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The points for attention in the remanufacturing of coal mill composite roller
Addtime: 2019-11-8 10:23:31 click: 68
Power plants are big consumers of coal and wear out a lot of equipment. The remanufacturing of coal mill composite roller is often used in power plant. This method has many advantages, but there are some matters needing attention to be grasped firmly, so as to ensure the perfect development of this technology.
(1) the speed of surfacing welding on the first layer should be slightly slower; The welding sequence starts from the most serious wear and gradually surfacing to the design size of grinding roller.
(2) layered surfacing welding is adopted. After welding 1 layer, another layer is welded. The weld bead of the latter welding layer is arranged between the 2 weld passes of the former welding layer. Taking 3.2mm flux-cored wire as an example, the suitable weld bead shape for submerged arc surfacing is 8.0mm wide to 12.0mm wide and 3.0mm high to 3.5mm narrow. The suitable weld pass shape for open-arc submerged arc surfacing welding is 10.0mm to 16.0mm wide and 3.0mm to 4.0mm high.
(3) appropriate welding process parameters should be selected, so as to reduce spatter, improve bead formation and make it beautiful. Attention should be paid to adjusting welding process parameters during welding.
(4) for serious wear parts should use good wear resistance welding wire.
(5) in order to reduce the layer temperature, facilitate continuous surfacing and improve the surface hardness of weld seam, water is generally added to cool the roller body in the submerged arc surfacing. In open-arc surfacing welding, the bead is cooled by water mist. If the temperature is too high, a small amount of water can be used on the surface to reduce the layer temperature and improve the hardness of the weld.
(6) the evenly distributed dense turtle cracks on the surface of the weld bead are caused by stress release. Although the micro-cracks reduce the strength of the weld, they are beneficial to avoid the surfacing layer shedding and peeling phenomenon in the use of the grinding roller. Therefore, tight turtle cracks are allowed, but no penetration cracks or dense pores in the surfacing layer are allowed.
Many experienced technicians in the power plant have a good understanding of these considerations and are very skilled in the operation of this technology. They often say that these considerations are summed up through a lot of practical operations and are the best teaching material for young technicians to learn, so they are very precious.
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