Three-Axis Milling Head Layout for Fast 3D Tool Positioning
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Solution Overview
Problem
Existing two-axis milling head units face limitations in angular positioning, requiring significant repositioning and limited pivoting ranges, which reduces processing speed and complicates electronic orientation error compensation, making them less suitable for producing large and complex 3D parts with high precision.
Innovation Solution
A three-axis milling head unit with orthogonal and inclined rotation axes (C, B, and A) allows for independent and simultaneous control of each axis, enabling larger pivoting angles and precise positioning, and facilitating electronic orientation error compensation through precise calibration and compensation mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a two-axis milling head unit with C and A axes is used, then the structure is simple, but the processing speed is reduced due to the pole problem requiring significant repositioning
Solution Approach 1:
The patent introduces a third rotation axis (B-axis) inclined at an angle between 0° and 90° relative to the C-axis, transforming the two-axis system into a three-axis system. This dimensional addition eliminates the pole problem by providing an alternative rotation path, allowing the milling tool to reach any position within a larger angular range without requiring complete revolutions or significant repositioning, thereby maintaining simplicity while dramatically improving processing speed
2Productivity
If a two-axis milling head unit with C and B axes is used, then the pole problem is eliminated, but electronic orientation error compensation becomes difficult
Solution Approach 1:
The patent segments the error compensation function into three independent rotation axes (C-axis, B-axis, and A-axis), each with its own drive device and control system. This segmentation allows for precise independent calibration and compensation of orientation errors on each axis, making electronic orientation error compensation feasible and effective by distributing the compensation task across multiple controllable degrees of freedom rather than requiring complex inter-axis coordination
3Device complexity
If the C-axis rotation range is limited to +/- 180°, then the cable and hose routing is simplified, but the milling tool must be turned back by considerable angles reducing efficiency
Solution Approach 1:
The patent adds an inclined B-axis rotation that provides an alternative path for positioning the milling tool. When the C-axis approaches its +/- 180° limit, the system can utilize B-axis rotation to achieve the desired tool orientation without requiring the C-axis to complete a full revolution or turn back by considerable angles. This dimensional addition maintains the simplicity of cable routing while eliminating time-consuming repositioning movements
Data Source
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Figure 4a~4c
AI summary
A three-axis tool head unit (1) for a machine tool spindle (90), in particular a three-axis milling head unit, is disclosed, comprising three components (16, 17, 18) that are rotatable or pivotable relative to one another about independent axes (A, B, C). A first head section (16) is rotatably mounted on a support arm (14) about a first axis (C) with respect to the support arm (14). A second head section (17) is rotatably mounted on the first head section (16) about a second axis (B) with respect to the first head section (16). A spindle assembly (18) is rotatably mounted on the second head section (17) about a third axis (A) with respect to the second head section (17). The third axis of rotation (A) is orthogonal to the first and second axes of rotation (C, B), while the first and second axes of rotation (C, B) are inclined to each other at an angle between 30° and 60°.Each of the three rotary axes (C, B, A) is assigned an individual drive unit (19, 21, 22) for driving and controlling the rotation of the component (16, 17, 18) about its respective axis (C, B, A). The three-axis tool head unit (1) offers large axis swivel ranges with a small interference contour and enables fast and precise positioning of a machine tool spindle (90) into the required machining position. A machine tool (1), in particular a milling machine, with such a three-axis tool head unit (1) is also disclosed.