Core Bolt With Frangible Drive for One-Sided Removable Fastening
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Solution Overview
Problem
Traditional fastener systems require a torque wrench for installation and cannot be removed after installation without drilling out the fastener head, posing challenges in confined spaces and limiting the flexibility of assembly and maintenance.
Innovation Solution
A core bolt with a recessed torquing feature and a frangible drive element that allows for installation without a torque wrench and enables easy removal by breaking off the drive element post-installation, facilitating one-sided removable bolts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional fastener systems with external wrenching features are used, then installation requires a torque wrench and the fastener breaks off flush with the head, but the fastener cannot be removed after installation without drilling out the fastener head
Solution Approach 1:
The fastener is divided into two functional segments: a reusable core bolt with internal threading and a disposable frangible drive element. The drive element is designed to break off after installation, leaving the core bolt intact for potential removal and reuse. This segmentation resolves the contradiction by making removal possible through the recessed torquing feature on the core bolt while maintaining simple installation through the frangible drive element.
Solution Approach 2:
The frangible drive element is designed as a disposable component that is intentionally made to break off after a single use. This disposable element carries the installation torque and then fractures, leaving the more valuable core bolt intact. This approach resolves the contradiction by sacrificing a low-cost component to enable the reuse of the higher-value fastener body.
2Productivity
If traditional fastener systems are used, then installation can be performed, but the fastener head must be drilled out for removal, increasing complexity and time for maintenance
Solution Approach 1:
By segmenting the fastener into a reusable core and disposable drive element, the invention enables simple removal through the recessed torquing feature without requiring drilling operations. This reduces removal process complexity from a multi-step drilling and extraction process to a simple rotational removal, resolving the contradiction between assembly speed and removal complexity.
Solution Approach 2:
The core bolt's recessed torquing feature is designed to accept standard torquing tools, allowing the fastener to be removed using the same type of tool used for installation. This self-service design resolves the contradiction by making the fastener its own tool for removal, eliminating the need for specialized drilling equipment and complex removal procedures.
3Strength
If traditional fastener systems are used, then structural integrity is maintained, but post-installation flushness shaving is required
Solution Approach 1:
The frangible drive element is designed to break off at a controlled location, extracting the protruding portion that would otherwise require post-installation shaving or trimming. This resolves the contradiction by eliminating the need for additional machining operations while maintaining the structural integrity of the joint through the core bolt's threaded engagement.
Data Source
Figure 1A~1C
Figure 2A~2C
Figure 3A~3B
AI summary
A core bolt of a fastener system for joining multiple substrates of a workpiece with a working side and a blind side is provided. The core bolt includes a head portion, a shank portion and a frangible drive element. The head portion includes a recessed torquing feature. The shank portion opposes the recessed torquing feature and extends from the head portion along a longitudinal axis to a distal end. The shank portion includes a threaded portion between the distal end and the head portion. The frangible drive element extends from recessed torquing feature and protrudes outward along the longitudinal axis to define a proximal end. A fastener system for joining multiple substrates of the workpiece includes a nut member and the core bolt. Methods for joining multiple substrates of a workpiece with a working side and a blind side are also provided.