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

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 year（50000 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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