Patent GB-723182-A (GB)
Title: Improvements in or relating to a billet grinder
IPC: B24B49/16
Filed: 1952-10-20
Abstract: 723,182. Automatic control systems. CRUCIBLE STEEL CO. OF AMERICA. Oct. 20, 1952 [Oct. 26, 1951; April 1, 1952], No. 26245/52. Class 38 (4). [Also in Group XXIII] A machine for grinding billets (see Group XXIII) comprises a grinding-wheel 10, Fig. 1, and driving motor 18 therefor mounted at one end of a pivoted beam 14, a counterweight 35 slidable on the beam to vary the load on the grind - wheel, and electrically - controlled means connected to the input circuit of the motor and responsive to the flow of current in such circuit for moving the counterweight to and from the grinding-wheel. The grinding- wheel is reciprocated across a billet clamped on a reciprocating table 62 by mounting the beam on a shaft 21 carried by bearings which are reciprocated on shafts disposed parallel to the beam by a fluid-actuated cylinder-and-piston device; The counterweight 35 is movable by a fluid-actuated cylinder-and-piston device 43 in one direction or the other on the beam dependent upon which of two solenoids 169, 170, Fig. 11, operates a valve controlling the admission of fluid to opposite ends of the cylinder. Either solenoid is energized according to which of two sets of contacts 218, 219 or 220, 221 is closed by the armature 222 of a relay 216, the energizing coil 215 of which is coupled with the input of the motor through a circuit including a bridge rectifier 210, transformer 208, manually-variable resistor 205 in series with a fixed resistor 206, reactance 204 and transformer 203. The load on the motor and grinding-wheel are maintained substantially constant since, as with varying loads on the grinding-wheel the motor input current rises above or falls below a predetermined value, the armature 222 moves from a position in which neither solenoid is energized to one in which the appropriate solenoid is energized for moving the counterweight in compensating direction. Adjustment of the response of the control circuit is effected by adjusting the biasing spring 223 of the armature 222 or altering the setting of the resistor 204 by means of the handle; this handle also co-operates with switches so that only when it is out of the vertical is the counterweight under automatic control, and when vertical it energizes the solenoid 169 to move the counterweight to its most rearward position where it lifts the grinding-wheel completely from the billet and actuates a switch 199 to de-energize the solenoid. As the beam approaches the forward or rear end of its reciprocating stroke (and the grinding wheel nears the forward or rear edge of the billet), the counterweight is caused to move away from the grinding-wheel by movement of the armature 222 to energize the solenoid 169, such movement being effected by a cam on the beam opening one of two limit switches to deenergize a relay 195 and thereby introduce a resistor 234 into the control circuit; the rearward movement of the counterweight continues until it is stopped because the downward force on the grinding wheel is sufficiently reduced to enable the armature to resume its intermediate position.