Patent GB-1085976-A (GB)
Title: Projection form grinding machine
IPC: G01B5/00
Filed: 1965-04-15
Abstract: 1,085,976. Grinding. A. KOLB. April 15, 1965 [April 16, 1964; Sept. 18, 1964], No. 16291/65. Heading B3D. A projection form grinding machine comprises a workpiece clamping plate carried by a slide movable relatively to a stationary member, the difference, if any, between the distance travelled by the plate and a known distance traversed by the slide being measured or compensated for by means of a calibrated template mounted on the slide and engaged senser associated with the stationary member. The plate 2 has clamps 3 for holding a workpiece 1 which is to be ground by a grinding wheel 5 and viewed through an objective 4, the profile to be formed on the workpiece having a number of shapes each of which when viewed on the screen of the projector may practically fill the screen and the distance apart of adjacent shapes is greater than the dimension of the screen. To move the workpiece so that the shapes can be ground thereon by the grinding wheel 5, the place 2 is secured to a slide to which the template 11 is fixed and which incorporates subdividing means 6. The latter consists of a stop 8, an abutment member 9 and a gauge 10, and end gauges 7 can be inserted between a wedgeshaped member 8a associated with the stop and the abutment member 9 to determine the distance the slide and hence the workpiece is moved. The wedge-shaped member 8a is urged by a spring against the template which is mounted on the slide at a point 12 and is adjustable by an eccentric 13. The compensating template is produced by clamping an end gauge of a predetermined length on the stage 2 in place of a workpiece and a similar end gauge or combination of end gauges 15 having the same length between the wedge-shaped member 8a and abutment member 9. One end of the end gauge on the stage 2 is then aligned with a line on the screen and the gauge 10 set to zero, the template 11 at this time having a straight surface so that when the slide is moved, the gauge shows no deflection. The plate and slide are then moved so that the other end of the gauge on the plate is aligned with the line on the screen, the end gauge 15 being removed. Any error indicated on the gauge 10 is corrected by grinding the template so that the wedge-shaped member moves to a position setting the gauge 10 to zero. This process is repeated with end gauges of different lengths until the template is formed with a curve which corrects the machine for all positions of the slide and plate. To compensate for the different loading of the plate and slide when attachments, such as for the grinding of round workpieces, are mounted on the machine, the attachments having different weights and loadings, the template can be adjusted by the eccentric 13 which is marked to indicate the various weights and loadings. In another embodiment, the wedge shaped member is replaced by a gauge secured to the stop to indicate the error which is then compensated by moving the plate until the gauge indicates the error shown on the first gauge. In a further embodiment, the error to be compensated is transferred from the template to the gauge or an electrical precision senser by a ball crank lever. In other embodiments, the movement of the slide is determined not by end gauges but by a scale which may be attached to the slide or a stationary part and co-operates with a cross wire or optical reading objective.