GB618483A - Improvements in indexing mechanism - Google Patents

Abstract

618,483. Thread grinding. JONES & LAMSON MACHINE CO. Oct. 15, 1946, No. 30680. Convention date, Oct. 16, 1945. [Class 60] Machines for grinding threads and the like are provided with a rotary work spindle, means for rotating said spindle, means for moving said spindle axially in predetermined relation to said rotation, means, including a planetary transmission having a normally stationary part, between said rotating and moving means, and power means comprising a motor for turning said normally stationary part at intervals to thereby change the angular relation between said rotating means and said moving means. In a multi-start thread-grinding machine of the type, for example, as that described in Specification 478,757, in which the work is traversed and rotated by lead screw and spindle driving mechanism, a work spindle 3, Fig. 3, is rotated by a gear 7, driven through reversing mechanism from a drive shaft 75 (not shown), through a lost motion device 15, 16, 17 and a ring 13 to a sleeve 8 having a bevel gear 18 which drives pinions 19 journalled in a normally stationary spider 21, the pinions 19 driving a bevel gear 22 keyed to the spindle 3. At the end of each grinding pass a motor 45, Fig. 9, is actuated to turn the spider 21 and thus give the work an extra, indexing, rotation. The spider 21 meshes with a worm 26 geared to a shaft 30 driven by a worm 33 and a worm wheel 31 driven by a pulley 42 from the motor 45. The means for actuating the motor include a solenoid 50 energized by the closing of a switch operated by a dog on the reciprocating carriage as the carriage approaches the end of its stroke. The solenoid lifts a pivoted latch dog 56, which contacts a locking shoulder 58 on a cam 32 mounted on the shaft 30, to allow the shaft 30 to rotate and at the same time the dog 56 lifts an element 61 to close a switch 63 which causes switch arms 65, 66 to close a holding circuit for a relay 64 and to energize a motor 45. Rotation of the shaft 30 continues until a cam 70 adjustably fixed to the cam 32 opens a switch 72 which stops rotation of the motor, any continued rotation of the motor after the shaft 30 is positively stopped by the dog 56 contacting the shoulder 58 is taken up by moving the worm wheel 33 along its shaft against the action of a spring.