Induction Coil Layout for Large-Diameter ERW Pipe Welding
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Solution Overview
Problem
Conventional electric resistance welded pipe manufacturing methods face inefficiencies in heating large diameter pipes due to excessive power consumption and defects from electrode contact issues, leading to reduced productivity and increased facility costs.
Innovation Solution
An electric resistance welded pipe welding apparatus is designed with an induction coil positioned above the opening of the pipe to form closed circuits straddling the opening, using a ferromagnet to suppress unwanted current flow and enhance heating efficiency, allowing for efficient welding without encircling the outer circumference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If an induction coil is wound around the outer circumference of the open pipe to generate induction current, then the pipe can be heated to welding temperature, but excessive power is consumed when manufacturing large diameter pipes
Solution Approach 1:
The patent segments the induction coil into two separate coils: a first induction coil positioned above the opening and a second induction coil positioned at the join portion. This segmentation allows each coil to be optimized for its specific function, reducing overall power consumption while achieving the required welding temperature. The first coil generates induction current without encircling the entire pipe, and the second coil provides supplemental heating at the critical weld zone.
Solution Approach 2:
The patent applies local quality by concentrating heating power where most needed. The second induction coil is specifically positioned at the join portion to provide intense localized heating, while the first coil provides more distributed heating. This localized approach to heating large diameter pipes reduces total power consumption by avoiding unnecessary heating of areas that don't require welding temperature.
2Loss of energy
If electrodes are pressed against the end parts of the open pipe to supply current, then heating efficiency improves, but defects occur due to electrode contact issues
Solution Approach 1:
The patent replaces the mechanical electrode contact system with a non-contact induction heating system. Instead of pressing electrodes against the pipe ends, the invention uses induction coils that generate electromagnetic fields to induce currents within the pipe material itself. This eliminates mechanical contact issues while maintaining high heating efficiency through electromagnetic energy transfer.
3Object-generated harmful factors
If a ferromagnet is placed at the inner face side of the pipe to prevent unwanted induction current, then current flow is controlled, but facility costs increase
Solution Approach 1:
The patent extracts the ferromagnet from the pipe interior and relocates it to the exterior surface at the join portion. This eliminates the need for internal ferromagnets that increase facility complexity and cost, while still achieving the goal of controlling induction current flow. The external ferromagnet configuration simplifies the overall system design and reduces manufacturing costs.
4Stability of the object's composition
If the induction coil is positioned to encircle the outer circumference of the pipe, then uniform heating is achieved, but productivity decreases for large diameter pipes
Solution Approach 1:
The patent segments the heating system into two strategically positioned coils rather than using a single encircling coil. This allows for faster, more targeted heating that improves productivity for large diameter pipes while still achieving sufficient temperature uniformity at the critical weld zone through the coordinated action of both coils.
Solution Approach 2:
The patent applies partial action by positioning the first induction coil above the opening rather than encircling the entire pipe circumference. This partial configuration is sufficient when combined with the second coil at the join portion, achieving the necessary heating effect more quickly than a full encircling coil would provide, thus improving manufacturing productivity.
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 configuration increases heating efficiency, reduces power requirements, and lowers facility costs by minimizing the need for large power sources and reducing electrode-related defects, enabling the production of larger diameter pipes with improved productivity.
Implementation Method 1
an induction heating coil with iron core is disposed above the end parts of an open pipe, and the end parts are heated by the action of an alternating magnetic field generated in an iron core by the flow of current in the induction heating coil
Implementation Method 2
a high frequency current is made to flow in end parts of the open pipe that face each other across an opening and, in a state of being heated to melting temperature
Implementation Method 3
a ferromagnet known as an impeder is often placed at the inner face side of the pipe. The impeder is employed to prevent induction current that does not contribute to welding, due to attempting to circulate around the internal circumference of the open pipe
Implementation Method 4
the end parts are heated by the action of an alternating magnetic field generated in an iron core by the flow of current in the induction heating coil
Data Source
Figure 1~3
Figure 4
Figure 5
AI summary
An apparatus for manufacturing electric resistance welded pipe, in which two across-opening-facing end parts (2a, 2b) of an open pipe (1) including an opening (2) extending in a running direction are melted by an induction current generated by an induction heating means and joined together at a join portion. The induction heating means includes a first induction coil (3), and the first induction coil (3) is disposed above the opening (2) so as not to encircle the outer circumference of the open pipe (1) and so that a primary current circuit is formed straddling the opening (2).