Patent GB-890847-A (GB)
Title: Method and apparatus for automatic control of machine tools by means of magnetic recording tapes
IPC: B23Q15/00
Filed: 1959-07-17
Abstract: 890,847. Electric copying machines; measuring angular rotation electrically. SHIBAURA KOKI KABUSHIKI KAISHA. July 17, 1959 [July 19, 1958], No. 24669/59. Classes 38 (6) and 40 (1). [Also in Groups XXII and XXXVII] In a control system for a turret lathe in which the movements of each successive tool are controlled by signals recorded on a first magnetic tape, the starting position of each tool is adjusted by hand and, a second magnetic tape prepared carrying the composite signal. The second tape is used thereafter to control the tool movements. The control system consists basically of a motor 26, Fig. 2, to adjust the tool slide, the motor being energized by a Ward-Leonard generator 135 the field of which is energized via amplifier 134 from a frequency discriminator in which are opposed the rectified outputs of two series resonant circuits 122, 123. These circuits are tuned above and below a reference frequency so that the magnitude and polarity of the signal applied to the amplifiers depends upon deviations in the frequency of a command signal relative to the reference frequency. The variable frequency command signal is obtained from the rotor of a selsyn transformer 118, the stator of which is energized at the reference frequency whilst the rotor is driven by another selsyn 116. The stator and rotor of selsyn 116 are energized via amplifiers 114, 115 from reference frequency and variable phase command signals respectively recorded on a magnetic tape 96. A third track on the tape 96 controls a duplicate system in respect of a second axis of movement. The fourth track is for on/off switching of the lathe. The motor 26 can also be controlled by signals from a manually adjusted potentiometer 138 by changing over contacts 130, 131. The movements of the motor 26 are converted to a phasemodulated signal by a selsyn 144 driven by motor 26 and energized from a signal generator 145. The outputs of the signal generator and the selsyn 144 are recorded on the second magnetic tape 101. It is assumed that the information on the first tape does not take into account the different datum positions of the various tools on the rotary turret, Fig. 1 (not shown). Therefore a preliminary run is made, without a workpiece, stopping the first tape temporarily before the programmed movement by each tool, and using the manual control 138 to move each tool to its correct starting position, this information being recorded on the second tape together with the programmed movement which then follows. The manual alignment is achieved by means of a retractable feeler 51, Fig. 3, which is brought into the operating position by a pneumatic ram 63 controlled by a solenoid valve 69 and push-button 95. The feeler comprises a head 62 coupled to a magnetic armature 61 and supported by a resilient disc 59. When the cutting tool is correctly aligned vertically and horizontally, it presses on the centre of the head 62 and so the armature 61 is displaced equally towards all four of the associated inductors 56, 57, 58 (and one not visible in the Figure), thereby bringing to resonance four series circuits tuned by capacitors 71 ... 74. The voltages across the capacitors then energize relays 83, 84 to disconnect the tool positioning motors and to energize a solenoid valve 70 so that the feeler is retracted.