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Inspection of Defects on the Roll Surface Using AC Magnetic Flux Leakage Method

Z.S.Lim
Research Institute of Industrial Science and Technology, P.O.Box 135, Pohang, Korea
D.R.Son
Physics Department, Hannam Univ., 133, Ojung-dong, Daejon, Korea
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ABSTRACT

INTRODUCTION

EXPERIMENTS

No. Len.(mm) Wid.(mm) Dep.(mm) Vol.(mm3) No. Dia.(mm) Dep.(mm) Vol.(mm3) Fig 4: Plate defect specimen
A1 9.79 0.272 0.435 1.146 D1 0.500 0.269 0.211
A2 9.79 0.272 0.380 1.012 D2 0.449 0.273 0.173
A3 9.79 0.099 0.250 0.233 D3 0.335 0.222 0.079
A4 9.79 0.132 0.185 0.256 D4 0.153 0.157 0.016
A5 9.79 0.189 0.090 0.167 D5 0.079 0.047 0.001
B1 4.92 0.237 0.444 0.556 E1 0.200 0.500 0.063
B2 4.92 0.263 0.352 0.452 E2 0.265 0.375 0.083
B3 4.92 0.081 0.213 0.100 E3 0.250 0.250 0.049
B4 4.92 0.165 0.180 0.125 E4 0.191 0.165 0.016
B5 4.92 0.191 0.082 0.077 E5 0.254 0.067 0.014
C1 2.00 0.248 0.356 0.177



C2 2.00 0.233 0.324 0.151



C3 2.00 0.211 0.253 0.108



C4 2.00 0.132 0.187 0.044



C5 2.00 0.169 0.094 0.033



Table 1: Dimensions of defects on HSS plate specimen

Roll Simulator
We have constructed a roll simulator to simulate a real situation. The outer diameter of HSS roll shell is 735 mm(Fig.5). The roll shell is rotated by 4 support rubber rolls with small diameter. The roll shell has 8 EDM defects(Table 2). The magnetic sensor is axially driven with 2 step motors with variable liftoff. In the following experiments the liftoff has been kept as small as possible.

Name Pos.(deg) Dir. Len.(mm) Wid.(mm) Dep.(mm) Fig 5: Shape HSS roll shell
D1 0 C 0.2 5.0 0.1
D2 45 C 0.2 5.0 0.2
D3 90 C 0.2 5.0 0.3
D4 135 C 0.2 5.0 0.4
D5 180 A 5.0 0.2 0.1
D6 225 A 5.0 0.2 0.2
D7 270 A 5.0 0.2 0.3
D8 315 A 5.0 0.2 0.4
Table 2: Dimensions of defects on HSS roll shell (A: axial, C: circumferential)

RESULTS AND DISCUSSION

CONCLUSION

REFERENCES

  1. P. Kumar and G.V.S. Murthy, "Ultrasonic evaluation of double poured rolls", NDT&E Int'l., 3, 1 (2000) 43-45
  2. W.Hill and E.Kerr, "Tool steel work roll maintenance at Dofasco", 37th MWSP Conf. Proc., ISS, Vol. XXXIII, 1996, 283-289
  3. H.Fujiwara, T.Suzuma, and T.Sakamoto, "Development of numerical analysis technique for alternating current magnetic leakage flux testing", JSNDI, 47, 2(1998), 127-133

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