Screw Thread Segmentation for 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 trough and apex angles, leading to limited cutting efficiency and insufficient bearing force, which result in either ineffective drilling or weak fastening.
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
1Productivity
If the trough angle A is made small to improve cutting efficiency, then the wave troughs can provide better auxiliary cutting, but the threads become weaker and more prone to collapse
Solution Approach 1:
The thread structure is segmented into multiple independent threads with different functions. The first threads have a smaller included angle optimized for cutting efficiency, while the second threads have a larger included angle optimized for bearing force. This segmentation allows each thread to specialize in one function without compromising the other.
Solution Approach 2:
Different regions of the thread structure are given different properties. The first threads located at certain positions have a smaller included angle for cutting, while the second threads at other positions have a larger included angle for bearing. This local differentiation of thread properties resolves the contradiction between cutting efficiency and strength.
2Productivity
If the first included angle is made small to improve severing effect, then cutting efficiency increases, but the threads cannot bear large drilling torque on rigid objects
Solution Approach 1:
The thread system is divided into first threads with smaller included angles for severing and second threads with larger included angles for bearing torque. This segmentation enables the screw to achieve both good severing effect and high torque bearing capacity simultaneously through the combined action of different thread types.
Solution Approach 2:
The thread structure functions as a composite system where first threads and second threads with different geometric properties work together. The composite thread configuration combines the advantages of small included angles (cutting) and large included angles (strength) in a single fastening element.
3Strength
If the second included angle is made large to increase bearing force, then thread strength improves, but cutting effect becomes inferior
Solution Approach 1:
The thread structure is segmented into first threads optimized for cutting with smaller included angles and second threads optimized for bearing with larger included angles. This segmentation allows the second threads to provide superior bearing force while the first threads maintain effective cutting performance.
Solution Approach 2:
Different thread regions are assigned different included angles based on their functional requirements. The second threads with larger included angles are positioned to provide bearing force where needed, while first threads with smaller included angles handle the cutting function, achieving local optimization of both properties.
Data Source
AI summary
A screw with low drilling resistance comprises a head portion, a shank portion, a plurality of first threads, a drilling portion, and a plurality of second threads. Wherein, a plurality of opening slots are correspondingly defined on the second threads, and a first included angle of the first threads is smaller than a second included angle of the second threads. Thereby, the opening slots on the second threads efficiently provide the first threads with an auxiliary cutting effect and preferably offers a debris accommodating room. The first threads including the smaller first included angle favorably reinforce the bearing force of the second threads including the larger second included angle, thereby promoting the cutting effect of the screw and allowing a speedy screwing.