JP5038206B2 - Constriction detection control method for consumable electrode arc welding - Google Patents

Abstract

The neckdown detection control method for an arc welding of consumable electrode detects a necking formation of a molten drop by reaching a neckdown detection standard value V(tn) through the change of a voltage (Vw) between a molten electrode and a base metal, to make a welding current (Iw) to decrease rapidly to regenerate electric arc under a state of low current. When an advancing angle setting signal is increasing, the value of the neckdown detection standard value (Vtn) is reduced. Therefrom, it is able to detect neckdown rapidly due to higher neckdown detection sensitivity. The result is that the molten drop transition is end almost after regenerating the electric arc because the time from neckdown detection till regenerating the electric arc may be added, thus it is able to restrain sputtering, such that it is able to restrain the sputtering through detection of molten drop neckdown and rapid decrease of welding current during arc welding period. The effect of decreasing sputtering may be implemented even though the advanced angle is large.

Description

  The present invention relates to a constriction detection control method of consumable electrode arc welding for detecting a constriction phenomenon of a droplet during a short-circuiting period and rapidly reducing a welding current to improve welding quality.

  FIG. 8 is a diagram showing current / voltage waveforms and droplet transfer in consumable electrode arc welding in which the short-circuit period Ts and the arc period Ta are repeated. FIG. 4A shows the change over time in the welding current Iw for energizing the consumable electrode (hereinafter referred to as welding wire 1), and FIG. 4B shows the time of the welding voltage Vw applied between the welding wire 1 and the base material 2. FIG. FIGS. 3C to 3E show the transition of the droplet 1a. Hereinafter, a description will be given with reference to FIG.

  During the short-circuit period Ts at times t1 to t3, the droplet 1a at the tip of the welding wire 1 is in a short-circuit state with the base material 2, and as shown in FIG. Iw gradually increases, and the welding voltage Vw becomes a low value of about several volts because the welding voltage Vw is in a short circuit state as shown in FIG. The increasing slope and peak value of the short-circuit current are controlled to appropriate values. As shown in FIG. 5C, the droplet 1a comes into contact with the base material 2 at a time t1 to enter a short circuit state. Thereafter, as shown in FIG. 4D, a constriction 1b is generated at the upper part of the droplet 1a by an electromagnetic pinch force generated by a welding current Iw for energizing the droplet 1a. And this constriction 1b advances rapidly, and as shown to the same figure (E) at the time t3, the droplet 1a transfers from the welding wire 1 to the molten pool 2a, and the arc 3 regenerates. At this time, spatter 1c is generated.

  When the above-mentioned constriction phenomenon occurs, the short circuit is released after an extremely short time of about several hundred μs, and the arc 3 is regenerated. That is, this constriction phenomenon is a precursor of short circuit opening. When the constriction 1b occurs, the conduction path of the welding current Iw becomes narrow at the constricted portion, and the resistance value of the constricted portion increases. The increase in the resistance value increases as the constriction progresses and the constricted portion becomes narrower. Therefore, the occurrence and progress of the constriction phenomenon can be detected by detecting the change in resistance value between the welding wire 1 and the base material 2 during the short-circuit period Ts. This change in resistance value can be calculated by welding voltage Vw / welding current Iw. Further, as described above, since the constriction occurrence time is extremely short, the change in the welding current Iw during this period is small as shown in FIG. For this reason, the occurrence of the constriction phenomenon can be detected by the change of the welding voltage Vw instead of the change of the resistance value. As a specific necking detection method, a change rate (differential value) of the resistance value or the welding voltage value Vw during the short-circuit period Ts is calculated, and the necking detection is performed when the rate of change reaches a predetermined necking detection reference value. There is a way to do. As another method, as shown in FIG. 5B, a voltage increase value ΔV from a stable short-circuit voltage value Vs before occurrence of constriction during the short-circuit period Ts is calculated, and this voltage increase value ΔV is calculated at time t2. There is a method of detecting the squeezing when the squeezing reaches a predetermined squeezing detection reference value Vtn. In the following description, a case in which the squeezing detection method is based on the above-described voltage increase value ΔV will be described, but other methods that have been proposed in the past may be used. Detection of arc reoccurrence at time t3 can be easily performed by determining that the welding voltage Vw has become equal to or greater than the short circuit / arc determination value Vta. Incidentally, the period of Vw <Vta is the short circuit period Ts, and the period of Vw ≧ Vta is the arc period Ta. The time from the occurrence of squeezing at times t2 to t3 to the reoccurrence of the arc is hereinafter referred to as squeezing detection time Tn. When the arc is regenerated at the time t3, the welding current Iw gradually decreases after rapidly increasing as shown in FIG. 9A, and the welding voltage Vw is about several tens of volts as shown in FIG. Arc voltage value. During the arc period Ta from time t3 to t4, the tip of the welding wire 1 is melted to form a droplet 1a. Thereafter, the operation in the period from time t1 to t4 is repeated.

  In the welding with short circuit described above, when the arc regeneration current value Ia when the arc 3 is regenerated at the time t3 is a large current value, the arc force from the arc 3 to the molten pool 2a increases sharply. A large amount of spatter 1c is generated. That is, the generation amount of the sputter 1c increases substantially in proportion to the current value Ia at the time of arc regeneration. Therefore, in order to suppress the generation of the spatter 1c, it is necessary to reduce the current value Ia at the time of arc re-occurrence. As a method for this, various welding power sources have been proposed in which a constriction detection control method is added to detect the occurrence of the above-mentioned constriction phenomenon, to rapidly reduce the welding current Iw and to reduce the current value Ia at the time of arc reoccurrence. . Hereinafter, this conventional technique (for example, refer to Patent Document 1) will be described.

  FIG. 9 is a block diagram of a welding apparatus that employs a conventional squeezing detection control method. The welding power source PS is a welding power source for general consumable electrode arc welding, and outputs an output voltage Vo and a welding current Iw. The transistor TR is inserted in series with the output, and a resistor R is connected in parallel therewith. A welding voltage Vw is applied between the welding wire 1 and the base material 2, and an arc 3 is generated. The illustration of the feeding mechanism of the welding wire 1 is omitted. The squeezing detection reference value setting circuit VTN outputs a squeezing detection reference value signal Vtn. The squeezing detection control circuit ND assumes a high level when the welding voltage Vw is input to detect that the squeezing of the droplet has occurred during the short-circuit period by the voltage increase value ΔV reaching the value of the squeezing detection reference value signal Vtn. The necking detection signal Nd is output. When the squeezing detection signal Nd is at a low level (when non-necking is detected), the driving circuit DR outputs a driving signal Dr that turns on the transistor TR. Therefore, the transistor TR is turned off when the squeezing detection signal Nd is at a high level (when squeezing is detected).

  FIG. 10 is a timing chart of each signal of the welding apparatus. (A) shows the welding current Iw, (B) shows the welding voltage Vw, (C) shows the squeezing detection signal Nd, and (D) shows the drive signal Dr. Hereinafter, a description will be given with reference to FIG.

  In the figure, during a period other than the squeezing detection time Tn from time t2 to t3, as shown in FIG. 10C, the squeezing detection signal Nd is at the low level, and as shown in FIG. The signal Dr becomes a high level. As a result, since the transistor TR is turned on, the operation is the same as that of a normal welding power source for consumable electrode arc welding.

  At time t2, as shown in FIG. 4B, it is detected that the welding voltage Vw has increased during the short-circuit period Ts and the voltage increase value ΔV has become equal to or greater than the value of the squeezing detection reference value signal Vtn. If it is determined that constriction has occurred, the constriction detection signal Nd becomes High level as shown in FIG. In response to this, as shown in FIG. 4D, the drive signal Dr goes to a low level, so that the transistor TR is turned off. As a result, the resistor R is inserted into the energization path of the welding current Iw. Since the value of this resistor R is set to a value that is at least 10 times larger than the short-circuit load (several tens of mΩ), it is accumulated in the DC reactor in the welding power source and the cable reactor as shown in FIG. As a result, the welding current Iw decreases rapidly. At time t3, when the short circuit is released and the arc is regenerated, the welding voltage Vw becomes equal to or higher than a predetermined short circuit / arc discrimination value Vta as shown in FIG. By detecting this, the squeezing detection signal Nd becomes the Low level as shown in FIG. 5C, and the drive signal Dr becomes the High level as shown in FIG. As a result, the transistor TR is turned on, and normal consumable electrode arc welding is controlled. By this operation, the arc regeneration current value Ia at the time of arc regeneration (time t3) can be reduced, and the occurrence of sputtering can be suppressed.

JP 2006-281219 A

  As described above, in the squeezing detection control method of the prior art, the occurrence of spatter can be reduced by detecting the squeezing phenomenon and rapidly reducing the welding current to reduce the current value Ia when the arc is regenerated. However, as the advance angle of the welding torch increases, the spatter generation mechanism at the time of arc re-generation changes. Therefore, the spatter generation cannot be significantly reduced only by reducing the current value Ia at the time of arc re-generation. Hereinafter, the spatter generation mechanism when the advance angle becomes large will be described.

  FIG. 11 is a diagram illustrating a state of droplet transfer when the advance angle θ is large. FIGS. 9A to 9D are the same as FIG. 10 described above. FIGS. 4E to 4G show the transition state of the droplet 1a at each timing. Hereinafter, a description will be given with reference to FIG.

  When the droplet 1a formed at the tip of the welding wire 1 comes into contact with the molten pool 2a on the base material 2 at time t1, as shown in FIG. As shown in FIG. 5E, the welding torch 4 is in a welding posture of the advance angle θ. In the short circuit period Ts, the welding current Iw increases as shown in FIG. 5A, and the welding voltage Vw becomes a low value of the short circuit voltage as shown in FIG.

  As shown in FIG. 4A, an electromagnetic pinch force acts on the droplet 1a as the welding current Iw increases, and as shown in FIG. 4F, a constriction 1b is formed at the upper portion of the droplet 1a. Is formed. The constriction 1b is formed non-target because the droplet 1a that is short-circuited due to the advance angle is inclined. When the occurrence of the constriction 1b is detected when the voltage increase value ΔV reaches the value of the constriction detection reference value signal Vtn as shown in FIG. 5B, the constriction is detected as shown in FIG. The signal Nd becomes High level at time t2. In response to this, the welding current Iw decreases rapidly to a low value as shown in FIG.

  As shown in FIG. 5F, the constriction 1b proceeds asymmetrically, and therefore the traveling speed thereof is slower than when the advance angle is small (when the constriction 1b is formed on a substantially target). As a result, as shown in FIG. 5G, the arc 3 is regenerated before the droplet 1a substantially moves to the molten pool 2a, and spatter 1c is generated. That is, as the advance angle θ increases, it takes a longer time to move the droplet 1a. Therefore, the arc 3 is regenerated before the droplet 1a is still sufficiently after the squeezing detection time Tn. As a result, spatter 1c is generated.

  Therefore, an object of the present invention is to provide a constriction detection control method for consumable electrode arc welding that can reduce the occurrence of spatter even when the advance angle of the welding torch is large.

In order to solve the above-described problem, the first invention
In consumable electrode arc welding where the arc generation state and short circuit state are repeated between the consumable electrode and the base material, the constriction phenomenon of droplets, which is a precursor to the arc re-occurring from the short circuit state, is observed between the consumable electrode and the base material. This is detected when the change in voltage value or resistance value reaches the squeezing detection reference value, and when this squeezing phenomenon is detected, the welding current that is applied to the short-circuit load is suddenly reduced and the arc is regenerated at a low current value. In the constriction detection control method of electrode arc welding,
Constriction detection time control for consumable electrode arc welding, characterized in that when the advance angle of the welding torch is increased, the squeezing detection time is controlled so that the squeezing detection time from the squeezing phenomenon detection time to the arc re-occurrence time becomes longer. Is the method.

  According to a second aspect of the present invention, in the constriction detection control for consumable electrode arc welding according to the first aspect, the constriction detection time control is performed by decreasing the constriction detection reference value when the advance angle increases. Is the method.

The third invention detects the squeezing detection time, changes the squeezing detection reference value by feedback control so that the detection value of the squeezing detection time becomes equal to the squeezing detection time set value,
In the constriction detection control method for consumable electrode arc welding according to the first aspect of the invention, the constriction detection time control is performed by increasing the constriction detection time set value when the advance angle increases.

4th invention changes it so that the peak value of the welding current which supplies with electricity to the said short circuit load may become small as the advance angle becomes large,
The constriction detection control method for consumable electrode arc welding according to any one of the first to third inventions.

  According to the first aspect of the invention, since the control is performed so that the squeezing detection time becomes longer as the advance angle becomes larger, the droplet transfer is completed immediately after the arc is regenerated. For this reason, an increase in spatter can be suppressed even if the advance angle is increased.

  According to the second aspect of the invention, the squeezing detection time is lengthened by reducing the squeezing detection reference value as the advance angle increases. As a result, even when the advance angle is increased, the transfer of the droplet is completed immediately after the arc is regenerated, so that the generation of spatter can be reduced.

  According to the third aspect of the invention, the squeezing detection time is lengthened by increasing the squeezing detection time set value as the advance angle increases. As a result, even when the advance angle is increased, the transfer of the droplet is completed immediately after the arc is regenerated, so that the generation of spatter can be reduced.

  According to the fourth aspect of the invention, by reducing the peak value of the welding current (short-circuit current) that energizes the short-circuit load as the advance angle becomes larger, excessive electromagnetic pinch is applied to the constricted portion that progresses unintentionally. It can suppress that force acts. For this reason, generation | occurrence | production of a sputter | spatter can further be reduced.

  Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment 1]
1 is a block diagram of a welding apparatus for carrying out a squeezing detection control method according to Embodiment 1 of the present invention. This figure corresponds to FIG. 9 described above, and the same reference numerals are given to the same blocks, and the description thereof is omitted. Hereinafter, blocks indicated by dotted lines different from those in FIG. 9 will be described with reference to FIG.

  The advance angle setting circuit θR outputs a predetermined advance angle setting signal θr. The advance angle corresponding squeezing detection reference value setting circuit Fθ receives the advance angle setting signal θr and calculates the value of the squeezing detection reference value signal Vtn by a predetermined advance angle corresponding squeezing detection reference value setting function f (θr). Output. This forward angle corresponding squeezing detection reference value setting function Vtn = f (θr) will be described later with reference to FIG. Constriction is detected according to the calculated squeezing detection reference value signal Vtn. The other blocks are the same as the corresponding blocks in FIG.

  The advance angle setting circuit θR may be set manually by a welding operator by providing a setting knob on the operation panel of the welding apparatus. When using a welding robot, the advance angle setting signal θr may be set from a teach pendant. Furthermore, the advance angle may be calculated from the teaching data of the robot and the advance angle setting signal θr may be automatically set.

  FIG. 2 is a diagram exemplifying the above-mentioned advance angle corresponding squeezing detection reference value setting function Vtn = f (θr). In the figure, the horizontal axis represents the advance angle setting signal θr, and the vertical axis represents the squeezing detection reference value signal Vtn. Hereinafter, a description will be given with reference to FIG.

  As shown in FIG. 6A, in the first example of the function f (θr), the value of the squeezing detection reference value signal Vtn decreases as the advance angle setting signal θr increases. Also, as shown in FIG. 5B, in the second example of the function f (θr), the value of the squeezing detection reference value signal Vtn is set to the first predetermined value when the advance angle setting signal θr is less than the predetermined value θp. If it is equal to or greater than θp, the second predetermined value is set to a value smaller than the first predetermined value. Further, as shown in FIG. 5C, in the third example of the function f (θr), the value of the squeezing detection reference value signal Vtn decreases as the value of the advance angle setting signal θr increases. Further, when the predetermined value θp or more is reached, the inversely proportional slope is increased.

    In FIG. 5B and FIG. 6C, the reason why θp is provided is that the generation of spatter further increases when the advance angle becomes equal to or greater than the predetermined value θp. θp is, for example, about 35 to 45.

  As described above, when the advancing angle is increased, the formation of the constriction becomes asymmetric, so that it takes time for the droplets to completely move to the molten pool. If the arc is regenerated before this transition is completed, sputtering will occur. Therefore, if control is performed so that the squeezing detection time Tn becomes longer as the advance angle becomes larger (necking detection time control), the transfer of the droplets is almost completed immediately after the arc is regenerated, and the spattering Occurrence can be reduced. In the first embodiment described above, as the necking detection time control, the necking detection reference value is made smaller as the advance angle becomes larger. As a result, the squeezing detection sensitivity becomes high, so that the occurrence of squeezing can be detected at an earlier stage. As a result, the constriction detection time becomes longer.

  Therefore, according to the first embodiment described above, the squeezing detection time is lengthened by reducing the squeezing detection reference value as the advance angle increases. As a result, even when the advance angle is increased, the transfer of the droplets is almost completed immediately after the arc is regenerated, so that the generation of spatter can be reduced.

[Embodiment 2]
FIG. 3 is a block diagram of a welding apparatus for carrying out the squeezing detection control method according to Embodiment 2 of the present invention. In the figure, the same blocks as those in FIG. 9 described above are denoted by the same reference numerals, and description thereof is omitted. Hereinafter, blocks indicated by dotted lines different from those in FIG. 9 will be described.

  The squeezing detection time detection circuit TND receives the squeezing detection signal Nd, detects the squeezing detection time Tn for each short circuit, calculates an average value thereof, and outputs a squeezing detection time detection signal Tnd.

  The advance angle setting circuit θR outputs a predetermined advance angle setting signal θr. The advance angle corresponding squeezing detection time setting circuit TNR receives the advance angle setting signal θr and outputs a squeezing detection time setting signal Tnr according to a predetermined advance angle corresponding squeezing detection time setting function g (θr). The error amplification circuit ET amplifies an error between the squeezing detection time setting signal Tnr and the squeezing detection time detection signal Tnd, and outputs a time error amplification signal ΔT. The error integration circuit SDT integrates the time error amplification signal ΔT and outputs a squeezing detection reference value signal Vtn. The necking is detected by this necking detection reference value signal Vtn and the necking detection control is performed.

  With the above configuration, the squeezing detection reference value signal Vtn is automatically adjusted by feedback control so that the value of the squeezing detection time detection signal Tnd becomes equal to the value of the squeezing detection time setting signal Tnr. Further, the value of the squeezing detection time setting signal Tnr changes to an appropriate value according to the advance angle setting signal θr. That is, when the value of the advance angle setting signal θr is increased, the value of the squeezing detection time setting signal Tnr is set to be longer. For this reason, the constriction detection time control is performed so that the constriction detection time Tn becomes longer as the advance angle becomes larger.

  FIG. 4 is a diagram for illustrating the above-described advance angle corresponding squeezing detection time setting function g (θr). In the figure, the horizontal axis represents the advance angle setting signal θr, and the vertical axis represents the squeezing detection time setting signal Tnr. Hereinafter, a description will be given with reference to FIG.

  As shown in FIG. 6A, in the first example of the function g (θr), the value of the squeezing detection time setting signal Tnr increases as the advance angle setting signal θr increases. Further, as shown in FIG. 5B, in the example 2 of the function g (θr), when the advance angle setting signal θr is less than the predetermined value θp, the value of the squeezing detection time setting signal Tnr is set to the first predetermined value. If it is equal to or greater than θp, the second predetermined value is set to a value larger than the first predetermined value. Further, as shown in FIG. 6C, in the third example of the function g (θr), the value of the squeezing detection time setting signal Tnr increases as the value of the advance angle setting signal θr increases. Further, when the value is equal to or greater than the predetermined value θp, the proportional gradient is increased.

    In FIG. 5B and FIG. 6C, the reason why θp is provided is that the generation of spatter further increases when the advance angle becomes equal to or greater than the predetermined value θp.

  As described above, when the advance angle becomes large, the formation of the constriction becomes asymmetric, so that it takes time for the droplets to move to the molten pool. If the arc occurs again before this transition is almost completed, spatter will occur. Therefore, if control is performed so that the squeezing detection time Tn becomes longer as the advance angle becomes larger (necking detection time control), the transfer of the droplets is almost completed immediately after the arc is regenerated, and the spattering Occurrence can be reduced. In the second embodiment described above, as the squeezing detection time control, the value of the squeezing detection time setting signal increases as the advance angle increases. As a result, the constriction detection time becomes longer.

  Therefore, according to the second embodiment described above, the squeezing detection time is lengthened by increasing the value of the squeezing detection time setting signal as the advance angle increases. As a result, even when the advance angle is increased, the transfer of the droplets is almost completed immediately after the arc is regenerated, so that the generation of spatter can be reduced.

[Embodiment 3]
FIG. 5 is a waveform diagram of a short-circuit current showing a constriction detection control method for consumable electrode arc welding according to Embodiment 3 of the present invention. FIG. 5A is a waveform diagram when the advance angle of the welding torch is small, and FIG. 4B is a waveform diagram when the advance angle is large. Hereinafter, a description will be given with reference to FIG.

  At time t1, when the droplet formed at the tip of the welding wire is in a short circuit state with the base material, a short circuit current that is a welding current for energizing the short circuit load increases. As shown in FIG. 5A, when it is detected that the constriction has occurred in the droplet at time t2, the short-circuit current rapidly decreases. When the arc is regenerated at time t3, the welding current increases. The same applies to the case of FIG. However, since the squeezing detection time control described above in Embodiments 1 and 2 acts, in the case of FIG. 5B where the advance angle is large, the timing at which the arc is regenerated after the squeezing is detected at time t2 is the time. Slower until t4. This is because when the advance angle is increased, the squeezing detection time at times t2 to t4 is controlled to be longer.

  The peak value of the short-circuit current in the same figure (A) becomes Ip1, and the peak value of the short-circuit current in the same figure (B) becomes Ip2. Here, the short-circuit current is controlled so that Ip1> Ip2. That is, the short circuit current is controlled so that the peak value of the short circuit current decreases as the advance angle increases. When the peak value of the short-circuit current is reduced when the advance angle is large, the electromagnetic pinch force acting on the constriction is weakened, so that the force for deforming the droplet is weakened. As a result, it is possible to suppress the occurrence of sputtering when the advance angle is large.

  FIG. 6 is a block diagram of a welding apparatus for carrying out a constriction detection control method for consumable electrode arc welding according to Embodiment 3 of the present invention. This figure corresponds to FIG. 1 described above, and the same blocks as those in FIG. The difference from FIG. 1 is that the advance angle setting signal θr is input to the welding power source PS. The rest is the same as FIG.

  FIG. 7 is a detailed block diagram of the welding power source PS in FIG. 6 described above. The welding power source PS shown in the figure receives an advance angle setting signal θr from the outside and outputs an output voltage Vo and a welding current Iw. Hereinafter, each block will be described with reference to FIG.

  The power supply main circuit PM receives a commercial power supply (not shown) such as three-phase 200V as input, performs output control by inverter control according to a pulse width modulation signal Pwm described later, and outputs an output voltage Vo and a welding current Iw. This power supply main circuit PM includes a primary rectifier for rectifying commercial power, a capacitor for smoothing the rectified direct current, an inverter circuit for converting the smoothed direct current to high frequency alternating current, and reducing the high frequency alternating current to a voltage value suitable for arc welding. High-frequency transformer, a secondary rectifier that rectifies the stepped-down high-frequency alternating current, a reactor that smoothes the rectified direct-current, and an inverter drive circuit that drives the switching element of the inverter circuit with the pulse width modulation signal Pwm as an input. The

  The current detection circuit ID detects the welding current Iw and outputs a current detection signal Id. The voltage detection circuit VD detects the output voltage Vo and outputs a voltage detection signal Vd. The short circuit determination signal SD receives the voltage detection signal Vd as an input, determines a short circuit period and an arc period based on the value, and outputs a short circuit determination signal Sd which is at a high level during the short circuit period and is at a low level during the arc period. To do. The voltage setting circuit VR outputs a predetermined voltage setting signal Vr. This voltage setting signal Vr sets the arc length by setting the arc voltage during the arc period. The voltage error amplification circuit EV amplifies an error between the voltage setting signal Vr and the voltage detection signal Vd, and outputs a voltage error amplification signal Ev.

  The peak value setting circuit IPR receives each forward setting signal θr from the outside and outputs a peak value setting signal Ipr corresponding to the value. The value of the peak value setting signal Ipr is set so as to decrease as the value of each forward setting signal θr increases. The short-circuit current waveform setting circuit ISR receives the peak value setting signal Ipr and outputs a short-circuit current waveform setting signal Isr for forming a short-circuit current waveform corresponding to the peak value. The current error amplification circuit EI amplifies an error between the short circuit current waveform setting signal Isr and the current detection signal Id, and outputs a current error amplification signal Ei. The external characteristic switching circuit SP receives the voltage error amplification signal Ev, the current error amplification signal Ei, and the short circuit determination signal Sd, and outputs an error amplification signal Ea. This external characteristic switching circuit SP outputs the voltage error amplification signal Ev as the error amplification signal Ea when the short circuit determination signal Sd is at the Low level (arc period), and the current error amplification signal Ei when it is at the High level (short circuit period). Is output as an error amplification signal Ea. Therefore, the external characteristics of the welding power source are constant voltage characteristics during the arc period and constant current characteristics during the short circuit period. Since the constant current characteristic is obtained during the short circuit period, a short circuit current according to the short circuit current waveform setting signal Isr can be applied. As a result, the peak value of the short circuit current is controlled to a value determined by the peak value setting signal Ipr.

  The pulse width modulation circuit PWM receives the error amplification signal Ea as described above, performs pulse width modulation control, and outputs a pulse width modulation signal Pwm. As a result, the output control of the inverter circuit included in the power source main circuit PM is performed by the pulse width modulation control. In the figure, the illustration of the block related to feeding of the welding wire is omitted.

  In the above-described third embodiment, the case where the squeezing detection time control is the method of the first embodiment has been described. However, the squeezing detection time control of the second embodiment can be similarly applied. .

  According to the above-described third embodiment, excessive electromagnetic is applied to the constricted portion that progresses unintentionally by reducing the peak value of the welding current (short-circuit current) that energizes the short-circuit load as the advance angle increases. It can suppress that pinch force acts. For this reason, generation | occurrence | production of a sputter | spatter can further be reduced.

  The functions f (θr) and g (θr) described above may be changed according to the welding method, the type of welding wire, the average welding current, and the like. Since the present invention can be applied to general consumable electrode arc welding, it can be applied to CO 2 welding, MAG / MIG welding, pulse arc welding, AC pulse arc welding, and the like.

It is a block diagram of the welding apparatus for enforcing the constriction detection control method which concerns on Embodiment 1 of this invention. FIG. 2 is a diagram for illustrating a forward angle corresponding squeezing detection reference value setting function f (θr) in FIG. 1. It is a block diagram of the welding apparatus for enforcing the constriction detection control method which concerns on Embodiment 2 of this invention. FIG. 4 is a view for illustrating a forward angle corresponding squeezing detection time setting function g (θr) in FIG. 3. It is a wave form diagram of a short circuit current which shows the constriction detection control method of consumable electrode arc welding concerning Embodiment 3 of the present invention. It is a block diagram of the welding apparatus for enforcing the constriction detection control method of the consumable electrode arc welding which concerns on Embodiment 3 of this invention. FIG. 7 is a detailed block diagram of a welding power source PS in FIG. 6. It is a current and voltage waveform diagram of consumable electrode arc welding in the prior art. It is a block diagram of the welding apparatus for enforcing the constriction detection control method in a prior art. It is a timing chart of each signal in the welding apparatus of FIG. It is a figure which shows the state of a droplet transfer in case the advance angle for demonstrating a subject is large.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Welding wire 1a Droplet 1b Constriction 1c Spatter 2 Base material 2a Weld pool 3 Arc 4 Welding torch DR Drive circuit Dr Drive signal Ea Error amplification signal EI Current error amplification circuit Ei Current error amplification signal ET Error amplification circuit EV Voltage error amplification circuit Ev Voltage error amplification signal f (θr) Advancing angle corresponding squeezing detection reference value setting function Fθ Advancing angle corresponding squeezing detection reference value setting circuit g (θr) Advancing angle corresponding squeezing detection time setting function Ia Current value ID when arc is regenerated Current detection Circuit Id Current detection signal Ip1, Ip2 Short circuit current peak value IPR Peak value setting circuit Ipr Peak value setting signal Iw Welding current ND Constriction detection control circuit Nd Constriction detection signal PM Power supply main circuit PWM Pulse width modulation circuit Pwm Pulse width modulation signal PS Welding power supply R Resistor SD Short circuit determination circuit Sd Short circuit determination signal SP External characteristic switching circuit S T error integration circuit Ta arc period Tn squeezing detection time TND squeezing detection time detection circuit Tnd squeezing detection time detection signal TNR squeezing detection time setting circuit Tnr squeezing detection time setting signal TR transistor Ts short circuit period VD voltage detection circuit Vd voltage detection signal Vo output Voltage VR Voltage setting circuit Vr Voltage setting signal Vs Short-circuit voltage value Vta Short-circuit / arc discrimination value VTN Necking detection reference value setting circuit Vtn Necking detection reference value (signal)
Vw Welding voltage ΔT Time error amplification signal ΔV Voltage increase value θ Advance angle θR Advance angle setting circuit θr Advance angle setting signal

Claims (4)

In consumable electrode arc welding where the arc generation state and short circuit state are repeated between the consumable electrode and the base material, the constriction phenomenon of droplets, which is a precursor to the arc re-occurring from the short circuit state, is observed between the consumable electrode and the base material. This is detected when the change in voltage value or resistance value reaches the squeezing detection reference value, and when this squeezing phenomenon is detected, the welding current that is applied to the short-circuit load is suddenly reduced and the arc is regenerated at a low current value. In the constriction detection control method of electrode arc welding,
Constriction detection time control for consumable electrode arc welding, characterized in that when the advance angle of the welding torch is increased, the squeezing detection time is controlled so that the squeezing detection time from the squeezing phenomenon detection time to the arc re-occurrence time becomes longer. Method.   2. The constriction detection control method of consumable electrode arc welding according to claim 1, wherein the constriction detection time control is performed by decreasing the constriction detection reference value when the advance angle is large. Detecting the squeezing detection time, changing the squeezing detection reference value by feedback control so that the detection value of the squeezing detection time is equal to the setting value of the squeezing detection time,
2. The constriction detection control method for consumable electrode arc welding according to claim 1, wherein the constriction detection time control is performed by increasing the set value of the constriction detection time when the advance angle increases. As the advance angle increases, the peak value of the welding current flowing through the short-circuit load is changed so as to decrease.
The constriction detection control method of consumable electrode arc welding according to any one of claims 1 to 3.

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