JPH05318114A - Method for controlling output of consumable electrode type gas shield arc welding and welding device therefor - Google Patents

Abstract

PURPOSE:To facilitate satisfactory welding even for the inexperienced person by measuring the value of a weld ripple element during welding, drawing a fuzzy inference in accordance with a prescribed control regulation and setting an output voltage. CONSTITUTION:A commercial AC is converted to DC by a rectifier 1 on the input side, and converted to a high-frequency AC by an inverter circuit 2. Through a welding transformer 3, a rectifier 4 on the output side, and a DC reactor 5, a DC is outputted to a welding zone. During the welding, a welding voltage is detected by a voltage detector 14; a short-circuited period and an arcing period are discriminated by a discriminator 17; the standard deviation between the two periods are processed in a fuzzy state by a fuzzy controller 22 through a prescribed fuzzy function and a rule of inference; an optimum arc voltage is calculated by an adder-subtractor circuit 11; and the inverter circuit 2 is operated. Even the inexperienced person can always obtain a satisfactory welding result equally as the experienced person.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power control method for consumable electrode type gas shielded arc welding and a welding apparatus therefor.

[0002]

_2. Description of the Related Art In consumable electrode type gas shielded arc welding such as CO ₂ or MAG welding, the welding current value is selected according to the work situation and the work shape. By the way, in order to obtain a good welding result, it is necessary to set the output voltage of the welding machine so as to obtain an appropriate arc voltage according to the welding current value. However, the appropriate arc voltage varies not only with the welding current value but also with the work environment and form. For this reason, considerable skill and skill improvement are required to set the output voltage of the welding machine so that an appropriate arc voltage can be obtained for the selected welding current value. is not. Therefore, in order that even a beginner can obtain a welding result equivalent to that of a skilled person, JP-A-56-1582
In Japanese Patent Publication No. 81 (hereinafter referred to as the first prior art), a database of the relationship between the welding current and the proper output voltage is prepared in advance, and when the welding current is selected, the output voltage of the welding machine is set in a unified manner. A technology provided with a function is disclosed. Further, JP-A-60-128340 (hereinafter referred to as the second prior art) and JP-A-60-162577 (hereinafter referred to as the third prior art) disclose the current and voltage waveforms during welding. A technique is disclosed in which the observation result is calculated by a predetermined function and the output voltage is set so that the calculated value becomes the minimum.

[0003]

When welding large structures, for example, the welding cable is often extended.
In this case, in order to obtain an appropriate arc voltage, it is necessary to increase the output voltage of the welding machine and correct the influence of the voltage drop that occurs in the extended welding cable. However, in the case of the above-mentioned first conventional technique, the output voltage automatically set as an appropriate arc voltage is selected as data under a predetermined reference condition and standard working environment, and therefore deviates from the standard working environment. In this case, the value is not appropriate. An appropriate value can be obtained by wiring the detection line for detecting the arc voltage up to the welded portion, but if the wiring is increased, the operability deteriorates. Furthermore, what is selected as the data is one selected by a specific skilled welding operator, and it cannot be said that it is necessarily an unbiased and proper value. In addition, in the case of the second to third conventional techniques, it is possible to correct the voltage drop when the extension cable is used, but in order to minimize the value calculated by the predetermined function, the output voltage It is necessary to operate and obtain at least three calculated values, and it takes time to obtain a proper arc voltage. The purpose of the present invention is to
An output control method for consumable electrode type gas shielded arc welding, which solves the above-mentioned problems and can always obtain good welding results, regardless of changes in work environment and form or degree of skill of an operator, and a method thereof. It is to provide a welding device for performing.

[0004]

Means for Solving the Problems The above-mentioned problem is solved in a power control method of consumable electrode type gas shielded arc welding in which a wire is fed at a substantially constant speed and welding is performed while alternately repeating a short circuit and an arc. The value of at least two kinds of welding waveform factors measured in the above is used as the antecedent part, and the manipulated variable of the output voltage is used as the antecedent part, and the fuzzy inference is executed according to the predetermined control rule to increase or decrease the output voltage setting. Solved by determining the amount.

[0005]

[Function] In a welding device with a constant voltage external characteristic, if the output voltage of the welding machine, that is, the arc voltage is changed while the wire feeding speed, that is, the setting value of the welding current is kept constant, it will respond to the change of the arc voltage. Then, the standard deviations of the short circuit period and the arc period also change. Therefore, the short circuit period and the arc period are measured to obtain the respective standard deviations, and the standard deviations thus obtained are fuzzy processed according to a predetermined fuzzy function and inference rules, and the manipulated variable for obtaining the proper arc voltage is calculated to calculate the output voltage. The output voltage of the welding machine is automatically set to an appropriate value because the value is increased or decreased.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a first structural example of a welding apparatus for carrying out the present invention. In the figure, 1 is an input side rectifier for converting commercial AC into DC, and 2 is an inverter circuit composed of power semiconductor elements, which converts the DC into high frequency AC. 3 is a welding transformer, the input side of which is connected to the inverter circuit 2. An output side rectifier 4 is connected to the output side of the welding transformer 3, and converts the high frequency alternating current generated by the inverter circuit 2 into a direct current again. A DC reactor 5 smoothes the DC output rectified by the output side rectifier 4. Reference numeral 6 denotes a wire, which is supplied to the welding portion by the wire feeding device 7. 8 is the base metal. 9 is a welding current setting device,
This is for setting the feeding speed of the wire 6. The inverter circuit 2 is controlled so that the external characteristic becomes a constant voltage characteristic. 10 is an output voltage setting device, which is an output voltage V
It is for setting ₀ . 11 is an adder / subtractor circuit,
The output voltage V ₀ set by the output voltage setting unit 10 and the manipulated variable ΔV of the output voltage output from the fuzzy controller 22 described later are combined, and the result is output to the pulse width control circuit 12. The pulse width control circuit 12 uses the signal from the adder / subtractor circuit 11 to drive the inverter circuit 2 via the drive circuit 13.
Control the output of.

Reference numeral 14 is a voltage detector. 15 is a voltage detector 14
Sampling condition setting device. 16 is a judgment voltage setting device. 1
Reference numeral 7 is a judgment device for judging whether it is a short circuit or an arc. The welding voltage υ measured by the voltage detector 14 and the judgment voltage setting device 16 are set in accordance with the sampling interval and sampling time set by the sampling condition setting device 15. The magnitude of the judgment voltage Vj is compared. Then, the determiner 17 determines that ν ≦ Vj
In the case of, the determination signal of the short-circuit period is output to the Ts measuring device 18, and in the case of υ> Vj, the determination signal of the arc period is output to the Ta measuring device 19.
The Ts measuring device 18 and the Ta measuring device 19 calculate the standard deviation s _Ts of the short-circuit period for the measured value (Ts and Ta value) of each time for each short-circuit cycle in which the short circuit and the arc are alternately repeated. Standard deviation s of instrument 20 and arc period
Input to the _Ta calculator 21. The arithmetic unit 20 uses the output of the Ts measuring unit 18 to calculate the sum ΣTs of Ts and the sum ΣTs ² of squares of Ts, and the number N of Ts.
_Is calculated, the value of the standard deviation s _Ts is calculated by the following equation 1, and the value is output to the fuzzy controller 22. The arithmetic unit 21 also calculates the value of the standard deviation s _Ta by the following equation 2 in the same manner as the arithmetic unit 20 and outputs the value to the fuzzy controller 22.

[0008]

[Equation 1]

[0009]

[Equation 2]

The setter 23 determines the standard deviations s _Ts and s _Ta which are the factors constituting the antecedent part of the fuzzy inference and the fuzzy variables of the factor ΔV (output voltage manipulated variable) which constitutes the antecedent part, and these variables. It is for inputting inference rules about factors. Then, the fuzzy controller 22 obtains the conformity of the input standard deviation s _Ts and standard deviation s _{Ta to} the inference rule based on the fuzzy variable and the inference rule set by the setter 23, Calculate the inference results that match each rule. Then, the inference results obtained for each inference rule are integrated, and the overall inference result ΔV
Is calculated by the centroid method and is output to the adder circuit 11.

The inference method in the fuzzy controller 22 will be described in more detail below. (1) When the transfer form of the droplet formed at the tip of the wire to the base material is a short-circuit transfer. When the droplet transfer form is a short-circuit transfer, the wire feeding speed is relatively slow and the welding current is relatively small. Then, the standard deviation s _Ts and the standard deviation s _Ta at this time change according to the arc voltage as shown in FIGS. 2 and 3, respectively. Therefore, the standard deviation s _{Ts, the} standard deviation s _Ta, and the fuzzy variables of the manipulated variable ΔV of the output voltage are set as shown in FIGS. 4 to 6, respectively, and a total of 15 inference rules shown in Table 1 are set.

[0012]

[Table 1]

Among the inference rules in Table 1,
R ₁ , R ₂ , and R ₃ will be described below as typical examples. The symbols in parentheses are shown in Table 1. R ₁ ; If s _Ts is small (S) and s _Ta is slightly small (SM), the output voltage is not changed (ΔV = Z
0) R ₂ ; If s _Ts is small (S) and s _Ta is extremely large (BB), the output voltage is significantly reduced (Δ
V = NB) R ₃ ; If s _Ts is large (B) and s _Ta is slightly large (MB), the output voltage is significantly increased (ΔV
= PB) That is, the output voltage V ₀ set by the output voltage setting unit 10
2 is lower than the proper voltage,
As shown in, since the value of s _Ts is large and the value of s _Ta is slightly large, the inference result that the above inference rule R ₃ is applied and the output voltage is significantly increased (ΔV = PB)
To get Further, when the output voltage V ₀ set by the output voltage setting device 10 is proper, the value of s _{T s} is small and s _Ta
Since the value of is slightly smaller, the above inference rule R ₁ is applied and the inference result that the output voltage is not changed (ΔV =
Z0) is obtained. Furthermore, if the output voltage V ₀ set by the output voltage setting unit 10 is too high with respect to the proper voltage, s _Ts
Since the value of is small and the value of s _Ta is extremely large, the above inference rule R ₂ is applied, and the inference result (ΔV = NB) is obtained that the output voltage is significantly reduced. In other cases, as in the case of R ₁ , R ₂ and R ₃ above,
When the set value of the output voltage is lower than the proper voltage, the amount of increase in the output voltage according to the amount of deviation from the proper voltage, and when the set value of the output voltage is higher than the proper voltage, the extent of the increase The reduction amount of the output voltage is given as the fuzzy inference result ΔV. That is, no matter what the initial output voltage setting is, test welding is performed for a predetermined time under the set value, and the fuzzy inference is performed using the values of s _Ts and s _Ta at that time. If done, the output voltage can always be set to an appropriate value.

(2) When droplets formed at the tip of the wire are transferred to the base material by globule transfer. When the droplet transfer form is globule transfer, the wire feed rate is relatively fast, and the welding current is medium to relatively large. Then, the standard deviation s _Ts and the standard deviation s _Ta at this time
Changes according to the arc voltage as shown in FIGS. 7 and 8, respectively. Therefore, the standard deviation s _{Ts, the} standard deviation s _Ta, and the fuzzy variables of the manipulated variable ΔV of the output voltage are set as shown in FIGS. 9 to 11, respectively, and the inference rules shown in Table 2 are set. As in the case of the short-circuit transfer, the test welding is performed for a specified time under the set value of the initial output voltage, and the values of s _Ts and s _Ta at that time are set. If the above fuzzy inference is performed using the output voltage, the output voltage can always be set to an appropriate value.

[0015]

[Table 2]

In the following (A) and (B), examples of fuzzy variables for which good results are obtained are shown in FIGS.
Based on. (A) When the transfer form of the droplets to the base material is a short circuit transfer. The wire feeding speed is 3 m / min. In FIG. 4, a ₁ = 1.2 ms, a ₂ = 1.5 ms, a ₃ = 2.0 ms, a
_{4 = 2.4ms, a 5 = 2.7ms} , a 6 = 3.2ms, a 7
= 3.5 ms, in FIG. _{5, b 1 = -0.3ms, b} 2 = 0.5ms, b 3 = 3.0ms,
b ₄ = 3.8 ms, b ₅ = 4.7 ms, b ₆ = 7.2 ms, b
_{7 = b 8 = 8.0ms, b} 9 = 11.3ms, b 10 = 13.0
ms, b ₁₁ = 15.5 ms, b ₁₂ = 18.0 ms, b ₁₃ =
In 19.7ms Figure _{6, c 1 = c 2 =} -6.5V, c 3 = c 4 = c 5 = -4.3V, c 6
_{= C 7 = c 8 = -2.2V} , c 9 = c 10 = c 11 = 0V, c 12
= C ₁₃ = c ₁₄ = 2.2V, c ₁₅ = c ₁₆ = c ₁₇ = 4.3V,
c ₁₈ = c ₁₉ = 6.5V (B) When the droplet transfer form to the base material is globule transfer. The wire feeding speed is 7.5 m / min. In FIG. 9, a ′ ₁ = 1.3 ms, a ′ ₂ = 1.4 ms, a ′ ₃ = a ′ ₄ = a
′ ₅ = 1.6 ms, a ′ ₆ = 1.8 ms, a ′ ₇ = 1.9 ms In FIG. 10, b ′ ₁ = ₆ ms, b ′ ₂ = ₇ ms, b ′ ₃ = 10 ms, b ′ ₄ =
_{12ms, b'5 = 13ms, b'} 6 = 17ms, b'7 = 1
_{8ms, b'8 = 20ms, b'} 9 = 23ms, b'10 = 2
_{4ms, b'11 = 25ms, b'} 12 = 28ms, b'13 =
29 ms In FIG. 11, c ′ ₁ = c ′ ₂ = −4.3 V, c ′ ₃ = c ′ ₄ = c ′ ₅ = −
_{2.2V, c'6 = c'7 =} c'8 = 0V, c'9 = c'10
_{= C'11 = 2.2V, c'12} = c'13 = c'14 = 4.3
V, are as _c'15 = _c'16 = 6.5V.

FIG. 12 is a second structural example view of a welding apparatus for carrying out the present invention. The same components as those in FIG. 1 are designated by the same reference numerals. In the figure, 31 is a DC reactor provided with a secondary winding 32. The secondary coil 32 has an stance of L ₂ . A detector 33 detects the voltage induced between the terminals of the secondary winding 32. Reference numeral 34 is a judging device for judging short circuit and arc. Further, 35 is a display, which displays the increase / decrease value of the obtained output voltage set value. Hereinafter, a method of determining a short circuit and an arc in the second configuration example will be described. When the welding current flows, the voltage e ₂ induced between the terminals of the secondary winding 32 changes the welding current with time d.
It can be expressed by Equation 3 using i / dt. e ₂ = −L ₂ · di / dt Formula 3 By the way, in the consumable electrode type gas shield arc welding in which short circuit and arc are alternately repeated, the current increases during the short circuit period,
Since the current decreases during the arc period, di during the short circuit period
/ Dt is positive and di / dt during the arc period is negative. Therefore, the voltage e ₂ between the terminals of the secondary winding 32 is e ₂ <0 during the short circuit period and e ₂ ≧ 0 during the arc period. Judge 34
Is based on the voltage e ₂ input from the detector 33, e ₂
In the case of <0, the determination signal of the short-circuit period is output to the Ts measuring device 18, and in the case of e ₂ ≧ 0, the determination signal of the arc period is output to the Ta measuring device 19. With such a configuration, it becomes possible to determine a short circuit and an arc without detecting the arc voltage, and the present invention can be implemented with a simpler configuration. Further, in this configuration example, since the indicator 35 is provided, if the same welding work is continuously performed, appropriate welding can be performed from the beginning by changing the set value of the output voltage according to the display of the indicator 35. The display 35 may display not only the increase / decrease value of the output voltage set value but also the output voltage set value and the increase / decrease value of the output voltage set value, or the sum thereof.

In the above two embodiments, the standard deviation s
_{Although the} method of performing fuzzy inference using _Ts and standard deviation s _Ta as the antecedent has been described, the factors used as the antecedent are not limited to s _Ts and s _Ta , and the arc voltage can be differentiated. Any factor may be used as long as it is available. That is, for example, an average value may be used instead of the standard deviation of the short circuit period Ts and the arc period Ta measured by the Ts measuring device 18 and the Ta measuring device 19. Further, the welding current value is detected by providing a welding current detector, and the standard deviation s _Is of the short circuit average current which is the average value of the welding current during the short circuit period Ts and the arc average which is the average value of the welding current during the arc period Ta. Similar results can be obtained by using the standard deviation s _{Ia of the} current. Furthermore, the factors that make up the antecedent part are not limited to two, and for example,
It goes without saying that the accuracy of inference can be further improved by using the above four s _Ts , s _Ta , s _Is, and s _Ia . Also, the manipulated variable of the output voltage obtained by fuzzy inference is
It is not always necessary to obtain the optimum voltage,
It can be easily inferred that what kind of output voltage should be obtained may be selected according to the work situation, that is, the work situation such as the reduction of excess or the deep penetration.

[0019]

As described in detail above, according to the present invention,
Whatever value the initial output voltage is set to, the output voltage can be automatically changed to an appropriate value. Therefore, even if an extension cable is added, the power supply voltage, the wire protrusion length is changed, etc., it is not necessary to make fine adjustment of the output voltage, which has been required by the skilled artisan. There is an effect that a good welding result can always be obtained.

[Brief description of drawings]

FIG. 1 is a first configuration example of a welding device for carrying out the present invention.

FIG. 2 is a diagram showing a relationship between a standard deviation s _Ts and an arc voltage in a short circuit transition region.

FIG. 3 is a diagram showing a relationship between a standard deviation s _Ta and an arc voltage in a short circuit transition region.

FIG. 4 is an example of a fuzzy variable of s _Ts for a short-circuit transition region.

FIG. 5 is an example of a fuzzy variable of s _Ta for a short-circuit transition region.

FIG. 6 shows an example of a ΔV fuzzy variable for a short-circuit transition region.

FIG. 7 is a diagram showing a relationship between s _Ts and an arc voltage in a globule transition region.

FIG. 8 is a diagram showing a relationship between s _Ta and arc voltage in a globule transition region.

FIG. 9 is an example of a fuzzy variable of s _Ts for a globule transition region.

FIG. 10 is an example of a fuzzy variable of s _Ta for a globule transition region.

FIG. 11 shows an example of a fuzzy variable of ΔV for a globule transition area.

FIG. 12 is a second configuration example of a welding device for carrying out the present invention.

[Explanation of symbols]

2 Inverter circuit 5,31 DC reactor 6 Wire 10 Output voltage setting device 11 Addition / subtraction circuit 12 Pulse width control circuit 14 Voltage detector 15 Sampling condition setting device 16 Judgment voltage setting device 17 Judgment device 18 Ts measurement device 19 Ta measurement device 20, 21 arithmetic unit 22 fuzzy controller 23 setting device 32 secondary winding 33 detector 34 judgment device 35 indicator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kihoku Fujiwara Co., Ltd. Machinery Research Institute, 502 Jinritsucho, Tsuchiura, Ibaraki Prefecture

Claims (6)

[Claims] 1. A power control method for consumable electrode type gas shielded arc welding in which a wire is fed at a substantially constant speed and welding is performed while alternately repeating a short circuit and an arc, and at least two types of measurements are performed during welding. The value of the welding waveform factor is the antecedent part, and the manipulated variable of the output voltage is the consequent part, and the fuzzy inference is executed according to a predetermined control rule to determine the increased or decreased manipulated variable of the output voltage setting. Output control method for consumable electrode gas shield arc welding. 2. The output control method for consumable electrode type gas shielded arc welding according to claim 1, wherein the value of the welding waveform factor input as the antecedent is the standard deviation of the short circuit period and the arc period. .. 3. The consumable electrode type gas shield arc according to claim 1, wherein the amount of increase / decrease operation of the output voltage obtained by fuzzy reasoning is for obtaining an appropriate arc voltage. Welding output control method. 4. A consumable electrode type gas shield arc welding welding device for feeding a wire at a substantially constant speed and alternately repeating a short circuit and an arc, and a means for calculating at least two kinds of welding waveform factors. A fuzzy controller which infers the manipulated variable of the output voltage for obtaining a predetermined arc state according to a predetermined control rule by using the calculation result of the calculation means as an input, and the output of the welding power source according to the output of the fuzzy controller A welding device for gas shielded arc welding of a consumable electrode, comprising: a means for increasing / decreasing a voltage setting value. 5. The consumable electrode type gas shielded arc welding according to claim 4, wherein the means for discriminating the short-circuit period and the arc period is a DC reactor having a secondary winding connected to the output circuit. apparatus. 6. The method according to claim 4, further comprising means for displaying an increase / decrease value of an output voltage set value of the welding power source, an output voltage set value and an increase / decrease value of the output voltage set value, or a sum thereof. Welding equipment for consumable electrode type gas shield arc welding.