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).
Conclusions and test results on the manufacturing and performance of worm gears.
| Identifier | ExFiles\Box 153\2\ scan0356 | |
| Date | 15th July 1937 guessed | |
| -10- Attempts have been made to grind the worm, with an arrangement approaching steering conditions, but with little success. The lapping of worms has also been attempted with more success, the worm being subjected to cutting conditions with a lap of cork and an abrasive compound being the method of operation. CONCLUSIONS. As the cost of hourglass worms produced for us is excessive, it is suggested that the necessary machine for worm shaping and testing is purchased. The estimated time to cut a piece similar in design to our own is, 6 minutes roughing, and 5 1/2 minutes finishing, with allowance made for side trimming after cutter re-grinding. The saving effected by a thread generator for roughness would not vouch for its purchase, considering that an hourglass gear shaper could produce approximately 200 worms per week working the machine with a 80% efficiency. [Handwritten note: Trufc out] The cost of a suitable machine is approximately $7000 with a guide cost of $250 each. The cost of a Red Liner testing machine would be $1800. All other operations may be performed on conventional machines, so that only tool costs would be necessary. TEST RESULTS ON ADAMANT WORMS. The 25/30. worms showed very bad worm form when tested on a Red line machine, the point of centre contact was .003 to .004 lower than the contact points at 1/4 turn in either direction, with a distinct well in the profile, amounting to .005 to .007 at 1 to 1 1/4 turns of the worm. The surface contact produced a general unevenness of .001 which may be traced to the climbing action of the cutter by the process used. The general contour of the Phantom III. type worm was good but surface undulations were of a similar nature. | ||