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Authors: Akira Azushima, Yoshifumi Nakata, Takahiro Toriumi

Paper: Prediction of effect of rolling speed on coefficient of friction in hot sheet rolling of steel using sliding rolling tribo -simulator. Authors: Akira Azushima, Yoshifumi Nakata, Takahiro Toriumi. Presenter: Gary Hedberg Date: September 11, 2009. Introduction.

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Authors: Akira Azushima, Yoshifumi Nakata, Takahiro Toriumi

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  1. Paper: Prediction of effect of rolling speed on coefficient of friction in hot sheet rolling of steel using sliding rolling tribo-simulator Authors: Akira Azushima, Yoshifumi Nakata, Takahiro Toriumi Presenter: Gary Hedberg Date: September 11, 2009

  2. Introduction • Need To Solve Problems of Increased Rolling Force, and Friction Pick Up in High Reduction Hot Rolling • Use of Lubricants Has Been Common Since the 1970’s • Measure the Effect of Lubricants on Hot Rolling at Different Rolling Speeds

  3. References • Azushima, A., Xue, W.D., Aoki, K., 2006. New evaluation method of lubricity of hot rolling oil. In: 9th International Conferences on Steel Rolling 2006, ATS, CD-ROM,S04-2 P103. • Azushima, A., Xue, W.D., Aoki, K., 2007a. Lubricant mechanism in hot rolling by newly developed simulation testing. Annals of the CIRP 56 (1), 297–300. • Azushima, A., Xue, W.D., Yoshida, Y., 2007b. Influence of lubricant factors on coefficient of friction and clarification of lubricant mechanism in hot rolling. Tetsu-to-Hagane 93 (11), 27–32 (in Japanese). • Azushima, A., Xue, W.D., Yoshida, Y., 2008. Effect of surface roughness of roll on coefficient of friction in hot rolling. Tetsu-to-Hagane 94 (4), 134–140 (in Japanese). • Ikeda, J., 1999. Recent trends in hot strip rolling oil. J. Jpn. Soc. Technol. Plast. 40, 1031–1036 (in Japanese). • Inoue, T., Yamamoto, H., Watanabe, K., Nishida, K., Sugiura, T., 2003. Lubricity characteristics of particles mixed with organic and inorganic powders and their seizure prevention effect at high temperature. J. Jpn. Soc. Technol. Plast. 44, 266–270 (in Japanese). • Kiuchi, M., 2005. Integrated development of metal forming technologies for ultra-fine grained steel, advanced technology of plasticity 2005. In: Proc. 8th ICTP, pp. 55–70. • Lenard, J.G., 2000. Tribology in metal rolling. Annals of the CIRP 49 (2), 567–590. • Mase, T., 1979. Lubricants for hot rolling of strip and the effects by using them. J. Jpn. Soc. Lubr. 24 (3), 144–149 (in Japanese). • Nagai, K., 2003. Recent developments for ultrafine-grained steels. Q. Jpn. Weld. Soc. 21, 142–147 (in Japanese). • Sato, K., Uesugi, H., Hagihara, H., Nogami, T., 1978. Correlation between chemical composition and efficacy of hot rolling oils for steel strips. Journal of the JSTP 19 (214), 942–949 (in Japanese).

  4. Models and Design Principles • Simulation Testing Machine (Created by Authors) • Measured: • Rolling Force - P • Torque of Upper Roll - G • Radius of Upper Roll - R • Calculated: • Coefficient of Friction: μ = G/(PR)

  5. Models and Design Principles Specification of simulation testing machine for hot rolling. • Velocity of main roll, U ≤207 m/min • Ratio of velocity, rv 6.3–24 • Velocity of sub roll, V ≤8–32 m/min • Rolling load, P ≤200kN • Rolling torque, G ≤800Nm • Temperature of furnace, Tf ≤1100 ◦C • Forward tension, TF ≤3.5kN

  6. Models and Design Principles • Infrared Image Furnace used • Three types of upper rollers used with different surface roughness (Ra= 0.05, 0.2, 0.8 μm) • Rolling reduction of 0.3mm used • Roll speed between 15 & 70 m/min • Colza oil is used in 0.1 & 3% @ 40°C • Statistical process for collection of data is not mentioned in the article

  7. Results Ra = 0.05 μm • For Ra = 0.05 μm : • Coefficient of friction is independent of the rolling speed at 3% emulsion concentration • Coefficient of friction decreases with increasing rolling speed at 0.1% emulsion concentration • Scaling and Cracking similar to each other at all speeds for 3% emulsion • Color is noted as uneven for speeds of 15 & 30 m/min for the 0.1% emulsion

  8. Results • For Ra = 0.2 μm : • Coefficient of friction is independent of the rolling speed at 3% emulsion concentration • Coefficient of friction decreases with increasing rolling speed until around 50 m/min at 0.1% emulsion concentration • Scaling and Cracking similar for all 3% emulsion to that of Ra = 0.05 μm • Plowing tracks are observed on all speeds except 50 m/min for the 0.1% emulsion Ra = 0.2 μm

  9. Results • For Ra = 0.8 μm : • Coefficient of friction is independent of the rolling speed at 3% emulsion concentration with values larger than those of Ra = 0.05 & 0.2 μm • Coefficient of friction increases with increasing speed and is also larger than those of Ra = 0.05 & 0.2 μm at 0.1% emulsion concentration • Plowing tracks are observed on all speeds for all emulsion concentrations • Failure on the track surface is observed at the 70 m/min and 0.1% emulsion Ra = 0.8 μm

  10. Results • The Authors Propose the following models • For Ra = 0.05 μm & 3% emulsion : μ=μb • For Ra = 0.8 μm & 3% emulsion : μ=μb+μpa Where subscripts b & p stand for adhesion and plowing • For 0.1% emulsion: Several complex equations given for different speeds

  11. Conclusions • Very Limited Industrial Use • Presents equations to calculate μ when using lubricants • Equations not yet verified • Lubricant greater than 1% shown to lower coefficient of friction for Hot Rolling • Impacts companies looking to develop ultra-fine grain steels using high reduction

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