Self-stemming Cartridge for Borehole Blasting
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Solution Overview
Problem
Existing blasting techniques for cracking rock and concrete require a time-consuming and potentially dangerous stemming operation to retain explosive force, and existing self-stemming devices are either costly, ineffective, or bulky and difficult to use.
Innovation Solution
A self-stemming cartridge with an integrated accelerant and stemming mechanism within a single casing, where the stemming mechanism expands upon detonation to concentrate blast force and stem the borehole, eliminating the need for separate stemming devices and simplifying the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional stemming operation is used to retain explosive force, then blasting effectiveness is improved, but time consumption and safety risks increase
Solution Approach 1:
The patent combines the explosive charge and stemming mechanism into a single integrated cartridge. The stemming elements are pre-positioned around the explosive charge within the same casing, eliminating the need for separate stemming operations. When the explosive detonates, the stemming elements are automatically deployed to contain the blast force, achieving both time savings and maintained effectiveness.
Solution Approach 2:
The stemming elements are pre-positioned and pre-configured within the cartridge before use. The casing is designed with features that automatically deploy the stemming elements upon detonation, such as radial flutes or expansion mechanisms. This preliminary preparation eliminates the need for manual stemming operations after drilling, significantly reducing time consumption while ensuring proper stemming is achieved.
2Loss of time
If self-stemming devices are used to eliminate stemming operation, then time consumption is reduced, but cost and effectiveness deteriorate
Solution Approach 1:
The cartridge is designed to automatically perform the stemming function through self-contained mechanisms. Upon explosive detonation, the force generated automatically deploys the stemming elements to seal the borehole. The system serves itself by using the explosive force to both crack the rock and simultaneously position the stemming elements, eliminating the need for separate stemming operations while maintaining effectiveness.
Solution Approach 2:
The patent integrates the stemming mechanism directly with the explosive charge within a single cartridge structure. The stemming elements are positioned around the charge and activated by the same detonation event, ensuring that the stemming action is synchronized with the explosive force generation. This integration maintains stemming effectiveness while eliminating the time-consuming separate stemming operation.
3Loss of time
If self-stemming devices are used to eliminate stemming operation, then time consumption is reduced, but device complexity and difficulty of use increase
Solution Approach 1:
The patent combines all components (explosive charge, stemming elements, casing, and activation mechanism) into a single pre-assembled cartridge. This integration simplifies the user's task to merely inserting the complete cartridge into the drilled hole, eliminating the need to handle separate stemming materials or complex assembly procedures. The self-stemming function is achieved through the integrated design rather than requiring complex user operations.
Solution Approach 2:
The cartridge is designed as a disposable, single-use unit that is inserted into the borehole and then discarded after detonation. This approach simplifies operation because there is no need to retrieve, reuse, or maintain the cartridge components. The stemming elements are designed to be consumed or discarded with the cartridge after serving their purpose, eliminating complexity associated with reusable stemming devices.
4Strength
If metal casing is used for self-stemming device, then structural strength is improved, but blast force requirement and cost increase
Solution Approach 1:
The patent employs a thin-walled casing structure that is designed to rupture easily upon explosive detonation. The casing may be made of materials such as cardboard, thin plastic, or thin metal sheets with controlled weakness points. This thin-walled design allows the explosive force to be released efficiently to activate the stemming elements and crack the rock, rather than being absorbed or contained by a thick metal casing. The casing provides sufficient structural integrity for handling and insertion but deliberately fails to allow optimal blast force release.
Solution Approach 2:
The patent changes the structural parameters of the casing from thick and strong to thin and easily rupturable. The casing is designed with controlled wall thickness and incorporated weakness points that allow it to fail at predetermined locations during detonation. This parameter change ensures that minimal explosive force is required to rupture the casing and activate the stemming mechanism, making the device suitable for smaller explosive charges and reducing overall force requirements.
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 self-stemming cartridge effectively cracks hard materials by concentrating blast force, enhancing safety and productivity, and reducing collateral damage with a smaller, easily rupturable casing made of materials like cardboard or plastic, allowing for safe and efficient small-scale blasting.
Implementation Method 1
Upon detonation of the accelerant (22) within the cartridge (12)
Implementation Method 2
the self-stemming mechanism (21) stems the borehole (B)... forcing its way between the borehole (B) walls
Data Source
AI summary
A cylindrical casing (18) has first and second ends (33 and 31), the first end (33) being closed. The casing (18) encloses an accelerant (22) disposed adjacent the first end (33), at least one stemming mechanism (21), and a fuse (14 or 14′) extending from the accelerant (22) out of the second end (31) of the cylindrical casing (18). The cartridge (12) is made of a rupturable cylindrical casing (18) with accelerant (22) and self-stemming mechanism (22) inserted therein. A method of breaking hard (R) materials involves detonating a self-stemming cartridge (12) disposed in a borehole (B).