Patent GB-1448021-A (GB)
Title: Feed control apparatus for a grinding machine
IPC: B24B47/20
Filed: 1973-10-19
Abstract: 1448021 Grinding TOYODA-KOKI KK 19 Oct 1973 [28 Oct 1972] 48898/73 Heading B3D [Also in Division G3] In feed control apparatus for a grinding machine in which the wheel is advanced by a stepping motor drive, means are provided to preset a set, F 1 -F 4  of feed speeds and a pair l 1 , l 2  of feed amounts in preset digital switches, latter feeds F 3 , F 4  of the grinding processes being commenced and terminated under control of actual size attained signals produced by a caliper 81 contacting a workpiece being ground. As shown the amount 11 of the first feed F 1  representing grinding wheel approach under stepping motor control is preset in digital switch 40 to be compared at 70 with the content of a counter 79 counted up or down by forward resp. reverse rotation pulses fed to the stepping motor 33 moving the wheel via a lead screw, the speed of the feed F 1  being pre-set in switch 42 and communicated during the first feed to units 72, 73 defining a corresponding pulse rate fed to D/A converter 75 whose output controls the pulse frequency of pulse generator 76, and consequently motor speed. When the content of switch 40 and counter 79 match, circuit 72, see also Fig. 5 (not shown) causes transfer of feed amount, and speed, to switches 41 storing l 2 , and 43 {feed F 2 , representing rough grinding}. Upon match of content of switch 41 and counter 79 content, feed is reduced to a creep rate for a time t a  set in switch 46, whose content is compared, with content of counter (400) Fig. 8 (not shown), counted up by a 1 Hz frequency pulse train, in unit (401) until equality prevails, feed F 2  then being resumed, caliper 81 being advanced toward the workpiece. Upon attainment of a first caliper size (AS1), Fig. 5 (not shown), fine grind F 3  is instigated after a delay t b , pre-set in switch 47, whose content is compared with content of the counter (400, Fig. 8), feed speed F 3  being pre-set in switch 44. When a second workpiece size is attained, a finishing feed F 4  {speed set in switch 45} is instigated until a final workpiece size is attained, whence the motor receives a high frequency pulse train to retract the wheel by reverse drive of motor 33, controlled charging and discharging of a capacitor (97), Fig. 6 (not shown) at the input of voltage to frequency converter (76a) of generator 76 ensuring gradual speed-up and slow down of the stepping motor, while counter 79 is counted back to zero. Simultaneously, an hydraulic feed arrangement, see Fig. 1 (not shown), piston (21) bodily carrying the leadscrew (22) with it, is fully retracted. When the wheel is dressed, facility is provided to correct the change in wheel diameter by feeding compensating pulses to the stepping motor, such pulses not counting up counter 79. Machine details, Fig. 1 (not shown).-Wheel slide 13 can be advanced hydraulically by piston-cylinder arrangement (20-21), the former moving the leadscrew (22) betweeen limit switches LS 1, LS2. The leadscrew is additionally rotated by stepping motor and gears (24, 29-32, 34), gear (29) being longitudinally extended to the extent of travel of piston (21). Swivel and traverse tables (36, 38) are provided, caliper (81) measuring workpiece diameter. Means (not shown) for dressing the wheel are provided.