Two-Line Tapping Screw with Auxiliary Threads
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Solution Overview
Problem
Conventional tapping screws are not versatile enough to be used across different materials such as injection-molded objects and soft or hard metals due to differences in pitch and thread engagement, leading to material damage and increased assembly torque, which complicates manufacturing and increases costs.
Innovation Solution
A general-purpose tapping screw with a two-line screw structure featuring main and auxiliary threads with specific diameter and angle configurations, allowing for adaptable thread engagement across various materials by forming coupling holes of varying diameters based on material type, and optionally coating with a lubricant for smooth operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large pitch and conical shape are used for injection-molded objects, then material deformation is minimized and reuse is permitted, but application to short coupling structures is difficult and mold lifespan is reduced
Solution Approach 1:
The screw thread is segmented into two distinct lines: main threads with larger pitch for engagement in injection-molded objects, and auxiliary threads with smaller pitch for engagement in metallic objects. This segmentation allows a single screw design to adapt to different material types and coupling depth requirements without compromising material deformation protection or short structure compatibility.
2Strength
If a smaller pitch is used for soft or hard metallic objects, then thread engagement is increased and torque is maintained, but injection-molded objects are excessively deformed or damaged
Solution Approach 1:
Different portions of the screw thread have different pitch characteristics tailored to specific material types. The main threads provide large pitch for soft injection-molded materials to prevent deformation, while auxiliary threads provide small pitch for hard metallic materials to ensure sufficient engagement and torque. This local differentiation of thread properties resolves the contradiction between maintaining thread engagement strength and preventing material damage across different material types.
3Reliability
If separate tapping screws are used for different materials, then optimal performance for each material is achieved, but device complexity and manufacturing costs increase
Solution Approach 1:
The tapping screw is designed with universal applicability through dual thread lines that can engage with both injection-molded objects and metallic objects. The main threads and auxiliary threads are both functional, allowing the same screw to achieve optimal performance across different material types without requiring separate screw designs. This multi-functionality eliminates the need for material-specific screw classification while maintaining reliable performance.
Data Source
AI summary
The present invention provides a general use tapping screw, which is a two-line screw having a cylindrical body, and main threads and auxiliary threads which are formed on the outer circumferential surface of the body, wherein the outer diameter of the auxiliary threads is 92˜97% the outer diameter of the main threads, the angle of the front flank surfaces of the main threads and the auxiliary threads is in the range of 12±3 degrees, the angle of the rear flank surfaces of the main threads is in the range of 25±3 degrees, the angle of the rear flank surfaces of the auxiliary threads is in the range of 20±3 degrees, and intervals between a first pitch from the main thread to the auxiliary thread and a second pitch from the auxiliary thread to the next main threads have a difference in the range of ±10-20%.