GB933914A - Drive gear mechanisms - Google Patents

Abstract

933,914. Drilling brush-stocks. J. EVANS & SON (PORTSMOUTH) Ltd. July 12, 1960 [July 13, 1959], No. 24051/59. Class 83 (3). [Also in Groups XXIII and XXIV] In mechanism for obtaining intermittent rotation of a shaft 29, Fig. 1, in variable steps, e.g. for indexing a workpiece in a brush-making machine relative to a drilling or tuft-inserting tool, a continuously reciprocating driving member 1 carries a sprocket 11 rolling on a chain 25 driving the shaft 29, means being provided to lock the sprocket to the member 1 for a selected portion of its return stroke so that during this portion the chain 25 is locked to and moves with the member 1. The member 1 is reciprocated by a crank pin on a driving shaft 4 and the sprocket 11 is coupled to a ratchet wheel 10 lockable by a pawl 13. Depression of the pawl to lock the wheel 11 is automatically controlled by an endless perforated tape 52 which is intermittently advanced over a fixed slotted plate 53 to allow a selected one of a row of spring-loaded pins 42 to project into the path of a roller 16 on the reciprocating pawls 13 as it returns. An adjustable ball catch holds the pawl down until the next forward stroke, when the tendency of the wheel 10 to rotate clockwise forces it up again. The frame 43 carrying the pins 42 is slidable on vertical rods 44, 45, Fig. 2, and is reciprocated vertically against spring action by linkwork actuated by a cam 47. The movements of the member 1, frame 43 and tape 52 are so phased that a pin 42 is projected through the plate 53 only during the return stroke of the member 1. The frame 43 carries two pins 54 also controlled by the tape 52 to actuate a reverse gear 34 on the shaft 29, e.g. through valves or switches. A brake 33 is permanently applied to the shaft 29 to prevent overrunning or back-running when the sprocket 11 is unlocked. The output shaft 40 of the reverse gear 34 may be coupled to a workholder to index it either between operations (such as drilling) or during operations (such as cutting). In a modification for obtaining complex movements (e.g advancing and tilting) of a workholder in a brush making machine, a single reciprocating driving member carries four sprockets selectively driving, in variable steps, four chains under the separate control of respective holes in a single endless tape to provide four independent output shafts. In this construction each of two of the pawls is controlled by a respective single row of pins, as in Fig. 1, while each of the other two pawls has two parallel rows of pins to provide for greater variation of output step. There are thus six rows of step-controlling pins and four -rows of reversal pins. The tape is fed by Geneva mechanism. In a modification wherein the chain gearing is replaced by toothed gearing, a driving member 201, Fig. 8, is oscillated about the axis of a driven gear 211 and carries a pinion 209 which may roll freely over the gear 211 or may be selectively locked to the driving member 201 during its return stroke by a pawl 212 to impart a step-by-step output to the gear 211. The pawl 212 is controlled by a perforated tape 218 coacting with upper pins 216 which are biased downwardly and engage lower upwardly biased pins 219. The construction may be modified to provide a plurality of separately controlled output shafts. In all constructions the endless perforated tape may be replaced by a succession of perforated plates. Specification 875,122 is referred to.