Ballbar Identification of Five-Axis Rotary Geometric Errors
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Solution Overview
Problem
Current methods for measuring position-independent geometric errors in the rotary axes of five-axis machine tools are inefficient and complicated, often requiring multiple installation positions and being affected by translation axis errors, leading to inaccurate identification.
Innovation Solution
An identification method using a ballbar that establishes coordinate systems based on a kinematic chain structure, performing error measurement under three installation modes with single-axis motion of the A and C axes, and calculating geometric errors through MATLAB fitting, eliminating the need for extension rods and rotary axis identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multi-axis coordinated measurement is used, then measurement coverage is improved, but measurement accuracy deteriorates due to translation axis errors affecting rotary axis error identification
Solution Approach 1:
The measurement process is segmented into separate single-axis measurement steps for the A-axis and C-axis, rather than performing multi-axis coordinated measurement simultaneously. This segmentation isolates the rotary axis measurements from translation axis errors, improving identification accuracy while maintaining comprehensive error coverage through systematic single-axis testing.
2Measurement precision
If existing ballbar-based identification methods with multiple installation positions are used, then measurement completeness is improved, but measurement time and complexity increase
Solution Approach 1:
The ballbar measurement system is designed with universal applicability to measure all rotary axis geometric errors through a single installation position. The system achieves multi-functionality by capturing both A-axis and C-axis errors, as well as their interaction errors, without requiring multiple installation positions, thereby reducing measurement time while maintaining completeness.
3Measurement precision
If existing ballbar-based identification methods with multiple installation positions are used, then error coverage is improved, but installation complexity increases
Solution Approach 1:
The method extracts and eliminates the requirement for multiple installation positions from the measurement process. By designing the ballbar system to function universally from a single installation position, the complex installation procedures associated with multiple positions are removed, simplifying the overall measurement setup while maintaining comprehensive error identification capability.
Data Source
AI summary
An identification method of position-independent geometric errors in rotary axes of five-axis machine tools based on ballbar, in which a center of a cutter ball is installed at an intersection point of A-axis and C-axis centerlines; a workpiece ball is installed with an offset in X and Y directions; the two axes are controlled to move independently to switch between two measurement modes under a single installation mode; and through three installations, eight position-independent geometric errors of the two axes are identified. In the method, coordinates of the workpiece ball are calculated through inverse matrix transformation, so as to establish initial coordinates of the two balls in a reference coordinate system; a comprehensive rod-length model including installation errors is constructed based on homogeneous coordinate transformation; and simulation analysis is conducted to compare identified values with preset values.