Automatic welding method and automatic welding device

Abstract

To provide a method for detecting a position of a welding line to perform automatic welding with a simpler device and control without needing complicated processing.SOLUTION: In an automatic welding method using a welder which performs fillet welding while operating a welding torch in line with a welding line, the welder travels in a direction inclining relative to the welding line, measures a torch measurement distance, a distance from the welding torch to a welded member, and operates the welding torch in a first orthogonal direction substantially orthogonal to a travel direction of the welder and a second orthogonal direction which is substantially orthogonal to a torch measurement distance measuring direction and different from the first orthogonal direction when the torch measurement distance changes.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to an automatic welding method and an automatic welding device for performing fillet welding while operating a welding torch. [Background technology]

[0002] When attempting to obtain a welded joint of stable quality in arc welding, automatic welding is applied. Automatic welding utilizes a welding robot or cart, and employs a method of welding while moving a welding torch to follow the weld line, and is configured with a detection means for detecting the weld line.

[0003] Methods for detecting a weld line to allow a welding torch to follow the weld line have been proposed according to the shape of the joint, and for fillet welding, methods are shown in Patent Documents 1 and 2. Patent Document 1 discloses a device using a welding robot, which scans the vicinity of the weld line with a laser beam and detects the weld line by processing the trajectory of the reflected light of the laser beam captured by a camera. Patent Document 2 discloses a welding method using a cart, which uses multiple laser rangefinders to measure whether or not there is any tilt between the cart and the weld line, and if tilt occurs, controls the wheel movement of the traveling cart to rotate the cart and correct it to a parallel state without tilt. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-62566 [Patent Document 2] Japanese Patent Application Publication No. 11-216566 Summary of the Invention [Problem to be solved by the invention]

[0005] In the case of the device in Patent Document 1, in order to process the image of the laser beam trajectory obtained by the camera, it is necessary to identify the shape of the part to be welded and detect the weld line based on that shape. Therefore, in addition to a laser beam scanning device, a complex device that performs precise shape identification and weld line detection is required.

[0006] Furthermore, the device in Patent Document 2 requires measuring multiple distances, and is equipped with multiple distance measurement devices and a complex travel function for controlling multiple wheels to keep the carriage parallel to the weld line. This requires highly accurate and stable control of the multiple distance measurement devices and wheel rotation control based on the measurement results, which also complicates the control aspect.

[0007] When adopting an automatic welding method or device, the complexity of the device and control not only increases costs, but also may lead to an increase in processing time and weight.

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method for automatic welding by detecting the position of a welding line using simpler devices and control without requiring complex processing, and an automatic welding device for realizing this method. [Means for solving the problem]

[0009] Therefore, the present invention provides an automatic welding method using a welding machine that performs fillet welding while moving a welding torch in accordance with a weld line, as follows.

[0010] The welding machine advances in a direction inclined to the weld line, measures a torch measurement distance, which is the distance from the welding torch to the workpiece, and when the torch measurement distance changes, moves the welding torch in a first orthogonal direction that is approximately perpendicular to the direction of advancement of the welding machine and in a second orthogonal direction that is approximately perpendicular to the measurement direction of the torch measurement distance and different from the first orthogonal direction.

[0011] This allows for good welding along the desired weld line by simply moving the welding torch as described above to a position where the measured torch distance reaches a predetermined value based on the change in the measured torch distance. In other words, stable, consistent quality welding can be achieved with simple means and control.

[0012] The present invention also provides an automatic welding apparatus including an extension guide and a carriage that travels along the extension guide and has a welding torch for welding workpieces, the apparatus comprising the following configuration.

[0013] The extension guide extends in a direction inclined to the weld line of the workpieces to be welded, and the cart has a distance measurement unit that measures the torch-measured distance from the welding torch to the workpieces to be welded, a distance determination unit that determines whether the measured distance matches a predetermined distance based on the measurement data of the distance measurement unit, and a torch movement unit that can move the welding torch based on the distance determination unit, and is controlled so that the torch-measured distance can be maintained at the predetermined distance as the cart moves forward.

[0014] With this configuration, the torch moving unit moves the welding torch unit until the predetermined distance is met in accordance with the determination by the distance determining unit, thereby achieving good welding. [Effects of the Invention]

[0015] According to the present invention, based on the distance measurement in one direction from the welding torch to the workpiece, the position of the welding torch is controlled so that the measured distance (torch measurement distance) matches a predetermined value, thereby enabling welding of a consistent quality. This provides an automatic welding method and automatic welding device with a control method and device configuration that are simpler than conventional methods. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a diagram showing the appearance of a garbage compactor according to an embodiment of the present invention; [Figure 2]2. (a) is a cross-sectional view of the body of a refuse compactor according to an embodiment of the present invention taken along the line AA in FIG. 2. (b) is an enlarged view of part B. [Figure 3] 1 is a front view showing the overall configuration of an automatic welding apparatus according to an embodiment of the present invention; [Figure 4] FIG. 2 is a top view showing the relationship between the rail, the workpieces to be welded, the weld line, and the carriage. [Figure 5] FIG. 10 is a diagram showing a state in which a welding torch and a laser rangefinder are set at appropriate positions. [Figure 6] This is an enlarged view of the weld line and the edge area. (a) shows the state where the laser beam from the laser rangefinder is irradiating the upper steel member, and (b) shows the state where the torch part has moved to the right and is irradiating the lower steel member. DETAILED DESCRIPTION OF THE INVENTION

[0017] An example of an embodiment of the present invention will be described below. 1 shows a garbage truck 1 equipped with a cargo box 11 to be welded by the automatic welding device according to the present invention. The cargo box 11 is a steel box mounted on a chassis frame with its longitudinal direction extending in the fore-and-aft direction of the vehicle, and has an elongated shape with its longitudinal direction extending in the fore-and-aft direction of the vehicle.

[0018] FIG. 2(a) is a cross-sectional view of the cargo box 11 shown in FIG. 1 taken along the line AA. As shown in the figure, the cargo box 11 is formed by assembling multiple metal plates (steel members). In this embodiment, welding of part B, where the steel members are joined together, will be mainly described. As shown in FIG. 2(b), which is an enlarged view of part B, a steel member 14 is placed on top of a steel member 13 that forms the floor of the cargo box. In this embodiment, the top surface of the steel member 13 is welded to the end surface of the steel member 14. The intersection of the top surface of the steel member 13 and the end surface of the steel member 14, with the longitudinal direction of the vehicle as the longitudinal direction, forms the weld line 12. In this embodiment, welding is performed along the weld line 12. Therefore, multiple steel members are spot-welded to each other (locally welded at several locations along the longitudinal direction of the vehicle) to create a temporary assembly state. Then, an automatic welding device is inserted into the space S surrounded by multiple steel members on the top, bottom, left, and right sides as shown in the figure, and continuous welding (main welding) is performed along the longitudinal direction of the vehicle.

[0019] The configuration of an automatic welding device 2 according to this embodiment for continuous welding will be described with reference to Fig. 3. Fig. 3 is a front view of the automatic welding device 2. The automatic welding device 2 is equipped with a rail 3 installed on a steel member 13 and a carriage 4 that runs on the rail 3. The carriage 4 is equipped with a control unit 41 provided on the top, an arm 42 that extends to the side (the negative X-axis direction), and a torch unit 43 attached to the arm 42 and facing downward.

[0020] The rail 3 has the function of guiding the travel of the bogie 4, and is a long member extending in a direction inclined on a horizontal plane with respect to the weld line in the longitudinal direction of the vehicle. The rail 3 has a base portion 301 and a guide portion 302, and the base portion 301 is provided with a fixing magnet 303 at its bottom, and is fixed to the upper surface of the steel member 13 via the magnetic force of the magnet 303. The guide portion 302 is provided in a fixed state on the base portion 301, and has a substantially inverted T-shaped cross section. Both the base portion 301 and the guide portion 302 are long members extending in the above-mentioned inclined direction.

[0021] In addition to the control unit 41, arm 42, and torch unit 43, the carriage 4 also includes rollers 50 and a roller drive unit 51. There are two sets of rollers 50, one set at the front and one at the rear of the carriage 4, one set shown in the figure. The carriage 4 has four roller units that roll on the approximately inverted T-shaped upright portion of the guide unit 302. Two of the four roller units roll on the side of the upright portion of the guide unit 302 (the right side in the figure), one roller unit rolls on the opposite side of the upright portion (the left side in the figure), and the remaining roller unit rolls on the top surface of the upright portion. The front set of rollers is not shown because it overlaps with the rear set. These roller units enable the carriage 4 to move stably along the extension direction of the guide unit 302. The roller drive unit 51 has a drive source (not shown) that drives the rollers 50, and the drive source is turned on or off at the appropriate timing to start automatic welding.

[0022] The control unit 41 is connected to the roller drive source 51, enabling it to output drive control commands, and is also connected to the arm drive unit 422, distance measurement unit 432, and distance determination unit (not shown), which will be described later, enabling it to input and output data.

[0023] The arm 42 is composed of a joint 421 with the carriage 4, an arm drive unit 422 extending horizontally from the joint 421, and an arm movement unit 423 attached to the arm drive unit 422 and movable horizontally. The arm movement unit 423 can be moved horizontally relative to the carriage 4 by the arm drive unit 422, and the arm drive unit 422 has a known configuration such as a unit of an electric motor and a ball screw, or a unit of an electric motor and a belt. In addition, the torch unit 43 is attached to the arm movement unit 423.

[0024] The torch unit 43 includes a welding torch 431 for performing arc welding, a distance measurement unit 432 for measuring the distance between the welding torch 431 and the steel members 13 and 15 (torch measurement distance), and a light shielding plate 433 (shown by a dashed line in Figure 3) arranged so as not to interfere with the measurement function of the distance measurement unit 432.

[0025] As shown in the figure, the welding torch 431 is positioned to point toward the weld line formed between the steel members 13 and 15, enabling fillet welding of the steel members 13 and 15. The distance measurement unit 432 includes a laser range finder 432a capable of measuring the distance from a predetermined location on the torch unit 43 to the top surface of the upper steel member 14 of the two steel members. The distance measurement unit 432 is positioned adjacent to the welding torch 431 in front of the carriage 4 in the direction of travel. The distance measurement unit 432 irradiates the steel member 14 with a laser beam and measures the distance using the reflected light. Information on the measured distance (torch-measured distance) is sent to a distance determination unit in the control unit 41. The distance determination unit determines whether the data measured and output by the distance measurement unit 432 matches a predetermined size. The control unit 41 outputs a drive control command to the arm drive unit 422 based on the determination result of the distance determination unit. Light shielding plate 433 is provided between laser rangefinder 432a and welding torch 431 to prevent welding arc light from affecting the measurements of laser rangefinder 432a. Torch unit 43 is further provided with a tracing mechanism 434 that maintains a constant distance from steel member 14. Trace mechanism 434 has a rod-shaped extension member that extends toward steel member 14 and a wheel attached to the tip of the extension member, and can move vertically together with torch unit 43, and by pressing the wheel against the member to be welded by gravity or the like, helps to maintain a constant distance between torch unit 43 and steel member 14.

[0026] Next, an automatic welding method for fillet welding the steel members 13 and 15 using the automatic welding device 4 will be described. As shown in Figure 4, which is a top view of steel members 13, 15 and bogie 4, bogie 4 is mounted on rails 3 that are inclined in the X-axis direction with respect to a weld line 12, the longitudinal direction of which is the fore-and-aft direction of the vehicle (Y-axis direction) on steel member 13, and is moved in the direction of arrow A. As bogie 4 moves forward, the distance between weld line 12 and rail 3 increases, but the difference in distance between the end (starting point) and end (ending point) of steel member 13 and weld line 12 is set to a value sufficiently small relative to the range of movement of arm movement unit 423. Note that, for ease of explanation, in Figure 4, weld line 12, which is hidden by the end of steel member 14 located above, is shown by a dashed line.

[0027] However, before the carriage 4 starts to move, the positions of the welding torch 431 and the laser rangefinder 432a are adjusted using their respective position adjustment mechanisms 435a and 435b. In this embodiment, as shown in Fig. 5, the laser beam emitted from the laser rangefinder 432a is irradiated in a direction approximately vertical to the upper surface of the steel member 14 (the right end in the figure). At this time, the irradiation position 103 of the laser beam is adjusted to be near the end of the steel member 14 as shown in Fig. 6(a). The distance measured by the laser rangefinder 432a at this time is set as the predetermined distance.

[0028] Welding is started and carriage 4 also begins to move forward. Even if the positional relationship between carriage 4 and weld line 12 changes slightly due to undulations of steel members 13, the vertical distance between welding torch 431 and weld line 12 is kept constant by tracing mechanism 434. On the other hand, because the extension direction of rail 3 is inclined with respect to weld line 12, carriage 4 gradually moves away from weld line 12 (steel members 13) as it moves forward.

[0029] In particular, because the laser beam from the laser range finder 432a is directed toward the right end of the steel member 14, if the position of the welding torch 431 shifts slightly to the right as the carriage 4 moves, the target of irradiation with the laser beam will be the upper surface of the steel member 13, as shown in FIG. 6(b). At this time, the distance measured by the laser range finder 432a (torch measured distance) increases approximately by the thickness of the steel member 14 stacked on top. Data regarding the torch measured distance is output to the distance determination unit, which determines that it does not match the predetermined distance. Based on the determination result, the control unit 41 outputs a drive command to the arm drive unit 422. When the arm drive unit 422 is driven, the arm movement unit 423 moves toward the tip of the arm 42. Specifically, the arm moves toward the weld line 12 in a direction (see FIG. 4) that is substantially perpendicular to the extending direction of the rail and that approaches the weld line 12 along the XY plane (see FIG. 4) that is substantially perpendicular to the laser irradiation direction (distance measurement direction) of the laser range finder 432a.

[0030] Measurement of the torch measurement distance by the laser rangefinder 432a continues while the carriage 4 is moving, and the arm drive unit 422 continues to drive and the arm movement unit 423 continues to move until the torch measurement distance value returns to the predetermined distance value. When data of the torch measurement distance that matches the predetermined distance value is input to the distance determination unit and the distance determination unit determines that it matches the predetermined distance, the control unit 41 stops the drive command to the arm drive unit 422. This stops the movement of the arm movement unit 423, eliminates the deviation of the welding torch 431 from the weld line 12, and allows the welding torch 431 to continue welding on the weld line 12 appropriately.

[0031] In this embodiment, torch unit 43 is controlled based on the measurement of the torch measurement distance and the judgment by the distance judgment unit, while actively moving cart 4 away from the weld line as cart 4 advances, eliminating the need to provide means or control for measuring the distance of welding torch 431 to weld line 12 or for identifying the position and shape of the weld line, and enabling automatic welding with sufficient accuracy with a simpler device configuration and control than conventional systems. Also, because the position of weld line 12 is detected from changes in the measurement value of laser distance meter 432a, which measures in the approximately vertical direction, the position can be detected without complex processing.

[0032] Furthermore, if the welding torch 431 can be positioned appropriately, similar control is possible by installing the rail 3 on the steel member 14 and tilting the rail 3 in a direction that approaches the welding line 12 as the carriage 4 moves forward.

[0033] Similar control is also possible by setting the laser rangefinder 432a to target the steel member 13 below, with the rail 3 tilted in the direction of extension toward the weld line 12 as the bogie 4 moves forward. However, because several small welds have been made in advance on the weld line 12 by tack welding, if the tack weld locations overlap with the irradiation position of the laser beam, the torch measurement distance will be shortened due to the influence of the raised portions caused by the tack welding. The shortened distance depends on the size of the tack welding, so the tack welding must be performed so that the change in the torch measurement distance is sufficiently smaller than the plate thickness of the steel member 14. However, this does not apply if the influence of the tack welding can be ignored or if tack welding is not performed.

[0034] In this embodiment, fillet welding of steel members 13 and 15 with their main surfaces overlapping each other is shown, but the shape of the welded joint to which the invention is applicable is not limited to this. For example, it can be applied to fillet welding of plates butted together in a T-shape, as long as the position of the weld line can be detected based on the change in distance.

[0035] Furthermore, the rail 3 is fixed to the workpiece 12 using the magnet 31, but the fixing means is not limited to the magnet 31.

[0036] Furthermore, although the rails 3 are fixed to the members to be welded 12 and the carriage 4 moves on the members to be welded 12, the present invention is not limited to this. For example, if the members to be welded 12 are covered (surrounded) on all sides of the weld line 12 and are not to be welded, the rails 3 may be provided at a position different from the members to be welded and the carriage 4 may move on the rails 3.

[0037] In addition, although the rail 3 is shown as a single piece in this embodiment, it may be divided into multiple pieces and connected according to the length of the welding line. Regarding the extension direction of the rail 3, although it is shown as a linear one-way in this embodiment, it may be a curved shape such as a curve, or a shape that bends in multiple stages. The welding line 12 is similarly not limited to a linear shape.

[0038] Furthermore, the distance measurement means is not limited to the laser distance meter 432a. Any other method can be appropriately selected as long as it can appropriately detect changes in distance. Furthermore, the direction of distance measurement is not limited to a direction approximately perpendicular to the workpieces to be welded, and other angles can be used as long as they do not impede the simplicity of the welding method or the welding equipment.

[0039] Furthermore, although the present embodiment is directed to a cargo box 11 mounted on a refuse compactor 1, it may also be mounted on other types of vehicles or may be a welded component in a field other than the vehicle field. [Explanation of symbols]

[0040] 1 garbage truck 11 Packing box 12 Welding Lines 13 Steel parts (bottom) 14 Steel parts (top) 2 Automatic welding equipment 3 Rail 301 Guide part 302 Pedestal 303 Magnet 4 carts 41 Control Unit 42 Arm 421 Joint 422 Arm drive unit 423 Arm movement part 43 Torch section 431 Welding Torch 432 Distance measurement unit 432a Laser Rangefinder 433 Shade 434 Copying Mechanism 435a Position adjustment mechanism 435b Position adjustment mechanism 50 Laura 51 Roller drive unit 103 Laser irradiation position

Claims

1. In an automatic welding method using a welding machine that performs fillet welding while moving a welding torch along the weld line, The welding machine advances in a direction oblique to the weld line, Measure a torch measurement distance, which is the distance from the welding torch to the workpiece; When the torch measurement distance changes, the welding torch is moved in a first orthogonal direction that is substantially orthogonal to the direction of travel of the welding machine and in a second orthogonal direction that is substantially orthogonal to the measurement direction of the torch measurement distance and different from the first orthogonal direction. An automatic welding method characterized by:

2. When the welding machine advances in a travel direction, the welding torch is moved in the first orthogonal direction and the second orthogonal direction so as to maintain the magnitude of the torch measurement distance.

2. The automatic welding method according to claim 1.

3. The workpieces are two stacked steel plates, The welding torch is extended when the measured torch distance changes from the distance from the welding torch to the top surface of the upper one of the two steel plates to the distance from the welding torch to the top surface of the lower one of the two steel plates.

3. The automatic welding method according to claim 2.

4. An automatic welding device comprising an extension guide and a carriage having a welding torch that travels along the extension guide and welds members to be welded, the extension guide extends in a direction inclined with respect to the weld line of the workpieces to be welded, The carriage includes a distance measurement unit that measures a torch-measured distance between the welding torch and the workpiece, a distance determination unit that determines whether the measured distance matches a predetermined distance based on the measurement data of the distance measurement unit, and a torch movement unit that can move the welding torch based on the distance determination unit, a movement direction of the welding torch of the torch movement unit is set to a first orthogonal direction that is substantially orthogonal to the extension direction of the extension guide and a second orthogonal direction that is substantially orthogonal to the measurement direction of the distance measurement unit and different from the first orthogonal direction, When the carriage moves, the torch moving unit moves the welding torch based on the determination of the distance determining unit, thereby controlling the torch measurement distance so that the predetermined distance can be maintained. An automatic welding device characterized by:

5. The distance measurement unit is provided on the front side of the welding torch in the traveling direction of the carriage.

5. The automatic welding apparatus according to claim 4.

6. The carriage is provided with a position adjustment mechanism that can adjust the positions of the welding torch and the distance measurement unit.

6. The automatic welding apparatus according to claim 4 or 5.

7. The extension guide is detachable by a magnet, and a plurality of the extension guides can be connected in accordance with the length of the welding line.

7. The automatic welding apparatus according to claim 4, wherein the welding is performed by a welding machine.

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