JP2011200867A - Arc welding equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide arc welding equipment that can shorten a cycle time of welding and improve arc starting performance.SOLUTION: In the arc welding equipment, when a welding torch 7 reaches a welding starting position and stops by a welding robot 4, a welding wire 1 is subjected to first slowdown so that the tip end of the welding wire 1 reaches a second slowdown starting position which is away from the welding starting position by a prescribed second slowdown distance S2. Then, when the welding torch 7 reaches the welding starting position and stops, second slowdown of the welding wire 1 is started, and the tip end of the welding wire 1 is short-circuited with a welding workpiece 2, and an arc 3 is generated. As a result, since a failure such that a pilot burner generated by short-circuiting the tip end of the welding wire with the welding workpiece is extinguished, is eliminated, the cycle time of welding is shortened and arc starting performance is improved.

Description

  The present invention relates to an arc welding apparatus for performing welding by feeding a consumable electrode (hereinafter referred to as a welding wire) from a welding torch provided in a welding robot.

  FIG. 6 is a configuration diagram of a general arc welding apparatus. In the figure, a welding torch 7 is attached to the tip of a manipulator 5 of a welding robot 4, and a welding wire 1 is fed from the welding torch 7, and the tip of the welding wire 1, the workpiece 2 and Arc 3 is generated during A welding speed setting signal Uw and operation trajectory data Dw of the welding torch 7 are input from the teach pendant 8 to the robot controller 9.

A wire feeder 11 is attached to the manipulator 5, and the welding wire 1 drawn from a wire reel (not shown) is fed by the wire feeder 11, and between the wire feeder 11 and the welding torch 7. It is guided by a coil liner in the connected one-wire power cable 6 and fed to the welding torch 7.

  The welding power source 10 includes a current control unit 12 and a feed control unit 13, and these units each have a communication circuit with the robot control device 9. The current control means 12 has an inverter control circuit composed of a plurality of transistor elements, for example. This inverter control circuit performs welding current waveform control with respect to the commercial power source input from the outside. The current control means 12 applies a welding voltage Vw between the welding wire 1 and the workpiece 2 via a power feed tip provided at the tip of the welding torch 7 and causes a welding current Iw to flow.

  The feed control means 13 is a circuit that outputs a feed control signal Fc for feeding the welding wire 1 to the feed motor of the wire feeder 11. The feed control signal Fc is a signal that gives an instruction to feed the welding wire 1 at the feed speed Ws.

  The robot control device 9 includes a drive circuit 14 having a microcomputer and a storage circuit 15 connected to the drive circuit 14. The storage circuit 15 stores a work program in which various operations of the welding robot 4 are set. The robot control device 9 can communicate with the welding robot 4, the welding power source 10, and the teach pendant 8. The drive circuit 14 sets a robot moving speed described later. The robot control device 9 gives an operation control signal Mc to the welding robot 4. By this operation control signal Mc, each motor is driven to rotate, and the welding torch 7 is moved to the welding start position of the workpiece 2. Further, the drive circuit 14 gives the welding power source 10 a welding power source output control signal Pc.

With reference to FIG. 7, the change of the protrusion length of the welding wire which is the length from the front-end | tip part of the electric power feeding chip | tip 16 to the front-end | tip part of the welding wire 1 is demonstrated. FIG. 7 is a diagram for explaining a change in the protruding length of the welding wire of the prior art. In FIG. 2A, the welding torch 7 is moved to the welding start position by the welding robot 4 and the welding robot stops. And the slowdown of the welding wire 1 is started, and as shown to the same figure (B), the front-end | tip part of the welding wire 1 and the to-be-welded object 2 short-circuit.

Simultaneously with the short-circuit, a seed arc is generated and a welding current begins to flow, the tip of the welding wire 1 is melted, and an arc is generated as shown in FIG. At this time, if the slowdown speed of the welding wire 1 is higher than the speed at which the tip of arc of the welding wire 1 is generated and the tip of the welding wire 1 is melted, the seeding arc disappears. It is set to 1 m / min, which is considerably slower than the speed. When welding is started, the feeding speed of the welding wire is switched to the feeding speed at the time of steady welding, the movement of the welding torch 7 is started, and welding is performed.

And as shown in the figure (D), the welding wire 1 is anti-stick processed at the end of welding, and the tip of the welding wire 1 burns up to a length Ls from the work piece 2, for example, 5 to 10 mm, The protruding length of the welding wire is Le.

Here, the reason for performing the anti-stick treatment is as follows. Even after the stop signal is input to the wire feeder, the feed motor feeds the welding wire 1 by inertia force. Therefore, when the welding wire 1 rushes into the molten pool and the molten pool cools, the tip of the welding wire 1 is fixed (stick) to the weld metal. In order to prevent this stick, the welding wire 1 is melted by applying a current smaller than the welding current value after a stop signal is input to the wire feeder, and the welding wire 1 is prevented from being pushed into the molten pool. There is a need.

Next, as shown in FIG. 7 (E), the welding robot 4 moves the welding torch 7 to the next welding start position, and as shown in FIG. 7 (F), the welding wire 1 is slowed down by the length Ls. Thus, the tip of the welding wire 1 and the workpiece 2 are short-circuited to generate an arc.

In this way, since the anti-stick process is performed at the end of welding and the tip of the welding wire 1 is burned up to the length of Ls from the workpiece 2, the welding robot 4 moves the welding torch 7 at the start of the next welding. Is moved to the welding start point and the welding robot 4 is stopped, and then the welding wire 1 needs to be slowed down by this length Ls.

  Conventionally, in order to reduce the tact time of the welding operation, instead of slowing down the welding wire 1 after the welding torch 7 of the welding robot 4 has reached the welding start position, the time when the welding torch 7 reaches the welding start position is determined. Also, a control method for a welding robot has been proposed in which the welding wire 1 is slowed down to shorten the time. The time shortened by this control method is 0.36 seconds if the slowdown speed of the welding wire 1 is, for example, 1 m / min. If the slowdown of 6 mm is performed, this time is shortened at the start of each welding. Is done.

Japanese Patent No. 3821404

The conventional welding robot control method described above starts the slowdown of the welding wire 1 before the welding torch 7 provided in the welding robot 4 reaches the welding start position, and the protruding length of the welding wire 1 is welded. After being slowed down to the wire protrusion length at the start, the tip of the welding wire 1 reaches the welding start position. That is, the tip of the welding wire 1 is moved by the welding robot 4 and short-circuited with the workpiece 2, so that the seed fire generated after the short-circuit may disappear because the moving speed of the welding robot is fast, The start of the arc was bad.

  An object of the present invention is to provide an arc welding apparatus capable of reducing the tact time of welding and improving the arc startability.

In order to solve the above-described problems, the invention of claim 1
In an arc welding apparatus for generating an arc by short-circuiting a tip of a welding wire of a welding torch provided in a welding robot and an object to be welded,
Welding torch moving means for moving the welding torch to a welding start position by the welding robot;
When the welding torch reaches the welding start position and stops, the welding wire is such that the tip of the welding wire reaches a second slow down start position that is a predetermined second slow down distance from the welding start position. First slow down means for first slowing down the wire;
A second slow down means for starting a second slow down of the welding wire when the welding torch reaches the welding start position and stops;
An arc welding apparatus comprising:

The invention of claim 2
The first slow-down is started from a time that precedes a preceding processing time required for the first slow-down of the welding wire by a predetermined first slow-down distance from a time at which the welding torch reaches the welding start position. 2. The arc welding apparatus according to claim 1, which starts.

The invention of claim 3
The first slow-down distance according to claim 2 is a distance obtained by subtracting the protruding length of the welding wire after the antistic treatment and the second slow-down distance from the wire protruding length at the start of welding. Device.

  In the arc welding apparatus of the present invention, when the welding torch reaches the welding start position and is stopped by the welding robot, the tip of the welding wire is separated from the welding start position by a predetermined second slowdown distance. The welding wire is first slowed down to reach the starting position. When the welding torch 7 reaches the welding start position and stops, the second slowdown of the welding wire is started, and the arc is generated by short-circuiting the tip of the welding wire with the workpiece. As a result, there is no problem that the seed fire generated by short-circuiting the tip of the welding wire with the work piece disappears, so that the tact time of welding can be shortened and the arc startability is improved. be able to.

It is a figure for demonstrating the change of the protrusion length of the welding wire of this invention. It is a figure which shows the timing chart of each signal etc. of the arc welding apparatus of this invention. It is a figure which shows the time passage of each signal in a robot control apparatus and a welding power supply. It is a figure which shows the time passage of each signal in the robot control apparatus and welding power supply following FIG. It is a figure which shows the step of operation | movement of the arc welding apparatus of this invention. It is a block diagram of a general arc welding apparatus. It is a figure for demonstrating the change of the protrusion length of the welding wire of a prior art.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on examples with reference to the drawings. With reference to FIG. 1, the change of the protrusion length of a welding wire is demonstrated. FIG. 1 is a view for explaining changes in the protruding length of the welding wire of the present invention. In FIG. 3A, the welding wire 1 is subjected to an anti-stick process at the end of the previous welding, and the tip of the welding wire 1 is burned from the workpiece 2 by, for example, 5 to 10 mm.

As shown in FIG. 5B, the first slowdown of the welding wire 1 is started before the welding torch 7 is moved to the welding start position by the welding robot 4, and the first slowdown distance S1 is the first slowdown. When the welding torch 7 reaches the welding start position as shown in FIG. 5C, the welding robot 4 stops. When the welding torch 7 reaches the welding start position, the second slowdown of the welding wire 1 is started, and the tip of the welding wire 1 and the workpiece 2 are short-circuited as shown in FIG. At this time, the protruding length La of the welding wire (hereinafter referred to as a welding protruding wire protruding length) is set to 15 mm when the welding current is 100A to 200A, for example.

Simultaneously with the short-circuit, a seed arc is generated and a welding current begins to flow, the tip of the welding wire 1 is melted, and an arc 3 is generated as shown in FIG. If the second slowdown speed of the welding wire 1 is faster than the speed at which the tip of the welding wire 1 is melted by the generation of the seeding arc, the seeding arc disappears, so the second slowing down speed of the welding wire 1 Is set to 1 m / min, which is considerably slower than the feeding speed during steady welding, for example. When welding is started, the feeding speed during steady welding of the welding wire is set to 2.2 m / min when the diameter of the welding wire 1 is 1.2 mm and the welding current is 100 A, for example. And the movement of the welding torch 7 is started and welding is performed.

Then, as shown in FIG. 5F, the welding wire 1 is subjected to anti-stick treatment at the end of welding, and the tip of the welding wire 1 burns up from the work piece 2 by the length of Ls, so that the protruding length of the welding wire is increased. Becomes Le. The protruding length Le of the welding wire at this time is 9 mm when the wire protruding length La at the start of welding is 15 mm, for example, and the length Ls at which the tip of the welding wire 1 is burned by the antistic treatment is 6 mm. The length Ls at which the tip of the welding wire 1 burns by this anti-stick treatment is set so as to be substantially constant without variation depending on the welding conditions.

Hereinafter, the arc welding apparatus of the present invention will be described in detail with reference to FIGS. FIG. 2 is a diagram showing a timing chart of each signal and the like of the arc welding apparatus of the present invention, and FIGS. 3 and 4 are diagrams showing a time passage of each signal in the robot controller and the welding power source.

At time t1 shown in FIGS. 2 and 3, an activation signal is input to the robot controller 9 to activate the welding robot 4, and welding is provided at the tip of the manipulator 5 of the welding robot 4 according to a previously taught path. The movement of the torch 7 is started.

  The first slow-down start command for the robot controller 9 to start the first slow-down of the welding wire 1 at time t2 preceding the time t4 when the welding torch 7 reaches the welding start position by the welding robot 4 by the preceding processing time Ta. Read the signal. From time t2 to time t3 when the first slowdown of the welding wire 1 is actually started, the periods Ta1 to Ta4 shown in FIG. 3 elapse.

That is, during the period Ta1, the robot control device 9 reads the first slowdown start command signal at time t2, and then internally processes it to convert it into a command signal for the welding power source 10 and outputs this command signal. It is a period. The period Ta2 is a period from when this command signal is output from the robot controller 9 until it is transmitted to the welding power source 10 by the communication means. During a period Ta3, the welding power source 10 is activated after receiving the command signal transmitted from the robot control device 9, and is processed internally to be converted into a welding condition signal to be transmitted to the wire feeder 11 with a welding wire. This is a period until the first slowdown start command signal for starting the first slowdown is converted and output. The period Ta4 is a period from when this command signal is output from the welding power source 10 until it is transmitted to the wire feeder 11 by the communication means.

  At time t3, the wire feeder 11 receives the first slowdown start command signal and starts up, and starts the first slowdown. The speed of the first slowdown is required to be high in order to reduce the tact time, but the welding wire 1 is fed to switch to the speed of the second slowdown after the end of the first slowdown. It is necessary to set the speed below that which is not affected by the inertia of the feed motor. Therefore, when the speed of the second slow-down described later is, for example, 1 m / min, the speed of the first slow-down is preferably set to 1 m to 2 m / min. Moreover, when using a servo motor with high responsiveness as a feed motor, the speed of the first slowdown may be further increased.

  When the welding torch 7 reaches the welding start position at time t4, the first slowdown of the welding wire 1 by the first slowdown distance S1 is completed. The first slowdown period is Ta5. The first slow-down distance S1 is a distance obtained by subtracting the welding wire protruding length Le after the anti-stic treatment at the end of the previous welding and a later-described second slow-down distance S2 from the wire protruding length La at the start of welding. is there. For example, if the wire protruding length at the start of welding is 15 mm, the protruding length Le of the welding wire after anti-stick treatment is 9 mm, and the second slowdown distance S2 is 2 mm, the first slowdown distance S1 is 4 mm.

  At time t4, the tip of the welding wire 1 of the welding torch 7 reaches a second slowdown start position that is separated from the work piece 2 by a predetermined second slowdown distance S2 just above the welding start position. ing.

  At time t4, the welding voltage Vw is applied between the welding torch 7 and the workpiece 2 and the second slowdown of the welding wire 1 is started by the second slowdown distance S2. If the second slowdown speed of the welding wire 1 is higher than the speed at which the tip of the welding wire 1 melts after the short circuit and the tip of the welding wire 1 melts, the seeding arc disappears. The down speed is set to 1 m / min, for example.

  At time t5 shown in FIG. 4, when the tip of the welding wire 1 is short-circuited with the workpiece 2, the welding current Iw is energized and the arc 3 is generated. The period of the second slowdown is Tb1.

After arc 3 is generated at time t5, welding robot 4 is actually restarted at time t6, which will be described later, welding robot 4 resumes movement of welding torch 7, and the feeding speed of welding wire 1 is steady. The period Tc1 to Tc3 elapses before switching to the feeding speed at the time of welding.

That is, during the period Tc1, after the arc 3 is generated between the distal end portion of the welding wire 1 and the work piece 2, the welding current detection signal detected by the welding current detector is internally processed, and the welding robot 4 And a period until the command signal is output after being converted into a command signal for the wire feeder 11. The period Tc2 is a period from when the welding power source 10 outputs this command signal to when it is transmitted to the robot controller 9 and the wire feeder 11 by the communication means. During the period Tc3, the robot control device 9 receives the command signal transmitted from the welding power source 10 and then restarts to resume the movement of the welding torch 7, and the wire feeder 11 is transmitted from the welding power source 10. This is a period from when the command signal is received until the welding wire 1 feed speed is switched to the steady feed speed.

At time t6, the welding robot 4 is actually restarted, the welding robot 4 resumes the movement of the welding torch 7, and the feeding speed of the welding wire 1 is switched to the feeding speed at the time of steady welding, and welding is performed. Is called. For example, when the welding wire 1 has a diameter of 1.2 mm and a welding current of 100 A, the feeding speed during steady welding of the welding wire is set to 2.2 m / min.

  At time t7, the robot controller 9 reads the start / stop command signal, the welding robot 4 stops starting, the wire feeder 11 stops feeding the welding wire 1, and performs anti-stick processing of the welding wire 1. Then, the application of the welding voltage is stopped and the welding is finished at time t8.

The operation will be described below. FIG. 5 is a diagram showing operation steps of the arc welding apparatus of the present invention. In the arc welding apparatus of the present invention, in step 1 shown in the figure, the welding robot 4 is activated at time t1 shown in FIGS. 2 and 3, and the movement of the welding torch 7 is started according to a previously taught path.

  In step 2, the robot controller 9 reads the wire first slow-down start command signal at a time t2 preceding the time t4 when the welding torch 7 reaches the welding start position by the welding robot 4 by the preceding processing time Ta.

  In step 3, at time t3, the wire feeder receives the first slowdown start command signal and starts up, and starts the first slowdown.

  In step 4, when the welding torch 7 reaches the welding start position and stops at time t4, the first slowdown is stopped.

  In step 5, a welding voltage is applied between the welding torch 7 and the workpiece 2 at time t4 to start the second slowdown of the welding wire 1.

  In step 6, when the tip of the welding wire 1 is short-circuited to the workpiece 2 at time t5, a welding current is applied and an arc 3 is generated.

  In step 7, the welding robot 4 is restarted at time t6, the welding robot 4 resumes the movement of the welding torch 7, and the feeding speed of the welding wire 1 is changed to the feeding speed at the time of steady welding.

  In step 8, the robot control device 9 reads the start / stop command signal at time t7, the welding robot 4 stops starting, the wire feeder 11 stops feeding the welding wire 1, and the anti-stick of the welding wire 1 is performed. The processing is performed to stop the application of the welding voltage, and the welding is finished at time t8.

Thus, when the welding torch 7 reaches the welding start position and stops by the welding robot 4, the arc welding apparatus of the present invention has the second slowdown distance that the tip of the welding wire 1 is predetermined from the welding start position. The welding wire 1 is first slowed down so as to reach the second slowdown start position separated by S2. When the welding torch 7 reaches the welding start position and stops, the second slowdown of the welding wire 1 is started, and the tip of the welding wire 1 is short-circuited with the workpiece 2 to generate the arc 3. ing. As a result, compared with the case where the welding torch 7 reaches the welding start position and stops and then starts slowing down, the time for slowing down is shortened, so that the tact time of welding can be shortened, In addition, since there is no problem that the seed flame generated by short-circuiting the tip of the welding wire 1 with the workpiece 2 is extinguished, the startability of the arc 3 can be improved.

Furthermore, since the arc welding apparatus of the present invention does not completely slow down the protruding length of the welding wire 1 to the wire protruding length at the start of welding by the time t4 when the welding torch reaches the welding start position by the welding robot, Compared with the prior art, it is possible to reduce interference of the tip of the welding wire 1 with the workpiece 2 and peripheral devices before the welding torch 7 reaches the welding start position.

DESCRIPTION OF SYMBOLS 1 Welding wire 2 Work piece 3 Arc 4 Welding robot 5 Manipulator 6 Single wire type power cable 7 Welding torch 8 Teach pendant 9 Robot controller 10 Welding power source 11 Wire feeder 12 Current control means 13 Feed control means 14 Drive circuit 15 Memory circuit 16 Power supply chip D1 Separation distance Dw Motion trajectory data Fc Feed control signal Iw Welding current La Welding start wire protrusion length Le Welding wire protrusion length Mc after antistic processing Operation control signal Pc Welding power output control signal S1 1st slowdown distance S2 2nd slowdown distance t1 to t10 Time Ta Pre-processing time Ta1 to Ta5 Period Tb1 Period Tc1 to Tc3 Period Td1 to Td3 Period Uw Welding speed setting signal Vw Welding voltage Ws Feeding speed

Claims (3)

In an arc welding apparatus for generating an arc by short-circuiting a tip of a welding wire of a welding torch provided in a welding robot and an object to be welded,
Welding torch moving means for moving the welding torch to a welding start position by the welding robot;
When the welding torch reaches the welding start position and stops, the welding wire is such that the tip of the welding wire reaches a second slow down start position that is a predetermined second slow down distance from the welding start position. First slow down means for first slowing down the wire;
A second slow down means for starting a second slow down of the welding wire when the welding torch reaches the welding start position and stops;
An arc welding apparatus comprising:   The first slow-down is started from a time that precedes a preceding processing time required for the first slow-down of the welding wire by a predetermined first slow-down distance from a time at which the welding torch reaches the welding start position. The arc welding apparatus according to claim 1, wherein the arc welding apparatus is started.   The first slow-down distance according to claim 2 is a distance obtained by subtracting the protruding length of the welding wire after the antistic treatment and the second slow-down distance from the wire protruding length at the start of welding. apparatus.

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