Patent GB-1191666-A (GB)
Title: Method and Control Circuit for effecting the Sequential Operation of Machine Elements
Inventor: KIRK COLIN JOHN
IPC: F15B13/07
Filed: 1966-07-16
Abstract: 1,191,666. Machine tool control. MARTONAIR Ltd. 25 Sept., 1967 [16 July, 1966], No. 32041/66. Heading B3B. [Also in Division F2] A method of effecting the sequential operation of machine elements having respective associated fluid-operable sensing means 31-38 for detecting from each machine operation when the next machine operation is to be initiated and for producing a corresponding signal, consists in energizing at any instant only the sensing means that is to initiate the next machine operation, and applying the signal produced by the energized sensing means to initiate the operation of the machine element for performing the next machine operation in the sequence and to energize the next sensing means in the sequence and also to de-energize the sensing means that produced the signal. A number of machine elements are operated from an air-pressure source 16 by double-acting rams each controlled by a five-port spool valve 10 operated by air applied to one end or the other by a distributer 91. The rams may be replaced by rotary or diaphragm actuators or single-acting rams operated by three-port valves. When a machine element has reached a point when the next operation is to be initiated, one of a number of stops 21-27 closes a detector hole 31-38 arranged in any convenient position in a stationary or moving element. The stops may be arranged as dead stops or to merely slide over the appropriate detector hole or holes. Each hole is connected to a port in a casing 63. A port 66 in a rotor 64 can co-operate with each of the latter ports in turn. The rotor 64 is carried on a shaft 65, which also carries the distributer 91, and the port 66 is in continuous communication through a shaft bore 67 and a line 71 with a supply line 75 through a restriction 73. The port 66 is also connected to the end of a valve 78 biased by a spring 79 to a position where air is supplied through lines 82, 80 to retract a pawl-driving piston 87. When a detector hole becomes blocked, pressure builds up in the line 71 and the valve 78 is actuated to cause the piston 87 to advance the ratchet 90. Thereby, the rotor 64 is indexed to communicate with the next detector hole and the distributer 91 is advanced to actuate one or more of the valves 10. If desired, several detector holes may be connected to one outlet of the casing 63 so that several conditions have to be satisfied before the next operation is commenced. The holes may be arranged so that it is impossible for the operator accidentally to block the operative holes at any time to cause malfunctioning. If it is desired to skip a position, one of the ports 51-62 in the casing 63 is plugged. The valves 10 may control and be controlled by liquid means and the detector holes 31 to 37 may utilize the escape of a liquid. Or the distributer 91 could supply actuators directly instead of by way of the valves 10. Or the rotor 64 and the distributer 91 may be on separately indexed shafts. In a further modification, as described also in Specification 1,191,667, the rotor 64 and the distributer 91 are replaced by a single cylindrical body 120, Fig. 3, around which is indexed a distributer member (132) communicating in turn with the detector holes and the operating lines. The stroke of the indexing pawl 89 can be adjusted by a screw (167). A setting mask " 1 " on the distributer member is visible through an aperture 168 and co-operates with a pointer 170 which indicates the ports then operative and the direction of movement of the distributer member. In a further modification, the indexing means is rendered self-cocking to assist in skipping positions. The indexing device will then advance intermittently until an unblocked hole is reached. Thus, any desired sequence of operations may be achieved by selecting the detector holes in any sequence by a punched tape which covers all holes but one as it is advanced by pneumatic and ratchet means over the holes. Air is prevented from passing to any of the valves 10 during repeat indexing of the distributer shaft by a time delay valve exhausting through a constricted passage.