Tool Position Measurement Decoupling Thermal Displacement
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Solution Overview
Problem
Existing machine tools face challenges in accurately determining the position of a tool relative to a workpiece due to contamination exposure and thermal displacements, which affect machining accuracy and require interruptions during measurement processes.
Innovation Solution
The implementation of at least two length measuring systems to determine the position of a measuring point close to the tool relative to other measuring points, using a thread element that is deflected and guided to the measuring system, allowing for continuous and parallel measurement of the tool's position without being directly in the working area, thus decoupling the measurement from the structural elements and thermal influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the measuring system is arranged directly in the working area to measure tool position, then measurement can be performed, but the measuring system is exposed to contamination from machining and cooling lubricant
Solution Approach 1:
The measuring system is extracted from the working area and relocated to a safe position outside the contamination zone. The patent implements this by positioning the measuring system on a bridge structure that spans over the working area but remains physically separated from the machining zone, allowing measurement without direct exposure to chips and cooling lubricant.
Solution Approach 2:
A thread element acts as an intermediary between the tool carrier and the measuring system. The thread element transmits positional information from the tool carrier to the measuring system without requiring direct contact between the measuring system and the contaminated working area, enabling indirect measurement while protecting the measuring apparatus.
2Measurement precision
If the measuring system is arranged in the working area to determine tool position, then position data can be obtained, but the machining process must be interrupted for measurement
Solution Approach 1:
The measuring system is designed to operate continuously during the machining process without interruption. The thread element continuously tracks the tool carrier position, and the measuring system continuously processes positional data, enabling real-time measurement that does not require pausing the machining operations.
Solution Approach 2:
The patent replaces traditional mechanical contact-based measurement systems with an optical or electromagnetic measuring system that uses a thread element as a reference. This substitution allows non-contact or minimal-contact measurement that does not interfere with the machining process, maintaining continuous production.
3Manufacturing precision
If thermal displacements occur on the main spindle and measuring system, then machining accuracy is influenced, but the measuring system exposed to working area conditions cannot compensate for these displacements
Solution Approach 1:
The measuring system is extracted from the thermally affected working area and positioned in a thermally stable environment. By locating the measuring system on a bridge structure outside the direct path of machining heat generation, the system experiences minimal thermal displacement, enabling accurate reference measurements for compensation calculations.
Solution Approach 2:
The measuring system continuously monitors tool carrier position and provides feedback data that is used to calculate and compensate for thermal displacements. The measured positional data is compared with expected positions, and correction values are generated to maintain machining accuracy despite thermal effects on the spindle and structural elements.
Data Source
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AI summary
The invention relates to a machine tool (10) comprising a workpiece holder (12) and a tool holder (24) displaceable relative to the workpiece holder (12) and a machine part (27) by means of machine elements (18, 21, 23), in which a tool (25) is chucked for machining a workpiece (14) supported by the workpiece holder (12). At least two length measurement systems (30) are provided, directly detecting the linear distance formula (I) between a measurement point (S) near the tool on the workpiece holder, and each further measurement point (A, B) on the machine part.