Flexible Workpiece Fixturing for Wet Machining Accuracy
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Solution Overview
Problem
Existing flexible tooling systems for holding contoured workpieces in machining operations, particularly in wet environments like waterjet cutting, are unreliable due to operational failures and mispositioning issues, which can lead to workpieces being machined out of tolerance.
Innovation Solution
The development of configurable workpiece support assemblies that provide accurate and verifiable support using a combination of joints, slides, and pivots, allowing for up to six degrees of kinematic freedom and automated position verification, while being immune to water exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If active flexible tooling systems with motors and valves are used, then workpiece positioning capability is improved, but reliability deteriorates in wet environments
Solution Approach 1:
The patent removes all electronic components, motors, and valves from the fixture elements that contact the workpiece. Instead of using active actuators, the system employs passive mechanical joints (spherical joints, cylindrical joints, prismatic joints) that provide degrees of freedom without requiring power sources or control systems, thereby eliminating failure points in wet environments.
Solution Approach 2:
The patent replaces electro-mechanical actuation systems with pure mechanical joint systems. The fixture elements use combinations of spherical joints (providing 2 rotational degrees of freedom), cylindrical joints (providing 1 rotational and 1 translational degree of freedom), and prismatic joints (providing translational degrees of freedom) to achieve positioning without motors or valves.
2Adaptability or versatility
If workpiece engaging end effectors pivot freely for flexibility, then adaptability is improved, but position detection capability deteriorates
Solution Approach 1:
The patent introduces automated verification systems (spindle probes, coordinate measuring machines, laser scanning systems) as intermediaries to detect and verify the positions of fixture elements. These external measurement systems can accurately determine the positions of the passive fixture elements without requiring embedded sensors in each fixture component.
Solution Approach 2:
The system implements automated position verification through feedback from measurement systems. The fixture element positions are measured and verified automatically, providing feedback to ensure correct positioning even though the fixture elements themselves do not contain active positioning components or sensors.
Data Source
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AI summary
A system for supporting workpieces during machining. The system comprises one or more adjustable workpiece support assemblies and a robotic unit. Each workpiece support assembly comprises a pedestal and a rotatable fixture element. The robotic assembly comprises means of mobilizing and immobilizing each support assembly, so that the fixture element may be secured in a particular orientation. The robotic unit moves along a frame, and manipulates and fixes the position of the fixture elements to match the contour of a workpiece. Vacuum forces may be applied through the workpiece support assemblies to secure the workpiece against the fixture elements.