JP2548430B2 - Arc welding power supply - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device used in an arc welding method,
In particular, it relates to control at the start of welding.

Conventional technology In the arc welding method, in order to obtain good arc start performance, the voltage applied between the welding wire and the base metal at the start of welding is set higher than that during steady welding, and the tip of the welding wire is The hot-start method is used to make the voltage applied during steady welding when the welding current flows in contact with the base metal, or the welding wire is fed at a slower feed rate than during welding, and the welding wire contacts the base metal. The wire slowdown method has been adopted in which the welding wire is fed at the welding wire feed amount during steady welding when the welding current flows.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention When the tip of the welding wire is heated red, arc start can be performed relatively easily as compared with the case where the tip of the welding wire is cooled.

Therefore, in both the conventional wire slowdown method and the hot start method, if welding is started and the next welding is started while the tip of the welding wire is still red, more energy is applied to the welding wire than necessary, The welding wire burns too much, causing arc breakage and also adversely affecting the bead shape. Furthermore, in the hot start method, there are many cases where the route for supplying current at the time of arc start and the route for supplying current at the time of steady welding are the same, and the current increase rate at arc start and the current increase rate at welding are respectively set. It is also a conventional problem that it is difficult to switch and set to an appropriate value.

Means for Solving the Problems The present invention has been made in view of the above circumstances, and identifies that a current flows between a drive signal generator, a welding wire, and a base metal in an arc welding power source. Identifying means, a first circuit for measuring a first predetermined period from the end of welding, and a second circuit for measuring a second predetermined period after the welding current flows.
A circuit and a first series circuit composed of a first resistor, a first switching element and a capacitor connected between the output terminals,
A second series circuit composed of a second resistance and a second switching element connected in parallel with the series circuit of the first resistor and the first switching element, and a third series circuit connected in parallel with the capacitor. And a gate drive circuit for opening and closing the first switching element and the second switching element.

Effect The present invention monitors the temperature of the welding wire tip portion from the time from the end of welding, and when the welding wire tip portion is in a cooled state, the welding wire and the base metal come into contact with each other from the welding start command The capacitor connected between the output terminals of the welding power source is charged until the flow of Supply the discharge current to. Further, when the tip of the welding wire is red-heated, the capacitor is not charged or discharged.

In this way, the welding wire tip is cooled by switching the current supplied between the welding wire and the base metal depending on whether the welding wire tip is cooled or heated red. In the case of, the same good arc starting performance can be obtained in the case of the red hot state, and the improvement of the welding workability is realized.

Examples Examples of the present invention will be described below.

FIG. 1 is a configuration diagram of an arc welding power supply device according to an embodiment of the present invention. In the figure, 1 is an input terminal of an arc welding machine, 2 is a rectifier, 3 is an output control element, 4 is a main transformer, and 5 is a main transformer. Is a reactor, 6 is a current detector, 7a and 7b are output terminals, 8 is a welding wire, 9 is a base material, 10 is a welding wire feed motor, 11 is a welding wire feed motor drive circuit, and 12 is a start signal generator. , 13 is a first timer, 14 is a second timer, 15 is a gate drive circuit, 16 is a first resistor, 17 is a second resistor, 18 is a first thyristor, 19 is a second thyristor, 20 is a capacitor, and 21 is a second. There are 3 resistors.

In FIG. 1, the output terminal 7a is electrically connected to the welding wire 8 via a welding torch (not shown), and
7b is connected to the base material 9. Further, the output terminal 7a is connected in parallel with the anode of the first thyristor 18 via the first charging resistor 16 and the cathode of the second thyristor 19 via the second discharging resistor 17. The cathode of the first thyristor 18 and the anode of the second thyristor 19 are the capacitor 20 and the third
It is connected to the resistor 21 and is connected to the output terminal 7b via a parallel circuit of the capacitor 21 and the third resistor 22. The welding wire 8 is
The welding wire feeding motor 10 causes the base material 9 to move at a predetermined speed.
Sent to. The output terminal of the start signal generator 12 is connected to the control input terminal of the output control element 3 of the welding power source and the control input terminal of the welding wire feeding motor drive circuit 11. The current detector 6 is connected between the output terminal 7b and the main transformer 4. The output terminal of the current detector 6 is connected to the trigger input terminal of the first timer 13 and the trigger input terminal of the second timer 14. The output terminals of the first timer 13 and the second timer 14 are connected to the input terminals of the gate drive circuit 15. The output terminals of the gate drive circuit 15 are the first thyristor 18 and the second thyristor 1
9 connected to each gate input terminal.

FIG. 2 shows the configuration of the first and second timers 13 and 14, and includes a welding current setting device 22, a measurement time setting device 23, and a timer 24.
It is composed of

Next, the operation of FIG. 1 will be described with reference to the timing chart of FIG.

The start signal generator 12 outputs the first level at the start of welding and outputs the second level at the end of welding.
The current detector 6 outputs the first level when the welding wire 8 and the base material 9 are in contact with each other and the welding current flows, and outputs the second level when the welding current stops flowing. The first timer 13
The first level is triggered by the second level of the output signal of the current detector 6.
The first level is output for a predetermined period, and the second level is output when the first predetermined period has elapsed. The second timer 14 outputs the first level for the second predetermined period triggered by the first level of the output signal of the current detector 6, and outputs the second level after the lapse of the second predetermined period. When the output signal of the first timer 13 is at the second level, the gate drive circuit 15 determines that the output signal of the activation signal generator 12 is at the first level and the output signal of the current detector 6 is at the second level. , And outputs a first level output signal to the gate input terminal of the first thyristor 18. When the output signal of the start signal generator 12 is at the first level and the output signal of the current detector 6 is at the second level, and when the output signal of the second timer 14 is at the first level, Second thyristor
The second level output signal is output to the gate input terminal of 19.

First, at the start of welding, the activation signal generator 12 outputs a drive signal to the output control element 3 of the welding power source and the welding wire feeding motor drive circuit 11. By this start signal, the welding power source applies a voltage between the welding wire 8 and the base material 9 through the reactor 5. Also, the welding wire feeding motor drive circuit 11
Drives the welding wire feeding motor 10 to drive the welding wire 8
Is fed toward the base material 9. Furthermore, the first timer 13
Measures a first predetermined period from the end of welding and outputs an output signal to the gate drive circuit. The gate drive circuit keeps the first thyristor 18 flowing until the welding current flows between the welding wire 8 and the base metal 9 from the start of welding when the welding is started after the lapse of the first predetermined period from the end of welding, The capacitor 20 is charged through the first resistor 16, and the welding wire 8 and the base material 9 are charged.
When the welding current flows during the period from the start of welding to the end of the second predetermined period, the second thyristor 19 is kept in the flowing state,
The capacitor 20 is discharged through the resistor 17. Capacitor
The discharge current of 20 is superimposed on the output current of the welding power source and flows between the welding wire 8 and the base material 9. Also, the first from the end of welding
When welding is started within the specified period, the first thyristor 18
The second thyristor 19 and the capacitor 20 remain in the non-flowing state.
Is not charged. Further, after the welding is completed, the electric charge charged in the capacitor 20 is discharged by the third resistor 22.

In this way, when the next welding is performed after the lapse of the first predetermined period from the end of welding, the first thyristor 18 is kept in the flow state until the welding current flows from the welding start command and the connection is made between the output terminals. The charged capacitor 20 is charged, and the capacitor 20 is discharged for a second predetermined period after the welding current flows,
The discharge current is supplied to the contact portion between the welding wire 8 and the base material 9, but when the next welding is performed within the first predetermined period after the end of welding, the capacitor 20 is not charged or discharged.

As described above, according to the present invention, in arc welding,
By switching the current supplied between the welding wire and the base metal depending on whether the tip of the welding wire is cooled or heated red, the tip of the welding wire is red-heated even when it is cooled. Similarly, even in the state, good arc start performance can be obtained, and welding workability can be improved, so that the practical effect thereof is great.

[Brief description of drawings]

FIG. 1 is a block diagram of an arc welding power source device in one embodiment of the present invention, FIG. 2 is a block diagram of a first timer and a second timer,
FIG. 3 is an operation timing chart of each part of FIG. 6 ... Current detector, 8 ... Welding wire, 12 ... Starting signal generator, 13 ... First timer, 14 ... Second timer, 15 ...
Gate drive circuit.

Claims (3)

(57) [Claims] 1. A drive signal generator, identification means for identifying that a current has flowed between a welding wire and a base material, a first circuit for measuring a first predetermined period from the end of welding, and a welding current A second circuit for measuring a second predetermined period from the first series circuit, a first series circuit composed of a first resistor, a first switching element and a capacitor connected between output terminals, the first resistor and the first switching element A second series circuit composed of a second resistor and a second switching element connected in parallel with the series circuit, a third resistor connected in parallel with the capacitor, and the first switching element. A gate drive circuit for opening and closing a second switching element, and when the next welding is performed after the first predetermined period has elapsed from the end of welding, the first welding operation is performed until the welding current flows from the welding start command. Sui of 1 The quenching element flowing state, charging the capacitor connected between the output terminal, from the welding current flows until after the second predetermined time period, the second
Of the switching element, the capacitor is discharged, and the discharge current is supplied to the contact portion between the welding wire and the base metal. On the other hand, the next welding is performed within the first predetermined period from the end of welding. In this case, the arc welding power supply device is configured such that the capacitor is not charged or discharged. 2. The arc welding power supply device according to claim 1, wherein the first predetermined period and the second predetermined period are determined by a welding current. 3. The first switching element and the second switching element are thyristors, and the first switching element and the second switching element are connected so that the energizing directions are opposite to each other. Claim 1 characterized by
The arc welding power supply device described.