JP6705173B2 - Welding method and welding equipment - Google Patents

Description

The present invention relates to a welding method and a welding apparatus, and more particularly to a welding method and a welding apparatus capable of automatically performing butt welding.

When welding a large number of objects of the same type, a method of automating the welding using a robot may be used. There may be an error in the position of the part to be welded for each individual object, but in order to detect the error and perform welding at an appropriate position for each individual, use a laser sensor etc. A method of investigating the shape of a target object and determining the position where welding should be performed based on the information is known. For example, in Patent Document 1, an interpolation point calculation means for calculating a planned interpolation point for moving a work tool such as a welding torch attached to a robot by using a preset teaching trajectory and moving speed as inputs, and a work tool A correction means for calculating a correction interpolation point for correcting the planned interpolation point based on the input from a sensor such as a scanning laser sensor that is mounted and recognizes the shape of the object, and the work tool is sequentially moved to the correction interpolation point. There is disclosed a robot control device including a driving unit for driving the robot control unit.

JP, 2011-62763, A

As in Patent Document 1, a laser sensor and a welding torch are attached to a robot, information on a work shape obtained by a laser sensor that moves prior to the welding torch is processed in real time to move the welding torch. When determining the trajectory to be used, it is necessary to perform the measurement with the laser sensor, the trajectory of the welding torch based on the measurement results, and the execution of welding all at the same time, which complicates the configuration of the calculation/control unit. Cheap. Specifically, the speed at which the shape is measured by the sensor, the measurement result is output, and the calculation for determining the trajectory is performed generally does not match the welding speed in the welding torch. Therefore, before and after the point where the welding speed is changed during welding, a free running region in which any of measurement, calculation, and welding is temporarily stopped easily occurs. Moreover, since the measurement and the calculation are performed in real time, if the calculation of the trajectory by the calculation is performed with high accuracy, the configuration of the calculation/control unit including software becomes complicated. The memory capacity of the arithmetic unit also becomes large. In particular, if there is an irregular shape such as a temporary welding mark at the part to be measured in advance by the sensor, ignoring the structure or considering the structure and trying to clearly determine the trajectory of the welding torch However, the accuracy of measurement and calculation tends to decrease, and when trying to compensate for the decrease, the calculation/control unit becomes complicated. Also, when welding is interrupted due to arcing of the welding torch, it is difficult to restart welding from the middle, and if this is made possible, a complicated calculation/control unit is also required. Becomes

Further, as a structural problem, the positional relationship between the sensor and the welding torch is limited because the measurement of the shape of the object by the sensor needs to precede the welding. That is, it is necessary to install the sensors side by side in front of the welding torch, and it is difficult to protect the sensors from spatter and fumes generated during welding.

The problem to be solved by the present invention is to provide a welding method capable of automatically performing butt welding at a position corresponding to the structure of an actual object by using a device having a simple structure, and a welding device such as this. To provide.

In order to solve the above-mentioned problems, a welding method according to the present invention is a welding method for performing butt welding on a linear butt portion of an object, and an exercise device capable of moving to designated coordinates in a space, A welding torch attached to the exercise device, and an optical sensor attached to the exercise device with a positional relationship fixed to the welding torch and capable of measuring a distance to an object in a linearly set measurement range. For each of a plurality of expected sensing points set on the abutting portion, an exercise device is used so that the measurement area intersects the line of the abutting portion including the sensing point. Sensing step of arranging the optical sensor to measure the distance to the object in the measurement area and recognizing the position where the abutting portion actually exists as a detection point based on the measurement result. And a welding process of moving the welding torch along a target line that linearly connects a plurality of detection points recognized by the sensing process using the exercise device, and performing welding on the target line. This is executed in this order.

Here, it is preferable that the abutting portion is linear.

It is preferable that the optical sensor uses laser light having a linear beam shape to simultaneously perform measurement in the entire measurement region.

The optical sensor and the welding torch may be attached to the exercise device so as to protrude in mutually opposite directions.

It is preferable to set three or more sensing points and set welding conditions in each of the plurality of sections of the target line that connects two adjacent detection points.

A welding device according to the present invention includes an exercise device capable of moving to designated coordinates in space, a welding torch attached to the exercise device, and a positional relationship fixed to the welding torch attached to the exercise device. And an optical sensor capable of measuring a distance to an object in a linearly set measurement area, and performing the welding method as described above.

In the welding method according to the above invention, the distribution of the distance to the object is measured along the direction intersecting the abutting portion using the optical sensor at the sensing point set along the supposed abutting portion. In the distribution of the measured distances, it is possible to recognize the detection point corresponding to the actual abutting portion as the position where the concave structure is observed. By creating a target line by connecting the detected points that are recognized for multiple sensing points in a straight line, the actual butt position is displaced from the expected butt position due to factors such as manufacturing error of the object. Even if it does, the actual position of the butt portion can be recognized. Then, by moving the welding torch along the target line and performing welding on the target line, it is possible to perform accurate welding at the position where the actual butted portion exists. In this way, even if welding is automated by using a motion device such as a robot, it is possible to correctly perform welding on the abutting portion for each individual object. Furthermore, since the welding can be performed in a state in which there is no displacement with respect to the abutting portion, the penetration rate in welding can be easily increased.

Then, the optical sensor and the welding torch are fixed to each other in a fixed positional relationship with each other and attached to the exercise device, and after completing the sensing step of detecting the position where the actual butting portion is present by the optical sensor, based on the detection result. By performing actual welding, the control program can be simplified as compared with the case where sensing and welding are performed in real time. There is no need to use a large amount of memory. Even if the speed of the measurement by the optical sensor and the calculation based on the measurement result and the speed of the welding by the welding torch are different, or even if there is a problem unique to each process such as arc breakage of the welding torch, Since each process is performed independently, there is no particular problem in terms of compatibility between both processes. Even if there is an irregular structure such as a temporary welding mark, it is not necessary to perform arithmetic processing corresponding to it at high speed. Further, as long as the optical sensor and the welding torch are fixed to each other in a known positional relationship, the relationship between the mounting positions of the two is calculated by the coordinate values, so each specific mounting position is not particularly limited, The structural flexibility of the welding device used can be increased. By fixing the positional relationship between the optical sensor and the welding torch, especially by aligning the positions of the two along the supposed butted part of the object, the position of the butted part can be determined by sensing using the optical sensor. Fix the relationship between the positions of the detected detection points and the positions where welding is actually performed with the welding torch corresponding to those detection points, and perform accurate welding along the straight line connecting the detection points. Will be able to.

Here, when the abutting portion is linear, sensing points are discretely set on the assumed abutting portion, and the detection points recognized corresponding to the respective sensing points are linearly connected. Even with a simple method of obtaining the target line, the actual butted portion can be reproduced with high accuracy.

When the optical sensor uses laser light having a linear beam shape to simultaneously perform measurement in the entire measurement area, in the sensing process, the distance in the measurement area set across the abutting portion is set. And the actual position of the abutting portion based on the measurement result can be easily and accurately performed.

When the optical sensor and the welding torch are mounted on the motion device so as to project in mutually opposite directions, the unused optical sensor is performing the welding while the welding torch is performing the welding. Since it is facing away from the portion, it is possible to prevent spatter and fumes generated during welding from adhering to the optical sensor and affecting the optical sensor such as deterioration.

When three or more sensing points are set and welding conditions are set in each of a plurality of sections of a target line connecting two adjacent detection points, appropriate welding according to each part on the butted portion is set. It is possible to continuously weld each portion while applying the conditions. As described above, since it is not necessary to match the speed between the measurement by the optical sensor and the welding by the welding torch, the welding condition can be changed during the welding by simple control.

In the welding device according to the above invention, the control for automatically performing the welding can be executed by recognizing the actual position of the butted portion with a simple configuration.

It is a perspective view showing a welding device concerning one embodiment of the present invention, and an axle housing as an example of an object. It is a perspective view which shows the state which is performing the sensing process. It is a figure explaining a sensing process. (A) is a cross-sectional perspective view showing an enlarged butt portion, and (b) shows a measurement result for the butt portion. It is a figure explaining a welding process. It is a figure explaining control in each process, (a) shows a sensing process, (b) shows a welding process, and (c) shows a process of updating a sensing wire.

Hereinafter, a welding method and a welding apparatus according to one embodiment of the present invention will be described in detail with reference to the drawings.

[Configuration of welding equipment]
FIG. 1 schematically shows a welding device 1 according to an embodiment of the present invention.

The welding device 1 includes a robot 10 as an exercise device. The robot 10 has six drive axes, and the movement of each drive axis is driven by a servo motor (11 or the like). Thereby, the robot 10 can move the mounting surface 12 provided at the tip to the designated coordinates in the space. The robot 10 stores a command related to a motion (change in position and posture) by teaching, and sequentially calls the command, so that the mounting surface 12 can sequentially perform a predetermined motion automatically.

A welding torch 20 and an optical sensor 30 are fixed to a mounting surface 12 of the robot 10. The welding torch 20 is a known arc welding torch having a core wire 21 made of a welding material at its tip. The welding torch 20 has a base end fixed to one surface of the mounting surface 12 of the robot 10, and a tip protruding outward from the mounting surface 12.

The optical sensor 30 is a known shape measuring laser sensor. The optical sensor 30 measures the distance to the surface of the measurement object by irradiating the measurement object with a laser beam B having a linear beam shape from the tip and detecting reflected light. (See FIG. 2). The measurement of the distance is simultaneously performed in each part of the linear measurement area Rs on which the laser beam B strikes. The base end of the optical sensor 30 is fixed to the surface of the mounting surface 12 of the robot 10 opposite to the surface on which the welding torch 20 is fixed. The tip projects outward from the mounting surface 12. The protrusion direction of the optical sensor 30 is opposite to the protrusion direction of the welding torch 20 by about 180°, and the emission direction of the laser beam B is opposite to the protrusion direction of the core wire 21 of the welding torch 20.

The positional relationship between the welding torch 20 and the optical sensor 30 on the mounting surface 12 of the robot 10 (in what direction and how far apart on the mounting surface 12) is fixed, and the positional relationship is known. .. As a method for confirming the accuracy of the positional relationship between the two, for example, a jig for origin adjustment made of a plate in which a cross shape is engraved can be used. When the tip of the core wire 21 of the welding torch 20 is arranged directly above the intersection of the cross, the coordinate value of each drive axis of the robot 10 and the center of the laser beam B emitted from the optical sensor 30 coincide with the intersection of the cross. The coordinate value of each drive axis of the robot 10 at that time is compared, and the coordinate 0 (zero) is set based on the difference between both coordinate values. The positional relationship must be confirmed every time the welding torch 20 is replaced.

By fixing the positional relationship between the welding torch 20 and the optical sensor 30, for example, as shown in FIG. 5 for an example in which the axle housing 50 described in detail below is used as an object, sensing by using the optical sensor 30 is performed. The relationship between the positions of the detection points (D1 to D3) detected as the position of the abutting portion 54 and the positions where welding is actually performed by the welding torch 20 corresponding to these detection points (D1 to D3) is fixed, Welding can be performed accurately along a straight line connecting the detection points (D1 to D3). In particular, by making the welding torch 20 and the optical sensor 30 have the same position in the x direction (the assumed direction along the abutting portion 54), the target connecting the detection points (D1 to D3) detected by the optical sensor 30. It is possible to prevent a deviation from occurring between the inclination of the line Lt and the inclination of the straight line on which the welding torch 20 actually performs welding.

The welding apparatus 1 is further provided with a control unit (not shown) including a computer and the like. The control unit can control the power supply of the welding torch 20 and set the current and voltage during welding. In addition, the control unit controls the optical sensor 30 to measure the distance, receives the measurement result from the optical sensor 30, and can process and calculate the measurement result. Furthermore, the control unit can set or change a teaching program for instructing changes in the position and orientation of the robot 10 based on the measurement result of the optical sensor 30 and the like.

[Example of object]
In the embodiment of the present invention, the object to be welded (work) may be any object as long as it has a butt portion to be butt-welded. Below, the axle housing 50 as shown in FIG. 1 is treated as an example of an object.

The axle housing 50 is used for a rear axle of a large vehicle such as a truck, and accommodates an axle, a differential gear, and the like. As shown in FIG. 1, the axle housing 50 has a body portion 51 and a tubular portion 52 as a main body portion. The body portion 51 is formed by bending a steel plate into a semi-cylindrical shape (substantially U-shaped in cross section or substantially U-shaped in cross section) and bulged in a substantially annular shape, and accommodates a differential gear. A hollow cylindrical portion 52 through which the axle is inserted is formed at both ends of the body portion 51. The tubular portion 52 is basically in the shape of a rectangular tube, but the end portion thereof has a cylindrical shape so that the tube end can be attached in a later step. A substantially triangular triangular plate 53 is attached to the space formed between the body portion 51 and the tubular portion 52.

The body portion of the axle housing 50 is manufactured from two split members 60, 60. That is, two split members 60, 60 having a shape obtained by splitting the annular shape of the body portion 51 and the tubular shape of the tubular portion 52 into halves are manufactured, and their end edges 61, 61 are butted to form a linear shape. The main body is formed by performing butt welding on the butt portion 54 using the welding method according to the embodiment of the present invention. Further, the triangular plate 53 is arranged in a portion between the body portion 51 and the tubular portion 52, and the portion between the main body portion and the triangular plate 53 is welded.

Immediately before performing butt welding, the axle housing 50 is in a state where the two split members 60, 60 are butted against each other at the edges 61, 61 and pressed against each other, and are temporarily welded together. As a result of the tack welding, tack welding marks 55, 55 are formed on the abutting portion 54 so as to be left and right one by one in a dot shape. By the temporary welding, the two divided members 60, 60 are not separated from each other, and even if the external force pressing against each other is released, the state in which the butt portion 54 is formed by the end edges 61, 61 is maintained. It

The two divided members 60, 60 are manufactured through a step of removing the excess thickness of the peripheral portion by plasma cutting after press molding. Therefore, sagging (melting of the upper edge) due to the plasma arc at the time of cutting occurs at the edges 61, 61 that will form the abutting portion 54. As a result, as shown in FIG. 3A, the edges 61, 61 are formed with an inclination whose upper surface (outer surface) side is slightly shorter. Therefore, a valley-shaped concave structure is formed in the butting portion 54 where the two end edges 61, 61 are butted.

[Welding method]
Next, a welding method according to an embodiment of the present invention will be described. Here, the welding device 1 described above is used to weld the abutting portion 54 with the axle housing 50 as an object.

In the welding method according to the present embodiment, (1) sensing step and (2) welding step are performed in this order. The welding process is executed based on the information obtained in the sensing process. Hereinafter, each step will be described in detail. In the following, the longitudinal direction of the axle housing 50 is the x direction and the width direction is the y direction.

(1) Sensing Step FIG. 2 shows the welding device 1 and the axle housing 50 in a state where the sensing step is being executed. Although illustration is omitted, prior to the sensing step, the axle housing 50 is installed at a predetermined position on the work table by a fixing jig.

In the sensing process, the optical sensor 30 attached to the robot 10 is directed downward and is disposed above the surface of the axle housing 50. In this state, the robot 10 is driven by teaching so as to move the optical sensor 30 along a preset linear sensing line Ls (see FIG. 5A). The sensing line Ls is set as an assumed position of the butt portion. Here, the “assumed” position of the abutting portion 54 varies due to various factors such as manufacturing errors in the previous process such as plasma cutting, errors in the installation position on the workbench, and deviation of the origin position of the robot 10. It means the position where the abutting portion 54 is assumed to be present, assuming that there is no influence of the above and is in an ideal state as designed.

A plurality of sensing points (points P1 to P3 in the example of FIG. 2) are preset on the sensing line Ls, avoiding the positions where the temporary welding marks 55, 55 are formed. In the example of FIG. 2, generally, the point P1 is the position of the end portion 52a of the tubular portion 52, the point P2 is the boundary portion between the cylindrical portion and the rectangular tubular portion, and the point P3 is the end point of the linear abutting portion 54. It is set in the section. The robot 10 moves the optical sensor 30 from one end 52a of the axle housing 50 inward along the sensing line Ls, and at each sensing point passing at that time (P1→P2→P3), the optical sensor 30 is detected. Measures the distance to the surface of the axle housing 50. The robot 10 stops the movement of the optical sensor 30 as needed during the measurement.

When performing measurement at each of the sensing points P1 to P3, the laser beam B is positioned so that the linear measurement area Rs is substantially orthogonal to the sensing line Ls, and the sensing points P1 to P3 are located at substantially the center of the measurement area Rs. Arranged as you would. Further, the maximum range in which the position of the abutting portion 54 may deviate in the y direction from the assumed position due to variations due to various factors is included in the measurement range Rs, so that the optical sensor 30 and the axle housing 50 have a maximum range. The distance between them is defined.

FIG. 3B shows the result of measuring the distance by the optical sensor 30 with respect to the abutting portion 54 having a valley-shaped concave structure as shown in FIG. 3A. In the figure, the horizontal axis is the coordinate in the y direction, and the vertical axis is the distance from the optical sensor 30 to the surface of the axle housing 50. As shown, a downward convex peak structure is observed corresponding to the concave structure of the abutting portion 54. The y coordinate of the apex of this peak structure is recognized as the position of the detection point D corresponding to the valley bottom of the abutting portion 54.

FIG. 5A shows an example of the measurement result at the sensing points P1 to P3. Here, the detection point D1 detected by the measurement at the point P1 is on the sensing line Ls and coincides with the sensing point P1. On the other hand, the detection point D2 detected by the measurement at the point P2 is displaced from the sensing line Ls in the +y direction. Further, the detection point D3 detected by the measurement at the point P3 is further deviated from the sensing line Ls in the +y direction. When the target line Lt is created by connecting the detection points D1 and D2 and the detection points D2 and D3 with straight lines, the target line Lt has one straight line.

The obtained target line Lt indicates the position where the abutting portion 54 of the actual axle housing 50 exists. In the example of FIG. 5A, the actual position of the abutting portion 54 in the y direction represented by the target line Lt does not deviate from the expected position at the position of the sensing point P1, but is +x more than that. In the region on the side, while maintaining the linearity, it is skewed in the +y direction from the assumed position of the abutting portion. Such a deviation from the assumed abutting portion while maintaining the linearity is likely to occur in the plasma cutting process of the edges 61, 61 of the dividing members 60, 60 and the installation process on the workbench.

In the present embodiment, the optical sensor 30 having a linear beam shape is used to simultaneously measure the entire measurement range Rs, so that the measurement within the measurement range Rs at each of the sensing points P1 to P3 is performed for a short time. It is possible to do it accurately. However, the optical sensor 30 to be used is not limited to this as long as it can measure the distance in the entire linear measurement range Rs. For example, the optical sensor 30 having a spot-shaped beam shape is used. Alternatively, the beam spot may be scanned to sequentially measure the distance in the entire measurement range Rs.

(2) Welding Process FIG. 4 shows the welding device 1 and the axle housing 50 in a state where the welding process is being performed. The axle housing 50 is still installed at a predetermined position on the work table before the sensing process, and maintains the same coordinates as when the sensing process is being performed.

In the welding process, the mounting surface 12 of the robot 10 is oriented in the opposite direction to that in the sensing process, the welding torch 20 is directed downward, and is arranged above the surface of the axle housing 50. In this state, the robot 10 is driven so as to move the welding torch 20 along the target line Lt obtained in the sensing process. During the movement, the coordinates of the robot 10 are set in consideration of the positional relationship between the optical sensor 30 and the welding torch 20 on the mounting surface 12, which is a known parameter, in addition to the coordinates of the target line Lt.

During the movement by the robot 10, the welding torch 20 continuously performs welding on the target line Lt, that is, on the actual butting portion 54 detected in the sensing step, as shown in FIG. 5B. The welding conditions at this time are set as a condition A in a section connecting the detection points D1 and D2 and a condition B in a section connecting the detection points D2 and D3, respectively, and go from the detection points D1 to D3. During the continuous welding, the welding condition is changed at the detection point D2. Here, the welding conditions include parameters such as current, voltage, speed (moving speed of welding torch 20), and distance from welding torch 20 to the surface. In welding, the presence of the temporary welding marks 55, 55 is not particularly considered, and the temporary welding marks 55, 55 are also linearly welded under the same welding conditions as the front and rear portions.

In the present embodiment, the sensing line Ls and the target line Lt are set only in the abutting portions 54 of the end edges 61, 61 of the tubular portion 52, but the sensing line Ls is linear even up to the surface of the triangular plate 53. May be extended to set the sensing point. In this case, the target line Lt is set from the abutting portion 54 to the region above the triangular plate 53, and welding is performed.

(3) Other Steps In the present welding method, other steps may be appropriately performed before, after, or during the process as long as the sensing step and the welding step are performed in this order with the axle housing 50 fixed at the same position. ..

For example, the step of updating the sensing line Ls can be executed after the welding step. This is because when welding is automatically performed sequentially on a large number of axle housings 50 of the same type, as shown in FIG. It is reset as the sensing line Ls′ used in the sensing process of the individual. Thereby, in the subsequent individual sensing process, the distance is detected at the new sensing points P1′ to P3′ set along the new sensing line Ls′ instead of the previous sensing line Ls. become. The direction of the measurement area Rs is also set so as to be substantially orthogonal to the new sensing line Ls'. When manufacturing a large number of axle housings 50 in a lot, the deviation from the design value of the actual position of the abutting portion 54 represented by the target line Lt may be systematic, and in that case, Misalignment tends to be common between individuals in the same lot. Then, there is a high possibility that the target line Lt set for a certain individual based on the measurement in the sensing step will match the actual position of the abutting portion 54 in the subsequent and subsequent individuals. Therefore, by adopting such a target line Lt as a new sensing line Ls′, in the next and subsequent individuals, the position shift from the sensing line Ls′ to the target line, that is, the estimated position of the abutting portion is actually used. It is possible to reduce the displacement to the position of the butt portion 54 where welding is performed.

(4) Characteristics of Welding Method In the present welding method, the actual position of the abutting portion 54 is detected in the sensing process, and then the welding process is performed to perform welding accurately on the actual abutting portion 54. be able to. This prevents the welding bead from being displaced in the y direction with respect to the butting portion 54. Further, if welding is performed in a state where the position of the abutting portion 54 and the position of the welding torch are deviated, the local welding conditions change, and welding cannot be performed under the desired constant conditions. Particularly, in the butt welding of the axle housing 50, it is preferable to achieve a penetration rate of 100% or more from the viewpoint of ensuring the strength, but the position of the bottom of the concave structure of the butt portion 54 and the core wire 21 of the welding torch 20. If the position is displaced in the y direction, it is difficult to achieve such a high penetration rate. In the present welding method, since the bottom of the recessed structure of the butted portion 54 and the position of the core wire 21 of the welding torch 20 can be adjusted so as not to be displaced by performing the sensing process, it is possible to achieve a high penetration rate. You can

When manufacturing a large number of axle housings 50, even if the steps up to welding are similarly performed for each individual, due to various factors, the axle housings 50 fixed to the workbench for welding are performed. Inevitably, an error occurs in the position and direction of the abutting portion 54 at. Factors that cause such an error include positional deviation during press molding of the split members 60, 60 and cutting of excess thickness at the edges 61, 61, changes in manufacturing conditions due to lot changes, and during installation on a workbench. Examples include positional deviation and inclination. However, by performing the sensing process on each individual body of the axle housing 50 before the welding process and confirming the actual position of the abutting portion 54 in the individual body, variations in the position of the abutting portion 54 for each individual can be obtained. Therefore, it is possible to accurately weld the abutting portion 54 of each individual. Further, conventionally, in order to confirm whether welding can be performed under a predetermined condition, the butting portion 54 is visually observed from the inside of the hollow shape of the tubular portion 52 of the axle housing 50, and the penetration rate exceeds 100%. Sampling inspections such as inspecting whether the welding bead has reached the back side of the butted portion 54 or cutting the tubular portion 52 to confirm the welding bead in the cross section have been frequently performed, but in this welding method, The frequency of the sampling inspection can be reduced by performing the welding securely after detecting the position of the butting portion 54 for each individual. It should be noted that changes in the mounting position and angle of the core wire 21 in the welding torch 20 also cause the welding position to shift, but in the present embodiment, as described above, each time the core wire 21 is replaced with the optical sensor 30, By confirming the positional relationship, it is possible to prevent a deviation from occurring between the target line Lt set in the sensing process and the position where welding is actually performed by the welding torch 20.

Further, in the present welding method, the measurement by the optical sensor 30 and the welding by the welding torch 20 are not simultaneously performed in real time, but the sensing step is completed as an independent step, and then the welding step is performed based on the result. By carrying out the operation, the complicated program and the large-capacity memory required for executing both processes in real time are eliminated, and the structure of the welding apparatus 1, especially the structure of the control unit is simplified. It can be anything. In addition, since it is not necessary to match the execution speed and the like between the measurement by the optical sensor 30 and the welding by the welding torch 20, each process can be executed by a simple method suitable for each. For example, even if the welding conditions including the speed are changed, the welding without considering the existence of the temporary welding marks 55, 55, the interruption and the restart of the welding due to the arc breakage, etc. are performed, the measurement by the optical sensor 30 is not affected. Does not give.

Further, when the measurement by the optical sensor 30 and the welding by the welding torch 20 are performed in real time, it is required to mount the optical sensor 30 side by side in front of the welding torch 20, but when performing both steps independently. No particular restrictions are placed on the positions of the optical sensor 30 and the welding torch 20. By mounting the optical sensor 30 and the welding torch 20 on opposite sides of the mounting surface 12 as in the present embodiment, it is possible to prevent fume and spatter during welding from affecting the optical sensor 30.

When the sensing process and the welding process are independently performed as in the present embodiment, it is necessary to ensure the consistency between the two processes with respect to the position where the sensing and the welding are performed. In the present embodiment, the positional relationship between the optical sensor 30 and the welding torch 20 is fixed, the positional relationship is grasped, and then the sensing line Ls, the sensing points P1 to P3, and the target line set with the common coordinate system as a reference. By performing both the sensing process and the welding process according to Lt, the consistency of the positions in both processes is secured. In this embodiment, the coordinate system is based on the coordinates of the robot 10, but the coordinates are based on one of the sensing points (for example, the point P1) and a specific portion of the axle housing 50 (for example, the center of the body 51). An arbitrary coordinate system such as a coordinate based on, a coordinate based on the optical sensor 30 or the welding torch 20, and the like can be adopted.

In the present embodiment, in the sensing step, the distance is measured at the sensing points P1 to P3 set discretely, and the detection points D1 to D3 corresponding to the position of the abutting portion 54 are recognized. Then, the discrete detection points D1 to D3 are connected by a straight line to form the target line Lt, which is regarded as the position where the actual abutting portion 54 exists. In this way, the sensing process can be completed at high speed by discretely detecting the butting portions 54. Further, by setting the sensing points P1 to P3 while avoiding an irregular structure such as temporary welding marks 55, 55, the influence of such a structure is eliminated and the position of the abutting portion 54 is detected. You can As described above, in the manufacturing process of the axle housing 50, the position of the abutting portion 54 is likely to be displaced due to an error in plasma cutting or installation on a workbench, but the linearity of the abutting portion 54 is impaired. Almost no slippage occurs. Therefore, as shown in FIG. 5, the deviation of the actual butting portion 54 (target line Lt) based on the supposed butting portion (sensing line Ls) is detected while maintaining the linearity. Even with a simple method of setting the sensing points P1 to P3 discretely by the linearity of the matching section 54 and interpolating the discretely obtained detection points D1 to D3 with a straight line to create the target line Lt, The actual butting portion 54 can be reproduced with high accuracy.

However, even if the abutting portion 54 is not linear and is bent in the middle, it is ensured that the measurement area Rs of the optical sensor 30 intersects the abutting portion 54, and then the linear portion forming the abutting portion 54 is formed. By setting the distance between the sensing points to be sufficiently fine with respect to the length of the portion, the butted portion 54 having such a bend can be detected by the same method. In the illustrated example, the sensing point P2 is set at the boundary between the cylindrical portion and the rectangular tubular portion of the tubular portion 52. If the shape of the abutting portion 54 deviates from a straight line, it often occurs in a region where the shapes of the dividing members 60, 60 change, such as the point P2. Therefore, the sensing point is set in such a region. This makes it easier to deal with the deviation of the butting portion 54 from the straight line. Further, in such a region where the shape changes, the optimum welding condition often changes, and from the viewpoint of appropriately switching the welding condition for each section of the target line Lt, the condition A in FIG. As in B, it is preferable to set the sensing point in such an area. The actual number and spacing of sensing points may be appropriately determined according to the shape of the object. Naturally, it is not necessary to arrange the sensing points at equal intervals, and it is not necessary to change the welding conditions for each of the sections of the target line Lt.

Although the embodiments of the present invention have been described above in detail, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Welding device 10 Robot 12 Attachment surface 20 Welding torch 21 Core wire 30 Optical sensor 50 Axle housing 51 Body 52 Cylindrical part 53 Triangular plate 54 Butt part 55 Temporary welding mark 60 Dividing member 61 Edge B Laser beam D, D1-D3 Detection point Ls Sensing line Lt Target lines P1 to P3 Sensing point Rs Measurement area

Claims (7)

Formed as trough-like recessed structures against the edges of the two divided members is subject to one another, with respect to the linear butt portion, in the welding method of performing butt welding,
An exercise device capable of moving to designated coordinates in a space, a welding torch attached to the exercise device, a fixed positional relationship with respect to the welding torch, attached to the exercise device, and set linearly Using an optical sensor that can measure the distance to the object in the measurement area,
For each of a plurality of expected sensing points set on the abutting portion, the optical sensor using the exercise device so that the measurement area intersects the line of the abutting portion including the sensing point. After arranging, measuring the distance to the object in the measurement area, based on the measurement result, a sensing step of recognizing the position where the abutting portion actually exists as a detection point,
Using the exercise device, a welding process of moving the welding torch along a target line that linearly connects a plurality of detection points recognized by the sensing process, and performing welding on the target line, in this order. Welding method characterized by performing. The welding method according to claim 1, wherein the butt portion is linear. The welding method according to claim 1 or 2, wherein the optical sensor uses laser light having a linear beam shape to simultaneously perform measurement in the entire measurement region. The welding method according to any one of claims 1 to 3, wherein the optical sensor and the welding torch are attached to the exercise device so as to project in mutually opposite directions. 5. The welding condition is set in each of a plurality of sections of the target line formed by connecting two or more adjacent detection points by setting three or more sensing points. The welding method according to item 1. The object obtained by abutting the two divided members with each other at the edge has a cylindrical portion and a rectangular tubular portion, and the abutting portion has the cylindrical portion and the rectangular tubular portion. It is formed across the site,
The welding method according to any one of claims 1 to 5, wherein the measurement in the sensing step and the welding in the welding step are performed across the cylindrical portion and the rectangular tubular portion. .. An exercise device capable of moving to designated coordinates in a space, a welding torch attached to the exercise device, a fixed positional relationship with respect to the welding torch, attached to the exercise device, and set linearly An optical sensor capable of measuring a distance to an object in a measurement area, and performing the welding method according to any one of claims 1 to 6 .

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