JPH10244375A - Power supply device for plasma working - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the plasma working excellent in economy by controlling the current and the gas flow rate based on the change pattern of the gas flow rate and current to be supplied to a plasma torch and on the table of the time, the flow rate and the current of each pattern when main arc current is changed. SOLUTION: When the main arc current value is inputted in an input device 22, a control device 21 obtains the range including the set current, the table of the range to be obtained from a table stage part 21c and a change pattern of the flow rate and the current for each gas to be obtained from a pattern storage part 21b are read, and the time, the flow rate and the current set in the table are applied to each pattern. The control signal according to the flow rate and the current is transmitted to a gas feed part having solenoid valves 8d-10d, 15d to feed/step the gas to a plasma touch and flow rate regulators 8c-10c, 15c, and to a current setting part 17 and regulates the flow rate and the current. The plasma torch can be driven under the optimum condition corresponding to the preset target current value in an automatic operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for plasma processing used for plasma processing such as plasma cutting and plasma welding.

[0002]

2. Description of the Related Art While supplying gas around an electrode provided on a plasma torch, a current is supplied between an electrode and a nozzle or between an electrode and a workpiece to convert the supplied gas into a plasma to produce a workpiece. A so-called plasma processing is performed in which the workpiece is melted by the sprayed plasma arc and the workpiece is melted and cut or welded.

In performing plasma processing, a power supply for supplying a constant current between an electrode and a nozzle or between a workpiece and a gas supply for supplying a predetermined flow rate of plasma gas around the electrode. Equipment is essential. For this reason,
A power supply device for plasma processing in which each of the above devices is incorporated in the same frame is commercially available and widely used.

[0004] In plasma processing, particularly in oxygen plasma cutting, a large amount of wear occurs on the electrode when a plasma arc is generated and when the plasma arc is stopped. In general, gas is supplied (pre-flow, after-flow), and the supply and stop of these gases are controlled at delicate timing to reduce electrode consumption as much as possible. The supply and stop of the power supply and gas are controlled by a control unit incorporated in the power supply device for plasma processing.

In a commonly used power supply device for plasma processing, since the processing capability is small, the workpiece is always processed at the maximum current, so that the gas flow rate adjustment pattern is single. Therefore, the flow rate of the gas can be adjusted by the needle valve and can be opened and closed by the solenoid valve, and the control of the power supply device for plasma processing can be performed by a so-called sequence control. For this reason, the power supply device for plasma processing is provided with a sequence control panel combining a relay, a timer, and the like that output an open / close signal of an electromagnetic valve provided in a gas supply path.

In the plasma processing, the current value is proportional to the thickness of the workpiece. Further, since the processing speed is high in plasma processing, the development of a power supply device for plasma processing having higher processing capability is required. Recently, a power supply having a current value of 400 A is being put to practical use.

[0007]

In the power supply device for plasma processing having a large current value, the processing capability is increased. Therefore, there is a possibility that the workpiece is processed with a current value smaller than the maximum current value. In this case, the processing itself can be performed even if the supply amount of the gas and the timing of supply and stop are uniquely controlled in accordance with the specification of the maximum current value, but when processing at a small current value, the flow rate of the gas is reduced. When it becomes excessive, a problem that a plasma arc, particularly a pilot arc is not formed smoothly, and a problem that gas is wasted are generated.

In order to solve the above problem, it is necessary to adjust the gas flow rate and the timer and the like every time it is necessary to perform machining with a current value smaller than the maximum current value. There is a possibility that a setting error or the like may occur.

SUMMARY OF THE INVENTION An object of the present invention is to provide a plasma processing power supply device capable of changing a gas supply amount and supply / stop timing in accordance with the setting of a current value.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a power supply device for plasma processing according to the present invention has a function of supplying a single or a plurality of gases to a plasma torch when performing plasma processing, a pilot arc and A power supply device for plasma processing having a function of controlling a current for forming a main arc, wherein the power supply device is provided for each of a single gas or a plurality of gases and controls a valve for supplying and stopping a gas to a plasma torch and a flow rate. Gas supply means having a flow rate adjustment unit, current adjustment means for adjusting a current value applied to the electrodes of the plasma torch, and current supply means having an opening / closing unit for energizing and stopping, and a single or plural gases supplied to the plasma torch A gas change pattern that is set for each and serves as a reference for a change in flow rate over time, and a reference for a change in pilot arc forming current and a main arc forming current. A pattern storage unit that stores a current change pattern, and a time value and a flow value that define a gas change pattern set for each of the single or multiple gases and a time value and a current value that define the current change pattern in advance. A table storage unit for storing a plurality of main arc current ranges corresponding to the set values, an input unit for inputting a main arc current value for operating a plasma torch, and the gas supply according to the input main arc current value And a control device having a control unit for controlling the power supply means.

In the above-mentioned power supply device for plasma processing (hereinafter simply referred to as "power supply device"), the gas supply means has a valve for supplying and stopping gas to and from the plasma torch and a flow rate adjusting member for adjusting the flow rate. Since the means has a current adjusting unit for adjusting the value of the energizing current and an opening / closing unit for energizing and stopping, the current value can be adjusted according to the intended processing, and the gas flow rate according to the current value can be adjusted. Can be adjusted.

The control device for controlling the power supply device includes a gas change pattern of a flow rate change with time set for each gas based on the start and stop signals of the plasma torch, and a current change of a pilot arc and a main arc current. A pattern storage unit in which a pattern is stored, and a time value and a flow value that define a gas change pattern corresponding to a main arc current value;
A table storage unit that stores a time value and a current value that define a current change pattern, an input unit that inputs a desired current value, and a control unit that controls gas supply means and energization means according to the input current value , The gas flow value and the time value required to optimally operate the plasma torch according to the input main arc current value, and the pilot arc,
It can be controlled by the current value and time value of the main arc.

In the above power supply device, when the control unit inputs the main arc current value for operating the plasma torch by the input unit, the gas in the main arc current range including the main arc current value input from the table storage unit. It is preferable that a time value and a flow rate value defining a change pattern and a time value and a current value defining a current change pattern are read, and the read data is output to the gas supply means and the current supply means.

By configuring the control unit as described above, when a main arc current value is input by the input unit, the time value, the flow value value, the current time value, and the current value of the gas in the main arc current range including the current value. The value can be read and each signal can be output to the gas supply means and the current supply means. That is, when a target main arc current value is input by the input unit prior to the start of the plasma processing, a gas change pattern corresponding to the main arc current value is read from the control unit, and a time value and a flow rate value defining the pattern are read out. A signal can be output to the gas supply means, a current change pattern can be read out, and a signal of a time value and a current value defining the pattern can be output to the energizing means. Therefore, it is possible to drive the plasma torch under optimum conditions corresponding to a preset target current value by an automatic operation, and to perform desired processing such as cutting or welding on the workpiece in an economical manner.

In the above power supply device, the input section inputs a main arc current value for operating the plasma torch, and inputs information defining a change pattern of the plasma gas or the main arc current. Defines the current value and the time value and flow rate value defining the gas variation pattern of the main arc current range stored in the table storage unit with reference to the information defining the variation pattern of the input plasma gas or main arc current. It is preferable to read out the time value and the current value, output the read data to the gas supply means and the energizing means, and control the main arc current to be set to the input main arc current value.

In the above power supply device, the input section inputs a main arc current value for operating the plasma torch and inputs a gas change pattern such as a flow rate of plasma gas and an initial current of the main arc or information defining a current change pattern. In the control unit, the time value and the flow rate value that define the gas change pattern of the main arc current range corresponding to the information from the table storage unit based on the input information and the time value and the current value that define the current change pattern Reading and outputting the read data to the gas supply means and the energizing means, and setting the main arc current value of the plasma torch irrespective of the value of the main arc current in the designated main arc current range. I can do it.
That is, it is possible to separately set the main arc current value, the gas flow value and the time value, and the pilot arc current value and the time value necessary for performing the intended processing. Therefore, the power supply can be manually operated.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the power supply device will be described below with reference to the drawings. FIG. 1 is a schematic diagram illustrating a configuration of a plasma cutting device as an example of a plasma processing device, FIG. 2 is a diagram illustrating a piping system of a power supply device, FIG. 3 is a block diagram of a control system, and FIG. FIG. 5 is a diagram illustrating an example of a current change pattern, and FIG. 5 is a diagram illustrating an example of a table of a main arc current range stored in a table storage unit.

The power supply device according to the present invention sets the current value equal to or less than the maximum current value to operate the plasma torch, and operates the plasma torch efficiently at the set current value. The configuration is such that the flow rate and time of the gas flowing at the time of starting and stopping can be set under appropriate conditions.

The configuration of a plasma cutting device as an example of a plasma processing device will be schematically described with reference to the drawings, and the configuration of a power supply device A according to the present embodiment will also be described.

The plasma cutting apparatus shown in FIG. 1 includes a power supply device A and a cutting torch B. In the present embodiment, the cutting torch B is configured as a transfer-type plasma torch, and is configured to flow the primary shield gas and the secondary shield gas around the plasma gas. That is, the cutting torch B has an electrode 1 in which an electrode material 1a is embedded at the center, and a nozzle 2, a primary shield nozzle 3, and a secondary shield nozzle 4 are provided on the same axis around the electrode 1. ing.

The electrode 1 and each of the nozzles 2 to 4 are mounted on a torch main body 5, respectively.
A current supplying member 6 for supplying current to the nozzle 2, a current supplying member 7 for supplying current to the nozzle 2, a plasma gas flow passage 8 for supplying a start gas and a plasma gas to a plasma gas passage 8a formed between the electrode 1 and the nozzle 2, Shield nozzle 3
The primary shield gas flow passage 9 through which the primary shield gas flows through the primary shield gas passage 9a formed between the secondary shield gas passage 9a and the secondary shield gas passage 10a formed between the primary shield nozzle 3 and the secondary shield nozzle 4 The secondary shield gas flow passages 10 through which the shield gas flows are formed respectively.

The current-carrying members 6, 7 formed on the torch body 5
Are connected to the power supply A via a cap tire, and the gas flow passages 8 to 10 are connected to the power supply A via a hose.
Is connected to The workpiece C and the power supply A are connected via a cap tire 11.

A primary power supply is connected to the power supply device A via a cap tire 12, an oxygen gas supply device 14 is connected via a hose 13, and a start gas such as nitrogen gas or air is further connected via a hose 15. The supply device 16 is connected. The oxygen gas supply device 14 is configured by a supply unit 14a such as a cylinder or a factory pipe and a pressure regulator 14b,
The start gas supply device 16 includes a supply unit 16a such as an air compressor when the start gas is air and a cylinder and the like when the start gas is nitrogen gas, and a pressure regulator 16b.

Next, the configuration of the gas supply piping system and the power supply system in the power supply A will be described with reference to FIG.

As shown in FIG. 1A, the piping connected to the hose 13 for supplying oxygen gas is composed of three systems of a plasma gas flow passage 8, a primary shield gas flow passage 9, and a secondary shield gas flow passage 10. Each of the pipes 8b to 10b is divided into pipes 8b to 10b. In each of the pipes 8b to 10b, a mass flow meter or the like having a function of setting a flow rate according to a control signal and detecting a mass of the flowing gas to adjust the flow rate of the gas is provided. Flow controller 8c
To 10c, and solenoid valves 8d to open and close each pipe 8b to 10b
10d is provided. The pipe 15b connected to the hose 15 for supplying the start gas is connected to the plasma gas flow passage 8 via a flow controller 15c such as a mass flow meter and an electromagnetic valve 15d for opening and closing the pipe 15b.

In this embodiment, the primary shielding gas and the secondary shielding gas are separately supplied to the cutting torch B, and oxygen gas is used as each shielding gas. However, the present invention is not limited to this configuration of the shielding gas.

That is, the present invention can be applied to a torch that does not use a shielding gas, and the shielding gas is not essential. Further, even when applied to a torch using a shielding gas, a plurality of shielding gases are not necessarily required, and only a primary shielding gas may be used, or a tertiary or higher shielding gas may be used. . Further, in each shield gas, oxygen gas is generally used as a primary shield gas, but a gas other than oxygen gas, for example, air may be used as a secondary or higher shield gas. Alternatively, a single gas may be supplied to the torch as a shielding gas, and this gas may be divided into a plurality of passages inside the torch and used as a plurality of shielding gases.

As shown in FIG. 2B, there is provided a current setting member 17 which is connected to the primary power supply via the cap tire 12 and sets a current according to a control signal.
The current setting member 17 is connected to the conducting members 6 and 7 and the cap tire 11. In particular, a high-frequency circuit 18 is provided on the current-carrying member 7 connected to the nozzle 2. Reference numeral 19 denotes a switching member that switches between the electrode 1 and the nozzle 2 to form a pilot arc and then to switch between the electrode 1 and the workpiece C to form a main arc.

Next, the control system of the power supply A will be described with reference to FIG. In the figure, reference numeral 21 denotes a control device which stores a microprocessor 21a serving as a control unit, a supply pattern of each gas based on a start signal and a stop signal of the cutting torch B shown in FIG. The pattern storage unit 21b stores, in a table, gas control data such as flow rate values, injection timings, and times of the respective gases corresponding to the set current values, and data such as energization times for the nozzles and switching timings from the nozzles to the workpiece. And a table storage unit 21c that stores the information as

Reference numeral 22 denotes an input device, and an interface 23
When the workpiece C is cut by the cutting torch B, an optimum current value is input according to the thickness of the workpiece C, or the table storage unit 21c
Is used to input information such as the flow rate of the plasma gas and the initial current of the main arc for designating the table stored in. Reference numeral 24 denotes a switch for instructing start and stop of the cutting torch B.

The control device 21 has an automatic operation mode and a manual operation mode, and is configured so that a desired mode can be selected by switching a switch (not shown). In the automatic operation mode, when the main arc current value for operating the cutting torch B is input by the input device 22, the main arc current including the main arc current value input from the table stored in the table storage unit 21c in advance is set. Read the data in the range and read each gas supply device 1
4, 16 and the current setting unit 17 are automatically controlled.

In the manual operation mode, a main arc current value for operating the cutting torch B is inputted by the input device 22, and a plasma gas is supplied to the main storage unit 21c to specify the main arc current range stored in the table storage unit 21c. When information such as a flow rate value or an initial current value of a main arc is input, data of a main arc current range corresponding to the input information is read out to control the gas supply devices 14, 16 and the current setting unit 17. Therefore, even when the main arc current value for operating the cutting torch B is different from the designated main arc current range, the operation is performed.

The power supply unit A includes, in one frame, gas pipes 8b to 10b including solenoid valves 8d to 10d and flow controllers 8c to 10c, a current setting member 17, a high-frequency circuit 18, and a switching member 19. The power supply unit and the control device 21 are arranged and assembled, and are covered with a cover. But,
The configuration is not necessarily limited to the above-described configuration, and the gas pipes 8b to 10b, the power supply unit, and the control device 21 may be arranged in different frames.

Next, control patterns of each gas and current when the workpiece C is cut by the power supply device A and the cutting torch B configured as described above will be described with reference to FIG.

In the figure, when an ON signal is generated from the switch 24, the start gas solenoid valve 15d is simultaneously generated with this signal.
Is opened, and the pre-flow (T1) of the flow rate VR1 is executed. The preflow time is set in consideration of the length, diameter, and the like of the plasma gas flow passage 8. That is, the time is set in consideration of the time required for the start gas to reach the plasma gas passage 8a formed between the electrode 1 and the nozzle 2 after the solenoid valve 15d is opened.

When the preflow time T1 of the start gas elapses, the high-frequency circuit 18 operates for a fixed time, and at the same time, a pilot arc current of VR5 starts between the electrode 1 and the nozzle 2 to convert the start gas into plasma. The formed pilot arc is formed. The control after a lapse of a certain time Tc from the activation of the high frequency circuit 18 is performed starting from this time, that is, T1 + Tc from the ON signal of the cutting torch B.

Starting from Tc, the solenoid valves 9d and 10d of the primary shield gas and the secondary shield gas are opened. The main arc initial current VR is supplied between the electrode 1 and the workpiece C at the same time.
6 is energized. Thereby, the pilot arc is ejected from the secondary shield nozzle 4 of the cutting torch B, and an initial main arc is formed between the pilot arc and the workpiece C.

When the time T3 has elapsed from Tc, the solenoid valve 8d of the plasma gas is opened, and a plasma arc is formed in which the start gas contains the oxygen gas at the flow rate VR2. At about the same time as the supply of the plasma gas (after the passage of the time T6), the energization between the electrode 1 and the nozzle 2 is stopped.
Next, after a lapse of time T2, the start valve is stopped by closing the solenoid valve 15d. Thereby, the electrode 1 and the nozzle 2
Oxygen gas is supplied to the plasma gas passage 8a formed between them, and a main arc in which the oxygen gas is turned into plasma is formed.

After a lapse of time T7 starting from Tc, the main arc current is changed from the initial current to the set current value for a time T7.
By raising over eight, a stable main arc is formed.

The switch 24 turns off the cutting torch B.
When the signal is generated, the supply of the main arc current is stopped, and the after-flow by each gas is executed starting from this signal. That is, when time T4 has elapsed from the OFF signal, the electromagnetic valve 8d is closed to stop the plasma gas, and when time T5 has elapsed, the electromagnetic valves 9d and 10d are closed to stop the primary shield gas and the secondary shield gas. I do.

The preflow operation and the afterflow operation are widely performed as operations for reducing the consumption of the electrode 1 of the cutting torch B using oxygen gas as a plasma gas.

As described above, the change pattern of each gas flow rate and the change pattern of the current are set in advance and the pattern storage unit 21 is set.
b, and the time T1 to T
8 and the flow rates VR1 to VR4 and the currents VR5 and VR6, it is possible to execute desired control.

Next, an example of a table in which the main arc current is divided into a plurality of ranges will be described with reference to FIG.

In this embodiment, the power supply A has a maximum current of 40.
It has a capacity of 0 A, and divides this current value into four ranges of 100 A from the maximum current value to the minimum current value. Times T1 to T8, flow rates VR1 to VR4, and currents VR5 and VR
6 is set.

The above table is stored in the table storage section 21c, and an optimum main arc current value is input from the input device 22 to the control device 21 according to the specification such as the thickness of the target workpiece C.
In the automatic operation mode, the control unit 21a reads out information of the table including the input main arc current value and outputs data, respectively. By inputting the current value and designating the table, the control unit 21a reads the designated table and outputs data.

Then, the ON signal from the switch 24 and the OFF signal
A start gas, a plasma gas, a primary shield gas, a secondary shield gas, a pilot arc current, and a main arc current supplied to the cutting torch B using a signal as a trigger can be controlled in accordance with respective set patterns.

The control for adjusting the flow rate of each gas is performed by controlling the control unit 21 in accordance with the gas flow rate with respect to the control units of the flow rate regulators 8c to 10c and 15c provided corresponding to each gas. It is transmitted and the flow rate is set according to this signal. The table in the present embodiment shows the maximum current A of the power supply A.
Is divided into four ranges. However, the present invention is not limited to this number of divisions, and may be divided into eight steps for each 50A or may be divided into less than four ranges.

The procedure for cutting the workpiece C using the power supply unit A and the cutting torch B set as described above will be described. Prior to the start of cutting, when a set current value capable of forming a main arc necessary for performing a target machining by the input device 22 is input, the control device 21 obtains a range including the input set current value, A table corresponding to the range obtained from the table storage unit 21c is read, and a change pattern for each gas and a current change pattern are read from the pattern storage unit 21b, and the time T1 set in the table is read.
To T8, flow rates VR1 to VR4, and currents VR5 and VR6 are applied to each pattern.

The control signals corresponding to the read flow rates VR1 to VR4 and the currents VR5 and VR6 are transmitted to the opposing flow regulators 8c to 10c and 15c and the current regulator 17, and the respective flow regulators 8c to 10c and 15c. And the current adjusting unit 17 adjusts the flow rate and the current according to the control signal.

Thereafter, when the switch 24 is operated to generate an ON signal, the solenoid valve 8c for supplying and stopping each gas is executed.
10c and 15c are controlled according to a change pattern for each gas starting from the time T1 starting from the ON signal and starting from T1 + Tc after the elapse of the time Tc. At the same time, the current is controlled in accordance with a change pattern for each current starting from the time T1 and the time obtained by adding Tc to the time T1.

Therefore, the workpiece C can be cut by moving the torch B in a desired direction in the process of controlling each gas and current for the cutting torch B. When the cutting is completed and the OFF signal of the cutting torch B is generated, the supply of the main arc current is stopped, and thereafter, the supply of each gas is stopped.

[0052]

As described above in detail, in the power supply device for plasma processing according to the present invention, the change pattern of the gas flow supplied to the plasma torch and the change pattern of the current are stored and the main arc current is changed. A time value, a flow value, and a current value that define each pattern at the time are tabulated and stored, a main arc current corresponding to actual processing is set, a change pattern of each gas and current is read, and a main current including the set current is read. By reading a table of the arc current range or a designated table and applying the table to the change pattern, each gas and current supplied to the plasma torch can be controlled.

For this reason, when the plasma processing power supply device is operated at a current value smaller than the maximum current value, the flow rate of each gas can be optimally controlled with respect to the set current value. Therefore, it is possible to perform plasma processing with excellent economic efficiency.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of a plasma cutting device as an example of a plasma processing device.

FIG. 2 is a diagram illustrating a piping system of the power supply device.

FIG. 3 is a block diagram of a control system.

FIG. 4 is a diagram illustrating an example of a gas change pattern and a current change pattern.

FIG. 5 is a diagram showing an example of a table of a main arc current range stored in a table storage unit.

[Explanation of symbols]

 Reference Signs List A power supply device B cutting torch C work piece 1 electrode 2 nozzle 3 primary shield nozzle 4 secondary shield nozzle 5 torch body 6, 7 conducting member 8 plasma gas flow path 9 primary shield gas flow path 10 secondary shield gas flow path 11 , 12 Cap tire 13, 15 Hose 14 Oxygen gas supply device 16 Start gas supply device 8c-10c, 15c Flow controller 8d-10d. 15d Solenoid valve 17 Current setting section 18 High frequency circuit 19 Switching member 21 Controller 21a Microprocessor 21b Pattern storage section 21c Table storage section 22 Input device 23 Interface 24 Switch

Claims (3)

[Claims] A power supply device for plasma processing having a function of supplying a single or a plurality of gases to a plasma torch and a function of controlling a current for forming a pilot arc and a main arc when performing plasma processing. Gas supply means having a valve provided for each of a single gas or a plurality of gases for supplying and stopping gas to the plasma torch, and a flow rate adjusting unit for adjusting a flow rate, and adjusting a current value applied to an electrode of the plasma torch. Energizing means having a current adjusting unit and an opening / closing unit for energizing and stopping, a gas change pattern which is set for each of a single gas or a plurality of gases supplied to the plasma torch and serves as a reference for a flow change with time, and a pilot arc forming current A pattern storage unit for storing a current change pattern serving as a reference for a current change for forming a main arc and a current change pattern for each of the single or plurality of gases. A table storage unit that stores a time value and a flow rate value that defines a gas change pattern set in a time value and a current value that defines a current change pattern in association with a plurality of preset main arc current range values; An input unit for inputting a main arc current value for operating the plasma torch, and a control device having a control unit for controlling the gas supply unit and the energizing unit according to the input main arc current value are provided. Power supply for plasma processing. 2. When the control unit inputs a main arc current value for operating a plasma torch by an input unit, the control unit defines a gas change pattern in a main arc current range including the main arc current value input from a table storage unit. 2. A plasma processing apparatus according to claim 1, further comprising reading a time value and a current value defining a time value and a flow value to be performed and a current change pattern, and outputting the read data to the gas supply means and the current supply means. Power supply. 3. The input unit is for inputting a main arc current value for operating a plasma torch, and for inputting information defining a change pattern of a plasma gas or a main arc current, and a control unit is configured to input the plasma. The time value and the flow rate value defining the gas change pattern of the main arc current range stored in the table storage unit based on the information defining the change pattern of the gas or main arc current, and the time value and the current value defining the current change pattern And reading the read data to the gas supply means and the energizing means and controlling the main arc current to the input main arc current value. Power supply device for plasma processing.