Cold-formed welded pipes need to be cut according to the required length after sizing. The traditional cutting is using a circular saw. The circular saw cuts the production cost is low and the production efficiency is high. The shear deformation is large, and the connection between the two welded pipes is not good when the user is using the product. It is difficult for the product to meet the requirements of European, American and Japanese standards for product quality. After the 1980s, manufacturers of cold-formed welded pipe equipment used a synchronous copying flying saw (equivalent to copy milling) in a new cold-formed welded pipe production line, using two saw blades to cut the steel pipe at the same time. The trajectory of each saw blade just cuts the cut of half the pipe. When the variety is changed, the trajectory of the saw blade can be automatically adjusted according to the cross-sectional shape of the pipe. This profiled milling saw is smooth, smooth and burr-free, with low noise and high precision when milling. According to reports: When cutting 18m fixed steel pipes, the length tolerance can reach ± 2.5mm. However, the copy milling saw has a high investment, and the blade needs to be changed every 3 to 4 hours during production, and the blade must be scrapped three times for grinding. The production cost is high.
Cold-formed welded pipe manufacturers need to choose sawing equipment according to different product positioning and user requirements.
4) Quick roll change technology
The traditional welded pipe production line requires a large roll change for the entire line, which usually takes 8 to 12 hours. According to user requirements and competitive needs, the well-known cold-formed welded pipe manufacturer SMS Company and the American Abbey Company have developed rapid roll change Technology, using a rapid roll change system, can complete the roll replacement required for the variety change through the roll change cart in 90 minutes, greatly reducing the production preparation time, thereby greatly improving the design capacity of the production line. At the same time, through the application of the computer, the roll position adjustment is provided with memory, and the roll position can be adjusted quickly and automatically when changing the product, which reduces the time and error of manually adjusting the roll position and improves the accuracy of the product.
In addition to the above typical cold-formed welded pipe production technical characteristics, some of the forming frames in the newly-formed cold-formed steel production line use URD—equal rigidity forming and welding frames. The frames can withstand similar rolling in the horizontal and vertical directions Force and stiffness are equal, the product is more accurate, and the frame roller system can be quickly moved horizontally when changing rolls; some production lines also use a new internal burr removal device, which features The burr can be broken at the same time of deburring, so as to protect the blade of the fixed-length milling saw. By removing the burr, the inner surface height tolerance can reach ± 0.2mm accuracy.
5) Production technology applied to China's cold-formed rectangular tube production line
China's current manufacturers of cold-formed rectangular tubes are mainly used in China's self-developed production technology. Wuxi Yulong Steel Pipe Factory has two square rectangular tube production lines, one is a 400mm × 400mm square rectangular tube production line, which is an old-style direct-roller continuous rolling calender continuous unit. Welded pipe sawing is performed using disc 生产. Quality problems such as poor weld quality, the product can not meet the requirements of advanced cold-formed rectangular rectangular tube product standards such as American standard and Japanese standard; the other is a 250mm × 250mm × 8mm (max) square rectangular tube roll production line. This production line The molding adopts the CFSR row roll forming production technology. When changing the product specifications, it is not necessary to replace the rolls, and the production efficiency is high. Shanghai Fangyuan Garden Good Profile Steel Co., Ltd. is a 250mm × 250mm × 8mm (max) square rectangular tube row roll production line. Baosteel Iron and Steel Technology Research Institute 200mm × 200mm ～ 450mm × 450mm / 500mm × 200mm square rectangular pipe production line uses the CFSR square, rectangular and round tube roll forming technology of Dalian Fudi Company. The production line speed is 10-30m / min, wall thickness 15 ～ 30m / min at 4 ～ 10mm, 10 ～ 15m / min at 10 ～ 19mm wall thickness, product specifications are 200 × 200 ～ 450 × 450 square tube, maximum length of rectangular tube is 500mm, minimum length of side is 200mm, rectangular tube is maximum The aspect ratio is 2: 1, the thickness is 4 ~ 19mm, the maximum thick side ratio is: 1: 15 ~ 1: 50 (the ratio of the wall thickness to the small side length of the rectangular tube), and the fixed length is 6 ~ 16m.