Laser cladding equipment uses a high-energy laser beam as a heat source to cladding powder materials on the surface of parts to prepare high-performance protective coatings, thereby improving the surface hardness, wear resistance, corrosion resistance, oxidation resistance, high temperature resistance and other properties of the material. It has a wide range of applications in the field of surface repair and remanufacturing of mechanical parts.The following will take the high-speed spline wheel as an example to discuss the application of laser cladding equipment in the field of surface repair and remanufacturing of mechanical parts.
Causes of Wear of High-Speed Spline Wheels
At present, my country’s military aviation is in a high-speed development stage, so people have put forward higher requirements for the safety of aero engines. Therefore, in order to fully guarantee the safe operation of aero engines, improve the safety performance of aero engines, and avoid major safety accidents, it is necessary to conduct regular maintenance on the aero engine parts on the ground. In the maintenance process, high-speed and high-precision gearbox equipment is required to simulate the high-speed and high-pressure working state of the engine. This kind of gear equipment is affected by factors such as alternating load, poor lubrication and poor heat dissipation during long-term use, which easily causes the spline part of the gearbox output shaft to wear and cause the gearbox to fail.
The original maintenance plan is to replace the new shaft regularly, but in the manufacturing cost of the entire shaft, the cost of the helical gear exceeds 70%, and the cost of the spline gear does not exceed 10%. If the spline parts are replaced due to wear and tear, a large amount of material will be wasted, which does not comply with the national policy of energy conservation and emission reduction. At present, the laser cladding process, as one of the remanufacturing technologies, is an effective technology for preparing alloy coatings, through which low-dilution and high-performance metallurgical bonding layers can be obtained. Compared with the traditional surfacing welding process, laser cladding technology has the advantages of small heat input, extremely fine microstructure and easy to realize precise control and industrial automation. It has a wide range of applications in the field of surface repair and remanufacturing of mechanical parts.
The laser metal deposition process of the spline gear shaft is: disassembly and cleaning, flaw detection before repair, cutting and polishing of the repaired part, laser cladding, spline processing, dynamic balance test, and flaw detection after repair. The detailed requirements of each process are as follows:
Disassembly and Cleaning:
Before the spline gear shaft is officially repaired, the gear box must be opened first, and then the worn spline gear shaft must be removed from the gear box. Finally, the bearings at both ends of the spline gear shaft must be removed with special tools. Due to the residual lubricating fluid and wear residue on the gear, after disassembly, the shaft needs to be placed in an ultrasonic cleaning tank, cleaned with a special alkaline cleaning fluid for 2 hours, and then dried with compressed air to prepare for the next step.
Flaw Detection Before Repair:
Since the gear of the spline gear shaft needs to withstand a speed of up to 28000r/min, it is a high-speed and high-precision shaft, so the gear of the shaft is a helical gear. In the entire shaft manufacturing process, the manufacturing cost of the helical gear exceeds 60%, and the difficulty of repairing the helical gear is high, the cost is high, and the stability of the repair layer is difficult to guarantee at high speeds. If the tooth surface of the helical gear is damaged, from a cost perspective, the shaft has lost the need for repair. If the gear is intact, proceed to the next step. Generally, most spline gear shafts are unusable due to excessive wear of the spline.
The scanning speed of cladding, the amount of overlap and the programming of other parameters are set together by the three-axis motion equipment and the rotating equipment. The defocus amount and spot position of the cladding are set together by the three-axis motion equipment and the position of the workpiece. The prefabricated powder feeding method is adopted to adjust the powder feeding amount of the powder feeder to reach the predetermined cladding thickness. Adjust the laser control cabinet and set the laser cladding power. When cladding the surface layer, reserve surface cooling time between each layer to reduce local temperature and prevent cracks and deformation. After repairing, put it into the incubator to cool down naturally.
The results show that the temperature of laser cladding has little effect on the material of the shaft base layer; the cladding layer is cladding with a higher hardness powder, which increases the wear resistance of the surface layer and improves the service life of the spline. Compared with the new shaft, the repair shaft has better performance, and the time cost and maintenance cost are lower. Therefore, the laser cladding technology has high maintainability for the repair of spline gear shafts.
Jinan SENFENG Technology Co., Ltd. has established a laser cladding technology research and development center, production and processing center. If you want to know more about laser cladding machine, please contact SENFENG LEIMING.
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