管材径压胀形特点及成形性能研究-机械制造及其自动化专业论文.docxVIP

II万方数据 II 万方数据 Abstract ABSTRACT Tube hydroforming with radial crushing is that the tube blank deforms under both internal hydraulic pressure and radial compression so that it is a new technique composing of free bulging and crushing. The process can save energy , decrease the requirements of tool and hydraulic equipments, enhance the precision of part, etc.. Therefore it is a powerful technique to deform circular tube into complex section configurations and has a great foreground. FE simulation was carried out for hydroforming with radial crushing by the FE code “DYNAFORM”. Based on the results of different loading path of movable tools, internal pressure, friction conditions, tube end conditions and material parameters, etc., the analysis for effect of these factors to the formability was performed. The results illustrate that the corner filling ability may be enhanced with the increasing of the diameter of bulging tube, internal pressure, and hardening- exponent, while decrease with the increasing of the coefficient of friction(COF) and the strength-coefficient. The formability of tube will decreases with the increasing of the diameter of the bulging tube, internal pressure, and hardening-exponent, but increase with the increasing of the COF and the strength coefficient. The asymmetry will be enhanced with the increasing of the diameter of bulging tube, internal pressure, hardening-exponent and the COF. Compared to the condition that the end of tube was restricted, tube without end restriction has better corner-filling ability and formability, The model proposed in this paper for evaluating the COF at the expansion zone in tube hydroforming is based on the special characteristics of hydrofoiming with radial crushing by making full use of its advantages. The analyzed results illustrate that the diagonals difference “ΔL” is sensitive to the friction force and varies with different COF remarkably so that it is an appropriate indicator to be measured. The COF at the