JPS606277A - Pulsed arc welding method with consumable electrode - Google Patents

Abstract

PURPOSE:To start arcing in a satisfactory condition free from deposition and scattering in pulsed arc welding with a consumable electrode by inputting the electric power in the arc start period with higher pulse current in shorter time so as to have the same value as the average value of welding current. CONSTITUTION:A command circuit 1 commands a base current power source BPS, a wire feed circuit WF and a pulse current control circuit 3 to start welding upon turning on of a welding start switch PB1 and at the same time a pulse current switch circuit 2 passes the pulse current which has a high pulse current value, short duration time and the same value as the average value of the welding current by the instruction from a start pulse setting circuit 7. A time limiting circuit TM is actuated by the detection DT for starting welding and after a specified time, a pulse signal switch circuit SW switches a pulse setting circuit 8 during welding to continue welding. Since the start input has the same value as the value of the input during welding, the sure arc starting is accomplished without deposition and scattering by melting of the electrode chip.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD This invention relates to improvements in arc starting for consumable electrode pulsed arc welding.

Conventional technology In the gas-shielded arc welding method, which involves welding a consumable electric pole (hereinafter referred to as wire) by pressing @ryuzono-ryu, wire material, wire diameter (hereinafter referred to as wire diameter), shielding gas composition, etc. Unless a current is applied for 1 m above the minimum current value (hereinafter referred to as critical current value) at which spray transfer is possible, which is determined by E.g., droplet transfer from the tip of the molten wire will not be stable and good welding results will not be obtained. Therefore, if the current value of the direct current Ichihara (hereinafter referred to as base Ki current) with relatively few ripples that flows through the wire is less than the critical current value, spray transfer is performed by superimposing a pulse current on the base current described above. This stabilizes the arc and yields good welding results. However, in such a pulsed arc welding method in which a pulsed current is superimposed, stabilization of the arc at the start of welding (hereinafter referred to as arc start) is more difficult than in an arc welding method in which spray transfer is performed without superimposing a pulsed current. Failure to generate and sustain an arc results in welding defects at the arc start position.

Therefore, as a conventional method to improve arc start,
For a few seconds from the start of welding (hereinafter referred to as arc start period), compared to during steady state welding, ■ Increase the peak value Ip of the pulse current, ■ Increase the duration Tp of one pulse of the pulse current. , ■ Set the frequency f of the pulse city gf to dog, ■ Make the external characteristics of the pulse 'AI' f flow closer to the constant pressure characteristic than the vertical F characteristic, ■ Increase the base current value Ib, ■ Methods such as consolidation have been proposed in IP.

However, in all of these conventional methods, because the average value of Ichihara during the arc start period 1111 is higher than during welding, the wire melting speed during the arc start period is higher than the wire slope speed during welding. growing. therefore,
These Tp, Tp, f during the arc start period
, If the setting 1141'Bj to make Ib smaller than during steady welding is even slightly longer, the arc length will become longer and a burnback phenomenon will occur in which the wire and the pole tip are welded together. However, if the heat input is a little too large, the tip of the wire melts and scatters, resulting in poor arc starting.The appropriate setting time range is narrow, making selection difficult.

Object of the Invention The present invention provides a consumable electrode pulse arc welding method that enables a good arc start without increasing the average value of the linear current applied during the arc start period compared to the average value during welding. The goal is to propose a method.

SUMMARY OF THE INVENTION The present invention provides a method in which the average value of the current applied during the arc start period is set to approximately the same value as the average value of the current during steady state welding, and the pulse current applied during the arc start period is The peak value of is made larger than that during welding, the duration of one pulse is made shorter than that during welding, and the pulse current is passed for a preset time, for example, 0.1 seconds to 1 second, after detecting the welding current. This is a consumable electrode arc welding method in which steady-state welding is started after the arc is stabilized by cooling.

-Example 1- Hereinafter, an example of the welding method of the present invention will be described with reference to the drawings. In consumable electrode pulsed arc welding,
Once the wire material, wire diameter, shielding gas composition, etc. are determined, the peak current value (hereinafter referred to as peak value) Ip[A] of the pulse current and the duration of one pulse (hereinafter referred to as duration) are determined to obtain good welding results. time) Tp [ms
] There is an appropriate range σH between . Figure 1 shows that the wire material is aluminum alloy 5183 and the wire diameter is l.
, 5 (mm) in welding in argon gas, is a diagram showing the relationship between the peak value IP [:A,] (vertical axis) and the duration Tp (horizontal axis). In the same figure, in the area below the hatched part, the pulse current is too small, so the period of movement of the droplet detached from the tip of the molten wire cannot follow the period of the pulse current, and the droplet movement occurs. It is an @ area that becomes irregular,
On the other hand, in the region above the hatched portion, the pulse current is too large, so the arc length becomes excessive, and good welding results cannot be obtained in either region. The hatched part in the same figure indicates that the relationship between the peak value Tp (A) of the Valsbo flow and the continuous time j1ηTp [ms] is within an appropriate range, so that droplet transfer occurs regularly and good welding results are obtained. I can do it.

Next, the peak value Tp (A) of the pulse current at the hatched part where a good welding result can be obtained and the duration Tp [:m
Consider how the relationship with s) affects the arc start. The hatched part in the figure is the empirical formula (I
P) 2.4.Tp - A range shown as constant, within this range, when the peak value Ip is large and continues, a short pulse current of 1 TP is generated. For example, the pulse M it at position A and the peak value Ip are A small pulse current with a long duration Tp, for example, a pulse current at position B, is shown by a solid line labeled A and a dotted line labeled B in FIG. 2, respectively. The pulse current of symbol A and the pulse regulation of symbol B both have an average current of the same value of Ia shown by the dashed-dotted line. A case will be described in which a pulse pattern in which these two average values are equal is applied to the present invention.

In the present invention, as shown in FIG. 3, during the predetermined arc start period of 0, 1 to 1.0 seconds after welding is started and the welding current starts flowing, the peak value indicated by the symbol A is A case is shown in which a pulse current with a large Ip and a short duration Tp is applied, and then it is switched to a pulse Km with a small peak value Ip and a long duration TP, indicated by the symbol B. The pulsed current during the arc start period and the pulsed current during steady-state welding have the same average value Ta, but the pulsed current shown by symbol B and the pulsed current shown by symbol B have different peak values and durations. In addition, the pulse frequency ρU number also differs.

Next, the reason will be explained. Base heavy flow value II
) = 30 CAI, average current value Ia = 100 [A]
, peak value at the position of code A 1pa - 400 [A), peak value at the position of code B 1pb = 300 [A:I,A
Pulse current at a point, duration time Tpa = 1 (mS)
Then, the duration of the pulse current at point B is TP I)
[m s ] is 1”pl)=T from the above-mentioned experimental formula.
pa (Tpa / TPb)”=IX(400/3
00) = 2 [:ms:I. Therefore, the code A
And the frequencies Fa and Fb of the pulse frequency at the position indicated by symbol B are Tav = Fa - Tpa (Ipa - Tb) + Th and Iav = Fb - Tpl) (Ipt) - Tb) +
1b, respectively Fa”” 190 [:Hz
) and Fb=130 [Hz].

Under these conditions, when the wire E comes into contact with the workpiece W, a short-circuit current flows and melts. At this time, the N magnetic pinch caused by the short-circuit DC current flowing into the wire is the square of the peak value Ip. It depends on the product Ip2·Tp of and the duration TP. Therefore, the pulsed fermentation flow having the waveform shown by the sign A with a large IP has a better start. Furthermore, the pulsed direct current having the waveform shown by the symbol A has a higher pulse frequency and a higher probability that the pulsed current will be applied immediately after the wire contacts the workpiece, resulting in a better start.

Next, the fourth figure shows a configuration diagram of one welding device for implementing the welding method of the present invention. In the figure, 1 is a welding start/end command circuit (hereinafter referred to as a command circuit) that outputs a welding start signal and a welding end signal by means of a welding start switch PB1 and a welding end switch PR2, and PPS is a pulse heavy current obtained by rectifying a commercial AC power source. 2 is a pulse current switch circuit that controls the pulse current using a semiconductor control element such as a transistor; 3 is a pulse current control circuit that outputs a pulse m flow control signal to the pulse current switch circuit 2; 4 is a flywheel. Diode, 5 is a DC reactor, BPS is a base current supply power supply that is controlled and rectified from commercial AC power supply,
7 is a start pulse setting circuit that sets the peak value and duration of the pulse current during the arc start period, 8 is the welding pulse setting circuit that sets the peak value and duration of the pulse current during steady state welding, and SW is the start A pulse signal switching circuit 10 switches the output signal of the pulse setting circuit 7 or the welding pulse setting circuit 8, and 10 is a pulse frequency setting signal and a pulse frequency peak value and duration setting signal output from the pulse signal switching circuit SW. This is a pulse signal synthesizing circuit that synthesizes the signals, determines pulse conditions, and supplies the output signal to the pulse current control circuit 3. Further, E is a wire, W is a workpiece to be welded, A is an arc generated between the wire E and a workpiece W, M is a wire feed motor, WF is a wire feed control circuit, DT is a welding current detection circuit, TM is a predetermined value of 0.1 to 0.1 after the output signal of the welding current detection circuit is input.
This is a time limit circuit that outputs a signal that switches the pulse signal switching circuit SW after one second.

Next, the operation of the apparatus for carrying out the welding method of the present invention will be explained. When the welding start switch PBl of the command circuit 1 is pressed, a welding start signal is supplied from the command circuit 1 to the base positive current supply power source BPS, the pulsed DC control circuit 3, and the wire feed control circuit WF, and the wire is E is fed, the tip of the wire contacts the workpiece W, and a welding current flows through the wire E from the base current supply power source BPS and the pulse current supply power source PPS. At this time, the pulse current output from the pulse current switch circuit 2 is controlled by the signal output from the start pulse setting circuit 7.
It has a waveform determined by the peak value Ipa and the duration Tpa indicated by reference numeral A in FIG. Further, when the welding current flows, a welding current detection signal is supplied from the welding current detector DT to the timer circuit TM, and the timer circuit TM starts a timer operation.

During this time period, that is, the arc start period Ts, the wire tip melts and an arc is generated between the wire tip and the workpiece W, and the arc length is in a steady state according to the melting speed of the wire tip determined by the welding type flow value. A stable arc can be obtained as the value approaches the value during welding. When the time limit circuit TM outputs a signal after the predetermined time period in which this stable arc is obtained ends, the pulse signal switching circuit SW outputs the output signal of the welding pulse setting circuit 8 to the pulse signal synthesis circuit 10. . At this time, the pulse current output from the pulse current switch circuit 2 is adjusted to the peak value Ipb shown in FIG. 3B by the signal output from the welding pulse setting circuit 8.
It has a waveform determined from the duration Tpb and the duration Tpb.

Next, we will discuss a conventional welding method that does not change the pulse current between arc start and during welding, and a welding method of the present invention that uses the device shown in Fig. 4 to switch the pulse current between arc start and welding. An example is shown below. An aluminum alloy 5183 wire with a wire diameter of 1.5 mm was used to weld the aluminum plate, and the average welding current was 180 mm.
[A], when welding with an arc voltage of 22 [V], the conventional welding method, for example, peak value lp - 330 [A] at arc start and during welding, duration TP = 1.5
When starting an arc by superpausing a pulse current of (ms), the arc cannot be started with a single contact between the wire tip and the aluminum plate, so-called arc start failures occur 20 out of 50 times. Ta. On the other hand, even if the aluminum plate, wire, average current, and arc voltage are the same, the welding method of the present invention shown in FIG.
50 [A], when continuing ffi”P-1, Q [ms]
The pulse current is super hosed to start the arc, and the TS starts from the time the wire tip contacts the aluminum plate.
= 0.4 C seconds], the pulse current is changed to the steady-state peak value lPb - 300 [A], and the duration TP b = 1.5
When switching to [ms:], arc start failure occurred only 2 out of 50 times, confirming the effectiveness of the welding method of the present invention.

Furthermore, during the arc start period hTs in which the peak value Ipa is larger than that during welding and the pulse current with a short duration Tpa is applied at the time of arc start shown in FIG. It is desirable to make Ts small as the flame rise increases, and conversely, the smaller Ipa is, the thicker Ts is to stabilize the arc at start. As described above, the arc start period Ts varies depending on welding conditions such as the peak value of the pulse current, duration, wire diameter, wire material, compatibility with the workpiece, and shielding gas composition, but within the normal practical range. T
s = about 0.1 to 1.0 [seconds].

Effects of the Invention The present invention makes the peak value Ip of the pulse current, which is commonly used during the arc start period, larger than the value during welding in a steady state,
In the process of improving the arc start by making the duration Tp of one pulse shorter than that during welding, the average value of the 2-digit number of currents energized during the arc start period and the average value of the current during welding are set to approximately the same value. Therefore, even if the preset arc start period Ts is too long, the arc length will become too short and a burnback phenomenon will occur where the wire and electrode tip are welded together, or the heat input will be too large and the wire tip will melt. There is no scattering, the arc starts reliably, and the welding result at the welding start part is also good.

[Brief explanation of the drawing]

Figure 1 shows the duration T of one pulse of pulse current when pulsed arc welding is performed using aluminum alloy wire.
A diagram showing the appropriate range (hatched area) between p [ms) (horizontal axis) and peak value Ip [A] (vertical axis). Figure 2 shows the pulse current at the position of symbol A in the hatched area in Figure 1. A diagram showing the waveform (solid line), the waveform of the pulse current at the position of symbol B (dotted line), and the average current value Ia (dotted chain line) of these pulse currents. A diagram showing the relationship between the pulse current waveform A, the pulse current saving waveform B during welding, and the average current value Ia (dotted chain line), and FIG. 4 shows an example of an apparatus for carrying out the welding method of the present invention. FIG. PPS...Pulse military power supply BPS...Base current supply power supply 7...Start pulse setting circuit 8...Welding pulse setting circuit SW...Pulse signal switching circuit Ts...Arc start period IPa...Peak value of pulse current during arc start period Tpa...Duration time of pulse current during arc start period Tpb...Peak value of pulse current during welding Tpb...
・Duration of pulse current during welding Representative Patent Attorney Medium
Hiroshi I (151 Fig. 1-4-Tρ (ms) α□ 1-t

Claims (1)

[Claims] 1. In a consumable electrode pulse-start arc welding method for welding by supplying a base current and a pulse current to a consumable external electrode and a workpiece, a predetermined arc start period when the welding amount is During welding, the average value of the current is the same as that of the current, and the peak value of the pulsed current is higher than that during welding.
A consumable electrode pulse arc welding method that welds by applying a pulsed current with a short pulse duration.