| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for cold drawing of a steel pipe adapted for inhibiting uneven thickness possibly occurring after cold drawing, to achieve improved accuracy of outer diameter and thickness. <P>SOLUTION: The cold drawing is performed under the conditions that meet the following equations (1): 20(%)≤R<SB POS="POST">D</SB>≤35(%) and (2): 5(%)≤R<SB POS="POST">T</SB>≤25(%), where R<SB POS="POST">D</SB>(%) denotes the degree of processing of the outer diameter and R<SB POS="POST">T</SB>(%) denotes the degree of processing of the thickness on a thick wall side in performing cold drawing. In the equations, R<SB POS="POST">D</SB>=100(D<SB POS="POST">0</SB>-D)/D<SB POS="POST">0</SB>, and R<SB POS="POST">T</SB>=100(T<SB POS="POST">0</SB>-T)/T<SB POS="POST">0</SB>, in which D<SB POS="POST">0</SB>and D stand for the outer diameters (mm) before and after the cold drawing, respectively, and T<SB POS="POST">0</SB>and T stand for the thicknesses (mm) before and after the cold drawing, respectively. It is desirable to perform a drawing process under the condition that meets the equation R<SB POS="POST">T</SB>/R<SB POS="POST">D</SB>≤0.5 in addition to the equations (1) and (2). <P>COPYRIGHT: (C)2012,JPO&INPIT |
