JP2009148801A - Stitch pulse welding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stitch pulse welding method with which a wide weld bead can be formed. <P>SOLUTION: In the stitch pulse welding method, after welding is performed by moving an arc welding torch T to a working position on an operation line L, while repeating re-welding in the next working position separated by a prescribed moving pitch, a weld bead is formed on a workpiece W by superimposing welding traces that are formed through the welding at respective working positions on one another. A welding track Kc including a working position Pn is formed in a prescribed region having a prescribed width in a direction orthogonal to an operation line direction Dr and the operation line L, and welding is performed while moving the tip end of the arc welding torch T along the welding track Kc. The welding track Kc is a circular or elliptical or spiral welding track and is formed in accordance with a pattern selected among predetermined track patterns. Since the welding traces are formed by the welding track Kc in respective working positions, a wide weld bead can be obtained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a stitch pulse welding method for performing welding while minimizing the influence of heat on a thin base metal.

  Stitch pulse welding is a welding method that minimizes the heat effect on the base metal by controlling the heat input and cooling during welding. It is a welding method aiming at automation of thin plate welding, and it is said that the welding appearance can be improved and the amount of welding distortion can be reduced as compared with conventional thin plate welding (see, for example, Patent Document 1).

  In Patent Document 1, an arc is generated for a predetermined time while the arc welding torch is stopped, the base material is melted, the arc is stopped after the set time has elapsed, and the arc welding torch is connected to the melting part. Means for moving to the arc restart point on the outer periphery side is disclosed. Hereinafter, this prior art will be described.

  FIG. 13 is a view showing a conventional stitch pulse welding apparatus 51.

  The manipulator M automatically performs arc welding on the workpiece W, and includes an upper arm 53, a lower arm 54, a wrist portion 55, and a plurality of servo motors (not shown) for rotationally driving them. It is configured.

  The arc welding torch T is attached to the tip portion of the upper arm 53 of the manipulator M, and guides the welding wire 57 having a diameter of about 1 mm wound around the wire reel 56 to the welding position where the workpiece W is taught. It is. The welding power source AP supplies a welding voltage between the arc welding torch T and the workpiece W. When welding the workpiece W, the welding wire 57 is protruded from the tip of the arc welding torch T by a desired protrusion length Ew. The length of the protruding length Ew is generally around 15 mm, but the operator adjusts it to the desired length in advance using the teach pendant TP, which will be described later, according to the groove shape of the welding location, welding conditions, etc. Is possible.

  The conduit cable 52 includes a coil liner (not shown) for guiding the welding wire 57 therein, and is connected to the arc welding torch T. Furthermore, the conduit cable 52 also supplies the electric power from the welding power source AP and the shield gas from the gas cylinder 58 to the arc welding torch T.

  The teach pendant TP as an operation means is a so-called portable operation panel, and the conditions (welding current, welding voltage, moving speed, moving pitch, welding time, and the conditions necessary for performing the operation of the manipulator M and stitch pulse welding) Cooling time) and the like. Using this teach pendant TP, the worker creates a work program in which the above conditions are set together with the operation of the manipulator M.

  The robot controller RC is for causing the manipulator M to control the welding operation, and includes a main control unit, an operation control unit, a servo driver (all not shown), and the like. Then, based on a work program taught by the operator using the teach pendant TP, an operation control signal is output from the servo driver to each servo motor of the manipulator M, and a plurality of axes of the manipulator M are rotated. Since the robot controller RC recognizes the current position based on an output from an encoder (not shown) provided in the servo motor of the manipulator M, the robot controller RC can control the tip of the arc welding torch T.

  Note that the position where the stitch pulse welding is performed is calculated in advance by dividing the work line stored in the work program at the set movement pitch. Hereinafter, the position after the division is referred to as a work position. The tip of the arc welding torch T is sequentially guided to the calculated work position, and stitch pulse welding is performed while repeating welding, movement, and cooling described below.

  FIG. 14 is a diagram for explaining a state when stitch pulse welding is performed. The welding wire 57 protrudes from the tip of the arc welding torch T. The shield gas G is always blown from the arc welding torch T at a constant flow rate from the start of welding to the end of welding. Hereinafter, each state at the time of stitch pulse welding will be described.

  FIG. 4A shows a state when an arc is generated. Based on the set welding current and welding voltage, an arc A is generated between the tip of the welding wire 57 and the workpiece W at the work position P1, and the welding wire 57 is melted to form a molten pool Y in the workpiece W. The The arc A is stopped after the set welding time has elapsed since the arc A was generated.

  FIG. 2B shows a state after the arc is stopped. After the arc is stopped, the state after welding is maintained until the set cooling time has elapsed. That is, since the manipulator M and the arc welding torch T are stopped in the same manner as the welding state, only the shielding gas G is blown out from the arc welding torch T. It is cooled and solidified to form a weld mark Y ′.

  FIG. 3C shows a state where the arc welding torch T is moved to the next work position P2. After the elapse of the cooling time, the arc welding torch T is moved to the next work position P2 separated by a preset movement pitch Mp in the work line direction. The moving speed at this time is the set moving speed. The moving pitch Mp is a distance set in advance so that the welding wire 57 is positioned on the outer peripheral side of the welding mark Y ′ after the molten pool Y is solidified as shown in FIG.

  FIG. 4D shows how the arc A is regenerated at the work position P2. The weld pool Y is newly formed at the front end portion of the welding mark Y ', and welding is performed. Thus, in the stitch pulse welding apparatus 51, the state in which the arc is generated and welding is performed, and the state in which the cooling and movement are performed are alternately repeated. As a result, a weld bead is formed so that scales that are welding marks overlap.

  FIG. 15 is a view for explaining a weld bead formed after welding. As shown in the figure, the work line L is divided at a predetermined movement pitch Mp, and work positions P1 to P4... Are calculated. Then, a welding mark Sc is formed at the first work position P1, and a similar welding mark Sc is also formed at the work position P2 separated by the movement pitch Mp in the work line direction Dr. Further welding marks Sc are sequentially formed after the work position P3. Thus, as a result of forming so that a welding trace may overlap, the scale-like weld bead B is formed.

JP-A-6-55268

  As described above, stitch pulse welding uses a thin base metal for arc welding. In general, in order to form a wide weld bead, it is necessary to perform welding with a high welding current or a long welding time. In this case, since the heat input increases, the thin base metal melts away. That is, there is a problem that a wide weld bead cannot be formed by stitch pulse welding.

  Therefore, an object of the present invention is to provide a stitch pulse welding method capable of easily forming a wide weld bead in stitch pulse welding in which a thin base metal is to be welded.

In order to achieve the above object, the first invention provides:
Welding formed by welding at each work position while repeatedly welding at the next work position separated by a predetermined movement pitch after welding is performed by moving the welding torch to the work position on the work line In a stitch pulse welding method in which a weld bead is formed on a workpiece by overlapping marks,
A welding trajectory is generated in a predetermined region having a predetermined width in the direction of the work line and in a direction perpendicular to the work line including the work position, and welding is performed while moving the tip of the welding torch according to the generated weld trajectory. It is a stitch pulse welding method characterized by performing.

  A second invention is the stitch pulse welding method according to the first invention, wherein the welding track is a circular welding track, an elliptical welding track, or a helical welding track.

  In a third aspect of the invention, the circular welding trajectory is calculated based on a predetermined parameter including a circular diameter value or a circular radius value and position and orientation information of the welding torch tip at the working position, and a center position is The stitch pulse welding method according to the second aspect, wherein the welding start position and the welding end position are arranged on the work line and on the track.

  According to a fourth aspect of the present invention, the elliptical welding trajectory is calculated based on predetermined parameters including a major axis value and a minor axis value of the ellipse and position and orientation information of the welding torch tip at the working position, Is a stitch pulse welding method according to the second invention, characterized in that a welding start position and a welding end position are arranged on the work line and on the track.

  A fifth invention is the stitch pulse welding method according to the third or fourth invention, wherein the welding start position and the welding end position are the work positions.

  A sixth invention is the stitch pulse welding method according to the third or fourth invention, wherein the center position is the working position.

  According to a seventh aspect of the invention, the welding is performed for a predetermined welding time while the welding torch is stopped at the central position before the welding torch is moved according to the welding trajectory. This is a stitch pulse welding method.

  According to an eighth aspect of the present invention, the elliptical welding trajectory is based on predetermined parameters including a maximum spiral radius value that is a movement distance in the work line direction and position and orientation information of the welding torch tip at the work position. The stitch pulse welding method according to the second aspect of the invention, characterized in that the calculated work position is a welding start position, and a position separated by the maximum spiral radius value in the work line direction is a welding end position. .

  A ninth invention is the stitch pulse welding method according to the eighth invention, wherein the maximum spiral radius value is the same as the moving pitch.

  According to a tenth aspect of the invention, in any one of the third to ninth aspects, the parameter includes a flattening ratio for deforming the welding track in a direction orthogonal to the work line direction. This is a stitch pulse welding method.

  In an eleventh aspect of the invention, the welding trajectory is generated according to one trajectory pattern selected from a plurality of trajectory patterns including a predetermined circle, ellipse, or spiral. This is a stitch pulse welding method described in the invention.

  According to the first invention, during welding at each work position, a welding track including the work position is generated in a predetermined region having a predetermined width in the work line direction and a direction orthogonal to the work line, and an arc is generated according to the welding track. By performing welding while moving the tip of the welding torch, welding marks can be formed in a large region including the work position while suppressing heat input to the base material. That is, since a welding mark larger than the welding mark formed in the conventional stopped state can be formed, a wide welding bead can be realized.

  According to the second aspect of the invention, since the welding track is a circle, an ellipse, or a spiral, in addition to the effect exhibited by the first aspect, the aesthetic appearance of the weld bead can be improved.

  According to the third invention, the circular welding trajectory is calculated based on the predetermined parameters including the circular diameter value or the circular radius value and the position and orientation information of the arc welding torch tip at the work position, and the center position is set as the work position. The welding start position and the welding end position are arranged on the track. That is, in addition to the effects exhibited by the first and second inventions, circular welding marks can be formed at each work position.

  According to the fourth invention, the elliptical welding trajectory is an elliptical welding trajectory calculated based on the predetermined parameters including the long axis value and the short axis value and the position and orientation information of the arc welding torch tip at the work position. Thus, the center position is arranged on the work line, and the welding start position and the welding end position are arranged on the track. That is, in addition to the effects exhibited by the first and second inventions, an elliptical welding mark can be formed at each work position.

  According to the fifth invention, by setting the welding start position and the welding end position as the work position, after starting welding at the work position, the arc welding torch tip is moved according to the circular welding path or the elliptical welding path. It is made to return to the position. As a result, in addition to the effects exhibited by the first to fourth inventions, a wide weld bead can be realized by the welding marks generated on the circular welding track or the elliptical welding track.

  According to the sixth invention, the center position of the circular welding track or the elliptical welding track is set as the work position. In the fifth invention, a circular welding track or an elliptical welding track offset in the working line direction with the working position as the base end is formed. On the other hand, in the sixth invention, a circular welding track or an elliptical welding track centered on the work position is formed. Thus, in addition to the effects exhibited by the first to fourth inventions, there is an effect that the formation position of the welding mark by the circular welding track or the elliptical welding track is ideal and easy for the operator to understand.

  According to the seventh invention, before the arc welding torch is moved in accordance with the generated circular or elliptical welding orbit, welding is performed for a predetermined welding time while the arc welding torch is stopped at the center position of the orbit. ing. For example, in the case of a circular welding track, if the circle radius value or circle diameter value defined as a parameter is too large, a welding mark may not be formed near the center position of the circle, but first the arc welding torch at the center position. By performing welding for a predetermined welding time while stopping the welding, a welding mark is formed near the center position even if the circle radius or the circle diameter is large. The same applies to an elliptical welding track. That is, in addition to the effects exhibited by the first to sixth inventions, a large welding mark can be more reliably formed.

  According to the eighth invention, the spiral welding trajectory is calculated based on the predetermined parameters including the maximum spiral radius value that is the moving distance in the work line direction and the position and orientation information of the arc welding torch tip at the work position. Is done. Then, after welding is started at the work position, the tip of the arc welding torch is moved according to the spiral welding path so as to reach a position separated by the maximum spiral radius value. As a result, in addition to the effects exhibited by the first and second inventions, a wide weld bead can be realized by the welding marks generated on the spiral welding track.

  According to the ninth aspect, the maximum spiral radius value of the spiral welding track is made the same as the movement pitch that is the movement distance to the next work position. As a result, in addition to the effects exhibited by the first, second and eighth inventions, the teaching man-hour relating to the spiral welding track can be reduced. In addition, the tact time can be shortened. That is, when the maximum spiral radius value is set to a value different from the moving pitch, the spiral welding track is drawn and moved in the working line direction by the maximum helical radius value, and then moved to the next working position separated by the moving pitch. However, if the maximum spiral radius value is the same as the movement pitch, it is not necessary to move to the next work position, and the tact time can be shortened.

  According to the tenth invention, the welding track can be deformed by determining the flatness for changing the welding track in the direction orthogonal to the work line direction as a parameter. That is, in addition to the effects exhibited by the first to ninth inventions, it is possible to realize a welding track that further meets the needs of the operator.

  According to the eleventh invention, it is possible to select a pattern of a welding trajectory that is particularly optimal for realizing a wide range of weld beads, from the predetermined ones. In addition, a bead appearance according to the needs of the operator can be realized.

[Embodiment 1]

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the invention will be described based on examples with reference to the drawings.

  FIG. 1 is a block diagram of a stitch pulse welding apparatus 1 to which a stitch pulse welding method according to the present invention is applied. In the figure, the difference from the prior art FIG. 13 is the robot controller RC and the teach pendant TP as the operation means. In addition, the manipulator M, the welding power source AP, the wire reel 56, the gas cylinder 58, and the like described in the related art are omitted without being illustrated. Hereinafter, the robot controller RC and the teach pendant TP constituting the main part of the present invention will be described.

  The robot controller RC is for causing the manipulator M to control the welding operation. The main control unit 3 serving as the center of the manipulator M, the trajectory calculation of the manipulator M, and the like. The operation control unit 11 for outputting to the motor, the drive command unit 12 for outputting the servo control signal for controlling the rotation of each servo motor of the manipulator M, the hard disk 4 for storing the work program and various parameters, and the temporary calculation area RAM 5, central processing unit CPU 6, welding control unit 13 for controlling welding, and a servo driver (not shown), which are connected via a bus (not shown).

  The teach pendant TP as an operation means includes a display unit 41 that displays various information, and a setting unit 42 that sets various conditions such as a movement target position of the manipulator M and operation parameters. Various conditions and the like input by the setting unit 42 are input to the main control unit 3 of the robot controller RC.

  The main control unit 3 includes a teaching processing unit 20, a display processing unit 21, and an interpretation execution unit 22 that store various conditions input from the setting unit 42. When the necessary conditions at the time of stitch pulse welding are input from the setting unit 42, the teaching processing unit 20 receives a welding condition Tc (welding current, welding voltage), a moving speed Ms, a moving pitch Mp, a cooling time Ct, a track pattern Kp, and The parameter Pm is stored in the hard disk 4. The display processing unit 21 displays various input data on the display unit 41 of the teach pendant TP as necessary. Here, the track pattern Kp is a track pattern when welding is performed on a predetermined area including the work position. The operation control unit 11 described above generates a welding track based on the track pattern Kp and its parameter Pm.

  FIG. 2 is a diagram illustrating an example of a trajectory pattern. A plurality of patterns as shown in the figure are stored in advance in the hard disk 4 as a track pattern group Kg. The orbital pattern group Kg is displayed on the display unit 41 of the teach pendant TP with a name and shape as a set, so that the operator can visually understand the orbital pattern and can select any one of the orbital patterns. it can.

  It is desirable that the track pattern group Kg includes a circle, an ellipse, or a spiral that is particularly optimal for realizing a wide range of weld beads. Furthermore, in the case of a spiral, as shown in FIGS. 5C to 5F, it is further preferable that a subdivided pattern is determined in advance so that the start position, the rotation direction, and the like of the spiral rotation can be imaged.

  Next, the welding trajectory generated by the motion control unit 11 according to the circular or elliptical trajectory pattern will be described. First, a welding line coordinate system that is a reference for generating a welding trajectory will be described.

  FIG. 3 is a diagram for explaining a weld line coordinate system. FIG. 4A shows a case where the arc welding torch T is taught perpendicular to the work line L, and FIG. 4B shows a case where the arc welding torch T is taught with an angle to the work line L. Is shown. In the figure, a work line L is a line connecting a start point Sp and an end point Ep taught to join the workpiece W1 and the workpiece W2. The work line direction Dr is a direction in which the arc welding torch T advances from the start point Sp toward the end point Ep. As in the prior art, the work line L is divided by the movement pitch Mp, and a plurality of work positions are calculated on the work line L. The work position Pn indicates one of a plurality of work positions. Hereinafter, a method for defining a weld line coordinate system in a predetermined region including the work position Pn will be described. The weld line coordinate system is defined in the same manner at other work positions.

  The welding line coordinate system can be defined as follows based on the position and orientation information of the tip of the arc welding torch T at the work position Pn, that is, the work line direction component and the position and orientation coordinate value in the base coordinate system.

  As shown in FIG. 6A, the origin is the working position Pn, the working line direction Dr at the working position Pn is the Z + direction, and a welding wire (not shown) inserted through the arc welding torch T is inserted. A coordinate system in which the retract direction is the X + direction, the Z + direction is orthogonal to the X + direction, and the direction according to the so-called right-handed coordinate system is the Y + direction is defined as a weld line coordinate system. The welding trajectory is calculated on the YZ plane.

  When the arc welding torch T is taught with an angle, the arc welding torch T is placed on a plane H that includes the work position Pn and is orthogonal to the Z axis of the welding line coordinate system, as shown in FIG. And the retract direction of the arc welding torch T ′ after the projection is defined as the X + direction. Others are the same as those in FIG.

  In the above description, the work line L is a straight line. However, when the work line L is an arc, if the tangent direction of the arc is regarded as the work line L, the welding line coordinates are obtained in the same manner as described above. Since the system can be defined, the description is omitted.

  Next, a method for generating a circular welding trajectory and an elliptical welding trajectory based on the weld line coordinate system will be described.

  FIG. 4 is a diagram illustrating a state in which a circular welding trajectory is generated. In this figure, the work position Pn, the arc welding torch T, the work W1, the work W2, the start point Sp, the end point Ep, the work line L, the work line direction Dr, and the XYZ directions of the welding line coordinate system are the same as in FIG. Therefore, explanation is omitted.

  The circular welding trajectory Kc is generated in an area having a predetermined width in the direction perpendicular to the work line direction Dr and the work line L, including the work position Pn. Further, the work position Pn is arranged as a welding start end position Wp. The welding start end position Wp is a position at which welding is started and a position at which the circular welding track Kc is made one round in accordance with the rotation direction Rd and welding is ended.

  The circle radius value Cr and the rotation direction Rd are set as the parameter Pm of the circle welding track. The circle radius value Cr as the predetermined width determines the width of the welding mark (that is, the bead width), and may be a circle diameter value instead of the circle radius value. The rotation direction Rd is for determining which direction to rotate left and right toward the work line direction Dr when the arc welding torch T is moved according to the circular welding trajectory.

  The circular welding trajectory Kc is generated as follows. A position that is separated from the work position Pn in the work line direction Dr by the circle radius value Cr is defined as a circle center position Cc, and a circular orbit having the circle radius value Cr in the YZ plane is calculated. Since this circular orbit is easily calculated based on a known function or the like, the detailed calculation formula and the like will not be described. The work position Pn is set as a welding start end position Wp. Thus, a circular welding trajectory Kc is generated in the work line direction side region including the work position Pn.

  It is also possible to generate an elliptical weld track in the same manner as described above. That is, instead of the above-described circle radius value Cr, the length radius value in the left-right direction and the length radius value in the traveling direction of the elliptical welding track are provided as parameters Pm. The left-right direction length radius value and the traveling direction length radius value may be the respective diameter values. These correspond to the major axis value and the minor axis value of the so-called ellipse necessary for generating the elliptical welding trajectory.

  Then, the position separated from the work position Pn by the traveling direction length radius value in the working line direction Dr is defined as the ellipse center position Cc, and the ellipse having the left and right direction length radius values and the traveling direction length radius value on the YZ plane. Calculate the trajectory. Since this elliptical orbit is also easily calculated based on a known function or the like, the detailed calculation formulas and the like will not be described. The work position Pn is set as a welding start end position Wp. Thus, the elliptical welding trajectory Kd is generated in the work line direction side region including the work position Pn.

  Next, the operation when performing stitch pulse welding will be described. FIG. 5 is a flowchart showing the flow of processing during stitch pulse welding.

  In step S1, the work position is calculated by dividing the work line L by the movement pitch Mp. If the first work position is P1, the work position P1 is the start point Sp shown in FIG.

  In step S2, the arc welding torch T is moved to the work position P1.

  In step S3, the welding line coordinate system at the work position P1 is set by the method described above.

  In step S4, a welding track having the work position P1 as the welding start end position Wp is generated by the method described above. Further, an interpolation calculation for moving the arc welding torch T according to the generated welding trajectory is performed. That is, in the case of the circular welding track Kc, the welding length (circumferential length) of the circular welding track Kc is geometrically calculated based on the circular radius value Cr, and based on the welding length and the set moving speed. A coordinate value in the weld line coordinate system to be taken in each interpolation cycle is calculated, converted into a coordinate value in the base coordinate system by coordinate conversion, and further subjected to inverse conversion operation to perform a movement target of each joint of the manipulator M Calculate the value. In the case of the elliptical welding track Kd, the welding length (elliptical circumference) of the elliptical welding track Kd is geometrically calculated on the basis of the length radius in the left-right direction and the length radius in the traveling direction. The movement target value of each joint of the manipulator M is calculated. The moving speed may be the moving speed Ms set as the stitch pulse welding condition, or the welding speed can be set as the track pattern parameter Pm, and this welding speed is used. May be.

  In step S5, welding is started, the arc welding torch T is moved according to the welding path, and the welding start end position Wp is reached. Although not shown, after the welding is finished at the welding start end position Wp, the welding mark is cooled during the cooling time Ct set in a state where the arc welding torch T is stopped, as in the prior art. Processing is performed.

  In step S6, it is determined whether or not the current work position is the end point Ep. If the current work position is the end point Ep, the flow ends. If the current work position is not the end point Ep, the process returns to step S2. After returning to step S2, steps S2 to S6 are repeated at each of the next work positions P2 to Pn separated by the movement pitch Mp.

  As described above, during welding at each work position, a welding track is generated in a predetermined region including the work position and having a predetermined width in the work line direction and the direction perpendicular to the work line, and the arc welding torch By performing welding while moving the tip, it is possible to form a welding mark in a large region including the work position while suppressing heat input to the base material. That is, since a welding mark larger than the welding mark formed in the conventional stopped state can be formed, a wide welding bead can be realized.

  In addition to the above effects, the appearance of the weld bead can be improved by making the welding track circular, elliptical, or spiral.

  In addition to the above effects, a bead appearance that meets the needs of the operator can be achieved by enabling the selection of the optimum welding track pattern to achieve a wide range of welding beads. can do.

  The circle welding track is calculated based on predetermined parameters including the circle diameter value or circle radius value and the position and orientation information of the arc welding torch tip at the work position, and the center position of the track is arranged on the work line. In addition, a welding start position and a welding end position are arranged on the track. That is, in addition to the above effects, a circular welding mark can be formed at each work position.

  The elliptical welding trajectory is calculated based on predetermined parameters including the long axis value and the short axis value and the position and orientation information of the arc welding torch tip at the work position, the center position is arranged on the work line, and A welding start position and a welding end position are arranged on the track. That is, in addition to the above effects, an elliptical welding mark can be formed at each work position.

  Also, by setting the welding start position and welding end position as the work position, after starting welding at the work position, the arc welding torch tip is moved according to the circular welding path or the elliptical welding path and returned to the working position. ing. In this way, in addition to the above effects, a wide weld bead can be realized by the welding marks generated on the circular welding track or the elliptical welding track.

[Embodiment 2]
Next, a second embodiment of the present invention will be described. In the first embodiment, the welding trajectory is generated on the work line direction side of the work position Pn. However, in the second embodiment, the welding trajectory is generated around the work position Pn.

  FIG. 6 is a diagram illustrating a state in which a circular welding trajectory is generated around the work position Pn in the second embodiment. In FIG. 4, the difference from FIG. 4 is that the work position Pn is set to the center position Cc ′ of the circular welding track Kc ′. Others are the same as those in the first embodiment, and thus the description thereof is omitted.

  The circular welding trajectory Kc ′ is generated as follows. First, a circular orbit having a circular radius value Cr in the YZ plane is calculated with the work position Pn as the center position Cc ′. Then, the welding start end position Wp ′ is calculated at a position on the circular track that is separated from the work position Pn by the circle radius value Cr in the direction opposite to the work line direction Dr. Thus, a circular welding trajectory Kc ′ is generated in the region around the work position Pn.

  Similarly to the first embodiment, it is also possible to generate an elliptical welding trajectory around the work position Pn. That is, instead of the circle radius value Cr described above, the length radius and the length radius of the elliptical welding track are provided as parameters Pm, the working position Pn is set as the center position Cc ′, and the length in the left and right direction on the YZ plane is set. An elliptical orbit having a radius and a traveling direction length radius is calculated. Then, a welding start end position Wp ′ is calculated at a position on the elliptical track that is separated from the work position Pn by the length in the traveling direction in the direction opposite to the work line direction Dr. Thus, an elliptical welding trajectory Kd 'is generated around the work position Pn. Further, as in the first embodiment, an interpolation calculation for moving the arc welding torch T according to the welding trajectory is performed.

  Next, the operation when performing stitch pulse welding will be described. FIG. 7 is a flowchart showing the flow of processing during stitch pulse welding in the second embodiment.

  In step S1, the work position is calculated by dividing the work line L by the movement pitch Mp. If the first work position is P1, the work position P1 is the start point Sp shown in FIG.

  In step S2, the welding line coordinate system at the work position P1 is set by the method described above.

  In step S3, a welding track having the work position P1 as the center position and having the welding start end position Wp ′ on the work line L is generated by the method described above. Further, as in the first embodiment, an interpolation calculation for moving the arc welding torch T according to the welding trajectory is performed.

  In step S4, the arc welding torch T is moved to the welding start end position Wp ′ on the welding track.

  In step S5, welding is started, and the arc welding torch T is moved according to the welding trajectory to reach the welding start end position Wp ′. Further, although not shown, after the welding is ended at the welding start end position Wp ′, the welding mark is not changed during the cooling time Ct set in a state where the arc welding torch T is stopped as in the conventional technique. A cooling process is performed.

  In step S6, it is determined whether or not the current work position is the end point Ep. If the current work position is the end point Ep, the flow ends. If the current work position is not the end point Ep, the process returns to step S2. After returning to step S2, steps S2 to S6 are repeated at each of the next work positions P2 to Pn separated by the movement pitch Mp.

  As described above, in the second embodiment, the center position of the circle or ellipse is set as the work position. In the first embodiment, a circle or an ellipse that is offset in the work line direction with the work position as the base end is formed. However, by setting the work position as the center position of the circle or the ellipse, the work position is set as the center. A circle or ellipse will be formed. As a result, there is an effect that the formation position of the welding mark by a circle or an ellipse is ideal and easy for the operator to understand.

  In the above-described second embodiment, the arc welding torch may be moved according to the welding track after being once welded at the center position of the welding track. Hereinafter, the form which once welds in the center position of a welding track | orbit is demonstrated.

  FIG. 8 is a flowchart in the case where the arc welding torch is moved according to the welding trajectory after once welding at the center position of the welding trajectory. In the figure, steps S1 to S4 and S6 indicated by dotted lines are the same steps as those in FIG. Hereinafter, steps S4 'and S5 indicated by solid lines will be described.

  In step S4 ', welding is performed for a predetermined welding time while the arc welding torch T is stopped at the work position. This welding time is configured so that it can be set in advance as a condition for stitch pulse welding.

  In step S5, the arc welding torch T is moved to the welding start end position Wp ′ on the welding track. In this movement, the arc may be stopped before the movement, or may be moved to the welding start end position Wp ′ while the arc is generated. Then, after moving along the welding trajectory, the welding start end position Wp ′ is reached.

  As described above, before the arc welding torch is moved in accordance with the generated circular or elliptical welding orbit, welding is performed at a center position of the welding orbit for a predetermined welding time while the arc welding torch is stopped. For example, in the case of a circular welding track, if the circle radius value or circle diameter value defined as a parameter is too large, a welding mark may not be formed near the center position of the circle, but first the arc welding torch at the center position. By performing welding for a predetermined welding time while stopping the welding, a welding mark is formed near the center position even if the circle radius or the circle diameter is large. The same applies to an elliptical welding track. That is, a large welding mark can be formed more reliably.

[Embodiment 3]
Next, a third embodiment of the present invention will be described. In the first and second embodiments, the circular welding trajectory Kc (Kc ′) or the elliptical welding trajectory Kd (Kd ′) is generated on the work line direction side of the work position Pn or around the work position Pn. Then, a spiral welding track that spirally rotates outward from the work position Pn is generated.

  FIG. 9 is a view for explaining a spiral welding track. This figure is a view of the YZ plane of the welding line coordinate system described in the first embodiment as seen from the X + direction, and shows a state in which the spiral welding trajectory Kr is drawn on the YZ plane. In the figure, the work position Pn, the work line L, the work line direction Dr, and the rotation direction Rd are the same as those given the same reference numerals in FIG.

  The spiral welding trajectory Kr shown in the figure is generated as follows. First, the work position Pn is set as the welding start position Ws, and a spiral trajectory having the maximum spiral radius value Sr in the YZ plane is calculated. A spiral trajectory refers to a so-called Archimedean spiral whose radius increases in proportion to the angle. The Archimedean spiral formula is expressed by a radius R = aθ (a is a constant, θ is a rotation angle). That is, a quadrant (0π, 1 / 2π, π, 3 / 2π) as shown in the figure is determined around the work position Pn, and the rotation start angle, rotation end angle, and rotation end radius (= maximum spiral radius value) By giving Sr) as the parameter Pm, the spiral trajectory can be easily calculated. In the case of the figure, the rotation start angle is 1 / 2π, the rotation end angle is 4π, and the maximum spiral radius value is Sr. Based on these, the constant a is calculated, and the radius R at each rotation angle is also calculated. That is, the coordinate value in the weld line coordinate system to be taken on the spiral trajectory can be easily calculated.

  FIG. 10 is a diagram illustrating an example of a spiral trajectory. For example, by changing the rotation start angle and the rotation end angle, the spiral welding trajectory Kr as shown in FIGS. FIGS. 9A to 9F show examples in which the rotation start angle and the rotation end angle are changed. By adding the radius value at the start of rotation to these, the spiral trajectory can be made more flexible. Can be determined. That is, the above-mentioned Archimedes spiral formula is set to radius R = Ri + aθ. Ri is a radius value at the start of rotation. FIG. 5G shows a spiral trajectory in consideration of the radius value Ri at the start of rotation in FIG.

  Returning to FIG. 9, the welding end position We is calculated at a position on the spiral track that is separated from the work position Pn by the maximum spiral radius value Sr in the work line direction Dr. Thus, the spiral welding track Kr is generated in the region around the work position Pn.

  The maximum spiral radius value Sr may be the same value as the movement pitch Mp. FIG. 11 is an image diagram of a weld bead for explaining the relationship between the maximum spiral radius value and the movement pitch. FIG. 5A shows a weld bead when the maximum spiral radius value Sr is the same value as the movement pitch Mp, and FIG. 5B shows a weld bead when the maximum spiral radius value Sr is shorter than the movement pitch Mp. (C) shows the weld bead when the maximum spiral radius value Sr is longer than the movement pitch Mp. In FIGS. 5B and 5C, it is necessary to draw the spiral welding trajectory Kr and move it in the working line direction Dr by the maximum helical radius value Sr, and then move it to the next working position separated by the moving pitch Mp. However, when the maximum spiral radius value Sr is made equal to the movement pitch Mp as shown in FIG. 5A, the movement to the next work position is not necessary.

  Next, the operation when performing stitch pulse welding will be described. FIG. 12 is a flowchart showing a flow of processing at the time of stitch pulse welding in the third embodiment.

  In step S1, the work position is calculated by dividing the work line L by the movement pitch Mp. If the first work position is P1, the work position P1 is the start point Sp shown in FIG.

  In step S2, the arc welding torch T is moved to the work position P1.

  In step S3, the welding line coordinate system at the work position P1 is set by the method described above.

  In step S4, the helical welding trajectory Kr having the work position P1 as the welding start position Ws and the position separated by the maximum spiral radius value Sr in the work line direction Dr as the welding end position We is generated by the method described above. Further, an interpolation calculation is performed to move the arc welding torch T according to the helical welding trajectory Kr. That is, the welding length (spiral length) of the spiral welding track Kr is calculated geometrically based on the rotation start angle, rotation end angle, maximum spiral radius value Sr, rotation start radius value, and the like of the spiral. Based on the set moving speed, the coordinate value to be taken in each interpolation cycle is calculated, and the movement target value of each joint of the manipulator M is calculated as in the first embodiment. As the moving speed, the moving speed Ms set as the condition of the stitch pulse welding may be used, or the welding speed can be set as the parameter Pm of the track pattern, and this welding speed may be used. good.

  In step S5, welding is started, the arc welding torch T is moved according to the spiral welding trajectory Kr, and the welding start end position Wp is reached. Further, although not shown, after the welding is finished at the welding start end position Wp, the welding mark is cooled during the cooling time Ct set in a state where the arc welding torch T is stopped as in the prior art. Processing is performed.

  In step S6, it is determined whether or not the current work position is the end point Ep. If the current work position is the end point Ep, the flow ends. If the current work position is not the end point Ep, the movement distance to the next work position is calculated by the difference between the maximum spiral radius value Sr and the movement pitch Mp, and the process returns to step S2. After returning to step S2, steps S2 to S6 are repeated at each of the next work positions P2 to Pn.

  As described above, at each work position where stitch pulse welding is performed, welding is started at the work position Pn, and the arc welding torch T is moved while drawing the spiral welding trajectory Kr in the direction of the rotational direction Rd, from the work position Pn. It reaches the welding end position Pe separated by the maximum spiral radius value Sr in the direction of the working line direction Dr.

  As described above, the helical welding trajectory is calculated based on the predetermined parameters including the maximum helical radius value that is the moving distance in the working line direction and the position and orientation information of the arc welding torch tip at the working position. Then, after welding is started at the work position, the tip of the arc welding torch is moved according to the spiral welding path so as to reach a position separated by the maximum spiral radius value. As a result, a wide weld bead can be realized by the welding marks generated on the spiral welding track.

  Further, the maximum spiral radius value of the spiral welding track is made the same as the movement pitch that is the movement distance to the next work position. In this way, in addition to the above effects, the teaching man-hours related to the spiral welding track can be reduced. In addition, the tact time can be shortened. That is, when the maximum spiral radius value is set to a value different from the moving pitch, the spiral welding track is drawn and moved in the working line direction by the maximum helical radius value, and then moved to the next working position separated by the moving pitch. However, if the maximum spiral radius value is the same as the movement pitch, it is not necessary to move to the next work position, and the tact time can be shortened.

  Although the embodiments have been described above, in each embodiment, the flatness ratio for deforming the welding track in a direction orthogonal to the work line direction may be included in the parameter Pm of each track pattern. As for this flatness, it is desirable that the right flatness and the left flatness can be set on the right side and the left side in the working line direction, respectively. This makes it possible to deform the welding track. Particularly, for example, as shown in FIG. 9, when the rotational direction Rd is right toward the work line direction Dr, the right side track is slightly larger than the left side track toward the work line direction Dr. Therefore, by setting the flatness ratio, it is possible to prevent the bias of the spiral welding track. That is, it is possible to realize a welding track that further meets the needs of the operator.

  In each of the above embodiments, the welding trajectory is generated at each work position. However, the welding trajectory is generated only at the first work position, and this is used again at the subsequent work positions. You may comprise.

1 is a block diagram of a stitch pulse welding apparatus 1 to which a stitch pulse welding method according to the present invention is applied. It is a figure which shows the example of several predetermined orbital patterns. It is a figure for demonstrating a weld line coordinate system. In Embodiment 1, it is a figure which shows a mode that the circular welding track | orbit was produced | generated in the predetermined area | region containing a work position. 5 is a flowchart showing a flow of processing at the time of stitch pulse welding in the first embodiment. In Embodiment 2, it is a figure which shows a mode that the circular welding track | orbit was produced | generated around the working position Pn. In Embodiment 2, it is a flowchart which shows the flow of the process at the time of stitch pulse welding. In Embodiment 2, it is a flowchart in the case of moving an arc welding torch according to a welding track after once welding in the center position of a welding track. In Embodiment 3, it is a figure for demonstrating a helical welding track | orbit. In Embodiment 3, it is a figure for demonstrating the kind of spiral welding track | orbit. In Embodiment 3, it is an image figure of the weld bead for demonstrating the relationship between the largest spiral radius value and a movement pitch. In Embodiment 3, it is a flowchart which shows the flow of the process at the time of stitch pulse welding. It is the figure which showed the conventional stitch pulse welding apparatus. It is a figure for demonstrating a state when performing stitch pulse welding. It is a figure for demonstrating the weld bead formed after welding construction.

Explanation of symbols

1 Stitch pulse welding device 3 Main control unit 4 Hard disk 5 RAM
6 CPU
DESCRIPTION OF SYMBOLS 11 Operation control part 12 Drive command part 13 Welding control part 20 Teaching process part 21 Display process part 22 Interpretation execution part 41 Display part 42 Setting part 51 Conventional stitch pulse welding apparatus 52 Conduit cable 53 Upper arm 54 Lower arm 55 Wrist part 56 Wire reel 57 Welding wire 58 Gas cylinder A Arc AP Welding power source B Weld bead Cc Center position Cc 'Center position Cr Circle radius Ct Cooling time Dr Work line direction Ep End point Ew Projection length G Shield gas H Z axis of welding line coordinate system Plane Kc orthogonal to the circular welding track Kc ′ circular welding track Kd elliptical welding track Kd ′ elliptical welding track Kg track pattern group Kr spiral welding track Kp track pattern L work line M manipulator Mp moving pitch Ms moving speed P1 working position P2 working position P3 Work position P4 Work position Pn Work position Pe Welding end Position Pm Parameter RC Robot controller Rd Direction of rotation Sc Weld mark Sp Start point Sr Maximum spiral radius value T Arc welding torch Tc Welding condition TP Teach pendant W Work W1 Work W2 Work We Weld end position Wp Weld start end position Wp 'Weld start End position Y Weld pool Y 'Weld mark

Claims (11)

Welding formed by welding at each work position while repeatedly performing welding at the next work position separated by a predetermined movement pitch after performing welding by moving the welding torch to the work position on the work line In a stitch pulse welding method in which a weld bead is formed on a workpiece by superimposing marks,
A welding trajectory is generated in a predetermined region having a predetermined width in the work line direction and the direction orthogonal to the work line including the work position, and welding is performed while moving the tip of the welding torch according to the generated weld trajectory. A stitch pulse welding method characterized by being performed.   The stitch pulse welding method according to claim 1, wherein the welding track is a circular welding track, an elliptical welding track, or a helical welding track.   The circular welding trajectory is calculated based on predetermined parameters including a circular diameter value or a circular radius value and position and orientation information of the welding torch tip at the working position, and a center position is arranged on the working line; 3. The stitch pulse welding method according to claim 2, wherein a welding start position and a welding end position are arranged on the track.   The elliptical welding trajectory is calculated based on predetermined parameters including a major axis value and a minor axis value of the ellipse and position and orientation information of the welding torch tip at the working position, and a center position is arranged on the working line. The stitch pulse welding method according to claim 2, wherein a welding start position and a welding end position are arranged on the track.   The stitch pulse welding method according to claim 3 or 4, wherein the welding start position and the welding end position are the work positions.   The stitch pulse welding method according to claim 3 or 4, wherein the center position is the work position.   The stitch pulse welding method according to claim 6, wherein welding is performed for a predetermined welding time while the welding torch is stopped at the center position before the welding torch is moved according to the welding trajectory.   The spiral welding trajectory is calculated based on a predetermined parameter including a maximum spiral radius value that is a moving distance in the work line direction and position and orientation information of the welding torch tip at the work position, and the work position The stitch pulse welding method according to claim 2, wherein a welding start position is defined as a welding end position at a position spaced apart by the maximum spiral radius value in the work line direction.   The stitch pulse welding method according to claim 8, wherein the maximum spiral radius value is the same as the moving pitch.   The stitch pulse welding method according to any one of claims 3 to 9, wherein the parameter includes a flatness ratio for deforming the welding track in a direction orthogonal to the working line direction.   11. The welding trajectory is generated according to one trajectory pattern selected from a plurality of trajectory patterns including a predetermined circle, ellipse, or spiral. The stitch pulse welding method as described.

Images