Patent GB-850400-A (GB)
Title: Improvements in control members for controlling the speed and direction of movement of machine-tool elements
IPC: B23Q5/26
Filed: 1957-12-09
Abstract: 850,400. Machine-tool details. WARNER & SWASEY CO. Dec. 9, 1957 [Dec. 14, 1956], No. 9717/59. Divided out of 850,399. Class 83 (3). A control-system for a machine-tool with a rotatable work-supporting spindle and a slidemember actuated by a drive responsive to an electric signal in accordance with a variablecharacteristic of the electric signal to effect relative feed-movement between a tool and the workpiece, is characterized in that selectivelyactuatable means are provided for varying the characteristic of the control-signal, and also means responsive to the rotational speed of the supporting-spindle to vary said characteristic of said signal, circuit means being included for applying the control-signal to a member for controlling said drive. Application of the invention to a turning and boring-mill is described in Specification 850,399. In this Specification a single hand control-lever 26, Fig. 2, operates a number of switches 76-79, Figs. 2 and 11, either separately or in pairs to move a tool-slide horizontally, vertically, or in a combination of these movements. The slide is driven by an hydraulic motor, e.g. 20, Fig. 12, and screw-andnut mechanism, and the direction and speed of traverse is controlled by an hydraulic valve, e.g. 31, operated by a torque-motor 38. The latter is controlled for feed, rapid traverse, and reverse through an electric control-circuit, Fig. 11, and an amplifier 128, Fig. 12. The hand lever referred to above moves the core 90, Figs. 2 and 11, of a differential transformer 91, energized by an oscillator 105, away from the neutral position so as to vary the output signal from split secondary coils 103, 104, arranged in " bucking " relationship. This signal is amplified at 106 and applied to the field coil 107 of an induction tachometer device 108, and to a primary coil 110 of a transformer 111 with split secondary 112, 113. The tachometer device has an output coil 115 which has a voltage induced therein dependent upon the magnitude of the voltage across field-coil 107, and the speed of rotation of a member 116 driven by the work-spindle of the boring-mill.. The output signal from the device 108 is connected across a primary 118 of a transformer 119 having a split secondary 120, 121. The output of the secondary coil 121 of transformer 119 is utilized to control the torquemotor 38, Fig. 12. A similar torque-motor 39 is controlled from secondary 120 to control the movements of a second compound tool slide. The other connections shown in Fig. 11 permit the spindle tachometer device to be by-passed for a rapid traverse movement of the slides, and also include reversing-arrangements obtained from signals of opposite phase to those used for the forward movements. Signals. are also imparted to the lines to obtain rapid response when the control lever is returned to " neutral " position. Movement of the control-lever from the neutral position to maximum displaced position causes the slide under control progressively to assume maximum feed-rate, and then finally, over the last 5 degrees of movement, a rapidtraverse movement. Arrangements may be made, however, for the control lever to assume maximum feed-rate, then return to zero feedrate, and after this to assume progressively a maximum rapid-traverse rate.