Claims
- 1. A method of cutting, from a cylindrical shaft, a worm screw having two adjacent threaded portions with respective worm threads of opposite hand, said method comprising the steps of,
- (a) mounting the shaft in a lathe,
- (b) rotating the shaft with the lathe,
- (c) initially forming a groove in the shaft between the two adjacent threaded portions of the worm threads to be cut, said groove forming a zone of separation,
- (d) cutting a worm thread in the shaft of one hand, to one side of said groove, by successive similar passes of a cutting tool whose approaching motion at the beginning of each pass is effected in the grooved zone of separation between the two threaded portions,
- (e) cutting a second worm thread in the shaft of opposite hand, to the other side of said groove by successive similar passes of a cutting tool whose approaching motion at the beginning of each pass is effected in the grooved zone of separation between the two threaded portions,
- wherein the worm threads cut in steps (d) and (e) are each of a predetermined depth and pitch, and
- wherein said step (c) of intially forming the groove comprises forming a groove of a depth less than the depth of the threads but at least one half of the and two times the pitch of the threads formed in steps (d) and (e).
- 2. The method of claim 1, wherein said groove formed in step (c) has a cross-sectional profile which is an arcuate profile.
- 3. The method of claim 2 wherein the respective worm threads of opposite hand formed in steps (d) and (e) have the same pitch and depth, the worm threads are symmetrical about a transverse plane of the shaft; and the groove formed in step (c) is symmetrical in relation to said plane of symmetry.
- 4. A method according to claim 2, wherein the two worm threads formed in steps (d) and (e) each comprise a multi-start thread, the number of said thread starts being the same for said two worm threads.
- 5. A method according to claim 4 wherein for each of said two worm threads .phi./8.ltoreq.PA.ltoreq.3.phi./8 where .phi. is the external diameter of the cylindrical shaft before cutting the worm threads therein, and PA is the axial pitch of a worm thread cut in step (d) or (e).
- 6. A method according to claim 4 wherein for each of said two worm threads .phi./8.ltoreq.HF.ltoreq.3.phi./8 where .phi. is the external diameter of the cylindrical shaft before cutting the respective worm threads therein, and HF is the depth of a worm thread.
- 7. A method according to claim 1 wherein for each of said two worm threads .phi./8.ltoreq.PA.ltoreq.3.phi./8 where .phi. is the external diameter of the cylindrical shaft before cutting the worm threads therein, and PA is the axial pitch of a worm thread cut in step (d) or (e).
- 8. A method according to claim 1 wherein for each of said two worm threads .phi./8.ltoreq.HF.ltoreq.3.phi./8 where .phi. is the external diameter of the cylindrical shaft before cutting the respective worm threads therein, and HF is the depth of a worm thread.
- 9. The method of claim 1 wherein said groove formed in step (c) has a cross-sectional profile which is a triangular profile.
- 10. The method of claim 9 wherein the respective worm threads of opposite hand formed in steps (d) and (e) have the same pitch and depth, the worm threads are symmetrical about a transverse plane of the shaft; and the groove formed in step (c) is symmetrical in relation to said plane of symmetry.
- 11. A method according to claim 10 wherein the two worm threads formed in steps (d) and (e) each comprise a multi-start thread, the number of said thread starts being the same for said two worm threads.
Priority Claims (1)
Number |
Date |
Country |
Kind |
80 06581 |
Mar 1981 |
FRX |
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Parent Case Info
This is a continuation, of application Ser. No. 243,805, filed Mar. 16, 1981 and now abandoned.
US Referenced Citations (7)
Foreign Referenced Citations (3)
Number |
Date |
Country |
7636327 |
Jun 1978 |
FRX |
143995 |
Sep 1979 |
JPX |
648355 |
Feb 1979 |
SUX |
Non-Patent Literature Citations (3)
Entry |
How to Run a Lathe 42nd Edition 1942, J. J. & M. W. O'Brien, p. 80. |
Lathes vol. II 1963 by P. S. Houghton, p. 2. |
Machine Shop Practice vol. 1 Karl Moltrecht, Industrial Press Inc., N.Y., N.Y., pp. 275-281, 289-294. |
Continuations (1)
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Number |
Date |
Country |
Parent |
243805 |
Mar 1981 |
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