Machine Tool Scale Mounting for Thermal-Stable Position Measurement
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Solution Overview
Problem
Current position and length measuring devices on machine tools face challenges in maintaining accuracy due to thermal expansion, which affects the precision of position measurements and calibration, particularly in numerically controlled machine tools.
Innovation Solution
A position measuring device with a scale section indirectly attached to a machine tool component using a holding element with a lower thermal expansion coefficient, allowing the scale section to remain temperature-independent and unaffected by thermal deformations of the machine tool, thus enabling precise and temperature-independent position measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the scale section is directly attached to the machine tool component, then the mounting is simple and secure, but the measurement accuracy deteriorates due to thermal expansion of the machine tool component
Solution Approach 1:
The patent introduces holding elements as intermediary components between the scale section and the machine tool component. These holding elements serve as a mediator that isolates the scale section from thermal expansion of the machine tool, while still providing secure mounting. The holding elements are made from materials with low thermal expansion coefficients, allowing them to bridge the gap between the scale and the expanding component without transmitting thermal distortion.
Solution Approach 2:
The patent changes the material parameter (thermal expansion coefficient) of the mounting structure. By selecting holding element materials with significantly lower thermal expansion coefficients than the machine tool component (e.g., ceramic, glass, or specialized composites), the system maintains measurement accuracy despite temperature variations. This parameter change allows the mounting structure to remain dimensionally stable while the machine tool component expands.
2Measurement precision
If a holding element with low thermal expansion coefficient is used, then temperature independence of measurement is improved, but the ease of manufacture deteriorates due to material selection constraints
Solution Approach 1:
The patent employs composite materials for the holding elements that combine low thermal expansion properties with manufacturability. These composites may include ceramic-matrix composites, glass-fiber reinforced plastics, or other engineered materials that achieve the desired thermal stability while remaining workable through conventional manufacturing processes. The composite structure allows tailoring of both thermal and mechanical properties.
Solution Approach 2:
The patent modifies material parameters by selecting substances with specific thermal expansion coefficients that balance temperature independence with manufacturability. By carefully choosing materials whose thermal expansion is an order of magnitude lower than the machine tool component, the system achieves temperature compensation without requiring exotic or difficult-to-manufacture materials.
3Measurement precision
If the scale section is indirectly attached via holding element, then the impact of thermal expansion is reduced, but the device complexity increases due to additional components
Solution Approach 1:
The patent segments the mounting function into distinct components: the holding elements that provide thermal isolation and the scale section that performs measurement. This segmentation allows each component to be optimized for its specific function - the holding elements for thermal stability and the scale section for measurement accuracy - while maintaining a relatively simple overall structure.
Solution Approach 2:
The holding elements act as intermediary components that simplify the overall design by providing a standardized interface between the scale section and the machine tool. Rather than designing complex custom mounting structures, the patent uses these intermediary holding elements to achieve thermal isolation, reducing the need for additional compensation mechanisms or complex adjustment systems.
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 configuration enhances machining accuracy and calibration options by minimizing the impact of thermal expansion on the scale section, allowing for accurate position measurements without the need for additional temperature compensation, thereby improving the overall performance of machine tools at a lower cost.
Implementation Method 1
a material of the at least one holding element has a thermal expansion coefficient that is smaller than a thermal expansion coefficient of a material of the first component of the machine tool
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
The invention relates to a position measuring device for use on a machine tool (1), comprising: a scale section (10) which can be scanned by a scanner device (9), and which is for detecting a position of a first component (2) of the machine tool (1) in relation to a second component (7) of the machine tool (1) that moves in relation to the first component (2), when the scale section (10) is arranged on the first component (2) and the scanner device (9) is arranged on the second component (7); and at least one holding element (11 and/or 13) as a constituent part of an indirect securing means for indirectly securing the scale section (10) to the first component (2) of the machine tool (1), wherein a material of the at least one holding element (11 and/or 13) has a thermal expansion coefficient that is smaller than a thermal expansion coefficient of a material of the first component (2) of the machine tool (1).