JP6524412B2 - Arc welding control method - Google Patents

Description

  According to the present invention, the feeding of the welding wire is periodically changed at a predetermined period and a predetermined amplitude alternately in forward feeding in which the welding wire is fed in the direction of the object to be welded and in reverse feeding in the direction opposite to the forward feeding. The present invention relates to a consumable electrode type arc welding control method in which welding is performed by feeding at a high wire feeding speed and repeating an arc period and a short circuit period.

  In recent years, for the purpose of reducing spatter generated during welding, consumable electrode type arc welding that performs welding by alternately feeding forward and reverse feeding of welding wire and alternately generating an arc period and a short circuit period. It has been put to practical use.

  FIG. 5 is an output waveform diagram showing an arc welding control method according to the prior art in which welding is performed by repeating forward feeding and reverse feeding and alternately generating an arc period and a short circuit period. The figure (A) shows wire feeding speed Wf, the figure (B) shows welding current Aw, and the figure (C) shows the time change of welding voltage Vw.

  In the figure, in the short circuit period from time t1 to time t2, when a short circuit occurs at time t1, the wire feeding speed Wf is the wire feeding speed Wfs which is reverse feeding from the wire feeding speed Wfa which is forward feeding. Transition towards As a result, the welding wire is fed back. In addition, in the short circuit period, the welding current Aw increases with the passage of time by current control.

  As mentioned above, by reversing the feed of the welding wire during the short circuit period, the amount of welding wire fed during the short circuit period is reduced. Thereby, compared with the case where a welding wire is fed by fixed feeding, since a short circuit can be opened mechanically, the electric current at the time of short circuit can be reduced, and the amount of spatters generated at the time of short circuit opening can be reduced. reference).

Patent No. 4211793 gazette

  Conducting feed control of the welding wire in the above-described conventional arc welding control method leads to reduction of spatter, but prevents disturbance of the short circuit period due to disturbance such as irregular movement of the molten pool, fluctuation of arc length, etc. Can not. If the short circuit condition continues for a long time due to the short circuit cycle disturbance, the welding wire delivery continues to be reverse fed during the short circuit period, during which the welding wire delivery amount is reduced, leading to the formation of uneven bead with unevenness. . Further, in CO 2 welding, spattering is apt to occur particularly due to a short circuit in a very short time (hereinafter referred to as a minute short circuit) immediately after the arc occurrence and during the short circuit occurrence of the arc period. When the short circuit cycle is disturbed, the behavior of the molten pool becomes large, so a micro short circuit is easily generated, and there is a problem that the spatter due to the micro short circuit increases.

A wire feeding speed which is periodically changed at a predetermined cycle and at a predetermined amplitude alternately in forward feeding in which welding wires are fed in the direction of the object to be welded and in reverse feeding in the reverse direction to forward feeding. The consumable electrode type arc welding control method in which welding is performed by repeating the arc period and the short circuit period, and when the short circuit period continues for a predetermined period or more, the wire feeding speed is The absolute value is controlled to be larger than the reverse wire feeding speed at the time when the predetermined period is reached. In addition, wire feeding in which the feeding of the welding wire is alternately changed in the direction of the object to be welded and in the reverse direction in which the forward feeding is performed in the opposite direction is periodically changed with a predetermined cycle and a predetermined amplitude. A consumable electrode type arc welding control method in which welding is performed by feeding at a feed rate and repeating an arc period and a short circuit period, wherein the short circuit period after the start of the short circuit is longer than the last short circuit period. When it becomes, the wire feeding speed of reverse feeding is controlled to an absolute value larger than the wire feeding speed of reverse feeding at the end of the last short circuit period.
In addition, wire feeding in which the feeding of the welding wire is alternately changed in the direction of the object to be welded and in the reverse direction in which the forward feeding is performed in the opposite direction is periodically changed with a predetermined cycle and a predetermined amplitude. A consumable electrode type arc welding control method in which welding is performed by feeding at a feed rate and repeating an arc period and a short circuit period, wherein short circuiting is started as compared with the average value of one or more of the previous short circuit periods. When the short circuit period after long becomes long, the wire feeding speed of the reverse feed is controlled to a value larger in absolute value than the average speed of the reverse feed at the end of the previous short circuit period.
In addition, the average value of the short circuit period and the average speed of the wire feeding speed of the reverse feed at the end of the short circuit period are acquired in advance, and a predetermined period equal to or more than the average value of the short circuit period is set. If the time period is longer than the predetermined time period, the wire feeding speed for reverse feeding is controlled to a value larger in absolute value than the average speed for reverse feeding previously acquired.
When the short circuit period continues for a predetermined period or more, the welding current is controlled to a value larger than the welding current at the time when the predetermined period is reached.
In addition, when the short circuit period continues for a predetermined period or more, the slope of the wire feed speed of reverse feed is controlled to a larger value than the slope of the wire feed speed of reverse feed before the short circuit period reaches the predetermined period. .
Further, the inclination of the wire feeding speed from reverse feeding to forward feeding is controlled to a different value according to the time from the time when the short circuit period reaches the predetermined time to the time when the short circuit opening is performed.
Also, the welding wire is a material of high thermal conductivity either of aluminum, aluminum alloy, copper or copper alloy.

  The present invention can lead to the short circuit opening early by controlling the wire feeding speed of the reverse feed to a larger absolute value when the short circuit period continues for a predetermined period or longer. By preventing the prolongation of the short circuit period and stabilizing the short circuit period, a uniform flat bead appearance with reduced unevenness can be obtained, and the welding quality is improved. In addition, the occurrence of a minute short circuit can be suppressed, the amount of spatter can be reduced, and stable welding can be realized.

The figure of the output waveform by the arc welding control method in Embodiment 1, 2 of the present invention The figure which shows schematic structure of the arc welding apparatus in this invention The figure which shows the change of the inclination of the feed speed in Embodiment 3 of this invention. The figure which shows the output waveform by the arc-welding control method in Embodiment 3 of this invention The figure which shows the output waveform in the conventional arc welding control method

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 4.

Embodiment 1
First, an arc welding apparatus which performs the arc welding control method of the present embodiment will be described with reference to FIG. FIG. 2 is a view showing a schematic configuration of an arc welding apparatus. The arc welding apparatus 20 performs welding by repeating an arc state and a short circuit state between the welding wire 22 which is a consumable electrode and the workpiece 21.
The arc welding apparatus 20 includes a main transformer 2, a primary side rectification unit 3, a switching unit 4, a DCL (reactor) 5, a secondary side rectification unit 6, a welding current detection unit 7, and a welding voltage detection unit 8, a short circuit detection unit 9, an output control unit 12, and a wire feeding speed control unit 16.

  The short circuit detection unit 9 includes a short circuit time detection unit 10 and a short circuit / arc detection unit 11. The output control unit 12 includes a short circuit control unit 13 and an arc control unit 14. The wire feeding speed control unit 16 includes a wire feeding speed detection unit 17, an arithmetic unit 18, and a forward / reverse feeding switching timing control unit 19. The primary side rectifying unit 3 rectifies an input voltage input from an input power supply located outside the arc welding apparatus 20. The switching unit 4 controls the output of the primary side rectifying unit 3 to an output suitable for welding. The main transformer 2 converts the output of the switching unit 4 into an output suitable for welding. The secondary side rectifier 6 rectifies the output of the main transformer 2. The DCL (reactor) 5 smoothes the output of the secondary side rectifier 6 to a current suitable for welding. The welding current detection unit 7 detects a welding current. The welding voltage detection unit 8 detects a welding voltage. The short circuit time detection unit 10 detects the time during which the welding wire 22 and the workpiece 21 are shorted based on the output of the welding voltage detection unit 8. The short-circuit / arc detection unit 11 determines whether the welding state is a short-circuit state in which the welding wire 22 and the workpiece 21 are short-circuited based on the output of the welding voltage detection unit 8 or the welding wire 22 and the workpiece It is determined whether or not the arc 23 is in an arc state in which the arc 23 is generated. The output control unit 12 outputs a control signal to the switching unit 4 to control the welding output. The short circuit control unit 13 controls the short circuit current, which is the welding current in the short circuit period, when it is determined that the short circuit / arc detection unit 11 is in the short circuit state. The arc control unit 14 controls an arc current, which is a welding current in an arc period, when it is determined that the short circuit / arc detection unit 11 is in the arc state. The wire feeding speed control unit 16 controls the wire feeding unit 25 to control the feeding speed of the welding wire 22. The wire feeding speed detection unit 17 detects a wire feeding speed. The computing unit 18 computes the integrated amount of the feeding time of the welding wire 22 or the predetermined time based on the signal from the wire feeding speed detecting unit 17. The forward feed / reverse feed switching timing control unit 19 controls the feed of the welding wire 22 based on the signal from the calculation unit 18 to delay the switching timing from forward feed to reverse feed, or from reverse feed to forward feed. Output a control signal that delays the switching timing.

  A welding condition setting unit 15 and a wire feeding unit 25 are connected to the arc welding apparatus 20. Welding condition setting unit 15 is used to set welding conditions in arc welding apparatus 20. The wire feeding unit 25 controls the feeding of the welding wire 22 based on the signal from the wire feeding speed control unit 16.

  The welding output of the arc welding apparatus 20 is supplied to the welding wire 22 via the welding tip 24. Then, welding is performed by generating an arc 23 between the welding wire 22 and the object to be welded 21 by the welding output of the arc welding apparatus 20.

  Next, the operation of the arc welding apparatus 20 configured as described above will be described using FIG.

  FIG. 1 is a diagram showing an output waveform according to a consumable electrode type arc welding control method in the present embodiment. The time change of the wire feeding speed Wf, the welding current Aw, and the welding voltage Vw in the arc welding which alternately repeats a short circuit period and an arc period is shown.

  In FIG. 1, the wire feeding speed Wf which is periodically changed at a predetermined cycle and a predetermined amplitude alternately between forward feeding in the direction of the object to be welded and reverse feeding in the reverse direction of the forward feeding is predetermined The forward feed and the reverse feed are controlled to be periodically repeated, for example, in a trapezoidal wave that is a basic waveform, at a frequency F of F and a predetermined velocity amplitude AV. However, the cycle T which is the reciprocal of the frequency is the sum of the short circuit period Ts from time t1 to time t2 and the arc period Ta from time t2 to time t3. The wire feeding speed Wf in the short circuit period Ts from the start of the short circuit opening to the short circuit opening is controlled to shift from the forward feeding speed Wfa to the reverse feeding speed Wfs, and the reverse feeding speed Wfs. Is controlled to be constant at this reverse feed speed Wfs. The wire feeding speed Wf in the arc period Ta is controlled to shift from the reverse feeding speed Wfs to the forward feeding speed Wfa, and when the forward feeding speed Wfa is reached, the reverse feeding is performed. It is controlled to be constant at the feed speed Wfa of.

  The forward feeding speed and the reverse feeding speed of the wire feeding speed Wf, that is, the shape of the feeding waveform such as the period, the amplitude and the inclination are previously determined for each set current set in the arc welding apparatus.

  The control of the welding current Aw increases the welding current to a predetermined peak current value in the arc period Ta, thereby increasing the melting speed of the tip of the welding wire to form a droplet. Then, the droplet is transferred to the melting pool in the short circuit period Ts. Welding is performed by repeating this.

  In the short circuit period Ts, in order to open the short circuit state, the welding current is controlled to be increased with the passage of time. Then, as this form of increase, for example, as shown in FIG. 1, the first current increase slope AWa1 is first increased, and then the second current increase slope having a gentler slope than the first current increase slope AWa1. Increase by AWa2. A current value when switching from the first current increase slope AWa1 to the second current increase slope AWa2 is called a bending point.

The waveform of the wire feeding speed Wf which repeats forward feeding and reverse feeding may be a trapezoidal wave as shown in FIG. 1 or may be a sine wave.
Also, as the wire feeding speed Wf, in the trapezoidal wave, as shown in FIG. 1, when it reaches the feeding speed Wfs for reverse feeding and the feeding speed Wfa for forward feeding, they are respectively fixed and held. In this case, it is not necessary to necessarily maintain the reached value of the feed speed at a constant value, as long as it is an amplitude amount respectively corresponding to the feed speed Wfs for reverse feed and the feed speed Wfa for forward feed.

FIG. 1 is a diagram showing the time change of the wire feeding speed Wf and the welding current Aw, and is a diagram showing the wire feeding control when the short circuit cycle is disturbed or the short circuit time becomes long. This is particularly difficult when using a wire of a material with high thermal conductivity such as aluminum, aluminum alloy, copper, copper alloy, braze, etc. and high resistance to joule heating, short circuit opening is difficult to occur, and dispersion of droplet transfer state is within the short circuit period. It appears prominently as variation.
There are disturbances such as the irregular movement of the molten pool and the fluctuation of the arc length as a factor of the increase of the short circuit period.

Therefore, in the first embodiment, after the welding wire 22 shorts to the workpiece 21, the short circuit time detection unit 10 based on the welding voltage detection unit 8 determines a short circuit period Ts1 in which the short circuit period Ts is less than a predetermined period. In the inside, the welding wire is made to have a predetermined wire feeding speed inclination WFs1, and the reverse feeding is performed at the reverse feeding wire feeding speed Wfs.
Even if the short circuit / arc detection unit 11 does not open the short circuit (arc detection) even if the predetermined period is exceeded, the reverse feed is performed at the reverse feed wire feed speed Wfs' whose absolute value is larger than the reverse feed wire feed speed Wfs. As a result, the welding wire 22 is short-circuited open from the object to be welded 21 to lead it to be released.
The predetermined period is an average short circuit period from the start of the short circuit to the end of the short circuit (short circuit open), and the area where the wire feeding speed is reverse feeding (the wire feeding state is reverse feeding) Period of time.

  In addition, the predetermined period may be a short circuit period immediately before or may be an average value of one or more previous short circuit periods. Alternatively, the predetermined period may be an average value of the short circuit periods acquired in advance.

  In addition, the predetermined period may be an average short circuit period determined in advance by experiments, experience values, or the like from the start of the short circuit to the end of the short circuit (short circuit opening).

  In addition, the wire feeding speed Wfs' of reverse feeding at this time can be set to 100 to 200% of the absolute value of the wire feeding speed Wfs of the last feeding, for example, the average value of short circuit period and short circuit in advance. Acquire the average speed of the wire feed speed for reverse feed at the end of the period, set a predetermined period equal to or more than the average value of the short circuit period, and the short circuit period after starting the short circuit becomes longer than the predetermined period, The wire feeding speed of reverse feeding may be a value larger in absolute value than the average speed of reverse feeding previously acquired.

  As described above, when the short circuit period becomes longer than the predetermined period, it is possible to lead to the short circuit open early by setting the wire feeding speed of the reverse feed to a larger absolute value.

  In addition, if the predetermined period is the immediately preceding short circuit period, the recovery from the prolongation of the short circuit period is quicker, and if the predetermined period is the average value of the one or more short circuit periods, the short circuit period is stabilized. . Further, by setting the predetermined period as the average value of the short circuit periods acquired in advance, stabilization of the short circuit cycle can be realized appropriately for different welding wires and works.

Second Embodiment
The second embodiment relates to an increase in welding current at the time of short circuit when the short circuit period is prolonged.

  In Embodiment 2, parts similar to those in Embodiment 1 are assigned the same reference numerals and detailed explanations thereof will be omitted. The main difference from the first embodiment is that the third current increase is a value larger than the second current increase slope AWa2 as shown in FIG. 1 when the short circuit is not opened (arc detection) beyond the predetermined period. At the slope AWa3, the welding current is increased. By increasing the welding current at the time of the short circuit, the welding wire 22 is easily melted, and the effect of promoting the short circuit opening and the electromagnetic pinch force act on the droplet to form a neck and promote the detachment.

  As described above, when the short circuit period continues for a predetermined period or more, the short circuit opening is further promoted by setting the welding current to a value larger than the welding current at the time when the predetermined period is reached (early leads to short circuit open )be able to.

Third Embodiment
The third embodiment relates to suppression of the decrease in the wire feeding amount due to the prolongation of the short circuit period. In the third embodiment, the same parts as those of the first and second embodiments are denoted by the same reference numerals and the detailed description will be omitted. The main point that differs from the first and second embodiments is that the reverse feed is performed at the reverse feed wire feed speed Wfs', which is larger in absolute value than the reverse feed wire feed speed Wfs until the short circuit is opened. The short-circuit period becomes longer and the amount of forward wire feeding decreases as the reverse feed is continued at the feeding wire feed speed Wfs'. In order to prevent this, the slope WFs2 of the wire feeding speed when reaching the wire feeding speed Wfs' with a large absolute value from the wire feeding speed Wfs of the reverse feeding, the wire feeding speed Wfa of the forward feeding The absolute value of the wire feeding speed at which the wire feeding speed Wfs is reached is larger than the inclination WFs1 of the wire feeding speed. In addition, as shown in FIG. 3, short-circuit detection of the wire feed speed inclination WFa2 as acceleration / deceleration of the wire feed speed transitioning from the reverse wire feed speed Wfs' to the forward wire feed speed Wfa. The value is controlled to a different value depending on when the short circuit is opened, such as T1 to T3, which is a post-elapsed time. As shown in FIG. 3B, when the time when the short circuit is opened is an elapsed time T1 after detection of the short circuit, the wire feeding speed shifts from the wire feeding speed Wfs' for reverse feeding to the wire feeding speed Wfa for forward feeding. The slope WFa2 of is set to WFT1. Similarly, when the time when the short circuit is opened is an elapsed time T2 after detection of the short circuit, the slope WFa2 of the wire feeding speed to shift from the wire feeding speed Wfs' for reverse feeding to the wire feeding speed Wfa for forward feeding is WFT2. When the elapsed time T3 after the detection of the short circuit, the inclination WFa2 of the wire feeding speed to shift from the wire feeding speed Wfs' for reverse feeding to the wire feeding speed Wfa for forward feeding is set as WFT3. This prevents the prolongation of the next arc period due to the prolongation of the short circuit period and suppresses the disturbance of the short circuit cycle. In addition, the method of controlling the wire feeding speed of reverse feeding to a large value of the absolute value when the short circuit is not opened beyond the predetermined period is, for example, as shown in FIG. The wire feed speed is shifted to the wire feed speed Wfs. The reverse feed is performed at the wire feed speed inclination WFs2, and after the shift to the fixed reverse feed wire feed speed Wfs ', the short circuit is opened at the fixed reverse feed wire feed speed Wfs'. You may continue to send back. Alternatively, for example, as shown in FIG. 4, it is also possible to continue the reverse feed at the slope WFs2 of the wire feeding speed until the short circuit is opened.

  As described above, when the short circuit period is longer than the predetermined period, the wire feeding speed of the reverse feed is set to a larger absolute value to prevent the short circuit period from being extended. In addition, the slope of the wire feeding speed from the reverse feed to the forward feed after the opening of the short circuit was opened according to the time from the time when the short circuit period reaches the predetermined period to the time the short circuit open. By controlling the value to a different value depending on the time point, it is possible to prevent the prolongation of the short circuit period which will occur next, suppress the disturbance of the short circuit cycle, and help stabilize the short circuit cycle.

  According to the present invention, in arc welding in which forward feeding and reverse feeding are repeated as wire feeding speed, by stabilizing the short circuit period, it is possible to improve the welding quality and reduce the spatter generation amount due to the minute short circuit. It is industrially useful as an arc welding control method and an arc welding apparatus which performs arc welding while continuously feeding a welding wire which is a consumable electrode.

1 Input power supply 2 Main transformer (transformer)
3 Primary side rectification unit 4 Switching unit 5 DCL (reactor)
DESCRIPTION OF SYMBOLS 6 Secondary side rectification part 7 Welding current detection part 8 Welding voltage detection part 9 Short circuit detection part 10 Short circuit time detection part 11 Short circuit / arc detection part 12 Output control part 13 Short circuit control part 14 Arc control part 15 Welding condition setting part 16 Wire Feeding speed control unit 17 Wire feeding speed detecting unit 18 Arithmetic unit 19 Forward feed / reverse feed switching timing control unit 20 Arc welding apparatus 21 Welded object 22 Welding wire 23 Arc 24 Weld tip 25 Wire feeding unit

Claims (7)

A wire feeding speed which is periodically changed at a predetermined cycle and at a predetermined amplitude alternately in forward feeding in which welding wires are fed in the direction of the object to be welded and in reverse feeding in the reverse direction to forward feeding. A consumable electrode type arc welding control method in which welding is performed by repeating the arc period and the short circuit period, and when the short circuit period continues for a predetermined period or longer, the reverse The arc welding control method which controls to the value whose absolute value is larger than the wire feeding speed of reverse feeding at the time of having reached the predetermined period. A wire feeding speed which is periodically changed at a predetermined cycle and at a predetermined amplitude alternately in forward feeding in which welding wires are fed in the direction of the object to be welded and in reverse feeding in the reverse direction to forward feeding. It is a consumable electrode type arc welding control method in which welding is performed by repeatedly feeding the arc period and the short circuit period,
If the shorting period after the start of the shorting becomes longer than the shorting period just before, the wire feeding speed for reverse feeding is larger in absolute value than the wire feeding speed for reverse feeding at the end of the shorting period immediately before Arc welding control method to control to the value. A wire feeding speed which is periodically changed at a predetermined cycle and at a predetermined amplitude alternately in forward feeding in which welding wires are fed in the direction of the object to be welded and in reverse feeding in the reverse direction to forward feeding. It is a consumable electrode type arc welding control method in which welding is performed by repeatedly feeding the arc period and the short circuit period,
If the shorting period after the start of the shorting becomes longer than the average value of the one or more shorting periods before, the wire feeding speed of the reverse feeding is the average speed of the reverse feeding at the end of the previous shorting period Arc welding control method to control to larger absolute value. The arc welding control method according to any one of claims 1 to 3, wherein when the short circuit period continues for a predetermined period or more, the welding current is controlled to a value larger than the welding current at the time when the predetermined period is reached. The slope of the wire feed rate of reverse feed when the short circuit period continues for the predetermined period or longer is an absolute value of the slope of the wire feed velocity of reverse feed when the short circuit period reaches the predetermined period. The arc welding control method according to any one of claims 1 to 3, wherein the value is controlled to a large value. The inclination of the wire feeding speed from reverse feeding to forward feeding is controlled to a different value in accordance with the time from the time when the short circuit period reaches the predetermined time to the time when the short circuit is open. The arc welding control method in any one. The welding wire of aluminum, aluminum alloy, copper or arc welding control method according to any one of claims 1 to 3, which is the material of one of the high thermal conductivity of copper alloy.

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