薄壁管材高速滚珠旋压拟动力学模型及工艺参数选取研究

发布时间：2018-04-20 02:22

本文选题：滚珠旋压 + 拟动力学　；参考：《太原科技大学》2017年硕士论文

【摘要】：高速滚珠旋压是一种采用滚珠作为变形工具的强力旋压加工工艺,综合了锻造、挤压、拉伸、弯曲、环轧、横轧和滚压等工艺的优点。由于作为变形工具的滚珠具有很好的表面粗糙度和尺寸精度,使得其加工产品能够达到很高的精度。同时,旋压过程中坯料的变形方式为局部逐点成型,具有其变形区域小,变形应力高的特点,通常用来加工一些,高硬度,塑性指标差的金属材料。本文对高速滚珠旋压过程中的力学、运动学特性及工艺参数配置等进行了研究,主要研究内容和结果如下:1)以高速滚珠为研究对象,在大量实验基础上提出旋压过程中滚珠的运动假设,通过对滚珠进行运动学与力学分析,考虑滚珠所受离心力与陀螺力矩建立了滚珠旋压的拟动力学模型。基于VC++平台编程求解此拟动力学模型,求解了不同工况下,滚珠的运动参数,及三点接触滚珠在的各接触点的力学参数。由于高速回转体其参数不易测试,本文利用ABQUS软件对旋压过程进行了动力学仿真,提取计算结果与理论计算结果对比,并间接的进行了实验验证。完善了高速滚珠旋压分析理论,为滚珠旋压的生产工艺提供了理论支撑。为进一步研究旋压过程中滚珠变形、模具变形所导致的管材精度偏差及其控制、摩擦生热控制等提供了理论基础。2)以管坯为研究对象,基于大量仿真实验结果,探讨了减薄量、进给比、滚珠直径三个主要工艺参数及其相互之间的耦合作用对管坯变形影响区内平均应力三轴度的影响;并对这四者之间的关系进行了多元非线性函数关系拟合,从而计算出最小应力三轴度对应的最优工艺参数。不同工艺参数配置下的镁合金薄壁管室温滚珠旋压实验结果表明:采用本文给出的最优工艺参数,可以使旋压后的管件表面开裂现象得到明显改善,镁合金管坯的滚珠旋压塑性成型性能得到了提高。研究结果极大的方便了旋压生产过程中的工艺参数选取。3)给出了一种应用滚珠旋压在钢管内壁加工环状沟槽的工艺方法。基于空间解析理论和径向螺旋进给的假设,给出了滚珠和工件之间径向和切向接触面积边界曲线的简化表达式,通过曲线积分,得出了用于计算旋压力的径向和切向接触面积的计算模型。通过算例得出的数据,研究了旋压深度、滚珠直径、旋压进给量和旋压力的关系,由本文给出的解析模型得到的计算数据和有限元模拟所得数据的比较,证明了本文所得出的解析模型具有可行性。4)以目前的立式低速旋压机床为参考,设计以高速电主轴驱动的高速滚珠旋压实验机,并给出高速旋压时管坯偏心径向受力不均导致振动的解决方案。以及在高速与重载之间切换拓展实验机旋压能力的实现方法。
[Abstract]:High speed ball spinning is a kind of strong spinning process which adopts ball as a deformation tool. It integrates the advantages of forging, extrusion, stretching, bending, ring rolling, cross rolling and rolling. Due to the good surface roughness and dimensional accuracy of the ball as a deformation tool, the product can achieve high precision. At the same time, the deformation mode of billet in spinning process is local point-by-point forming, which has the characteristics of small deformation area and high deformation stress. It is usually used to process some metal materials with high hardness and poor plasticity index. In this paper, the mechanical, kinematic and technological parameters of high speed ball spinning are studied. The main contents and results are as follows: 1) High speed ball is taken as the object of study. On the basis of a large number of experiments, the motion hypothesis of the ball during spinning is put forward. By analyzing the kinematics and mechanics of the ball, the quasi-dynamic model of the ball spinning is established considering the centrifugal force and the gyroscopic moment of the ball. Based on VC platform, the kinematic parameters of ball and the mechanical parameters of three point contact ball at various contact points are solved by programming the pseudo-dynamic model. Because the parameters of high-speed rotary body are not easy to test, the dynamic simulation of spinning process is carried out by using ABQUS software. The results of extraction and calculation are compared with those of theoretical calculation, and the experimental results are indirectly verified. The theory of high-speed ball spinning analysis is perfected, which provides theoretical support for the production process of ball spinning. In order to further study the tube precision deviation and its control caused by ball deformation and die deformation during spinning, and the control of friction heat generation, etc., this paper provides a theoretical basis for the study of tube billet. Based on a large number of simulation results, the thinning amount is discussed. The effect of feed ratio, ball diameter and their coupling on the average stress triaxiality in the zone affected by tube billet deformation is studied, and the multivariate nonlinear function is used to fit the relationship between the four parameters. The optimum process parameters corresponding to the minimum stress triaxiality are calculated. The experimental results of room temperature ball spinning of magnesium alloy thin-walled tubes with different processing parameters show that the surface cracking of tube fittings after spinning can be improved obviously by using the optimum process parameters given in this paper. The spinning plastic forming property of magnesium alloy tube billet was improved. The research results greatly facilitate the selection of process parameters in spinning process. 3) A new method for machining annular grooves with ball spinning on the inner wall of steel pipe is presented. Based on the spatial analytic theory and the assumption of radial spiral feed, a simplified expression of radial and tangential contact area boundary curve between ball and workpiece is given. A model for calculating radial and tangential contact area of rotary pressure is obtained. The relationship among spinning depth, ball diameter, feed rate and pressure is studied by the example. The comparison between the calculated data obtained from the analytical model presented in this paper and the data obtained by finite element simulation is made. It is proved that the analytical model obtained in this paper is feasible. (4) based on the present vertical low speed spinning machine, a high speed ball spinning experiment machine driven by high speed motorized spindle is designed. The solution of vibration caused by eccentric radial force of tube billet under high speed spinning is given. And the realization of switching between high speed and heavy load to expand the spinning capacity of the experimental machine.
【学位授予单位】：太原科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG306

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