JP2016052689A - Welding method and welding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a welding method which can prevent that a welding shield gas is disturbed by a convectional upward current with a bevel as a flow passage when welding rotor discs in downward postures by making them horizontal abut on each other, and a welding device.SOLUTION: In a welding method, two cylindrical members 1 are made to abut on each other with a cylinder axial direction as a horizontal direction, a welding torch 6 is arranged on an upper part of the abutting two cylindrical members 1 in a downward posture so that the cylindrical members are oriented to a bevel 4 which is formed along an external periphery of an abutment face 8, the surroundings of the abutment face 8 are covered with a heater, and heated in advance, and after that, the two cylindrical members 1 are rotated and weld-joined to each other. Partitioning members 7 are arranged so as to separate a peripheral direction of a space in the bevel 4 in positions at a front side and a rear side of the cylindrical members 1 in rotational directions which are apart from an upper part in which the welding torch 6 is arranged by prescribed center angles in the bevel 4 which is formed along an external periphery of the abutment face 8 with cylinder axes of the cylindrical members 1 as centers, and the partitioning members 7 are arranged so as to be turnable with respect to fixed members 13.SELECTED DRAWING: Figure 3

Description

  In the present invention, when a welding torch is arranged in a downward posture on the upper part of a joint part of two tubular members that are horizontally butted, and the joint part is welded by rotating the tubular member while preheating around the joint part. The present invention relates to a welding method and a welding apparatus to be applied.

  A rotor for a turbine or the like is assembled by abutting divided cylindrical members and performing welding on a groove formed around the abutting portion (see Patent Document 1). In Patent Document 1, the rotor disk (cylindrical member) of the steam turbine is abutted with the axis being the vertical direction, and a welding torch is disposed in a horizontal lateral orientation at the abutting portion to perform TIG welding. If a gas shielded arc welding method using a TIG welding torch is used for the first layer welding, high quality welding can be achieved.

Moreover, it is highly efficient if sub-arg arc welding is used after the first layer. Sub-arge arc welding can be performed only for downward welding due to method limitations. In order to perform the first layer by TIG welding and the subsequent processes by sub-arc arc welding, first perform horizontal TIG welding with the rotor vertically set up, and then tilt the rotor horizontally and face downward submerged arc welding. Need to do.
Re-installing a huge rotor from vertical to horizontal takes a lot of man-hours (work volume). In order to make a product quickly, it is better not to move the rotor once installed from the start to the end of welding. Therefore, in order to continuously shift to submerged arc welding, it is desired to establish a method of welding the first layer by abutting the rotor disk with the axis as the horizontal direction and disposing the welding torch in a downward posture at the butted portion.

JP 2010-201507 A (paragraph [0038], FIG. 2)

  When the rotor disk is butted and welded, the periphery of the butted portion is covered with a panel heater or the like, and pre-heat treatment is performed. Then, the air around the rotor is heated by the preheated rotor and thermally expanded. Since the volume of the thermally expanded air increases, the air density around the rotor decreases. Between gases having different densities, buoyancy occurs in the smaller density. That is, buoyancy is generated in the air around the rotor, and the airflow rises upward (convective updraft).

  When the rotor disk is horizontally butted and welded in a downward posture, convective updraft is also generated in the groove of the butted portion. If the groove of the butt portion (joint portion) becomes a passage for the convective updraft, it will cause the welding shield gas to be disturbed during the gas shield arc welding construction. When the welding shield gas is disturbed by the convective updraft, the oxygen concentration in the argon gas around the molten pool increases and oxygen is mixed into the molten metal. The mixing of oxygen into the molten metal increases the possibility of welding defects such as blow holes.

  The present invention has been made in view of such circumstances. When welding a rotor disk in a horizontal position while facing down, welding shield gas is disturbed by a convective updraft having a groove as a flow path. It is an object of the present invention to provide a welding method and a welding apparatus that can prevent this from occurring.

  In order to solve the above-mentioned problems, the present invention has two cylindrical members which are butted so as to face two grooves formed along the outer periphery of the abutting surface, with the cylinder axis direction being abutted horizontally. A welding method in which a welding torch is arranged in a downward posture on the upper part of the member, the periphery of the abutting surface is covered with a heater using electricity or gas as a heat source and preheated, and then the two cylindrical members are rotated and welded together A groove formed along the outer periphery of the abutting surface with the cylindrical axis of the cylindrical member as a center from the upper side where the welding torch is arranged, and the front side in the rotational direction of the cylindrical member; Provided is a welding method in which partition members are arranged so as to separate the circumferential direction of the inner space of the groove at positions apart from each other by a predetermined center angle on the rear side, and the partition members are arranged so as to be rotatable with respect to the fixed member. .

  In addition, the present invention provides a welding torch on the upper part of the abutted two cylindrical members so that the two cylindrical members are abutted with the cylinder axis direction being horizontal, and facing the groove formed along the outer periphery of the abutting surface. Is a welding apparatus for rotating and welding the two cylindrical members after covering and a preheating with a heater or the like that uses electricity or gas as a heat source. Each of the front side and the rear side in the rotational direction of the cylindrical member from the upper part in the groove formed along the outer periphery of the abutting surface around the cylindrical axis of the cylindrical member from the upper part where the welding torch is arranged. Provided is a welding apparatus that includes a partition member installed so as to separate the circumferential direction of the inner space of the groove at a position away from a predetermined center angle, and wherein the partition member is arranged to be rotatable with respect to a fixed member.

  By providing the partition member at a predetermined position in the weld groove, it is possible to prevent the convective updraft generated by the preheating from entering the welded portion, so that the disturbance of the welding shield gas can be reduced. As a result, it is possible to prevent the occurrence of welding defects.

  1 aspect of the said invention WHEREIN: It is preferable to make the said partition member into plate shape, a comb shape, or a brush shape.

By disposing the plate-like partition member at a predetermined position in the groove so that the plate surface faces the groove width direction, it is possible to prevent the convective updraft from entering the welded portion.
Since the teeth of the comb-shaped partition member can be deformed flexibly, the partition member can be installed in the groove so as to be along the groove bottom portion rather than being plate-shaped. Thereby, even when the groove bottom is uneven, it is possible to make it difficult to form a gap on the contact surface between the partition member and the groove. As a result, the degree of adhesion between the partition member and the groove is improved.
Since the brush-like partition member has a structure in which comb teeth are arranged in multiple layers with their positions shifted in the depth direction, the convective updraft can be prevented from entering the welded portion rather than being comb-like. Thereby, the sealing performance of the partition member is improved.

  1 aspect of the said invention WHEREIN: It is preferable to form the said partition member from the material which mainly has a metal.

  By forming the partition member from metal, it is possible to suppress deterioration of the material of the partition member even when the temperature becomes high by welding. Thereby, the soundness of the function as the partition member can be maintained.

  1 aspect of the said invention WHEREIN: It is preferable to fix the said partition member to the said welding torch at the one end part of the said fixing member.

  As welding proceeds in the groove, the weld depth accumulates at the groove bottom, and the groove depth gradually decreases. By fixing the partition member to the welding torch, the partition member can move following the welding torch. Thereby, since the welding operator can cope with the change in the groove depth only by adjusting the height position of the welding torch as before, it is not necessary to control the height position of the partition member.

  1 aspect of the said invention WHEREIN: It is preferable that the said partition member is urged | biased by the elastic member in the other end part of the said fixing member.

  The partition member can be pressed at two points by fixing the partition member to be rotatable and connecting the fixing member and the partition member by an elastic member on the welding torch side. Moreover, by connecting with an elastic member, a partition member can be along with the welding groove | channel in the cylindrical member from which a diameter differs with an appropriate angle. As a result, the welding operator does not need to control the angle of the partition member.

  The present invention can prevent the welding shield gas from being disturbed by the convective updraft using the groove as a flow path when the cylindrical members are horizontally butted and welded in a downward posture.

It is a side view of the rotor for turbines after an assembly. It is an enlarged view of the butt | matching part of the state which butt | matched the rotor disk before welding construction. It is sectional drawing of the butt | matching part by which the welding apparatus which concerns on this embodiment is arrange | positioned. It is a graph which shows the result of oxygen concentration analysis. It is a contour figure of the velocity vector of a convective updraft. It is an image figure of the clearance gap produced between a groove and a partition member. It is an image figure of the comb-shaped partition member pressed against the groove. It is an image figure where the partition member is pinched | interposed into the groove | channel. It is a figure which shows the example of fixation of a partition member. It is a figure which shows the example of installation of an elastic member.

  Hereinafter, an embodiment of a welding method and a welding apparatus according to the present invention will be described by taking as an example the assembly of a rotor for a turbine such as a gas turbine or a steam turbine. FIG. 1 shows a side view of the turbine rotor after assembly. In FIG. 1, the description of the blades on the rotor surface is omitted for the sake of simplicity. The rotor for a turbine has a configuration in which a plurality of rotor disks (cylindrical members) 1 are coaxially butted and arranged, and the butted portion 2 is welded to join the rotor disks.

  In the welding method according to the present embodiment, first, the two rotor disks 1 to be welded are arranged to face each other with the cylinder shaft 3 being horizontal. In FIG. 2, the enlarged view of the butting | matching part 2 of the state which butted the rotor disk before welding construction is shown. A groove 4 is formed in the butting portion 2 of the rotor disk 1 along the outer periphery of the butting surface. Next, the periphery of the butting portion 2 is covered with a preheating heater 5 such as a heater using electricity or gas as a heat source, and preheat treatment is performed at 150 ° C. to 300 ° C.

  Subsequently, the welding torch is arranged in a downward posture on the top of the rotor disk so that welding can be performed in the groove. In FIG. 3, the cross section (AA cross section of FIG. 3) figure of the butt | matching part by which the welding apparatus which concerns on this embodiment is arrange | positioned is shown. In this embodiment, the gravity direction side (g) of the horizontal rotor disk 1 is defined as the lower side, and the opposite side of the gravity direction is defined as the upper side. With the welding torch 6 fixed, the rotor disk 1 is rotated to perform gas shield arc welding on the groove 4 of the butt portion 2.

  A partition member 7 is disposed in the groove 4 at a predetermined position with the welding torch 6 interposed therebetween so as to separate the circumferential direction of the groove inner space. The partition member 7 is provided on each of the front side and the rear side in the rotational direction of the rotor disk 1. The predetermined position is a position away from the center 9 of the abutting surface 8 by a predetermined center angle with reference to the upper portion of the rotor disk 1 on which the welding torch 6 is disposed. When the abutting surface 8 is circular, the predetermined position is on an arc at a position separated by a central angle of 20 ° to 30 °.

  Here, the effect by providing a partition member is shown. Using a computational fluid dynamics analysis (CFD analysis), an oxygen concentration analysis was performed around the tungsten electrode (10 mm forward, 20 mm rear, 10 mm height) in the case where the partition member was provided. The results are shown in FIG. In the figure, the horizontal axis represents the distance from the wire portion, and the vertical axis represents the oxygen concentration. According to FIG. 4, it was possible to suppress the oxygen concentration around the tungsten electrode by providing the partition member.

  Next, the basis for setting a predetermined position for arranging the partition member will be described. CFD analysis was used to simulate the preheat treatment of the two rotor disks that were butted. The CFD analysis conditions were as follows: wall surface temperature: 180 ° C., ambient environment temperature: 20 ° C., and rotor rotation speed: 2.58 rpm. FIG. 5 shows a contour diagram of the velocity vector of the convective updraft. According to FIG. 5, the speed of the convective updraft increased in the upper part of the groove. Further, according to FIG. 5, it has been clarified that the convective updraft does not peel off from the groove during the ascending process but moves up to the vicinity of the upper portion of the butt portion due to the viscosity of the fluid. According to FIG. 5, the high-speed convective updraft wraps around an arc whose central angle is 20 ° to 30 ° apart from the upper part. From the above results, when the butt surface is circular, the convective updraft can be shielded most effectively by arranging the partition member at a position of 20 ° to 30 ° from the top (upper part) of the circle. .

Next, the welding apparatus according to the present embodiment will be described.
The welding apparatus includes a partition member 7. The partition member 7 may have a plate shape, a comb shape, or a brush shape. For example, the partition member 7a has a structure in which a plate-like shielding portion 11 having a surface corresponding to a groove width and a groove depth is attached to the base portion 10. A partition member (hereinafter referred to as a plate-shaped partition member) 7a having a plate-shaped shielding member is disposed at a predetermined position in the groove 4 so that the plate surface is along the groove width w direction, thereby providing convection. It is possible to prevent the upward airflow from flowing toward the welding torch 6 side.

  For example, the partition member 7 may have a comb-like structure in which the shielding portion 11 is divided into a plurality of teeth along the depth direction d of the groove. In the partition member (hereinafter referred to as a comb-shaped partition member) 7b having the shielding portion 11 in a comb shape, the end portion of the partition member 7b in contact with the groove bottom portion 12 is flexible. When welding is advanced in the groove 4, the bead welded to the groove bottom 12 becomes a wave pattern, and there is a possibility that a gap is formed between the partition member 7 a and the groove bottom 12 as shown in FIG. 6. On the other hand, when the comb-shaped partition member 7b is pressed and inserted into the groove 4, the end of the partition member 7b is deformed as shown in FIG. 7, so that the partition member 7 and the groove 4 are in close contact with each other. Can increase the sex. If there is a gap between the partition member 7 and the groove 4, the speed of the convective updraft passing through the gap increases and the shield gas may be disturbed, but the partition member 7 has a comb shape. As a result, the gap can be reduced as much as possible.

  For example, the partition member 7 may have a brush-like structure in which the teeth obtained by dividing the shielding portion 11 are arranged in multiple layers while shifting the positions in the groove width direction w and the groove circumferential direction x. When the shielding portion 11 is a brush-shaped partition member (hereinafter referred to as a brush-shaped partition member), the sealing performance when pressed against the groove 4 is improved. Further, when welding is advanced into the groove 4, the base material of the rotor disk 1 is deformed by welding heat, the groove width is gradually narrowed, and the partition member 7 is sandwiched between the grooves 4. May fall into an impossible situation (see FIG. 8). On the other hand, by making the partition member 7 into a brush shape, it becomes possible to more reliably block the convective updraft while accommodating changes in the groove width.

  The partition member 7 is preferably formed from a material mainly made of metal. The metal is preferably selected from those having high temperature resistance. When welding is advanced to the groove 4, the groove 4 is in a high temperature state. On the other hand, by forming the partition member 7 from a metal resistant to high temperatures, it is possible to prevent the partition member 7 from being altered by welding heat. The high temperature resistant metal material is SUS304 or the like.

  It is preferable that the partition member 7 is fixed to the welding torch 6 via the fixing member 13. A fixing example is shown in FIG. In FIG. 9A, the fixing member is an L-shaped fixing rod. One end of the fixing rod is fixed to the welding torch. The other end of the fixing rod is fixed to the base 10 of the partition member. The partition member 7 fixed to the welding torch 6 can move following the welding torch 6 (see FIG. 9B).

  When welding is advanced to the groove 4, the weld metal is deposited on the groove bottom 12, so that the groove depth gradually decreases. Therefore, it is necessary to adjust the installation height of the welding torch and the partition member each time corresponding to the change y of the groove depth. When the welding torch 6 and the partition member 7 are independent, the welding operator must adjust the height with respect to each of them, and workability is impaired. On the other hand, by fixing the partition member 7 to the welding torch 6, the welding operator can adjust the height of the partition member 7 incidentally as long as the height of the welding torch 6 is adjusted as usual. . Therefore, workability is not reduced by adding the partition member 7 to the welding apparatus.

  When the partition member 7 is fixed to the fixing member 13, it is preferable to fix the partition member 7 so as to be rotatable. In that case, the base 10 of the partition member 7 and the fixing member 13 may be connected by the elastic member 14 on the welding torch 6 side of the fixing member 13. The elastic member 14 is, for example, a spring. An installation example of the elastic member is shown in FIG. As described above, when welding is advanced to the groove 4, the groove depth d gradually decreases. That is, the radius of the butted portion 2 in which the groove 4 is formed gradually increases. On the other hand, by fixing the partition member 7 to the welding torch so as to be rotatable, the angle of the partition member 7 can be changed in accordance with a change in radius. The elastic member 14 plays a role of pressing the welding torch 6 side of the partition member 7 (see FIG. 10B). Thereby, the welding operator can always keep the partition member 7 at an appropriate angle as long as the height position of the welding torch 6 is adjusted as usual. Therefore, workability is not reduced by adding the partition member 7 to the welding apparatus.

1 Cylindrical member (rotor disc)
2 abutting portion 3 cylindrical shaft 4 groove 5 preheating heater 6 welding torch 7, 7a, 7b partition member 8 abutting surface 9 center of abutting surface 10 base 11 shielding portion 12 groove bottom 13 fixing member 14 elastic member

Claims (10)

Two cylindrical members are butted with the cylinder axis direction horizontal,
A welding torch is arranged in a downward posture on the upper part of the two tubular members butted so as to face the groove formed along the outer periphery of the butting surface,
After covering the periphery of the abutting surface and preheating,
A welding method in which the two cylindrical members are rotated and welded together,
Each of the front side and the rear side in the rotational direction of the cylindrical member from the upper part in the groove formed along the outer periphery of the abutting surface around the cylindrical axis of the cylindrical member from the upper part where the welding torch is arranged. A partition member is arranged at a position away from a predetermined center angle so as to separate the circumferential direction of the inner space of the groove,
The welding method which arrange | positions the said partition member so that rotation with respect to a fixing member is possible.   The welding method according to claim 1, wherein the partition member is fixed to the welding torch at one end portion of the fixing member.   The welding method according to claim 1, wherein the partition member is urged by an elastic member at the other end portion of the fixing member.   The welding method according to any one of claims 1 to 3, wherein the partition member has a plate shape, a comb shape, or a brush shape.   The welding method according to claim 1, wherein the partition member is formed from a material mainly made of metal. Two cylindrical members are butted with the cylinder axis direction horizontal,
A welding torch is arranged in a downward posture on the upper part of the two tubular members butted so as to face the groove formed along the outer periphery of the butting surface,
After covering the periphery of the abutting surface and preheating,
A welding device for rotating and welding the two cylindrical members,
Each of the front side and the rear side in the rotational direction of the cylindrical member from the upper part in the groove formed along the outer periphery of the abutting surface around the cylindrical axis of the cylindrical member from the upper part where the welding torch is arranged. A welding apparatus comprising: a partition member installed so as to separate the circumferential direction of the inner space of the groove at a position away from a predetermined center angle, wherein the partition member is arranged to be rotatable with respect to the fixed member.   The welding apparatus according to claim 6, wherein the partition member is fixed to the welding torch at one end of the fixing member.   The welding device according to claim 6 or 7, wherein the partition member is biased by an elastic member at the other end of the fixing member.   The welding apparatus according to any one of claims 6 to 8, wherein the partition member has a plate shape, a comb shape, or a brush shape.   The welding apparatus according to claim 6, wherein the partition member is formed of a material mainly made of metal.

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