Less Interference Optimization Method for Thread Milling Cutter Profile
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摘要: 根据螺纹铣削过程的径向和轴向干涉误差分析,提出了调整铣刀牙型轮廓特征点位置的螺纹铣刀牙型轮廓少干涉优化方法。首先,利用特征点法分别对标准螺纹和螺纹铣刀的牙型轮廓进行参数化表示;然后,建立螺纹轮廓面和螺纹铣刀铣削加工包络面的数学计算模型,以及螺纹铣削加工的干涉误差计算模型;最后,利用干涉模型计算得到的轴向和径向干涉误差,对螺纹铣刀牙型轮廓特征点进行适当调整,优化螺纹铣刀轮廓以减少干涉误差。以∅8×1.5螺纹铣刀加工M14×1.5内螺纹的加工仿真与切削实验为例,利用MATLAB计算螺纹铣刀优化后的最大干涉误差为2.6 μm,相比于螺纹铣刀优化前(8.1 μm)降低了67.9%;内螺纹铣削实验结果表明螺纹铣刀优化后的最大干涉误差仅为15.5 μm,相比于普通螺纹铣刀的最大干涉误差值(24.8 μm)降低了37.5%。可见,螺纹铣刀牙型轮廓少干涉优化方法能极大减小螺纹铣削加工干涉误差,有效提高螺纹加工精度。Abstract: Based on the analysis of radial and axial interference errors of the thread milling process, this paper presents a less interference optimal method for the thread milling cutter profile by adjusting the position of the feature points for the profile. Firstly, the feature point method is used to parameterize the standard thread profile and the thread milling cutter profile, respectively. Then, the mathematical computing models of thread contour surface and thread milling envelope surface are established, and the interference error calculation model of thread milling is established. Finally, the position of the feature points for the thread milling cutter profile is transformed appropriately by using the axial and radial interference errors which is calculated by interference model, and the thread milling cutter profile is optimized to reduce the interference errors. Taking ∅8×1.5 threaded milling cutter for machining M14×1.5 internal threads as an example, the maximum interference error of the optimized thread milling cutter calculated by MATLAB is 2.6 μm, which is 67.9% lower than that of the conventional thread milling cutter (8.1 μm). The thread milling experimental results show that the maximum interference error of the optimized thread milling cutter is only 15.5 μm, which is 37.5% lower than that of the conventional thread milling cutter (24.8 μm). It can be seen that the less interference optimal method for the thread milling cutter profile established in this paper can greatly reduce the interference errors of thread milling and effectively improve the thread machining accuracy.
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表 1 螺纹铣削仿真实验条件
螺纹类型 普通右旋圆柱内螺纹 螺纹深度L 10 mm 螺纹尺寸 M14×1.5 螺纹铣刀尺寸 ∅8×1.5 主轴转速Ss 1 500 r/min 进给速度Vf 300 mm/min 表 2 螺纹铣削加工仿真实验方案与结果
序号 迭代次数 最大干涉误差/μm 牙型轮廓优化方法 现有优化方法的 1 0 8.1 8.1 2 1 3.6 7.3 3 2 2.8 3.1 4 3 2.6 2.8 表 3 螺纹铣削加工的实验条件
毛坯材料 锻铝 工件尺寸 50×50×30 mm 普通螺纹尺寸 M16×1.5×15 mm, M14×1.5×15 mm 刀具尺寸 ∅8×1.5 主轴转速Ss 1 500 r/min 进给速度Vf 300 mm/min 表 4 螺纹铣削实验结果
序号 螺纹大径
D/mm最大干涉误差/μm 铣刀优化前 铣刀优化后 1 14 24.8 15.5 2 16 16.8 10.8 -
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