基于加工仿真的钛合金Ti6Al4V螺旋铣孔专用刀具优化设计

发布时间：2019-05-06 19:19

【摘要】：随着飞机飞行性能要求的不断提高,航空制造领域一直致力于新型材料的应用,通过降低机体质量以及提高结构强度来提高飞机的综合性能,钛合金等新型材料由于具备密度小、比强度高、耐腐蚀及耐热性能好等种种优越的性能被广泛地应用在飞机结构部件。然而,因为钛合金存在导热性能差、弹性模量小以及化学活性高等问题,使得切削时散热效果不充分,容易造成切削温度过高,表面产生冷硬现象,而且已加工表面回弹严重,造成刀具磨损加剧,是一种典型的难加工材料。而在飞机装配现场工况下,传统的钻孔加工方式已经难以满足难加工材料的加工要求,针对钻孔工艺存在的种种不足,螺旋铣孔工艺应运而生。螺旋铣孔采用偏心加工的方式,大大改善了散热条件,能显著减小切削力,有利于提高加工质量和刀具寿命,是当前国内外相关领域研究的热点。本文通过切屑分析并利用有限元模型,对适用于螺旋铣孔加工方式的专用刀具优化设计展开了研究。首先,通过研究刀具在螺旋铣孔加工时的运动特征建立了刀具的运动方程并建立了各控制参数与切削用量之间的关系,利用三维建模软件建立了未变形切屑的实体模型,并结合文献、试验对比了不同刀具进行螺旋铣孔加工时切屑的特征,分析了采用传统形式铣刀进行螺旋铣孔加工的弊端并提出专用刀具的优化设计思路。根据螺旋铣孔加工过程的特殊性,进行了钛合金Ti6A14V螺旋铣孔三维切削过程的有限元建模,并利用两组参数试验验证了有限元模型的准确性。利用该有限元模型进行了以轴向切削力为评判指标,刀具V型刃夹角、V型刃倾斜角、刀具前角为因素的正交试验,采用极差分析的方法得到不同刀具几何参数对轴向切削力的影响规律,并得到刀具优化的角度。同时利用该模型对螺旋铣孔切削条件下的流屑特征进行了初步的研究,为刀具冷却孔的开设提供了参考。最后,采用螺旋铣孔试验平台对优化后的刀具进行了螺旋铣孔加工钛合金的刀具寿命试验,试验结果证明,相对于优化前的专用刀具,优化后刀具寿命得到明显提高,且加工性能良好。
[Abstract]:With the continuous improvement of aircraft flight performance requirements, the aviation manufacturing field has been committed to the application of new materials, by reducing the mass of the airframe and improving the structural strength to improve the overall performance of aircraft. Because of its low density, high specific strength, good corrosion resistance and heat resistance, titanium alloys and other new materials have been widely used in aircraft structural components. However, due to the problems of poor thermal conductivity, low elastic modulus and high chemical activity of titanium alloy, the heat dissipation effect during cutting is not sufficient, and the cutting temperature is too high, the surface of titanium alloy is hard and cold, and the rebound of machined surface is serious. The tool wear is aggravated, and it is a typical difficult-to-work material. However, under the condition of aircraft assembly site, the traditional drilling technology can not meet the requirements of difficult-to-process materials. In view of the shortcomings of drilling technology, spiral milling technology emerges as the times require. The eccentric machining of helical milling hole greatly improves the heat dissipation condition and can significantly reduce the cutting force, which is beneficial to the improvement of machining quality and tool life. It is a hot topic in the field of research at home and abroad at present. In this paper, the chip analysis and finite element model are used to study the optimal design of special cutting tools suitable for screw milling. Firstly, the motion equation of the cutter and the relationship between the control parameters and the cutting parameters are established by studying the motion characteristics of the cutter in the machining of spiral milling hole, and the solid model of the undeformed chip is established by using the 3D modeling software. Combined with the literature, the paper compares the chip characteristics of different cutting tools in helical milling, analyzes the disadvantages of traditional milling cutters in helical milling, and puts forward the optimized design idea of special cutting tools. According to the particularity of spiral milling process, the finite element modeling of three-dimensional machining process of titanium alloy Ti6A14V spiral milling hole was carried out, and the accuracy of the finite element model was verified by two groups of parameter tests. Based on the finite element model, the orthogonal test is carried out with axial cutting force as evaluation index, V-shaped edge angle, V-shaped edge inclination angle and tool front angle as the factors, and the cutting force is used as the evaluation index, and the cutting tool V-shaped edge angle is included. The influence of different tool geometry parameters on the axial cutting force is obtained by using the method of extreme difference analysis, and the optimization angle of the tool is obtained. At the same time, the chip characteristics under the condition of spiral milling are studied by using the model, which provides a reference for the opening of cooling holes of cutting tools. Finally, the optimized tool life of titanium alloy is tested by spiral milling test platform. The results show that compared with the special tool before optimization, the tool life of optimized tool is improved obviously, and the cutting tool life of the optimized tool is improved obviously compared with the special tool before the optimization, and the tool life of the optimized tool is improved obviously. And the processing performance is good.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG71

【共引文献】