Causes of wear
Shaft wear is the most common equipment problem during shaft use. There are many reasons for shaft wear, but the main reason is the metal characteristics used to make the shaft, although the metal has high hardness, but poor concession (can not be restored after deformation), poor impact resistance, poor fatigue resistance, so it is easy to cause adhesive wear, abrasive wear, fatigue wear, fretting wear, etc., most of the shaft wear is not easy to detect, only when the machine high temperature, large runout, abnormal noise, etc., will cause people to notice, but by the time people find out, most of the shafts have been worn, This results in machine downtime.
For technology
Repair of large equipment shaft heads after wear is a concern. When the material of the shaft is 45 gauge steel (quenching treatment), if only surfacing is used, internal welding stress will occur, and cracks or even fractures may occur at the shaft shoulder under heavy load or high-speed operation. If stress relief annealing is used, it is difficult to operate, and the processing cycle is long, and the maintenance cost is high. When the shaft material is HT200, cast iron welding is also not ideal. Domestic for shaft wear generally use repair welding, shaft sleeve, pockmarks, etc., if the downtime is short and spare parts, generally use to replace the new shaft, some maintenance technology higher enterprises will use brush plating, laser welding, micro-arc welding and even cold welding, etc., these maintenance technologies need to purchase high equipment and high wages to hire skilled workers, some domestic small and medium-sized enterprises generally through higher technology outsourcing to help repair high-value shafts, but to pay high maintenance costs and transportation costs.
Repair technology
For the above repair technology, in Europe, America, Japan and South Korea enterprises is not very common, because the traditional technology effect is poor, and laser welding, micro-arc welding and other advanced repair technology on equipment and personnel requirements are high, the cost is large, Europe, America, Japan and South Korea generally use carbon nanopolymer material technology and nanotechnology, on-site operation, not only effectively improve the maintenance efficiency, but also greatly reduce the maintenance cost and maintenance intensity. Because the metal material is a "constant relationship", although the strength is high, but the impact resistance and concession are poor, so the long-term operation will cause the mating gap to increase and cause shaft wear, after realizing this key reason, the polymer composite material developed by the European and American new technology research institutions has the strength and hardness required by the metal, and has the concession (variable relationship) that the metal does not have, through the "tooling repair", "component correspondence", "machining" and other processes, It can ensure the size of the repair part and the matching parts to the greatest extent; At the same time, the use of the composite material itself has comprehensive advantages such as compression resistance, bending resistance, elongation, etc., can effectively absorb the impact of external forces, greatly dissolve and offset the radial impact of the bearing on the shaft, and avoid the possibility of clearance, which avoids the wear of relative movement caused by the increase of the clearance, so for the static fit of the shaft and the bearing, the composite material does not rely on "hardness" to solve the wear of the equipment, but by changing the relationship between the force to meet the operating requirements of the equipment.
