KR20120133086A - Circumference welding method of thick-wall product and weldment thereof - Google Patents

Abstract

PURPOSE: A circumferential welding method and structure for a thick-wall product are provided to reduce the time for circumferential welding of a thick-wall product and improve productivity. CONSTITUTION: A circumferential welding method for a thick-wall product comprises the steps of: oscillating one or more electrode wires along the thickness of a thick-wall product while generating arc with the electrode wires on the interior and/or exterior surface of a weld part(130) and rotating a welding member when the weld part is filled with a predetermined amount of material molten by the electrode wires. The electrode wires are arranged on the exterior of the weld part and the interior of the weld part is sealed before welding.

Description

CIRCUMFERENCE WELDING METHOD OF THICK-WALL PRODUCT AND WELDMENT THEREOF}

The present invention relates to a one-pass circumferential welding method of a thick material used in an offshore structure and the like, and a welded welded by the same, and to a circumferential welding method of a thick material in which a manufacturing time is drastically shortened, and a weldable product that is easy to produce.

Recently, due to the rise in oil prices and the destruction of the environment of fossil energy and nuclear energy, there is a lot of interest in environmentally friendly energy, and accordingly, wind power generation is receiving attention.

In the case of wind power generation, it is installed on the ground or the ocean, and often installed in places where people do not live due to the size and noise, and therefore, the ocean is preferred as a location for installing a wind power plant. When installed at sea, the stiffness required for a wind generator is large because the wind generator must withstand not only the wind but also the waves, thus requiring a rigid structure.

1 shows an example of a wind generator installed in the ocean. As shown in FIG. 1, the wind generator includes a main body 1 including Russell, a tower 2 supporting the same, a platform 3 formed on the tower 2, a monopile 4 fixing the tower 2 at sea, and It consists of the sky protector 5 which protects the said mono pile 4.

At this time, the tower 2 has a substantially cylindrical shape, in order to withstand waves as well as wind, the use of a thick material of 50mm or more is required. The formation of the cylindrical tower 2 using this thick material is shown in FIGS. 2A and 2B.

Since the tower 2 is formed at a considerable height, the cylindrical material 4a, 4b is circumferentially welded after rolling the thick material to form the cylindrical members 4a, 4b. Primarily, the thick material is welded using X groove welding, the inside of the cylindrical member using a welding arm, and then subjected to Girth Submerged Arc Welding (20). Submerged arc welding 21 is performed.

At this time, the submerged arc welding apparatuses 20 and 21 are fixed, and circumferential welding is made while rotating the cylindrical members 4a and 4b through the roller 10.

However, such a welding method has a small welding amount, and thus, as shown in FIG. 3A, multi-pass welding in which many welding portions 30a and 30b are generated is required, and as the thickness of the thick material increases, There is a problem that the number increases. As shown in Figure 3a, when welding the thick material of about 50mm by the gauze submerged arc welding method it is necessary to weld 50 ~ 60 passes.

In addition, the thicker the thickness of the thick material, the larger the diameter of the cylindrical member is, and the circumferential length is about 15m. Therefore, as the thickness of the thick material increases, the welding time by gauze submerged arc welding increases exponentially, and there is a problem that productivity is extremely reduced.

In addition, even in the case of non-wind power generation, when the circumferential welding is required for offshore structures, thick materials, or ultra thick materials, the thickness of the members becomes thicker, so that the length of each pass becomes longer with conventional welding such as submerged arc welding. However, there is a problem that the required path also increases, which takes a long time for welding.

The present invention is to solve the above problems, an object of the present invention to provide a welding method for innovatively reducing the welding time in the circumferential welding of the thick material.

It is also an object of the present invention to provide a weldment structure which improves the productivity of the product.

The present invention provides the following circumferential welding method and welding structure in order to achieve the above object.

The present invention is a circumferential welding method for welding the circumference of a cylindrical or truncated cone-shaped member formed of a thick material, the arc of the electrode wire at one or more of the inner circumferential surface and the outer circumferential surface of the weld portion, the thickness of the thick material A circumferential welding method for oscillating in a direction and rotating the welding member when a predetermined melt is filled in the welding portion by melting the electrode wire.

In the present invention, the electrode wire is disposed on the outer circumferential surface of the welding portion, it is possible to seal the inner circumferential surface of the welding portion before welding with the electrode wire.

At this time, the sealing of the inner circumferential surface may be performed by welding or by attaching a backing material.

In addition, in the present invention, the electrode wires are two electrode wires arranged in the thickness direction, and the outer circumferential surface of the welding member is blocked by copper quench, and the protective gas may be supplied to the welding part during welding.

On the other hand, the present invention is a welding structure welded two or more cylindrical or truncated conical member formed of a thick material, including a weld welded in the circumferential direction, the weld is formed in the X-type welding groove, the outer peripheral surface of the X-type welding groove The side provides a welding structure having a one-pass welding structure.

Alternatively, the present invention is a welding structure in which two or more cylindrical or truncated cone-shaped members formed of a thick material are welded, and includes a welded portion welded in the circumferential direction, and the welded portion is formed in a V-shaped weld groove, Branches provide a welded structure.

In addition, the member is preferably formed of a high heat input steel material rigidity is maintained even in the high heat input due to one-pass welding.

In the present invention, the one-pass weld structure may include a coarse heat affected zone having a primary austenite grain size of 150 μm or more.

At this time, the composition of the weld metal of the weld portion includes a needle-like ferrite and grain boundary ferrite (Grain boundary ferrite), the grain size (Grain size) of the weld metal may be 4 ~ 10㎛.

Further, the one-pass welded structure may include a coarse heat affected zone having a primary austenitic grain size of 80 to 100 μm.

The present invention can provide a welding method for greatly reducing the welding time in the circumferential welding of the thick material through the above configuration.

In addition, the present invention can provide a weldment structure that improves the productivity of the product.

1 is a schematic diagram of wind power generation.
2A to 2B are schematic views showing a conventional welding method, FIG. 2A is a schematic sectional view, and FIG. 2B is a schematic perspective view.
3 is a cross-sectional view of a welded portion circumferentially welded in the conventional welding method.
4 is a schematic cross-sectional view showing the circumferential welding method of the present invention.
5 is a sectional view of a welded portion of the welded structure welded according to the circumferential welding method of FIG. 4.
6A and 6B are schematic cross-sectional views showing another embodiment of the circumferential welding method of the present invention. FIG. 6A shows the inner circumferential welding, and FIG. 6B shows the outer circumferential welding.
7 is a sectional view of a welded portion of a welded structure welded according to the circumferential welding method of FIGS. 6A and 6B.
8A is an enlarged view of the structure of a weld welded by a conventional welding method, and FIG. 8B is an enlarged view of the structure of a weld welded according to the present invention.

Hereinafter, with reference to the accompanying drawings, it will be described a specific embodiment of the present invention.

In the embodiment of the present invention is described as a cylindrical member, wherein the cylindrical member is a substantially cylindrical or truncated cone, it can be applied to the shape rotated around the axis of rotation.

In addition, the one-pass welding structure means a structure in which the heat affected zone is formed at one time by welding in a single pass.

4 shows the circumferential welding method of the present invention in a schematic sectional view. As shown in FIG. 4, a cylindrical member 100 is formed of a thick material having a thickness t1 of 50 mm or more, and welding is performed while two cylindrical members 100 are aligned side by side (see FIG. 2B).

In addition, the cylindrical member 100 is placed on the roller 101 which is the rotation driving unit, and as the roller 101 rotates, the cylindrical member 100 rotates. The backing material 150 is attached to the inner circumferential surface of the welded portion 130 of the cylindrical member 100 before welding, which seals the inner circumferential surface of the welded portion 230 to prevent the melt from flowing into the cylindrical member 100.

On the other hand, as shown in the enlarged view of the welded part, in the circumferential welding of the present invention, carbon dioxide 160 is mainly used as a protective gas, and an arc is generated by the electrode wire W supplied to the electrode wire torch 110. This arc heat melts the electrode wires W of the torch 110 for electrode wires to allow welding. At this time, the electrode torch 110 for oscillating in the thickness direction so that the melt by the arc of the electrode wire (W) evenly filled throughout the weld.

The water-cooled copper immersion 140 is installed on the front surface of the cylindrical member 100, and the backing material 150 is provided on the back surface, and the electrode wire is provided through an arc generated between the supplied electrode wire W and the molten portion 130. (W) is melted to form a molten metal 132. The electrode wire torch 110 is mounted, and the electrode wire torch 110 is oscillated through a driving means (not shown) of the welding carriage body (not shown) fixed to be movable in the front-rear direction. 132 is well filled in the weld.

In the circumferential welding of the present invention, when the welding wire W is melted and the molten metal 132 is filled to a certain level, a stick-out control for changing the welding position is performed. In particular, in the present invention, since the welding member is a cylindrical member 100, the welding carriage body (not shown) is fixed, the cylindrical member 100 in which the molten metal 132 is filled in the molten portion 130 is downward. Rotate That is, the roller 101 disposed below the cylindrical member 100 is rotated, and accordingly, the cylindrical member 100 including the welded part 130 and the molten metal 132 filled therein is lowered.

As the welding carriage body (not shown) is fixed in this manner, the cylindrical member 100 is rotated, such that the welding carriage body (not shown) and the torch 110 for electrode wire mounted thereon are cylindrical members only by the forward and backward movement. Welding to 100 can be performed. Particularly, in the present invention, the rotating body, that is, the cylindrical member 100 and the truncated conical member are targeted, and since their features are rotated about the center, the welding is performed when the roller 101 is rotated. The part performed is always in the same position, so that the weld carriage body (not shown) can be fixed in position without having to move.

In addition, in order to initially collect the molten metal 132, it is preferable to weld the plate 170 corresponding to the shape of the welding portion to the welding portion 130, attach the backing material 140 before welding, and after the welding is finished It is preferable to remove the backing material 140.

In the present invention, since the electrode wire W is oscillated with respect to the entire thickness, the molten metal 132 is supplied, so that the welding member may be welded in one pass unlike the conventional submerged arc welding.

In the case of forming a cylindrical or truncated cone with a thick material of 50 mm or more, it is inevitable to have a large diameter, and generally has a diameter of 3 m or more. Therefore, in the case of welding the welding member in one pass, the welding distance can be drastically reduced in comparison with the multiple passes.

FIG. 5 shows a sectional view of the welded portion 130 of the welded structure, ie, the cylindrical member 100, circumferentially welded by the circumferential welding method of the invention of FIG. 4.

As shown in FIG. 5, the weld part 130 is formed as a V-shaped groove part, and is welded in one pass by the circumferential welding method of the present invention, so that the heat-affecting part only on the weld part 130 side of the cylindrical member 100 is formed. HAZ) is formed.

As described above, the circumferential welding method of the present invention is to perform the conventional multi-pass submerged arc welding by the one-pass circumferential welding method, which can be performed by innovatively reducing the time required for welding. That is, by welding 50 to 60 passes, it is possible to reduce the welding distance to 15 m using the one-pass circumferential welding method of the conventional welding method that required a 900 m welding distance in the case of a cylindrical member having a circumference of 15 m.

In addition, the stick-out control for rotating the cylindrical member without the need to move the welding carriage body (not shown) because it is a rotating body, there is no need for a configuration for the movement of the welding carriage body, it is advantageous to apply the welding method.

Moreover, in the case of the welded structure welded by the circumferential welding method of this invention, since it is a structure with good productivity, it becomes possible to provide the same rigid structure more cheaply.

However, in the case of one-pass circumferential welding, since the amount of heat input is high and the heat-affected portion formed on the welding member may be weak, it is preferable to use a thick material formed of a high heat input steel material as the thick material.

FIG. 6A shows the inner circumferential welding of another embodiment of the circumferential welding method of the present invention, and the outer circumferential welding in FIG. 6B.

When the thickness of the cylindrical member 100 is thick, in the case of one-pass welding by the circumferential welding method as shown in FIG. 4, the amount of heat input is large, and the rigidity of the heat affected zone may be reduced. Accordingly, the present invention provides another embodiment of a circumferential welding method in which a portion of the inner circumferential surface is welded by submerged arc welding with a small amount of heat input, and the remaining portion is performed through the circumferential welding described in FIG. 4.

In the case of submerged arc welding, the arm is inserted into the cylindrical member 200 in the same manner as the conventional inner circumferential welding, and submerged arc welding is performed in the flux. At this time, the submerged arc welding is performed in multiple passes, while the welding of the outer circumferential surface is performed in one pass by rotating the welding member while oscillating the torch for the electrode wire in the thickness direction. At this time, the welding portion 230 is formed as an X-shaped groove, to enable welding from both sides.

FIG. 6A illustrates a welding operation using the SAW welding apparatus 220 on the inner circumferential surface of the cylindrical member 200. SAW welding of the inner circumferential surface is performed in a multi-pass, the roller 201 is rotated to rotate the cylindrical member 200, the SAW welding proceeds.

On the other hand, after removing the flux of the submerged arc welding of the inner circumferential surface, welding is performed to oscillate the electrode wire in the thickness direction on the outer circumferential surface. At this time, since the inner circumferential surface is sealed by the submerged arc welding part 205, a separate backing material 150 (refer to FIG. 4) is not necessary.

As shown in the enlarged view of the welded portion, in the embodiment of FIG. 6B, the outer circumferential side welding is performed using a plurality of torches 210 and 220 for electrode wires. The outer circumferential side welding in this embodiment mainly uses carbon dioxide 260 as a protective gas, similarly to the embodiment of FIG. 4, and is provided by electrode wires W1 and W2 supplied to the torch 210 and 220 for electrode wires. The arc is generated, and the arc heat melts the electrode wires W1 and W2 of the torch 210 and 220 for the electrode wire, thereby welding.

Water-cooled copper alloy 240 is installed on the front surface of the cylindrical member 200, but the submerged arc welding portion 205 is formed on the rear surface, so an additional backing material 150 (see FIG. 4 may not be necessary). The electrode wires W1 and W2 are melted through an arc generated between the electrode wires W and W2 and the melting part 230 to form a molten metal 232. Torch 210 and 220 for electrode wires And torch the electrode wire torches 210 and 220 through a driving means (not shown) of the welding carriage body (not shown) fixedly movable in the front-rear direction, so that the molten metal 232 is welded to the welding portion. Make sure it is well charged.

4 and 5, the circumferential welding of this embodiment is a stick-out control to change the welding position when the welding wires W1 and W2 are melted and the molten metal 232 is filled to a certain level. The welding carriage body (not shown) does not move, and the cylindrical member 200 in which the molten metal 232 is filled in the melting part 230 rotates downward. That is, the roller 201 disposed below the cylindrical member 200 is rotated, and accordingly, the cylindrical member 200 including the welded portion 230 and the molten metal 232 filled therein is lowered.

In addition, in order to initially collect the molten metal 232, it is preferable to weld the plate 270 corresponding to the shape of the weld to the weld 230.

The hybrid circumferential welding method as described above can apply the one-pass welding method of rotating the welding member while oscillating the electrode wire, even if the thickness of the thick material is increased. Therefore, even if the welding time of the inner circumferential surface takes a while, the welding time can be shortened by one-pass welding on the outer circumferential surface, and thus, the overall welding time can be reduced.

In particular, by forming the X-shaped grooves symmetrically rather than symmetrically to one side to form welds of one-pass welding with a thickness that does not affect the rigidity, the thickness of the submerged arc welding on the inner circumferential surface can be reduced. This can reduce the time of the entire welding.

 7 is a cross-sectional view of a welded portion welded by the welding method of FIG. 6. As shown in FIG. 7, the inner peripheral surface side (the lower side in FIG. 7) has a weld 205 formed by multipass welding by submerged arc welding, and thus the heat affected portion is formed a plurality of times, and the heat affected portion is also formed in the weld 205. do.

On the other hand, since the outer circumferential surface side (upper side in FIG. 7) is performed by one-pass welding, in particular, one-pass welding using a plurality of electrode wires, the heat-affecting portion is formed only on the welded portion 230 side of the cylindrical member 200.

In addition, the center of the X-type welding groove is also lowered to the inner circumferential surface side (lower side in Fig. 7), so that the one-pass circumferential welding welds a larger thickness than the submerged arc welding.

As such, the present invention significantly reduces the welding time while welding the circumference of a cylindrical or truncated conical member using one-pass circumferential welding with or without conventional submerged arc welding.

In addition, by providing a structure in which the welding time can be reduced, it is possible to lower the cost of the product.

8A is an enlarged view of the structure of a welded portion welded according to a conventional welding method, and FIG. 8B is an enlarged view of the structure of a welded portion welded according to the welding method of the present invention.

8A and 8B, the primary austenitic grain size of the heat affected zone, in particular the coarse heat affected zone (CG HAZ) of the conventional welding method is 100-150 μm, The primary austenite grain size of the heat affected zone and the coarse heat affected zone according to the welding method is 150 to 250 μm. This is because, due to the one-pass welding, the heat input amount is increased compared to the conventional SAW welding.

In the case of the weld metal, the conventional and the present invention are the same as acicular ferrite and grain boundary ferrite, but the crystal grain size of the conventional weld metal is 0.5 to 5 μm, but the present invention is In the case of 4 ~ 10㎛ the oral cavity according to the method of the present invention is coarser than conventional.

However, when the present invention is applied to high heat input steel, the crystal grain size of the primary austenite of the coarse heat affected zone may be reduced to a level of 80 to 100 μm. Thus, high quality welds can be provided in a short time.

100, 200: cylindrical member, 101, 202: roller
110, 210, 220: torch for electrode wire
130, 230: weld 132, 232: molten metal
140, 240: lump sum 150: backing material
170, 270: plate

Claims (10)

A circumferential welding method for welding the circumference of a cylindrical or truncated conical member formed of a thick material,
Oscillating the electrode wire in the thickness direction of the thick material while generating an arc with at least one electrode wire on at least one of the inner and outer circumferential surfaces of the weld portion,
A circumferential welding method wherein a welding member is rotated when a predetermined melt is filled in a welding portion by melting the electrode wire. The method of claim 1,
The electrode wire is disposed on the outer peripheral surface of the welding portion,
And the inner circumferential surface of the weld portion is sealed before welding with the electrode wire. The method of claim 2,
Sealing of the inner circumferential surface is a circumferential welding method, characterized in that carried out by welding. The method of claim 2,
Sealing the inner circumferential surface is performed by attaching a backing material. 5. The method according to any one of claims 2 to 4,
The electrode wires are two electrode wires arranged in the thickness direction,
The outer circumferential surface of the welding member is blocked with copper quench, and a circumferential welding method characterized in that for supplying a protective gas to the welding portion during welding. A welding structure in which two or more cylindrical or truncated conical members formed of thick materials are welded,
Including a weld welded in the circumferential direction,
The welding portion is formed in the X- or V-type welding groove, the welding structure having a one-pass welding structure on the outer peripheral surface side of the welding groove. The method according to claim 6 or 7,
The member is welded structure, characterized in that formed of a high heat input steel. The method according to claim 6,
The one-pass welding structure includes a coarse heat affected zone having a primary austenitic grain size (Primary Austenite Grain Size) of 150 μm or more. The method of claim 8,
The welding metal composition of the welding portion includes a needle-like ferrite and grain boundary ferrite (Grain boundary ferrite), the weld grain characterized in that the grain size (Grain size) of the weld metal is 4 ~ 10㎛. The method of claim 7, wherein
The one-pass welding structure is a welding structure, characterized in that it comprises a coarse heat affected zone having a primary Austenite grain size (Primary Austenite Grain Size) of 80 ~ 100㎛.

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