JPS63299859A - Plasma arc cutting device - Google Patents

Abstract

PURPOSE:To eliminate the need for an air tank and pressure adjusting mechanism and to miniaturize the title device by interlocking the operation of the compressor for feeding the compressed air for cutting with the feed of the electric power for cutting. CONSTITUTION:A compressor 1 has no air tank, pressure detecter and pressure control device, and a mechanical safety valve releasing a pressure when it rises abnormally is simply provided on the pump exhausting a sucked air by compressing and pressurizing it. A power unit 2 has a pressure regulater 21 only, having the control circuit for actuating and stopping the compressor 1 by interlocking with the cutting start and stoppage. In starting the cutting, therefore, the feeding of the compressed air is started by actuating the compressor 1 and the feed of a cutting electric power is started by having a time delay until the compressed air is sufficiently injected from a cutting torch 51. In the case of the cutting completion, the structure of stopping the feed of the cutting power and the compressor 1 after the lapse of the cooling time of the torch 51 as well is taken.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of a plasma arc cutting device that cuts by supplying compressed air to a plasma arc section.

[Conventional device]

Conventionally, in the plasma arc cutting device 5, a cutting die, a source, and a compressed air source are provided separately, and the compressed air source is connected to a factory air piping or compressor via a pressure regulator and a solenoid valve. It was supplying the torch.

FIG. 5 shows an example of such a conventional device. In Figure 1, 1 is a compressor, and since a normal general-purpose compressor is used, in addition to the compression pump, it also comes with an air tank, a pressure detector, and a control circuit to stop the drive pump when the pressure inside the air tank reaches the set pressure. are doing.

2 is a power supply device that supplies power for cutting, and controls the start/stop of power supply and the supply of compressed air along with a power conversion circuit that converts commercial power to two direct currents with constant current or drooping characteristics suitable for plasma cutting. , a pressure regulator 21'j6 for compressed air, and a solenoid valve 22 for supplying and stopping the compressed air.

Reference numeral 5 denotes a known air plasma cutting torch connected to the power supply device 2 by a torch cable 4°, and the torch cable 4 includes a cutting cable conductor, a compressed air hose, and a switch 51 for commanding the start and stop of cutting. Contains signal cable for. Reference numeral 6 denotes an object to be cut, which is connected to the output terminal of the power supply device 2 through an electric cable 7. Reference numerals 8 and 9 are connected to a single-phase or three-phase commercial AC power source by connecting cables to the AC power source. Further, the compressor 1 and the power supply unit r112 are connected through an air hose 3.

In the device shown in the figure, pressing switch 51 turns on the power supply!
The control circuit 2 operates to open the solenoid valve 22 and supply compressed air to the cutting torch 5. After a predetermined time after the supply of compressed air is started, power for cutting is supplied from the power supply device 2 to the torch 5. An arc is generated and cutting of the workpiece 6 is started.When the switch 51 is released at the end of cutting T,
The supply of cutting power is stopped to cut off the arc, and after a predetermined period of time, the solenoid valve 22 is closed to stop the supply of compressed air.

[Problem that the invention seeks to solve]

Since the conventional equipment is configured as described above, the compressor for supplying compressed air is always in operation independently regardless of whether cutting work is being performed or not, and the compressor is in constant operation depending on the rise and fall of the pressure in the air tank. In order to keep this constant, a control circuit including a pressure setting device and a pressure detector for starting and stopping the pump is required, which is expensive and large due to the attached air tank. In addition, the power supply equipment requires a solenoid valve to supply and shut off compressed air, but since this solenoid valve includes moving parts, it has a relatively short lifespan and is expensive to maintain. There are drawbacks.

[Means for solving problems]

In order to solve the problems of the conventional device described above, the present invention has the following features:
It is designed to start and stop the compressor in response to the disconnection start/stop command switch.

[Effect]

In the present invention, when starting cutting, the compressor is first started to start supplying compressed air, and the supply of power for cutting is started with a time delay until the compressed air has sufficiently spouted out from the cutting torch. When the torch is finished, the cutting stop command immediately stops the supply of power for cutting, and after a certain period of time corresponding to the cooling time of the torch (
This is a small device with a structure to stop the compressor.
This is an inexpensive version designed for simplicity.

〔Example〕

FIG. 1 is an external connection diagram showing an embodiment of the present invention. In the figure, the compressor 1 does not have an air tank, a pressure detector, or a pressure control device, but simply compresses and pressurizes intake air, and then discharges the pump.It is equipped with a mechanical safety valve that releases pressure when the pressure rises abnormally. It is something that Further, the power supply device 2S has only a pressure regulator and does not have a solenoid valve for supplying or cutting off compressed air. Power bag! ! 2 also includes a control circuit for starting and stopping the compressor 1 in conjunction with the start and stop of cutting, and this control circuit sends a signal to the solenoid valve 22 in the conventional device shown in FIG. Cable 9 as start/stop signal of 1
What is necessary is to change the output to the compressor 1 at .

The other components 3 to 8 have the same functions as the conventional device shown in FIG. An example of the control circuit of power supply circuit 2 is
Shown in Figure 42.

In the figure, E is an AC type #CRI, CR2 is a relay, and CRla and CR2a are normally open contacts of each relay.

T1 is a delayed action instant return type timer, TR1a is a normally open contact of timer T1, T2 is an instantaneous action limited time return type timer, and TR2a is a normally open contact of timer T2. Reference numeral 23 denotes a power converter, which is a DC power supply circuit with known drooping characteristics or constant current characteristics, which generates an output when the starting terminals a and -b are closed, and when the circuit is opened, the output is cut off. 11 is the compressor motor.

12 is a compressor pump whose air output is supplied to the plasma torch 5 through a pressure regulator 21 and an air hose attached to the torch cable.

The operation of the embodiment shown in FIG. 1 equipped with the control circuit shown in FIG.
This will be explained with reference to the diagram in the figure. Torch 5≦When the attached switch 51 is pressed, the relay CRI is energized and the contact CR
1a is closed. Timer T is activated by closing contact CR-1a.
2 is energized, its instantaneous operation time-limited return contact T2a closes, and energizes relay CR2. Contacts CR2a and CR2a are closed by the excitation of relay CR2, and compressor motor 11
starts, and the pump 12 connected to the motor 11 starts supplying compressed air.

On the other hand, the timer T1 is also excited by the closing of the switch 51, and after the set time tl, the time limit contact Tla is closed and the power converter 2
3 is supplied to the DC output torch 5 and the object to be cut 6. In this state, the arc is started by a normal arc starting process (for example, a method in which a high frequency, high voltage is applied between the torch and the wave cutting object to break the insulation in the gap between the electrode and the cutting object to start the arc). This arc is narrowed down by a stream of compressed air supplied around the electrodes of the torch and becomes a plasma arc, which heats and melts the object to be cut. This heated and melted portion is partially oxidized and burned by the blown compressed air, and is blown away, so if the torch is moved along the object to be cut in this state, cutting will proceed.

Next, when the switch 51 is released at the end of the disconnection T, the relay C
RI and timer T1 are de-energized, and contacts CR1a and Tla are opened. Since the power converter 23 stops outputting due to the opening of the contact Tla, the plasma arc generated from the torch 5 disappears.

On the other hand, by opening relay contact CR1a, timer T2
.

becomes de-energized, and the contact T2a reaches the set time t from this point on.
Open after 2. Relay C is activated by opening contact T2a.
Contacts CR2a and CR2a of R2 are also opened, and the motor 11 and pump 12 are stopped.

Since the apparatus of the present invention operates as described above, compressed air begins to flow from the moment the switch 51 is pressed, as shown in FIG. 3, and its flow rate gradually increases. By setting the time limit t1 of the timer T1 to be approximately equal to the time required to increase the flow rate, it is possible to start cutting properly. Furthermore, when the switch 51 is opened, the arc is first stopped, and then the compressor 1 is stopped after the time t2 set by the timer T2, so the compressed air is stopped after sufficiently cooling the torch 5 that was heated during cutting. It turns out.

In the above, the control circuit 2 is configured by a relay and a timer, but these may be configured by combining semiconductor logic elements, and the function of the switch 51 is other than closing the circuit as shown in the example. Alternatively, after pressing once at start-up, the special stop number may be self-held by the circuit, and pressing the stop special number again will issue a stop command. This method can be easily implemented using a known flip-flop circuit.

FIG. 4 is a diagram showing another embodiment of the present invention, and in this figure, the compressor 1, which was referred to as the power supply device in FIG. 1, is built into the power supply device 1. By doing so, it becomes unnecessary to connect the air hose 3 and the motor control cord 9, which makes manufacturing and handling easier.

〔Effect of the invention〕

Since the present invention is as described above, the compressor for obtaining compressed air for cutting does not require a large and complicated mechanism such as an air tank or a pressure adjustment mechanism, and can be downsized. Furthermore, since the air tank is a pressure vessel, it is extremely expensive in order to ensure its pressure resistance and durability, and it accounts for an extremely large portion of the price of the compressor. By eliminating this air tank, a significant cost reduction can be achieved. Moreover, the control circuit required for the present invention is the same as that of the conventional device 1.
This is extremely useful in practice as there is almost no need to change anything that is already included.

[Brief explanation of drawings]

FIG. 1 is an external connection diagram of an embodiment of the present invention, and FIG. 2 is a connection diagram showing an example of a control circuit of the embodiment of the present invention. FIG. 3 is a diagram for explaining the operation of the embodiment shown in FIG.
FIG. 4 is a diagram showing another embodiment of the present invention, and FIG. 5 is a diagram showing an example of a conventional device. 1...Compressor, 2...Power supply device, 3...
Air hose, 4...torch cable, 5...cutting torch. 51...Start/stop switch agent Patent attorney Nakai

Claims (1)

[Scope of Claims] 1. In a plasma arc cutting device that processes uncut objects by supplying cutting power and compressed air to a plasma arc torch, the operation of a compressor for supplying compressed air for cutting is cut off. A plasma arc cutting device characterized in that it is linked to the supply of electric power. 2. In a plasma arc cutting device that processes a workpiece by supplying cutting power and compressed air to a plasma arc torch, there is a switch that commands cutting start and stop, and a start command signal from the switch. A first timer that starts a time limit accordingly, a second timer that starts a time limit in response to a disconnection stop command signal from the switch, and from the start command signal from the switch to the end of the time limit of the second timer. a compressor for supplying compressed air for cutting, which is driven for a period of time; and a power supply device for supplying cutting power between the torch and the object to be cut from the end of the first timer to the cutting stop command signal. A plasma arc cutting device equipped with 3. The compressor consists of an electric compression pump, a drive means for the pump, and attached piping, and does not have an air storage tank or automatic pressure adjustment means, and is operated continuously while receiving a drive signal. 3. The plasma arc cutting device according to claim 2, which is a compressor and includes a pressure regulating valve between the compressor and the cutting torch. 4. The plasma arc cutting device according to claim 2 or 3, wherein the compressor is built in a power supply device that supplies the cutting power.