JP3250325B2 - Consumable electrode type arc welding control method and power supply device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a consumable electrode type arc welding method using a CO2 gas, a MAG gas, etc., by controlling the external characteristics of a welding power supply at a high speed during welding. The present invention relates to a consumable electrode type arc welding control method and a power supply device for improving the stability of a welding state.

[0002]

2. Description of the Related Art Attempts to improve the stability of welding conditions by switching the external characteristics of a welding power supply device according to the welding load condition during welding and controlling the repetition of arcing and short-circuiting have been conventionally proposed. Have been.

As an example, FIG. 1 shows external characteristics (hereinafter, referred to as external characteristics) of a welding power supply device in a welding method (hereinafter, referred to as short-circuit transfer welding) in which droplet generation is performed by repeating arc generation and short-circuit generation. , Welding load characteristics between the workpiece and the consumable electrode wire (hereinafter, wire)
And a transient trajectory of an operating point determined by the external characteristic and the load characteristic. In the figure, solid lines of a straight line and a broken line represent external characteristics, and the welding current value Ia
[A] shows the relationship between the welding power supply output voltage value e [V],
The straight dotted line indicates the load characteristics, and the welding current value Ia [A]
And the relationship between the welding load voltage value Va [V] and the solid line of the arrow is the locus of the operating point, indicating the relationship between the welding current value Ia [A] and the welding load voltage value Va [V].

FIGS. 2A and 2B respectively show a welding load voltage value Va [V] during short-circuit transfer welding according to the prior art.
FIG. 4C is a diagram showing waveforms of the welding current value Ia [A] with respect to the passage of time t. FIG. 4C shows a molten pool 1b grown on the wire tip 1a corresponding to the welding current value Ia [A]. It is a transition state diagram explaining the state which shifts to 2a. FIG.
2 (A) to 2 (C) show the wire feeding speed of 3.5.
[M / min], wire type YGW12 (JIS Z
3312), an average welding current value of 150 using a wire diameter of 1.2 [mm] and a shielding gas type of CO2.
[A], a case where welding was performed at an average welding load voltage value of 19 [V]. Hereinafter, the operation of the related art will be described with reference to FIGS. 1 and 2A to 2C.

[0005] (1) Periods t0 to t2 in FIGS.
Description of the operation at t1. Droplet 1b and molten pool 2 at wire tip 1a
It is detected at time t0 that a has been short-circuited with a, and the external characteristic is switched to the external characteristic 1 (the characteristic of a straight line composed of symbols F and G) in FIG. At this time, because of the short-circuit state, the load characteristic is represented by the resistance characteristic II 'shown by the dotted line in FIG.
And the welding current value Ia [A] and the welding load voltage value Va
The operating point of [V] is an intersection A between the external characteristic 1 and the load characteristic Ey '. In this period, as shown in FIG. 2 (C), the droplet 1b comes into contact with the molten pool 2a at time t0. As shown in FIG. 2B, the welding current value Ia [A] in the period t0 to t1 is set to be more complete and the welding current value Ia [A] is changed in the period t1 to t2 to be described later. It is maintained at a value lower than the welding current value. Note that the set short-circuit time (set time of the external characteristic 1) TS1 in the period t0 to t1 is set to about several ms in advance.

(2) Periods t1 to t3 in FIGS. 2A to 2C
Description of the operation at t2. At time t1 when the short-circuit duration time TS has exceeded the set short-circuit time TS1 shown in FIG. 2A, the external characteristic is switched from the external characteristic 1 in FIG. 1 to the external characteristic 2 (the characteristic of a straight line composed of symbols F and H). . At this time, since the load characteristics are continuously the resistance characteristics II ', the operating points of the welding current value Ia [A] and the welding load voltage value Va [V] are determined by the external characteristic 2 and the load characteristic II'. It becomes intersection B.
During this period, the operating point is shifted to the intersection B to increase the welding current value Ia [A] and increase the pinch force. By increasing the pinch force, FIG.
As shown in (1), the state where the wire tip 1a and the droplet 1b can be separated is promoted, and the droplet 1b is transferred to the molten pool 2a.

(3) Description of the operation in the periods t2 to t3 in FIGS. 2A to 2C. The external characteristic is shown in FIG. 1 at time t2 when it is detected that the arc 3 has regenerated between the wire 1 and the workpiece 2 .
The small current region has a drooping characteristic and the middle current region has a rising characteristic.
And the large current range depends on the welding current range, which is a constant current characteristic.
The external characteristic 3 of the composite characteristic in which the external characteristic changes (reference symbol J,
(Characteristic of a polygonal line composed of K, L and M). At this time, the load characteristic becomes the arc characteristic "ha", the operating point gradually moves from the operating point "C" immediately after the arc reoccurs, and reaches the intersection D between the external characteristic 3 and the arc characteristic "ha". During this period, a large welding current I
When a [A] is energized, as shown in FIG. 2 (C), melting of the wire tip 1a is promoted to grow a droplet 1b. Thereafter, as the operating point moves, the welding current value Ia [A] gradually decreases, and the arc force decreases.
The pushing force acting on the droplet 1b is reduced. Due to this, the droplet 1b hangs down due to gravity as shown in FIG. 2 (C) and comes into contact with the molten pool 2a.

As described above, the droplet 1b at the wire tip 1a
The external characteristics are optimized in accordance with the transition state of (1), and by repeating the above operations (1) to (3), droplet transfer is performed regularly, and the stability of the welding state is improved.

[0020]

In the prior art,
Even if the wire feeding speed, the type of the wire, and the type of the shielding gas are changed, the external characteristics 1 to 3 shown in FIG. 1 remain unchanged without change. In the combination of the external characteristics 1 to 3 shown in FIG. 1, the wire feeding speed is 3.5 [m
/ Min], wire type YGW12, wire diameter 1.2
When short-circuit transfer welding is performed under appropriate welding conditions using [mm] and the type of shielding gas CO2, a stable welding state as shown in FIGS. 2A to 2C is obtained.

FIGS. 3A and 3B use the external characteristics 1 to 3 of FIG. 1 to increase only the wire feed speed to 7.0 [m / m].
min], and the welding load voltage value Va [V] and the welding load voltage value Va when the other conditions, ie, the wire type YGW12, the wire diameter 1.2 [mm], and the shield gas type CO2 are welded under the same welding conditions. Welding current value Ia [A]
FIG. 7 is a diagram showing a waveform with respect to the passage of time t. FIG. 4C shows the droplet 1 grown on the wire tip 1a at that time.
FIG. 6 is a transition state diagram for explaining a state in which b moves to a molten pool 2 a on the workpiece 2.

In the figure, the welding current value I during the period t2 to t4 is shown.
a is determined by the external characteristic 3 in FIG. However, if the wire feeding speed is set to a high speed such as 7.0 [m / min], the welding current value Ia in the range determined by the external characteristic 3 in FIG.
A short circuit occurs before b is not sufficiently formed. Further, the welding current value Ia in the short-circuit state during the period t4 to t5 is also determined by the external characteristic 2 in FIG. The unwound wire tip 1a cannot be smoothly separated from the molten pool 2a by a pinch force. Therefore, the short-circuit state continues for a long period, and the wire tip 1a
Is heated by Joule heat, the wire is blown, and a transition from a short circuit state to an arc occurs. Since the arc length becomes very long due to the fusing of the wire, the arc cannot be maintained and the arc breaks. Then, the wire tip 1a comes into contact with the molten pool 2a again, and an arc is generated. As described above, since the arc interruption and the re-generation of the arc are repeated, a regular short-circuit transition state cannot be obtained.

[0030]

Means for Solving the Problems The first aspect of the present invention is shown in FIG.
As shown in the claim corresponding diagram of 3, Oite consumable electrode arc welding control method,

A welding current detecting step of detecting a welding current value Ia and outputting a welding current detection signal Ic (for example, FIG. 1)
1 SP5),

A short-circuit arc discriminating step of detecting a welding load voltage value Va and outputting a welding voltage detection signal Vc to discriminate between a short-circuit state and an arc generation state (for example, SP in FIG. 12)
9) and

When the short-circuit state and the short-circuit duration time TS are shorter than the set short-circuit time (set time of the external characteristic 1) TS1, the welding current detection signal Ic is input and the output for forming the first external characteristic is obtained. A signal corresponding to the voltage setting signal Vs (digital output voltage setting signal Vd) is output from the external characteristic data storage circuit ROM, and a first external characteristic output step for supplying a low current welding current (for example, FIG. 12)
SP10 to SP12), and

When the short-circuit state is shorter than the set short-circuit time (TS1), the welding current detection signal Ic is input and corresponds to the output voltage setting signal Vs forming the second external characteristic. A signal (digital output voltage setting signal Vd) is output from the external characteristic data storage circuit ROM, and a second external characteristic output step (for example, SP10, SP11 and S11 in FIG. 12) for applying a large welding current.
P16),

When an arc is being generated, the welding current detection signal Ic is input, and external characteristics are determined according to the welding current range.
A signal (digital output voltage setting signal Vd) corresponding to the output voltage setting signal Vs forming the third external characteristic of the composite characteristic in which the output voltage changes is output from the external characteristic data storage circuit ROM, and the third current for supplying the arc current is output. an output step of externally characteristics (e.g., SP15 and SP17 in Fig. 12), before
The first to third external characteristics are set as one set of characteristic groups.
The feed speed setting signal Wa, the wire type selection signal Wc, and the
At least one of the cold gas type selection signals Wd.
In response, multiple sets of the characteristic groups are stored in the external characteristic data.
The feed speed setting signal Wa and the
Ear type selection signal Wc and shield gas type selection signal
A particular set of signals by at least one signal of the signal Wd
Characteristic group selection step to select the characteristic group
(For example, SP1 to SP4 in FIG. 11) .

In the consumable electrode type arc welding control method described in the flowcharts shown in FIGS . 11 and 12, FIG.
Speed setting signal W output by the feeding speed setting circuit WA
a is converted into a digital feed speed setting signal Wb by the feed speed digital signal conversion circuit ADW, read into the central processing circuit CPU, and stored in the temporary storage circuit RAM;

A wire type storage step 2 (SP2) for reading the wire type selection signal Wc output from the wire type selection circuit WC of FIG. 8 into the central processing circuit CPU and storing it in the temporary storage circuit RAM;

A shield gas type storage step 3 (SP3) in which the shield gas type selection signal Wd output from the shield gas type selection circuit WD in FIG. 8 is read into the central processing circuit CPU and stored in the temporary storage circuit RAM.

After at least one of the steps 1 to 3 is performed and the data is stored, the digital feed rate setting signal Wb, the wire type selection signal Wc, and the shield gas type selection signal Wd are used for at least one signal. A characteristic group selection step 4 in which setting conditions shown in Table 1 described below are branched and a specific group is selected from the A1 to D3 groups of external characteristics.
(SP4),

A welding current detection step 5 (SP5) for detecting the welding current value Ia by the welding current detection circuit CD of FIG. 8 and outputting a welding current detection signal Ic;

Initial setting step 6 (SP6) for resetting the short-circuit continuation time count value Ns to 0 and setting the interrupt timer time limit Tc;

After the initial setting step 6, it is determined whether or not there is a timer interrupt. If there is an interrupt, the process proceeds to step 8 (SP8), which will be described later. If there is no interrupt, the interrupt is determined until the next timer interrupt occurs. Step 7
(SP7),

After the timer interruption, the welding current detection signal I detected by the welding current detection circuit CD in FIG.
c is converted to a digital welding current detection signal Ib and stored in the temporary storage circuit RAM.
8)

After storing the welding current detection signal, the short circuit determination signal Vt is read into the central processing circuit CPU from the short circuit determination circuit VT which receives the welding voltage detection signal Vc in FIG.
A short-circuit state or an arc occurrence state is determined. If the short-circuit state occurs, the process proceeds to step 10 (SP10). If the arc state occurs, the process proceeds to step 15 (SP15) described below.

If the short-circuit state is detected in the short-circuit arc discriminating step 9, the short-circuit continuation time count value Ns is counted up to Ns + 1.
0),

The short circuit continuation time count value Ns and the short circuit time count set value (external characteristic 1)
(The set value of the continuation time count) Ns1 and Ns <
If Ns1, the process proceeds to step 12 (SP12) described later, and if Ns ≧ Ns1, the process proceeds to step 16 (S12) described later.
P16) Short circuit time comparison step 11 (SP11)
When,

In the short-circuit time comparison step 11, Ns <Ns1
, A digital output voltage setting signal Vd corresponding to the digital welding current detection signal Ib of the external characteristic 1 for applying a welding current of a low current value is read from the external characteristic data storage circuit ROM. (SP
12)

The digital output voltage setting signal Vd read from the external characteristic data storage circuit ROM of FIG.
The conversion circuit DA converts the signal into an analog output voltage setting signal Vs, outputs the signal to the power control circuit 10 through the comparison circuit CM, and proceeds to step 14 described later.
(SP13),

In the short-circuit time comparison step 11, Ns ≧ Ns1
In the case of, from the external characteristic data storage circuit ROM of FIG.
The digital output voltage setting signal Vd corresponding to the digital welding current detection signal Ib of the external characteristic 2 for supplying a welding current having a large current value is read, and the power control step 13 described above is performed.
To the second external characteristic output step 16 (SP16)
When,

When an arc is generated in the short-circuit arc determination step 9, a short-circuit reset step 15 (SP15) for resetting the short-circuit continuation time count value Ns to 0;

After the short-circuit reset step 15, the digital output voltage setting signal Vd corresponding to the digital welding current detection signal Ib of the external characteristic 3 for supplying the welding current when an arc is generated is read from the external characteristic data storage circuit ROM of FIG. A third external characteristic output step 17 (SP17) for reading and proceeding to the power control step 13;

After the execution of the power control step 13, it is determined whether or not there is a welding end command. If there is no command, the process returns to the interrupt determination step 7 (SP7). If there is a command, welding ends. (SP14).

According to a second aspect of the present invention, as shown in the block diagram of FIG. 8, in a consumable electrode type arc welding power supply, the characteristics of a commercial power supply PS are converted into output characteristics suitable for a welding method applicable to the present invention. The power control circuit 10 detects an output voltage on the output side of the power control circuit 10 and outputs an output voltage detection signal V
b, an output voltage detection circuit VB for outputting the welding current value Ia
A welding current detection circuit CD that detects the current and outputs a welding current detection signal Ic;

A feed speed setting circuit WA for outputting a feed speed setting signal Wa, and a feed motor control circuit WB for controlling the wire feed motor with the feed speed setting signal Wa as an input.
A wire feed motor WM for feeding a wire, a welding voltage detection circuit VC for detecting a welding load voltage value Va and outputting a welding voltage detection signal Vc, and a welding voltage detection signal Vc.
A short-circuit determination circuit VT that determines the occurrence of a short-circuit between the wire and the workpiece, and outputs a short-circuit determination signal Vt.
A feed speed digital signal conversion circuit ADW that receives the feed speed setting signal Wa as an input and outputs a digital feed speed setting signal Wb, and a wire type selection circuit WC that outputs a wire type selection signal Wc corresponding to the type of wire; A shield gas type selection circuit WD that outputs a shield gas type selection signal Wd corresponding to the type of the shield gas;

The total welding current value Ia in the welding current adjustment range output by the power control circuit 10 is sequentially divided into a group of signals corresponding to a large number of welding current values Ia and corresponds to a welding current range storage signal Id. signal and outer consisting signals (e.g. digital output voltage setting signal Vd) corresponding to the output voltage setting signal Vs corresponding to the signal corresponding to the signal Id
This is the part characteristic data.
When the current is less than the constant short-circuit time, apply a low current welding current
The first external characteristic data and the short-circuit condition
When the time is longer than the set short-circuit time, a large current
The second external characteristic data to be energized and the state of arc generation
The welding current range for applying the arc current
External characteristic data of a composite characteristic in which external characteristics change
As a set of characteristic groups, the feed speed setting signal Wa,
Ear type selection signal Wc and shield gas type selection signal W
a plurality of sets of said characteristics corresponding to at least one signal of d.
An external characteristic data storage circuit ROM for storing groups ;

A signal corresponding to the welding current detection signal Ic (for example, a digital welding current detection signal Ib) and a short circuit determination signal Vt are input to the external characteristic data storage circuit R.
First, from among a plurality of sets of external characteristic data stored in the OM, a characteristic group of a specific external characteristic is selected by a digital feed speed setting signal Wb, a wire type selection signal Wc, and a shield gas type selection signal Wd. Is determined from the selected characteristic group, and a signal group corresponding to the output voltage setting signal Vs corresponding to the welding current range storage signal Id specified by the welding current detection signal Ib is stored in the external characteristic data. A central processing circuit CPU that reads and outputs from a circuit ROM;

The output voltage detection signal Vb is compared with the output voltage setting signal Vs, and the power control signal Cm is supplied to the power control circuit 1.
This is a consumable electrode type arc welding power supply device comprising a comparison circuit CM that outputs 0.

[0070]

According to the present invention, the optimum external characteristic group is automatically selected according to the wire feeding speed, the wire type, and the type of the shielding gas as shown in Table 1.

Table 1 is a conditional branch table for explaining a method for selecting one specific group from the characteristic groups A1 to D3 of the external characteristic in the present invention.

When the wire feeding speed is 3.5 [m / min],
Wire type is YGW12, wire diameter is 1.2 [mm]
When the type of the shielding gas is CO2 gas, the A1 group of the characteristic group is selected as shown in Table 1, which is a combination of the external characteristics 1 to 3 shown in FIG. When the wire feeding speed is 7 [m / min], the wire type is YGW12, the wire diameter is 1.2 [mm], and the shield gas type is CO2 gas, the A3 group of the characteristic group shown in Table 1 is used. The selected combination is a combination of the external characteristics 1 to 3 shown in FIG.

The description of the operation when the external characteristic shown in FIG. 1 is selected is omitted because it has been described in the section of the prior art. FIG.
(A) and (B) respectively show the welding load voltage value Va [V] and the welding current value I when the external characteristic of FIG. 4 is selected.
FIG. 7 is a diagram showing a waveform of a [A] with respect to the elapse of time t;
FIG. 3C shows the corresponding droplet 1 at the wire tip 1a.
FIG. 5B is a transition state diagram illustrating a state where b transitions, and the operation will be described below with reference to FIGS. 4 and 5A to 5C.

(1) Period t0 to t0 in FIGS. 5A to 5C
Description of the operation at t1. Droplet 1b and molten pool 2 at wire tip 1a
It is detected at time t0 that a has been short-circuited with a, and the external characteristic is switched to the external characteristic 1 (the characteristic of a straight line composed of symbols F and G) in FIG. External characteristic 1 of FIG. 4 and FIG.
Is the same as the external characteristic 1. At this time, because of the short-circuit state, the load characteristic is represented by the resistance characteristic curve shown by the dotted line in FIG.
The operating points of the welding current value Ia [A] and the welding load voltage value Va [V] are determined by the external characteristic 1 and the load characteristic
Intersection A with

In this period, as shown in FIG.
At time t0, the droplet 1b comes into contact with the molten pool 2a. In order to make this contact state more complete and to smoothly transfer the droplet 1b, as shown in FIG.
During the period from 0 to t1, the welding current value Ia [A] is kept lower than the welding current value during the period from t1 to t2 described later. Note that the set short-circuit time (set time of the external characteristic 1) TS1 in the period t0 to t1 is set to about several ms in advance.

(2) Periods t 1 to t 5 in FIGS.
Description of the operation at t2. At time t1 when the short-circuit duration time TS has exceeded the set short-circuit time TS1 shown in FIG. 5A, the external characteristic is switched from the external characteristic 1 in FIG. . At this time, since the load characteristics are continuously the resistance characteristics II ', the operating points of the welding current value Ia [A] and the welding load voltage value Va [V] are determined by the external characteristic 2 and the load characteristic II'. It becomes intersection B.

The external characteristic 2 shown in FIG. 4 is different from the external characteristic 2 shown in FIG. 1. The welding current value Ia at the intersection B is larger than the current value shown in FIG. . For this reason, even if the wire feeding speed is set higher than that in FIG. 1, the short-circuit current value in the case of the external characteristic 2 shown in FIG. 5B is larger than that in FIG. Therefore, the pinch force is greater than that, and the droplet 1b is smoothly separated from the wire tip 1a and moves to the molten pool 2a.

(3) Periods t2 to t5 in FIGS.
Explanation of the operation at t3. At time t2, it is detected that the arc 3 has reoccurred between the wire 1 and the workpiece 2, and at time t2, the external characteristic is changed to the external characteristic 3 (characteristic of a broken line composed of J, K, L and M) in FIG. Switch to. At this time, the load characteristic becomes the arc characteristic "ha", and the operating point gradually moves from the operating point "C" immediately after the reoccurrence of the arc to reach the intersection D of the external characteristic 3 and the arc characteristic "ha".

The external characteristic 3 in FIG. 4 is different from the external characteristic 3 in FIG. 1, and the welding current values Ia at the intersections C and D are different.
Are respectively larger than the current values in FIG. For this reason, even if the wire feeding speed is set higher than that in FIG. 1, the wire tip 1a is melted in a short time as shown in FIG. be able to. Thereafter, as the operating point moves, the welding current value Ia [A] gradually decreases, the arc force decreases, and the pushing force acting on the droplet 1b also decreases. Therefore, the droplet 1b hangs down due to gravity and comes into contact with the molten pool 2a.

Next, an embodiment in which the types of the shielding gas are different will be described. In this embodiment, the wire feed speed is 3.5 [m / min], the wire type is YGW12, the wire diameter is 1.2 [mm], and the shield gas type is MA.
In the case of G gas, the C1 group of the characteristic groups shown in Table 1 is selected, and a combination of the external characteristics 1 to 3 shown in FIG.

FIGS. 7A and 7B respectively show the welding load voltage value Va [V] when the external characteristic shown in FIG. 6 is selected.
FIG. 3C is a diagram showing a waveform of the welding current value Ia [A] with the elapse of time t, and FIG. 4C is a transition state diagram for explaining a state in which the droplet 1b of the wire tip 1a corresponding thereto transitions. Hereinafter, the operation will be described with reference to FIGS. 6 and 7A to 7C.

(1) Periods t0 to t7 in FIGS. 7A to 7C
Description of the operation at t1. Droplet 1b and molten pool 2 at wire tip 1a
It is detected at time t0 that a is short-circuited with a, and the external characteristic is switched to the external characteristic 1 (the characteristic of a straight line composed of symbols F and G) in FIG. 1 and FIG.
Is the same as the external characteristic 1 of FIG.
The description is omitted because it is the same as in the case of.

(2) Periods t1 to t7 in FIGS. 7A to 7C
Description of the operation at t2. At time t1 when the short-circuit duration time TS has exceeded the set short-circuit time TS1 shown in FIG. 7A, the external characteristic is switched from the external characteristic 1 in FIG. 6 to the external characteristic 2 (the characteristic of a straight line composed of symbols F and H). . At this time, since the load characteristics are continuously the resistance characteristics II ', the operating points of the welding current value Ia [A] and the welding load voltage value Va [V] are determined by the external characteristic 2 and the load characteristic II'. It becomes intersection B.

The external characteristic 2 in FIG. 6 is different from the external characteristic 2 in FIG. 1, and the welding current value Ia at the intersection B is smaller than the current value in FIG. I have. The reason is that compared to the case of CO2 gas, MAG
In the case of gas, the push-up force due to the arc force is reduced, so that the wire tip 1 is not used during a period t2 to t3 described later.
It is unlikely that the droplet 1b that grows on a becomes excessive. For this reason, a small pinch force is required to smoothly separate the droplet 1b from the molten pool 2a, so the external characteristic 2 in FIG. 6 is changed so as to reduce the current value at the intersection B. Therefore, since the current value at the time of short circuit becomes small, it is possible to reduce the occurrence of spatter accompanying the arc regeneration.

(3) Periods t2 to t7 in FIGS. 7A to 7C
Explanation of the operation at t3. At time t2, it is detected that the arc 3 has regenerated between the wire 1 and the workpiece 2, and at time t2, the external characteristic is changed to the external characteristic 3 in FIG. 6 (characteristic of a broken line composed of J, K, L and M). Switch to. At this time, the load characteristic becomes the arc characteristic "ha", and the operating point gradually moves from the operating point "C" immediately after the reoccurrence of the arc to reach the intersection D of the external characteristic 3 and the arc characteristic "ha".

The external characteristic 3 in FIG. 6 is different from the external characteristic 3 in FIG.
a are respectively smaller than the voltage values in FIG.
The reason is that the welding load voltage Va for maintaining the same arc length is smaller in the case of MAG gas than in the case of CO2 gas. This is because it is necessary to set a smaller value.

As described above, the above operation is repeated by changing the optimum external characteristics in accordance with the change of the set value of the wire feeding speed and the change of the type of the shield gas. Is performed regularly, and the stability of the welding state can be improved. It should be noted that optimum external characteristics can be obtained in accordance with a change in the diameter of the wire, and the stability of the welding state can be similarly improved with a change in which these are combined.

[0110]

【Example】

[Description of FIG. 8]. FIG. 8 is a block diagram of an embodiment of the welding power supply device of the present invention, which will be described below with reference to FIG. WL is the above-mentioned wire 1, workpiece 2 and arc 3
Or a welding load consisting of a short circuit. A power control circuit 10 for converting a commercial power supply PS into an output characteristic suitable for a welding method to which the present invention is applied. For example, in the case of an inverter-controlled welding power supply, a primary rectifier circuit, an inverter circuit, and an inverter transformer not shown And a power conversion circuit such as a secondary rectifier circuit and a drive circuit thereof. DC reactor DC
L smoothes the output of the power control circuit 10 and sets the welding load WL
Is supplied with continuous energy. Output voltage detection circuit V
B detects an output voltage of the power control circuit 10, that is, an output voltage before being smoothed by the DC reactor DCL, and outputs an output voltage detection signal Vb.

The welding current detection circuit CD detects the welding current value Ia.
And the welding current detection signal Ic is converted to an A / D conversion circuit AD.
Output to The A / D conversion circuit AD receives the welding current detection signal Ic as an input, converts the signal into a digital signal, and outputs a digital welding current detection signal Ib. This digital welding current detection signal Ib is read into the central processing circuit CPU through the input / output circuit I / O.

The feed speed setting circuit WA outputs a feed speed setting signal Wa. The feed motor control circuit WB receives the feed speed setting signal Wa and controls the wire feed motor. The wire feed motor WM feeds a wire.

The interrupt timer TM outputs an interrupt signal for each interrupt timer time Tc. Temporary storage circuit R
The AM temporarily stores data required for processing by the central processing unit CPU.

The external characteristics stored in the external characteristic data storage circuit ROM are made up of twelve characteristic groups as shown in Table 1, with three types of external characteristics 1 to 3 as one group. Characteristic groups total 36
It is formed from different types of external characteristics. Therefore, the external characteristic data storage circuit ROM stores three of characteristic numbers 1 to 36.
Six types of external characteristics are stored, and for each of these external characteristics, a digital welding current range storage signal Id and a digital output voltage setting signal Vd corresponding to the signal Id are stored.

As will be described later, the central processing circuit CPU reads the digital output voltage setting signal Vd corresponding to the digital welding current range storage signal Id from the external characteristic data storage circuit ROM, and outputs the digital output voltage setting signal Vd through the input / output circuit I / O. / A conversion circuit DA. D / A conversion circuit DA
Converts the digital output voltage setting signal Vd into an analog output voltage setting signal Vs.

Feed speed digital signal conversion circuit ADW
Receives the feed speed setting signal Wa as an input and outputs a digital feed speed setting signal Wb. Wire type selection circuit WC
Outputs a wire type selection signal Wc corresponding to the wire type. In the following description, as an example, when the wire type is YGW12 and the wire diameter is 1.2 [mm], the wire type selection signal Wc is set to 1, and the wire type is YGW1.
2. Assume a 1-bit signal in which the wire type selection signal Wc is 0 when the wire diameter is 1.0 [mm]. The shield gas type selection circuit WD outputs a shield gas type selection signal Wd corresponding to the type of the shield gas. In the following description, as an example, the type of shielding gas is CO2
In the case of a gas, the shield gas type selection signal Wd is set to 1, and when the type of the shield gas is MAG gas, the shield gas type selection signal Wd is set to 0. The digital feed speed setting signal Wb, the wire type selection signal Wc, and the shield gas type selection signal Wd are read into the central processing unit CPU through the input / output circuit I / O.

The central processing unit CPU receives the digital feed speed setting signal Wb and the wire type selection signal Wc.
And a shield gas type selection signal Wd. Then, conditional branching of Table 1 is performed by using these signals as described later, and one specific characteristic group is selected from 12 types of characteristic groups of the A1 group to the D3 group.
The data is stored in the temporary storage circuit RAM.

The welding voltage detecting circuit VC detects the welding load voltage value Va, that is, the output voltage after being smoothed by the DC reactor DCL, and outputs a welding voltage detecting signal Vc to the short circuit determining circuit VT. The short-circuit determination circuit VT determines the occurrence of a short circuit between the wire and the workpiece, and determines whether the input-output circuit I / O
And outputs the short-circuit determination signal Vt through.

The central processing circuit CPU reads the short-circuit determination signal Vt, and from the external characteristic data stored in the external characteristic data storage circuit ROM, the three types belonging to the characteristic group already selected as described above. One type of external characteristic data is selected from among them. Then, among the selected external characteristic data, the digital output voltage setting signals Vd corresponding to the digital welding current range storage signal Id specified by the digital welding current detection signal Ib which changes momentarily and is input are immediately and successively generated. And input / output circuit I / O
Output to

[Description of Table 1] External characteristic is external characteristic 1
3 are formed as one characteristic group. Table 1 described in the section of [Operation] is a table for explaining a method of selecting each characteristic group. The characteristic group A1 group is determined by the digital feed speed setting signal Wb, the wire type selection signal Wc, and the shield gas type selection signal Wd. One specific group is selected from the D3 group.

As described above, the wire type selection signal Wc
Indicates that the wire diameter of the wire type YGW12 is 1.2 [m
m] and the case where the wire diameter is 1.0 [mm]. The shield gas type selection signal Wd is CO2
The case where the signal is a signal for selecting gas and MAG gas will be described.

The feed speed digital signal conversion circuit A
A description will be given of a case where the resolution of the DW is set to 8 bits and converted into a digital feed speed setting signal Wb of data numbers 0 to 255 corresponding to the setting range 0 to 10 [m / min] of the feed speed setting signal Wa. I do. When the data number of the digital feed speed setting signal Wb is less than the data number 102 (the feed speed setting signal Wa is less than 4 [m / min]),
In addition, data number 102 or more and less than data number 154 (the feeding speed setting signal Wa is 4 [m / min] or more and 6 [m / mi]
n] and the data number 154 or more and the data number 255 or less (the feed speed setting signal Wa is 6 [m / min]).
In this case, the state branches to three states of 10 m / min or less.

These wire type selection signal Wc, shield gas selection signal Wd and digital feed speed setting signal W
According to b, as shown in Table 1, a specific characteristic group is selected from the twelve types of characteristic groups from the characteristic groups A1, A2, A3, and B1 to D3.

[Description of FIG. 9] Next, a control method for setting and outputting one external characteristic will be described. External characteristic digital welding current range storage signal Id and their respective signals Id
And a digital output voltage setting signal Vd corresponding to the external characteristic data storage circuit Rd as shown in FIG.
It is stored on the OM.

In the following description, the resolution of the A / D conversion circuit AD is 8 bits, and the detected analog welding current detection signal Ic is applied to the welding current adjustment range output by the power control circuit 10, for example, 0 to 500 [ A] is converted into a digital welding current range storage signal Id of data numbers 0 to 255 corresponding to the data number 0 to 255, and the resolution of the D / A conversion circuit DA is 8 bits. A case in which the analog output voltage setting signal Vs is converted into a setting range of 0 to 5 [V] in accordance with the digital output voltage setting signal Vd will be described.

Digital welding current range storage signal Id designated by the detected digital welding current detection signal Ib
And the digital output voltage setting signal Vd that defines the external characteristics corresponding to these signals Id, respectively. The external characteristic data is a digital welding current range storage signal Id for each external characteristic. = 0 to 2
55 are stored in the external characteristic data storage circuit ROM in the order of 55. In FIG. 9, the external characteristic 1 of the A1 group
Welding current range storage signal IdA1 / 1
/ 0, IdA1 / 1/1,..., IdA1 / 1/255, and the digital output voltage setting signal VdA1 / 1 /
0, VdA1 / 1/1,..., VdA1 / 1/255 are stored. Further, the external characteristics 2 and 3 of the A1 group and the external characteristics 1 to 3 of the A2 to D3 groups.
Are stored as shown in the data storage explanatory diagram of FIG.

[Description of FIG. 10] FIG. 10 is a data storage explanatory diagram showing a data storage method in the case of the external characteristic 1 of the A1 group. For example, if the detected welding current value Ia is 1
In the case of 7 [A], the digital welding current detection signal Ib converted by the A / D conversion circuit AD in FIG. 8 is data number 9, and the digital welding current detection signal Ib = The digital output voltage setting signal Vd = 77 corresponding to the welding current range storage signal Id designated by 9 is read. The digital output voltage setting signal Vd = 77 is output from the D / A conversion circuit DA.
Analog output voltage setting signal Vs = 1.5 [V]
Is converted to Thereby, the welding current value Ia = 17
Analog output voltage setting signal Vs = 1.
5 [V] is output.

[Description of FIGS. 11 and 12] FIGS. 11 and 12 show the A1 group to D described in Table 1 and FIG.
It is the 1st and 2nd following flowchart which shows the control method which switches the external characteristics 1 to 3 of three groups.
In the figure, every time the interrupt timer time Tc (for example, 100 [μs] in this case) is set, a step 7 [SP] is executed.
7] is performed, and step 7 [SP7] is performed.
Through step 17 [SP17], one round of control is performed. Hereinafter, the operation of each step will be described with reference to the waveform diagrams of FIGS. 5A and 5B and the block diagram of the welding power supply device of the present invention of FIG.

In the feed speed storage step 1 [SP1], the feed speed setting signal Wa output from the feed speed setting circuit WA in FIG. 8 is converted into a digital feed speed setting signal Wb by the feed speed digital signal conversion circuit ADW. Is read into the central processing unit CPU, stored in the temporary storage circuit RAM, and proceeds to step 2.

The wire type storage step 2 [SP2]
In this step, the wire type selection signal Wc output by the wire type selection circuit WC in FIG. 8 is read into the central processing unit CPU, stored in the temporary storage circuit RAM, and proceeds to step 3.

Shield gas type storage step 3 [SP
3] converts the shielding gas type selection signal Wd output by the shielding gas type selection circuit WD of FIG.
This is a step of reading the data into the PU and storing it in the temporary storage circuit RAM, and proceeding to Step 4.

Characteristic group selection step 4 [SP4]
Performs a branch shown in Table 1 by a digital feed speed setting signal Wb, a wire type selection signal Wc, and a shield gas type selection signal Wd, selects a specific characteristic group from the A1 group to the D3 group, and proceeds to step 5 It is.

In welding current detection step 5 [SP5], welding current value Ia is detected by welding current detection circuit CD in FIG. 8, a welding current detection signal Ic is output, and the process proceeds to step 6.

In the initial setting step 6 [SP6], the interrupt timer time Tc (100 [μs] in this case) is set in the interrupt timer TM for generating a timer interrupt. Further, this is a step in which the short-circuit continuation time count value Ns is reset to 0, and the process proceeds to step 7.

In the interrupt determination step 7 [SP7], the presence or absence of a timer interrupt is determined. If there is an interrupt, the process proceeds to step 8, and if there is no interrupt, the process is continued until the next timer interrupt occurs.

In welding current storage step 8 [SP8], when a timer interrupt occurs, the detected welding current detection signal Ic is converted into a digital welding current detection signal Ib, stored in the temporary storage circuit RAM, and then to step 9 This is the next step.

The short arc determination step 9 [SP9]
The short-circuit determination signal Vt is read into the central processing circuit CPU from the short-circuit determination circuit VT which receives the welding voltage detection signal Vc in FIG.
If it is in the short-circuit state, the process proceeds to step 10, and if it is in the arc generation state, the process proceeds to step 15.

[Step 9 [SP9] When Short-circuited] The short circuit counting step 10 [SP10] counts up the short circuit continuation time count value Ns to obtain Ns + 1.
Then, the process proceeds to step 11. One count of the above count value is determined by the interrupt timer time limit Tc.

Short circuit time comparison step 11 [SP11]
Compares the short-circuit duration count value Ns with the short-circuit time count set value (duration count set value of the external characteristic 1) Ns1, and when Ns <Ns1, proceeds to step 12.
When Ns ≧ Ns1, the process proceeds to step S16. The relationship between the short-circuit time count set value Ns1 and the set short-circuit time TS1 in FIG.
Since 0 [μs], Ns1 = TS1 [sec] × 100
00. For example, Ns1 = 10 when TS1 = 1 ms.

[Step 11: Ns <Ns in [SP11]
1]. First external characteristic output step 12 [SP1
2] is a digital welding current detection signal I of the external characteristic 1 for supplying a welding current of a low current value from the external characteristic data storage circuit ROM when Ns <Ns1 in step 11.
In this step, the digital output voltage setting signal Vd corresponding to the digital welding current range storage signal Id designated by b is read out, and the process proceeds to step S13.

Power control step 13 [SP13] converts the digital output voltage setting signal Vd into a D / A conversion circuit DA.
Is converted to an analog output voltage setting signal Vs, and output to the power control circuit 10 through the comparison circuit CM.

[Step 11: Ns ≧ Ns in [SP11]
1]. Second external characteristic output step 16 [SP1
6] is a digital welding current detection signal I of the external characteristic 2 for supplying a welding current of a large current value from the external characteristic data storage circuit ROM when Ns ≧ Ns1 in step 11.
In this step, the digital output voltage setting signal Vd corresponding to the digital welding current range storage signal Id designated by b is read out, and the process proceeds to step S13.

[Step 9 When an Arc is Generated in [SP9]] The short circuit reset step 15 [SP15]
This is a step of resetting the short-circuit continuation time count value Ns to 0 and proceeding to step 117.

In the third external characteristic output step 17, a digital welding current detection signal I of the external characteristic 3 for applying a welding current of an arc current is read from the external characteristic data storage circuit ROM.
In this step, the digital output voltage setting signal Vd corresponding to the digital welding current range storage signal Id designated by b is read out, and the process proceeds to step S13.

The welding end command determination step 14 is a step for determining whether or not a welding end command is present after the execution of the step 13, and returning to step 7 when there is no command, and ending welding when there is a command.

[0200]

According to the present invention, in a consumable electrode type arc welding using CO2 gas, MAG gas or the like, a short-circuit state can be achieved by switching external characteristics at a high speed according to a transition state of a droplet at a wire tip. Since the repetition of the arc generation state becomes regular and the transfer of the droplet at the tip of the wire is performed smoothly, the effect of the prior application technique that a stable welding state can be obtained is provided.

Furthermore, in the present invention, the prior art (Japanese Patent Application No.
-345343), it is possible to prevent the occurrence of an irregular repetition of a short circuit and arcing that occurs when at least one of the set values of the wire feeding speed, the wire type, and the shield gas type is changed. Therefore, even if the set value of the welding condition is changed, a favorable welding state can always be obtained.

In particular, in the present invention, even if the wire feeding speed and the wire type are the same, the type of the shielding gas is set to CO.
2 When the gas and the MAG gas are changed, the growth size of the droplet 1b is different due to the difference in the magnitude of the arc force depending on the type of the shielding gas, and the current value at the time of short circuit can be appropriately adjusted accordingly. Therefore, spatter during arc regeneration can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a transient characteristic of a welding power supply device, a load characteristic between an object to be welded and a wire, and an operating point determined by the external characteristic and the load characteristic in short-circuit transfer welding according to the prior art. It is.

FIGS. 2A and 2B are respectively a welding load voltage value Va and a welding current value Ia during short circuit transfer welding according to the prior art.
FIG. 4C is a diagram showing waveforms with respect to the passage of time t. FIG. 4C is a transition state diagram illustrating a state in which droplets 1b that have grown on the wire tip 1a corresponding thereto transition.

FIGS. 3 (A) and (B) show a welding current value Ia and a welding load voltage value Va when a welding condition becomes unstable due to a change in welding conditions in short-circuit transfer welding according to the prior art. FIG. 7C is a diagram showing waveforms with respect to the passage of time t. FIG. 7C is a transition state diagram for explaining a state in which the molten droplet 1b of the wire tip 1a corresponding thereto transitions.

FIG. 4 is a diagram showing external characteristics 1 to 3 of an A3 group shown in Table 1 in the welding power supply device of the present invention.

5 (A) and 5 (B) respectively show a welding current value I when welding is performed with the external characteristics of FIG. 4 in the present invention.
FIG. 7C is a diagram showing waveforms of the welding load voltage value Va with respect to the passage of time t. FIG. 7C is a transition state diagram illustrating a state in which the droplet 1b of the wire tip 1a corresponding thereto transitions.

FIG. 6 is a diagram showing external characteristics 1 to 3 of a C1 group shown in Table 1 in the welding power supply device of the present invention.

7 (A) and 7 (B) show welding current values I when welding is performed with the external characteristics shown in FIG. 6 in the present invention, respectively.
FIG. 7C is a diagram showing waveforms of the welding load voltage value Va with respect to the passage of time t. FIG. 7C is a transition state diagram illustrating a state in which the droplet 1b of the wire tip 1a corresponding thereto transitions.

FIG. 8 is a block diagram of an embodiment of the welding power supply device of the present invention.

FIG. 9 is an explanatory diagram of external characteristic data storage in an external characteristic data storage circuit ROM.

FIG. 10 is an explanatory diagram of data storage of the external characteristic 1 of the A1 group in the control method of the present invention.

FIG. 11 is a first flowchart illustrating a control method for switching the external characteristics 1 to 3 of the groups A1 to D3 in the present invention.

FIG. 12 is a second flowchart following the first flowchart in FIG. 11;

FIG. 13 is a claim correspondence diagram of a control method for switching the external characteristics 1 to 3 of the A1 group to the D3 group according to the first aspect of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 wire 1a wire tip 1b droplet 2 workpiece 2a weld pool 3 arc 10 power control circuit WL welding load PS commercial power supply DCL DC reactor VB output voltage detection circuit VC welding voltage detection circuit CD welding current detection circuit VT short circuit determination circuit CM Comparison circuit AD A / D conversion circuit I / O input / output circuit DAD / A conversion circuit RAM Temporary storage circuit ROM External characteristic data storage circuit CPU Central processing circuit TM Interrupt timer circuit WM Wire feed motor WA Feed speed setting circuit WB Feed motor control circuit ADW Feed speed digital signal conversion circuit WC Wire type selection circuit WD Shield gas type selection circuit TS Duration TS1 Set short circuit time (Set time of external characteristic 1) Ia Welding current value Va Welding load voltage value e Welding power supply output voltage value Ic (analog) welding Current detection signal Ib Digital welding current detection signal Id (Digital) welding current range storage signal Vd Digital output voltage setting signal Vs (Analog) output voltage setting signal Vc Welding voltage detection signal Vt Short circuit determination signal Vb Output voltage detection signal Cm Power control signal Wa Feeding speed setting signal Wb Digital feeding speed setting signal Wc Wire type selection signal Wd Shield gas type selection signal Tc Interrupt timer time limit Ns Short circuit continuation time count value Ns1 Short circuit time count setting value (continuous time count setting value of external characteristic 1) SP1 to SP17 Steps 1 to 17

[Table 1]

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Takuji Matsuura 2-1-1-11 Tagawa, Yodogawa-ku, Osaka-shi Daihen Co., Ltd. (56) References JP-A-62-112069 (JP, A) JP-A-62 −33068 (JP, A) JP-A-2-187270 (JP, A) JP-A-4-13479 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 9/073 B23K 9/10 B23K 9/173

Claims (2)

(57) [Claims] 1. A placed in consumable electrode arc welding control method
A welding current detecting step of detecting a welding current value and outputting a welding current detection signal; a short-circuit arc determining step of detecting a welding load voltage value to determine whether a short-circuit state or an arc occurrence state has occurred; If the duration of the short-circuit is less than the set short-circuit time, the output voltage setting signal for forming the first external characteristic for applying the welding current having a low current value from the external characteristic data storage circuit with the welding current detection signal as an input. A step of outputting a first external characteristic, and when the short-circuit state and the duration of the short-circuit are equal to or longer than the set short-circuit time, the welding current detection signal is input and the high-current welding is performed from the external characteristic data storage circuit. Second to pass current
Output voltage setting signal forming the external characteristic of the second
The step of outputting the external characteristics of the following; and when the arc is occurring , the external characteristics change depending on the welding current range for applying the arc current from the external characteristic data storage circuit with the welding current detection signal as an input.
An output step of a third external characteristic for outputting an output voltage setting signal for forming a third external characteristic of the combined characteristic; and the first to third external characteristics as one set of characteristic groups.
Feed speed setting signal, wire type selection signal and shield
Multiple signals corresponding to at least one of the gas type selection signals
Several sets of the characteristic groups are stored in the external characteristic data storage circuit.
The feed speed setting signal and the wire type selection signal
Signal and at least one of the shield gas type selection signals
Select a specific set of said characteristic groups
Consumable electrode type arc welding control method, comprising : 2. A consumable electrode type arc welding power supply device, a power control circuit for converting characteristics of a commercial power supply into an output voltage suitable for welding, and a welding current detection for detecting a welding current value and outputting a welding current detection signal. A wire feed motor control circuit that controls the wire feed motor with the feed speed setting signal as an input; a welding voltage detection circuit that detects a welding load voltage value and outputs a welding voltage detection signal; A short circuit determining circuit that receives a welding voltage detection signal as input and determines whether a short circuit has occurred between the wire and the workpiece and outputs a short circuit determination signal, and a wire type selection circuit that outputs a wire type selection signal corresponding to the type of wire. A shield gas type selection circuit that outputs a shield gas type selection signal corresponding to the type of the shield gas; and a total welding current in a welding current adjustment range output by the power control circuit. Are sequentially divided and stored in a signal group corresponding to a number of welding current values, and a signal corresponding to the welding current range storage signal and an output voltage setting signal corresponding to the signal corresponding to the welding current range storage signal. External characteristic data consisting of signals
Data, and the short-circuit duration is set in the short-circuit state.
When the welding current is less than the first welding current, a welding current having a low current value is supplied.
The external characteristic data of
Apply a large welding current when the set short-circuit time is exceeded
When the second external characteristic data and the arc occurrence state
External characteristics depend on the welding current range for conducting arc current.
The third external characteristic data of the composite characteristic of which
Feed speed setting signal and wire type selection as characteristic group
At least one of the signal and the shield gas type selection signal
An external characteristic data storage circuit for storing a plurality of sets of the characteristic groups corresponding to the signals; and a feed speed setting signal and the wire from a plurality of sets of the external characteristic data stored in the external characteristic data storage circuit. After selecting a characteristic group of a specific external characteristic by inputting at least one of a type selection signal and the shield gas type selection signal, a signal corresponding to the welding current detection signal and the short circuit determination signal are input, and One external characteristic data is determined from the selected characteristic group, and a signal group corresponding to an output voltage setting signal corresponding to the welding current range storage signal specified by the welding current detection signal is read out from the external characteristic data storage circuit. A consumable electrode type arc welding power supply device comprising: a central processing circuit for outputting to the power control circuit.