Rolling die of ballscrew

Abstract

The roller for a ball spindle comprises a cylindrical section with a helical form protrusion formed in an outer circumferential face in order to form a helical ball track in the raw material of the spindle shaft, and a conical lead-in section formed in one end section of the cylindrical section and comprising a number of truncated cone shaped sections, the contact angle of which in relation to the raw material of the spindle shaft is established becomes continuously larger in the direction from the cylindrical section to the end of the lead-in section.

Description

technical field [0001] The invention relates to a rolling die of a ball screw, which is used for manufacturing a screw in the ball screw. Background technique [0002] Typically, the screw in a ball screw is formed from a rod-shaped screw blank made of metal and includes a helical ball groove formed therein. As a method for manufacturing such a screw, a method is disclosed in JP-A-9-133195 in which there is a rolling die 10 as shown in FIG. 7 . That is, a rolling die 10 is pressed against the screw blank w as shown in FIG. The rolling die 10 also includes a conical lead-in portion 13 and a conical exit portion 14 respectively formed at both ends of the cylindrical portion 12 . In this pressing state, one of the rolling die 10 and the screw blank w is rotated relative to the other, thereby rolling and machining a ball groove g on the screw blank w. The method disclosed in the cited publication is a so-called through-feed type rolling method using the through-feed phenomeno...

AI Technical Summary

Problems solved by technology

[0003] However, when a thread rolling die shown in FIG. 7 is used to manufacture a screw whose upper ball groove has a pitch larger than the ball diameter, that is, as shown in FIG. 9, the pitch p of the ball groove g on the screw bs It is 1.7 times or larger than the diameter dB of the ball b, which may make the amount of billet rolled by the thread rolling die larger each time

This will increase the possibility that the circularity deviation and shape transfer property of the ball grooves to be rolled and formed on the screw stock may be degraded, thereby failing to meet necessary technical requirements

In order to meet the necessary technical requirements, in the case of increasing the length of the introduction part of the rolling die to thereby reduce the amount of billet rolling per squeeze, the number of processing operations is increased, thereby causing the screw blank to harden through the processing operation, Thereby spalling may occur on the machined surface of the screw blank

[0004] Also, in the case of rolling and processing a ball groove on a screw blank using a rolling die shown in FIG. Concentration, which will shorten the durable life of the rolling die

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