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Abstract. Taking overlap joint as the object, it simulates welding process. And it obtains residual stress and distribution curves. By simulating the equivalent form of tack welding, it discusses the influence of tack welding by XYZ displacement constraint, X displacement constraint, node matching and adhesive contact on stress distribution. It verifies the results. The results show that four sets of tack welding are designed, and it calculates stress distributions. By XYZ displacement constraint, X displacement constraint and node matching, the simulation results is not consistent with the classical longitudinal stress distribution. By adhesive contact, the stress distribution is consistent with the test results, and error is controlled within 12.9%. It verifies the equivalent form of tack welding. Without considering tack welding, error is 40.3% at the distance from arc building of 50 mm. It does not meet the application requirements. It suggests that tack welding influence on the welding residual stress should be considered in the small model, and it simulates tack welding by adhesive contact.

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To effectively enhance the service life, the research of milling machine scraper structure design and welding process are optimized. Through the structural optimization analysis, the improved structure is obtained, and the working resistance force is reduced. The full factor test is used to optimize the brazing process, and the best parameters are obtained, which improves the shear strength. The accuracy of the model is verified by experiments. The results show that compared with the working resistance force, the improved scraper tends to be slow and the peak value is smaller. The cutting rake and relief angle of the scraper are optimized. When the cutting rake angle is 6° and the cutting relief angle is 9°, both working resistance force and impact force are minimum. It proves the accuracy of the simulation results. Using CT861 solder, brazing temperature is 75°C, and the brazing time is 10s. While the cooling method uses furnace cold, the minimum value of shear strength is 200MPa. The average working life of the scraper is raised from 800 hours to 1600 hours after the optimization design. Research results have guiding significance for the structure design and the welding process optimization of the scraper.