Method for calibrating articulated coordinate measuring machine in combination with numerical control machine tool

Abstract

The invention discloses a method for calibrating an articulated coordinate measuring machine in combination with a numerical control machine tool. A traditional measuring machine calibration method requires a high-precision measuring instrument or auxiliary calibration tool, and has difficulty in field calibration. The method comprises installing a three-ball cone calibration tool on the main shaft of the numerical control machine tool, and setting virtual calibration rods in a defined measurement area, wherein each virtual calibration rod is a line for successively connecting t measuring points arranged at equal intervals; enabling the taper hole center of the three-ball cone calibration tool to successively position respective measuring points; after a certain measuring point is positioned, embedding the spherical measuring head of a calibration machine in the taper hole of the three-ball cone calibration tool for data sampling; for the data sampling in each time, enabling the calibration machine to measure the taper hole center of the three-ball cone calibration tool for n times within an articulated operation range in different attitudes; and processing the coordinate value ofthe measuring head obtained after the data sampling to obtain the optimal solution of the structural parameter vector A of the calibration machine. The method, by using the numerical control machine tool as a calibration instrument, improves field environment adaptability and reduces cost.

Description

technical field [0001] The invention belongs to the technical field of coordinate measurement, and in particular relates to a calibration method for an articulated coordinate measuring machine combined with a numerical control machine tool. Background technique [0002] The articulated coordinate measuring machine is a multi-degree-of-freedom coordinate measuring machine, which consists of a measuring arm and a rotating joint connected in series to form an open chain structure. Compared with the traditional three-coordinate measuring machine with orthogonal coordinate system, it has the advantages of small size, large measurement range, convenience and flexibility, and good environmental adaptability. However, due to the shortcomings of accumulative error amplification in this series structure, the structural parameter errors of joints at all levels will be amplified step by step, resulting in a decrease in its accuracy. In order to improve the measurement accuracy of the m...

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Problems solved by technology

"An Optimal Sampling Strategy for Structural Parameter Calibration of a Portable Articulated Coordinate Measuring Machine" (Tool Technology, 2012) uses a quartz rod with cone dimples at both ends for calibration, and places the quartz rod at six circumferential positions where the measuring machine is the center of the circle At each position, 500 sets of data were measured by rotating the quartz rod in different planes with a certain division, a total of 3,000 sets of data; although such a sampling strategy can satisfy the entire measurement space, the implementation process is complicated, and at the same time, it does not consider Single-point repeatability is the precision indicator

[0005] The above methods still have deficiencies in calibration. During the calibration process, high-precision measuring instruments or high-precision auxiliary calibration tools are required, and it is difficult to calibrate in the field.

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