Screw Thread Tip Protrusion Prevention via Cutting and Rolling
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Solution Overview
Problem
Existing methods of manufacturing screws result in protruding sections at the thread tip, which can lead to breakage and malfunction in applications, due to the pressing of side surfaces during rolling, causing cavities and potential structural weaknesses.
Innovation Solution
A method that involves cutting the thread to create a tapered shape with an underfill space and excess thickness portions, followed by rolling to plastically deform and guide these portions to the thread tip, preventing protrusions and maintaining the thread's basic shape, while reducing manufacturing resistance and enhancing surface roughness and lead accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If rolling is used to plastically deform the thread surface, then surface roughness and lead accuracy are improved, but protruding sections are formed at the thread tip section
Solution Approach 1:
The invention performs preliminary cutting to create an underfill space at the thread tip section before rolling. This preliminary action prepares the work material by removing excess material at the tip, preventing protruding sections from forming during the subsequent rolling process while still allowing the rolling to improve surface roughness and lead accuracy.
Solution Approach 2:
The invention divides the thread into two distinct sections: the thread body section with normal side surfaces and the thread tip section with narrowed width and underfill space. This segmentation allows different processing approaches for each section, enabling the rolling to be applied to the body section without causing protrusions at the tip section.
2Manufacturing precision
If rolling is used to plastically deform the thread surface, then surface roughness is improved, but protruding sections are formed at the thread tip section
Solution Approach 1:
The cutting process is performed before rolling to create the underfill space at the thread tip section. This preliminary removal of material ensures that when rolling subsequently plastically deforms the thread surface to improve roughness, there is no excess material at the tip to form protruding sections.
3Ease of manufacture
If cutting is performed before rolling, then manufacturing resistance of rolling is reduced, but additional manufacturing steps are required
Solution Approach 1:
The invention combines cutting and rolling into a sequential two-step process where cutting creates the thread form and underfill space, then rolling improves surface quality. While this adds a step, it reduces the complexity of each individual step by optimizing the cutting parameters to prepare for rolling, thereby reducing overall manufacturing resistance.
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
This approach effectively suppresses the formation of protruding sections at the thread tip, ensuring a robust and accurate screw structure with improved surface roughness and lead accuracy, and can be applied to both female and male screws, including multiple start screws, with optional heat treatment for increased surface hardness.
Implementation Method 1
the rolling plastically deforms the both side surfaces of the thread body section to cause the excess thickness portion to plastically flow toward both side surfaces of the thread tip section
Data Source
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AI summary
A method of machining a screw is provided that is capable of preventing formation of a protruding section at a thread tip section even when rolling is performed. A thread (2A) is formed by cutting on a cylindrical body inner circumferential surface (1a), and a surface of the thread (2A) is plastically deformed by rolling. Because of the cutting, a width (Lt) between both side surfaces (2ATs) of a thread tip section (2AT) is in a narrowed state as compared to a normal width (Lts) and is gradually narrowed toward a tip of the thread (2A) while a thread body section (2AM) has a width (Lm) between both side surfaces (2AMs) expanded as compared to a normal width (Lms) so that each of the side surfaces (2AMs) of the thread body section (2AM) is formed to bulge by an excess thickness portion (4) as compared to normal side surfaces (2AMss). The rolling plastically deforms the both side surfaces (2AMs) of the thread body section (2AM) to cause the excess thickness portion (4) to plastically flow toward each of the side surfaces (2ATs) of the thread tip section (2AT).