Double-beam laser welding method for exhaust pipe barrel and flange

Abstract

The invention relates to a double-beam laser welding method for an exhaust pipe barrel and a flange. The double-beam laser welding method comprises the following steps that firstly, welding edges of the exhaust pipe barrel and the flange are machined into annular welding edges; secondly, according to the design parameters of the annular welding edge, a double-beam laser welding geometric position form and a welding path are planned; 3, double-beam laser welding parameters are determined; fourthly, according to double-beam laser welding parameters, double-beam laser welding is conducted on the flange and the exhaust pipe barrel; the first step comprises the steps that an annular groove is formed in the inner side of the welding edge of the flange, and the radial height of the annular groove of the flange is consistent with the wall thickness of the exhaust pipe barrel; the welding edge of the exhaust pipe cylinder is assembled in the annular groove of the flange in an inserted mode. According to the method, reliable welding of the butt joint area of the flange and the exhaust pipe barrel and sufficient fusion of the interface of the lap joint area are achieved, and welding seam forming is remarkably improved.

Description

technical field [0001] The invention relates to the technical field of aircraft engine exhaust pipe welding, in particular to a double-beam laser welding method for an exhaust pipe cylinder and a flange. Background technique [0002] The engine exhaust pipe of a large-scale fire extinguishing / water rescue amphibious vehicle includes parts such as flanges, exhaust pipe barrels, and reinforcing rings. The flange is usually set at the end of the exhaust pipe, and is installed near the engine through fasteners; the flange is a ring-shaped machined part, and the thickness of the part connected to the exhaust pipe cylinder is 4mm-8mm. The cylinder body of the exhaust pipe is a thin-walled shell structure, which is usually manufactured by sheet metal method, the central axis is a space curve, and the wall thickness ranges from 0.8mm to 1.5mm. The reinforcing ring is usually set at the tail of the exhaust pipe, and is also installed on the body through fasteners. The length of the ...

AI Technical Summary

Problems solved by technology

[0005] Both the first and second welding methods use argon arc welding to realize the circular connection between the exhaust pipe flange and the cylinder body. Due to the large heat input and wide welding width of argon arc welding, the welding deformation is large and the discharge The roundness tolerance of the gas pipe after welding can only be controlled within the range of ±3mm, resulting in a large deviation between the actual service life of the exhaust pipe and the design life; the residual stress of argon arc welding is large, and stress relief annealing is required after welding; 3. While the melting width is wide, the sag on the back of the weld is relatively large, resulting in a relatively high grinding strength of the weld on the inner wall of the exhaust pipe

Compared with the first connection method, although the second connection method can slightly reduce the welding deformation of the exhaust pipe, it not only increases the sudden change in the geometric size of the inner wall of the exhaust pipe, but also affects the exhaust pipe to a certain extent. Function will have a certain impact, and the unfused interface inside the lap joint can easily accelerate crack initiation and propagation under fatigue load and reduce the service reliability of the structure

The third connection technology is limited by the small diameter of the laser beam spot and the small welding pool, resulting in a narrow welding process margin. When the laser beam trajectory deviates from the preset trajectory by more than 0.2mm, it is easy to produce the top of the flange welding edge The edge is not fully melted, and there are problems such as welding toe undercut in the overlapping area of ​​the flange and the cylinder welding joint. image 3 As shown, the formed laser weld 4 and weld toe undercut 41

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