Design And Experimental Study Of Extrusion Tap For High-Precision Internal Thread Processining Of Aluminum Alloy Thin-Walled Part

As a kind of advanced thread manufacturing technology,thread extrusion processing implements thread manufacturing with high efficiency and high precision.Thread extrusion processing can strengthen the fatigue performance of the workpiece thread,improving mechanical strength and connection performance.It is widely used in key parts thread manufacturing of equipment which work in variable load and high load conditions,such as aircraft,high railway and automotive engine.At present,the related researches at home and abroad focus on the thread extrusion processing mechanism and process optimization for high strength steel used in aviation manufacturing,but there are few research achievements in the tool design and process optimization for aluminum alloy thin-walled part thread extrusion in automotive engine manufacturing industry.This thesis aimed at the thread extrusion processing in automotive engine box parts production line,aiming to improve the thread processing quality and tool performance in the production line,and the optimum design and experimental study of high-precision internal thread extrusion processing for aluminum alloy thin-walled part were carried out.The main contents include as follow:(1)Combined with thread processing conditions in automotive engine cylinder head/valve body production line,simulation of M6 thread extrusion processing for A356 aluminum alloy was implemented using Deform-3D,and process variables such as tool load were computed.Material constitutive model and friction condition parameters of simulation model were corrected combined with thread processing experimental data,which improved the simulation accuracy.The simulation model was equivalent simplified based on differential element method for thread extrusion processing load,and equivalent computation of thread extrusion processing load was implemented by Matlab programming,which improved simulation efficiency.(2)Several groups of processing load data under different tool structure parameters conditions were obtained based on orthogonal test design and Deform simulation.Combined with response square method,multiple regression and prediction model of tool load was implemented,and the influence law of tool structure parameters on tool torque and axial force during thread extrusion were analyzed.(3)With the aim to improve tool life and decrease energy consumption in processing,optimum design of tool structure parameters was implemented using Particle Swarm Optimization algorithm.Considering precision requirements for thread machining,regression model of thread forming size was constructed based on simulation tests,and the appropriate range of bottom hole size was calculated.Considering the deformability of thin-wall structure of automotive engine parts,elastic deformation error in thread extrusion processing was analyzed,and thread precision was further controlled.(4)With aluminum alloy workpiece thread extrusion processing experiments using optimized extrusion tap implemented,tool load,power consumption in processing and formed thread accuracy data were analyzed,which validated the availability and accuracy of tool design and process optimization.