Research On Material Forming Simulation Analysis And Centering Detection System Of Hydrostatic Extruder

In this paper,the MB25 material forming process of hydrostatic extruder and the problem of hydrostatic extruder's center detection are studied.Firstly,the strength analysis of the extrusion cylinder,which is the key component of hydrostatic extruder,is carried out.And then the sealing structure of hydrostatic extruder is explained.Then,the magnesium alloy MB25 was selected as extrusion test material.The hydrostatic extrusion process of materials was simulated by DEFORM-2D software,and then we get pressure-displacement curve of the extrusion process.After that we analyse the pressure-displacement curve with the simulation diagram in different extrusion stages.And it has guiding significance for the research of hydrostatic extrusion pressure control.According to the material velocity nephogram based on simulation,we predict that the necking will happen at the tail of formed pipe.Then the experiments proved it,so the simulation results have reference value.The degree of influence of extrusion ratio,die cone angle,extrusion speed and billet temperature on extrusion force were studied by orthogonal test.The extrusion ratio is the first,the second is extrusion speed,the third one is billet temperature and die cone angle is the final one.The microstructures and tensile properties of MB25 magnesium alloy pipes extruted by hydrostatic extrusion are analyzed.From the analysis results,its tensile properties have been greatly improved,compared with the billet.In order to find the reason that the magnesium alloy pipes were not formed in a small extrusion ratio by the hydrostatic shrinkage extrusion,using the DEFORM-3D software to simulate the extrusion process.And then we explain the reason from equivalent stress and equivalent strain.Because the coaxiality error of extrusion cylinder end faces are too large,leading to the phenomenon of uneven wall thickness of extruded pipe.In order to solve this problem,a non-contact measuring device based on photoelectric position sensor is designed.Using this device we measured the coaxiality error of extrusion cylinder was 0.241 mm.In order to solve the nonlinear problem in PSD,we did the calibration experiments.And then design the BP neural network with calibrated experimental data as training sample,using the corrected data to calculate the coaxiality error is 0.223 mm.The content of this paper has certain guiding significance and engineering reference value for hydrostatic extrusion forming of MB25 magnesium alloy.Compared with traditional metering method,the designed coaxiality detection device for inner hole of extrusion cylinder can get rid of the requirement of precision rotary shaft and fixture,and is easy to operate...