JPS61115680A - Two-stage pulsed arc welding - Google Patents

Abstract

PURPOSE:To prevent generation of spatter surely, make droplets small particles and speed up welding by impressing the second pulse current before the first pulse current rises up and making the pulse current off by one pulse at the time of short circuit. CONSTITUTION:Before the first pulse current IP1 rises up, the second pulse current IP2 of larger peak is impressed. When welding is made by short arc length, droplets are separated by pinching force caused by the peak current IP2 by the high frequency pulse current before the wire short-circuits to the base metal to prevent generation of spatter. When short circuit is caused by the first pulse current IP1, the first and second pulse current IP1 and IP2 become off, and shift to base current IB. Thus, generation of spatter is prevented surely.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a consumable electrode type arc welding method, and more particularly to a pulsed arc welding method that prevents the generation of spatter.

Conventional technology Conventionally, when spatter occurs in consumable electrode arc welding, it adheres to the torch and deteriorates shielding performance, causing blow holes to occur, which can also cause equipment failure and worsen the working environment. is bringing about. Spatter occurs when the welding wire short-circuits with the base metal and the arc regenerates, and particularly occurs frequently when the current value during arc regeneration is large.

As a method for eliminating such spatter, a pulsed arc welding method in which a pulsed current is superimposed on a direct current welding current is widely used. According to this method, when an arc current is applied to a certain extent, the welding wire becomes constricted due to the pinch force of the generated arc, and when a pulse current is applied in this state,
The melting of the welding wire tip is accelerated, and the strong pinching force promotes the separation of the molten part of the welding wire tip. To explain this with a diagram, the arc current has a waveform as shown in FIG. In the figure, IP is the peak current and IB is the base current. When welding is performed using this arc current, as the value of the current (2) approaches IP in the state of the pulse waveform a, the arc A as shown in FIG. 4 occurs, and the welding wire W begins to melt.

When the current becomes I-IP with the pulse waveform S, the wire W
is squeezed by pinch force P. The constriction of the wire W further progresses in the state of the pulse waveform C, and the droplets separate from the wire W in the base current region of the pulse waveform d. In this way, according to the pulsed arc welding method, droplets can be separated smoothly, and by 1 drop/1 pulse, droplets can be made finer and short circuits can be prevented, and spatter can be prevented (for example, JP-A-56 -114580 Publication, 56-1655
Publication No. 64).

Problems to be Solved by the Invention However, when using this welding method to increase the pulse frequency to make the droplets finer, a short circuit occurs between the welding wire W, the base material, and the material before the droplets are separated. It became like this,
This causes spatter.

Further, as shown in FIG. 5, when welding is performed with a short arc length in order to increase the welding speed, the droplets do not separate even when the current reaches its peak value, making it easy to short-circuit, resulting in spatter.

An object of the present invention is to provide a pulsed arc welding method that enables finer droplets and faster welding speeds without causing spatter.

Means and Effects for Solving the Problems In order to achieve the above object, the first invention provides a two-step pulse waveform in pulsed arc welding in which arc welding is performed by superimposing a pulsed current on a basic welding current. , a two-stage pulsed arc welding method characterized in that a second pulsed current larger than the first pulsed current is applied before the first pulsed current falls. According to this welding method, the first
Since the strong pinching force of the second pulsed current is applied to the melted portion at the tip of the welding wire which has been constricted by the pinching force of the pulsed current, the droplets are reliably detached.

The second invention is a two-stage pulsed arc welding method characterized in that if a short circuit occurs due to the first or second pulsed current, the pulsed current is immediately turned off by one pulse. According to this welding method, if a short circuit occurs with the first or second pulse current, the pulse current is immediately turned off and restored to the base current, so the short circuit disappears and normal arc returns, and the next Shift to pulsed current.

EXAMPLES The present invention will be described in more detail with reference to Examples below. In the welding method according to the first invention, as shown in FIG.
Add I Ku-ryu■ to Beekmirsumi-ryu■, which becomes P2. As a result, as shown in Figure 2,
Even when welding with a short arc length using a high-frequency pulsed current, the pinch force caused by the peak current ■ causes the droplet to break off before the wire shorts to the base metal! 1 to prevent the occurrence of spatter.

FIG. 6 is an embodiment of a pulse current generating circuit in the welding method of the first invention. 1 is the rectifier, 2 is the peak current I
Similarly to the switching element for IIJtII, the switching element 4 is a switching element for controlling the peak current I, and the switching element 4 is a switching element for the base current IBIIIriJ, and the switching elements 2, 3.4 are transistors. 5
is the base current detector. The circuit including 6 to 13 and 15 to 21 is an output current control circuit. 14
is the output current detector.

22 is a welding part, 22a is a base metal, 22b is an arc, 22
c is a consumable electrode, 22d is a power supply chip, and 22e is a consumable electrode feeding roller.

The output current detection circuit 15 amplifies the detection signal of the total current 1a from the output current detector 14. The pulse current I signal generation circuit 13 receives signals from the detection circuits 157) to 157, a signal from the output current setting device 16, and a signal set by the output current setting device 16 and the peak current I signal generation circuit 18. Compare the two. As a result, the signal generation circuit 13 transmits the signal (peak signal IP1) for turning on and off the pulse current control switching element 3 to the peak/base changeover switch 8 so that the detected value of the total current 1a matches the set value. The pulse current I is then sent to the control transistor drive circuit 7. The switch 8 is a switch that is turned on only for a time t according to the pulse current time tP1 and the base current time tS set by the pulse frequency setter 17.

The peak N current I signal generation circuit 18 sends the signal (peak signal ■) set by the detection circuit 15 to the peak current 1 control transistor drive circuit 6 via the peak on/off switch 9. The switch 9 is operated by the pulse period circuit 19 to determine the peak current time (t) and base current time (t-B-tB+t) set by the pulse frequency setter 20 synchronized with the pulse frequency setter 17.
Pl is on only for tP2 hours according to -1 >
P2 is a switch.

The base current detection circuit 11 amplifies the base current detection signal from the base current detector 5, and the base signal generation circuit 12
The signal from the base current detection circuit 11 and the signal (base signal) from the base current setter 21 are passed through the base current control transistor drive circuit 10 through the tP and tB image periods.
to activate the base current control switching element 4.

In the welding method according to the second invention, if a short circuit occurs with the first pulse current, the first and second pulse currents are immediately turned off to return to the base current, thereby ensuring that spatter is not generated due to the short circuit. The pulse current is prevented from moving to the next pulse current.

FIG. 7 shows an embodiment of a two-stage pulse generation circuit having a short circuit detection and short circuit release control circuit according to the second invention. Components numbered 1 to 22 are the same as in FIG. 6, and their explanation will be omitted. The short circuit detection circuit 23 determines whether a short circuit has occurred based on the signal from the short circuit detector 24, and if a short circuit has occurred, generates a signal to turn off the peak current by one pulse at the changeover switch 8.9. The 1 pulse generation circuit 25 has a 1 pulse current 1 gQ regulator 2
When a short circuit signal is generated from the short circuit detector 24, the value set in step 6 is synchronized by the pulse period circuit 19, and one pulse is generated at the time of the base current and before the rise of the signal. Sending one pulse signal from the pulse generation circuit 25 to the peak current l control transistor drive circuit 27,
Transistor 28 is activated. At this time, the pulse waveform becomes as shown in Fig. 8, and the first pulse current I causes a short circuit S.
When this occurs, the first and second pulse currents are immediately turned off as shown in FIG. 8(b), and the current returns to the base current.

As described in detail, the first invention provides a pulse arc welding process in which the pulse waveform is a two-stage pulse, and before the first pulse current falls, a second pulse current larger than the first pulse current is applied.
Since this is a two-stage pulsed arc welding method in which a pulsed current of 100% is applied, it is effective in making the droplets finer and increasing the welding speed without causing spatter.

A second invention further provides a two-stage pulse welding method according to the first invention, which includes a step of turning off the pulse current by one pulse if a short circuit occurs due to the first or second pulse current.・Since it is an arc welding method, it has the effect of more reliably preventing the occurrence of spatter.

[Brief explanation of drawings]

1 and 2 are explanatory diagrams of the operation of the first invention, FIGS. 3 to 5 are explanatory diagrams of the operation of the conventional pulse arc welding method, and FIGS. 6 and 7 are explanatory diagrams of the operation of the conventional pulse arc welding method. A two-stage pulse generation circuit diagram of each embodiment in the second invention, and FIG. 8 is an explanatory diagram of the operation of the second invention. I...First pulse current (pulse current) 1...
・Second pulse current (peak current) IB...Base current king...Peak current time ■...1 pulse current time Applicant Hidehiko Okada, attorney at Toyota Motor Corporation! :D (1) Whale
taste

Claims (2)

[Claims] (1) In pulsed arc welding, in which arc welding is performed by superimposing a pulsed current on a basic welding current, the pulse waveform is a two-stage pulse, and before the first pulsed current falls, a second pulsed current larger than the first pulsed current is applied. A two-stage pulsed arc welding method characterized by applying pulsed current. (2) In pulsed arc welding, in which arc welding is performed by superimposing a pulsed current on the basic welding current, the pulse waveform is a two-stage pulse, and before the first pulsed current falls, a second pulsed current larger than the first pulsed current is applied. A two-stage pulsed arc welding method characterized in that a pulsed current is applied, and if a short circuit occurs due to the first or second pulsed current, the pulsed current is immediately turned off by one pulse.