A novel method for measuring radial and axial errors in a cylindrical coordinate system using a combined double ball bar

Abstract

Multiaxis machine tools are widely used in manufacturing. The measurement of motion error is important to improve the machining accuracy of machine tools. A double ball bar (DBB), as a high-precision single-dimensional position reading device, is widely used to measure the motion error of the circular path of machine tools. However, the motion errors contain the cylindrical radial and axial errors with respect to the circular path plane. Therefore, the measurement results of the DBB are incomplete because they do not contain axial errors. To measure the motion error of the circular path accurately, completely and concisely, a novel measurement method based on the combined double ball bar (C-DBB) is proposed in this paper, which can directly measure the radius and axial motion error of the circular path in one measurement. First, the measuring principle of the C-DBB method is introduced, and the measurement model of the radius and axial motion error of the circular path is established. Then, a measuring device using the C-DBB method was designed based on the lever principle, and the error parameters of the designed device were analyzed. According to the error analysis results, the measurement results of the C-DBB method were compensated and corrected. Finally, the C-DBB method is used to measure the circular path on the vertical CNC milling machine, and the results are compared with the measurement results using the DBB method. It is shown that the proposed C-DBB method can obtain high-precision multidimensional motion error in a single measurement, and the designed measuring device based on the C-DBB method has high repeatability and good circular path measuring ability. The proposed method provides an effective method for machine tool multidimensional motion error measurement and compensation.

Fast detection of geometric errors for three-axis machine tools with combined double-ball bars based on spatial circle detection

“…Therefore, based on the equation ( 29), the measurement uncertainty µ r of the radial error and the measurement uncertainty µ a of the axial error are µ r = 0.23 µm and µ a = 1.47 µm, respectively. The detail deduction of the measurement uncertainties can be found in our previous work [33].…”

“…However, multiple measurements could introduce errors to the measurement results [30,31], which limits the measurement accuracy of the DBB for the machine tool errors. To tackle this problem, Sun et al [32,33] previously proposed combined double-ball bars (C-DBBs), which can measure both the radial and axial errors of the machine tool in a single measurement through the linkage of two linear axes of the machine tool. However, the geometric errors of machine tools include positioning errors, straightness errors, angle errors and squareness errors.…”

Optimizing dynamic measurement accuracy for machine tools and industrial robots with unscented Kalman filter and particle swarm optimization methods

“…The telescoping ballbar, first proposed and patented by Bryan in 1982 [3], revolutionized the measurement of radial changes in circular motion using an accurate linear scale sensor. Since their introduction, ballbars have been extensively applied in circular tests [4,5], calibration of rotary axes [6,7], assessment of the thermal or geometrical behavior of five-axis machine tools [8,9], kinematic calibration of parallel kinematic machines [10], and industrial robots [11]. As an efficient automated tool conforming to ISO 230-4 standards, the telescoping ballbar excels in error detection in machine tools and industrial robots, ensuring precise error identification [12].…”