GB1411217A - Control apparatus - Google Patents

Abstract

1411217 Photo-electric motor control WICKMAN MACHINE TOOL SALES Ltd 27 July 1972 [5 Aug 1971] 36762/71 Heading G1A [Also in Divisions G3 H1 and H2] A stepping motor 17 is supplied through a decoder and selector 19 and an amplifier 20, the former element being controlled by either one of two control circuits 12, 14, 21, 22 and 13, 15, 18 whereby the motor may drive in a desired direction of rotation at a desired speed through manual operation of rotary knobs associated respectively with members 12, 13, the knob of member 12 being adjustable in either direction from a centrezero position to a fixed angular position representative of a desired speed and the knob of member 13 being continuously rotatable in either direction to produce a motor speed dependant upon the speed of knob rotation. Member 12 produces a signal which controls an oscillator 21 supplying a binary counter 22, a switch 14 being operable to change the speed range of the control. Member 13 produces a signal which is fed to a data selector 18, a further speed range switch 15 being associated with this control. Fig. 5 shows the member 13 which consists of a rotatable knob (having the same reference) operating a shaft 23 carrying a disc 25 having four radially-displaced rows of holes forming inner and outer pairs, the rows of each pair being circumferentially offset, Fig. 6 (not shown). Each row co-operates with a light source 34 and photo-electric cell 35 so that rotation of the knob 13a produces a signal pattern whose nature and frequency depends on the direction and speed of the knob rotation, which signal pattern is fed to the data selector 18. Tactile indication of the relationship between knob movement and the number of steps of the motor is provided by a flange 27 having serrations engaging a spring detent 36 on the housing 24. Instead of using photo-electric means, the signal pattern may be produced by using a disc 25 having rows of depressions or alternating conductive and non- conductive portions which control or constitute switch contacts. Fig. 7 shows the member 12 which consists of a rotatable knob (having the same reference) operating a shaft 37 carrying a cam 45 controlling micro-switches 49, 51 determining the - direction of motor rotation. The cam also carries a pin 43 co-operating with 180 degrees arcuate slots 44 in discs 41, 42 spring-urged against a stop corresponding to the centre-zero position of the knob, Fig. 8 (not shown), the slots being diametrically opposed so that operation of the knob moves one or other of the discs via members 43, 45, after which a locking mechanism is operated, Fig. 9 (not shown) to hold members 37, 41 or 42 and 45 in the set position. The shaft 37 also operates a rotary potentiometer 39 which controls the frequency of the oscillator 21. The stepping motor and its control apparatus may be duplicated to control the two lead screw operated slides which adjust the position of the grinding wheel of a grinding machine, Figs. 1, 2 and 3 (not shown).