Method for controlling penetration energy in electron beam welding of hollow blade

Abstract

The invention belongs to the field of electron beam welding, and particularly relates to a method for controlling penetration energy in hollow blade electron beam welding. According to the technical scheme, the method comprises the following steps that (1) an air inlet casing is combined and assembled; 2) welding and positioning the hollow blade; 3) electron beam welding on one side of the hollow blade; feeding the positioned and welded air inlet casing into a vacuum chamber, and vacuumizing; the electron beam track is adjusted to coincide with a welding seam on one side of the hollow blade, electron beam welding is conducted, and parameters are as follows: the acceleration voltage is 90-120 KV, the focusing current is 1700-1730 mA, the speed is 15-20 mm / s, the welding current is 7-12 mA, the electron beam scanning waveform is circular wave, the amplitude is 0.5-1 mm, and the frequency is 500-1000 Hz; according to the electron beam welding method, electron beam spot energy distribution is regulated and controlled through electron beam welding parameter optimization and verification, and the problems of penetration burn and splash in electron beam welding of the hollow blade of the air inlet casing are solved.

Description

Technical Field

[0001] The present invention belongs to the field of electron beam welding, and particularly relates to a method for controlling the penetration energy in electron beam welding of hollow blades. Background Art

[0002] The material of the inlet casing is titanium alloy, which is an important load-bearing component on an aero-engine. It is composed of an outer casing, an inner casing, and numerous hollow blades welded together. Among them, the hollow blade is a long and narrow thin-walled cavity structure, and the full-profile blade is connected to the inner and outer casings through electron beam welding on both sides respectively. Due to the high energy density of the electron beam, there are often problems of backside burn and spatter during welding, which will bring greater deformation, stress, performance loss, and foreign matters. Generally, in open components, it is controlled by adding a protective plate on the back of the weld. Since the distance between the two side profiles of the hollow blade is only 3 - 5 mm and the inner cavity is completely closed, the method of adding a protective plate cannot be used for control. When electron beam welding is performed on one side of the hollow blade, due to the high energy density of the electron beam, after penetrating and melting the weld, the remaining energy will directly act on the inner surface of the other side. Due to the small distance between the two sides, the remaining electron beam energy can still melt the metal surface to form a weld. In addition, the remaining high-energy electron beam will also disturb the weld metal molten pool, resulting in an unstable molten pool. Fine metal droplets will fly out from the molten pool, move along the direction of the electron beam energy, and adhere to the surface of the narrow blade inner cavity, forming spatter. The penetration burn and spatter in the inner cavity will affect the manufacturing quality of the inlet casing. Summary of the Invention

[0003] The present invention provides a method for controlling the penetration energy in electron beam welding of hollow blades. Through the optimization and verification of electron beam welding parameters, the energy distribution of the electron beam spot is regulated. On the basis of ensuring the weld quality, the problems of penetration burn and spatter in electron beam welding of the hollow blades of the inlet casing are eliminated, the processing quality of the inlet casing is improved, the deformation and residual stress are reduced, and the service life and reliability are enhanced.

[0004] The technical solution of the present invention is as follows: A method for controlling the penetration energy in electron beam welding of hollow blades includes the following steps: 1) Assembly of the inlet casing components; assemble the hollow blade, outer casing, and inner casing on the welding fixture to ensure that the gap of the hollow blade welding joint is not greater than 0.05 mm and the misalignment is not greater than 0.12 mm, meeting the assembly requirements for electron beam welding; 2) Welding positioning of the hollow blade; adjust the electron beam trajectory to coincide with the weld, and use a small-current electron beam to perform tack welding on both sides of the hollow blade respectively. The parameters are as follows: acceleration voltage 90 - 120 KV, focusing current 1630 - 1660 mA, speed 15 mm / s, welding current 2 - 3 mA, the electron beam scanning waveform is a triangular wave, the amplitude is 1.0 mm, and the frequency is 50 Hz; 3) Electron beam welding on one side of the hollow blade; Feed the inlet casing with the tack welding completed into the vacuum chamber and evacuate the air. Adjust the electron beam trajectory to coincide with the weld seam on one side of the hollow blade and perform electron beam welding. The parameters are as follows: accelerating voltage 90 - 120 KV, focusing current 1700 - 1730 mA, speed 15 - 20 mm / s, welding current 7 - 12 mA. The electron beam scanning waveform is a circular wave, amplitude 0.5 - 1 mm, frequency 500 - 1000 Hz; 4) Electron beam welding on the opposite side of the hollow blade; Adjust the position and angle of the inlet casing, adjust the electron beam trajectory to coincide with the weld seam on the opposite side of the hollow blade and perform electron beam welding. The parameters are the same as those in step 3).

[0005] The beneficial effects of the present invention are as follows: The present invention mainly controls the energy distribution of the electron beam spot. Under the condition of ensuring weld fusion, it reduces the penetration energy density and controls the stability of the molten pool. The regulation of the electron beam energy density is mainly achieved through the optimal matching of parameters such as accelerating voltage, focusing current, welding speed, welding current, scanning amplitude, and frequency. Therefore, first, by reducing the accelerating voltage, the penetration ability of the electron beam is reduced, and the keyhole welding of the hollow blade is adjusted to conduction welding. Secondly, the focusing current is adjusted to increase the beam spot size, slow down the transition between the molten pool and the base metal, and improve the stability of the molten pool. Then, the electron beam scanning amplitude and frequency are adjusted to fully stir the molten pool, reduce the probability of internal porosity defects in the weld seam, and refine the grains. The above measures are combined with the electron beam welding process test to verify the matching relationship between the parameters, so as to modulate reasonable welding parameters, thereby eliminating the problems of penetration burn and spatter during the electron beam welding of the hollow blade, improving the weld quality, reducing the welding deformation and residual stress of the inlet casing, improving the machining quality of the inlet casing, and increasing the service life and reliability. Specific embodiments

[0006] A method for controlling the penetration energy in electron beam welding of a hollow blade, comprising the following steps: 1) Assembly of the inlet casing; Assemble the hollow blade, outer casing, and inner casing on the welding fixture, ensuring that the gap of the welding joint of the hollow blade is not greater than 0.05 mm and the misalignment is not greater than 0.12 mm, meeting the assembly requirements for electron beam welding; 2) Welding positioning of the hollow blade; Adjust the electron beam trajectory to coincide with the weld seam, and use a small-current electron beam to perform tack welding on both sides of the hollow blade respectively. The parameters are as follows: accelerating voltage 100 KV, focusing current 1650 mA, speed 15 mm / s, welding current 2.5 mA. The electron beam scanning waveform is a triangular wave, amplitude 1.0 mm, frequency 50 Hz; 3) Electron beam welding on one side of the hollow blade; Feed the inlet casing with the tack welding completed into the vacuum chamber and evacuate it; Adjust the electron beam trajectory to coincide with the weld seam on one side of the hollow blade and perform electron beam welding with the following parameters: acceleration voltage 100 KV, focusing current 1720 mA, speed 20 mm / s, welding current 10 mA, the electron beam scanning waveform is a circular wave, amplitude 0.5 mm, frequency 500 Hz; 4) Electron beam welding on the opposite side of the hollow blade; Adjust the position and angle of the inlet casing, adjust the electron beam trajectory to coincide with the weld seam on the opposite side of the hollow blade and perform electron beam welding with the same parameters as in step 3).

[0007] Use visual inspection, X-ray inspection and penetrant inspection methods to check the quality of the electron beam weld seam of the hollow blade. No defects exceeding the standard are found, meeting the secondary weld standard. Use a borescope to visually inspect the inside of the hollow blade of the inlet casing. No burns or spatter are found in the weld seam and base metal area of the inner cavity of the hollow blade, and only the phenomenon of metal vapor plating exists.

Claims

1. A method for controlling the penetration energy in electron beam welding of a hollow blade, characterized in that, The steps are as follows: 1) Assembly of the inlet casing; Assemble the hollow blades, outer casing and inner casing on the welding fixture, ensuring that the gap of the welding joint of the hollow blades is not greater than 0.05 mm and the misalignment is not greater than 0.12 mm, meeting the assembly requirements of electron beam welding; 2) Welding positioning of the hollow blades; Adjust the electron beam trajectory to coincide with the weld seam, and use a small current electron beam to perform tack welding on both sides of the hollow blades respectively. The parameters are as follows: acceleration voltage 90 - 120 KV, focusing current 1630 - 1660 mA, speed 15 mm / s, welding current 2 - 3 mA, the electron beam scanning waveform is triangular wave, amplitude 1.0 mm, frequency 50 Hz; 3) Electron beam welding on one side of the hollow blade; Send the inlet casing with tack welding completed into the vacuum chamber and evacuate; Adjust the electron beam trajectory to coincide with the weld seam on one side of the hollow blade and perform electron beam welding. The parameters are as follows: acceleration voltage 90 - 120 KV, focusing current 1700 - 1730 mA, speed 15 - 20 mm / s, welding current 7 - 12 mA, the electron beam scanning waveform is circular wave, amplitude 0.5 - 1 mm, frequency 500 - 1000 Hz; 4) Electron beam welding on the opposite side of the hollow blade; Adjust the position and angle of the inlet casing, adjust the electron beam trajectory to coincide with the weld seam on the opposite side of the hollow blade and perform electron beam welding. The parameters are the same as those in step 3).