Defocused Laser Fracture Start Portion Formation
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Solution Overview
Problem
Existing methods for forming fracture start portions in ductile metal parts, such as connecting rods, using laser irradiation often result in uneven groove widths and heat-induced fusion, leading to suboptimal fracture surfaces due to excessive heat transmission and dross accumulation.
Innovation Solution
A method involving defocused laser irradiation with assist gas to form recess parts at predetermined intervals on the inner circumferential face of through holes in ductile metal parts, preventing heat interference and ensuring clean fracture surfaces by maintaining a wide recess part opening and preventing dross accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser is focused exactly onto the inner circumferential face to form recess parts, then manufacturing precision of the groove is improved, but heat transmission to adjoining positions causes fusion and uneven groove width
Solution Approach 1:
The patent applies local quality by defocusing the laser beam so that the focal point is positioned slightly away from the inner circumferential face of the through hole. This creates a localized heat affected zone that is confined to the target area, preventing heat transmission to adjoining positions while maintaining precise control over the recess part formation. The defocused laser beam distributes energy more evenly across the irradiation area, achieving uniform groove width without excessive heat concentration.
2Productivity
If laser irradiation is used to form fracture start portion, then productivity is improved compared to machining, but heat generated causes dross accumulation and contamination
Solution Approach 1:
The patent extracts the harmful dross from the formation process by introducing an assist gas flow that actively removes molten material and vaporized contaminants from the irradiation zone. The assist gas carries the dross away from the recess part, preventing accumulation and contamination of the fracture start portion. This allows high-speed laser irradiation to proceed without the harmful side effects of dross buildup.
Solution Approach 2:
The patent employs pneumatic principles by using a flow of assist gas to blow away dross and contaminants generated during laser irradiation. The gas flow is directed at the irradiation position to actively remove harmful byproducts, maintaining a clean fracture start portion while enabling high-productivity laser processing. This pneumatic removal mechanism effectively separates the useful laser heating effect from the harmful dross generation.
3Productivity
If continuous laser irradiation is applied to form groove, then productivity is improved, but heat accumulation causes fusion and loss of material control
Solution Approach 1:
The patent applies periodic action by using pulsed laser irradiation instead of continuous irradiation. The laser beam is applied in periodic pulses, allowing heat to dissipate between pulses and preventing heat accumulation that would lead to fusion and loss of material control. This periodic application of energy maintains manufacturing precision while achieving high productivity through efficient pulse timing and repetition rates.
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 allows for the precise formation of fracture start portions according to design dimensions, avoiding heat-induced deformations and ensuring a clean fracture surface when tensile stress is applied, thus enhancing the quality of the fracture surface.
Implementation Method 1
a step for forming a recess part by irradiating the laser onto the inner circumferential face of the through hole
Implementation Method 2
heat generated at a (specific) irradiation position of the laser
Implementation Method 3
supplying an assist gas to a position of the laser irradiation
Data Source
AI summary
This is a method of forming a fracture start portion of a ductile metal part on an inner circumferential face of a through hole by irradiating laser to an opposing position of the inner circumferential face of the thorough hole of the ductile metal part having a predetermined through hole and by forming a large number of recess portions separated with a predetermined distance at a predetermined interval from one opening to the other opening of the through hole, in which a recess part is formed, instead of by focusing the laser exactly onto the inner circumferential face of the through hole, by irradiating it onto the inner circumferential face of the through hole while defocusing from the inner circumferential face of the through hole by a predetermined amount as well as by supplying an assist gas to a position of the laser irradiation, and the laser is moved linearly at a predetermined speed from one side opening to the other side opening on the inner circumferential face of the through hole while irradiating the laser onto the inner circumferential face of the through hole at a predetermined pulse.