圆柱坐标数控机床加工整体叶轮的运动学分析

Kinematic Analysis of Cylindrical Coordinate CNC Machine in Integral Impeller Machining

为研究一种叶轮加工的新方法,使其能够提高叶轮加工时机床的刚性,并且降低叶轮加工的成本。从机构学角度提出并分析了一种用于整体叶轮三轴联动数控加工的机床模型和运动模型。该机床由2个线性轴和1个转动轴组成,称为圆柱坐标数控机床。另外,该机床具有2个辅助轴用于调整主轴姿态,且加工过程中上述两轴被锁紧。通过遍历待加工叶轮叶片上选择的采样点,可寻找每个采样点对应的主轴姿态可行域空间,并可在所有可行域的基础上求解公共的可行域,进而可在此公共可行域中确定机床主轴的姿态。使用提出的算法求解该数控机床加工叶轮的运动,并在VERICUT软件中对某一叶轮进行了加工仿真以验证该圆柱坐标数控机床模型和相关算法。对于此叶轮,求出的机床可行的B′的值在[-5°,9°]之间,对应的C′的值在[-3°,3°]之间,使用圆环面刀具计算刀轨后在VERICUT中进行仿真,仿真结果表明95%的加工区域的欠切量在0.02mm以内,即此方法可用于叶轮加工。使用该新型圆柱坐标数控机床加工叶轮的方案是可行的,且具有工业应用价值。

The purpose of this study is to research a new impeller machining method that can improve a machine tool＇s rigidity and reduce its machining cost.This paper presents and analyzes the structure model and kinematic configuration of a novel machine tool from the viewpoint of mechanism.The machine tool,which is called a cylindrical coordinate CNC machine,consists of two linear motion axes,one rotational axis and two auxiliary axes used to adjust the spindle＇s posture,which are fixed during machining.By traversing every sampling point selected from an impeller＇s blade,the corresponding feasible region of the spindle＇s posture can be found in each sampling point.The common feasible region is obtained based on all these feasible regions.Then the spindle＇s posture can be confirmed in this common feasible region.The motion of the CNC machine is calculated by using the proposed algorithm to machine impellers.And the simulation of an impeller＇s machining is completed in software VERICUT to verify the cylindrical coordinate CNC machine and the relevant algorithm.For this impeller,the feasible value of the machine tool＇s B＇ is between-5° and 9°,the relevant value of C＇ is between-3° and 3°.The torus is used to calculate the cutter path which is simulated in VERICUT.The simulation result shows that,95％ of the machining region＇s undercut is less than 0.02 mm,which means this method is useful in impeller machining.It is believed that this methodology of using the novel cylindrical coordinate CNC machine for impeller manufacturing is workable and valuable in the manufacturing industry.