Oil Supply Pipe Thread Rolling to Prevent Cracks in Metal Pipes
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Solution Overview
Problem
The existing methods for forming threaded portions in metal pipes, particularly in enlarged diameter portions, often result in material thinning and cracking due to work hardening, especially when using forming rollers with overlapping ridge portions that simultaneously process the pipe.
Innovation Solution
A device and method employing two forming rollers with a first roller having a single ridge portion of less than one turn on its outer surface and a second roller with multiple ridge portions on its inner surface, where the rollers are positioned to prevent simultaneous contact and processing by the first roller's ridge portion, reducing material thinning and stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a forming roller with overlapping ridge portions is used to form threaded portions in metal pipes, then the threading process can be completed, but material thinning and cracking occur due to simultaneous processing by multiple ridge portions
Solution Approach 1:
The forming roller is divided into multiple ridge portions (first ridge portion and second ridge portion) that are positioned at different axial locations. This segmentation ensures that only one ridge portion contacts and processes the metal pipe at any given time, eliminating the simultaneous processing problem that causes material thinning and cracking while still achieving complete threading through the sequential action of multiple ridges.
2Manufacturing precision
If multiple ridge portions are provided on the forming roller to ensure complete threading, then the threading coverage is improved, but material thinning occurs at overlapping processing locations
Solution Approach 1:
The metal pipe is rotated in advance to bring different sections into contact with the forming roller sequentially. This preliminary rotation action ensures that each ridge portion processes a unique section of the pipe, preventing overlapping processing and the associated material thinning, while still achieving complete threading coverage through the sequential engagement of multiple ridges.
3Productivity
If the forming roller processes the metal pipe at multiple locations simultaneously, then the threading efficiency is improved, but work hardening increases leading to cracks
Solution Approach 1:
The forming process is made dynamic by rotating the metal pipe continuously during threading. This dynamic rotation ensures that different sections of the pipe engage with the forming roller at different times, preventing simultaneous processing and the associated work hardening that leads to cracks, while maintaining threading efficiency through continuous motion and sequential ridge engagement.
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 prevents cracks during the formation of threaded portions in metal pipes, even in enlarged diameter portions, by minimizing material thinning and strain, thereby enhancing the reliability of the oil supply pipe production process.
Implementation Method 1
pressing a ridge forming part of a forming roller which rotates in a direction opposite to that of the core metal against the metal pipe, and plastically deforming it to gradually form a screw part
Data Source
AI summary
A method for producing an oil supply pipe in which occurrence of cracks can be prevented at the time of forming a threaded portion in a metal pipe is provided. A method for producing an oil supply pipe in which a first rotating shaft 13, a first circumferential surface 14, and one first ridge portion 15 are provided, and in which, using a first forming roller 11 having the first ridge portion 15 spirally provided to have a length of less than one turn in a circumferential direction of the first circumferential surface 14 and a second forming roller 21 having a second rotating shaft 23, a second circumferential surface 24, and a second ridge portion 25 and the second ridge portion 25 spirally provided in a circumferential direction of the second circumferential surface 24, a threaded portion formed of a spiral protrusion is formed in an inner circumferential surface of a metal pipe by inserting the metal pipe to the second forming roller 21, disposing the first rotating shaft 13 and the second rotating shaft 23 so that they are parallel to each other, and pressing a material forming the metal pipe between the second ridge portions 25 using the first ridge portion 15 while rotating the first forming roller 11 and the second forming roller 21 is provided.