Numerical Simulation Of High Pressure Cylinder Necking Plastic Forming And Defect Prediction

This topic come from one product quality improvement project based on steel and aluminum cylinder of a cylinder factory in Shanghai.High pressure cylinder as an important component of the production safety equipment, belongs to the special equipment category,and plays more and more important role in the national economy. Because cylinder is mainly used to store high pressure gas, so in the cylinders production process,the control to the cylinder quality must be extremely strict. This requires cylinders deformation process be tight rein about the deformation parameters,to ensure the process accuracy and coherence.At the same time this put forward higher request to the cylinder test equipement.There are mainly two kinds of cylinder forming method:extrusion forming and spin forming.The two methods belong to nocutting-shape,and the property is superior to the welded gas cylinder.At present the two kinds of cylinder accounted for more than 90 percent. So we study and contrast the two kinds of cylinder forming method comprehensively,there is general sense on the cylinder deformation study.According to the high pressure cylinders high safety requirement and the complex process of forming, we observe the cylinder production process carefully,study the core process of cylinder,based on the factory practice,we analysis the main parameters of the cylinder deformation.The main parameters of spinning include spin roller outline,the temperature,the speed of main spindle,spinning feed speed,spin pass and so on. Stretching extrusion process main parameters include necking coefficient, heating temperature, lubricated friction coefficient,main shrinkage mouth coefficient, the heating temperature, lubrication friction coefficient, extrusion speed, etc. Through the study of the cylinder deformation characteristics, preliminarily analysis of the key factors leading to deformation defects. By finite element numerical simulation technology, we make necessary simplification to the practical production process, establish a spinning cylinders finite element model and a extrusion cylinder finite element model, and use the Abaqus software to simulate the spinning forming, use the Deform software to simulate extrusion process. This paper analyzes the forming mechanism and the stress state in the forming process, put forward the parameters effect of forming defects, and provides theoretical support for practical production cylinders forming and prevention cylinder defects.For the formed cylinder, it is important to check the deformation defects.The hydrostatic test is designed just for the cylinder defects test.lt has been seemed as the necessary test equipment before the cylinder out of the factory.The hydrostatic test equipment we designed is currently in the domestic leading level,can check the, can accurately detect the inner surface defects, internal cracks, stack, stoma defects and so on.