls 18 in the grooves and rotating one element relative to the other at, for example, 60 r.p.m. Alternate balls may be slightly smaller to provide a reference surface for comparing the appearance of the lapping balls during the lapping operation as the balls wear. The lapping may be effected in two stages first using balls accurate to 0À000,05 inch and then using balls accurate to 0À000,02 inch. After dismantling and cleaning, the bearing is assembled using more accurately spherical balls and the errors in circular motion of the bearing may be about 0À000,015 inch or less. Each element may also be lapped against a third element which has been similarly machined. In another embodiment, the raceways lie in different planes and may have part-conical cross-sections. In a further embodiment, the elements 31, 32, Fig. 4, receive tapered rollers 38. In yet another embodiment, the elements 41, 42, Fig. 5, have raceways for balls 48a and rollers 48b.