Hexapod Mobile Machine Tool for Rigidity and Working Range
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Solution Overview
Problem
Mobile machine tools face a trade-off between maximizing working area, natural frequency, and rigidity, where higher stiffness and frequency typically reduce the working space and increase complexity and cost.
Innovation Solution
A mobile machine tool with a mechanically overdetermined framework that allows the machine bed head to be attached to the base body with high rigidity and adjustable positioning, using a hexapod structure with varying strut natural frequencies and pretensioning devices to maintain high damping and rigidity while increasing the working area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the machine bed head is attached to the base body with high stiffness and high natural frequency, then the rigidity is improved, but the working space is reduced
Solution Approach 1:
The framework is divided into multiple extensible struts that can be independently adjusted. This segmentation allows the machine bed head to be positioned at multiple discrete locations, effectively increasing the working space while maintaining rigidity through the structured framework design.
Solution Approach 2:
The framework incorporates extensible struts that can dynamically change length to adjust the position of the machine bed head. This dynamic capability allows the system to adapt its configuration for different working requirements while maintaining structural rigidity when positioned.
2Manufacturing precision
If the machine tool is designed with high rigidity and high natural frequency, then the manufacturing precision is improved, but the device complexity increases
Solution Approach 1:
The framework serves multiple functions: it provides structural support, enables position adjustment through extensible struts, and maintains rigidity for precise machining. This multi-functionality reduces the need for separate components, thereby managing complexity while achieving high manufacturing precision.
Solution Approach 2:
The natural frequencies of the struts are deliberately varied to differ by at least 3% (preferably at least 5%, particularly preferably at least 10%). This parameter variation optimizes the dynamic characteristics of the framework, providing sufficient damping across different excitation frequencies while maintaining a relatively simple structural design.
3Strength
If the framework is designed as a mechanically overdetermined structure, then the rigidity is improved, but the device complexity increases
Solution Approach 1:
The framework merges multiple struts into a coordinated system where the extension of one strut generates constraining forces on other struts. This merging creates a mechanically overdetermined structure that achieves high rigidity through the interconnected nature of the components rather than through individual component complexity.
Data Source
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AI summary
The invention relates to a mobile machine tool (10) comprising (a) a base body (12) with which the machine tool (10) stands on the ground (48), (b) a machine bed head (14) which cantilevers relative to the base body (12), and (c) an end effector (16) which is guided on the machine bed head (14) by means of a positioning system (18). According to the invention, the machine bed head (14) is attached to the base body (12) by means of a mechanically overdetermined frame (24).