WCA July 2011

Parameters of crack

V-shaped, concave shaped, U-shaped cracks

Shape-related parameter

Depth (h)

0.10, 0.35, 0.60, 1.0mm

Breadth (a)

0.73, 0.93, 1.15, 1.40mm

Angle ( θ )

60º, 70º, 80º, 90º, 100º, 110º, 120º

Direction

Circumferential direction

Material condition for wire

Material

SUS304

Young’s modulus

206GPa

Diameter

10mm, 8mm

α =6º, R/P=20%

Die half angle, reduction

Friction factor

0.05μm

❍ ❍ Table 3 : Parameters of crack

2) It is thought that there is a danger of wire breakage when Di/Do is 0.3 or higher, and that the highest frequency of wire breakage is where Di/Do is approximately 0.7. This was found to be because drawing stress moves rapidly upward when an inclusion passes through the die 3) The result of FEM analysis agrees with the experi- mental result; therefore, it is possible to estimate crack deformation behaviour by FEM analysis to predict the state after drawing 4) The mechanism underlying the removal of a crack in a wire rod is the rise of the bottom of the crack during drawing 5) The behaviour of a U-shaped crack during drawing depends on the depth (h) 6) Where there is a greater depth, however, the right side of the crack is tilted so that it overhangs the left side and forms an overlapping crack (defect), indicating that the crack cannot be removed by drawing. Moreover, a deep crack develops in the wire, although it appears to be small This paper was presented at Istanbul Cable & Wire ’09. It is reproduced here by kind permission of the IWMA and WAI. 1 H Tanaka et al, “Analysis of copper wire breaks,” Furukawadenko- jihou, Volume 59, 1976, pp 91-98 2 J Togasi et al, “An analysis of copper wire breaks during drawing,” Furukawadenko-jihou, Volume 66, 1979, pp 25-32 3 T Yamasita and K Yoshida, “Classification of wire breaks and countermeasures in superfine gold wire drawing,” Wire Journal International, March 2005, pp 180-184 4 T Yamasita and K Yoshida, “Analysis and prevention methods for wire breaks in ultra-fine gold wire drawing,” Wire Journal International, March 2007, pp 200-203 5 K Yoshida, “FEM analysis of wire breaks in drawing of superfine wire with an inclusion,” Wire Journal International, March 2000, pp 102-107 6 The Japan Society for Technology of Plasticity, Drawing, Corona sha Co Ltd 1990, pp 68-73 7 Standardization Committee of the Iron and Steel Institute of Japan, Definition of surface crack for steel rods, 1987 8 T Shinohara and K Yoshida, Iron and Steel, Volume 90, No 12, 2004, p 31 9 T Shinohara and K Yoshida, “Effect of rolling and drawing of rod wires on removal of surface cracks”, Wire Journal International, Volume 37, 2004, pp 52-57 References

10 The Japan Society for Technology of Plasticity, Drawing, Corona Co, Ltd p 14 and p 69 11 K Yoshida and Y Shinohara, Prediction of Surface Micro-Defects in Plate Rolling, No 9690, Current Advances in Materials and Processes, 2004, pp 11-14

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Wire & Cable ASIA – September/October 2007 July/August 2011