Title:
COILED SPRING AND MANUFACTURING METHOD THEREFOR
Document Type and Number:
WIPO Patent Application WO/2013/115404
Kind Code:
A1
Abstract:
The purpose of the present invention is to provide a coiled spring exhibiting excellent fatigue resistance, while reducing material costs and simplifying the manufacturing process thereof without reducing yields. This coiled spring has, in mass%, 0.5-0.7% of C, 1.0-2.0% of Si, 0.1-1.0% of Mn, 0.1-1.0% of Cr, not more than 0.035% of P, and not more than 0.035% of S, the remainder comprising iron and unavoidable impurities. An arbitrary wire cross section includes, expressed as an area ratio, at least 65% of bainite, and 4-13% of retained austenite. The average C concentration in the retained austenite is 0.65-1.7%. When a cross-sectional circle equivalent diameter of the wire cross section is D (mm), a compressive residual stress layer is formed extending from a surface to within the range of 0.35mm-D/4, the maximum compressive residual stress is 800-2000MPa, the hardness at the centre is 50-650HV, a high-hardness layer which is 50-500HV harder than the hardness at the centre is formed having a depth from the surface in the range of 0.05-0.3mm, and both end surfaces are ground flat.
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Inventors:
KUROKAWA SHIMPEI (JP)
SUZUKI TAKESHI (JP)
ONO YOSHIKI (JP)
SHIBAIRI KOSUKE (JP)
SUZUKI TAKESHI (JP)
ONO YOSHIKI (JP)
SHIBAIRI KOSUKE (JP)
Application Number:
PCT/JP2013/052641
Publication Date:
August 08, 2013
Filing Date:
January 30, 2013
Export Citation:
Assignee:
NHK SPRING CO LTD (JP)
International Classes:
C22C38/00; C21D7/06; C21D9/02; C22C38/34
Domestic Patent References:
| WO2010110041A1 | 2010-09-30 | |||
| WO2012018144A1 | 2012-02-09 |
Foreign References:
| JP2011247276A | 2011-12-08 | |||
| JPS62110036A | 1987-05-21 | |||
| JPS63312917A | 1988-12-21 | |||
| JPH05320749A | 1993-12-03 |
Attorney, Agent or Firm:
SUENARI, Mikio (JP)
End 成 Mikio (JP)
End 成 Mikio (JP)
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Claims: