Asymmetric Screw Thread Geometry for Chip Removal and Low Resistance
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Solution Overview
Problem
Existing screws with symmetric thread flanks face challenges in achieving optimal cutting capability, strength, and reducing screwing resistance during operations.
Innovation Solution
The screw design features asymmetric thread flanks with curved and straight sections, notches, and annular grooves to enhance cutting capability, strength, and reduce screwing resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If symmetric thread flanks are used, then manufacturing is simpler, but cutting capability and screwing resistance are insufficient
Solution Approach 1:
The patent applies asymmetry by designing the thread flanks with different configurations: the first flank has a first angle (70-75 degrees) while the second flank has a second angle (37-43 degrees). This asymmetric design allows the thread to cut into the workpiece more effectively on one side while maintaining structural integrity on the other, thereby improving cutting capability and reducing screwing resistance compared to symmetric designs.
Solution Approach 2:
The thread flank is segmented into multiple sections with different angles. The first flank section and second flank section are divided with distinct angular measurements, allowing each segment to perform a specific function during the screwing operation. This segmentation enables optimized cutting action while maintaining manufacturability.
2Productivity
If multiple flank sections with different angles are used, then cutting sharpness improves, but device complexity increases
Solution Approach 1:
The asymmetric thread design with two distinct flank angles creates different cutting surfaces that work together to achieve sharp cutting. The first angle (70-75 degrees) and second angle (37-43 degrees) are specifically chosen to optimize the cutting action while maintaining a relatively simple overall thread structure that can be manufactured with standard tools.
Data Source
AI summary
A screw includes thread convolutions spirally disposed around a shank. Each thread convolution has a thread crest formed along a junction of opposite upper and lower thread flanks. Notches are recessed into the thread crest of at least one thread convolution. Each lower thread flank includes a first lower flank section and a third lower flank section extended in a curved manner and includes a second lower flank section extending between the first and the third lower flank section in a non-curved manner. Accordingly, the third lower flank section cuts a workpiece sharply and allows cut chips to travel along the first lower flank section, the third lower flank section, and the notches, thereby attaining a quick removal and proper accumulation of chips. The second lower flank section provides supporting force, thereby increasing the strength of the thread convolutions, improving the cutting capability, and reducing the screwing resistance.