GB128907A - Improvements in and relating to Grinding Gauge-pieces and the like. - Google Patents

Abstract

128,907. Pratt & Whitney Co., (Assignees of Hoke, W. E.). June 28, 1918, [Convention date]. Block, rubber, and like apparatus.-Gaugeblanks are lapped between two ring-shaped laps 1, 2, the upper of which is capable of a free floating movement towards or away from the lower but is held against lateral oscillation. The blanks are mounted loosely in holes around the periphery of a thin disk 5, the spindle 6 of which is mounted loosely in the crank-arm of a driving-shaft. As this shaft rotates, the disk 5 is traversed across the face of the lap by the throw of the crank-arm, and the weight of the upper lap 1 acting upon the gauge blanks causes the disk to rotate about its spindle 6 once every five or six revolutions of the driving- shaft ; also each blank rotates about its own individual axis. The result of this compound circular and precessional movement is stated to be that all the gauge-blanks pass successively between all parts of the two lapping-surfaces, travelling in a continuous cycloid or spiral curve. Alternatively, the spindle 6 may be positively rotated in addition to having an eccentric throw imparted to it from the driving-shaft. Limit stops 4 may take the weight of the upper lap when the blanks have been ground to the required height; or an adjustable screw may be used to limit the approach of the two laps. The blocks are transferred symmetrically from their holes in the disk 5 at an intermediate stage of the lapping operation so as to ensure equal treatment. In operation, the whole lapping-device is immersed in a liquid bath kept at a constant temperature. In order to obtain gauges of a definite size with a high degree of accuracy, the following method of measurement is adopted; it is stated that all the pieces produced in one lapping operation are absolutely equal in height. Thirty-six pieces, say, are lapped in the first operation, and the whole of them are taken out from the disk from time to time and piled up to compare with a standard yard measure. When the pile exactly equals the yard measure, each is an exact inch, and ten of these mav be taken as a basis against which to measure one hundred other pieces formed all together in a second operation, to obtain a gauge exactly one-tenth of an inch in height, and so on.