颗粒增强钛基复合材料缓进深切磨削研究

发布时间：2018-06-08 07:20

  本文选题：颗粒增强钛基复合材料 + 缓进深切磨削　； 参考：《南京航空航天大学》2017年硕士论文

【摘要】：颗粒增强钛基复合材料因具有高的比强度、比刚度以及优异的高温性能和耐蚀性能,在航空航天领域具有广阔应用前景。但是,由于该类材料中同时存在高强韧钛合金基体和高硬脆增强颗粒这两种力学性质相差显著的材料,使其成为了典型的难加工材料。采用普通切削和磨削加工存在加工效率低、工具寿命短、加工成本高、表面质量差以及工件易烧伤等问题,严重制约了颗粒增强钛基复合材料的加工质量与效率,并阻碍了该材料的应用进程。有鉴于此,本课题提出开展颗粒增强钛基复合材料缓进深切磨削研究,通过三种刚玉砂轮缓进深切磨削钛基复合材料的对比试验研究,从磨削力与砂轮磨损、磨削温度与热量分配、加工表面完整性三个方面研究颗粒增强钛基复材的磨削问题。研究成果对于实现颗粒增强钛基复合材料高效精密加工具有重要理论意义和应用价值。论文完成的主要研究工作及取得的成果如下:(1)揭示了刚玉砂轮缓进深切磨削颗粒增强钛基复合材料磨削力与砂轮磨损的变化规律。磨削用量和砂轮种类对磨削力具有显著影响,磨削力随砂轮线速度增加而下降、随工件进给速度与切深增大而上升。微晶刚玉砂轮的磨削力明显小于白刚玉与铬刚玉砂轮,这表明微晶陶瓷刚玉砂轮最锋利。微晶刚玉砂轮缓进深切磨削颗粒增强钛基复合材料过程中,砂轮磨损主要以粘附为主,并且随着切深的增大,粘附面积逐渐增加。(2)研究了缓进深切磨削颗粒增强钛基复合材料的磨削温度与热量分配比例。磨削温度随砂轮线速度和切深增大而升高,随工件进给速度增大而减小。同等条件下,微晶刚玉砂轮的磨削温度低于其它砂轮。缓进深切磨削过程中,磨削弧区冷却液存在泡核沸腾和膜沸腾两个阶段。当切深小于0.6mm时,磨削弧区冷却液处于泡核阶段,冷却作用显著,磨削温度变化比较平缓并且最高温度小于130℃。然而,当切深大于0.8mm时,磨削热量易使磨削弧区冷却液从泡核阶段转变为膜沸腾阶段,磨削温度升高至700℃以上,工件发生烧伤。泡核沸腾和膜沸腾阶段,磨削热量进入工件的比例分别为20~30%和70~85%。(3)探明了缓进深切磨削颗粒增强钛基复合材料的加工表面完整性。缓进深切磨削表面形貌主要包括塑性切削方式去除钛合金基材产生的涂覆、沟槽与裂纹,以及增强颗粒以拔出、破碎、压入等方式去除产生的孔洞。同时,阐明了磨削用量对加工表层显微硬度、金相组织以及残余应力的影响规律。由此,提出了优化的缓进深切磨削工艺参数范围。
[Abstract]:Because of its high specific strength, specific stiffness, excellent high temperature performance and corrosion resistance, particle reinforced titanium matrix composites have a wide application prospect in the field of aeronautics and astronautics. However, due to the existence of both high strength and tough titanium alloy matrix and high hard brittle reinforced particles, these two materials have different mechanical properties, which make them become typical refractory materials. The problems of low machining efficiency, short tool life, high machining cost, poor surface quality and easy burn of workpiece have seriously restricted the machining quality and efficiency of particle reinforced titanium matrix composites. It also hinders the application of the material. In view of this, this paper puts forward to carry out the research of progressive deep grinding of particle reinforced titanium matrix composites. Through the comparative experimental study of three kinds of corundum grinding wheels, the grinding force and grinding wheel wear are studied. Grinding temperature and heat distribution and surface integrity are studied in this paper. The research results have important theoretical significance and application value for realizing high efficiency precision machining of particle reinforced titanium matrix composites. The main research work and results obtained in this paper are as follows: 1) the variation of grinding force and wheel wear of grain reinforced titanium matrix composites by corundum grinding wheel is revealed. The grinding force decreases with the increase of the linear speed of the grinding wheel and increases with the increase of the feed speed and the cutting depth of the workpiece. The grinding force of microcrystalline corundum grinding wheel is obviously less than that of white corundum and chrome corundum grinding wheel, which indicates that the microcrystalline ceramic corundum grinding wheel is the sharpest. In the process of microcrystalline corundum wheel slowly advancing deep grinding particle reinforced titanium matrix composites, the wear of grinding wheel is mainly adhesion, and with the increase of cutting depth, The ratio of grinding temperature to heat distribution of grain reinforced titanium matrix composites with slowly advancing deep grinding was studied. The grinding temperature increases with the increase of grinding wheel linear velocity and cutting depth, and decreases with the increase of workpiece feed speed. Under the same conditions, the grinding temperature of microcrystalline corundum grinding wheel is lower than that of other grinding wheels. There are two stages of bubble nucleation boiling and film boiling in the coolant in the arc zone of the grinding process. When the cutting depth is less than 0.6mm, the coolant in the grinding arc zone is in the stage of bubble nucleus, the cooling effect is obvious, the grinding temperature changes slowly and the maximum temperature is less than 130 鈩，

本文编号：1995092