Soft Magnet Composite Impeder Core for Faster Induction Seam Welding
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Solution Overview
Problem
Current high-frequency induction welding systems for steel pipes are limited by the inefficiency of ferrite impeder cores, which have low saturation flux density, high thermal losses, and short service life, leading to reduced processing speed and increased energy consumption, particularly affecting small and medium diameters.
Innovation Solution
The use of soft magnet polymer composites for impeder cores, combined with selective ceramic protection and internal/external cooling, eliminates the need for a circumferential protective shell, enhancing efficiency and extending service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ferrite impeder cores are used in high-frequency induction welding, then the welding process can be performed, but the saturation flux density is low and thermal losses are high, limiting processing speed
Solution Approach 1:
The patent applies composite materials by combining soft magnetic particles (providing magnetic properties) with a polymer matrix (providing mechanical flexibility and processability). This composite structure achieves both high saturation flux density and reduced thermal losses, resolving the contradiction between productivity and energy loss.
Solution Approach 2:
The patent changes the material parameters of the impeder core by transitioning from conventional ferrite to soft magnet-polymer composite. This parameter change includes increasing saturation flux density and reducing thermal losses, thereby enabling higher processing speeds without excessive energy loss.
2Reliability
If ferrite impeder cores are used, then welding can be performed, but service life is short due to high thermal losses and material limitations
Solution Approach 1:
The soft magnet-polymer composite combines the advantages of soft magnetic materials (high permeability, low coercivity) with polymer materials (thermal stability, mechanical flexibility). This composite structure reduces thermal losses and extends service life while maintaining welding reliability.
Solution Approach 2:
The patent moves away from the disposable nature of conventional ferrite impeders by creating a durable composite material that can withstand repeated thermal cycles and mechanical stress, significantly extending service life and reducing replacement frequency.
3Volume of moving object
If conventional ferrite impeders are used for small diameter pipes, then welding is possible, but the impeder volume must be small which increases demands on saturation flux density and efficiency
Solution Approach 1:
The soft magnet-polymer composite provides high saturation flux density in a compact form, enabling small diameter pipe welding with reduced impeder volume while maintaining or improving welding efficiency. The composite material's superior magnetic properties compensate for the reduced volume.
4Productivity
If high welding speeds are achieved with conventional ferrite impeders, then processing output increases, but leakage current increases leading to heating of the pipe back and damage to material microstructure
Solution Approach 1:
The patent changes the electromagnetic parameters of the impeder core material, achieving lower leakage current at high welding speeds. The soft magnet-polymer composite's superior magnetic properties reduce eddy current losses and leakage current, preventing harmful heating of the pipe back while maintaining high 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 approach increases welding speed, reduces energy consumption, and improves weld quality while extending impeder core service life, thereby lowering manufacturing costs and environmental impact.
Implementation Method 1
High-frequency currents generate high-frequency electromagnetic fields in an inductor. These fields induce eddy currents of the same frequency f in electrically conductive materials
Implementation Method 2
These fields induce eddy currents of the same frequency f in electrically conductive materials, leading to a local concentration of the current density distribution
Implementation Method 3
leading to a local concentration of the current density distribution and, consequently, to local heating of the electrically conductive material through resistance heating
Implementation Method 4
A high frequency increases the efficiency of energy transfer from the inductor to the pipe preform
Implementation Method 5
Impeder cores are used for this purpose. They increase the resistance of the current path along the pipe's back, resulting in an increase in the usable gap current
Implementation Method 6
Additionally, due to the so-called skin effect, a higher frequency must be selected for thin walls to limit heat input to the joining zone
Data Source
Figure 1~2
Figure 3~5
AI summary
The invention relates to a device for manufacturing closed profile semi-finished products by means of inductive longitudinal seam welding, comprising an impeder core and an inductor that can be inserted into a profile semi-finished product and wherein the inductor encloses the profile semi-finished product at least partially during the joining process and forms a joining zone on the profile semi-finished product, wherein the impeder core consists of a soft magnet polymer composite and does not have a protective covering enclosing the impeder core, wherein a protective component is arranged at least on the side of the impeder core facing the direction of the joining zone.