Patent GB-1381074-A (GB)
Title: Arrangement for reversing a drive for a reciprocating machine part
IPC: B23Q16/00
Filed: 1973-05-21
Abstract: 1381074 Grinding WERKZEUGMASCHINENKOMBINAT 7 OKTOBER BERLIN VEB 21 May 1973 [19 May 1972] 24095/73 Heading B3D  An arrangement for reversing a drive for the timed reciprocation of a machine part 2 between two reversal points, such as a table of a grinding machine, comprises a control shaft 7 adapted to be directly or indirectly driven by the table drive of the machine, two drive discs 18, 19 non-rotatably mounted on the control shaft; one being axially slidable thereon, and two control discs 13, 14 axially slidable and rotatably mounted on the control shaft. Each of the control discs engages a respective end of a torsion spring 15 pre-tensioned between the discs. An annular friction surface is provided on each control disc opposed to a friction surface on a respective drive disc, and means 21 stress the slidable drive disc in the direction of the control discs. Each control disc has an element 9a, 9b for actuating a respective signal transmitter 8a, 8b and engaging a stop 16. The table 2 is reciprocatable by a rolling screw transmission which is driven through gearing 4 by a motor 1. The transmission is connected to a numerical-rotary path measuring system 17, for use in a numerically controlled machine, and by a worm 5 to a wormwheel 6 on the control shaft 7 mounted in a bearing 22. The drive disc 19 is secured to the end of the shaft and has a hub having an extension in which the drive disc 18 is keyed for axial movement. A sleeve on the hub supports by way of bearings, the two control discs 13, 14 which have friction surfaces engaging those on the drive discs, the disc 18 being urged by springs 21 abutting a thrust disc 20 against control disc 14, and control disc 13 being urged against drive disc 19. A pin 23 engages drive disc 18 and is movable by a thrust piece 12 which is disposed in a bore in shaft 7 and is engaged by the lever 11 of a solenoid 10. Each of the control discs carries an actuating element, 9a, 9b, for operating a signal transmitter which controls the deceleration and reversal of the table 2 in accordance with a predetermined programme. To set the actuating elements, the table is moved automatically or by hand to one of its reversal points and the solenoid actuated so that the drive disc 18 is moved against its springs 21 to disengage the friction surfaces and permit the torsion spring 15 to move the control discs until their actuating elements engage the stop 16, thus setting one of the elements 9a, 9b. Thereafter the table is run to its other reversal point to set the other of the elements by bearing against the stop as the set element moves away from the stop. During reciprocation of the table, the actuating elements 9a, 9b do not engage the stop 16 but actuate the signalling transmitters 8a, 8b which reduce the table speed prior to reversing of the motor 1. Additional transmitters may be provided to further control the reduction in speed and reversing. In other embodiments, the frictional connections may be effected by electromagnetic couplings and each frictional connection may be actuated separately.