External Pipe Thread Rolling for Non-Round Steel Pipes
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Solution Overview
Problem
Existing methods for rolling external pipe threads on steel pipes face challenges with non-roundness and large outer diameters, requiring complex apparatus and high precision cutting processes, which are not suitable for on-site installation in pipe network construction.
Innovation Solution
A method and apparatus using a rolling wheel group with odd-even different numbers of rolling wheels to pre-roll a steel pipe into a cylindrical or conical surface, followed by thread formation, allowing for standard outer diameters and non-roundness up to 100 um without die stamping or cutting, enhancing applicability and reducing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If axial punching or cutting of conical surface is used to reduce outer diameter, then the outer diameter can be reduced to meet rolling requirements, but the apparatus becomes complex and the steel pipe is damaged
Solution Approach 1:
The invention applies preliminary rolling action to the steel pipe before thread rolling, where the first rolling wheel group forms a pre-rolled surface (cylindrical, conical, or mixed) that prepares the pipe surface for subsequent thread formation. This preliminary action eliminates the need for complex axial punching or cutting apparatus while achieving the required outer diameter reduction and surface preparation in one integrated rolling process.
2Shape
If a tool is used to cut the perfect conical surface in the external pipe thread section, then the non-roundness problem can be solved, but high processing precision is required which cannot be easily achieved at construction sites
Solution Approach 1:
The rolling apparatus is designed to perform self-alignment during the rolling process. The rolling wheels automatically conform to the pipe's outer surface, and the pre-rolling action naturally corrects non-roundness without requiring high-precision pre-alignment of tools. The system adapts to the pipe's geometry rather than requiring the pipe to meet strict geometric tolerances before processing.
Solution Approach 2:
The invention changes the processing approach from cutting (which requires high precision) to rolling (which is more tolerant of variations). The rolling process uses pressure and deformation to form the conical surface and threads, allowing for greater flexibility in handling pipes with varying degrees of non-roundness and eliminating the need for high concentricity precision.
3Adaptability or versatility
If conventional steel pipe with standard outer diameter and non-roundness is used as blank, then material availability is improved, but the non-roundness greater than 100 um cannot be processed by traditional rolling methods
Solution Approach 1:
The first rolling wheel group performs a preliminary rolling action that forms a pre-rolled surface on the conventional steel pipe. This pre-rolling step corrects the non-roundness of pipes with outer diameter deviations up to 100 um by gradually deforming the pipe surface into a more circular cross-section, enabling subsequent thread rolling to proceed successfully on otherwise unprocessable conventional pipes.
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
The method effectively forms external pipe threads on conventional steel pipes with improved non-roundness control, reducing material damage and operational complexity, and achieving high pass rates of over 90% in thread formation, thus simplifying the rolling process and enhancing product quality.
Implementation Method 1
the first rolling wheel group rolls the outer surface of the hollow blank into a cylindrical surface, a conical surface, or a cylindrical conical mixing surface
Implementation Method 2
the second rolling wheel group rolls the outer surface of the hollow blank processed in the step 1 again, so as to form the external pipe thread by rolling
Data Source
AI summary
Provided is a method for performing an external pipe thread process on a hollow blank by at least twice rolling, wherein amount of rolling wheels in a rolling wheel set, used in any two back-to-back rolling processes in a processing sequence, are different in parity. Further provided are various roll-processing modules and corresponding rolling apparatuses, achieving the above processing method and having a simple structure, portability and practicality. A hollow blank is not liable to deform when performing an external pipe thread rolling process thereon, thereby improving a processing yield.