KR-20260064223-A - Laser welding device for LNG cargo holds and laser welding system for LNG cargo holds including the same

KR20260064223AKR 20260064223 AKR20260064223 AKR 20260064223AKR-20260064223-A

Abstract

A laser welding device for an LNG cargo tank and a laser welding system for an LNG cargo tank including the same are disclosed. The laser welding device for an LNG cargo tank according to the present invention includes a laser receiver for receiving a laser beam, a light equalization unit for increasing the cross-sectional area of the effective beam region of the laser beam received by the laser receiver, and a mask unit for passing the effective beam region of the laser beam that has passed through the light equalization unit through a specific cross-sectional shape.

Inventors

조영호
박정원
김점구

Assignees

에이치디한국조선해양 주식회사

Dates

Publication Date: 20260507
Application Date: 20241031

Claims (15)

A laser receiver that receives a laser beam; A light equalization unit that increases the cross-sectional area of the effective beam region of the laser beam received from the laser receiver; and, A laser welding device for an LNG cargo tank comprising: a mask portion that passes the effective beam region of a laser beam passing through the light uniformization portion above through a specific cross-sectional shape.
In paragraph 1, A laser welding device for an LNG cargo tank, characterized in that the laser beam received by the laser receiver has a wavelength range of 800 nm to 1100 nm.
In paragraph 1, A laser welding device for an LNG cargo tank characterized by the above-mentioned light homogenizing unit performing light splitting, re-synthesis, and homogenization of the above-mentioned laser beam.
In paragraph 1, The above light homogenization unit is, A lens array section that divides the above laser beam into a plurality of small beams to form a uniform distribution, and A laser welding device for an LNG cargo tank characterized by including a focusing lens unit that increases the cross-sectional area of the effective beam region by focusing and advancing a plurality of small beams forming the above uniform distribution at a desired point.
In paragraph 4, A laser welding device for an LNG cargo tank, characterized in that the lens array section includes a first lens array section and a second lens array section, and the first lens array section and the second lens array section are arranged side by side.
In paragraph 1, A laser welding device for an LNG cargo tank characterized in that the laser beam passing through the above mask portion has a square cross-section.
In paragraph 6, A laser welding device for an LNG cargo tank, characterized in that the laser beam passing through the above mask portion has a cross-sectional side length of 3mm to 6mm.
entity; A moving part that moves the above main body along a certain trajectory; and, A laser welding device provided on one side of the main body and moving together with the main body to perform laser welding; is included. A laser welding system for an LNG cargo tank characterized by the above-mentioned laser welding device performing welding by increasing the cross-sectional area of the effective beam region of the laser beam.
In paragraph 8, The above laser welding device is, A laser receiver that receives a laser beam, and A light equalization unit that increases the cross-sectional area of the effective beam region of the laser beam received from the above-mentioned laser receiver, and, A laser welding system for an LNG cargo tank, characterized by comprising a mask portion that passes the effective beam area of the laser beam passing through the light uniformization portion above through a specific cross-sectional shape.
In Paragraph 9, The above light homogenization unit is, A lens array section that divides the above laser beam into a plurality of small beams to form a uniform distribution, and A laser welding system for an LNG cargo tank characterized by including a focusing lens unit that increases the cross-sectional area of the effective beam region by focusing and advancing a plurality of small beams forming the above uniform distribution at a desired point.
In Paragraph 10, A laser welding system for an LNG cargo tank, characterized in that the lens array section includes a first lens array section and a second lens array section, and the first lens array section and the second lens array section are arranged side by side.
In Paragraph 9, A laser welding system for an LNG cargo tank characterized in that the laser beam passing through the above mask portion has a square cross-section.
In Paragraph 12, A laser welding system for an LNG cargo tank characterized in that the laser beam passing through the above mask portion has a cross-sectional side length of 3mm to 6mm.
In Paragraph 9, A laser welding system for an LNG cargo tank, characterized in that the laser beam received by the laser receiver has a wavelength range of 800 nm to 1100 nm.
In paragraph 8, A laser welding system for an LNG cargo tank characterized by the above-mentioned laser welding device using the flat-top region of the laser beam as the effective beam region.

Description

Laser welding device for LNG cargo holds and laser welding system for LNG cargo holds including the same The present invention relates to a laser welding device for an LNG cargo tank and a laser welding system for an LNG cargo tank including the same, and more specifically, to a laser welding device for an LNG cargo tank and a laser welding system for an LNG cargo tank including the same that can perform laser welding without applying beam wobbling motion by increasing the effective cross-sectional area of the laser beam. Due to its characteristics, liquefied natural gas (LNG) must be stored and transported at cryogenic temperatures; to this end, ships or storage tanks used for storing or transporting LNG require highly reliable cargo tanks. The cargo tanks of LNG carriers are critical structures for safely storing and transporting cryogenic LNG. LNG carrier cargo tanks are classified into MOSS and membrane types. Inside membrane-type cargo tanks, membrane-shaped components are manufactured from metal materials such as Invar or stainless steel, and multiple panels are connected by welding. Conventional membrane welding methods have mainly applied traditional arc welding technologies such as TIG (Tungsten Inert Gas) or plasma welding. However, while TIG and plasma welding have the advantages of good weld quality and aesthetics, the welding speed is slow, resulting in low welding work efficiency. To address these issues, the introduction of laser welding technology has been considered. Laser welding offers advantages such as high precision and consistency, fast welding speeds, a small heat-affected zone, and low deformation. Automated laser systems can ensure uniform welding quality, and the use of high-energy-density laser beams can significantly improve welding speeds. However, there are still several technical challenges in laser welding of LNG cargo tank membranes. Major challenges remain, such as the difficulty of laser welding on metal surfaces with high reflectivity, precise laser beam control and positioning for large structures, ensuring welding quality for curved and corner sections, and real-time monitoring and quality control during the welding process. Specifically, LNG cargo tank membranes consist of very thin metal panels, so the welding depth and energy control must be very precise during laser welding. Otherwise, excessive welding may damage the membrane or reduce airtightness. In addition, optimization of the size and shape of the laser welding device is required, and due to the structural characteristics of the vessel, welding operations must be possible at various positions and angles. Therefore, developing a laser welding device specialized for welding the membranes of LNG cargo tanks and achieving high-quality welding through this is an important task in this technology field to increase the efficiency of the manufacturing process and ensure the stability of the cargo tanks. Meanwhile, since the laser beam of a conventional fiber laser welding device has a diameter of several hundred micrometers, welding must be performed through 'beam wobbling' when the gap size increases during membrane welding. Here, 'beam wobbling' refers to a method of rapidly moving the laser beam in a circular or straight line perpendicular to the weld seam. However, applying a wobble head to a laser welding device to implement 'beam wobbling' has disadvantages. The addition of motors and other components for wobbling increases the system's weight, making installation and relocation difficult and reducing productivity. Furthermore, the increased complexity of the system can affect maintenance and durability. Additionally, 'beam wobbling' increases welding time and can cause sagging during side and overhead welding of cargo tanks, potentially leading to quality issues. Therefore, there is a need to develop a laser welding system capable of responding to gap increases by increasing the effective cross-sectional area of the laser beam without configuring additional devices for 'beam wobbling' such as wobble heads and motors. FIG. 1 is a perspective view of a laser welding system for an LNG cargo tank according to one embodiment of the present invention. FIG. 2 is a front view of a laser welding device for an LNG cargo tank according to an embodiment of the present invention. FIG. 3 is a perspective view of a laser welding device for an LNG cargo tank according to an embodiment of the present invention. FIG. 4 is a perspective view of a laser welding device for an LNG cargo tank according to one embodiment of the present invention, viewed from another side. FIG. 5 is a configuration diagram illustrating a light homogenization section of a laser welding device for an LNG cargo tank according to an embodiment of the present invention. Figure 6 is an image comparing the cross-sectional profile of a typical laser beam with a profile in which the cross-sectional area of the effective beam region is increased by the optical