Patent GB-1038065-A (GB)
Title: Improvements in or relating to a control system for surfacing apparatus
IPC: B23Q15/007
Filed: 1963-04-23
Abstract: 1,038,065. Grinding. ALLEGHENY LUDLAM STEEL CORPORATION. April 23, 1963 [May 2, 1962], No. 16056/63. Heading B3D. In apparatus for removing a surface of a workpiece and including a surfacing tool such as a grinder with a grinding wheel, the tool is arranged to be driven relative to the workpiece in both senses of a first direction and in one sense of a second direction transverse to the first direction by independent respective power sources, both directions being parallel to the plane of the surface, so that the tool removes the entire surface of the workpiece, and first direction control devices are provided for automatic actuation at selected limits of relative movement in one or both senses of the first direction, the control devices being electrically connected to the means that drives the relative movement in the second direction so that when the tool actuates the selected control device relative movement is carried out in the second direction by an increment of the total required second direction movement and the sense of the movement in the first direction is reversed, and the said reversal and incremental movement is repeated each time the tool reaches the selected limit(s) of its first direction until the entire surface of the workpiece has been traversed by the tool. A slab 10 to be ground is positioned on a stationary support or a table comprising frame members 12. The grinding apparatus comprises a carriage 19 mounted for reciprocating movement on tracks 14, 16 by wheels 32, 34 driven by a reversible hydraulic motor 66. The carriage 19 has at one end an operator's platform 20 with a seat 22. Above the platform 20 is a control console 24. A transparent shield 28 extending upwardly on one side of the platform 20 protects the operator from flying pieces of hot metal. Adjacent the platform 20, on the side opposite the shield 28, is a control box 30 housing the electrical control apparatus. A trunnion 36 mounted on the carriage 19 carries a boom structure 38 for pivotal movement. The boom structure includes a column 40 surrounded by a bellows 42 and carrying at its forward end a grinding-wheel 44. A platform 46 adjacent the boom structure can reciprocate on guideways 48 and carries an electric motor 50 rotating the grinding wheel through gear reducer 52 and belt drive 54. Hydraulic piston/ cylinder means 58 simultaneously reciprocates the column 40 and the platform 46. A housing 56 on the rearward end of the boom structure encloses a counterweight actuated by the piston/ cylinder means 58 such that when the grinding wheel moves outwardly the counterweight moves outwardly in the opposite direction to produce the desired balancing effect to maintain constant the downward force on the grinding wheel. A downward force is exerted on the column by a second hydraulic piston/cylinder means 60 connected to the boom structure 38. A pump 64 supplies hydraulic pressure for means 58, 60 and a metering means 62; a pump 68 supplies hydraulic pressure for the motor 66; the pumps 64, 68 are driven by an electric motor 70. Means 58 has associated therewith a valve 78 actuated in opposite directions from a central position by solenoids 82, 86. Means 60 has associated therewith a valve 92 actuated in opposite directions from a central position by solenoids 94, 96. Metering means 62 has a stroke limiting adjustable stop 122, and has associated therewith a valve 108 actuated in one direction from a normal position by a solenoid 114. The motor 66 has associated therewith a valve 128 activated in opposite directions from a central position by solenoids 134, 140. With MANUAL switch 152 closed, operation is under the control of switches M1, M2, M3, M4, M5, M6 closure of which energizes respectively solenoids 82, 86, 96, 94, 140, 134. The operator manipulates the switches to cause the carriage 19 to move to and fro parallel to the long dimension of the slab and the grinding wheel to move inwardly or outwardly parallel to the short dimension of the slab until the entire surface has been ground. With AUTOMATIC switch 160 closed, a cycle is started by depressing START push-button 166. The cycle proceeds under the control of limit switches LS1, LS2 adjustably positioned on the track 16 and actuated by the carriage 19, and limit switches LS3, LS4 adjustably positioned on the carriage 19 and activated by a projection on the carriage 46. The carriage is automatically reversed at the ends of its stroke and the grinding wheel is cross-fed in increments at one or both ends of the slab, depending on whether switch 237 is open or closed. Grinding can be interrupted by a STOP push-button 188. The limit switches LS-1 to LS-4 may be replaced by bridge circuit arrangements wherein one arm of the bridge comprises a potentiometer connected to the wheels 32, 34 or the boom so that at a predetermined location of the wheels and/or boom the bridge produces an output signal to trip a relay closing or opening contacts.