Article
Sliding Mode Control with Sliding Perturbation
Observer-Based Strategy for Reducing Scratch Formation in
Hot Rolling Process
†
Hyun-Hee Kim
1
, Sung-Jin Kim
1
, Sung-Min Yoon
2
, Yong-Joon Choi
3
and Min-Cheol Lee
4,
*
Citation: Kim, H.-H.; Kim, S.-J.;
Yoon, S.-M.; Choi, Y.-J.; Lee, M.-C.
Sliding Mode Control with Sliding
Perturbation Observer-Based Strategy
for Reducing Scratch Formation in
Hot Rolling Process. Appl. Sci. 2021,
11, 5526. https://doi.org/10.3390/
app11125526
Academic Editor: Giovanni Boschetti
Received: 20 April 2021
Accepted: 29 May 2021
Published: 15 June 2021
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1
Division of Robotics Convergence, Pusan National University, 2, Busandaehak-ro 63beon-gil, Geumjeong-gu,
Busan 46241, Korea; sleepingjongmo@gmail.com (H.-H.K.); jins2410@gmail.com (S.-J.K.)
2
Ronfic Co., Inc., 34, Yutongdanji 1-ro 57beon-gil, Gangseo-gu, Busan 46721, Korea; tactics1019@gmail.com
3
POSCO Technology Research Lab, 6267, Donghaean-ro, Nam-gu, Pohang-si 37859, Korea; cyj@posco.com
4
School of Mechanical Engineering, Pusan National University, 2, Busandaehak-ro 63beon-gil, Geumjeong-gu,
Busan 46241, Korea
* Correspondence: mclee@pusan.ac.kr
† Submission is extension of conference paper: Kim, H.-H.; Lee, M.-C. The Finite Element Analysis of Flying
Touch Hot Rolling Method Using Ansys Simulation. In Proceedings of the 10th Asian Control Conference
(ASCC), Sabah, Malaysia, 31 May–3 June 2015; doi:10.1109/ASCC.2015.7244667.
Abstract:
In a hot rolling process, excessive friction between rollers and steel plates may lead to the
formation of scratches on the steel plate. To reduce scratch formation in the finishing mill of the hot
rolling process, two techniques are proposed in this work: flying touch and velocity synchronization.
The proposed flying touch method can reduce the impact of the generated force when the upper roller
collides with the steel plate. In addition, the proposed velocity synchronization method can decrease
the frictional force resulting from the velocity difference between the rollers and steel plate. The
effectiveness of the proposed methods was demonstrated through simulations and experiments using
a 1/40 downscaled hot rolling simulator. The simulations and experimental results demonstrate that
the proposed methods can reduce the magnitudes of friction and impact forces that lead to scratch
formation on the steel plates in the hot rolling process.
Keywords: hot rolling; scratch; flying touch; velocity synchronization; downscaled simulator
1. Introduction
Manufacturers employ the hot rolling to process thick steel slabs into relatively thin
steel coils, which consumers can conveniently use. Hence, reducing coil defects is crucial
for improving the productivity and reliability of the steel industry. There are two types
of coil defects: shape defect (caused by the rolling process) and quality defect (associated
with the steel material) [
1
]. Shape defects include crowns, width failures, and thickness
failures, as well as scratches caused by the intense frictional force between the rollers and
steel plate.
Several studies have been conducted to reduce defects resulting from the rolling
process. For example, Sun used the random forest method to predict the occurrence of strip
crown defects during the hot rolling process [
2
]. Zhang discussed the macroscopic defects
that occur during the superplastic formation and diffusion bonding of the four-layer struc-
ture of Ti–6Al–4V metal [
3
]. Kim examined the burr defects caused by the rolling process
through a shear mechanism analysis and subsequently proposed a method to reduce such
flaws through field experiments [
4
]. Research on friction, which is the main cause of defects
in industrial automation, has also been conducted. Hwang compared various intelligent
friction compensation methods based on motion control systems to reduce the frictional
force that can cause defects in industrial products [
5
]. Kang implemented a frictional
isolator in a rotary system to realize a high-precision roll-to-roll manufacturing process,
Appl. Sci. 2021, 11, 5526. https://doi.org/10.3390/app11125526 https://www.mdpi.com/journal/applsci
