Patent GB-1474480-A (GB)
Title: Apparatus for controlling the operation of a grinding wheel
IPC: B23Q15/013
Filed: 1974-10-28
Abstract: 1474480 Grinding TOYODA KOKI KK 28 Oct 1974 [29 Oct 1973] 46462/74 Heading B3D [Also in Division G3] In the grinding of a generally cylindrical workpiece W wherein, a normal cycle, rough grinding ab 1  takes place until a given oversize f 3 , as measured by gauge 12 is attained, whence finish feed b 1 , c 1  at a lesser feedrate takes place until the measured final size f 4  is attained, should; due to degradation of wheel quality engendering increased wheel-workpiece pressure and workpiece deflection; the duration of the finish feed phase became less than or equal to a predetermined time t 1 , the instigation of the finish feed in the subsequent cycle(s) takes place when the measured oversize is f 2  to give the feed cycle ab 2 c 2 . Similarly, fine feed is instigated at oversize f 1  as soon as the duration of the finish grind b 2 c 2  becomes less than or equal to a time t 2 . Gauge 12 provides signals AS1-AS4 at each of the oversizes, and at the finished size. At the instigation of a normal grinding cycle, relays (K1, K2), Fig. 2 (not shown) are set, so that when the signal AS3 is received at oversize f 3 , timer (TR1) is operated, relay (CR3) being energized, timer contacts (TR1b1) opening after time t 1 . Should the final size f 4  be reached in a lesser, or equal time, relay (CR4) operates, coil U1 resetting relay (K1), enabling the operation of relay (CR2) at oversize f 2  in the subsequent cycle. Timer TR2 of interval t 2  is energized when the oversize f 2  is reached, to enable the resetting of relay K 2  and enabling of relay (CR1) should the final size now be reached in a lesser or equal time to t 2 . When a predetermined number of cycles of all types are completed, a counting device (not shown) automatically instigates a dressing of the wheel, and automatic starting of further, normal grinding cycles, after the dressing. In a second embodiment, Fig. 4 (not shown), during a normal grinding cycle counter (32) counts the number of pulses; at the finish feedrate and also fed via forward/reverse and pulse motor controls (37-39) to pulse motor (31) of a leadscrew type wheelfeed; provided after the oversize f 3  has been reached, and until the finished size f 4  is attained. Should this number fall below a number, corresponding to the time t 1  and set in digital switch (33A) flip-flop FF1 is set so that, in the subsequent cycle, counter (32) counts the number of finish feed pulses from the oversize f 2 . A similar comparison between the content of counter (32) and that of digital switch (33B) set to correspond to time t 2  enables finishfeed to be instigated at oversize f 1  when the duration of the former finish feed becomes less than t 2 . Use of the three different types of cycle in sequence enables reduction in wheel redressing frequency for given finish accuracy. Grinding machine, Fig. 1.-The wheel is hydraulically driven, dog 8 on the wheel carriage operating reducing valve 9 to instigate the rough feed, one of the signals AS1-AS3 shutting off valve 24 to introduce a finish feed at a rate determined by valve 25. Signal AS4 given at the finished size operates forward/reverse valve 23 to retract the wheel check valves 26, 27 being provided. The work measuring device is fed forward hydraulically when measurements are to be made, diamond tool 18 being hydraulically reciprocated across the width of the wheel during dressing. Alternatively, the wheel may be driven by a pulse motor and leadscrew, Fig. 4 (not shown).