Method for detecting space error of machine tool by using ball rod instrument constructed by ball hinge

Abstract

The invention discloses a method for detecting a space error of a machine tool by using a ball rod instrument constructed by a ball hinge. An existing ball rod instrument difficultly achieves high precision in a small range. According to the method, the ball rod instrument is prepared by utilizing the precise ball hinge, and the posture of a ball rod in space is solved based on a geometric principle according to distances between an exit point of each ultrasonic transmitter and receiving points of four ultrasonic receivers; coordinates of a ball center position point of a positioning ball under a Cartesian coordinate system when the space error of a main shaft of the machine tool is not considered and coordinates of an actual position point of the ball center of the positioning ball when the space error of the main shaft of the machine tool is considered are obtained according to the rod length of the ball rod instrument; and meanwhile, according to the differential capacitance of twopairs of spherical crown-shaped electrodes and a pair of spherical belt-shaped electrode plates, an X value, a Y value and a Z value of ball head eccentricity are calculated, and finally the theoretical track and the actual track of the main shaft of the machine tool and the space error offset of the main shaft of the machine tool are obtained. According to the method, compared with the existing ball rod instrument, the size is much smaller, and the high precision can be achieved within the small range.

Description

technical field [0001] The invention belongs to the technical field of machine tool precision detection, and in particular relates to a method for detecting space errors of machine tools using a ballbar constructed with a ball hinge. Background technique [0002] The ballbar is a multi-purpose measuring tool that can be applied to the error detection of various types of CNC machine tools. It has been quickly accepted since its inception and has been widely used in actual inspection work. [0003] A conventional ballbar is essentially a high precision telescoping linear sensor with a precision ball at each end and is equipped with two precision magnetic cups to mount the ballbar on the machine tool. During use, the precision ball of a conventional ballbar is fixed to the magnetic bowl in a three-point orientation. When the machine tool performs arc interpolation motion with the center ball seat on the workbench as the center of the circle, the ballbar can measure the slight ...

AI Technical Summary

Problems solved by technology

However, during the testing process, the geometric motion of the machine tool has errors in the axial expansion and contraction direction of the ballbar, and there are certain geometric motion errors in other degrees of freedom (such as degrees of freedom perpendicular to the axial expansion and contraction direction of the ballbar) , and the coupling relationship of multiple degrees of freedom directional errors will directly affect the detection accuracy of the ballbar's axial expansion and direction errors, so it is difficult for conventional ballbars to measure the spatial error of the machine tool (the comprehensive error of multiple degrees of freedom) Evaluation, it is necessary to obtain the spatial error field of the machine tool by detecting and comprehensively analyzing the machine tool errors in different directions

The comprehensive analysis of one-way errors is a tedious and time-consuming process, so scholars have conducted extensive research on the method of directly measuring spatial errors using measuring devices

John C.Ziegert used the developed laser ballbar to directly measure the spatial error of the machine tool based on the triangulation method; Shih-Ming Wang et al. used this principle to obtain the spatial error of the machine tool with a ballbar, but the data processing and instrument calibration of this method complex, difficult to apply

B.Li proposed a spatial micro-displacement measurement method. This method can directly obtain the three-dimensional coordinates of the cone relative to the sensor by using a triangular pyramid and three displacement sensors. However, the structure of the device is complex and the installation is complicated, which is not conducive to popularization.

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