GB1127434A - Improvements in grinding machines - Google Patents

Abstract

1,127,434. Grinding. CHURCHILL MACHINE TOOL CO. Ltd. 1 Dec., 1965 [1 Dec., 1964], No. 48731/64. Heading B3D. A grinding machine comprises a grinding wheel 12 adapted to be moved axially and radially relative to a rotatable workpiece 6, and gauging means 22, 23 having a signal output which is related to the difference between the actual diameter of the workpiece and a datum diameter, the signal output being adapted to determine the force which is applied in a radial direction to the grinding wheel in such a manner that at any one axial position of the grinding wheel relative to the workpiece any one value of the signal output produces a discrete and predetermined force, the response to the signal output being so arranged that a higher force is applied to the grinding wheel when the position of the workpiece being ground is substantially larger than the datum diameter, and a lower force is applied when the gauging means indicates that the workpiece is approaching the datum diameter. The datum diameter is varied along the length of the workpiece under the control of a tape so that the workpiece, such as a roll used in steel making or paper making has a barrel form. The workpiece is mounted between a workhead 2, Fig. 1 (not shown), and a tailstock 1 and is rotated by a motor 11 through reduction gearing 10 and a driving pin and plate 8, 9. The grinding wheel 12, which is mounted on a head 3 and driven from a motor 13, is supported on a sub-base 14 mounted at one end on a pivot 17 and at the other end supported by a rod 18 on a carriage 4 movable parallel to the axis of the workpiece along a base 5 by a rack-and-pinion mechanism 19, 20 driven by a motor. The wheelhead 3 is adjustable relative to the sub-base perpendicular to the axis of the workpiece by a screw and handwheel 15, 16. The carriage 4 also has a pivot 24 and hinge 25 supporting a caliper frame 21 having at its upper end, a probe 23 which is in continuous contact with the workpiece and is vertically adjustable relative to the caliper frame 21 by a worm-and-wheel mechanism 36, 37 movable in one direction or the other to raise or lower the probe by stepping mechanisms 32, 33 operated by signals in lines 34, 35 connected to the reading head 26 of the tape 27. The lower end of the caliper frame carries a gauge head 22 supplied with air through a regulator 39, restriction 40 and line 42 which is also connected to a cylinder 43 containing a flexible bellows 44 supporting the rod 18, the interior of the bellows being connected by a passage 45 to atmosphere. The carriage 4 has a switch 28 which is actuated at each oscillation of an arm 29 caused by a roller 51 moving over teeth or notches 31 on a plate secured to the base 5 as the carriage moves along the base to feed the tape 27 through the reading head so successive characters on the tape are read by the head as the carriage moves along the base, each character being associated with a respective notch 31 and being arranged to operate one or other of the stepping mechanisms 32, 33. In operation, as the carriage moves along the base, the arm 29 is oscillated to actuate the switch 28, each actuation causing the tape to be fed stepwise through the reading head which, according to the character read, sends a signal along line 34 or 35 to operate one or other of the mechanisms 32, 33 to raise or lower the probe according to the position of the carriage along the base. The movement of the probe determines the distance 41 between the gauge head 22 and workpiece and the pressure in line 42. If the distance 41 is small, the pressure in line 42 is relatively high and acts in cylinder 43 to compress the bellows and consequently force the sub-base 14 about pivot 17 so that the grinding wheel is forced against the workpiece. As the diameter of the workpiece is reduced to approach the datum diameter for the axial portion of the workpiece, the distance 41 increases and the pressure in line 42 and cylinder 43 decreases resulting in a reduction in the force between the grinding wheel and workpiece. The movement of the sub-base 14 relative to the carriage 4 is damped by a dashpot comprising a double piston 49, Fig. 3 (not shown), carried by the sub-base co-operating with a pair of chambers 47 which are mounted on the carriage, connected by a capillary tube 48, and contain a suitable liquid.