From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Issues with gearcutting and lapping processes, with conclusions for camwheel and crankcase production.
| Identifier | ExFiles\Box 136\1\ scan0175 | |
| Date | 15th January 1936 | |
| -2- RHC{R. H. Coverley - Production Engineer}/RH{R. Hollingworth}8/ETM.15.1.36. No attempt is made to true up the wheel relative to the finally ground taper bore prior to gearcutting, and it is very important this should be done and a suitable operation included in the Op. List. GEARCUTTING. The present method of setting up is to locate off the bore and clamp the wheel sideways between plates. This has the effect of pulling the wheel back into shape whilst gearcutting, but distortion reappears on releasing the wheel on completion of the operation, with the result that tooth bedding is uneven. An error of .002" is accepted on all operations affecting the outside diameter - this should not be permitted. The condition of the gearcutting tackle in general was found to be very poor, but this is now receiving attention. LAPPING OF GEARS. The lapping rigs are badly in need of overhaul and spindles require checking for alignment and parallelism. At the moment both machines in use have a piece of bonus card inserted between slides under the headstock in order to throw the bedding and as this is a regular practice it is obvious that either the lapping rigs or gearcutting are consistently inaccurate. The method of procedure is - gears are lapped and "passed off" to engine erecting, the engine isrun for a short time on the rig, gears are removed and the heavy marks eased with No.2 Emery cloth. Gears are then reassembled and the above procedure repeated, again using No.2 Emery Cloth to relieve hard bedding. The tooth bedding is so very uneven as to make it impossible to correct by lapping and the only way to eliminate the present practice of stoning and polishing would be to introduce ground gears. CONCLUSIONS. The production of camwheels requires speci al attention and revision of machined operations is necessary so as to ensure that distortion is rectified before gearcutting. The crankcase casting requires stiffening up around auxiliary drive housings and since the water pump and dynamo gears are, next to the camwheel, the chief offenders as regards noise, it is suggested that layout of auxiliaries should be reconsidered in order to see whether these two gears could not be dispensed with and use made of the idler gear. The fixture for reaming and facing of crankcase bores should have provision for more positive location of crankcase. RHC.{R. H. Coverley - Production Engineer} | ||