JP2007275941A - Arc welding equipment and its fault detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an arc welding equipment that can ensure successful operation of equipment by facilitating detection of short-circuit failure. <P>SOLUTION: Before applying arc welding treatment, a base material 5 or a tool 7 is brought into contact with a welding wire 17, with an electric current flowing in a welding circuit 25 measured. This measured current IK is compared with a reference current I0 for discrimination which is predetermined corresponding to the welding circuit 25, thereby discriminating the presence/absence of a short-circuit between the welding circuit 25 and a tool control circuit 12. If occurrence of a short-circuit failure is discriminated, the process is prevented from shifting to the arc welding treatment. Accordingly, burning of control equipment or electric wire that may occur when arc welding treatment is carried out without knowing the occurrence of the short-circuit failure can be surely avoided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an arc welding apparatus and a failure detection method thereof.

As an example of an apparatus configured to detect a failure in an arc welding apparatus, there is an arc welding apparatus disclosed in Patent Document 1. An arc welding apparatus disclosed in Patent Document 1 has an overcurrent circuit breaker connected to an input terminal, an abnormal voltage detection circuit for detecting an abnormal voltage on the output side of the overcurrent circuit breaker, and a signal from the abnormal voltage detection circuit. A short circuit that operates, an output control circuit that controls the output of the arc welding apparatus, and an output control element that operates in response to a signal from the output control circuit. In this device, when an abnormal voltage enters, the abnormal voltage detection circuit works, receives a signal from the abnormal voltage detection circuit, a short circuit works, excessive current flows, the overcurrent breaker trips, and it is weak against abnormal voltage The output control circuit and the output control element are electrically cut off for protection.
Moreover, in an arc welding apparatus, a jig may be used to hold a base material. As an example of an arc welding apparatus using a jig, there is an arc welding apparatus shown in FIG.
JP 7-178549 A

By the way, in an arc welding apparatus, a jig may be used to hold a base material. In an arc welding apparatus using a jig, a welding circuit used for generating an arc may be short-circuited through the jig to a control circuit arranged in the vicinity of the jig. An arc welding apparatus using this jig and its short circuit failure will be described with reference to FIGS.
In FIG. 4, an arc welding apparatus 1 includes a welding mechanism 3 mainly including a welding robot 2, a welding power source 4, a jig 7 on which a base material 5 is placed and which can be moved to a base portion 6. And a sensor 8 including a proximity switch, a limit switch, and the like disposed in the jig 7 or in the vicinity thereof. The arc welding apparatus 1 further includes a jig control panel 10 and a robot controller 11.
The jig control panel 10 is connected to the sensor 8 via a control circuit (hereinafter referred to as a jig control circuit 12), and the jig 7 is driven by a detection signal of the sensor 8 and a command from the robot controller 11 described later. Take control.
The robot controller 11 controls a drive unit of the welding mechanism 3 (a drive unit such as a motor of the welding robot 2) via the welding power source 4 or directly.
In a state where the base material 5 is placed on the jig 7, the jig 7 and the base material 5 are electrically connected. Further, the jig 7 and the sensor 8 are electrically insulated.

The welding robot 2 includes a wire supply device 15 and feeds a welding wire 17 (a filler material also serving as an electrode) to a torch 18 through a hose 16.
The arc welding apparatus 1 further includes an ammeter 20 interposed between the positive electrode of the welding power source 4 and the torch 18 so as to be readable by an operator, an output side portion of the positive electrode of the welding power source 4 and an output side of the negative electrode And a voltmeter 22 interposed between the parts and provided so as to be readable by an operator.
The welding power source 4 includes an arc generation confirmation relay (WCR) 23. The contact signal of the arc generation confirmation relay 23 is assigned to a hard I / O (multi-core cable) 24 that connects the robot controller 11 and the welding power source 4. The arc generation confirmation relay 23 is turned on when the current flowing through the welding circuit 25 including the base material 5, the jig 7, the welding wire 17, and the welding power source 4 is equal to or greater than a certain value. This is sent to the robot controller 11 via a hard I / O (multi-core cable) 24 connected to the power supply 4 so that the robot controller 11 can grasp that a current exceeding a certain value flows in the welding circuit 25. ing.
The jig control panel 10 is provided with a DC 24V power source and is applied to the jig control circuit 12. Further, the welding power source 4 has a terminal voltage set to DC 90V.

In this arc welding apparatus 1, when operating normally, a welding current flows through the welding circuit 25 as shown by an arrow Y1 shown in FIG.
However, when a part of the welding circuit 25 is short-circuited to the jig control circuit 12 for some reason, a part of the welding current flows into the jig control circuit 12 as indicated by an arrow Y2 in FIG. This could cause equipment failure and wire burnout, and could eventually lead to a shutdown of the entire device.
This invention is made | formed in view of the said situation, and it aims at providing the arc welding apparatus which can detect a short circuit failure easily and can ensure the favorable operation | movement of an apparatus.

  In the invention according to claim 1, a part of the jig control circuit related to the jig is disposed in the vicinity of the jig holding the base material or the jig, and the welding mechanism is controlled by the controller. An arc welding apparatus in which an arc welding process is performed by applying a voltage of a welding power source to the base material and the wire, and the controller performs the base material or the jig and the wire before performing the arc welding process. A current measuring means before arc welding process for measuring a current flowing in a welding circuit including the base material, the jig, the wire and the welding power source, and a measurement obtained by the current measuring means before the arc welding process Short-circuit presence / absence determining means for comparing the current with a predetermined reference current corresponding to the welding circuit and determining whether or not the welding circuit and the jig control circuit are short-circuited.

  In the invention according to claim 2, a part of the jig control circuit related to the jig is arranged in the vicinity of the jig holding the base material or the jig, and the welding mechanism is controlled by the controller. A failure detection method used in an arc welding apparatus in which an arc welding process is performed by applying a voltage of a welding power source to the base material and the wire, and before the arc welding process, the base material or the jig and the wire And measuring the current flowing in the welding circuit including the base material, the jig, the wire, and the welding power source, and the current measuring step before arc welding processing, and the current measuring step before arc welding processing. A short-circuit presence / absence determination step of comparing the measured current with a predetermined reference current corresponding to the welding circuit to determine whether or not the welding circuit and the jig control circuit are short-circuited. .

  According to the first and second aspects of the present invention, before the arc welding process is performed, the base material or the jig and the wire are brought into contact with each other, the current flowing through the welding circuit is measured, and the measured current corresponds to the welding circuit. Then, the presence or absence of a short circuit between the welding circuit and the jig control circuit is determined by comparison with a predetermined reference current for determination. If it is determined that a short-circuit failure has occurred, the transition to the arc welding process should not be performed, so that the occurrence of a short-circuit failure cannot be grasped and the control equipment and electric wires that can occur when the arc welding process is executed as it is Burnout can be avoided reliably.

Hereinafter, an arc welding apparatus 1A according to an embodiment of the present invention will be described with reference to FIGS. Note that members equivalent to those shown in FIGS. 4 to 6 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.
The arc welding apparatus 1A of this embodiment is mainly different from the following (1) to (4) in comparison with the arc welding apparatus 1 of FIG.
(1) Instead of the robot controller 11 of FIG. 4, a robot controller 11A is provided as shown in FIG.
(2) A welding power source composed of a digital power source (hereinafter referred to as a digital welding power source 4A for convenience in order to be distinguished from the welding power source 4 of FIG. 4) instead of the welding power source 4 of FIG.
(3) A Device Net cable (device net cable) 27 is used instead of the hard I / O (multi-core cable) 24 for connecting the robot controller 11 of FIG. 4 and the arc welding apparatus 1 of FIG.
(4) A method of detecting a short circuit failure between the welding circuit 25 and the jig control circuit 12 (described later) is adopted.

  The digital welding power source 4A adjusts the magnitude of the input voltage in accordance with an instruction from the robot controller 11A using PWM control or the like and outputs the adjusted voltage. When performing the arc welding process, the output voltage is set to DC 90V, and when the input of the short-circuit confirmation command is received from the robot controller 11A, the output voltage is set to DC 24V. The digital welding power source 4A is provided with an ammeter 31 and a voltmeter 32 in the vicinity of the positive electrode and the negative electrode, detects the current flowing through the welding circuit 25 and the voltage between the positive electrode and the negative electrode, and detects the detected value as a robot controller. 11A is output.

11 A of robot controllers are provided with the current measurement means 35 before an arc welding process, the short circuit presence determination means 36, and the memory | storage part 37 which stores the reference electric current 10 for determination. The robot controller 11A is provided with notification means 40.
The reference current I0 for determination is obtained by a value obtained by measurement by setting the output voltage of the digital welding power source 4A to 24V DC or by simulation in a state where the welding circuit 25 and the jig control circuit 12 are not broken. The obtained value is adopted and stored in the storage unit 37.

  The current measuring means 35 before the arc welding process brings the base material 5 and the welding wire 17 into contact with each other before performing the arc welding process by the arc welding apparatus 1A, so that the welding circuit 25 (the base material 5, the jig 7, the welding is performed). The current flowing through the wire 17 and the digital welding power source 4A) is measured. In the present embodiment, the measurement current is obtained by receiving the current detected by the ammeter of the digital welding power source 4 </ b> A via the Device Net cable 27. This measured current, that is, the current flowing through the welding circuit 25 obtained by measurement by the current measuring means 35 before arc welding processing is referred to as measured current IK.

  The short circuit presence / absence determining means 36 compares the measured current IK obtained by the current measuring means 35 before arc welding processing with the determination reference current I0 (normal value) stored in the storage unit 37, and the welding circuit 25 The presence / absence of a short circuit with the jig control circuit 12 is determined. In the present embodiment, when the measurement current IK = the reference current for determination I0, there is no short-circuit failure, and when the measurement current IK <the reference current for determination I0, it is determined that a short-circuit failure has occurred. That is, when a short circuit failure has occurred, a part of the current of the welding circuit 25 leaks to the jig control circuit 12, thereby reducing the value of the measurement current IK. By utilizing this fact, as described above, when the measurement current IK <the reference current for determination I0, it is determined that a short circuit failure has occurred.

The operation of the arc welding apparatus 1A configured as described above will be described with reference to FIGS.
As shown in FIG. 3, first, the welding robot 2 is moved to the arc-on (arc-on) position by the operation of the robot controller 11A, and the base material 5 and the welding wire 17 are brought into contact as shown in FIG. 2 (step S1). .
The robot controller 11A outputs a short-circuit confirmation command (step S2).
Subsequently, the output voltage of the digital welding power source 4A is set to 24 V, and the voltage is applied between the torch 18 and the base material 5 (step S3).
In the present embodiment, steps S1 to S3 constitute a current measurement process before arc welding processing.

The ammeter 31 of the digital welding power source 4A detects the current of the welding circuit 25, and the detected content is input to the robot controller 11A as the measurement current IK and compared with the determination reference current I0 (step S4).
In the present embodiment, step S4 constitutes a short circuit presence / absence determination step.
If the measured current IK = the reference current for determination I0 in the comparison in step S4, the process proceeds to step S5, where it is determined that no short-circuit failure has occurred and the arc welding apparatus 1A is normal, and arc welding is performed. Execute the process.
Further, if the measured current IK is smaller than the determination reference current I0 (measurement current IK <determination reference current I0) in the comparison in step S4, the current of the welding circuit 25 leaks to the jig control circuit 12. That is, it is determined that a short-circuit failure has occurred (step S6), and the notification means 40 is activated to notify the operator of this (step S7) so that the transition to the arc welding process can be stopped.

As described above, before the arc welding process is performed, the base material 5 or the jig 7 and the welding wire 17 are brought into contact with each other, the current flowing through the welding circuit 25 is measured, and the measured current IK corresponds to the welding circuit 25. Then, it is determined whether or not there is a short-circuit failure between the welding circuit 25 and the jig control circuit 12 in comparison with a predetermined reference current for determination I0. If it is determined that a short-circuit failure has occurred, the process proceeds to arc welding processing. I try not to. For this reason, it is possible to reliably avoid the occurrence of burnout of control devices and electric wires that may occur when the arc welding process is executed as it is without grasping the occurrence of a short-circuit failure.
In the conventional technique shown in FIG. 4 described above, the ammeter 20 is provided. However, the ammeter 20 is only grasped by the operator, and the robot controller 11 uses the ammeter for detecting a failure. I couldn't. In contrast, in the present embodiment, a digital welding power source 4A is provided, and an ammeter 31 provided in the digital welding power source 4A detects a current flowing through the welding circuit 25 and inputs this current to the robot controller 11A. . The robot controller 11A can detect a failure by using the fed back current (current flowing through the welding circuit 25).

  In the above embodiment, the case where the output voltage of the digital welding power source 4A is set to 24 V when detecting a short-circuit failure is taken as an example, but the present invention is not limited to this, and if an arc is not generated, Another voltage may be set.

It is a figure which shows typically the arc welding apparatus which concerns on one embodiment of this invention. It is a figure which shows typically the mode at the time of the short circuit occurrence of the arc welding apparatus of FIG. It is a flowchart which shows the short circuit detection method of the arc welding apparatus of FIG. It is a figure which shows typically an example of the conventional arc welding apparatus. It is a figure which shows typically the case where the arc welding apparatus of FIG. It is a figure which shows typically the case where the short circuit failure has occurred in the arc welding apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1A ... Arc welding apparatus, 11A ... Robot controller, 35 ... Current measurement means before an arc welding process, 36 ... Short-circuit presence determination means, 37 ... Memory | storage part.

Claims (2)

A part of the jig control circuit related to the jig is arranged in the vicinity of the jig holding the base material or in the vicinity of the jig, and the welding mechanism is controlled by the controller, so that the welding power source for the base material and the wire An arc welding apparatus in which arc welding processing is performed by applying a voltage of
The controller brings the base material or the jig into contact with the wire before performing the arc welding process, and a current flowing in a welding circuit including the base material, the jig, the wire, and the welding power source. Current measuring means before arc welding processing for measuring the current, and the measured current obtained by the current measuring means before arc welding processing is compared with a reference current predetermined corresponding to the welding circuit, and the welding circuit and the jig control An arc welding apparatus comprising: a short-circuit presence / absence determination unit that determines presence / absence of a short-circuit with a circuit. A part of the jig control circuit related to the jig is arranged in the vicinity of the jig holding the base material or in the vicinity of the jig, and the welding mechanism is controlled by the controller, so that the welding power source for the base material and the wire A fault detection method used in an arc welding apparatus in which arc welding processing is performed by applying a voltage of
Before performing the arc welding process, the arc that measures the current flowing through the welding circuit including the base material, the jig, the wire, and the welding power source by bringing the base material or the jig into contact with the wire. A current measurement step before welding treatment, and a measurement current obtained in the current measurement step before arc welding treatment is compared with a reference current predetermined corresponding to the welding circuit, and the welding circuit and the jig control circuit A failure detection method for an arc welding apparatus, comprising: a short-circuit presence / absence determination step for determining presence / absence of a short-circuit.

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