Patent GB-609427-A (GB)
Title: Improvements relating to electric automatic control apparatus, more particularly for machine-tool and similar drives
IPC: G05B19/14
Filed: 1946-03-14
Abstract: 609,427. Switching systems. PRECISION DEVELOPMENTS CO., Ltd., and OLAH, G. March 14, 1946, No. 7935. [Class 38 (iv)] [Also in Group XXXVII] Automatic control apparatus for motors of machine tools or the like required to carry out a series of different operations and in which the start of at least one operation is dependent upon the completion of, or the attainment of a certain stage in, a preceding operation, is characterised by two control elements which progress synchronously in steps, one element initiating at each step the various operations in their desired sequence, whilst the other element controls the simultaneous progress of both elements to the next step in dependence upon the attainment of the certain stage in a previously initiated operation. The control elements preferably comprise insulating programme stencils which co-operate with contacts on either side thereof, the stencil or contacts being moved relatively to control the machine circuits by a step-bystep or other motor. As shown in Figs. 1 and 2, two machines are controlled by the contacts RMa2, RMb2 of relays RMa, RMb in machine control units Ma, Mb, energization of the relays being determined by a programme stencil Q, a step-by-step motor ZPS, which drives the stencil over a drum D past fixed contact fingers, and by limit switches MaE, MbE actuated by the machines themselves. The drum D comprises two cylindrical conducting portions' insulated from one another and provided with slip-rings DstO, DcO. Portion Dst of the drum co - operates with stencil - controlled contact fingers StMa, StMb to control the initiation of energization of the relays RMa, RMb, whilst drum portion DC and contact fingers CMa, CMb control the progress of the drum and stencil. A micro-switch SQ prevents energization of relays RMa, RMb in the absence of a stencil from the drum whilst repetition of a cycle of operations may be prevented by a contact finger OSt controlling a relay ROst which has normally closed contacts Rost, in the holding circuit of a main starting relay RSt. The apparatus operates as follows: Closure of button Bst energizes relay Rst which holds in over contacts ROst and Rst, thereby energizing drum portion Dst and also relays PSr, PR for pulsing the stepping magnet PS of motor ZPS which then rotates the drum. Upon, say, contact finger StMa making contact with the drum through a perforation in the stencil, relay RMa picks up and holds in over contacts RMa1 and limit switch MaE. The machine associated with unit Ma thereupon starts its operation and continues until the limit switch opens. Unit Mb is similarly energized over contact finger StMb and limit switch MbE when the drum advances to the next step. This may, however, be delayed by contact finger CMa previously engaging portion DC of the drum and completing, over slip-ring contact DCO and intermediate " limit " switch contacts MaF associated for instance with the machine controlled by unit Ma, a holding circuit for the stepping magnet of motor ZPS. Upon opening of the switch MaF, the drum advances to energize unit Mo. Further advance of the drum to initiate other operations is dependent upon one or more contact fingers CMb associated with a similar number of intermediate " limit " switches such as MbF, MbG controlled by the progress of other operations. A switch SC provides for the manual closure of the holding circuit of the stepping magnet when desired. In a modified arrangement switches, mechanically operated by the armature of motor ZPS, replace the stepping relays PSR, PR.