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Computing approach of uncut chip thickness in orthogonal turn-milling with inserted cutters
QIU Wenwang, LIU Qiang, YUAN Songmei
School of Mechanical Engineering and Automation, Beijing University of Aeronautics and Astronautics, Beijing 100191, China
Abstract: The computing of uncut chip thickness is the basis for further studying the cutting mechanism as well as simulating the cutting process. The research about orthogonal turn-milling operation with inserted cutters was focused on. By simplifying the trajectory of cutting edge, the uniform formulation to calculate uncut chip thickness for cutters with different shapes was derived and then compared with the numerical method through several examples. Upon the presented formulation of uncut chip thickness, the cutting force in orthogonal turn-milling operation was predicted and a validation experiment was carried out on a turn-milling machine tool. Both the comparison examples and the result of cutting force prediction show that the presented approach can provide a solution for the calculation of uncut chip thickness with good accuracy and high computation efficiency. Due to the uniform expression, the proposed approach is suitable for the development of general simulation software for orthogonal turn-milling process and thus has potential value in engineering practice.
Key words: inserted cutters     orthogonal turn-milling     cutting edge trajectory     uncut chip thickness     cutting force

1 正交车铣运动关系的描述 1.1 正交车铣概述

 图 1 正交车铣示意图 Fig. 1 Orthogonal turn-milling process

 图 2 不同形状的面铣刀 Fig. 2 Inserted cutters with different shapes
1.2 切屑厚度计算公式的推导

 图 3 刀具坐标系和工件坐标系 Fig. 3 Tool coordinate system and workpiece coordinate system

 图 4 切屑厚度的示意图 Fig. 4 Schematic diagram of uncut chip thickness

A在刀具坐标系中的坐标表达式可以写成式(4)的形式,如同前面介绍的点P一样,通过对式(4)进行旋转变换和平移变换便可得到点A在工件坐标系中的表达式.

γ=0,上面所推导的公式便可以用来计算图 2(a)所示铣刀正交车铣加工时的切屑厚度.

1.3 圆刀片铣刀的情形

 图 5 圆刀片铣刀几何包络的近似 Fig. 5 Approximation of geometry envelop of round insert cutter

2 仿真实例验证

 图 6 γ为0°的铣刀切屑厚度的仿真实例 Fig. 6 Simulation example of uncut chip thickness for cutter with γ being 0°
 图 7 γ为45°的铣刀切屑厚度的仿真实例 Fig. 7 Simulation example of uncut chip thickness for cutter with γ being 45°
 图 8 圆刀片铣刀切屑厚度的仿真实例 Fig. 8 Simulation example of uncut chip thickness for round insert cutter

 图 9 转速比对切屑厚度仿真误差的影响 Fig. 9 Influence of speed ratio on simulation error of uncut chip thickness
3 实验验证

 图 10 切削力测试实验设置 Fig. 10 Experimental setup of cutting force test
 图 11 切削力仿真结果与实验对比 Fig. 11 Comparison of simulation results of cutting forces and experimental results
4 结论

1) 本文在对切削刃轨迹进行近似的基础上,给出了一种计算面铣刀正交车铣加工过程侧刃切屑厚度的统一模型.

2) 结合几组实例,应用本文所提出的模型对切屑厚度进行了仿真,并与数值方法的计算结果进行了对比分析.结果显示,在仿真的接触角范围内,二者的相对误差在10%以内.

3) 在本文切屑厚度模型的基础上对切削力进行了仿真,并在车铣复合机床上进行了实验验证.数据对比显示,仿真得到的切削力曲线的波形和幅值均能够与实验结果较好地吻合.

4) 仿真分析及切削力实验验证结果显示,在一定的参数范围内,本文所提出的方法能够正确地计算正交车铣加工中刀具侧刃的切屑厚度,并且具有良好的精度;同时省去了数值方法中的迭代运算,具有较高的计算效率和较大的实际应用价值.

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#### 文章信息

QIU Wenwang, LIU Qiang, YUAN Songmei

Computing approach of uncut chip thickness in orthogonal turn-milling with inserted cutters

Journal of Beijing University of Aeronautics and Astronsutics, 2015, 41(9): 1638-1644.
http://dx.doi.org/10.13700/j.bh.1001-5965.2014.0700