Screw Design with Segmented Threads for Low Drilling Resistance
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Solution Overview
Problem
Existing screw designs face challenges in achieving optimal drilling and fastening efficiency due to improper dimensions of the trough angle and first apex angle, leading to limited cutting efficiency and insufficient bearing force, which results in either ineffective drilling or thread breakage under torque.
Innovation Solution
A screw design featuring first and second threads with distinct included angles and opening slots on the second threads, where the first included angle is smaller than the second, providing a reinforcing effect and accommodating debris, thereby reducing drilling resistance and enhancing cutting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the trough angle A is made small to improve cutting function, then the wave troughs can provide better auxiliary cutting, but the threads become weaker and thinner leading to insufficient bearing force and thread collapse
Solution Approach 1:
The thread structure is segmented into multiple components: first threads with a first included angle for bearing load, and second threads with a second included angle for cutting. This segmentation allows each thread type to be optimized for its specific function without compromising the other.
Solution Approach 2:
Different regions of the thread structure are given different properties: the first threads have a smaller included angle for strength, while the second threads have a larger included angle for cutting efficiency. This local differentiation resolves the contradiction between strength and cutting function.
2Strength
If the first apex angle α is made large to bear larger drilling torque, then the threads can withstand more rigid object drilling, but the cutting effect becomes inferior
Solution Approach 1:
The threading function is divided between first threads optimized for torque bearing (smaller included angle) and second threads optimized for cutting (larger included angle), eliminating the need to compromise between these conflicting requirements in a single thread structure.
Solution Approach 2:
The included angle parameter is varied between different thread types: first threads use a smaller included angle for strength, while second threads use a larger included angle for cutting, allowing optimal performance in both aspects.
3Ease of manufacture
If the threads are made thinner to improve cutting efficiency, then the auxiliary cutting performance improves, but the drilling resistance increases and drilling speed decreases
Solution Approach 1:
The cutting function is separated from the load-bearing function, with second threads providing thin, efficient cutting edges while first threads provide the structural strength needed for rapid drilling without excessive resistance.
Solution Approach 2:
The thread structure exhibits local quality variations where second threads have larger included angles for efficient material removal, while first threads maintain smaller included angles for structural integrity and reduced drilling resistance.
Data Source
Figure 1
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AI summary
A screw (3) with low drilling resistance comprises a head portion (31), a shank portion (32), a plurality of first threads (33), a drilling portion (34), and a plurality of second threads (35). Wherein, a plurality of opening slots (A) are correspondingly defined on the second threads (35) , and a first included angle (α) of the first threads (33) is smaller than a second included angle (α') of the second threads (35). Thereby, the opening slots (A) on the second threads (35) efficiently provide the first threads (33) with an auxiliary cutting effect and preferably offers a debris accommodating room. The first threads (33) including the smaller first included angle (α) favorably reinforce the bearing force of the second threads (35) including the larger second included angle (α'), thereby promoting the cutting effect of the screw and allowing a speedy screwing.