JP2009101370A - Arc welding control method and arc welding apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that unstable arc and rapid arc cutting occurs, and much spatter is produced and deposited during the period of shifting of arc welding from arc generation to stationary state. <P>SOLUTION: During the arc start period, the changes of the wire feed rate and the welding voltage are synchronously and continuously controlled, and the welding voltage corresponding to the wire feed rate is applied for the predetermined time to realize the excellent arc starting property, and to reduce production and deposition of spatter without any unstable arc immediately after the arc starts. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an arc welding control method and an arc welding apparatus at the time of arc start in arc welding in which an arc is generated between a welding wire that is a consumable electrode and a base material that is a workpiece.

  In recent years, in the welding industry, there has been an increasing demand for high quality welding for improving productivity. Among them, there is a reduction in spatter at the time of arc start. At the time of arc start, it takes time until the arc stabilizes, and the occurrence of spatter increases and often adheres to the workpiece. And the post-process for removing adhesion spatter is needed, and welding productivity will fall.

In the conventional arc start control, the so-called hot voltage method in which the welding voltage at the arc start is set higher than the welding voltage at the steady welding, or the wire feed speed is set lower than the steady speed before the arc start even if the welding voltage is constant. A slow-down method for starting the vehicle has been implemented (see, for example, Patent Document 1).
Japanese Unexamined Patent Publication No. 1-197068

However, as shown in FIG. 3, the conventional arc start control improves the arc stability immediately after the arc start, and immediately after the arc start, the wire feed speed signal is instantaneously changed from the slowdown speed to the steady welding. And the welding voltage is switched from the hot voltage to the voltage during steady welding.
For this reason, the arc generation immediately after the occurrence of the arc is stabilized, but it takes about 1 second to 2 seconds until the arc stabilizes thereafter, and the spatter increases rapidly or the arc breaks until the arc is stabilized. It wasn't. This phenomenon was particularly noticeable in pulse welding and the like, and had the disadvantage that the unstable period after the start lasted.

  In order to solve the above-described problems, the arc welding control method of the present invention is configured so that the wire is applied in a state in which a voltage is applied between a wire that is a consumable electrode and an object to be welded in an arc start period before the steady welding period. An arc welding control method of starting an arc by bringing the workpiece into contact with the workpiece, applying a voltage between the wire and the workpiece, and feeding the wire at a first feeding speed A step of feeding toward the workpiece, a step of detecting contact between the wire and the workpiece, and a contact speed between the wire and the workpiece when detecting the contact between the wire and the workpiece. A step of continuously changing from a first feeding speed to a steady wire feeding speed which is a feeding speed at the time of steady welding faster than the first feeding speed; and from the first feeding speed to the steady wire. Feeding speed The welding voltage applied between the wire and the workpiece to be welded is synchronized with the change in the continuous wire feed speed of the wire from the voltage at the time when the wire and the workpiece are in contact with each other at the time of steady welding. A step of continuously changing to a first welding voltage higher than a steady welding voltage that is a welding voltage, and when a first time elapses from the time when the wire and the workpiece are in contact, Regardless, the step of continuously changing the welding voltage from the first welding voltage toward the steady welding voltage is provided.

  Further, in addition to the above, the arc welding control method of the present invention includes the time from when the wire and the workpiece are in contact until the welding voltage changes from the first welding voltage to the steady welding voltage, or the first It is possible to adjust at least one of the welding voltage magnitudes.

  Further, the arc welding apparatus of the present invention contacts the wire with the workpiece in a state where a voltage is applied between the wire that is a consumable electrode and the workpiece during the arc start period before the steady welding period. An arc welding apparatus that performs an arc start and detects a welding current, and a contact detection unit that detects contact between the wire and the workpiece to be welded based on a signal from the welding current detection unit A signal from the contact detection unit, a wire feed rate control unit that controls the feed rate of the wire, a control unit that controls a welding voltage applied between the wire and the workpiece A counter unit that counts an elapsed time from when the wire and the workpiece are in contact with each other, and the wire feeding speed control unit feeds the wire at the first feeding speed. For When the wire and the workpiece are in contact with each other, the wire feeding speed is higher than the first feeding speed from the first feeding speed at the time of steady welding. When the wire is brought into contact with the workpiece to be welded, the control section applies a voltage between the wire and the workpiece to be welded. A welding voltage applied between the wire and the workpiece to be welded in synchronization with a continuous change in the wire feeding speed from the first feeding speed to the steady wire feeding speed by the feeding speed control unit. Is continuously changed from a voltage at the time when the wire and the workpiece to be welded contact each other to a first welding voltage higher than a steady welding voltage that is a welding voltage at the time of steady welding, and further, the wire and the workpiece to be welded The first time has passed since the point of contact with the object , Regardless of the wire feed rate, but continuously changing the welding voltage from the first welding voltage towards said stationary welding voltage.

  In addition to the above, the arc welding apparatus of the present invention further includes a setting unit for setting the welding conditions, and the welding voltage is steady-state welding from the first welding voltage from the time when the wire and the workpiece are contacted. The time to voltage or the magnitude of the first welding voltage is set welding current set to perform welding set by the setting unit, set welding voltage set to perform welding, wire It is determined by the control unit based on at least one of feeding speed, shield gas type, wire material, wire diameter, and welding method.

  As described above, according to the present invention, instead of instantaneously switching to the steady wire feed speed or the steady welding voltage immediately after the start, the change between the wire feed speed and the welding voltage is synchronized in the arc start period. In addition, the welding voltage associated with the wire feed speed is applied continuously for a predetermined length of time to improve arc start performance, and without causing arc instability immediately after the start of sputtering. Generation and spatter adhesion can be reduced. In addition, a welding state can be stabilized by changing a welding voltage gradually gradually compared with the case where it changes suddenly.

(Embodiment 1)
Hereinafter, this embodiment will be described with reference to FIGS.

  FIG. 1 is a diagram showing a schematic configuration of an arc welding apparatus. This arc welding apparatus mainly feeds a welding power source 17 for supplying electric power between a wire 13 that is a consumable electrode and a workpiece 16 to be welded, a welding torch 14, and the wire 13 in the direction of the workpiece 16. The wire feeding unit 12 is configured.

  In the welding power source 17, the electric power from the input power source 1 is rectified by the primary rectifier 2, converted to alternating current by the switching element 3, stepped down by the transformer 4, and rectified by the secondary rectifier 5 and DCL (inductance) 6. And applied between the wire 13 and the workpiece 16. An arc 15 is generated between the wire 13 and the workpiece 16.

  Further, the welding power source unit 17 includes a control unit 8 that outputs a control signal for controlling the welding output to the output control unit 7, a welding current detection unit 9 that detects a welding current, and a welding voltage detection unit 10 that detects a welding voltage. And a wire feeding speed control unit 11 for controlling the wire feeding device 12 and a setting unit 18 for setting welding conditions. The welding conditions set by the setting unit 18 include a set welding current set for performing welding, a set welding voltage set for performing welding, a wire feed speed, a shield gas type, and a wire material. And a wire diameter, a welding method such as pulse welding, and the like. The set welding current is a welding current set by the operator according to the shape and welding speed of the workpiece, and the set welding voltage is a welding current set by the operator according to the shape and welding speed of the workpiece. is there. And the output control part 7 controls a welding output by controlling the switching element 3 based on the control signal from the control part 8. FIG.

  Further, when the control unit 8 receives a signal indicating that the welding current is detected from the welding current detection unit 9 at the time of the arc start before the steady welding state, the control unit 8 detects the contact between the wire 13 and the workpiece 16, It has the function of a counter that counts the elapsed time from that point. Furthermore, the control unit 8 also has a function of controlling a welding voltage such as a hot voltage and a steady welding voltage described later based on the welding conditions set by the setting unit 18.

  In addition, each component which comprises an arc welding apparatus may each be comprised independently as needed, and you may make it comprise combining a some component part.

  An example of control of the wire feed speed and welding voltage at the time of arc start will be described with reference to FIG. FIG. 2A is a diagram showing a time change of the welding start signal, FIG. 2B is a diagram showing a time change of the wire feed speed, and FIG. 2C is a diagram showing a time change of the welding voltage. FIG. 2 (d) is a diagram showing a change in welding current over time.

  In FIG. 2, a welding start signal is turned ON by turning on a torch switch (not shown) provided on the welding torch 14. When the wire feeding speed control unit 11 receives a signal indicating that the activation signal is turned on via the control unit 8, the wire feeding speed control unit 11 sets the wire feeding speed to the wire feeding unit 12 at the time of steady welding. A wire feeding signal for feeding the wire 13 at a slow-down speed that is lower than the speed is transmitted, and the wire feeding unit 12 feeds the welding wire 13 toward the workpiece 16 at the slow-down speed. At the same time, the control unit 8 outputs to the output control unit 7 a signal for applying a no-load voltage higher than the steady welding voltage, which is a voltage during steady welding, between the wire 13 and the workpiece 16. A no-load voltage is applied between the wire 13 and the workpiece 16.

  When the wire 13 comes into contact with the workpiece 16 with no load voltage applied, a welding current flows. This welding current is detected by the current detection unit 9, and a signal indicating that the current has been detected is transmitted to the control unit 8. Is done.

  When the wire feeding speed control unit 11 receives a signal indicating that the current has been detected via the control unit 8, the wire feeding speed control unit 11 sends a predetermined steady state higher than the slow down speed from the slow down speed to the wire feeding unit 12. To gradually increase the feeding speed of the wire 13 at a constant rate toward the wire feeding speed, and transmit a signal for maintaining the predetermined steady wire feeding speed when the predetermined steady wire feeding speed is reached. To control the wire feed speed.

  When receiving the signal indicating that the current has been detected, the control unit 8 moves from the welding voltage at the time of detecting the current to a hot voltage having a predetermined magnitude higher than the steady welding voltage that is the welding voltage at the time of steady welding. The welding voltage is gradually increased at a constant rate, and when the predetermined hot voltage is reached, a signal for maintaining the predetermined hot voltage is transmitted to the control unit 7 to control the welding voltage. The control unit 8 receives a signal related to the wire feed rate from the wire feed rate control unit 11 and controls the welding voltage so as to correspond to the wire feed rate and to synchronize with the change in the wire feed rate. is there.

  When the control unit 8 receives a signal indicating that a current has been detected at the time of arc start, the control unit 8 counts an elapsed time from that point. Then, when the first time t1 elapses, the control unit 8 changes the hot voltage to the welding voltage at the time of steady welding from the time when the first time t1 elapses until the second time t2 elapses. The welding voltage is controlled so as to gradually decrease the hot voltage.

  Here, the total time of the first time t1 and the second time t2 is the hot voltage application time, and the voltage applied during this hot voltage application period is the hot voltage. That is, the hot voltage is a voltage that is gradually increased from the start time of the first time t1, is maintained at a predetermined magnitude, and is then reduced toward the steady welding voltage. And it is the welding voltage which has a larger value than the steady welding voltage applied in the initial period when an arc generate | occur | produces, or the period until it stabilizes after an arc occurs.

  Further, the first time t1 is, for example, about 200 ms to 2000 ms, and the second time t2 is, for example, 100 ms. These times may be fixed from experiments, etc., or may be set welding current, setting welding voltage, wire feeding speed, shield gas type, wire material, wire diameter set by the setting unit 18. Alternatively, it may be determined by the control unit 8 based on a welding method or the like. As for the hot voltage, similarly to the first time t1 and the second time t2, the set welding current, the set welding voltage, the wire feed speed, the shield gas type, the wire, You may make it determine by the control part 8 based on a material, a wire diameter, a welding method, etc. For example, the wire feed speed is determined so that the hot voltage application time is long and the maximum value of the hot voltage is high if the feed speed is fast. Further, the wire diameter is determined so that the larger the diameter, the longer the hot voltage application time and the higher the maximum value of the hot voltage. As for the welding method, when pulse welding is performed, the hot voltage application time is long, and the maximum value of the hot voltage is determined to be high.

  As described above, by continuously controlling the change between the wire feed speed and the hot voltage to be synchronized, and further applying the hot voltage associated with the wire feed speed for a predetermined time, the arc It is possible to reduce the occurrence of spatter and adhesion of spatter without causing arc instability immediately after the start as well as reliably starting. In addition, by gradually changing the hot voltage, the welding state can be stabilized as compared with a case where the hot voltage is changed rapidly.

  Further, increase in spatter, arc breakage, etc. are noticeable in pulse welding using, for example, Ar—CO 2 shielding gas. Therefore, it is very effective to apply the control described in this embodiment to such pulse welding. It is.

  Since the arc welding control method and the arc welding apparatus of the present invention can improve the productivity of welding work by reducing spatter generation and spatter adhesion at the time of arc start, they are a welding wire that is a consumable electrode and an object to be welded. This is useful for arc welding or the like in which an arc is generated between the base metal and welding.

The figure which shows schematic structure of the arc welding apparatus in Embodiment 1. FIG. (A) The figure which shows the time change of the starting signal in Embodiment 1 (b) The figure which shows the time change of the wire feed speed in Embodiment 1 (c) The figure which shows the time change of the welding voltage in Embodiment 1 (D) The figure which shows the time change of the welding current in Embodiment 1. FIG. (A) The figure which shows the conventional starting signal (b) The figure which shows the change of the conventional wire feed signal (c) The figure which shows the change of the conventional welding voltage (d) The figure which shows the change of the conventional welding current

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Input power supply 2 Primary rectification part 3 Switching element 4 Transformer 5 Secondary rectification part 6 DCL (inductance)
DESCRIPTION OF SYMBOLS 7 Output control part 8 Control part 9 Welding current detection part 10 Welding voltage detection part 11 Wire feed speed control part 12 Wire feed part 13 Wire (consumable electrode)
14 welding torch 15 arc 16 work piece 17 welding power source (welding machine)
18 Setting section

Claims (4)

Arc welding control method for performing arc start by bringing the wire into contact with the work piece in a state where a voltage is applied between the wire as a consumable electrode and the work piece during the arc start period before the steady welding period. Because
Applying a voltage between the wire and the work piece;
Feeding the wire toward the workpiece at a first feed rate;
Detecting contact between the wire and the work piece;
When contact between the wire and the workpiece is detected, the wire feed speed is a steady wire feed speed that is a feed speed during steady welding that is higher than the first feed speed from the first feed speed. A step of continuously changing the feeding speed;
A welding voltage applied between the wire and the workpiece to be welded is synchronized with a change in the continuous wire feeding speed from the first feeding speed to the steady wire feeding speed. Continuously changing from the voltage at the time of contact with the workpiece to the first welding voltage higher than the steady welding voltage that is the welding voltage at the time of steady welding;
When the first time elapses from the time when the wire and the workpiece are in contact, the welding voltage is continuously changed from the first welding voltage toward the steady welding voltage regardless of the wire feed speed. Arc welding control method comprising the steps of: The time until the welding voltage changes from the first welding voltage to the steady welding voltage from the time when the wire and the workpiece are in contact, or at least one of the magnitudes of the first welding voltage can be adjusted. The arc welding control method according to 1. An arc welding apparatus that starts an arc by bringing the wire into contact with the work piece in a state where a voltage is applied between the wire as a consumable electrode and the work piece during an arc start period before the steady welding period. There,
A welding current detector for detecting a welding current;
A contact detection unit that detects contact between the wire and the workpiece to be welded based on a signal from the welding current detection unit;
A wire feed speed control unit for controlling the feed speed of the wire;
A control unit that controls a welding voltage applied between the wire and the workpiece;
A counter unit that counts an elapsed time from the time when the wire and the workpiece are in contact with each other based on a signal from the contact detection unit;
The wire feeding speed control unit feeds the wire toward the workpiece at a first feeding speed, and when the wire and the workpiece are in contact with each other, the wire feeding speed control unit sets the feeding speed of the wire. Continuously changing from a first feeding speed to a steady wire feeding speed that is a feeding speed at the time of steady welding faster than the first feeding speed;
The control unit applies a voltage between the wire and the workpiece, and when the wire and the workpiece are in contact with each other, from the first feeding speed by the wire feeding speed control unit, The welding voltage applied between the wire and the workpiece to be welded is synchronized with the change of the continuous wire feeding speed to the steady wire feeding speed. When the first time elapses from the time when the wire and the workpiece to be welded are continuously changed from the voltage to the first welding voltage higher than the steady welding voltage that is the welding voltage at the time of steady welding. An arc welding apparatus that continuously changes the welding voltage from the first welding voltage toward the steady welding voltage regardless of the wire feed speed. It further comprises a setting unit for setting welding conditions,
The time from when the wire comes into contact with the workpiece to be welded until the welding voltage changes from the first welding voltage to the steady welding voltage, or the magnitude of the first welding voltage is set by the setting unit. Determined by the control unit based on at least one of the set welding current set to perform welding, the set welding voltage set to perform welding, the wire feed speed, the shield gas type, the wire material, the wire diameter, and the welding method. The arc welding apparatus according to claim 3.