GB572529A - New or improved precision registering or indexing mechanism for machine tool parts such as milling machine tables, jig boring tables, milling machine dividing heads, andthe like - Google Patents

Abstract

572,529. Indexing. HANCOCK, W. A. April 6, 1944, No. 6454. [Class 83 (iii)] Dividing or indexing mechanism for machine tools such as milling-machines and jig-boring machines, comprises a circular series of rolls or balls of uniform diameter closely juxtaposed, a detector roll or ball supported by a longitudinally movable rod, and urged by a spring against the circular series of rolls or balls, a worm-wheel annulus fastened to the indexing table or head and a worm engaging with the annulus. A circular work-table d is rotated by means of an annular worm-wheel b bolted to the underside of the table and engaging a worm c operated by a hand wheel r. The worm-wheel revolves in a groove or channel a<2> in a base member a and, if desired, the groove may be filled with lubricant. To a depending central hub d<1> of the table d is keyed a member f which serves as a holder for the circular series of rollers h. In the example described, twentyfour rollers are employed and are held in position by a ring j, one roller of the series being held by a bolt h<1> against movement around the member f. The series of rollers is engaged by a smaller roller o mounted at the end of a rod m longitudinally movable through two ball races carried in a slideway k and urged forwardly into contact with the rollers h by means of a spring incorporated in an indicator or gauge p whose operating rod p<1> engages a hardened end m2 of the rod m. As shown in Fig. 3, rotation of the rod m is prevented by means of a ball n engaging a longitudinal V-groove in the rod and in an adjustable race bar n. The indications of the gauge pointer will show when the roller o is exactly in the bight between two rollers h and also when it is exactly on the crest of one of the rollers h, thus giving forty-eight accurately adjustable positions for the table d. Intermediate readings of the gauge may also be used if desired. Clamping plates (not shown) carried by the base a may engage the wormwheel b to hold the table in any required position. Detent means may be provided for holding the rod m out of contact with the rollers h for rapid coarse adjustment. The wheel b may have 180 teeth and the pitch of the worm c may be such that one revolution gives a onetooth feed or a two degree rotation of the table. A graduated dial q which rotates with the worm shaft co-operates with a vernier scale on a fixed dial t.