Research on a Novel Method for Measuring Volumetric Error of Coordinate Measuring Machine
CMM (Coordinate Measuring Machine) is used as an accurate measuring instrument in manufacturing and design of products. High accurate CMM is required by the development of super-finish, micro-machinery, micro-electronic mechanical systems (MEMS). The precision of CMM is influenced by its volumetric error and dynamic error. The volumetric error is the major component during slowly probing, but the dynamic error is not omitted during fast probing. Compensating the volumetric error is an effective approach to improve the precision of CMM. The volumetric error in the working space of CMM must be measured and the error model must be set up before compensating. In this paper, a novel method to measure 5 volumetric errors of a guide way at the same time by 3-beam laser interferometer is proposed. The error compensating model is validated by experiment. The method can also be used to measure the dynamical error of CMM and CNC machine in real-time. The research can be referred to design the super higher accurate CMM and the accurate CNC machine.
A New Method of the CMM Probe Radius Compensation
The probe radius compensated is necessary when we measure by the CMM.Based on analyses the existing methods of the probe radius compensation,a new algorithm named "4-point build a sphere" is proposed.The theory of the algorithm is expounded,at the same time,the way of gathering data and its operation speed are offered.And then,the precision of the algorithm is analyzed by computer simulation and how to improve the precision is introduced farther.And it's showed that the algorithm can satisfy a majority of measure and has application value.Finally,the algorithm is verified by an instance again.
The laser ball bar: a new instrument for machine tool metrology
Abstract Current techniques for mapping the volumetric positioning errors of machine tools are time and labor intensive. To address these shortcomings, a linear displacement measuring device is introduced to rapidly and easily determine tool positions via trilateration. The laser ball bar (LBB) consists of a laser interferometer aligned within a telescoping ball bar. The design of the device is discussed and an error budget is developed to estimate its predicted accuracy. Results of repeatability and linear accuracy test of the assembled prototype LBB are given. The LBB is used to map the volumetric errors of a two-axis turning center. Comparison of the LBB error map and the error map obtained through parametric error measurements shows the LBB can accurately map the machine errors in a timely manner.