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).
Production methods and heat treatment for manufacturing gear blanks.
| Identifier | ExFiles\Box 94\2\ scan0276 | |
| Date | 9th August 1937 | |
| -3- Lead distortion could not be obtained, but it was evident from the lapped teeth that this had not been excessive. The bedding of mating teeth, for helix angle was observed to be good. It should be noted that slight modifications were incorporated upon the helix angle to facilitate the use of existing guides, but which closely approximate the existing design. PRODUCTION METHODS EMPLOYED. The machining of the gear blanks was conducted in a conventional manner with the exception of the gear cutting and lapping, which was employed as alternative to our own methods. The cutting was performed upon a gear shaper roughing out and finishing in two cutting cycles, while the piece was in position upon the machine. The method is similar to that employed by the Dodge Motors and other members of the Chrysler Corporation, and should not be confused with the shaving process. After hardening of the finish out blanks, lapping was used as the refining process, being performed upon a machine using three lapping gears and applying axial movement to the blank under process. The effect of such an operation is inclined to be severe upon form, but enables correction of helix angle to be effected. The adoption was incorporated of a type of tooth chamfering, which generated the ends of the gear teeth in involute form, and thus allowed involute action during the interval of entry when meshing mating gears. This operation was performed upon a gear shaper using helical guide and involute generating cutter, with helix angle of the guide at approximate 45° to the lead angle of the gear. The splined bores of the gears were produced soft as an aid to production and saving in production costs. TREATMENT EMPLOYED UPON BLANKS. The material employed was an S.A.E. 4620 material forged into blanks to suit the pieces being produced. The forgings were normalized and rough machined before being subjected to a simple strain annealing at a temperature of 1150°F.{Mr Friese} Continued...... | ||