All-position automatic pipeline welding refers to the pipeline at a relatively fixed, the welding torch along the rail car to drive around the wall motion, in order to achieve automatic welding. In general, all-position welding automatic welding equipment by part car, walking tracks, automatic control systems and other components.
Welding carriage is to achieve automatic welding process, the drive mechanism, which is mounted on welded rail, with the torch along the wall in a circular motion, is an important part of achieving automatic welding nozzle. Welding carriage should have a beautiful appearance, small size, light weight, easy operation. It is a core part of the running gear, wire feeder and torch oscillation adjustment mechanism. Running gear from the motor and gear bodies, to make walking motor position and speed instruction execution issued by the computer control unit, the motor speed feedback mechanism should have, in order to ensure the motor at various locations pipeline girth accurate alignment, but with a more good speed tracking. Wire agencies must ensure that accurate and stable wire feed speed, has a smaller moment of inertia, better dynamic performance, but should have sufficient driving torque. The regulatory agencies should have a gun swinging around the weld torch relative to swing left and right ends of stay, up and down gesture control, torch angle adjustable function. Each of the above part of the welding trolley, a computer-implemented by a programmable automatic control, the program starts, the operation of each part of the welding carriage according to the logic of the coordination program order.
Track is chucking in the pipe welding trolley travel and positioning altar dedicated mechanism which directly affects the structure and location of the weld smooth trolley travel, also affect the quality of welding. Track should satisfy the following conditions: easy assembly and disassembly, easy to locate; reasonable structure, lighter weight; there is a certain strength and hardness, wear and corrosion resistance. Track divided into rigid and flexible rail track two. The so-called rigid body stiffness of the track means the track is large, easily deformed, and the flexible track is relatively rigid orbits. Two types of tracks each have their own characteristics. Rigid track positioning accuracy, after chucking small deformation, welding carriage to ensure smooth running, welding torch radial adjustment is small, but the larger the weight, assembly and disassembly inconvenient. The flexible track assembly and disassembly, lighter, high accuracy is not rigid track.
Smooth wire feeding directly affect the degree of weld quality. Wire mode can be simply pushed into the drawing and silk in two ways. When drawing the gun from the mounting position closer to the wire feeder, the smaller the process after welding wire feeder wire left by the resistance, so you can ensure a smooth wire feeding process, but the wire feeder and welding wire tray must be installed in the car's on the increase in the weight of the welding carriage, give artificial assembly and disassembly increases the difficulty, but also likely to cause an increase in weight is not stable welding trolley travel.
Currently, in addition to using manual welding, the pipe welding is the use of more automatic submerged arc welding process and GMAW processes. Submerged arc welding has good weld, welding, high efficiency, low cost welding for pipeline construction, the submerged arc welding can be used for dual inline welding, referred to as "the second pick one," that the torch is fixed at a certain position, the tube is rotated. Obviously impossible to make long-distance pipeline welding tube rotates, thus "two pick one" can only be used prefabricated pipe. If the pipeline all-position welding using automatic submerged arc welding process, you must add the welding device with solder delivery, supporting the recovery mechanism, so that the structure of the welding device becomes more complex to operate and dismantle the inconvenience, and increased a trolley load, impact trolley smoothness. Submerged arc welding is generally coarse, high current welding for all-position automatic welding may occur due to high deposition rates drop droplet flow, such as welding defects, affecting the quality of the weld forming and will therefore submerged arc applies to all position welding automatic welding pipe is quite difficult to implement.
Using gas-shielded flux-cored welding process plus, if multiple passes molding, the surface of the weld slag each time and labor; if forced molding, shall be equipped with a gun plus a molded copper sliders move together and pass into cooling water, can greatly improve the welding efficiency, so that not only the structure of the complex welding apparatus, and increased weight. Because of higher prices flux cored wire, while also addressing the protective gas gas source, so the higher the welding costs. Single-use self-shielded welding wire, shielding gas, although savings, but there are difficult issues slag. Using solid core wire welding gas welding process, if multiple passes molding, the welding process can be simply divided into primer, filling, cover three stages faces, no clean weld surface and directly next step, but welding speed is relatively slow in terms of forcing molding. Usually the shielding gas is pure carbon dioxide gas, carbon dioxide and argon or a mixed gas of carbon dioxide and oxygen. Gas mixture of carbon dioxide and argon arc welding can make combustion stability, spatter small, but when the field work hard to find the source of argon gas, higher prices, from economic considerations, when welding the pipeline, the best possible using pure carbon dioxide as a protective gas.
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