Welding system and welding speed adjustment method

Abstract

To provide a technique that is able to easily adjust a welding speed from information on a molten pool.SOLUTION: A 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 width information and length information of a molten pool 24 from shape information detected by the detection device 51; a storage unit that stores a correspondence relation between proper width information and proper length information of the molten pool 24 when the welding torch 21 is operated at a proper welding speed; a comparison unit that obtains the proper length information corresponding to the width information from the correspondence relation stored in the storage unit and compares the obtained proper length information with the length information; and an adjustment unit that adjusts the welding speed, based on the proper length information and the length information compared by the comparison unit.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to a welding system and a method for adjusting a welding speed. [Background technology]

[0002] Japanese Patent No. 7261682 (Patent Document 1) discloses creating a database based on the results of extracting appropriate combinations of welding operation feature quantities and welding phenomenon feature quantities by correlating them with time or coordinates. In Japanese Patent No. 7261682 (Patent Document 1), the created database is used to manage welding quality. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7261682 Summary of the Invention [Problem to be solved by the invention]

[0004] In welding, it is desirable to prevent welding defects in the bead and improve welding quality by adjusting the welding speed, which is the speed at which the welding torch is moved in the welding direction. However, in multi-layer welding, which involves stacking multiple welding passes, the welding torch simultaneously performs a weaving motion, which is a movement perpendicular to the welding direction, making it difficult to determine the appropriate welding speed for each pass. Furthermore, the technology disclosed in Japanese Patent No. 7261682 (Patent Document 1) requires a complex process for creating a database from a combination of welding motion feature values ​​and welding phenomenon feature values, and the process for determining the appropriate welding speed takes time.

[0005] An object of the present disclosure is to provide a technology that can easily adjust the welding speed based on information about the molten pool. [Means for solving the problem]

[0006] The welding system of the present disclosure includes a welding torch, a detection device for detecting shape information of a molten pool, and a control device. The control device includes a calculation unit that calculates width information and length information of the molten pool from the shape information detected by the detection device, a memory unit that stores a correspondence relationship between appropriate width information and appropriate length information of the molten pool when the welding torch is operated at an appropriate welding speed, a comparison unit that determines appropriate length information corresponding to the width information from the correspondence relationship stored in the memory unit and compares the determined 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. [Effects of the Invention]

[0007] In the welding system of the present disclosure, the welding speed is adjusted based on the length information and the appropriate length information compared by the comparison unit, which makes it possible to easily adjust the welding speed based on the molten pool information. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram schematically illustrating a welding system according to a first embodiment. [Figure 2] FIG. 10 is a diagram showing an example of the shape of a bead for each pass. [Figure 3] FIG. 10 is a diagram showing the cross-sectional shape of a bead after welding. [Figure 4] FIG. 10 is a diagram showing the correspondence relationship between the width and length of the molten pool. [Figure 5] FIG. 10 is a diagram showing the appropriate range of the shape of the molten pool. [Figure 6] 4 is a flowchart showing control content according to the first embodiment. [Figure 7] 10 is a flowchart showing the control content according to the second embodiment. [Figure 8] 10A and 10B are diagrams showing the cross-sectional shape of a bead after welding in a modified example. DETAILED DESCRIPTION OF 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 designated by the same reference numerals, and description thereof will not be repeated.

[0010] [Embodiment 1] 1 is a diagram schematically illustrating a welding system 1 according to embodiment 1. 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] Robot arm 40 is a multi-joint arm, for example a six-axis multi-joint arm. Robot arm 40 functions as a drive device that moves welding torch 21 at a set welding speed. As robot arm 40 moves welding torch 21, bead 12 is formed by melting welding wire 22. Welding wire 22 is supplied from a wire feeder (not shown).

[0012] Welding torch 21 supplies welding current from a welding power source (not shown) to welding wire 22. Welding wire 22 is melted by arc 23 generated between welding torch 21 and base metal 10. Bead 12 is formed by melting welding wire 22 and base metal 10. Shielding gas is supplied to welding torch 21 by a shielding gas supply unit (not shown). Shielding gas may be, for example, argon, CO2, or a mixture of these.

[0013] A molten pool 24 is formed immediately below and in the vicinity of the welding torch 21. When the arc 23 is extinguished and the temperature drops, the molten pool 24 solidifies and becomes a bead 12 with a thickness (depth) and width appropriate for welding. The bead 12 is formed along the welding direction indicated by the arrows in Figure 1 between two base materials 10 having inclined groove faces 10a.

[0014] Welding base materials 10 having groove faces 10a together is called groove welding. Groove welding is a type of welding in which multiple passes are overlapped and layered. A bead 12 is formed for each pass. A backing material 11 that contacts the lower side of the base materials 10 prevents burn-through of the bead 12 in the first pass.

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

[0016] The control device 30 includes an arithmetic unit 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 a computing entity (computer) that executes predetermined processing. The arithmetic device 31 is configured with 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 interpreted as a processing circuitry that executes predetermined processing.

[0018] The memory 32 includes a storage area (for example, a working area) for storing program code or work memory when the arithmetic unit 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 input of various data and outputs data obtained by various processes in accordance with instructions from the arithmetic unit 31.

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

[0022] 2A and 2B are diagrams showing examples of the shape of the bead 12 for each pass. Fig. 2A shows an example of the shape of the bead 12 for the first pass, Fig. 2B shows an example of the shape of the bead 12 for the second pass, and Fig. 2C shows an example of the shape of the bead 12 for the fourth pass. The welding torch 21 moves in the length direction between the base materials 10. The direction in which the welding torch 21 moves is referred to as the welding direction.

[0023] 2(A), welding torch 21 moves in the welding direction to weld groove surface 10a and backing material 11 together with bead 12. A molten pool 24 is formed around arc 23 where welding wire 22 melts. The molten pool 24 in the first pass has a length L1 and a width W1 in the welding direction, for example.

[0024] 2(B), welding torch 21 performs weaving to form a wide bead 12 by moving in a zigzag pattern in the welding direction. Weaving can change the width of bead 12. The molten pool 24 in the second pass has, for example, a length L2 and a width W2 in the welding direction.

[0025] In the fourth pass in Figure 2(C), the welding torch 21 performs a larger weaving than in the second pass. As the number of passes increases, the width from one groove face 10a to the other groove face 10a increases, and therefore the width of the bead 12 also increases. The molten pool 24 in the fourth pass has, for example, a length L4 in the welding direction and a width W4. As shown in Figures 2(A) to 2(C), the length and width of the molten pool 24 in the welding direction tend to increase as the number of passes increases.

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

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

[0028] As shown in Figure 3, adjusting the welding speed of the welding torch 21 is important to prevent welding defects from occurring in the bead 12, which has a different shape for each pass. Note that the welding speed is the movement speed of the welding torch 21 in the welding direction, even when weaving is performed. In other words, the weaving distance in a direction unrelated to the welding direction is not taken into consideration. If the welding speed is slower than the appropriate speed, the amount of deposited metal may be excessive, resulting in a welding defect such as bead overflow. Conversely, if the welding speed is faster than the appropriate speed, the amount of deposited metal may be insufficient, resulting in a welding defect such as chipping of the bead 12.

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

[0030] The circles, crosses, and triangles in the graph represent plots of information about the molten pool 24 when three experienced welders performed welding. 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 width and length of the molten pool 24 have a corresponding relationship in which the length of the molten pool 24 increases as the width of the molten pool 24 increases.

[0031] Figure 5 shows the appropriate range for the shape of the molten pool. In Figure 5, the circles in the graph of Figure 4 are extracted and set as appropriate values. A linear approximation of the circles in the graph results in a line P0, indicated by a dashed line. Lines P1 and P2, indicated by dashed lines, are set approximately 10% above and below line P0. The molten pool 24 is considered to have an appropriate shape in which no welding defects occur within the range from line P1 to line P2.

[0032] The control device 30 adjusts the welding speed so that the plotted points fall within the width between lines P1 and P2. Note that there are plotted points outside the range between lines P1 and P2, but the information on the molten pool 24 at these points does not necessarily indicate a welding defect. In this embodiment, by setting the width between lines P1 and P2, which is a strict standard range, the welding speed is adjusted to a value that allows the formation of a molten pool 24 that is reliably free of welding defects.

[0033] The data in Figure 5 is data relating to the correspondence between the appropriate width information and appropriate length information of the molten pool 24 when the welding torch 21 is operated at an appropriate welding speed. The data in Figure 5 is pre-stored in the storage device 33, which also functions as a storage unit. The appropriate width information and appropriate length information of the molten pool 24 can also be rephrased as a first threshold value for the appropriate width, a second threshold value for the appropriate length, information for determining the appropriate width, and information for determining the appropriate length. In this embodiment, the data marked with a circle in the graph in Figure 4 is used, but data marked with a triangle or cross may also be used. Only the data with the highest welding quality may be extracted from multiple data and used as the appropriate width information and appropriate length information of the molten pool 24, and the data can be changed as desired.

[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 and executed as a subroutine from the main routine in the control of control device 30. First, in step S (hereinafter simply referred to as "S") 1, control device 30 starts welding based on welding data previously stored in storage device 33.

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

[0036] Here, the detection device 51 can detect, as image information, a groove width W0, which is the maximum width between the groove surface 10a at the end of the upper surface in the thickness direction of one base material 10 and the groove surface 10a at the end of the upper surface in the 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 processing of S3, the calculation device 31 calculates a value obtained by dividing the groove width W0 by width information of the molten pool 24, and also executes a process of calculating a value obtained by dividing the groove width W0 by length information of the molten pool 24.

[0037] Next, the control device 30 compares the obtained value with the appropriate data shown in Fig. 5 and calculates the appropriate value of the molten pool length corresponding to the molten pool width (S4). Specifically, the process of S4 is executed by the calculation device 31 functioning as a comparison unit. The calculation device 31 obtains appropriate length information corresponding to the width information of the molten pool 24 calculated in S3 from the correspondence relationship 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 calculated in S4 (appropriate value of the length of the molten pool 24) (S5). If the control device 30 determines in S5 that the length of the molten pool 24 is within the appropriate value range (the range between lines P1 and P2 in FIG. 5) (YES in S5), it proceeds to processing in S9. If the control device 30 determines in S5 that the length of the molten pool 24 is not within the appropriate value range (NO in S5), it proceeds to processing in S6. In processing S5, the calculation device 31, which functions 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 compare 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. Through the processes of S5 and S6, the control device 30 compares the length of the molten pool 24 based on the groove width W0, which is a constant width. For example, even if the distance between the detection device 51 and the bead 12 changes or the groove width varies depending on the sample, the control device 30 can compare the appropriate value based on the groove width W0.

[0040] If the control device 30 determines in S6 that the length of the weld pool 24 is longer than the appropriate value (YES in S6), it adjusts the welding speed to decrease (S7). If the control device 30 determines in S6 that the length of the weld pool 24 is shorter than the appropriate value (NO in S6), it adjusts the welding speed to increase (S8). The processes of S7 and S8 are processes in which the calculation device 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 calculation device 31 also functions as an adjustment unit that adjusts the welding speed. The adjustment of the welding speed may be, for example, by increasing or decreasing the welding speed by a predetermined amount.

[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. Because the processes of S7 and S8 allow the control device 30 to adjust the welding speed based on the constant groove width W0 as a reference, 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 reference.

[0042] Next, the control device 30 outputs the welding speed information to the display device 60 for display (S9). By the process of S9, the control device 30 can notify the current welding speed status to the operator or the like. Next, the control device 30 determines whether or not welding has finished (S10). If the control device 30 determines in S10 that welding has finished (YES in S10), the control device 30 returns the process from the subroutine to the main routine. If the control device 30 determines that welding has not finished (NO in S10), the control device 30 repeats the processes of S2 to S9.

[0043] In the welding system 1 of the first embodiment, in the processes of S7 and S8, the processing unit 31 adjusts the welding speed based on the optimum length information obtained in S4 and the length information calculated in S3, which are compared in the process of S5. This makes it possible to easily adjust the welding speed based on the information on the molten pool 24.

[0044] [Embodiment 2] A second embodiment will now be described. The control device 30 of the second embodiment executes a process for adjusting an appropriate welding speed based on shape information of the molten pool 24 in each of a plurality of passes. The process executed by the control device 30 of the second embodiment will now be described. FIG. 7 is a flowchart showing the control content according to the second embodiment. The processes of S22 to S29 are similar to the processes of S2 to S9 of the first embodiment, and therefore will not be described in detail.

[0045] First, in step S21, the control device 30 starts the nth welding pass based on welding data previously stored in the storage device 33. Next, the control device 30 acquires image information of the molten pool 24 detected by the detection device 51 (S22). Next, the control device 30 calculates width information and 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 the weld pool width with the appropriate data and calculates an appropriate value for the weld pool length corresponding to the weld pool width (S24). The appropriate data may be, for example, information that sets the optimal weld pool width and weld pool length for each of multiple passes. Next, the control device 30 determines whether the length of the weld pool 24 calculated in S23 is within the appropriate length range calculated in S24 (appropriate value for the length of the weld pool 24) (S25). If the control device 30 determines in S25 that the length of the weld pool 24 is within the appropriate value range (the range from line P1 to line P2 in Figure 5) (YES in S25), it proceeds to processing in S29. If the control device 30 determines in S25 that the length of the weld pool 24 is not within the appropriate value range (NO in S25), it proceeds to processing in S26.

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

[0048] Next, control device 30 outputs the welding speed information to display device 60 for display (S29). Next, control device 30 determines whether the nth welding pass currently being performed has been completed (S30). The determination of whether the nth welding pass has been completed may be made based on whether the data for the nth welding pass stored in storage device 33 has been executed. For example, the data for the nth welding pass includes a program for welding welding torch 21 from one end of base material 10 to the other end, and then moving the position of welding torch 21 back to one end.

[0049] If the control device 30 determines in S30 that welding of the th pass has not been completed (NO in S30), it repeats the processes of S25 to S29. If the control device 30 determines in S30 that welding of the th pass has been completed (YES in S30), it updates n to n+1 (S31). This sets the number of welding passes for the pass next to the pass currently being welded.

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

[0051] The welding system 1 of the second embodiment can adjust the welding speed appropriately based on the shape information of the molten pool 24 in each of the multiple passes.

[0052] [Variations] FIG. 8 is a diagram showing the cross-sectional shape of the bead 12 after welding in a modified example. Compared to the cross-sectional shape of FIG. 3 where one pass of welding is performed per layer, FIG. 8 differs in the number of passes in the sixth layer. Specifically, the sixth layer in the modified example is formed by two passes of the bead 126a and the bead 126b. The number of passes in the sixth layer may be three or more. Thus, even when the bead 12 is formed by two or more passes per layer, the welding speed can be easily adjusted from the shape information of the molten pool 24 by performing the processing of the above-described embodiment.

[0053] The welding system 1 of the embodiment has been described as being for automatic welding using a robot arm 40. The welding system 1 may also be applied to a manual welding machine. In the case of a manual welding machine, the worker performs welding work while wearing a welding mask. When applied to a manual welding machine, instructions to increase or decrease the welding speed may be displayed on the screen of a welding mask with a display. When communicating the welding speed to the worker, in addition to displaying the information on the display, the information may be communicated to the worker by sound, light, or a combination of these.

[0054] The welding system 1 of the embodiment has been described as being groove welding, but the welding technique may be any welding technique as long as it forms a molten pool 24.

[0055] In the above embodiment, welding torch 21 may be moved by a Cartesian robot instead of by 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 shape information of the weld pool, and a control device 30. The control device 30 includes a calculation unit (arithmetic unit 31) that calculates width information and length information of the weld pool 24 from the shape information detected by the detection device 51, a memory unit (storage device 33) that stores a correspondence relationship between appropriate width information and appropriate length information of the weld pool 24 when the welding torch 21 is operated at an appropriate welding speed, a comparison unit (arithmetic unit 31) that determines appropriate length information corresponding to the width information from the correspondence relationship stored in the memory unit (storage device 33) and compares the determined appropriate length information with the length information, and an adjustment unit (arithmetic unit 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 based on the appropriate length information and the information on the molten pool 24 based on the length information.

[0058] (2) In the welding system 1 of (1), the adjustment unit (calculation 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 to 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 based on 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, the welding speed can be adjusted to an appropriate speed based on the correspondence between the width information and length information of the molten pool 24.

[0062] (4) In any of the welding systems 1 described in (1) to (3), in groove welding between a first member (base material 10) and a second member (base material 10), the detection device 51 is capable of detecting a 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). The calculation unit (computing 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 the values ​​obtained by dividing the appropriate width information and the appropriate length information by the groove width W0. The comparison unit (computing 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 (computing 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, which has a constant length.

[0064] (5) In the welding system 1 of (4), groove welding is performed by stacking multiple passes. The control device 30 adjusts the welding speed appropriately for each of the multiple passes.

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

[0066] (6) The welding speed adjustment method of the present disclosure is a welding speed adjustment method that uses a computer (control device 30) to adjust the welding speed of welding torch 21. The processing executed by computer (control device 30) includes the steps of: calculating width information and length information of weld pool 24 from shape information detected by detection device 51 that detects shape information of weld pool 24; storing a correspondence relationship between appropriate width information and appropriate length information of weld pool 24 when welding torch 21 is operated at an appropriate welding speed; obtaining 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 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 appropriate length information and information on the molten pool 24 based on the length information.

[0068] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the description of the above embodiments, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0069] 1 welding system, 10 base material, 10a groove surface, 11 backing material, 12 bead, 21 welding torch, 22 welding wire, 23 arc, 24 molten pool, 30 control device, 31 arithmetic unit, 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 shape information of the molten pool; a control device; The control device a calculation unit that calculates width information and length information of the molten pool from the shape information detected by the detection device; a storage unit that stores a correspondence relationship between appropriate width information and appropriate length information of the molten pool when the welding torch is operated at an appropriate welding speed; a comparison unit that obtains the appropriate length information corresponding to the width information from the correspondence relationship stored in the storage unit and compares the obtained appropriate length information with the length information; an adjusting unit that adjusts the welding speed based on the appropriate length information compared by the comparing unit and the length information.

2. The welding system according to claim 1 , wherein the adjustment unit adjusts the welding speed so as to decrease the welding speed when the length information is longer than the appropriate length information, and to increase the welding speed when the length information is shorter than the appropriate length information.

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

4. In groove welding between a first member and a second member, The detection device is capable of detecting a groove width that is a 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 values ​​obtained by dividing the appropriate width information and the appropriate length information by the groove width, The comparison unit compares the value obtained by dividing the appropriate length information by the groove width with the value obtained by dividing the length information by the groove width, The welding system according to claim 1 or 2, wherein 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.

5. The groove welding is a welding in which a plurality of passes are stacked, The welding system of claim 4 , wherein the control device adjusts the welding speed appropriately for each of the plurality of passes.

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

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