Foreign cold bending forming technology:
Foreign roll forming technology has more than 100 years of history, roughly divided into three stages.
The first stage (183,811,909) is the stage of exploration and trial production, and the research work of roll forming theory and cold-formed steel is progressing slowly. With the rapid development of industrial transportation, the cold-formed steel produced by roll-bending process can not meet the requirements of users.
The second stage (191,011,959) is to establish and gradually promote the roll-forming process of cold bending stage.
The third stage (1960 to present) is the rapid development stage of roll-bending production. The development trend of cold-formed steel production abroad, summed up, there are several aspects:
1). Increasing production
Since the 60 's, the output of cold-formed steel in foreign countries has increased rapidly, which is the general trend, according to the statistics of the cold-formed steel in the past years, the output of cold-formed steel and the output of steel are relatively stable in a certain proportion, generally 1.5:100 to 4:100. As in the 1975 Development Plan of the former USSR, the proportion of cold-formed steel production in 1990 will reach 4%, with the improvement of the production technology of cold-formed Steel, the product specification and variety are increasing, the product quality is continuously improved and the application scope is expanding, the former Soviet Union in the 1979 is to redefine the original development plan, The provisions of 1990 will reach 5%, other countries also plan to increase the output of cold-formed steel, now foreign cold-formed steel production of about 10 million tons a year, accounting for the world's total steel 3%.
2. Research is in progress
The research work of roll forming theory, forming process and forming equipment is deeply carried out in foreign countries, and a series of progress has been made in the research of the practical application of cold bending steel. For example, the former Soviet Union and the United States have used electronic computers to study the force and energy parameters in cold bending forming, and to explore the least energy-dissipation deformation methods.
3. The new technology is constantly appearing
Roll-type cold bending molding process Since 1910, the success of the United States, after decades of improvement and improvement, the molding process is maturing. With the technical and economic effect of cold-formed steel in practical application becoming more and more popular, cold-formed steel is widely used in various fields of national economy. The user is more and more strict to the quality of the cold-formed steel, requirements of variety specifications, so that the roll bending process to adapt to the requirements of the user, the development of the roll forming technology and the corresponding equipment, the introduction of a vertical roller forming machine, forming roll central regulation of the formation of the group referred to as the CTA ( Tool adjustment), Straight edge forming unit.
4 The product variety unceasingly increases, the product structure unceasingly renews.
With the development of cold-formed steel production and the expansion of application scope, the variety of cold-formed steel is increasing, the product structure is constantly updated, and the product standard is gradually perfected. With the continuous emergence of new technology, billet material and specification range is expanding, now foreign production of cold bending steel varieties have more than 10,000 specifications, of which the specification range of cold-formed Steel: blank expansion width of 10mm 2500mm, thickness 0.1mm~32mm. From the material of cold-formed Steel, the 70 's of this century, the main carbon steel, the more accounted for 90%; Since the 70, through the practical application of technical and economic comparisons, the promotion of the use of High-strength Low-alloy steel, alloy steel and stainless steel, so that the proportion of carbon steel products, alloy steel, High-strength Low-alloy steels and stainless steel products accounted for a growing proportion of the year.
Cold bending forming technology in China:
In China, since the end of the 50 to build the cold bending unit, experienced the development, adjustment twists and turns, only 6 in the late 70, 80 's China's cold bending steel rapid development, To 1982 the production of only 16,000 tons, to 1989, the country more than 20 manufacturers, production development to more than 300,000 tons, the design capacity of more than 600,000 tons, of which the metallurgical system 14 key plant, unit 45 sets, cold-formed steel variety specifications are also increasing, now has reached more than 800 species. Under the favorable form of reform and opening-up, the construction of national economy puts forward new requirements for steel varieties and quality, the advantages of cold-formed steel are gradually recognized and accepted, and the production of cold-formed Steel has achieved great development. So far, more than 100 sets of cold bending units, the annual production capacity of 1.5 million tons, a total of more than 1000 varieties of specifications.
(1) The rough forming section uses the common roll and the replacement roll combination way, the replacement product specification, some rack's roll does not need to replace, may save some rolls the reserve quantity.
(2) Flat roller with combination roll, rough forming section for six racks, vertical roll group roll tilt Layout, car roll volume is small, compared with the traditional roll molding machine roll weight reduction of more than 1/3, more compact equipment structure.
(3) The Roll shape curve is simple, the manufacture and the repair are convenient, the roll repetition utilization is high.
(4) Forming stability, the mill on the thin-walled tube and rear wall tube molding applicability, product specifications wide range. The institute designed the CR a φ219 forming unit of the first set of equipment in August 1992 in Tianjin Jinhai joint venture pipe factory officially put into operation. However, whether from the production, quality, variety, consumption and application areas, or equipment level, technological level, compared with the developed countries, the gap is very large, with an annual output of nearly billion tons of steel production status is very disproportionate. It can be expected that cold-formed steel in China will have a greater development.