Offset detection device for welding wire and offset detection method for welding wire

Abstract

To detect the offset amount corresponding to the positional deviation of the welding wire, the welding wire offset detection device includes a detection plate 30, a running control unit, and a detection unit. The detection plate 30 has a first detection groove 31 extending in the X direction (first direction), and the first detection groove 31 has a shape where the groove width 31a narrows in the X direction. The running control unit controls the operation of the welding robot based on teaching data, causing the welding wire to move along a path in the X direction inside the first detection groove. When the welding wire contacts the inner surface 31d of the first detection groove, the detection unit detects the offset amount of the welding wire in the Y direction (second direction), which is orthogonal to the X direction, based on the position of the welding wire in the X direction and the groove width of the first detection groove at that position.

Description

Technical Field

[0001] This invention relates to a device and method for detecting the offset of welding wire. Background Technology

[0002] In welding robots performing arc welding, the welding wire extends from the tip of the welding torch. When the welding wire deviates from its position, it cannot weld along the target line, resulting in what is known as wire deflection. This wire deflection during welding can, for example, lead to welding defects such as poor penetration of the deposited metal into the base metal.

[0003] Techniques for confirming the positional deviation of welding wires are known (see Patent Document 1). In the arc welding method disclosed in Patent Document 1, the welding torch is moved to a welding posture, and the welding wire is moved along a path provided in a confirmation fixture. Then, the positional deviation of the welding wire tip is confirmed based on whether the welding wire can pass through this path. If the welding wire does not come into contact with the wall of the path, it is determined that no positional deviation has occurred. If the welding wire comes into contact with the wall of the path, it is determined that a positional deviation has occurred.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2018-126753 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] In Patent Document 1, the width of the path in the direction orthogonal to the direction of wire movement is constant. The technology in Patent Document 1 determines whether a positional shift has occurred based solely on whether the wire abuts against the wall of the path; its purpose is not to detect the amount of the shift itself. Specific examples are given below. For instance, consider a path width of 3mm and a wire diameter of 1.2mm. Even if the wire shifts less than 0.9mm from the center of the groove towards the width, it is considered that no positional shift has occurred because the wire is not abutting against the path wall. When the shift is less than 0.9mm, the shift itself is not detected. Only when the wire shifts 0.9mm from the center of the groove towards the width does it abut against the path wall, thus indicating a positional shift. In this case, the shift amount is determined by the path width and the wire diameter, and is only a single value of 0.9mm.

[0009] As mentioned above, the purpose is not to detect the amount of wire displacement itself, and it is impossible to manage the trend of wire displacement increasing over time. As a result, consumables around the welding torch (e.g., contact tips) have to be replaced based on timing calculated from the welding length and the number of welding operations, and on experience, making it impossible to rationalize the replacement cycle.

[0010] Therefore, the purpose of this invention is to provide a welding wire offset detection device and a welding wire offset detection method. According to the detection device and detection method of this invention, the offset itself corresponding to the position offset of the welding wire can be detected.

[0011] Problem Solving Methods

[0012] One aspect of the present invention is a device for detecting the offset of a welding wire extending from the tip of a welding torch of a welding robot. The welding wire offset detection device includes a detection plate, an operation control unit, and a detection unit. The detection plate has a first detection groove extending in a first direction, the first detection groove having a shape in which the groove width narrows in the first direction. The operation control unit controls the operation of the welding robot based on teaching data, causing the welding wire to move along a track inside the first detection groove in the first direction. When the welding wire contacts the inner surface of the first detection groove, the detection unit detects the offset of the welding wire in a second direction orthogonal to the first direction based on the position of the welding wire in the first direction and the groove width of the first detection groove at the position of the welding wire.

[0013] Another aspect of the invention is a method for detecting the offset of a welding wire extending from the tip of a welding torch of a welding robot. The welding wire offset detection method controls the operation of the welding robot based on teach data, causing the welding wire to track along a first direction inside a first detection groove, the first detection groove extending in a first direction formed on a detection plate, and the groove width narrowing in the first direction. Subsequently, when the welding wire contacts the inner surface of the first detection groove, the offset of the welding wire in a second direction orthogonal to the first direction is detected based on the position of the welding wire toward the first direction and the groove width of the first detection groove at the position of the welding wire.

[0014] The effects of the invention

[0015] According to the present invention, a welding wire offset detection device and a welding wire offset detection method are provided, which can detect the offset amount itself corresponding to the positional offset of the welding wire. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a welding device that incorporates a wire offset detection device.

[0017] Figure 2 This is a front view of the detection plate of the welding wire offset detection device.

[0018] Figure 3 This is a block diagram representing the control system of the welding wire offset detection device.

[0019] Figure 4A A schematic diagram illustrating wear on the contact tip that causes welding wire misalignment.

[0020] Figure 4B A schematic diagram illustrating the deformation and relaxation of the welding torch that causes the welding wire to deviate.

[0021] Figure 4C This is a schematic diagram illustrating the positional displacement of the welding fixture that causes the welding wire to deviate.

[0022] Figure 5A This is a schematic diagram illustrating the process of the welding wire moving along a track inside the first detection groove.

[0023] Figure 5B This is a cross-sectional view showing the situation where the welding wire moves along a track inside the first detection groove.

[0024] Figure 5C This is a schematic diagram illustrating the offset in the X direction, the offset in the Y direction, and the combined offset in the X and Y directions.

[0025] Figure 6 This is a schematic diagram used to illustrate the structure of the first and second data.

[0026] Figure 7 This is a schematic diagram illustrating the use of first and second data to detect the offset.

[0027] Figure 8 This is a schematic diagram illustrating the method of determining the quality of welding wire offset based on composite offset.

[0028] Figure 9A This is the main view showing the operation display section.

[0029] Figure 9B This is a diagram showing an example of a timing chart displayed on a monitor.

[0030] Figure 9C This is a graph representing an example of data displayed in a time series chart.

[0031] Figure 9D A diagram illustrating a good or bad example of wire offset determination.

[0032] Figure 9E A diagram to illustrate other examples of the decisions shown.

[0033] Figure 9F A diagram to illustrate other examples of the decisions shown.

[0034] Figure 10A This is a flowchart illustrating the sequence of welding operations using a wire offset detection method.

[0035] Figure 10B To indicate continuation Figure 10A A flowchart outlining the sequence of welding operations.

[0036] Figure 11A This is a front view showing a modified example of the detection groove (a straight line with steps).

[0037] Figure 11B This is a front view showing a modified example of the detection groove (a cone shape with protrusions).

[0038] Figure 11C This is a front view showing a modified example of the detection groove (a cone shape with protrusions).

[0039] Figure 11D This is a front view showing a modified example of the detection groove (a cone shape with protrusions).

[0040] Figure 11E This is a front view showing a modified example of the detection groove (single-sided cone).

[0041] Figure 11F This is a front view showing a modified example of the detection groove (a combination of single-sided conical shapes).

[0042] Explanation of symbols

[0043] 10 Welding apparatus, 11 Welding robot, 12 Robot controller, 14 Welding fixture, 17 Welding torch, 18 Contact nozzle, 20 Welding wire offset detection device, 21 Welding wire, 30 Detection plate, 31 First detection groove, 31a Groove width, 31b Starting end, 31c Ending end, 31d Inner side, 32 Second detection groove, 32a Groove width, 32b Starting end, 32c Ending end, 32d Inner side, 33 Connecting groove, 40 Controller, 41 Operation control unit, 42 Detection unit, 43 Storage unit, 43a First storage unit, 43b Second storage unit, 44 Operation display unit, 50 Threshold, 61, 62, 63, 64 Detection grooves Detailed Implementation

[0044] The embodiments for carrying out the present invention will now be described in detail with reference to the accompanying drawings. The embodiments shown herein are provided to embody the technical concept of the present invention and are not intended to limit the invention. Therefore, other implementable methods, embodiments, and techniques that can be conceived by those skilled in the art without departing from the spirit of the present invention are included within the scope and spirit of the present invention, and are included within the scope of the invention as described in the claims and its equivalents.

[0045] Furthermore, for ease of illustration and understanding, the accompanying drawings may appropriately alter the scale, aspect ratio, shape, etc., from the actual object and be shown in an illustrative manner. However, such treatment is merely an example and is not intended to limit the interpretation of this invention.

[0046] In addition, ordinal numbers such as "first" and "second" may sometimes be used in this specification. However, unless otherwise specified, these ordinal numbers are additional markers for the purpose of facilitating the description and identification of the constituent elements, and are not used to determine quantity or order.

[0047] <Implementation Method>

[0048] Figure 1 A welding apparatus 10 employing a wire offset detection device is shown. Generally, the welding apparatus 10 includes a welding robot 11, a robot controller 12 for controlling the welding robot 11, a welding fixture 14 for setting the workpiece 13 to be welded, and a wire offset detection device 20 (hereinafter, also simply "detection device 20") for the welding wire 21 (hereinafter also simply "wire 21"). The welding robot 11 and the welding fixture 14 are mounted on a base 15. The welding robot 11 has multiple robot arms 16 and a welding torch 17 mounted on the robot arms 16. The welding wire 21 is automatically supplied by a supply device (not shown). The welding wire 21 extends from a conductive tip 18 provided at the front end of the welding torch 17. The robot controller 12 controls the posture of the welding robot 11, the supply of the welding wire 21, and the supply of welding current, etc.

[0049] First, let's explain the key factors that cause the welding wire 21 to deviate. Figure 4A , Figure 4B and Figure 4C The key factors contributing to the offset of welding wire 21 are shown below. Figure 4A As shown, before the contact tip 18 wears (upper side state), the welding wire 21 is located at the center of the contact tip hole 18a, or scrapes against the front end of the contact tip hole 18a due to the bending tendency of the welding wire 21. With repeated welding operations, the welding wire 21 scrapes against the contact tip hole 18a, and the contact tip hole 18a gradually wears down. When the wear of the contact tip 18 intensifies (lower side state), the diameter of the contact tip hole 18a increases. The amount of increase in diameter is indicated by arrow 18b. This causes the welding wire 21 to shift. Figure 4B As shown, with repeated welding operations, the deformation of the welding torch 17 (arrow 17a) and the loosening of the welding torch 17 (arrow 17b) will intensify. This leads to the misalignment of the welding wire 21. Figure 4C As shown, when the welding fixture 14 is replaced on the base 15, as indicated by the dashed line, the welding fixture 14 shifts position. This causes the welding wire 21 to shift. To detect the amount of shift itself corresponding to this shift in the position of the welding wire 21, the detection device 20 is configured as described below.

[0050] Figure 2 The detection plate 30 of the detection device 20 is shown. Figure 3 The block diagram shows the control system of the detection device 20.

[0051] The detection device 20 detects the offset of the welding wire 21 extending from the tip of the welding torch 17 of the welding robot 11. For example... Figure 2 and Figure 3 As shown, the detection device 20 includes a detection plate 30 and a controller 40 for controlling the detection offset. The controller 40 is connected to the robot controller 12 and receives signals between itself and the robot controller 12. The controller 40 includes an operation control unit 41, a detection unit 42, a storage unit 43, and an operation display unit 44.

[0052] like Figure 1 As shown, the detection plate 30 is fixed on the welding fixture 14. The detection plate 30 is formed of a conductor.

[0053] like Figure 2 As shown, the detection plate 30 has a first detection groove 31 extending in a first direction and a second detection groove 32 extending in a second direction orthogonal to the first direction. The first detection groove 31 has a shape in which the groove width 31a narrows in the first direction. The second detection groove 32 has a shape in which the groove width 32a narrows in the second direction. In the following description, the first direction and the second direction will be referred to as the X direction and the Y direction, respectively. Figure 2 The X-axis and Y-axis represent the X-direction and Y-direction, respectively.

[0054] The first detection groove 31 has a groove width 31a and a widest starting end 31b ( Figure 2 The right end of the groove 31a and the narrowest terminating end 31c (in the groove width 31a) Figure 2 The left end of the middle). The second detection groove 32 has the widest starting end 32b with groove width 32a. Figure 2 The lower end of the groove 32a and the narrowest terminating end 32c ( Figure 2 (The upper part of the middle).

[0055] Figure 5A and Figure 5BThis illustrates the tracking movement of the welding wire 21 inside the first detection groove 31. (Example) Figure 5A As shown, when detecting the offset of the welding wire 21 in the Y direction, the welding wire 21 is tracked and moved from the starting end 31b to the ending end 31c of the first detection groove 31 inside the first detection groove 31. When detecting the offset of the welding wire 21 in the X direction, the welding wire 21 is tracked and moved from the starting end 32b to the ending end 32c of the second detection groove 32 inside the second detection groove 32. Figure 5B As shown, the welding wire 21 extends a specified length L (e.g., 15 mm) from the contact tip 18, enabling it to contact the inner surface 31d of the first detection groove 31. The welding wire 21 can also contact the inner surface 32d of the second detection groove 32.

[0056] The first detection groove 31 of the embodiment has a shape in which the groove width 31a decreases linearly in the X direction. The second detection groove 32 also has a shape in which the groove width 32a decreases linearly in the Y direction. For ease of explanation, the type of the first detection groove 31 and the second detection groove 32 is referred to as "basic cone shape". The basic cone shape of the first detection groove 31 and the second detection groove 32 can continuously capture the contact points between the welding wire 21 and the inner surfaces 31d, 32d without interruption. The position of the groove width 31a of the first detection groove 31 in the X direction is known. The position of the groove width 32a of the second detection groove 32 in the Y direction is known. Therefore, the offset of the welding wire 21 can be detected and recorded in detail based on the "distance from the starting ends 31b, 32b". Therefore, the tendency of the welding wire 21 to offset can be easily managed, for example, the tendency of the offset to increase with the number of welding operations can be managed. As described below, the first detection groove 31 and the second detection groove 32 of the basic cone shape can also divide the detection groove into multiple intervals, and the offset of the welding wire 21 is detected based on the "contact interval". Starting from the point where the welding wire 21 contacts the inner surfaces 31d and 32d, the first detection groove 31 and the second detection groove 32 of the basic cone shape maintain continuous contact with the welding wire 21. Therefore, contact signals are not missed. For the basic cone shape, when the offset is large, the welding wire 21 maintains continuous contact with the inner surfaces 31d and 32d. Therefore, to suppress wear caused by long-term use, it is preferable to coat the inner surfaces 31d and 32d with a conductive coating that reduces sliding resistance. The basic cone shape has a simple shape. Therefore, it can be manufactured at a lower cost.

[0057] The detection plate 30 has a connecting groove 33 that connects the end of the first detection groove 31 to the end of the second detection groove 32. In the illustrated example, the connecting groove 33 connects the terminating end 31c of the first detection groove 31 to the starting end 32b of the second detection groove 32. Through the connecting groove 33, the welding wire 21 can continuously track and move from the inside of the first detection groove 31 to the inside of the second detection groove 32. Therefore, after detecting the offset of the welding wire 21 in the Y direction, the offset in the X direction can be continuously detected.

[0058] Furthermore, the connecting groove 33 can be formed at a position connecting the terminating end 32c of the second detection groove 32 and the starting end 31b of the first detection groove 31. In this case, the welding wire 21 can continuously track and move from the inside of the second detection groove 32 to the inside of the first detection groove 31 via the connecting groove 33. Therefore, after detecting the offset of the welding wire 21 in the X direction, the offset in the Y direction can be continuously detected.

[0059] When the operation control unit 41 detects the offset of the welding wire 21 in the Y direction, it controls the operation of the welding robot 11 based on the teaching data. The welding wire 21 is tracked and moved in the X direction inside the first detection groove 31. Based on the teaching data at this time, the start position, intermediate position, and end position are preset in sequence, so that the tip of the welding wire 21 is located at the center of the groove of the first detection groove 31. When the welding robot 11 runs automatically, the tip of the welding wire 21 passes through the center of the groove of the first detection groove 31.

[0060] Similarly, when the operation control unit 41 detects the offset of the welding wire 21 in the X direction, it controls the operation of the welding robot 11 based on the teaching data. The welding wire 21 is tracked and moved in the Y direction inside the second detection groove 32. Based on the teaching data at this time, the start position, intermediate position, and end position are preset in sequence, so that the tip of the welding wire 21 is located at the center of the groove of the second detection groove 32. When the welding robot 11 runs automatically, the tip of the welding wire 21 passes through the center of the groove of the second detection groove 32.

[0061] When the welding wire 21 contacts the inner side 31d of the first detection groove 31, the detection unit 42 detects the offset in the Y direction, which is orthogonal to the X direction of the welding wire 21, based on the position of the welding wire 21 in the X direction and the groove width 31a of the first detection groove 31 at the position of the welding wire 21.

[0062] During the tracking movement of the welding wire 21, if the welding wire 21 contacts the inner surface 31d of the first detection groove 31, Figure 1The path indicated by the dashed line is energized. The welding robot 11 outputs an activation signal indicating that contact has been made. Based on the activation signal, the detection unit 42 identifies the contact between the welding wire 21 and the inner surface 31d of the first detection groove 31. The position of the welding wire 21 can be determined from the operating position of the welding robot 11 controlled by the operation control unit 41. The groove width 31a of the first detection groove 31 is known in the X direction. Therefore, based on the activation signal, the operating position of the welding robot 11, and the known groove width 31a of the first detection groove 31, the detection unit 42 can detect the offset of the welding wire 21 in the Y direction.

[0063] Similarly, when the welding wire 21 contacts the inner side 32d of the second detection groove 32, the detection unit 42 detects the offset of the welding wire 21 in the X direction based on the position of the welding wire 21 in the Y direction and the groove width 32a of the second detection groove 32 at the position of the welding wire 21.

[0064] During the tracking movement of the welding wire 21, if the welding wire 21 contacts the inner surface 32d of the second detection groove 32, the welding robot 11 outputs an activation signal indicating that contact has occurred. The position of the welding wire 21 can be determined from the operating position of the welding robot 11 controlled by the operation control unit 41. The groove width 32a of the second detection groove 32 is known in the Y direction. Therefore, based on the activation signal, the operating position of the welding robot 11, and the known groove width 32a of the second detection groove 32, the detection unit 42 can detect the offset of the welding wire 21 in the X direction.

[0065] The operation control unit 41 causes the welding wire 21 to continuously track and move through both the first detection groove 31 and the second detection groove 32 via the connecting groove 33. Therefore, the offset in the Y direction and the offset in the X direction of the welding wire 21 can be continuously and rapidly detected.

[0066] Based on the offset in the Y direction and the offset in the X direction of the welding wire 21, the detection unit 42 detects the combined offset in the Y and X directions. When the offset in the Y direction of the welding wire 21 is set as y and the offset in the X direction is set as x, the combined offset r is calculated by the following equation 1.

[0067] r=(x 2 +y 2 ) 1 / 2 …(Formula 1)

[0068] Figure 5C A schematic diagram illustrating the composite offset. Figure 5CIn this equation, wa represents the width 31a of the first detection groove 31, xa and ya represent the offset of the welding wire 21 in the X and Y directions, yb represents the allowable offset of the welding wire 21 in the Y direction, and yc represents the gap size between the welding wire 21 and the inner surface 31d after the position offset. For example, if wa = 3.0 mm, the diameter of the welding wire 21 = 1.2 mm, xa = 0.7 mm, and ya = 0.7 mm, then yb = 0.9 mm and yc = 0.2 mm. According to Equation 1, the composite offset ra is r = (0.7... 2 +0.7 2 ) 1 / 2 =0.99. The welding wire 21 did not contact the inner surface 31d, thus it was judged as "OK," but in reality, a 0.99mm offset occurred, exceeding the allowable dimension yb=0.9mm. Therefore, compared to judging the offset in the X and Y directions separately, it is preferable to judge whether the offset of the welding wire 21 is appropriate based on the combined offset in the X and Y directions.

[0069] Secondly, the process of dividing the basic conical first detection groove 31 and second detection groove 32 into multiple intervals and detecting the offset of the welding wire 21 based on the "interval of contact" is explained.

[0070] like Figure 3 As shown, the storage unit 43 of the detection device 20 further includes a first storage unit 43a and a second storage unit 43b. For each interval in which the first detection groove 31 is divided into multiple sections in the X direction, the first storage unit 43a stores first data that sets the offset amount of the welding wire 21 in the Y direction. For each interval in which the second detection groove 32 is divided into multiple sections in the Y direction, the second storage unit 43b stores second data that sets the offset amount of the welding wire 21 in the X direction.

[0071] Figure 6 This is a schematic diagram illustrating the structure of the first and second data. Here, the structure of the first data is described. In this embodiment, the second data also has the same data structure. The first data includes an interval number representing the interval of the first detection groove 31, and the offset of the welding wire 21 in the Y direction within that interval. The diameter of the welding wire 21 is, for example, 1.2 mm, and the starting end 31b of the first detection groove 31 ( Figure 6 The groove width 31a at the right end is, for example, 2.9 mm, and the terminating end 31c ( Figure 6The width 31a of the groove (at the left end) is, for example, 1.3 mm. The length of the first detection groove 31 is, for example, 40.0 mm, and the length of one interval is, for example, 5.0 mm. The first detection groove 31 is divided into 8 intervals, each with a tapered shape in which the groove width 31a varies by 0.1 mm to one side in each interval. The interval numbers of the first detection groove 31 are sequentially labeled "1" to "8" from the starting end 31b to the ending end 31c. The Y-direction offset for interval "1" is set to 0.8 mm. From interval "2" onwards, each interval is set to decrease by 0.1 mm. The Y-direction offset for the final interval "8" is set to 0.1 mm.

[0072] When the welding wire 21 contacts the inner side 31d of the first detection groove 31, the detection unit 42 detects the offset of the welding wire 21 in the Y direction based on the contact area of ​​the welding wire 21 and the first data stored in the first storage unit 43a.

[0073] When the welding wire 21 moves within the first detection groove 31, it is necessary to identify which section of the first detection groove 31 it has passed through and how many millimeters the welding wire 21 has deviated from the reference. The welding robot 11 has the function of communicating with the controller 40. When the welding wire 21 passes through the range of section number "1" in the first detection groove 31, the welding robot 11 outputs "signal 1". After "signal 1" is input to the controller 40, the counter of the detection unit 42 counts "1". Subsequently, when the welding wire 21 passes through the range of section number "2" in the first detection groove 31, the welding robot 11 outputs "signal 2". After "signal 2" is input to the controller 40, the counter of the detection unit 42 counts "2". Subsequently, when the welding wire 21 passes through the range of section number "3" in the first detection groove 31, the welding robot 11 outputs "signal 1". After "signal 1" is input to the controller 40, the counter of the detection unit 42 counts "3". Thus, each time the travel range of the welding wire 21 is switched, the welding robot 11 alternately outputs "signal 1" and "signal 2". Each time "Signal 1" and "Signal 2" are alternately input to the control device, the counter of the detection unit 42 increments by 1. This process is performed by numbering the intervals from "1" to "8" in the first detection slot 31, and the counter records which interval of the first detection slot 31 the welding wire 21 has passed through. Figure 6 It also shows the value recorded in the counter.

[0074] When the welding wire 21 moves along its path, if it contacts the inner surface 31d of the first detection groove 31, the welding robot 11 outputs an activation signal indicating that contact has occurred. Based on the current value of the counter, it can be determined which section of the first detection groove 31 the welding wire 21 has passed through. The first data sets the offset of the welding wire 21 in the Y direction in each section of the first detection groove 31. Therefore, based on the activation signal, the current value of the counter, and the offset set in the first data, the detection unit 42 can detect the offset of the welding wire 21 in the Y direction, that is, the offset corresponding to the section where initial contact occurred.

[0075] Similarly, when the welding wire 21 contacts the inner side 32d of the second detection groove 32, the detection unit 42 detects the offset of the welding wire 21 in the X direction based on the contact area of ​​the welding wire 21 and the second data stored in the second storage unit 43b.

[0076] As described above, the counter records which section of the second detection groove 32 the welding wire 21 passes through. When the welding wire 21 moves along its path, if it contacts the inner surface 32d of the second detection groove 32, the welding robot 11 outputs a signal indicating that contact has occurred. Based on the current value of the counter, it can be determined which section of the second detection groove 32 the welding wire 21 has passed through. The second data sets the offset of the welding wire 21 in the X direction for each section of the second detection groove 32. Therefore, based on the signal, the current value of the counter, and the offset set in the second data, the detection unit 42 can detect the offset of the welding wire 21 in the X direction, that is, the offset corresponding to the section where initial contact occurred.

[0077] Figure 7 This is a diagram illustrating the use of first and second data to detect the offset. For example... Figure 7 As shown, for example, when the welding wire 21 contacts the inner surface 31d of the first detection groove 31 while passing through the interval number "7" in the first detection groove 31, based on the first data, the detection unit 42 detects that the offset y of the welding wire 21 from the reference Y direction corresponding to the counter value "7" is 0.2. Furthermore, when the welding wire 21 contacts the inner surface 32d of the second detection groove 32 while passing through the interval number "5" in the second detection groove 32, based on the second data, the detection unit 42 detects that the offset x of the welding wire 21 from the reference X direction corresponding to the counter value "5" is 0.4. Subsequently, the detection unit 42 calculates the composite offset r using Equation 1 as r = (0.42 + 0.22)¹ / ² = 0.45. Thus, the detection unit 42 can identify the composite offset itself in the Y and X directions.

[0078] Figure 8 This is a schematic diagram illustrating the method of determining the quality of the offset of welding wire 21 based on composite offset. Figure 8This shows the state of the welding wire 21 offset from reference O in the Y and X directions. Reference O is the center of the first detection groove 31 and the center of the second detection groove 32. The diameter of the welding wire 21 used is selected based on various factors such as the welding location and welding speed. In this embodiment, the offset index is the value of the composite offset in the Y and X directions plus the radius of the welding wire 21. The good or bad offset is determined based on the offset index. The threshold of the offset index is represented by symbol 50. When the offset of the welding wire 21 in the Y direction is y1 and the offset in the X direction is x1, the composite offset r1 is calculated by Equation 1. At this time, the offset index (composite offset r1 + radius of welding wire 21) is within the allowable range that is more inward than the threshold 50, so the offset of the welding wire 21 is judged as "OK". On the other hand, when the offset of the welding wire 21 in the Y direction is y2 and the offset in the X direction is x2, the composite offset r2 is calculated by Equation 1. At this point, the offset index (composite offset r2 + radius of welding wire 21) is outside the allowable range, which is further out than the threshold 50, and therefore the offset of welding wire 21 is judged as "NG". Since the composite offset and even the offset index itself can be detected, the impact on welding quality caused by the offset of welding wire 21 can be mitigated. Furthermore, the threshold 50 of the offset index can be set with different values ​​for each product and the diameter of the welding wire 21 used.

[0079] Figure 9A To show the main view of the operation display unit 44, Figure 9B This is a diagram illustrating an example of a timing diagram 44b displayed on a display 44a. Figure 9C This is a graph representing an example of the data displayed in time series chart 44b. Figure 9D This diagram illustrates an example of how to determine the quality of welding wire 21 offset. Figure 9E , Figure 9F A diagram to illustrate other examples of the decisions shown.

[0080] like Figure 9A As shown, the operation display unit 44 includes a display 44a and operation buttons. The operation display unit 44 is composed of a graphical user interface panel. The operation display unit 44 has slots for internal memory and external storage media such as memory cards.

[0081] like Figure 9BAs shown, the display 44a can display a timing chart 44b. The vertical axis of the timing chart 44b represents the values ​​of the Y-direction offset y, the X-direction offset x, and the combined offset r of the welding wire 21. The horizontal axis represents the number of runs of the welding robot 11. In this embodiment, before performing welding operations on the workpiece 13 to be welded, the Y-direction offset and X-direction offset of the welding wire 21 are detected. Therefore, the number of runs of the welding robot 11 is the same as the number of times the offset of the welding wire 21 is detected. The timing chart 44b uses a black triangle to represent the Y-direction offset y, a black square to represent the X-direction offset x, and a black circle to represent the combined offset r. The timing chart 44b shows a combined offset r of 0.5 mm marked as a notice line 44c and a combined offset r of 0.6 mm marked as an abnormal line 44d. The notice line 44c is indicated, for example, in yellow. The abnormal line 44d is indicated, for example, in red. The timing chart 44b visualizes the offset and the tendency of the offset. Therefore, the operator can easily grasp that the composite offset r tends to increase with the number of times the welding robot 11 is started.

[0082] like Figure 9C As shown, the data 44e displayed in timing chart 44b includes the production counter, the offset x in the X direction, the offset y in the Y direction, and the composite offset r. The data is stored in internal memory. Data can also be stored on external storage media for external data retrieval and traceability.

[0083] like Figure 9D As shown, the display 44f for judging the quality of the welding wire 21 offset includes the judgment of the number of runs of the welding robot 11, the offset x in the X direction, the offset y in the Y direction, the composite offset r, and the offset index (composite offset r + radius of welding wire 21).

[0084] The displayed judgment is "OK" (see reference). Figure 9D "Note" (refer to) Figure 9E ) and "NG" (refer to) Figure 9F There are three types: "OK" indicates the offset indicator is within the allowable range, "Caution" indicates the offset indicator is approaching the limit of the allowable range, and "NG" indicates the offset indicator is outside the allowable range. "OK" is indicated by, for example, a green light. "Caution" is indicated by, for example, a yellow light. "NG" is indicated by, for example, a red light.

[0085] When the result is "OK" or "Caution", the offset index does not exceed the threshold of 50, so the welding robot 11 moves on to the next action for welding. When the result is "NG", the offset index exceeds the threshold of 50, so the welding device 10 stops operating and an anomaly report is generated.

[0086] Secondly, the sequence of welding operations will be explained.

[0087] Figure 10A and Figure 10B This is a flowchart illustrating the sequence of welding operations using the offset detection method for welding wire 21. Control is executed by the CPU of the robot controller 12 and the CPU of the controller 40 of the detection device 20.

[0088] Before performing welding operations on the workpiece 13, the offset of the welding wire 21 in the Y and X directions is detected each time. In order to detect the offset of the welding wire 21, the welding robot 11 moves towards the detection plate 30 (S101).

[0089] First, the offset of the welding wire 21 in the Y direction is detected. The welding wire 21 is tracked and moved in the X direction inside the first detection groove 31. The offset is sampled from the starting end 31b of the first detection groove 31 (S102) to the ending end 31c (S103). When the welding wire 21 contacts the inner surface 31d of the first detection groove 31, the offset of the welding wire 21 in the Y direction is detected based on the position of the welding wire 21 in the X direction and the groove width 31a of the first detection groove 31 at the position of the welding wire 21. The detected offset in the Y direction is sampled.

[0090] Regardless of whether the welding wire 21 contacts the inner surface 31d of the first detection groove 31, the welding wire 21 is moved along a track from the starting end 31b to the ending end 31c of the first detection groove 31. By moving the welding wire 21 along a track to the ending end 31c of the first detection groove 31, there is no need to change the posture of the welding robot 11 during the process. Therefore, the control of the welding robot 11 when detecting the offset of the welding wire 21 in the Y direction becomes easier.

[0091] Next, the offset of the welding wire 21 in the X direction is detected. The welding wire 21 is tracked and moved in the Y direction inside the second detection groove 32. The offset sampling starts from the starting end 32b of the second detection groove 32 (S104) and ends at the ending end 32c (S105). When the welding wire 21 contacts the inner surface 32d of the second detection groove 32, the offset of the welding wire 21 in the X direction is detected based on the position of the welding wire 21 in the Y direction and the groove width 32a of the second detection groove 32 at the position of the welding wire 21. The detected offset in the X direction is sampled.

[0092] Regardless of whether the welding wire 21 contacts the inner surface 32d of the second detection groove 32, the welding wire 21 is moved along a track from the starting end 32b to the ending end 32c of the second detection groove 32. By moving the welding wire 21 along a track to the ending end 32c of the second detection groove 32, there is no need to change the posture of the welding robot 11 during the process. Therefore, the control of the welding robot 11 when detecting the offset of the welding wire 21 in the X direction becomes easier.

[0093] After the offset sampling is completed, the welding robot 11 retracts from the detection plate 30 (S106) and moves to the standby position for welding operation.

[0094] Calculate the offset index (S107). The offset index is a value that is the combined offset in the Y and X directions plus the radius of the welding wire 21. The combined offset is calculated based on the Y and X offsets of the sampled welding wire 21. Determine whether the offset of the welding wire 21 is qualified or not based on the offset index (S108), and output the determination result to the operation display unit 44 (S109).

[0095] When the offset index is below the threshold of 50 (S110: Yes), the welding robot 11 begins welding (S111). After welding is completed (S112), the welding robot 11 moves to the standby position for detecting the offset of the welding wire 21.

[0096] On the other hand, if the offset index exceeds the threshold of 50 (S110: No), an anomaly report is made and the equipment is stopped (113). For the abnormal offset of the welding wire 21, appropriate repair processing is performed (S114). In terms of repair processing, for example, replacing the consumed contact tip 18, etc.

[0097] After the repair process is completed (S115: Yes), the abnormality report is cancelled and the equipment is stopped (116).

[0098] As described above, the detection device 20 of this embodiment has a detection plate 30 with a first detection groove 31 and a second detection groove 32. The first detection groove 31 has a shape in which the groove width 31a narrows in the X direction, and the second detection groove 32 has a shape in which the groove width 32a narrows in the Y direction. The operation control unit 41 controls the operation of the welding robot 11 based on teaching data, causing the welding wire 21 to move along a line in the X direction inside the first detection groove 31, and then to move along a line in the Y direction inside the second detection groove 32. Subsequently, when the welding wire 21 contacts the inner surface 31d of the first detection groove 31, the detection unit 42 detects the offset of the welding wire 21 in the Y direction based on the position of the welding wire 21 in the X direction and the groove width 31a of the first detection groove 31 at the position of the welding wire 21. When the welding wire 21 contacts the inner side 32d of the second detection groove 32, the detection unit 42 also detects the offset of the welding wire 21 in the X direction based on the position of the welding wire 21 in the Y direction and the groove width 32a of the second detection groove 32 at the position of the welding wire 21.

[0099] With this configuration, the widths 31a and 32a of the first detection groove 31 and the second detection groove 32 are narrowed. Therefore, based on the contact position of the welding wire 21 and the groove widths 31a and 32a known at that position, the offset in the Y direction and the offset in the X direction of the welding wire 21 can be accurately detected respectively. Thus, a detection device 20 can be provided that can detect the offset itself corresponding to the positional offset of the welding wire 21.

[0100] Because the offset of the welding wire 21 that causes derailment during welding can be accurately detected, welding defects can be reduced. Furthermore, based on the detected offset of the welding wire 21, its change over time can be understood and its offset tendency can be managed. For example, regarding consumable parts such as the contact tip 18, premature replacement for safety reasons may result in over-replacement, leading to cost disadvantages. In this embodiment, because the offset tendency of the welding wire 21 can be managed, consumable parts can be replaced at the optimal replacement time, thereby reducing costs.

[0101] The first storage unit 43a stores first data, which sets the offset of the welding wire 21 in the Y direction for each interval that divides the first detection groove 31 into multiple intervals in the X direction. The second storage unit 43b stores second data, which sets the offset of the welding wire 21 in the X direction for each interval that divides the second detection groove 32 into multiple intervals in the Y direction. When the welding wire 21 contacts the inner surface 31d of the first detection groove 31, the detection unit 42 detects the offset of the welding wire 21 in the Y direction based on the interval in which the welding wire 21 contacts and the first data stored in the first storage unit 43a. When the welding wire 21 contacts the inner surface 32d of the second detection groove 32, the detection unit 42 also detects the offset of the welding wire 21 in the X direction based on the interval in which the welding wire 21 contacts and the second data stored in the second storage unit 43b. Thus, based on the interval in which the welding wire 21 contacts, both the offset in the Y direction and the offset in the X direction of the welding wire 21 can be detected separately. Therefore, the offset itself corresponding to the positional offset of the welding wire 21 can be detected.

[0102] The detection unit 42 detects the combined offset in the Y and X directions based on the offset of the welding wire 21 in the Y and X directions. This configuration allows for the detection of situations where the individual offsets in the Y and X directions are within acceptable limits, but the combined offset is outside the acceptable range. Because the combined offset itself can be detected, welding defects caused by the offset of the welding wire 21 can be more effectively prevented in advance.

[0103] The detection plate 30 has a connecting groove 33 that connects the terminating end 31c of the first detection groove 31 to the starting end 32b of the second detection groove 32. The operation control unit 41 causes the welding wire 21 to continuously track and move through both the first detection groove 31 and the second detection groove 32 via the connecting groove 33. With this configuration, the operation of the welding robot 11 can be simplified, and the offset in the Y direction and the offset in the X direction can be detected more quickly.

[0104] The detection plate 30 is fixed on the welding fixture 14. With this configuration, it is possible to detect the displacement of the welding wire 21 caused by the positional displacement of the welding fixture 14.

[0105] The first detection groove 31 has a groove width 31a that decreases linearly in the X direction, and the second detection groove 32 has a groove width 32a that decreases linearly in the Y direction. With this configuration, the welding wire 21 maintains continuous contact with the inner surface 31d of either the first or second detection groove 32, starting from the point where it contacts the inner surface 32d of either the first or second detection groove 31. Therefore, no contact signal is missed, and the offset of the welding wire 21 can be detected more accurately.

[0106] The offset detection method for the welding wire 21 in this embodiment uses a detection plate 30 with a first detection groove 31 and a second detection groove 32. The first detection groove 31 has a groove width 31a that narrows towards the X direction, and the second detection groove 32 has a groove width 32a that narrows towards the Y direction. The operation of the welding robot 11 is controlled based on teaching data, causing the welding wire 21 to move along a track in the X direction inside the first detection groove 31, and then to move along a track in the Y direction inside the second detection groove 32. Subsequently, when the welding wire 21 contacts the inner surface 31d of the detection groove 31, the offset of the welding wire 21 in the Y direction, which is orthogonal to the X direction, is detected based on the position of the welding wire 21 in the X direction and the groove width 31a of the first detection groove 31 at the position of the welding wire 21. Furthermore, when the welding wire 21 contacts the inner side 32d of the second detection groove 32, the offset of the welding wire 21 in the X direction is detected based on the position of the welding wire 21 in the Y direction and the groove width 32a of the second detection groove 32 at the position of the welding wire 21.

[0107] With this configuration, the widths 31a and 32a of the first detection groove 31 and the second detection groove 32 are narrowed. Therefore, based on the contact position of the welding wire 21 and the groove widths 31a and 32a known at that position, the offset of the welding wire 21 in the Y direction and the offset in the X direction can be accurately detected respectively. Thus, a method for detecting the offset of the welding wire 21 can be provided that can detect the offset itself corresponding to the positional offset of the welding wire 21.

[0108] Because the offset of the welding wire 21 that causes derailment during welding can be accurately detected, welding defects can be reduced. Furthermore, by detecting the offset of the welding wire 21, its change over time can be understood and its offset tendency can be managed. Therefore, consumable parts such as the contact tip 18 can be replaced at the optimal replacement time, thereby reducing costs.

[0109] Regardless of whether the welding wire 21 contacts the inner surface 31d of the first detection groove 31, the welding wire 21 moves from the starting end 31b of the first detection groove 31 to the ending end 31c. Similarly, regardless of whether the welding wire 21 contacts the inner surface 32d of the second detection groove 32, the welding wire 21 moves from the starting end 32b of the second detection groove 32 to the ending end 32c. This configuration simplifies the operation of the welding robot 11 and enables more rapid detection of offsets in the Y and X directions.

[0110] Before welding workpiece 13, the offset of welding wire 21 in the Y direction is detected, and then the offset of welding wire 21 in the X direction is detected. This configuration can prevent welding defects from occurring in advance.

[0111] (Modified examples of the first detection slot 31 and the second detection slot 32)

[0112] Figure 11A , Figure 11B , Figure 11C , Figure 11D , Figure 11E , Figure 11F This is a front view showing a modified example of the detection groove. Furthermore, to clearly indicate the shape of the detection groove, shading lines have been added to areas other than the detection groove in these figures.

[0113] The first detection groove 31 is not limited to a shape in which the groove width 31a decreases linearly in the X direction. Similarly, the second detection groove 32 is not limited to a shape in which the groove width 32a decreases linearly in the Y direction. As long as the detection groove has a shape in which the groove widths 31a and 32a narrow in the direction extending toward the detection groove (X direction or Y direction), it can be changed to a suitable shape as described below.

[0114] like Figure 11AAs shown, the detection groove 61 can have a shape in which the groove width 61a decreases in a stepped manner at certain intervals in the direction extending towards the detection groove 61 (X direction or Y direction). For ease of explanation, this form of the detection groove 61 is referred to as a "stepped straight shape". The stepped straight shape detection groove 61 is the same as the basic conical detection groove of the embodiment, and the welding wire 21 will continuously contact the inner surface 61d from the point where the welding wire 21 contacts it. Therefore, no contact signal is missed. The width of a section has a straight shape. Therefore, it is not possible to detect the offset of the welding wire 21 based on the "distance from the starting end 31b, 32b" as in the basic conical shape. In the case of the stepped straight shape, the offset of the welding wire 21 is detected based on the "contacted section". The stepped straight shape is the same as the basic conical shape. When the offset is large, the welding wire 21 will continuously contact the inner surface 61d. Therefore, in order to suppress wear caused by long-term use, it is preferable to coat the inner surface 61d with a conductive coating or the like to reduce sliding resistance.

[0115] like Figure 11B As shown, the detection groove 62 has protrusions 62e at regular intervals in the direction extending toward the detection groove 62 (X direction or Y direction). The protrusions 62e protrude from the inner surface 62d of the detection groove 62. For ease of explanation, this form of the detection groove 62 is referred to as a "cone with protrusions". It can be said that the detection groove 62 with protrusions also has a shape in which the groove width 62a decreases in a stepped manner in the direction extending toward the detection groove 62 (X direction or Y direction) at regular intervals. The detection groove 62 with protrusions detects the contact between the welding wire 21 and the inner surface 62d at the protrusions 62e. Therefore, it is not possible to detect the offset of the welding wire 21 based on the "distance from the starting ends 31b, 32b" as in the basic cone. In the case of the cone with protrusions, the offset of the welding wire 21 is detected based on the "contacted area". In the case of the cone with protrusions, the contact time between the welding wire 21 and the surface is short, thus reducing wear caused by long-term use. Of course, a conductive coating to reduce sliding resistance can also be applied to the protrusion 62e.

[0116] The shape of the protrusion 62e is not limited to a semi-circular arc shape; it can be changed to a rectangular shape. Figure 11C ) or triangular shape ( Figure 11D Suitable shapes, such as (e.g., ).

[0117] like Figure 11EAs shown, the detection groove 63 has a groove width 63a that decreases linearly in the direction extending toward the detection groove 63 (X direction or Y direction). It has a conical shape only on one side of the inner surface 63d. For ease of explanation, this form of the detection groove 63 is referred to as a "single-sided conical". The single-sided conical detection groove 63 is the same as the basic conical detection groove, where the welding wire 21 maintains continuous contact with the inner surface 63d starting from the point where it contacts the inner surface 63d. Therefore, no contact signal is missed. Similar to the basic conical, the offset of the welding wire 21 can be detected based on the distance from the starting ends 31b, 32b. Like the basic conical, when the offset is large, the welding wire 21 maintains continuous contact with the inner surface 63d. Therefore, to suppress wear caused by long-term use, it is preferable to coat the inner surface 63d with a conductive coating or the like to reduce sliding resistance. The single-sided conical is suitable for use when the offset direction of the welding wire 21 is determined in one direction (the upper direction in the figure).

[0118] like Figure 11F As shown, the detection groove 64 has a shape in which two single-sided cones, reversed along the left-right direction as shown in the figure, are staggered in the length direction. For ease of explanation, this form of the detection groove 64 is referred to as a "single-sided cone combination shape". Compared with the single-sided cone shape, even when the offset direction of the welding wire 21 is not determined, the single-sided cone combination shape detection groove 64 can detect the offset of the welding wire 21.

[0119] As described above, the first detection groove 31 may have a shape in which the groove width 31a decreases in a stepped manner at certain intervals in the X direction. Furthermore, the second detection groove 32 may have a shape in which the groove width 32a decreases in a stepped manner at certain intervals in the Y direction. By configuring it in this stepped shape, the welding wire 21 will continuously contact the inner surface 31d of the first detection groove 31 or the inner surface 32d of the second detection groove 32, starting from the point where the welding wire 21 contacts it. Therefore, no contact signal is missed, and the offset of the welding wire 21 can be detected more accurately.

[0120] (Other variations)

[0121] This invention is not limited to the embodiments described above, and appropriate modifications can be made. In this embodiment, both the offset in the Y direction and the offset in the X direction of the welding wire 21 are detected, but of course, only the offset in one direction can be detected. In this embodiment, the offset index is a value that is the composite offset r plus the radius of the welding wire 21, but the offset index can be just the composite offset r, or it can be a value other than the radius of the welding wire 21 added to the composite offset r.

Claims

1. A device for detecting the offset of welding wire, the device comprising a detection plate, an operation control unit, and a detection unit, for detecting the offset of welding wire extending from the tip of the welding torch of a welding robot. The detection plate has a first detection groove extending in a first direction, the first detection groove having a shape in which the groove width narrows in the first direction. The operation control unit controls the operation of the welding robot based on the teaching data, causing the welding wire to move along a line inside the first detection groove in the first direction. When the welding wire contacts the inner side of the first detection groove, the detection unit detects the offset of the welding wire in a second direction orthogonal to the first direction based on the position of the welding wire toward the first direction and the groove width of the first detection groove at the position of the welding wire.

2. The wire offset detection device according to claim 1, wherein, It also has a first storage section, The first storage unit stores first data, which sets the offset of the welding wire in the second direction for each interval that divides the first detection groove toward the first direction into a plurality of intervals. When the welding wire contacts the inner side of the first detection groove, the detection unit detects the offset of the welding wire in the second direction based on the contact area of ​​the welding wire and the first data stored in the first storage unit.

3. The wire offset detection device according to claim 1, wherein, The detection plate also has a second detection groove extending toward the second direction, the second detection groove having a shape in which the groove width narrows toward the second direction. The operation control unit controls the operation of the welding robot based on the teaching data, causing the welding wire to move along a line inside the second detection groove in the second direction. When the welding wire contacts the inner side of the second detection groove, the detection unit detects the offset of the welding wire in the first direction based on the position of the welding wire toward the second direction and the groove width of the second detection groove at the position of the welding wire.

4. The wire offset detection device according to claim 3, wherein, It also has a second storage section. The second storage unit stores second data, which sets the offset of the welding wire in the first direction for each interval that divides the second detection groove toward the second direction into a plurality of intervals. When the welding wire contacts the inner side of the second detection groove, the detection unit detects the offset of the welding wire in the first direction based on the contact area of ​​the welding wire and the second data stored in the second storage unit.

5. The wire offset detection device according to claim 3 or claim 4, wherein, The detection unit detects the combined offset of the second direction and the first direction based on the offset of the welding wire in the second direction and the offset in the first direction.

6. The wire offset detection device according to claim 3 or claim 4, wherein, The detection plate has a connecting groove that connects the narrowest terminating end of the first detection groove and the widest starting end of the second detection groove, or connects the narrowest terminating end of the second detection groove and the widest starting end of the first detection groove. The operation control unit causes the welding wire to continuously track and move through both the first detection slot and the second detection slot via the connecting groove.

7. The wire offset detection device according to claim 1 or claim 3, wherein, The detection plate is fixed on the welding fixture of the workpiece to be welded.

8. The wire offset detection device according to claim 1, wherein, The first detection groove has a shape in which the groove width decreases linearly toward the first direction, or has a shape in which the groove width decreases in a stepped manner toward the first direction at certain intervals.

9. The wire offset detection device according to claim 3, wherein, The second detection groove has a shape in which the groove width decreases linearly toward the second direction, or has a shape in which the groove width decreases in a stepped manner toward the second direction at certain intervals.

10. A method for detecting the offset of a welding wire, the method comprising detecting the offset of a welding wire extending from the tip of a welding torch of a welding robot, including, The welding robot is controlled based on teaching data, causing the welding wire to move along a line in a first direction inside the first detection groove. The first detection groove is formed in the detection plate and extends in the first direction, with its width narrowing in the first direction. When the welding wire contacts the inner side of the first detection groove, the offset of the welding wire in a second direction orthogonal to the first direction is detected based on the position of the welding wire toward the first direction and the groove width of the first detection groove at the position of the welding wire.

11. The method for detecting the offset of welding wire according to claim 10, wherein, Regardless of whether the welding wire is in contact with the inner side of the first detection groove, the welding wire is moved from the widest starting end of the first detection groove to the narrowest ending end.

12. The method for detecting the offset of welding wire according to claim 10 or claim 11, wherein, Before performing welding operations on the workpiece to be welded, the offset of the welding wire in the second direction is detected.

13. The method for detecting the offset of welding wire according to claim 10, wherein, The welding robot is controlled based on the teaching data, causing the welding wire to move along a track inside the second detection groove in the second direction. The second detection groove is formed in the detection plate and extends in the second direction, with its width narrowing in the second direction. When the welding wire contacts the inner side of the second detection groove, the offset of the welding wire in the first direction is detected based on the position of the welding wire toward the second direction and the groove width of the second detection groove at the position of the welding wire.

14. The method for detecting the offset of welding wire according to claim 13, wherein, Regardless of whether the welding wire is in contact with the inner side of the second detection groove, the welding wire is moved from the widest starting end of the second detection groove to the narrowest ending end.

15. The method for detecting the offset of welding wire according to claim 13 or claim 14, wherein, Before performing welding operations on the workpiece to be welded, the offset of the welding wire in the first direction is detected.

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