Decoupled Measuring Frame for Machine Tool Positioning
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Solution Overview
Problem
Machine tools face inaccuracies due to mechanical and thermal deformations that cannot be fully detected by integrated position measuring systems, leading to errors in workpiece dimensions and position tolerances.
Innovation Solution
A machine tool design featuring a stationary frame, a machining head with a pivoting unit, and a thermally and mechanically decoupled measuring frame that is integrated with flexible elements, equipped with first and second position measuring systems to determine the spatial position of the machining head and workpiece positioning device relative to the measuring frame, ensuring precise positioning without detours and minimizing errors from thermal and mechanical influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a position measuring system is integrated into the machine tool, then the position of the machining head and workpiece can be determined, but mechanical and thermal deformations cause measurement errors that cannot be fully detected or compensated
Solution Approach 1:
A measuring frame serves as an intermediary reference structure that is thermally and mechanically decoupled from the machine tool components. The measuring frame with its rectangular configuration provides a stable reference system that does not deform with the machine tool, allowing accurate position measurements to be taken relative to this independent reference frame rather than to deforming machine components
Solution Approach 2:
The patent replaces the conventional mechanical position measuring system that is rigidly connected to the machine tool with an optical measurement system that uses the decoupled measuring frame as reference. This substitution allows position determination to be independent of mechanical deformations in the machine tool structure
2Device complexity
If the measuring frame is rigidly connected to the pivoting unit, then the structure is simple, but thermal and mechanical influences cause deformations that affect measurement accuracy
Solution Approach 1:
The measuring frame is extracted from the rigid mechanical structure of the pivoting unit and given thermal and mechanical independence. By decoupling the measuring frame from the pivoting unit through flexible connections, the measuring frame can maintain its geometric stability while still being positioned within the machine tool structure
Solution Approach 2:
The patent changes the thermal and mechanical parameters of the connection between the measuring frame and the pivoting unit by introducing flexible elements. This allows the measuring frame to have different thermal expansion characteristics and mechanical compliance compared to the rigid pivoting unit, preventing deformation transmission
3Measurement precision
If position measuring systems are arranged on the machine frame and workpiece table, then position determination is possible, but the table's travel range that can be recorded is limited by the scale's spatial extent
Solution Approach 1:
The patent extends the measurement capability to five spatial degrees of freedom by arranging measuring systems in multiple dimensions. The measuring frame provides a reference system that enables position determination not only in the traditional table movement directions but also in the pivoting unit's rotation axes, effectively adding measurement dimensions beyond the limited linear scale range
Data Source
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AI summary
Machine tool comprising: - a stationary machine frame (1), - a machining head (2) which can be positioned along three orthogonally oriented translation axes (x, y, z) relative to the machine frame (1) and which includes a motor-driven tool (2.1), and - a swivel unit (3) which can be swivelled about a horizontal swivel axis (S) relative to the machine frame (1) and which includes a workpiece positioning device (4) by means of which a workpiece (100) can be rotated about a rotary axis (D) oriented perpendicular to the swivel axis (S), characterized in that a measuring frame (6) is associated with the swivel unit (3), which is swivelable with the swivel unit (3) and is thermally and/or mechanically decoupled from the swivel unit (3) and on which components of a first and second position measuring system are arranged.- wherein further components of the first position measuring system are arranged on the machining head (2) and further components of the second position measuring system are arranged on the workpiece positioning device (4) and - wherein the spatial position of the machining head (2) is determined in relation to the measuring frame (6) via the first position measuring system and - wherein the spatial position of the workpiece positioning device (4) is determined in relation to the measuring frame (6) via the second position measuring system.