Laser Welding Preheating Using Internal Joule Heating
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Solution Overview
Problem
Existing laser welding techniques face challenges in maintaining a high temperature of the object to be welded due to heat radiation from the surface, which can lead to inadequate preheating and increased risk of cracking, especially at the end edges during the welding process.
Innovation Solution
A laser welding device that incorporates a preheating system using electrodes to generate heat from within the object by flowing current through a first electrode contacting one face and a second electrode contacting the opposite face, effectively heating the object internally and preventing cracking by efficiently maintaining a high temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If preheating is performed by irradiating the object with a light beam from outside, then the object can be heated, but the high temperature cannot be maintained due to heat radiation from the surface
Solution Approach 1:
Instead of heating the object from the outside surface using light beam irradiation, the invention inverts the approach by inserting electrodes inside the object to generate heat internally through resistive heating. This internal heat generation eliminates the heat radiation loss from the surface that plagues external heating methods, allowing the object to maintain high temperature effectively during preheating.
Solution Approach 2:
The object itself serves as the heating element by utilizing its own electrical resistance. When current flows through the object via the inserted electrodes, the object generates heat internally through Joule heating (I²R heating). This self-heating mechanism allows the object to reach and maintain the necessary preheating temperature without relying on external heat sources that suffer from radiation losses.
2Ease of manufacture
If external light beam preheating is used, then the heating process can be simplified, but the preheating effectiveness is insufficient due to heat radiation
Solution Approach 1:
The invention inverts the heating approach from external light beam irradiation to internal electrode-based resistive heating. This inversion fundamentally improves preheating effectiveness by eliminating heat radiation losses, ensuring that the generated heat is retained within the object rather than being radiated away, thus achieving reliable preheating even though the process becomes slightly more complex.
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 ensures consistent and effective preheating of the object, particularly at the end edges, reducing the likelihood of cracking and improving the overall welding process by maintaining a high temperature without surface heat radiation issues.
Implementation Method 1
The preheating device heats at least part of the object by heat generated when a current flows in the object via the first electrode and the second electrode
Data Source
AI summary
There is provided a laser welding device that welds an object to be welded including two or more conductors contacting each other. The laser welding device includes: a welding laser irradiation unit that faces a first face of the object, the welding laser irradiation unit welding the object by irradiating the object with laser light; and a preheating device preheating the object. The preheating device includes a first electrode including a first contact part contacting the first face, and a second electrode including a second contact part contacting a second face of the object, the second face being on an opposite side to the first face. The preheating device heats at least part of the object by heat generated when a current flows in the object via the first electrode and the second electrode.