JP2013035018A - Tandem arc welding method and tandem arc welding system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem with a conventional tandem arc welding for only performing weaving integrated with a welding torch, wherein the weaving can not be performed by changing the weaving amplitude of a preceding electrode and a succeeding electrode, for example, even if desired such that the preceding electrode performs a weaving welding of a small amplitude and the succeeding electrode performs the weaving welding of a large amplitude.SOLUTION: The method includes: a step of determining a substantially perpendicular rotary shaft to a line for connecting a predetermined control point of the preceding electrode tip to draw a weaving trajectory of the amplitude individually set for each of the preceding electrode and the succeeding electrode with a predetermined control point of the succeeding electrode tip; a step of calculating a rotation angle by which the welding torch is rotated centering on the rotary shaft, and the preceding electrode and the succeeding electrode perform the reciprocating movement of a specified amplitude; and a step of controlling the welding torch into the reciprocating movement at the rotation angle centering on the rotary shaft.

Description

  The present invention relates to a tandem arc welding method and a tandem arc welding system for performing a predetermined operation by an operation program and welding an object to be welded under a predetermined welding condition.

  In the production of various welded structures, high weld welding is performed to improve productivity. In recent years, a two-electrode integrated welding torch (hereinafter referred to as a “tandem torch”) that feeds two welding wires from one welding torch or a single welding wire is used to further advance this. A welding method is used in which two single electrode welding torches to be fed are arranged close to each other. These are called tandem arc welding.

  Usually, a welding system used at a production site is mainly configured by a device that moves by mounting a welding torch such as a manipulator of a welding robot. Then, automatic welding is performed by performing a predetermined operation at a predetermined speed according to the operation program and executing a predetermined welding control. The same applies to a welding system that performs tandem arc welding. In that case, in the portion where tandem arc welding is performed, the operation program is created so that the two welding wires are in a positional relationship in which the two welding wires are generally arranged in the front-rear direction.

  FIG. 1 shows a simplified configuration example of a tandem arc welding system using a tandem torch 50. The schematic configuration and operation of the tandem arc welding system will be described with reference to FIG. The tandem torch 50 is mounted on a manipulator of a welding robot (not shown), and moves along a predetermined welded portion of the workpiece 60 to be welded. The manipulator of the welding robot is connected to the controller 20.

  Two welding machines, a welding machine 30 and a welding machine 40, are connected to the controller 20. A welding wire feeding device (not shown) is connected to each of the welding machine 30 and the welding machine 40, and two welding wires (not shown) are supplied to the tandem torch 50. In the tandem torch 50, the two welding wires are supplied through two contact tips (not shown).

  Each contact tip is connected to the output terminal of the welding machine 30 and the welding machine 40 via the power cable 31 and the power cable 42, and the electric power from the welding machine 30 and the welding machine 40 is supplied to each welding wire. The workpiece 60 to be welded is connected to the ground terminals of the welding machine 30 and the welding machine 40 via the ground cable 32 and the ground cable 41. When an arc is generated between the welding wire and the workpiece 60 to be welded, a circuit through which a welding current flows is formed.

  The controller 20 holds an operation program and welding conditions, and transfers commands and parameters to the welding machine 30 and the welding machine 40 through the control line 33 and the control line 43 in a timely manner according to the operation program. . The welding machine 30 and the welding machine 40 supply each welding wire with a wire feeding amount corresponding to a parameter commanded from the controller 20 by controlling a welding wire feeding device connected thereto. In this manner, the tandem arc welding system performs predetermined welding at a predetermined location of the workpiece 60 to be welded.

  Next, a state where tandem arc welding is performed will be described with reference to FIG. FIG. 2 shows a state in which tandem arc welding is performed from the right to the left in FIG. 2 (arrow direction in the figure) by the tandem torch 50 (see FIG. 1). In the following description, the word “preceding” is attached to the front of the welding direction, and the word “following” is attached to the rear.

  In FIG. 2, two contact chips, that is, a leading contact chip 51 and a trailing contact chip 52 are arranged in the nozzle 58 of the tandem torch 50. A leading welding wire 53 is supplied to the leading contact tip 51, and a trailing welding wire 54 is supplied to the trailing contact tip 52.

  The welding wire protrudes from the contact tip by a predetermined length. The welding robot performs control by providing a control point at a position corresponding to a predetermined length of the tip of the welding wire. In general, since the welding wire is also referred to as an electrode, hereinafter, the leading welding wire 53 is referred to as a leading electrode 53 and the trailing welding wire 54 is referred to as a trailing electrode 54. The distance between the control point at the tip of the leading electrode 53 and the control point at the tip of the trailing electrode 54 is referred to as an interelectrode distance.

  In FIG. 2, the leading electrode 53 is supplied with power from the leading electrode welding machine 30 or the welding machine 40 via the leading contact tip 51, and generates a leading arc 55 between the leading electrode 53 and the workpiece 60 to be welded. Let The leading electrode 53 and the workpiece 60 to be welded are melted by the arc heat, and molten metal is supplied to the molten pool 61.

  At the same time, the trailing electrode 54 is supplied with electric power from the welding electrode 30 or the welding machine 40 for the trailing electrode via the trailing contact tip 52, and the trailing arc is interposed between the trailing electrode 54 and the workpiece 60 to be welded. 56 is generated. The trailing electrode 54 and the workpiece 60 to be welded are melted by the arc heat, and the molten metal is supplied to the molten pool 61.

  The leading electrode 53 and the trailing electrode 54 are fed continuously, and the tandem torch 50 moves at a predetermined speed, thereby moving the molten pool 61. Later, the molten metal hardens and forms a weld bead 62. In this way, the welding process is performed.

  In tandem arc welding, the welding performed by the leading electrode and the welding performed by the trailing electrode have different roles in the welding process. As an example, in FIG. 2, the molten metal in the molten pool 61 formed by the leading arc 55 generated from the leading electrode 53 tends to flow backward by the arc force of the leading arc 55. On the other hand, the arc force of the trailing arc 56 generated from the trailing electrode 54 pushes it back to stabilize the molten pool 61 by this balance. In addition to this, each method has a role in how to contribute to the penetration and how to contribute to the shape of the weld bead 62. Thus, since both electrodes are not performing the same welding, it is necessary to perform welding by giving different welding condition parameters to the welding machine 30 and the welding machine 40.

  In general, in arc welding, welding is often performed while weaving the torch in order to optimize the penetration shape and bead shape (this is called “weaving welding”). This point is the same in tandem arc welding.

  For example, Patent Document 1 discloses an invention related to copying control of a weld line by a welding robot of a tandem arc welding system. As a premise of the invention, it is shown that a tandem torch attached to a welding robot is welded by weaving left and right using a welding robot.

  As described above, in a manipulator of a welding robot, welding while weaving a torch attached to the tip is a widely spread technique and has been widely used. As this torch, weaving can be performed even with a tandem torch, and it can be read from Patent Document 1 that it is used as a basic technique.

JP 2008-93670 A

  However, conventional tandem arc welding systems only perform the same weaving as normal weaving. For this reason, there has been a problem that weaving suitable for tandem arc welding is not necessarily performed.

  For example, the leading electrode is subjected to weaving welding with small amplitude to ensure sufficient penetration, or welding without weaving, and the trailing electrode is subjected to weaving welding with relatively large amplitude for bead shape shaping. Sometimes you want to. However, in the conventional tandem arc welding system, since weaving is performed only with the torch as an integral body, the weaving amplitude of the leading electrode and the trailing electrode is the same, and weaving cannot be performed by changing the weaving amplitude.

  In view of the above, an object of the present invention is to provide a tandem arc welding method and a tandem arc welding system capable of performing weaving by changing the weaving amplitude of the leading electrode and the trailing electrode.

  In order to solve the above-described problems, the tandem arc welding method of the present invention draws a weaving trajectory having an amplitude set individually for each of the preceding electrode and the succeeding electrode, so that a predetermined control of the leading electrode tip is performed. Determining a rotation axis substantially perpendicular to a line connecting the point and a predetermined control point at the tip of the succeeding electrode, and rotating the welding torch around the rotation axis, so that the preceding electrode and the succeeding electrode are rotated. Includes a step of calculating a rotation angle for performing a reciprocating operation with a specified amplitude, and a step of performing a control for reciprocating the welding torch at the rotation angle about the rotation axis.

  In the tandem arc welding method of the present invention, in addition to the above, the amplitude of the reciprocating motion of the preceding electrode is smaller than the amplitude of the reciprocating motion of the trailing electrode.

  The tandem arc welding system of the present invention provides a predetermined control point of the leading electrode tip and a trailing electrode tip for drawing a weaving trajectory having a separately set amplitude for each of the leading electrode and the trailing electrode. A rotation axis determination unit that determines a rotation axis that is substantially perpendicular to a line connecting a predetermined control point, and a welding torch that rotates around the rotation axis, and the amplitude that the leading electrode and the trailing electrode are designated A rotation angle calculation unit that calculates a rotation angle for performing the reciprocating operation, and a control unit that reciprocates the welding torch at the rotation angle about the rotation axis.

  In the tandem arc welding system of the present invention, in addition to the above, the amplitude of the reciprocating motion of the leading electrode is smaller than the amplitude of the reciprocating motion of the trailing electrode.

  As described above, the present invention provides a tandem arc welding method and a tandem arc welding system capable of performing weaving welding suitable for tandem arc welding by causing the leading electrode and the trailing electrode to perform reciprocating motions with different amplitudes. provide.

Diagram showing schematic configuration of tandem arc welding system Schematic showing the welding state with a tandem torch (A) Schematic diagram showing the weaving mechanism in the first embodiment of the present invention (b) Schematic diagram showing the weaving mechanism in the first embodiment of the present invention Schematic diagram showing the weaving operation in the first embodiment of the present invention. Schematic diagram showing a method of determining a weaving surface in the first embodiment of the present invention.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to FIGS. 1 and 2 have already been described, and in the following, description will be made with reference to FIGS.

(Embodiment 1)
The schematic configuration of the tandem arc welding system according to the first embodiment is the same as that shown in FIG. Further, the welding state of the tandem arc welding of the first embodiment is the same as that in FIG. Accordingly, the same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals and detailed description thereof is omitted. The first embodiment will be described with reference to FIGS. 3 to 5.

  FIG. 3 is a diagram for explaining the mechanism of tandem arc welding according to the first embodiment. As shown in FIG. 3A, in the following description, the leading end of the leading electrode 53 and the leading end of the trailing electrode 54 in a non-welded state, and inside the leading arc 55 and the trailing arc 56 during welding. It is assumed that there is a control point a for the leading electrode and a control point b for the succeeding electrode. As will be described below, the control point a of the leading electrode and the control point b of the succeeding electrode are points that draw each weaving locus. And the control point a and the control point b are predetermined.

  FIG. 3B is a diagram illustrating the z-z arrow view of FIG. 3A, and the control point a of the leading electrode (hereinafter also referred to as “point a”) and the control point b ( Hereinafter, it is also referred to as “point b”. Here, a line segment connecting the points a and b is indicated by a line segment l, and the length thereof is a distance d. Then, a line segment m1 perpendicular to the line segment l is considered on the plane f where the points a and b exist (the paper surface in the case of FIG. 3B), and the midpoint thereof is made coincident with the point a. Similarly, a line segment m2 perpendicular to the line segment l is considered, and its midpoint coincides with the point b.

  Here, the intersection of the line segment j connecting one end of the line segment m1 and one end of the line segment m2 with the line segment l is the length of the line segment m1 and the line segment m2. This is a point obtained by internally dividing the line segment l by the ratio of lengths, and this is defined as point o. A line segment k connecting the other ends of the line segment m1 and the line segment m2 also intersects the line segment l at the point o. The angle r formed by the line segment j and the line segment l (or the line segment k and the line segment l) is an angle having a relationship of tan (r) = (m1 + m2) / 2d.

  When an axis perpendicular to the line segment l on the plane f is set from the point o and the line segment l is reciprocally rotated between the angles + r and -r around the axis, the points a and b are converted into the line m1 and the line Draw an arc that touches the minute m2. Here, the lengths of the chords of both arcs are different from the lengths of the line segment m1 and the line segment m2, but the difference is small. Therefore, in the following, it is assumed that the chord lengths of both arcs are equal to the lengths of the line segment m1 and the line segment m2.

  When the reciprocating rotation operation in which the control point (point a) of the leading electrode 53 and the control point (point b) of the succeeding electrode 54 draw an arc is regarded as the weaving operation of the tandem torch 50, the chord of each arc is the weaving amplitude The length of the line segment m1 is the amplitude of the leading electrode 53, and the length of the line segment m2 is the amplitude of the trailing electrode 54. These arcs are weaving trajectories drawn on the plane f. For this reason, the plane f is called a weaving plane.

  If the tandem torch 50 is moved in the welding progress direction and at this time moved so as to draw a weaving locus on the same weaving plane f, weaving of the locus as shown in FIG. 4 is performed. The upper side of FIG. 4 is the weaving locus drawn by the point a, and the lower side is the weaving locus drawn by the point b. Here, m1 and m2 of each locus are weaving amplitudes. Incidentally, the distance d indicates the interelectrode distance between the leading electrode 53 and the trailing electrode 54.

  When the weaving plane f is in the horizontal plane, the weaving trajectory drawn by the points a and b is drawn on the horizontal plane as a result of the weaving operation. In the first embodiment, the weaving plane f is not necessarily limited to the horizontal plane. For example, the points a and b may not be in the horizontal plane, that is, the line segment l may be inclined from the horizontal. Further, the rotation axis set up from the point o can be set up in any direction from the line segment l. However, if the rotation axis and the line segment l are not perpendicular, the weaving amplitude will be different from the specified value.

  When the weaving amplitude of the preceding electrode is designated as 0 (zero), the point o coincides with the point a. That is, the rotation axis passes through the control point a of the preceding electrode, the leading electrode does not perform weaving, and only the succeeding electrode performs weaving. The same applies when the weaving amplitude of the trailing electrode is designated as zero. Thus, by changing the designation of the weaving amplitude of the leading electrode and the trailing electrode, various weaving methods can be designated, and weaving suitable for desired welding can be performed.

  The weaving amplitude and the weaving plane are determined based on information registered in advance in the operation program. For example, the weaving amplitude may be specified as a parameter by a program. For example, as shown in FIG. 5, the weaving plane f is perpendicular to the two directions x, y, and x and y, which are obtained by projecting the weld line direction formed by the teaching point on the weld line registered in the program onto the horizontal plane. On a coordinate system that can be set in a simple direction y, the tilt parameter h1 and the tilt parameter h2 can be designated.

  As described above, according to the first embodiment, the rotation axis for weaving is determined as described above according to the designated weaving plane and the designated weaving amplitude, and the rotation angle is calculated. Actually, weaving is performed by reciprocating the determined rotation axis and the calculated rotation angle.

  Here, the controller 20 which comprises a tandem arc welding system is provided with the memory | storage part, the rotating shaft determination part, the rotation angle calculation part, and the control part.

  The storage unit stores an operation program for operating the tandem arc welding system.

  The rotation axis determination unit applies a line connecting the control point of the leading electrode tip and the control point of the trailing electrode tip to draw a weaving locus having an amplitude set individually for each of the leading electrode and the trailing electrode. An approximately vertical rotation axis is determined based on an operation program.

  The rotation angle calculation unit rotates the tandem torch 50 around the rotation axis determined by the rotation axis determination unit, and determines the rotation angle for performing the reciprocating operation with the amplitude specified by the preceding electrode and the succeeding electrode. Is calculated based on

  The control unit is configured to determine the rotation axis determined by the rotation axis determination unit based on the operation program stored in the storage unit, the rotation axis determined by the rotation axis determination unit, and the rotation angle calculated by the rotation angle calculation unit. The tandem torch 50 is reciprocated at the rotation angle calculated by the rotation angle calculation unit.

  The tandem arc welding method using the tandem arc welding system is configured such that the control point of the leading electrode tip and the trailing electrode tip for drawing a weaving locus having an amplitude set individually for each of the leading electrode and the trailing electrode. A step of determining a rotation axis substantially perpendicular to the line connecting the control points based on the operation program, and the tandem torch 50 rotates around the rotation axis determined by the rotation axis determination unit, so that the preceding electrode and the following electrode A step of calculating a rotation angle for performing reciprocating motion of the electrode with a specified amplitude based on an operation program, an operation program stored in a storage unit, a rotation axis determined by a rotation axis determination unit, and rotation Based on the rotation angle calculated by the angle calculation unit, the tandem torch 50 is reciprocated around the rotation axis determined by the rotation axis determination unit at the rotation angle calculated by the rotation angle calculation unit. To those having a step.

  The reciprocating operation of the tandem torch 50 is realized by, for example, holding the tandem torch 50 in a manipulator that constitutes a welding robot and controlling the operation of the manipulator by the controller 20 that is a robot control device that constitutes the welding robot. can do.

  The operation program is for operating the tandem arc welding system in a predetermined operation pattern and welding an object to be welded under predetermined welding conditions.

  As described above, according to the tandem arc welding method and the tandem arc welding system of the first embodiment, even in tandem arc welding using the tandem torch 50 or two single electrode welding torches arranged in close proximity, the leading electrode Different weaving can be performed for the trailing electrode and the trailing electrode.

  According to the present invention, the degree of freedom of the weaving operation in tandem arc welding can be increased, and the possibility of performing a weaving operation suitable for tandem arc welding is increased. As a result, the welding quality such as penetration and bead shape can be improved. For example, it is industrially useful as a tandem arc welding method or tandem arc welding system used in a welding can manufacturing process or the like.

20 controller 30 welding machine 31 power cable 32 ground cable 33 control line 40 welding machine 41 ground cable 42 power cable 43 control line 50 tandem torch 51 preceding contact tip 52 following contact tip 53 leading electrode (preceding welding wire)
54 Back electrode (following welding wire)
55 Leading arc 56 Trailing arc 58 Nozzle 60 Work piece to be welded 61 Melting pool 62 Weld bead a Control point (leading electrode)
b Control point (following electrode)
d Distance (Distance between electrodes)
l Line segment (Line segment connecting the leading electrode control point and the trailing electrode control point)
m1 line segment (line segment showing the amplitude of the leading electrode)
m2 line segment (line segment showing the amplitude of the trailing electrode)
j line segment (auxiliary line)
k line segment (auxiliary line)
r angle (weaving angle)
o Point (weaving center)
f Plane (weaving plane)
x Direction in which the welding line direction formed by the teaching point on the welding line registered in the program is projected onto the horizontal plane z Vertical direction y Direction perpendicular to the two directions x and y h1 Inclination parameter h2 Inclination parameter

Claims (4)

A line connecting a predetermined control point at the tip of the leading electrode and a predetermined control point at the tip of the trailing electrode in order to draw a weaving trajectory having an amplitude set individually for each of the leading electrode and the trailing electrode. Determining a rotation axis substantially perpendicular to
A step of calculating a rotation angle for rotating the welding torch around the rotation axis and performing a reciprocating operation with a specified amplitude between the leading electrode and the trailing electrode;
A tandem arc welding method comprising a step of performing control to reciprocate the welding torch at the rotation angle about the rotation axis. The tandem arc welding method according to claim 1, wherein the amplitude of the reciprocating motion of the preceding electrode is smaller than the amplitude of the reciprocating motion of the trailing electrode. Connecting a predetermined control point at the tip of the preceding electrode and a predetermined control point at the tip of the succeeding electrode for drawing a weaving locus having an amplitude set individually for each of the leading electrode and the following electrode A rotation axis determination unit that determines a rotation axis substantially perpendicular to the line;
A rotation angle calculation unit for calculating a rotation angle for rotating the welding torch around the rotation axis and performing a reciprocating operation with a specified amplitude between the leading electrode and the trailing electrode;
A control unit for reciprocating the welding torch at the rotation angle around the rotation axis;
Tandem arc welding system equipped with. The tandem arc welding system according to claim 3, wherein the amplitude of the reciprocating motion of the leading electrode is smaller than the amplitude of the reciprocating motion of the trailing electrode.

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