Vacuum brazing method for pump impeller

Abstract

The invention relates to a vacuum brazing method for a pump impeller, which comprises the following steps: 1) cutting soldering terminals into shapes corresponding to those of the cross sections of blades on an impeller, and punching positioning holes on the 2 to 3 soldering terminals; 2) cleaning a pump impeller to be welded and the soldering terminals, and checking the smoothness of welding surfaces of the blades; 3) preheating the pump impeller to be welded; 4) coating the welding surfaces of the blades to be welded with welding flux, placing the soldering terminals on the welding surfaces of the blades, and then coating the welding flux on the upper surfaces of the soldering terminals; 5) using a pump cover to cover the upper surfaces of the soldering terminals, and using positioning pins to fix the pump cover on the soldering terminals; 6) assembling an upper pressed tyre and a lower pressed tyre together by the pump impeller to be welded; 7) sending an assembly into a heating chamber in a vacuum furnace for heating; and 8) taking out a workpiece after the temperature reduction. The pump impeller brazed by the method has uniform and full welding seams, apparent circular arcs at interfaces, compactly combined welding surfaces, no air holes, high welding strength, and longer service life.

Description

technical field [0001] The invention relates to a brazing method, in particular to a vacuum brazing method for a pump wheel in a hydraulic transmission shunting transmission box. Background technique [0002] In the power transmission process of the locomotive, the transmission wheels such as the pump wheel in the hydraulic transmission shunting transmission box undertake the task of power transmission and play an important role in the overall performance of the locomotive. The production method is machining and then using salt bath The brazing method is welded, and the raw materials used in the salt bath brazing method mainly include solder, flux, flux (salt for brazing), and the contents of each component are as follows (as shown in Table 1): [0003] Table 1 [0004] [0005] The salt bath brazing method is: first cut the welding piece into the shape of the impeller of the pump wheel, which is slightly larger than the outer edge of the impeller, then apply flux, conne...

AI Technical Summary

Problems solved by technology

However, the saturated vapor pressures of zinc and cadmium used in the salt bath brazing method are 133.3×10 2 MPa, 133.3×10 3 Mpa, therefore, these two raw materials are almost completely volatilized at the working temperature, resulting in low welding bonding strength and insufficient weld seam

Therefore, the solder composition used in the salt bath brazing method is not suitable for brazing in a vacuum state, and the material cannot contain phosphorus, cadmium, zinc, lithium, etc.

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