Composite Fastener Structure to Prevent Nut Slip and Shear Fracture
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Solution Overview
Problem
Existing fastening structures face issues with weight increase due to metal materials, shear fracture, and nut slip caused by insufficient resistance to fastening torque, particularly in applications like vehicle floor panels and equipment covers.
Innovation Solution
A fastener design incorporating a metal nut part with an internal thread and a resin body, featuring a plate-like flange and erected parts to distribute force and torque, reducing shear fracture and nut slip, while minimizing weight through the use of metal and resin materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the whole fastener is made of metal to ensure strength, then the strength is improved, but the weight increases
Solution Approach 1:
The fastener combines metal nut parts with resin body parts to create a composite structure. The metal portions provide necessary strength for load-bearing and torque resistance, while the resin portions reduce overall weight. This composite approach resolves the contradiction by distributing material properties where needed rather than using a single material throughout.
Solution Approach 2:
Different parts of the fastener use different materials based on local requirements. The nut parts that require high strength and torque resistance are made of metal, while other structural parts that primarily need weight reduction use resin. This localized material selection optimizes both strength and weight simultaneously.
2Weight of stationary object
If a nut is mounted on an additive manufacturing member to integrate panels, then the weight is reduced, but shear fracture is likely to occur due to pull-out load
Solution Approach 1:
The fastener uses a composite structure where metal nut parts are integrated with resin body parts. The metal nut parts provide the necessary strength to resist shear forces and pull-out loads, while the resin body maintains the reduced weight benefit. This composite design prevents shear fracture while preserving weight reduction.
Solution Approach 2:
The fastener is segmented into distinct functional parts: metal nut parts for load-bearing and torque resistance, and resin body parts for structural support and weight reduction. This segmentation allows each part to be optimized for its specific function, preventing shear fracture in the nut while maintaining overall lightness.
3Weight of stationary object
If a nut is mounted on an additive manufacturing member, then the weight is reduced, but slip of the nut is likely to occur due to insufficient resistance against fastening torque
Solution Approach 1:
The metal nut parts provide high friction and grip characteristics necessary to resist fastening torque and prevent nut slip. The resin body parts maintain the reduced weight. The composite material combination ensures both reliability (no slip) and weight reduction are achieved simultaneously.
Solution Approach 2:
The nut parts that require high torque resistance are specifically made of metal with appropriate friction characteristics, while other parts use resin for weight reduction. This local quality differentiation ensures the nut does not slip under fastening torque while the overall fastener remains lightweight.
Data Source
AI summary
Provided are a fastener that can reduce the fastener weight, decrease body shear fracture, and avoid slip of a nut part and damage of the body due to the slip. The fastener includes: a metal nut part into which a bolt is screwed along an axis; and a resin body in which the nut part is inserted, the nut part includes an internal thread part into which the bolt is screwed from one end to another, a plate-like flange part connected to a side of the other end of the internal thread part and having a flange face perpendicular to the axis, and an erected part arranged at a position apart from the internal thread part radially about the axis and erected axially from the flange face, and the internal thread part and the erected part are inserted in the body.