CMM Calibration Laser Head with Swivelable Beam
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Solution Overview
Problem
Current calibration methods for coordinate measuring machines (CMMs) are time-consuming, expensive, and require skilled operators due to the need for manual setup and monitoring of laser devices at multiple positions, leading to inefficiencies and increased costs.
Innovation Solution
A method utilizing a guided laser emitting unit and fixed retro-reflectors, where the laser beam is swivelable around two perpendicular axes, allowing for interferometric measurement of distance changes, enabling automated calibration without the need for external tracking systems, and using a set of retro-reflectors to gather machine positions and calculate error parameters, reducing the complexity and cost of the calibration process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional calibration methods using external laser trackers are used, then measurement precision can be achieved, but device complexity and cost increase significantly
Solution Approach 1:
The patent extracts the laser emitter from the external tracking system and integrates it directly into the tool carrier of the CMM. This eliminates the need for separate external laser trackers and their associated complex infrastructure, while maintaining calibration precision through the integrated laser interferometer system.
Solution Approach 2:
The tool carrier is designed to perform multiple functions: it carries both the measurement probe and the laser emitter for calibration. This multi-functionality reduces the need for separate calibration equipment and simplifies the overall system architecture while achieving accurate calibration across the measuring volume.
2Measurement precision
If manual setup and monitoring of laser devices is required, then calibration accuracy can be maintained, but productivity decreases due to time-consuming procedures
Solution Approach 1:
The system performs calibration automatically using the CMM's own integrated laser emitter and interferometer. The tool carrier autonomously carries out calibration measurements at multiple positions within the measuring volume without requiring external tracking equipment or manual intervention, thereby maintaining accuracy while significantly improving calibration speed and productivity.
3Measurement precision
If skilled operators are required for calibration, then measurement precision is ensured, but ease of operation deteriorates due to specialized training requirements
Solution Approach 1:
The integrated calibration system automates the calibration process completely, eliminating the need for operators to manually set up or monitor external laser trackers. The CMM performs self-calibration using its own laser emitter and interferometer, making the process accessible to operators without specialized training while maintaining calibration reliability through automated precision measurements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for precise, automated calibration of the entire measuring volume with reduced hardware costs and maintenance, eliminating the need for skilled operators, resulting in significant time and cost savings while maintaining high measurement precision.
Implementation Method 1
changes in distance are measurable interferometrically by means of the calibration laser head
Implementation Method 2
A set of retro-reflectors is arranged in fixed positions relative to and/or onto the base of the CMM
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Calibration method for a coordinate measuring machine (1), the coordinate measuring machine (1) comprising a drive mechanism for moving a tool carrier (15) relative to a base (11) for approaching a measurement point and comprising a calibration laser head (20) implemented so and attached to the tool carrier (15) so that a laser beam (25), which is emittable by the calibration laser head (20,21), is swivelable around at least two basically perpendicular axes (X, Y, Z) and changes in distance are measurable interferometrically by means of the calibration laser head (20). A set of retro-reflectors (16a-d) is arranged in fixed positions relative to and/or onto the base (11). The method comprises emitting and directing the laser beam (25) towards a first of the set of retro-reflectors (16a-d), whereby a measuring path (26) is defined by the orientation of the laser beam (25), moving the calibration laser head (20) along the measuring path (26) so that the laser beam (25) is kept directed towards the first retro-reflector (16a) according to the measuring path (26) and the reflected laser beam is continuously received at the calibration laser head (20), measuring the change in distance to the first retro-reflector (16a) at a plurality of measuring positions along the measuring path (26) and gathering a machine position for each of the plurality of measuring positions, the machine position relating to a position of the tool carrier (15) relative to the base (11).