Segmented Fastener Shank with Inclined Transition Parts
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Solution Overview
Problem
Existing fasteners face issues with thread breakage due to inefficient cutting and torque resistance, leading to incomplete drilling and loosening, as the angle of the threads affects both cutting efficiency and structural integrity.
Innovation Solution
The fastener design features first and second threads with radially converging surfaces and opening slots, where the second threads are affixed to the first, providing auxiliary cutting and debris accommodation, and the shank is segmented with inclined transition parts to enhance torsional resistance and tensile force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the trough angle of threads is increased to improve cutting efficiency, then the cutting efficiency is improved, but the thread structure becomes thinner and more prone to breakage
Solution Approach 1:
The patent divides the thread structure into two distinct types: first threads with a first trough angle optimized for cutting efficiency, and second threads with a second trough angle optimized for strength and torque bearing. This segmentation allows each thread type to specialize in its respective function without compromise.
Solution Approach 2:
Different regions of the fastener are assigned different thread characteristics. The first threads (with larger trough angles) are positioned where cutting action is needed, while the second threads (with smaller trough angles) are positioned where structural strength is required. This local differentiation resolves the contradiction between cutting efficiency and thread strength.
2Productivity
If the included angle of threads is decreased to improve cutting efficiency, then the cutting efficiency is improved, but the threads cannot bear larger screw-in torque and get broken easily
Solution Approach 1:
The patent segments the threading system into two functional groups: first threads with smaller included angles for efficient cutting, and second threads with larger included angles for bearing screw-in torque. This segmentation enables each thread type to optimize for its specific function.
Solution Approach 2:
The patent applies different included angles to different thread types based on their functional requirements. First threads have smaller included angles localized for cutting efficiency, while second threads have larger included angles localized for torque resistance, resolving the contradiction between cutting efficiency and torque bearing capacity.
3Strength
If the shank surface is made smooth to reduce twisting, then the torsional resistance is improved, but the drilling efficiency is reduced
Solution Approach 1:
The patent segments the shank surface into different zones: a drilling portion with a rougher surface to enhance drilling efficiency through better chip evacuation and reduced heat buildup, and a threading portion with a smoother surface to reduce twisting and enhance torsional resistance. This spatial segmentation resolves the contradiction between drilling efficiency and torsional resistance.
Data Source
Figure 1
Figure 2~3
Figure 4~4A
AI summary
A fastener (3) includes a shank (31), a head (32) connected thereto, a drilling portion (33) opposite to the head (32) and a plurality of first threads (34) and second threads (35) spirally disposed on the shank (31). The second threads (35) are affixed to the first threads (34) and provided with a plurality of opening slots (354) defined thereon. The opening slots (354) expose portions of the first threads (34) therethrough. The first threads (34) divide the shank (31) into a plurality of shank segments (311), each of which has a base part (3111) and a transition part (3112) extending outward from the base part (3111) to be inclined by 5 to 10 degrees. The opening slots (354) formed on the second threads (35) provide an auxiliary cutting effect and accommodate cut debris. The first threads (34) reinforce the bearing and drilling force of the second threads (35). The inclined transition part (3112) helps increase the ability of resisting the driving torsion and attain an anti-loosening force, thereby increasing the fastening effect.