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Spring and spring processing method

  • US 8,069,881 B1
  • Filed: 04/27/2009
  • Issued: 12/06/2011
  • Est. Priority Date: 12/02/2004
  • Status: Active Grant
First Claim
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1. A residual stress enhancement method for a coil spring, said method comprising:

  • radially expanding a coil spring, said coil spring including an inner diameter portion exhibiting residual tensile stress and an outer diameter portion, said step of radially expanding said coil spring comprising using an expansion force such that said outer diameter portion is expanded radially from an initial size to an expanded size; and

    ,removing the expansion force from the spring such that the spring relaxes and becomes a processed spring comprising said inner diameter portion and said outer diameter portion, wherein said outer diameter portion of said processed spring defines a final size that is dimensioned between said initial size and said expanded size and said inner diameter portion of the processed spring comprises residual compressive stress.

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