GB1445022A - Indexing mechanism for machine tools - Google Patents

Abstract

1445022 Indexing HURTH VERWALTUNGS GmbH 8 Oct 1974 [20 March 1974] 43489/74 Heading B3B [Also in Division F2] In a mechanism for effecting stepped rotation of a machine tool spindle, an index member 10 is arranged to engage index indentations 9 in a dividing plate 6 secured to the spindle 1, a one-way clutch 14, Fig. 1, transmits step-bystep forward drive rotation to the spindle from a driving rocker member 13, which is driven in a reciprocating motion through a connecting rod 12 by a crank 11, and a separate controllable clutch periodically couples the spindle to the rocker 13 during a portion of each cycle of reciprocation. Control of the latter clutch is governed by a cam coupled to crank 11. By the action of this clutch the spindle is prevented from freewheel spinning, following the initial acceleration period of forward rotation, and the spindle is further compelled to participate in the subsequent deceleration of the rocker, until the clutch is released shortly before a reverse movement of the rocker begins. The spindle is then free to be driven into a precise index orientation by the entry of pawl 10 into one of the indentations 9, under the action of a cam follower lever 17 and cam 16. The interchangeable dividing plate 6 is detachably secured by fastening means 7, 8, to a carrier body 2 which is held fast on spindle 1 by a key 3, a ring 4 and nuts 5. The crank 11 is provided with adjustment means in a slot 15 for alteration of the crank throw. In the embodiment of Figs. 1, 2, the controllable clutch comprises a disc 27, frictionally engaging a face of rocker 13, the disc 27 being keyed by a pin 29 to the carrier body 2, and its control means consists of a screw-threaded bush 23 fixed to casing 24, upon which is engaged a nut member 22 carrying arms 21, 26, such that a displacement of cam follower 20 by cam 19, against bias of a spring 25, causes an axial movement of nut 22, thereby engaging clutch disc 27 against rocker 13. In an alternative embodiment, Fig. 3, a cam follower 36 and cam 35 impart motion to an external shoe 30, pivoted by arms 32, 33 to the reciprocating rocker 13, in a radial clutch in which a friction lining 31 engages a peripheral face of the carrier body 2. In another embodiment, Fig. 5 (not shown), a similar linkage may actuate a radial clutch having an internal friction shoe, outwardly engaging a drum formed within the carrier body. Alternatively, a radially-acting band clutch may be employed.