Title:
HELICAL COMPRESSION SPRING AND METHOD FOR MANUFACTURING SAME
Document Type and Number:
WIPO Patent Application WO/2014/042066
Kind Code:
A1
Abstract:
Provided are: a highly-durable helical compression spring that is produced using inexpensive wire rod by eliminating tensile residual stress caused by coiling, and forming a carbon concentrated layer on the surface of the wire rod to impart an appropriate compressive residual stress distribution; and a method for manufacturing the helical compression spring. The helical compression spring is characterized by: using steel wire rod containing, in wt%, 0.45 to 0.80% carbon, 0.15 to 2.50% silicon, and 0.3 to 1.0% manganese, with the remainder comprising iron and unavoidable impurities, said steel wire rod having an equivalent circle diameter of 2.5 mm to 10 mm; having an internal hardness of 570 to 700 HV in an arbitrarily-defined cross section of the wire rod; having a carbon concentrated layer in which the carbon exceeds the average concentration of carbon contained in the steel wire rod in the surface layer; and having an unloaded compressive residual stress greater than or equal to 200 MPa on the inner diameter side of the coil spring at a depth of 0.2 mm from the surface of the wire rod in substantially the direction of maximum principal stress when a compressive load is applied to the spring; and an unloaded compressive residual stress greater than or equal to 60 MPa at a depth of 0.4 mm from the surface.
Inventors:
ONO YUITIROU (JP)
SHIRAISHI TOHRU (JP)
ONO YOSHIKI (JP)
TAKAHASHI KEITA (JP)
SHIRAISHI TOHRU (JP)
ONO YOSHIKI (JP)
TAKAHASHI KEITA (JP)
Application Number:
PCT/JP2013/073937
Publication Date:
March 20, 2014
Filing Date:
September 05, 2013
Export Citation:
Assignee:
NHK SPRING CO LTD (JP)
International Classes:
C22C38/00; B21F3/02; B21F35/00; B24C1/10; B24C11/00; C21D1/06; C21D7/06; C21D8/06; C21D9/02; C22C38/04; C22C38/54; C23C8/22; C23C8/80; F16F1/06
Foreign References:
JP2012077367A | 2012-04-19 | |||
JP2001082518A | 2001-03-27 | |||
JPH0586418A | 1993-04-06 | |||
JPH01177318A | 1989-07-13 | |||
JPH0499126A | 1992-03-31 | |||
JPS56152921A | 1981-11-26 | |||
JP2000326036A | 2000-11-28 | |||
JP2008045178A | 2008-02-28 | |||
JP5064590B1 | 2012-10-31 | |||
JP3595901B2 | 2004-12-02 | |||
JP2009226523A | 2009-10-08 |
Other References:
See also references of EP 2896712A4
Attorney, Agent or Firm:
SUENARI, Mikio (JP)
End 成 Mikio (JP)
End 成 Mikio (JP)
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