Patent GB-546080-A (GB)
Title: Improvement in operating means for the indexing mechanism of turrets for lathes and other machine tools
IPC: B23B3/18
Filed: 1940-11-21
Abstract: 546,080. Lathes. TRIGGS, W. W. (Warner & Swasey Co.). Nov. 21, 1940, No. 16746. [Class 83 (iii)] The turret of a lathe or other machine tool is carried by a slide fitted with separate indexing, locking, and clamping means and with a single motor for operating the indexing, locking, and clamping means. As applied to a lathe in which the turret 34 is rotatable on a saddle 28 which can be adjusted on the bed by means of a handwheel 28a, and also by means of a double threaded quick motion shaft 31, Fig. 8, with which coact nuts with opposite threads mounted in a box 32, the direction of motion of the saddle is controlled by a lever 55 which operates cam devices which actuate friction shoes for holding one or other of the nuts from rotation to effect movement in the desired direction or leave both nuts free when the saddle is stationary. This lever 55 is actuated by a knock-out rod 33 which acts to stop the motion of the saddle, and the lever 55 is associated with a switch-operating lever 52 which controls the energization of the motor 37 operating the indexing and clamping devices for the turret 34. The motor circuit includes two switches 49, 50, Fig. 15, in series, the switch 49 being hand-operated by a rod 51 which is moved inwards to operate the switch lever 51b and is normally returned to open the switch by a spring-pressed cam pin 61 mounted on the shaft 41 of the worm wheel 40 which operates the indexing mechanism. This worm wheel 40 is driven by the motor 37 and is fitted with a pin 42 forming part of a Geneva mechanism including slots 43a for rotating the turret. Prior to the operation of the Geneva mechanism a pin 45 on the worm wheel 40 operates a spring- controlled latching device which engages one of a series of apertures 43b in the turret base, and a cam 44 moves a rod 46 to cause the release of a clamping member which normally clamps the turret firmly in position. The indexing operation starts on closing of the switch 50 by a lever 56a which is operated by lever 55 when acted upon by the knock-out rod 33. The switch 49 is automatically opened at the completion of the indexing operation, and the switch 50 when the lever 55 is operated to cause the quick return of the saddle. The automatic opening of the switch 49 can be delayed, when it is required to give two or more succesive movements to the turret, by means of a lever 68 which is operated by a cam member secured to the turret in the desired position. The lever 68 prevents the rod 51 from being moved outwards to open the switch, and the spring mounting of pin 61 allows it to pass over the conical end 51a of the rod 51 when this is held by the lever 68. In a modification both switches are operated automatically, and one lever 52 only is operated to set the mechanism for stopping the saddle in its rearmost position, and to set the motor starting to operate the indexing, clamping, and locking mechanism for rotating the turret through the desired angular movement. A further operation of the lever 52 is necessary to cause the quick motion shaft 31 to return the saddle to bring the turret into operative position.