超声振动辅助铣削钛合金工艺实验研究

发布时间：2018-01-10 00:05

本文关键词：超声振动辅助铣削钛合金工艺实验研究　出处：《南京理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着航空航天工业的迅速发展,对钛合金材料的需求日益提高,传统的切削工艺已经难以实现钛合金高效高质加工。超声振动辅助加工是将超声波信号引入到普通加工中,通过将电信号转化为机械振动再传递给工件或刀具,使其实现断续切削的加工效果,从而减小加工过程中的切削力、切削温度,改善加工效率,提高加工质量。目前该技术在陶瓷等硬脆材料的加工中体现出独特优势,但在钛合金的铣削加工中应用较少。因此,本文以TC4钛合金为对象,开展了超声振动辅助铣削实验。分析了超声振动辅助作用和工艺参数对刀具磨损、铣削力以及表面完整性的影响规律。首先,设计了超声振动辅助铣削钛合金的刀具磨损实验,分析了铣削加工过程中刀具的磨损机理。通过对不同铣削时间下普通铣削和超声振动辅助铣削的刀具磨损形貌进行观察和分析,发现超声振动的辅助作用对加工过程中产生的刀具磨损有明显的改善效果,并且能够延长刀具使用寿命。同时对比了两种加工方式下的钛合金切屑形貌,发现超声振动辅助铣削下的切屑微小细碎且呈均匀弧状形态。其次,在不同的铣削参数下开展了超声振动辅助铣削钛合金的铣削力实验,分析随着铣削参数的变化,超声振动作用对铣削力的影响规律。实验结果表明,超声振动的辅助作用可降低钛合金铣削过程中的最大铣削力和平均铣削力,并且在一定范围内,超声电流越大,铣削力越小。两种加工方式下的铣削力都随主轴转速的增加而减小;随着进给速度及切削深度的增加而增大,但超声振动的辅助使得铣削力增幅较为缓慢。此外,在实验基础上建立了超声振动辅助铣削钛合金的铣削力指数预测模型,并对钛合金铣削加工参数进行了优化。结果表明,所建的指数模型预测精度以及稳定性均相对较高;优化后的铣削力明显减小,优化效果显著。最后,通过非接触式3D形貌仪测量了不同加工参数下钛合金的表面三维粗糙度。结果表明高频的振动冲击作用使得钛合金加工表面更加细微且均匀,主轴转速的增加有利于降低表面粗糙度,而切削深度对表面粗糙度影响较小。利用体视显微镜对两种加工方式在不同铣削深度下的棱边质量进行了分析。发现超声振动辅助铣削加工后的棱边质量与普通铣削相比明显有所改善,不仅毛刺的尺寸较小而且密集程度也远低于普通铣削;另外,随着铣削深度的增大两种加工方式下的边缘毛刺均有一定程度的增加。利用X射线衍射仪测量了不同超声电流下的钛合金表面残余应力。结果表明,超声振动辅助铣削表面形成的为残余压应力,高频的振动冲击有利于提升加工表面的残余压应力,并随着超声电流的增大呈现递增趋势。
[Abstract]:With the rapid development of the aerospace industry, the titanium alloy material of increasing demand, the traditional cutting process of titanium alloy has been difficult to achieve high quality processing. Ultrasonic vibration assisted machining is introduced into the ordinary ultrasonic signal processing, through the electrical signal into mechanical vibration transmitted to the workpiece or tool in the effect of intermittent cutting processing, and cutting force, in the process of reducing the cutting temperature, improve processing efficiency, improve the quality of processing. The technology in the processing of hard brittle materials such as ceramics embody the unique advantages, but in milling of titanium alloy in application. Therefore, in this paper, TC4 titanium alloy as the object. The ultrasonic vibration assisted milling experiments. Analysis of the effect of ultrasonic vibration and process parameters on tool wear, cutting force and surface integrity are studied. Firstly, the design of ultrasonic vibration The auxiliary tool wear in milling of titanium alloy, analyzed the mechanism of tool wear in milling. The morphology were observed and analyzed by means of tool wear in different milling time under ordinary milling and ultrasonic vibration assisted milling, found the auxiliary effect of ultrasonic vibration has significant effect on the tool processing process produces wear. And can prolong the service life of the cutter. At the same time compared the titanium alloy under two different processing chip chip morphology, found tiny fine under the ultrasonic vibration assisted milling and uniform arc shape. Secondly, the milling force experiment of ultrasonic vibration assisted milling of titanium alloy in different milling parameters, with the analysis of changes the influence of milling parameters, effect of ultrasonic vibration on milling force. The experimental results show that the auxiliary effect of ultrasonic vibration can reduce the milling process of titanium alloy The average milling force and milling force, and in a certain range, the greater the current ultrasonic milling force, milling force is small. Two kinds of processing modes with increasing spindle speed decreases; increased with increasing feed rate and cutting depth, but the ultrasonic vibration assisted milling force increased more slowly. In addition, to establish a prediction model of ultrasonic vibration assisted milling of titanium alloy milling force index based on the experimental data, and the processing parameters of milling of titanium alloy were optimized. The results showed that the index model prediction accuracy and stability are relatively high; the optimized milling force decreases, the optimization effect is obvious. Finally, through non contact measurement of surface morphology of 3D titanium alloy under different machining parameters of 3D roughness. The results show that the vibration frequency of the impact of the titanium alloy surface is more fine and uniform, the main shaft speed The increase is beneficial to reduce the surface roughness, and cutting depth on surface roughness is smaller. Effects of two kinds of processing methods in different milling depth of edge quality was analyzed by stereomicroscope. Ultrasonic vibration assisted milling after edge quality and ordinary milling than improved, not only small size of burr but the intensity is also much lower than the ordinary milling; in addition, with the increase of burr increased milling depth under two different processing to a certain degree. The titanium alloy surface residual stress under different ultrasonic current were measured using X ray diffraction. The results show that the ultrasonic vibration assisted milling surface compressive residual stress the impact of high frequency vibration, is beneficial to improve the machined surface residual compressive stress, and with the increase of current ultrasound showed an increasing trend.

【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG663;TG54

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