Welding system and welding speed adjustment method

Abstract

Provided is a technique capable of easily adjusting the welding speed from the information of the molten pool. 【Solution means】The welding system 1 includes a welding torch 21, a detection device 51, and a control device 30. The control device 30 includes a calculation unit that calculates the width information and the length information of the molten pool 24 from the shape information detected by the detection device 51, a storage unit that stores the correspondence between the appropriate width information and the appropriate length information of the molten pool 24 when the welding torch 21 operates at an appropriate welding speed, a comparison unit that obtains the appropriate length information corresponding to the width information from the correspondence stored in the storage unit and compares the obtained appropriate length information with the length information, and an adjustment unit that adjusts the welding speed based on the appropriate length information and the length information compared by the comparison unit.

Description

Technical Field

[0001] The present disclosure relates to a welding system and a welding speed adjustment method.

Background Art

[0002] Japanese Patent No. 7261682 (Patent Document 1) discloses creating a database based on an extraction result obtained by correlating an appropriate combination of welding operation feature amounts and welding phenomenon feature amounts with time or coordinates. In Japanese Patent No. 7261682 (Patent Document 1), welding quality is managed by using the created database.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In welding, it is desired to improve the welding quality by setting the welding speed, which is the speed when the welding torch is moved in the welding direction, to an appropriate speed so as not to cause welding defects in the bead. However, in multi-layer welding in which a plurality of welding passes are stacked, since a weaving operation, which is a movement orthogonal to the direction in which the welding torch is welded, is performed simultaneously, it is difficult to determine the appropriate welding speed for each pass. Further, the technique of Japanese Patent No. 7261682 (Patent Document 1) has a complicated process of creating a database from a combination of welding operation feature amounts and welding phenomenon feature amounts, and the process for determining an appropriate welding speed takes time.

[0005] An object of the present disclosure is to provide a technique capable of easily adjusting the welding speed from information on a molten pool.

Means for Solving the Problems

[0006] The welding system of the present disclosure includes a welding torch, a detection device for detecting the shape information of the molten pool, and a control device. The control device includes a calculation unit that calculates the width information and length information of the molten pool from the shape information detected by the detection device, a storage unit that stores the correspondence between the appropriate width information and the appropriate length information of the molten pool when the welding torch operates at an appropriate welding speed, a comparison unit that obtains the appropriate length information corresponding to the width information from the correspondence stored in the storage unit and compares the obtained appropriate length information with the length information, and an adjustment unit that adjusts the welding speed based on the appropriate length information and the length information compared by the comparison unit.

Effect of the Invention

[0007] In the welding system of the present disclosure, the welding speed is adjusted based on the appropriate length information and the length information compared by the comparison unit. As a result, the welding speed can be easily adjusted from the information of the molten pool.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and their description will not be repeated.

[0010] [Embodiment 1] FIG. 1 is a diagram schematically showing a welding system 1 according to Embodiment 1. The welding system 1 includes a robot arm 40, a welding torch 21, a detection device 51, a control device 30, and a display device 60.

[0011] The robot arm 40 is an articulated arm, for example, a 6-axis articulated arm. The robot arm 40 functions as a driving device that moves the welding torch 21 at a set welding speed. When the robot arm 40 moves the welding torch 21, a bead 12 is formed by melting the welding wire 22. The welding wire 22 is supplied from a wire feeding device (not shown).

[0012] The welding torch 21 supplies a welding current from a welding power source (not shown) to the welding wire 22. The welding wire 22 is melted by an arc 23 generated between the welding wire 22 and the base material 10. When the welding wire 22 and the base material 10 are melted, a bead 12 is formed. Shielding gas is supplied to the welding torch 21 by a shielding gas supply unit (not shown). As the shielding gas, for example, argon, CO2, etc. and a mixed gas containing these are used.

[0013] A molten pool 24 is formed in the vicinity directly below the welding torch 21. When the arc 23 disappears and the temperature decreases, the molten pool 24 solidifies into a bead 12 having an appropriate thickness (depth) and width for welding. The bead 12 is formed along the welding direction indicated by the arrow in FIG. 1 between two base materials 10 having an inclined groove face 10a.

[0014] Welding the base materials 10 with the groove face 10a applied is called groove welding. Groove welding is a welding in which a plurality of passes are overlapped and stacked. A bead 12 is formed for each pass. The backing material 11 that contacts the lower side of the base material 10 prevents the bead 12 from dropping off in the first pass.

[0015] The detection device 51 is, for example, a camera. The detection device 51 is fixed to the robot arm 40 together with the welding torch 21. The detection device 51 includes a light-shielding filter 52 for reducing the light generated by welding. The detection device 51 detects the shape information of the molten pool 24 through the light-shielding filter 52. The shape information of the molten pool 24 detected by the detection device 51 is transmitted to the control device 30. The shape information of the molten pool 24 is, for example, the image information of the molten pool 24.

[0016] The control device 30 includes an arithmetic device 31, a memory 32, a storage device 33, and an input / output interface 34. These components are connected via a bus.

[0017] The arithmetic device 31 is an arithmetic entity (computer) that executes predetermined processing. The arithmetic device 31 is composed of, for example, a processor such as a CPU (Central Processing Unit), an MPU (Micro-Processing Unit), a TPU (Tensor Processing Unit), or a GPU (Graphics Processing Unit). The arithmetic device 31 can also be read as a processing circuit (Processing Circuitry) that executes predetermined processing.

[0018] The memory 32 includes a storage area (for example, a working area) for storing program codes or working memories when the arithmetic device 31 executes various programs.

[0019] The storage device 33 functions as a storage unit that stores various programs or various data executed by the arithmetic device 31. For example, the storage device 33 stores a control program 330 executed by the arithmetic device 31.

[0020] The input / output interface 34 receives inputs of various data. The input / output interface 34 outputs the data required by various processes according to the instructions of the arithmetic device 31.

[0021] The display device 60 displays the data output from the input / output interface 34 according to the instruction of the arithmetic device 31. The display device 60 is, for example, a display, and displays information regarding the welding speed and the like.

[0022] FIG. 2 is a diagram showing an example of the shape of the bead 12 for each pass. FIG. 2(A) shows an example of the shape of the bead 12 in the first pass, FIG. 2(B) shows an example of the shape of the bead 12 in the second pass, and FIG. 2(C) shows an example of the shape of the bead 12 in the fourth pass. The welding torch 21 moves in the longitudinal direction between the base materials 10. The direction in which the welding torch 21 moves is referred to as the welding direction.

[0023] In the first pass of FIG. 2(A), the welding torch 21 welds the groove surface 10a and the backing material 11 with the bead 12 by moving in the welding direction. A molten pool 24 is formed around the arc 23 where the welding wire 22 melts. The molten pool 24 in the first pass is, for example, of a size having a length L1 and a width W1 in the welding direction.

[0024] In the second pass of FIG. 2(B), the welding torch 21 executes weaving to form a wide bead 12 by operating in a zigzag manner with respect to the welding direction. By the weaving, the width of the bead 12 can be changed. The molten pool 24 in the second pass is, for example, of a size having a length L2 and a width W2 in the welding direction.

[0025] In the fourth pass of FIG. 2(C), the welding torch 21 executes a weaving larger than that in the second pass. As the number of passes increases, the width from one groove surface 10a to the other groove surface 10a becomes larger, so the width of the bead 12 also becomes larger. The molten pool 24 in the fourth pass is, for example, of a size having a length L4 and a width W4 in the welding direction. As shown in FIGS. 2(A) to 2(C), the molten pool 24 tends to increase in length and width in the welding direction as the number of passes increases.

[0026] Here, the shortest distance connecting the groove face 10a at the upper surface end in the plate thickness direction of one base material 10 and the groove face 10a at the upper surface end in the plate thickness direction of the other base material 10 is defined as the groove width W0. The groove width W0 is the maximum width between the groove face 10a of one base material 10 and the groove face 10a of the other base material 10.

[0027] Figure 3 is a diagram showing the cross-sectional shape of the bead 12 after welding. As shown in Figure 3, the bead 12 becomes wider as the number of passes increases, such as the first-pass bead 121, the second-pass bead 122, the third-pass bead 123, the fourth-pass bead 124, and the fifth-pass bead 125.

[0028] As shown in Figure 3, in order to prevent welding defects from occurring in the beads 12 with different shapes for each pass, it is important to adjust the welding speed of the welding torch 21. Note that the welding speed is the moving speed of the welding torch 21 in the welding direction even when weaving is performed. That is, the distance of weaving in a direction not related to the welding direction is not considered. If the welding speed is too slow compared to the appropriate speed, there is a possibility of welding defects such as an excessive amount of deposited metal and the bead overflowing. Conversely, if the welding speed is too fast compared to the appropriate speed, there is a possibility of welding defects such as an insufficient amount of deposited metal and the bead 12 chipping.

[0029] When considering an appropriate welding speed for welding, focusing on the shape of the molten pool 24, the results shown in Figure 4 were obtained. Figure 4 is a diagram showing the correspondence between the molten pool width and the molten pool length. The horizontal axis of the graph is the value obtained by dividing the width of the molten pool 24 by the groove width W0. The vertical axis of the graph is the value obtained by dividing the length of the molten pool 24 by the groove width W0.

[0030] The ○, ×, and △ in the graph are points plotted with the information of the molten pool 24 when three veteran welders performed welding, respectively. The dashed ellipse indicates the range of the molten pool 24 from the first pass to the fifth pass. As shown in Figure 4, the correspondence between the width and length of the molten pool 24 is such that the length of the molten pool 24 increases as the width of the molten pool 24 increases.

[0031] FIG. 5 is a diagram showing an appropriate range of the shape of the molten pool. In FIG. 5, the circles in the graph of FIG. 4 are extracted and set as appropriate values. When linearly approximating the points of the circles in the graph, a straight line P0 indicated by a one-dot chain line is obtained. Straight lines P1 and P2 indicated by broken lines are set at positions 10% translated upward and downward from the straight line P0. It is assumed that the molten pool 24 has an appropriate shape in which welding defects do not occur within the range from the straight line P1 to the straight line P2.

[0032] The control device 30 adjusts the welding speed so that the plotted points fall within the width from the straight line P1 to the straight line P2. Although there are also points plotted outside the range of the width from the straight line P1 to the straight line P2, the information on the molten pool 24 at these points does not necessarily result in welding defects. In the present embodiment, by setting the width from the straight line P1 to the straight line P2, which is a strict reference range, the welding speed is adjusted to form a molten pool 24 in which welding defects surely do not occur.

[0033] The data in FIG. 5 is data regarding the correspondence relationship between the appropriate width information and the appropriate length information of the molten pool 24 when the welding torch 21 operates at an appropriate welding speed. The data in FIG. 5 is stored in advance in a storage device 33 that also functions as a storage unit. The appropriate width information and appropriate length information of the molten pool 24 can be rephrased as a first threshold value regarding the appropriate width, a second threshold value regarding the appropriate length, information for determining the appropriate width, information for determining the appropriate length, and the like. In the present embodiment, the data of the circles in the graph of FIG. 4 is used, but the data of triangles or crosses may also be used. It is also possible to extract only the data with the highest welding quality from a plurality of data as the appropriate width information and appropriate length information of the molten pool 24, and the data can be arbitrarily changed.

[0034] FIG. 6 is a flowchart showing the control content according to Embodiment 1. The processing of the flowchart in FIG. 6 is repeatedly called as a subroutine and executed from the main routine in the control of the control device 30. The control device 30 first starts welding based on the welding data stored in the storage device 33 in step S (hereinafter simply referred to as "S") 1.

[0035] Next, the control device 30 acquires the image information of the molten pool 24 detected by the detection device 51 (S2). Next, the control device 30 calculates the width information of the molten pool 24 and the length information of the molten pool 24 from the image information (shape information) of the molten pool 24 detected by the detection device 51 (S3). Specifically, the process of S3 is a process executed by the arithmetic unit 31 as a calculation unit that calculates the width information and the length information of the molten pool 24 from the image information by image analysis. Note that, separately from the arithmetic unit 31, the width and length of the molten pool 24 may be calculated by an image processing device dedicated to image processing.

[0036] Here, the detection device 51 can detect, as image information, the groove width W0 which is the maximum width between the groove surface 10a of the upper surface end portion in the plate thickness direction of one base material 10 and the groove surface 10a of the upper surface end portion in the plate thickness direction of the other base material 10. The groove width W0 is a constant width regardless of the shape of the molten pool 24. In the process of S3, the arithmetic unit 31 also executes a process of calculating a value obtained by dividing the groove width W0 by the width information of the molten pool 24 and a value obtained by dividing the groove width W0 by the length information of the molten pool 24.

[0037] Next, the control device 30 compares with the appropriate data as shown in FIG. 5 and calculates an appropriate value of the molten pool length corresponding to the molten pool width (S4). Specifically, the process of S4 is a process executed by the arithmetic unit 31 functioning as a comparison unit. The arithmetic unit 31 obtains the appropriate length information corresponding to the width information of the molten pool 24 calculated in S3 from the correspondence relationship as shown in FIG. 5 stored in the storage device 33.

[0038] Next, the control device 30 determines whether the length of the molten pool 24 calculated in S3 is within the range of the appropriate length (the appropriate value of the length of the molten pool 24) calculated in S4 (S5). When the control device 30 determines in S5 that the length of the molten pool 24 is within the range of the appropriate value (the range between the straight line P1 and the straight line P2 in FIG. 5) (YES in S5), it proceeds to the process of S9. When the control device 30 determines in S5 that the length of the molten pool 24 is not within the range of the appropriate value (NO in S5), it proceeds to the process of S6. The process of S5 is a process in which the arithmetic unit 31 functioning as a comparison unit compares the appropriate length information obtained in S4 with the length information calculated in S3.

[0039] Next, the control device 30 determines whether the length of the molten pool 24 is longer than the appropriate value (S6). The processes of S5 and S6 are processes of comparing the value obtained by dividing the appropriate length information calculated in S4 by the groove width W0 with the value obtained by dividing the length information of the molten pool 24 calculated in S3 by the groove width W0. The control device 30 compares the length of the molten pool 24 based on the groove width W0, which is a constant width, in the processes of S5 and S6. For example, even if the distance between the detection device 51 and the bead 12 changes or the groove width changes due to a sample, the control device 30 can compare with an appropriate value based on the groove width W0.

[0040] When the control device 30 determines in S6 that the length of the molten pool 24 is longer than the appropriate value (YES in S6), it adjusts to decrease the welding speed (S7). When the control device 30 determines in S6 that the length of the molten pool 24 is shorter than the appropriate value (NO in S6), it adjusts to increase the welding speed (S8). The processes of S7 and S8 are processes in which the arithmetic unit 31 adjusts the welding speed based on the appropriate length information obtained in S4 and the length information calculated in S3, which are compared in the process of S5. In this way, the arithmetic unit 31 also functions as an adjustment unit for adjusting the welding speed. The adjustment of the welding speed may be, for example, increasing or decreasing the welding speed by a predetermined width.

[0041] The processes of S7 and S8 are processes for adjusting the welding speed based on the value obtained by dividing the appropriate length information calculated in S4 by the groove width W0 and the value obtained by dividing the length information of the molten pool 24 calculated in S3 by the groove width W0. The control device 30 adjusts the welding speed based on the groove width W0, which is a constant width, by the processes of S7 and S8. Therefore, even if the position of the detection device 51 changes during welding and the size of the image changes, the welding speed can be adjusted to an appropriate value based on the standard.

[0042] Next, the control device 30 outputs to display the information on the welding speed on the display device 60 (S9). By the process of S9, the control device 30 can convey the current state of the welding speed to the operator or the like. Next, the control device 30 determines whether or not welding has been completed (S10). If the control device 30 determines in S10 that welding has been completed (YES in S10), the process returns from the subroutine to the main routine. If the control device 30 determines that welding has not been completed (NO in S10), the processes of S2 to S9 are repeated.

[0043] In the welding system 1 of Embodiment 1, in the processes of S7 and S8, the arithmetic unit 31 adjusts the welding speed based on the appropriate length information obtained in S4 compared by the process of S5 and the length information calculated in S3. As a result, the welding speed can be easily adjusted from the information of the molten pool 24.

[0044] [Embodiment 2] Embodiment 2 will be described. The control device 30 of Embodiment 2 executes a process of adjusting an appropriate welding speed from the shape information of the molten pool 24 in each of a plurality of passes. The process executed by the control device 30 of Embodiment 2 will be described. FIG. 7 is a flowchart showing the control content according to Embodiment 2. Since the processes of S22 to S29 are processes similar to the processes of S2 to S9 of Embodiment 1, detailed description thereof will be omitted.

[0045] First, in step S21, the control device 30 starts the welding of the n-th pass based on the welding data stored in the storage device 33 in advance. Next, the control device 30 acquires the image information of the molten pool 24 detected by the detection device 51 (S22). Next, the control device 30 calculates the width information of the molten pool 24 and the length information of the molten pool 24 from the image information (shape information) of the molten pool 24 detected by the detection device 51 (S23).

[0046] Next, the control device 30 compares with the appropriate data and calculates the appropriate value of the molten pool length corresponding to the molten pool width (S24). The appropriate data may be, for example, information in which the optimal molten pool width and molten pool length are set for each of a plurality of passes. Next, the control device 30 determines whether the length of the molten pool 24 calculated in S23 is within the range of the appropriate length (the appropriate value of the length of the molten pool 24) calculated in S24 (S25). If the control device 30 determines in S25 that the length of the molten pool 24 is within the range of the appropriate value (the range from the straight line P1 to the straight line P2 in FIG. 5) (YES in S25), it proceeds to the process of S29. If the control device 30 determines in S25 that the length of the molten pool 24 is not within the range of the appropriate value (NO in S25), it proceeds to the process of S26.

[0047] Next, the control device 30 determines whether the length of the molten pool 24 is longer than the appropriate value (S26). If the control device 30 determines in S26 that the length of the molten pool 24 is longer than the appropriate value (YES in S26), it adjusts to lower the welding speed (S27). If the control device 30 determines in S26 that the length of the molten pool 24 is shorter than the appropriate value (NO in S26), it adjusts to increase the welding speed (S28).

[0048] Next, the control device 30 outputs so as to display the information on the welding speed on the display device 60 (S29). Next, the control device 30 determines whether or not the welding of the n-th pass that is currently being welded has ended (S30). The determination as to whether or not the n-th pass has ended may be made based on whether or not the data of the welding of the n-th pass stored in the storage device 33 has been executed. For example, the data of the welding of the n-th pass includes a program for moving the position of the welding torch 21 to one end again after welding the welding torch 21 from one end to the other end of the base material 10.

[0049] If the control device 30 determines in S30 that the welding of the pass has not ended (NO in S30), the control device 30 repeats the processes of S25 to S29. If the control device 30 determines in S30 that the welding of the pass has ended (YES in S30), the control device 30 updates n to n + 1 (S31). As a result, the number of passes of the welding of the next pass of the currently welded pass is set.

[0050] Next, the control device 30 determines whether or not the welding has ended (S32). If the control device 30 determines in S32 that the welding has ended (YES in S32), the control device 30 returns the process from the subroutine to the main routine. If the control device 30 determines that the welding has not ended (NO in S32), the control device 30 repeats the processes of S21 to S31.

[0051] The welding system 1 according to the second embodiment can adjust an appropriate welding speed from the shape information of the molten pool 24 in each of a plurality of passes.

[0052] [Modification Example] FIG. 8 is a diagram showing the cross-sectional shape of the bead 12 after welding in the modified example. FIG. 8 is compared with the cross-sectional shape in which one-pass welding is performed in one layer of FIG. 3, and the number of passes in the sixth layer is different. Specifically, in the sixth layer of the modified example, one layer is formed by two passes of the beads 126a and 126b. The number of passes in the sixth layer may be three or more. Thus, even when two or more passes of the bead 12 are formed in one layer, the welding speed can be easily adjusted from the shape information of the molten pool 24 by executing the process of the above-described embodiment.

[0053] The welding system 1 of the embodiment has been described for the case of automatic welding using the robot arm 40. The welding system 1 may be applied to a manual welding machine. In the case of a manual welding machine, an operator performs a fillet welding operation covering the welding surface. When applying it to a manual welding machine, an instruction to increase or decrease the welding speed may be displayed on the screen of the welding surface with a display. When transmitting the welding speed to the operator, in addition to the display on the display, it may be transmitted to the operator by sound, light, etc., or a combination thereof.

[0054] The welding system 1 of the embodiment has been described for the case of groove welding. However, the welding technique may be any welding technique as long as it is a welding technique in which the molten pool 24 is formed.

[0055] In the above embodiment, the welding torch 21 may be moved by a Cartesian robot instead of the articulated robot arm 40.

[0056] [Summary] (1) The welding system 1 of the present disclosure includes a welding torch 21, a detection device 51 that detects the shape information of the molten pool, and a control device 30. The control device 30 includes a calculation unit (operation device 31) that calculates the width information and length information of the molten pool 24 from the shape information detected by the detection device 51, a storage unit (storage device 33) that stores the correspondence relationship between the appropriate width information and the appropriate length information of the molten pool 24 when the welding torch 21 operates at an appropriate welding speed, a comparison unit (operation device 31) that obtains the appropriate length information corresponding to the width information from the correspondence relationship stored in the storage unit (storage device 33) and compares the obtained appropriate length information with the length information, and an adjustment unit (operation device 31) that adjusts the welding speed based on the appropriate length information and the length information compared by the comparison unit.

[0057] According to the welding system 1 of the present disclosure, the welding speed can be easily adjusted from the information of the molten pool 24 based on the appropriate length information and the length information.

[0058] (2) In the welding system 1 of (1), the adjustment unit (operation device 31) adjusts the welding speed so as to decrease the welding speed when the length information is longer than the appropriate length information and increase the welding speed when the length information is shorter than the appropriate length information.

[0059] According to the welding system 1 of the present disclosure, the welding speed can be easily adjusted from the length information of the molten pool 24.

[0060] (3) In the welding system 1 of (1) or (2), the correspondence relationship is such that the length information increases as the width information increases.

[0061] According to the welding system 1 of the present disclosure, it is possible to adjust to an appropriate welding speed from the correspondence relationship between the width information and the length information of the molten pool 24.

[0062] (4) In the groove welding of the first member (base material 10) and the second member (base material 10), any one of the welding systems 1 in (1) to (3) can detect the groove width W0, which is the maximum width between the groove surface 10a of the first member (base material 10) and the groove surface 10a of the second member (base material 10), by the detection device 51. The calculation unit (arithmetic device 31) calculates a value obtained by dividing the width information and the length information by the groove width W0. The storage unit (storage device 33) stores a value obtained by dividing the appropriate width information and the appropriate length information by the groove width W0. The comparison unit (arithmetic device 31) compares the value obtained by dividing the appropriate length information by the groove width W0 with the value obtained by dividing the length information by the groove width W0. The adjustment unit (arithmetic device 31) adjusts the welding speed based on the value obtained by dividing the appropriate length information by the groove width W0 and the value obtained by dividing the length information by the groove width W0.

[0063] According to the welding system 1 of the present disclosure, the length of the molten pool 24 can be compared based on the groove width W0 having a constant length.

[0064] (5) In the welding system 1 in (4), the groove welding is welding in which a plurality of passes are stacked. The control device 30 adjusts an appropriate welding speed for each of the plurality of passes.

[0065] According to the welding system 1 of the present disclosure, it is possible to adjust with an appropriate welding speed for each of the plurality of passes.

[0066] (6) The welding speed adjustment method of the present disclosure is a welding speed adjustment method for adjusting the welding speed of the welding torch 21 using a computer (control device 30). As processes executed by the computer (control device 30), a step of calculating the width information and the length information of the molten pool 24 from the shape information detected by the detection device 51 that detects the shape information of the molten pool 24, a step of storing the correspondence relationship between the appropriate width information and the appropriate length information of the molten pool 24 when the welding torch 21 operates at an appropriate welding speed, a step of obtaining the appropriate length information corresponding to the width information from the stored correspondence relationship and comparing the obtained appropriate length information with the length information, and a step of adjusting the welding speed based on the compared appropriate length information and length information.

[0067] According to the welding speed adjustment method of the present disclosure, the welding speed can be easily adjusted from the information of the molten pool 24 based on the appropriate length information and the length information.

[0068] The embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The scope of the present disclosure is shown by the claims rather than the description of the above-described embodiments, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Explanation of Signs

[0069] 1 Welding system, 10 Base material, 10a Groove surface, 11 Backup material, 12 Bead, 21 Welding torch, 22 Welding wire, 23 Arc, 24 Molten pool, 30 Control device, 31 Arithmetic device, 32 Memory, 33 Storage device, 34 Input / output interface, 40 Robot arm, 51 Detection device, 52 Light-shielding filter, 60 Display device, 330 Control program, W0 Groove width.

Claims

1. A welding torch, a detection device for detecting the shape information of the molten pool, and a control device, wherein the control device includes a calculation unit that calculates the width information and the length information of the molten pool from the shape information detected by the detection device, a storage unit that stores the correspondence between the appropriate width information and the appropriate length information of the molten pool when the welding torch operates at an appropriate welding speed, a comparison unit that obtains the appropriate length information corresponding to the width information from the correspondence stored in the storage unit and compares the obtained appropriate length information with the length information, and an adjustment unit that adjusts the welding speed based on the appropriate length information and the length information compared by the comparison unit. A welding system.

2. The welding system according to claim 1, wherein the adjustment unit adjusts the welding speed such that the welding speed is decreased when the length information is longer than the appropriate length information, and the welding speed is increased when the length information is shorter than the appropriate length information.

3. The welding system according to claim 1 or claim 2, wherein the correspondence is a relationship in which the length information increases as the width information increases.

4. In the groove welding of the first member and the second member, the detection device can detect the groove width, which is the maximum width between the groove surface of the first member and the groove surface of the second member, the calculation unit calculates a value obtained by dividing the width information and the length information by the groove width, the storage unit stores a value obtained by dividing the appropriate width information and the appropriate length information by the groove width, the comparison unit compares a value obtained by dividing the appropriate length information by the groove width with a value obtained by dividing the length information by the groove width, and the adjustment unit adjusts the welding speed based on a value obtained by dividing the appropriate length information by the groove width and a value obtained by dividing the length information by the groove width. The welding system according to claim 1 or claim 2.

5. The groove welding is welding in which a plurality of passes are stacked, and the control device adjusts the appropriate welding speed in each of the plurality of passes. The welding system according to claim 4.

6. A welding speed adjustment method for adjusting the welding speed of a welding torch using a computer, wherein, as a process executed by the computer, a step of calculating the width information and the length information of the molten pool from the shape information detected by a detection device that detects the shape information of the molten pool A step of storing the correspondence relationship between the appropriate width information and the appropriate length information of the molten pool when the welding torch is operated at an appropriate welding speed; A step of obtaining the appropriate length information corresponding to the width information from the stored correspondence relationship and comparing the obtained appropriate length information with the length information; A welding speed adjustment method comprising a step of adjusting the welding speed based on the compared appropriate length information and the length information.

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