Lockable Multipod Machine Tool for Rigidity and Machining Range
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Solution Overview
Problem
Existing machine tools face limitations in rigidity, leading to low process forces and long machining times, with previous solutions offering small machining areas and low mobility due to hexapod drives and parallel kinematic systems.
Innovation Solution
A machine tool with a multipod drive having at least three drive elements and two supporting elements that can be locked, providing mechanical overdetermination to increase rigidity, allowing the tool head to be positioned and machined with higher precision and force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a hexapod drive with six legs is used to position the tool head, then the machining area can be enlarged, but the degree of rigidity decreases leading to lower process forces
Solution Approach 1:
The system dynamically transitions between mobile state (for positioning and large machining area) and braced state (for rigid machining). The supporting elements can be locked to create a braced state during machining operations, transforming the structure from a purely mobile parallel kinematic system to a statically determinate rigid structure when needed.
Solution Approach 2:
The hexapod drive is segmented into drive elements and supporting elements with independent functions. The supporting elements can be selectively locked to provide rigidity without interfering with the positioning function of the drive elements, allowing simultaneous optimization of both mobility and rigidity.
2Strength
If a parallel kinematic system with overdetermined drive is used to increase rigidity, then the degree of rigidity improves, but the installation space becomes limited
Solution Approach 1:
The system uses dynamic bracing where supporting elements are locked only during machining operations rather than being permanently fixed. This allows the machine tool to maintain high rigidity when needed while preserving mobility and reducing installation space requirements when the supporting elements are unlocked.
Solution Approach 2:
The mechanical properties of the system are changed by locking or unlocking the supporting elements. During positioning, the system operates in a mobile state with lower rigidity. During machining, the supporting elements are locked to increase rigidity, changing the structural parameters dynamically based on operational requirements.
3Strength
If the multipod drive is mechanically overdetermined by locking supporting elements during positioning, then the degree of rigidity increases, but the tool head frame cannot be moved
Solution Approach 1:
The system dynamically switches between mobile and braced states. During positioning operations, the supporting elements remain unlocked allowing free movement of the tool head frame. During machining operations, the supporting elements are locked to provide high rigidity. This dynamic state change resolves the contradiction between mobility and rigidity.
Solution Approach 2:
The supporting elements are locked in advance before machining operations begin, ensuring high rigidity is established before cutting forces are applied. The locking action is performed as a preliminary step after positioning is complete but before machining starts, optimizing both positioning accuracy and machining rigidity.
Data Source
AI summary
A machine tool includes with a tool head frame, a tool head, and an axis unit fixed to the tool head frame which fixes the tool head in a predefinable position. A movement device for moving the tool head frame includes a machine frame and a multipod drive which has at least three drive elements. The movement device is arranged in the flux of force between the machine frame and the machine tool frame, and has at least two supporting elements which can be brought into a locked state. The multipod drive is mechanically overdetermined by the supporting elements and the drive elements.