JP2021090994A - Arc-welding control method - Google Patents

Abstract

To keep a spatter occurrence rate low without being influenced by viscosity of a welding wire in a reciprocal feed arc welding method.SOLUTION: In an arc-welding control method for welding by repeating a short-circuit period and an arc period by alternately switching a feed speed Fw of a welding wire between a forward feed and a reverse feed, a forward feed peak value Wsp is made smaller as viscosity of the welding wire is lower. Further, an acceleration period Tsu to the forward feed peak value Wsp is made longer as the viscosity of the welding wire is lower. Further, a level of the viscosity of the welding wire is determined from a total mass % of silicon and manganese occupied in the welding wire. In this way, a spatter occurrence rate can be reduced regardless of the viscosity of the welding wire.SELECTED DRAWING: Figure 2

Description

The present invention relates to an arc welding control method in which the feed rate of a welding wire is alternately switched between forward feed and reverse feed, and a short circuit period and an arc period are repeatedly welded.

In general consumable electrode type arc welding, welding wire, which is a consumable electrode, is fed at a constant speed, and an arc is generated between the welding wire and the base metal to perform welding. In consumable electrode type arc welding, the welding wire and the base metal are often in a welded state in which short-circuit periods and arc periods are alternately repeated.

In order to further improve the welding quality, a forward / reverse feed arc welding method has been proposed in which the feed of the welding wire is alternately switched between forward feed and reverse feed for welding (see, for example, Patent Document 1). In this forward / reverse feed arc welding method, the cycle of repeating short circuit and arc can be stabilized as compared with the conventional technique of constant feed rate, so that the amount of spatter generated can be reduced, the bead appearance can be improved, etc. Welding quality can be improved.

Japanese Unexamined Patent Publication No. 2018-1270

Many brands of welding wire are sold for arc welding of steel materials. Since these welding wires have different components, they also have different viscosities. In forward / reverse feed arc welding, if a welding wire having a relatively low viscosity is used, there is a problem that the amount of spatter generated immediately after the arc is generated increases.

Therefore, an object of the present invention is to provide an arc welding control method capable of always reducing the amount of spatter generated without being affected by the viscosity of the welding wire in forward / reverse feed arc welding.

In order to solve the above-mentioned problems, the invention of claim 1 is
In the arc welding control method in which the feed rate of the welding wire is switched alternately between forward feed and reverse feed, and the short circuit period and the arc period are repeatedly welded.
The lower the viscosity of the welding wire, the smaller the peak value of the positive feed.
This is an arc welding control method characterized by the above.

The invention of claim 2 is
The lower the viscosity, the slower the acceleration of the positive feed to the peak value.
The arc welding control method according to claim 1, wherein the arc welding control method is characterized in that.

The invention of claim 3 is
The high or low viscosity is determined by the total mass% of silicon and manganese in the welding wire.
The arc welding control method according to claim 1 or 2, wherein the arc welding control method is characterized in that.

According to the present invention, in forward / reverse feed arc welding, the amount of spatter generated can always be kept small without being affected by the viscosity of the welding wire.

It is a block diagram of the welding power source for carrying out the arc welding control method which concerns on Embodiment 1 of this invention. It is a timing chart of each signal in the welding power source of FIG. 1 which shows the arc welding control method which concerns on Embodiment 1 of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Embodiment 1]
FIG. 1 is a block diagram of a welding power source for carrying out the arc welding control method according to the first embodiment of the present invention. Hereinafter, each block will be described with reference to the figure.

The power supply main circuit PM receives a commercial power supply (not shown) such as three-phase 200V as an input, performs output control by inverter control or the like according to an error amplification signal Ea described later, and outputs an output voltage E. Although not shown, this power supply main circuit PM is driven by a primary rectifier that rectifies a commercial power supply, a smoothing capacitor that smoothes the rectified DC, and the above-mentioned error amplification signal Ea that converts the smoothed DC into high-frequency AC. It is equipped with an inverter circuit that is used, a high-frequency transformer that steps down high-frequency AC to a voltage value suitable for welding, and a secondary rectifier that rectifies the stepped-down high-frequency AC to DC.

The reactor WL smoothes the welding current Iw. The inductance value of this reactor WL is, for example, 100 μH.

The feed motor WM receives the feed control signal Fc, which will be described later, as an input, and alternately repeats forward feed and reverse feed to feed the welding wire 1 at the feed speed Fw. As the feed motor WM, a motor having a high transient response is used. The feed motor WM may be installed near the tip of the welding torch 4 in order to accelerate the rate of change of the feed rate Fw of the welding wire 1 and the reversal of the feed direction. In addition, two feed motors WM may be used to form a push-pull feed system.

The welding wire 1 is fed in the welding torch 4 by the rotation of the feeding roll 5 coupled to the feeding motor WM, and an arc 3 is generated between the welding wire 1 and the base metal 2. A welding voltage Vw is applied between the feeding tip (not shown) in the welding torch 4 and the base metal 2, and the welding current Iw is energized. Shield gas is ejected from the tip of the welding torch 4 to shield the arc 3 from the atmosphere.

The output voltage setting circuit ER outputs a predetermined output voltage setting signal Er. The output voltage detection circuit ED detects and smoothes the output voltage E, and outputs an output voltage detection signal Ed.

The voltage error amplification circuit EV takes the above-mentioned output voltage setting signal Er and the above-mentioned output voltage detection signal Ed as inputs, and amplifies the error between the output voltage setting signal Er (+) and the output voltage detection signal Ed (-). , Outputs the voltage error amplification signal Ev.

The current detection circuit ID detects the welding current Iw and outputs the current detection signal Id. The voltage detection circuit VD detects the welding voltage Vw and outputs a voltage detection signal Vd. The short-circuit discrimination circuit SD takes the above voltage detection signal Vd as an input, and when this value is less than the predetermined short-circuit discrimination value (about 10V), it determines that it is in the short-circuit period and reaches the High level. A short-circuit determination signal Sd that determines that the circuit is in the arc period and reaches the Low level is output.

The welding wire viscosity setting circuit MR outputs a welding wire viscosity setting signal Mr, which becomes a high level when the operator selects “high” and becomes a low level when the operator selects “low”. The welding wire viscosity setting circuit MR is, for example, a changeover switch provided on the front panel of the welding power supply. JIS standard Z3312 defines the components of the welding wire. In this standard, YGW 11 is used for a large current of carbon dioxide arc welding, and YGW 12 is used for a small / medium current of carbon dioxide arc welding. The total mass% of silicon and manganese in the welding wire is larger in YGW 11 than in YGW 12. The viscosity of the welding wire increases as the total mass% of silicon and manganese in the welding wire increases. Therefore, when using the YGW 11, the operator switches the welding wire viscosity setting circuit MR to “high” and sets the welding wire viscosity setting signal Mr to the High level. On the other hand, when the YGW 12 is used, the operator switches the welding wire viscosity setting circuit MR to “low” and sets the welding wire viscosity setting signal Mr to the Low level.

The forward acceleration period setting circuit TUR receives the above-mentioned welding wire viscosity setting signal Mr as an input, and when the welding wire viscosity setting signal Mr is a High level (high viscosity), it becomes a predetermined short setting value and becomes a Low level (viscosity). Is low), the forward acceleration period setting signal Tsur, which is a predetermined length setting value, is output. Short setting value <long setting value. As a result, the lower the viscosity of the welding wire, the longer the normal feed acceleration period Tsu, and the slower the acceleration to the peak value of the normal feed.

The forward deceleration period setting circuit TSDR outputs a predetermined forward deceleration period setting signal Tsdr.

The reverse feed acceleration period setting circuit TRUR outputs a predetermined reverse feed acceleration period setting signal Trur.

The reverse feed / deceleration period setting circuit TRDR outputs a predetermined reverse feed / deceleration period setting signal Trdr.

The forward peak value setting circuit WSR receives the above-mentioned welding wire viscosity setting signal Mr as an input, and when the welding wire viscosity setting signal Mr is a High level (high viscosity), it becomes a predetermined high setting value and becomes a Low level (viscosity). Is low), the forward peak value setting signal Wsr, which is a predetermined low setting value, is output. High setting value> Low setting value. As a result, the lower the viscosity of the weld wire, the smaller the forward peak value Wsp.

The reverse feed peak value setting circuit WRR outputs a predetermined reverse feed peak value setting signal Wrr. The reverse peak value setting signal Wrr is a value corresponding to the value of the forward peak value setting signal Wsr.

The feed rate setting circuit FR includes the forward feed acceleration period setting signal Tsur, the forward feed deceleration period setting signal Tsdr, the reverse feed acceleration period setting signal Trur, the reverse feed deceleration period setting signal Trdr, and the above. The forward peak value setting signal Wsr, the reverse peak value setting signal Wrr, and the short-circuit discrimination signal Sd are input, and the feed rate pattern generated by the following processing is output as the feed rate setting signal Fr. When the feed rate setting signal Fr is 0, it is in a stopped state, when it is larger than 0, it is a normal feed period, and when it is smaller than 0, it is a reverse feed period.
1) Positive feed acceleration period setting signal During the normal feed acceleration period Tsur determined by Tsur, the feed rate setting signal Fr that accelerates from 0 to the positive value forward peak value Wsp determined by the positive feed peak value setting signal Wsr is output. ..
2) Subsequently, during the normal feed peak period Tsp, the feed rate setting signal Fr that maintains the above normal feed peak value Wsp is output.
3) When the short-circuit discrimination signal Sd changes from the Low level (arc period) to the High level (short-circuit period), it shifts to the forward deceleration period Tsd determined by the forward deceleration period setting signal Tsdr, and from the above normal feed peak value Wsp. The feed rate setting signal Fr that decelerates to 0 is output.
4) Subsequently, during the reverse feed acceleration period Tru determined by the reverse feed acceleration period setting signal Trur, the feed rate setting signal Fr accelerates from 0 to the negative value reverse feed peak value Wrp determined by the reverse feed peak value setting signal Wrr. Is output.
5) Subsequently, during the reverse feed peak period Trp, the feed rate setting signal Fr that maintains the reverse feed peak value Wrp is output.
6) When the short-circuit discrimination signal Sd changes from the High level (short-circuit period) to the Low level (arc period), it shifts to the reverse-forward deceleration period Trd determined by the reverse-forward deceleration period setting signal Trdr, and from the above-mentioned reverse-forward peak value Wrp. The feed rate setting signal Fr that decelerates to 0 is output.
7) By repeating the above 1) to 6), a feed rate setting signal Fr of a feed pattern that changes in a positive or negative trapezoidal wave shape is generated.

The feed rate detection circuit FD receives the encoder signal Es from the feed motor WM as an input and outputs the feed rate detection signal Fd.

The feed control circuit FC receives the feed rate setting signal Fr and the feed rate detection signal Fd as inputs so that the value of the feed rate detection signal Fd becomes equal to the value of the feed rate setting signal Fr. The feed control signal Fc that controls the feed rate Fw is output to the feed motor WM.

The current reduction resistor R is inserted between the reactor WL and the welding torch 4. The value of the current reducing resistor R is set to a value (about 0.5 to 3Ω) 50 times or more larger than the short-circuit load (about 0.01 to 0.03Ω). When the current-reducing resistor R is inserted into the current-carrying path of the welding current, the energy stored in the reactor component by the reactor WL and the welding cable is suddenly discharged.

The transistor TR is connected in parallel with the current-reducing resistor R described above, and is controlled to be turned on or off according to a drive signal Dr described later.

The constriction detection circuit ND receives the above-mentioned short-circuit discrimination signal Sd, the above-mentioned voltage detection signal Vd, and the above-mentioned current detection signal Id as inputs, and receives the above-mentioned short-circuit discrimination signal Sd as the voltage detection signal Vd when the short-circuit discrimination signal Sd is at the High level (short-circuit period). Constriction detection that determines that the constriction formation state has reached the reference state when the voltage rise value reaches the reference value and reaches the High level, and reaches the Low level when the short-circuit discrimination signal Sd changes to the Low level (arc period). The signal Nd is output. Further, the constriction detection signal Nd may be changed to the High level when the differential value of the voltage detection signal Vd during the short-circuit period reaches the corresponding reference value. Further, the value of the voltage detection signal Vd is divided by the value of the current detection signal Id to calculate the resistance value of the droplets, and when the differential value of this resistance value reaches the corresponding reference value, the constriction detection signal Nd is obtained. It may be changed to a high level.

The low level current setting circuit ILR outputs a predetermined low level current setting signal Ilr. The current comparison circuit CM takes the low level current setting signal Ilr and the above current detection signal Id as inputs, and sets the current comparison signal Cm to the High level when Id <Ilr and the Low level when Id ≥ Ilr. Output.

The drive circuit DR receives the above-mentioned current comparison signal Cm and the above-mentioned constriction detection signal Nd as inputs, and when the constriction detection signal Nd changes to the High level, it changes to the Low level, and then when the current comparison signal Cm changes to the High level. The drive signal Dr that changes to the High level is output to the base terminal of the above-mentioned transistor TR. Therefore, when the constriction is detected, the drive signal Dr goes to the Low level, the transistor TR is turned off, and the current reducing resistor R is inserted into the current-carrying path of the welding current, so that the welding current Iw drops sharply. Then, when the value of the suddenly reduced welding current Iw decreases to the value of the low level current setting signal Ilr, the drive signal Dr becomes the High level and the transistor TR is turned on, so that the current reduction resistor R is short-circuited and normally. Return to the state of.

The current control setting circuit ICR receives the short-circuit discrimination signal Sd, the low-level current setting signal Ilr, and the constriction detection signal Nd as inputs, performs the following processing, and outputs the current control setting signal Icr.
1) When the short-circuit discrimination signal Sd is at the Low level (arc period), the current control setting signal Icr which becomes the low level current setting signal Ilr is output.
2) When the short-circuit discrimination signal Sd changes to the High level (short-circuit period), the initial current set value is set in advance during the predetermined initial period, and then the peak set value at short-circuit is set in advance with the predetermined short-circuit slope. The current control setting signal Icr that rises to and maintains that value is output.
3) After that, when the constriction detection signal Nd changes to the High level, the current control setting signal Icr, which is the value of the low level current setting signal Ilr, is output.

The current error amplifier circuit EI uses the above-mentioned current control setting signal Icr and the above-mentioned current detection signal Id as inputs, and amplifies the error between the current control setting signal Icr (+) and the current detection signal Id (-) to amplify the current. The error amplification signal Ei is output.

The current drop time setting circuit TDR outputs a predetermined current drop time setting signal Tdr. The current drop time setting signal Tdr is set as a value corresponding to the average feeding speed (average welding current value).

The small current period circuit STD receives the above-mentioned short-circuit discrimination signal Sd and the above-mentioned current drop time setting signal Tdr as inputs, and is determined by the current drop time setting signal Tdr from the time when the short-circuit discrimination signal Sd changes to the Low level (arc period). When the time elapses, the high level is reached, and then when the short circuit determination signal Sd reaches the high level (short circuit period), the low level signal Std is output.

The power supply characteristic switching circuit SW receives the above-mentioned current error amplification signal Ei, the above-mentioned voltage error amplification signal Ev, the above-mentioned short-circuit discrimination signal Sd, the above-mentioned reverse feed / deceleration period setting signal Trdr, and the above-mentioned small current period signal Std as inputs. , The following processing is performed, and the error amplification signal Ea is output.
1) From the time when the short-circuit discrimination signal Sd changes to the High level (short-circuit period), the short-circuit discrimination signal Sd changes to the Low level (arc period) and the reverse feed deceleration period determined by the reverse feed deceleration period setting signal Trdr has elapsed. During the period up to the time point, the current error amplification signal Ei is output as the error amplification signal Ea.
2) During the subsequent large current arc period, the voltage error amplification signal Ev is output as the error amplification signal Ea.
3) During the small current arc period in which the small current period signal Std becomes the High level during the subsequent arc period, the current error amplification signal Ei is output as the error amplification signal Ea.
With this circuit, the characteristics of the welding power supply become constant current characteristics during the short circuit period, reverse feed deceleration period, and small current arc period, and constant voltage characteristics during other large current arc periods.

FIG. 2 is a timing chart of each signal in the welding power supply of FIG. 1 showing an arc welding control method according to the first embodiment of the present invention. FIG. (A) shows the time change of the feed rate Fw, FIG. (B) shows the time change of the welding current Iw, and FIG. 3C shows the time change of the welding voltage Vw. ) Indicates the time change of the short-circuit discrimination signal Sd, and FIG. 3 (E) shows the time change of the small current period signal Std. Hereinafter, the operation of each signal will be described with reference to the figure.

The feed rate Fw shown in FIG. 1A is controlled by the value of the feed rate setting signal Fr output from the feed rate setting circuit FR of FIG. The feed rate Fw is determined by the normal feed acceleration period Tsu determined by the normal feed acceleration period setting signal Tsur in FIG. 1, the normal feed peak period Tsp that continues until a short circuit occurs, and the positive feed deceleration period setting signal Tsdr in FIG. Forward / deceleration period Tsd, reverse feed acceleration period Tru determined by the reverse feed acceleration period setting signal Trur in FIG. 1, reverse feed peak period Trp that continues until an arc is generated, and reverse feed determined by the reverse feed deceleration period setting signal Trdr in FIG. It is formed from the deceleration period Trd. Further, the forward peak value Wsp is determined by the forward peak value setting signal Wsr in FIG. 1, and the reverse peak value Wrp is determined by the reverse peak value setting signal Wrr in FIG. As a result, the feed rate setting signal Fr becomes a feed pattern that changes in a substantially trapezoidal wave shape of positive and negative.

[Operation during short-circuit period at times t1 to t4]
When a short circuit occurs at time t1 during the normal feed peak period Tsp, the welding voltage Vw drops sharply to a short circuit voltage value of several V as shown in FIG. The short-circuit discrimination signal Sd changes to the High level (short-circuit period). In response to this, the feed rate shifts to the predetermined normal feed deceleration period Tsd at times t1 to t2, and as shown in FIG. .. For example, the forward deceleration period Tsd = 1 ms is set.

As shown in FIG. 3A, the feed rate Fw enters the predetermined reverse feed acceleration period Tru at time t2 to t3, and accelerates from 0 to the above-mentioned reverse feed peak value Wrp. The short-circuit period continues during this period. For example, the reverse feed acceleration period Tru = 1 ms is set.

When the reverse feed acceleration period Tru ends at time t3, the feed rate Fw enters the reverse feed peak period Trp and becomes the above-mentioned reverse feed peak value Wrp, as shown in FIG. The reverse peak period Trp continues until an arc is generated at time t4. Therefore, the period at times t1 to t4 is the short-circuit period. The reverse peak period Trp is not a predetermined value, but it is about 4 ms.

As shown in FIG. 3B, the welding current Iw during the short-circuit period at times t1 to t4 becomes a predetermined initial current value during the predetermined initial period. After that, the welding current Iw rises at a predetermined short-circuit inclination, and maintains that value when the predetermined short-circuit peak value is reached.

As shown in FIG. 6C, the welding voltage Vw rises from the point where the welding current Iw reaches the peak value at the time of short circuit. This is because the back feed of the welding wire 1 and the action of the pinch force due to the welding current Iw gradually form a constriction in the droplets at the tip of the welding wire 1.

After that, when the voltage rise value of the welding voltage Vw reaches the reference value, it is determined that the constriction formation state has reached the reference state, and the constriction detection signal Nd in FIG. 1 changes to the High level.

In response to the constriction detection signal Nd reaching the High level, the drive signal Dr in FIG. 1 becomes the Low level, so that the transistor TR in FIG. 1 is in the off state and the current reducing resistor R in FIG. 1 is in the welding current. It is inserted into the energizing path. At the same time, the current control setting signal Icr of FIG. 1 becomes smaller than the value of the low level current setting signal Ilr. Therefore, as shown in FIG. 6B, the welding current Iw sharply decreases from the peak value at the time of short circuit to the low level current value. Then, when the welding current Iw decreases to a low level current value, the drive signal Dr returns to the high level, so that the transistor TR is turned on and the current reducing resistor R is short-circuited. As shown in FIG. 3B, since the current control setting signal Icr remains the low level current setting signal Ilr in the welding current Iw, from the recurrence of the arc until the predetermined reverse feed deceleration period Trd elapses. Maintain a low level current value. Therefore, the transistor TR is turned off only during the period from the time when the constriction detection signal Nd changes to the High level until the welding current Iw decreases to the low level current value. As shown in FIG. 3C, the welding voltage Vw decreases once and then rises sharply because the welding current Iw becomes small. Each of the above-mentioned parameters is set to the following values, for example. Initial current = 40A, initial period = 0.5ms, short-circuit slope = 180A / ms, short-circuit peak value = 400A, low-level current value = 50A.

[Operation during arc period from time t4 to t7]
At time t4, when the constriction progresses due to the pinch force due to the reverse feed of the welding wire and the energization of the welding current Iw and an arc is generated, the welding voltage Vw is an arc voltage value of several tens of V as shown in FIG. As shown in FIG. 3D, the short-circuit discrimination signal Sd changes to the Low level (arc period). In response to this, the process shifts to the predetermined reverse feed deceleration period Trd at times t4 to t5, and as shown in FIG. (A), the feed rate Fw decelerates from the above reverse feed peak value Wrp to 0. .. For example, the reverse feed deceleration period Trd = 1 ms is set.

When the reverse feed deceleration period Trd ends at time t5, the process shifts to the predetermined forward feed acceleration period Tsu at times t5 to t6. During this normal feed acceleration period Tsu, as shown in FIG. 6A, the feed rate Fw accelerates from 0 to the above normal feed peak value Wsp. The arc period continues during this period.

When the normal feed acceleration period Tsu ends at time t6, the feed rate Fw enters the normal feed peak period Tsp and reaches the above normal feed peak value Wsp, as shown in FIG. The arc period continues during this period. The forward peak period Tsp continues until a short circuit occurs at time t7. Therefore, the period from time t4 to t7 is the arc period. Then, when a short circuit occurs, the operation returns to the operation at time t1. The forward peak period Tsp is not a predetermined value, but it is about 4 ms.

When an arc is generated at time t4, the welding voltage Vw rapidly increases to an arc voltage value of several tens of V, as shown in FIG. On the other hand, as shown in FIG. 3B, the welding current Iw continues to have a low level current value during the reverse feed deceleration period Trd at times t4 to t5. After that, from time t5, the welding current Iw rapidly increases to a peak value, and then gradually decreases to a large current value. Therefore, the timing at which the welding current Iw increases after the arc is generated at time t4 (time t5) is the end time of the reverse feed deceleration period Trd at which the feed rate becomes 0 when switching from reverse feed to forward feed. It becomes.

During the large current arc period at time t5 to t61, the feedback control of the welding power source is performed by the voltage error amplification signal Ev of FIG. 1, so that the constant voltage characteristic is obtained. Therefore, the value of the welding current Iw during the high current arc period changes depending on the arc load.

At time t61, when the current drop time determined by the current drop time setting signal Tdr in FIG. 1 elapses after the arc is generated at time t4, the small current period signal Std changes to the High level as shown in FIG. To do. In response to this, the welding power supply is switched from the constant voltage characteristic to the constant current characteristic. Therefore, as shown in FIG. 6B, the welding current Iw drops to a low level current value and maintains that value until the time t7 when the short circuit occurs. Similarly, as shown in FIG. 6C, the welding voltage Vw also decreases. The small current period signal Std returns to the Low level when a short circuit occurs at time t7.

According to the first embodiment described above, when the feed rate at which the welding current is increased from the low level current value after the start of the arc period is switched from the reverse feed to the normal feed becomes 0. And. That is, the timing of increasing the welding current is set to the end point of the reverse feed deceleration period. When forward / reverse feed arc welding is performed using a welding wire having a low viscosity among the welding wires for steel, the following welding state is obtained depending on the timing of increasing the welding current after the arc is generated.
(1) When the increase timing of the welding current is in the middle of the reverse feed deceleration period In this case, the welding current increases when the welding wire is still reverse feed. When the welding current increases, the tip of the welding wire is melted to form droplets. In a welding wire having a low viscosity, a part of the droplets is scattered as spatter when the droplets are formed while being fed back. In the case of a highly viscous welding wire, spatter does not occur even if droplets are formed when the wire is fed back.
(2) When the welding current increase timing is at the end of the reverse feed deceleration period (Embodiment 1)
In this case, the welding current increases when the feeding speed of the welding wire is 0. When the welding current increases, the tip of the welding wire is melted to form droplets. Therefore, droplets are gradually formed in a state where the feeding speed is gradually accelerated from 0, and the amount of spatter generated is reduced regardless of the viscosity of the welding wire.
(3) When the welding current increase timing is in the middle of the normal feed acceleration period In this case, the welding current increases when the welding wire is forward feed. Therefore, since the normal feed is performed in a state where droplets have not been formed yet, the probability that a short circuit will occur again increases regardless of the viscosity of the welding wire. When a re-short circuit occurs, the welded state becomes unstable.

Further, according to the first embodiment described above, the lower the viscosity of the welding wire, the smaller the normal feed peak value. If the normal feed peak value is too large when the viscosity of the welding wire is low, droplets are scattered and the amount of spatter generated increases. When the viscosity of the welding wire is high, the period between the short-circuit period and the arc period can be shortened by increasing the normal feed peak value, and the droplet transition state can be improved. Therefore, when the viscosity of the welding wire is low, it is desirable to make the normal feed peak value smaller than when the viscosity is high in order to reduce the amount of spatter generated. For example, when the welding wire has a low viscosity (YGW12), the forward feed peak value is set to 50 m / min and the reverse feed peak value is set to -30 m / min, and when the welding wire has a high viscosity (YGW11), the forward feed is set to normal feed. The peak value is set to 70 m / min and the reverse peak value is set to -40 m / min.

Further, according to the first embodiment described above, the lower the viscosity of the welding wire, the slower the acceleration to the normal feed peak value. If the acceleration to the normal feed peak value becomes steep when the viscosity of the welding wire is low, droplets are scattered and the amount of spatter generated increases. When the viscosity of the welding wire is high, the cycle between the short-circuit period and the arc period can be shortened by steeply accelerating to the normal feed peak value, and the droplet transition state can be improved. .. Therefore, when the viscosity of the welding wire is low, it is desirable to accelerate to the normal feed peak value more slowly than when the viscosity is high in order to reduce the amount of spatter generated. For example, in the case of a welding wire having a low viscosity (YGW12), the normal feed acceleration period is set to 1.5 ms, and in the case of a welding wire having a high viscosity (YGW11), the normal feed acceleration period is set to 1 ms.

Further, according to the first embodiment, the high or low viscosity of the welding wire is determined by the total mass% of silicon and manganese in the welding wire. The larger the total mass% of silicon and manganese in the welding wire, the higher the viscosity of the welding wire. In this way, the operator can easily determine whether the viscosity of the welding wire is high or low.

1 Welding wire
2 Base material
3 arc
4 Welding torch
5 Feeding roll CM Current comparison circuit Cm Current comparison signal DR Drive circuit Dr Drive signal E Output voltage Ea Error amplification signal ED Output voltage detection circuit Ed Output voltage detection signal EI Current error amplification circuit Ei Current error amplification signal ER Output voltage setting circuit Er Output voltage setting signal Es (from feed motor) Encoder signal EV Voltage error amplification circuit Ev Voltage error amplification signal FC Feed control circuit Fc Feed control signal FD Feed speed detection circuit Fd Feed speed detection signal FR Feed Speed setting circuit Fr Feeding speed setting signal Fw Feeding speed ICR Current control setting circuit Icr Current control setting signal ID Current detection circuit Id Current detection signal ILR Low level current setting circuit Ilr Low level current setting signal Iw Welding current MR Welding wire viscosity Setting circuit Mr Welding wire viscosity Setting signal ND Constriction detection circuit Nd Constriction detection signal PM Power supply Main circuit R Flow-reducing resistor SD Short circuit discrimination circuit Sd Short circuit discrimination signal STD Small current period circuit Std Small current period signal SW Power supply characteristic switching circuit TDR Current Descent time setting circuit Tdr Current drop time setting signal TR Transistor Trd Reverse feed deceleration period TRDR Reverse feed deceleration period setting circuit Trdr Reverse feed deceleration period setting signal Trp Reverse feed peak period Tru Reverse feed acceleration period TRUR Reverse feed acceleration period setting circuit Trur Reverse Feed acceleration period setting signal Tsd Normal feed deceleration period TSDR Positive feed deceleration period setting circuit Tsdr Positive feed deceleration period setting signal Tsp Positive feed peak period Tsu Positive feed acceleration period TUR Positive feed acceleration period setting circuit Tsur Forward feed acceleration period setting signal VD Detection circuit Vd Voltage detection signal Vw Welding voltage WL Reactor WM Feed motor Wrp Reverse feed peak value WRR Reverse feed peak value setting circuit Wrr Reverse feed peak value setting signal Wsp Forward feed peak value WSR Forward feed peak value setting circuit Wsr Forward feed peak Value setting signal

Claims (3)

In the arc welding control method in which the feed rate of the welding wire is switched alternately between forward feed and reverse feed, and the short circuit period and the arc period are repeatedly welded.
The lower the viscosity of the welding wire, the smaller the peak value of the positive feed.
An arc welding control method characterized by this. The lower the viscosity, the slower the acceleration of the positive feed to the peak value.
The arc welding control method according to claim 1. The high or low viscosity is determined by the total mass% of silicon and manganese in the welding wire.
The arc welding control method according to claim 1 or 2.

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