The Research and Application of Zinc Dross Removing Robot in
Galvanized Production Line
Xiaodong Hao, Lu Bai, Chongfeng Yue, Xiaoqing Xu, Zihao Yin and Mengfei Zhang
China Iron and Steel Research Institute, Beijing, 100081
Keywords: Galvanizing, Zinc dross removing, Robot.
Abstract: A large number of zinc dross will be produced on the surface of zinc bath, which then will be gathered and
have a serious impact on strip surface quality, thus removing zinc dross and placing it in a dross container
timely is a must in galvanizing production line. At present, zinc dross removal is executed performed by
humans, which has many problems such as potential safety hazards, poor working conditions, difficulties in
controlling dross-removal process and enterprise costs. Robotic solutions were employed to replace humans
in zinc dross removal in foreign steel enterprises, which has obvious advantages in terms of safety, cost
reduction and efficiency. The research of dross removal robot in domestic has just started, China iron and
steel research institute and Ma-steel jointly developed a dross removal robot, with intelligent and efficient,
reasonable configuration characters, which has been used successfully in Masteel.
1 BACKGROUND
By 2013, China is the world's largest consumer
country for industrial robots which are widely applied
in automotive, electronics, metal processing, food,
beverage, rubber and chemical industries (Wenli
Liang, 2015). While in steel industry, the research and
application progress is relatively slow, due to its
characteristics such as process modularization, large
equipment scale and highly automated.
It is a general trend to employee robots to replace
labour for production, with the increase of labour cost
in recent years. At present, the robots is mainly used
in the auxiliary process of iron and steel industry such
as transportation, welding and disassembly.
In the field of deep processing steel, continuous
hot-dip plating process equipment is one of the focus.
At the meantime, the bath pot is the core equipment
of production line. Many zinc dross will be produced
on the surface of zinc bath, which then will be
gathered and have a serious impact on strip surface
quality, thus removing zinc dross and placing it in a
dross container timely is a must in galvanizing
production line (Song Xinli, 2009; Jiang Guangrui,
2015; Zhang Yanwen, 2013).
Currently, zinc dross removal is done by 1-2
people, who need to wear protective clothing, splash
helmet, anti-noise earpad, and safety belt to ensure
the safety as shown in figure 1. The following
problems exist during this process.
1) security risks. In the operation process, the
workers are only 0.2 meters away from the high
temperature liquid zinc. Added in the complex dross
removal operation, there is a higher personal safety
risk.
2) Abominable working environment. The
temperature of liquid zinc in the bath is about 460
centigrade and the ambient temperature of the
working position is about 80 centigrade. The noise of
the gas knife up to 120 DB combines with a large
amount of dust. The amount of dross for the single
operation is about 30 kg and 3 tons a day. Thus the
dross removal is a high intensity work and are
executed in a hot, noisy and polluted environment,
which seriously affects the staff health.
3) Difficulty to control dross removal process
which affects the strip quality. The process dross
removal depends on the worker’s experience, thus the
frequency and the standard are out of control,
especially for automotive and high-grade household
strips.
4) Difficulty to control enterprise cost. The
amount of zinc contained in dross is about 30%cost
increased 24.5 yuan per ton.
Hao, X., Bai, L., Yue, C., Xu, X., Yin, Z. and Zhang, M.
The Research and Application of Zinc Dross Removing Robot in Galvanized Production Line.
In 3rd International Conference on Electromechanical Control Technology and Transportation (ICECTT 2018), pages 529-531
ISBN: 978-989-758-312-4
Copyright © 2018 by SCITEPRESS Science and Technology Publications, Lda. All rights reserved
529
Figure 1: manual operation
2 RESEARCH AND
APPLICATION OF DROSS
REMOVAL ROBOT IN
FOREIGN COUNTRIES
Q-ROBOT ZINC of Danieli Group (MerluzziA, 2017)
is widely used. The working principle of Q-ROBOT
Zinc is based on an industrial 6-axis anthropomorphic
robot with its own control system that skims the
surface of the zinc bath to remove dross, and places it
in a dross container, using a specially designed tool
as shown in figure 2. At last, when the container is
full, the operator will change another container.
Figure 2: Danieli Group Q-ROBOT ZINC
Q-ROBOT Zinc has been used successfully,
especially in zinc savings due to the optimized zinc
dross skimming operation in Marcegaglia and Arvedi.
Overall, the Q-ROBOT ZINC has the advantages
of simple structure, convenient maintenance and high
reliability. However, the Q-ROBOT ZINC slag-
cutting robot is still in the first generation of industrial
robots, and which is of high price.
3 RESEARCH AND
APPLICATION OF DROSS
REMOVAL ROBOT IN CHINA
The research of dross removal robot started relatively
late in China (Dai Xichun, 2017). Many large state-
owned enterprises such as China Iron and Steel
Research Institute(CISRI), Bao-steel, Shougang and
MaSteel carried out the research and application of
dross removal robot and achieved certain
achievements. However, the mature solution has not
been formed yet. In February 2016, an on-line dross
removal robot system which was designed according
to operating habits and processes and can meet the
production requirements of the Masteel galvanizing
line, was developed by a joint R&D team in CISRI
and MaSteel.
Demonstration project (Figure 3) of galvanized
line dross removal robot developed by CISRI and
Masteel jointly, realizes the whole requirement of
users correctly in May 2017. The dross removal robot
belongs to the third-generation industrial robot, which
took the bath pot and its peripheral equipment into
consideration, with the characters of high intelligence,
reasonable configuration et al. It was designed
according to operating habits and processes. The
process has reached the advanced level of similar
products in developed countries, which contains 22
kinds of processes (Figure 4) for different
components zinc bath and different kinds of strips.
Figure 3: On-line dross removal robot system developed
by CISRI and MaStell
Figure 4: Manual process evolution to robotic process
ICECTT 2018 - 3rd International Conference on Electromechanical Control Technology and Transportation
530
Many experiments, such as hardware and
software reliability tests, crash reliability tests, dross
removal efficiency tests have been conducted and
great improvements has been made during the
debugging process. Experiments results show that the
equipment is reliable, efficient and reasonable, which
can meet production pace of 2 # galvanizing line in
Masteel. The distribution of zinc dross on the zinc
bath surface (before and after operation) are shown in
figure 5.
Figure 5:Zinc bath surface picture (before and after
operation)
The robot has a protection class IP67, and wear
protective clothing, with the ability of splash, dust,
heat resistance, which means it is well protected
against dust leakage and high temperature. The
robot’s HMI is programed using C# language and is
human friendly.
The dross removal robot can control position of
the special tool precisely, thus the depth of removal
tool in zinc bath is keep constant less than 10 mm,
making the liquid level fluctuations in the bath
minimal and production stability improved greatly.
The level of technology reached the first-class level
of similar products in developed countries
Compared with the existing international
equipment, this device has following advantages.
(1) Dross removal tool has little effect on the
composition in zinc bath, which was treated specially,
thus has no infiltration of zinc liquid, can increase
service life.
(2) Integrated many different sensors such as
vision, level, collision et al. thus it can remove the
zinc dross intelligently.
(3) Little changes in operating habits, makes it
easy to be accepted by operators.
(4) Adopting small arm development robot, has
low environmental requirements.
To sum up, the system can save investment and
operation cost, which has high dross removal
efficiency and less loss of zinc.
At present, the equipment has been used
successfully in 2# Masteel galvanizing line. Due to
the use of the robot, a worker can be replaced at least
in each shift group. Thus 200,000 yuan can be saved
in a year50000 yuan per year a person.
4 CONCLUSIONS
The research shows that the robot can effectively
skim the zinc dross from the surface of zinc bath in
the galvanizing line and can reduce the production
cost and replace the manual operation in the harsh
environment, with the advantages of simple structure,
convenient maintenance, good reliability and high
cost performance. It has been promoted gradually in
China.
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