Fuse Head Validation in Electronic Detonators
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Solution Overview
Problem
Existing methods for validating the welding of fuse heads in electronic detonators are ineffective when the detonator is assembled, as measuring leads cannot reach the fuse head inside the metallic shell, posing safety and economic risks.
Innovation Solution
A method involving a reference resistor, capacitors, and switching means to form RC circuits, where the charge times in both circuits are measured to determine if the fuse head is valid by comparing the second charge time to a defined range around the first charge time, allowing validation even after assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a multimeter is used to measure the resistance of the fuse head, then the welding validation can be performed, but the measurement must be performed before the detonator is assembled because measuring leads cannot reach the fuse head inside the metallic shell
Solution Approach 1:
The patent performs the resistance measurement of the fuse head before the detonator is assembled into its final configuration. By conducting the measurement in advance when the fuse head is still accessible, the system obtains validation data without requiring later access to the enclosed fuse head. This preliminary action resolves the contradiction by capturing the measurement opportunity before the structural changes make access impossible.
2Reliability
If the fuse head is welded to the electronic circuit during manufacturing, then the detonator can function, but incorrect welding may cause the fuse head to not initiate the explosive charge or to initiate at incorrect current thresholds
Solution Approach 1:
The patent implements a feedback mechanism by measuring the resistance of the fuse head and comparing it against expected values to validate the welding quality. The measurement system provides feedback about the welding state, allowing the system to detect incorrect welding that could lead to safety hazards. This feedback loop enables early detection and rejection of defective fuse head welds before they can cause safety incidents.
Solution Approach 2:
The validation measurement is performed as a preliminary check during or immediately after the welding process, before the detonator is finalized and deployed. By conducting the resistance measurement at this early stage, the system can identify welding defects and prevent defective units from proceeding to later stages, thereby eliminating safety risks associated with incorrect welding.
3Productivity
If the detonator is assembled with the electronic circuit inside the metallic shell loaded with explosive charge, then the detonator is complete, but validation of the fuse head becomes impossible as measuring leads cannot reach it
Solution Approach 1:
The patent resolves this contradiction by performing the fuse head validation measurement as a preliminary action before the detonator is fully assembled and sealed. The measurement is conducted when the fuse head is still accessible, allowing the system to complete both the validation and the assembly process without compromise to either productivity or measurement capability.
Solution Approach 2:
The patent uses the electronic circuit as an intermediary element that provides access to the fuse head for measurement purposes. By routing the measurement through the electronic circuit connections rather than requiring direct access to the fuse head, the system can perform validation even when the fuse head is enclosed within the metallic shell, thus maintaining measurement capability while achieving complete assembly.
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
This method securely validates the fuse head and welding, ensuring the detonator's integrity and safety by accurately determining the validity of the fuse head within the detonator's metallic shell, thereby reducing economic and safety risks.
Implementation Method 1
measuring at least once a first charge time t1, the first charge time t1 being the time required for the at least one capacitor to reach a specified charge value in the first RC circuit
Implementation Method 2
measuring at least once a second charge time t2, the second charge time t2 being the time required for the at least one capacitor in the second RC circuit to reach the same specified charge value
Data Source
AI summary
A method for the validation of a fuse head in an electronic detonator is disclosed, the method including measuring at least once a first charge time; activating a switching means to a second position to replace a reference resistor in an RC circuit with the fuse head; measuring at least once a second charge time; and determining the deviation of the second charge time from the first charge time.