High-Speed Vacuum Cycling for Shearography Defect Inspection
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Solution Overview
Problem
Conventional vacuum systems for testing and inspection, such as those used in shearography, are limited by the need to return the test sample surface to atmospheric pressure between vacuum pressure applications, leading to inefficiencies and increased D-noise, which hampers defect detection in laminated structures.
Innovation Solution
A vacuum system utilizing solenoid pneumatic valves and a piston mechanism allows for rapid cycling of vacuum pressures without returning to atmospheric pressure, enabling high-frequency operation up to 1000 Hz, thereby improving defect detection by reducing D-noise and enhancing imaging consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional vacuum systems with mechanical pumps are used, then vacuum inspection can be performed, but the system is bulky, expensive, and cannot keep up with high-speed production lines
Solution Approach 1:
The patent replaces mechanical vacuum pumps with a vacuum chamber that oscillates between vacuum and atmospheric pressure states. This substitution eliminates bulky mechanical pumping equipment while enabling high-speed inspection by cycling the vacuum state rapidly using programmable logic controllers and solenoid valves, directly resolving the contradiction between inspection speed and system size.
Solution Approach 2:
The system employs periodic oscillation of the vacuum chamber between vacuum and atmospheric pressure states. By rapidly cycling the vacuum state at frequencies synchronized with production line speeds, the system achieves high-productivity inspection without requiring continuous mechanical pumping, thus improving productivity while reducing device complexity.
2Measurement precision
If vacuum pressure is maintained continuously for inspection, then accurate defect detection is achieved, but the inspection process is too slow for high-speed production lines
Solution Approach 1:
The patent implements periodic oscillation of the vacuum chamber between vacuum and atmospheric pressure states. During vacuum phases, defect detection occurs with high precision; during atmospheric phases, the system rapidly transitions to the next inspection cycle. This periodic action enables both accurate measurement and high productivity by synchronizing inspection with the oscillation frequency.
Solution Approach 2:
The system maintains continuous inspection capability by rapidly oscillating the vacuum state, ensuring that defect detection occurs during each vacuum phase without interruption to the production flow. The continuous cycling between vacuum and atmospheric states allows uninterrupted high-speed inspection while maintaining measurement precision.
3Ease of operation
If a vacuum seal is broken to access the workpiece, then the workpiece can be loaded and unloaded, but contaminants may enter the vacuum chamber
Solution Approach 1:
The patent uses periodic oscillation between vacuum and atmospheric pressure to control the vacuum seal state. The seal remains intact during vacuum phases for protection, and is deliberately broken only during controlled transitions to atmospheric pressure for workpiece access. This periodic control minimizes contaminant exposure while maintaining ease of operation.
Solution Approach 2:
The system employs an intermediary atmospheric pressure phase as a buffer between vacuum inspection phases and workpiece loading/unloading operations. This intermediary state allows safe access to the workpiece while preventing direct exposure of the vacuum chamber to contaminants, thus protecting against harmful factors while maintaining operational ease.
4Reliability
If mechanical pumps are used to maintain vacuum, then vacuum pressure can be sustained, but the system becomes expensive and difficult to synchronize with production line speeds
Solution Approach 1:
The patent replaces expensive mechanical vacuum pumps with a programmable logic controller system that manages solenoid valves to oscillate the vacuum chamber. This substitution maintains vacuum pressure stability through controlled cycling while dramatically reducing system cost and complexity, and enabling easy synchronization with production line speeds through programmable timing.
Solution Approach 2:
The system transitions from static continuous vacuum maintenance to dynamic oscillation between vacuum and atmospheric states. This dynamic approach allows the vacuum pressure to be sustained reliably during inspection phases while enabling rapid adaptation to different production line speeds through programmable oscillation frequencies, reducing both cost and complexity.
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 system enables efficient and rapid identification of defects in laminated structures by maintaining continuous vacuum pressure changes, reducing D-noise, and improving imaging consistency through high-frequency vacuum pressure cycling.
Implementation Method 1
a piston within the housing that oscillates to vary a volume of the vacuum chamber
Data Source
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AI summary
A vacuum system and method for inspecting a workpiece that can include use the vacuum system, where the vacuum system can include a housing defining at least a portion of a vacuum chamber, a piston within the housing that oscillates to vary a volume of the vacuum chamber, a first valve and a second valve in fluid communication with the vacuum chamber, and a hood in fluid communication with the second valve and the vacuum chamber. The vacuum system can include high-speed valves that enable vacuum system cycling and thus vacuum pressure cycling at a rapid frequency.