Application of metal pipe cutting process

Content abstract: In the field ground construction process, often encounter the tube-tube or pipe and other objects connected to the situation. According to the requirements of the site construction accuracy, this paper adopts the corresponding cutting method, and completes the construction task simply and efficiently.

1. Overview
According to the construction needs of the site, in the pipe cutting material when my company commonly used methods for manual gas welding cutting, magnetic automatic pipe cutting machine, CNC line CNC cutting machine cutting. Each device and its corresponding cutting process have advantages in specific applications, as well as certain problems and deficiencies.
(1) Manual gas welding cutting (Changzhou City Junwei welding tool factory) advantages: easy and fast operation, very suitable for the need for high-precision sealing welding port on-site cutting. Disadvantages: the need for a level of professional skills of gas welding technicians, such as the need for high-precision line welding, the need for specialized technical personnel to carry out accurate lofting, the use of production model, drawing, manual lofting, manual cutting and manual grinding and other backward and complex operation process. This method of cutting automation is low, the work intensity is large, the technical level and proficiency of workers are more stringent, processing quality, processing accuracy is difficult to be guaranteed, it is easy to cause scrap workpieces.

( 2 ) Magnetic walking trolley cutting (Changsha Tobo Welding Technology Co. , Ltd.) advantages: magnetic type is the use of magnetic trolley to do walking machinery, to achieve automatic cutting. Disadvantages: First, the steel pipe roundness is not good, magnetic car along the pipe wall, walking path changes, especially large-calibre steel pipe, welding roundness is difficult to maintain very good, cutting effect is not good. Second, in the surface of the coating or insulation layer, such as the case, the magnetic force is reduced, can not overcome self-weight, magnetic type can not work. Third, in cutting a seam pipe, especially a spiral tube, the magnetic walking trajectory changes, the magnetic car in the weld through the spiral tube easy to fall off or due to bumps, walking mechanism wheels to go partial. Fourth, stainless steel and other non-magnetic pipes can not be cut. Fifth, when the magnetic cutting machine is placed on the tube, it is difficult to ensure that the cutting body and the end of the parallel, walking deviation is inevitable, the larger the pipe diameter, the greater the deviation, so often draw the line first, the cutting process and then by the workers real-time monitoring, deviation and then manual intervention, waste of working hours, but also can not completely guarantee the quality, as shown in Figure 1.

Figure 1 Magnetic walking trolley cutting
In addition, there are manufacturers for the magnetic may fall this shortcoming, can be equipped with fixed chain and other institutions, but still can not solve due to the pipe diameter error and roundness error caused by the loss of cutting accuracy.

( 3 ) Consistent line CNC cutter
(Beijing Linkman CNC Technology Co., Ltd.) Advantage: Is a steel pipe and non-ferrous metal pipe combination of the line hole, the end of the line, elbow (shrimp rice section) for automatic calculation and cutting equipment. CNC phase-through line cutting function is very convenient cutting and processing such workpieces, without operator calculation, programming, just input the pipe radius of the pipe-through system, intersection angle and other parameters, the machine can automatically cut out the pipe line, the line hole and welding slope.
Cons: Equipment is expensive. Pipe needs to be cut in the workshop, transferred to the construction site, can not carry out on-site work construction, as shown in Figure 2.

Figure 2 Phase-line CNC cutter

2. Application of different cutting techniques
In many years of production practice, we have summarized different pipe cutting methods, can achieve its corresponding pipe cutting, bevel cutting quality requirements and different production efficiency.
Here's how to apply different cutting methods to specific projects:
( 1 ) Hand-cut In the anti-corrosion pipeline two plant transformation project, the four-piece depository platform is required to be re-fabricated. The platform is made of a 168m m x 10m thick-walled steel pipe. Since the steel pipe welding place does not need to seal, only need to reach the corresponding welding strength can be, in the process of steel pipe welding, we have chosen the field loft manual gas welding cutting method. This method is simple and fast, eliminating the need to transfer the steel pipe material multiple times. Edge material, edge welding, 10 workers, only took 12h to complete the platform prefabrication tasks.
( 2 ) Magnetic walking trolley cutting In the high-pressure water injection project of the third oil extraction plant in Daqing Oilfield, the engineering requires the slope treatment of the three-layer P E anticorrosion pipe of the 3rd-layer P E pipe of the 3rd-level of the Daqing Oilfield. Because my company's metal cutting slope machine, not suitable for the completion of such a wall thick steel pipe bevel treatment, finally decided to use magnetic walking car cutting. The bevel processing of the 7k m pipeline is completed by this method. The quality of the bevel is qualified, and the welding pipeline has been accepted by the supervisor and Party A, as shown in Figure 3.

Figure 3 Specific application of magnetic walking trolley cutting
(3) CNC pipe alignment line cutting machine in Daqing refining 300,000 t polypropylene device reconstruction project, there are a large number of different specifications of the pipeline needs to be connected. In order to ensure the sealing and aesthetics of the connecting structure, it is necessary to cut strictly along the track of the pipe line. When used for welding joints, leave the welding bet at the same time as the line cutting. Therefore, our company adopted the operation is convenient and flexible, can meet the processing accuracy requirements of the CNC phase-through tube machine, as shown in Figure 4.

Figure 4 Specific application of the line CNC cutting machine
Further research and development of pipe cutting equipment
With the rapid development of China's industry, the requirements for cutting quality and precision are constantly improving, in order to improve production efficiency, ensure product quality, realize the automatic cutting of the line, the development of CNC cutting machine must adapt to the requirements of modern industrial development.
(1) Flame cross-line cutting From the current several common CNC cutting machine application situation, the flame cross-line cutting machine function and performance has been relatively perfect, its material cutting limitations (only cut carbon steel pipe), cutting speed is slow, low production efficiency, so that its scope of application gradually shrinks, the market can not have a big increase.
( 2 ) Plasma phase-through wire cutting machine with a wide range of cutting (can cut all metal materials), cutting speed, high efficiency and so on, the future direction of development lies in the plasma power technology improvement, numerical control system and plasma cutting cooperation problems, such as power supply increase can cut thicker sheet The perfection and improvement of fine plasma technology can improve the speed, face quality and cutting accuracy of cutting, and the improvement of numerical control system and improvement to adapt to plasma cutting can effectively improve the efficiency and cutting quality.
( 3 ) Special phase-through wire cutting machine is suitable for a variety of pipe scuttling cylindrical orthogonal, oblique, eccentric and other habitual line holes, square holes, elliptical holes, and can be cut at the end of the pipe with the customary line. This type of equipment is widely used in the production of metal structures, electrical equipment, boiler industry, petroleum and chemical industries.
4. Conclusion
With the upgrading of computer technology, advanced numerical control technology has been applied to the field of consistent line cutting, which makes high-precision phase line efficient cutting achieved. However, in the specific application should also pay attention to the cultivation and retention of traditional gas cutting process, to maximize the advantages of different processes in pipeline cutting, mobile, flexible, efficient, high-quality to complete different production tasks.