JP6873859B2 - Welding equipment and welding method - Google Patents

Description

Embodiments of the present invention relate to welding torches, welding devices and welding methods.

For the purpose of preventing wear caused by sliding and adhesion of oxide scale to parts such as seats and sliding parts used in steam valves for steam turbines installed in thermal power plants, etc. Overlay welding of Stellite is performed on the base metal. For example, in a cylindrical part such as a guide sleeve of a reheating valve or a valve stem bush, stellite is built up so that a spiral weld bead is formed on the cylindrical surface of the part serving as a base material.

Such steam valve parts are manufactured through processes such as a material annealing process, a pre-welding process, a welding process for overlay welding, an annealing process, a non-destructive inspection process, and a finishing machining process. Among them, the welding process occupies a lot of time. In particular, in recent years, steam turbines in which the main steam exceeds 600 ° C. have been manufactured, and in this case, the capacity of the steam valve also increases in order to increase the output. As a result, parts such as guide sleeves are also increased in size, and the welding time is also increased accordingly.

Here, a general method of overlay welding will be described with reference to FIG. As shown in FIG. 9, the head portion 101 of a general welding torch 100 is provided with one arc generating portion 102. When overlay welding is performed using such a welding torch 100, the welding torch 100 is continuously moved in a direction along the central axis of the cylindrical surface 103 while continuously rotating the parts to be welded. At this time, the arc generation unit 102 generates an arc while weaving. As a result, the weld bead 104 formed by the arc is spirally formed on the cylindrical surface 103. In the weld bead 104, a spiral weld bead 104 is continuously formed from one end to the other end. For this reason, a lot of time was spent on overlay welding. Furthermore, in order to prevent poor penetration from occurring between the weld beads 104 adjacent to each other, the weld bead 104 is formed so as to partially overlap the immediately preceding weld bead 104, and this point is also welded. This is the cause of the lengthening of time.

If a large amount of time is spent on overlay welding in this way, there is a problem that the manufacturing time of parts becomes long as a result.

Japanese Unexamined Patent Publication No. 2012-130934 Japanese Unexamined Patent Publication No. 2009-078274

The present invention has been made in consideration of such a point, and provides a welding torch, a welding device, and a welding method capable of shortening the welding time for performing overlay welding on the cylindrical surface of a welding object. The purpose is to do.

The welding torch according to the embodiment is a welding torch that moves in a direction along the central axis of the cylindrical surface of the object to be welded and performs overlay welding on the cylindrical surface. This welding torch includes a stem portion and a head portion provided at the tip end portion of the stem portion. The head portion has a plurality of arc generating portions, each of which generates an arc. The plurality of arc generating portions are arranged at different positions from each other in the moving direction of the welding torch.

Further, the welding apparatus according to the embodiment is a welding apparatus that performs overlay welding on the cylindrical surface of the object to be welded. This welding device includes the above-mentioned welding torch, a rotary drive unit for rotating the welding object, and a torch drive unit for moving the welding torch in a direction along the central axis of the cylindrical surface.

Further, the welding apparatus according to the embodiment is a welding apparatus that performs overlay welding on the cylindrical surface of the object to be welded. This welding device moves a pair of welding torches, each having an arc generating portion for generating an arc, a rotational driving portion for rotating a welding object, and a corresponding welding torch in a direction along the central axis of the cylindrical surface. It includes a pair of torch drive units and a control unit. The circular control unit transfers one welding torch from the first end region arranged on one side in the direction along the central axis of the build-up welding region performed on the cylindrical surface to the second arranged on the other side. A pair of torch drives to move the welding torch along the central axis toward the end region and the other welding torch along the central axis from the second end region to the first end region. Control the part.

Further, the welding method according to the embodiment is a welding method in which overlay welding is performed on the cylindrical surface of the welding target using the above-mentioned welding torch. In this welding method, first, an arc is generated by each arc generating portion of the welding torch, and a first main bead that makes one round in the circumferential direction is formed on the cylindrical surface of the welding object. Subsequently, the welding torch is moved in the direction along the central axis of the surface of the cylinder. After that, an arc is generated by each arc generating part of the welding torch, and a second main bead that makes one circumference in the circumferential direction is formed at a different position on the cylindrical surface in the direction along the central axis with respect to the first main bead. Will be done.

Further, the welding method according to the embodiment is a welding method in which overlay welding is performed on the cylindrical surface of a welding object by using a pair of welding torches each having an arc generating portion for generating an arc. In this welding method, one welding torch is arranged from the first end region arranged on one side of the area of overlay welding performed on the cylindrical surface in the direction along the central axis of the cylindrical surface to the other. It is provided with a step of moving the weld bead toward the second end region in the direction along the central axis and generating an arc by the arc generating portion of the one welding torch to form a welding bead on the cylindrical surface of the welding object. ing. Further, in this welding method, the other welding torch is moved from the second end region to the first end region in the direction along the central axis, and an arc is generated by the arc generating portion of the other welding torch. It is provided with a step of forming another welding bead on the cylindrical surface of the object to be welded.

According to the present invention, it is possible to shorten the welding time for performing overlay welding on the cylindrical surface of the object to be welded.

FIG. 1 is a diagram showing a schematic configuration of a welding apparatus according to the first embodiment. FIG. 2 is a plan view of the head portion of the welding torch shown in FIG. 1 as viewed from the welding target body. FIG. 3 is a cross-sectional view showing a schematic configuration of a head portion of the welding torch shown in FIG. FIG. 4 is a diagram for explaining a start-end bead forming step in the welding method according to the first embodiment. FIG. 5 is a diagram for explaining a first main bead forming step in the welding method according to the first embodiment. FIG. 6 is a diagram for explaining a second main bead forming step in the welding method according to the first embodiment. FIG. 7 is a diagram showing a schematic configuration of a welding apparatus according to the second embodiment. FIG. 8 is a view of the welding torch shown in FIG. 7 viewed from the left side of FIG. 7 in a direction along the central axis of the surface of the cylinder. FIG. 9 is a diagram for explaining a welding method using a general welding torch.

Hereinafter, the welding torch, the welding apparatus, and the welding method according to the embodiment of the present invention will be described with reference to the drawings.

(First Embodiment)
The welding torch, the welding apparatus, and the welding method according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 7. Here, the welding torch and the welding apparatus provided with the welding torch according to the present embodiment are made of cylindrical parts (hereinafter, referred to as welding objects) such as a guide sleeve and a valve rod bush constituting a steam valve for a steam turbine. This is for overlay welding the surface of a cylinder.

As shown in FIG. 1, the welding apparatus 10 moves a welding torch 20 that generates an arc for overlay welding, a positioner 11 (rotational drive unit) that rotates the welding object 1, and a welding torch 20. A torch drive unit 12 and a control unit 14 are provided. Of these, the welding torch 20 is arranged above the cylindrical surface 2, especially directly above the central axis 3 of the cylindrical surface 2.

The positioner 11 is configured to hold one end of the cylindrical surface 2 in the direction along the central axis 3 and rotate the welding object 1 around the central axis 3. The weld target body 1 rotates in the clockwise direction when viewed from the left side of FIG. A support 13 is provided on the opposite side of the positioner 11. The support 13 rotatably supports the other end of the welding object 1. The cylindrical surface 2 of the welding object 1 is attached to the welding device 10 by the positioner 11 and the support 13 so that the central axis 3 is horizontal.

The torch drive unit 12 is configured to move the welding torch 20 in a direction (parallel direction) along the central axis 3 of the cylindrical surface 2. In this way, overlay welding can be performed on a desired region with respect to the cylindrical surface 2. The region where the overlay welding is performed is referred to as a welding region 4. The welding region 4 is a first end region 5 arranged on one side (left side in FIG. 1) and a second end portion arranged on the other side (right side in FIG. 1) in the direction along the central axis 3 of the cylindrical surface 2. It has a region 6 and. That is, overlay welding is performed from the first end region 5 to the second end region 6.

Next, the welding torch 20 will be described in more detail.

As shown in FIG. 1, the welding torch 20 includes a stem portion 21 and a head portion 22 provided at the tip end portion of the stem portion 21. Of these, the stem portion 21 is connected to the torch drive portion 12, and the welding torch 20 is moved by the torch drive portion 12. The stem portion 21 shown in FIG. 1 and the like has a longitudinal direction, and in the welding apparatus 10, this longitudinal direction is along the moving direction of the welding torch 20.

As shown in FIGS. 1 to 3, the head portion 22 has a plurality of arc generating portions 23A to 23C, each of which generates an arc (three in the present embodiment), and a shield gas supply hole 24. ing. The three arc generating portions 23A to 23C are arranged at different positions from each other in a predetermined direction, that is, in the moving direction of the welding torch 20 (longitudinal direction of the welding torch 20). Here, the first arc generating portion 23A, the second arc generating portion 23B, and the third arc generating portion 23C are arranged in this order along the moving direction of the welding torch 20 (from the left side to the right side in FIG. 1). An example of this will be described. That is, the first arc generating portion 23A is located on the side opposite to the moving direction of the welding torch 20, and the third arc generating portion 23C is located on the side in the moving direction of the welding torch 20. The second arc generating section 23B is located between the first arc generating section 23A and the third arc generating section 23C.

In the present embodiment, the arc generating units 23A to 23C are configured to generate the plasma arc A. That is, the arc generating portions 23A to 23C supply a plurality of powders P to the arc ejection holes 25A to 25C for ejecting the plasma arc A and the plasma arcs A ejected from the corresponding arc ejection holes 25A to 25C. The supply holes 32A to 32C are included. More specifically, the first arc generating section 23A includes an arc ejection hole 25A and a powder supply hole 32A, and the second arc generating section 23B includes an arc ejection hole 25B and a powder supply hole 32B. The third arc generation unit 23C includes an arc ejection hole 25C and a powder supply hole 32C.

As shown in FIG. 3, a pilot gas supply path 26 communicates with the arc ejection holes 25A to 25C, and the pilot gas is supplied from a pilot gas supply source (not shown). The supply of pilot gas is controlled by the control unit 14, which will be described later. Further, an arc electrode 27 is provided in the arc ejection holes 25A to 25C. The arc electrode 27 is connected to the positive electrode of the arc power source 28. The negative electrode of the arc power source 28 is connected to the welding object 1.

A pilot gas nozzle 29 is formed around the arc electrode 27. The pilot gas nozzle 29 defines the pilot gas supply path 26 described above. The arc ejection holes 25A to 25C described above are formed at the tip of the pilot gas nozzle 29. Further, a cooling water flow path 30 is provided in the pilot gas nozzle 29, and the pilot gas nozzle 29 (particularly, the tip portion thereof) is cooled by the cooling water flowing through the cooling water flow path 30. The pilot gas nozzle 29 is connected to the negative electrode of the pilot power supply 31. The positive electrode of the pilot power supply 31 is connected to the arc electrode 27 described above.

A powder supply source (not shown) and a carrier gas supply source (not shown) are connected to the powder supply holes 32A to 32C, and the powder P is supplied along with the carrier gas. The powder P is a build-up material formed on the cylindrical surface 2 of the welding object 1, and for example, stellite is preferably used. The supplied powder P is ejected in a direction inclined toward the plasma arc A ejected from the corresponding arc ejection holes 25A to 25C. The supply of the powder P and the supply of the carrier gas are controlled by the control unit 14 described later.

As shown in FIG. 2, the powder supply holes 32A to 32C are arranged around the pilot gas nozzle 29. In the present embodiment, four powder supply holes 32A to 32C are provided around one arc ejection hole 25A to 25C. That is, the four powder supply holes 32A are provided around the arc ejection holes 25A of the first arc generating portion 23A, and the four powder supply holes 32B are around the arc ejection holes 25B of the second arc generating portion 23B. The four powder supply holes 32C are provided around the arc ejection holes 25C of the third arc generation unit 23C. The powder supply holes 32A to 32C are evenly arranged in the circumferential direction of the corresponding arc ejection holes 25A to 25C.

As shown in FIGS. 2 and 3, the arc ejection holes 25A to 25C of the arc generating portions 23A to 23C are arranged at different positions in the moving direction of the welding torch 20. In the present embodiment, the three arc ejection holes 25A to 25C are linearly arranged parallel to the moving direction of the welding torch 20.

The shield gas supply hole 24 described above is configured to supply the shield gas around the plasma arc A generated by the arc generation units 23A to 23C. As shown in FIGS. 2 and 3, the shield gas supply hole 24 is provided so as to surround the three arc generating portions 23A to 23C. In other words, the arc ejection holes 25A to 25C and the powder supply holes 32A to 32C constituting the three arc generating portions 23A to 23C are arranged inside the shield gas supply hole 24.

The control unit 14 shown in FIG. 1 controls the positioner 11 and the torch drive unit 12 described above. After positioning the welding torch 20 in the first end region 5, the control unit 14 positions the starting bead forming step, the first main bead forming step, the torch moving step, the second main bead forming step, and the ending bead forming. It is configured to perform the process.

The control unit 14 in the start end bead forming step welds while generating plasma arc A by the first arc generation unit 23A of the three arc generation units 23A to 23C of the welding torch 20 located in the first end region 5. The positioner 11 is controlled so that the object body 1 is rotated once to form a start-end bead 40 that makes one round in the circumferential direction on the cylindrical surface 2. During this time, the welding torch 20 is not moved by the torch drive unit 12. Further, during this period, it is preferable that no arc is generated from the remaining two arc generating units 23B and 23C. After the starting bead forming step, the first main bead forming step is performed without moving the welding torch 20.

The control unit 14 in the first main bead forming step rotates the welding target body 1 once while generating plasma arcs A by the arc generating units 23A to 23C of the welding torch 20, and forms the cylindrical surface 2 of the welding target body 1. The positioner 11 is controlled so as to form the first main bead 41 that makes one revolution in the circumferential direction. During this time, the welding torch 20 is not moved by the torch drive unit 12.

Subsequently, as a torch moving step, the control unit 14 controls the torch driving unit 12 to move the welding torch 20 in the direction along the central axis 3 of the cylindrical surface 2. After that, as the second main bead forming step, the control unit 14 rotates the welding target body 1 once while generating the plasma arc A by the arc generating units 23A to 23C of the welding torch 20, and makes one revolution in the circumferential direction. The positioner 11 is controlled so as to form the second main bead 42. The second main bead 42 is formed at a different position on the cylindrical surface 2 in the direction along the central axis 3 with respect to the first main bead 41. During this time, the welding torch 20 is not moved by the torch drive unit 12.

By the way, the control unit 14 sets the moving distance of the welding torch 20 in the above-mentioned torch moving process to the first arc generating unit 23A and the third arc generating unit 23C among the three arc generating units 23A to 23C of the welding torch 20. Let the pitch dimension D between them (see FIG. 2).

Further, the control unit 14 may have an input unit and an arc generation unit selection unit. Of these, the input unit inputs the region length L (see FIG. 1) in the direction along the central axis 3 of the welding region 4 and the moving distance of the welding torch 20 (that is, the pitch dimension D shown in FIG. 2). It is configured in. The arc generation unit selection unit selects an arc generation unit to generate an arc when forming a terminal bead (not shown) described later based on the region length L and the movement distance input to the input unit. It is configured as follows.

Next, the operation of the present embodiment having such a configuration will be described. Here, a welding method using the above-mentioned welding apparatus 10 will be described.

First, as shown in FIG. 4, one end of the welding object 1 is held by the positioner 11 of the welding apparatus 10, and the other end of the welding object 1 is supported by the support 13 (see FIG. 1). Weld.

Subsequently, the welding torch 20 is positioned in the first end region 5.

Next, as a starting bead forming step, the starting bead 40 is formed. In this case, the plasma arc A is ejected from the arc ejection hole 25A of the first arc generating portion 23A of the welding torch 20 located in the first end region 5. During this time, the powder P is supplied from the powder supply hole 32A toward the ejected plasma arc A. As a result, the powder P is melted in the plasma arc A, and the melted powder material is sprayed onto the cylindrical surface 2 of the welding object 1. On the cylindrical surface 2 on which the molten powder material is sprayed, the base material of the welding object 1 is partially melted to form a molten pool (not shown) in which the powder material and the base material are mixed. .. Further, while the plasma arc A is ejected, the positioner 11 is driven to rotate the welding object 1 once. As the welding target body 1 rotates, the molten material solidifies in the portion of the molten pool formed on the cylindrical surface 2 away from the plasma arc A. When the welding target body 1 makes one rotation, a start-end bead 40 that makes one revolution in the circumferential direction is formed on the cylindrical surface 2 of the welding target body 1. The starting bead 40 is a weld bead formed by the plasma arc A ejected from the arc ejection hole 25A.

After the starting bead forming step, as shown in FIG. 5, the first main bead forming step is performed without moving the welding torch 20, and the first main bead 41 is formed. In this case, plasma arc A is ejected from the three arc ejection holes 25A to 25C of the welding torch 20 still located in the first end region 5, and corresponds to the ejected plasma arc A. The powder P is supplied from the powder supply holes 32A to 32C. While the plasma arc A is ejected, the positioner 11 is driven to rotate the welding object 1 once. As a result, the first main bead 41 that makes one round in the circumferential direction is formed on the cylindrical surface 2 of the welding object 1. The first main bead 41 is a weld bead formed by plasma arcs A ejected from three arc ejection holes 25A to 25C, and is a width W1 of the first main bead 41 (dimensions in the direction along the central axis 3). Is larger than the width W0 of the starting bead 40 shown in FIG.

By the way, the plasma arc A ejected from the arc ejection holes 25A to 25C of each arc generating portion 23A to 23C diffuses as it approaches the cylindrical surface 2 like a jet jet. Here, a part of the plasma arc A ejected from the arc ejection hole 25A and a part of the plasma arc A ejected from the arc ejection hole 25B overlap each other and reach the cylindrical surface 2. Similarly, a part of the plasma arc A ejected from the arc ejection hole 25B and a part of the plasma arc A ejected from the arc ejection hole 25C overlap each other and reach the cylindrical surface 2. That is, the distance between the welding torch 20 and the cylindrical surface 2 is set so that the plasma arcs A generated by the arc generating portions 23A to 23C adjacent to each other partially overlap each other on the cylindrical surface 2. In this way, the first main bead 41 is used as a continuous welding bead, and a portion having poor penetration is prevented from being formed in the first main bead 41.

Further, a part of the first main bead 41 overlaps with the start bead 40. That is, as described above, after the starting bead 40 is formed, the first main bead 41 is formed without moving the welding torch 20. As a result, in the first main bead forming step, the arc ejection hole 25A is positioned at the position where the plasma arc A was ejected during the starting bead forming step. Therefore, the starting bead 40 is melted again while being supplied with the powder P melted by the plasma arc A ejected from the arc ejection hole 25A of the first main bead 41, and becomes a part of the first main bead 41. It is solidified. In this way, the thickness of the overlay in the first end region 5 is secured, and the machining allowance at the time of finishing machining after overlay welding is secured. The above-mentioned starting bead 40 is sometimes called a bank heap.

After the first main bead forming step, a torch moving step is performed to move the welding torch 20 as shown in FIG. In this case, the welding torch 20 moves in the direction along the central axis 3 of the cylindrical surface 2 of the welding object 1. The moving distance of the welding torch 20 in the torch moving step is the pitch dimension D (see FIG. 2) between the arc ejection holes 25A and the arc ejection holes 25C among the three arc ejection holes 25A to 25C of the welding torch 20. Therefore, the arc ejection hole 25A after the torch moving step is positioned at the position of the arc ejection hole 25C before the torch moving step.

After the torch moving step, as shown in FIG. 6, a second main bead forming step is performed to form the second main bead 42. In this case, plasma arc A is ejected from the three arc ejection holes 25A to 25C of the welding torch 20, and powder P is ejected from the powder supply holes 32A to 32C corresponding to the ejected plasma arc A. Be supplied. While the plasma arc A is ejected, the positioner 11 is driven to rotate the welding object 1 once. As a result, the second main bead 42 that makes one round in the circumferential direction is formed on the cylindrical surface 2 of the welding object 1. The second main bead 42 is formed at a position ahead of the first main bead 41 in the moving direction of the welding torch 20. The second main bead 42 is a weld bead formed by plasma arcs A ejected from the three arc ejection holes 25A to 25C, and has a width substantially the same as the width W1 of the first main bead 41 shown in FIG. .. Similar to the first main bead 41, the second main bead 42 is a plasma ejected from arc ejection holes 25A to 25C adjacent to each other in order to prevent a portion having a poor penetration from being formed inside. The arc A is adapted to partially overlap on the cylindrical surface 2.

,
By the way, a part of the second main bead 42 overlaps with the first main bead 41. That is, the arc ejection hole 25A in the second main bead forming step is positioned at the position of the arc ejection hole 25C in the first main bead forming step. Therefore, the portion of the first main bead 41 formed by the plasma arc A ejected from the arc ejection hole 25C is the powder melted by the plasma arc A ejected from the arc ejection hole 25A of the second main bead 42. While the body P is supplied, it melts again and is solidified as a part of the second main bead 42. In this way, it is prevented that a portion having poor penetration is formed between the first main bead 41 and the second main bead 42.

The torch moving step and the second main bead forming step described above are repeated a plurality of times according to the region length L of the welding region 4. As a result, a plurality of second main beads 42 are formed at different positions in the direction along the central axis 3, and continuous welding beads are formed over the entire welding region 4.

When the welding torch 20 reaches the second end region 6, the terminal bead forming step is performed. In this case, the arc generation unit selection unit of the control unit 14 selects the arc generation unit to generate the plasma arc A. More specifically, the region length L in the direction along the central axis 3 of the welding region 4 and the moving distance of the welding torch 20 are input in advance in the input unit of the control unit 14, and the region length L is defined as the region length L. The arc generating part is selected based on the moving distance. For example, the arc generating portion is selected so that a weld bead having a width equal to or larger than the remainder value (residual distance) obtained by dividing the region length L by the moving distance can be formed. Here, if the remaining distance is equal to or less than the width of the weld bead that can be formed by the plasma arc A from one arc generating portion, the second arc generating portion 23B and the third arc generating portion are generated as the arc generating portions to generate the arc. Part 23C is selected. Further, if the remaining distance is larger than the width of the weld bead that can be formed by the plasma arc A from one arc generating portion, the first arc generating portion 23A and the second arc generating portion are the arc generating portions to generate the arc. 23B and the third arc generator 23C are selected.

The terminal bead is formed by generating the plasma arc A by the arc generating portion selected as described above. The formed terminal bead is formed so as to overlap at least a portion of the second main bead 42 formed immediately before, which is formed by the plasma arc A ejected from the arc ejection hole 25C. In this way, it is prevented that a portion having poor penetration is formed in the build-up in the second end region 6.

In this way, a continuous welding bead is formed over the entire welding region 4, and the overlay welding operation is completed.

As described above, according to the present embodiment, the head portion 22 of the welding torch 20 is provided with three arc generating portions 23A to 23C, and the three arc generating portions 23A to 23C are the moving directions of the welding torch 20. Are placed at different positions in the torch. As a result, three plasma arcs A can be generated, and the width of the welding beads (first main bead 41 and second main bead 42) formed on the cylindrical surface 2 of the welding object 1 can be widened. it can. Therefore, the welding time for performing overlay welding on the cylindrical surface 2 of the welding target body 1 can be shortened. In this case, the manufacturing time of the welding target body 1 can be shortened.

Further, according to the present embodiment, the head portion 22 of the welding torch 20 is provided with a shield gas supply hole 24 so that the three arc generating portions 23A to 23C are arranged inside. As a result, the shield gas can be supplied around the plasma arcs A generated by the three arc generation units 23A to 23C, and even when the three plasma arcs A are generated, the plasma arcs A and the air Contact can be blocked. Therefore, the welding quality can be improved.

Further, according to the present embodiment, first, the plasma arc A is generated by the three arc generating portions 23A to 23C, and the first main bead 41 that makes one round in the circumferential direction is formed on the cylindrical surface 2, followed by Then, the welding torch 20 is moved in the direction along the central axis 3 of the cylindrical surface 2, and then plasma arc A is generated by the three arc generating portions 23A to 23C to make one circumference in the circumferential direction on the cylindrical surface 2. The second main bead 42 is formed. As a result, the second main bead 42 can be formed at a position ahead of the first main bead 41 in the moving direction of the welding torch 20. Therefore, the welding time for performing overlay welding on the cylindrical surface 2 of the welding target body 1 can be shortened.

Further, according to the present embodiment, the moving distance of the welding torch 20 is the first arc generating portion 23A and the third arc generating portion 23A located at both ends in the moving direction of the welding torch 20 among the three arc generating portions 23A to 23C. The pitch dimension D between the arc generating portion 23C and the arc generating portion 23C. As a result, in the portion of the first main bead 41 formed by the plasma arc A generated by the third arc generating portion 23C, the plasma arc A generated by the first arc generating portion 23A of the second main bead 42 causes the portion. The formed portions are formed so as to overlap each other. As a result, it is possible to prevent the formation of a portion having poor penetration between the first main bead 41 and the second main bead 42. Therefore, the welding quality can be improved.

In the above-described embodiment, an example in which the moving distance of the welding torch 20 in the torch moving step is the pitch dimension D between the first arc generating portion 23A and the third arc generating portion 23C has been described. However, the movement distance of the welding torch 20 is not limited to this, and if it is possible to prevent the occurrence of poor penetration, the moving distance of the welding torch 20 is within a range in which the first main bead 41 and the second main bead 42 partially overlap. It can be optional.

Further, in the above-described embodiment, an example in which the plasma arc A is generated by the first arc generating unit 23A to form the starting bead 40 in the starting bead forming step has been described. However, the present invention is not limited to this, and the plasma arc A may be generated by the second arc generating unit 23B when the starting bead 40 is formed. Further, if the processing allowance for finishing machining after overlay welding can be secured, the starting bead forming step does not have to be performed.

Further, in the above-described embodiment, an example in which the head portion 22 of the welding torch 20 is provided with three arc generating portions 23A to 23C has been described. However, the number of arc generating parts is arbitrary.

Further, in the above-described embodiment, an example in which the arc generating units 23A to 23C generate the plasma arc A has been described. However, the present invention is not limited to this, and the arc generating portions 23A to 23C may be configured to perform MAG welding or MIG welding. In this case, the arc generating portions 23A to 23C are configured as wire drawing portions (not shown) for leading out the wire, an arc is generated from the tip of the wire, and the wire material eluted in the arc is applied to the cylindrical surface 2. It is sprayed to form a molten pool and a weld bead is formed.

(Second Embodiment)
Next, the welding torch, the welding apparatus, and the welding method according to the second embodiment of the present invention will be described with reference to FIGS. 7 and 8.

In the second embodiment shown in FIGS. 7 and 8, overlay welding is performed using a pair of welding torches, and one welding torch moves from the first end region to the second end region. However, the main difference is that the other welding torch moves from the second end region to the first end region, and the other configurations are substantially the same as those of the first embodiment shown in FIGS. 1 to 6. Is. In FIGS. 7 and 8, the same parts as those in the first embodiment shown in FIGS. 1 to 6 are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 7, the welding apparatus 10 in the present embodiment includes a pair of welding torches (first welding torch 20A and second welding torch 20B) and a pair of torch drive units (first torch drive unit 12A and first torch drive unit 12A and second). 2 torch drive unit 12B) and. Of these, the first torch drive unit 12A moves the first welding torch 20A in the direction along the central axis 3 of the cylindrical surface 2, and the second torch drive unit 12B moves the first welding torch 20A in the direction along the central axis 3 of the cylindrical surface 2. 2 Move the welding torch 20B. The first welding torch 20A and the second welding torch 20B have the same configuration as the welding torch 20 in the first embodiment.

As shown in FIG. 8, when viewed in the direction along the central axis 3 of the cylindrical surface 2, the vertical straight line (center) of the straight line L1 passing through the arc generating portions 23A to 23C of the first welding torch 20A and the central axis 3 The torch angle θ with respect to the vertical line passing through the axis 3) is less than 45 degrees. Similarly, the torch angle θ of the straight line L2 passing through the arc generating portions 23A to 23C of the second welding torch 20B and the central axis 3 with respect to the vertical line is less than 45 degrees. In the present embodiment, the torch angle θ for the first welding torch 20A is smaller than the torch angle θ for the second welding torch 20B, and in the embodiment shown in FIG. 8, the torch for the first welding torch 20A. The angle θ is 0 degrees. That is, similarly to the welding torch 20 in the first embodiment, the first welding torch 20A is arranged directly above the central axis 3 of the cylindrical surface 2.

The value of the current supplied to the arc electrodes 27 of the arc generating portions 23A to 23C of the second welding torch 20B is the current supplied to the arc electrodes 27 of the arc generating portions 23A to 23C of the first welding torch 20A. Is greater than the value of. The arc power supply 28 that supplies a current to each arc electrode 27 of the first welding torch 20A and the arc power supply 28 that supplies a current to each arc electrode 27 of the second welding torch 20B may be configured separately. Alternatively, using an electric circuit (not shown), a desired value of current is supplied from the same arc power source 28 to each arc electrode 27 of the first welding torch 20A and each arc electrode 27 of the second welding torch 20B, respectively. You may try to do it.

As shown in FIG. 7, the control unit 14 moves the first welding torch 20A from the first end region 5 to the second end region 6 in the direction along the central axis 3. The drive unit 12A is controlled. Similarly, the control unit 14 controls the second torch drive unit 12B so as to move the second welding torch 20B from the second end region 6 toward the first end region 5 in the direction along the central axis 3. To do.

When overlay welding is performed using the welding apparatus 10 according to the present embodiment, the first welding torch 20A has the same as the welding torch 20 in the first embodiment, that is, the starting bead forming step and the first main bead. A forming step, a torch moving step and a second main bead forming step are performed. Of these, in the start-end bead forming step, the start-end bead 40 is formed in the first end region 5, and in the torch moving step, the direction in which the first welding torch 20A is directed from the first end region 5 to the second end region 6. Move to. The torch moving step and the second main bead forming step are repeated a plurality of times. In this way, a continuous weld bead is formed as the first weld torch 20A departs from the first end region 5 and moves towards the central region.

On the other hand, regarding the second welding torch 20B, the starting bead forming step and the first main bead forming are carried out in the same manner except that the moving directions of the welding torch 20 and the second welding torch 20B in the first embodiment are opposite to each other. A step, a torch moving step and a second main bead forming step are performed. Of these, in the start-end bead forming step, the start-end bead 40 is formed in the second end region 6, and in the torch moving step, the direction in which the second welding torch 20B is directed from the second end region 6 to the first end region 5. Move to. The torch moving step and the second main bead forming step are repeated a plurality of times. In this way, a continuous weld bead is formed as the second weld torch 20B departs from the second end region 6 and moves towards the central region.

As shown in FIG. 8, the plasma arc A generated by the arc generating portions 23A to 23C of the second welding torch 20B is inclined with respect to the vertical line, that is, the arc generating portions 23A to 23C and the central axis 3 are aligned with each other. It is ejected in the direction along the straight line L2. In this case, since the ejection direction of the plasma arc A is inclined at the torch angle θ with respect to the vertical line, the ejected plasma arc A can be eccentric downward due to the influence of gravity. Then, the molten pool formed on the cylindrical surface 2 may be eccentric downward due to the influence of gravity. However, in the present embodiment, as described above, since the value of the current supplied to the arc electrodes 27 of the arc generating portions 23A to 23C of the second welding torch 20B is increased, the arc of the first welding torch 20A More energy than the plasma arc A generated by the generators 23A to 23C is supplied to the cylindrical surface 2. Therefore, the region where the plasma arc A is sprayed is expanded upward, and the region where the molten pool is formed is expanded upward.

Each step of the first welding torch 20A and each step of the second welding torch 20B are performed in parallel. As a result, the main beads 41 and 42 by the first welding torch 20A and the main beads 41 and 42 by the second welding torch 20B are formed in parallel.

After the first welding torch 20A and the second welding torch 20B reach the central region, the second main bead 42 immediately before being formed by the first welding torch 20A and the second immediately before being formed by the second welding torch 20B. If the remaining distance from the main bead 42 is less than or equal to the width of the second main bead 42 that can be formed by either the first welding torch 20A or the second welding torch 20B, 3 of the one welding torch Plasma arcs A are generated by the two arc generation units 23A to 23C to form a connecting bead (not shown). Also in this case, the connecting bead is a portion of the second main bead 42 formed immediately before by the first welding torch 20A and formed by the plasma arc A ejected from the arc ejection hole 25C of the third arc generating portion 23C. And the second main bead formed immediately before by the second welding torch 20B, which is formed so as to overlap the portion formed by the plasma arc A ejected from the arc ejection hole 25C of the third arc generating portion 23C. .. Depending on the remaining distance, the connecting bead may be formed in a plurality of times.

In this way, a continuous welding bead is formed over the entire welding region 4, and the overlay welding operation is completed.

As described above, according to the present embodiment, the head portions 22 of the welding torches 20A and 20B are provided with three arc generating portions 23A to 23C, and the three arc generating portions 23A to 23C are the welding torch 20A. They are arranged at different positions in the moving direction of 20B. As a result, three plasma arcs A can be generated by the welding torches 20A and 20B, and the welding beads (first main bead 41 and second main bead 42) formed on the cylindrical surface 2 of the welding target body 1 can be generated. ) Can be widened. Therefore, the welding time for performing overlay welding on the cylindrical surface 2 of the welding target body 1 can be shortened. In this case, the manufacturing time of the welding target body 1 can be shortened.

Further, according to the present embodiment, the first main bead 41 and the second main bead 42 are formed while the first welding torch 20A moves from the first end region 5 to the second end region 6. At the same time, the first main bead 41 and the second main bead 42 are formed while the second welding torch 20B moves from the second end region 6 to the first end region 5. As a result, the two welding torches 20A and 20B can form continuous welding beads from the first end region 5 and the second end region 6 of the welding region 4 toward the central region, respectively. Therefore, the welding time for performing overlay welding on the cylindrical surface 2 of the welding target body 1 can be further shortened.

Further, according to the present embodiment, when viewed in the direction along the central axis 3 of the cylindrical surface 2, the vertical line L1 passing through the arc generating portions 23A to 23C of the first welding torch 20A and the central axis 3 is vertical. The torch angle θ with respect to the line and the torch angle θ with respect to the vertical line of the straight line L2 passing through the arc generating portions 23A to 23C of the second welding torch 20B and the central axis 3 are less than 45 degrees. As a result, it is possible to prevent the molten pool formed by the plasma arcs A generated by the arc generating portions 23A to 23C from being eccentric downward due to the influence of gravity. Therefore, it is possible to prevent the portion of the molten pool formed on the cylindrical surface 2 away from the plasma arc A from moving downward under the influence of gravity before solidifying, and the weld beads are evenly distributed in the circumferential direction. Can be formed.

Further, according to the present embodiment, the torch angle θ for the first welding torch 20A is smaller than the torch angle θ for the second welding torch 20B, and each arc generating portion of the second welding torch 20B is generated. The value of the current supplied to the arc electrodes 27 of 23A to 23C is larger than the value of the current supplied to the arc electrodes 27 of the arc generating portions 23A to 23C of the first welding torch 20A. Therefore, the energy of the plasma arc A generated by the arc generating portions 23A to 23C of the second welding torch 20B can be increased, and the region where the plasma arc A is sprayed can be expanded upward. Therefore, the melting pool can be expanded upward, and it is possible to prevent the formation of a portion having poor penetration and improve the welding quality.

In the above-described embodiment, an example in which the first welding torch 20A and the second welding torch 20B each have a plurality of arc generating portions 23A to 23C has been described. However, the present invention is not limited to this, and the first welding torch 20A and the second welding torch 20B may have only one arc generating portion as shown in FIG. Also in this case, the welding bead is formed while the first welding torch 20A moves from the first end region 5 to the second end region 6, and the second welding torch 20B is the second end region. A weld bead is formed as it moves from 6 towards the first end region 5. As a result, the two welding torches 20A and 20B can form continuous welding beads from the first end region 5 and the second end region 6 of the welding region 4, respectively, and the cylinder of the welding target body 1 can be formed. The welding time for performing overlay welding on the surface 2 can be shortened. In this case, it is preferable that the welding torches 20A and 20B are continuously moved while the welding target body 1 is continuously rotated, so that the welding beads are spirally formed on the cylindrical surface 2.

According to the above-described embodiment, the welding time for performing overlay welding on the cylindrical surface of the object to be welded can be shortened.

Although embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. This novel embodiment can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

1: Welding object 2: Cylindrical surface 3: Central axis, 4: Welding area, 5: First end area, 6: Second end area, 10: Welding device, 11: Positioner, 12: Torch drive Unit, 12A: 1st torch drive unit, 12B: 2nd torch drive unit, 14: control unit, 20: welding torch, 20A: 1st welding torch, 20B: 2nd welding torch, 21: stem part, 22: head Parts, 23A to 23C: Arc generating part, 24: Shield gas supply hole, 25A to 25C: Arc ejection hole, 32A to 32C: Powder supply hole, 41: 1st main bead, 42: 2nd main bead, A: Plasma arc, D: pitch dimension, L1, L2: straight line, P: powder, θ: torch angle,

Claims (6)

A welding device that performs overlay welding on the cylindrical surface of the object to be welded.
Welding torch and
A rotary drive unit that rotates the welding object and
A torch drive unit that moves the welding torch in a direction along the central axis of the cylindrical surface,
With a control unit
The welding torch
Stem part and
A head portion provided at the tip portion of the stem portion is provided.
The head portion has a plurality of arc generating portions, each of which generates an arc.
The plurality of arc generating portions are arranged at different positions from each other in the moving direction of the welding torch.
First, the control unit rotates the welding target body once while generating the arc by each of the arc generating parts of the welding torch, and makes one round in the circumferential direction around the cylindrical surface of the welding target body. The first main bead is formed, then the welding torch is moved in a direction along the central axis of the cylindrical surface, and then the arc is generated by each of the arc generating portions of the welding torch. The welding object is rotated once to form a second main bead that makes one round in the circumferential direction at different positions on the cylindrical surface in a direction along the central axis with respect to the first main bead. Controls the rotation drive unit and the torch drive unit,
In the control unit, the moving distance of the welding torch is set to the pitch dimension of the pair of arc generating parts located at both ends in the moving direction of the welding torch among the plurality of arc generating parts of the welding torch. to, to control the torch drive unit, welding apparatus. A welding device that performs overlay welding on the cylindrical surface of the object to be welded.
A pair of welding torches and
A rotary drive unit that rotates the welding object and
A pair of torch drive units that move the corresponding welding torch in a direction along the central axis of the cylindrical surface.
With a control unit
The welding torch
Stem part and
A head portion provided at the tip portion of the stem portion is provided.
The head portion has a plurality of arc generating portions, each of which generates an arc.
The plurality of arc generating portions are arranged at different positions from each other in the moving direction of the welding torch.
The control unit is arranged so that one of the welding torches is arranged on the other side from the first end region arranged on one side in the direction along the central axis in the area of overlay welding performed on the cylindrical surface. The welding torch is moved in the direction along the central axis toward the second end region, and the other welding torch is moved in the direction along the central axis from the second end region toward the first end region. Control the pair of the torch drive units so as to
When viewed in a direction along the central axis of the cylindrical surface, the torch angle of the straight line passing through the arc generating portion and the central axis of each of the welding torches is less than 45 degrees with respect to the vertical line.
The torch angle of one of the welding torches is smaller than the torch angle of the other welding torch, and the value of the current supplied to each of the arc generating parts of the other welding torch is determined. greater than the value of current supplied to the arc generating portion of each of said one welding torch, welding apparatus. The head portion further has a shield gas supply hole for supplying shield gas around the arc generated by the arc generating portion.
The welding apparatus according to claim 1 or 2 , wherein a plurality of the arc generating portions are arranged inside the shield gas supply hole. The arc generating unit generates a plasma arc as the arc, and the arc generating unit generates a plasma arc.
The arc generating unit includes an arc ejection hole for ejecting the plasma arc and a plurality of powder supply holes for supplying powder to the plasma arc ejected from the corresponding arc ejection hole. The welding apparatus according to any one of 3 to 3 . This is a welding method in which overlay welding is performed on the cylindrical surface of the object to be welded using a welding torch.
The welding torch includes a stem portion and a head portion provided at a tip portion of the stem portion, and the head portion has a plurality of arc generating portions, each of which generates an arc, and the plurality of arcs are generated. The generating parts are arranged at different positions in the moving direction of the welding torch.
The welding method is
A first main bead forming step of generating the arc by each of the arc generating portions of the welding torch to form a first main bead that makes one round in the circumferential direction on the cylindrical surface of the welding object.
After the first main bead forming step, a torch moving step of moving the welding torch in a direction along the central axis of the cylindrical surface, and a torch moving step.
After the torch moving step, the arc is generated by each of the arc generating portions of the welding torch, and the circumference of the first main bead at different positions on the cylindrical surface in the direction along the central axis. A second main bead forming step of forming a second main bead that makes one round in the direction is provided.
In the torch moving step, the moving distance of the welding torch is the pitch dimension of a pair of arc generating parts located at both ends in the moving direction of the welding torch among the plurality of arc generating parts of the welding torch. , welding method. Overlay welding is performed on the cylindrical surface of the welding target using the pair of the welding torches, and in the torch moving step, one of the welding torches is used for overlay welding on the cylindrical surface. A welding torch that moves in a direction along the central axis from a first end region arranged on one side of the region along the central axis toward a second end region arranged on the other side. The welding method according to claim 5 , wherein the welding method moves from the second end region toward the first end region in a direction along the central axis.

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