AI solutions for the steel industry

Accurate weighting and sizing system for continuous casting slabs

The billet weight fixing system is the first of its kind. No similar technology has been found at home or abroad. It has been identified by authoritative organizations and has reached the international advanced level.

Automatic Online Control

Realize intelligent and online automatic control of continuous casting billet weight to avoid human intervention.

Closed-loop Control

Realizes intelligent linkage with collectible information such as casting speed, molten steel temperature, water distribution, steel grade specifications, etc., to achieve closed-loop control.

Improve the accuracy and qualification

Improve the accuracy and qualification rate of continuous casting billet weight determination, and the proportion of billet weight determination accuracy "target value ±1‰~21‰" is ≥80%.

1. Background and value: industry pain point - casting and rolling standards are not unified

1) Corresponding to bar production line

(1) Continuous casting is cut according to fixed length, and steel rolling is rolled according to weight. The implementation standards of the two are not uniform, resulting in loose lengths in rolled steel products, which also affects the yield rate and economic benefits;

(2) Take the 165*165/150*150 cross-section billet as an example: for the same fixed length, the weight difference can reach more than 20kg under different production conditions, and the flows are unbalanced;

(3) The billet is too light, resulting in a short rolling length, which affects the cut-to-length rate; the billet is overweight, resulting in too much cutting material, which affects the yield rate.

2) Corresponding steel production line

(1) Continuous casting is cut according to fixed length, and steel rolling is rolled according to weight. The execution standards of the two are not uniform, resulting in a decrease in the yield rate of steel sections;

(2) The current control method of billet weight is to increase or decrease the length through pure fixed-length cutting or weight feedback after cutting. However, due to changes in process, equipment and other conditions, the weight of the billet fluctuates in a large range and is unstable in the long term, which becomes a problem for improving the yield rate of section steel. Restrictive links.

H Steel Production Line

2. Comparison with market technology

1) Methods of controlling the weight of cast slabs

(1) Offline or online weighing + fixed length modification + flame cutting;

(2) “Pure fixed length”, the fixed length is manually adjusted based on feedback from steel rolling;

(3) Intelligent fixed weight model + hidden online roller weighing + dynamic fixed length optimization, forming a closed loop.

2) Technical comparison

(1) Continuous casting cannot achieve constant temperature and constant speed casting, and the linear relationship between weight and length cannot be realized. Therefore, in actual production, continuous casting billets are frequently adjusted through the first two types of cutting methods, and the target weight cannot be accurately hit.

(2) The third type of technology forms a closed-loop control. The feedforward model collects production data in real-time, which can accurately predict the online relationship between the scale and the fixed weight according to production fluctuations, and adds online weighing and feedback calibration, feedforward + feedback. Control is more precise.

Comparison of methods

Weighing method

Weighing time

Fixed weight accuracy

Fixed weight pass rate

Pure fixed length

None

None

±0.3%

<50%

Weighing + infrared sizing + post correction

Hydraulic

30~50s

±0.3%

65~75%

Intelligent online weight determination

Hidden roller scale

6~10s

±0.3%

>90%

±0.1~±0.2%

≥80%

3) Factors affecting the qualification rate of fixed length and weight

(1) Composition of steel grade

Different steel types have different compositions, and the billet drawing speed and cooling time during billet casting will be different.

(2) Drawing speed

Different casting speeds affect the cross-sectional size of the slab, resulting in different weights of slabs of the same length.

(3) Temperature of molten steel

When casting the billet, the temperature of the molten steel is different, which affects the billet casting speed and cooling time, resulting in different billet casting speed and cooling time.

(4) Crystallizer wear degree

The more severe the wear of the mould, the larger the cross-sectional size of the cast slab, the greater the weight of the cast slab of the same length, and the greater the error.

(5) Density of billet

The density of the slabs is different, and the weight of the slabs of the same length is different.

(6) Cross-sectional dimensions of the cast slab

The cross-sectional dimensions of the slabs are different, and the weights of the slabs of the same length are different.

Carry out in-depth systematic analysis and research on various process factors and equipment factors that affect the accuracy of casting slab weight, such as steel grade composition, tundish temperature, casting speed, cooling rate, mould wear, etc., as well as others such as nozzle Replacement, replacement of fixed weight, physical and chemical indicators of mould powder, flow blocking and opening, etc., the quantifiable key factors are summarized through sorting out, and then using online big data collection, data mining, data analysis, artificial neural network and other technologies, Establish an online model for billet weight determination to accurately control length cutting and improve weight determination accuracy.

4)Weighing device

Hidden integral roller weighing method

Structure: The weighing scale frame, sensor, transmission motor and other components are installed together under the post-cutting roller table or the cooling bed roller table.

Advantage:

(1) The hydraulic lifting device is cancelled, there is no hydraulic energy consumption, and the daily maintenance and active costs are reduced.

(2) Reduce weighing time, traditional weighing takes 30~50s, and bracket-type integral roller weighing takes 6~10s

(3) The equipment has good durability, easy operation and maintenance, low power consumption, and no gantry obstruction, making it convenient for on-site operations.

steel slab casting process

3. Performance cases (user feedback)

1) Delong Yutian Jinzhou Industrial

The equipment was put into operation in December 2022, and the ±6 kg fixed weight qualification rate has reached more than 88%. After the equipment is put online, the rolling steel loose length rate has been reduced by 0.7%-1%, creating benefits for the enterprise of nearly 10 million yuan per year.


2) Baowu E-Steel

The equipment was put into use in February 2021, with a ±4 kg (±1.6‰) fixed weight qualification rate of more than 80%. After the equipment went online, the fixed length rate increased by 0.95%, and the finished product rate increased by 0.35%. The two casting machines have been put into operation for 11 months since February 2021, creating a profit of approximately 13 million yuan.

3) Changzhou Dongfang Special Steel

The equipment has been put into use in January 2022, and the -1‰-3‰ fixed weight pass rate is more than 85%. Before the use of intelligent fixed weight, the finished product rate was approximately 102.7%, and after the fixed weight was put into use, the finished product rate increased to 103%.

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