JPH08243741A - Arc welding machine - Google Patents

Abstract

(57) [Summary] [Purpose] We propose a welding machine that can be easily selected according to the type of welding rod. [Configuration] First setting of hot current at arc start
Setting device 21, a second setting device 22 for setting a small current at arc start, a third setting device 23 for setting an output current at steady state, and an arc start current selection for switching the current setting at arc start And means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arc welding machine, and more particularly to a manual welding arc welding machine using a welding rod.

[0002]

2. Description of the Related Art This type of arc welder rectifies a commercial power source, converts this rectified direct current into a high frequency alternating current by an inverter, and rectifies it again to obtain a welding direct current, which is then applied to the welding rod and the work. Is being supplied. Furthermore, the current flowing through the welding load is detected, and the output is made constant by feedback control of the inverter based on the output current setting signal. This type of welding machine does not require a large-capacity input transformer, and by increasing the output frequency of the inverter, the output transformer can be miniaturized. By controlling the switching of the inverter as the reference voltage of 1, the output current can be efficiently stabilized.

In arc welding using a welding rod, a constant current DC is supplied from a welding machine to a welding load formed by the welding rod and a work at the time of starting, and the welding rod is short-circuited to the work.
The short-circuited welding rod is separated from the work to form an arc and weld.

The welding machine used in this welding usually has metal at its tip. Therefore, when the welding rod is short-circuited to the work at the start of the arc and then the welding rod is separated from the work, an arc is easily generated. However, when the output current value at the start of the arc is increased, a large amount of spatter is generated when the arc is generated. Therefore, as shown in FIG. 2, the arc is started with a small current and then the current is shifted to the steady state.

On the other hand, some welding machines have a cellulosic material such as 6010 (trade name), and in a welding machine using this welding rod, the flux of the welding rod is melted during welding before starting an arc start. And, the tip of the welding rod is semiconductor-like. For this reason, as with the arc start of the metal welding rod, even if an attempt is made to start the arc with a small current, it may not be possible to start the arc.

[0006]

It is uneconomical to own a welding machine having two types of arc start characteristics according to the above two types of welding rods, and it is uneconomical to have each welding start for each arc start. Had to set.

[0007]

SUMMARY OF THE INVENTION The present invention is directed to an input rectifier for rectifying AC power, an inverter for converting the output of the rectifier to high frequency AC, an output rectifier for rectifying the output of the inverter, and an output rectifier thereof. In an arc welding machine equipped with a means for supplying the output of the above to a welding rod and a work, and a control means for driving the above inverter, a first setting device for setting a hot current at the time of arc start, and a small setting device at the time of arc start. A second setting device for setting a current, a third setting device for setting a steady-state output current, and an arc start current selecting means for switching the current setting at the arc start were provided.

[0008]

The AC power is rectified by the input rectifier, and the rectified output is converted into high frequency AC by the inverter. The converted high frequency AC is rectified by the output rectifier, and DC power is supplied to the welding rod and the work.

Then, the first setter is selected, and the output thereof controls the control means for driving the inverter,
At the start of arc, a large amount of hot current is supplied to the welding load. Further, the second setting device is selected, and the control means is controlled by the output of the second setting device so that a small current at arc start is supplied to the welding load.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG.
Shown in 2 is an input rectifier for rectifying the AC power supplied to the input terminal 1, 3 is a capacitor for smoothing the DC output rectified by the input rectifier 2, 4 is an IGBT, MOS
An inverter equipped with switching elements such as FETs and transistors converts smoothed DC into high-frequency AC.
Reference numeral 5 is an output transformer for transforming the converted high frequency alternating current, 6 is an output rectifier for rectifying the high frequency alternating current, and 7 is a smoothing reactor. Reference numeral 8 is a welding rod, and 9 is a work, which forms a welding load 10 together with the welding rod.

Reference numeral 15 is a current detector for detecting the output current flowing through the welding load 10. Reference numeral 16 is an operational amplifier.
Detection signal and output current setting means 1 for setting output current
The error with the setting signal of 7 is amplified. Reference numeral 18 denotes a drive circuit which receives the output signal of the operational amplifier and drives the inverter 4, and performs feedback control to make the output constant current.

The output current setting means 17 includes a first setter 21 for setting the output current at arc start to a large hot current, a second setter 22 for setting a small current at arc start, and a steady-state time. A third setter 23 for setting the output current of the second setter, and an arc start current selecting means 24 for switching between the current setting of the first setter 21 and the second setter 22;
It is composed of opening / closing means 25 and 26 for switching between current setting at the time of arc start and current setting at the time of steady state.
In addition, 31 is a switch for starting the arc welding machine, 27
Is a timer for setting the arc start time, and its opening / closing section is composed of opening / closing means 25 and 26.

The arc welder thus constructed operates as follows. The AC power supply is rectified by the input rectifier 2 and smoothed by the capacitor 3. The smoothed direct current is converted into high frequency alternating current by the inverter 4 and transformed by the transformer 5. The transformed high frequency alternating current is rectified by the output rectifier 6, and the rectified output is the welding load 1
0 is supplied.

If the welding rod is of cellulose type, the arc start current selecting means 24 is connected to the first setting device 21 side. When the welding rod 8 is short-circuited to the work 9 and the start switch 31 is turned on, the timer 27 operates. At this time, the normally-closed opening / closing means 25 is on, and the current setting signal of the first setting device 21 is input to the operational amplifier 16. On the other hand, the output current flowing through the welding load 10 is detected by the current detector 15, this current detection signal is input to the operational amplifier 16, the error from the current setting signal is amplified, and the inverter 4 is driven via the drive circuit 18. . At this time, the first setting device 21 sets a large hot current, so that a large current flows through the welding load 10 as shown in FIG. Then, when the timer 27 times out, the normally-closed opening / closing means 25 is opened and the normally-opening opening / closing means 26 is short-circuited. The setting signal of the third setting device 23 that sets the output current at the constant time is input to the operational amplifier 16, and a predetermined output current flows to the output of the inverter 4.

For this reason, even if the tip of the welding rod 8 is a semiconductor, a large current flows at the time of arc start.
A good arc start is possible.

When the welding rod is made of a metal other than cellulose, the arc start current selecting means 24 is connected to the second setting device 22 side. When the welding rod 8 is short-circuited to the work 9 and the start switch 31 is turned on, the timer 27 operates. At this time, similarly to the above, the normally-closed opening / closing means 25
Is on, and the current setting signal of the second setting device 22 is input to the operational amplifier 16. The output current flowing through the welding load 10 is detected by the current detector 15, this detection signal is input to the operational amplifier 16, the error from the current setting signal is amplified, and the inverter 4 is driven via the drive circuit 18. At this time, the second setting device 22 sets a small current so that a small current flows through the welding load 10 as shown in FIG. Then, when the timer 27 times out, the normally-closed opening / closing means 25 is opened, the normally-opening opening / closing means 26 is short-circuited, and the setting signal of the third setting device 23 for setting the output current in the steady state is the operational amplifier 16 And a predetermined output current flows to the output of the inverter 4.

Therefore, the tip of the welding rod 8 is not overheated, and a stable arc start without spattering can be achieved.

In the above embodiment, the arc welding machine controls the feedback of the inverter 4 based on the current setting signal of the output current setting means 17, but when the feedback control is not performed because the operational amplifier 16 is not provided. The output current setting means 17 may be connected to the signal input side of the drive circuit 18 of the inverter 4.

[0019]

According to the present invention, the arc start can be selected according to the welding rod, and good arc start can be performed.

[Brief description of drawings]

FIG. 1 is a block connection diagram of an embodiment of an arc welder of the present invention.

FIG. 2 is a time chart of the output current of the arc welding machine.

FIG. 3 is a time chart of the output current of the arc welding machine.

[Explanation of symbols]

 2 Input Rectifier 4 Inverter 5 Output Transformer 7 Reactor 8 Welding Rod 9 Workpiece 10 Welding Load 15 Current Detector 16 Operational Amplifier 17 Output Current Setting Means 18 Drive Circuit 21 (First) Setting Device 22 (Second) Setting Device 23 (third) setter 24 arc start current selecting means 25, 26 opening / closing means 27 timer 31 start switch

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Atsushi Kinoshita 2-14-3 Awaji, Higashiyodogawa-ku, Osaka City, Osaka Prefecture Sansha Electric Manufacturing Co., Ltd. (72) Takashi Hashimoto 2-chome, Awaji, Higashiyodogawa-ku, Osaka City, Osaka Prefecture No.14-3 Sansha Electric Manufacturing Co., Ltd.

Claims (1)

[Claims] 1. An input rectifier for rectifying AC power,
An inverter that converts the output of the rectifier into high-frequency AC, an output rectifier that rectifies the output of the inverter, a means that supplies the output of the output rectifier to a welding rod and a work, and a control means that drives the inverter In an arc welding machine, a first setter for setting a hot current at the arc start, a second setter for setting a small current at the arc start, and a third setter for setting a steady-state output current. , An arc welding current selection means for switching the current setting at the time of arc starting.