Rock Cracker Cartridge with Plastic Inner Sleeve for Safe Electrical Ignition
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Solution Overview
Problem
Existing rock cracker cartridges lack electrical ignition capability and safe priming and unpriming processes, posing hazards during assembly and use, especially on work sites, and are not suitable for delay blasting applications.
Innovation Solution
A powder charged rock cracker cartridge design featuring a cylindrical outer sleeve with a main chamber filled with blasting powder, an acetal plastic insert unit comprising a plug and inner sleeve, and a priming chamber for electrical ignition, allowing for safe and easy assembly and delayed blasting without exposing hazardous materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a pierceable port design is used to allow detonator insertion, then the detonator can be placed in direct contact with the explosive, but the assembly becomes hazardous and the explosive may be exposed during unpriming
Solution Approach 1:
The cartridge is divided into separate functional zones: a sealed main chamber containing the explosive charge, and a separate priming chamber that houses the detonator. The inner sleeve acts as a barrier that prevents direct contact between the detonator and main explosive charge, eliminating the hazard of exposure during assembly and unpriming while still allowing the detonator to function effectively.
Solution Approach 2:
The inner sleeve is nested within the main chamber, creating a concentric structure where the priming chamber (inside the inner sleeve) is contained within the main explosive chamber. This nested design allows the detonator to be positioned centrally without compromising the integrity of the main charge, providing both safety and functional effectiveness.
2Device complexity
If manual rope ignition is used, then the system is simple, but electrical ignition and delay blasting cannot be employed
Solution Approach 1:
The sealed priming chamber design with the inner sleeve structure is universally compatible with different ignition methods. The chamber can accommodate both traditional fuse ignition and modern electrical detonators, allowing the same cartridge design to be used for immediate blasting, delay blasting, and various other applications without requiring structural modifications.
3Ease of operation
If the explosive charge is compressed or pressed aside to make room for the detonator, then the detonator can be inserted, but the assembly becomes hazardous and the explosive may be exposed
Solution Approach 1:
The inner sleeve serves as an intermediary structure between the detonator and the main explosive charge. It provides a dedicated priming chamber that houses the detonator and its ignition components without requiring compression or displacement of the main charge. This intermediary barrier ensures the explosive remains contained and undisturbed throughout assembly, handling, and unpriming operations.
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
Enables safe and efficient electrical ignition of the blasting powder charge with optional delay, reducing hazards during use and assembly, and meets lower explosive classification for safer transportation and storage.
Implementation Method 1
a blasting powder charge (6) in the outer sleeve between the end wall (3) and the insert unit (25)
Data Source
Figure 1~3
AI summary
A powder charged rock cracker cartridge (1) comprises asubstantially cylindrical outer sleeve (2) with an end wall in a first end (3); a plug (4) which, enclosing said outer sleeve, is inserted into and is secured in an opposite second end of the outer sleeve; a main chamber (5) in the outer sleeve (2) between said end wall and said plug, which main chamber is filled with a blasting powder charge (6); a substantially cylindrical inner sleeve (7), which is coaxial with the outer sleeve (2), is connected to said plug, and extends into the charge of blasting powder in the main chamber; and a central through hole (8) in said plug which communicates with the inner sleeve, which is closed in its inner end, which is inserted into the blasting powder charge. The hole in the plug and the inner sleeve in combination form a priming chamber (9) having a shape corresponding to the outer shape of a detonator (10), which can be trigged electrically and comprises an igniting powder charge. The inner sleeve has an inner wall (13) consisting of a plastic material. The thickness of the plastic wall and plastic material are selected such that the plastic wall in less than 25 ms (milliseconds) is penetrated by the pressure and the flame of fire which are formed when the detonator is ignited, thereby igniting the blasting powder charge.