Multi-layer build-up welding method, multi-layer build-up welding joint and multi-layer build-up welding layer stacking pattern calculation method

Abstract

The present invention provides a multi-layer build-up welding method capable of forming a welded joint with a good surface of a weld metal while suppressing the generation of a weld bead sag to a minimum even in multi-layer build-up welding in a transverse posture, a multi-layer build-up welding joint formed by the multi-layer build-up welding method, and a multi-layer build-up welding layering pattern calculation method. The weld metal (WL) has a plurality of layers from a back surface (1B) to a surface (1A) of a base material. The plurality of layers include a finished layer (FL) having at least two layers including a final layer (EL), and a base layer (GL) for forming the finished layer (FL). A boundary layer (BL) in the base layer (GL) that becomes a layer adjacent to the finished layer (FL) is formed closer to a surface (1A) of a base material than a position (P UB ) of an upper plate side deposition portion LB ).

Description

Technical Field

[0001] This invention relates to a multi-layer welding method that minimizes weld bead sagging and forms a weld joint with a good weld metal surface in multi-layer welding under lateral orientation, a multi-layer stacked weld joint formed by the multi-layer welding method, and a method for calculating the stacking pattern of multi-layer welding. Background Technology

[0002] Welding processes during structural construction have always aimed for labor-saving and efficiency improvements, leading to an increased application of welding robots in recent years. Furthermore, the increasing size and specialized design of steel structures have resulted in the use of mobile welding robots in on-site welding at construction sites to further reduce labor costs and improve efficiency, increasing opportunities for automated welding in various postures. It's important to note that welding postures include downward, vertical, and lateral postures. Lateral welding is frequently used in column connection welding, resulting in longer weld lengths and potentially higher workloads compared to other postures. Additionally, lateral welding is more challenging due to the tendency of molten metal to sag, leading to poor appearance.

[0003] Among the aforementioned mobile welding robots, especially the 3-axis mobile welding robots widely used in construction sites, most lack a torch angle adjustment mechanism. In this case, welding is performed with a constant torch angle, further increasing the difficulty of welding in lateral positions. Furthermore, when beveling to create U-shaped or V-shaped bevels on the lower plate side, the difficulty of construction makes weld sag particularly prone to occur near the lower plate side, further increasing the difficulty.

[0004] One reason why lateral welding is considered a difficult orientation is the tendency for weld bead sag under the influence of gravity. Once weld bead sag occurs, a good joint appearance is difficult to achieve, necessitating temporary interruption of welding and grinding to straighten the weld bead shape. Furthermore, the likelihood of weld bead sag is also higher in multi-layer weld overlays, sometimes requiring countermeasures such as the use of surface backing materials. It should be noted that grinding and surface backing materials increase production cycle time, which is not preferable from a construction efficiency perspective.

[0005] Patent Document 1 discloses a welding method in which, while oscillating the welding wire in the up-down direction during horizontal welding, the time for the welding wire to move in the down direction is longer than the time for it to move in the up direction, and a magnetic field is applied to the molten pool during welding to generate a stirring force in the direction that pushes the molten metal up, thereby forming a flat weld bead.

[0006] In addition, Patent Document 2 describes an automatic welding method in which at least three sets of wire feeders are arranged in the welding head along the axial direction of the welding wire. The central wire feeder is offset in the vertical direction relative to the axis connecting the two outer sets of wire feeders, thereby feeding the wire while adding a vertical bending tendency, and welding the upper or lower surface of the bevel joint.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 63-108973

[0010] Patent Document 2: Japanese Patent Application Publication No. 8-309524 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] However, the welding methods disclosed in Patent Documents 1 and 2 require additional specialized devices such as a dedicated magnetic field generating device to generate a pushing force on the molten metal and a wire feeding device that feeds the wire while simultaneously applying a bending tendency in the vertical direction. This results in increased setup time and equipment costs. Furthermore, the use of automated machines leads to larger devices, making them particularly difficult to apply to lightweight and compact mobile welding robots or welding devices with trolleys as their movement mechanism, which are preferred from the perspectives of transportability and operability.

[0013] The present invention was made in view of the aforementioned problems, and its object is to provide a multi-layer welding method that can minimize the occurrence of weld bead sagging and form a weld joint with a good surface of weld metal even in multi-layer welding in a lateral orientation, a multi-layer stacked weld joint formed by the multi-layer welding method, and a method for calculating the stacking mode of multi-layer welding.

[0014] Solution for solving the problem

[0015] Therefore, the above-mentioned objective of the present invention is achieved by the following [1] structure of the multilayer welding method.

[0016] [1] A multi-layer welding method for joining a pair of base materials consisting of an upper plate and a lower plate configured to form a bevel, wherein,

[0017] The weld metal has multiple layers from the back side to the surface of the base material.

[0018] The plurality of layers have:

[0019] A completed floor, comprising at least two floors including the final floor; and

[0020] A base layer, located on the back side of the base material closer to the finished layer, and including a boundary layer that becomes the layer adjacent to the finished layer.

[0021] Position P of the upper plate side weld portion in the boundary layer UB The position P of the lower plate side weld portion in the boundary layer LB The boundary layer is formed in a manner close to the surface of the base material.

[0022] Furthermore, the above-mentioned objective of the present invention is achieved by the following [2] structure of the multilayer stacked welding head.

[0023] [2] A multi-layer stacked butt weld joint, which is formed by joining a pair of base materials consisting of an upper plate and a lower plate configured to form a bevel through a weld metal formed by multi-layer overlay welding, wherein,

[0024] The weld metal has multiple layers from the back side to the surface of the base material.

[0025] The plurality of layers have:

[0026] A completed floor, comprising at least two floors including the final floor; and

[0027] A base layer, located on the back side of the base material closer to the finished layer, and including a boundary layer that becomes the layer adjacent to the finished layer.

[0028] The location P of the upper plate-side welded portion in the boundary layer UB The position P of the lower plate side weld portion in the boundary layer LB Approaching the surface of the base material.

[0029] Furthermore, the above-mentioned objective of the present invention is achieved by the following [3] structure of the multilayer welding stacking mode calculation method.

[0030] [3] A method for calculating the stacking mode of multi-layer welding, used to perform the multi-layer welding method described in [1], wherein,

[0031] The construction information includes at least the bevel shape, bevel angle, and thickness of the base material, and is linked to the P. UB Location information, the P LB Location information, and the P UB and the P LB At least two of the relative positional information between them established an associated database.

[0032] The method for calculating the stacking pattern of multi-layer welding has a step of determining the stacking pattern, which includes the number of stacks and the position of the boundary layer, based on the database.

[0033] Invention Effects

[0034] According to the multi-layer welding method of the present invention, even in multi-layer welding in a lateral orientation, the occurrence of weld bead sagging can be minimized to form a weld joint with a good surface of the weld metal. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of one embodiment of a welding system equipped with a mobile welding robot using the multi-layer welding method of this embodiment.

[0036] Figure 2 This is a side view of a mobile welding robot.

[0037] Figure 3 This is a 3D view of a mobile welding robot.

[0038] Figure 4 This is a 3D view of a mobile welding robot installed on a polygonal square steel pipe.

[0039] Figure 5 This is a low-magnification photograph showing the cross-section of the multilayer stacked weld joint formed by the multilayer welding method of this embodiment.

[0040] Figure 6 This is a schematic cross-sectional view of the base layer of the multi-layer stacked weld head formed by welding mode 1.

[0041] Figure 7 This is a schematic cross-sectional view of the base layer of the welded joint formed by the multi-layer stack of welding mode 2.

[0042] Figure 8 This is a schematic cross-sectional view of the base layer of the welded joint formed by the multi-layer stack of welding mode 3.

[0043] Figure 9 It is a schematic cross-sectional view showing the state of a bevel with a constant torch angle and a lateral orientation during welding.

[0044] Figure 10 It is a schematic cross-sectional view showing the state before the final pass of the third layer is welded, that is, the weld pass that contacts the bevel surface of the upper plate. Detailed Implementation

[0045] Hereinafter, an embodiment of the multi-layer welding method of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that this embodiment using a mobile welding robot is the most effective example of the present invention. For example, it can also be an embodiment based on a welding device with a trolley as the moving mechanism, a 6-axis industrial robot, or manual welding by an operator.

[0046] <1. Welding System>

[0047] First, refer to Figures 1-4 The welding system 50 equipped with a mobile welding robot 100 will be described.

[0048] Figure 1 This is a schematic diagram showing the structure of the welding system according to this embodiment. Figure 1 As shown, the welding system 50 includes a mobile welding robot 100, a feed device 300, a welding power source 400, a shielding gas supply source 500, and a control device 600.

[0049] (1-1. Control device)

[0050] The control device 600 is connected to the mobile welding robot 100 via a robot control cable 620 and to the welding power supply 400 via a power supply control cable 630.

[0051] The control device 600 includes a data storage unit 601 that stores pre-set workpiece information, guide rail information, the base material (workpiece Wo) to be welded, and the position information of the guide rail 120, as well as teaching data such as the motion mode of the mobile welding robot 100, welding start position, welding end position, welding conditions, and oscillation motion. Furthermore, based on this teaching data, it sends commands to the mobile welding robot 100 and the welding power supply 400 to control the motion of the mobile welding robot 100 and the welding conditions.

[0052] Furthermore, the control device 600 includes a bevel condition calculation unit 602 that calculates bevel shape information based on detection data obtained from contact sensors, vision sensors, etc., and a welding condition calculation unit 603 that obtains welding conditions by correcting the welding conditions of the teaching data based on the bevel shape information. Additionally, it includes a speed control unit 604 that controls the drive unit in the mobile welding robot 100 for driving along the X, Y, and Z directions (described later), a welding torch position determination unit 605 that determines the welding torch position, and a welding torch angle calculation unit 606 that controls the movable arm 116 in the mobile welding robot 100, which serves as a welding torch angle drive unit. A control unit 610 is configured including the bevel condition calculation unit 602, welding condition calculation unit 603, speed control unit 604, welding torch position determination unit 605, and welding torch angle calculation unit 606. It should be noted that the welding torch position determination unit 605 and the welding torch angle calculation unit 606 can also be integrated into one unit.

[0053] Furthermore, the control device 600 is formed by integrating a controller for teaching and a controller with other control functions. However, the control device 600 is not limited to this; the controller for teaching and the controller with other control functions may be divided into multiple units depending on their functions, such as two separate units. Alternatively, the control device 600 may be included within the mobile welding robot 100, or as described above. Figure 1 As shown, the control device 600 is provided separately from and independently of the mobile welding robot 100. That is, the welding system with the mobile welding robot 100 and the control device 600 described in this embodiment includes either the case where the control device 600 is included within the mobile welding robot 100, or the case where the control device 600 is provided independently of the mobile welding robot 100. Furthermore, in this embodiment, signals are transmitted using a robot control cable 620 and a power control cable 630, but this is not a limitation; wireless transmission is also possible. It should be noted that, from the viewpoint of usability in the welding field, it is preferable to have two controllers: one for teaching and one with other control functions.

[0054] (1-2. Welding power source)

[0055] The welding power source 400 supplies power to the consumable electrode (hereinafter also referred to as "welding wire") 211 and the workpiece Wo according to instructions from the control device 600, thereby generating an electric arc between the welding wire 211 and the workpiece Wo. Power from the welding power source 400 is transmitted to the feed device 300 via the power cable 410, and from the feed device 300 to the welding torch 200 via the conductor conduit 420. Furthermore, as... Figure 2As shown, the welding wire 211 is supplied via the contact tip at the front end of the welding torch 200. It should be noted that the current during welding can be either direct current or alternating current, and its waveform is not limited. Therefore, the current can also be a rectangular wave, a triangular wave, or other pulses.

[0056] Additionally, the welding power source 400 connects power cable 410 as the positive (+) electrode to the welding torch 200 side and power cable 430 as the negative (-) electrode to the workpiece Wo. It should be noted that this is the case of welding with reverse polarity. In the case of welding with positive polarity, the positive power cable is connected to the workpiece Wo side and the negative power cable is connected to the welding torch 200 side.

[0057] (1-3. Protect the gas supply source)

[0058] The protective gas supply source 500 consists of a container filled with protective gas and auxiliary components such as valves. The protective gas is supplied from the protective gas supply source 500 to the feed device 300 via a gas pipe 510. The protective gas supplied to the feed device 300 is then supplied to the welding torch 200 via a wire guide pipe 420. The protective gas supplied to the welding torch 200 flows within the torch 200 and is guided towards the nozzle 210, and is ejected from the front end of the welding torch 200. For example, argon (Ar), carbon dioxide (CO2), or a mixture thereof can be used as the protective gas in this embodiment.

[0059] (1-4. Feeding device)

[0060] The feed device 300 extracts the welding wire 211 and feeds it to the welding torch 200. The welding wire 211 fed by the feed device 300 is not particularly limited and is selected based on the properties of the workpiece Wo, the welding method, etc., for example, solid welding wire or flux-cored welding wire can be used. Furthermore, the material of the welding wire 211 is not limited; for example, it can be mild steel, stainless steel, aluminum, titanium, etc. Moreover, the wire diameter of the welding wire 211 is not limited, but in this embodiment, the preferred upper limit is 1.6 mm and the lower limit is 0.9 mm.

[0061] In this embodiment, the conduit 420 has a conductive path formed on its outer sheath for functioning as a power cable, and a protective tube for the welding wire 211 is disposed inside the conduit, forming a flow path for the protective gas. However, the conduit 420 is not limited to this; for example, a conduit formed by bundling a power supply cable and a protective gas supply hose around the protective tube for feeding the welding wire 211 to the welding torch 200. Furthermore, for example, the conduit for conveying the welding wire 211 and the protective gas can be provided separately from the power cable.

[0062] (1-5. Mobile welding robots)

[0063] 100 mobile welding robots Figure 2 as well as Figure 3 As shown, the robot includes a guide rail 120, a robot body 110 mounted on and moving along the guide rail 120, and a welding torch connection portion 130 mounted on the robot body 110. The robot body 110 mainly includes a housing portion 112 mounted on the guide rail 120, a fixed arm portion 114 mounted on the housing portion 112, and a movable arm portion 116 mounted on the fixed arm portion 114 in a state that can rotate in the direction of arrow R1.

[0064] The welding torch connection 130 is mounted on the movable arm 116 via a crankshaft 170, which serves as a movable part that allows the welding torch 200 to move along the welding line direction, i.e., the X direction. The welding torch connection 130 includes a welding torch holder 132 and a welding torch holder 134 for fixing the welding torch 200. In addition, on the side of the housing 112 opposite to the side where the welding torch 200 is mounted, a cable holder 150 is provided to support the wire conduit 420 that connects the feed device 300 and the welding torch 200.

[0065] In this embodiment, a contact sensor is used as the detection mechanism. This sensor applies a voltage between the workpiece Wo and the welding wire 211 and senses the surface of the bevel 10 on the workpiece Wo by utilizing the voltage drop phenomenon generated when the welding wire 211 contacts the workpiece Wo. The detection mechanism is not limited to the contact sensor of this embodiment. Image sensors (i.e., visual sensors) or laser sensors (i.e., laser sensors) or combinations of these detection mechanisms can also be used. However, the contact sensor of this embodiment is preferred for the sake of simplicity of the device structure.

[0066] The shell portion 112 of the robot body 110 has such Figure 2 The robot drive unit (not shown) is driven in the X direction (perpendicular to the plane of the paper, i.e., the X direction in which the robot body 110 moves along the guide rail 120), as indicated by arrow X. Additionally, the housing 112 can also be driven in the Z direction (moving in the depth direction of the bevel 10 perpendicular to the X direction). Furthermore, the fixed arm 114 can be driven relative to the housing 112 via the sliding support 113 in the Y direction (width direction of the bevel 10 perpendicular to the X direction).

[0067] Furthermore, the welding torch connection 130, on which the welding torch 200 is mounted, is connected via the crankshaft 170 as follows: Figure 3 As shown by arrow R2, it can be rotated in the X direction along the front-to-back direction, i.e., the welding line direction, and can be driven to swing. In addition, the movable arm 116 is mounted so that it can rotate relative to the fixed arm 114 as shown by arrow R1, and the optimal angle can be adjusted and fixed.

[0068] As described above, the robot body 110 can drive the welding torch 200, which serves as its front end, with three degrees of freedom. However, the robot body 110 is not limited to this and can also be driven with any number of degrees of freedom depending on the application.

[0069] With the configuration described above, the front end of the welding torch 200, mounted on the welding torch connector 130, can face any direction. Furthermore, the robot body 110 can move along the guide rail 120... Figure 2 The welding torch 200 is driven along the X direction. By reciprocating along the Y direction while the robot body 110 moves along the X direction, oscillating welding can be performed. Furthermore, the welding torch 200 can be tilted according to construction conditions such as setting a forward or backward angle, driven by the crankshaft 170. Moreover, by tilting the welding torch 200 in the X direction using the crankshaft 170, corrections can be made. Figure 4 The change in the welding torch angle, i.e. the advance angle or the retreat angle, is caused by the different curvatures of the corner WC of the workpiece Wo (such as a polygonal square steel pipe) and the curved part 122 of the guide rail 120.

[0070] Below the guide rail 120, a mounting member 140, such as a magnet, is provided. The guide rail 120 is configured to be easily loaded and unloaded relative to the workpiece Wo via the mounting member 140. When the movable welding robot 100 is placed on the workpiece Wo, the operator can easily place the movable welding robot 100 on the workpiece Wo by grasping the handles 160 on both sides of the movable welding robot 100.

[0071] <2. Multi-layer welding method with lateral orientation>

[0072] Next, the multi-layer welding method using the lateral posture of the aforementioned mobile welding robot 100 will be described.

[0073] In typical lateral welding situations, welding is generally performed using a "straight-line motion" except for the initial layer. Here, "straight-line motion" refers to a welding operation performed in a straight line without oscillation. Furthermore, from the viewpoint of preventing weld bead sagging, low heat input is usually employed. However, when performing a straight-line motion with low heat input, a convex weld bead shape is easily formed. Therefore, optimal torch angles are typically set in each pass to achieve a strip-like, accumulated finish. Welding methods that allow for setting arbitrary torch angles include, for example, welding performed by skilled workers or welding using industrial robots with 6 or more axes.

[0074] On the other hand, mobile welding robots 100 typically lack a torch angle adjustment mechanism, therefore... Figure 9As shown, even in lateral welding, a constant torch angle α is used for all passes on both the upper and lower plate sides. In welding with a constant torch angle α, in addition to the difficulty of lateral welding, it is impossible to set the torch angle to the optimal condition based on the situation, thus making weld sag more likely. Furthermore, in the case of beveling the lower plate side to create a レ-shaped or V-shaped bevel (hereinafter, also generally referred to as "lower bevel"), weld sag is particularly prone to occur near the lower plate side due to the difficulty of construction.

[0075] Therefore, in this embodiment, not only in the case of a difficult lateral posture, but also in welding with a constant torch angle α that easily causes weld bead sag, and with a bevel shape of レ or V, in order to achieve a good joint appearance, it is necessary to take into account the weld bead sag in the "finished layer," especially the "final layer," and to properly form the weld bead shape in the "base layer," which is the previous stage. Hereinafter, three welding modes for forming the base layer will be described.

[0076] (2-1. Welding Mode 1)

[0077] Figure 5 This is a low-magnification cross-sectional photograph of the multi-layer stacked welded joint 20 formed by a multi-layer cladding welding method in a lateral orientation based on welding mode 1. Additionally, Figure 6 This is a schematic cross-sectional view of the base layer GL formed by the multi-layer overlay welding method of welding mode 1.

[0078] for Figure 5 Regarding the welded joint 20 shown, a horizontal weld was performed using a backing plate 2 and a 7-layer weld metal WL, with the lower plate 1L (25mm thick, made of SM490A material) and the upper plate 1U arranged in a transverse orientation with bevels below them. It should be noted that the lower bevel referred to here is specifically a bevel formed by beveling the lower plate side. More specifically, by... Figure 5 The weld metal WL is formed by a base layer GL consisting of five layers (circled numbers 1-5) and a finishing layer FL consisting of two layers (circled numbers 6 and 7). It should be noted that... Figure 5 The dashed lines in each layer schematically indicate the boundaries of each pass. In principle, each pass is stacked sequentially from the side closest to the lower plate 1L toward the upper plate 1U.

[0079] In welding with such a downslope and lateral orientation, weld bead sagging is prone to occur, which may have a significant impact on the appearance of the joint.

[0080] It should be noted that in the following description, "multiple layers" refers to at least two layers, including the final layer EL, designated as the finished layer FL; the layer that will serve as the base of the finished layer FL designated as the base layer GL; and the layers in the base layer GL adjacent to the finished layer FL designated as boundary layers BL. It should be noted that the term "multiple layers" here refers to... Figure 5 In the implementation shown, there are 7 layers, with the "boundary layer BL" becoming the 5th layer.

[0081] In addition, the position of the welded portion on the upper plate 1U side of each layer is set as P. U(n) The position of the welded part on the lower plate 1L side is set as P. L(n) Where n represents the number of layers. Specifically, Figure 5 This shows the case where n=3. Figure 6 The case where n=4 is shown.

[0082] It should be noted that the location of the welded portion refers to the position closest to the surface at the boundary between the upper plate 1U or lower plate 1L and the weld metal WL in each layer. Therefore, when the 5th layer becomes the boundary layer BL, the location P of the welded portion on the upper plate side of the boundary layer BL is... UB =P U(5) The location P of the welded portion on the lower plate side of the boundary layer BL LB =P L(5) .

[0083] In addition, Figure 5 The upper plate 1U and the lower plate 1L, which serve as the base material, have their right side surface 1A and their left side surface 1B.

[0084] In the welded joint 20 of this embodiment, the position P of the upper plate side fusion portion of the boundary layer BL UB The location P of the lower plate side weld portion formed by the boundary layer BL LB Surface 1A close to the base material.

[0085] Specifically, the position P of the welded part on the upper plate side UB Distance D from surface 1A of upper plate 1U UB The welded portion on the lower plate side is within the range of 2 to 12 mm. LB The distance D from the surface 1A of the lower plate 1L LB It falls within the range of 4–16 mm. Furthermore, the position P of the welded portion on the lower plate side... LB The distance D from the surface 1A of the lower plate 1L LB Position P of the welded part on the upper plate side UB Distance D from surface 1A of upper plate 1U UB The difference is D LB -D UB Formed to a size between 1mm and 10mm.

[0086] This is how distance D is formed. LB D UB The large, sloping boundary layer BL ensures a larger space on the lower plate 1L side than on the upper plate 1U side, even in welding with a lateral orientation prone to weld sag, thus allowing for the containment of molten metal. Consequently, the surface shape of the weld metal is optimized, enabling the easy formation of a high-quality finished layer FL.

[0087] It should be noted that the finished layer FL can also be a single layer, but by gradually correcting the tilt as a multi-layered structure of two or more layers, it is easier to form a finished layer FL with a good appearance, so it is preferred to set it to two or more layers.

[0088] exist Figure 6 In welding under welding mode 1 as shown, regarding the boundary layer BL, the construction information such as the bevel shape, bevel angle, and base material thickness X, as well as the position P of the welded part on the lower plate side, can be determined in advance through experiments. LB Location information, location P of the welded part on the upper plate side UB Location information and the location P of the welded part on the lower plate side LB The position P of the welded part on the upper plate side UB The relationship between relative positional information, for example, by pre-creating a table like Table 1 below.

[0089] [Table 1]

[0090] Table 1

[0091]

[0092] Where X is the thickness of the base material (mm).

[0093] Furthermore, based on construction information, the location P of the welded portion on the lower plate side was manually determined according to Table 1 above. LB Location information, location P of the welded part on the upper plate side UB Location information and the location P of the welded part on the lower plate side LB The position P of the welded part on the upper plate side UB The shape of the boundary layer BL, which is the target, is determined by at least two of the relative positional information between the two elements.

[0094] To obtain a boundary layer BL of this shape through welding, such as Figure 6 As shown, in the welding based on soil welding mode 1, the position P of the plate side welded portion below each layer of the base layer GL is... L(n) Distance D from the surface 1A of the base material L(n) Position P of the welded part on the upper plate side U(n) Distance D from the surface 1A of the base material U(n)The difference is D L(n) -D U(n) The layers are stacked in a progressively larger manner up to the boundary layer BL. To form a defect-free base layer GL, the inclination of each layer of the base layer GL is preferably adjusted so that it gradually approaches the boundary layer BL from layer 1 to layer 5. This adjustment simplifies the fabrication of the boundary layer BL, which is difficult to fabricate due to the tendency of the molten portion of the upper plate side weld passes to sag under gravity. It should be noted that the number of layers n and the number of passes can be determined manually based on construction information.

[0095] Furthermore, the determination of the aforementioned number of layers n, number of passes, each layer of the base layer GL, and boundary layer BL can also be automated without manual intervention. That is, regarding the number of layers n, construction information such as the bevel shape, bevel angle, and base material thickness X is input into a pre-determined formula to calculate the number of layers n. Moreover, based on stored information, the construction information and the position P of the lower plate side welded portion of the boundary layer BL are linked. LB Location information, location P of the welded part on the upper plate side UB Location information and the location P of the welded part on the lower plate side LB The position P of the welded part on the upper plate side UB A database of associated data is established using at least two of the relative positional information between layers, determining the stacking pattern of each layer, including the position of the boundary layer (BL). Furthermore, the number of traces for each layer is calculated by inputting other formulas that derive the trace count from the stacking number n.

[0096] For example, if the number of layers n is determined to be 8 layers according to the formula, the layer that becomes the boundary layer BL is determined based on the database. If the 5th layer is determined to be the boundary layer BL, then the 5th layer is used as the boundary layer BL, and the welding mode of the base layer GL and the finished layer FL, as well as the number of passes in each layer, are determined. Furthermore, to ensure that the base layer GL, boundary layer BL, and finished layer FL each satisfy the determined shape, the oscillation, welding speed, target position of the welding wire tip, etc., described later, are adjusted to form each layer.

[0097] It should be noted that, based on the distance D from the surface 1A of the base material... L(n) With D U(n) The difference is D L(n) -D U(n) For welding pattern 1, which increases sequentially up to the boundary layer BL, the formula for calculating the number of layers n and the number of passes becomes simple, and the stacking conditions can be easily calculated.

[0098] It should be noted that the above-mentioned multi-layer welding method is not limited to Figure 5 The レ-type bevel shown can also be applied to other bevel shapes such as I-type bevels and V-type bevels.

[0099] (2-2. Welding Mode 2)

[0100] like Figure 7 As shown, in the multi-layer welding method based on the lateral orientation of welding mode 2, the position P of the upper plate side weld portion of the boundary layer BL is... UB It also forms the position P of the lower plate side weld portion compared to the boundary layer BL. LB Surface 1A is close to the base material. Specifically, it is set as position P of the welded portion on the upper plate side. UB Distance D from surface 1A of upper plate 1U UB The thickness is in the range of 2 to 12 mm, and the position P of the welded part on the lower plate side is... LB The distance D from the surface 1A of the lower plate 1L LB It falls within the range of 4–16 mm. Furthermore, the position P of the welded portion on the lower plate side... LB The distance D from the surface 1A of the lower plate 1L LB Position P of the welded part on the upper plate side UB Distance D from surface 1A of upper plate 1U UB The difference is D LB -D UB It forms a shape between 1mm and 10mm. It should be noted that... Figure 7 An example is shown where n=4.

[0101] In addition, in welding mode 2, each base layer GL is from the specified layer, i.e. Figure 7 From the second layer to the boundary layer BL, the position P of the welded portion on the lower plate side. L(n) The distance D from the surface 1A of the lower plate 1L L(n) Position P of the welded part on the upper plate side U(n) Distance D from surface 1A of upper plate 1U U(n) The difference is D L(n) -D U(n) Multiple layers are formed continuously. By forming each base layer GL in this way, it is easy to form a boundary layer BL of the desired shape when forming a weld joint with a good surface finish of the weld metal. In addition, according to welding mode 2, by setting a larger amount of deposited metal on the upper plate 1U side from the initial layer, the tilt angle of the target boundary layer BL can be achieved earlier, and thus the tilt angle adjustment becomes easier.

[0102] (2-3. Welding Mode 3)

[0103] like Figure 8 As shown, in the multi-layer welding method based on the lateral orientation of welding mode 3, the position P of the upper plate side weld portion of the boundary layer BL is... UB It also forms the position P of the lower plate side weld portion compared to the boundary layer BL. LBSurface 1A near the base material. Specifically, location P where the upper plate side weld portion is formed. UB Distance D from surface 1A of upper plate 1U UB The thickness is in the range of 2 to 12 mm, and the position P of the welded part on the lower plate side is... LB The distance D from the surface 1A of the lower plate 1L LB It falls within the range of 4–16 mm. Furthermore, the position P of the welded portion on the lower plate side... LB The distance D from the surface 1A of the lower plate 1L LB Position P of the welded part on the upper plate side UB Distance D from surface 1A of upper plate 1U UB The difference is D LB -D UB It forms a shape between 1mm and 10mm. It should be noted that... Figure 8 An example is shown where n=3.

[0104] In addition, based on welding mode 3, each base layer GL has a lower plate side welded portion P in each layer. L(n) The distance D from the surface 1A of the lower plate 1L L(n) Position P of the welded part on the upper plate side U(n) Distance D from surface 1A of upper plate 1U U(n) The difference is D L(n) -D U(n) The layers are stacked alternately in a positive and negative manner up to the boundary layer BL. Figure 8 In the embodiment shown, the positions P of the lower plate side weld portions of the second and fourth layers of the substrate GL are... L(n) Formed at position P of the welded portion on the upper plate side U(n) The positions P of the lower plate side welded portions of the third and fifth layers, close to the surface 1A of the lower plate 1L which serves as the base material. L(n) Formed at position P of the welded portion on the upper plate side U(n) The position is away from the surface 1A of the lower plate 1L, which is the parent material.

[0105] By forming each base layer GL in this way, it is easy to form a boundary layer BL of the desired shape when forming a weld joint with a good surface finish of the weld metal. In addition, according to welding mode 3, it is easy to ensure the space for the final pass of each layer, i.e., the weld pass that contacts the bevel surface of the upper plate, as described later, and it is easy to balance appearance and weld quality.

[0106] In the above, by utilizing any of the welding modes 1 to 3 to form a boundary layer BL of the desired shape, the thickness direction of the weld bead is larger in the lower plate side than in the upper plate side due to the influence of gravity on the weld bead shape when welding the finished layer. As a result, the surface shape of the weld metal in the final layer becomes better, and a weld joint with excellent appearance can be formed.

[0107] It should be noted that, as an example of a method for adjusting the shape of each layer and the amount of fusion in each pass based on the above-mentioned welding pattern, the factors shown in (A) to (C) below can be cited.

[0108] (A) Swinging

[0109] By setting the frequency to 1–3 Hz, the oscillation width to 0.5–1.5 mm, and the oscillation stop time to 0–0.5 sec, a good weld bead that makes the joint shape neat can be formed.

[0110] (B) Ensuring the target position of the welding wire tip and the welding space

[0111] In the final pass of each layer, i.e., the weld pass that contacts the bevel surface of the upper plate, the target position of the welding wire tip is preferably separated from the bevel surface of the upper plate, which serves as the base material, by approximately 2–5 mm. Here, refer to… Figure 10 Please provide a detailed explanation. Figure 10 This diagram shows the state before the final pass of the third layer, which is the pass that contacts the bevel surface of the upper plate. Here, when the target position of the welding wire tip is excessively close to the bevel surface 1UA, to the point where it is less than 2 mm from the bevel surface 1UA of the upper plate 1U (e.g., 0-1 mm), the arc tends to form on the bevel surface 1UA side, potentially causing instability in the arc length. Furthermore, this arc length variation leads to excessive spatter generation, degrading the joint appearance. On the other hand, when the target position of the welding wire tip is excessively separated from the bevel surface 1UA, to the point where it is more than 5 mm from the bevel surface 1UA (e.g., 6 mm or more), the arc may not contact the upper plate 1U of the base material, potentially causing welding defects such as poor fusion.

[0112] It should be noted that the stack width LW before the final pass affects the space available for the final pass. For example, if the stack width LW is too large, the space available for the final pass becomes narrower; conversely, if the stack width LW is too small, the deposition rate of the final pass needs to be increased. Therefore, the size of the stack width LW before the final pass becomes a cause of weld beads, weld sagging, etc., and thus needs to be set to an appropriate height. It should be noted that the stack width LW mentioned above refers to the width from the bevel face 1LA of the lower plate 1L to the position furthest from the bevel face 1LA in the weld passes welded before the final pass.

[0113] Furthermore, in the initial pass of each layer, i.e., the welding pass that contacts the bevel surface of the lower plate, the target position of the welding wire tip is expected to be separated from the bevel surface 1LA of the lower plate 1L, which is the base material, by about 1 to 3 mm. In the mobile welding robot 100, changing the torch angle α is relatively difficult, thus weld bead sagging is prone to occur in the horizontal welding posture. Therefore, by separating the target position of the welding wire tip from the bevel surface 1LA by about 1 to 3 mm, the generation of weld beads can be suppressed. Weld beads refer to the portion at the end of the weld bead where the fusion with the base material is poor. In JIS Z 3001-4, it is defined as "the portion of the weld metal WL that overlaps with the base material at the end without fusion." To improve fusion, appropriate welding speed and oscillation can also be expected to improve the effect.

[0114] (C) Number of layers and number of passes

[0115] Besides the optimal shape design of the base layer GL and the finished layer FL mentioned above, the number of layers and the number of passes are the most important factors in adjusting the space for welding.

[0116] The above description, based on the accompanying drawings, details one embodiment of the multilayer welding method of the present invention. However, the present invention is not limited to the aforementioned embodiment and can be appropriately modified or improved.

[0117] For example, the multi-layer welding method of the present invention is preferably used in a welding system 50 equipped with the mobile welding robot 100 of this embodiment, but the present invention is not limited thereto and can also be applied in a welding system equipped with a 6-axis welding robot.

[0118] As stated above, the following matters are disclosed in this specification.

[0119] (1) A multi-layer overlay welding method for joining a pair of base materials consisting of an upper plate and a lower plate configured to form a bevel, by forming weld metal through multi-layer overlay welding in a transverse orientation, wherein,

[0120] The weld metal has multiple layers from the back side to the surface of the base material.

[0121] The plurality of layers have:

[0122] A completed floor, comprising at least two floors including the final floor; and

[0123] A base layer, located on the back side of the base material closer to the finished layer, and including a boundary layer that becomes the layer adjacent to the finished layer.

[0124] Position P of the upper plate side weld portion in the boundary layer UB The position P of the lower plate side weld portion in the boundary layer LBThe boundary layer is formed in a manner close to the surface of the base material.

[0125] According to this structure, even in multi-layer welding in a lateral orientation, the occurrence of weld bead sagging can be minimized to form a weld joint with a good surface of the weld metal.

[0126] (2) According to the multi-layer welding method described in (1), wherein,

[0127] The multi-layer welding method determines the P based on construction information. UB Location information, the P LB Location information, and the P UB and the P LB The process of obtaining at least two positional information from the relative positional information between them.

[0128] The construction information includes at least the bevel shape, bevel angle, and thickness of the base material.

[0129] Based on this structure, the boundary layer can be designed based on the specified construction information.

[0130] (3) The multilayer welding method according to (1) or (2), wherein,

[0131] The construction information includes at least the bevel shape, bevel angle, and thickness of the base material, and is linked to the P. UB Location information, the P LB Location information, and the P UB and the P LB At least two of the relative positional information between them established an associated database.

[0132] The multilayer welding method includes a step of determining a stacking pattern, including the number of stacks and the position of the boundary layer, based on the database.

[0133] Based on this structure, a stacking pattern, including the number of layers and the location of boundary layers, can be automatically determined based on a database that links construction information with specified location information.

[0134] (4) The multilayer welding method according to any one of (1) to (3), wherein,

[0135] The boundary layer is formed in the following manner:

[0136] From the surface of the base material to P UB Distance D UB It is in the range of 2 to 12 mm, and from the surface of the base material to the P LB Distance D LBIt is in the range of 4 to 16 mm, and

[0137] The D UB With the D LB The difference is more than 1 mm and less than 10 mm.

[0138] According to this structure, by forming a finished layer on the surface side of the boundary layer, a good joint appearance can be obtained with fewer finished layers.

[0139] (5) The multilayer welding method according to any one of (1) to (4), wherein,

[0140] Let P be the position of the upper plate-side welded portion in the nth layer. U(n) The position of the lower plate side welded part in the nth layer is set as P. L(n) In this case,

[0141] From the surface of the base material to the P L(n) Distance D L(n) From the surface of the base material to the P U(n) Distance D U(n) The difference (D) L(n) -D U(n) The base layer is formed by progressively increasing in size up to the boundary layer.

[0142] Based on this structure, when forming a weld joint with a good surface finish of the weld metal, it is easy to form a boundary layer of the desired shape. Furthermore, the formulas for calculating the number of layers and passes become simple, making it easy to calculate the stacking conditions.

[0143] (6) The multilayer welding method according to any one of (1) to (4), wherein,

[0144] Let P be the position of the upper plate-side welded portion in the nth layer. U(n) The position of the lower plate side welded part in the nth layer is set as P. L(n) In this case,

[0145] A continuous layer is formed from the surface of the base material to the boundary layer, extending from the specified layer in the base layer to the P layer. L(n) Distance D L(n) From the surface of the base material to the P U(n) Distance D U(n) The difference (D) L(n) -D U(n) () represents multiple layers that are positive.

[0146] According to this structure, when forming a weld joint with a good surface finish of the weld metal, it is easy to form a boundary layer of the desired shape. In addition, it is possible to provide a greater amount of deposited metal thickness on the upper plate side from the initial layer.

[0147] (7) The multilayer welding method according to any one of (1) to (4), wherein,

[0148] Let P be the position of the upper plate-side welded portion in the nth layer. U(n) The position of the lower plate side welded part in the nth layer is set as P. L(n) In this case,

[0149] From the surface of the base material to the P L(n) Distance D L(n) From the surface of the base material to the P U(n) Distance D U(n) The difference (D) L(n) -D U(n) The base layer is formed by alternating positive and negative forms up to the boundary layer.

[0150] Based on this structure, when forming a weld joint with a good surface finish on the weld metal, it is easy to form a boundary layer of the desired shape. In addition, it is easy to ensure space on the bevel side, making it easier to balance appearance quality and weld quality.

[0151] (8) A multi-layer stacked butt weld joint, wherein a pair of base materials consisting of an upper plate and a lower plate configured to form a bevel are joined by weld metal formed by multi-layer overlay welding, wherein,

[0152] The weld metal has multiple layers from the back side to the surface of the base material.

[0153] The plurality of layers have:

[0154] A completed floor, comprising at least two floors including the final floor; and

[0155] A base layer, located on the back side of the base material closer to the finished layer, and including a boundary layer that becomes the layer adjacent to the finished layer.

[0156] The location P of the upper plate-side welded portion in the boundary layer UB The position P of the lower plate side weld portion in the boundary layer LB Approaching the surface of the base material.

[0157] According to this structure, even in multi-layer welding in a lateral orientation, the occurrence of weld bead sagging can be minimized to obtain a weld joint with a good surface finish of the weld metal.

[0158] (9) The multi-layer stacked butt weld joint according to (8), wherein,

[0159] From the surface of the base material to P UB Distance D UB It is in the range of 2 to 12 mm, and from the surface of the base material to the P LB Distance D LB It is in the range of 4 to 16 mm, and

[0160] The D UB With the D LB The difference is more than 1 mm and less than 10 mm.

[0161] Based on this structure, welded joints with excellent appearance performance can be obtained with fewer finished layers.

[0162] (10) A method for calculating the stacking pattern of multi-layer weld overlay, used for performing the multi-layer weld overlay method described in (3), wherein,

[0163] The construction information includes at least the bevel shape, bevel angle, and thickness of the base material, and is linked to the P. UB Location information, the P LB Location information, and the P UB and the P LB At least two of the relative positional information between them established an associated database.

[0164] The method for calculating the stacking pattern of multi-layer welding includes a step of determining the stacking pattern, including the number of layers and the position of the boundary layer, based on the database.

[0165] Based on this structure, a stacking pattern, including the number of layers and the location of boundary layers, can be automatically determined based on a database that links construction information with specified location information.

[0166] Various embodiments have been described above with reference to the accompanying drawings, but the present invention is not limited to the examples described above. Those skilled in the art will be able to conceive of various modifications or alterations within the scope of the patented technical solutions, and these modifications or alterations naturally fall within the technical scope of the present invention. Furthermore, the constituent elements in the above embodiments can be arbitrarily combined without departing from the spirit of the invention.

[0167] It should be noted that this application is based on Japanese patent application (Japanese Patent Application No. 2021-124523) filed on July 29, 2021, the contents of which are referenced in this application.

[0168] Explanation of reference numerals in the attached figures

[0169] 1A Surface of the base material

[0170] 1B Back side of the base material

[0171] 1L as the base material lower plate

[0172] 1U upper plate as the base material

[0173] 20+ multi-layer stacked butt welded joints

[0174] BL boundary layer

[0175] D L(n) From the surface of the base material to P L(n) distance

[0176] D LB From the surface of the base material to P LB distance

[0177] D U(n) From the surface of the base material to P U(n) distance

[0178] D UB From the surface of the base material to P UB distance

[0179] EL final layer

[0180] FL Finished Floor

[0181] GL base layer

[0182] n layers

[0183] P L(n) The position of the lower plate side welded part in the nth layer

[0184] P LB Location of the lower plate side weld in the boundary layer

[0185] P U(n) The position of the upper plate side welded part in the nth layer

[0186] P UB Location of the upper plate side weld in the boundary layer

[0187] WL Welding Metal

[0188] The thickness of the base material.

Claims

1. A multi-layer overlay welding method for joining a pair of base materials consisting of an upper plate and a lower plate configured to form a bevel, by forming weld metal through multi-layer overlay welding in a transverse orientation, wherein, Welding is performed with a constant torch angle, and / or the bevel is a U-shaped or V-shaped bevel formed by beveling on the lower plate side. The weld metal has multiple layers from the back side to the surface of the base material. The plurality of layers have: A completed layer, which has at least two layers, including the final layer; as well as A base layer, located on the back side of the base material closer to the finished layer, and including a boundary layer that becomes the layer adjacent to the finished layer. Position P of the upper plate side weld portion in the boundary layer UB The position P of the lower plate side weld portion in the boundary layer LB The boundary layer is formed in a manner close to the surface of the base material.

2. The multi-layer welding method according to claim 1, wherein, The multi-layer welding method determines the P based on construction information. UB Location information, the P LB Location information, and the P UB and the P LB The process of obtaining at least two positional information from the relative positional information between them. The construction information includes at least the bevel shape, bevel angle, and the thickness of the base material.

3. The multi-layer welding method according to claim 1 or 2, wherein, The construction information includes at least the bevel shape, bevel angle, and thickness of the base material, and is linked to the P. UB Location information, the P LB Location information, and the P UB and the P LB At least two of the relative positional information between them established an associated database. The multilayer welding method includes a step of determining a stacking pattern, including the number of stacks and the position of the boundary layer, based on the database.

4. The multi-layer welding method according to claim 1 or 2, wherein, The boundary layer is formed in the following manner: From the surface of the base material to P UB Distance D UB It is in the range of 2 to 12 mm, and from the surface of the base material to the P LB Distance D LB It is in the range of 4 to 16 mm, and The D UB With the D LB The difference is greater than 1 mm and less than 10 mm.

5. The multi-layer welding method according to claim 3, wherein, The boundary layer is formed in the following manner: From the surface of the base material to P UB Distance D UB It is in the range of 2 to 12 mm, and from the surface of the base material to the P LB Distance D LB It is in the range of 4 to 16 mm, and The D UB With the D LB The difference is greater than 1 mm and less than 10 mm.

6. The multi-layer welding method according to claim 1 or 2, wherein, Let P be the position of the upper plate-side welded portion in the nth layer. U（n） The position of the lower plate side welded part in the nth layer is set as P. L（n） In this case, From the surface of the base material to the P L（n） Distance D L（n） From the surface of the base material to the P U（n） Distance D U（n） The difference (D) L（n） -D U（n） The base layer is formed by progressively increasing in size up to the boundary layer.

7. The multi-layer welding method according to claim 3, wherein, Let P be the position of the upper plate-side welded portion in the nth layer. U（n） The position of the lower plate side welded part in the nth layer is set as P. L（n） In this case, From the surface of the base material to the P L（n） Distance D L（n） From the surface of the base material to the P U（n） Distance D U（n） The difference (D) L（n） -D U（n） The base layer is formed by progressively increasing in size up to the boundary layer.

8. The multi-layer welding method according to claim 4, wherein, Let P be the position of the upper plate-side welded portion in the nth layer. U（n） The position of the lower plate side welded part in the nth layer is set as P. L（n） In this case, From the surface of the base material to the P L（n） Distance D L（n） From the surface of the base material to the P U（n） Distance D U（n） The difference (D) L（n） -D U（n） The base layer is formed by progressively increasing in size up to the boundary layer.

9. The multi-layer welding method according to claim 1 or 2, wherein, Let P be the position of the upper plate-side welded portion in the nth layer. U（n） The position of the lower plate side welded part in the nth layer is set as P. L（n） In this case, A continuous layer is formed from the surface of the base material to the boundary layer, extending from the specified layer in the base layer to the P layer. L（n） Distance D L（n） From the surface of the base material to the P U（n） Distance D U（n） The difference (D) L（n） -D U（n） () represents multiple layers that are positive.

10. The multi-layer overlay welding method according to claim 3, wherein, Let P be the position of the upper plate-side welded portion in the nth layer. U（n） The position of the lower plate side welded part in the nth layer is set as P. L（n） In this case, A continuous layer is formed from the surface of the base material to the boundary layer, extending from the specified layer in the base layer to the P layer. L（n） Distance D L（n） From the surface of the base material to the P U（n） Distance D U（n） The difference (D) L（n） -D U（n） () represents multiple layers that are positive.

11. The multi-layer welding method according to claim 4, wherein, Let P be the position of the upper plate-side welded portion in the nth layer. U（n） The position of the lower plate side welded part in the nth layer is set as P. L（n） In this case, A continuous layer is formed from the surface of the base material to the boundary layer, extending from the specified layer in the base layer to the P layer. L（n） Distance D L（n） From the surface of the base material to the P U（n） Distance D U（n） The difference (D) L（n） -D U（n） () represents multiple layers that are positive.

12. The multilayer welding method according to claim 1 or 2, wherein, Let P be the position of the upper plate-side welded portion in the nth layer. U（n） The position of the lower plate side welded part in the nth layer is set as P. L（n） In this case, From the surface of the base material to the P L（n） Distance D L（n） From the surface of the base material to the P U（n） Distance D U（n） The difference (D) L（n） -D U（n） The base layer is formed by alternating positive and negative forms up to the boundary layer.

13. The multi-layer welding method according to claim 3, wherein, Let P be the position of the upper plate-side welded portion in the nth layer. U（n） The position of the lower plate side welded part in the nth layer is set as P. L（n） In this case, From the surface of the base material to the P L（n） Distance D L（n） From the surface of the base material to the P U（n） Distance D U（n） The difference (D) L（n） -D U（n） The base layer is formed by alternating positive and negative forms up to the boundary layer.

14. The multi-layer welding method according to claim 4, wherein, Let P be the position of the upper plate-side welded portion in the nth layer. U（n） The position of the lower plate side welded part in the nth layer is set as P. L（n） In this case, From the surface of the base material to the P L（n） Distance D L（n） From the surface of the base material to the P U（n） Distance D U（n） The difference (D) L（n） -D U（n） The base layer is formed by alternating positive and negative forms up to the boundary layer.

15. A multi-layer stacked butt weld joint, wherein a pair of base materials consisting of an upper plate and a lower plate configured to form a bevel are joined by weld metal formed by multi-layer overlay welding, wherein, Welding is performed with a constant torch angle, and / or the bevel is a U-shaped or V-shaped bevel formed by beveling on the lower plate side. The weld metal has multiple layers from the back side to the surface of the base material. The plurality of layers have: A completed layer, which has at least two layers, including the final layer; as well as A base layer, located on the back side of the base material closer to the finished layer, and including a boundary layer that becomes the layer adjacent to the finished layer. The location P of the upper plate-side welded portion in the boundary layer UB The position P of the lower plate side weld portion in the boundary layer LB Approaching the surface of the base material.

16. The multilayer stacked butt weld joint according to claim 15, wherein, From the surface of the base material to P UB Distance D UB It is in the range of 2 to 12 mm, and from the surface of the base material to the P LB Distance D LB It is in the range of 4 to 16 mm, and The D UB With the D LB The difference is greater than 1 mm and less than 10 mm.

17. A method for calculating the stacking pattern of multi-layer weld overlay, used to perform the multi-layer weld overlay method of claim 3, wherein, The construction information includes at least the bevel shape, bevel angle, and thickness of the base material, and is linked to the P. UB Location information, the P LB Location information, and the P UB and the P LB At least two of the relative positional information between them established an associated database. The method for calculating the stacking pattern of multi-layer welding includes a step of determining the stacking pattern, including the number of layers and the position of the boundary layer, based on the database.

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