JP4981513B2 - Welding method and welding equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a welding method and welding equipment for more rapidly and more accurately detecting a weld line. <P>SOLUTION: An automatic welding equipment 1 highly accurately specifies the position coordinate of the weld line 13c in respective positions and creates the actual trajectory information of a welding torch 2 by performing touch sensing in three or more places in a plurality of respective positions (position y<SB>1</SB>, y<SB>2</SB>, ... y<SB>n</SB>) along the weld line. At that time, the position coordinate of the weld line 13c is highly accurately specified by performing touch sensing in the minimum places, it is made possible to perform the detection of the actual weld line more rapidly as a result. Further, since the touch sensing is performed by making a shielding nozzle 3 touch a workpiece (actual workpiece) 13, the position detection is highly accurately performed. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a method and apparatus for automatically welding a welding torch along a weld line of a member to be welded (hereinafter, “work”).

A position of a welding wire (hereinafter simply referred to as “wire”) is set in advance with respect to the workpiece welding line, and the wire is automatically welded along the welding line based on the preset wire position. In order to perform welding accurately, the wire moving during welding needs to follow the weld line accurately. In order for the wire to follow the weld line accurately, the welding torch must be accurately positioned relative to the weld line at the position where welding is to begin.
When performing automatic welding, a welding line is set in advance for the workpiece. This weld line is referred to as a “reference weld line”. The welding torch (or wire) will move along the reference weld line. However, in the welding work on site, the welding line of the workpiece that is actually set (hereinafter, “actual welding line”) may be displaced from the reference welding line. This makes it impossible to perform accurate welding work automatically.
Therefore, various techniques have been proposed for detecting a deviation between the reference weld line and the actual weld line before starting welding and correcting the weld line based on the deviation amount.

  For example, in Patent Document 1, a rough position of a workpiece is detected by a touch sensor, the position of the camera is corrected according to the rough position of the workpiece detected by the touch sensor, and the camera is corrected at the corrected position. Image the welded part of the workpiece. In this case, since the camera can image the welded part of the workpiece at the corrected position, the welded part can be sufficiently enlarged and imaged. Therefore, by accurately calculating the position of the welded part of the workpiece and controlling the position of the wire based on the calculated position of the welded part, the positioning accuracy of the wire with respect to the welded part of the workpiece can be improved.

  In Patent Document 1, since a touch sensor is provided separately from a wire and a camera is provided, the device configuration is complicated and expensive. On the other hand, a technique is known in which a wire has a function of a touch sensor, and a deviation amount between a reference weld line and an actual weld line is detected using the wire (for example, Patent Document 2 and Patent Document 3). . When the wire has a function of a touch sensor, a detection voltage is applied to the wire, and when the wire comes into contact with the workpiece, a current flows through the workpiece, so that the voltage is lowered and the contact can be detected. Alternatively, the contact can be detected by detecting the current flowing through the workpiece.

FIG. 10 is a diagram for explaining the principle of detecting the shift amount between the reference weld line and the actual weld line by the touch sensor 100 in the fillet joint.
As shown in FIG. 10 , the reference work model 101 is indicated by a dotted line. The reference workpiece model 101 is preset for teaching, and the plate 101a and the plate 101b are orthogonal to each other to form a fillet joint. This intersection is indicated by reference weld line 103. The actual work 102 that is actually set is indicated by a solid line. In the actual workpiece 102, the plate 102a and the plate 102b are orthogonal to each other to form a fillet joint. This intersection is indicated by the actual weld line 104.

With respect to the reference work model 101, the initial position Ps of the touch sensor 100 is set by teaching. The touch sensor 100 includes a wire 100a that functions as a stylus. The touch sensor 100 is disposed so that the tip of the wire 100a coincides with the initial position Ps. The sensing described below is performed with the protruding length of the wire 100a being constant.
When the touch sensor 100 is moved from the initial position Ps of the touch sensor 100 toward the plate 101a along the x-axis, a wire 100a (hereinafter sometimes simply referred to as the touch sensor 100) and the plate of the touch sensor 100 The position at which 101a virtually contacts is set as a position coordinate P _101a . Further, when the touch sensor 100 is moved from the initial position Ps of the touch sensor 100 toward the plate 101b along the z-axis, a position where the wire 100a and the plate 101b virtually contact with each other is set as a position coordinate _P101b. To do.

The touch sensor 100 is moved from the initial position Ps toward the plate 102a along the x axis. The position coordinates P _102a where the wire 100a and the plate 102a are in contact with each other and the wire 100a and the plate 102a are in contact is detected. After detecting the position coordinate P _{102a at} which the wire 100a contacts the plate 102a, the touch sensor 100 returns to the initial position Ps. Next, the touch sensor 100 is moved from the initial position Ps toward the plate 102b along the z-axis direction. The position coordinates P _102b where the wire 100a and the plate 102b are in contact with each other and the wire 100a and the plate 102b are in contact is detected.
Based on the preset position coordinates P _101a and the detected position coordinates P _102a , the amount of deviation Δx in the horizontal direction with respect to the actual work 102 relative to the reference work model 101, that is, the x-axis direction is obtained. Further, a deviation amount Δz in the direction perpendicular to the actual workpiece 102 with respect to the reference workpiece model 101, that is, the z-axis direction is obtained from the preset position coordinates P _101b and the detected position coordinates P _102b . Based on the obtained Δx and Δz, the reference weld line 103 of the reference workpiece model 101 can be corrected in accordance with the actual weld line 104 of the actual workpiece 102.

JP 2003-33874 A JP-A-6-55269 JP 2001-225288 A

However, in the conventional technology as described above, there is room for further improvement in that the actual weld line is detected more quickly and with higher accuracy. For example, in the example of FIG. 10 , the installation angle of the reference workpiece model 101 and the actual workpiece 102 is the same, but when the actual workpiece 102 is actually set, the actual workpiece 102 is inclined with respect to the reference workpiece model 101. There is. In such a case, in the above method, the position of the actual welding line 104 cannot be accurately specified, and the corrected reference welding line 103 remains shifted from the actual welding line 104. In addition, the plate 102a and the plate 102b of the actual work 102 are assumed to be orthogonal to each other. However, when the plate 102a and the plate 102b are actually set, the crossing angle may be shifted. Even in such a case, the position of the actual weld line 104 cannot be accurately specified by the above method.
The present invention has been made based on such a technical problem, and an object of the present invention is to provide a welding method and a welding apparatus that can detect a weld line more quickly and with higher accuracy.

The welding method of the present invention, which has been made to solve the above problems, is a track for operating a welding torch along a weld line of a fillet joint when a workpiece having a fillet joint is fillet welded. A step of creating information, and a step of welding the fillet by moving the welding torch along the weld line based on the created trajectory information. Then, in the step of creating the trajectory information, three or more locations by the touch sensor are provided on both sides of the fillet joint at the plurality of positions spaced from each other along the weld line with respect to the workpiece. The position coordinates of each part are acquired by performing touch sensing. Furthermore, the position coordinates of the weld line at each of a plurality of positions spaced from each other along the weld line are specified from the acquired position coordinates of each location, and the trajectory information is generated from the position coordinates of the specified weld line. To do.
Here, in the present invention, touch sensing is performed at three or more locations on both sides of the fillet joint weld line, and the three locations referred to here are one of the fillet joint weld lines. It is the total of the number of touch sensing locations on the side and the number of touch sensing locations on the other side.

According to such a method, by performing touch sensing at three or more locations on the actual workpiece, even when the actual workpiece is tilted, the welding line at each of a plurality of positions along the weld line is detected. The position coordinates can be specified accurately, and the trajectory information of the welding torch can be generated from the specified position coordinates. If the workpiece has a simple shape such that the flat plates are welded to the fillet, automatic welding can be performed by generating orbit information only by touch sensing of the actually set workpiece.
In the case of workpieces with complicated shapes, such as when the weld line is curved three-dimensionally, reference trajectory information for operating the welding torch when welding the workpiece fillet based on the workpiece design data Preferably, the method further comprises the step of creating In the step of creating the trajectory information, the positional deviation amount between the position coordinates of the identified welding line and the reference trajectory information is acquired, the reference trajectory information is corrected from the acquired positional deviation amount, and the workpiece is welded to the fillet In this step, the corrected reference trajectory information is used as trajectory information, and the welding torch is operated.

In the step of creating the trajectory information, by performing touch sensing at three or more locations by the touch sensor, the position coordinates of the weld line at each of a plurality of positions spaced apart from each other along the weld line are specified. The position coordinates of the line can be specified with high accuracy.
Here, the touch sensing is performed at three or more locations by the touch sensor. In the present invention, the following configuration is essential.

That is , at each of a plurality of positions spaced apart from each other along the weld line, touch sensing is performed at the touch location on one side and the touch location on the other side across the weld line of the fillet joint with respect to the workpiece. Performing the steps of calculating an intermediate position between the touch location on one side and the touch location on the other side, moving the touch sensor to the calculated intermediate location, and bringing the touch sensor closer to the weld line. Repeat several times . In this method, the touch sensor finally reaches a position facing the weld line. As a result, not only when the workpiece is tilted but also when the fillet joint angle is misaligned, the position coordinates of the weld line at each of a plurality of positions spaced apart from each other along the weld line are accurate. Can be specified.

By the way, in the above-described method, in MIG welding (Metal Inert Gas welding) or the like, the shield gas is discharged from the shield nozzle attached to the tip of the welding torch, and fillet welding is performed while the shield nozzle is in contact with the workpiece. It is effective when performing .

By the way, for example, as shown in FIG. 11A , when welding is performed while the shield nozzle 105 is in contact with the workpiece (fillet joint) 106, the amount of deviation of the actual workpiece 102 with respect to the reference workpiece model 101 as described above. The protruding length of the wire 100a is constant in the sensing process for obtaining. Then, it is assumed that the protruding length of the wire 100a at the time of welding is also made to coincide with the protruding length in the process of obtaining this deviation amount. In this case, there is no problem when the workpiece 106 having a constant joint angle is welded. However, when welding the workpiece 106 whose joint angle changes depending on the position on the weld line, a problem arises. That is, as shown in FIG. 11B , the work 106 and the shield nozzle 105 interfere with each other at a portion where the joint angle is small, and welding itself cannot be performed. Further, as shown in FIG. 11C, in the portion where the joint angle is large, the workpiece 106 and the shield nozzle 105 are separated from each other, and the shielding performance of the shielding gas cannot be ensured.

Conventionally, as shown in FIG. 10 , sensing is performed by providing the wire 100 a with a fixed protrusion amount with the function of a touch sensor. Therefore, as described above, interference or separation between the workpiece 106 and the shield nozzle 105 occurs. Therefore, the present inventor has conceived that the shield nozzle to be brought into contact with the workpiece has the function of a touch sensor and the amount of deviation of the shield nozzle is obtained. Since the shield nozzle and the actual workpiece come into contact with each other during sensing, it is possible to ensure contact between the shield nozzle and the actual workpiece in the process of performing welding along the torch trajectory information corrected based on this sensing. As a result, even a workpiece whose joint angle changes can be automatically welded while preventing interference or separation between the shield nozzle and the workpiece.

Based on such an idea, the present inventors have already proposed the following welding method (Japanese Patent Application No. 2007-44822). This method includes a step (a) of creating reference trajectory information of a welding torch at the time of welding based on design data of a workpiece having a fillet joint portion to be welded by gas shielded arc welding, and welding for the reference trajectory information. Step (b) of acquiring the amount of positional deviation of the torch by touch sensing to the workpiece actually set at the welding position, and correcting the reference trajectory information based on the positional deviation amount of the welding torch to create actual trajectory information A step (c) for performing welding, and a step (d) for performing welding by controlling the track of the welding torch based on the actual track information. Here, welding is performed while contacting a fillet joint portion with a shield nozzle that is attached to the tip of the welding torch and discharges a shielding gas during welding. This is for securing the shielding property by the shielding gas. Therefore, the reference trajectory information is created by welding while bringing the shield nozzle into contact with the workpiece, and the positional deviation amount of the welding torch is acquired by bringing the shield nozzle into contact with the workpiece. As a result, it is possible to perform welding while bringing the shield nozzle into contact with the workpiece based on the corrected actual trajectory information of the welding torch.
In such a welding method, the touch sensor of the touch sensor can be arranged on the shield nozzle at a position where the shield nozzle contacts the fillet joint during welding to perform touch sensing on the workpiece. Since the shield nozzle itself can contact and sense the workpiece, the actual track information of the welding torch obtained as a result ensures the contact between the shield nozzle and the workpiece.

  Moreover, even if sensing is performed by providing a function of a touch sensor to a simulated shield nozzle having the same shape as the shield nozzle, the positional deviation amount of the welding torch with respect to the workpiece actually set at the welding position is similarly acquired. be able to. Then, when welding is actually performed, a shield nozzle may be attached instead of the simulated body. This idea includes realizing the entire welding torch with the shield nozzle attached in place of a simulated body having a function as a touch sensor. That is, the displacement amount of the welding torch can be acquired by bringing the shield nozzle simulated body into contact with the workpiece instead of the shield shield nozzle.

As a result of further studies by the present inventors on the above technique, it has been found that the above technique has the following problems to be solved.
First, when sensing is performed using a simulated shield nozzle, there is a problem in ensuring accuracy with the shield nozzle used when actually performing welding. In other words, after sensing with the shield nozzle simulated body, when the shield nozzle simulated body is replaced with the shield nozzle, there is a possibility that a positional deviation may occur due to an attachment error or the like. Further, if deformation or the like occurs in the shield nozzle simulated body or the shield nozzle with use, this also leads to a positional shift when the actual shield nozzle is replaced. Furthermore, when the workpiece is large, the welding torch may be long. In a long welding torch, a shape change may occur due to an external force or the like with use. Therefore, it is necessary to maintain the accuracy of both the shield nozzle simulated body and the shield nozzle, and it takes time to manage the accuracy.
In addition, when the touch nozzle of the touch sensor is provided on the shield nozzle without using the shield nozzle simulated body, since the welding torch and the shield nozzle are formed of a conductive material, it is necessary to insulate them from the touch needle. . For this purpose, it is necessary to form an insulating layer between the stylus and the welding torch and shield nozzle. However, since the welding torch must be inserted into a narrow space in the fillet joint, welding is performed for insulation. It is not preferable that the torch or the shield nozzle is enlarged. However, sufficient insulation cannot be achieved if the thickness of the insulating layer is small.
Further, the stylus needs to be provided in a pair at a position symmetrical to the shield nozzle or the shield nozzle simulated body, but wiring for energizing each stylus is also required, and this is also the shield nozzle or the shield nozzle simulated body. Will lead to an increase in size. In addition, when the weld line is three-dimensionally curved, the position (angle) of the material to be welded on both sides of the fillet joint is relative to the center axis of the shield nozzle or the simulated shield nozzle. It depends on the position of. As a result, the touch angle of the workpiece with respect to the pair of styluses provided on the shield nozzle or the shield nozzle simulated body changes, and reliable touch sensing may not be performed. In order to cope with this, it is conceivable that the welding torch is rotated around its central axis and the work touch angle of the pair of styluses is always appropriate, but this complicates the control.
For the reasons described above, there is room for further improvement with respect to the method already proposed by the present inventors.

  Therefore, in the present invention, when a shield nozzle is used, the touch sensor detects a change in the voltage applied to the shield nozzle, a power supply that applies a voltage to the shield nozzle, a power supply that applies a voltage to the shield nozzle. And a controller for obtaining the position coordinates of the welding torch when a change in voltage is detected. That is, the shield nozzle itself functions as a touch sensor. This can solve the above problems.

The present invention relates to a welding torch for performing fillet welding of a workpiece having a fillet joint, a moving device for moving the welding torch, and a shield made of a conductive material that is provided on the welding torch and discharges a shielding gas during welding. The nozzle, the power source that applies the voltage to the shield nozzle, the change in the voltage applied to the shield nozzle is detected, and the position coordinates of the welding torch when the change in voltage is detected are obtained, and the obtained position coordinates A trajectory generator for generating trajectory information for operating the welding torch along the weld line of the fillet joint, and a torch operation controller for controlling the operation of the welding torch based on the trajectory information , The trajectory generator is connected to the workpiece at a plurality of positions spaced apart from each other along the weld line. Performing touch sensing at the location and the touch location on the other side, calculating an intermediate position between the touch location on one side and the touch location on the other side, and moving the touch sensor to the calculated intermediate location, Furthermore, by repeating the step of causing the touch sensor to approach the weld line a plurality of times, the position coordinates of the weld line at the position are specified, and the welding torch is used when welding the workpiece based on the workpiece design data. The reference trajectory information for operating is generated, the positional deviation amount of the specified position coordinates of the welding line with respect to the reference trajectory information is acquired, the reference trajectory information is corrected from the acquired positional deviation amount, and the torch operation control unit is The corrected reference trajectory information is used as trajectory information, the welding torch is operated, and the shield gas is discharged from the shield nozzle attached to the tip of the welding torch. As well as out, fillet weld while contacting the shield nozzle to workpiece may be a welding apparatus which comprises carrying out.

  Here, the trajectory generating unit makes the shield nozzle contact with the workpiece at three or more positions on both sides of the fillet joint portion at each of a plurality of positions spaced apart from each other along the weld line. The position coordinates of each part are acquired, the position coordinates of the weld line at the position are specified from the acquired position coordinates of each part, and the trajectory information is generated from the position coordinates of the specified weld line. .

According to the present invention, with respect to an actual workpiece, by performing touch sensing at three or more locations at each of a plurality of positions along the weld line, the position coordinates of the weld line at each position are specified with high accuracy. The trajectory information of the welding torch can be generated from the specified position coordinates. At this time, since the position coordinates of the weld line can be specified with high accuracy by touch sensing to the minimum part, it becomes possible to detect the actual weld line more quickly.
In addition, by causing the shield nozzle itself to function as a touch sensor, it is possible to reliably ensure accuracy as compared with the case where the shield nozzle simulated body is used. Compared to the touch sensor stylus provided on the shield nozzle, the shield nozzle is not enlarged, and the shield nozzle is securely inserted into the narrow space of the fillet joint for touch sensing and welding. It becomes possible.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
FIG. 1 is a diagram showing a schematic configuration of an automatic welding apparatus 1 to which the present invention is applied. In addition, the automatic welding apparatus 1 can be widely applied to gas shield welding which discharges shield gas, such as MIG welding, TIG welding (Tungsten Inert Gas), and MAG welding (Metal Active Gas welding), from a shield nozzle.

As shown in FIG. 1, the automatic welding apparatus 1 includes a welding torch 2 that holds a welding wire 5 and a shield nozzle 3 that is detachably attached to the tip of the welding torch 2. Here, the shield nozzle 3 is assumed to function as a touch sensor for detecting the position of an actually set work 13 (hereinafter, this may be referred to as an actual work).
Since FIG. 1 shows a state in which the amount of positional deviation of the actual workpiece is detected, the welding wire 5 is retracted in the shield nozzle 3. During welding, the welding wire 5 protrudes from the shield nozzle 3 by a predetermined length. The automatic welding apparatus 1 is a so-called consumable electrode type welding apparatus, and the welding wire 5 is sequentially supplied from a wire supply apparatus (not shown) during welding.
The automatic welding apparatus 1 includes an articulated robot (moving device) 6 that holds a welding torch 2, a gas supply device 7 that supplies a shielding gas, and a robot controller (controller, torch operation control that drives and controls the articulated robot 6. Part) 8, a sensor power source (power source) 9 for applying a predetermined voltage to the shield nozzle 3, and a welding power source 10 for supplying power to the welding wire 5 during welding.
The automatic welding apparatus 1 further includes a CAD system 11 and an offline teaching data creation system (orbit generation unit) 12.

  The workpiece 13 to be welded by the automatic welding apparatus 1 includes a bottom plate 13a and a vertical plate 13b. In the workpiece 13 constituting the fillet joint, the joint angle formed by the bottom plate 13a and the vertical plate 13b is not constant and changes in the direction in which the weld line 13c continues as shown in FIG. Although the workpiece 13 shows an example in which the joint angle continuously decreases from the front in the figure, it goes without saying that the present invention is not limited to this and can be applied to a workpiece whose joint angle increases or decreases. In FIG. 1, the weld line 13c is linear, but the present invention can be applied even if the weld line 13c is curved in a three-dimensional shape.

The automatic welding apparatus 1 includes a shield nozzle 3 in order to effectively shield a welded part from the outside with an inert gas supplied from a gas supply apparatus 7 and passing through a welding torch 2. The shield nozzle 3 has a hollow cylindrical shape. When welding the workpiece 13, the outer peripheral edge of the tip of the shield nozzle 3 is brought into contact with the bottom plate 13a and the vertical plate 13b in the same manner as shown in FIG . This is to improve the shielding property. One point on the outer peripheral edge of the tip of the shield nozzle 3 contacts the bottom plate 13a, and one point on the outer peripheral edge of the shield nozzle 3 positioned symmetrically with respect to this point and the center contacts the vertical plate 13b. Welding is performed along a welding line 13c continuous in the longitudinal direction. At the time of welding, electric power is supplied from the welding power source 10 to the welding wire 5, and shield gas (inert gas) is supplied from the gas supply device 7. The robot controller 8 performs power supply control from the welding power supply 10 and shield gas supply control from the gas supply device 7.

The shield nozzle 3 is made of a conductive material, and has an outer shape that is bilaterally symmetric, such as a circle or a rectangle.
In order for this shield nozzle 3 to function as a touch sensor for detecting the position of the actual workpiece, current-carrying cables 4 a and 4 b for applying a voltage from the sensor power supply 9 to the shield nozzle 3 are connected to the shield nozzle 3. .
When the shield nozzle 3 comes into contact with the bottom plate 13a or the vertical plate 13b in a state where a voltage is applied from the sensor power supply 9 via the energization cables 4a and 4b, the voltage applied to the shield nozzle 3 is lowered. The robot controller 8 electrically connected to the sensor power supply 9 can detect that the shield nozzle 3 has contacted the bottom plate 13a or the vertical plate 13b by detecting this voltage drop. In the robot controller 8, the position (coordinates) of the shield nozzle 3 (welding torch 2) when the contact of the shield nozzle 3 with the bottom plate 13a or the vertical plate 13b is detected can be detected.
At this time, since the moving direction of the shield nozzle 3 is known, the robot controller 8 can recognize whether it is in contact with the bottom plate 13a or the vertical plate 13b. Since the outer dimensions of the shield nozzle 3 are also known, the position coordinates of the touch location of the shield nozzle 3 with respect to the bottom plate 13a or the vertical plate 13b can be detected from the position coordinates detected by the robot controller 8.

  The articulated robot 6 can have, for example, six independent joints. The articulated robot 6 includes a head 6a, and the head 6a holds the welding torch 2. By moving the head 6a, the welding torch 2 can be moved freely along the welding track. The welding torch 2 can be used as an automatic welding device 1 that automatically replaces the welding torch 2 by providing a separate device for the welding torch 2 with respect to the head 6a. These operations are controlled by a robot controller 8 electrically connected to the articulated robot 6.

  The robot controller 8 controls the operation of the articulated robot 6 as described above, in addition to controlling the operations of the sensor power supply 9 and the welding power supply 10. This operation control includes detection of the deviation amount of the actual workpiece with respect to the reference workpiece model (design model) and the operation of the welding torch 2 at the time of welding. An offline teaching data creation system 12 is connected to the robot controller 8, and a CAD system 11 is connected via the offline teaching data creation system 12. The robot controller 8 realizes the above-described operation control by executing predetermined processing in cooperation with the CPU, the memory, and the like of the computer device.

  The CAD system 11 creates reference trajectory information of the welding torch 2 for obtaining a more ideal welding state based on the CAD data (design data) of the workpiece 13 in cooperation with the offline teaching data creation system 12. The CAD system 11 includes an input unit including a mouse, a keyboard, and the like, a processing unit that performs a predetermined process based on a computer program installed in advance, a display unit that outputs (displays) a processing result and the like in the processing unit, And a data storage unit for storing various data such as CAD data of the workpiece 13 as a welding object. The offline teaching data creation system 12 includes a computer program for creating offline teaching data.

In order to create the reference trajectory information in the CAD system 11, first, the processing means virtually generates a three-dimensional model (work shape model) of the work 13 based on the CAD data of the work 13 read from the data storage unit. To create. This model is the reference work model. This model includes at least line segments indicating the shapes of the surfaces of the bottom plate 13a and the vertical plate 13b of the workpiece 13. The workpiece shape model is displayed on the display unit. The operator creates welding line position information that serves as a reference for generating the welding torch trajectory by using a mouse or the like of the input means while looking at the workpiece shape model of the workpiece 13 displayed on the display unit. Therefore, the weld line position information is created by teaching in cooperation with the CAD system 11 and the offline teaching data creation system 12. Next, the CAD system 11 and the off-line teaching data creation system 12 perform welding along the weld line specified by the weld line position information based on the dimension data and the weld line position information of the welding torch 2 stored in the data storage unit. The reference trajectory information for the torch 2 to perform welding is created.
That is, the reference trajectory information created in this way is information indicating the reference trajectory on the design data (reference work model).

  The offline teaching data creation system 12 moves the welding torch 2 along the welding line 13c of the workpiece 13 that is actually set, so that the reference trajectory information created as described above is used for the workpiece 13 that is actually set. The actual trajectory information (trajectory information) is created by correcting according to the position.

Next, a procedure for welding the bottom plate 13a and the vertical plate 13b of the workpiece 13 using the automatic welding apparatus 1 will be described. The following processing is performed by executing predetermined processing based on a program installed in advance by the CAD system 11 and the offline teaching data creation system 12 working together.

  When welding the workpiece 13 using the automatic welding apparatus 1, first, as described above, actual track information of the welding torch 2 is created before actual welding is performed. For this purpose, the steps of S101 (work shape model creation), S103 (weld line position information creation), S105 (torch reference trajectory information creation), S107 (touch sensing) and S109 (torch trajectory correction) in FIG. 2 are sequentially performed. Do. After the creation of the actual track information of the welding torch 2, the welding is performed while moving the welding torch 2 based on the track information.

"Step S101 (work shape model creation)"
As an initial procedure for creating the actual trajectory information of the welding torch 2, a three-dimensional workpiece shape model is created for the workpiece 13. As described above, the model is created based on the CAD data of the work 13 read from the data storage unit by the processing unit of the CAD system 11. This three-dimensional workpiece shape model becomes the reference workpiece model. This model is therefore specified by the three-dimensional coordinates of x, y and z.

“Step S103 (Create Welding Line Position Information)”
If the reference work model is created, the position information of the weld line on this model is created. As described above, the weld line position information is created in cooperation with the CAD system 11 and the offline teaching data creation system 12. This weld line position information is also specified by the three-dimensional coordinates of x, y, and z. The position information of the weld line includes position information of a plurality of points spaced from each other on the weld line on the reference workpiece model. Thereby, it is possible to specify a weld line (referred to as a reference weld line as appropriate) on the reference work model.

"Step S105 (Create torch reference trajectory information)"
The robot controller 8 acquires the welding line position information created by the CAD system 11 and the offline teaching data creation system 12 and the dimension data of the welding torch 2 stored in the data storage unit, and is specified by the welding line position information. Reference trajectory information for the welding torch 2 to perform welding along the weld line is created.

“Step S107 (Touch Sensing)”
Next, touch sensing is performed on the workpiece 13 actually set. The touch sensing step is the most characteristic part of the present invention and includes a plurality of steps as will be described in detail later. In touch sensing, the robot controller 8 controls the operation of the articulated robot 6 to detect the position of the work 13 by bringing the shield nozzle 3 functioning as a touch sensor into contact, and the amount of displacement of the work 13 relative to the reference work model. To get.

The touch sensing is performed by setting the work 13 at a predetermined welding position. The object on which the workpiece 13 is installed is not particularly limited as long as the workpiece 13 can be appropriately fixed at the time of touch sensing and welding. It can also be installed in a positioner that can change the posture of the workpiece 13.
Then, touch sensing is performed at each of a plurality of positions y ₁ , y ₂ , y ₃ ,..., _{N n} spaced from each other along the weld line 13 c of the workpiece 13, and the positions y ₁ , y ₂ , y _3, ..., in each of the _{y n,} to obtain information (intersection of the bottom plate 13a and the vertical plate 13b) position of the welding line 13c.

"Step S109 (torch trajectory correction)"
Position _{y 1, y 2, y 3} , ..., in each of the _{y n,} if the position information of the weld line 13c is determined, the robot controller 8 performs the torch trajectory correction using the position information. In the torch trajectory correction, the position of the reference weld line at each of the positions y ₁ , y ₂ , y ₃ ,..., _N included in the reference trajectory information created in step S105 and the weld line of the actual workpiece 13 are described. It can be obtained by calculating the amount of deviation from the position 13c and adding this amount of deviation to the reference trajectory information. For example, if the torch trajectory information at the position y ₁ is (x ₁ , z ₁ ) and the amount of displacement at the position y ₁ is (Δx ₁ , Δz ₁ ), (x ₁ + Δx ₁ , z ₁ + Δz ₁ ) is corrected. The actual trajectory information is obtained. The corrected actual trajectory information corresponds to the actual weld line 13c. This correction, position _{y 2,} y 3, ..., go to _{y n,} the correction of the torch track is finished.

The position in the direction along the weld line 13c of the workpiece 13 for obtaining the positional deviation amount is arbitrary, but if the positional deviation amount is obtained at more positions than necessary, the sensing time is wasted. Therefore, it is preferable to determine the position for sensing according to the curvature of the weld line 13c. FIG. 3 illustrates this. That is, the sensing position is specified so that the sensing interval is wide in the region where the curvature of the weld line 13c is large, and conversely, the sensing position is narrowed so that the sensing interval is narrow in the region where the curvature of the weld line 13c is small. Identify. By doing so, the number of sensing points can be reduced while ensuring the position accuracy. The curvature of the weld line 13c can be obtained from a reference weld line obtained by teaching. Then, the obtained real trajectory information (x ₁ + Δx ₁ , z ₁ + Δz ₁ ), (x ₂ + Δx ₂ , z ₂ + Δz ₂ ) (x ₃ + Δx ₃ , z ₃ + Δz ₃ ), (x ₄ + Δx ₄ , z _{Between 4} + Δz ₄ )..., Linear interpolation or circular interpolation may be performed according to the curvature.

  In the above description, the displacement amount of the weld line 13c has been described. However, since the position detection is performed by the shield nozzle 3, it can also be handled as a positional deviation amount of the shield nozzle 3 when welding the weld line 13c. Further, since the shield nozzle 3 is attached to the welding torch 2, it can be handled as a positional deviation amount of the welding torch 2.

"Step S111 (welding)"
Welding is performed while moving the welding torch 2 based on the actual track information. A series of welding controls are performed by the robot controller 8. Until the torch trajectory is corrected, the welding wire 5 is retracted into the shield nozzle 3, so that welding is performed after the welding wire 5 is projected by a predetermined length. The welding is performed while the shield nozzle 3 is in contact with the workpiece 13 and the shield gas is supplied into the shield nozzle 3.
In the case of the workpiece 13, there is one welding line 13c. However, in the case of the workpiece 13 having a plurality of welding lines 13c, steps S103 (welding line position information creation) to S111 (welding) are performed for each welding line 13c. The procedure is executed (steps S113 and S117).
If welding has been completed for all the weld lines 13c (step S113), if there is a workpiece 13 to be welded next (step S115), steps S101 (work shape model creation) to S111 are performed for the next workpiece 13. Execute the procedure up to (welding). Next, when there is no workpiece 13 to be welded (step S115), the series of processing ends.

Here, step S107 of the touch sensing will be described in detail. FIG. 4 is a diagram showing a detailed processing flow of touch sensing. To do touch sensing, first, the position _y 1 direction along the weld line 13c of the workpiece _{13, y 2, y 3,} ..., in each of the _{y n,} in performing touch sensing, a primary initial The touch sensor positions (hereinafter referred to as initial positions) P ₁ , P ₂ , P ₃ ,..., P _n are set. For example, as shown in FIG. 5, the initial position P ₁ is the position y ₁ in the direction along the weld line 13 c of the workpiece 13. The initial position P _1, the operator sets the teaching. However, setting of the initial position P ₁ is not limited to the teaching may be automatically set by a method such as providing a reference orbit information a predetermined offset value. Incidentally, when setting up the initial position P _1, it is needless to say that the touch sensor and the workpiece 13 is performed so as not to interfere.

Thereafter, first, touch sensing at the position y ₁ is performed.
"Step S201 (move the touch sensor initial position _{P 1)"}
As shown in FIG. 5, the touch sensor is moved to the initial position P ₁ at the position y ₁ in the direction along the weld line 13 c of the workpiece 13. The touch sensor here refers to a shield nozzle 3 which is energized from the sensor power 9, the center of the shield nozzle 3 is moved to coincide with the initial position P _1. In addition, although the shield nozzle 3 is attached to the welding torch 2, only the shield nozzle 3 is described in FIGS.
In FIG. 5, a work (actual work) 13 is depicted in a different posture from the installation state of FIG. Further, FIG. 5 shows a cross section of the workpiece 13 in position _{y 1.} Furthermore, in FIG. 5, the three-dimensional x, y, and z axial directions are defined as shown by arrows. Therefore, the y-axis is along the longitudinal direction of the workpiece 13. As shown in FIG. 5, the workpiece (actual workpiece) 13 is installed so as to be shifted from the reference workpiece model 13 ′.

"Step S202 (contact touch sensor bottom plate 13a)"
The shield nozzle 3 of the initial position P _1, as shown in FIG. 6, into contact with the bottom plate 13a is moved in the right direction in FIG. Movement amount x _R of the shield nozzle 3 from the initial position P ₁ until it is detected that in contact with the bottom plate 13a is obtained. The movement of the shield nozzle 3 is performed in parallel with the x axis. Robot controller 8 obtains the amount of movement _{x R.}
"Step S203 (contact touch sensor vertical plate 13b)"
When the move amount x _R is determined, then, until it contacts the vertical plate 13b, as shown in FIG. 7, to move the shield nozzle 3 to the left in FIG. By detecting that it has contact with the vertical plate 13b, moving distance x _L of the shield nozzle 3 from the initial position P ₁ until it contacts the vertical plate 13b is obtained. Also in this case, the movement of the shield nozzle 3 is performed in parallel with the x axis. Robot controller 8 obtains the amount of movement _{x L.}
“Step S204 (Calculate the center position coordinate P _c1 between the bottom plate 13a and the vertical plate 13b)”
If the movement amount _{x R} and the movement amount _{x L} have been determined, the robot controller 8 performs arithmetic processing of _{(x R + x L) /} 2 ( Fig. 8). Center position coordinate P _c1 obtained by this calculation processing, the center between the bottom plate 13a and the vertical plate 13b. The central position coordinate P _c1 exists on a line passing through the initial position P ₁ and parallel to the x axis.

“Step S205 (Move to touch sensor center position, descend)”
When the center position coordinate P _c1 between the bottom plate 13a and the vertical plate 13b is obtained, the shield nozzle 3 is moved so that the center of the shield nozzle 3 coincides with the center position coordinate P _c1 as shown in FIG.
If the shield nozzle 3 has moved to the center position coordinate P _c1 , this time the shield nozzle 3 is lowered in parallel with the z-axis direction. Then, as shown in FIG. 9, the shield nozzle 3 comes into contact with the bottom plate 13a and the vertical plate 13b. Therefore, the position coordinate P _w1 when the shield nozzle 3 contacts the bottom plate 13a and the vertical plate 13b is acquired.

At this time, when the shape of the workpiece 13 is a complicated three-dimensional shape, or when the workpiece 13 is installed inclined with respect to the reference workpiece model 13 ′, the shield nozzle 3 is made parallel to the z-axis direction. Even if it is lowered, the shield nozzle 3 may not contact the bottom plate 13a and the vertical plate 13b. Therefore, depending on the shape of the workpiece 13, the shield nozzle 3 is moved to the center position coordinate P _c1 , and then the shield nozzle 3 is moved by a predetermined dimension parallel to the z-axis direction to approach the weld line 13c (step S206). , S207). The moving dimension at this time is kept down to a position where the shield nozzle 3 does not contact the bottom plate 13a and the vertical plate 13b.
At that position, the above steps S202, S203, and S204 are repeated until the shield nozzle 3 comes into contact with the bottom plate 13a and the vertical plate 13b. Then, to acquire the position coordinates _{P w1} when the shield nozzle 3 is in contact with the bottom plate 13a and vertical plate 13b.

Here, from the trajectory information of the welding torch 2 created in step S105 of FIG. 2, the position coordinate P ′ _w1 where the shield nozzle 3 contacts the bottom plate 13′a and the vertical plate 13′b of the reference work model 13 ′ is obtained. Can be calculated. Therefore, as shown in FIG. 9, the positional deviation amount (Δx ₁ , Δz ₁ ) of the work (actual work) 13 with respect to the reference work model 13 ′ is obtained by comparing the position coordinates P _w1 and the position coordinates P ′ _w1. (Step S208).

Thus, the calculation of the positional deviation amount of the workpiece 13 in position y ₁ in the direction along the weld line 13c of the workpiece 13 is completed. If it is necessary to calculate the amount of displacement of the workpiece 13 at other positions (positions y ₂ , y ₃ ,..., Y _n ) in the direction along the weld line 13 c of the workpiece 13, the shield nozzle 3 is connected to the workpiece 13. Are moved in the direction along the welding line 13c and are positioned at other positions (positions y ₂ , y ₃ ,..., Y _n ) (steps S209 and S210). Then, the process returns to step S201, and the amount of positional deviation similar to the above is calculated. If the calculation of the positional deviation amount of the workpiece 13 has been completed at other positions in the direction along all the required weld lines 13c, the touch sensing step S107 is completed.

The automatic welding apparatus 1 according to the present embodiment can automatically calculate the amount of displacement of the workpiece 13 by bringing the shield nozzle 3 into contact with the workpiece (actual workpiece) 13. Therefore, even when the automatic welding apparatus 1 performs welding while bringing the shield nozzle 3 into contact with the workpiece 13, the shield nozzle 3 does not interfere with the workpiece 13 or the shield nozzle 3 is not separated from the workpiece 13 in the welding process. . Further, since the shield nozzle 3 itself functions as a touch sensor, the accuracy can be ensured more reliably than when a shield nozzle simulated body is used. In addition, the shield nozzle 3 is not increased in size compared with the case where the touch nozzle of the touch sensor is provided on the shield nozzle 3, and the shield nozzle 3 is securely inserted into the narrow space of the fillet joint portion to perform touch sensing. It becomes possible to perform welding.
At this time, when the shape of the workpiece 13 is a complicated three-dimensional shape, or when the workpiece 13 is installed to be inclined with respect to the reference workpiece model 13 ′, a plurality of pieces along the weld line 13c are provided. By performing touch sensing at three or more locations in each of the positions (positions y ₁ , y ₂ ,..., Y _n ), the position coordinates of the weld line 13c at each position can be identified with high accuracy and identified. The actual trajectory information of the welding torch 2 can be generated from the obtained position coordinates. At this time, since the position coordinates of the welding line 13c can be specified with high accuracy by touch sensing to the minimum part, the actual welding line can be detected more quickly.

In the above embodiment, each method for generating actual trajectory information as shown in FIGS . 4 to 9 is not limited to the case where the shield nozzle 3 itself functions as a touch sensor. The present invention can also be applied to a case where a stylus for a touch sensor is provided, or a shield nozzle simulation body dedicated to touch sensing is provided instead of the shield nozzle 3.
In addition to this, as long as it does not depart from the gist of the present invention, the configuration described in the above embodiment can be selected or changed to another configuration as appropriate.

It is a figure which shows schematic structure of the automatic welding apparatus in this Embodiment. It is a flowchart which shows the welding procedure in the automatic welding apparatus by this Embodiment. It is a figure explaining the method of specifying a sensing position. It is a flowchart which shows the procedure which detects the positional offset amount of a real workpiece | work with a touch sensor. It is a figure explaining the principle which detects the amount of position shift of an actual work with a touch sensor, and is a figure showing the state where the touch sensor was arranged in the initial position. It is a figure which shows the state which the touch sensor contacted one board same as the above. It is a figure which shows the state which the touch sensor contacted the other board same as the above. It is a figure which shows the state which has arrange | positioned the touch sensor in the center between both boards similarly. It is a figure which shows the state which the touch sensor contacted both the plates similarly. It is a figure explaining the principle which detects the deviation | shift amount of a reference | standard weld line and an actual weld line with a touch sensor in a fillet joint. It is a figure which shows that a shield nozzle interferes with a workpiece | work or leaves | separates by the workpiece | work from which a joint angle changes.

DESCRIPTION OF SYMBOLS 1 ... Automatic welding apparatus, 2 ... Welding torch, 3 ... Shield nozzle, 5 ... Welding wire, 6 ... Articulated robot (movement apparatus), 7 ... Gas supply apparatus, 8 ... Robot controller (controller, torch operation control part), DESCRIPTION OF SYMBOLS 9 ... Power supply for sensors (power supply), 10 ... Welding power supply, 11 ... CAD system, 12 ... Offline teaching data creation system (trajectory generation part), 13 ... Work, 13 '... Standard work model, 13a ... Bottom plate, 13b ... Vertical Plate, 13c ... Welding line

Claims (3)

Creating trajectory information for operating a welding torch along the weld line of the fillet joint when a workpiece having a fillet joint is welded;
Based on the workpiece design data, creating reference trajectory information for operating the welding torch when fillet welding the workpiece;
Operating the welding torch along the weld line based on the created trajectory information to weld the workpiece fillet,
In the step of creating the trajectory information, at each of a plurality of positions spaced apart from each other along the weld line, a touch location on one side of the fillet joint portion sandwiching the weld line with respect to the workpiece And performing touch sensing at the touch location on the other side to calculate an intermediate position between the touch location on the one side and the touch location on the other side, and the touch sensor at the calculated intermediate position. Moving the touch sensor closer to the weld line, and repeating a plurality of times to identify the position coordinates of the weld line at the position,
Obtaining a positional deviation amount relative to the reference trajectory information of the position coordinates of the identified welding line, correcting the reference trajectory information from the obtained positional deviation amount,
In the step of fillet welding the workpiece, the corrected reference trajectory information is used as the trajectory information, the welding torch is operated,
The fillet welding is performed by discharging a shield gas from a shield nozzle attached to the tip of the welding torch and making the shield nozzle contact the workpiece. The touch sensor is
The shield nozzle formed from a conductive material;
A power supply for applying a voltage to the shield nozzle;
A controller that detects a change in voltage applied to the shield nozzle and obtains a position coordinate of the welding torch when a change in voltage is detected;
The welding method according to claim 1 , comprising: A welding apparatus for carrying out the welding method according to claim 1 or 2,
A welding torch for performing fillet welding of a workpiece having a fillet joint,
A moving device for moving the welding torch;
A shield nozzle that is provided on the welding torch and discharges a shielding gas during welding, and is made of a conductive material;
A power supply for applying a voltage to the shield nozzle;
A change in voltage applied to the shield nozzle is detected, and a position coordinate of the welding torch when the voltage change is detected is obtained, and the welding torch is attached to the fillet joint based on the acquired position coordinate. A trajectory generator for generating trajectory information for operation along the weld line of the part,
A torch operation control unit that controls the operation of the welding torch based on the trajectory information ,
The trajectory generator is located on one side of the fillet joint with respect to the workpiece at each of a plurality of positions spaced from each other along the weld line. Performing touch sensing at the touch location and the touch location on the other side to calculate an intermediate position between the touch location on the one side and the touch location on the other side, and the touch at the calculated intermediate location The position of the weld line at the position is specified by repeating a plurality of times by moving the sensor and further causing the touch sensor to approach the weld line, and
Based on the design data of the workpiece, the reference trajectory information for operating the welding torch when the workpiece is fillet welded is generated, and the positional deviation of the specified position coordinates of the welding line with respect to the reference trajectory information Acquiring the amount, correcting the reference trajectory information from the acquired amount of displacement,
The torch operation control unit uses the corrected reference trajectory information as the trajectory information, operates the welding torch, discharges a shield gas from a shield nozzle attached to a tip of the welding torch, and controls the shield nozzle. Fillet welding is performed while contacting the workpiece .

Images