Multi-Blade Holding Device for Precision Positioning
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Solution Overview
Problem
Conventional devices for holding a first mass relative to a second mass lack a combination of high stiffness in the vertical direction, flexibility in one horizontal direction, strength, stability under load, ease of adjustability, and the ability to maintain positional tolerances in three-dimensional space, particularly in precision systems like microlithography.
Innovation Solution
The use of multi-blade holding devices with interleaved blades that provide relative stiffness in orthogonal directions and flexibility in others, allowing for thermal expansion and precise positional adjustment through controlled compression and actuation, enabling the device to support masses with high accuracy and adaptability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If bolts and shims are used to support the plate holder relative to the plate table, then stability and vertical stiffness are provided, but flexibility in horizontal directions is lost and adjustability becomes difficult
Solution Approach 1:
The connection is segmented into multiple thin blades interleaved between the plate holder and plate table, replacing the single rigid bolt connection. This segmentation allows the structure to be stiff in the vertical direction while remaining flexible in horizontal directions, as each blade can independently deform to accommodate thermal expansion and adjustment needs.
Solution Approach 2:
The blade connection transitions from a static rigid connection (bolts) to a dynamic flexible connection. The interleaved blades can deform elastically in horizontal directions to accommodate thermal expansion, while maintaining vertical stiffness. The system adapts its stiffness characteristics based on the direction of applied forces.
2Stability of the object's composition
If bolts are tightened to provide high vertical stiffness, then stability is improved, but thermal stress relaxation capability is lost
Solution Approach 1:
The connection parameters are changed from rigid (bolts) to flexible (blades). The blades have appropriate thickness and material properties that allow them to deform under thermal stress, relaxing internal stresses while maintaining positioning stability. The flexibility parameter is tuned to accommodate expected thermal expansion without compromising vertical stiffness.
3Manufacturing precision
If multiple adjustment operations are performed with bolts and shims, then positioning accuracy is achieved, but time consumption and manual labor increase
Solution Approach 1:
The blade connection provides self-adjusting capabilities through its flexible structure. The interleaved blades automatically accommodate minor misalignments and thermal expansions without requiring manual intervention. The design eliminates the need for repeated shim adjustments by incorporating built-in compliance that absorbs positioning variations.
4Force
If conventional bolt connections are used, then vertical support is provided, but ease of adjustability is reduced
Solution Approach 1:
The single bolt connection is replaced by multiple segmented blades. This segmentation allows the connection to be easily adjusted by simply inserting or removing blades, or changing blade thickness, without requiring complex disassembly and reassembly operations. The modular blade structure significantly improves adjustability while maintaining support capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The multi-blade holding devices offer high stiffness in the vertical and one horizontal direction, flexibility in the remaining direction, and precise adjustability, effectively addressing the limitations of conventional holding devices by allowing for thermal expansion and maintaining positional accuracy in precision systems.
Implementation Method 1
Compression of the overlap region (using, for example, a clamp) usually produces a large frictional force in the overlap region. When not compressed or at most slightly compressed, the overlap region allows positional and/or angular adjustment of the interleaved sets of blades relative to each other.
Implementation Method 2
The relative flexibility can be exploited to allow, for example, thermal expansion of the first mass relative to the second mass as the device supports the first mass relative to the second mass.
Data Source
AI summary
An exemplary device includes first and second portions that are movably connected together by first and second sets, respectively, of multiple blades interleaved with each other at an overlap region. When the overlap region is compressed, displacement of the first and second portions relative to each other is prevented so as to provide relatively high stiffness in first and second orthogonal directions (e.g., z- and y-directions) and relatively low stiffness in a third orthogonal direction (e.g., x-direction). The device can be used in coordination with an actuator, wherein operation of the actuator and compression of the overlap region are automated.