Pipe Thread Rolling Head With Two-Stage Preforming for Non-Round Pipes
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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, requiring complex apparatus and high precision processing, which can damage the pipe and destroy zinc layers, necessitating a more applicable and efficient technology.
Innovation Solution
A method using a rolling head with a first and second rolling wheel group, where the first group pre-forms a threaded cylindrical or conical surface, and the second group forms the external pipe thread, without the need for die stamping or cutting, using odd-even different numbers of rolling wheels to achieve the desired thread profile and reduce non-roundness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If axial punching or cutting of conical surface is used to reduce outer diameter, then the outer diameter is reduced to meet rolling requirements, but the apparatus becomes complex and the steel pipe is damaged
Solution Approach 1:
The patent applies preliminary action by pre-forming a threaded cylindrical or conical surface on the steel pipe before the actual thread rolling process. This pre-formed surface provides the necessary geometric conditions for successful thread rolling, eliminating the need for complex axial punching or cutting operations to reduce outer diameter. The pre-forming step is performed using simple rolling wheels that create the required surface geometry without damaging the pipe or requiring complex apparatus.
2Length of stationary object
If axial punching or cutting of conical surface is used, then the outer diameter is reduced, but the zinc layer on the surface of galvanized steel pipe is destroyed
Solution Approach 1:
The pre-forming process creates the threaded surface geometry before thread rolling, and this process is designed to work with the pipe's existing outer diameter rather than requiring reduction. This eliminates the need for aggressive cutting or punching operations that would destroy the protective zinc layer. The rolling wheels apply controlled pressure to deform the surface into the required shape without removing material or compromising the zinc coating.
3Manufacturing precision
If high processing precision is used for cutting perfect conical surface, then the concentricity of workpiece and tool is improved, but the processing becomes difficult to achieve in construction site
Solution Approach 1:
The pre-forming process creates the necessary surface geometry with adequate precision for thread rolling without requiring ultra-precise concentricity control. The rolling wheels are designed to accommodate reasonable variations in pipe roundness and concentricity, making the process suitable for field conditions. The pre-formed threaded surface provides a robust foundation that tolerates the less stringent precision requirements of construction site operations.
Solution Approach 2:
The patent changes the approach from requiring high concentricity precision to accepting reasonable variations by using a pre-forming process that creates the surface geometry through controlled deformation rather than precise cutting. This parameter change in the manufacturing approach allows the process to be performed with simpler equipment suitable for mobile construction site applications.
4Adaptability or versatility
If conventional steel pipe with standard outer diameter and non-roundness is used, then the applicability is improved, but the non-roundness causes problems for thread rolling
Solution Approach 1:
The pre-forming process is specifically designed to work with conventional steel pipes that have standard outer diameters and acceptable levels of non-roundness. The rolling wheels create the threaded surface geometry through controlled deformation that accommodates the natural variations in pipe roundness. This pre-forming step transforms the pipe surface into a suitable configuration for thread rolling without requiring the pipe to have perfect circularity, thereby enabling the use of conventional off-the-shelf piping.
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 method allows for the rolling of external pipe threads on conventional steel pipes with standard dimensions, reducing non-roundness by 10-50% and increasing surface hardness, while preserving the zinc layer, and achieving a 99% pass rate for pipe thread products, enhancing the applicability and environmental sustainability of the process.
Implementation Method 1
the first rolling wheels are pre-formed rolling wheels with outer surface... the first rolling wheel group rolls the outer surface of the hollow blank into a threaded cylindrical surface, a threaded conical surface, or a threaded cylindrical conical mixing surface
Implementation Method 2
the surface roughness Ra of the thread on the outer surface of the hollow blank is less than 0.125, the surface hardness is increased by 20% to 100%
Data Source
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 step 1, 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.