Flexible Workpiece Fixturing With Robotic Position Verification
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Solution Overview
Problem
Existing universal fixtures for holding contoured workpieces in machining operations are unreliable, especially in wet environments, and lack accurate position verification, leading to potential machining errors due to mispositioning of actuators that cannot be visually detected.
Innovation Solution
A workpiece support assembly with a pedestal, support tube, and offset arm, featuring a fixture element with up to six degrees of kinematic freedom, allowing for precise immobilization and automated position verification using robotic units and sensors, eliminating the need for electronic components or motors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If motor driven screws or fluidic actuators are used to actuate workpiece engaging rods, then the system can achieve active positioning control, but the reliability deteriorates in wet environments such as waterjet cutting
Solution Approach 1:
The patent removes all electronic components, motors, and valves from the fixture system. The workpiece engaging rods are actuated purely mechanically through hand-operated knobs that rotate the rods to engage or disengage from workpiece features, eliminating the actuators that cause reliability problems in wet environments.
Solution Approach 2:
The fixture system uses self-contained mechanical elements where operators directly manipulate the workpiece engaging rods through hand knobs. The system serves itself through pure mechanical advantage without requiring external power sources or control systems, making it inherently reliable in wet environments.
2Adaptability or versatility
If workpiece engaging end effectors pivot freely to accommodate contoured workpieces, then the adaptability improves, but the ability to detect and verify position deteriorates
Solution Approach 1:
The patent introduces laser scanners and other automated scanning devices as intermediaries to detect the position of workpieces on the fixture. These external measurement systems can accurately verify the position of contoured workpieces even when the engaging rods are adjusted to various orientations, solving the measurement problem without restricting fixture adaptability.
3Manufacturing precision
If actuators are used to position workpiece engaging rods, then the positioning precision may be improved, but the complexity of the system increases due to potential malfunctions and verification requirements
Solution Approach 1:
The patent employs simple, inexpensive mechanical elements such as hand-operated knobs and rigid rods instead of complex, expensive actuators. These simple components have fewer failure modes and do not require maintenance or verification systems, reducing overall system complexity while maintaining sufficient positioning precision for the application.
Data Source
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.