Patent GB-691083-A (GB)
Title: Control systems for use with a machine tool
IPC: B23Q35/26
Filed: 1951-02-23
Abstract: 691,083. Copy - turning. MONARCH MACHINE TOOL CO. Feb. 23, 1951 [March 8, 1960], No. 4490/61. Class 83 (iii). A control system comprises pattern means 50, 51 and actuating means for moving a tracer control from one pattern to the other to control the relative movements of the tool and work in separate parts of an automatic cycle of a machine tool. As applied to a lathe having a spindle-driving motor 17 and a variable-speed reversible electric motor 24 for rotating the leadscrew 23, the control system comprises a pattern and tracer assembly 42, a hydraulic cylinder 22 carrying the tool 28 and cooperating with a piston 26 fast with the saddle 20, a hydraulic pump 32 and an air pressure source 36. The tracer 42 is linked with the cylinder 22 and by bleeding air from the supply line 44 in accordance with the shape of templates 50, 51 controls a bellows 31. The bellows 31, in turn, controls a hydraulic valve 30 supplying fluid to the cylinder 22. The roughing and finishing templates 50, 51, Fig. 3, are clamped at 53 to a table 47 oscillatable about a pivot 48 by a pneumatic piston 56 supplied through a twoway valve 61, Fig. 7. The saddle 20 carries limit switches 64, 65, Fig. 9, to contact adjustable or fixed right- and left-hand stops 67, 68 and a centre-switch 66 to contact a stop 69 adjustably mounted on a rail 70. The electrical circuit for controlling the cycle of operations of the lathe includes a rectifier system 92, which may be electronically controlled in accordance with the bias established by a feed potentiometer 97 and a traverse potentiometer 98, and a maximum feed-rate potentiometer 99. The rectifier system also includes a tachometer generator 101 driven by the motor 24 with a controlling potentiometer 102 and a feed meter 103 to indicate the rate of feed of the saddle 20. Two three-phase motors 17, 33 drive the spindle and hydraulic pump 32 respectively. A solenoid SOL3 operates an air bleed 89 to place the valve 30 in a neutral position or to cause the tool to be withdrawn. Operation. Initially, the table 47, Fig. 3, is in its raised position so that the roughing template 50 may be engaged by the tracer which is positioned at 42a, Fig. 6, and the right limit switch 64 is in its closed position. A switch 100 is then closed to energize the rectifier system 92 and switches 77, 81, 82, 87 are closed to start the cycle of operations. Closing of the switches causes relays HM, SM to be energized to start the spindle motor 17, the hydraulic power motor 33 and a timing relay TA is energized. The tool then advances into the work until the tracer contacts the roughing template 50 and bleeds air from the system to establish the valve 30 in a neutral position. The tracer 42 is at the position 42b when the timer TA starts the saddle-motor 24, opens a switch F5 to break a dynamic braking circuit, and completes a circuit to the feed meter 103. The saddle 20 is thus fed to the left until, when the tracer 42 is at position 42c, the switch 66 energizes a solenoid SOL1 which reverses the valve 61 and causes the piston 56 to lower the table 47. Closing of the switch 66 also causes contacts J4 to be closed to render further operation of the switch 66 ineffective. Solenoid SOL3 is also actuated to open the air bleed 89 to prevent further feed of the tool and the tool is locked in position by opening contacts TR1 to stop the motor 33. The relay TR is energized and the saddle is returned to the right, the contacts TR6 being open and the feed potentiometer 97 being replaced in the circuit by the traverse potentiometer 98. When the tracer 42 reaches the position 42d, the limit switch 64 on the saddle is actuated by the stop 67 to re-set the circuit to its initial state with the exception that a timing relay TB is substituted for the relay TA and the solenoid SOL1 has been actuated to lower the table 47. Thus the tracer 42 moves in to contact the finishing template 51 and the saddle is fed to the left until the switch 65 is actuated by the stop 68. The solenoid SOL2 is energized, and, if a plugging switch 83 has been closed, the spindle motor 17 is rapidly brought to rest. The solenoid SOL2 is energized to raise the table 47 and the saddle is returned at a rapid traverse rate. When the saddle-switch 64 is actuated, the machine comes to rest with the controls in their initial positions so that a new cycle will be started by actuation of the button 87. Actuation at any time of a reversing switch 85 returns the saddle to the right. A switch 88 can be opened to cut-out movement of the table 47 to enable a single template to be used, the trip dog 69 then being removed. Opening of the switch 82 during a leftward feed of the saddle brakes and stops the motor 24. Specification 660,112 is referred to.