Patent GB-977941-A (GB)
Title: Improvements relating to feed means for machine tools
Inventor: BALMER HENRY
IPC: G05B19/04
Filed: 1959-12-30
Abstract: 977,941. Machine tool details. KENDALL & GENT Ltd., and ASSOCIATED ELECTRICAL INDUSTRIES Ltd. March 29, 1961 [Dec. 30, 1959], No. 44204/59. Heading B3B. [Also in Divisions G1 and G4] . The feed movements of a tool or workpiece in a machine tool are produced by a selsyn system, the transmitter drive motor of which is controlled by a bridge network including in one arm a potentiometer coupled to the drive motor and in the other arm a plurality of resistors arranged for switching in or out according to the feed required, the motor being automatically stopped when the bridge is balanced. Motorgenerator a, b supplies the selsyn transmitter drive motor c through reversing switches actuated by a centre-stable polarized relay 13. Bridge resistors 11, 12 are preset to correspond to a datum and a retracted position of the tool-holders, and 10 is manually adjustable for setting the feed movement required. A manual drive 20 is provided for the tool holder 18, which is normally driven by selsyn receiver g. A centre zero meter 37 may be provided to indicate the position of the tool, and an additional relay 33 of lower sensitivity may be provided to permit rapid feed except when close to the balance point. Tool holder 18 has a locking device 22 controlled by motor 21 with limit switches 23, 24, and the work table is controlled by motor 25 through clutches 26, 27, one of which gives a slow feed into the cut, while the other provides a rapid traverse. Limit switches 28, 29 are provided. A uniselector 39 is associated with relays and a control panel 38 to provide various automatic cycles of operation. The relays provide control as follows :-relay 2 controls motor 25 and clutch 26; relay 3 controls motor 21; relay 4 operates contact 4 to retract the quill; relay 5 operates motor 25 and clutch 27; relay 6 operates contact 6 to move the quill to a manually preset datum; relay 7 operates contact 7 and the feed set on potentiometer 10 is applied to the quill; relay 8 operates motor 21 to lock the quill. Energization of relay US controls the uni-selector contactor through contacts IL, OL, UL and LL, which are operated by limit switches 29, 30, 24 and 23 respectively. Automatic operation. (a) A first cycle consisting of rough-cutting the workpiece, unlocking and retracting the quill, rapidly traversing the workpiece, returning the quill to datum and relocking, is achieved by initially manually setting and locking the quill at datum, setting switch 40 to " Auto " and pressing " Start Cyele " button 41. Relays 2, 3, 4, 5, 6 and 8 are then energized in sequence. (b) A second cycle, consisting of the quill initially at datum unlocking, retracting, then feeding out to a set increment beyond datum and relocking, is obtained by setting switch 40 at " Off " and potentiometer 10 to the required feed, then pressing button 42. Relays 3, 4, 3, 7 and 8 are energized in sequence. (c) The previously set feed is cancelled, the quill unlocking, retracting, returning to datum and relocking, by setting switch 40 at " Off " and pressing " Reset " button 43. Relays 3, 4, 3, 6 and 8 are energized in sequence. (d) The quill at datum is unlocked and retracted by moving switch 40 to " Retract," whereupon relays 3, 4 and 3 are energized. (e) The quill is returned from retract to datum and relocked by turning turning switch 40 to " Off," whereupon relays 3, 6 and 8 are energized. If desired a number of feed-setting potentiometers representing a series of feed positions can be arranged for sequential switching to give a cycle of several cuts. A number of selsyn receivers may be fed in parallel from a single transmitter.