Patent GB-920066-A (GB)
Title: An electro-mechanical chucking mechanism for clamping devices
IPC: B24B41/06
Filed: 1959-05-06
Abstract: 920,066. Disc brakes. A. HONSBERG, [trading as HONSBERG GEB.]. May 6, 1959 [May 9, 1958; June 10, 1958], No. 15559/59. Class 103 (1). [Also in Groups XXII, XXIII, XXIV and XXXVII] In a mechanism wherein the input shaft 2, Fig. 2, of a clamping device (not shown) is driven rapidly by a quick-traverse electric motor 5 and more slowly by a clamping electric motor 6, the two motors are coupled to the shaft 2 through epicyclic gearing by spring- loaded axially-movable worms 9, 15 respectively driving the sun 11, Fig. 3, and carrier 16 of the epicyclic gearing, such gearing comprising stepped planets 12 mounted in the carrier 16 and coupling the worm-driven sun 11 with a sun on the shaft 2. The axiallymovable worms 9, 15 are urged towards a central position by springs 21, 22 repectively acting through levers 19, 20 and rock-shafts 17, 18 engaged by notched bearing bushes such as 28, Fig. 2, on the worm shafts. As the clamping device closes and the shaft 2 is accordingly braked, first the quick-traverse worm 9 and then the clamping worm 15 are displaced axially. The consequent displacements of the levers 19, 20 actuate pairs of switches 23, 24 and 25, 26 controlling respectively the motors 5 and 6. The motors 5, 6, Fig. 15, are universal motors having field windings FE1, FS1 for forward running and separate field windings FE2, FS2 for reverse running. When a manual switch P1 is moved to "clamp" (closing contacts 1<SP>1</SP>-2<SP>1</SP> and 1<SP>1</SP>-3<SP>1</SP>) both motors run forwardly until firstly the shaft 17 is rocked by the axial movement of worm 9 to switch-off the quicktraverse motor 5 and subsequently the shaft 18 is rocked by the axial movement of worm 15 to switch-off the clamping motor 6. Should the clamping pressure subsequently diminish below the value set by the spring 22 the switch 26 will automatically reclose to cause the motor 6 to re-establish that value. When the switch P1 is moved to " release " (closing contacts 1<SP>1</SP>-4<SP>1</SP> and 1<SP>1</SP>-5<SP>1</SP>) both motors run in reverse until again stopped by the axial movements of their respective worms. Brakes.-Means are provided for braking the quick-traverse worm 9, which is a reversible worm, upon axial movement of the irreversible clamping worm 15, and for this purpose the rock-shaft 18, Fig. 5 (actuated by the worm 15) has at one point a groove engaged by a plate 31 which, through one or other of two elements 32, presses brake plates 33, 34 against the housing, the plates 33, 34 being grooved to engage splines on the worm 9. In a modification the plate 31 comprises a stack of thin resilient plates. The brakes can only be released when the clamping motor 6 is reversed to shift the worm 15. The levers 19, 20 are preferably constructed as leaf springs. Provision is made, Fig. 8 (not shown), for adjusting the strength of spring 22 and hence adjusting the clamping pressure exerted before the clamping worm 15 is shifted axially. The motors 5, 6 may be arranged on the same or opposite sides of the epicyclic gearing. The shaft 2 may actuate the clamping bar of a drilling attachment, Fig. 11 (not shown), through rack gearing, or may have screwed engagement with the movable jaw of a vice, Fig. 13 (not shown), or may have screwed engagement with the driving piston of an hydraulic clamping device, Fig. 12 (not shown), operating through a number of clamping pistons. In the latter case the additional travel required during clamping, arising from the compression of the oil column, necessitates making the brake actuating plate 31 resilient, and providing a degree of play between the lever 20 and its spring 22 (Fig. 8a, not shown). Where, however, there is no yielding at all of the workpiece the control circuit may be modified, Fig. 16 (not shown), so that the two motors 5, 6, are switched-off simultaneously by switches actuated by the rock-shaft 18.