Welding device

Abstract

To provide a technique that can reduce a possibility that welding defect may occur when variation in shape of regions to be welded occurs, at the time of welding a first object to be welded to a second object to be welded.SOLUTION: A welding device, which welds a first object to be welded to a second object to be welded, is provided with: a welding torch that applies energy towards a region to be welded, in order to melt the region to be welded set across the first object to be welded and the second object to be welded; a welded-object sensor that measures a physical amount concerning the region to be welded, and obtains shape information on the region to be welded, using the measured physical amount; and a control device that changes a welding condition using the shape information on the region to be welded obtained using the welded-object sensor.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a welding apparatus.

Background Art

[0002] Conventionally, a technique of arc-welding a workpiece using a welding apparatus including a welding torch and a welding sensor that emits and images a laser from the front of the welding torch with respect to the welding direction is known (Patent Document 1). In this technique, control for adjusting the groove-tracing control and welding conditions is performed by acquiring the three-dimensional positions of the welding torch, the molten pool, the groove, etc. using the welding sensor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the conventional technique, when there are variations in the shape of the welding area, there is a possibility of welding defects such as an undesired penetration amount not being obtained.

Means for Solving the Problems

[0005] The present disclosure can be realized in the following forms.

[0006] (1) According to the first aspect of the present disclosure, a welding apparatus is provided. A welding apparatus for welding a first workpiece and a second workpiece, comprising: a welding torch that applies energy toward the welded region to melt the welded region spanning the first workpiece and the second workpiece; a workpiece sensor that measures a physical quantity related to the welded region and acquires shape information of the welded region using the measured physical quantity; and a control device that changes welding conditions using the shape information of the welded region acquired using the workpiece sensor. According to this aspect, the welding conditions can be changed using the shape information of the welded region acquired using the workpiece sensor so as to obtain a desired penetration amount. Thereby, even when there are variations in the shape of the welded region, the possibility of welding defects can be reduced. (2) In the above aspect, the first workpiece and the second workpiece each have a surface located on the welding torch side and a back surface facing the surface, and the workpiece sensor includes a step sensor that measures the step amount of a step surface formed by the surface of the first workpiece and the surface of the second workpiece in the welded region. The control device may change the tilt angle, which is one of the welding conditions, with respect to the axial direction of the welding torch in the reference posture so that the energy is applied to the step surface, and the tilt angle may be increased as the step amount increases. According to this aspect, when there is a step in the welded region, the tilt angle of the welding torch is changed according to the step amount so that energy is applied to the step surface. Thereby, even when there is a step in the welded region, energy can be more reliably applied to the step surface. Thereby, the possibility of welding defects can be further reduced. (3) In the above-described embodiment, the control device may change the inclination angle such that the inclination angle increases as the step amount increases until the inclination angle reaches a predetermined upper limit value. According to this embodiment, when the inclination angle of the welding torch is equal to or greater than a predetermined upper limit value, the inclination angle of the welding torch is maintained at the upper limit value. By doing so, the inclination angle of the welding torch can be changed without the welding torch taking an unreasonable posture. In addition, it is possible to reduce the possibility that energy is not applied to a desired position in the welded area due to the inclination angle of the welding torch becoming too large. (4) In the above-described embodiment, the control device may maintain the inclination angle at zero without inclining the welding torch when the step amount is less than a predetermined threshold value. According to this embodiment, when the step amount is less than the threshold value, the inclination angle of the welding torch is maintained at zero. By doing so, for example, since the operation of changing the inclination angle of the welding torch can be omitted, the time required for welding can be shortened. (5) In the above-described embodiment, the first work piece and the second work piece are each a plate-shaped member having a surface located on the side of the welding torch and a back surface facing the surface. The work piece sensor includes an angle sensor that measures the surface angle formed by the surface of the first work piece and the surface of the second work piece, and a gap sensor that measures the gap, which is the distance between the first work piece and the second work piece on the surface side. The control device calculates the root gap, which is the distance between the first work piece and the second work piece on the back surface side, using the plate thickness of the first work piece, the plate thickness of the second work piece, the surface angle, and the gap. The smaller the root gap, the larger the total amount of energy applied to the welded area, which is one of the welding conditions. According to this embodiment, the root gap can be calculated using the plate thickness of the work piece, the surface angle, and the gap. And even when there are variations in the shape of the welded area, the total amount of energy applied to the welded area can be changed according to the root gap. Thereby, when there are variations in the shape of the welded area, the possibility of causing welding defects can be further reduced. The present disclosure can be realized in various forms other than the above-described welding apparatus. For example, it can be realized in the form of a method for manufacturing a welding apparatus, a control method for a welding apparatus, a computer program for realizing the control method, a non-transitory recording medium recording the computer program, and the like.

Brief Description of the Drawings

[0007]

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Mode for Carrying Out the Invention

[0008] A. First Embodiment: FIG. 1 is a perspective view showing a schematic configuration of a welded object W in which a welded area WS spanning the first welded object W1 and the second welded object W2 is welded. In the upper diagram of FIG. 1, the welded object W during welding and a part of the welding apparatus 10 are schematically shown. In the lower diagram of FIG. 1, the welded object W after welding is schematically shown. The welded object W is manufactured, for example, by applying energy to the welded area WS in a state where the first welded object W1 and the second welded object W2 are butted against each other, and welding the welded area WS.

[0009] The workpiece W has a first workpiece W1, a second workpiece W2, and a welded joint portion WF. The first workpiece W1 and the second workpiece W2 are, for example, plate-shaped metal members. Each of the first workpiece W1 and the second workpiece W2 has a surface W1a, W2a, a back surface W1b, W2b facing the surface W1a, W2a, and an end surface W1c, W2c. The end surfaces W1c, W2c are the surfaces located in the welded region WS among the surfaces connecting the surface W1a, W2a and the back surface W1b, W2b. In the present embodiment, the boundary portion W1d between the surface W1a of the first workpiece W1 and the end surface W1c of the first workpiece W1 is referred to as the first boundary portion W1d. Further, the boundary portion W2d between the surface W2a of the second workpiece W2 and the end surface W2c of the second workpiece W2 is referred to as the second boundary portion W2d. Note that the first workpiece W1 and the second workpiece W2 may be flat plates or curved plates.

[0010] In the present embodiment, the plate thickness t1 of the first workpiece W1 is smaller than the plate thickness t2 of the second workpiece W2. Therefore, in a state where the end surface W1c of the first workpiece W1 and the end surface W2c of the second workpiece W2 are butted against each other, a stepped surface SF is formed in the welded region WS by the surface W1a of the first workpiece W1 and the surface W2a of the second workpiece W2. That is, the stepped surface SF is a surface formed on a part of the end surface W2c of the second workpiece W2 butted against the end surface W1c of the first workpiece W1. Therefore, it can be said that when the stepped surface SF occurs, the shape of the groove K varies. Note that the plate thickness t1 of the first workpiece W1 may be larger than the plate thickness t2 of the second workpiece W2. When the plate thickness t1 of the first workpiece W1 is larger than the plate thickness t2 of the second workpiece W2, the stepped surface SF is a surface formed on a part of the end surface W1c of the first workpiece W1 butted against the end surface W2c of the second workpiece W2. Further, the plate thickness t1 of the first workpiece W1 and the plate thickness t2 of the second workpiece W2 may be the same. When the plate thickness t1 of the first workpiece W1 and the plate thickness t2 of the second workpiece W2 are the same, the stepped surface SF is not formed.

[0011] The welded joint WF is a joint portion between the first workpiece W1 and the second workpiece W2 formed by solidification after the first workpiece W1 and the second workpiece W2 are melted in the welded area WS. Therefore, the welded joint WF fixes the first workpiece W1 and the second workpiece W2 to each other. In this embodiment, the welded area WS has a V-shaped groove KV. Note that the welded area WS may have a groove K of other shapes (for example, I-shaped) or may not have a groove K.

[0012] FIG. 2 is a schematic diagram showing a schematic configuration of the welding apparatus 10. The welding apparatus 10 welds the first workpiece W1 and the second workpiece W2. In this embodiment, the welding apparatus 10 is an arc welding apparatus that manufactures the workpiece W by welding the first workpiece W1 and the second workpiece W2 by arc welding. The welding apparatus 10 includes a stage 14, an arc welding unit 12, a workpiece sensor 11, a position and posture changing mechanism 13, and a control device 15.

[0013] The stage 14 is a pedestal for placing the workpieces to be welded, that is, the first workpiece W1 and the second workpiece W2. The first workpiece W1 and the second workpiece W2 are arranged such that their back surfaces W1b and W2b are located on the stage 14 side and their front surfaces W1a and W2a are located on the welding torch 125 side. In this embodiment, the stage 14 is plate-shaped and arranged parallel to the horizontal plane. Also, in this embodiment, the first workpiece W1 and the second workpiece W2 are fixed to the stage 14 in a state where the end surface W1c of the first workpiece W1 abuts against the end surface W2c of the second workpiece W2.

[0014] The arc welding unit 12 includes a welding torch 125 and a power supply device 121. The arc welding unit 12 is electrically connected to the control device 15.

[0015] The welding torch 125 applies energy (in this embodiment, an arc AC) toward the welded region WS in accordance with a control command from the control device 15 in order to melt the welded region WS spanning the first workpiece W1 and the second workpiece W2. The welding torch 125 is, for example, an arc torch for MIG welding. A welding wire mainly composed of the same material as the workpiece W is supplied to the welding torch 125 for arc welding as the electrode 127, and a shielding gas such as argon gas, carbon dioxide gas, or a mixed gas of argon gas and carbon dioxide gas is supplied. Note that the welding torch 125 may be an arc torch for welding by other methods such as TIG welding. Further, the electrode 127 may be a welding rod mainly composed of the same material as the workpiece W instead of the welding wire. Also, the type of shielding gas is not limited to this.

[0016] The power supply device 121 is electrically connected to the welding torch 125 by a cable 122 such as a power cable. The power supply device 121 is electrically connected to the workpiece W by a cable 123 such as an earth cable. The power supply device 121 applies a positive voltage to the electrode 127 supplied to the welding torch 125 and a negative voltage to the workpiece W. While welding voltages are applied to the electrode 127 of the welding torch 125 and the workpiece W, respectively, shielding gas is ejected from the welding torch 125 into the welded region WS. Thereby, an arc AC is generated between the welding torch 125 and the workpiece W.

[0017] The workpiece sensor 11 measures a physical quantity related to the welded region WS and acquires shape information of the welded region WS using the measured physical quantity. The "physical quantity" mentioned here is an element necessary for acquiring shape information indicating the shape of the welded region WS. Specifically, the physical quantity is, for example, the position of the edge E of the workpiece W indicating the shape and position of the first boundary portion W1d and the second boundary portion W2d, the surface angle θs (FIG. 11 described later), and the gap amount G (FIG. 11 described later). The workpiece sensor 11 and the control device 15 are electrically connected. The shape information of the welded region WS is transmitted to the control device 15.

[0018] The work piece sensor 11 is preferably arranged in front of the welding torch 125 in the welding progress direction (hereinafter referred to as the welding progress direction). By arranging the work piece sensor 11 in front of the welding torch 125 in the welding progress direction, the welding conditions can be appropriately changed using the shape information of the work piece area WS obtained using the work piece sensor 11.

[0019] The work piece sensor 11 is, for example, a laser sensor. The laser sensor as the work piece sensor 11 includes a laser oscillator 111, a laser head 115, and a light receiving unit 118. The laser oscillator 111 generates laser light LS. The laser head 115 irradiates the laser light LS toward the surfaces W1a, W2a of the work piece W. The laser head 115 is connected to the laser oscillator 111 by a cable 112 such as an optical fiber. The laser light LS generated by the laser oscillator 111 is transmitted from the laser oscillator 111 to the laser head 115 by the cable 112 and emitted from the laser head 115 toward the work piece area WS. The light receiving unit 118 receives the reflected light of the laser light LS projected on the work piece area WS.

[0020] In the present embodiment, the work piece sensor 11 is a laser sensor and functions as a step sensor for measuring the step amount St of the step surface SF shown in FIG. 1 and an edge sensor for detecting the edge E of the work piece W. The "step amount St" mentioned here is one of the shape information of the work piece area WS and is, for example, the linear separation distance between the first boundary portion W1d and the second boundary portion W2d when the first boundary portion W1d is projected onto the end surface W2c of the second work piece W2.

[0021] The position and orientation changing mechanism 13 shown in FIG. 2 changes the position and orientation of the laser head 115 and the welding torch 125 with respect to the work piece W according to the control command of the control device 15. In the present embodiment, the position and orientation changing mechanism 13 is an articulated robot having six rotational axes J1 to J6. Specifically, the articulated robot as the position and orientation changing mechanism 13 includes a robot arm 130 and a fixing member 135. The fixing member 135 is attached to the tip of the robot arm 130. The laser head 115 and the welding torch 125 are fixed to the fixing member 135 such that the laser head 115 is positioned forward in the welding progress direction with respect to the welding torch 125. Thereby, the position and orientation changing mechanism 13 changes the position and orientation of the laser head 115 and the welding torch 125 with respect to the welded area WS by integrally moving the laser head 115 and the welding torch 125 fixed to the fixing member 135. Note that the position and orientation changing mechanism 13 is not limited to an articulated robot, and may be, for example, a horizontal articulated robot. Further, the position and orientation changing mechanism 13 may be configured by combining, for example, an electric linear actuator or the like.

[0022] The control device 15 controls the operation of the welding device 10 and changes the welding conditions using the shape information of the welded area WS acquired using the work piece sensor 11. The control device 15 includes a CPU 150 and a storage unit 19.

[0023] The storage unit 19 stores various information including various programs for controlling the operation of the welding device 10 and a condition changing program used for changing predetermined welding conditions. The storage unit 19 includes a RAM, a ROM, a rewritable nonvolatile memory, and the like.

[0024] The CPU 150 functions as a welding condition changing unit 151, a sensor control unit 153, and an operation control unit 155 by developing various programs stored in the storage unit 19.

[0025] The welding condition changing unit 151 changes the initial value of the preset welding conditions using the shape information of the welding area WS acquired using the workpieces sensor 11. Specifically, the welding condition changing unit 151 calculates the amount of change with respect to the initial value of the welding conditions and outputs it to the operation control unit 155. The "welding conditions" mentioned here refer to, for example, the position of the welding torch 125, the posture of the welding torch 125, and the total amount of energy (in this embodiment, the arc AC) applied to the welding area WS. When welding the first workpiece W1 and the second workpiece W2, the initial value of the welding conditions is preset, for example, by teaching using a member similar to the first workpiece W1 and the second workpiece W2 to be welded. For example, the position of the welding torch 125, which is one of the welding conditions, is defined by the three-dimensional position in a predetermined coordinate system, that is, the coordinate values (x, y, z). In this case, the movement path R of the welding torch 125 (FIG. 4 described later) is defined, for example, as the coordinate values with respect to the elapsed time from the start of welding. Also, the posture of the welding torch 125, which is one of the welding conditions, is defined, for example, by the inclination angle θt (FIG. 6 described later). Also, the total amount of energy applied to the welding area WS as one of the welding conditions is defined, for example, by the magnitude of the welding voltage applied to the electrode 127 of the welding torch 125 and the workpiece W. Specifically, by changing the magnitude of the welding voltage applied to the electrode 127 of the welding torch 125 and the workpiece W, the magnitude of the welding current (the amount of energization) changes. Thereby, the total amount of energy applied to the welding area WS is defined. In this embodiment, the welding condition changing unit 151 changes the posture of the welding torch 125 according to the step amount St, which is one of the welding conditions.

[0026] The sensor control unit 153 controls the operation of the work piece sensor 11 according to a preset program. Further, in the present embodiment, the sensor control unit 153 uses the shape information of the weld area WS acquired by the work piece sensor 11 to change the position of the welding torch 125, which is one of the welding conditions, along the shape of the edge E of the work piece W, that is, the shape of the weld area WS including the shape of the groove K. The sensor control unit 153 calculates a preset amount of change in the position of the welding torch 125 and transmits it to the welding condition changing unit 151. Note that the control for changing the position of the welding torch 125 may be executed by the welding condition changing unit 151 instead of the sensor control unit 153.

[0027] The operation control unit 155 controls the operation of the welding apparatus 10. Specifically, when the operation control unit 155 receives the amount of change with respect to the initial value of the welding conditions from the welding condition changing unit 151 and the sensor control unit 153, it outputs the changed value obtained by reflecting the amount of change on the initial value of the welding conditions to each component such as the position and orientation changing mechanism 13 and the power supply device 121. As a result, the position of the welding torch 125, the attitude of the welding torch 125, the electrode 127 of the welding torch 125, and the magnitude of the welding voltage applied to the work piece W are changed.

[0028] In the present embodiment, the CPU 150 further has a general-purpose register 159. The general-purpose register 159 is a storage device provided inside the CPU 150 and stores the shape information of the weld area WS acquired by the work piece sensor 11. By acquiring the data stored in the general-purpose register 159, the welding condition changing unit 151 can increase the possibility of improving the calculation speed of the amount of change with respect to the initial value of the welding conditions. Note that the general-purpose register 159 is not an essential component. The shape information of the weld area WS acquired by the work piece sensor 11 may be stored in the storage unit 19, for example. Also, at least some of the functions of the CPU 150 may be realized by a hardware circuit.

[0029] FIG. 3 is a control block diagram showing the control modes of the groove following control and the step adaptation control. In FIG. 3, step numbers are also attached to explain the flow of the groove following control and the step adaptation control.

[0030] FIG. 4 is a diagram for explaining the details of the groove following control. FIG. 4 shows the state of the workpieces W as viewed from the surfaces W1a and W2a sides. Also, in FIG. 4, the movement paths R of the welding torch 125 and the workpiece sensor 11 along the shape of the groove K are indicated by arrows. Even when predetermined welding conditions are set using members similar to the first workpiece W1 and the second workpiece W2 to be welded, the optimal movement path R of the welding torch 125 may vary due to variations in the arrangement state of the workpiece W and the shape of the workpiece W itself. Therefore, the sensor control unit 153 executes control (hereinafter referred to as groove following control) to change the position of the welding torch 125 according to the positions of the boundary portions W1d and W2d in order to optimize the movement path R of the welding torch 125 during welding, for example, as follows.

[0031] As shown in FIG. 3, in the groove following control, first, the workpiece sensor 11 measures the position of the edge E (FIG. 4) of the workpiece W, which is one of the physical quantities (step S1). The workpiece sensor 11 detects the position of the edge E of the workpiece W including the first boundary portion W1d and the second boundary portion W2d by, for example, detecting the reflected light when the laser light LS is irradiated onto the surfaces W1a and W2a sides of the first workpiece W1 and the second workpiece W2 by the light receiving unit 118.

[0032] Next, the sensor control unit 153 acquires the position of the edge E of the work W measured by the work sensor 11, and calculates the amounts of change Δx, Δy, and Δz in the position of the welding torch 125 at each time point from the start time to the end time of welding (hereinafter, during welding) (step S2). For example, when defining the position of the welding torch 125 at each time point during welding as the coordinate values in a predetermined coordinate system, the sensor control unit 153 calculates the x-coordinate value, y-coordinate value, and z-coordinate value indicating the center positions of the first boundary portion W1d and the second boundary portion W2d, respectively. Specifically, the sensor control unit 153 inputs the acquired coordinate value of the edge E into a predetermined relational expression indicating the correlation between the position of the edge E of the welding region WS and the suitable coordinate values of the welding torch 125, thereby calculating the x-coordinate value, y-coordinate value, and z-coordinate value indicating the center positions of the first boundary portion W1d and the second boundary portion W2d, respectively. The "center position" mentioned here refers to the center positions of the first boundary portion W1d and the second boundary portion W2d in the state where the members W1 and W2 are viewed from the surface W1a and W2a sides. Then, the difference between the coordinate values preset by teaching at each time point during welding and the coordinate values indicating the center positions of the first boundary portion W1d and the second boundary portion W2d is calculated as the amounts of change Δx, Δy, and Δz related to the position of the welding torch 125. Then, the sensor control unit 153 transmits the amounts of change Δx, Δy, and Δz related to the position of the welding torch 125 to the welding condition changing unit 151.

[0033] Next, the welding condition changing unit 151 outputs the amounts of change Δx, Δy, and Δz related to the position of the welding torch 125 to the operation control unit 155 (step S8). Note that the welding condition changing unit 151 may output the amounts of change with respect to the initial values of the welding conditions to the operation control unit 155 and store them in the second data area 159b, the storage unit 19, and the like. By doing so, for example, the user can confirm the amounts of change with respect to the initial values of the welding conditions at a desired timing.

[0034] Next, the operation control unit 155 outputs to the position and orientation changing mechanism 13 a changed value (welding condition) that is a coordinate value indicating the position of the welding torch 125 and reflects the amount of change with respect to the coordinate value preset by teaching (step S9). Thereby, as shown in FIG. 4, the welding torch 125 can be moved along an appropriate movement path R along the shape of the groove K.

[0035] FIG. 5 is a diagram for explaining the details of the step adaptation control. Due to variations in the arrangement state of the workpiece W and the shape of the workpiece W itself, etc., the shape of the welded region WS may vary. For example, the step amount St of the step surface SF formed in a state where the end surface W1c of the first workpiece W1 and the end surface W2c of the second workpiece W2 are butted against each other may be different between one side Wa and the other side Wb of the workpiece W. In the example shown in FIG. 5, in a state where the end surface W1c of the first workpiece W1 and the end surface W2c of the second workpiece W2 are butted against each other, the step amount St1 on one side Wa of the workpiece W is smaller than the step amount St2 on the other side Wb of the workpiece W. Thus, when there are variations in the shape of the welded region WS, even if the groove following control is executed, there may be welding defects such as an insufficient heat input amount resulting in an inability to obtain the desired penetration amount, or an excessive heat input amount causing unintended holes to be formed in the workpiece W. Therefore, the welding condition changing unit 151 executes control (hereinafter referred to as step adaptation control) to change the posture of the welding torch 125 according to the step amount St, for example, as follows. Here, the "penetration amount" mentioned here is, for example, the shape of the welded joint portion WF and the penetration depth.

[0036] As shown in Fig. 3, in the step adaptation control, first, the welded object sensor 11 measures a physical quantity related to the welded region WS (for example, the position of the edge E) (step S1). Next, the welded object sensor 11 calculates the step amount St using the physical quantity measured in step S1 (step S3). Specifically, the welded object sensor 11 calculates, for example, the difference between the first boundary portion W1d and the second boundary portion W2d as the step amount St based on the position of the edge E of the welded object W. Note that the method for calculating the step amount St is not limited to this. Also, the step amount St may be calculated by the control device 15 based on the measured physical quantity. In the present embodiment, the calculated step amount St is stored in the first data area 159a of the general-purpose register 159 (step S4).

[0037] Next, the welding condition changing unit 151 acquires the step amount St stored in the first data area 159a and calculates the tilt angle θt of the welding torch 125 (step S5). Fig. 6 is a first diagram for explaining the tilt angle θt of the welding torch 125. Fig. 6 schematically shows a state in which the welded region WS of the welded object W is viewed from one side Wa (Fig. 5). Fig. 7 is a second diagram for explaining the tilt angle θt of the welding torch 125. Fig. 7 schematically shows a state in which the welded region WS of the welded object W is viewed from the other side Wb (Fig. 5).

[0038] The posture of the welding torch 125, which is one of the welding conditions, is defined, for example, by the inclination angle θt with respect to the axial direction PL of the welding torch 125s in the reference posture. In the present embodiment, the axial direction PL of the welding torch 125s in the predetermined reference posture is the direction along the gravitational direction. The inclination angle θt of the welding torch 125 is defined, for example, by the three-dimensional rotation amount with respect to the reference posture, that is, the rotation amounts Δrx, Δry, and Δrz from the reference posture in the x-direction, y-direction, and z-direction. The welding condition changing unit 151 calculates the rotation amounts Δrx, Δry, and Δrz of the welding torch 125 in each direction by substituting the step amount St into a predetermined relational expression showing the correlation between the step amount St generated in the welded region WS and the suitable rotation amounts Δrx, Δry, and Δrz of the welding torch 125 in each direction, and sets it as the inclination angle θt of the welding torch 125. At this time, the welding condition changing unit 151 calculates the rotation amounts Δrx, Δry, and Δrz as the change amounts related to the posture of the welding torch 125 so that the inclination angle θt of the welding torch 125 becomes larger as the step amount St becomes larger so that energy is applied to the step surface SF. In the present embodiment, the rotation amounts Δrx, Δry, and Δrz representing the calculated inclination angle θt are stored in the second data area 159b of the general-purpose register 159 (step S7).

[0039] Next, the welding condition changing unit 151 acquires the rotation amounts Δrx, Δry, and Δrz representing the inclination angle θt of the welding torch 125 stored in the second data area 159b, and outputs them to the operation control unit 155 (step S8). Then, the operation control unit 155 outputs the rotation amounts Δrx, Δry, and Δrz representing the inclination angle θt with respect to the axial direction PL of the welding torch 125s in the reference posture as the changed welding condition to the position and posture changing mechanism 13 (step S9). Thereby, the posture of the welding torch 125 can be changed according to the step amount St.

[0040] FIG. 8 is a diagram showing the difference in the welding state depending on the presence or absence of step adaptation control. The upper diagram of FIG. 8 shows the welding state when welding the weld area WS shown in FIG. 7 without performing step adaptation control. The lower diagram of FIG. 8 shows the welding state when welding the weld area WS shown in FIG. 7 while performing step adaptation control.

[0041] As shown as the non-molten area NM in the upper diagram of FIG. 8, when welding the weld area WS of the workpiece W having the step surface SF without performing step adaptation control, a part of the end surface W1c of the first workpiece W1 in the weld area WS may not melt. In other words, when welding is performed without changing the inclination angle θt of the welding torch 125 according to the step amount St, a desired penetration amount may not be obtained for the side of the weld area WS that is particularly away from the arc AC generation position. On the other hand, as shown as the molten area M in the lower diagram of FIG. 7, when welding the weld area WS of the workpiece W having the step surface SF while performing step adaptation control, the portion M located on the side away from the arc AC in the weld area WS is also melted. That is, by welding the weld area WS of the workpiece W having the step surface SF in a state where the inclination angle θt of the welding torch 125 is changed according to the step amount St, energy can be more reliably applied to the step surface SF.

[0042] According to the first embodiment described above, when there are variations in the shape of the welded region WS, the control device 15 can change the inclination angle θt (posture) of the welding torch 125, which is one of the welding conditions, using the shape information of the welded region WS obtained by the work-piece sensor 11. Specifically, as shown in FIGS. 6 and 7, when a stepped surface SF is present in the welded region WS, the control device 15 executes stepped surface adaptation control to change the inclination angle θt of the welding torch 125 according to the step amount St. By doing so, even when a stepped surface SF is present in the welded region WS, by changing the inclination angle θt of the welding torch 125 according to the step amount St, energy can be more reliably applied to the stepped surface SF. As a result, it is possible to reduce the possibility that the penetration amount is insufficient in a portion such as the portion of the welded region WS located on the side away from the arc AC in the welded region WS, that is, a portion where energy is relatively difficult to be applied. Therefore, it is possible to reduce the possibility that welding defects such as an undesired penetration amount cannot be obtained when there are variations in the shape of the welded region WS. For this reason, it is possible to reduce the possibility that the strength of the welded joint WF decreases.

[0043] Further, according to the first embodiment described above, in addition to the stepped surface adaptation control, the control device 15 executes groove tracing control. As a result, when there are variations in the shape of the welded region WS, the movement path R and the posture (inclination angle θt) of the welding torch 125 can be changed and optimized according to the shape of the welded region WS.

[0044] Note that the relational expression representing the correlation between the position of the edge E of the welded region WS and the coordinate values of the welding torch 125, and the relational expression representing the correlation between the step amount St of the welded region WS and the inclination angle θt of the welding torch 125 may be generated as a set of numerical data such as a correlation table.

[0045] B. Second Embodiment: FIG. 9 is a flowchart showing a step control method in the second embodiment. FIG. 10 is a graph for explaining the details of the step adaptation control in the second embodiment. In the first embodiment, the welding condition changing unit 151 changes the rotation amounts Δrx, Δry, and Δrz representing the tilt angle θt of the welding torch 125 so that the larger the step amount St, the larger the tilt angle θt of the welding torch 125. On the other hand, in this embodiment, a part of the changing mode of the tilt angle θt of the welding torch 125 according to the step amount St (control mode of the step adaptation control) is different from that in the first embodiment. The configurations of the welding apparatus 10 and the workpiece W are the same as those in the first embodiment (FIGS. 1 and 2). The same steps as those in the first embodiment and the same configurations are denoted by the same reference numerals and the description thereof is omitted.

[0046] In this embodiment, the control device 15 executes three types of controls, i.e., dead zone control, linear control, and upper limit control, according to the magnitude of the step amount St. In FIG. 10, in the relational expression F showing the correlation between the step amount St of the welded region WS and the preferable tilt angle θt of the welding torch 125, the regions where each control is executed are illustrated. As shown in FIG. 9, the control device 15 compares the step amount St calculated in step S3 with the thresholds P1 and P2 related to the predetermined step amount St, and determines which control to execute.

[0047] The welding condition changing unit 151 determines whether or not the step amount St calculated in step S3 is less than a predetermined first threshold value P1 (step S51). The first threshold value P1 is set in advance, for example, when there is a range in which a desired penetration amount can be obtained without changing the tilt angle θt of the welding torch 125 with respect to the step amount St. The first threshold value P1 is, for example, the limit value of the step amount St that does not cause welding defects when welding is performed without changing the tilt angle θt of the welding torch 125. When the step amount St is less than the first threshold value P1 (step S51: Yes), the welding condition changing unit 151 maintains the rotation amounts Δrx, Δry, and Δrz representing the tilt angle θt of the welding torch 125 at zero, assuming that the step amount St at the welding target location exists in the dead zone control region. That is, when the step amount St is less than the first threshold value P1 (step S51: Yes), the welding condition changing unit 151 maintains the welding torch 125 in the reference posture (step S52).

[0048] On the other hand, when the step amount St is equal to or greater than the first threshold value P1 (step S51: No), the welding condition changing unit 151 determines whether or not the step amount St at the welding target location is less than a second threshold value P2 that is greater than the first threshold value P1, assuming that the step amount St exists in the linear control region (step S54). The second threshold value P2 is set in advance, for example, when increasing the tilt angle θt of the welding torch 125 too much may cause the welding torch 125 to adopt an unreasonable posture or may prevent energy from being applied to a desired position in the welded region WS. The second threshold value P2 is, for example, the step amount St corresponding to the upper limit value θm of the tilt angle θt of the welding torch 125 that can avoid the above problems when linearly controlled by a predetermined relational expression F. When the step amount St is less than the second threshold value P2 (step S54: Yes), the welding condition changing unit 151 changes the rotation amounts Δrx, Δry, and Δrz representing the tilt angle θt of the welding torch 125 so that the tilt angle θt of the welding torch 125 increases as the step amount St increases, according to a predetermined relational expression F (step S56).

[0049] On the other hand, when the step amount St is equal to or greater than the second threshold value P2 (step S54: No), the welding condition changing unit 151 maintains the inclination angle θt of the welding torch 125 at the upper limit value θm of the inclination angle θt determined in advance, assuming that the step amount St at the welding target location is within the upper limit value control region (step S58). That is, the welding condition changing unit 151 maintains the rotation amounts Δrx, Δry, and Δrz of the welding torch 125 at the upper limit value θm determined in advance. Then, the welding condition changing unit 151 outputs the change amounts Δrx, Δry, and Δrz related to the posture (inclination angle θt) of the welding torch 125 determined as above to the operation control unit 155 (step S8). The processing contents after step S9 are the same as those in the first embodiment.

[0050] According to the second embodiment described above, as shown in FIGS. 9 and 10, the control device 15 does not change the posture of the welding torch 125 from the reference posture when the step amount St is less than the predetermined first threshold value P1. By doing so, when there is a range in which a desired penetration amount can be obtained without changing the inclination angle θt of the welding torch 125 for the step amount St, welding can be performed without changing the inclination angle θt of the welding torch 125. Thereby, for example, since the position and posture changing mechanism 13 can omit the operation of changing the inclination angle θt of the welding torch 125, the time required for welding can be shortened.

[0051] Also, according to the second embodiment described above, as shown in FIGS. 9 and 10, the control device 15 maintains the inclination angle θt of the welding torch 125 at the upper limit value θm when the step amount St is equal to or greater than the second threshold value P2 corresponding to the upper limit value θm of the inclination angle θt of the welding torch 125. By doing so, the inclination angle θt of the welding torch 125 can be changed without the welding torch 125 taking an unreasonable posture. Thereby, the possibility that the welding torch 125 or the member supporting the welding torch 125 is damaged or fails can be reduced.

[0052] Further, according to the second embodiment, as shown in FIGS. 9 and 10, when the step amount St is equal to or greater than the second threshold value P2 corresponding to the upper limit value θm of the inclination angle θt of the welding torch 125, the control device 15 maintains the inclination angle θt of the welding torch 125 at the upper limit value θm. By doing so, it is possible to reduce the possibility that energy is not applied to the desired position in the welded region WS due to excessive tilting of the welding torch 125. That is, energy can be more reliably applied to the desired position of the welded region WS.

[0053] In the step adaptation control, the dead zone control and the upper limit control may be both executed as in the second embodiment, or either one of them may be executed.

[0054] C. Third Embodiment: In the above embodiment, the control device 15 executes the groove tracing control for changing the position of the welding torch 125 according to the positions of the boundary portions W1d and W2d among the variations in the shape of the welded region WS, and the step adaptation control for changing the posture of the welding torch 125 according to the step amount St. In contrast, in this embodiment, the control device 15 executes the groove tracing control and the control for changing the total amount of energy applied to the welded region WS according to the variation in the shape of the groove K among the variations in the shape of the welded region WS (hereinafter referred to as groove adaptation control). As a result, a part of the function of the welded object sensor 11 and a part of the control mode by the control device 15 are different from those in the above embodiment. The groove tracing control is the same as in the first embodiment. The same steps and the same configurations as those in the above embodiment are denoted by the same reference numerals and the description thereof is omitted.

[0055] FIG. 11 is a diagram showing an example of the variation in the shape of the groove K. In FIG. 11, as an example, the case where the welded region WS has a groove KI of the I type (hereinafter referred to as the I-type groove KI) and the case where the welded region WS has a groove KV of the V type (hereinafter referred to as the V-type groove KV) are shown, and the welding process is schematically illustrated. That is, in FIG. 11, the shape of the groove K itself is different. FIG. 12 is a diagram showing the difference in the penetration amount due to the difference in the shape of the groove K. The upper diagram of FIG. 12 is a view of the state after welding of the welded object W having the I-type groove KI in the welded region WS as seen from the back surfaces W1b and W2b sides. The lower diagram of FIG. 12 is a view of the state after welding of the welded object W having the V-type groove KV in the welded region WS as seen from the back surfaces W1b and W2b sides.

[0056] Hereinafter, as shown in FIG. 11, the boundary W1d between the surface W1a and the end face W1c of the first workpiece W1 is referred to as the "first boundary W1d on the surface side". The boundary W2d between the surface W2a and the end face W2c of the second workpiece W2 is referred to as the "second boundary W2d on the surface side". In the present embodiment, the first boundary W1d on the surface side and the second boundary W2d on the surface side are located on the side of the welding torch 125 and the workpiece sensor 11. The linear separation distance between the first boundary W1d on the surface side and the second boundary W2d on the surface side, that is, the separation distance between the first workpiece W1 and the second workpiece W2 on the surface W1a, W2a side is referred to as the "gap amount G". In the examples shown in FIGS. 11 and 12, the gap amount G in the welded region WS having the I-shaped groove KI is the same as the gap amount G in the welded region WS having the V-shaped groove KV. Further, the boundary W1e between the back surface W1b and the end face W1c of the first workpiece W1 is referred to as the "first boundary W1e on the back surface side". Further, the boundary W2e between the back surface W2b and the end face W2c of the second workpiece W2 is referred to as the "second boundary W2e on the back surface side". In the present embodiment, the first boundary W1e on the back surface side and the second boundary W2e on the back surface side are located on the side away from the welding torch 125 and the workpiece sensor 11. The linear separation distance between the first boundary W1e on the back surface side and the second boundary W2e on the back surface side, that is, the separation distance between the first workpiece W1 and the second workpiece W2 on the back surface W1b, W2b side is referred to as the "root gap RG". In the examples shown in FIGS. 11 and 12, due to the difference in the shape of the groove K between the I-shaped groove KI and the V-shaped groove KV, the root gap RG in the welded region WS having the I-shaped groove KI is different from the root gap RG in the welded region WS having the V-shaped groove KV. Note that in FIGS. 11 and 12, in order to clarify the difference in the penetration amount due to the difference in the shape of the groove K, a V-shaped groove KV with a root gap RG of zero is shown.

[0057] As shown in Fig. 11, when welding under the same welding conditions, if the gap amount G is the same and there is a difference in the root gap RG, the I-shaped groove KI with a larger root gap RG than the V-shaped groove KV allows the arc AC as energy to more easily reach the back-side first boundary portion W1e and the back-side second boundary portion W2e. Therefore, in the examples shown in Figs. 11 and 12, when the welded region WS has an I-shaped groove KI with a root gap RG larger than that of the V-shaped groove KV, the back-side first boundary portion W1e and the back-side second boundary portion W2e are sufficiently melted to form a welded joint portion WF. Actually, when the shape of the back surfaces W1b, W2b of the workpiece W after welding is represented by the line Ib, the line Ib has a straight portion along the back surfaces W1b, W2b of the workpiece W and a curved portion along the welded joint portion WF. That is, the larger the root gap RG, the more easily a molten region M is formed on the back surfaces W1b, W2b side, and it is easier to weld the first workpiece W1 and the second workpiece W2 by full penetration welding.

[0058] On the other hand, when welding under the same welding conditions, even if the gap amount G is the same, if the root gap RG is small, the arc AC may have difficulty reaching the back-side first boundary portion W1e and the back-side second boundary portion W2e. Actually, when the shape of the back surfaces W1b, W2b of the workpiece W after welding is represented by the line Vb, the line Vb has only a straight portion along the back surfaces W1b, W2b of the workpiece W. That is, when determining the variation in the groove K shape by the gap amount G and changing the total amount of energy applied to the welded region WS according to the gap amount G, there may be a case where the welded joint portion WF is formed without melting the back-side first boundary portion W1e and the back-side second boundary portion W2e. In other words, when determining the variation in the groove K shape by the difference in the gap amount G and changing the total amount of energy applied to the welded region WS according to the difference in the gap amount G, it is difficult to form a molten region M on the back surfaces W1b, W2b side, and there may be a case where the desired penetration amount cannot be obtained.

[0059] FIG. 13 is a view of the welded region WS of the workpiece W in a state where the shape of the groove K varies, as seen from the surfaces W1a and W2a sides. In FIG. 13, a case is illustrated where the gap amount G in a state where the end face W1c of the first workpiece W1 and the end face W2c of the second workpiece W2 are butted together is different between one side Wa and the other side Wb of the workpiece W. Specifically, in FIG. 13, in a state where the end face W1c of the first workpiece W1 and the end face W2c of the second workpiece W2 are butted together, the gap amount G1 on one side Wa of the workpiece W is smaller than the gap amount G2 on the other side Wb of the workpiece W. Thus, even when there is a variation in the shape of the groove K due to the different gap amounts G1 and G2 within the same welded region WS, the same can be said as in the case where the shape of the groove K itself is different (FIGS. 11 and 12).

[0060] Here, the inventors of the present application have found that even when there is a variation in the shape of the groove K, a desired penetration amount can be obtained by changing the total amount of energy applied to the welded region WS according to the root gap RG. Therefore, in the present embodiment, the welding condition changing unit 151 determines the variation in the shape of the groove K based on the root gap RG, and changes the total amount of energy applied to the welded region WS, which is one of the welding conditions, according to the root gap RG.

[0061] FIG. 14 is a control block diagram showing the control mode of the groove adaptation control. In FIG. 14, step numbers are also attached to explain the flow of the groove adaptation control. In the present embodiment, the workpiece sensor 11 is a laser sensor, and functions as a gap sensor that measures the gap amount G shown in FIG. 11 and an angle sensor that measures the surface angle θs formed by the surface W1a of the first workpiece W1 and the surface W2a of the second workpiece W2.

[0062] As shown in FIG. 14, in the groove adaptation control, first, the workpiece sensor 11 measures the gap amount G and the surface angle θs as physical quantities (step S1). Next, the workpiece sensor 11 calculates the root gap RG (step S3a).

[0063] FIG. 15 is a diagram for explaining an example of a method for calculating the root gap RG. In FIG. 15, a welded region WS of a workpiece W having a V-groove KV with the first workpiece W1 and the second workpiece W2 having the same plate thickness t and a non-zero root gap RG is illustrated as viewed from one side Wa or the other side Wb of the workpiece W. In the present embodiment, the workpiece sensor 11 calculates the root gap RG using the plate thickness t, the surface angle θs, and the gap amount G of the first workpiece W1 and the second workpiece W2. Specifically, the workpiece sensor 11 first substitutes the surface angle θs obtained by measurement into the following formula (1) to calculate the bevel angle θr. The bevel angle θr can be calculated by dividing by 2 the angle obtained by subtracting 180° from the surface angle θs, as shown in the following formula (1). Bevel angle θr = (Surface angle θs - 180°) ÷ 2 Formula (1) Also, as shown in FIG. 15, in the welded region WS having a V-groove KV, the bevel angle θr corresponds to the angle obtained by dividing by 2 the groove angle formed by the end face W1c of the first workpiece W1 and the end face W2c of the second workpiece W2.

[0064] Next, the workpiece sensor 11 substitutes the plate thickness t, the bevel angle θr, and the gap amount G of the first workpiece W1 and the second workpiece W2 into the following formula (2) to calculate the root gap RG. At this time, the plate thickness t is stored in advance in the first data area 159a (FIG. 14) of the general-purpose register 159 via an input operation unit (not shown), for example. Root gap RG = Gap amount G - 2 × (Plate thickness t × sin θr) Formula (2)

[0065] Note that the method for calculating the root gap RG is not limited to this. Also, the root gap RG may be calculated by the control device 15 based on the measured physical quantities, the stored data determined in advance, and the like. As shown in FIG. 14, the calculated root gap RG is stored in the first data area 159a of the general-purpose register 159 (step S4).

[0066] Next, the welding condition changing unit 151 acquires the root gap RG stored in the first data area 159a, and calculates a change amount ΔV related to the total amount of energy to be applied to the welded area WS (step S6). In the present embodiment, it is assumed that the total amount of energy to be applied to the welded area WS is defined by the size of the welding voltage applied to the electrode 127 of the welding torch 125 and the workpiece W shown in FIG. 2. For example, in order to obtain a desired penetration amount, the welding condition changing unit 151 substitutes the root gap RG into a relational expression showing the correlation between the root gap RG and the total amount of energy to be applied to the welded area WS, thereby calculating a suitable welding voltage. At this time, the smaller the root gap RG, the larger the total amount of energy (welding voltage) required to melt the first back surface boundary portion W1e and the second back surface boundary portion W2e. Therefore, the smaller the root gap RG, the larger the welding voltage that defines the total amount of energy to be applied to the welded area WS. Then, the welding condition changing unit 151 calculates the difference between the initial value of the welding voltage preset by teaching and the suitable welding voltage according to the root gap RG as the change amount ΔV with respect to the initial value of the total amount of energy to be applied to the welded area WS. In the present embodiment, the change amount ΔV related to the total amount of energy to be applied to the welded area WS is stored in the second data area 159b (step S7).

[0067] Next, the welding condition changing unit 151 acquires the change amount ΔV with respect to the initial value of the total amount of energy to be applied to the welded area WS stored in the second data area 159b, and outputs it to the operation control unit 155 (step S8). Then, the operation control unit 155 outputs the changed value obtained by reflecting the change amount ΔV on the initial value of the total amount of energy to be applied to the welded area WS to the power supply device 121 (FIG. 2) (step S9). Thereby, the total amount of energy to be applied to the welded area WS can be changed according to the root gap RG.

[0068] According to the third embodiment, as shown in FIG. 11, the penetration amount depends on at least the size of the root gap RG among the shapes of the groove K. Therefore, as shown in FIG. 14, when there are variations in the shape of the groove K, the control device 15 executes groove adaptation control. By doing so, even when there are variations in the shape of the groove K, the total amount of energy applied to the weld area WS can be changed according to the root gap RG. As a result, it is possible to reduce the possibility that the penetration amount of a portion such as a portion of the weld area WS located on the side away from the arc AC in the weld area WS, where energy (in this embodiment, the arc AC) is relatively difficult to be applied, is insufficient. Therefore, when there are variations in the shape of the groove K, it is possible to further reduce the possibility of welding defects such as the desired penetration amount not being obtained.

[0069] Also, according to the third embodiment, the work piece sensor 11 measures the gap amount G and the surface angle θs as physical quantities related to the weld area WS. Then, as shown in FIG. 15, the work piece sensor 11 can calculate the root gap RG using the gap amount G, the surface angle θs, and the plate thickness t. Thereby, for example, even when the root gap RG cannot be directly measured because the laser light LS of the work piece sensor 11 located on the surfaces W1a, W2a side does not reach the back surfaces W1b, W2b side sufficiently, the root gap RG can be calculated without separately providing a sensor.

[0070] D. Other Embodiments: D-1. Other Embodiment 1: In the above embodiment, the shape of the groove K was at least one of the I-shaped groove KI and the V-shaped groove KV, but the present disclosure is not limited to this. Even when a groove K having a shape other than the I-shaped groove KI and the V-shaped groove KV exists in the weld area WS, the control of the present disclosure can be applied.

[0071] D-2. Other Embodiment 2: In the above-described embodiment, the position and orientation changing mechanism 13 integrally moved or tilted the laser head 115 and the welding torch 125. However, the present disclosure is not limited to this. The position and orientation changing mechanism 13 may move or tilt the laser head 115 and the welding torch 125 independently of each other. Further, the position and orientation changing mechanism 13 may change the position and orientation of the laser head 115 and the welding torch 125 with respect to the welded region WS by moving or tilting the laser head 115, the welding torch 125, and the stage 14, respectively. Even in such a form, the position and orientation changing mechanism 13 can change the position and orientation of the laser head 115 and the welding torch 125 with respect to the welded region WS.

[0072] D-3. Other Embodiment 3: In the above-described embodiment, as shown in FIG. 2, the welding apparatus 10 was an arc welding apparatus that welded the first workpiece W1 and the second workpiece W2 by arc welding to manufacture the workpiece W. However, the present disclosure is not limited to this. The welding apparatus 10 may be an apparatus that welds the workpiece W by another welding method.

[0073] D-4. Other Embodiment 4: In the above-described embodiment, in the step adaptation control, the welding condition changing unit 151 only changed the tilt angle θt of the welding torch 125. However, the present disclosure is not limited to this. The welding condition changing unit 151 may change other welding conditions (for example, the movement path R (position) of the welding torch 125, the total amount of energy applied to the welded region WS) in the step adaptation control so as to obtain a desired penetration amount regardless of the step amount St. In this case, the welding condition changing unit 151 calculates the amount of change with respect to the initial value of the welding condition to be changed by substituting the step amount St into a predetermined relational expression indicating the correlation between the step amount St generated in the welded region WS and the suitable value of the welding condition to be changed.

[0074] For example, when the control device 15 executes both the groove following control and the step adaptation control, the welding condition changing unit 151 may calculate the change amounts Δx, Δy, and Δz related to the position of the welding torch 125 in step S5 shown in FIG. 3. The welding condition changing unit 151 calculates the change amounts Δx, Δy, and Δz related to the position of the welding torch 125 by substituting the step amount St into a relational expression showing the correlation between the step amount St of the welded region WS and the suitable position (coordinate value) of the welding torch 125 at each point in time during welding, for example. At this time, the change amounts Δx, Δy, and Δz of the position of the welding torch 125, that is, the change amounts Δx, Δy, and Δz with respect to the coordinate values preset by teaching, are calculated by both the sensor control unit 153 and the welding condition changing unit 151. Therefore, in step S8, the welding condition changing unit 151 outputs, for example, the total value of the change amounts Δx, Δy, and Δz related to the position of the welding torch 125 calculated in steps S2 and S5 to the operation control unit 155. In such a form, the control device 15 can change the position of the welding torch 125 so as to realize both the groove following control and the step adaptation control.

[0075] D-5. Other Embodiment 5: According to the above embodiment, in the groove adaptation control, the welding condition changing unit 151 only changed the total amount of energy applied to the welded region WS. However, the present disclosure is not limited to this. The welding condition changing unit 151 may change other welding conditions (for example, the movement path R (position) of the welding torch 125, the inclination angle θt (posture) of the welding torch 125) in the groove adaptation control so that a desired penetration amount can be obtained regardless of the shape of the groove K. In this case, the welding condition changing unit 151 calculates the change amount with respect to the initial value of the welding condition to be changed by substituting the root gap RG into a predetermined relational expression showing the correlation between the root gap RG and the suitable value of the welding condition to be changed, for example. In such a form, the desired welding conditions can be changed in the groove adaptation control.

[0076] D-6. Other Embodiment 6: In the above-described embodiment, the control device 15 executed either the step adaptation control shown in FIG. 3 or the groove adaptation control shown in FIG. 14. However, the present disclosure is not limited to this. The control device 15 may execute both the step adaptation control and the groove adaptation control. In this case, for example, the welding condition changing unit 151 substitutes the step amount St and the root gap RG generated in the welded region WS into a relational expression indicating the correlation between the step amount St and the root gap RG and the suitable values of the welding conditions. In such a form, the welding condition changing unit 151 can calculate the change amount with respect to the initial value of the welding conditions, which is the change amount taking into account both the step amount St and the root gap RG. Thereby, when there are variations in the shape of the welded region WS, the possibility of welding defects can be further reduced.

[0077] The present disclosure is not limited to the above-described embodiments, and can be realized in various configurations without departing from the gist thereof. For example, the technical features of the embodiments corresponding to the technical features in each form described in the summary of the invention can be appropriately replaced or combined in order to solve some or all of the above-described problems or to achieve some or all of the above-described effects. Further, if the technical feature is not described as essential in this specification, it can be appropriately deleted.

Description of Reference Numerals

[0078] 10... Welding device, 11... Welded object sensor, 12... Arc welding part, 13... Position and posture changing mechanism, 14... Stage, 15... Control device, 19... Memory part, 111... Laser oscillator, 112... Cable, 115... Laser head, 118... Light receiving part, 121... Power supply device, 122, 123... Cable, 125, 125s... Welding torch, 127... Electrode, 130... Robot arm, 135... Fixed member, 150... CPU, 151... Welding condition changing part, 153... Sensor control part, 155... Operation control part, 159... General-purpose register, 159a... First data area, 159b... Second data area, AC... Arc, E... Edge, F... Relational expression, G, G1, G2... Gap, Ib, Vb... Line, J1~J6... Rotation axis, K... Groove, KI... I-shaped groove, KV... V-shaped groove, LS... Laser beam, M... Melting area, NM... Non-melting area, P1... First threshold value, P2... Second threshold value, PL... Axial direction, R... Movement path, RG... Root gap, SF... Step surface, St, St1, St2... Step amount, W... Welded object, W1... First welded object, W1a... Surface of the first welded object, W1b... Back surface of the first welded object, W1c... End face of the first welded object, W1d... First boundary part on the surface side, W1e... First boundary part on the back surface side, W2... Second welded object, W2a... Surface of the second welded object, W2b... Back surface of the second welded object, W2c... End face of the second welded object, W2d... Second boundary part on the surface side, W2e... Second boundary part on the back surface side, WF... Weld joint part, WS... Welded area, Wa... One side, Wb... The other side, t, t1, t2... Plate thickness, θm... Upper limit value, θs... Surface angle, θt... Tilt angle, θr... Bevel angle

Claims

1. A welding apparatus for welding a first workpiece and a second workpiece, A welding torch that applies energy toward a welded region that spans the first workpiece and the second workpiece to melt the welded region; a workpiece sensor that measures a physical quantity related to the welded region and acquires shape information of the welded region using the measured physical quantity; A control device that changes welding conditions using the shape information of the welded area acquired using the workpiece sensor, The first workpiece and the second workpiece each have a front surface located on the welding torch side and a back surface opposite to the front surface, The workpiece sensor includes: a step sensor for measuring a step amount of a step surface formed by the surface of the first workpiece and the surface of the second workpiece in the welding area; The control device includes: A welding device that changes the inclination angle, which is one of the welding conditions and is the inclination angle with respect to the axial direction of the welding torch in a standard position, so that the energy is applied to the step surface, so that the inclination angle becomes larger as the step amount increases.

2. 2. The welding apparatus of claim 1, The control device includes: The welding device changes the inclination angle so that the inclination angle increases as the step amount increases until the inclination angle reaches a predetermined upper limit value.

3. 2. The welding apparatus of claim 1, The control device includes: A welding device that maintains the tilt angle at zero without tilting the welding torch when the step amount is less than a predetermined threshold value.

4. A welding apparatus for welding a first workpiece and a second workpiece, A welding torch that applies energy toward a welded region that spans the first workpiece and the second workpiece to melt the welded region; a workpiece sensor that measures a physical quantity related to the welded region and acquires shape information of the welded region using the measured physical quantity; A control device that changes welding conditions using the shape information of the welded area acquired using the workpiece sensor, The first workpiece and the second workpiece are each a plate-like member having a front surface located on the welding torch side and a back surface opposite to the front surface, The workpiece sensor includes: an angle sensor for measuring a surface angle between the surface of the first workpiece and the surface of the second workpiece; a gap sensor for measuring a gap amount, which is a distance between the first workpiece and the second workpiece on the front surface side; The control device includes: a root gap, which is the distance between the first workpiece and the second workpiece on the back side, is calculated using the sheet thicknesses of the first workpiece and the second workpiece, the surface angle, and the gap amount, and the total amount of energy applied to the welded area, which is one of the welding conditions, is increased as the root gap becomes smaller.

Images