Patent GB-1088108-A (GB)
Title: Improvements in or relating to 360-degree copying apparatus
IPC: B23Q35/123
Filed: 1964-10-21
Abstract: 1,088,108. Copy-milling; copy-grinding. TURBOMECA. Oct. 21, 1964 [Oct. 29, 1963], No. 42905/64. Headings B3D and B3K. [Also in Division G3] A copying machine comprises a first servocontrol chain for controlling movement of a follower-holder in a cylindrical casing 14, a second such chain for controlling the movements of a platen 1c according to the movements of the follower-holder to maintain the follower 4c in contact with the pattern 2c, and a compensation device 22 acting on the first chain for compensating for the difference in diameters between the follower 4c and a tool 8c. The machine is hydraulically-controlled and the difference in diameter is set into the copying head 14 by a graduated manual-setting device 22, 23. The head 14, Figs. 7 and 8, carries a ball mounting 30 for the tracer. It also contains a hydraulic motor 36, a rotor arm 39 of which carries a pivot 35a for a lever 35 carrying a roller 32 held by a spring 37 against the inside of the head 27 of the tracer. The rotor arm also carries a pivot 38a for a cross-support 38 carrying rollers 33, 34 also bearing on the tracer head. The end of the rotor arm 39 has a slot 40 to receive a roller 41 on the tracer to restrict pivoting movement of the tracer to a direction perpendicular to the tangent at the point of contact. The motor 36 is of ball-type and is started and stopped by a valve 45 bearing on the crosssupport 38. The end of the rotor 36, Fig. 9, is shaped to actuate valves 51, 52 controlling hydraulic motors 17, 18 which move the work- and pattern-carrying platen 1c. In operation, a spring 54 moves the valve 45 forwardly to cause the rollers in the support 38 to tilt the tracer and to rotate the motor 36. Rotation of the motor causes movement of the table 1c by actuation of the motors 17, 18 and rotation of the tracer. When the tracer contacts the pattern, the motor is stopped and the cutter proceeds along the path then set. To increase the response of the tracer to changes, a leak past a collar 55 on the valve 45 causes the motor to vibrate and a slight offset of the slot 40 results in anticipation of a change. The hand wheel 22 is connected to a nut 58 engaging a thread on a sleeve 43 so that the valve 45 may be moved forwardly or rearwardly and so set-in the compensation for cutter diameter. If a milling cutter or a grinding wheel (69), Fig. 11 (not shown), is used, the hand wheel 22 may be adjusted automatically to compensate for wear by electrical measuring means (66), (68). The copying head (73), Figs. 12 (not shown) and 13, may be controlled electrically. Movements of the tracer affect a differential transformer 79 which applies signals to a device 80 which controls magnetic powder-type couplers 81, 82 causing a continuously-rotating electric motor 84 to be coupled to, or uncoupled from, the rotor 85. The rotor 85, Figs. 14, 15 and 16 (not shown), has cam surfaces contacted by valves 87, 88 to control the platen movements. When the tracer 4d, on a mounting (90), is moved by a biasing spring (93) about pivots (91, 92) on the rotor 85, the core (94) of the transformer 79 is moved to adjust the rotor 85. To improve stability, the tracer 4d is slightly offset and a third coupler 83 is provided to impose braking impulses on any movement of the rotor at a frequency of 100 times/sec. A switch (96) limits tracer movement. A knurled wheel (116) is provided to cause an approach movement of the tracer towards the pattern. The compensation for diameter is set in by a second differential transformer (123), Fig. 21 (not shown), which effectively modifies the neutral position of the transformer 79. In both systems, the compensating means may be used for setting the cutter for a roughing pass. A control panel 78, Fig. 22, carries a red light 131, indicating when the tracer is not contacting the pattern, and an approach button 130. A green light 133 indicates when a start pushbutton 132 has been depressed and goes out when cutting commences. It lights again when cutting is complete, and a push-button 134 stops the machine.