Shaped Charge Axial Wedge Fastening
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Solution Overview
Problem
Existing shaped charges face challenges in securely joining the explosive charge and casing, particularly for smaller diameters, due to the complexity of radial screw tightening, which can damage the coating and require specific tools, making it difficult to achieve consistent torque.
Innovation Solution
A shaped charge design featuring a ring with radially moving wedges secured by screws, where the screws' axial displacement causes radial wedges to contact the casing, facilitated by a conical profile for axial retention and a spring washer for compression, allowing for simple and reliable assembly without damaging the coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If radial screw tightening is used to join the explosive charge and casing, then secure attachment is achieved, but the coating is damaged and assembly complexity increases
Solution Approach 1:
The patent introduces an intermediary mechanism (the conical wedge system) between the screw and the coating. The screw acts axially on the wedge, which then converts this axial force into radial force against the casing, eliminating direct contact between tightening tools and the coating surface.
Solution Approach 2:
The patent changes the dimension of force application from radial (direct radial tightening) to axial (axial screw movement). By moving the screw axially, the force is transmitted through the conical wedge to create radial clamping force, thus protecting the coating while achieving secure attachment.
2Strength
If radial screw tightening is used to join the explosive charge and casing, then secure attachment is achieved, but assembly difficulty increases for small diameters
Solution Approach 1:
The patent changes the dimension of force application from radial to axial. The screw moves axially rather than radially, which simplifies the assembly operation especially for small diameter charges where radial access and tool application are difficult.
Solution Approach 2:
Instead of applying radial tightening force directly, the patent inverts the approach by using axial screw movement to generate radial clamping force through the conical wedge geometry, making assembly easier and more consistent.
3Strength
If specific tightening tools are used for radial tightening, then attachment is achieved, but device complexity increases
Solution Approach 1:
The patent creates a universal tightening mechanism where a standard axial screw can be used regardless of the specific application. The conical wedge system serves as a multi-functional element that converts axial screw movement into radial clamping force, eliminating the need for specialized radial tightening tools.
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 design ensures secure and reliable attachment of the explosive charge to the casing, accommodating various diameters, while minimizing coating damage and simplifying assembly, with the compressible material in the annular space providing shock protection and expansion compensation.
Implementation Method 1
The screw comprises a conical end cooperating with a conical bore of said wedges, an axial displacement of the screw during its screwing leading to a radial displacement of said wedges
Implementation Method 2
Patent FR2669721 also proposes means making it possible to compensate for thermal expansion between the explosive charge and the casing. These means comprise an annular filling of a compressible material (for example a polysiloxane elastomer) which is interposed between the casing of the formed charge and the explosive charge
Implementation Method 3
The load may include a spring washer interposed between the coating and the abutment surface of the ring
Data Source
Figure 1
Figure 2~3b
AI summary
The subject-matter of the invention is a shaped charge (1) comprising an explosive charge (2) arranged in a casing (3), a coating (4) applied to the charge (2), and means for securing the casing (3) and the charge (2) with the coating (4). Said securing means comprise a ring (5) having an abutment surface for the coating and at least two spacers (6) each covering an angular section and moving radially through the action of a clamping means (11), in order to engage with an internal bearing surface of the casing (3). According to the invention, the axis of the internal thread of the clamping screw(s) (11) is parallel with the axis (7) of the casing, and the spacer (6) is positioned axially with respect to the ring by at least one radial axis (8) allowing the sliding function thereof.