JP2002144038A - Method for welding butt jointing part and welding torch using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for welding a butt jointing part and a welding torch using the method with which even in the case of developing ascending gas stream with a preheating, etc., the shield can be surely performed. SOLUTION: A shield cover 1 is fitted to a welding torch body (auxiliary shield box) and the shield gas is closely shielded by always covering almost the whole periphery of bevel 16 in the butt jointing part of an upper and a lower members 11, 12 with this shield cover, and while exhausting the shield gas from an opening part 17 formed at the front part in the welding direction of the welding torch body, the gas shield arc welding is performed. Further, in the case of using plural welding torches, shield parting walls in the shield cover of each welding torch, are arranged and each shield cover is made independent. Furthermore, in the case of performing the butt welding to flat platy members, the bevel is covered with the shield cover fitted to the welding torch body, and at both end parts of the shield cover, the shield parting walls are arranged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of welding a butt joint and a welding torch used for the method, and is useful when applied to a butt joint of a cylindrical member or a flat plate member such as a turbine rotor. .

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for a steam turbine plant with a high temperature, a large capacity, and a short delivery time. In order to meet this need, a welding structure of a steam turbine rotor is considered, and its development is currently being promoted.

FIG. 14 is a longitudinal sectional view showing an example of such a steam turbine rotor. The turbine rotor 1 shown in FIG. 1 has welded joints 2 and 3 at two locations in the axial direction. 12% Cr steel is adopted in a high temperature region where high temperature strength is required, and in a low temperature region where toughness is required. Adopts 3.5NiCrMoV steel. In the welded joints 2 and 3, the inside of the rotor is hollow, that is, cylindrical.

In such welding of the turbine rotor, since the straightness of the entire turbine rotor is required after the welding, the members must be accurately butted at the time of welding. The members are erected vertically and the butt joints are horizontal, and the welding position of the welding torch is accordingly horizontal. As a welding method, a gas shielded arc welding method using a TIG welding torch is employed in order to obtain high quality.
Further, in order to prevent low-temperature cracking during welding, the turbine rotor member is preheated to 200 to 300 ° C by a preheater.

[0005]

However, when the turbine rotor member is preheated at the time of welding, the air around the turbine rotor member is also heated and an updraft is generated, which disturbs the flow of the gas shield. Oxidation of the bead surface and blowhole defects are likely to occur. Further, since an oxide film is formed on the groove surface of the weld metal, the fluidity of the molten metal is deteriorated, so that poor fusion is likely to occur. Therefore, defect-free welding is difficult. In particular, defect-free welding is required for a turbine rotor that is a rotating body.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above problems, and provides a method for welding a butt joint and a welding torch used for the same, which can reliably perform shielding even when an updraft is generated due to preheating of members. The task is to

[0007]

Means for Solving the Problems A first method for solving the above problems is described below.
The method of welding a butt joint of the present invention is a welding method of welding a butt joint portion of a cylindrical member by gas shielded arc welding, wherein a band-shaped shield cover attached to the welding torch main body is fixed to the cylindrical member together with the welding torch main body. The shield gas is sealed by covering the groove of the butt joint part from the welding torch main body to the rear in the welding direction over substantially the entire circumference by the shield cover at all times. Gas shielded arc welding is performed while discharging shield gas from an opening formed in the front of the main body in the welding direction.

A welding torch for a butt joint according to a second aspect of the present invention is a welding torch for welding a butt joint portion of a cylindrical member by gas shielded arc welding, wherein a band-shaped shield cover attached to the welding torch main body is used for welding. The shield gas is sealed by moving in the welding direction relatively to the cylindrical member together with the torch body, and covering the groove of the butt joint part substantially all the way from the welding torch body to the rear in the welding direction. And, while discharging the shielding gas from the opening formed in the welding direction front of the welding torch body,
It is characterized in that gas shielded arc welding is performed.

A butt joint welding method according to a third aspect of the present invention is a welding method for welding a butt joint portion of a cylindrical member by gas shielded arc welding, wherein the welding is performed by simultaneously using a plurality of welding torches. In each welding torch, the band-shaped shield cover attached to the welding torch main body is moved in the welding direction relative to the cylindrical member together with the welding torch main body. The shield gas is sealed by covering the groove of the butt joint.
In addition, the shield gas is discharged from the opening formed in the welding torch main body in the front in the welding direction, and furthermore, the shield gas is provided by the shield partition provided at both ends of the shield cover in the welding direction so as to be movable in the radial direction of the cylindrical member. Gas shielded arc welding is performed while preventing leakage before and after the welding direction.

A welding torch for a butt joint according to a fourth aspect of the present invention is a welding torch for welding a butt joint portion of a cylindrical member by gas shielded arc welding, wherein the welding is performed by simultaneously using a plurality of welding torches. In each welding torch, the belt-shaped shield cover attached to the welding torch main body moves in the welding direction relative to the cylindrical member together with the welding torch main body. Sealing the shielding gas by covering the groove of the butt joint part backward, and,
The shield gas is discharged from the opening formed in the front of the welding torch in the welding direction, and furthermore, the shield gas is moved in the welding direction by the shield partition walls provided at both ends of the shield cover in the welding direction so as to be movable in the radial direction of the cylindrical member. Gas shielded arc welding is performed while preventing the gas from flowing out before and after.

A butt joint welding method according to a fifth aspect of the present invention is a welding method for welding a butt joint portion of a flat plate member by gas shielded arc welding, wherein the band-shaped shield cover attached to the welding torch body is flattened together with the welding torch. The shield gas is moved in the welding direction relatively to the member, and the shield gas is always sealed by covering the groove of the butt joint part from the welding torch body to the rear in the welding direction with the shield cover. The shield gas is discharged from the opening formed in the front of the main body in the welding direction, and furthermore, the shield gas is moved forward and backward in the welding direction by a shield partition provided at both ends of the shield cover in the welding direction so as to be vertically movable with the flat member. While preventing spills
It is characterized by performing gas shielded arc welding.

A welding torch for a butt joint according to a sixth aspect of the present invention is a welding torch for welding a butt joint portion of a flat plate member by gas shielded arc welding, wherein a band-shaped shield cover attached to the welding torch main body is used for welding. The shield gas is moved by moving the welding torch relative to the flat member together with the torch body, and always covers the groove of the butt joint from the welding torch body to the rear in the welding direction to seal the shielding gas. The shield gas is discharged from the opening formed in front of the welding direction of the shield cover. It is characterized in that gas shielded arc welding is performed while preventing leakage.

A butt joint welding method according to a seventh aspect of the present invention is the butt joint welding method according to the first, third or fifth aspect, wherein the welding torch main body is perpendicular to the radial direction of the cylindrical member or to the plate member. An electrode portion and a seat cover attachment portion are provided so as to be relatively movable in the directions, and a shield cover is attached to the seat cover attachment portion.

The welding torch for a butt joint according to an eighth aspect of the present invention is the welding torch for a butt joint according to the second, fourth or sixth aspect, wherein the welding torch main body is perpendicular to the radial direction of the cylindrical member or to the flat member. An electrode portion and a shield cover attaching portion are provided so as to be relatively movable in the direction, and a shield cover is attached to the shield cover attaching portion.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings.

[First Embodiment] FIGS. 1, 2 and 3 are a perspective view, a longitudinal sectional view and a cross section showing a method of welding a butt joint according to a first embodiment of the present invention and a configuration of a welding torch used for the method. FIG. 4 is a cross-sectional view of the electrode portion of the welding torch. FIG. 5 is an explanatory view showing the reason why an opening is provided in the welding torch main body in the front in the welding direction, and FIG. 6 is a longitudinal sectional view showing a state in which a shield cover is not attached to the welding torch main body.

<Structure> As shown in FIG. 1, FIG. 2 and FIG.
The first member 12 and the second member 12
Of the lower member 11 and the lower end of the lower member 12 are accurately butted against each other (a butt joint portion). 13).

In the first embodiment, gas shield arc welding is performed on the butt joint portion 13 of the upper and lower members 11 and 12 by using a TIG welding torch 14 having a shield cover 15. The upper and lower members 11 and 12 are hollow inside the butt joint portion 13, that is, have a cylindrical shape. Since the upper and lower members 11 and 12 are rotated around the vertical axis in the direction of arrow A by the rotary table, the welding torch 14 moves in the direction of arrow B (welding direction) relative to the upper and lower members 11 and 12. .

A band-shaped shield cover 15 made of an appropriate heat-resistant material is attached to the main body of the welding torch 14 (a portion (details will be described later) including an electrode portion 18 and an auxiliary shield box 19). Have been. The shield cover 15 is wound around the butt joint 13 from the welding torch body to the rear in the welding direction so that the groove 16 is formed.
, The shield gas supplied into the groove 16 is sealed. However, instead of completely shielding the shielding gas, an opening 17 is formed in front of the welding torch main body in the welding direction, and the shielding gas in the groove 16 is discharged from the opening 17. I have.

That is, the welding torch 14 of the first embodiment
The upper and lower members (cylindrical members) together with the welding torch main body have a band-shaped shield cover 15 attached to the welding torch main body.
It moves in the welding direction relatively to 11 and 12,
Butt joint 13 from the welding torch body to the rear in the welding direction
The gas shield arc welding is performed while covering the groove 16 substantially over the entire circumference to seal the shield gas and discharge the shield gas from the opening 17 formed in the welding torch body in the front in the welding direction. Is configured to do so. In this case, by providing the opening 17 in the welding direction front of the welding torch main body, the flow of the shield gas in the shield cover 15 is not disturbed, and a good shield state is maintained. In addition, the welding wire 35 can be supplied to the welding portion from the opening 17 and the arc can be monitored.

The opening 17 is formed forward of the welding torch body in the welding direction because the shielding gas is
This is to ensure that the gas flows backward in the welding direction in the inside 7 and is supplied to the region to be shielded. That is, FIG.
As shown in FIG. 7, since the area to be shielded is the area 34 behind the electrode 18 in the welding direction, if an opening is formed behind the welding torch main body in the welding direction, the shielding gas will pass through this opening. Is discharged, and the shield gas is not sufficiently supplied to the region 34 to be shielded.

The main body of the welding torch 14 is an electrode 18
And an auxiliary shield box 19. As shown in FIG. 4, the electrode portion 18 has a very small thickness t and a wide band width w. By adopting such a shape, the electrode portion 18 can enter the narrow groove 16.

An elongated tungsten electrode 20 is inserted through the center of the electrode portion 18.
The leading end of the projection 0 protrudes from the leading end surface of the electrode portion 18. Also, by increasing the width w of the electrode portion 20,
A water channel 21 and a gas channel 22 are also formed. Therefore, the cooling water supplied from the cooling water supply device (not shown)
1 to cool the tungsten electrode 20. Further, a shield gas (Ar gas) 31 supplied from a shield gas supply device (not shown) flows through the gas passage 22 and passes through the electrode section 2.
0 is blown out into the groove 16.

On the other hand, the auxiliary shield box 19 has a rectangular parallelepiped shape, and a shield gas (Ar gas) 32 supplied from a shield gas supply device (not shown) flows through the gas passage 23 provided in the auxiliary shield box 19. The auxiliary shield box 19 is blown into the groove 16 from the distal end face. The reason why the shielding gas is blown out not only from the electrode portion 18 but also from the auxiliary shield box 19 is to enhance the shielding performance by the shielding gas. The electrode portion 18 and the auxiliary shield box 19 are relatively movable in the radial direction (the direction of arrow C) of the upper and lower members 11 and 12. Specifically, the electrode unit 1
8 penetrates through the central part of the auxiliary shield box 19, and both can slide relatively in the direction of arrow C. Then, the shield cover 15 is attached to the auxiliary shield box 19. In the illustrated example,
Base end of shield cover 15 (auxiliary shield box 1
9 is formed in a truncated quadrangular pyramid shape so as to surround the gap between the auxiliary shield box 19 and the upper and lower members 11 and 12.

Since the electrode portion 18 and the auxiliary shield box 19 are relatively movable, the auxiliary shield box 19 is fixed by a support member (not shown) and the distance between the auxiliary shield box 19 and the upper and lower members 11 and 12 ( With the gap kept constant, only the electrode portion 18 is moved by a moving means (not shown) in accordance with a change in the welding position (the increase in the welding bead in the radial direction of the upper and lower members) due to the progress of welding. 12 can be moved to the outer surface side. That is, only the electrode portion 18 can be moved in the radial direction of the upper and lower members 11 and 12 without changing the position of the auxiliary shield box 19. For this reason, the position of the shield cover 15 attached to the auxiliary shield box 19 is also changed, and the state in which the groove 16 is covered by the shield cover 15 can be maintained.

<Operation / Effect> As described above, according to the first embodiment, the band-shaped shield cover 15 attached to the welding torch main body is connected to the upper and lower members 1 together with the welding torch main body.
The shield gas is sealed by moving in the welding direction relative to the welding parts 1 and 12 and covering the groove 16 of the butt joint 13 from the welding torch body to the rear in the welding direction over substantially the entire circumference. Further, since the gas shield arc welding is performed while the shield gas is discharged from the opening 17 formed forward of the welding torch main body in the welding direction, even if an upward airflow is generated due to preheating of the upper and lower members 11 and 12. The shield cover 15 can prevent the rising airflow from flowing into the groove 16.

Therefore, the butt joint portion 13 can be reliably shielded by the shielding gas, and discoloration of the surface of the weld bead and occurrence of blowhole defects can be prevented. ) Is possible.

That is, as shown in FIG. 6, when the upper and lower members 11 and 12 are preheated by a preheater (not shown) in order to prevent low-temperature cracking during welding, a rising air flow (atmospheric flow) 3 is generated.
3 is generated, and the rising air flow 33 flows into the groove 16 and disturbs the flow of the shielding gases 31 and 32, so that the shield condition of the welded portion is deteriorated, the surface of the weld bead is oxidized, and blowhole defects are generated. appear. Further, since an oxide film is formed on the groove surface of the weld metal, the fluidity of the molten metal is deteriorated, so that poor fusion occurs. In contrast, in the first embodiment, the shield cover 15 attached to the welding torch main body can prevent the updraft 33 from entering, so that discoloration of the surface of the welding bead and occurrence of blowhole defects can be prevented. it can.

By actually using the configuration of the first embodiment and performing welding while supplying Ar gas at a rate of 50 liters / minute as a shielding gas, a good shield state is secured at the welded portion, and the surface of the weld bead is reduced. It was not oxidized and showed silver luster, confirming that the occurrence of welding defects could be prevented.

When the opening 17 was not provided, turbulence occurred in the shield gas in the shield cover 15 and the shield condition at the weld was deteriorated. In addition, when the shield cover 15 was provided with the shield gas supply function, even if the opening 17 was provided, the turbulence was likely to be generated in the shield gas, and the shield state at the welded portion tended to be deteriorated. . Therefore, if the shield cover 15 is not provided with a shield gas supply function, a better shield state can be obtained.

In the first embodiment, the electrode portion 18 and the auxiliary shield box 19 are relatively movable.
5, the electrode part 18 is connected to the upper and lower members 11 and 12.
, The shield cover 15 does not move in the same direction, so the function of the shield cover 15, namely,
The state in which the groove 16 is covered by the shield cover 15 can be maintained.

Second Embodiment FIGS. 7, 8, and 9 are a front view, a longitudinal sectional view, and a cross section showing a method of welding a butt joint according to a second embodiment of the present invention and a configuration of a welding torch used for the method. FIG. 10A and FIG.
(B) is the perspective view and sectional view showing the composition of the shield partition provided in the shield cover. In the second embodiment, a configuration relating to the shield cover is devised in order to perform welding by simultaneously using a plurality of welding torches, and other configurations are the same as those in the first embodiment.
Therefore, in the figure, the same parts as those in the first embodiment are denoted by the same reference numerals, and overlapping detailed description will be omitted.

As shown in FIGS. 7, 8, and 9, in the second embodiment, gas shield arc welding is performed using a plurality of TIG welding torches 14 simultaneously. In the illustrated example, two welding torches 14 are used.
2 are arranged 180 ° apart on both sides in the radial direction.

Each of the welding torches 14 has a band-shaped shield cover 41 attached to the welding torch main body.
Moves in the welding direction (arrow B direction) relatively to the upper and lower members 11 and 12 together with the welding torch main body, and always covers the groove 16 of the butt joint portion 13 backward from the welding torch main body in the welding direction. And an opening 4 formed in front of the welding torch main body in the welding direction.
2. Shield gas is exhausted from the
Gas shielded arc welding is performed while shield gas is prevented from flowing out before and after in the welding direction by shield walls 43 provided at both ends in the welding direction so as to be movable in the radial direction of the upper and lower members 11 and 12. It is configured.

That is, in the first embodiment, one shield cover 15 covers substantially the entire circumference of the groove 16, whereas in the second embodiment, two welding torches 14 are used at the same time. A shield cover 41 attached to each welding torch main body covers the groove 16 substantially half a circumference, and forms an opening 42 in the welding direction front of each welding torch main body. That is, in FIG. 9, the shielding gases 31 and 32 supplied from the right welding torch 14 are discharged from the right opening 42, and the shielding gases 31 and 32 supplied from the left welding torch 14 are removed from the left opening 42. It is to be discharged from. By providing these openings 42, the flow of the shield gases 31, 32 in the respective shield covers 41 is not disturbed, and a good shield state is maintained.

Further, shield partitions 43 are provided at both ends of each shield cover 41 in the welding direction. These shield partitions 43 enter the groove 16 and block the flow of the shield gas. That is,
The shield partition wall 43 prevents the shield gas from flowing out before and after in the welding direction. As a result, the shielding gas 31 supplied from the left and right welding torches 14,
32 can be prevented from being mixed with each other and disturbing the flow (reducing the shielding performance).

As shown in FIGS. 9 and 10, the shield partition wall 43 is guided by guide portions 44 formed at both ends of the shield cover 41, and in the radial direction of the upper and lower members 11 and 12 (in the direction of arrow D). It is freely movable. this is,
Change in welding position with progress of welding, that is, upper and lower members 1
This is because the shield partition wall 43 can move in the same direction in accordance with the increase of the weld beads in the radial direction of the first and the 12th. That is, the shield partition wall 43 moves outward in the radial direction of the upper and lower members so as to be pressed by the welding bead 45.

<Operation / Effect> As described above, according to the second embodiment, the band-shaped shield cover 41 attached to the welding torch main body includes the upper and lower members 1 together with the welding torch main body.
By moving the welding torch relative to the welding torch main body 1 and 12 and always covering the groove 16 of the butt joint portion 13 backward from the welding torch main body in the welding direction, the shield gas is sealed, and Opening 4 formed in front of welding direction
2. Shield gas is exhausted from the
Gas shielded arc welding is performed while shield gas is prevented from flowing out in the welding direction by shield partition walls 43 provided at both ends in the welding direction so as to be movable in the radial direction of the upper and lower members 11 and 12, Upper and lower members 11, 12
Even if an ascending air current is generated by the preheating of this, the inflow of the ascending air current can be prevented by the shield cover 15, and
Since the shield cover 41 is independent for each welding torch by the shield partition 43, it is possible to prevent the shielding gases 31 and 32 of each welding torch 14 from being mixed to generate turbulence (deterioration of shielding performance). it can.

For this reason, in each of the welding torches 14, the welding portion can be reliably shielded by the shielding gas, and the surface of the welding bead is not oxidized, has a silver luster, and the occurrence of welding defects is reliably prevented. Is done. That is,
According to the second embodiment, high-efficiency and high-quality welding using a plurality of welding torches 14 at the same time becomes possible.

[Embodiment 3] FIGS. 11A and 11
(B) It is the longitudinal cross-sectional view and the cross-sectional view which show the welding method of the butt joint which concerns on Embodiment 3 of this invention, and the structure of the welding torch used for it. The third embodiment is the same as the first embodiment except that the welding target and the welding position are different from the first embodiment. Therefore, in the figure, the same parts as those in the first embodiment are denoted by the same reference numerals, and overlapping detailed description will be omitted.

<Structure> As shown in FIG. 11, the objects to be welded in the third embodiment are titanium alloy pipes 51 and 52, which are butt-connected in a horizontal state, and are turned around a horizontal axis by rotating means (not shown). It is rotated in the E direction. The welding posture of the welding torch 14 is vertical, and the welding direction is the arrow F direction.

When welding the titanium alloy tubes 51 and 52, there is no updraft due to preheating, but since the titanium alloy is an active metal, even if the gas shield at the time of welding is only slightly inferior, the titanium alloy tubes 51 and 52 can be welded. Butt joint part 53 of, 52
In this case, a small amount of oxygen or nitrogen in the atmosphere is absorbed, and the weld metal is embrittled, and the surface of the weld bead is changed to blue, black or gray. For this reason, in welding, an auxiliary shield box 19 is provided on the welding torch 14, and the shielding gas 32 is also blown out from the auxiliary shield box 19, thereby performing welding while maintaining a sufficient shield state. However, even if the direction of the welding torch 14 (the direction of the electrode part 18 and the auxiliary shield box 19) is slightly changed, the shielding property is deteriorated.
Advanced skills are required for welding.

Therefore, also in the third embodiment, the shield cover 15 is provided on the welding torch main body as in the first embodiment.

That is, welding torch 14 of the third embodiment.
The belt-shaped shield cover 15 attached to the welding torch main body moves in the welding direction relative to the titanium alloy pipes (cylindrical members) 51 and 52 together with the welding torch main body, and always moves backward from the welding torch main body in the welding direction. The shield gas is sealed by covering the groove 54 of the butt joint part 53 over substantially the entire circumference, and the gas is discharged while discharging the shield gas from the opening 17 formed in the welding torch body in the front in the welding direction. It is configured to perform shield arc welding. In this case, by providing the opening 17 in the welding direction front of the welding torch main body, the flow of the shield gases 31 and 32 in the shield cover 15 is not disturbed, and a good shield state is maintained. In addition, the welding wire 35 can be supplied to the welding portion from the opening 17 and the arc can be monitored. The electrode portion 18 of the welding torch 14 shown in FIG. 11 is not thin because it is not for narrow groove welding.

<Operation / Effect> As described above, according to the third embodiment, the shield cover 15 is attached to the welding torch main body, so that the shield cover 15 can be easily (without requiring advanced skills). The state of the shield gas in the inside can always be kept in a good state. That is, even if the position of the welding torch 14 is slightly changed, the shielded state of the welded portion is favorably maintained by the shield cover 15, so that the titanium alloy pipes 51 and 52 do not require advanced skills. Embrittlement of the weld metal and discoloration of the weld bead surface can be prevented.

The structure of the third embodiment is actually used, and A is used as a shielding gas having a purity of 99.99 vol%.
As a result of performing welding while supplying r gas at about 50 liter / min, it was confirmed that embrittlement of the weld metal and discoloration of the surface of the weld bead could be prevented.

Fourth Embodiment FIGS. 12 and 13 are a perspective view and a vertical sectional view showing a method of welding a butt joint according to a fourth embodiment of the present invention and a configuration of a welding torch used for the method. The fourth embodiment differs from the first and second embodiments in that the welding target is different from the first and second embodiments, and the shape of the shield cover is slightly different depending on the welding target (plate-shaped member). The same is true. Therefore, the same reference numerals are given to the same portions as those in the first and second embodiments in the drawings, and the overlapping detailed description will be omitted.

As shown in FIGS. 12 and 13, in the fourth embodiment, the butt joint portions 63 of the plate members 61 and 62 are connected.
Gas-shielded arc welding. For this reason,
In the first and second embodiments, the shield covers 15 and 41 are arc-shaped, whereas the welding torch 1 of the fourth embodiment is used.
The shield cover 65 provided in 4 has a band shape and a straight shape so as to cover the straight groove 64. The flat members 61 and 62 are moved in the direction of arrow H by moving means (not shown), and the welding torch 14 relatively moves in the direction of arrow I (welding direction).

Further, similarly to the second embodiment, shield partitions 67 are provided at both ends of the shield cover 65 in the welding direction. These shield partitions 67 are provided with a groove 64.
It is inside and is blocking the flow of shielding gas. That is, the shield partition wall 67 prevents the shield gas from flowing out before and after in the welding direction. Also,
The shield partition 67 is guided by guide portions 68 formed at both ends of the shield cover 67, and the flat members 61, 6 are formed.
It is movable in a direction perpendicular to 2 (direction of arrow G). This is a change in the welding position with the progress of welding, that is,
This is because the shield partition wall 67 can move in the same direction as the number of weld beads in the direction perpendicular to the plate members 61 and 62 increases. The shield partition wall 67 moves in a direction (upward in the figure) perpendicular to the flat plate members 61 and 62 so as to be pushed by the welding bead. Further, an opening 66 is formed in the welding torch main body in the front in the welding direction.

That is, welding torch 14 of the fourth embodiment.
The belt-shaped shield cover 65 attached to the welding torch main body includes flat plate members 61 and 62 together with the welding torch main body.
Relative to the welding direction, and always moves backward from the welding torch body in the welding direction.
To shield the shield gas, discharge the shield gas from an opening 66 formed forward of the welding torch body in the welding direction, and further form flat plate members 61 and 62 on both ends of the shield cover 65 in the welding direction. The shield partition 67 movably provided in the vertical direction is configured to perform gas shield arc welding while preventing the shield gas from flowing out before and after in the welding direction. in this case,
By providing the opening 66 in the welding direction front of the welding torch main body, the shielding gas 31 in the shield cover 65,
32 is not disturbed, and a good shield state is maintained. Further, from the opening 66, the welding wire 35 can be supplied to the welding portion, and the arc can be monitored.

<Operation and Effect> According to the fourth embodiment,
With the above configuration, the gas shield of the butt joint portion 63 can be reliably performed by the shield gas, and thus, for example, the plate members 61 and 62 are installed vertically, and the rising airflow due to preheating becomes a problem. Even in the case or when the plate-like members 61 and 62 are made of active metal and even a small amount of air causes a problem, very high-quality welding (defect-free welding) can be performed.

By the way, unlike the cylindrical members, the plate members 61 and 62 have end faces. When welding is to be performed up to these end face positions, the gas shield state is maintained until the end face positions are welded. In order to maintain a good state, as shown by a chain line in FIGS.
An auxiliary plate 70 having a groove 71 having the same shape as the groove 64 of 62
May be arranged at the ends of the plate-shaped members 61 and 62.

In the first to fourth embodiments, the member to be welded is moved. However, the present invention is not limited to this. The torch may be moved.

In the first to fourth embodiments, the shielding gas is also blown out from the auxiliary shield box 19 in order to enhance the shielding performance. However, the present invention is not limited to this. The box 19 may be a simple shield cover mounting portion that does not blow out the shielding gas. That is, the present invention can be applied regardless of whether or not the shield cover mounting portion has the shielding gas blowing function.

In the first to fourth embodiments, the electrode portion 18 and the auxiliary shield box 19 are relatively movable, and the shield covers 15, 41, 65 are attached to the auxiliary shield box 19. , Even if the electrode part 18 is moved, the shield covers 15, 41, 6
5 allows the groove 16, 54, 64 to be maintained in a covered state without moving, but the present invention is not necessarily limited to this, and the member to be welded such as when the groove is shallow is used. When it is not necessary to change the electrode position with respect to (a cylindrical member, a plate member, or the like), a configuration may be employed in which the electrode portion 18 and the auxiliary shield box 19 do not relatively move.

[0056]

As described above, the method for welding a butt joint according to the first aspect of the present invention relates to a welding method for welding a butt joint of a cylindrical member by gas shielded arc welding. By moving the band-shaped shield cover attached to the welding torch main body together with the welding torch main body in the welding direction relative to the cylindrical member,
With this shield cover, the shield gas is always sealed from the welding torch main body by covering the groove of the butt joint part substantially rearward in the welding direction rearward, and formed in front of the welding torch main body in the welding direction. Gas shielded arc welding is performed while discharging the shielding gas from the opening.

The welding torch for a butt joint according to the second invention is a welding torch for welding a butt joint of a cylindrical member by gas shielded arc welding, wherein a band-shaped shield cover attached to the welding torch main body is used for welding. The shield gas is sealed by moving in the welding direction relatively to the cylindrical member together with the torch body, and covering the groove of the butt joint part substantially all the way from the welding torch body to the rear in the welding direction. And, while discharging the shielding gas from the opening formed in the welding direction front of the welding torch body,
It is characterized in that gas shielded arc welding is performed.

Therefore, according to the first or second invention,
The shield cover can reliably prevent air from flowing into the groove. That is, there is a case where the generation of an updraft is caused by preheating the cylindrical member in a state where the cylindrical member is set upright, or a case where the cylindrical member is made of active metal and even a small amount of air is mixed in. However, since the shield cover reliably prevents the inflow of air (such as updraft), the butt joint can be reliably shielded,
Discoloration of the weld bead surface and occurrence of blowhole defects can be prevented, and very high-quality welding (defect-free welding) can be performed.

A butt joint welding method according to a third aspect of the present invention is a welding method for welding a butt joint portion of a cylindrical member by gas shielded arc welding, wherein the welding is performed by simultaneously using a plurality of welding torches. In each welding torch, the band-shaped shield cover attached to the welding torch main body is moved in the welding direction relative to the cylindrical member together with the welding torch main body. The shield gas is sealed by covering the groove of the butt joint.
In addition, the shield gas is discharged from the opening formed in the welding torch main body in the front in the welding direction, and furthermore, the shield gas is provided by the shield partition provided at both ends of the shield cover in the welding direction so as to be movable in the radial direction of the cylindrical member. Gas shielded arc welding is performed while preventing leakage before and after the welding direction.

A welding torch for a butt joint according to a fourth aspect of the present invention is a welding torch for welding a butt joint portion of a cylindrical member by gas shielded arc welding, wherein the welding is performed using a plurality of welding torches simultaneously. In each welding torch, the belt-shaped shield cover attached to the welding torch main body moves in the welding direction relative to the cylindrical member together with the welding torch main body. Sealing the shielding gas by covering the groove of the butt joint part backward, and,
The shield gas is discharged from the opening formed in the front of the welding torch in the welding direction, and furthermore, the shield gas is moved in the welding direction by the shield partition walls provided at both ends of the shield cover in the welding direction so as to be movable in the radial direction of the cylindrical member. Gas shielded arc welding is performed while preventing the gas from flowing out before and after.

Therefore, according to the third or fourth aspect,
The inflow of air (updraft, etc.) into the groove can be prevented by the shield cover, and since the shield cover is independent for each welding torch by the shield partition, the shielding gas of each welding torch is mixed. As a result, it is possible to prevent turbulent flow (shield performance is reduced). For this reason, in each of the welding torches, the welding gas can be reliably shielded by the shielding gas, and the surface of the welding bead is not oxidized, exhibits silver luster, and the occurrence of welding defects is reliably prevented. That is, according to the third or fourth invention, highly efficient and high quality welding using a plurality of welding torches at the same time becomes possible.

The welding method of a butt joint according to a fifth aspect of the present invention is the welding method of welding a butt joint portion of a flat plate member by gas shielded arc welding, wherein the band-shaped shield cover attached to the welding torch body is flattened together with the welding torch. The shield gas is moved in the welding direction relatively to the member, and the shield gas is always sealed by covering the groove of the butt joint part from the welding torch body to the rear in the welding direction with the shield cover. The shield gas is discharged from the opening formed in the front of the main body in the welding direction, and furthermore, the shield gas is moved forward and backward in the welding direction by a shield partition provided at both ends of the shield cover in the welding direction so as to be vertically movable with the flat member. While preventing spills
It is characterized by performing gas shielded arc welding.

A welding torch for a butt joint according to a sixth aspect of the present invention is a welding torch for welding a butt joint of a plate-shaped member by gas shielded arc welding, wherein a band-shaped shield cover attached to the welding torch main body is used for welding. The shield gas is moved by moving the welding torch relative to the flat member together with the torch body, and always covers the groove of the butt joint from the welding torch body to the rear in the welding direction to seal the shielding gas. The shield gas is discharged from the opening formed in front of the welding direction of the shield cover. It is characterized in that gas shielded arc welding is performed while preventing leakage.

Therefore, according to the fifth or sixth aspect,
The shield cover can reliably prevent air from flowing into the groove. That is, there is a case where the generation of an ascending air current is caused by preheating the plate-shaped member in a state where the plate-shaped member is set upright, or a case where the plate-shaped member is made of active metal and even a small amount of air is mixed in. However, since the shield cover reliably prevents the inflow of air (such as updraft), the butt joint can be reliably shielded,
Discoloration of the weld bead and occurrence of blowhole defects can be prevented, and very high-quality welding (defect-free welding) can be performed.

A butt joint welding method according to a seventh aspect of the present invention is the butt joint welding method according to the first, third or fifth aspect, wherein the welding torch main body is perpendicular to the radial direction of the cylindrical member or the plate member. An electrode portion and a seat cover attachment portion are provided so as to be relatively movable in the directions, and a shield cover is attached to the seat cover attachment portion.

The welding torch for a butt joint according to the eighth invention is the welding torch for a butt joint according to the second, fourth or sixth invention, wherein the welding torch main body is perpendicular to the radial direction of the cylindrical member or to the plate member. An electrode portion and a shield cover attaching portion are provided so as to be relatively movable in the direction, and a shield cover is attached to the shield cover attaching portion.

Therefore, according to the seventh or eighth aspect,
Even if the electrode part is moved in the radial direction of the cylindrical member or in the direction perpendicular to the plate-shaped member, the shield cover does not move in the same direction, so the function of the shield cover, that is, the state in which the groove is covered by the shield cover. Can be maintained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a method for welding a butt joint according to Embodiment 1 of the present invention and a configuration of a welding torch used for the method.

FIG. 2 is a longitudinal sectional view showing a method of welding a butt joint according to Embodiment 1 of the present invention and a configuration of a welding torch used for the method.

FIG. 3 is a cross-sectional view showing a method of welding a butt joint according to Embodiment 1 of the present invention and a configuration of a welding torch used for the method.

FIG. 4 is a cross-sectional view of an electrode portion of the welding torch.

FIG. 5 is an explanatory view showing the reason why an opening is provided in the welding torch main body in the front in the welding direction.

FIG. 6 is a longitudinal sectional view showing a state where a shield cover is not attached to the welding torch main body.

FIG. 7 is a front view showing a method of welding a butt joint according to Embodiment 2 of the present invention and a configuration of a welding torch used for the method.

FIG. 8 is a longitudinal sectional view showing a method of welding a butt joint according to Embodiment 2 of the present invention and a configuration of a welding torch used for the method.

FIG. 9 is a transverse sectional view showing a method of welding a butt joint according to Embodiment 2 of the present invention and a configuration of a welding torch used for the method.

FIGS. 10A and 10B are a perspective view and a sectional view showing a configuration of a shield partition provided in a shield cover.

FIGS. 11A and 11B are a longitudinal sectional view and a transverse sectional view showing a method of welding a butt joint according to Embodiment 3 of the present invention and a configuration of a welding torch used for the method.

FIG. 12 is a perspective view showing a method for welding a butt joint according to Embodiment 4 of the present invention and a configuration of a welding torch used for the method.

FIG. 13 is a longitudinal sectional view showing a method of welding a butt joint according to Embodiment 4 of the present invention and a configuration of a welding torch used for the method.

FIG. 14 is a longitudinal sectional view showing an example of a steam turbine rotor having a welding structure.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Turbine rotor 2, 3 Butt joint part 11, 12 Components of turbine rotor (first member,
2nd member) 13 Butt joint part 14 Welding torch 15 Shield cover 16 Groove 17 Opening 18 Electrode part 19 Auxiliary shield box 20 Tungsten electrode 21 Water path 22 Gas path 23 Gas path 31 Shield gas 32 Shield gas 33 Ascending airflow 34 Shield Area to be welded 35 Welding wire 41 Shield cover 42 Opening 43 Shield partition wall 44 Guide part 45 Weld bead 51,52 Titanium alloy pipe 53 Butt joint part 54 Groove 61,62 Plate member 63 Butt joint part 64 Groove 65 Shield cover 66 Opening 67 Shield partition wall 68 Guide part 70 Auxiliary plate 71 Groove

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Katsuhide Castle 2-1-1, Shinhama, Arai-machi, Takasago-shi, Hyogo F-term in Takasago Works, Mitsubishi Heavy Industries, Ltd. (Reference) 4E001 AA03 BB07 CC04 DA01 DA02 DB01 DC01 DD02 LB07 LF02 LH04 NA08 4E081 YG02 YX02

Claims (8)

[Claims] 1. A welding method for welding a butt joint portion of a cylindrical member by gas shielded arc welding, wherein a band-shaped shield cover attached to a welding torch main body is welded together with the welding torch main body in a welding direction relative to the cylindrical member. By moving the shield cover, the shield gas is sealed by covering the groove of the butt joint part almost all around the welding direction rearward from the welding torch body at all times, and the welding direction of the welding torch body is A method for welding a butt joint, wherein gas shielded arc welding is performed while discharging shielding gas from an opening formed in the front. 2. A welding torch for welding a butt joint portion of a cylindrical member by gas shielded arc welding, wherein a band-shaped shield cover attached to the welding torch main body includes:
The shield gas is sealed by moving in the welding direction relative to the cylindrical member together with the welding torch main body, and covering the groove of the butt joint almost all the way from the welding torch main body to the rear in the welding direction. A welding torch for a butt joint, wherein gas shielding arc welding is performed while discharging a shielding gas from an opening formed in a welding direction front of the welding torch main body. 3. A welding method for welding a butt joint of a cylindrical member by gas shielded arc welding, wherein the welding is performed by simultaneously using a plurality of welding torches, and each welding torch is attached to a welding torch main body. Moving the shield cover in the welding direction together with the welding torch body relative to the cylindrical member, and always cover the groove of the butt joint from the welding torch body to the rear in the welding direction with this shield cover. And shield gas is discharged from an opening formed forward of the welding torch body in the welding direction, and further provided at both ends of the shield cover in the welding direction so as to be movable in the radial direction of the cylindrical member. Performs gas shielded arc welding while preventing shield gas from leaking back and forth in the welding direction with a shield partition wall Welding method butt joint, characterized and. 4. A welding torch for welding a butt joint portion of a cylindrical member by gas shielded arc welding, wherein the welding torch is for simultaneously performing welding by using a plurality of welding torches. The band-shaped shield cover attached to the welding torch body moves in the welding direction relative to the cylindrical member together with the welding torch body, and always covers the groove of the butt joint from the welding torch body to the rear in the welding direction. By sealing the shielding gas,
In addition, the shielding gas is discharged from an opening formed in the welding torch main body in the front in the welding direction, and furthermore, the shielding gas is provided by a shielding partition provided at both ends in the welding direction of the shield cover so as to be movable in the radial direction of the cylindrical member. A welding torch for a butt joint characterized by performing gas shielded arc welding while preventing leakage before and after the welding direction. 5. A welding method for welding a butt joint portion of a flat plate member by gas shielded arc welding, wherein a belt-shaped shield cover attached to a welding torch body is moved together with the welding torch in a welding direction relative to the flat plate member. With this shield cover, the shield gas is always sealed by covering the groove of the butt joint part from the welding torch body to the welding direction rearward, and from the opening formed in the welding torch body in the welding direction front. The shield gas is discharged while shielding gas is discharged and furthermore, the shielding partition is provided at both ends in the welding direction of the shield cover so as to be movable in the vertical direction with the flat member, while preventing the shielding gas from flowing out before and after in the welding direction. A method for welding a butt joint, comprising performing arc welding. 6. A welding torch for welding a butt joint portion of a plate-shaped member by gas shielded arc welding, wherein a band-shaped shield cover attached to the welding torch main body comprises:
The shield gas is moved by moving the welding torch main body relative to the flat plate member in the welding direction and covering the groove of the butt joint portion from the welding torch main body to the rear in the welding direction at all times to seal the shielding gas, and The shield gas is discharged from the opening formed in the front of the main body in the welding direction, and furthermore, the shield gas is moved forward and backward in the welding direction by a shield partition provided at both ends of the shield cover in the welding direction so as to be vertically movable with the flat member. A butt joint welding torch characterized in that gas shielded arc welding is performed while preventing gas from flowing out to the butt joint. 7. An electrode according to claim 1, wherein the welding torch main body is provided so as to be relatively movable in a radial direction of the cylindrical member or in a direction perpendicular to the flat member. And a seat cover attaching portion, and a shield cover is attached to the seat cover attaching portion. 8. The welding torch according to claim 2, 4 or 6, wherein the welding torch body is provided so as to be relatively movable in a radial direction of the cylindrical member or in a direction perpendicular to the flat member. And a shield cover mounting portion, wherein the shield cover is mounted on the shield cover mounting portion.