The Forming Mechanism Of The Barrel Barrel And The Optimization Design Of Process Parameters

Radial precision forging technology when the rifling and chamber are productes at the same time is a key technology for the manufacture of barrel.But at present,this technology is still lack of theoretical guidance,so that there are various defects in the inner barrel,especially the cones at the barrel chamber are difficult to fill by blank,the chamber is not easy to form,and the pnetration efficiency is poor.In this paper,the forming process of barrel chamber during simultaneous forging is taken as the research object.The material flow process and the forging penetration efficiency in the process of are studied by means of geometric analysis and finite element analysis.The process of blank filling the cavity between mandrel and hammer is analyzed by geometric analysis,The cavity thickness at different cones is calculated,and the relative reduction,total forging ratio and forging section forging ratio of each section of the chamber are calculated.Geometric analysis under various technological conditions was integrated into the barrel precision forging aided design software,and the software was supplemented and improved to facilitate the replacement and selection of technological parameters.According to the relative reduction,the geometric condition when the blank can touch every cone of the chamber is obtained,and the reasonable range of the parameters such as the position of lifting hammer and the position of lowering pressure is determined preliminarily.The finite element model of the precise forging process of the chamber is established,and the material flow of the barrel during the forming process is analyzed.According to the strain variation at the key points of the cone of the chamber,the penetration efficiency based on the reduced value of strain is proposed.Through the finite element analysis of material fluidity,it can be seen that the degree of forming difficulty is different at each cone of chamber.Taking the data of the end point of the second cone which is the most difficult to form as the the standard of penetration of chamber forging,the radial strain reduction of the barrel material at this point after touching the mandrel reaches a certain threshold value,which can be used as the threshold value to judge the penetration efficiency of the chamber forming.According to the comparison and analysis with the actual forging test,the threshold value is 8%.Combining finite element analysis with geometric analysis,when the strain reduction at the second cone reaches the threshold value(8%),the forging ratio of the forging section can be calculated to be 23%.The forging penetration criterion derived from theoretical analysis is applied to the forging process of a certain caliber rifle and machine gun barrel.After analyzing the influence of lifting hammer position and the size of workpiece on the penetration efficiency of the chamber forming,the reasonable parameters of chamber forming in the forging process of a certain caliber rifle and machine gun are found out.The processing verification is carried out in the experiment,and the qualified inner chamber barrel is forged.The results show that the forging penetration efficiency criteria derived from theoretical analysis are reasonable and applicable.Through geometric analysis,finite element analysis and comparison and verification with experiments,the forming conditions of chamber forging during the simultaneous forging are obtained,which has theoretical guiding significance for the formulation of technological parameters for the the chamber of the chamber-rifle integral radial forging of gun barrel and the matching design of the hammer and mandrel.