External Pipe Thread Rolling with Sinusoidal Pre-Forming
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Solution Overview
Problem
Existing methods for rolling external pipe threads on steel pipes face challenges with large outer diameters and non-roundness, leading to complex apparatus requirements, material damage, and high precision needs, which are difficult to achieve, especially in construction site settings, and often result in failure during the process.
Innovation Solution
A method and apparatus that use a pre-rolling process with a greater number of rolling wheels in the first group compared to the second, forming a sinusoidal thread profile that matches the external pipe thread, allowing for the rolling of external pipe threads on conventional steel pipes without prior die stamping or cutting, reducing non-roundness and preserving the zinc layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional steel pipe with standard outer diameter and non-roundness is used as blank, then material availability and cost are improved, but the rolling process cannot be completed successfully due to non-roundness exceeding equipment capability
Solution Approach 1:
The patent applies preliminary action by introducing a pre-rolling process before the main rolling operation. The pre-rolling step prepares the steel pipe blank by initially forming the thread profile and reducing non-roundness, thereby creating suitable conditions for the subsequent rolling process to succeed on conventional steel pipes
Solution Approach 2:
The patent segments the rolling process into two distinct stages: pre-rolling and main rolling. The pre-rolling uses a first rolling wheel group to initially form the thread and reduce non-roundness, while the main rolling uses a second rolling wheel group to complete the thread formation, allowing each stage to be optimized independently
2Shape
If axial punching or cutting of conical surface is performed to reduce diameter, then outer diameter problem is solved, but apparatus complexity and material damage increase
Solution Approach 1:
The patent applies parameter changes by using rolling wheels with specifically designed thread profiles and angles that enable diameter reduction through the rolling process itself, rather than through axial punching or cutting. The rolling wheels are configured with parameters that allow them to gradually reduce the outer diameter while forming the thread profile
3Shape
If axial punching or cutting of conical surface is performed, then diameter reduction is achieved, but zinc layer on galvanized steel pipe surface is destroyed
Solution Approach 1:
The patent replaces the mechanical cutting or punching system with a rolling system. Instead of using cutting tools that remove material and damage the zinc layer, the rolling wheels apply controlled pressure to deform and form the thread profile, substituting a forming mechanism for a material removal mechanism
4Manufacturing precision
If high processing precision with high concentricity between workpiece and tool is required, then conical surface quality is improved, but ease of operation and applicability at construction site deteriorate
Solution Approach 1:
The patent applies self-service by designing the rolling apparatus to automatically self-align with the steel pipe blank during the rolling process. The apparatus includes self-centering mechanisms that eliminate the need for high-precision manual alignment, allowing the equipment to achieve proper concentricity automatically even in field conditions at construction sites
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 enables the rolling of external pipe threads on standard steel pipes with improved surface roughness, hardness, and reduced non-roundness, enhancing the applicability and quality of the process while avoiding material damage and complex apparatus requirements.
Implementation Method 1
a rolling method which comprises: performing pre-rolling on an outer surface of a hollow blank by using a rolling wheel with a pre-formed pipe thread
Implementation Method 2
performing pre-rolling on an outer surface of a hollow blank by using a rolling wheel with a pre-formed pipe thread
Data Source
Figure 1a~1c
Figure 2a~2b
Figure 3a~3c
AI summary
Provided is a method for performing an external pipe thread process on a hollow blank by at least twice rolling: firstly, the first rolling wheel group rolls the outer surface of the hollow blank into a threaded cylindrical surface or a threaded conical surface or a threaded cylindrical conical mixing surface, and secondly, the second rolling wheel group rolls again for the outer surface of the hollow blank which has processed in step1, and rolling to form an external pipe thread; wherein the number of rolling wheels in a rolling wheel group, used in any two back-to-back rolling processes in a processing sequence, are different in parity. Further provided are various rolling head, module, apparatuses and production line for pipe thread, achieving the above processing method and having a simple structure, portability and practicality. When preforming an external pipe thread rolling process of the hollow blank, thereby improving a processing yield; in addition, the invention also provides a threaded cylindrical surface or a threaded conical surface or threaded cylindrical conical mixing surface products by the first rolling wheel group.