Induction Coil Layout for ERW Pipe Heating Near Squeeze Rolls
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Solution Overview
Problem
Existing electric resistance welded pipe welding devices face issues with impeder burnout and reduced heating efficiency due to strong magnetic fields and the positional limitations of induction coils, particularly when manufacturing small-diameter or thick-walled pipes, where the induction coil's magnetic flux directly affects the impeder and limits the coil's proximity to squeeze rolls.
Innovation Solution
The electric resistance welded pipe welding device employs an induction coil with opening-vicinity conductor parts and a circulating conductor part that form a closed circuit without striding over the open pipe's opening portion, reducing magnetic flux density and allowing the coil to be positioned closer to squeeze rolls, thereby preventing impeder damage and enhancing heating efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the induction coil is arranged to circulate around the open pipe and stride over the opening portion, then the heating efficiency is improved, but the impeder is burnt out or rod coupling cutter breaks due to strong magnetic field inside the pipe
Solution Approach 1:
The induction coil is divided into a first induction coil and a second induction coil that are arranged separately on opposite sides of the open pipe, rather than using a single coil that strides over the opening. This segmentation prevents the formation of a strong magnetic field inside the pipe while maintaining effective heating of the end faces.
Solution Approach 2:
Non-magnetic support structures are introduced as intermediaries to hold the induction coils at appropriate positions without creating magnetic flux paths through the impeder. These support structures mediate between the need for coil positioning and the protection of magnetic components.
2Use of energy by moving object
If the induction coil is positioned closer to the squeeze rolls to improve heating efficiency, then the heating efficiency increases, but the magnetic field strength inside the pipe increases causing impeder damage
Solution Approach 1:
By segmenting the induction coil into multiple separate coils positioned on opposite sides of the pipe, the magnetic field distribution is changed. Each coil generates a localized magnetic field that heats the end faces effectively without creating a strong cumulative magnetic field inside the pipe that would damage the impeder.
Solution Approach 2:
The induction coils are positioned to create localized magnetic fields specifically at the end face regions that need heating, rather than generating a uniform strong magnetic field throughout the entire pipe interior. This localizes the heating effect while minimizing harmful magnetic field exposure to the impeder.
3Device complexity
If a single induction coil strides over the opening portion, then the device complexity is reduced, but the magnetic flux density inside the pipe increases causing component failure
Solution Approach 1:
The induction heating system is segmented into multiple independent coils rather than using a single continuous coil. This increases the number of components but eliminates the need for the coil to stride over the opening, thereby preventing magnetic flux from concentrating inside the pipe and causing component failures.
Solution Approach 2:
The problematic portion of the induction coil that would stride over the opening portion is extracted and removed from the design. Instead, separate coils are positioned on either side of the opening, taking out the source of the magnetic field problem while maintaining the heating function.
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 prevents impeder burnout and improves heating efficiency by reducing magnetic flux density and allowing closer proximity of the induction coil to squeeze rolls, effectively addressing issues in small-diameter and thick-walled pipe manufacturing.
Implementation Method 1
an induction coil (solenoid coil) is provided on, for example, the open pipe and a primary current is made to flow through the induction coil, to thereby directly generate an induced current in the open pipe
Implementation Method 2
both the end face portions that face the opening portion each other from both sides are made of a pipe material, by induced currents generated by an induction heating means
Implementation Method 3
a ferromagnet called an impeder is arranged at the inner surface side of the pipe in many cases
Implementation Method 4
In order to inhibit, out of the induced currents induced by this high-frequency current, the induced current that does not contribute to welding by tending to circulate around an inner periphery of the open pipe
Data Source
Figure 1~3
Figure 4~5(b)
Figure 6(a)~8
AI summary
An electric resistance welded pipe welding device for manufacturing an electric resistance welded pipe that melts both end face portions, of an open pipe having an opening portion extending in a running direction, both the end face portions that face the opening portion each other from both sides and are made of a pipe material, by induced currents generated by an induction heating means and brings the end face portions into contact with each other at a squeeze roll unit while gradually narrowing a gap of the opening portion and welds the end face portions together, the electric resistance welded pipe welding device includes: as the induction heating means, an induction coil composed of a pair of opening-vicinity conductor parts that are extended in the running direction along the end face portions at both sides of the opening portion and are arranged apart from an outer peripheral surface of the open pipe at positions not overlapping the opening portion in a plan view; and a first-portion circulating conductor part that is integrally provided at at least end portions, of the opening-vicinity conductor parts, on the side close to the squeeze roll unit in a longitudinal direction and is arranged apart from the outer peripheral surface of the open pipe so as to circulate around a portion, of the outer peripheral surface of the open pipe, excluding the opening portion.