JPH0349827Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a DC pine seam welding machine, and more specifically to a DC power supply device that supplies DC power to a rotating disk electrode.

[Conventional technology]

FIG. 5 is a schematic configuration diagram showing a power supply section of a conventional DC pine seam welding machine, and FIG. 6 is a configuration diagram showing a clamper section of the same welding machine.

In the figure, 1 is a DC power supply, 2 is two secondary conductors connected to the DC power supply 1, 3 is an upper conductor connected to the end of one secondary conductor 2, and 4 is another secondary conductor. A lower conductor is fastened to the end of the secondary conductor 2, 5 is an upper rotating disk electrode fastened to the upper conductor 3, and 6 is a lower rotating disk electrode fastened to the lower conductor 4. 7 is a shear disposed near the secondary conductors 2, 2, 8 is an inlet clamp, 9 is an outlet clamp, and 10 is a welded strip.

FIG. 7 is a circuit diagram of a conventional DC power supply device for a DC pine seam welding machine. In the figure, 11 is a transformer, the primary side of which is connected to an AC power source 12. 13 is a full-wave rectifier circuit connected to the secondary side of the transformer 11, and its output side is connected to the secondary conductors 2, 2. Reference numeral 14 denotes two thyristors connected in parallel with opposite polarities, which are provided between the primary side of the transformer 11 and the AC power source 12, and function as a switch.

A conventional DC pine seam welding machine is configured as described above. For example, by firing the two thyristors 14, 14 of the DC power supply 1, the transformer 11 is excited by the AC power supply 12, and the full-wave rectifier circuit is activated. The DC current is rectified into direct current at step 13 and flows through the secondary conductor 2 . This direct current flows through the upper conductor 4 to the upper rotating disk electrode 6, the superimposed strips 10, 10, the lower rotating disk electrode 6, the lower conductor 4, the secondary conductor 2, and the strips 10, 10.
When it flows, it generates heat and performs welding.

[Problem that the invention attempts to solve]

In the conventional DC pine seal welding machine as described above, the DC power supply 1 is only provided with one full-wave rectifier circuit 13 on the secondary side of one transformer 11. Therefore, the polarity of the rectified direct current is never reversed. Therefore, when direct current is applied from the DC power supply 1 to weld the strips 10, 10, the secondary conductors 2,
A large direct current necessary for welding flows through the secondary conductor 2, and magnetic materials such as the shear 7, the inlet clamp 8, and the outlet clamp 9 near the secondary conductors 2 and 2 are magnetized by the magnetic flux passing through them. Ru. Therefore, the magnetic materials such as the magnetized shear 7 and the inlet and outlet clamps 8 and 9 attract iron powder and pieces of iron floating in the atmosphere, and when cutting the tip of the strip 10, the blade surface of the shear 7 Missing, input and exit clamps 8, 9
There was a problem in that the strip 10 was damaged when clamped.

This invention was made to solve this problem, and it is a DC pine seam welding machine that prevents the magnetic materials such as the shear and the inlet and outlet clamps from attracting iron powder and iron pieces floating in the atmosphere. The purpose is to obtain.

[Means for solving problems]

The DC pine seam welding machine according to this invention is connected to two transformers whose primary sides are connected in parallel to an AC power source, and to the secondary sides of the two transformers.
It was configured to include a DC power supply device consisting of two full-wave rectifier circuits whose output sides are connected with opposite polarities, and a changeover switch that alternately switches the connection between the primary sides of the two transformers and the AC power supply. It is something.

[Effect]

In this device, alternating current power is alternately supplied to two transformers by switching a changeover switch, and two full-wave transformers are provided corresponding to each transformer, and the output side polarities are connected to each other in reverse. Since the rectifier circuit is also operated alternately to reverse the polarity of the direct current flowing through the secondary conductor, the residual magnetic flux does not have a coercive force even if the magnetic material near the secondary conductor is magnetized.

〔Example〕

Fig. 1 is a circuit diagram showing an embodiment of this invention, Fig. 2 is a perspective view showing the core of the transformer, Fig. 3 is an explanatory diagram showing an inverted DC current waveform, and Fig. 4 is energizing the secondary conductor. FIG. 3 is an explanatory diagram showing the direction of magnetic flux when

In the figure, the same components as those in the conventional example are given the same reference numerals as those in the conventional example, and the explanation of the redundant components will be omitted.
11a is a first transformer, 11b is a second transformer, and the primary sides of the transformers 11a and 11b are connected in parallel to an AC power source 12. These first and second
As shown in FIG. 2, the cores 15 of the transformers 11a and 11b have a five-legged core structure, and the structure is integrated and simplified, and the primary winding of the first transformer 11a,
The secondary winding and the primary and secondary windings of the second transformer 11b are separately insulated. 13a is a first full-wave rectifier circuit connected to the secondary side of the first transformer 11a, and 13b is a second full-wave rectifier circuit connected to the secondary side of the second transformer 11b. The output sides of these first and second full-wave rectifier circuits 13a and 13b are connected so that the polarities are opposite to each other, and are connected to the secondary conductors 2, 2 by sharing the DC output terminal 16. Reference numeral 14a indicates two first thyristors connected in parallel with opposite polarities, which are provided between the primary side of the first transformer 14a and the AC power supply 12, and which function as a switch. Reference numeral 14b indicates the primary side of the second transformer 14b. Two second thyristors are provided between the AC power source 12 and the AC power source 12 and are connected in parallel with opposite polarities to each other and function as a switch.

In the DC pine seam welding machine configured as described above, first, the two first thyristors 14
a, 14a, the first transformer 1
1a is excited, and the DC current rectified by the first full-wave rectifier circuit 13a connected to the secondary side of the first transformer 11a is transmitted to the upper rotating disk via the secondary conductor 2 and the upper conductor 3. It flows through the electrode 5 strips 10, 10, the lower rotating disk electrode 6, the lower conductor 4, and the secondary conductor 2. At this time, a branch current tries to flow from the center tap of the second transformer 13b, but the two second
Since the thyristors 14b and 14b are not ignited, the internal impedance of the second transformer 11b is at a high level, and most of the DC current is transmitted to the upper and lower conductors 3 and 4, that is, the upper and lower rotating disk electrodes, at a current similar to the excitation current. It flows to 5 and 6.

Next, when reversing the polarity of the DC current,
By firing the two second thyristors 14b, 14b, it acts in the same manner as above, and most of the direct current is now passed through the secondary conductor 2, the lower conductor 4 to the lower rotating disk electrode 6, the strip 10, 10, it flows to the upper conductor 3 and the secondary conductor 2, and the polarity of the DC current is reversed. The inverted DC current waveform W of this DC current is as shown in FIG. Such reversal of the polarity of the DC current is caused by the first thyristor 14 when welding.
This can be done by alternately switching the ignition of the thyristors 14a, 14a and the second thyristors 14b, 14b.
b, 14b serves as a changeover switch.

Further, the reversal of the polarity of the direct current results in the reversal of the magnetic flux near the secondary conductors 2, 2. This is because when direct current flows through the secondary conductors 2, 2, the direction of the generated magnetic flux Φ follows a certain law with the direction of current flow, as shown in Figure 4, so the direct current flowing through the secondary conductors 2, 2 This is because if the polarity of the current, that is, the direction of flow is reversed, the direction of the generated magnetic flux Φ is also reversed. Therefore, even if the magnetic material such as the shear 7, inlet and outlet clamps 8, 9, etc. near the secondary conductors 2, 2 is magnetized, if the direction of direct current flow is reversed, the magnetic material will no longer be magnetized. Because it is magnetized with reversed polarity, the residual magnetic flux has no coercive force, and it no longer attracts iron powder or pieces of iron floating in the atmosphere. It is usually sufficient to reverse the polarity of the DC current each time weld, but depending on the magnitude of the DC current, it may be possible to reverse the polarity several times during one welding, and the polarity may vary depending on the time product. Of course, it is also possible to switch. Note that when the time product is used, the inversion current is also applied for the same time product.

By the way, in the above explanation, the case where this invention is applied to a DC pine seam welding machine has been described, but it goes without saying that it is not only applicable to this, but can be applied to welding machines in general.

[Effect of idea]

As explained above, this device alternately supplies alternating current to two transformers by switching a changeover switch, and two The two full-wave rectifier circuits were also activated alternately to reverse the polarity of the DC current flowing through the secondary conductor, so that magnetic materials such as the shear and inlet and outlet clamps near the secondary conductor were magnetized. The residual magnetic flux has no coercive force, and there is an effect that the magnetic material no longer attracts iron powder, iron pieces, etc. floating in the atmosphere.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of this invention, Fig. 2 is a perspective view showing the core of the transformer, Fig. 3 is an explanatory diagram showing an inverted DC current waveform, and Fig. 4 is energizing the secondary conductor. Fig. 5 is a schematic configuration diagram showing the power supply part of a conventional DC pine seam welding machine, Fig. 6 is a configuration diagram showing the clamper part of the welding machine, and Fig. 7 is a diagram showing the same welding machine. FIG. 2 is a circuit diagram of the DC power supply device of the machine. In the figure, 1 is a DC power supply, 2 is a secondary conductor, 5 is an upper rotating disk electrode, 6 is a lower rotating disk electrode, 11a is a first transformer, 11b is a second transformer,
12 is an AC power supply, 13a is a first full-wave rectifier circuit, 1
3b is a second full-wave rectifier circuit, 14a is a first thyristor (changeover switch), and 14b is a second thyristor (changeover switch). Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims for Utility Model Registration] (1) In a DC pine seam welding machine equipped with a DC power supply that supplies DC power to two rotating disc electrodes via a secondary conductor, the DC power supply has a primary side connected to an AC power supply. Two transformers are connected in parallel, two full-wave rectifier circuits are connected to the secondary sides of the two transformers, and the output side polarities are opposite to each other, and the two transformers are connected to the primary side and A DC pine seam welding machine characterized by comprising a changeover switch that alternately switches connection to an AC power source. (2) The direct current according to claim 1 of the utility model registration claim, wherein the changeover switch is two thyristors connected in parallel with opposite polarities and provided between the alternating current power source and each transformer. Pine seam welding machine.