Here is China Standard Heavy Steel Rail Manufacturer talking about the
precautions for the welding rail process.
The process of welding the rail is a local rapid heating and cooling process. The welding zone cannot be freely expanded and contracted due to the restraint of the surrounding work piece body, and the welding stress and deformation are generated in the weldment after cooling. Important products need to eliminate welding stress after welding and correct welding deformation. Let's take a look at the precautions for the welding process:
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1. The cross-sectional shape of the butt joint weld is determined by the thickness of the welded body before welding and the groove form of the two joints. When welding a thick steel plate, grooves of various shapes are opened at the joint edges for penetration to facilitate feeding of the welding rod or the welding wire. The groove form has a single-sided welded groove and a double-sided welded groove. When selecting the groove form, in addition to ensuring the penetration, it is also necessary to consider the convenience of welding, the small amount of filler metal, the small welding deformation and the low processing cost of the groove.
2. When two steel plates with different thicknesses are butt jointed, in order to avoid serious stress concentration caused by sharp changes in the cross section, the thicker plate edges are gradually thinned to reach equal thickness at the two joint edges. The static strength and fatigue strength of the butt joint are higher than other joints. Welding of butt joints is often preferred over joints that operate under alternating, impact, or low temperature, high pressure vessels.
3. The pre-weld preparation of the lap joint is simple, the assembly is convenient, the welding deformation and residual stress are small, so it is often used in the installation of joints on the construction site and unimportant structures. In general, lap joints are not suitable for operation under alternating loads, corrosive media, high temperatures or low temperatures.
4. The use of T-joints and corner joints is usually due to structural requirements. The work characteristics of the fillet welds that are not welded on the T-joint are similar to the fillet welds of the lap joint. When the weld is perpendicular to the direction of the external force, it becomes a front fillet weld. At this time, the shape of the weld surface will cause different degrees of stress concentration; the weld of the fillet weld is similar to that of the butt joint.
5. The angular joint has low bearing capacity and is generally not used alone. It is only improved when it is welded through, or when there are fillet welds inside and outside, and it is mostly used at the corner of the closed structure.
6. The welding product is lighter than the riveting parts, castings and forgings, which can reduce the weight and save energy for the transportation tools. The welding has good sealing properties and is suitable for manufacturing various types of containers. The development of joint processing technology, welding, combination of forging and casting, can be made into a large, economical and reasonable cast-welded structure and forged welded structure, with high economic benefits. The welding process can effectively utilize the materials, and the welded structure can use different performance materials in different parts, giving full play to the advantages of various materials to achieve economic and high quality. Welding has become an indispensable and increasingly important processing method in modern industry.
7. On the other hand, it is necessary to improve the level of welding mechanization and automation, such as the realization of program control and digital control of the welding machine; the development of special welding machines for the whole process from preparation process, welding to quality control; in the automatic welding production line, promote and expand the numerical control Welding robots and welding robots can improve the level of welding production and improve the sanitary and safety conditions of welding.
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