<p>With the progression of CNC technology, five-axis machine tools have become increasingly prevalent due to the distinct advantages offered by the additional axes for attitude adjustment. Geometric errors constitute a substantial portion of the total errors in five-axis machine tools, with errors associated with rotary axes being the primary source. This study proposes a novel method for detecting errors in the linear and rotary axes of five-axis machine tools, improving the accuracy of geometric error identification through the application of a transposed matrix approach. Laser tracker is employed to measure the position of the machine tool tip point, and a rapid calibration technique is developed to determine the position of the laser tracker relative to the machine tool coordinate system. This calibration utilizes distance data collected as the spindle moved along an “n”-shaped trajectory within the workspace. A spatial error model is established for the five-axis machine tool, followed by sensitivity analysis of the error terms to determine those exerting the greatest influence on the position of the tool tip. In the process of identifying geometric errors associated with the rotary axis, position-independent geometric errors (PIGEs) are initially identified, followed by the identification of position-dependent geometric errors (PDGEs) after applying matrix transposition to the overall coordinates, thereby improving the overall accuracy of geometric error identification. The rotary axis was utilized as a case to experimentally validate the proposed approach, with results indicating high precision and efficiency relative to the conventional double ball bar (DBB) measurement method.</p>

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Measurement and identification of geometric errors in five-axis machine tools based on transposed matrix

  • Ying Tang,
  • Yi Wan,
  • Shuai Ji,
  • Yan Xia,
  • Xichang Liang

摘要

With the progression of CNC technology, five-axis machine tools have become increasingly prevalent due to the distinct advantages offered by the additional axes for attitude adjustment. Geometric errors constitute a substantial portion of the total errors in five-axis machine tools, with errors associated with rotary axes being the primary source. This study proposes a novel method for detecting errors in the linear and rotary axes of five-axis machine tools, improving the accuracy of geometric error identification through the application of a transposed matrix approach. Laser tracker is employed to measure the position of the machine tool tip point, and a rapid calibration technique is developed to determine the position of the laser tracker relative to the machine tool coordinate system. This calibration utilizes distance data collected as the spindle moved along an “n”-shaped trajectory within the workspace. A spatial error model is established for the five-axis machine tool, followed by sensitivity analysis of the error terms to determine those exerting the greatest influence on the position of the tool tip. In the process of identifying geometric errors associated with the rotary axis, position-independent geometric errors (PIGEs) are initially identified, followed by the identification of position-dependent geometric errors (PDGEs) after applying matrix transposition to the overall coordinates, thereby improving the overall accuracy of geometric error identification. The rotary axis was utilized as a case to experimentally validate the proposed approach, with results indicating high precision and efficiency relative to the conventional double ball bar (DBB) measurement method.