CPE process is the use of oblique rolling piercing machine to replace hydraulic piercing machine and skew rolling extension machine, combined with the traditional pipe method to produce large diameter straight seam steel pipe technology. When the CPE process is applied, the metal at the end of the tube is moved away from the deformation zone until the metal leaves the roll. The process of stabilization and the process of instability are markedly different, which is easily observed in production. Such as a capillary on the head and tail size and the middle size there is a difference, usually the diameter of the capillary front, tail diameter is small, and the middle part is the same. Large head-to-tail size deviation is one of the characteristics of unstable processes. The reason for the large diameter of the head is that the frictional force on the contact surface between the metal and the roll is gradually increased until the fully filled deformation zone is reached, especially when the front end of the tube is in contact with the plug At the time of the encounter, the axial extension of the metal is resisted by the axial resistance of the plug, resulting in reduced axial extension deformation and increased lateral deformation, with no outer end restriction, leading to a large front-end diameter. Tail diameter is small, because the end of the tube is beginning to penetrate the head, the head resistance decreased significantly, easy to extend the deformation, while horizontal rolling is small, so the outer diameter is small. First, because the pressure is not perforated perforation than the limit, the billet weight increased, the maximum weight can be the traditional billet tube 500KG increased to 1400KG, the length of the pipe up to 16-22M. Second, because the skew rolling piercing the deformation of large, fast, and thus high productivity, can reduce the deformation of the pipe jacking machine, roll die seat can be cited should be shortened, which is the result of the increase in the wall thickness. The final product range is expanded to produce a diameter of up to 244.5MM. Cup bottom is small, finished product rate is high. Process is simple, equipment investment costs less.Compared with the mandrel mandrel mill, telex, electronic control equipment is simple and convenient operating.

Defects of low temperature steel tube when drawing 1. The cause of cracking formation Low-temperature austenitic steel pipe cold work hardening index (low-temperature steel pipe 0.34). Cryogenic steel is metastable, deformation occurs in the phase transition, induced martensite phase. Martensitic phase is brittle, so prone to cracking. In the plastic deformation, with the increase of the deformation, the higher the martensite phase content, the greater the residual stress, and the easier the cracking process. 2. Surface scratches the formation of reasons Cracks on the surface of the drawn parts of the low-temperature steel pipe are mainly due to the relative movement of the workpiece and the mold surface, resulting in direct friction between the billet and the mold surface under certain pressure, and the deformation heat of the billet makes the billets and metal scraps deposited Mold surface, the workpiece surface scratches scratches.

Stainless steel seamless tube is not only looks polished, the internal need to be polished, smooth inside and outside the seamless tube in use will be more convenient, will not cause congestion, liquid flow more smoothly. Although the use of seamless transport is not only liquid, and some only use the tube to build features. Stainless steel seamless tube polishing or to improve the quality of seamless tubes, the external smooth effect, the internal must be so, and the pipe is corrosion resistance after polishing, the probability of occurrence of cracks will be reduced. The main is no gap for seamless steel tube using, if cracks, can be said that the whole pipe to scrap, and can no longer continue to use, a waste of resources. Polished change the quality of the pipe, although the internal polishing is more complex, the use of the corresponding polishing technology can be completed as usual, do not worry about this problem.

The current demagnetization of large diameter spiral steel pipe is usually used in the DC demagnetization coil, the demagnetization coil will be added to the magnetic particle inspection machine in the future, but the demagnetization effect does not enable customers to meet the problem is that the DC demagnetization field occurs only reverse half of the magnetic field, How to demagnetize the internal remanence magnetic steel reverse some offset, the external performance of the residual magnetism to stay in the required range, so the role is very unstable. Often in the field can pass, after the transfer, hit, the magnetic field and overrun. The reason is that the internal magnetic domain is not through the "magnetic exercise" in a very unstable situation. The demagnetization of large diameter spiral steel tube is the national standard 30GS following, HT30D steel tube demagnetization system can be remanufactured steel tube stability to 10GS remnant, in order to avoid the future in the process of remanence and then rebound. Specifications: Dimensions: 400 * 500 * 600mm, operating voltage: 220V, operating current: 5-20A successive adjustable, operating frequency: 0-50Hz successive adjustable, demagnetization coil diameter scale: 100-250 (or customer demand meter).

The main development direction of spiral steel pipe is to produce large-diameter thick-walled pipe to improve the pressure resistance capacity, design and produce new structure for the spiral steel pipe unit due to the increasing load pressure of pipeline, the increasingly harsh conditions of use and the longest service life of pipeline. Of the steel pipe, such as double spiral steel pipe, that is, with half the thickness of the pipe wall welded double pipe, not only the strength of the same thickness than the single-tube high, and will not appear brittle damage; vigorously develop coating pipe, In the pipe wall coated with anti-corrosion layer, not only can extend the service life, and can improve the smooth wall, reduce fluid friction, reduce wax and dirt, reduce the number of pigging, reduce maintenance costs, the development of new steel, improve smelting process Technology, widely used to control the rolling and residual heat treatment after rolling to continuously improve the strength and toughness of the pipe and welding performance. Spiral pipe unit from the welding process, the spiral steel pipe and straight seam steel pipe welding method is consistent, but the straight seam welded pipe will inevitably have a lot of T-shaped weld, so there is the probability of welding defects is also greatly improved, and the weld Of the welding residual stress is large, the weld metal is often in a three-way stress state, increasing the possibility of cracks.According to the provisions of the submerged arc welding process, each arc should be arc and arc Department, but each This condition can not be achieved when the welding of straight seam welded pipe is done, so that there may be more welding defects in the arc-extinguishing area.Using air plasma cutting machine to cut the steel pipe into single pipe. , While the spiral steel pipe is hot-rolled coil production. In this case, The rolling process of the hot strip mill has a number of advantages, such as a metallurgical process capability to produce high quality pipeline steel, for example, a water cooling system is provided on the output stage to accelerate cooling, which allows the use of low alloy components to achieve special (carbon equivalent) is often lower than similar grades of steel, which also increases the strength of the spiral steel pipe of the steel grade, and the low temperature toughness, thereby improving the weldability of steel, but this system is not in the steel plate production plant. (The pinch depends on the helix angle of the steel pipe), and the rolling direction of the steel plate of the straight seam steel pipe is perpendicular to the axis direction of the steel pipe, so that the spiral steel pipe has the rolling direction of the steel pipe, The crack resistance of the material is better than the straight seam steel pipe.