JP2009006382A - Attitude control method of welding torch of arc welding robot, and control device of arc welding robot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an attitude control method of a welding torch of an arc welding robot and a control device of the arc welding robot capable of unifying the reinforcement height of a bead, and obtaining the bead appearance of high uniformity. <P>SOLUTION: The control device 10 of the arc welding robot acquires the shape of a bead formed by performing the welding by a welding torch 14 by an image pickup camera 25 supported by a manipulator M. The reinforcement height of the bead is calculated by a camera control device CCU based on the acquired data of the image pickup camera 25. The manipulator M is controlled so that, as the larger the reinforcement height is, the more the drag angle of the welding torch 14 is increased by a robot control device RC; and as the smaller the reinforcement height is, the more the drag angle of the welding torch is decreased. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a welding torch attitude control method for an arc welding robot and an arc welding robot control apparatus.

  In the arc welding robot system that realizes the laser sensor copying technique, a welding torch 50 and a laser sensor LS are provided at the free end of a manipulator M as shown in FIG. Then, the laser sensor control device LU performs image analysis based on the distance measurement data acquired by the laser sensor LS preceding the welding torch 50, and thereby the groove feature point and physical quantity (gap amount corresponding to the groove). The groove information including the groove angle, the groove area, etc.) is acquired, and the obtained feature points are connected to generate the three-dimensional trajectory of the welding torch 50.

  Here, in the obtained three-dimensional trajectory, the tangent vector is defined as a traveling direction vector. The laser sensor control device LU defines a feature line in the groove as a reference angle and gives a target relative angle with respect to the reference angle with respect to the groove information (that is, the feature point and the physical quantity). Together with the vector, the target posture of the welding torch 50 with respect to the groove is generated.

  For example, FIG. 9 shows groove information when image analysis is performed on the lap joint based on distance measurement data sampled by the laser sensor LS. In the case of a lap joint, as shown in FIG. 9, a point that is an end angle of an upper plate (not shown) is a feature point. In this case, it is possible to generate the target posture of the welding torch 50 with respect to the groove together with the traveling direction vector by setting the groove normal line through which the feature point passes as a reference angle and giving a target relative angle with respect to the reference angle. it can.

FIG. 10 shows an example in which the three-dimensional trajectory of the welding torch 50 is generated by connecting the characteristic points obtained for the lap joint.
By the way, only the position / posture of the feature point with respect to the groove coordinate system can be calculated only by the groove information based on the distance measurement data obtained from the laser sensor LS. Therefore, the robot controller RC transmits the current coordinates of the welding torch 50 in the robot coordinate system to the laser sensor controller LU.

  The laser sensor control device LU receives the current position in the robot coordinate system of the welding torch 50 received, the feature point coordinates acquired by image analysis, and the speed (velocity data) given in advance, so that the target position (in the robot coordinate system) That is, the target coordinates are calculated and returned to the robot controller RC.

In the robot controller RC, the interpolation point generated from the teaching data is replaced with the received target position (target coordinate), and copying is performed by operating the manipulator M.
Further, the laser sensor control device LU calculates groove information such as a gap amount and a groove area in real time in the process of obtaining the target position (target coordinates). Therefore, the laser sensor control device LU returns the groove information to the robot control device RC together with the return of the target position (target coordinates). For example, the laser sensor control device LU calculates the gap amount G for the fillet joint shown in FIG. 11A and the gap amount G and the groove area for the butt joint shown in FIG.

  By the way, in the adaptive welding function using the laser sensor LS, the robot controller RC refers to a preset adaptive welding condition table, and refers to a welding condition (for example, welding current or the like) commanded to the welding power source WPS according to the groove information. The welding voltage can be changed in real time. For example, Table 1 shows an example of an adaptive welding condition table that changes the welding current, which is one of the welding conditions, according to the gap amount as the groove information. In this example, the set current Is, which is a welding current, changes stepwise according to the gap amount. Table 2 shows another example of an adaptive welding condition table that changes the welding current in accordance with the gap amount. In this example, when the gap amount is 0.0 mm to 3.0 mm, the set current Is that is a welding current changes linearly.

  In both Tables 1 and 2, the current is set to be constant at the upper limit value when the gap amount is 3.0 mm or more. By setting an appropriate adaptive welding condition table by such a method and changing the welding conditions in real time according to the gap amount, a desired welding operation can be performed while filling the gap.

  By the way, even under the same welding conditions, there is a variation in the degree of welding that occurs depending on the heat input state of the workpiece and the degree of melting of the workpiece. For example, when the work piece is cold, it is difficult to input heat, and thus tends to be a convex bead B (see FIG. 12A). Conversely, when there is a lot of heat input to the workpiece, the surplus height tends to be low (see FIG. 12B). Although the adaptive welding function monitors the gap amount while welding, it cannot directly capture the change in conditions given by the heat input of the workpiece W.

As a result, even if the gap amount changes, welding while filling the gap is possible, but there is a problem that the surplus height is not necessarily uniform.
An object of the present invention is to provide a method for controlling the attitude of a welding torch of an arc welding robot and a control apparatus for the arc welding robot that can make the surplus height of the beads uniform and, as a result, obtain a highly uniform bead appearance. There is to do.

  In order to solve the above-mentioned problems, the invention described in claim 1 includes a measuring means for measuring a cross-sectional shape of a welded joint, a welding torch for welding the welded joint, and the measuring means together with the welding torch. A manipulator that moves along the taught path; first computing means for computing a cross-sectional shape of the welded joint based on measurement data of the measuring means; and a first position for computing a target position and welding conditions based on the cross-sectional shape. 2, in a posture control method of a welding torch of an arc welding robot that performs welding by controlling the manipulator based on the target position and the welding condition, the shape obtaining unit supported by the manipulator The shape of a bead formed by welding with a torch is acquired, and the extra height of the bead based on the acquisition data of the shape acquisition means It is calculated by the surplus height calculation means, and is controlled by the control means so that the advance angle of the welding torch is increased as the surplus height is higher and the advance angle of the welding torch is decreased as the surplus height is lower. The gist of the method is to control the attitude of the welding torch of the arc welding robot.

  The invention according to claim 2 is the welding torch according to claim 1, wherein the welding torch comprises a surplus height and a advance angle related variable corresponding to the surplus height, and the advance angle related variable increases as the surplus height increases. The bead appearance adjustment table set so as to decrease the advance angle of the welding torch as the surplus height is lower is stored in the storage means, and the control means is the surplus height calculation means. The advancing angle related variable corresponding to the extra height calculated by is read from the storage means, and the attitude of the welding torch is controlled based on the read advancing angle related variable.

  The invention of claim 3 is a measuring means for measuring a cross-sectional shape of a welded joint, a welding torch for welding the welded joint, and a manipulator for moving the measuring means together with the welding torch along a previously taught path. First calculation means for calculating a cross-sectional shape of the welded joint based on measurement data of the measurement means; second calculation means for calculating a target position and welding conditions based on the cross-sectional shape; the target position and the welding In an arc welding robot controller that performs welding by controlling the manipulator based on conditions, shape acquisition means for acquiring the shape of a bead that is supported by the manipulator and welded by the welding torch. , Surplus height calculating means for calculating the surplus height of the bead based on the acquisition data of the shape acquiring means, and the surplus height The higher, it is an gist control device of an arc welding robot, characterized in that it comprises a control means for controlling so as to increase the advancing angle of the welding torch.

  According to a fourth aspect of the present invention, in the third aspect, the height includes a surplus height and a advance angle related variable corresponding to the surplus height, and the advance angle related variable increases the advance angle of the welding torch as the surplus height increases. And a storage means for storing a bead appearance adjustment table set so as to decrease the advance angle of the welding torch as the surplus height is lower, and the control means is calculated by the surplus height calculation means. The advance angle related variable corresponding to the extra height is read from the storage means, and the attitude of the welding torch is controlled based on the read advance angle related variable.

  According to a fifth aspect of the present invention, in the fourth aspect, the bead appearance adjustment table is set such that the advance angle related variable changes linearly in accordance with a change in surplus height.

  The invention of claim 6 is characterized in that, in claim 4, the bead appearance adjustment table is set so that the advance angle related variable changes stepwise in accordance with a change in surplus height. .

  According to the method of the invention of claim 1, the advance angle of the welding torch increases as the surplus height calculated based on the acquisition data of the shape acquisition means increases, and the advance of the welding torch as the surplus height decreases. The angle decreases. As a result, when the advance angle of the welding torch is increased, that is, as the welding posture of the welding torch is tilted toward the advance angle side, the bead width is increased and the surplus height can be reduced. On the contrary, as the welding posture of the welding torch is tilted toward the receding angle side, the bead width is narrowed and the surplus height can be increased. For this reason, the surplus height of the beads can be made uniform, and as a result, a highly uniform bead appearance can be obtained.

  According to the method of the invention of claim 2, the storage means stores the bead appearance adjustment table so that the control means reads the advance angle related variable corresponding to the surplus height from the storage means, and the read advance angle related variable is read. Since the attitude of the welding torch is controlled based on the bead, the extra height of the beads can be made uniform, and as a result, a highly uniform bead appearance can be obtained.

  According to the invention of claim 3, the advance angle of the welding torch increases as the surplus height calculated based on the acquisition data of the shape acquisition means increases, and the advance angle of the welding torch decreases as the surplus height decreases. To do. As a result, when the advance angle of the welding torch is increased, that is, as the welding posture of the welding torch is tilted toward the advance angle side, the bead width is increased and the surplus height can be reduced. On the contrary, as the welding posture of the welding torch is tilted toward the receding angle side, the bead width is narrowed and the surplus height can be increased. Therefore, it is possible to provide a control device for an arc welding robot that can make the surplus height of the beads uniform and, as a result, obtain a highly uniform bead appearance.

  According to the control device of the fourth aspect of the invention, the storage means stores the bead appearance adjustment table, so that the control means reads the advance angle related variable corresponding to the surplus height from the storage means and reads the read advance angle. Since the welding posture of the welding torch is controlled based on the related variable, the extra height of the beads can be made uniform, and as a result, a highly uniform bead appearance can be obtained.

  According to the invention of claim 5, the change in the posture of the welding torch linearly changes according to the surplus height of the bead, so that the surplus height of the bead can be linearly changed to be uniform. A bead appearance with high uniformity can be obtained.

  According to the invention of claim 6, by changing the posture of the welding torch in a step shape according to the extra height of the bead, the extra height of the bead can be changed in a step shape to be uniform, As a result, a highly uniform bead appearance can be obtained.

  Hereinafter, an embodiment in which a method for controlling a position of a welding torch of an arc welding robot and a control device for an arc welding robot according to the present invention will be described with reference to FIGS. FIG. 1 is a block diagram illustrating a configuration of a control apparatus 10 for a welding robot.

The control device 10 of the welding robot controls the workpiece (work object) W so as to automatically perform arc welding.
The welding robot control device 10 includes a manipulator M that performs a welding operation, a robot control device RC that controls the manipulator M, a laser sensor LS as a measurement unit that detects the shape of the workpiece W, and a laser that controls the laser sensor LS. A sensor control unit LU and the like are provided.

  In addition, a teach pendant TP as a portable operation unit is connected to the robot controller RC. The teach pendant TP is provided with a keyboard and a liquid crystal display (not shown). Various teaching data are input to the robot controller RC by the keyboard.

  The manipulator M includes a base member 12 fixed to a floor or the like, and a plurality of arms 13 connected via a plurality of shafts. A welding torch 14 as a work tool is provided at the distal end portion of the arm 13 located on the most distal side. The welding torch 14 includes a wire 15 as a filler material, generates an arc between the tip of the wire 15 fed by a feeding device (not shown) and the workpiece W, and welds the wire 15 with the heat. To weld the workpiece W. A plurality of motors (not shown) are disposed between the arms 13, and the welding torch 14 can be freely moved back and forth and left and right by driving the motors. Note that front and rear refers to the direction in which the welding torch 14 travels along the weld line (that is, the welding progress direction indicated by the arrow in FIG. 1) as the front, and the direction opposite to 180 degrees as the rear. Left and right are referred to as left and right with reference to the direction in which the person travels. Weaving is possible by moving the welding torch 14 in the forward and leftward directions.

  The robot controller RC is composed of a computer as shown in FIG. That is, the robot controller RC is a rewritable EEPROM 21 that stores a CPU (Central Processing Unit) 20, various programs for controlling the manipulator M, and a plurality of image analysis programs prepared according to various groove shapes. And a RAM 22 serving as a working memory, and a storage unit 23 including a rewritable nonvolatile memory for storing various data. In the present embodiment, the robot control device RC corresponds to a second calculation unit.

  The storage unit 23 includes a first storage area 23a and a second storage area 23b. The first storage area 23a stores the adaptive welding condition table of Table 2 described above. Note that the adaptive welding condition table of Table 1 described above may be stored in the first storage area 23a.

The second storage area 23b stores a bead appearance adjustment table (see Table 3) described later. Bead appearance adjustment table are surplus and prime height Cv of the bead, and a forward angle P _R. Advancing angle P _R corresponds to the forward angle-related variables.

ビードの余盛り高さＣｖは図７（ａ）、（ｂ）に示すように、ワークＷに対して形成されるビードＢにおいて、水平な基準線ＬとビードＢの左右方向の中央部に形成される凸状部の頂点間の距離Ｄ１（すなわち、高さ）や、水平な基準線ＬとビードＢの左右方向の中央部に形成される凹状部の最深部間の距離Ｄ２（すなわち、深さ）を含む。基準線ＬからのビードＢの左右方向の中央部に形成される凸状部の頂点までの高さは＋値で示され、基準線ＬからのビードＢの左右方向の中央部に形成される凹状部の最深部の深さは−値で示される。

As shown in FIGS. 7A and 7B, the bead surplus height Cv is formed at the horizontal reference line L and the center of the bead B in the left-right direction in the bead B formed on the workpiece W. The distance D1 (that is, the height) between the vertices of the convex portion to be formed, and the distance D2 (that is, the depth) between the horizontal reference line L and the deepest portion of the concave portion formed at the center in the left-right direction of the bead B. Included). The height from the reference line L to the apex of the convex portion formed at the center in the left-right direction of the bead B is indicated by a positive value, and is formed at the center in the left-right direction of the bead B from the reference line L. The depth of the deepest part of the concave part is indicated by a minus value.

  The reference line L is a line along the horizontal plane when the surface of the bead B becomes a horizontal plane, and the boundary between the left edge BL of the bead B and the workpiece W and the boundary between the right edge BR and the workpiece W are defined. pass. The reference line L is determined based on imaging data as acquisition data of the imaging camera 25 described later. The imaging camera 25 corresponds to a shape acquisition unit.

Further, the advancing angle P _R, as shown in FIG. 4, perpendicular La (i.e., normal) to the tangent of the welding line the straight line L1 that represents the Z-axis direction of the welding torch 14 with respect to the perpendicular line La when the upright , L2. In addition, when the advance angle PR is less than 0 ° (in the case of L2), it is also referred to as a receding angle, but in this specification, the advancing angle is used to include this receding angle. In the case of the meaning of the receding angle, a value of “−” is added to the value of the advancing angle.

The bead appearance adjustment table shown in Table 3, when excess prime height Cv is less -4.0Mm, an advancing angle P _R is 0 °, when excess prime height Cv of less than 4.0mm or more -4.0Mm is advancing angle _{P R} are calculated _{(P R = 1.25Cv + 5)} , excess prime height Cv is the case of the above 4.0 mm, the advancing angle _{P R} is fixed to 10 °.

Thus bead appearance tuning table, if excess prime height Cv of less than 4.0mm or more -4.0Mm, the advancing angle P _R as excess prime height Cv rises increases linearly, the excess prime height Cv , the more an advancing angle P _R is set so as to decrease linearly lowered.

  In addition, the numerical value represented by this bead appearance adjustment table is an example, and is not limited to these values. For example, the advancing angle may be appropriately changed so as to include a negative value (that is, a receding angle). The storage unit 23 corresponds to a storage unit.

The storage unit 23 also includes a teaching data storage area (not shown) for storing teaching data such as a route input by the keyboard.
The robot controller RC controls the motor to drive the welding torch 14 along a route that is preset teaching data. Further, the robot controller RC outputs welding conditions such as a welding current and a welding voltage to the welding power source WPS, and causes the welding operation to be performed by electric power supplied from the welding power source WPS through the power cable PK.

  The laser sensor LS is a scanning type laser sensor that measures the distance to the workpiece W by light emission and light reception of a laser, is mounted on the welding torch 14, and the direction in which the welding torch 14 travels along the welding line (that is, FIG. The distance of the groove opening (that is, the unwelded portion) portion on the side of the traveling direction indicated by the arrow 1 is measured. The laser sensor LS includes a light emitting unit that emits light toward the workpiece W, a light receiving unit that receives the laser reflected by the workpiece W, and the like (both not shown). The laser emitted from the light emitting unit is irregularly reflected by the workpiece W and received by the light receiving unit. The light receiving unit is constituted by a CCD line sensor, for example, and measures the distance from the center of gravity of the received light amount distribution to the workpiece W.

  The laser sensor control device LU drives and controls the laser sensor LS, and in the process of obtaining the target position (target coordinates) of the welding torch 14 in the same manner as in the prior art, the gap amount and the opening amount from the measured distance measurement data (distance information). The groove information such as the tip area and cross-sectional shape is calculated in real time. The laser sensor control device LU returns the groove information including the cross-sectional shape of the weld joint together with the return of the target position (target coordinates) to the robot control device RC.

  The laser sensor control device LU includes a central processing unit (CPU), a computer having a plurality of image analysis programs prepared according to various groove shapes, a memory for storing various data, and the like. In the present embodiment, the laser sensor control device LU (computer) corresponds to the first calculation means.

  The welding torch 14 is equipped with an imaging camera 25 that images a bead formed on the side opposite to the traveling direction of the welding torch 14. In the present embodiment, the imaging camera 25 is composed of a CCD camera. However, the imaging camera 25 may be a camera composed of another imaging element (for example, CMOS), and is not limited. The imaging camera 25 corresponds to a shape acquisition unit.

  The camera control unit CCU includes a central processing unit (CPU), a computer having an image analysis program prepared according to various groove shapes, a memory for storing various data, and the like. The camera control unit CCU performs image processing of the imaging data of the imaging camera 25, calculates (that is, analyzes) the surplus height Cv of the imaged bead B, and notifies the surplus height Cv to the robot control unit RC. The camera control unit CCU corresponds to extra height calculation means.

  Next, a change in welding conditions and an attitude control of the welding torch, which are adaptive welding functions in the robot controller 10, will be described. The workpiece W to be welded is a fillet joint as a weld joint.

  As a precondition, the welding progress direction of the welding torch 14 is set to be the X axis or Y axis of the tool coordinate system, and the laser sensor LS is attached so as to be parallel to the X axis or Y axis. The The laser sensor LS (that is, the sensor head LSa shown in FIG. 2B) is configured to irradiate a laser beam at a position spaced a predetermined distance from the tip of the welding torch 14 toward the welding direction. The distance between the laser toe point on the tool coordinate system that is a predetermined distance away from the tip of the welding torch 14 and the welding direction is referred to as the sensor look-ahead distance T. In this embodiment, the + X direction is set as the welding progress direction. Note that the laser sensor LS may be attached obliquely to the welding torch 14 as shown in FIG.

2 (a) and 2 (b) show a welding torch 14 as a tool, and the tool coordinate system is represented as shown in FIG. 2 (a).
In addition, teaching data indicating the operation of the manipulator M when welding is performed, welding conditions, and the like are input to the robot controller RC via the teach pendant TP before the welding operation is performed. It is stored in the storage area 23b.

  For convenience of explanation, after the welding torch 14 is moved to the detected welding start point by the laser sensor LS preceding the welding torch 14, copying and welding are performed along a path taught in advance. A description will be given from the start (see FIG. 6A).

  Here, weaving is executed, and based on the distance measurement data obtained by the laser sensor LS for each sampling period, the laser sensor control device LU detects the feature point of the groove and the gap amount G of the initial groove, etc. The groove information including the gap amount G is notified to the robot controller RC.

  On the other hand, the camera control unit CCU performs image processing on data captured by the imaging camera 25. If there is a bead B, the camera control unit CCU analyzes the surplus height Cv of the bead B and notifies the surplus height Cv to the robot control unit RC.

FIG. 5 is a control flowchart executed by the CPU 20 of the robot controller RC every predetermined calculation cycle.
In S <b> 10, the CPU 20 determines whether or not the bead B is within the field of view of the imaging camera 25. If there is no notification of the surplus height Cv, it is determined as “NO”, and in S20, the CPU 20 refers to the adaptive welding condition table based on the gap amount G and determines the set current Is that is a welding current. The welding power source WPS is notified. The welding power source WPS supplies a welding current to the wire 15 based on the set current Is.

  In next S30, the CPU 20 controls the posture of the manipulator M with the target posture determined based on the groove information on the posture of the welding torch 14, and once ends this control flowchart. This target posture is a forward angle (hereinafter referred to as a teaching posture) taught in advance as teaching data. By the attitude control of the manipulator M, the welding torch 14 becomes the target attitude. Therefore, in this case, as shown in FIG. 6B, the welding posture of the welding torch 14 moves in the teaching posture.

  On the other hand, if there is a notification of the surplus height Cv in S10, the CPU 20 determines “YES”, and in S40, the CPU 20 refers to the adaptive welding condition table based on the gap amount G, and determines the welding current. A certain set current Is is determined and notified to the welding power source WPS. The welding power source WPS supplies a welding current to the wire 15 based on the set current Is.

In subsequent S50, CPU 20 refers to the bead appearance adjustment table to determine the advancing angle _{P R} in accordance with the excess prime height Cv. Then, in S60, CPU 20 notifies the advancing angle _{P R} to the laser sensor control unit LU. Laser sensor controller LU changes the parameters to be used for image analysis of the distance measurement data laser sensor LS is obtained based on the notified advanced angle P _R.

Then, in S70, CPU 20 is a manipulator M and attitude control based on a target position determined based on the groove information and the advancing angle P _R, temporarily ends the control flow chart. The attitude control of the manipulator M, the welding torch 14 reaches a target position, including forward angle P _R.

Therefore, in this case, until the welding end point, welding position of the welding torch 14 will vary based on the target position determined based on the groove information and forward angle P _R. And the advance angle of the welding torch 14 is changed by the process of S50-S70. Here, when the advance angle of the welding torch 14 is increased, the bead width generated by the welding torch 14 is widened, and the surplus height is lowered. On the other hand, as the advancing angle of the welding torch 14 becomes smaller, the bead width becomes narrower and the surplus height becomes higher.

According to this embodiment, the following effects can be obtained.
(1) A welding torch attitude control method and an arc welding robot control device 10 according to the present embodiment is configured to bead B formed by welding with a welding torch 14 by an imaging camera 25 supported by a manipulator M. The shape was acquired. Then, the surplus height of the bead B is calculated by the camera control unit CCU based on the acquired data of the imaging camera 25, and the advance angle of the welding torch 14 is increased as the surplus height is high, and the surplus height is low. The manipulator M is controlled by the robot controller RC so as to reduce the advance angle of the welding torch. As a result, the extra height of the bead B can be made uniform and a bead appearance with high uniformity can be obtained.

  (2) The welding torch attitude control method and the arc welding robot control apparatus 10 according to the present embodiment include a surplus height and a forward angle (advance angle related variable) corresponding to the surplus height. The storage unit 23 stores a bead appearance adjustment table that is set so that the advance angle increases as the height increases and the advance angle decreases as the height increases. Then, the robot controller RC reads the advance angle corresponding to the surplus height calculated by the camera controller CCU from the storage unit 23, and controls the welding posture of the welding torch 14 based on the read advance angle. . As a result, the extra height of the beads B can be made uniform and a bead appearance with high uniformity can be easily obtained.

  (3) Moreover, the control apparatus 10 of the arc welding robot of this embodiment sets the bead appearance adjustment table so that the advance angle changes linearly according to the change of the surplus height. As a result, the extra height of the bead B can be changed linearly so that the extra height of the bead B can be made uniform, and a highly uniform bead appearance can be easily obtained.

In addition, this invention is not limited to the said embodiment, You may comprise as follows.
○ In the above embodiment, the bead appearance adjustment table, if excess prime height Cv of less than 4.0mm or more -4.0Mm, the advancing angle P _R as excess prime height Cv becomes higher so as to increase linearly Yes. Alternatively, excess prime as shown in Table 4 Height Cv is the advancing angle P _R as becomes higher to increase stepwise advancing angle P _R as excess prime height Cv is low is reduced stepwise In this way, the bead appearance adjustment table may be set. In addition, the numerical value of the bead appearance adjustment table of Table 4 is an example, and is not limited.

このように、ビードの余盛り高さに応じて溶接トーチの姿勢をステップ状に変化させることにより、ビードの余盛り高さをステップ状に変化させて均一にでき、その結果、均一性の高いビード外観を得ることができる。

In this way, by changing the position of the welding torch in a step shape according to the extra height of the bead, the extra height of the bead can be changed stepwise to make it uniform, and as a result, the uniformity is high. A bead appearance can be obtained.

In the above-described embodiment, the imaging camera 25 is used as the shape acquisition unit. However, instead of the imaging camera 25, a laser sensor may be used.
In the above embodiment, the surplus height of the bead B is calculated by the camera control unit CCU as surplus height calculating means based on the imaging data, but the bead width of the bead B is calculated based on the imaging data, The extra height Cv may be obtained indirectly based on this bead width. That is, generally, as the welding position of the welding torch is tilted toward the advance angle side (that is, the advance angle is increased), the bead width is increased and the surplus height is decreased. Further, as the angle of retreat is inclined (that is, the advance angle becomes smaller), the bead width becomes narrower and the surplus height becomes higher.

  Because of this relationship, the relationship between the bead width and the surplus height is obtained in advance from a test value, a table is created, the bead width is calculated based on the imaging data, and the surplus according to the calculated bead width You may make it obtain height.

  In the embodiment, the adaptive welding condition table for changing the welding current as the welding condition according to the gap amount as the groove condition is set, but the adaptive welding condition table is not limited to this. You may set the adaptive welding condition table for changing the welding voltage as a welding condition according to the gap amount as a groove condition. In this case, the robot controller RC fills the gap by referring to the adaptive welding condition table and communicating the command according to the gap amount, that is, the welding voltage to the welding power source WPS and changing the welding voltage in real time. The desired welding construction can be performed.

  In addition, instead of the welding current in the adaptive welding condition table of the above embodiment, the feed amount (that is, the feed speed) of the wire 15 as a welding condition may be used. Although not described in detail in the embodiment, the wire 15 is fed to the welding torch 14 side by a wire feeding device (not shown) provided on the upper arm that supports the welding torch 14 in the manipulator M. In this case, the adaptive welding condition table is set so that the feed amount increases as the gap amount increases. When the gap amount of the groove information is notified, the robot control device RC refers to the adaptive welding condition table to determine the feed amount of the wire 15 and, based on this feed amount, determines the wire feeding device. Control.

  ○ The adaptive welding condition table corresponds to the gap amount and the weaving frequency or amplitude as the welding condition. If the gap amount increases, the weaving frequency or amplitude of the welding torch 14 is changed to increase the welding speed. You may set to do.

  ○ In the adaptive welding condition table, combine at least two variables of welding current, welding voltage, wire 15 feed amount, weaving frequency and / or amplitude as welding conditions, and combine them according to the increase in gap amount. May be set to increase both of the given variables.

  A sensor device control unit SDCU that integrates the laser sensor control unit LU and the camera control unit CCU of the above embodiment is provided, and the sensor device control unit SDCU provides the same management as the laser sensor control unit LU and the camera control unit CCU. You may make it manage groove information, such as a feature point, and a surplus height (refer FIG. 1). In this case, the adaptive welding condition table and the bead appearance adjustment table may be managed by the sensor device control apparatus SDCU. That is, the sensor device control apparatus SDCU may include a storage unit 23 having a first storage area 23a for storing an adaptive welding condition table and a second storage area 23b for storing a bead appearance adjustment table. The sensor device controller SDCU notifies the robot controller RC of the target position of the welding torch 14 obtained from the feature points and the target attitude of the welding torch 14 obtained from the advance angle after referring to the bead appearance adjustment table. At the same time, the welding power source WPS may be notified directly of the welding conditions obtained from the groove information and the surplus height.

○ The bead appearance adjustment table of the embodiment advancing angle P _R is set at a value from the vertical line La, but need not be set at a value of from vertical La, from the teachings posture which is previously taught as teaching data May be set as a relative value. The teaching data including the teaching posture is stored in the teaching data storage area of the storage unit 23. This relative value corresponds to the advance angle related variable. In this case, the robot controller RC reads the relative value and adds / subtracts the read relative value to / from the teaching posture to obtain the target posture of the welding torch 14.

  In the above embodiment, the manipulator M is driven and controlled so that the welding torch 14 is weaved. However, the manipulator may be driven and controlled so that the welding torch 14 is along the weld line without weaving.

The block diagram of the control apparatus of the robot of one Embodiment. (A) is explanatory drawing of a tool coordinate system, (b) is a perspective view of the laser sensor LS which shows the attachment state of the laser sensor LS. The block diagram of a robot control apparatus. Explanatory drawing of advancing angle. The flowchart which CPU of a robot control apparatus performs. (A) is explanatory drawing of the state in which the welding torch 14 reached the welding start point, (b) is explanatory drawing of the attitude | position of the welding torch 14 when the bead B is not in the visual field of the imaging camera 25, (c) is Explanatory drawing in which the attitude | position (namely, advance angle) of the welding torch 14 in case the bead B exists in the visual field of the imaging camera 25 changes. (A), (b) is explanatory drawing of the surplus height of a bead. The block diagram of the control apparatus of the robot of a prior art example. Explanatory drawing of groove | channel information (characteristic point) at the time of performing image analysis based on the ranging data sampled with the laser sensor LS with respect to the lap joint. Explanatory drawing of the three-dimensional track | orbit of a welding torch. (A) is explanatory drawing of gap amount G with a fillet joint, (b) is explanatory drawing of gap amount G and groove area of a butt joint. (A), (b) is explanatory drawing of surplus height.

Explanation of symbols

10 ... Control device, 14 ... Welding torch, 15 ... Wire,
20 ... CPU, 23 ... storage part (storage means),
25. Imaging camera (shape acquisition means),
M ... Manipulator, RC ... Robot control device (second calculation means, control means), LU ... Laser sensor control device (first calculation means),
LS: Laser displacement sensor (measuring means),
L ... reference line, P R _... advancing angle (advancing angle-related variables),
Cv: surplus height, CCU: camera control device (surplus height calculation means).

Claims (6)

Measuring means for measuring the cross-sectional shape of the welded joint, a welding torch for welding the welded joint, a manipulator for moving the measuring means along the route taught in advance together with the welding torch, and measurement data of the measuring means First calculation means for calculating the cross-sectional shape of the welded joint based on the second calculation means, second calculation means for calculating the target position and welding conditions based on the cross-sectional shape, and the manipulator based on the target position and the welding conditions. In the attitude control method of the welding torch of the arc welding robot that performs welding by controlling,
The shape acquisition means supported by the manipulator acquires the shape of the bead formed by welding with the welding torch,
Based on the acquisition data of the shape acquisition means, the extra height of the bead is calculated by the extra height calculation means,
The welding of the arc welding robot is controlled by the control means so that the advance angle of the welding torch is increased as the surplus height is higher, and the advance angle of the welding torch is decreased as the surplus height is lower. Torch attitude control method. And the advance angle related variable corresponding to the surplus height, and the advance angle related variable increases the advance angle of the welding torch as the surplus height increases, The bead appearance adjustment table set to decrease the advance angle of the welding torch as the lower the value is stored in the storage means,
The control means reads the advance angle related variable corresponding to the surplus height calculated by the surplus height calculating means from the storage means, and controls the attitude of the welding torch based on the read advance angle related variable. The attitude control method for a welding torch of an arc welding robot according to claim 1. Measuring means for measuring the cross-sectional shape of the welded joint, a welding torch for welding the welded joint, a manipulator for moving the measuring means along the route taught in advance together with the welding torch, and measurement data of the measuring means First calculation means for calculating the cross-sectional shape of the welded joint based on the second calculation means, second calculation means for calculating the target position and welding conditions based on the cross-sectional shape, and the manipulator based on the target position and the welding conditions. In a control device for an arc welding robot that performs welding under control,
Shape acquisition means for acquiring the shape of a bead formed by being welded by the welding torch while being supported by the manipulator;
Surplus height calculation means for calculating the surplus height of the bead based on the acquisition data of the shape acquisition means;
A control device for an arc welding robot, comprising control means for controlling the advance angle of the welding torch to increase as the surplus height increases. It consists of a surplus height and an advance angle related variable corresponding to the surplus height, and the advance angle related variable increases the advance angle of the welding torch as the surplus height increases, and the surplus height is low. Storage means for storing a bead appearance adjustment table set so as to reduce the advance angle of the welding torch,
The control means reads the advance angle related variable corresponding to the surplus height calculated by the surplus height calculation means from the storage means, and determines the attitude of the welding torch based on the read advance angle related variable. The control device for an arc welding robot according to claim 3, wherein the control device is controlled.   5. The control device for an arc welding robot according to claim 4, wherein the bead appearance adjustment table is set so that the advance angle related variable changes linearly in accordance with a change in surplus height.   5. The control device for an arc welding robot according to claim 4, wherein the bead appearance adjustment table is set so that the advance angle-related variable changes stepwise in accordance with a change in surplus height. .

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