压铸AM50镁合金汽车座椅骨架的设计及组织和性能研究

发布时间：2018-04-04 17:49

本文选题：AM50镁合金　切入点：座椅骨架　出处：《长春工业大学》2017年硕士论文

【摘要】：座椅骨架目前主要由钢板冲压焊接而成,随着整车对座椅轻量化要求的日益提高,热塑性塑料成型骨架、镁合金骨架以及碳纤维增强复合材料骨架成为现阶段座椅骨架用材料的重要开发方向。热塑性塑料成型骨架成本低,但机械性能和回收性能差;碳纤维增强复合材料骨架的机械性能优异,但价格昂贵且无法回收;镁合金骨架的成本居中,具有良好的机械性能,可回收利用,依托铸造工艺可实现复杂结构的集成化,成为座椅骨架用材料的新方向。本文从轻量化和工艺可行性的角度出发,将国产某型乘用车前排座椅的原钢板冲压焊接结构采用AM50镁合金集成铸件取代。首先,确定了采用高压铸造工艺一次成型该座椅骨架铸件,实现复杂造型,在保证座椅骨架原有强度和硬度的条件下实现座椅的减重;其次,根据汽车正常行驶和碰撞时座椅的受力情况以及座椅骨架设计方案的结构评估结果,在座椅骨架不同部位取样,对本体试样进行显微组织的观察与分析、晶粒尺寸的测量、力学性能测试和断口分析,以观察不同区域的显微组织和力学性能的差异化,并对差异化产生的原因进行分析与讨论;第三,依据上述分析结果对AM50镁合金汽车座椅骨架的结构进行再设计、模具的设计及工艺的设计与优化,从而制造出符合要求的镁合金汽车座椅骨架,为轻量化镁合金座椅骨架铸件提供结构设计及工艺优化的开发依据。本文主要研究结果如下:(1)将座椅骨架的结构设计、模拟和工艺开发紧密结合,实现了替代钢板冲焊部件的整体集成AM50镁合金座椅骨架的结构优化和集成设计;(2)汽车座椅骨架选用AM50镁合金,采用高压铸造工艺一次成型,减少了零件数量,提升了整体精度,工艺上减少了装配过程,不需要焊接,消除了焊缝撕裂的风险,节约时间,铸件拥有更多的自由度,可实现复杂的造型及减轻座椅骨架的重量,最终所得座椅骨架各个部分铸件的质量为:坐盆的质量为922g,左右两个侧板的质量分别为423g和407g,靠背的质量为1476g,总体减重达到49.6%;(3)根据汽车正常行驶和碰撞过程中座椅骨架实际受力情况,并结合座椅骨架设计方案的结构评估结果以及铸件的实际铸造工艺和性能分析结果,在座椅骨架不同部位取样,利用光学显微镜、扫描电镜(SEM)等对座椅骨架不同部位进行显微组织分析,用Image Pro Plus软件对压铸成形后不同部位AM50镁合金的晶粒尺寸等进行研究,并对不同部位的力学性能进行检测与分析,发现座椅骨架不同区域的显微组织和力学性能存在差异,分析认为此差异化的产生,一方面是由于座椅铸件结构复杂、壁厚不均,镁合金液在铸件各区域凝固时的冷却速度不同,各区域的晶粒尺寸存在差异导致;另一方面,高压铸造时,熔融镁合金液在型腔不同部位的充型顺序存在差异,使得镁合金液的凝固顺序存在差异,导致座椅各区域组织和性能存在差异。本论文的研究结果表明,利用高压铸造工艺生产镁合金座椅骨架时,必须与铸件的受力分析相结合,进行座椅压铸模具的优化设计,保证产品的性能满足要求。
[Abstract]:The seat frame is mainly composed of steel plate stamping and welding, with the increasing demand for lightweight vehicle seat, thermoplastic plastic molding skeleton, the framework of magnesium alloy and carbon fiber reinforced composite material skeleton has become the seat frame with an important development direction of the material. The thermoplastic moulding skeleton of low cost, but the mechanical properties and the recovery of poor performance; carbon fiber reinforced composite materials reinforced with excellent mechanical properties, but the price is expensive and can not be recovered; magnesium alloy skeleton cost center, has good mechanical properties, Recyclable use, relying on the casting process can realize the integration of complex structure, a seat frame with new material. In this paper, lightweight and process the perspective of feasibility, the welding of a certain type of domestic passenger car seat in the front row of the original stamping steel structure using AM50 magnesium alloy casting integrated replaced. First of all, the high Pressure casting molding of the seat frame castings, complex shape, so as to ensure that the strength and hardness of the original seat seat frame under the condition of weight loss; secondly, according to the normal running of the vehicle and the collision force and the structure of the seat seat frame design scheme evaluation results in sampling in different parts of the seat frame, were observed. With the analysis of the microstructure of the bulk sample grain size measurement, mechanical test and fracture analysis, to observe the differences of microstructure and mechanical properties of different regions, and the differences of the reasons were analyzed and discussed; third, according to the analysis results of structure of AM50 magnesium alloy automobile seat frame again design, design and optimization of mold design and process, so as to meet the requirements of manufacturing magnesium alloy automobile seat frame, lightweight magnesium alloy seat frame castings Provide the design and optimization of structure development basis. The main results of this paper are as follows: (1) the seat frame structure design, combining simulation and process development, realize the structure optimization of steel plate punching welding parts replacement integrated AM50 magnesium alloy seat frame and integrated design; (2) automobile seat frame with AM50 magnesium alloy, forming a high pressure casting process, reduce the number of spare parts, improve the overall accuracy, process reduces the assembly process, without welding, eliminating the risk of weld tear can save time, casting has more degrees of freedom, can realize complex shape and reduce the weight of the seat frame, the quality of the final seat the various parts of the casting framework as: the quality of bidet is 922g, the quality of about two side plates are respectively 423g and 407g, a mass of 1476g, the overall weight reached 49.6%; (3) according to the normal line Driving and collision process of the seat frame actual stress, combined with the evaluation results of the seat frame structure design and casting the actual casting process and performance analysis results in different parts of the seat frame, sampling, using optical microscopy, scanning electron microscopy (SEM) microstructure analysis of different parts of the seat chair frame, with Image Pro Plus the software of die casting AM50 magnesium alloy after different parts of the grain size, and the detection and analysis of mechanical properties of different parts of the seat frame, found that the microstructure of different regions and differences in performance analysis that this difference is due to the production, a seat casting complex structure, wall thickness both, the cooling speed of magnesium alloy castings during solidification of liquid in each region is different, the grain size of the regional differences result; on the other hand, high pressure casting, molten magnesium alloy The filling sequence of liquid gold in different parts of the cavity are different, the solidification sequence of liquid magnesium alloy are different, leading to the existence and performance of the seat area organization difference. The results show that the production of magnesium alloy seat frame by using high pressure casting process, must be combined with the stress analysis of castings, optimization design seat of die-casting mould, ensure product performance meet the requirements.

【学位授予单位】：长春工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U463.836;TG249.2

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