Machine Tool Rotary Axes Configuration for Precision Alignment
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Solution Overview
Problem
Existing machine tools face issues with alignment errors and reduced precision due to the use of long linear guide rails and stacked orthogonal axes, which introduce compliance, Abbe offset errors, and require costly and time-consuming alignment procedures.
Innovation Solution
A machine tool configuration using rotary axes mounted on a machine base, with a control arrangement to manage the orientation and position of supports relative to each other, eliminating the need for long linear axes and allowing for axisymmetric stiffness, reducing misalignment errors, and enabling precise control of cutting tools and workpieces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If long linear guide rails are used to enable contact between cutting tool and workpiece at any position, then the workpiece length coverage is improved, but the axis compliance increases and manufacturing precision deteriorates
Solution Approach 1:
The machine tool axis is divided into multiple modular segments (carriages) that can be positioned along the workpiece length. Each carriage carries a cutting tool and can be independently positioned, eliminating the need for a single long guide rail. This segmentation maintains stiffness while providing full length coverage through coordinated movement of multiple shorter modules.
Solution Approach 2:
The patent transitions from a single linear axis to a multi-dimensional configuration where multiple carriages move along the workpiece length and can be positioned at different locations. This dimensional approach allows coverage of long workpieces using multiple shorter, stiffer axis segments working in coordination rather than one long compliant axis.
2Adaptability or versatility
If orthogonal stacked linear axes are used to facilitate tool motion towards or away from workpiece, then the tool accessibility is improved, but the stiffness loop compliance increases and manufacturing precision deteriorates
Solution Approach 1:
The patent combines multiple cutting tools and their support carriages into a single integrated carriage assembly that moves together along the workpiece length. This merging eliminates the need for stacked orthogonal axes, maintaining tool accessibility while preserving stiffness by avoiding the compliance introduced by stacked linear guide rails.
Solution Approach 2:
Instead of stacking linear axes orthogonally to achieve tool accessibility, the patent inverts the approach by using a single linear axis with multiple positionable carriages. Each carriage can carry tools oriented in different directions, achieving the same accessibility goal without the stiffness-penalizing stacked configuration.
3Measurement precision
If on-axis position encoders are employed with stacked axes, then the position measurement capability is improved, but the Abbe offset errors increase and measurement precision deteriorates
Solution Approach 1:
The patent extracts the position measurement function from the complex stacked axis configuration and implements it on a single linear axis. By placing encoders on the simplified single-axis system rather than on multiple stacked axes, the Abbe offset errors are eliminated while position measurement capability is fully maintained.
4Length of moving object
If long linear guide rails are used, then the workpiece length coverage is improved, but the alignment complexity increases and ease of manufacture deteriorates
Solution Approach 1:
The machine tool is segmented into multiple independent carriage modules that can be manufactured separately and then assembled. Each module uses standard-length guide rails, avoiding the need to manufacture and align single extremely long rails. This segmentation dramatically simplifies manufacturing while maintaining full workpiece length coverage through coordinated module positioning.
Data Source
AI summary
A machine tool is provided which comprises a machine base (10), a first support (20,100) mounted on a first rotational machine axis on the base, and a second support (22,102) mounted on a second rotational machine axis on the base. The second rotational axis is parallel to and spaced laterally from the first rotational axis and carries a mount (38,112) moveable relative to the second support along a first linear machine axis orthogonal to the second rotational axis. A control arrangement is operable to control the orientation of the first support on the first rotational axis, and the orientation of the mount relative to the second rotational axis and its location along the linear axis, so as to govern the position and orientation of the first support and the mount relative to each other. Existing machine tools often use long linear guide rails and stacked orthogonal axes which introduce alignment and offset errors. The present invention avoids the need for and/or reduces the number of these structures in machine tools.