High-speed bar production line core technology and equipment

1. Project background and issues

Rebar products are an important demand for the development of national infrastructure, railway bridges and water conservancy. The advancement of its production technology and equipment is an important symbol of the development level of long steel rolling. China’s annual demand for rebar is about 200 million tons, and the consumption of small-sized rebar (Ø10-Ø22mm) accounts for about 70% of rebar products. In the past, small-sized rebar was cut with a speed of less than 18m/s and multiple lines. Produced by ordinary bar rolling. As the quality requirements of rebar products increase, high-speed bar production technology has begun to be widely used. Compared with ordinary bars, it has the advantages of single-line high-speed rolling of finished products, high product accuracy and high appearance quality.

In the past, when high-speed bar production lines used conventional rolling processes, they generally adopted centralized transmission of the finishing rolling unit or partial decentralized transmission. In the actual production of Ø10-Ø22mm rebar, more than 6 basic pass shapes are needed before the finished product, which increases the downtime for specification replacement and makes the rolling line operation rate low, which can only reach about 88%-90%; in addition, it is relatively Multiple hole types also increase the cost of production spare parts such as roller rings and guides. During the production process, the bouncing of the rolling mill and the inconsistent head and tail material shapes cause dimensional fluctuations, which also affect the product’s dimensional accuracy and bar accuracy.

In terms of steel equipment on the high-speed bar production line, the multiplier control accuracy is low, which affects the product yield; the tail clamp uses cylinder clamping, and the clamping force adjustment ability is poor, which can easily cause serious cracks at the tail of the rolled piece. Clamp marks affect product quality; the cooling bed action cycle adopts a fixed cycle method. When optimizing the rolling stock length, it cannot compensate for the periodic changes caused by the same rolling stock length, and the rolling stock tooth collision phenomenon will occur, affecting the stability of the operation. sex.

In terms of alloy reduction production, the existing high-speed bar production line-controlled rolling and cooling process is imperfect, and the temperature control of the rolled parts is inaccurate. As a result, the production line cannot effectively reduce the proportion of alloy elements manganese and vanadium, which increases the consumption of alloy resources and the cost of production.

According to the trend of technological development in the intelligent development of steel rolling production processes, improving the intelligence level of high-speed bar production lines has become an urgent need for steel companies. Therefore, we systematically study the rebar production technology of high-speed bar production lines to solve the problems faced by existing high-speed bar production lines such as low product precision, insufficient production flexibility, poor stability of high-speed steel loading, low yield, alloy reduction production. In response to the demand for intelligence, the development of core technologies and equipment for flexible 45m/s high-speed bar production lines is of great significance to improving the technical level of high-speed bar production lines and achieving high-quality, high-efficiency, low-cost, and low-consumption production of customer rebars.


2. Technical solutions and main content


high speed bar, Bar, water cooling, finish rolling, rolling mill


1) General idea


(1) In order to solve the problems of low product accuracy, low production flexibility and low level of intelligence of the production line in the existing high-speed bar production line, apply the theory of flexibility and modular rolling and develop high-speed and high-capacity modular rolling mill equipment and dynamics. Compensation variable extension control technology.

(2) In order to solve the problem of poor stability of the high-speed steel loading system, systematically study the rules of rolling stock doubling and brake loading, establish a dynamic model of the high-speed steel loading system, and develop key equipment and equipment to achieve high-speed steel loading stability. Control Technology.

(3) In order to overcome the problem of rebar alloy reduction production that meets the requirements of the new national standard, conduct research on the rolling temperature system, phase change system, controlled rolling and controlled cooling process technology, and find out a rolling production process that can reduce alloy consumption. , according to the characteristics of high-speed bar production technology, the rolling line is studied to study measures to improve intelligence and realize intelligent production of the rolling line.

Through theoretical research and technical research, we have opened up a full set of technical links from process technology, core equipment, and control technology innovation to market transformation of results, and comprehensively solved customers’ demands for high-quality, high-efficiency, low-cost, low-consumption production and intelligent rebar. needs.


2) Research and development of high-speed bar flexibility modular rolling concepts and modular rolling mill equipment

Based on the characteristics of high-speed bar production of rebar, a full-sized single-hole system for smaller rebar (Ø10~Ø22mm) has been developed. The entire pass profile of this single pass system is a basic pass profile except K1 and K2. When switching product specifications, only the roll rings of the K1 and K2 rolling mills need to be replaced, and the remaining rolling mills can be passed or the roll gaps can be adjusted. , this method has great flexibility and adaptability and realizes flexible and flexible production of the rolling line.


3) Development of steel system equipment for 45m/s high-speed bar production line


The high-speed bar steel loading system equipment developed in this project can complete double-length shearing, tail clamping and braking, and safely and accurately transport bars of Ø10mm-Ø22mm specifications to the maximum final rolling speed of 45m/s. The cooling bed and high-speed steel loading system equipment mainly include pinch rollers, high-speed double-length flying shears, tail clamps and rotating hub steel loading devices.


4) Development of controlled rolling and controlled cooling technology for alloy reduction and high bar


Depending on the production scale of the rolling line, there are two types of high-speed bars: single high-speed bars and double high-speed bars. However, no matter which type of high-speed bar production line is used, the final product is rolled from the ring-type finishing rolling unit (2-4 racks). ) rolling out and finishing rolling unit layouts including the “4+2” layout and “4+4” layout.

In order to ensure that high-speed bars adopt controlled rolling and cooling technology, a number of water tanks (2-3) are arranged before and after finishing rolling unit I and behind finishing rolling unit II to meet the two-phase temperature of 780-830°C in the finishing rolling unit. Low-temperature finishing rolling is carried out in the zone. After rolling, graded controlled cooling is used to control the cooling rate after rolling and the temperature of the upper cooling bed of the rolled piece.


5) Development of an electrical control system for a high-speed bar production line


The core part of the high-speed bar production line control system is in the high-speed area. The high-speed area is mainly divided into a modular rolling mill, high-speed flying shear, high-speed steel unloading area and water-cooling temperature closed loop. This project is aimed at the existing high-speed bar high-speed area control In order to solve the existing problems, we conducted a systematic study on the electrical control system and developed the control system in the following aspects.


(1) High-speed modular rolling mill dynamic compensation variable elongation control system

(2) High-speed bar water-cooling temperature closed-loop control system

(3) Pulse equivalent dynamic measurement multiplier flying shear control system

(4) Bar braking micro-clamp braking control system

(5) Adaptive periodic rotating hub steel control system

(6) High-speed bar intelligent production line system


3. Main innovative achievements


Based on advanced rolling concepts, this project took the lead in developing a complete set of flexible 45m/s high-speed bar process, equipment and control technologies, resulting in four innovative achievements:

1) Innovatively proposed the concept of high-speed bar flexibility and modular rolling, pioneered the world’s first single-pass high-speed bar rolling technology, developed the core equipment of high-speed and high-bearing capacity modular rolling mill, and realized the integration of traditional multi-specification products. The rolling method of using multiple sets of pass shapes is transformed into a new production mode using only one set of pass shapes, which improves production efficiency and dimensional accuracy, solves the problems of low product precision and insufficient flexibility, and reduces production costs.

2) Systematically studied the rules of rolling stock doubling and brake loading, established a high-speed steel loading system dynamics model, and developed a high-speed doubling flying shear with double servo switches, intelligent tail clipper and servo hub. The core set of high-speed steel loading equipment enables the stable operation speed of the high-speed steel loading system to reach 45m/s, greatly improving production efficiency.

3) In view of the problem of reducing the production of new national standard rebar alloys, the company innovatively proposed a controlled rolling and controlled cooling process of low-temperature finishing rolling and post-rolling graded water cooling and developed a hot-rolled steel bar microstructure and performance prediction model and an intelligent water-cooling temperature control system to achieve The low-manganese and vanadium-free production of hot-rolled steel bars effectively reduces resource consumption.

4) In view of the problems such as high requirements for intelligent control of flexible rolling, low stability of steel on the rotating hub, and severe clamping marks on rolled parts, a dynamic compensation variable-speed system was developed based on advanced means such as machine vision, artificial intelligence, edge computing, and cloud computing. A complete set of high-speed bar intelligent control technologies with the core of extension, adaptive rotating hub loading, double-scale shearing and micro-clamp braking based on dynamic measurement of pulse equivalents, which improves the stability of rolling line operation and achieves high double-scale precision. , the yield rate reaches a high level, and the level of intelligent control of high-speed bars is improved.

This achievement has applied for 22 patents and published 1 monograph. The scientific and technological achievements have been evaluated by the China Metal Society to reach the international advanced level, among which the single-pass flexible rolling technology has reached the international leading level. This technology has the characteristics of high production flexibility, fast speed, high operating rate and finished product rate, low alloy consumption and a high degree of intelligence. It has changed the production method of small-sized rebar and promoted technological progress in the production process of rebar bars in the field of long products.


4. Application and effects


The successful development of the 45m/s high-speed bar line steel equipment and control system developed by this project has changed the current high-speed bar line production status and reduced investment in production line construction. The core technology and equipment of the high-speed bar production line were applied to Shanxi Jincheng Fusheng Steel Co., Ltd. for the first time in 2018. The production line adopts high-speed rolling and manganese reduction production processes. It has a high level of intelligence, product quality meets national standards, and technical indicators have reached domestic standards. leading level, creating significant economic benefits for customers.


Source of article: Website of Chinese Metal Society

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