Variable-Focus Laser Optics for Gap Welding Sheet Metal
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Solution Overview
Problem
Existing laser processing machines struggle to effectively weld sheet metals with gaps due to a laser beam having a small beam diameter, which results in inadequate emission on both sides of the gap and reduced intensity when attempting to increase beam diameter by defocusing, leading to suboptimal gap welding.
Innovation Solution
A laser processing machine equipped with an optical device capable of changing the beam profile by using a focusing lens with different focal lengths and a moving mechanism to adjust the lens position, allowing for the beam profile to be tailored to specific welding conditions, such as using a Gaussian or ring-shaped profile, to ensure proper focusing and intensity distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the beam diameter is increased by defocusing the laser beam, then the beam can cover both sides of the gap, but the intensity of the laser beam becomes low
Solution Approach 1:
The focusing lens is divided into multiple lens regions (first lens region and second lens region) with different focal lengths. The first lens region focuses the laser beam to a small spot for high intensity, while the second lens region creates a larger beam diameter. This segmentation allows the system to achieve both high intensity and adequate beam coverage without defocusing the entire beam.
Solution Approach 2:
Different regions of the lens are assigned different optical properties (different focal lengths) to create different beam characteristics in different areas. The first lens region provides high intensity focusing for deep penetration welding, while the second lens region provides larger beam diameter for gap coverage, allowing each region to optimize for its specific function.
2Illumination intensity
If a small beam diameter is used, then the laser beam intensity is high, but the beam cannot be emitted to both sides of the gap
Solution Approach 1:
The optical device can dynamically switch between different beam profiles (small diameter high intensity profile and large diameter ring-shaped profile) by changing which lens region is active. This dynamic adaptability allows the system to adjust the beam characteristics according to the specific welding conditions, such as gap size and material thickness.
Solution Approach 2:
The focusing lens with multiple lens regions serves multiple functions: it can produce both small diameter high intensity beams for deep penetration welding and large diameter ring-shaped beams for gap welding. This multi-functionality eliminates the need for separate optical systems for different welding applications.
3Area of moving object
If defocus is performed to increase beam diameter, then the beam covers larger area, but the focusing position shifts from the sheet surface
Solution Approach 1:
The optical device acts as an intermediary between the laser source and the workpiece, transforming the beam profile without requiring defocusing. By using the second lens region to create a ring-shaped beam with larger diameter, the system achieves adequate gap coverage while maintaining the focus position at the sheet surface, eliminating the need for defocus.
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 solution enables flexible beam profile adjustment, allowing for effective welding across various processing conditions, including deep penetration, surface treatment, and gap welding, by optimizing beam diameter and intensity distribution, thereby improving the quality and efficiency of the welding process.
Implementation Method 1
a focusing lens configured to focus the laser beam emitted from the optical device, the focusing lens including a first lens region with a first focal length on an inner peripheral side thereof and a second lens region with a second focal length on an outer peripheral side thereof
Data Source
AI summary
A laser processing machine includes a coupler that is an optical device capable of changing a beam profile of a laser beam emitted from a fiber laser oscillator, a focusing lens configured to focus the laser beam emitted from the coupler, the focusing lens including a first lens region with a first focal length on an inner peripheral side thereof and a second lens region with a second focal length on an outer peripheral side thereof, the second focal length being different from the first focal length, and a moving mechanism configured to move the focusing lens in an optical axis direction.