Patent GB-496965-A (GB)
Title: Improvements in the reproduction of motion from records thereof
IPC: B23Q35/122
Filed: 1937-06-10
Abstract: 496,965. Electric control systems. BERGIER, J., ESKENAZI, A., and GAVRONSKY, V. June 10, 1937, No. 16102. Convention date, June 20, 1936. [Class 40 (i)] [Also in Group XL] In a system for controlling machine tools, embroidering machines, paint spray-guns &c., the different co-ordinate movements are produced by motors controlled through followup devices by records representative of the co-ordinates. The records of the desired movements are produced by recording photoelectrically or electromagnetically the movements of a member operated in accordance with the movements to be effected to control electric impedances and thereby produce recording currents of variable amplitude or frequency. The record may be associated with a follower device having a contact which co-operates with the recorded trace or the record may be used to reproduce electric currents which operate the primary element of a follow-up device. In the former case the record may consist of a curve formed of insulating-material on a conducting base or vice versa and in the latter case records of the sensitive film or magnetized iron type may be employed. The records may be produced by currents of varying amplitude or by currents of different frequency produced by a resistance-controlled relaxation oscillator circuit. When currents of different frequency are employed, a number of different movements may be recorded on a single record film or disc, a complex wave being reproduced the various frequencies being filtered out to effect control of the corresponding motion-producing devices. In order to produce accurate working a single co-ordinate motion may be produced by two or more records. Furthermore when it is necessary to take into account the inertia and frictional forces arising during operation additional control may be effected by records of functions of velocity and acceleration. These records may be derived from the original record graphically or electrically with the aid of transformers. The forces of friction and inertia may be automatically accounted for by the use of electrical dynamometers when the original record is produced. Fig. 4 shows a circuit for controlling a motor v by a record consisting of two metallic surfaces s, t separated by an insulating trace. The motor is driven in one or other direction in order to make the brush p follow the trace. A brake u is provided to prevent the brush oscillating about the trace. In order to provide accurate working the movement of the record is made subservient to the operation of the controlled object and this is effected by ensuring that the record is moved on only when the brush engages the trace. When the record reproduces current which operates the primary element of a follow-up switch, the controlled object operates a relay which controls the driving clutch and the brake of the record. Fig. 7 shows apparatus for controlling single co-ordinate motion by two records. A drum 3 is provided with two metallic segments 4, 5 separated by an insulating zone 10. The drum is mounted for rotary and longitudinal movement by a threaded rod until the insulating zone co-operates with a brush 8 mounted on a ring 9 adapted to be rotated in accordance with one record and moved axially by a second record. This arrangement facilitates coarse and fine adjustments of the controlled apparatus. Instead of using a follow-up switch of ordinary type, a primary shutter 19, Fig. 12, and a follower shutter 18 controlling the passage of light to a pair of photo-electric cells 20, 21 and operated respectively by the record and the object controlled, may be employed for controlling the motion. The amount of discrepancy between the elements of the follow-up switch or between the shutters may be used to control the quantity of driving force applied to the controlled object.