Multi-Region Thread Fastener for Cutting and Pull-Out Balance
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Solution Overview
Problem
Conventional screws face limitations in cutting efficiency, leading to increased resistance and material breakage during drilling, and are restricted in their applicability due to inadequate thread strength and accumulation of chips, which can cause workpieces to crack.
Innovation Solution
A versatile fastener with a shank featuring multiple thread convolutions of varying included angles and shapes in different regions, allowing efficient cutting and stable fastening across diverse materials by distributing cutting forces and accommodating chips effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the threads are made thinner to increase engagement area, then the pull-out resistance is improved, but the thread strength is reduced making them prone to breakage
Solution Approach 1:
The patent applies different thread profiles to different regions of the shank. The first region (near the tip) has threads with a first profile optimized for initial engagement and cutting, while the second region (near the head) has threads with a second profile optimized for pull-out resistance. This local differentiation allows each region to perform its specific function optimally without compromising the other.
Solution Approach 2:
The shank is divided into two distinct regions with different thread characteristics. The first region threads are designed with specific geometric parameters for cutting efficiency, while the second region threads are designed with different parameters for engagement and pull-out resistance. This segmentation resolves the contradiction by allowing thin threads in the first region for cutting while maintaining adequate thread strength in the second region for pull-out resistance.
2Ease of manufacture
If conventional uniform thread shapes are used, then the manufacturing is simple, but the cutting efficiency is limited and resistance increases
Solution Approach 1:
Different thread profiles are applied to different regions along the shank length. The first region threads have a profile optimized for cutting through workpiece material, while the second region threads have a profile optimized for engagement. This local quality differentiation improves cutting efficiency and reduces drilling resistance while maintaining reasonable manufacturing complexity.
Solution Approach 2:
The thread profile changes dynamically along the length of the shank rather than remaining uniform. This dynamic variation in thread geometry allows the screw to adapt its cutting and engagement characteristics to different stages of the drilling and fastening process, improving overall drilling efficiency.
3Reliability
If chips are accumulated during drilling, then the fastening engagement is increased, but the workpiece cracks due to excessive pressure
Solution Approach 1:
The shank is segmented into two regions with different thread characteristics. The first region threads are designed to cut and evacuate chips effectively during the drilling phase, preventing excessive chip accumulation that would cause cracking. The second region threads are designed to engage and hold the workpiece firmly after drilling is complete, providing reliable fastening engagement without the harmful effects of chip accumulation.
Data Source
AI summary
A versatile fastener includes a head, a shank, and thread convolutions including a first plurality of thread convolutions, a second plurality of thread convolutions, and a third plurality of thread convolutions. The shank is divided into a plurality of regions according to the pluralities of thread convolutions. Respective upper flanks of the thread convolutions each include an upper connecting section and an upper extension section, and respective lower flanks thereof each include a lower connecting section and a lower extension section, thereby forming three dual-section flank structures. The thread convolutions in at least two regions differ in their respective included angles defined with respect to a baseline which passes through a crest. Accordingly, the dual-section flank structures provide sufficient supporting forces while drilling, augment the cutting efficiency, and attain a stable fastening effect. The fastener is adapted to workpieces made of different materials for multiple applications.