JPH0299276A - Hot wire heating power source and hot wire welding procedure utilizing the same - Google Patents

Abstract

PURPOSE:To change the polarity of a hot wire heating current by an electrical means without changing the connection of a power cable and to convert it to AC by changing over a switch of a semiconductor switch circuit by an output control circuit. CONSTITUTION:When transistors Tr2 and Tr4 of the semiconductor switch circuit 10 are controlled to ON by the output control circuit 12 of a hot wire heating power source 7, the DC current of the positive polarity is obtained. In addition, when transistors Tr1 and Tr3 are controlled to ON, the DC current of the negative polarity is obtained. When the transistors Tr2 and Tr3 are then controlled to ON, an intermittent pulse current of the positive polarity is obtained and when the transistors Tr1 and Tr4 are controlled to ON, an intermittent pulse current of the negative polarity is obtained. Further, an AC current is obtained by turning the transistors Tr1 and Tr4, and Tr2 and Tr3 ON and OFF respectively and then, executing repeatedly switching to control the Tr2 and Tr3, and Tr1 and Tr4 to ON and OFF respectively.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a hot wire heating power source and a hot wire welding method using the same, and in particular to converting AC input into DC output and converting the DC output. The present invention relates to a hot wire heating power source suitable for electrically switching between positive and negative polarities and alternating current, and a hot wire welding method suitable for stably performing all-position welding using the power source.

[Conventional technology]

FIG. 4 is a diagram showing an outline of a commonly used hot wire TIG welding device.

The hot wire TIG welding apparatus shown in FIG. 4 includes a torch 1, a wire feeder 3 that feeds out a wire 2, and a TIG
It has a power source 4 and a hot wire heating power source 5. In addition, 6 is a base material.

In this hot wire TIG welding device, the wire 2 is also energized to generate heat, thereby compensating for the drawback of low efficiency while maintaining the high quality characteristic of TIG welding. A direct current power source is often used as the hot wire heating power source 5, and FIGS. 5 to 7 show the basic circuit configuration of a typical hot wire heating power source.

FIG. 5 is the most basic circuit, in which the rectified DC output is used as hot wire heating current. Figure 6 shows a power supply that can easily obtain intermittent DC pulse output by providing a bidirectional sirisk on the AC input on the primary side.It has better controllability than normal DC current, and can be easily controlled from wires. It is characterized by good workability because there is little arcing (see Japanese Patent Application No. 156253/1983). FIG. 7 shows a hot wire heating power supply using an inverter, which can easily obtain both DC output and intermittent pulse output.

By the way, in the case of hot wire TIG welding, the wire heating current and the arc current interfere, causing magnetic blowing of the arc.

FIGS. 8(a) to 8(d) schematically show the state of magnetic blowing depending on the polarity of the wire and the direction of welding progress.

In the cases of Fig. 8 (a) and (d), the arc is deflected in the direction of welding progress, so the molten pool tends to spread to the front, and in the cases of Fig. 8 (b) and (C), the arc is deflected in the direction of welding progress, and in the cases of Fig. 8 (b) and (C), it is opposite to the welding direction. Since the arc is deflected, the molten pool tends to spread to the rear side.

Therefore, when welding in the downward direction as shown in Fig. 9(a), it is better to deflect the arc backwards as shown in Figs. 8(b) and (c) so that the molten pool does not flow in advance.
This is advantageous from the viewpoint of preventing cold wrap defects and the like, as well as from the viewpoint of workability. On the other hand, when welding in the upward direction as shown in Figure 9(b), it is advantageous to deflect the arc in the advancing direction as shown in Figures 8(a) and (d) because the molten pool will not drip downward. It is.

Note that the cold lap defect is when a vortex flow occurs during downward welding, and the molten pool precedes the melting of the base material.
Refers to defects in which beets form on unmelted base metal.

However, in the hot wire heating power supply as shown in FIGS. 5 to 7, in order to change the polarity of the hot wire heating current, it is necessary to change the connection of the power cable each time.

Furthermore, in all-position welding of fixed pipes, the connection of the power cable cannot be changed, so it is impossible to change the polarity during welding, which results in poor workability and makes it difficult to obtain a sound weld. This is one of the reasons why hot wire TIG welding has not been widely applied for all-position welding.

[Problem to be solved by the invention]

In the prior art, each time the polarity of the hot wire heating current is changed, the power cable connection must be reversed. Further, since it is impossible to change the method during welding, it is difficult to apply the method when the welding position changes, such as in full-position welding of a fixed pipe, because dripping of the molten pool cannot be controlled.

A first object of the present invention is to provide a hot wire heating power source that can change the polarity of hot wire heating current by electrical means and convert it to alternating current without changing the power cable connection. A second object of the present invention is to provide a hot wire welding method that uses the hot wire heating power source to stably perform all position welding in any hot wire welding.

[Means for Solving the Problems] The first object is to provide a circuit that converts AC input to DC output, a semiconductor switch circuit that can switch the DC output to positive, negative polarity, and AC, and a This is achieved by including an output shaping circuit that switches the switch of the semiconductor switch circuit and changes the flow direction of the hot heating current.

The second object is to set the hot wire heating power source in all-position welding using a hot wire so that the polarity of the hot wire heating current is such that during downward welding, the arc is deflected by magnetic blowing in the opposite direction to the welding progress; This is achieved by switching the polarity to the opposite polarity when welding in the upward direction.

Furthermore, the second purpose is to switch the hot wire heating power source to an alternating current hot wire heating current when transitioning from downward direction to upward direction welding and from upward direction to downward direction welding. This can also be achieved by using a TIG power source as the welding power source to perform hot wire TIG welding, or by performing welding using a consumable electrode arc power source as the welding power source.

[Effect]

In the hot wire heating power supply according to the present invention, by switching the semiconductor switch circuit using the output control circuit, the DC output can be switched between positive and negative polarities, and can also be switched to AC.

Therefore, there is no need to take the trouble to reversely connect the power cables, and even during welding, the polarity of the DC output can be easily changed by electrical means to convert it to AC.

Further, in the hot wire welding method according to the present invention, the hot wire heating power source of the present invention is used, and when welding in the downward direction in all position welding, hot wire heating is performed such that the arc is deflected by magnetic blowing in the opposite direction to the welding progress direction. Since the polarity of the current is set to the opposite polarity when welding in the upward direction, cold lap defects can be eliminated, and welding in all positions can be performed stably.

In the hot wire welding method according to the present invention, an alternating current hot wire heating current is applied at the time of transition from downward direction to upward direction welding and at the time of transition from upward direction to downward direction welding in the all-position welding. Since the welding is carried out using the welding method, the influence of the magnetic blow of the arc can be eliminated, and therefore all-position welding can be performed more stably.

Furthermore, in the hot wire welding method according to the present invention, a TIG power source or a consumable electrode arc power source may be used as the welding power source (it is also effective for hot wire welding using these power sources as the welding power source). can do.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the basic circuit configuration of an embodiment of the hot wire heating power source of the present invention.

The hot wire heating power source 7 of the embodiment shown in FIG.
A commercial AC power supply 8, an inverter unit 9 that is a circuit that converts the AC input into DC output, an inverter control circuit 11 that controls this, and a semiconductor switch circuit 10 that switches the DC output to positive, negative polarity, and AC. and an output control circuit 12 that controls this.

The semiconductor switch circuit 10 is configured as a bridge circuit by transistors Tri to Tr4 that function as switches.

FIGS. 2(a) to 2(C) show waveforms of hot wire heating current that can be output by the hot wire heating power supply shown in FIG.

The output control circuit 12 of the hot wire heating power supply 7 controls the transistors Tr2 and Tr of the semiconductor switch circuit 1o.
4 is turned on, a positive polarity DC current as shown in FIG. 2(a) can be obtained, and the transistors Tri and T
By controlling r3 to ON, a negative polarity DC current can be obtained. Then, by controlling the transistors Tr2 and Tr3 to ON, an intermittent pulse current of positive polarity as shown in FIG. 2(b) is obtained, and the transistors Tri and Tr4 are turned on.
If controlled to N, an intermittent pulse current of negative polarity can be obtained. Furthermore, transistors Tri and Tr4 are turned on, and transistors Tr2 and Tr3 are turned off,
Next, by repeatedly controlling the transistors Tr2 and Tr3 to turn on and the transistors Trl and Tr4 to turn off, an alternating current as shown in FIG. 2(C) is obtained.

When the hot wire heating power source 7 is used for TIG welding, for example, and is a hot wire TIG, by changing the polarity of the hot wire heating current, the spreading direction of the molten pool as shown in FIG. 8 can be easily controlled. can be controlled.

FIGS. 3(a) and 3(b) show an embodiment of the hot wire welding method of the present invention, in which the hot wire heating power source shown in FIG. 1 is applied to TIG welding in all positions of fixed pipes. FIG. 3 is a diagram showing the relationship between torch position and the direction of hot wire heating current suitable for this torch position; Figure 3 (a
), the wire 2 is supplied from the front side in the welding direction. In the region A where welding is in the downward direction, the molten pool flows forward due to gravity, so the transistors Tr2 and Tr3 of the semiconductor switching circuit IO of the hot wire heating power source 7 shown in FIG. 1 are turned on. By controlling the hot wire heating current to be opposite to the TIG current,
The direction of magnetic blowing of the arc is controlled to be opposite to the direction of travel. This lowers the temperature on the front side (wire side) of the molten pool and prevents the molten pool from flowing forward due to gravity, which not only prevents cold wrap defects but also improves welding workability.

In region B, where welding occurs in the upward direction, the molten pool is held by surface tension, and there is no force acting on the molten pool to flow either to the front or to the rear in the welding direction. Therefore, the transistors Tr1 and Tr4 of the semiconductor switch circuit 10 are turned on.
At the same time, the transistors Tr2 and Tr3 are turned off, and the transistors Tr2 and Tr3 are turned on, and the transistors Tri and Tr4 are turned off. Make sure there is no such thing.

Further, in the region C where welding is performed in the upward direction, contrary to the region A, the transistors Tri and Tr4 of the semiconductor switch circuit 10 are turned ON, and the wire 2 is set as the negative electrode, and the TI
By making it the same as the G electrode, the arc is deflected towards the wire side. This can prevent the molten pool from hanging backward.

In this example, as shown in Fig. 3(b), the hot wire heating current is not a continuous direct current, but an intermittent pulsed current, which is because the pulsed current is less affected by magnetic blowing. This is because it is difficult to accept (and workability is improved).

The position at which the direction of the current is switched from positive to AC to negative may be determined by simply determining the angle, but it is
The state of the molten pool may be determined by monitoring with a camera, etc., and automatically changed.

A major feature of the hot wire welding method of the present invention is that the direction of the wire heating current can be changed during welding.
This is effective in welding in all positions, but if the position does not change during downward welding, there is no particular need to change the current direction.

However, if the polarity of the TIG electrode and wire are reversed and the wire separates from the base metal during welding,
In the hot wire heating power source as shown in FIGS. 6 and 7, the arc current flows around to the hot wire heating power source side even during the period when the wire is not energized, causing unnecessary wire heating.

In this respect, like the hot wire welding method of the present invention, the first
By using the hot wire heating power source 7 shown in the figure,
In this hot wire heating power supply 7, the transistor Tr L Tr of the semiconductor switch circuit 10 is
Since 4 is in a non-conducting state, the above-mentioned problems can be easily solved.

In addition, in the hot wire welding method of the present invention, T is applied to the welding power source.
It can be applied not only to those using an IG power source but also to those using a consumable electrode arc power source.

〔Effect of the invention〕

According to the invention described in claim (1) of the present invention described above, by switching the switch of the semiconductor switch circuit by the output control circuit, the DC output can be switched between positive and negative polarity, and furthermore, the polarity of the DC output can be changed to positive and negative polarity. Since it can be switched, there is no need to take the trouble to reversely connect the power cable, and the polarity of the DC output can be easily changed by electrical means even during welding, and it can also be converted to AC.

Further, according to the invention set forth in claim (2) of the present invention, the hot wire heating power source set forth in claim (1) is used, and in all-position welding, when welding in the downward direction, the arc is generated in the opposite direction to the welding progress direction. The polarity of the hot wire heating current is such that it is deflected by magnetic blowing, and the polarity is opposite when welding in the upward direction, which eliminates cold lap defects and allows stable all-position welding. There are benefits to be gained.

According to the invention described in claim (3) of the present invention, when transitioning from downward welding to upward welding and from upward welding to downward welding in all position welding,
Since welding is performed using an alternating current hot wire heating current, the influence of magnetic arc blowing can be eliminated, and therefore all-position welding can be performed more stably.

Furthermore, in the invention described in claim (4) of the present invention, a TIG power source is used as the welding power source, and in the invention described in claim (5), a consumable electrode arc power source is used. It can also be effectively applied to hot wire welding methods using these power sources.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the basic circuit configuration of a hot wire heating power source according to the present invention, and FIG. 2 (a), (b), (c)
is a diagram showing the waveform of the wire heating current obtained with the hot wire heating power supply shown in FIG. 1, and FIGS. 3(a) and (b) are
This figure shows an embodiment of the hot wire welding method according to the present invention, and shows the relationship between the torch position and the waveform of the hot wire heating current when the pot wire heating power source is used for TIG welding in all positions. Figure 4 shows the basic configuration of general hot wire TIG welding, Figures 5 to 7 show the basic circuit configuration of a conventional hot wire heating power source, and Figures 8 (a) to (d) A diagram showing the relationship between the molten pool and magnetic arc blowing depending on the wire insertion direction, welding progress direction, and wire polarity in hot wire TIG welding, FIG. 9 (a),
(b) is a diagram showing the upward direction and downward direction of the full-position TIG welding process. DESCRIPTION OF SYMBOLS 1... Torch, 2... Wire, 4... TIG power supply, 6... Base material, 70. , hot wire heating power supply, 8.
...Commercial AC power supply, 9...Inverter section, 10...
Semiconductor switch circuit, Tri to Tr4...transistor, 11...inverter control circuit, 12...output control circuit. Patent applicant Pubcock Hitachi Co., Ltd. Agent Patent attorney Takeshi Kawakita: Hot wire heating power source: Inverter control circuit: Output control circuit: Hot wire heating power source: Commercial AC power source: Inverter section two-semiconductor switch circuit: Inverter control circuit: Output Control circuit diagram (a) (b) (d)

Claims (5)

[Claims] (1) A circuit that converts AC input into DC output, a semiconductor switch circuit that can switch the DC output to positive, negative polarity, and AC, and a hot heating current that switches the semiconductor switch circuit during welding. and an output control circuit for changing the flow direction of the hot wire heating power source. (2) In all-position welding using a hot wire, the hot wire heating power source is set to a polarity of hot wire heating current such that the arc is deflected by magnetic blowing in the opposite direction to the welding progress when welding in the downward direction, and when welding in the upward direction. A hot wire welding method that is characterized by switching the polarity to the opposite polarity during welding. (3) The hot wire heating power source is switched to an alternating current hot wire heating current for welding when transitioning from downward direction to upward direction welding and when transitioning from upward direction to downward direction welding. The hot wire welding construction method according to claim (2). (4) Use a TIG power source as the welding power source, and use hot wire TI
Claim (2) or (3) characterized in that the method is G welding.
) hot wire welding construction method. (5) The hot wire welding method according to claim (2) or (3), wherein welding is carried out using a consumable electrode arc power source as the welding power source.