Study Of Accuracy Inspection And Evaluation Of Coordinate Measuring Machine And Virtual Coordinate System

As a large, multi-functional modern precision instrument, coordinate measuring machine(CMM) has more and more shown its great importance and wide development prospect in industry. It has the advantages of strong versatility, accurate and reliable measurement and convenient data processing. It is a significant part in automated manufacturing and flexible production assembly. Thus, there are many researches on CMM. And the error correction of CMM is the focus of international researches. These include the researches on rapid inspection and inspection tools, dynamic error correction and thermal deformation error correction and so on. The main work of this paper involves the evaluation and correction of CMM static and dynamic errors, including the inspection of CMM using ball plate, the evaluation of CMM dynamic errors. And also this paper brings forward a novel way of inspecting and correcting CMM static and dynamic errors: error correction based on virtual coordinate measuring system. The detailed research aspects are as follows:The ball plate has some potential applications in the precision verification of CNC machine and CMM. This paper discusses the precision problems of using the ball plate, and analyzes the influences on the measured results subject to the ball plate calibration error and position error on the working bench. This paper presents two methods which can reduce the influences of the above two errors and proposes a combination verification method to verify the precision of the ball plate. In addition, this paper presents the experiment of verifying CMM accuracy with ball plate. The experimental system of calibrating the center distance of two balls of ball plate is given. And the results of verifying the axis accuracy of CMM are also given.In view of the limitation of current commonly used method-the static evaluation method, which may result in an incorrect assessment owing to the very dynamic nature of the CMM, this paper presents an error separation method for dynamic measuring data to obtain their accuracy evaluation indices. Referring to international evaluation principles of measurement uncertainty, this method was derived from the analysis of dynamic measuring data and dynamic measuring error. To verify the validity of the proposed method, the dynamic accuracy of a CMM was evaluated and was found to be much better than that of the current static evaluation method.This paper brings up with the theory of Virtual Coordinate Measuring System. The basic theoretic models of the virtual coordinate measuring system are given. This theory of virtual coordinate measuring system makes use of the principle of Time-Space correspondence and turns the time pulses into spatial displacement. The virtual coordinate measuring system can take the place of the scale system in traditional instruments, which has the disadvantages of high cost and difficulty ofproduction.This paper gives the basic theoretic models of two-dimension and three-dimension virtual coordinate measuring systems. By the way of embedding the 2- and 3- dimension virtual coordinate measuring systems into the 2- and 3-dimension measuring instruments respectively, the systematic and random errors of the instruments can be obtained and corrected. The independent virtual coordinate measuring system as a new kind of measuring instrument is also studied in this paper.The experiments of one-dimension coordinate measuring system are also studied. The one-dimension virtual coordinate system is carried out on a three-Coordinate Measuring Machine. The data of the experiments are analyzed.This paper brings forward a novel way for the academic and industrial circles in structuring a virtual coordinate measuring system inspecting and correcting CMM static and dynamic errors compensatory technology, which has the value of application and research.