The geometric accuracy of the fixed beam gantry machining center directly determines the machining accuracy of the workpiece and is the core indicator for equipment performance evaluation. Geometric accuracy testing quantifies the form and position errors of key components of equipment through professional instruments, determines whether they meet design standards, and provides a basis for equipment debugging, maintenance, and accuracy compensation. Its principles and processes must follow rigorous technical logic.

The detection principle is based on geometric measurement as the core, relying on the two core logics of "benchmark comparison" and "error accumulation analysis". Benchmark comparison refers to selecting key reference surfaces of equipment (such as workbenches and guide surfaces) as measurement benchmarks, and comparing the measured geometric quantities with standard quantities through precision instruments such as laser interferometers, ball bar gauges, and level gauges to quantify the deviation values. Error accumulation analysis focuses on the equipment motion chain, and the motion accuracy of the fixed beam gantry machining center is determined by multiple links such as guide rail guidance accuracy and screw transmission accuracy. During detection, it is necessary to analyze the transmission and accumulation laws of errors in each link, and identify the fundamental source of positioning accuracy deviation. The core testing indicators include guide rail straightness, coordinate axis parallelism, spindle and worktable perpendicularity, crossbeam levelness, etc. These indicators directly affect the dimensional accuracy and form tolerance of the workpiece.

The testing process should follow the standardized steps of "preliminary preparation benchmark calibration sub item testing data processing result judgment". In the early preparation stage, it is necessary to clean key parts such as equipment workbenches and guide rails, remove impurities such as chips and oil stains, and avoid affecting measurement accuracy; At the same time, check the calibration status of the testing instruments to ensure that their accuracy meets the requirements, and install and debug the instruments according to the testing items.

Benchmark calibration is the fundamental step in testing. Firstly, use a level to measure the flatness of the workbench as a reference, ensuring that the accuracy of the reference surface meets the standard; Subsequently, calibrate the guide rail reference, use a laser interferometer to detect the straightness of the X and Y axis guide rails, and mark the reference line as the reference standard for subsequent testing. The sub item inspection should be carried out in the order of "static accuracy dynamic accuracy", with static inspection focusing on fixed geometric relationships such as horizontal alignment of the crossbeam, perpendicularity of the spindle axis and the worktable; Dynamic detection simulates the machining motion trajectory of the equipment through a ball bar instrument, and detects the coordinate axis linkage accuracy and positioning accuracy.

In the data processing stage, abnormal data needs to be removed, and the measurement data should be analyzed based on equipment design standards to determine whether the deviation of each indicator is within the allowable range. If there is an accuracy deviation, a testing report should be issued to clarify the deviation items, deviation values, and possible sources of error, providing technical basis for subsequent equipment debugging.

Scientific geometric accuracy testing is the key to ensuring the machining quality of fixed beam gantry machining centers. Strictly following the testing principles and standardized processes can accurately grasp the accuracy status of equipment and provide reliable support for the full life cycle management of equipment.