JP6686313B2 - Welding equipment - Google Patents

Description

  The present invention relates to a welding device that automatically performs multi-layer welding.

  Conventionally, in the case of multi-layer welding, for example, when automatically performing multi-layer welding on a lateral groove of a work piece, the shape of the groove is obtained in advance from design data and the obtained shape is stored and stored. Welding conditions were created based on the groove shape and saved as a welding condition database, and welding was performed based on the welding condition database (teaching playback method).

  In Patent Document 1, a pair of optical sensors for measuring the cross-sectional shape of the groove portion is provided adjacent to the welding torch, and the deepest position is selected from the cross-sectional shapes measured by the optical sensor, It is disclosed that a bead is formed along a line connecting the deepest position in the welding line direction.

JP-A-6-277843

  However, when the molten metal solidifies, the groove may shrink and the shape may be deformed.If there is a gap between the target position obtained from the data and the actual target position due to welding deformation, the operator manually It was necessary to correct the target position with.

  In view of the above situation, the present invention provides a welding device that can automate welding even when the groove shape changes.

  The present invention includes a welding torch that generates an arc in a groove, a wire supply unit that supplies a welding wire to the welding torch, a traveling drive unit that causes the welding torch to travel along a welding line, and the welding torch. A weaving drive unit for weaving, a sensor that measures a cross-sectional shape in the groove, a storage unit that stores a plurality of path patterns set corresponding to the cross-sectional shape, and the cross-sectional shape detected by the sensor From one of the plurality of path patterns, and a controller for executing welding based on the selected path pattern.

  In the present invention, the control unit detects an upper end and a lower end of a single bead based on the cross-sectional shape data in the groove measured by the sensor, and the upper end or the lower end of the single bead is used as a reference. The present invention relates to a welding device configured to determine a target position of a welding torch.

  In the present invention, the storage unit further includes a first threshold value for a remaining width between the upper end of a single bead of the latest pass and the groove and a second threshold value for a layer thickness of the upper end of the single bead of the latest pass. Is stored, the control unit determines whether the welding performed based on the cross-sectional shape data measured by the sensor is the bottom pass, and compares the remaining width with the first threshold value. However, the present invention relates to a welding apparatus configured to compare the layer thickness with the second threshold value and select a pass pattern.

  Further, according to the present invention, the storage unit stores three pass patterns of a lower end pass, an intermediate pass, and an upper end pass, and the control unit causes the lower end pass to be executed when welding to be executed is a lowermost pass. And selecting the intermediate path when the remaining width is larger than the first threshold value and selecting the upper end path when the remaining width is less than or equal to the first threshold value. It relates to a welding device.

  Further, in the present invention, the storage unit further stores an additional pass as a pass pattern, and the control unit compares the layer thickness with the second threshold after the upper end pass is performed, The present invention relates to a welding device configured to select the additional path when the thickness is equal to or less than the second threshold value.

  Furthermore, the present invention relates to a welding device in which the welding torch and the sensor are independently movable up and down, forward and backward, and rotatable.

  According to the present invention, the groove can be deformed by welding deformation, and even when the target position of the welding torch or the required welding amount of the bead is changed, it is possible to automate the welding without performing a separate correction process. Exerts the excellent effect of

It is a front view of the welding device concerning the example of the present invention. It is a perspective view of the welding device which concerns on the Example of this invention. It is explanatory drawing explaining the lamination | stacking state of the bead in a groove | channel, and the kind of pass selected. (A) is an explanatory view showing a case where a lower end path is selected, (B) is an explanatory view showing a case where an intermediate path is selected, and (C) is an explanatory view showing a case where an upper end path is selected. It is a figure. (A)-(D) is a sequence diagram explaining the multi-layer welding by the welding apparatus which concerns on the Example of this invention.

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

  First, referring to FIGS. 1 and 2, a welding apparatus 1 according to an embodiment of the present invention will be described. In FIG. 1, the vertical direction relative to the paper surface is the Z-axis direction, the horizontal direction relative to the paper surface is the X-axis direction, and the Z-axis direction and the direction orthogonal to the X-axis direction are the Y-axis directions. Also, in FIG. 2, the X-axis direction, the Y-axis direction, and the Z-axis direction are as illustrated.

  A disk-shaped lower workpiece 3 is placed on the pedestal 2, and a cylindrical upper workpiece 4 is placed on the lower workpiece 3. The lower workpiece 3 is provided with a circular hole that is concentric with the upper workpiece 4 and has the same diameter as the inner diameter of the upper workpiece 4. The upper workpiece 4 is composed of a base portion 4a and a main body portion 4b, and the base portion 4a is welded to the lower workpiece 3 in advance.

  The lower end of the main body portion 4b is notched so as to gradually widen toward the outer peripheral side over the entire circumference, and a groove 5 is formed. A backing material 6 is attached to the inner peripheral surface of the connecting portion between the base portion 4a and the main body portion 4b over the entire circumference. Multi-layer welding is performed on the groove 5.

  The base portion 4a and the main body portion 4b are temporarily fixed to each other via the backing material 6, the main body portion 4b is positioned concentrically with respect to the base portion 4a, and the main body portion 4b becomes self-supporting. ing.

  The welding device 1 is provided on the upper workpiece 4. The welding apparatus 1 has a cylindrical support member 7 having a closed upper end, and the support member 7 is fitted to the upper end portion of the upper workpiece 4 and the support member 7 and the main body are fitted together. It is positioned concentrically with the portion 4b. Further, the support member 7 and the main body portion 4b are fixed by a predetermined means such as a screw.

  A welding device main body 9 is provided on the support member 7 via a rotary shaft 8. The welding device body 9 is supported by the upper workpiece 4 via the support member 7 and is rotatable about the axis of the support member 7 via the rotary shaft 8. There is.

  A support pedestal portion 11 is provided on the rotary shaft portion 8. The support pedestal portion 11 is provided with a rotary motor 12 for rotating the welding device main body portion 9 and an upright column 13 extending vertically. A first elevating part 14 is provided on one surface of the column 13, and a second elevating part 15 is provided on the surface opposite to the column 13. The first elevating part 14 and the second elevating part 15 have the same structure.

  A first advancing / retreating portion 16 extending in the horizontal direction (X-axis direction) toward one end side (left side with respect to the paper surface in FIG. 1) is vertically moved (Z-axis direction) in the first elevating / lowering unit 14. It is possible. The first elevating unit 14 has a vertically elevating first guide shaft 17, a first elevating screw rod 18, and a first elevating motor 19 connected to the first elevating screw rod 18. ing. The first advancing / retreating part 16 is slidably fitted to the first elevating guide shaft 17 and screwed to the first elevating screw rod 18. When the first lifting screw rod 18 is rotated by the first lifting motor 19, the first advancing / retreating portion 16 moves up and down along the first lifting guide shaft 17.

  The first advancing / retreating unit 16 is provided with a sensor unit 21 so as to be able to advance / retreat. The first advancing / retreating portion 16 includes a first advancing / retreating guide shaft (not shown) provided in a horizontal direction, a first advancing / retreating screw rod (not shown), and a first advancing / retreating screw rod connected to the first advancing / retreating screw rod. It has an advancing / retreating motor 22. The first advancing / retreating motor 22 rotates the first advancing / retreating screw rod so that the sensor portion 21 moves back and forth in the horizontal direction (X-axis direction) along the first advancing / retreating guide shaft.

  The sensor part 21 has a sensor support part 23 depending from the first advancing / retreating part 16 and a sensor 24 provided at a lower end of the sensor support part 23, and rotates the sensor 24 in a predetermined direction. It has a first pitch motor (not shown) and a first roll motor (not shown). The first pitch motor rotates the sensor 24 around a first pitch shaft 25 extending in the Y-axis direction, and the first roll motor centers a first roll shaft 26 extending in the X-axis direction. The sensor 24 is rotated. That is, the sensor 24 is rotatable about two horizontal axes (X axis and Y axis) orthogonal to the vertical axis (Z axis).

  The sensor 24 is, for example, a laser sensor, and includes a laser irradiator 27 that irradiates the groove 5 with a line laser, and a camera 28 that photographs the inside of the groove 5. The sensor 24 acquires cross-sectional shape data in the groove 5 based on an image of the line laser irradiated in the groove 5 acquired by the camera 28, and based on the cross-sectional shape data, the sensor 24 acquires the cross-sectional shape data. The cross-sectional shape inside the groove 5 can be measured. That is, the upper and lower ends of the single bead 29 formed in the groove 5 as shown in FIG. 3 can be detected.

  The second elevating / lowering portion 15 is provided with a second advancing / retreating portion 31 extending in the horizontal direction (X-axis direction) toward the other end side so as to be vertically movable (Z-axis direction). The second elevating unit 15 includes a vertically elevating second elevating guide shaft (not shown), a second elevating screw rod (not shown), and a second elevating screw rod connected to the second elevating screw rod (not shown). And a lifting motor 32. By rotating the second lifting screw rod by the second lifting motor 32, the second advancing / retreating portion 31 moves up and down along the second lifting guide shaft.

  A torch portion 33 is provided in the second advancing / retreating portion 31 so as to be able to advance / retreat. The second advancing / retreating portion 31 has a second advancing / retreating guide shaft 34 provided in a horizontal direction, a second advancing / retreating screw rod 35, and a second advancing / retreating motor 36 connected to the second advancing / retreating screw rod 35. ing. By rotating the second advancing / retreating screw rod 35 by the second advancing / retreating motor 36, the torch portion 33 moves forward / backward in the horizontal direction (X-axis direction) along the second advancing / retreating guide shaft 34. There is.

  The torch part 33 is provided on a torch support part 39 having two upper and lower shelf plate parts 37, 38, a torch body part 41 hung from the torch support part 39, and a lower end of the torch body part 41. And a welding torch 42. Further, the torch part 33 has a yaw motor 43 provided on the upper shelf plate part 37, a second pitch motor 44 and a second roll motor 45 provided on the lower shelf plate part 38. ing.

  The yaw motor 43 rotates the welding torch 42 together with the second pitch motor 44 and the second roll motor 45 about a yaw shaft 46 extending in the Z-axis direction. The second pitch motor 44 rotates the welding torch 42 around a second pitch shaft 48 extending in the Y-axis direction, and the second roll motor 45 extends a second pitch motor 48 in the X-axis direction. The welding torch 42 is rotated around the roll shaft 47. That is, the welding torch 42 is rotatable about three axes about a vertical axis (Z axis) and two horizontal axes (X axis and Y axis) orthogonal to the vertical axis.

  As described above, the sensor 24 and the welding torch 42 can independently move up and down in the vertical direction and can advance and retreat in the horizontal direction. The sensor 24 can rotate about two horizontal axes, and the welding torch 42 can rotate about two vertical axes and two horizontal axes. In addition, a traveling drive unit for moving the sensor 24 and the welding torch 42 along the welding line of the groove 5 by the rotary motor 12, the first elevating motor 19, the second elevating motor 32, and the like. Composed. Further, a weaving drive unit for reciprocating the tip of the welding wire supplied to the welding torch 42 in the groove 5 by the yaw motor 43, the second pitch motor 44, the second roll motor 45, and the like. Composed.

  The welding device 1 also has a controller 49. The controller 49 controls the rotary motor 12, the first elevating motor 19, the first advancing / retreating motor 22, the first pitch motor, the first roll motor, the second elevating motor 32, and the second advancing / retreating motor 36. , The yaw motor 43, the second pitch motor 44, and the second roll motor 45 are controlled, the arc generated from the tip of the welding torch 42 is controlled, and the inside of the groove 5 by the sensor 24 is controlled. The surface shape (cross-sectional shape) of the laminated bead 51 (see FIG. 3) is measured.

  Further, the control unit 49 has a storage unit 52. In the storage unit 52, a plurality of paths set in correspondence with the cross-sectional shape data in the groove 5 measured in advance before welding and the cross-sectional shape data in the groove 5 measured by the sensor 24. The pattern and the torch angle corresponding to the plurality of pass patterns are stored, and the sectional shape data in the groove 5 measured by the sensor 24 and the measurement position at that time are associated and sequentially stored. Further, the storage unit 52 stores a control program such as a sequence program for selecting a pass pattern based on the cross-sectional shape data in the groove 5 measured by the sensor 24 and performing welding. .

  3 and 4, the pass pattern applied in the welding device 1 of the present embodiment will be described. In the present embodiment, a single stroke welding locus from the start end to the end is referred to as a pass, and a pass in which a target position and a torch angle are set in advance is referred to as a pass pattern.

  In this embodiment, three path patterns of the lower end path, the intermediate path, and the upper end path are set. Incidentally, in FIG. 3, the single bead 29 laminated in the vertical direction is executed from the lower end pass to the upper end pass to form one layer of laminated beads 51a to 51c. 4A to 4C, the white circles indicate the upper and lower ends of each single bead 29 formed by welding, and the black circles indicate the target position by the welding torch 42.

  As shown in FIGS. 3 and 4A, the lower end pass is a pass pattern selected when the first pass of each layer of the laminated bead 51 formed in the groove 5 is welded. There is. In the lower end pass, the angle of the welding torch 42 with respect to the groove 5 is set to a first torch angle, for example, 30 °, and welding is performed with the lower end of the single bead 29a of the second pass of the previous layer as the target position. There is.

  The target position of the welding torch 42 in the lower end pass is preferably slightly above the lower end of the single bead 29a in the second pass of the previous layer, for example, about 1 mm above.

  As shown in FIGS. 3 and 4B, the intermediate pass is a pass pattern selected when welding the second and subsequent passes of each layer of the laminated bead 51 formed in the groove 5. ing. In the intermediate pass, the angle of the welding torch 42 with respect to the groove 5 is set to the second torch angle smaller than the first torch angle, for example, 20 °, and the upper end of the single bead 29b of the latest pass, that is, the same layer in the second pass. If the upper end of the single bead 29 of the first pass and the third pass, welding is performed with the upper end of the single bead 29 of the second pass of the same layer as the target position.

  In the middle path, the distance W in the height direction between the upper end of the single bead 29b of the latest path and the upper end of the single bead 29c of the previous layer uppermost path is a single value of the single latest path that is preset. It is selected when it is larger than the threshold value α which is the first threshold value regarding the remaining width between the upper end of the bead 29b and the groove 5. That is, the intermediate pass is selected within the range of α <W from the second pass.

  The target position of the welding torch 42 in the intermediate pass is preferably slightly above the upper end of the single bead 29b in the latest pass, for example, about 1 mm above.

  As shown in FIGS. 3 and 4C, the upper end pass has a pass pattern selected when welding the upper end portion in the groove 5 after the end of the intermediate pass. In the upper end pass, the angle of the welding torch 42 with respect to the groove 5 is set to a third torch angle smaller than the second torch angle, for example, 10 °, and welding is performed with the upper end of the single bead 29b of the latest pass as a target position. Has become.

  The first torch angle, the second torch angle, and the third torch angle described above are stored as a database by accumulating judgments when a skilled worker manually performs the multi-layer welding of the groove 5, and the database. It is a value set based on, and can be changed as appropriate.

  When the upper end pass is executed, a distance (remaining groove width) W between the upper end of the single bead 29b of the latest pass and the upper end of the single bead 29c of the preceding uppermost pass is set to a preset threshold value α. The following, that is, W ≦ α, or the distance (layer thickness) h in the horizontal direction between the upper end of the single bead 29b of the latest path and the upper end of the single bead 29c of the preceding uppermost layer path is set in advance. The control unit 49 determines whether or not it is smaller than a threshold value β which is a second threshold value regarding the layer thickness at the upper end of the set single bead 29b of the latest path, that is, h <β. .

  When W ≦ α and h <β, the upper end pass is selected again, and when β <h, the welding of the same layer is finished, and the lower end pass is selected again in the next layer, and welding is performed. Is executed.

  The target position of the welding torch 42 in the upper end pass is slightly above the upper end of the single bead 29b of the latest pass, for example, about 1.5 mm above, or from the upper end of the single bead 29b of the latest pass. Is also selected to be slightly below, for example, about 1.5 mm below. As the selection of the aiming position, for example, if the groove remaining width W is 0, the lower part than the upper end of the single bead 29b of the latest path is selected, and if the groove remaining width W is not 0, the single of the latest path is selected. The upper side of the upper end of the bead 29b is selected.

  The thresholds α and β set in each of the pass patterns described above are stored as a database by accumulating the judgments made by a skilled worker when performing the multi-layer welding of the groove 5 manually, and based on the database. The value is set to.

  Next, referring to FIG. 1, FIG. 2, and FIG. 5 (A) to FIG. 5 (D), the automatic multi-layer welding of the groove 5 using the welding device 1 will be described. 5 (A) to 5 (D), solid arrows indicate a state in which welding or measurement is being performed, and wavy arrows indicate a state in which welding or measurement is not being performed. Is shown.

  First, as shown in FIGS. 1 and 2, the upper end of the upper workpiece 4 is covered with the support member 7 and fixed by a predetermined means such as a screw.

  Next, the rotating motor 12 is driven to rotate the welding device body 9, and the yaw motor 43, the second pitch motor 44, and the second roll motor 45 are driven to adjust the position of the welding torch 42. By doing so, the tip position of the welding wire supplied from the wire supply unit (not shown) is guided to the welding start position in the groove 5.

  Also, a first pitch motor (not shown) and a first roll motor (not shown) are driven to adjust the position of the sensor 24 and guide it to a position facing the welding torch 42.

  When the induction is completed, an arc is generated between the electrode of the welding torch 42 and the base portion 4a and the main body portion 4b by the control unit 49, a welding wire is further supplied, and welding is started.

  For the welding of the first pass, since no bead is formed in the groove 5, the pre-measured cross-sectional shape data in the groove 5 before welding stored in the storage unit 52 is used. In addition, welding is performed from a preset aiming position.

  In this embodiment, as shown in FIG. 5A, first, the control unit 49 drives the traveling drive unit and the weaving drive unit to move the welding torch 42 downward along the groove 5 with respect to the paper surface. From the above to the upper part, it is moved clockwise by a half turn (180 °) and welding is performed. When the welding for the left half circumference is completed, the welding is stopped, the welding torch 42 is further moved clockwise for a half circumference, and the welding torch 42 is guided again to the welding start position.

  At this time, as shown in FIG. 5 (B), in parallel with the guidance of the welding torch 42 to the welding start position, a cross section in the groove 5 corresponding to the left half circumference where welding is performed by the sensor 24. Shape data is measured.

  The measurement in the groove 5 is performed at a predetermined angular pitch, for example, every 6 ° pitch, and the measured cross-sectional shape data is associated with a measurement position (measurement point) and stored in the storage unit 52. Is stored.

  When the guiding of the welding torch 42 to the welding start position is completed, the control unit 49 drives the traveling driving unit and the weaving driving unit to move the welding torch 42 to the welding starting position as shown in FIG. Welding is performed by moving along the groove 5 counterclockwise by half a turn (180 °) from the bottom to the top with respect to the paper surface. When the welding for the right half circumference is completed, the welding is stopped, the welding torch 42 is further moved counterclockwise for a half circumference, and the welding torch 42 is guided again to the welding start position.

  At this time, as shown in FIG. 5 (D), in parallel with the guidance of the welding torch 42 to the welding start position, a cross section in the groove 5 for the right half circumference where welding is performed by the sensor 24. Shape data is measured.

  The cross-sectional shape data in the groove 5 measured by the sensor 24 is discontinuous data for each predetermined angular pitch, and the control unit 49 performs a complementary process between the cross-sectional shape data. Thus, the cross-sectional shape data of the entire circumference in the groove 5 can be obtained.

  When the welding and measurement of the first pass of the groove 5 are completed over the entire circumference by the left and right half turns, the second pass is welded. Similarly to the first pass, in the second pass, the welding torch 42 welds the left half of the groove 5, and the sensor 24 measures the cross-sectional shape of the left half of the groove 5. After that, the welding torch 42 welds the right half circumference of the groove 5, and the sensor 24 measures the cross-sectional shape of the right half circumference in the groove 5.

  For welding after the second pass, based on the cross-sectional shape data in the groove 5 acquired by the sensor 24, the control unit 49 determines whether or not it is the lowermost pass, and the remaining groove width W And the threshold value α, the layer thickness h is compared with the threshold value β, and one of the upper pass, the intermediate pass, and the lower end pass is selected (see FIG. 3). The control unit 49 causes the welding apparatus 1 to perform welding for the second and subsequent passes based on the selected pass pattern.

  Regarding the welding of the first layer, since the uppermost bead does not exist, the distance in the height direction between the upper end of the bead 29b of the latest pass and the upper end of the bottom of the groove 5 is set as the groove remaining width W and the threshold α And the horizontal distance between the upper end of the bead 29b of the latest path and the upper end of the bottom of the groove 5 is set as the layer thickness h and compared with the threshold value β.

  Welding is similarly performed for the third and subsequent passes, and the single beads 29 are sequentially stacked in the groove 5. When the whole of the groove 5 is filled with the laminated bead 51, that is, when the control unit 49 cannot detect the layer thickness h, the control unit 49 is filled with the laminated bead 51 in the groove 5. Then, the cosmetic beads are applied to the upper end of the groove 5 for one pass, and the automatic multi-layer welding process of the groove 5 is finished.

  As described above, in the present embodiment, the welding torch 42 that generates an arc in the groove 5, the wire supply unit that supplies the welding wire to the welding torch 42, and the welding torch 42 along the welding line. Running drive unit for running the welding torch 42, the weaving drive unit for weaving the welding torch 42, the sensor 24 for measuring the cross-sectional shape in the groove 5, and a plurality of path patterns set corresponding to the cross-sectional shape. Is stored in the storage unit 52 and the control unit 49 that selects one of the pass patterns from the cross-sectional shape detected by the sensor 24 and executes welding based on the selected pass pattern. Therefore, even if the groove 5 is deformed due to welding deformation and the target position of the welding torch 42 or the required welding amount of the laminated bead 51 is changed, it is separately supplemented. It is possible to automate the welding without performing processing.

  Further, the upper end and the lower end of the single bead 29 are detected from the obtained sectional shape data, and the target position of the welding torch 42 is determined with the upper end or the lower end of the single bead 29 as a reference. Therefore, even if the groove 5 is deformed by welding and the position where the single bead 29 is formed deviates from the initially predicted position, it is not necessary to perform the correction process of the target position.

  In the upper end pass, the remaining groove width W and the layer thickness h are compared with preset thresholds α and β, and the number of executions of the upper end pass is automatically increased or decreased according to the comparison result. Therefore, even if the shape of the groove 5 is deformed by welding and the required welding amount of the laminated bead 51 is changed, the bead having the optimum welding amount is automatically obtained without performing a separate correction process. be able to.

  Therefore, in the present embodiment, it is not necessary to set welding conditions for each required welding amount of the laminated bead 51 that has changed due to the deformation of the groove 5, and three path patterns of a lower end pass, an intermediate pass, and an upper end pass are set. Since the welding can be automated simply by doing so, the welding conditions such as the target position and the number of passes for each required welding amount become unnecessary, and the welding condition database for automation can be easily constructed.

  Further, since the sensor 24 and the welding torch 42 can independently move up and down, advance and retreat, and rotate, the upper welded object 4 is vertically attached to the inclined lower welded object 3. In some cases, as shown in FIG. 2, multi-layer welding can be performed even if the shape of the groove 5 is an inclined ellipse or the like.

  Incidentally, in the present embodiment, three pass patterns of the lower end pass, the intermediate pass, and the upper end pass are set as the pass patterns when welding the groove 5, but the upper end pass is the upper end pass and the additional pass. It may be divided into two path patterns.

  In this case, the upper end pass is executed only once, and the control unit 49 compares the layer thickness h with the threshold value β after the upper end pass is executed. If h ≦ β, the control unit 49 causes the additional pass to be performed, and if β <h, the welding of the next layer is performed without performing the additional pass.

  Further, in this embodiment, circumferential welding is performed on the ring-shaped groove 5, but the welding device 1 is allowed to travel straight in the horizontal direction, and multi-layer welding is performed on a linear groove. You can do it as well. In this case, the welding pass and the shape measurement are performed alternately, after welding for one pass to the groove on the straight line, the cross-sectional shape of the groove is measured, and the next pass is determined based on the measurement result. To be executed.

DESCRIPTION OF SYMBOLS 1 Welding device 3 Lower to-be-welded object 4 Upper-to-be-welded object 5 Groove 7 Supporting member 9 Welding device main body part 12 Rotating motor 14 First elevating part 15 Second elevating part 16 First advance / retreat part 19 First elevating motor 24 Sensor 29a-29c Single bead 31 2nd advancing / retreating part 32 2nd raising / lowering motor 42 Welding torch 43 Yaw motor 44 2nd pitch motor 45 2nd roll motor 49 Control part 52 Storage part

Claims (5)

  Welding torch, wire supply unit, traveling drive unit for traveling the welding torch along the welding line, weaving drive unit for weaving the welding torch, sensor for measuring the cross-sectional shape in the groove, and the cross section A storage unit that stores a plurality of path patterns set corresponding to the shape; and a control unit that selects one of the plurality of path patterns from the cross-sectional shape detected by the sensor and executes welding. The control unit includes a first threshold value for a remaining width between the upper end of the single bead of the latest pass and the groove, and a second threshold value for a layer thickness of the upper end of the single bead of the latest pass. A welding device configured to select a pass pattern from.   The control unit detects the upper end and the lower end of a single bead based on the cross-sectional shape data in the groove measured by the sensor, and the target position of the welding torch with the upper end or the lower end of the single bead as a reference. The welding device according to claim 1, wherein the welding device is configured to determine. The storage unit stores three pass patterns of a lower end pass, an intermediate pass, and an upper end pass, and the control unit selects the lower end pass when the welding to be executed is the lowest pass, and If the remaining width is greater than the first threshold value and selects the intermediate path, to the claim 1 configured as to select the upper path if the remaining width is less than the first threshold value The welding device described. The storage unit further stores an additional pass as a pass pattern, and the control unit compares the layer thickness with the second threshold after the upper end pass is executed, and the layer thickness is the second threshold. The welding device according to claim 3 , wherein the welding path is configured to select the additional path when the value is equal to or less than the threshold value of. The welding device according to any one of claims 1 to 4 , wherein the welding torch and the sensor are configured to be independently movable up and down, forward and backward, and rotatable.

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