Precision Machining by Local Machining Station Method

针对工业机器人自动加工系统，提出了局部加工站（LMS）方法。该方法旨在提高大型工件局部定位精度和机器人加工系统的刚度。LMS由一个带有位移传感器的基准板、几个支腿和一个可移动的小型机床组成。腿的长度是可变的。机架和机床固定在基准板上。LMS作为末端执行器安装在机械臂上。当LMS用腿夹紧在大型工件上时，机器人加工系统的刚度增加。由于移动机床的位置是通过参考板上的位移传感器来测量的，因此对大型工件局部区域的定位精度变得更高。在试验中制造了LMS样机。在参考板上安装一个铅笔大小的电火花机作为活动机床。原型通过PI控制进行定位。腿的长度是用电位器测量的。样机的定位精度为几十微米数量级。在工件上用孔确定一个坐标系，在坐标系上加工其他一些孔。LMS法加工孔的精度优于机器人。

In this study, Local Machining Station (LMS) method is proposed for automatic machining systems with industrial robots. This method aims to improve the positioning accuracy for a local area of a large workpiece and the stiffness of the robot machining system. The LMS consists of a reference plate with displacement senosors, several legs and a movable small machine tool. The length of the legs is variable. The lags and the machine tool are fixed on the reference plate. The LMS is mounted on a robot arm as an end-effector. When the LMS is clamped onto a large workpiece with its legs, the stiffness of the robot machining system increases. Since the position of the movable machine tool is measured with the displacement sensors on the reference plate, the positioning accuracy for a local area of the large workpiece becomes higher. A prototype of LMS is manufactured in trial. A pencil-size electrical discharge machine is installed on the reference plate as the movable machine tool. The prototype is positioned by the PI control. The length of the legs is measured with potentiometers. The positioning accuracy of the prototype is several tens micrometer order. A coordinate system is settled by using holes on a workpiece and some other holes are machined on the coordinate system. The accuracy of machined holes by the LMS method is better than that with a robot.