Abstract
Turn-Milling Combined NC machine tool is different from traditional machine tools in structure and process realization. As an important means in the design stage, the analysis method of geometric accuracy error is also different from the traditional method. The actual errors and the error compensation values are a pair of "symmetry" data sets which are connected by the movement of machine tools. The authors try to make them more consistent through this work. The geometric error terms were firstly determined by topological structure analysis, then based on homogeneous coordinate transformation and multibody system theory, the geometric error model was established. With the interval theory, the function rule of sensitivity of geometric error sources to spatial errors was analyzed in detail, and the global maximum interval sensitivity of nine geometric error sources was extracted, providing a theoretical basis for error compensation and precision distribution. The geometric error sensitivity analysis method proposed in this paper can accurately evaluate the influence weights of each error term on the machining accuracy, and identify the important sensitive error terms with great influence on the machining accuracy from many error terms.
Highlights
Aimed at actual processing needs of the automotive, aerospace, military, and other industries, Turn-Milling combined NC machine tool can carry out turning, milling, drilling, grinding, and other multi-process compound processing, the use of multi-axis linkage function can complete the inclined parts and complex space surface processing, which is greatly improving the processing efficiency and accuracy
The geometric error sensitivity analysis method proposed in this paper can accurately evaluate the influence weights of each error term on the machining accuracy, and identify the important sensitive error terms with great influence on the machining accuracy from many error terms
Guo et al used various methods for error sensitivity analysis and error optimization methods, such as the use of extended Fourier amplitude sensitivity test method to establish a quantitative global sensitivity analysis model for geometric error elements, which is suitable for identifying the key geometric errors and improving the precision of CNC machine tools effectively [18]
Summary
Aimed at actual processing needs of the automotive, aerospace, military, and other industries, Turn-Milling combined NC machine tool can carry out turning, milling, drilling, grinding, and other multi-process compound processing, the use of multi-axis linkage function can complete the inclined parts and complex space surface processing, which is greatly improving the processing efficiency and accuracy. Fu et al [13,14] used the product-of-exponential theory to establish an exponential product error model for CNC machine tools and proposed a geometric error compensation method based on Jacobian of twists. Guo et al used various methods for error sensitivity analysis and error optimization methods, such as the use of extended Fourier amplitude sensitivity test method to establish a quantitative global sensitivity analysis model for geometric error elements, which is suitable for identifying the key geometric errors and improving the precision of CNC machine tools effectively [18] He used the global sensitivity analysis method to quantitatively analyzed the influence of uncertainty of geometric error on the multidimensional output simultaneously [19,20]. As a new type of machine tool, this work provides an effective method to improve the machining accuracy
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