Split Nut Assembly With Unequal Thread Pitches for Reusable Fastening
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Solution Overview
Problem
Current bolt-nuts with equal pitches face issues in detaching the nut after surface deformation or painting, leading to resource waste due to inability to reuse the nut, and they lack sufficient fastening force.
Innovation Solution
A bolt-nut design featuring a cylindrical nut body divided into sections, a cover body with tapered portions, and a spring mechanism allowing the nut to move and mesh with the bolt screws having unequal pitches, enabling easy detachment and maintaining a strong fastening force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the bolt and nut have equal pitches, then the nut can move along the bolt when being threaded, but the nut cannot be held by the bolt and is naturally loosened
Solution Approach 1:
The patent applies asymmetry by making the pitch of the bolt ridges different from the pitch of the nut ridges. Specifically, the bolt has a first pitch while the nut has a second pitch that is different from the first pitch. This asymmetric pitch design allows the nut to be held securely by the bolt while still enabling controlled movement during threading operations, resolving the contradiction between ease of operation and reliability.
2Ease of operation
If the ridges of the bolt and nut mesh with clearance, then the nut can be threaded onto the bolt, but the fastening force is insufficient and one nut loosening causes the other to loosen instantaneously
Solution Approach 1:
The asymmetric pitch design causes the ridges of the bolt and nut to contact at different positions rather than with uniform clearance. This creates multiple contact points that distribute and enhance the fastening force, preventing instantaneous loosening of both nuts when one is loosened, while still allowing the nut to be threaded onto the bolt.
Solution Approach 2:
The patent creates different local contact conditions between the bolt and nut ridges due to the pitch difference. Each ridge interface has unique contact characteristics, with some ridges providing primary fastening force while others provide secondary support. This local quality variation enhances overall fastening force while maintaining threading capability.
3Ease of manufacture
If the nut is painted after being fixed to the bolt, then the surface is covered with paint film, but the nut cannot be detached from the bolt for re-use
Solution Approach 1:
The asymmetric pitch design creates a self-loosening mechanism that allows the nut to be easily detached from the bolt even after painting. The pitch difference generates differential forces during any rotational movement that tend to loosen the nut, enabling detachment for re-use while still allowing the surface to be painted after initial fixation.
4Ease of manufacture
If the ridges are crushed due to painting or aged deterioration, then the bolt-nut structure is deformed, but with equal pitches the nut still cannot be detached
Solution Approach 1:
The asymmetric pitch design provides tolerance to ridge deformation caused by painting or aging. When ridges are crushed or deformed, the pitch difference ensures that not all contact points are affected equally, maintaining enough functional engagement to allow the nut to be loosened and detached for re-use, unlike equal pitch designs where deformation locks the nut in place.
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 design allows for easy re-use of the nut by facilitating its detachment from the bolt even when ridges are deformed, while maintaining a large fastening force due to unequal pitches, reducing waste and enhancing resource conservation.
Implementation Method 1
a spring that is accommodated together with the nut body in the cover body and is disposed on another end portion side of the cover body
Data Source
AI summary
A bolt-nut (1) includes: a nut body (4) in a substantially cylindrical shape; plural nut divided bodies (4a); a cover body (5) in a substantially cylindrical shape for covering the nut body (4); a cover-side tapered portion formed on an inner wall of the cover body (5); a nut-side tapered portion (4a) formed such that an outer diameter of an outer wall of the nut body (4) is reduced toward one end portion thereof so as to correspond to the cover-side tapered portion; a spring (6) that is accommodated together with the nut body (4) in the cover body (5); and a nut (2) that includes a lid body (7) covering the other end portion of the cover body (5). A bolt screw as a ridge of the bolt and a nut screw as a ridge of the nut body (4) have unequal pitches that are different from each other.