Patent GB-881057-A (GB)
Title: Pattern controlled milling machine
IPC: B23Q35/123
Filed: 1959-03-24
Abstract: 881,057. Electric correspondence control systems; copy-milling. CINCINNATI MILLING MACHINE CO. March 24, 1959 [April 16, 1958], No. 10125/59. Classes 38 (6) and 40 (1). [Also in Groups XXII and XXIX]  In a copy-milling machine of the kind in which the outputs of a first E-type transformer actuated by the template follower is resolved into two components at right angles to control electrohydraulic servomotors effecting tool movements along two axes, and a second E-type transformer is provided for three axis operation, selector switches and relays enable one axis or any pair of axes, or all three axes, to be automatically controlled, with manual control of any remaining axis, or purely manual control can be used.  Milling machine.-A travelling column milling machine has a fixed vertical column 28, Fig. 1, carrying the template and the workpiece; and a travelling column 22 mounted on longitudinal guide-ways 21 and driven by a rack and pinion 206 by a first hydraulic servomotor. The tool spindle 39 is mounted on a compound slide for vertical and horizontal movements controlled by two further hydraulic servomotors. The template tracer 31 is mounted on a further slide 33, vertically adjustable on a pillar 34 slidably mounted on the tool carrier. Tracer construction.-The tracer head 100, Fig. 6, is rotatably journalled at 97, 98 about a central rod 84 which slides within a sleeve 83 and is urged forward against a stop 115 by a spring 119. The rod 84 carries an arm 114 which operates the armature of a first E-type pick-off 81 which controls the horizontal tool feed only when all 3 axes are under automatic control. The rod 84 is otherwise locked to the sleeve 83 by a clamping ring 122. The sleeve 83 is itself universally mounted within the casing 80 being journalled at 92 for longitudinal movement against a spring 107, which spring also urges the sleeve against a spherical seating 87 so as to pivot about a point 88. The spring 107 operates through a plunger 105 having a ball and double cone coupling with the rear of the sleeve 83. The plunger 105 carries an arm 108 which operates the armature of the second E-type pickoff 82 which normally controls the tool movements. In all cases an initial deflection of the feeler is necessary to move the pick-off to null. This amount is adjustable by a spring-loaded counterbalancing yoke 131, Fig. 7 (not shown). Two axis automatic control.-The output of the pick-off 82, Fig. 12, is applied via a phase discriminator to an hydraulic motor, Fig. 13 (not shown), which rotates a pair of mechanically linked resolvers R1, R2. The rotor windings 291, 292 of the resolvers are energized by a feed rate signal tapped off a potential divider 295. The stator windings 304, 305 are at right angles to each other so that sine and cosine signals are obtained which are applied via manually selected relays to the desired pair of servomotors so as to move the tool, and tracer, along the contour of the template. A part of the output from pick-off 82 is also applied to rotor windings 289, 290 on the resolvers to provide a component of movement at right angles to the feed and so keep the tracer pressed against the template. Provision is made for automatically aligning the resolverse before starting a cut, and direction of movement, rate of cutting &c. can all be manually selected.  Three axis automatic control.-Substantially as above, except that the pick-off 81 is connected in to control the horizontal feed, whilst the vertical and longitudinal feeds are controlled by pick-off 82. One axis automatic control.-The output of the pick-off 82 controls the horizontal feed servo only, the resolvers being disabled and locked by selected relays. Manual control with one or two axis automatic control.-Each axis servomotor drives a synchro e.g. CT1 and for each axis there is provided a hand wheel and synchro e.g. TDX1. The system of selector relays is such that when an axis is not controlled from the tracer, the rotor of TDX1 is connected to the stator of CT1 and the output from the rotor of CT1 is connected to the phase discriminator and electrohydraulic servo for that axis. To provide a smooth change-over from automatic to manual, the stator of the synchro TDX1 is energized from a synchro TR1, the rotor of which is connected to a reference source. During automatic working the stator of synchro TR1 is energized by relays via the synchro TDX1, from the stator of yet another synchro TX1 which is driven by the axis servomotor. Hence the rotor of TR1  follows the automatic movement so that on connecting up TDX1 and CT1 for manual working the stator of TDX1 is energized so as to provide zero output from CT1. Pure manual control.-Selected relays connect feed voltages from transformer 325 directly into the phase detectors and servo amplifiers render the control of pairs of reversing push buttons, one pair for each axis.