BALL SCREW - NSK LTD

Title:

BALL SCREW

Document Type and Number:

WIPO Patent Application WO/2006/104015

Kind Code:

A1

Abstract:

A ball screw suitable for use under high load, which is used particularly in an electric injection molding mechanism and in which damage and wear of balls are reduced as compared to conventional products to provide the ball screw with long lifetime and high reliability. The ball screw is characterized in that the balls have surface hardness higher than that of a ball groove of a screw shaft and that of a ball groove of a nut, and that a solid lubricant film having a thickness of not less than 1 μm and not more than 5 μm is formed on the surface of the balls. The grooves (11, 21) of the screw shaft (1) and the nut (2) have a Gothic arch-like cross-section. The ratio (R/D) of the radius (R) of the cross-sectional circular arc of the groove (11) to the diameter (D) of a ball (2) is set to not less than 51.0% and not more than 52.0%. A solid lubricant coating composed of MoS₂ and having a thickness of not less than 0.5 μm and not more than 3.0μm is formed on the surface of a ball (3).

Inventors:

TAKAHASHI DAIJU

Application Number:

PCT/JP2006/305850

Publication Date:

October 05, 2006

Filing Date:

March 23, 2006

Export Citation:

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Assignee:

NSK LTD (JP)
TAKAHASHI DAIJU

International Classes:

F16H25/22; F16C33/372; F16C33/44; F16H25/24; F16H29/06

Foreign References:

JP2005003103A	2005-01-06
JP2005009649A	2005-01-13
JP2003301916A	2003-10-24
JP2004060742A	2004-02-26
JPH06109022A	1994-04-19
JP2003336638A	2003-11-28
JP2003232421A	2003-08-22
JP2000346162A	2000-12-12
JP2004060742A	2004-02-26
JP2001049274A	2001-02-20
JPH06109022A	1994-04-19
JPH11315835A	1999-11-16
JP2004092787A	2004-03-25
JPS62283252A	1987-12-09

Other References: