Patent GB-872469-A (GB)
Title: Improvements in or relating to gauging apparatus
IPC: B23Q16/02
Filed: 1957-08-20
Abstract: 872,469. Programmed electric control systems; dimension checking systems. WARNER & SWASEY CO. Aug. 20, 1957 [Aug. 21, 1956], No. 26293/57. Classes 38 (6) and 40 (1). [Also in Group XIX] Programmed apparatus for gauging a workpiece 50 by alternate positioning and probing movements of a probe 55, and indicating or recording electrically both the actual profile of the workpiece and a standard profile comprises a base 20, a fixed block 21 upon which is slidably mounted a block 22 movable in a longitudinal direction by a lead-screw 25L driven through gearing 29 . . . 31 by reversible fast or slow motors FML, SML, and a block 41 carrying the probe movable transversely on the block 22 by a lead-screw 25T driven by reversible fast or slow motors FMT, SMT. Records of both the actual and standard measurements are made by spark recorders 58, 58<SP>1</SP>, Fig. 8, for the longitudinal and transverse movements respectively. The apparatus is programmed either (a) partly by a punched tape 70 having groups of four holes controlling qualitatively the movements of the probe, i.e. longitudinal or transverse, fast or slow, forward or back, and positioning or probing, and partly by disc stacks CDL, VDL, CDT, VDT set by hand to control the extent of the various movements or (b) wholly by punched tape having groups of eight holes controlling both the nature and the extent of the various movements of the probe. Programming method (a).-The punched tape 70 is fed step-by-step through a reader 71 and controls through relays the various motors FML, SML, FMT, SMT, to move the probe quickly into position for probing, slowly for the actual probing movements and quickly for retraction. The disc stacks for hand setting of the extent of the movements comprise annular conducting discs 132a-132#, Figs. 5 and 6, each with a whisker 137 contacting an insulating rotor 130 with a thin brass contact-plate 131 earthed through the shaft e.g. 122L. The discs are displaced angularly by a picker engager in slots 160 by amounts representing the desired extents of the movements of the probe. Coarse longitudinal and transverse disc stacks CDL, CDT have their rotors 130 driven from the shafts 25L, 25T, respectively, through worm gearing by one revolution for every eighty revolutions of the shafts 25L, 25T and control the movement of the probe to the nearest whole revolution of the shafts. Fine movement disc stacks VDL, VDT have their rotors coupled direct to the free ends of the shafts 25L, 25T and control the movements of the probe to fractions of a revolution. Disc steppers CSL, CST, VSL, VST are associated with the disc stacks to select the discs for the next operation, the discs being connected to terminals 200, Fig. 8, over which a contact 201 is stepped by a ratchet-wheel 202 actuated by a solenoid 203. On contact of a whisker 137 with a plate 131 the respective disc is earthed through an amplifier 204 to produce an output signal which energizes winding FD to disconnect the motor, e.g. FML, and dynamically brake it. The disc steppers VSL, VST are similarly arranged in amplifier circuit 205<SP>1</SP> for slow positioning movement, but are connected to stylus 58, 58<SP>1</SP> during a probing movement of the apparatus. On contact of the whisker and plate in the disc stack VDL or VDT an output signal is produced from amplifier 204<SP>1</SP> which is supplied to the recording stylus 58, 58<SP>1</SP> depending on longitudinal or transverse movement, to produce a mark on record strip 59, 59<SP>1</SP> indicative of the predetermined standard dimension, which may be compared with a mark produced by a signal from amplifier 230 on contact of the probe 55 with the workpiece 50; the output signal from the amplifier 230 in this case also causes the motor driving the probe to be reversed. Programming method (b).-A single disc, Fig. 10 (not shown) of similar construction to that described above is substituted for the plurality of discs in the disc stack, the tape 70 having additional code holes in each group which control contacts, e.g. qa-qd and associated relay windings QA-QD, the permutations of which are translated into an analogue value by a digital-to-analogue network comprising resistors rl-r8 connected in series across the secondary 250 of a transformer 251 whose primary 252 is connected between power lines 180 and 181; the turns ratio of the transformers primary and secondary winding is such as to impress, say, 10 volts across the resistors r1-r8. The resistors r1 and r5, r2 and r6, r3 and r7, r4 and r8 are connected in parallel and have resistance values 1, 2, 2, 5, respectively. If the windings QA, QB, QC, QD are energized the contacts QA1, QB1, QC1, QD1 remain open while contacts QA2, QB2, QC2, QD2 remain shorted out, the 10 volts appearing entirely across resistors rl to r4. By energizing the relays, contacts on each side of junction 260 will be respectively opened and closed to impress varying voltages above and below the junction 260. Servo units CUL, CUT, VUL, VUT replace units CDL and CSL, CDT and CST, VDL and VSL, VDT and VST. The desired operational characteristic is read off the tape and the corresponding servo unit energized, e.g. CUL. In this event a variable tap resistor 265 is connected across the resistors rl to r8 and the two input terminals of servo amplifier 266 are connected to junction 260 and tap 270, respectively. The tap is driven along resistor 265 by a servomotor 267 which also angularly adjusts the contact whisker. Any resistance unbalance of the bridge will be manifested as a proportional voltage appearing between junction 260 and tap 270 and the servo amplifier 266 will respond to drive the servomotor until the tap 270 restores the bridge to balance and adjust the contact whisker to its required setting. The contact of the whisker and contactplate in the case of a probing operation may actuate a camera which causes an image of the instantaneous angular position of the contactplate to be exposed upon the camera film. The camera is again actuated in response to the signal produced upon contact of the probe 55 with the workpiece 50 to similarly record the instantaneous angular position of the contactplate. These two images may then be compared for departure of the portion being gauged from its required tolerance value. Or a counter may be operated and the reading of the counter photographed, once when the contact-plate reaches the whisker and again when the ball 55 makes contact with the workpiece 50. Specifications 662,073, 695,725, 701,116 and 872,470 are referred to.