Development of rolling mill

1. Development of the primary rolling mill

The development of the primary rolling mill has gone through three stages. By the early 1970s, the roll diameter of the mill has increased to 1500mm. Since 1959, China has designed and manufactured the blank opener. At present, 700mm, 750m, 850m and 1150M primary rolling mill have been made. Since the 1980s, continuous casting technology has been developed greatly. The ratio of continuous casting is 80% or higher. The continuous casting and rolling process and equipment are becoming more and more perfect. The function of the primary rolling mill machine will be gradually transformed into co-continuous casting, which will make up for the deficiency of continuous casting in steel grades and specifications.

2. Development of strip rolling mill

In all the steel market demand, the sheet and strip account for a considerable proportion. In 1981, China introduced a complete set of 1700m hot rolling mill from Japan. Then, a large number of hot strip rolling mills with advanced production technology have risen rapidly. By 2007, the annual production capacity of hot rolled wide strip in China will reach 55million tons, and the annual production capacity of cold-rolled wide strip rolling will also reach 30million tons.

The main characteristics of hot continuous rolling mill development include: increasing the weight of strip and blank, reducing the loss of cutting end and increasing the product yield; adopting accelerated rolling to improve the steel production, the export speed of finishing mill of strip mill has been increased from 10m/s to 12m/s in the 1950s to 35m / S; product specification increased and precision improved; computer control was adopted to improve automation level.

Although the production cost and investment cost of cold-rolled steel plate are higher than that of hot rolled steel plate, the performance and quality of cold-rolled steel plate are better than that of hot rolled steel plate, and the metal material can be saved by 30% under the same use, so the cold rolling plate production has been developed rapidly. Almost 100% of the sheets used in some industrial developed countries (such as the United States) are cold-rolled. The hot rolled plate is only used as the blank of cold-rolled plate, welded pipe and cold-formed section steel.

In China, a 300 mm five stand trial narrow strip cold tandem mill was made in late 1965. In the 1980s, 1700m five-stand cold tandem mill set of steel was introduced from original West Germany. After the 1990s, six high H C and C V C mills were also put into production. The cold strip rolling mill is developing to large scale, high speed, high precision and automation.

3. Development of steel pipe rolling mill

Steel pipe has two production methods: welding and rolling. Before the founding of the people’s Republic of China, China could not produce hot-rolled steel pipes. After the founding of the people’s Republic of China, China can not only produce large-diameter spiral welded pipes to meet the needs of long-distance transportation of oil and gas, but also widely use the periodic cold rolling pipe mill to produce cold-rolled steel pipes. In the 1990s, a large-diameter hot rolled seamless steel pipe factory was built. Now, there are more than 50 sets of hot-rolled steel pipe equipment, and the products are more than 1000 kinds.

4. Development of profile steel rolling mill

The profile steel is mainly produced by hot rolling. The rolling mill used for hot rolling section steel is divided into rail beam, large, medium, small and wire mill according to the roll diameter and product specification. In recent years, the profile steel rolling mill has been developed greatly. The universal rolling mill is used in the primary and middle rolling mills to reduce the number of steel turning and shorten the interval time; the short stress line rolling mill and the prestressed rolling mill are used for finishing rolling to increase the rigidity of the rolling mill and ensure the product has a small tolerance range; the guide device and its installation and disassembly method are improved to extend the service life of the guide device and reduce the stopping time during the replacement; The automatic pressing setting mechanism is adopted to ensure the accurate size of the rolling parts, shorten the adjustment and trial rolling time, and adopt the combination of roll system to shorten the roll changing time.

Wire rod mill is used to produce round section rolling material with 5mm-12.7mm. In the 1940s, the wire mill needs manual feeding, the maximum rolling speed is limited to below 10m/s, the plate weight is about 800K n-900kn; in the mid-1960s, Y-type high-speed torsion free rolling mill appeared, the highest rolling speed is 50m/s-70m/s, the wire rod plate weight reaches 25000k n; the exit speed of cantilever 45 ° torsion-free finishing mill developed in the 1970s reaches 65m / S ~ 80m / s, some of which reach 120m / s.

In recent 30 years, wire rod mill has developed greatly in high speed, large plate weight, high yield and high precision.