Screw Thread Interruption for Torque Reduction
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Solution Overview
Problem
Existing screws require additional manufacturing steps and generate processing waste due to the need for machining scraper grooves that penetrate the core, which increases production complexity and costs, while also not effectively reducing screwing-in torque without compromising extraction force.
Innovation Solution
A screw design featuring a scraping gap that only affects the thread, allowing for precise axial extent and production through forming or rolling processes, eliminating the need for machining and reducing torque without impacting pull-out force, using thread interruptions and rolling dies to create the scraping gap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If scraper grooves are produced by machining after screw production, then scraping function is achieved, but manufacturing complexity and production time increase due to additional operation
Solution Approach 1:
The scraping groove formation is merged with the thread rolling process. The rolling die incorporates features that simultaneously create both the thread and the scraping groove in a single operation, eliminating the need for separate machining steps and reducing manufacturing complexity
Solution Approach 2:
The scraping groove is pre-formed during the thread rolling process before the screw is completed. By incorporating the scraping groove creation into the initial forming stage, the need for subsequent machining operations is eliminated
2Ease of operation
If scraper grooves penetrate the core of the screw, then scraping function is achieved, but extraction force is compromised
Solution Approach 1:
The scraping groove is designed to affect only specific portions of the thread structure locally, rather than penetrating the entire core. The groove is positioned and dimensioned to provide scraping functionality at the thread edges while preserving the core integrity and pull-out strength
Solution Approach 2:
Instead of creating deep grooves that penetrate the core, the invention uses shallower grooves that extend only partially through the thread height. This partial action provides sufficient scraping function while maintaining the structural integrity needed for extraction force
3Ease of operation
If thread interruptions extend over the entire length of the screw shank, then screwing-in torque is reduced, but structural integrity is compromised
Solution Approach 1:
The thread interruption is localized to specific regions of the screw shank rather than extending over the entire length. This localized interruption reduces screwing-in torque in critical areas while preserving thread continuity and structural integrity in other regions
Solution Approach 2:
The thread interruption is segmented into discrete sections rather than being continuous. This segmentation allows torque reduction at specific locations while maintaining overall structural strength through uninterrupted thread sections
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Simplifies manufacturing, reduces production waste, and effectively lowers screwing-in torque without compromising extraction force, by precisely defining the scraping gap within the thread using rolling or forming processes.
Implementation Method 1
The rolling die (1) for the production of a screw (5) has thread-forming grooves (7) which are interrupted by surfaces (8) running transversely
Implementation Method 2
The scraping gap makes it possible for the sharp edges of the thread thus formed to facilitate screwing in the screw
Data Source
Figure 1
Figure 2~3
Figure 4~6
AI summary
The invention relates to a screw the front portion of the cylindrical shank of which has a screw thread that is interrupted. The interruption of the thread extends over not more than three turns and over an angle at circumference of approximately 15°. The interruption of the thread is produced by forming. The invention also relates to a method for the production of such a screw and to a flat die for carrying out the method.