The three coordinate measuring instrument constructs a three-dimensional Cartesian coordinate system, combined with a high-precision probe system and intelligent algorithms, to achieve nanoscale precision measurement of the geometric dimensions of workpieces. Its core mechanism can be decomposed into three major steps: coordinate system establishment, probe sampling, and data processing.
1、 Construction of three-dimensional coordinate system: a reference framework for spatial positioning
The measuring instrument adopts a three-axis linkage structure (X/Y/Z axis), and real-time feedback of displacement of each axis is achieved through a grating ruler or laser interferometer. After booting up, the system establishes the origin (0,0,0) through a calibration program and defines the positive directions of the three axes to form a Cartesian coordinate system. For example, when measuring aviation blades, the X-axis corresponds to the length direction of the blade, the Y-axis corresponds to the width direction, and the Z-axis corresponds to the thickness direction, ensuring that each measurement point has a corresponding three-dimensional coordinate (x, y, z). Some devices use temperature compensated grating rulers, which can control the coordinate positioning error within ± 0.5 μ m, even if the ambient temperature fluctuates by ± 2 ℃, the coordinate system stability can still be maintained.
2、 Probe sampling: Collaborative detection of contact and non-contact methods
The probe system is the core of data acquisition and can be divided into two types: contact and non-contact. Contact probes (such as ruby probes) trigger sensors with small displacements to record the center coordinates of the probe, making them suitable for high-precision measurement of form and position errors. For example, when measuring the aperture of a car engine cylinder block, the probe scans along the hole wall, and the system calculates the roundness error through multi-point sampling. Non contact probes (such as laser probes) achieve non-contact measurement by emitting light beams and receiving reflected signals, and are suitable for soft materials or complex surfaces. Two types of probes can be switched for use, balancing measurement accuracy and efficiency.
3、 Data Processing: Intelligent Analysis from Coordinate Points to Geometric Features
The measurement software fits the collected coordinate points into geometric elements (such as planes, cylinders, cones, etc.) and optimizes the fitting accuracy through the least squares method. For example, fitting hundreds of hole wall coordinate points into an ideal cylinder, calculating its diameter, roundness, and positional accuracy. The system can also output shape and position tolerance reports, such as perpendicularity, parallelism, etc., directly connected to ISO standards. Some devices integrate AI algorithms that can automatically identify measurement features and optimize sampling paths, reducing measurement time by more than 30%.