Coordinate-measurement machine precision stage with angled bearings
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Solution Overview
Problem
Existing coordinate-measuring machines (CMMs) face challenges in reducing the mass of movable components during platform movements, leading to inefficiencies in precision and accuracy.
Innovation Solution
The positioning system employs non-parallel surfaces and actuators that allow relative movement between bearings, reducing the mass moved during surface changes, and incorporates linear encoders for precise measurement, enabling 2D or 3D positioning with reduced complexity and increased accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional CMM design with large movable masses is used, then measurement capability is achieved, but measurement precision and accuracy deteriorate due to the mass being moved during platform movements
Solution Approach 1:
The movable platform is divided into multiple segments or components that can move independently. Instead of moving the entire heavy platform, only necessary lighter components are moved during measurement operations, thereby reducing the effective moving mass while maintaining measurement capability
Solution Approach 2:
Instead of moving the heavy platform to achieve measurement, the invention inverts the approach by keeping the platform stationary and moving lighter measurement components relative to it, or by using a fixed reference frame that eliminates the need to move large masses for positioning
2Manufacturing precision
If conventional positioning system with parallel surfaces is used, then structural simplicity is maintained, but precision deteriorates and system complexity increases
Solution Approach 1:
The invention employs non-parallel surfaces in the positioning system where at least one surface is angled or asymmetrically oriented relative to the platform. This asymmetric geometry enables precise positioning through mechanical constraints while reducing the need for complex active control systems, thereby improving manufacturing precision without proportionally increasing device complexity
Data Source
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AI summary
The invention relates to a positioning system for positioning and/or measuring a movable object, wherein the movable object (10) has an object position that is defined with respect to a at least two axes (X, Y) extending in at least two different directions. The movable object (10) has a first surface (SX) and a second surface (SY) having mutually different orientations. The first surface (SX) makes a first angle (α) with the first direction and the second surface (SY) makes a second angle (β) with the second direction. The positioning system comprises: i) a first bearing (BX) for establishing a first surface position of the first surface (SX) with respect to the first axis (X) and for allowing a movement of the movable object (10) in a first plane parallel to the first surface (SX) in at least the second direction; ii) a second bearing (BY) for establishing a second surface position of the second surface (SY) with respect to the second axis Y and for allowing a movement of the movable object (10) in a second plane parallel to the second surface (SY) in at least the second direction. The system further comprises respective actuators for establishing the respective positions. Such system may be further extended to three dimensions. The advantage of the positioning system is that during movement of the movable object less masses are moved. The positioning system is widely applicable. The invention further relates to a machine or a tool comprising such positioning system.