JPWO2020008679A1 - Arc welder - Google Patents

Abstract

The power calculation unit 41 calculates the power consumption consumed within a predetermined unit time based on the load current detected by the load current detection unit 31 and the load voltage detected by the load voltage detection unit 32. The comparison unit 42 compares the power consumption with a predetermined power threshold value. The abnormality determination unit 40 determines that the output of the load power is abnormal when the power consumption is larger than the power threshold value.

Description

The present invention relates to an arc welder.

Conventionally, in a power supply device used in an arc welder or the like, the output power is adjusted by controlling the switching operation of the switching element constituting the inverter circuit (see, for example, Patent Document 1).

In Patent Document 1, in order to protect the switching element from overheating, a temperature sensor is arranged around the inverter circuit, and the switching operation is stopped based on the detection of the overheating state of the switching element by the temperature sensor. Is disclosed.

Japanese Patent No. 5897381

By the way, in the conventional power supply device for welding, when a high load higher than the rating of the device is generated depending on the welding method and welding conditions, the internal temperature of the power supply device may exceed the permissible value.

Specifically, the welding power supply is defined as a rated load, for example, a load current of 350 A, a load voltage of 36 V, and a usage rate of 60%. However, depending on the welding method and welding conditions, under low usage rate (or instantaneous) conditions, for example, during pulse welding, a high load with a load current of 520 A and a load voltage of about 40 V may occur in 2 ms. ..

At this time, a sudden heat concentration occurs due to a high load exceeding the rated load, and the internal temperature of the power supply device rises, but it is difficult to sensitively detect this sudden temperature change with a temperature sensor. Therefore, the switching operation of the switching element does not stop, and the temperature permissible value of each component inside the device is exceeded, which may damage the welding power supply.

The present invention has been made in view of such a point, and an object of the present invention is to enable overheat protection of the device when a high load exceeding the rating of the device is generated.

The aspect of the present disclosure is intended for an arc welder that performs arc welding by supplying load power to a machining load including an electrode for arc welding and a base metal, and has taken the following solutions.

That is, the first aspect is a load current detection unit that detects the load current supplied to the machining load.
A load voltage detector that detects the load voltage supplied to the machining load, and
A power calculation unit that calculates the power consumption consumed within a predetermined unit time based on the load current and the load voltage.
It is characterized by including an abnormality determination unit that determines that the output of the load power is abnormal when the power consumption is larger than a predetermined power threshold value.

In the first aspect, the power consumption consumed within a predetermined unit time is calculated based on the load current and the load voltage. Then, when the power consumption is larger than the predetermined power threshold value, it is determined that the output of the load power is abnormal.

Specifically, the power supply of the arc welder has a rated load of, for example, a load current of 350 A and a load voltage of 36 V (or, according to the standard, a load current of 350 A and a load voltage of 31.5 V) and a usage rate of 60%. It is stipulated. Here, the usage rate indicates the ratio of the time during which the arc is actually generated to the time during which the arc welder is used. For example, when the welding machine is used for 10 minutes, the arc generation time is 6 minutes and the rest time is 4 minutes.

However, under low usage rate (or instantaneous) conditions, for example, during pulse welding, a high load with a load current of 520 A and a load voltage of about 40 V may occur in 2 ms.

Therefore, while constantly monitoring the state of the load power of the arc welder, the cumulative value of the load power per unit time (for example, 10 minutes), that is, the power consumption consumed within the unit time is greater than the predetermined power threshold. When it becomes large, it may be determined that the output of the load power is abnormal, and for example, the arc welder may be stopped urgently, or the operator may be warned by an alarm or an error message. The unit time may be, for example, 1 minute or 5 minutes, and may be arbitrarily set.

Here, the power threshold value for determining the abnormality may be set based on, for example, the allowable temperature of the main semiconductor inside the device. Further, it may be set to (350 × 36) /1000=12.6 kW based on the rated load.

As a result, overheat protection of the arc welder can be performed even when an instantaneous high load exceeding the rated standard load characteristic of the arc welder is generated.

The second aspect is, in the first aspect,
It is provided with an output control unit that controls the supply operation of the load power with respect to the processing load.
The output control unit is characterized in that when an abnormality is determined by the abnormality determination unit, the load power supply operation is stopped.

In the second aspect, when it is determined that the output of the load power is abnormal, the load power supply operation is stopped to prevent the temperature inside the device from rising further, and each of the devices inside the device. The component can be protected from exceeding the temperature tolerance.

The third aspect is, in the first or second aspect,
Equipped with a temperature detector that detects the temperature around the device
The abnormality determination unit is characterized in that it calculates a difference value between the detection temperature detected by the temperature detection unit and a predetermined temperature threshold value, and changes the power threshold value based on the difference value. is there.

In the third aspect, the power threshold value for abnormality determination is changed based on the difference value between the detected temperature around the device and the predetermined temperature threshold value. As a result, the device can be protected according to the temperature around the device.

Specifically, when the temperature around the device is low, for example, when the device is used in a cold region, even if a high load exceeding the rating of the device is generated and the switching part inside the device generates heat, heat is generated. Since the parts are cooled and the temperature drops, there is a margin before the temperature tolerance of the equipment is exceeded.

Therefore, the larger the difference between the detected temperature around the device and the temperature threshold value, the larger the power threshold value for determining the abnormality. It is possible to suppress the judgment. As a result, the device can be protected while stabilizing the output of the load power.

According to the aspect of the present disclosure, overheat protection of the device can be performed when a high load exceeding the rating of the device occurs.

FIG. 1 is a schematic view showing a configuration of an arc welder according to the first embodiment. FIG. 2 is a schematic view showing the configuration of the arc welder according to the second embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the following description of the preferred embodiment is essentially merely an example and is not intended to limit the present invention, its application or its use.

<< Embodiment 1 >>
As shown in FIG. 1, the arc welder 10 supplies load power to a machining load 13 including an electrode 11 for arc welding and a base metal 12, and performs arc welding. An AC power supply 15 is connected to the input terminal 16 of the arc welder 10. The arc welder 10 includes a power conversion unit 20 that converts the AC power of the AC power source 15 into load power.

The power conversion unit 20 includes an input rectifier unit 21 that rectifies the AC power of the AC power supply 15 into DC power, a switching unit 22 that converts the output power of the input rectifier unit 21 into AC power of a predetermined frequency, and a switching unit 22. The transformer unit 23 that lowers the output voltage, the output rectifier unit 24 that rectifies the output power of the transformer unit 23 to a DC load power for supplying the electrode 11, and the output rectifier unit 24 suppresses harmonics of the output power. It is equipped with a DC reactor 25.

A cable 26 connected to the base material 12 is connected to the output side of the output rectifying unit 24. A cable 26 connected to the electrode 11 is connected to the output side of the DC reactor 25.

The arc welder 10 is provided with a load current detection unit 31 for detecting the load current supplied to the machining load 13 and a load voltage detection unit 32 for detecting the load voltage supplied to the machining load 13.

The load current detection unit 31 is connected to the output side of the output rectification unit 24. The load voltage detection unit 32 is connected to a load voltage detection line 33 arranged from the vicinity of the electrode 11 and the vicinity of the base material 12, respectively.

The load current detected by the load current detection unit 31 and the load voltage detected by the load voltage detection unit 32 are input to the output control unit 34. The output control unit 34 outputs a control signal to the switching unit 22 and feeds back the operation of the switching unit 22 so that the load power for appropriately performing arc welding can be obtained based on the load current and the load voltage. Control.

A temperature sensor 35 is arranged around the switching unit 22. The detected temperature detected by the temperature sensor 35 is input to the output control unit 34. The output control unit 34 stops the operation of the switching unit 22 when the detected temperature exceeds the temperature permissible value of each component.

By the way, in a conventional arc welder, when a load higher than the rating of the equipment is generated depending on the welding method and welding conditions, the internal temperature of the equipment may exceed the permissible value.

Specifically, a sudden heat concentration occurs due to a high load exceeding the rated load, and the internal temperature of the device rises, but it is difficult for the temperature sensor 35 to sensitively detect this sudden temperature change. Therefore, the switching operation of the switching unit 22 does not stop, and the temperature permissible value of each component inside the device is exceeded, which may damage the arc welder 10.

Therefore, in the present embodiment, it is possible to determine an abnormality in the output of the load power based on the cumulative value of the load power consumed by the processing load 13.

Specifically, the arc welder 10 includes an abnormality determination unit 40. The abnormality determination unit 40 includes a power calculation unit 41 and a comparison unit 42. A signal indicating the load current detected by the load current detection unit 31 and a signal indicating the load voltage detected by the load voltage detection unit 32 are input to the abnormality determination unit 40.

The power calculation unit 41 calculates the load power consumed by the machining load 13 by integrating the load current and the load voltage. Here, the power calculation unit 41 calculates the cumulative value of the load power per predetermined unit time (for example, 10 minutes), that is, the power consumption consumed within the unit time.

The comparison unit 42 compares the power consumption calculated by the power calculation unit 41 with a predetermined power threshold value. The predetermined power threshold value may be set based on, for example, the allowable temperature of the main semiconductor inside the device. Further, (350 × 36) / 1000 = 12.6 kW may be set based on the rated load of the arc welder 10 (for example, the load current is 350 A and the load voltage is 36 V).

The abnormality determination unit 40 determines an abnormality in the output of the load power based on the comparison result of the comparison unit 42. Specifically, in the abnormality determination unit 40, when the power consumption consumed within a predetermined unit time is larger than the predetermined power threshold value, an overload occurs due to the instantaneous rating exceeding, and the output of the load power is abnormal. It is determined that it is.

Then, when the abnormality determination unit 40 determines that the output of the load power is abnormal, the abnormality determination unit 40 outputs an abnormality signal to the output control unit 34. Based on the determination result of the abnormality determination unit 40, the output control unit 34, for example, stops the load power supply operation to stop the arc welder 10 in an emergency, or warns the operator by an alarm or an error message.

As described above, according to the arc welder 10 according to the present embodiment, it is possible to protect the arc welder 10 from overheating even when an instantaneously high load exceeding the rated standard load characteristic is generated.

<< Embodiment 2 >>
FIG. 2 is a schematic view showing the configuration of the arc welder according to the second embodiment. Hereinafter, the same parts as those in the first embodiment are designated by the same reference numerals, and only the differences will be described.

As shown in FIG. 2, the arc welder 10 includes a temperature detection unit 43 that detects the temperature around the equipment. A signal indicating the detected temperature detected by the temperature detection unit 43 is input to the abnormality determination unit 40.

The abnormality determination unit 40 calculates a difference value between the detection temperature detected by the temperature detection unit 43 and a predetermined temperature threshold value. The temperature threshold value may be set to the rated temperature around the device (for example, 40 ° C.). The abnormality determination unit 40 changes the power threshold value for abnormality determination based on the difference value between the detected temperature and the temperature threshold value.

Specifically, when the temperature around the device is low, for example, when the device is used in a cold region, switching occurs even if a high load exceeding the rating of the device occurs and the switching unit 22 inside the device generates heat. Since the unit 22 is cooled and the temperature is lowered, there is a margin before the temperature tolerance of the device is exceeded.

Therefore, the abnormality determination unit 40 changes so that the larger the difference value between the detection temperature around the device and the temperature threshold value, the larger the power threshold value for abnormality determination.

For example, when the temperature threshold is 40 ° C. and the temperature around the device is 30 ° C., the difference value is 10 ° C., but when the temperature around the device is 0 ° C., the difference value is 40 ° C. Therefore, when the difference value is 40 ° C., it is determined to be abnormal even though there is a margin in the temperature tolerance of the device by changing the power threshold value so that it is larger than when the difference value is 10 ° C. It can be suppressed. As a result, the device can be protected while stabilizing the output of the load power.

As described above, the present invention is extremely useful and industrial because it has a highly practical effect of being able to protect the device from overheating when a load higher than the rating of the device is generated. High availability.

10 Arc welder 11 Electrode 12 Base material 13 Machining load 31 Load current detection unit 32 Load voltage detection unit 34 Output control unit 40 Abnormality judgment unit 41 Power calculation unit 43 Temperature detection unit

Claims (3)

An arc welder that performs arc welding by supplying load power to a machining load that includes electrodes for arc welding and a base metal.
A load current detector that detects the load current supplied to the machining load, and a load current detector.
A load voltage detector that detects the load voltage supplied to the machining load, and
A power calculation unit that calculates the power consumption consumed within a predetermined unit time based on the load current and the load voltage.
An arc welder including an abnormality determining unit that determines that the output of the load power is abnormal when the power consumption is larger than a predetermined power threshold value. In claim 1,
It is provided with an output control unit that controls the supply operation of the load power with respect to the processing load.
The output control unit is an arc welder characterized in that when an abnormality is determined by the abnormality determination unit, the load power supply operation is stopped. In claim 1 or 2,
Equipped with a temperature detector that detects the temperature around the device
The abnormality determination unit calculates a difference value between the detected temperature detected by the temperature detection unit and a predetermined temperature threshold value, and changes the power threshold value based on the difference value. Machine.

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