Oscillating Magnetic Pool Backing for Deep Arc Weld Support
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Solution Overview
Problem
In arc welding, high-frequency electromagnetic pool backings fail to provide sufficient penetration depth and supporting effect for weld pools, leading to unreliable weld seams, especially in thicker materials, due to insufficient magnetic power and capillary forces.
Innovation Solution
A low-frequency electromagnetic pool backing system is used in combination with arc welding, where a pair of magnetic poles generates a low-frequency oscillating magnetic field orthogonal to the arc, supporting the weld pool against hydrostatic and gravitational forces, and a self-moving magnetic unit eliminates the need for additional mechanical axes, allowing for improved gap bridging and filler material mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-frequency electromagnetic pool backing is used (above 1 kHz), then the arc is not influenced by magnetic fields and induced currents, but the penetration depth of the magnetic field and induced currents is too low resulting in insufficient supporting effect
Solution Approach 1:
The patent changes the frequency parameter of the electromagnetic field from the conventional high frequency (>1 kHz) to a lower frequency range (10-1000 Hz). This parameter change allows the magnetic field to penetrate deeper into the weld pool while still maintaining arc stability, as the lower frequency generates sufficient induced currents for deep penetration without creating harmful high-frequency interference with the arc
2Force
If higher magnetic power is applied at high frequencies to compensate for hydrostatic pressure, then the supporting effect increases, but the penetration depth remains insufficient due to skin layer theory
Solution Approach 1:
The patent applies parameter changes by reducing the frequency from >1 kHz to 10-1000 Hz, which fundamentally alters the skin depth of magnetic field penetration. This allows the electromagnetic force to act effectively at greater depths within the weld pool, combining sufficient support force with adequate penetration depth
3Ease of operation
If a mechanical axis is used for synchronous magnetic movement, then the welding process can be implemented, but the device complexity increases and it becomes difficult to realize for longer weld seams
Solution Approach 1:
The patent implements self-service by enabling the welding torch itself to generate and move the electromagnetic field along with the welding process. The torch contains the magnetic poles and power supply, allowing it to autonomously provide synchronous magnetic backing as it moves along the weld seam without requiring external mechanical axes or separate magnetic field generation systems
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 the depth effect of the magnetic field, enhances weld seam quality, and maintains arc stability, achieving better root and seam reinforcement uniformity across the weld seam, even in thicker materials, without negatively influencing the arc.
Implementation Method 1
a magnetic flux density of the low-frequency oscillating magnetic field is selected such that a Lorentz force induced in the weld pool by the low-frequency oscillating magnetic field supports the weld pool in a section of the joining gap against a hydrostatic force and/or against a gravitational force
Implementation Method 2
the frequency of the alternating field used for its operation is typically above 1 kHz in order to keep the penetration depth of the magnetic field and the induced currents low
Data Source
AI summary
An arc welding process is disclosed. In one example, the process comprises arranging an electrode at the front of a joining gap formed by joining partners contacted with opposite poles to the electrode; arranging a pair of magnetic poles at the rear or top of the joining gap and substantially centered with respect to the front electrode surface; generating the arc such that the joining partners form a welding zone comprising a weld pool with substantially simultaneous induction of a low-frequency oscillating magnetic field between the pair of magnetic poles; progressively moving the electrode along the joining gap to move the weld pool between the joining partners, leaving behind a weld seam, with synchronous entrainment of the low-frequency oscillating magnetic field. A magnetic flux density of the low-frequency oscillating magnetic field is selected such that an induced Lorentz force supports the weld pool and prevents escape from the joining gap.