JPH05200555A - Nonconsumable electrode arc welding method and equipment - Google Patents

Abstract

PURPOSE:To prevent the unmolten wire tip from thrusting base metals by stopping the feed of a filler wire when the filler wire feed is started and the wire comes into contact with the base metals and restarting the wire feed after the wire melts in an arc formation part. CONSTITUTION:An arc is formed between a nonconsumable electrode 1 and the base metals 2. The filler wire 5 is fed to the arc formation part 10 by a filler wire feed motor 7. When the filler wire 5 comes into contact with the base metals 2, a filler wire contact detection circuit 11 with the base metals detects this and the filler wire feed motor 7 is stopped. When the tip of the filler wire 5 comes into contact with the arc formation part 10 and melts, it separates from the base metals 2. The contact detection circuit 11 detects this and driving of the feed motor 7 is restarted to feed the filler wire 5 at a set feed rate. There is no fear of the filler wire 5 tip thrusting the base metals 2 at the time of starting welding and welding work is started normally.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to welding, and more particularly to feeding a filler wire to a welding site.

[0002]

2. Description of the Related Art FIG. 10 shows the construction of a welding apparatus that has been generally used as a hot wire TIG welding method. An arc power source 34 is connected to the non-consumable electrode 32 and the base material 33 in the TIG welding torch 31 to form an arc in an argon shield gas. Filler wire 36 for welding
Is guided from the filler wire feeder 37 through the conduit 38 and the contact tip 39 connected to the conduit 38 to the arc forming portion 35 to be brought into contact with the base material 33. The contact tip 39 and the wire heating power source 40 are connected, and a direct current or an alternating current is passed through the filler wire 36 to generate Joule heat, thereby increasing the melting rate of the filler wire 36. In the case of cold wire TIG welding in which the filler wire 36 is not electrically heated, it can be said that the wire heating power source 40 of FIG. 10 is excluded.

By the way, as shown in FIG. 11, the filler wire 36 is 3 m away from the non-consumable electrode 32 forming an arc.
When the TIG torch 43 is configured so as to feed the molten pool 42 approximately parallel to each other at a distance of about m, the size of the entire torch including the wire feeding portion can be made very compact.

[0004]

In the above prior art, as shown in FIG. 12 (a), the base wire 33 of the filler wire 36 is fed to the welded portion at a low initial speed (for example, at a constant initial speed). 0.5-1.0 m / min),
When the filler wire 36 came into contact with the base material 33, the filler wire was raised to a regular filler wire feeding speed. Electrode 32 at this time
If the arc current to the line rises to a normal value with the start of the filler wire feeding as shown by the line (a) in FIG. 12 (b), the filler wire 36 becomes as shown by the line (b) in FIG. 12 (b). In some cases, an initial current having a small value is applied until the base material 33 comes into contact with the base material 33, and when the filler wire 36 comes into contact with the base material 33, an electric current having a normal value may be applied.

At this time, as shown in FIG. 13 (a), when the filler wire 36 comes into contact with the base metal 33, for example, when the arc current is small as in thin plate welding, the base metal 3
Since the area of the molten pool 42 above 3 is also small, the tip of the filler wire 36 adheres to the end of the molten pool 42. And the base material 3
As shown in FIG.
Alternatively, when the base material 33 starts moving, the filler wire 3
The filler wire 36, which is fixed adjacent to the torch 31, remains connected to one point on the base material 33 without melting, and the welding operation cannot be started. When the arc current is small and the area of the molten pool 42 is too small, the tip of the filler wire 36 cannot reach the molten pool 42 on the base material 33, and the tip of the filler wire 36 pokes the unmelted base material 33. So-called "stucking" occurred and normal welding work could not be performed.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a welding method and apparatus capable of reliably supplying a filler wire to a base metal molten pool at the start of welding work and starting normal welding work.

[0007]

The present invention adopts the following basic structure in order to achieve the above object. In a non-consumable electrode arc welding method of feeding a filler wire to an arc forming portion between a base material and a non-consumable electrode, and welding a base material by supplying a current synchronized with the supply of the filler wire to the non-consumable electrode, a filler wire is fed. When the filler wire starts to contact the base material and the filler wire is temporarily stopped,
After the tip of the filler wire has melted in the arc forming part,
A non-consumable electrode arc welding method that starts the movement of the welding torch or the base material to carry out the welding of the base material and sends the filler wire to the arc forming part at the regular set filler wire feeding speed, or the arc power supply, A non-consumable electrode connected to an arc power source, a filler wire guided to an arc forming portion between the base material and the non-consumable electrode, and a filler wire feeding device for feeding the filler wire to the arc forming portion between the base material and the non-consumable electrode. In the welding apparatus including, a filler wire feeding speed control device for controlling the speed of feeding the filler wire from the filler wire feeding device to the arc forming part, and a filler wire feed-controlled by the filler wire feeding speed control device. A filler wire base material contact detection device for detecting contact with the base material in the arc forming part is provided, and the filler wire feed rate control device is provided. Starts the supply of the filler wire at a predetermined initial speed, and once the filler wire base material contact detection device detects contact of the filler wire with the base material, the supply of the filler wire is once stopped, and then the filler wire base material contact detection device. When the tip of the filler wire is melted by the arc and it is detected that the filler wire has separated from the base metal, the welding torch or base metal starts moving to perform welding of the base metal and The welding device has a function of restarting the supply of filler wire at a set speed.

[0008]

When the welding is started, the arc current is started to flow to the non-consumable electrode, and at the same time, the feeding of the filler wire toward the arc forming portion is started. At this time, the filler wire slowly starts feeding at a predetermined initial speed, and once the filler wire comes into contact with the base material, the filler wire feeding is temporarily stopped. While the supply of the filler wire is stopped, the molten pool is formed on the base material by the arc from the non-consumable electrode and the tip of the filler wire is also melted. Then, the filler wire base metal contact detection device detects that the filler wire has separated from the base metal, so the welding torch or base metal starts moving to carry out the welding of the base metal, and here the filler wire is fed at the normal feed rate. To send.

Thus, even if only a small weld pool is formed due to the small arc current, the tip of the unmelted filler wire sticks to the base metal at the start of welding, or the filler wire tip is connected to a point on the base material. It will not be done.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a TIG welding machine according to this embodiment and its control device. T
An arc power source 3 is connected to the non-consumable electrode 1 and the base material 2 of the torch of the IG welding machine to form an arc in the argon shield gas. The filler wire 5 for welding is fed to the arc forming portion 10 on the base material 2 by the filler wire feeding motor 7. In FIG. 1, a non-consumable electrode 1 and a base material 2 are controlled by an arc power source 3 whose current is controlled by an arc current control circuit 9.
During that, an arc is formed. The filler wire feed amount control signal forming circuit 12 includes a filler wire 5 detected by a filler wire base material contact detection circuit 11 described in detail later.
A detection signal of contact or non-contact with the base material 2 is output. The contact of the filler wire 5 with the base material 2 is detected.

On the other hand, the filler wire 5 is fed to the arc forming portion 10 on the base material 2 by the filler wire feeding motor 7 whose rotation speed is controlled by the filler wire feeding motor rotation speed control circuit 6. Further, as will be described later in detail, the filler wire base material contact detection circuit 11 detects whether or not the filler wire 5 contacts the base material 2 based on the filler wire terminal voltage Vw. The detection signal is output to the filler wire feed amount control signal forming circuit 12 to control the feed speed of the filler wire 5. The detection signal of the filler wire base material contact detection circuit 11 is also output to the torch or base material movement control circuit 13 via the filler wire feed amount control signal forming circuit 12 to control the movement of the torch or base material. Be seen. Further, the control signal of the arc current control circuit 9 is also output from the filler wire feed amount control signal forming circuit 12.

Further, the filler wire base material contact detection circuit 11
JP-A-62-192265 discloses in detail, as shown in FIG. 3, from the zero-cross signal forming circuit 14 of the filler wire terminal voltage Vw and the commercial power supply voltage when the filler wire is not energized (in the case of the hot wire method). The zero cross signal of the filler wire terminal voltage sample and hold circuit 15
And the filler wire terminal voltage Vw is sampled and held. The filler wire terminal voltage Vw is approximately 0 V as shown in the section a in FIG. 4 in a state where the filler wire 5 is in contact with the base material 2 to be energized and heated and welding is proceeding stably. Then, when the filler wire is separated from the base material, a negative voltage from -1 V obtained by contacting the plasma of the arc and a part of the power supply voltage are applied (in the case of the hot wire method), as shown in section b of FIG. Since it becomes a voltage, it becomes a voltage more negative than -1V. Therefore, the voltage of -1 V formed by the reference voltage setting circuit 16 and the output voltage of the sample hold circuit 15 of the filler wire terminal voltage Vw are output to the comparison circuit 17 and are compared. Then, if the output voltage of the sample hold circuit 15 is a voltage more negative than -1V, it is determined that the filler wire 5 is separated from the base material 2. If the output voltage of the sample hold circuit 15 is a voltage on the positive side of -1V, it is determined that the filler wire 5 is in contact with the base material 2. The result of the base material contact detection of the filler wire 5 is output to the filler wire feed amount control signal forming circuit 12. The filler wire terminal voltage Vw is usually detected between the contact tip 19 and the base material 2, but may be detected from the output terminal of the filler wire heating power source (in the case of the hot wire method).

FIG. 6 shows the arc current control circuit 9. The arc current value setting circuit 51 adjusts the output voltage of the reference power source 50 on the basis of the signal from the filler wire feed amount control signal forming circuit 12 to obtain the control voltage corresponding to the initial current of the arc current or the regular set current. Output to the arc power supply 3.

FIG. 7 shows a filler wire feeding motor rotation speed control circuit 6. The motor rotation speed command signal from the filler wire feed amount control signal forming circuit 12 and the actual motor rotation speed detection signal from the motor rotation speed detection circuit 63 are compared by the comparison circuit 62, and a signal corresponding to the deviation is used for the motor. Output to the motor drive circuit 61 of the power supply 60. The motor drive circuit 61 controls the electric power supplied to the filler wire feeding motor 7 based on the signal from the comparison circuit 62. The motor rotation speed detection circuit 63 generates a signal proportional to the rotation speed of the filler wire feeding motor 7.

FIG. 8 is a detailed explanatory diagram of the filler wire feed amount control signal forming circuit 12. Based on the signal from the filler wire base material contact detection circuit 11, the filler wire feed amount setting circuit 70 controls the rotation speed command values corresponding to the initial speed, the stop speed, and the normal speed of the filler wire feed motor rotation control. Output to the circuit 6. Also, based on the signal from the filler wire base material contact detection circuit 11, the arc current initial current period, normal current period signal generation circuit 71
The arc current control circuit 9 determines whether the arc power supply 3 is currently in the initial current output period or in the regular current output period.
Output to. Further, the filler wire base material contact detection circuit 1
Based on the signal from 1, the torch or base material movement start signal generation circuit 72 outputs to the torch or base material movement control circuit 13 whether the movement period or the stop period is present.

FIG. 9 shows a torch or base material movement control circuit 13
FIG. Based on the movement period and stop period signals from the torch or base material movement start signal generation circuit 72, the motor drive circuit 81 supplies the output of the motor power supply 80 to the torch or base material movement motor 82 during the movement period. The motor 82 is rotated, and in the stop period, the supply is stopped and the motor 82 is stopped.

FIG. 2 is a diagram showing an arc current and a filler wire feeding speed with time (filler wire feeding amount) in the apparatus of FIG. The arc power supply 3 is supplied with a rather low continuous current called a start current for a short time after the arc starts (line (d) in FIG. 2B).
reference). Of course, as shown by the line (c) in FIG. 2B, an arc current having a regular set value may be applied at the same time as the start of the arc. Since the base material 2 may be melted and a through hole may be formed before it is supplied, a slightly lower current is applied at the start of welding to melt the filler wire 5 as shown by the curve (d) in Fig. 2 (b). It is preferable to start a regular arc current when starting.

The driving of the filler wire feeding motor 7 is started at the same time when the arc current is supplied. First, the filler wire 5 is driven.
Starts feeding toward the arc forming portion 10 of the base metal at a predetermined initial speed lower than the normal set feeding speed during welding.
Then, when the filler wire base material contact detection circuit 11 detects that the tip of the filler wire 5 contacts the base material 2, the filler wire feeding motor 7 is stopped. At this time, even if the tip portion of the filler wire 5 in the arc forming portion 10 is welded using a weak arc current value,
Melts if you touch the arc for a while. At this time, when the tip portion of the filler wire 5 melts, the filler wire 5 separates from the base material 2. The separation of the filler wire 5 from the base material 2 is detected by the filler wire base material contact detection circuit 11. The detection signal indicating that the filler wire 5 is not in contact with the base material 2 is a signal forming circuit 1 for controlling the filler wire feed amount.
2, the control signal is output from the circuit 12 to the filler wire feeding motor rotation speed control circuit 6, and the driving of the filler wire feeding motor 7 is restarted. The filler wire feeding motor 7 feeds the filler wire 5 at a set feeding speed required for normal welding work. Thus, there is no possibility that the tip of the filler wire 5 will hit the base material 2 at the start of welding, and the welding operation can be started normally.

The detection signal of the filler wire base material contact detection device in which the filler wire 5 is not in contact with the base material 2 is passed through the filler wire feed amount control signal forming circuit 12 to the torch or base material movement control circuit 13. The movement of the torch or the base metal is started from this time, so that the tip of the unmelted filler wire as shown in FIG. 13 (b) is dragged to the torch while being attached to the base metal. It disappears.

This embodiment is particularly effective when only a small weld pool is formed due to the small arc current. Although the present embodiment has been described using the hot wire type TIG welder, the present invention is also applicable to hot wire type and cold filler wire type non-consumable electrode arc welders. Further, the present invention can be applied not only to the welding machine in which the non-consumable electrode and the filler wire of FIG. 13 are integrated in the torch, but also to the non-consumable electrode arc welding machine of the type shown in FIG. 10 in which the filler wire is attached separately from the electrode.

[0021]

According to the present invention, the tip of the unmelted filler wire does not hit the base material at the start of welding, or the filler wire is not connected to one point on the base material, and the welding operation can be started normally. In particular, it is particularly effective when only a small weld pool is formed because the arc current is small. In this way, the welding performance is improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a time course of an arc current and a filler wire feeding speed in one embodiment of the present invention.

FIG. 3 is a filler wire base material contact detection circuit diagram of an embodiment of the present invention.

FIG. 4 is a wire terminal voltage waveform diagram when the filler wire of one embodiment of the present invention is in contact with the base material and welding is proceeding stably.

FIG. 5 is a wire terminal voltage waveform diagram when the filler wire of one embodiment of the present invention is separated from the base material.

FIG. 6 is an arc current control circuit diagram of an embodiment of the present invention.

FIG. 7 is a circuit diagram of a filler wire feeding motor rotation speed control circuit according to an embodiment of the present invention.

FIG. 8 is a signal forming circuit diagram for controlling a filler wire feed amount according to an embodiment of the present invention.

FIG. 9 is a torch movement control control circuit diagram of an embodiment of the present invention.

FIG. 10 is a schematic view of a hot wire TIG welding apparatus.

FIG. 11: T integrating a filler wire and an arc electrode
It is a principal part explanatory drawing of an IG welding apparatus.

FIG. 12 is a diagram showing the timing of the arc current and the filler wire feeding method of the prior art.

FIG. 13 is a diagram illustrating a defect of TIG welding according to the related art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Non-consumable electrode, 2 ... Base material, 3 ... Arc power supply, 5 ... Filler wire, 6 ... Filler wire feeding motor rotation speed control circuit, 7 ... Filler wire feeding motor, 9 ... Arc current control circuit, 10 ... Arc Forming unit, 11 ... Filler wire base material contact detection circuit, 12 ... Filler wire feed amount control signal forming circuit, 13 ... Torch or base material movement control circuit

Claims (2)

[Claims] 1. A non-consumable electrode arc welding method in which a filler wire is fed to an arc forming portion between a base material and a non-consumable electrode, and a base material is welded by flowing a current synchronized with the feed of the filler wire to the non-consumable electrode. In order to perform welding of the base metal after the supply of the filler wire is started and the filler wire comes into contact with the base metal, the supply of the filler wire is temporarily stopped and the tip of the filler wire is melted in the arc forming part. A non-consumable electrode arc welding method, characterized in that the welding torch or the base metal is started to move and the filler wire is fed to the arc forming part at a regular set filler wire feeding speed. 2. An arc power source, a non-consumable electrode connected to the arc power source, a filler wire guided to an arc forming part between the base material and the non-consumable electrode, and an arc formation between the base material and the non-consumable electrode. And a filler wire feeding device for feeding the filler wire to the arc forming part, and a filler wire feeding speed control device for controlling a speed of feeding the filler wire from the filler wire feeding device to the arc forming part, and the filler wire feeding speed. A filler wire base material contact detection device that detects that the filler wire controlled by the controller has contacted the base material in the arc forming portion, and the filler wire feed speed control device feeds the filler wire at a predetermined initial speed. After the start, the filler wire base material contact detection device detects the contact of the filler wire with the base material, and once the filler wire is fed. After that, the filler wire base metal contact detection device detects that the filler wire has separated from the base metal due to melting of the tip end of the filler wire by the arc, and in order to perform welding of the base metal, welding is performed. A welding device having a function of starting the movement of the torch or the base metal and restarting the filler wire feeding at a regular set speed.