内螺纹冷挤压成形金属流动行为的研究

发布时间：2018-10-15 18:12

【摘要】：随着科学技术的快速发展,内螺纹越来越多地运用于各种先进制造生产中,特别是航空航天工业中。内螺纹传统的加工方法主要是切削加工,这种方法加工出的内螺纹切断了金属的纤维,对内螺纹的连接质量产生了一定程度上的影响。内螺纹冷挤压成形加工是一种无切屑的加工方法,其运用金属塑性流动理论为依据,相较于切削加工,其螺纹的抗拉强度和抗疲劳性能得到了较大的提升。本文运用仿真与实验相结合的研究方法,深入研究了内螺纹挤压成形过程中金属的流动行为,主要的研究内容如下:(1)介绍了内螺纹冷挤压成形的理论基础,分析了内螺纹挤压过程中金属材料的受力状态,找出了影响金属流动的主要因素。对挤压丝锥的设计方法、参数计算进行了简述。(2)建立了挤压攻丝的刚塑性有限元模型。通过对材料属性的定义,丝锥运动方式的加载,边界值问题的设置,接触关系的设定等,建立起符合工艺要求的有限元模型。(3)利用塑性成形软件DEFORM-3D对内螺纹冷挤压成形过程进行了仿真。通过点追踪的方法对牙形截面的X、Y、Z三个方向上以及牙底金属的流动行为进行分析,得出挤压前后追踪点坐标的变化以及追踪点位移、速度的变化曲线图。(4)绘制在不同的底孔直径下金属最大位移、牙形高度、牙饱满率的曲线图,分析底孔直径对它们的影响。(5)通过挤压攻丝实验,将实验结论与仿真结论进行对比分析。总结内螺纹挤压成形过程中金属的流动行为。
[Abstract]:With the rapid development of science and technology, internal thread is more and more used in various advanced manufacturing production, especially in aerospace industry. The traditional machining method of internal thread is cutting. The inner thread cut off the metal fiber, which has a certain influence on the connection quality of internal thread. Cold extrusion forming of internal thread is a kind of processing method without chip. Based on the theory of metal plastic flow, the tensile strength and fatigue resistance of internal thread are greatly improved compared with that of cutting. In this paper, the flow behavior of metal in the process of internal thread extrusion is studied by means of simulation and experiment. The main research contents are as follows: (1) the theoretical basis of cold extrusion forming of internal thread is introduced. The stress state of metal material during internal thread extrusion is analyzed and the main factors affecting metal flow are found out. The design method and parameter calculation of extrusion tap are briefly introduced. (2) the rigid-plastic finite element model of extrusion tap is established. Through the definition of material properties, the loading of taps, the setting of boundary value problems, the setting of contact relations, etc. A finite element model is established to meet the process requirements. (3) the cold extrusion process of internal thread is simulated by the plastic forming software DEFORM-3D. By means of point tracing, the flow behavior of metal in three directions of tooth section and bottom metal is analyzed, and the change of trace point coordinate and the displacement of tracing point before and after extrusion are obtained. (4) drawing the curves of metal maximum displacement, tooth height, tooth fullness rate under different bottom hole diameters, and analyzing the influence of bottom hole diameter on them. (5) through extrusion tapping experiment, The results of experiment and simulation are compared and analyzed. The flow behavior of metal during extrusion of internal thread was summarized.
【学位授予单位】：陕西理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG62

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