Search

KR-20260062323-A - Trihedron laser welding method

KR20260062323AKR 20260062323 AKR20260062323 AKR 20260062323AKR-20260062323-A

Abstract

The present invention relates to a welding method capable of laser welding a trihedron with improved quality without relying on the skill of a worker, wherein welding is performed on a trihedron having different type information so that it can be mounted while maintaining a downward tilt relative to an automatic positioner. More specifically, the method comprises: 1) a step of forming the outer shape of a trihedron of a different type by tack welding a plurality of panels; 2) a step of mounting the tack-welded trihedron on an automatic positioner device and inputting type information suitable for the mounted trihedron; and 3) a step of welding the trihedron based on the setting information stored in the automatic positioner and the type information of the trihedron, wherein the setting information stored in the automatic positioner in step 3) includes the mounting position and mounting angle value of the trihedron having different type information.

Inventors

  • 곽명섭
  • 남태운
  • 주성진

Assignees

  • 한화오션 주식회사

Dates

Publication Date
20260507
Application Date
20241029

Claims (5)

  1. In a welding method for manufacturing a trihedron (100), The above welding method is 1) A step of forming the outer shape of different types of trihedrons (100) by temporarily joining multiple panels; 2) a step of mounting the attached trihedron (100) on an automatic positioner device and inputting type information suitable for the mounted trihedron (100); and 3) A step of welding the trihedron (100) based on the setting information stored in the automatic positioner and the type information of the trihedron (100); wherein A trihedron laser welding method characterized in that, in step 3) above, the setting information stored in the automatic positioner includes the seating position and seating angle values of the trihedron (100) having different type information.
  2. In paragraph 1, Among the setting information stored in the automatic positioner in step 3) above A trihedron laser welding method characterized by tilting the trihedron (100) at an angle of 15 to 60 degrees relative to 0 degrees, where the ground is horizontal.
  3. In paragraph 1, In step 3) above, the welding of the trihedron (100) A trihedron laser welding method characterized by welding being performed in an outward direction starting from a center point (P).
  4. In paragraph 1, In step 3) above, the welding of the trihedron (100) A trihedron laser welding method characterized by welding from a high degree of constraint to minimize welding deformation.
  5. In paragraph 1, In step 1) above, the type information of the trihedron (100) is The alpha angle value (10) and the beta angle value (20) between the upper plate (120) welded to the upper surface of the horizontal plate (110) are determined by the alpha angle value (10) and the beta angle value (20), Type 1, where the beta angle value (20) is 90 degrees when the alpha angle value (10) is 90 degrees; Type 2, where the beta angle value (20) is 90 degrees when the alpha angle value (10) is 78.89 degrees; Type 3, where the beta angle value (20) is 78.89 degrees when the alpha angle value (10) is 74.48 degrees; Type 4, where the beta angle value (20) is 74.48 degrees when the alpha angle value (10) is 78.89 degrees; Type 5, where the beta angle value (20) is 78.89 degrees when the alpha angle value (10) is 90 degrees; Type 6, where the beta angle value (20) is 90 degrees when the alpha angle value (10) is 101.11 degrees; and when the alpha angle value (10) is 105.52 degrees. A trihedron laser welding method characterized by inputting into an automatic positioner as a 7th type where the beta angle value (20) is 101.11 degrees, an 8th type where the beta angle value (20) is 105.52 degrees when the alpha angle value (10) is 101.11 degrees, and a 9th type where the beta angle value (20) is 101.11 degrees when the alpha angle value (10) is 90 degrees.

Description

Trihedron laser welding method The present invention relates to a welding method capable of laser welding a trihedron with improved quality without relying on the operator's skill, wherein welding is performed on a trihedron having different type information so that it can be mounted while maintaining a downward tilt relative to an automatic positioner. Liquefied natural gas (LNG) carriers are vessels that transport liquefied natural gas from production facilities to receiving terminals, and are commonly abbreviated as LNG ships or LNGCs (LNG Carriers). LNG (Liquefied Natural Gas) is natural gas, whose main component is methane (NH4), liquefied at -162°C at atmospheric pressure. The volume ratio of liquid to gas in LNG is about 1/600, and the specific gravity of LNG in the liquefied state is 0.21 to 0.50. LNG storage tanks capable of withstanding cryogenic temperatures are installed on liquefied natural gas carriers, and these can be classified into independent type and membrane type. Because independent tank-type storage tanks use a large amount of non-ferrous metals as the main material, the manufacturing cost of the storage tank is high, so membrane-type storage tanks are currently widely used as LNG storage tanks. Membrane-type storage tanks are a proven technology that has been applied in the LNG storage tank sector for a long time, as they are relatively inexpensive and have not caused safety issues. The membrane type is structured such that the inner wall of the cargo tank, which is in direct contact with ultra-low temperature liquefied natural gas, is made using Invar alloy (Fe-Ni alloy) with high low-temperature toughness, and an insulation layer is placed between the outer wall. Meanwhile, metals generally change into a brittle state when cooled to low temperatures, becoming susceptible to breaking even from weak impacts. Therefore, the aforementioned storage tank made of metal is inevitably in a very vulnerable state because it stores ultra-low temperature liquefied gas inside. Under these conditions, if frequent rolling and pitching of the vessel cause the liquefied gas inside the storage tank to slosh and strike the inner walls, there is a risk that the vulnerable storage tank will be destroyed. To prevent this phenomenon, a 45-degree slope is placed on the inner wall of the storage tank to weaken the sloshing. The Invar trihedron is a member that connects two Invar tubes at a 135-degree angle to each other at the part where the inclined surface, horizontal plane, and vertical plane of the inner wall of the storage tank meet, which is bent at a 135-degree angle. To manufacture such an Invar trihedron, a highly precise process is required in which Invar components are mounted on a specially manufactured device and then welded. The above-mentioned trihedron is typically composed of 9 types and installed in LNGC storage tanks. It is welded by manual gas tungsten arc welding (GTWA). Since it is a 3t Invar fillet weld (or fillet weld), it is difficult to ensure welding quality unless the welder is highly skilled. Even for highly skilled welders, deformation may occur after tack welding and welding depending on the skill level. Therefore, flatness is maintained by impact within a strength limit where deformation of the Invar material does not occur. In other words, the conventional manufacturing of trihedrons for installation in LNGC storage tanks involves the inconvenience of relying on the skill of the operator, and additional post-welding processes (e.g., flatness maintenance processes) are inevitably required depending on the operator's skill level. Consequently, there is an urgent need for improvements in welding methods for trihedron manufacturing that eliminate the need for additional processes while not relying on highly skilled workers. FIG. 1 is a flowchart illustrating a trihedron laser welding method according to the present invention. FIG. 2 is a drawing illustrating a trihedron for FIG. 1. FIG. 3 is a drawing illustrating the welding sequence of a trihedron based on the front or rear direction relative to FIG. 2. FIG. 4 is a simplified front view of a first type of trihedron according to FIG. 1. Figures 5 and 6 are drawings showing the inclination of the trihedron for the automatic positioner during inside welding and outside welding for Figure 4. FIG. 7 is a drawing showing the welded appearance at point D of a 7th type trihedron according to the trihedron laser welding method according to the present invention. Hereinafter, various embodiments are described in more detail with reference to the attached drawings. The embodiments described in this specification may be modified in various ways. Specific embodiments may be depicted in the drawings and described in detail in the detailed description. However, specific embodiments disclosed in the attached drawings are intended only to facilitate understanding of various embodiments. Accordingly, the technical concept is not limited by spec