JP2002263839A - Welding power unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a welding power unit provided with both of a resistance welding function and a TIG welding function. SOLUTION: The unit is provided with an input-side rectifier 2 for rectifying an input primary AC voltage, a high frequency converter such as an inverter 6 for converting an output DC voltage of the input-side rectifier to a high-frequency voltage of a frequency higher than that of the primary AC voltage, a TIG welding voltage generation part 9 connected between the output of the inverter and a TIG welding power output terminal 16 through the first switching switch 8, a resistance welding voltage generation part 19 connected between the output of the inverter and an resistance welding power output terminal 26 through the second switching switch 18, and a welding switching control part 41 for controlling on/off of the first/second switching switches and the operation of the inverter according to the switching of TIG welding and resistance welding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding power supply, and more particularly to a welding power supply suitable for repairing a mold.

[0002]

2. Description of the Related Art A mold is worn when used for a long period of time, and may be damaged by hitting another mold or article during storage or handling, such as cracks, chips or dents. For such worn or damaged molds, repair metal materials of the same or equivalent material are repaired by welding them to the worn or damaged parts, and reused. are doing.

[0003] The repair metal material is usually very small, and to weld it to the repair part of the mold, it is first temporarily welded by resistance welding in a short time, and then overlaid by TIG (Tungsten Inert Gas) welding. . After welding the repair metal material to the repair part of the mold, the repaired part is polished to regenerate the mold.

When the repair metal material is to be welded to the repair part of the mold only by TIG welding, the repair metal material is very small, so that the repair metal material is used due to an inert gas flow such as argon used during TIG welding. The metal material is blown away and cannot be welded in place. On the other hand, if the mold is to be repaired only by resistance welding, the repair metal material is less likely to penetrate into the repaired portion, and sufficient build-up cannot be performed. For this reason, in order to weld the repair metal material to the repair portion of the mold, first, temporary welding by resistance welding and subsequent TIG welding are required.

[0005]

Therefore, in order to repair a worn portion of a mold or a damaged portion such as a crack or a chip, an independent power source for resistance welding and a power source for TIG welding have conventionally been used. It was necessary to prepare the equipment and the repair work also required to replace the power supply unit for TIG welding after completion of the resistance welding and perform TIG welding, which was very troublesome and the work efficiency was not good.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a welding power supply having both a function as a resistance welding power supply and a function as a TIG welding power supply by itself.

[0007]

According to a first aspect of the present invention, there is provided an input rectifier for rectifying an input commercial AC voltage, and an output DC voltage of the input rectifier having a frequency higher than the frequency of the commercial AC voltage. A high-frequency converter for converting to a high-frequency voltage of
A TIG welding voltage generator coupled between the output of the high-frequency converter and a TIG welding power supply output terminal via a first change-over switch; and between the output of the high-frequency converter and the resistance welding power supply output terminal. A resistance welding voltage generator connected via a second changeover switch, and a welding switching controller for selectively switching between TIG welding and resistance welding are provided.
When the TIG welding is selected, the welding changeover control section turns on the first changeover switch, turns off the second changeover switch, and sets the high frequency so as to obtain a current and a welding time required for the TIG welding. The operation of the converter is controlled, and when resistance welding is selected, the first switch is turned off and the second switch is turned on.
The operation of the high-frequency converter is controlled so that a current and a welding time required for resistance welding are obtained.

According to a second aspect of the present invention, in the first aspect, the TIG welding voltage generator includes a first switch and a TIG welding voltage generator.
A first welding power transformer, a first output rectifier, and a first reactor coupled in series between the welding power output terminal and a resistance welding voltage generator; A second welding power transformer, a second output rectifier, and a second reactor are connected in series between the power output terminal and a second welding power transformer.

In a third aspect of the present invention, in the second aspect, the TIG welding power supply transformer and the resistance welding power supply transformer are configured as one transformer by winding respective windings around a common iron core. It is characterized by having.

According to a fourth aspect of the present invention, in the first to third aspects, a welding current detector is provided in each of the TIG welding voltage generator and the resistance welding voltage generator. The magnitude of the welding current at the time of welding is detected, and a signal representing the magnitude of the welding current is supplied to the welding switching control unit as a feedback signal, and the welding switching control unit responds to the signal to determine a predetermined value at each welding. The high-frequency converter is controlled so as to obtain a welding current having a magnitude of.

According to a fifth aspect of the present invention, in the first to third aspects, one welding current detector is provided at a work connection terminal common to the TIG welding voltage generator and the resistance welding voltage generator. The one welding current detector detects the magnitude of the welding current at the time of each welding, and supplies a signal representing the magnitude of each welding current to the welding switching control unit, and the welding switching control unit The high frequency converter is controlled so that a welding current of a predetermined magnitude is obtained at each welding in response to the signal.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, a portion 1 surrounded by a chain line shows an embodiment of a welding power supply suitable for mold repair according to the present invention, and 2 is an input-side rectifier of the welding power supply.
4 is connected to a commercial power supply to supply a commercial AC voltage. The DC obtained by rectifying the commercial AC voltage by the input side rectifier 2 is converted into a high frequency converter, for example, an inverter 6 at a frequency much higher than the frequency of the commercial AC voltage, for example, 10 Hz.
It is converted to a high frequency of KHz or more.

The high frequency voltage generated by the inverter 6 is
It is coupled to a TIG welding voltage generator 9 via a first switch 8 and to a resistance welding voltage generator 19 via a second switch 18. TIG welding voltage generator 9
A TIG welding power transformer 10 having a primary winding coupled to the output of the inverter 6 via the first switch 8 to generate an output high-frequency voltage converted to a voltage suitable for TIG welding; 2 coupled to the secondary winding of the transformer 10
An output rectifier 11 including phase half-wave rectifier diodes 12 and 13, a reactor 14 and a TIG coupled in series between the output rectifier 11 and a TIG welding power output terminal 16.
And a welding current detector 15.

Similarly, the resistance welding voltage generating section 19 has a primary winding coupled to the output of the inverter 6 via the second switch 18 and outputs an output high frequency converted to a voltage suitable for resistance welding. Resistance welding power transformer 20 for generating voltage
An output rectifier 21 including two-phase half-wave rectifier diodes 22 and 23 coupled to a secondary winding of the transformer 20, and a series connection between the output rectifier 21 and a resistance welding power output terminal 26. , A reactor 24 and a resistance welding current detector 25 coupled thereto.

During a welding operation, a TIG welding torch (electrode) 28 is connected to the TIG welding power supply output terminal 16.
Although the TIG welding torch 28 is not shown in the drawing,
As is well known, a tungsten electrode and a nozzle surrounding the tungsten electrode for discharging an inert gas such as argon are provided. The inert gas shields and stabilizes the arc, and also acts as a shield gas for preventing the weld metal from reacting with oxygen, nitrogen and the like in the atmosphere and being adversely affected. A resistance welding torch (electrode) 30 is connected to the resistance welding power supply output terminal 26.

The intermediate taps of the power transformers 10 and 20 are connected to each other at a connection point 32 and to a work connection terminal 34. A work (base material) 36 including a repair mold and a repair metal material is connected to the work connection terminal 34.

Reference numeral 38 denotes a welding selection device. When this selects TIG welding, the switch 8 is turned on and the switch 18 is turned off, and a TIG welding selection signal is sent to a high-frequency converter control device, in this embodiment, an inverter control device 40. Supply. When the welding selection device 38 selects resistance welding,
With switch 8 off and switch 18 on,
A resistance welding selection signal is supplied to the inverter control device 40. From this, the welding selection device 38 and the inverter control device 40 cooperate to constitute the welding switching control unit 41.

In response to a welding selection signal supplied from welding selection device 38, inverter control device 40 determines the operating time and output current of inverter 6 during resistance welding.
Control is performed so as to conform to each of the G welding. The inverter control device 40 is provided with a torch switch 42 for starting TIG welding and a torch switch 44 for starting resistance welding. A signal indicating the magnitude of the welding current at that time is supplied as a feedback signal from the welding current detectors 15 and 25 to the inverter control device 40, and the inverter control device 40 responds to the signal to make necessary signals for each welding. The operation of the inverter 6 is controlled so that a welding current of an appropriate magnitude is maintained.

In the welding power supply device of the present invention having the above structure, when repairing a worn mold or a damaged mold, a repair metal material is placed on a repair portion of the repaired mold. Work connection terminal 34
Connect to When resistance welding is first selected by the welding selection device 38, the inverter control device 40 sets the inverter 6 to the resistance welding specification. Further, the switch 8 is turned off and the switch 18 is turned on.

In the resistance welding specification, the inverter 6 is connected to the output terminal 26 of the resistance welding power supply,
0V, welding voltage 5V, welding current 750A, welding time 30
It is set so that mS (millisecond) is obtained. Here
When the resistance welding torch 30 is brought into contact with the work 36 and the resistance welding activation torch switch 44 is turned on (the TIG welding activation torch switch 42 is turned off), the inverter control device 40 operates the inverter 6 in accordance with the above resistance welding specification. Then, the repair metal material is temporarily welded to the mold. The welding current at this time is detected by the resistance welding current detector 25, and a signal representing the detected current value is provided as a feedback signal to the inverter control device 40.
Supplied to Thereby, the inverter control device 40
As shown in FIG. 2A, the operation of the inverter 6 is controlled so that the welding current maintained at, for example, 750 A flows for 30 mS, and the repair metal material is temporarily welded to the mold.

After the provisional welding of the repair metal material, when TIG welding is selected by the welding selection device 38, the switch 8 is turned on and the switch 18 is turned off, and the inverter control device 40 sets the inverter 6 to the TIG welding specification. In the TIG welding specification, the inverter 6 is connected to the TIG welding power supply output terminal 16 at a no-load voltage of 80 V, a welding voltage of 20 V, for example.
The welding current is set to 250 A and the welding time is set to 600 mS (millisecond). Here, when the torch switch 42 for starting TIG welding is turned on (the torch switch 44 for starting resistance welding is turned off), the inverter control device 40 operates the inverter 6 in accordance with the above TIG welding specification.

At the start of TIG welding, an inert gas flows in the torch 28 in a well-known manner, and a pilot arc is generated in the torch (between the electrode and the nozzle) by a high-frequency voltage supplied from a high-frequency generator (not shown). . T
When the IG welding torch 28 is brought closer to the work 36, a main arc is generated between the torch 28 and the work 36, that is, the repair part of the mold. The main arc current is detected by the TIG welding current detector 15, and a signal representing the magnitude of the main arc current is fed back to the inverter control device 40. As a result, the inverter control device 40
As shown in (b), the operation of the inverter 6 is controlled so that the welding current maintained at, for example, 250 A flows for 600 mS (millisecond). By this TIG welding, a necessary build-up is performed on a welded portion between the mold and the repair metal material.

Since the torch (electrode) for TIG welding is cold at the start of TIG welding, a so-called hot start is usually performed by applying a large current for a short time at the start of the main arc as shown in FIG. 2 (b). ing. After the mold is provided with a predetermined build-up, the repair portion is polished to complete the repair of the mold.

In the above-described embodiment of the welding power supply device of the present invention, the TIG welding power supply transformer 10 and the resistance welding power supply transformer 20 are separately provided.
It is also possible to replace each transformer with a single transformer constituted by winding the transformer windings magnetically loosely around a common iron core. With such a configuration, the number of parts is reduced, and downsizing of the welding power supply device can be realized. Two current detectors 15 to detect the welding current,
25, the connection point 32 and the work connection terminal 3
4, one welding current detector may be provided, and a signal indicating the magnitude of the welding current detected at each welding may be supplied to the inverter control device 40. Also in the case of such a configuration, the number of components can be reduced, and the size of the welding power supply device can be reduced. In the embodiment, the inverter is used as the high-frequency converter.
Instead of this, a chopper or another having the same effect may be used.

In the above embodiment, the torch switch 42 for starting TIG welding and the torch switch 44 for starting resistance welding are not turned on at the same time.
If for some reason the other torch switch is turned on while one torch switch is on,
It is desirable that the inverter control circuit 40 interlocks or the inverter 6 is stopped. Also, instead of separately providing the torch switch 42 for starting TIG welding and the torch switch 44 for starting resistance welding, one starting switch, for example, one foot-operated switch is used to perform resistance welding at the first step. Start up,
It is also possible to configure so that resistance welding is stopped and TIG welding is started at the second step.

[0026]

As described above, according to the welding power supply of the present invention, a single welding power supply having a common input-side rectifier for rectifying a commercial AC voltage and a high-frequency converter can simply switch a switch. Resistance welding and TIG welding can be performed continuously, and each welding power supply device is prepared as in the prior art, and after the completion of one welding operation, the welding power supply device is replaced and the other welding is performed. There is an effect that welding can be performed much more efficiently than in a welding operation, and it is particularly excellent as a welding power supply device for repairing a mold. Further, the welding power supply of the present invention uses a high-frequency converter that generates a high frequency having a frequency much higher than the commercial AC voltage. In this case, the mold can be repaired in a short time, and there is also an effect that the mold does not have to be distorted by heat during welding.

[Brief description of the drawings]

FIG. 1 is a schematic circuit diagram partially showing a welding power supply device according to an embodiment of the present invention by blocks.

FIG. 2A is a diagram showing an example of a welding current waveform when resistance welding is performed by the welding power supply device of FIG. 1; (B) is a figure which shows an example of the welding current waveform at the time of performing TIG welding with the welding power supply device of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Welding power supply 2 Input side rectifier 6 Inverter (high frequency converter) 8 1st switch 9 TIG welding voltage generation part 10 1st welding power supply transformer 11 1st output side rectifier 14 1st reactor 15 TIG welding current Detector 16 TIG welding power output terminal 18 Second switch 19 Resistance welding voltage generator 20 Second welding power transformer 21 Second output rectifier 24 Second reactor 25 Resistance welding current detector 26 Resistance welding power output Terminal 32 Connection point 34 Work connection terminal 38 Welding selection device 40 Inverter control device (high frequency converter control device) 41 Welding switching control unit

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Atsushi Kinoshita 3-1-1, Nishiawaji, Higashiyodogawa-ku, Osaka-shi, Osaka F term (reference) 4E082 CA02 DA01 EC13 EE06 EF07 EF15 EF30 5H790 BA03 BB08 CC02 DD06 DD08 EA02 EA07 EA22 EB03

Claims (5)

[Claims] An input-side rectifier for rectifying an input commercial AC voltage; a high-frequency converter for converting an output DC voltage of the input-side rectifier to a high-frequency voltage having a frequency higher than the frequency of the commercial AC voltage; A TIG welding voltage generator coupled between the output of the high-frequency converter and the TIG welding power supply output terminal via a first selector switch, and a TIG welding voltage generator connected between the output of the high-frequency converter and the resistance welding power supply output terminal. 2) a resistance welding voltage generating unit coupled via the two changeover switches; and a welding switching control unit for selectively switching between TIG welding and resistance welding. The first switch is turned on, the second switch is turned off, and the operation of the high-frequency converter is controlled so that a current and a welding time required for TIG welding can be obtained. The during resistance welding selecting first off changeover switch, thereby turning on the second switching switch,
A welding power supply device that controls the operation of the high-frequency converter so that a current and a welding time required for resistance welding are obtained. 2. A TIG welding voltage generator, comprising: a first welding power transformer, a first output rectifier, and a first reactor coupled in series between a first switch and a TIG welding power output terminal. Wherein the resistance welding voltage generator includes a second welding power transformer, a second output rectifier, and a second reactor coupled in series between the second switch and the resistance welding power output terminal. The welding power supply device according to claim 1, comprising: 3. The transformer according to claim 2, wherein the TIG welding power transformer and the resistance welding power transformer are formed as one transformer by winding respective windings around a common iron core. The described welding power supply. 4. A welding current detector is provided in each of the TIG welding voltage generator and the resistance welding voltage generator, and each welding current detector detects a magnitude of a welding current at the time of welding. A signal representing the magnitude of the welding current is supplied to a welding switching controller, and the welding switching controller controls the high-frequency converter in response to the signal so that a welding current of a predetermined magnitude is obtained at each welding. The welding power supply device according to any one of claims 1 to 3, characterized in that: 5. A welding current detector is provided at a work connection terminal common to the TIG welding voltage generator and the resistance welding voltage generator, and the welding current detectors detect the welding current at the time of each welding. The magnitude is detected, and a signal representing the magnitude of the welding current is supplied to a welding switching control section. The welding switching control section responds to the signal to obtain a welding current of a predetermined magnitude at each welding. The welding power supply device according to any one of claims 1 to 3, wherein the high-frequency converter is controlled as described above.