GB505470A - Improvements in and relating to electrically controlled copying systems for milling and like machines - Google Patents

Abstract

505,470. Electric control systems; copying milling - machines. BRITISH THOMSON-HOUSTON CO., Ltd. Aug. 10, 1938, No. 23599. Convention date, Aug. 13, 1937. [Class 40 (i)] [Also in Group XXII] In a machine for copying a pattern, such as a copy milling or grinding machine, wherein a universally mounted feeler follows the outline of the pattern, the feeler carries an auxiliary feeler which takes up a position relative to the main feeler dependent on the pitch of the felt curve and in consequence controls the speed of the feed motors of the tool and feelers so that the resultant movement is in the direction of the tangent of the pattern at any point. Fig. 2 shows the feeler system, the main feeler 10 being mounted universally and carrying three armatures 12, 13, 14 which co-operate with electromagnets M1, M2, M3 arranged in bridge circuits and controlling pairs of relays for the depth, vertical and horizontal reversible feed motors respectively. The auxiliary feeler 24 is carried on a sleeve 18 which is rotatable within the sleeve 17 by a motor 8 under the control of a magnetic system M4 operated by horizontal movements of the auxiliary feeler 24. The main feeler 10 is maintained in contact with the pattern by a spring 28 which is anchored to the sleeve 18 and a ring 29 rotatable on the feeler. The sleeve 18 also carries contacts K1, K2 which co-operate with fixed potentiometers P1, P2 to effect a speed control of the horizontal and vertical feed motors. The potentiometer arrangement is shown in Fig. 1, the potentiometers P1, P2 being supplied from series connected generators 2, 3 and effecting speed control and reversal of the feed motors 4, 6 in accordance with the positions of the contact arms K1, K2 as determined. by the operation of the motor 8 and the position of the auxiliary feeler relatively to the main feeler, i.e. in accordance with the pitch of the felt curve. The resultant movement produced by the feed motors. is such that, so long as the main feeler engages the pattern, the feelers move tangentially to the pattern. If the main feeler leaves the pattern, the magnet system M2 or M3 or both become operative to control the feed motors 4, 6 directly, the potentiometer control being rendered ineffective until the main feeler again engages the pattern. During this operation the main feeler is moved up to the pattern in a direction approximately at right-angles to the pattern. The motor control relays are operated by the magnet systems through electric discharge tubes. The auxiliary feeler may be adjusted relatively to the main feeler by manual push button control.