高强钢汽车传动轴管辊弯成型过程管坯变形行为及辊形设计方法研究

发布时间：2018-08-02 12:37

【摘要】：汽车传动轴管是传动系统的重要零部件,大型商用汽车的传动轴管一般采用屈服强度为480MPa的普通钢材制造,为满足力学性能要求,传动轴管壁厚较大,影响汽车轻量化。采用高强钢代替普通钢材制造轴管具有力学性能好、节能减排、节材效果明显等优点,高强钢传动轴管一般采用辊弯成型、高频焊接等工艺制造,其中辊弯成型是最基本和重要的成型工艺,对后续焊接质量也具有重要影响。因此,研究高强钢汽车传动轴管辊弯成型技术具有重要的理论意义和应用价值。辊弯成型过程中板坯变形复杂,涉及材料非线性、几何非线性、接触非线性等问题。高强钢具有材料强度高、回弹大、塑性较差、焊接难等特点,其成型难度较普通钢大。影响高强钢辊弯成型的因素很多,包括辊形设计、工艺参数等,其中辊形设计与管坯变形过程密切相关,对管坯成型质量具有重要影响。因此,研究高强钢辊弯成型中辊形设计方法和管坯变形规律,揭示高强钢成型中辊形与成型质量之间的关系,对于控制管坯回弹变形、管坯边缘状态、管坯成型质量和后续焊接效果具有十分重要的意义。本文主要研究了高强钢轴管辊弯成型中的辊形设计、管坯整体变形行为及边缘成型规律。以Φ120×4mm传动轴管为研究对象,材料为700QZ高强钢,基于ABAQUS模拟软件,研究了适合高强钢轴管辊弯成型的建模方法,通过采用合理的轧辊简化手段和成型过程参数设置,建立了辊弯成型过程有限元数值模拟模型,并通过实验对板坯截面形状、开口度和纵向深度进行了对比和验证。以Φ134×4mm高强钢轴管为研究对象,采用普通双半径法对辊弯成型中的轧辊进行了辊形设计,揭示了成型中的板坯变形规律、应力应变分布特点及成型中存在的应力应变过大和板坯干涉等问题,分析并提出了第一次辊形优化设计方案,改进了辊缝、立辊和闭口辊的设计;针对第一次优化方法不能解决成型中存在的立辊组应力集中、变形分配不合理问题,在第二次优化方法中研究了 W辊形设计并应用于高强钢轴管成型,建立了双W辊与双半径辊组合成型系统,改善了成型过程中变形分配和立辊组应力集中问题。针对高强钢成型困难和普通双半径成型中应力应变分布不均、立辊组应力集中等问题,本文提出了一种三半径辊形设计新方法,以Φ134×4mm高强钢轴管为例,对成型轧辊进行了详细的辊型设计,系统分析了成型中应力应变大小及分布的均匀性、板坯截面厚度变化规律、立辊组应力分布,并与普通双半径法的成型结果进行了对比,研究表明,三半径成型法在实现高强钢板坯变形均匀和改善立辊组应力集中等方面具有明显优势。研究了单道次W、双道次W在三半径成型法中的应用,系统分析了双W组合辊对应力应变分布及立辊组区域应力状态的影响,为高强钢传动轴管辊形设计提供了新的思路。针对立辊组应力集中问题,分析了普通双半径、双W双半径、三半径成型法在立辊组成型道次中的变形量,揭示了板坯变形分配与区域应力集中间的关系。研究了辊弯成型过程中实现边缘平行对接和边缘变形控制的基本方法,分析和对比了边缘变形辊和W成型辊对板坯边缘受力状态的影响,研究了双W组合辊中实体板坯内外壁的应变分布,提出了衡量板坯内外壁变形的相对变形量概念,并对不同成型辊下的内外壁相对变形量进行了对比,总结了不同初始成型辊对边缘平行对接的影响;分析了单半径和双半径立辊对板坯的接触和受力状态,针对双半径和三半径立辊设计提出了避免应力集中和回弹控制的设计方法;分析了普通单半径闭口辊对边缘控制的不足,提出了考虑板坯伸长、实现边缘控制的双半径闭口辊形设计方法,为辊弯成型中边缘控制提供了参考思路。
[Abstract]:The drive shaft tube is an important part of the transmission system. The shaft tube of a large commercial vehicle is usually made of ordinary steel with a yield strength of 480MPa. In order to meet the mechanical performance requirements, the wall thickness of the drive shaft is larger and affects the light weight of the automobile. The mechanical properties of the shaft tube made of high strength steel instead of ordinary steel are good in mechanical properties, energy saving and emission reduction. The high strength steel transmission shaft tube is usually made of roll bending and high frequency welding, in which roll bending is the most basic and important molding process, and it has important influence on the quality of subsequent welding. Therefore, it has important theoretical significance and application value to study the bending forming technology of high strength steel automobile shaft tube roll. In the process of roll bending, the slab deformation is complicated, involving nonlinear material, geometric nonlinearity and contact nonlinearity. High strength steel has the characteristics of high material strength, large resilience, poor plasticity, and difficult welding. Its forming difficulty is larger than that of ordinary steel. There are many factors affecting roll shape of high strength steel, including roll shape design, process parameters and so on, among which roll shape The design is closely related to the deformation process of the tube billet, which has an important influence on the quality of the tube billet. Therefore, the design method of the roll shape and the deformation law of the tube blank in the bending of high strength steel are studied. The relationship between the roll shape and the forming quality in the molding of high strength steel is revealed, and the shape of the springback, the edge state of the tube billet, the quality of the tube billet and the subsequent welding are controlled. This paper mainly studies the roll shape design, the whole deformation behavior and the edge forming rule of the high strength steel shaft tube roll forming. The research object is that the shaft pipe of 120 x 4mm is used as the research object, and the material is 700QZ high strength steel. Based on the ABAQUS simulation software, the modeling method suitable for the bending forming of high strength steel shaft tube is studied. The finite element numerical simulation model of roll forming process is established by using reasonable roll simplification and forming process parameters. Through experiments, the section shape, opening and longitudinal depth of the slab are compared and verified. The axial tube of 134 x 4mm high strength steel is used as the study of the image, and the common double radius method is used in the roll bending forming. The roll shape design is carried out. The deformation law of the slab, the distribution characteristic of stress and strain, the excessive stress and strain in the forming and the interference of the slab are revealed. The first roll shape optimization design scheme is analyzed and proposed, and the design of the roll gap, the vertical roll and the closed roll are improved. The first optimization method can not solve the molding. In the second time optimization method, the W roll shape is designed and applied to the high strength steel shaft tube forming. The combined forming system of double W roll and double radius roller is established, which improves the deformation distribution and the stress concentration in the vertical roll group in the forming process. In this paper, a new method of three radius roll shape design is put forward in this paper. In this paper, a new method of three radius roll shape design is put forward. With the example of the shaft pipe of 134 x 4mm high strength steel, the roll shape is designed in detail. The size of stress and strain, the uniformity of the distribution and the thickness variation of the slab section are systematically analyzed. Law, the stress distribution of the vertical roll group is compared with the forming results of the common double radius method. The study shows that the three radius forming method has obvious advantages in realizing the uniform deformation of the high strength steel plate and improving the stress concentration of the vertical roll group. The application of single pass W and double pass W in the three half diameter forming method are studied, and the double W combination roll is systematically analyzed. The influence of the stress and strain distribution and the stress state of the vertical roll group provides a new idea for the design of the roll shape of the high strength steel transmission shaft. According to the stress concentration problem of the vertical roll group, the deformation of the common double radius, the double W double radius and the three radius forming method in the vertical roll form is analyzed, and the deformation distribution of the slab and the stress concentration in the region are revealed. The relationship between the edge deformation and the edge deformation control in the roll forming process is studied. The influence of the edge deformation roll and the W forming roller on the stress state of the edge of the slab is analyzed and compared. The strain distribution in the outer wall of the solid slab in the double W composite roll is studied, and the relative variation of the inner and outer wall deformation of the slab is proposed. The relative deformation of the inner and outer walls under different forming rollers was compared, and the influence of different initial forming rollers on the parallel butt of the edge was summarized. The contact and force state of the single radius and double radius vertical rollers on the slab were analyzed. The setting of the double radius and three radius vertical rollers was put forward to avoid the stress concentration and the Springback Control. By analyzing the shortcomings of the edge control of the ordinary single radius closed roll, the design method of double radius closed roll shape design considering the length of the slab and realizing the edge control is put forward, which provides a reference for the edge control in the roll bending.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG30;U463.2

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