Finite Element Analysis And Improvement Of Welding Structure Of Vacuum Packaging Machines

Vacuum packing machine is mainly made up of vacuum cover and vacuum chamber two parts, and the packing work for vacuum packaging machine was mainly occurred in a closed vacuum space which formed by the vacuum lid and chamber. After welding, it is easy to produce large deformation and residual stress. The vacuum lid and vacuum chambers prone to cracks and large plastic deformation due to frequent pumping pressure and external air pressure during working. How to improve the stress concentration and deformation is the focus of this paper.In this paper, studying the structure and welding technology of vacuum packaging machine produced by Hualian Machinery Group which is a famous Chinese packaging machinery company. The original vacuum packaging machine vacuum cover always has quality instability,cracking, failure and other issues. Through finite element analysis find that the design structure is unreasonable and there is stress concentration at the diagonal and great deformation impact on the assembly accuracy.The vacuum chamber in the combination of steel and bending plate welding stress is more concentrated, and also easy cracked, which seriously affect the vacuum packaging machine quality and service life.Through study these issues, use of optimization structure and adjust the welding process to solve the problem. For the vacuum cover in the stress concentration area, according to the stress concentration and gradient relationship apply different shapes and sizes of the triangular plate stiffeners. The vacuum chamber is to reduce the weld, and the vacuum chamber of the central beam is not using welding but the use of mechanical methods and the bending plate to be improved. The two corners of the bottom of the bending plate are cut off, and the sides of the bending plate trimming. Not only make the shape beautiful but save resources and reduce the costs.This paper uses finite element analysis software to help the structure optimization. Since the vacuum cover is made of the 304 stainless steel which thickness is 4 mm. It is difficult to single-sided welding to complete double-sided molding with an argon arc welder, so that double-sided are welded. Since the vacuum cover has a different slope, the weld width becomes larger as the slope increases. As the heat source check also need to be based on the actual situation, which increases the difficulty of simulation. First cutting the 4mm thick 304 stainless steel and then making the corner weld test and butt welding test. Analysis of test results to identify the smallest residual stress in the experimental group. And the heat input fitting, according to the welding method to find fit heat source. The heat-source test is performed on each of the three groups of experiments to find the group with the smallest heat-affected zone, and the best experimental group is then identified by combining the group with the least stress. The best experimental group is the set of experiments to be verified by the heat source. The temperature field and residual stress and strain of the welding process are simulated by software.At last, the simulation of the vacuum cover and the vacuum chamber is carried out by using the calibrated heat source to understand the changes of the temperature field and the stress field during the welding process.The distribution of stress field under different load and under different constraints is also analyzed which provides the theoretical basis and guidance for the structural optimization of vacuum packaging machine and also has great significance in actual production.