Patent GB-692686-A (GB)
Title: Improvements in or relating to a gauge adjusting and regulating apparatus for grinding and polishing machines
IPC: B24B5/38
Filed: 1952-01-18
Abstract: 692,686. Automatic control systems. CRUCIBLE STEEL CO. OF AMERICA. Jan. 18, 1952 [Feb. 12, 1951], No. 1488/52. Class 38 (iv). [Also in Groups XXIII and XL (b)] Elongated stock, such as wire, is ground to a pre-selected size which is automatically controlled by means including a reversible motor for displacing the grinding element towards and away from the stock, a pair of switches for selectively energizing the motor to run in one direction or the other, and a reversibly-energizable relay selectively to actuate the switches in accordance with the response of a gauging element. The motors 179, 180 for adjusting the grinding means towards and away from the stock are fed from a three-phase supply 181, 182 and are rendered reversible by switch means 189, 190 controlled by the gauging element. The latter consists of two photo-electric cells or tubes differentially connected to a relay 244 and respectively responsive to a magnified shadow of the stock 263 and an equally magnified shadow of a wire or rod 262 of the selected gauge. Variations in the size of the stock above and below the selected gauge produce a net current flow in opposed coils 245, 246 to swing a contact-arm 247 left or right as the case may be. The direction of movement of the arm determines the direction of rotation of reversibly-energizable motors 231, 232 fed from an A.C. supply 239 and serving to adjust rheostats 214, 228 controlling the balance of opposed magnetizing currents in two further relays 203, 204. Each of these latter actuates a contact arm 212 or 213 to cause selective energization of two pairs of relays 185, 187 and 186, 188 which operate the switch means 189, 190 to rotate the motors 179, 180 in the required direction until balance is restored at the gauging element. To prevent over-travel of the motors 231, an interrupter 271 is connected across their supply so that they receive a step-by-step rotation. The relay 203 has two opposed coils 206, 207 energized in proportion to the current and voltage respectively in the supply lines to the motors 175, 176, the coil 206 being fed through a current transformer 213, a step-up transformer 215 and a full-wave rectifier 216, and the coil 207 through a step-down trans. former 218 and a full-wave rectifier 220. This arrangement governs the load on the machine since current and voltage variations produce a compensatory adjustment of the motor 179 by disturbing the balance of the relay 203. The relay 204 is similarly connected. The effect of random fluctuations is suppressed by chokes 280. Initial balance of the relays 203, 204 is achieved by manually-adjustable rheostats 214 and by manual control of the motors 231 through switches 237, 238, 240 and 241. At the start of the operation, the stock passing through the machine is gauged manually and the grinding-wheels adjusted until it is the correct size by operating the relays 185 ... 188 through ganged switches 193 ... 200 which ensure that only one pair of relays is energized at a time. For this purpose, the relays 185 ... 188 are isolated from the relays 203, 204 by deenergizing a relay 211 fed by a transformer 268. Transformer-fed ammeters 201, 202 enable the load on the machine to be balanced before it is switched to automatic operation.