Shell Casing Primer Pocket Inspection With Angled Laser Lines
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Solution Overview
Problem
Existing inspection systems for manufactured products, particularly ammunition shell casings, face challenges in accurately measuring the dimensions of recessed regions like primer pockets due to variations caused by chamfers or fillets, leading to inaccurate measurements.
Innovation Solution
An inspection system utilizing multiple lasers and cameras positioned at specific angles to project and capture laser lines on the interior surfaces of primer pockets, combined with a controller for calculating dimensions, and a sorting mechanism to direct casings based on tolerance ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single laser and camera are used to measure primer pocket dimensions, then the device complexity is low, but the measurement precision is insufficient due to variations caused by chamfers or fillets
Solution Approach 1:
The measurement system is segmented into multiple independent laser-camera units, each capturing data from a specific angle. This segmentation allows the system to collect comprehensive dimensional information from multiple perspectives, enabling accurate measurement of primer pocket dimensions while compensating for geometric variations like chamfers and fillets.
Solution Approach 2:
The system transitions from single-point or single-line measurement to multi-dimensional laser line projection. By projecting laser lines at multiple angles and capturing them with cameras positioned at different orientations, the system creates a three-dimensional measurement model that accurately represents the primer pocket geometry, eliminating measurement errors caused by chamfers and fillets.
2Measurement precision
If multiple lasers and cameras are positioned at specific angles to capture laser lines, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
Each laser-camera unit is designed to perform multiple functions: projecting measurement lines, capturing images from specific angles, and contributing to the overall three-dimensional reconstruction. The system uses multiple identical modular units that can be configured at different angles, making the system versatile and adaptable to various measurement requirements while maintaining consistent performance.
Solution Approach 2:
The system uses multiple copies of the laser-camera measurement unit, each positioned at specific angles. These copies capture identical types of data (laser line projections) from different perspectives, allowing the system to reconstruct the complete three-dimensional geometry of the primer pocket by combining the information from all copies.
3Measurement precision
If laser lines are projected at angles relative to primer pocket axes, then the accuracy of diameter measurement improves by minimizing chamfer/fillet impact, but the difficulty of detecting and measuring increases
Solution Approach 1:
The system changes the measurement parameters by projecting laser lines at specific angles relative to the primer pocket axes rather than perpendicular to the surface. This angular parameter change allows the laser lines to intersect the primer pocket diameter in a manner that minimizes the influence of chamfers and fillets, thereby improving measurement accuracy.
Solution Approach 2:
The system replaces traditional mechanical contact measurement methods with optical laser line projection and digital image capture. This substitution eliminates mechanical interference and allows for non-contact, high-precision measurement of the primer pocket dimensions, including accurate diameter measurement despite the presence of chamfers and fillets.
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
Enhances the accuracy of dimension estimation by minimizing the impact of chamfers or fillets and efficiently sorts casings into passing or rejected categories based on precise measurements.
Implementation Method 1
The first and second lasers are configured to project first and second laser lines onto interior surfaces of the shell casings within the primer pockets
Implementation Method 2
The first and second cameras are configured to capture a first set of images of the first and second laser lines on the interior surfaces of the shell casings within the primer pockets
Data Source
AI summary
An inspection system includes a conveyance system, at least one laser, at least one camera, and a controller. The conveyance system is configured to transport casings. Each casing has an exterior surface and a recessed region extending inward from the exterior surface. Each recessed region has a depth and a diameter. The at least one laser is configured to project first and second laser lines onto the recessed region of each casing along the corresponding diameter of each casing. The at least one camera is configured to capture a set of images of the first and second laser lines on the recessed region of each casing. The controller is programmed to estimate a magnitude of each diameter of each recessed region based on a corresponding set of images of the first and second laser lines on a corresponding recessed region of each casing.