5-Axis Machine Tool Head Layout to Avoid Rotary-Axis Singularities
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Solution Overview
Problem
Machine tools with two rotary feed axes and three linear feed axes experience significant tool posture changes and rapid speed increases at singularities, leading to shape deviations in the machined surface when attempting to avoid singularities through software adjustments.
Innovation Solution
A machine tool design that restricts the rotary feed range of the spindle head by inclining the C-axis pivot shaft, preventing the spindle axis from being parallel or coincident with the second axis, and using a stopper or limit switch to limit the A-axis rotational range, ensuring the spindle axis intersects the vertical direction at a predetermined angle, thus avoiding singularities through hardware modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If software is used to change the tool path at singularities, then singularities can be avoided, but the machined surface may have differences in shape from the desired shape
Solution Approach 1:
The patent replaces software-based tool path modification with a hardware-based solution by inclining the C-axis pivot shaft at a predetermined angle (e.g., 45 degrees) relative to the vertical direction. This mechanical reconfiguration prevents the spindle axis from becoming parallel to the C-axis rotation axis, thereby eliminating singularities through structural design rather than computational workarounds.
Solution Approach 2:
The patent changes the geometric parameter of the C-axis pivot shaft inclination angle from the conventional vertical orientation to a predetermined inclined angle. This parameter modification fundamentally alters the coordinate system transformation relationships, preventing the mathematical singularity condition from occurring while maintaining accurate tool path execution.
2Adaptability or versatility
If the spindle axis is allowed to become parallel or coincident with the C-axis, then the rotary feed range is maximized, but significant tool posture changes and rapid speed increases occur at singularities
Solution Approach 1:
The patent applies preliminary anti-action by pre-inclining the C-axis pivot shaft to prevent the singularity condition before it can occur. The structural design proactively eliminates the possibility of the spindle axis becoming parallel to the C-axis rotation axis, thereby preventing tool posture instability and speed spikes before they can manifest during machining operations.
3Reliability
If the rotary feed range is restricted by hardware, then singularities are avoided and smooth operation is achieved, but the device complexity increases
Solution Approach 1:
The patent merges the singularity prevention function into the existing C-axis pivot shaft structure by inclining it at a predetermined angle. Rather than adding a separate restriction mechanism, the structural modification combines the support function with the singularity avoidance function, minimizing additional complexity while ensuring reliable operation.
Data Source
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AI summary
A machine tool with two rotary feed shafts that control the position of a tool and three linear feed shafts for moving the position of a workpiece relative to the tool comprises: a main shaft on the tip of which the tool is mounted; a main shaft head for supporting the main shaft so as to be able to rotate around the rotational axis line of the main shaft; a main shaft head support for supporting the main shaft head so as to be able to rotate around a first axis line that extends perpendicular to the rotational axis line of the main shaft; a first rotary feed shaft device provided on the main shaft head support for rotary feeding of the main shaft head around the first axis line; a saddle that supports the main shaft head support so as to be able to rotate around a second axis line that is perpendicular to the first axis line and inclined with respect to the vertical direction; a second rotary feed shaft device provided on the saddle for rotary feeding of the main shaft head support around the second rotational axis line; and a restricting means for restricting the range of rotary feeding of the first rotary feed shaft device so that the main shaft rotational axis line does not become parallel or coincide with the second axis line.