JPH0542367A - Output control method for gas shielded arc welding power source - Google Patents

Abstract

PURPOSE:To omit complicated adjusting work before welding and during welding and to remarkably improve welding performance in performing gas shielded arc welding while at least one of a welding current and the welding voltage is controlled based on an output control pattern. CONSTITUTION:Excess and deficiency of the output control quantity based on the output control pattern are subjected to fuzzy inference according to an analyzed result of a welding state based on detected values of the welding current and welding voltage during welding and above-mentioned output control quantity is corrected so as to enhance stability of an arc according to a result of the inference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention controls at least one of a gas shielded consumable electrode, a welding current flowing through a base metal and a welding voltage in accordance with a set control pattern so that the electrode and the base metal are connected to each other. The present invention relates to an output control method for a gas shielded arc welding power source that alternately generates a short circuit and an arc between the two.

[0002]

2. Description of the Related Art Conventionally, in gas shielded arc welding, stabilizing the arc to improve weldability is equivalent to suppressing spatter generation and enabling high-speed welding work. In order to achieve the above object, an output control method of this type of gas shielded arc welding power source is disclosed in Japanese Patent Application Nos. 63-126792 and 63-1.
As described in the specification and drawings of the applications of No. 26793 and No. 63-212797, at least one of the welding current and the welding voltage is variably controlled in accordance with the state change of short circuit occurrence and arc occurrence.

Next, a conventional output control method for a gas shielded arc welding power source will be described with reference to FIG. In the figure, 1 is an input side rectification unit connected to an AC power source such as a commercial power source, 2 is a smoothing unit connected to the rectification unit 1, 3 is a high frequency inverter unit connected to the smoothing unit 2, and a smoothing unit It is composed of a switching element that converts the output of 2 into alternating current.

Reference numeral 4 is a transformer for transforming the output voltage of the inverter unit 5, 5 is an output side rectifying unit for rectifying the secondary side output of the transformer 4, and 6 is a power supply connected to one output terminal of the rectifying unit 5. The tip 7 is a consumable electrode that is energized via the power feed tip 6, and is composed of a welding wire that is fed at a predetermined speed in the direction of the welding base metal 8 during welding.

Reference numeral 9 is a current detector provided between the base material 8 and the other output terminal of the rectifying section 5, and 10 is a voltage detector, which detects the voltage between the feeding chip 6 and the base material 8.

Reference numeral 11 is a reference current setting device, 12 is a reference voltage setting device, 13 is a threshold voltage setting device, 14 is an error amplifier for outputting the difference between the detection value of the detector 9 and the current reference value of the setting device 11, Reference numeral 15 is an error amplifier that outputs the difference between the detected value of the detector 10 and the voltage reference value of the setter 12, and 16 is the electrode 7 comparing the detected value of the detector 10 with the threshold value of the threshold voltage setter 13. , A discriminator for discriminating the occurrence of a short circuit between the base materials 8 and the occurrence of arc, 17 is a timer which operates for Td time from the occurrence of arc, 18
Is a control unit having a microcomputer configuration, which controls each unit based on the outputs of the error amplifiers 14 and 15 and the timer 17.

19 is a high frequency oscillator of 100 to 500 Hz,
Reference numeral 20 denotes a pulse generator that generates a rectangular pulse having an output frequency of the oscillator 19 in response to an interrupt signal from the control unit 18. Reference numeral 21 denotes an inverter drive unit, which is controlled in operation by the control unit 18 and drives a switching element of the inverter unit 3. Then, the output of the inverter unit 3 is controlled.

In the shield gas atmosphere, the electrode 7 is fed at a constant speed in the direction of the base metal 8, and in the short circuiting transfer type arc welding of the small current region, the output control of the control unit 18 is performed. DC power is supplied to the electrode 7 and the base metal 8 by driving the inverter 3 based on the above, and a short circuit and an arc are alternately generated between the electrode 7 and the base metal 8 at every welding cycle T.

[0009] The period of occurrence of this short circuit and arc is Tshor
Assuming t and Tarc, during those periods Tshort and Tarc, the control unit 18 uses the welding currents of the error amplifiers 14 and 15 and the output of the difference of the welding voltage from the reference value and the output of the timer 17 based on the discrimination result of the discriminator 16. By grasping the state, based on a preset control pattern, the output control amount is variably set in accordance with the occurrence of short circuit and arc, and the inverter drive unit 21 is controlled by the output setting signal according to this output control amount. Adjust the size and shape of at least one of welding current (output current) and welding voltage (output voltage).

By the way, an example of the control patterns of the welding current and the welding voltage is as shown in FIGS. 6 and 7. In these figures, the magnitudes Is, Ip1, Ip2 and the period Ts are four control elements (parameters) of the welding current, and the magnitude ΔV, the period Td, the inclination angle θ of the waveform, and the pulse waveform (wave shape) Vpulse are There are four control elements for the welding voltage.

The waveforms of the periods Td and Vpulse are timer 1
7 and the output of the generator 20, and the remaining magnitudes Is, Ip1, Ip2, ΔV and the angle θ are given in advance according to welding conditions and the like. Further, in FIG. 6, the solid line is a control pattern when an arc is actually generated by the arc transition, and the one-dot chain line is a control pattern when the arc is not generated even if the arc is retained for a certain period of time Ip1.

Further, as shown in FIG. 7, the welding voltage after the arc transition is controlled to the pulse waveform Vpulse only when the short circuit does not transit to the short circuit even after a certain period of time, so as to promote the transition to the short circuit.
Then, FIG. 8 shows an example of a control result when the welding current and the welding voltage are both controlled.

By the way, when the magnitude of the welding current is changed,
As shown in Fig. 9, the arc transfer forms are short-circuit transfer in the small current region and globular transfer in the medium current region.
r), and changes to spray transfer in the large current range. Note that FIG. 9 shows a change in the form of arc transfer under a certain condition, where SH is a short-circuit transfer region, G is a globule transfer region, and SP is a spray transfer region.

In the short-circuit transition area SH, 100%
Control is required, but control is completely unnecessary in the spray transfer area SP. Therefore, conventionally, as shown in FIG. 10, an appropriate welding current in the region G of the globule transition, for example, 23
With 0 (A) as the threshold value, the control amount is switched to 100% (degree of control 1.0) or 0% (degree of control 0) depending on the current or above.

[0015]

In the case of the conventional output control method of the gas shielded arc welding power source shown in FIG. 5, the welding current and the welding voltage are forward controlled by a so-called fixed function based on the set control pattern. , Each of the four control elements (Is, Ip1, Ip2, Ts) of the welding current and welding voltage as parameters of this function, (ΔV, Td,
(θ, Vpulse) must be set to an appropriate value by repeating trial welding a number of times while changing each, and there is a problem that extremely complicated parameter setting work is required.

Moreover, the set values of the respective control elements are usually halfway values that cover only a certain range of welding conditions, and do not cover the entire range. Therefore, an appropriate control element or a plurality of control elements, for example, the period Td must be finely adjusted during the actual welding work, and there is a problem that complicated adjustment is required during the work.

Further, since the state of the arc actually varies depending on various factors such as the composition of the components of the electrode 7, the torch moving speed during welding, the shape of the welded material forming the base metal 8, etc., the arc stability is stable. In order to enhance the stability, it is necessary to control the welding current and welding voltage in consideration of all of these factors, but in reality it is impossible to consider all of these factors, and the stability of the arc is There is a problem that it cannot be raised sufficiently.

Further, as shown in FIG. 10, the control amount 100%, 0
Since a simple alternative control of% is performed, there is a problem that appropriate control cannot be performed particularly in the region G of the globule transition of FIG. 9 in which the short-circuit transition and the spray transition are mixed.

An object of the present invention is to enable automatic control in real time to an optimum control state so as to stabilize the arc without performing the conventional complicated adjustment work, and to dramatically improve welding performance. To do.

[0020]

In order to achieve the above-mentioned object, in the output control method of the gas shielded arc welding power source of the present invention, the welding state analysis result based on the detected values of welding current and welding voltage Fuzzy inference is performed on the excess or deficiency of the output control amount based on the output control pattern, and the output control amount is corrected based on the result of the inference so as to enhance the stability of the arc.

[0021]

In the output control method of the gas shielded arc welding power source of the present invention configured as described above, the output control amount is obtained from the analysis result of the welding state obtained every moment, which is obtained from the detected values of welding current and welding voltage during welding. The excess or deficiency of is inferred by fuzzy reasoning, and the result of this inference automatically corrects the output control amount so as to improve the stability of the arc. Therefore, the output control amount is automatically adjusted in real time to the optimum amount in consideration of various factors by fuzzy inference during welding without performing the conventional complicated adjustment work before and during actual welding.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment will be described with reference to FIGS. 1 showing the device configuration is different from the conventional configuration in FIG. 5 in that a fuzzy inference unit 22 having an LSI and a microcomputer configuration is added.

The control unit 18 then controls the error amplifiers 14, 1
The welding state is grasped by the output of the difference of 5 and the output of the timer 17, and the output control amount is variably set in accordance with the occurrence of a short circuit and the occurrence of an arc based on a preset control pattern of, for example, FIGS. An output setting signal corresponding to the output control amount is supplied to the inverter control unit 21 to control at least one of welding current and welding voltage. At this time, the control unit 18 uses the result of the fuzzy inference by the inference unit 22 based on the analysis result of the welding state to increase the stability of the arc between the electrode 7 and the base metal 8 by controlling each control element Is, …, Vpu
The lse is adjusted to correct the output control amount.

Next, adjustment of each control element Is, ..., Vpulse based on the result of the fuzzy inference by the inference unit 22 will be described by taking the control element (period) Td as an example. Regarding the period Td, for example, the excess or deficiency is inferred from the period Tarc (arc time) of arc generation and the welding current.

Therefore, the control unit 18 constantly obtains the frequency distribution of the arc time as shown in FIG. 2 from the welding current and the welding voltage. Then, as shown in FIG. 2, 65 (msec) is the most frequent arc time. At this time, if the welding current is maintained at a constant value of 230 (A), the control unit 18 causes the inference unit 22
As information of the analysis result of arc time and welding current, 6
Information of 5 (msec) and 230 (A) is transmitted.

Further, the inference unit 22 is set with various membership functions required for inference of each control element, and the arc time is “long”, “slightly long” and the welding current is “significantly large” and the period Td is “long”. "Slightly short", "Slightly short"
When the membership function of is the shape shown in (a), (b) and (c), (d) and (e), (f) of FIG. The degree of excess or deficiency of the period Td is inferred by the minimum value synthesis (MIN synthesis) from the combinations of "long" and "significantly large" and "slightly long" and "significantly large" of the welding current.

That is, the suitability of "long" and "slightly long" of arc time 65 (msec) is set to 0.5 and 0.25, respectively, and the suitability of welding current 230 (A) at "reasonably large". Is 0.35, the shaded area in (e) of FIG. 3 is “substantially short” by the MIN composition of (a) and (c) in FIG.
Then, the shaded area in (f) of the figure is obtained as the range of the "slightly short" fitness of the period Td by the MIN composition of (b) and (d) of the figure.

Further, the shaded portions of (e) and (f) of FIG. 3 are combined by maximum value (MAX synthesis) to obtain the function shape of the shaded portion of (g) of FIG. 3, and the centroid method is applied to this function shape. It is applied and the degree (−0.7) at the position of the center of gravity is inferred as the degree of excess or deficiency of the period Td.

The inference result of the inference unit 22 is the control unit 1
8 and the degree of control element Td is -0.7,
The control pattern period Td of FIG. 7 is set so that this degree becomes 0.
Is adjusted to correct the output control amount.

By the way, the same inference as described above is executed for each of the control elements Is, ..., Vpulse.
Each control element Is,…, Vpulse of the control pattern of is adjusted. As a result of these adjustments being repeated during actual welding,
Real-time automatic correction during welding according to the welding state of the output control amount, which was not possible in the past, is possible, without repeating the trial welding before welding to determine each control element as before. Moreover, the gas shielded arc welding can be performed with the arc kept extremely stable without adjustment during welding.

Furthermore, in order to control the state of the arc by fuzzy reasoning, various known and unknown arcs such as the composition of the material of the electrode 7, the torch moving speed during welding, the shape of the welded material forming the base metal 8 and the like. Optimum correction is comprehensively taken into consideration without individually analyzing or detecting the fluctuation factors.

Therefore, it is possible to perform welding with extremely excellent characteristics by omitting the conventional complicated adjustment work before and during actual welding.
Welding performance is significantly improved.

In addition, the arc transition is shown in FIG. 9 according to the welding current.
Even when changing to short-circuit transition, globule transition, or spray transition, a membership function for area determination is prepared, and fuzzy reasoning is used to control the area within the area G of globule transition as shown by the solid line in FIG. It is possible to change the degree stepwise (continuously) and perform optimum control. Then, it can be applied to output control when controlling at least one of welding current and welding voltage.

The fuzzy reasoning method, membership function, etc. are not limited to those in the embodiment.

Further, although the inference unit 22 and the control unit 18 are configured separately from each other in the above-described embodiment, the inference unit 22 and the control unit 18 may be configured by one microcomputer or the like. Further, the inference unit 22 may be formed by a combination of a hardware logic circuit and an analog circuit.

[0036]

Since the present invention is configured as described above, it has the following effects. From the detected values of welding current and welding voltage during welding, the result of analysis of the welding state is obtained every moment, and the fuzzy inference of the output control amount is fuzzy inferred,
The output control amount was automatically corrected based on the result of this inference so as to improve the arc stability. Therefore, fuzzy inference during welding can be used to perform output without performing complicated adjustment work before and during actual welding. The control amount is automatically adjusted in real time to the optimum amount considering various factors, and the welding current,
The welding voltage can be controlled to an optimum value according to the welding state, and the welding performance can be dramatically improved.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of an output control method of a gas shielded arc welding power source of the present invention.

FIG. 2 is an arc time generation distribution diagram for explaining the control of FIG.

3A to 3G are explanatory diagrams of fuzzy reasoning based on the characteristics of FIG.

FIG. 4 is an explanatory diagram of changes in the control amount of FIG. 1 based on arc transfer.

FIG. 5 is a block diagram of a conventional example.

FIG. 6 is an explanatory diagram of a control pattern of welding current.

FIG. 7 is an explanatory diagram of a welding voltage control pattern.

FIG. 8 is a control characteristic diagram of welding current and welding voltage of a conventional example.

FIG. 9 is an explanatory diagram of arc transition.

10 is an explanatory diagram of changes in the control amount of FIG. 5 based on arc transfer.

[Explanation of symbols]

 7 Consumable Electrode 8 Welding Base Material 9 Current Detector 10 Voltage Detector 18 Control Section 22 Fuzzy Reasoning Section

Front page continued (72) Inventor Kunio Kano 2-14-3 Awaji, Higashiyodogawa-ku, Osaka City Sansha Electric Co., Ltd.

Claims (1)

[Claims] 1. A consumable electrode, at least one of a welding current flowing through a welding base material and a welding voltage is controlled in accordance with a set output control pattern, and between the gas shielded consumable electrode and the base material. In a power control method of a gas shielded arc welding power source for alternately generating a short circuit and an arc, the result of analysis of a welding state based on the detected values of the welding current and the welding voltage is used to determine whether the output control amount based on the pattern is excessive or insufficient. An output control method for a gas shielded arc welding power source, which comprises making an inference and correcting the output control amount so as to enhance arc stability based on the result of the inference.