JP2009119525A - Teaching method of welding line coordinate in welding robot, and teaching method of offset value in multi-layer build up welding of welding robot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a teaching method of welding line coordinates in a welding robot capable of improving efficiency in teaching work of offset values in welding lines after second pass when performing the teaching method of the offset values in multi-layer build up welding. <P>SOLUTION: The teaching method of welding line coordinates in the welding robot includes the steps of: setting ground welding line coordinates by defining a line connected by each teaching point in a first pass of multi-layer build up welding as a welding line to move a welding torch to a teaching point position of an m-th point in the first pass based on the ground welding line coordinates; moving the welding torch to an offset scheduled position corresponding to each pass after a second pass from the teaching point position of the m-th point in the first pass based on the ground welding line coordinates; and teaching the position of the welding torch every time when the welding torch moves to the offset scheduled position in each pass to record the difference between the position or posture of the first pass as an offset value based on the ground welding line coordinates in each pass after the second pass. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for teaching welding line coordinates in a welding robot and a method for teaching an offset value in multi-layer welding of a welding robot.

  In multi-layer welding, which is performed by welding thick plate structures, the welding section is repeatedly welded in multiple passes. Therefore, teaching all the teaching points of each pass makes the teaching work enormous, so only the teaching points of the lowermost one pass are taught, and the second and subsequent passes are offset to the teaching points of the first pass. The teaching work is reduced by adding a value. This offset value is specified on the basis of the weld line coordinate at each teaching point in the first pass.

  The X and Y axes of the welding line coordinates depend on the torch attitude of the welding torch at the teaching point as shown in FIG. 9, that is, the X axis of the welding line coordinates is made to coincide with the torch center axis. The offset value and the groove shape are not directly related. Therefore, when determining the offset value, the ideal offset value obtained from the groove shape drawing cannot be adopted as it is, and it is manually operated from the teaching point of the first pass to the position of the second pass or the third pass. It is necessary to decide by teaching work.

Patent Document 1 discloses a multi-layer welding method using a laser sensor. A groove shape is detected by the laser sensor, and multi-layer welding conditions such as a welding condition and an offset after the second pass are automatically detected. Is generated.
Japanese Patent Laid-Open No. 8-118022

  As described above, in the teaching work performed by manually moving the welding torch from the teaching point of the first pass to the teaching point of the second pass or the third pass, the manual operation is performed under the welding line coordinates. The weld line coordinates are set according to an axial direction including the weld line and an axial direction such as a torch center axis. However, since the axial directions other than the weld line depend on the torch posture regardless of the groove shape, there is a problem that manual operation is difficult.

  In Patent Document 1, the groove shape is detected using a laser sensor or the like, and the welding condition and the offset value are automatically set. In such a case, the offset value is a weld line coordinate. It doesn't matter. However, an arc welding robot that does not have a function for generating welding conditions and a multi-layer welding condition such as an offset after the second pass automatically needs to determine an offset value by a teaching operation.

  An object of the present invention is to perform an offset value teaching work efficiency in the second and subsequent passes when executing an offset value teaching method in multi-layer welding in an arc welding robot that does not have an automatic offset value generation function. An object of the present invention is to provide a method of teaching an offset value in multi-layer welding of a welding robot that can improve the welding speed.

  Another object of the present invention is to provide a welding line coordinate teaching method in a welding robot that can suitably set the welding line coordinates when executing the offset value teaching method in multi-layer welding of a welding robot. There is.

  In order to solve the above problems, the invention according to claim 1 teaches a weld line, teaches a reference axis that is perpendicular to the axis on the weld line and related to a groove shape, and is a non-torch central axis. And a teaching method of welding line coordinates in a welding robot including a step of setting welding line coordinates composed of axes orthogonal to both of the axis on the taught welding line and the reference axis. .

The invention of claim 2 is characterized in that, in claim 1, the reference axis is an axis included in a surface forming the groove shape, or an axis positioned between the surfaces forming the groove shape. To do.
The invention of claim 3 is characterized in that, in claim 2, the axis on the weld line is taught at one teaching point on the welding line and a teaching point adjacent to the teaching point.

According to a fourth aspect of the present invention, in the first or second aspect, the reference axis is parallel to an axis orthogonal to the ground in the absolute coordinate system.
According to a fifth aspect of the present invention, a line connected at each teaching point in the first pass of multi-layer welding is a welding line, and the welding line coordinates of the welding robot according to any one of the first to fourth aspects are defined. The first step of setting the welding line coordinates by the teaching method, and manually operating the welding torch at the teaching point position of the m (m = 1,... M) point of the first pass with reference to the welding line coordinates. The second step of moving and the welding torch is manually moved from the m-th teaching point position of the first pass to the corresponding offset planned position of each of the second and subsequent passes based on the welding line coordinates. Each time the welding torch moves to the expected offset position in each pass, the position of the welding torch is taught, and the difference from the position and orientation of the first pass is determined as the welding line coordinates in each pass after the second pass. As an offset value based on It is an gist methods taught offset value in multipass welding of a welding robot, characterized in that it comprises a third step of.

  The invention of claim 6 is the invention according to claim 5, wherein when moving to the m-th teaching position in the first pass in the second step, the (m + 1) -point direction from the m-point is set as a new axis on the weld line. An axis on the weld line is set, and the weld line coordinates are updated.

According to the first aspect of the present invention, when teaching the offset value in the multi-layer welding of the welding robot, the welding line coordinates can be suitably set.
According to the second aspect of the present invention, it is possible to suitably set the welding line coordinates that are axes included in the surface where the reference axis forms the groove shape, or an axis located between the surfaces forming the groove shape. .

According to the invention of claim 3, the welding line coordinates can be suitably set by teaching the axis on the welding line by one teaching point on the welding line and a teaching point adjacent to the teaching point. .
According to the invention of claim 4, it is possible to suitably set the welding line coordinates with the axis orthogonal to the ground in the absolute coordinate system as the reference axis.

  According to the invention of claim 5, in the arc welding robot that does not have an automatic offset value generation function, when the offset value teaching method in multi-layer welding is executed, the offset value teaching in the second and subsequent passes is taught. Work efficiency can be improved.

  According to the invention of claim 6, when the welding line is non-linear, the welding line coordinates can be updated by setting the axis on the new welding line as a line connecting adjacent teaching points, and the welding after the update It is possible to improve the efficiency of teaching the offset value in the weld line after the second pass with reference to the line coordinates.

A coordinate system used in this embodiment will be described.
FIG. 6 is a coordinate system relationship diagram illustrating the relationship between each coordinate system including the world coordinate system, the robot base coordinate system, the tool coordinate system, and the weld line coordinate system regarding the manipulator 11. As shown in the figure, the manipulator 11 has links L0 to L6 and joint axes K1 to K6.

(World coordinate system X _Σ -Y _Σ -Z _Σ )
As shown in FIG. 6, the world coordinate system X _Σ -Y _Σ -Z _Σ is a coordinate system based on the ground, and the origin is set at a reference position Σ arbitrarily determined on the ground, and the direction in which gravity acts Is a right-handed orthogonal coordinate system in which the opposite direction is the ZΣ axis and the horizontal plane is the reference plane X _Σ -Y _Σ . The world coordinate system corresponds to the absolute coordinate system.

(Robot base coordinate system Xw-Yw-Zw)
A robot base coordinate system (also referred to as a base coordinate system) Xw-Yw-Zw has an origin set at a reference position W of the manipulator 11, and a horizontal plane parallel to the bottom surface of the manipulator 11 when the manipulator 11 is installed has a reference plane Xw. This is a right-handed orthogonal coordinate system in which the direction from the reference plane Xw-Yw to the manipulator 11 is the Zw axis.

(Tool coordinate system Xt-Yt-Zt)
In the tool coordinate system Xt-Yt-Zt, the origin is set at the torch tip position T, and the direction from the torch tip position T along the torch center axis, that is, the direction toward the torch mounting position of the link of the manipulator 11 is the Zt axis. It is a right-handed orthogonal coordinate system.

(Ground weld line coordinate system Xs-Ys-Zs)
In the ground weld line coordinate system Xs-Ys-Zs, the origin is the current welding position S, the welding progress direction at this welding position S is the Zs axis, and the plane including the welding position S and perpendicular to the welding progress direction axis Zs is a plane. The weld line orthogonal plane is Xs-Ys. Further, the earth welding seam coordinate system Xs-Ys-Zs may be the acting direction and a plane perpendicular to the weld line perpendicular plane Xs-Ys include Z _sigma axis toward the opposite direction of gravity and the weld line vertical plane Xs-Zs, It is a right-handed orthogonal coordinate system in which the plane orthogonal to the weld line orthogonal plane Xs-Ys and the weld line vertical plane Xs-Zs is the weld line horizontal plane Ys-Zs.

Here, the ground weld line coordinates are set in relation to the groove shape of the weld joint.
Specifically, an Xs axis (reference axis) that is parallel to the Z _Σ axis of the world coordinate system that goes in the opposite direction to the direction in which gravity acts and that passes through the first-pass teaching point forms a groove shape. The ground weld line coordinates are set so as to be positioned between the pair of surfaces of the base material or included in the surface of the base material forming the groove shape. In this case, examples of the groove shape include a T joint, a fillet joint, a V shape, and a ledge shape.

  In this embodiment, as shown in FIG. 4, a pair of plate-like workpieces 16 are arranged so as to be orthogonal to each other to form a fillet joint, and one workpiece (mother) forming a groove shape is formed. The surface of the (material) 16 is arranged so as to include the Xs axis. The teaching point in the first pass is on the weld line where the Zs axis coincides.

(Relationship between each coordinate system)
The torch tip position T is determined from the mechanical structure of the lengths of the links L0 to L6 and the joint angles of the joint axes K1 to K6. The position and orientation relationship between the world coordinate system _X Σ -Y Σ -Z Σ a robot-base coordinate system Xw-Yw-Zw and the tool coordinate system Xt-Yt-Zt is represented by Twt = Twb × Tbt.

Here, Twt, Twb, and Tbt are as follows.
Twt: Position and orientation relationship of the tool coordinate system with respect to the world coordinate system,
Twb: Position and orientation relationship of the robot base coordinate system with respect to the world coordinate system
Tbt: Position and orientation relationship of the tool coordinate system with respect to the robot base coordinate system.

  Usually, since the manipulator 11 is used while being fixed to the ground, the position and orientation relationship between the world coordinate system and the robot base coordinate system does not change. Therefore, Twb is constant. For this reason, the position and orientation relationship Tbt of the tool coordinate system with respect to the robot base coordinate system can be calculated from the position of each axis of the manipulator 11.

The relationship between the ground weld line coordinates and the robot base coordinate system will be described later.
Next, an embodiment in which the teaching method of the welding line coordinates in the welding robot of the present invention and the teaching method of the offset value in the multi-layer welding of the welding robot will be described with reference to FIGS.

FIG. 1 is a schematic diagram showing the configuration of an arc welding robot and its robot controller RC.
The robot controller RC of the welding robot controls the workpiece 16 so that arc welding is automatically performed on the workpiece 16, and includes a six-axis (that is, six joint axes) manipulator 11 that performs a welding operation, and a manipulator 11. A robot controller RC for controlling A teach pendant TP as a portable operation unit is connected to the robot controller RC. A display device including a keyboard and a liquid crystal display (not shown) is provided on the operation surface of the teach pendant TP. The keyboard is provided with various keys such as a mode designation key and a coordinate system designation key. Further, various teaching data are input to the robot controller RC by the keyboard. The manipulator 11 includes a base member 12 fixed to a floor or the like, and a plurality of arms 13 (corresponding to the links described above) 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 work 16, and welds the wire 15 with the heat. By doing so, the workpiece 16 is welded. A plurality of motors (not shown) are disposed between the arms 13, and the welding torch 14 can be freely moved in translation and rotation by driving the motors.

  As shown in FIG. 3, the robot controller RC stores a CPU (central processing unit) 20, a rewritable EEPROM 21 that stores various programs for controlling the manipulator 11, a RAM 22 that serves as a work memory, and various data. A storage unit 23 composed of a rewritable nonvolatile memory is provided. The robot controller RC includes a servo driver 24 for controlling the motor of the manipulator 11, and controls the manipulator 11 by various programs including preset teaching data, and the position of the welding torch 14 during welding, It is possible to change the posture.

  Next, the teaching procedure of the offset value in the multi-layer welding of the welding robot will be described with reference to FIG. FIG. 5 is a flowchart of an offset value teaching procedure in multi-layer welding. In addition, the welded joint in this embodiment is intended for a T-joint or fillet joint in which two base materials are combined at a right angle.

  In step (hereinafter referred to as ST) 1, the operator determines M teaching points from the welding path of the first pass of the workpiece 16 and operates the manipulator 11 by input from the teach pendant TP. Each time the welding torch 14 reaches each teaching point on the workpiece 16, the position and orientation of the welding torch 14 relative to the workpiece 16 are taught at each teaching point. In this way, the weld line is taught by teaching M teaching points in the first pass. At each teaching point in the first pass, the position and orientation of the welding torch 14 are taught in the robot base coordinate system. In addition, for each teaching point, a teaching torch operation instruction, a welding condition instruction, and the like are also input by the teach pendant TP.

In the next ST2, the operator selects the weld line coordinates using the coordinate system designation key on the keyboard of the teach pendant TP. Here, the operator selects the Xs axis parallel to the Z _Σ axis of the world coordinate system as a reference axis in order to select the ground weld line coordinates. The Xs axis that is the reference axis corresponds to a non-torch central axis that does not pass through the central axis of the welding torch 14.

  The selection result of the Xs axis at the selected ST2 is stored in the storage unit 23 of the robot controller RC. Here, the Xs axis of the ground weld line coordinate serving as a reference coordinate for manual operation described later is selected. At the same time, the robot controller RC obtains the Zs axis of the ground weld line coordinates from the weld line obtained in ST1. For example, the Zs axis is calculated based on a straight line connecting the first teaching point and the second teaching point in the first pass. In this case, the teaching point is not limited to the first teaching point and the second teaching point in the first pass, and may be a straight line connecting adjacent teaching points such as the second teaching point and the third teaching point.

The next ST3 to STn _{+ 2} are teaching processes in the second and subsequent passes, and are repeated from the first teaching point to the Mth teaching point in the first pass. The first teaching point,..., Mth teaching point indicates the order of teaching points when counted from the welding start point to the welding end point side.

Hereinafter, ST4 to STn _{+ 2} will be described as processing in the second and subsequent passes corresponding to the first teaching point of the first pass (in this case, m = 1).
In ST4, the operator moves the welding torch 14 by manual regeneration operation using the teach pendant TP at the first teaching point of the first pass. Next, in ST5, the operator inputs the teaching point direction from the first teaching point (in this case, the direction from m point to m + 1 point) with the teach pendant TP as the Zs axis. With this input, the robot controller RC updates the ground weld line coordinates at the first teaching point with the Xs axis selected in ST2 and the input Zs axis.

Here, the calculation of the ground weld line coordinates will be described with reference to FIG.
As described above, when the trajectory Q1Q2 is the direction from m point to m + 1 point (in the above example, the first teaching point direction to the second teaching point direction), the trajectory Q1Q2 of the ground weld line coordinates is taught on the basis of the robot base coordinate system, When the Xs axis of the ground weld line coordinates is designated as the Z _Σ axis direction of the world coordinates, the ground weld line coordinates are calculated as follows.

If the orientation of the world coordinates as seen from the robot base coordinate system is given by _w X _Σ (= [ _w n _Σ , _w o _Σ , _w a _Σ ]), the ground weld line coordinates to be calculated (= [ _w n, _w o, _w a]) is given by:

_w a = vector Q1Q2 / | vector Q1Q2 |
_w o = _w a × _w a _Σ / | _w a × _w a _Σ |
_w n = _w o × _w a / | _w o × _w a |
Here, _w a, _w a _Σ , _w o, _w n, _w n _Σ , and _w o _Σ are vectors, and “×” represents an outer product.

  Returning to the flowchart, in ST6, the operator selects the jog feed mode using the teach pendant TP, and operates the manipulator 11 by jog feed, that is, by manual operation to offset the welding torch 14 in the second pass. Place it at the planned position.

  At the time of this manual operation, the design drawing of the groove shape of the present embodiment is such that the operator moves to the planned offset position of the second pass corresponding to the first teaching point (m = 1 in this case). The moving operation is performed based on the ideal offset value obtained from (hereinafter, this offset value is referred to as a target offset value).

  This target offset value is an offset value from the first teaching point in the first pass, and is set as a coordinate value in the ground weld line coordinate system. The display device (not shown) of the teach pendant TP is based on the detected value (rotation angle) of an angle sensor such as a rotary encoder (not shown) provided on each joint shaft of the manipulator 11 and the length of each link. The calculated position of the welding torch 14 is displayed as coordinate values in the ground weld line coordinate system. The operator manually operates the manipulator 11 with reference to the coordinate values of the ground welding line coordinate system of the welding torch 14 displayed on the display device of the teach pendant TP, and offsets the welding torch 14 in the second pass. Place it at the planned position.

  After positioning the welding torch 14 at the planned offset position of the second pass in this way, in ST7, a memory key (not shown) provided on the operation surface of the teach pendant TP is pressed, so that the first pass The position and orientation at the teaching point of the welding torch 14 in the second pass corresponding to the first teaching point is stored in the storage unit 23. At the same time, the robot controller RC stores the difference between the first teaching point in the first pass and the position and orientation at the corresponding teaching point in the second pass as an offset value in a file in the storage unit 23.

  Subsequently, in ST8, the operator selects the jog feed mode using the teach pendant TP in the same manner as ST6, and the manipulator 11 is operated by jog feed, that is, by manual operation, so that the welding torch 14 is offset in the third pass. Place it at the planned position.

  At the time of this manual operation, the operator is moved to the planned offset position of the third pass corresponding to the first teaching point (in this case, m = 1) in the first pass. Based on the ideal target offset value obtained from

  The target offset value of the third pass is a value of an offset from the first teaching point of the first pass, and is set in the same manner as the second pass with the coordinate value of the ground weld line coordinate system. The display device (not shown) of the teach pendant TP is based on the detected value (rotation angle) of an angle sensor such as a rotary encoder (not shown) provided on each joint shaft of the manipulator 11 and the length of each link. The calculated position of the welding torch 14 is displayed as coordinate values in the ground weld line coordinate system. The operator manually operates the manipulator 11 with reference to the coordinate values at the time of the ground welding line coordinate system of the welding torch 14 displayed on the display device, so that the welding torch 14 is set to the offset intended position in the third pass. Position.

  After positioning the welding torch 14 at the planned offset position for the third pass in this way, in ST9, a memory key (not shown) provided on the operation surface of the teach pendant TP is pressed to obtain the first pass. The position and orientation of the welding torch 14 at the teaching point in the third pass corresponding to the first teaching point is stored in the storage unit 23. In addition, the robot controller RC stores the difference between the first teaching point in the first pass and the position and orientation at the corresponding teaching point in the third pass in the file of the storage unit 23 as an offset value.

Hereinafter, second pass, third pass and in the same manner, the ST _n, the manipulator 11 in the manual operation to the position of the N pass is manually operated to position the welding torch 14 to the offset predetermined position. Similarly to the second pass and the third pass, in ST _{n + 1} , by pressing a storage key (not shown) provided on the operation surface of the teach pendant TP, the first teaching point of the first pass The position and orientation of the welding torch 14 in the Nth pass corresponding to are stored in the storage unit 23. At the same time, the robot controller RC stores the difference between the first teaching point in the first pass and the position and orientation at the corresponding teaching point in the N pass in the file of the storage unit 23 as an offset value.

When recording of the offset value of the welding torch 14 at the teaching point in all the passes of multi-layer welding corresponding to the m-th teaching point in the first pass (in this case, m = 1) is completed, in ST _{n + 2} , Preparation for the teaching process of the next teaching point in the first pass (in this case, m = 2) is made, and the process returns to ST3.

When returning to ST3, the operations and processes of ST4 to STn _{+ 2} are similarly repeated.
Then, when the operation and processing of ST4 to STn _{+ 2} regarding the Mth teaching point in the first pass are finally completed and m> M in ST3, the operator ends this series of processing.

  In addition, the position and orientation (offset value) of the welding torch 14 at each teaching point in each of the second and subsequent passes stored in the file of the storage unit 23 configured as described above is as follows during reproduction when arc welding is performed. The calculation is performed as follows in the robot controller RC.

It is assumed that the position and orientation [P, R] of the Mth teaching point in the first pass. In the first pass position and orientation, the reference coordinate system is the robot base coordinate system.
The offset value of the Mth teaching point in the Nth pass is (x, y, z, a, b, c).

The first pass M, from 2 teaching points M + 1, calculated ground welding seam coordinates _{[w n, w o, w} a, w P M] to a robot-base coordinate system.
The position P of the Mth teaching point on the Nth pass is
_{P = w P M + w n} · x + w o · y + w a · z
It becomes.

The posture R of the Mth teaching point in the Nth pass is
R = _w R _y · RPY (a, b, c) · _y R _m
It becomes. However,
_w R _y = [ _w n, _w o, _w a]
_y R _m = Attitude of M teaching point in the first pass as seen from the ground weld line coordinates
RPY (a, b, c) is a transformation matrix based on roll, pitch, and yaw angle.

(Check offset value / manual correction)
The offset value taught as described above is confirmed by the operator using the teach pendant TP to read the file stored in the storage unit 23 and place the welding torch 14 at each teaching point in the first pass. After the movement, the welding torch 14 is performed by manually performing a regeneration operation to the teaching point reflecting the offset value of each pass after the second pass.

  When the teaching point reflecting the offset value of each pass after the second pass is corrected in the regenerative operation, the operator is required to perform ground welding in the same manner as the manual operation in each pass after the second pass. The manual operation is performed on the basis of the line coordinates, the welding torch 14 is moved to the desired offset planned position, and then the storage key is operated. As a result, the offset value of the position and orientation of the welding torch 14 at the teaching point of the path in the storage unit 23 is corrected.

Now, according to this embodiment, there are the following features.
(1) The welding line teaching method according to the present embodiment teaches a welding line at ST1 as shown in FIG. 5, and is perpendicular to the Zs axis on the welding line and is related to the groove shape at ST2, and is a non-torch central axis. The Xs axis (reference axis) is taught. In ST5, a ground weld line coordinate (weld line coordinate) composed of a Ys axis that is orthogonal to both the Zs axis and the Xs axis (reference axis), which are axes on the taught line, is set. .

As a result, when teaching the offset value in the multi-layer welding of the welding robot, the ground welding line coordinates (welding line coordinates) can be suitably set.
(2) In the welding line teaching method of the present embodiment, the Xs axis (reference axis) is an axis included in the surface forming the groove shape. As a result, it is possible to suitably set the ground weld line coordinates (weld line coordinates) that are axes included in the surface on which the Xs axis (reference axis) forms the groove shape.

  (3) In the welding line teaching method of this embodiment, as shown in FIG. 5, in ST5, the axis on the welding line (Zs axis) is one teaching point (m point) on the welding line and the teaching point (m The welding line coordinates can be suitably set by being taught by the teaching point (m + 1 point) adjacent to the point).

(4) In the welding line teaching method of the present embodiment, the Xs axis (reference axis) is parallel to the Z _Σ axis orthogonal to the ground in the world coordinate system (absolute coordinate system).
As a result, it is possible to suitably set the welding line coordinates in which the axis orthogonal to the ground in the absolute coordinate system is the Xs axis (reference axis).

(5) In the teaching method of the offset value in multi-layer welding of the welding robot of the present embodiment, as a first step, a line connected at each teaching point in the first pass of multi-layer welding is used as a welding line, and the above-described welding line. The ground welding line coordinates were set by the coordinate teaching method. As shown in FIG. 5, in ST4, as a second step, the welding torch 14 is manually operated at the teaching point position of the mth (m = 1,... M) point of the first pass with reference to the ground welding line coordinates. Moved. Further, as a third step, the welding torch 14 is manually moved from the teaching point position of the m-th pass of the first pass to the corresponding offset planned position of each pass after the second pass with reference to the ground weld line coordinates. and so as to (see ST6, ST8, ST _n, etc. Figure 5). As the third step, every time the welding torch 14 moves to the expected offset position in each pass, the position of the welding torch 14 is taught, and the difference from the position / posture of the first pass is determined from the second pass onward. The offset values are recorded with reference to the ground weld line coordinates in each of the paths (see ST7, ST9, STn _{+ 1,} etc. in FIG. 5).

  As a result, according to the present embodiment, in the arc welding robot having no automatic offset value generation function, when the offset value teaching method in the multi-layer welding is executed, the offset value in the second and subsequent weld lines is The efficiency of teaching work can be improved.

  In particular, in the teaching work of multilayer overlay welding of a thick plate whose groove is oriented in a specific direction, such as a workpiece placed on the floor surface, where the groove at the time of welding is positioned upward by a positioner or the like. When teaching (or correcting) the offset value of the teaching point after the pass, the teaching work can be performed more efficiently because it moves in the direction along the groove shape regardless of the torch posture.

  (6) In the teaching method of the offset value in the multi-layer welding of the welding robot of the present embodiment, as the second step, when moving to the m-th teaching position in the first pass, the direction from the m point to the (m + 1) point direction Set the axis on the weld line as the new axis on the weld line, and update the ground weld line coordinates.

  As a result, when the weld line is non-linear, the ground weld line coordinate can be updated by setting the axis on the new weld line to the line connecting adjacent teaching points, and the weld line coordinate after the update is used as a reference. Thus, it is possible to improve the efficiency of teaching the offset value in the second and subsequent passes.

In addition, you may change embodiment of this invention as follows.
In the above embodiment, the manipulator 11 of the 6-axis welding robot is 6-axis, but is not limited to 6-axis, and may be a manipulator other than 6-axis.

  In the above embodiment, in ST2 of FIG. 4, the operator selects (teaches) the Xs axis as the reference axis, but selects (teaches) the Ys axis of the ground weld line coordinate system that is the non-torch central axis as the reference axis. You may do it.

  In the above embodiment, the ground weld line coordinates are set in the case of the fillet joint. However, the weld line coordinates are not limited to the ground weld line coordinates. For example, when the weld line is in a direction opposite to the direction in which the gravity of the earth acts as in upward welding, the direction of the Xs axis of the weld line coordinate is orthogonal to the weld line instead of the ground weld line coordinate. You may make it go to a horizontal direction.

  For example, FIG. 7 shows a groove (that is, a clevis shape) having a groove 16a having a cross-sectionally-letter shape extending upwardly perpendicularly to the ground on the surface of the workpiece 16. The groove 16a at the groove has a pair of inner surfaces 16b and 16c.

  In this case, in ST1 of the flowchart of the above-described embodiment, a weld line perpendicular to the ground and directed upward is taught by the teach pendant TP as a first-pass weld line. Subsequently, in ST2, using the teach pendant TP, a point P1 on the welding line of the first pass and a point P2 on the axis included in the inner surface 16c that passes through the point P1 horizontally and forms a groove are obtained. By teaching, the points P1 and P2 directions may be taught as the Xs axis of the welding line coordinates.

  Further, FIG. 8 shows a V groove (that is, a V shape) having a groove 17a having a V-shaped cross section that extends vertically upward on the surface of the work 16 with respect to the ground. The V groove groove 17a has a pair of inner surfaces 17b and 17c.

  In this case, in ST1 of the flowchart of the above-described embodiment, a weld line perpendicular to the ground and directed upward is taught by the teach pendant TP as a first-pass weld line. Subsequently, in ST2, using the teach pendant TP, the point P1 on the welding line of the first pass and the axis line between the two inner surfaces 17b and 17c passing through the point P1 and forming the V groove are formed. By teaching the point P2, the points P1 and P2 directions may be taught as the Xs axis of the weld line coordinates.

In the above embodiment, as described in ST4 to STn _{+ 1} in the flowchart of FIG. 4, the offset value of the teaching point after the second pass is obtained by the teaching operation, but it may be as follows.

  Since the reference axis of the ground weld line coordinates as the weld line coordinates is related to the groove shape, it is possible to input the offset value of the teaching point for the second and subsequent passes without performing the teaching operation as described above. Good. In this case, dimensions relating to a general groove (for example, fillet, V groove, lave groove, etc.) are determined in advance and stored in the storage unit 23, and the groove is based on the dimensions. The operator operates the keyboard to display the shape on the screen of the display device of the teach pendant TP. Then, on the screen of the display device, the offset value of each teaching point after the second pass is input as a numerical value in the ground weld line coordinate system. The input offset value is stored in a file in the storage unit 23.

In addition, when the position of the teaching point reflecting the offset value of each pass after the second pass is confirmed by numerical input, it may be performed by a manual regeneration operation as in the above embodiment.
Also, when the offset value of the teaching point is corrected after the numerical value of the teaching point offset value after the second pass is performed, it is performed by the teaching operation as in the above embodiment, or The file to be corrected may be read and the offset value may be re-input on the screen of the teach pendant TP display device.

Schematic which shows the structure of the arc welding robot and robot control apparatus RC of one Embodiment which actualized this invention. Schematic which shows the relationship between a ground weld line coordinate, a robot base coordinate, and a world coordinate. The block diagram of robot controller RC. Explanatory drawing of fillet welding. The flowchart of the teaching procedure of the offset value in multilayer overlay welding. FIG. 5 is a coordinate system relationship diagram illustrating the relationship between each coordinate system including a world coordinate system, a robot base coordinate system, a tool coordinate system, and a weld line coordinate system related to the manipulator 11. Explanatory drawing which shows the relationship between the groove shape of other embodiment, and a weld line coordinate. Explanatory drawing which shows the relationship between the groove shape of other embodiment, and a weld line coordinate. Explanatory drawing of the conventional weld line coordinate and groove shape.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Manipulator, 12 ... Base member, 13 ... Arm, 14 ... Welding torch, 16 ... Workpiece, 23 ... Memory | storage part, RC ... Robot control apparatus, (Sigma) ... World coordinate system reference position, W ... Robot base coordinate reference position , S: welding position.

Claims (6)

Teaching a weld line, teaching a reference axis that is orthogonal to the axis on the weld line and is related to the groove shape and is a non-torch central axis;
A method for teaching welding line coordinates in a welding robot, comprising the step of setting welding line coordinates composed of axes orthogonal to both the axis on the taught welding line and the reference axis.   2. The welding line in the welding robot according to claim 1, wherein the reference axis is an axis included in a surface forming the groove shape or an axis positioned between the surfaces forming the groove shape. Coordinate teaching method.   3. The method for teaching welding line coordinates in a welding robot according to claim 2, wherein the axis on the welding line is taught at one teaching point on the welding line and a teaching point adjacent to the teaching point.   3. The method for teaching welding line coordinates in a welding robot according to claim 1, wherein the reference axis is parallel to an axis orthogonal to the ground in the absolute coordinate system. The line connected by each teaching point in the first pass of multi-layer welding is a welding line, and the welding line coordinates are determined by the welding line coordinate teaching method in the welding robot according to any one of claims 1 to 4. A first step to set,
A second step of manually moving the welding torch to the teaching point position of the m-th (m = 1,... M) point of the first pass with reference to the welding line coordinates;
The welding torch is manually moved with reference to the welding line coordinates from the m-th teaching point position in the first pass to the corresponding offset planned position in the second and subsequent passes, and the offset is scheduled in each pass. Each time the welding torch moves to a position, the position of the welding torch is taught, and the difference from the position / posture of the first pass is an offset value based on the weld line coordinates in each pass after the second pass. The teaching method of the offset value in the multi-layer welding of the welding robot characterized by including the 3rd step recorded as.   When moving to the m-th teaching position in the first step in the second step, the axis on the weld line is set with the direction from the m point to the (m + 1) point as the new axis on the weld line, and the weld line coordinates The method of teaching an offset value in multi-layer welding of a welding robot according to claim 5, wherein:

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