JPS5825871A - Arc welding machine - Google Patents

Abstract

PURPOSE:To unify setting of welding conditions and select adequate conditions by providing a setter for welding current, a signal converter for welding voltage, a detector for welding voltage, control circuits for pulse and base voltages, and a converter and a control circuit for wire feed speed. CONSTITUTION:The material of base metals and the diameter of a wire are set with a switch 24, and an adequate current value is set with a setter 14 for welding current, thereafter a welding machine is started. Then the voltage signal Vi from the setter 14 is converted to a welding voltage signal Ve and a wire feed speed signal Vf. The signal Ve is distributed to a pulse voltage control signal and a base voltage control signal, which are applied to respective regulators 7 and 8. Since the signal for the average value of the welding voltage of an electric power source 6 is fed back from a detector 16 for welding voltage, the average value is controlled to a constant value determined by the set current. The wire feed speed is also controlled to the constant value determined by the set current value with a control circuit 21. When the set current value changes, the three factors; pulse voltage, base voltage and wire feed speed, change as well in follow up said change, whereby always adequate conditions are selected.

Description

DETAILED DESCRIPTION OF THE INVENTION In order to transfer droplets by spraying with relatively low heat input, the present invention uses a wire feeding motor to send a welding voltage in which a pulse voltage is periodically superimposed on a base voltage at a substantially constant speed. The present invention relates to an improvement of an arc welding machine used for arc welding (hereinafter referred to as pulsed arc welding) in which an electric current is applied between a supplied welding wire and a base metal.

The main factors that determine the welding conditions for pulsed arc welding are:
Pulse voltage, base voltage, wire feed motor setting device, base voltage setting device, and wire feed speed setting device were each provided independently, but it is now possible to independently change these three types of factors to obtain the appropriate welding conditions. Detailed experience is required to make a decision, and in particular, the pulse voltage requires a voltage waveform with a narrow pulse width and a high pulse peak value from the viewpoint of weldability9, so the setting is extremely delicate. It is.

To reduce the trouble of setting such conditions.

Some welding machines set the base voltage to a constant value in stages, and then change two factors, pulse voltage and wire feed speed, within this range to determine the welding conditions. The three factors of pulse voltage, base voltage, and wire feed speed each have appropriate values depending on the welding current (average value), so if the base voltage is set to a constant value in stages, the appropriate welding conditions can also be set in stages. You can only get it.

In view of the above points, the present invention centralizes the setting of conditions for pulsed arc welding so that appropriate welding conditions can be easily and continuously selected, and furthermore feeds back the average value of welding voltage to adjust the pulse voltage and base voltage. The present invention aims to provide an arc welding machine that is capable of performing stable welding even in the face of camera shake of the welding torch and other disturbances by controlling the related art.

° Droplet transfer phenomenon in pulsed arc welding.

At a certain critical value of the average welding current (hereinafter referred to as the critical welding current value), the appearance becomes somewhat different.

When the welding current is below the critical welding current value, the welding wire 1 is preheated and the droplet grows in the base voltage section 4 of the welding voltage waveform 3, as shown in FIG. The droplet 2 separates from the wire 1 and spray transfer occurs without shorting between the wire and the base material.

In a large current range exceeding the critical welding current value, spray transfer can occur without applying a pulse voltage, but by applying a pulse voltage, droplet growth can be suppressed and droplet transfer in fine particles can be promoted. In this case, since the pulse voltage acts auxiliary, no large output is required when the welding current is below the critical welding current value.

From the above, under appropriate welding conditions for pulsed arc welding, the following relationship is established between the welding current (average value), the peak value of the pulse voltage, and the average value of the base voltage. That is, the peak value of the pulse voltage is the critical welding current value I. The average value of the base voltage has a nearly proportional relationship with the welding current value (see FIG. 3).

Furthermore, in pulsed arc welding in which the welding wire is fed at a substantially constant speed, the welding current and the wire feeding speed have a substantially proportional relationship as shown in FIG.

Furthermore, when looking at the average value of the welding i pressure obtained by adding the pulse voltage and the base voltage, it has a substantially proportional relationship to the welding current (average value) as shown in FIG.

In this way, the six factors that determine the welding conditions of pulsed arc welding, including one-pulse electric field, penis voltage, and wire feed speed, can all be expressed as a function of the welding current as a parameter, and the relationship between them is It varies depending on the material □ wire diameter, type of shielding gas, etc. This can be expressed as an experimental formula as follows.

The peak value of the pulse voltage is V, (V)', the average value of the base voltage is V, (V), the wire feeding speed is fW Cm'm
in ” Let the welding current (average value) be I (A') and the welding voltage (average value) be ■8 [■].

When using iron wire (1,2 mmφ) (shielding gas Ar
+20%0O2) VP Connie, 00062I2+0.251' I +1
2.5v = Q, 0001 I2+0.0024I+1
3.6V ='0.04 I+19 fW=1,79e0006■ 1'-e - When using Mg wire (1.2mmφ) (shielding gas Ar) V--0,00058I2+0.244I+10.3- VB: 0. 059 I +14.3 V =0.0'425 I+ 14.9fW=0.05
2 I-0,078 The present invention was made based on the above considerations and experimental results, and will be described in detail below with reference to FIG. 6.

In Fig. 6, 6 generates a welding voltage by superimposing a pulse voltage (25 to 500 Hz in terms of pulse frequency) on the base voltage, and is configured so that the base voltage and Norms voltage can be adjusted independently. It is a welding power source. This welding power source itself is publicly known, and the figure schematically shows an example in which a pulse voltage output regulator 7 and a base voltage output regulator 8 (eg, a thyristor) are provided separately, but a transistor is used as a control element. By using this, it is also possible to adjust the pulse voltage output and the base voltage output with the same element. The welding wire 1 is fed at a substantially constant speed by a feed roller 1o driven by a wire feed motor 9, and a welding arc is created between the welding wire 1 and the base metal 12, which are energized through the contact tip 11. 16 is generated.

Reference numeral 14 denotes a welding current setting device, which is composed of a podensimeter and the like that outputs a voltage signal v2 corresponding to a set current value. 15 inputs the voltage signal V.

A welding voltage signal converter converts this into a welding voltage signal ve and outputs it, and the relationship between input voltage and output voltage is a linear amplifier that corresponds to the relationship between welding current ■ and welding voltage va as shown in Figure 5. A welding voltage detector 16 outputs a voltage signal corresponding to the average value Va of the welding voltage generated from the welding power source 6, and the output signal is fed back to the summing point 17, and the welding voltage is used as a reference input. signal V
compared to

18 is a feedback signal from the welding voltage detector 16 and a welding voltage signal V; A control signal is generated corresponding to the deviation from A pulse voltage control circuit that controls the output of the device 7.

19 generates a control signal corresponding to the deviation between the feedback signal from the welding voltage detector 16 and the welding voltage signal ve, so that the average value VB of the base voltage during the steady break is the third with respect to the set value of the welding current ■. A base voltage control circuit that controls the output of the base voltage output regulator 8 so as to have a predetermined relationship as shown in the figure.

These control circuits 18.1.9 are constituted by an analog arithmetic circuit including a function generator, a microcomputer, or the like.

Reference numeral 20 denotes a wire feed speed signal converter, which also includes a function generator and the like, and converts the input voltage signal V into a wire feed speed signal Vf and outputs the signal.

The relationship between the input voltage and the output voltage corresponds to the relationship between the welding current ■ and the wire feeding speed fw as shown in Figure 4.
, 21 feeds the wire at a speed corresponding to the wire feeding speed signal fW so that the wire feeding speed fw in a steady state has a predetermined relationship as shown in FIG. 4 with respect to the setting value of the welding current machine. This is a wire feeding speed control circuit that rotates the motor 9. If necessary to stabilize the wire feeding speed, the output signal from the wire feeding speed detector 22 is added to the summation point 26.
The wire feeding speed control circuit 21 may be operated based on the deviation between this feedbank signal and the wire feeding speed signal vf as a reference input. The wire feeding speed detector 22 is.

Simply, it is configured to detect the restart voltage of the wire feeding motor 9 and output it as a signal corresponding to the wire feeding speed.

24 is an analog or digital switch for setting the base material material, wire diameter, type of shielding gas, etc. This switch controls the welding voltage signal converter 15. Pulse voltage control circuit 18. Base voltage control circuit 19. Select the relationship of the wire feed speed signal converter 200 Å output. Like a dedicated welding machine, the base material, wire diameter, and type of shielding gas are specified.

In this case, the switch 24 can be omitted. in this case,
Depending on the signal level of the voltage signal (2), it may be used as is as the welding voltage signal ve.

When performing pulse arc welding using the welding machine configured as described above, the switch 24 is used to set the base material material, wire diameter, type of shielding gas, etc., and the welding current setting device 14 is used to set the base material plate thickness, opening, etc. When you start the welding machine after setting the appropriate current value determined by the tip shape, etc., the welding current setting device 14
The voltage signal vL from is the welding voltage signal V. and wire feed speed signal f.

■Converted into welding voltage signal. is further distributed into a pulse voltage control signal and a base voltage control signal corresponding to the set current value, and the pulse voltage output regulator 7. A pace voltage output regulator 8 is provided.

When a welding voltage is generated from the welding power source 6, a signal corresponding to the average value va of the welding voltage is fed from the welding voltage detector 16 to the summing point 17. Therefore, in a steady state, the average value Va of the welding voltage is As shown in Figure 5, the peak value of the pulse voltage is controlled to a constant value determined by the set current value.■1
．． The average value VB of the pace voltage has a predetermined correlation with the set current value, as shown in FIGS. 2 and 6, respectively. Further, the wire feeding speed fw is also controlled by the wire feeding speed control circuit 21 to a constant value determined by the set current value, as shown in FIG.

When the set current value changes, the pulse voltage, base voltage, and wire feed motor pressure factor also change accordingly, so that welding is always performed under appropriate welding conditions.

Next, considering the case where the arc length increases due to camera shake of the welding torch and the welding voltage increases, welding voltage detector 1
6 detects the rise in the welding voltage and feeds it back, and immediately controls the pulse voltage output regulator 7. It works to lower the output of the base voltage output regulator 8, so the welding voltage decreases and returns to a stable steady value. This reduction in welding voltage forcibly reduces the welding current, which has the effect of further speeding up recovery of the relative bare arc length when relying only on the self-control action of the arc due to power supply characteristics. A similar correction function also works when the welding voltage drops below a steady value. Moreover, looking at the relationship between the pulse voltage and the base voltage in this transient state, as mentioned above, the peak value of the pulse voltage etc. and the average value VB of the base voltage change in accordance with the input voltage of each control circuit 18 and 19. Therefore, as shown in Figures 2 and 3, when the input voltage of the control circuits 18 and 19 is small (when the welding voltage and current are decreasing), the dependence of the welding voltage on the pulse voltage decreases. When the input of control circuit 18 and 19 is large (
When the welding voltage and current tend to increase), the dependence of the welding voltage on the base voltage increases. Therefore, the pulse voltage and base voltage are controlled to maintain a predetermined correlation so that a stable arc condition can be obtained even in a transient state.Furthermore, the wire feeding speed is detected as shown in Figure 6. By adding a control system that feeds back to the input side of the wire feeding speed control circuit 21, when the wire feeding speed decreases due to an increase in the resistance of the wire feeding path, the input voltage of the wire feeding speed control circuit 21 can be adjusted. becomes relatively large,
Since the rotation speed of the wire feed motor 9 is increased and the wire feed speed is returned to a stable steady value, the arc state can be further stabilized. If the wire feeding speed is controlled to be constant in this way, when the control function that reduces the welding voltage in response to the elongation of the arc works as described above, the wire feeding speed will transiently change from the steady state. The welding current is also higher than the welding current, but this works to promote recovery of the arc length. The same applies when the arc length becomes short.

According to the configuration of the present invention explained above, the following effects can be obtained. The six speed factors are automatically controlled to appropriate values, so even beginners can easily set the conditions for russ arc welding, which previously required considerable experience.

(2) Since the three factors of pulse voltage, base voltage, and wire feeding speed can be changed continuously according to the set current value, the optimal arc condition is always maintained over a wide range from small electric power range to large current range. ’ can be used for welding.

(6) By adjusting the average value of the welding voltage, the welding voltage can be controlled at a constant value while maintaining the correlation between the pulse voltage and the base voltage so that a stable arc condition can be obtained even in a transient state. Stable welding is possible even in the face of torch shake and other disturbances.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing the relationship between welding voltage waveform and droplet transfer.
Fig. 2 is a curve diagram showing the relationship between welding current and the peak value of Norkulls voltage under appropriate welding conditions, and Fig. 6 is a curve diagram showing the relationship between welding current and the average value of base voltage under appropriate welding conditions. Fourth
Figure 5 is a curve diagram showing the relationship between welding current and wire feed speed under proper welding conditions, Figure 5 is a curve diagram showing the relationship between welding current and average welding voltage under appropriate welding conditions, and Figure 6 is a diagram showing the relationship between welding current and wire feed speed under appropriate welding conditions. FIG. 1 is a block diagram showing an embodiment of the invention. 1. Welding wire 6: Welding power source 7 Pulse voltage output regulator 8: Base voltage output regulator 9: Wire feed motor 12: Base material 13: Welding arc 14: Welding current setting device 15: Welding voltage signal converter 16: Welding voltage detector 18: Pulse voltage control circuit 19: Base voltage control circuit 20: Wire feed speed signal converter 21: Wire feed speed control circuit Attorney Junnosuke Nakamura 4'1 Figure 2 Figure 3

Claims (1)

[Claims] Generates a welding voltage by superimposing a pulse voltage on the base voltage,
Using a welding power source configured so that its base voltage and noggle voltage can be adjusted independently, a welding arc is generated between the welding wire fed at a constant speed and the base metal. In an arc welding machine, there is a welding current setting device that outputs a signal corresponding to the set current value, and a welding voltage signal converter that outputs a welding voltage signal' that has a predetermined relationship with the output signal from this welding current setting device. a welding voltage detector that outputs a signal corresponding to the average value of the welding voltage generated from the welding power source, and a welding voltage detector that outputs a signal corresponding to the average value of the welding voltage generated from the welding power source; A pulse voltage control circuit and a base voltage control circuit that control the generated pulse voltage and base voltage so that they have a predetermined correlation, and a wire feeding speed signal converter that outputs a wire feeding speed signal having the relationship shown in FIG. An arc welding machine with one feature.