Carbon Fiber Composite Threads With Zigzag Fiber Reinforcement

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Solution Overview

Problem

Existing methods for manufacturing carbon-fiber-reinforced composite bolts and nuts often result in threads that are prone to breaking under axial stress due to the division of carbon fibers during the threading process, leading to inadequate reinforcement and reduced strength.

Innovation Solution

A manufacturing method where multiple carbon fibers are embedded in a zigzag manner across the threads in a longitudinal cross-section, ensuring that adjacent threads are reinforced, using carbon-fiber-reinforced composite materials with thermosetting or thermoplastic matrices, and forming threads that can be carbonized or produced through other methods.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If threads are formed by lathing or machining the outer periphery of carbon-fiber-reinforced shaft material, then threads can be created on the shaft, but carbon fibers located within adjacent threads are divided and cut, resulting in inadequate thread reinforcement and reduced strength

Engineering Contradiction:
Improvethread formationVSAvoidthread strength
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The patent applies preliminary action by pre-embedding carbon fibers in a zigzag pattern along the thread path before thread formation. The fibers are positioned in advance to follow the thread contour, ensuring they remain intact and provide reinforcement during subsequent machining operations. This pre-positioning prevents fiber division and maintains thread strength.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent applies local quality by concentrating carbon fibers specifically within the thread regions where reinforcement is most needed, rather than uniform distribution throughout the entire shaft. The zigzag arrangement ensures fibers are locally concentrated along the thread path, providing targeted reinforcement exactly where axial stress is applied to threads.

Inventive Principle:
Principle #3Local quality

2Device complexity

If carbon fibers are arranged in a straight axial direction, then the structure is simple and manufacturing is easier, but the fibers do not follow the thread contour and cannot reinforce the threads under axial stress

Engineering Contradiction:
Improvefiber arrangementVSAvoidthread reinforcement
Core Design Contradiction:
Device complexityVSStrength

Solution Approach 1:

The patent applies curvature by arranging carbon fibers in a zigzag pattern that follows the helical contour of the threads, rather than straight axial alignment. This curved arrangement allows fibers to conform to the thread geometry, enabling them to effectively reinforce threads when axial stress is applied, while still maintaining relatively simple manufacturing processes.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Data Source

PatentEP3726073B1Member having screw thread made from carbon fiber-reinforced composite material
Publication Date: 2023.06.07 HARD LOCK IND CO LTD
  • EP3726073B1 patent drawingFigure 1
  • EP3726073B1 patent drawingFigure 2
  • EP3726073B1 patent drawingFigure 3~4

AI summary

A member with threads is provided that is made of a carbon-fiber-reinforced composite material with improved strength. Carbon fibers each extending in the axial direction across at least two threads appearing in a longitudinal cross section are embedded in the at least two threads in a zigzag manner along the surface shape of the at least two threads appearing in a longitudinal cross section. Preferably, the member is a nut, where the above-described structure is embedded in the threads of the female threadform of the nut, thereby providing a nut that is lightweight and exhibits improved strength.