GB1253512A - Improvements in or relating to grinding apparatus - Google Patents

Abstract

1,253,512. Grinding glasses. C. C. MAYERS. 29 Nov., 1968 [29 Nov., 1967], No. 54380/67. Heading B3D. A glass grinding machine comprises means 17 to hold a glass or tumbler with the outer surface or part thereof to be cut unobstructed, a grinding wheel 51 rotatable about an axis in a plane parallel to a tangent to the glass or at a small angle thereto, means to rotate the axis of the grinding wheel in the plane to alter the plane of rotation of the wheel, the glass holder being supported on a vertical spindle 56 and the holder and wheel being relatively movable in directions axially of the glass and towards and away from one another, drive means to rotate and move the spindle along its axis and to move the grinding wheel towards and away from the axis, and means to control the drive means in response to a predetermined programme. The machine consists of a frame 11, the lower part 12 of which carries a vertically adjustable grinding unit having two grinding wheels 51, 51a for acting on diametrically opposite parts of the glass, and the upper part of which carries a vacuum-holding means 17 for the glass, the holding means being transversely movable to convey glasses between a conveyer 18 and a working position. The grinding unit comprises two heads 21, 22, Fig. 2, each vertically adjustable by a screw jack 23, 23a. Each unit has a table 24 on which is a further table 27 adjustable for limited rotation. A pair of guide rails 29 extend between abutments 32, 33 on the table 27 and support a slide member 31 movable by piston unit 34. Slide member 31 carries a pair of supports 38, 39 for a shaft 41 carrying a support 47 for a motor 49 driving the grinding wheel 51. A gear 42 on the shaft 41 engages a rack 43 movable by an hydraulic ram 44 to effect adjustment of the plane of the grinding wheel. The work-holder 17 consists of a vertical spindle 56, Fig. 5, mounted for axial and rotary movement in a bearing 63. The lower end of the spindle carries a disc 58 for engaging the upper rim of the glass 10 which is held on the disc by a vacuum source connected to a passage 61. The upper end of the spindle is rotatably mounted in a plate 64 and is rotatable by gearing from an electric stepping motor 66. The spindle is vertically movable in the bearing 63 by an hydraulic ram 68, and the bearing 63 is slidable along a horizontal guideway by a ram to move the spindle between an operative position between the grinding wheels and a position over the conveyer 18. A template 74, Fig. 4, corresponding to the shape of the glass 10 is carried by the plate 64 and engaged by the feeler 77 of a master cylinder 76 connected to a slave cylinder 78, the rod 79 of which carries a micro-switch 81 having a lever 80 engaging the member 33 and controlling the supply to the units 34, 34a In operation, glasses are fed to the machine intermittently by the conveyer 18. The ram moves the spindle 56 to a position over a glass and the spindle is lowered by ram 68 to engage the disc 58 with the glass. Vacuum is applied to hold the glass on the disc and the spindle raised. If the glass is not securely held the lowering of the spindle is repeated. With the glass securely held, the spindle, after being raised, is moved to position the glass between the grinding wheels. The grinding wheels are, at this time, in their retracted positions and have been adjusted by the rams 44, 44a to be tilted at a desired angle relative to the axis of the glass. High pressure fluid is supplied to the piston units 34, 34a to rapidly advance the grinding wheels until feeler 77 contacts the template 74 which occurs just before the grinding wheels engage the glass. Low pressure fluid then advances the grinding wheels into engagement with the glass. The grinding wheels cut a line pattern in the glass as the spindle 56 is raised and lowered by ram 68, the grinding wheels following the contour of the glass under control of the template 75, and the spindle is rotated by the stepping motor 66. The stepping motor is also controlled to index the glass after each line has been cut to form a pattern on the glass. The grinding wheels may be tilted to an opposite position so as to cut lines diagonal to those already cut. Control of the stepping motor 66 is effected by a second stepping motor rotating an arm actuating a plurality of switches, the stepping motor 66 rotating the tumbler through a first angle and back through a second smaller angle to effect the indexing. The motors and rams are controlled automatically by an electrical circuit. In another embodiment, the feeler 77 adjacent a grinding wheel senses the shape of the glass to control the movement of the grinding wheels, the sensor being in the form of an air pipe.