JPS60180675A - Consumable electrode type pulse arc welding method - Google Patents

Abstract

PURPOSE:To shift molten metal in the state of small lump without stopping a large quantity of molten metals at the tip of a wire, and to stabilize the arc preventing generation of spatter by changing speed of feeding of the welding wire in synchronization with the period of pulse current. CONSTITUTION:In consumable electrode type pulse arc welding, the welding wire 12 is melted by a welding arc 21 and forms molten metal 12a. The molten metal 12a is accumulated at the tip of the wire 12, and at the same time, the wire 12 is fed toward an object to be welded 14. At this time its current value increases. From this state, the feeding speed of the wire 12 is reversed. That is, the wire 12 is shifted in the direction going away from the object to be welded 14, and the molten metal 12a is separated and shifted forcibly by inertia. As force of inertia due to change of feeding speed of the wire is given to the molten metal 12a in addition to pinch effect of pulse peak current, sure separation and shifting are made from the state of small lump. Accordingly, a beautiful bead free from welding defect can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a consumable electrode type pulsed arc welding method that prevents welding and produces a beautiful weld bead.

The conventional consumable electrode type pulse arc welding method is carried out using a T-structure shown in FIG. In Fig. 1, ■ is a welding l/-ch, 2 is a welding wire, 3 is a wire reel, 4 is a workpiece, 5 is a pulse welding power source, 6 is a motor, and 7 is a wire directly connected to the motor 6. 8 is a holding roller, and 9 is a motor drive current.To explain these functions, since the motor 6 rotates at a constant speed set by the motor drive power source 9, the wire feed roller 7 and The welding wire 2 is fed from the wire reel 3 through the welding torch 1 toward the workpiece 4 at a constant speed by the holding roller 8. In this case, the voltage applied from the pulse welding power source 5 is applied to the welding torch 1. As a result, an arc is generated between the tip of the welding wire 2 and the workpiece 4 as a result of the voltage being applied to the welding wire 2 through the contact tip etc. inside the welding torch 1. Welding is performed by partially melting and solidifying the welding wire 2 and the object to be welded.

FIG. 2 shows the welding state (A) and the characteristics of pulsed welding current (B) by this welding.

In Fig. 2 (A), the tip of the welding wire 2 shown in an enlarged view is shown melting and detaching as time elapses from (al to (1)). In this figure, the unit of time is the welding current and the wire diameter. Each unit interval is about 2 mseO, although it varies depending on the situation.In Fig. 2, 2 is the welding wire, 4 is the material to be welded, 2a is the molten metal at the tip of the welding wire 2, 10 is the welding arc, and 2b is the flight The molten metal 2C is the molten metal J2d on the surface of the material to be welded 4. Also, Fig. 2(B)
The figure shown in Figure 2 shows the temporal change of the pulse current in correspondence with the movement of the molten metal shown in Figure 2 (A), and the horizontal axis (:
L time (L), the vertical axis shows the current value (11). In FIG. 2, the welding wire 2 is melted by the welding arc 10,
Forms molten metal 2a, but at pulse peak current l;3
The molten metal 2a rapidly increases (I)), receives a pinching effect due to the strong pulse peak current flowing through the molten metal itself, and is pushed out toward the workpiece and moves away, as shown in (C). .

However, the state of occurrence of an arc point at the tip of the welding wire 2,
Due to the influence of the state of the current raw cotton in the molten metal 2a, the molten metal 2a has a normal pinch effect! As a result, the transfer to the FBI is often unsuccessful, as shown in (f). In this case, a large amount of molten metal accumulates at the tip of the welding wire 2, and when it comes into contact with the workpiece 4 as shown in (h) or when the molten metal 2 separates as shown in Since the spatter 2d is generated, the arc 1
0 becomes unstable. For this reason, the appearance of the welding bead is damaged by the scattered spatter 2d, and significant welding defects occur in the molten metal 1.

In view of the two drawbacks, the present invention is a consumable electrode type that does not allow a large amount of molten metal to remain at the tip of the welding wire, but reliably transfers the molten metal in the form of small lumps, and stabilizes the arc without generating spatter. The purpose is to provide a pulse arc welding method.

In order to achieve this object, the present invention is characterized in that the feeding speed of the welding wire is changed in synchronization with the pulse current cycle.

3 and 4 show an embodiment of the invention.

In FIG. 3, 11 is a welding 1-ch, 12 is a welding wire, 13 is a wire reel, 14 is a workpiece, 15 is a pulse welding power source, 16 is a motor, and 17 is a wire feeder directly connected to the motor 16. 18 is a holding roller, 19 is a motor and a driving power source, and 20 is a wire feeding speed control device which is connected to the pulse welding power source 15 for control. Voltage from the pulse welding power source 15 is applied between the welding wire 12 and the object to be welded 14 through the welding torch 11, and a welding arc is generated between the two, but as the ear 12 melts during welding, the wire From the reel 13 to the wire feeding roller 17
It is fed by a restraining roller 18. The motor 16 directly connected to the wire feed roller 17 is powered by a motor drive power source 1.
9, the motor and drive mJ power supply 19 are
Since it is controlled by the wire feeding speed control device 20, it is possible to synchronize the wire feeding with the pulse current change to perform repeated increasing/decreasing feeding, 1ljr continuous feeding, forward/reverse repeating feeding, etc.

The trend of molten metal at the tip of the welding wire 12 when the wire feeding speed is synchronized with the pulse current change is shown together with the change in the wire feeding speed and the pulse current change, where 12 is the welding wire; 14 is an object to be welded, 21 is a welding arc, and 12a is a molten metal. The diagram in FIG. 4(B) shows the change in pulse current, and the diagram in FIG. 4(C) shows the change in wire feeding speed in response to the movement of the molten metal 12a in FIG. 4(A). The horizontal axis of the diagram in FIG. 4(B) shows the time elapsed (tl), and the vertical axis shows the current value (1).The horizontal axis of the diagram in FIG. 4(C) shows the time elapsed (tl, the horizontal axis shows the The wire feeding speed (vl) indicates forward rotation and θ means reverse rotation.

Now, the welding wire 12 is melted by the welding arc 21 to form the molten metal 12a, but in (al, (bl), the molten metal 12a is deposited on the tip of the welding wire 12, and at the same time the welding wire 12 is sent toward the workpiece 14. In this case, the current value is increasing at (bl).

Next, in (C), although the current value increases, the wire feeding speed 1v1 is reversed, that is, the welding wire 12 moves in the direction away from the workpiece 14, so the molten metal 12a is forcibly separated and transferred due to inertia. .

According to the present invention, as shown in Part B, in addition to the pinch effect of the pulse peak current, inertia force is applied to the molten metal due to changes in the wire feeding speed, so that MLL detransition can be more reliably performed in the form of small lumps. ), the arc 21 is stabilized without generating spatter, and a beautiful bead without welding defects can be obtained.

[Brief explanation of drawings]

Figures 1 and 2 are examples of conventional pulse arc welding methods, and Figure 1 is IF! Figure 2 (A) is a diagram showing the state of the tip of the i8 solder, Figure 2 (B) is a graph showing the current one-hour characteristics, and Figures 3 and 4 are examples of the present invention. Fig. 3 is a tF7 diagram, Fig. 4 (A) is a state diagram of the tip of the welding wire, (B) is a graph showing the current one-hour characteristic, (
C,) is a graph showing the wire feeding speed versus time. In the figure, reference numeral 11 indicates a welding device 1--, 12 a welding wire, 12a a molten metal, 14 an object to be welded, 15 a pulse welding power source, 20 a wire, an ear feed speed control device, and 21 an arc. Patent applicant: Mitsubishi Heavy Industries, Ltd. Patent attorney: Shibu Mitsuishi (and 1 other person)

Claims (1)

[Claims] A consumable electrode type pulse arc welding method characterized by changing the feeding speed of welding wire in synchronization with the pulse current cycle.