The Connection Technology Research Of High Pressure Seamless Steel Tube In The Coal Cutting Equipment

Coal cutting equipment also known as high pressure hydraulic slotting machine is a set of equipment to improve low permeability coal seam gas drainage efficiency, which utilizes high pressure water jet technology to drill and cut seam in coal mining process. This equipment is made up of hydraulic driving mechanism, continuous steel pipe winding mechanism, reversing mechanism, moving mechanism, continuous steel pipe clamping mechanism, pushing and clamping mechanism, straightening mechanism and the supporting hydraulic system. Among them, to solve problems of the limited space of underground tunnels and high pressure of the steel tube long-distance transport, the continuous steel pipe winding mechanism is specially designed into a set of mechanism to wind flexible pipe on the rotary drum, which facilitates the continuous steel pipe long distance transport and conveying and guarantees minimal tunnel space. The longest continuous steel pipe is10meters in the market. For the deep buried coal seam, we will need to put the steel pipe connected. The practice proves that the continuous steel pipe can meet the using requirements, which is manufactured by welding the short pipe. Long distance continuous steel pipe to be wrapped around the1280millimeter diameter roller is bended and straightened unidirectionally and repeatedly by straightening mechanism, which requires that the steel pipe has good plasticity, toughness and weldability; Continuous steel pipe is pulled by the pushing and clamping mechanism repeatedly, which requires that it has higher strength;70MPa of high pressure water flows through continuous steel pipe, which requires that the continuous steel pipe has much higher sealing; Under conditions of target distance determined, high pressure water should have a certain direction when drilling and slotting, which requires the steel pipe has certain stiffness. So the welding technology of continuous steel pipe is put forward higher requirements.A great quantity of experiments show that the20G seamless steel pipe used in high-pressure boiler can reach the using requirement through the reasonable welding process. Welding process of the specifications forï¿ 25X3seamless steel pipe is researched and experimented in the article, and the bending stress of the seamless steel pipe welded is simulated and analyzed. Reasonable inclination angle and the correct bending direction of the seamless steel pipe welding parts are discussed, which determine the twining way of steel pipe. The welded steel pipe weld CT scan test, can clearly see that the quality of weld, weld defect location and defect formation reason, the welding operation and welding process for further improvement direction. Taking20g boiler plate as an example, the change process of temperature field in the welding is simulated by using APDL programming language the of ANSYS software. The main contents of this paper include the following aspects:(1) The welding process of20G seamless steel pipe is drafted, and single-side welding double-side molding operation technique of the20G seamless steel pipe is researched importantly.(2) The welding temperature field of20g boiler plate is simulated by using the APDL language of ANSYS. According to post-processing function of ANSYS, temperature change of each node in the welding parts is analyzed in the welding process.(3) When welding angle are30degrees,45degrees and60degrees, their bending deformations are given. The bending stress is analyzed by using ANSYS software, reaching the ideal inclined angle of welding line.(4) The four directions of the bending stress in the direction of45degrees weld are analyzed by using ANSYS software. It is reached that the maximum principal stress in the steel pipe is minimum, when it is bended at the horizontal direction; So the reasonable winding and installing position of steel pipe is determined.(5) Through the CT scan experiment about welding seam of20G seamless steel tube and detection of the double-sided forming quality of one-sided welding, the welding defects have been found out of, the reasons of the welding defect have been analyzed, which must further improve the welding process and the operation level of welders.