GB781660A - Improvements relating to mechanism for releasably securing a tool-holding device of a machine tool - Google Patents

Abstract

781,660. Lathe-details; chucks. NEW BRITAIN MACHINE CO. April 4, 1955, No. 9822/55. Class 83 (3). Mechanism for securing a toolholder L in the spindle 20 of a machine-tool comprises a member 44 slidable within the spindle and connectable to the toolholder, spring-means 56 for drawing the member 44 into the spindle and the toolholder into operative position, and means 59, 61 for moving the member towards the forward end of the spindle. As applied to securing the arbor L of a milling-cutter M in the spindle of a horizontal boring, milling and drilling-machine, the spindle 20 is supported in a slide 24, Fig. 2, traversed in the spindle-head by manual or power-means through a leadscrew 21 which co-operates with a divided-nut 23 to take up back-lash. The slide 24 may also support a pneumatic actuator 59, 61 for operating the chuck under the control of a push-button-switch 65 which operates a solenoid-valve 64 to admit compressed-air to, or exhaust it from, the actuator. The piston-rod 62 of the actuator engages the end of a rod 54, Fig. 3, secured to the sleeve 44 in which is mounted a plunger 46, influenced towards the front end of the spindle by a spring 49, and at least one locking member 52, e.g. four steel balls of larger diameter than the thickness of the wall of the sleeve and carried in passages 51, the outer ends of which may be peened to prevent escape of the balls during assembly. Before the arbor L is inserted in the spindle, the sleeve is held in the position illustrated in Fig. 5, against the influence of the spring 56, by the balls 52 which are projected outwardly of the sleeve and lodged behind a shoulder 53 in the spindle by the head 47 of the plunger 46. Upon inserting the arbor, a plug 38 integral with, or screwed into, the end thereof and having an annular-recess 40 adjacent its free end, displaces the plunger and allows the shoulder 53 to cam the balls into the recess 40 to free the sleeve 44 and enable it to draw the plug further into the spindle through the spring 56 and the balls 52, which are retained in the recess 40 by the narrower diameter of a part 32 of the spindle-bore, Fig. 3. In this position, keys 66 on the spindle engage slots 67 in the arbor-flange. The arbor is released by the pneumatic-actuator 59, 61 which displaces the sleeve 44 to carry the balls 52 past the shoulder 53 and allow them to be cammed outwardly by a shoulder 41 of the recess 40, into an enlarged bore 31 as the plunger 46 is advanced by its spring 49. If the pressure of spring 49 is insufficient to release the arbor, a positive release will be effected by contact between the end of the sleeve and a flange 39 on the plug 38. In a modification, Fig. 7, the sleeve 84 is displaced, against the influence of the spring 95, to release the arbor, by a cam or eccentric 78 which bears against the end of the sleeve. The spring 95 acts between a snapring 97, through which the sleeve may pass, and a flange 96 on the sleeve.