Method of cutting a worm screw and a worm screw obtained by the said method
AssigneeEquipements Automobiles Marchal
InventorHubert A. Perraudin
Life of this patent
Estimating the term…
Abstract
A worm screw has two threaded portions of opposite hand cut on a single shaft, using a lathe. Several passes of the cutting tool are used to form each of these threaded portions, and in order to provide a compact and robust worm screw of this type the two threaded portions are separated by a groove having a depth shallower than that of the threads being cut and having a width at least equal to 15% of the greater axial pitch of the threaded portions.
Claims11
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).
Dependencies are inferred from the claim text.