型腔拐角铣削加工参数优化与研究

发布时间：2019-06-20 13:17

【摘要】：模具被普遍的应用于汽车产业、手机产业和航空航天产业等领域,因此模具的数控加工精度是一个重要研究对象。由于产品零件的形状变化万千,使得模具的形状千差万别,特别是模具有较多拐角时,增加了加工难度。这些角度不同的锐角、钝角等内外过渡连接,使得铣削加工过程中,刀具产生的铣削力波动增大造成工件震颤、加工效率降低等问题。本文针对平面拐角铣削加工效率和铣削力问题进行了研究。首先,查阅了国内外研究现状,拐角处优化加工有三种方式:(1)数控系统控制方面,利用数控系统的自身的控制方式如运动轨迹插补特性、速度前瞻预处理、加减速运动控制等方面;(2)刀具轨迹方面,考虑的是最优路径、走刀优化等;(3)工艺参数方面,主要考虑进给速度、切削深度和主轴转速等参数。比较三种方式优缺点,本文采用工艺参数方面。其次,剖析了铣削平面拐角时铣刀与工件的位置参数关系,得出铣削过程中刀刃真实轨迹,经分析其真实轨迹给出了平面拐角铣削加工过程中相应参变量的数学表达式。针对典型性的模具型腔拐角,使用平面几何理论对铣削加工过程中铣刀与工件不同阶段的接触情况进行了分析,得出了铣刀与工件瞬时接触角的变化趋势,并根据瞬时接触角度的变动求解拐角加工过程中的刀刃瞬时铣削面积,以此建立了计算刀刃瞬时铣削面积的公式。再次,使用仿真软件DEFORM-3D,对设计的对比参数方案进行了模拟仿真,获得了铣削载荷曲线,针对曲线的波动情况,选用统计分析的方法,在MATLAB中使用“3σ”原则剔除了仿真结果中的异常数据,保证了仿真数据的可靠性。通过对铣削力、铣刀扭矩与进给量、铣刀转速的函数关系进行推导,将指数公式转化为线性公式,为数据分析提供了依据。通过MATLAB软件,对仿真结果数据进行了回归分析,得到了铣削力和铣削扭矩的预测模型,并且通过对数据线性相关性和线性拟合度的分析,考证了数据的可靠性。最后,详细介绍了粒子群算法(POS)的基本理论、形式和设计流程,根据算法基本形式推导出了优化目标的函数和约束条件的数学模型,根据基本流程在MATLAB软件中编制了优化程序,迭代运算结果显示拐角铣削优化后铣削参数设置比经验参数设置加工时间节省了54.75%与58.20%。
[Abstract]:Mould is widely used in automobile industry, mobile phone industry, aerospace industry and other fields, so the NC machining accuracy of die is an important research object. Because of the thousands of changes in the shape of the product parts, the shape of the die is very different, especially when the die has more corners, it increases the difficulty of machining. The internal and external transition connections of these angles, such as sharp angle, obtuse angle and so on, make the milling force fluctuation produced by the cutting tool cause the workpiece trembling and the machining efficiency decrease in the milling process. In this paper, the machining efficiency and milling force of plane corner milling are studied. First of all, after consulting the research status at home and abroad, there are three ways to optimize machining at the corner: (1) in the control aspect of NC system, the control mode of NC system, such as the interpolation characteristic of motion trajectory, speed prospective preprocessing, acceleration and deceleration motion control, etc. (2) in the aspect of tool path, the optimal path is considered, and the optimization of tool walking is considered. (3) in terms of process parameters, feed speed, cutting depth and spindle speed are mainly considered. The advantages and disadvantages of the three methods are compared, and the process parameters are adopted in this paper. Secondly, the relationship between the position parameters of milling cutter and workpiece when milling plane corner is analyzed, and the real trajectory of cutter edge in milling process is obtained, and the mathematical expression of the corresponding parameter variables in the process of plane corner milling is given by analyzing its real trajectory. Aiming at the typical corner of die cavity, the contact between milling cutter and workpiece in different stages is analyzed by using plane geometry theory, and the changing trend of instantaneous contact angle between milling cutter and workpiece is obtained, and the instantaneous milling area of cutting edge in the process of corner machining is solved according to the change of instantaneous contact angle, and the formula for calculating the instantaneous milling area of cutter edge is established. Thirdly, the simulation software DEFORM-3D, is used to simulate the designed comparative parameter scheme, and the milling load curve is obtained. according to the fluctuation of the curve, the statistical analysis method is selected, and the abnormal data in the simulation results are eliminated by using the "3 蟽" principle in MATLAB to ensure the reliability of the simulation data. Through the derivation of the functional relationship between milling force, milling cutter torque and feed rate and milling cutter speed, the exponential formula is transformed into a linear formula, which provides a basis for data analysis. Through MATLAB software, the regression analysis of the simulation data is carried out, and the prediction model of milling force and milling torque is obtained, and the reliability of the data is verified by analyzing the linear correlation and linear fitting degree of the data. Finally, the basic theory, form and design flow of particle swarm optimization algorithm (POS) are introduced in detail. According to the basic form of the algorithm, the mathematical model of optimization objective function and constraint conditions is deduced. According to the basic flow, the optimization program is compiled in MATLAB software. The iterative operation results show that the machining time of milling parameters after corner milling optimization is 54.75% and 58.20% less than that of empirical parameter setting.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG547

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