多截面异型管件的塑性成形方法研究

发布时间：2018-03-08 13:32

本文选题：管材　切入点：塑性成形　出处：《吉林大学》2017年硕士论文　论文类型：学位论文

【摘要】：零件的节材节能、高精度、高效率化生产是塑性成形的主要发展方向之一,其中空心件代替实心件是一种有效的节材节能化生产方式,因此管件塑性成形方法的研究越来越受关注。多截面异型管件广泛应用于现代化工业生产,管材塑性成形具有轻量化、近净成形的优点,但该方面文献研究相对较少。本文以载重车整体驱动桥壳的轴头为例来研究多截面异型管件的塑性成形方法,该种桥壳常采用方、矩形管来成形,如何将方、矩形管的端部变为圆截面是整体驱动桥壳成形重点需要解决的问题之一。因此本文主要研究了方、矩形管变圆管的轴头制坯以及轴头成形工艺,并取得了如下成果:方管变圆管采用两道次辊锻和一次整形辊锻。基于空心件辊锻过程中常出现管壁增厚、壁厚不均匀现象,在辊锻成形过程中添加芯模,改善辊锻件的成形质量。由于空心件辊锻理论的空白,本文在借鉴实心件辊锻理论的基础上再结合DEFORM模拟软件设计辊锻模以及芯模,对比分析有无芯模的成形过程、温度场、管壁厚度、等效应变、载荷分布情况,得出有芯模成形可以使圆管的壁厚均匀化、提高成形精度,减少材料消耗,降低生产成本,提高辊锻的稳定性,有利于汽车轻量化生产,而且对空心件辊锻工艺的研究具有一定的参考价值。根据圆管直径介于矩形管长边与短边之间的特点,矩形管变圆管采用两次带芯模温挤压成形即一次外缩内扩,一次外缩。通过分析凹模内径和摩擦系数对成形效果的影响,模拟研究凹模内径、摩擦系数、挤压速度、工作带长度对两次挤压过程中最大挤压力的影响规律,得出成形效果好且最大挤压力较小的参数,为管材挤压模拟参数的选择提供了重要参考价值。分析了挤压过程中金属流动速度、温度场、等效应变、行程-载荷的分布规律,这对管材生产中缺陷产生的位置的预测、模具设计合理性的判断以及设备吨位的选择有重要意义。根据轴头的结构特征及坯料形状,提出4种轴头挤压方案,分析各个方案的优缺点,确定轴头温-冷复合挤压工艺即温挤压、冷整形。以管材缩径为研究对象,探讨了温度以及摩擦系数对管坯壁厚增量、端部翘曲、载荷的影响。分析轴头成形过程中材料堆积、飞边、折叠,挤压件与凹模定径区间隙、充不满,固定端镦粗,这些常见缺陷产生的原因并提出优化方案。该工艺将温挤压与冷挤压的优点结合在了一起,它既满足了轴头的厚度尺寸,也提高了轴头的成形精度,节约了材料,减少了加工工序,为轴头的生产提供了一种新的思路。
[Abstract]:The energy-saving, high-precision and high-efficiency production of parts is one of the main development directions of plastic forming, in which hollow parts replace solid parts is an effective energy saving production mode. Therefore, more and more attention has been paid to the study of plastic forming methods of pipe fittings. Multi-section special-shaped pipe fittings are widely used in modern industrial production. Plastic forming of pipes has the advantages of light weight and near net forming. But there is relatively little research on this aspect. This paper studies the plastic forming method of multi-section special-shaped pipe by taking the axle head of the integral drive axle housing of the truck as an example. The bridge shell is usually shaped by square and rectangular tubes. Turning the end of rectangular tube into round section is one of the key problems to be solved in the forming of integral drive axle housing. The results are as follows: the square tube adopts two pass roll forging and one shaping roll forging. Based on the phenomenon of tube wall thickening and uneven wall thickness, the core die is added in the process of roll forging, because the tube wall is thickened and the wall thickness is uneven in the process of hollow parts roll forging. To improve the forming quality of roll forgings. Due to the blank of the theory of roll forging for hollow parts, this paper, based on the theory of solid part roll forging, and combining with DEFORM simulation software, designs roll forging die and core die, and analyzes the forming process and temperature field of the die with or without core. The thickness, equivalent strain and load distribution of the tube wall are obtained. It is concluded that the core-die forming can make the wall thickness of the circular pipe even, improve the forming accuracy, reduce the material consumption, reduce the production cost, improve the stability of roll forging, and benefit the light weight production of the automobile. According to the characteristic that the diameter of the circular tube is between the long and short sides of the rectangular tube, the variable circular tube of the rectangular tube is formed by two times of warm extrusion with the die with core, that is, the expansion of the inner part of the tube is the first time, and it has a certain reference value for the research of the roll forging technology of the hollow part. By analyzing the influence of die inner diameter and friction coefficient on forming effect, the influence of die inner diameter, friction coefficient, extrusion speed and working belt length on the maximum extrusion force during twice extrusion is simulated. The parameters with good forming effect and low maximum extrusion pressure are obtained, which provide an important reference value for the selection of parameters for tube extrusion simulation. The distribution of metal flow velocity, temperature field, equivalent strain, stroke and load during extrusion is analyzed. It is of great significance to predict the position of defects in pipe production, to judge the rationality of die design and to select the tonnage of equipment. According to the structural characteristics of shaft head and the shape of blank, four kinds of extrusion schemes for shaft head are put forward. The advantages and disadvantages of each scheme are analyzed, and the temperature extrusion and cold shaping of shaft head are determined. Taking pipe shrinkage as the research object, the effect of temperature and friction coefficient on the increment of wall thickness and end warping of tube billet is discussed. Influence of load. Analysis of material accumulation, flange, folding, clearance between extruder and die, filling, fixed end upsetting, The process combines the advantages of warm extrusion and cold extrusion. It not only satisfies the thickness of shaft head, but also improves the forming accuracy of shaft head and saves material. The processing procedure is reduced and a new way of thinking is provided for the production of shaft head.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG306

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