Design Of Large Combinable Electron Beam Welding Vacuum Chamber

Electron beam welding is increasingly used in defense and aerospace applications,but limited by the size of electron beam welding vacuum chambers,many large-scale spacecraft components cannot be integrally welded in a vacuum chamber.This project designs a large-scale combinable electron beam welding vacuum chamber to solve this problem.The vacuum chamber can increase or decrease the number of intermediate sections of the vacuum chamber cylinder according to the size of the welded components,which can satisfy various large components' overall welding requirements.The vacuum chamber is mainly composed of a cylinder,a head and a frame.The vacuum chamber is designed as a vertical cylindrical structure with a diameter of 8m.The vacuum chamber is designed as a combinable structure.The height of each cylinder structure is 4m,and a maximum of 4 knots can be combined.The vacuum chamber cylinder is designed as a double-layer structure,and the interlayer is a honeycomb structure.The wall thickness of the vacuum chamber cylinder and the size of the rib are calculated according to the empirical formula in the vacuum design manual.The model was imported into the Workbench software to optimize the response surface of the honeycomb structure,and the finite element static analysis was performed on the optimized model.The design of the bottom hole of the vacuum chamber is calculated according to the empirical formula,and the part with large deformation is reinforced.For simulation analysis,the deformation and stress strength at the opening meet the design requirements.Under the condition that the design requirements are met,four types of flat heads,elliptical heads,butterfly heads and spherical heads are designed.The size of the head and the size of the ribs are optimized for finite element static.mechanical analysis.The evaluation indexes of the four types of heads were comprehensively compared,and the flat cover head was finally selected.According to the design requirements,the vacuum chamber frame is designed to withstand and transfer the weight of the vacuum chamber itself and the additional pressure of the atmospheric pressure after vacuuming,and optimize the response surface of the weight and deformation of the frame.The finite element static analysis of the vacuum chamber is carried out.The maximum displacement of the vacuum chamber is located at the center of the head.The maximum deformation is 3.82 mm.The overall deformation of the vacuum chamber is gradually reduced from top to bottom.The radial direction of the wall of the vacuum chamber The deformation is about 0.25 mm.The stress concentration mainly occurs at the joint edge of the head frame and the vacuum chamber cylinder frame,the stress intensity is less than the yield strength of Q690 steel,and there is no obvious stress concentration at other positions.The overall weight of the vacuum chamber is 210 t.The finite element buckling analysis of the vacuum chamber is carried out,and the first 4th buckling mode of the vacuum chamber is analyzed.The critical instability external pressure of the vacuum chamber is 0.959 MPa.The vacuum chamber structure has sufficient rigidity to ensure safety and stability.Based on the modal analysis theory,the first 9 modes of the vacuum chamber are extracted,and the first 9 natural frequencies and corresponding vibration patterns of the vacuum chamber are obtained.For the safety and stability of the vacuum chamber,the operating frequency should be effective.Avoid the natural frequency of the vacuum chamber and use vibration isolation measures to avoid excitation of the vacuuming device to form resonance.