HU209714B - Connection arrangement for producing plasma arc - Google Patents

Abstract

Air jet is started, the pilot current capacitor is charged to the pilot voltage, the plasma arc is ignited by the superposition of a high frequency, high voltage signal and finally the plasma arc is ''blown over'' to the workpiece. - The equipment comprises main transformer (T1), pilot current condenser (PC), rectifier (PE), ferrite transformer (TF), condenser block (CP), high frequency, high voltage producing transformer (TH), spark gap (52K), condenser block (CS), the transformer (TH) is connected to the control transformer (TV) via contacts (KN), which control the primary circuit ignition timing. The sec. winding of the ferrite transformer (TF) is connected between the pilot voltage supply and the cup (KU). - (Dwg.1/1)

Description

Scope of the description: 10 pages (including 3 sheets)

EN 209 714 B and its output points (c, D) are connected to a relay unit (J) which is connected to the switching unit (KE), and the output connection points (X, Y) of the second secondary coil of the control transformer (TV) are high frequency. connected to a high-voltage transformer (TN) at the contact switch (KN1) of the ignition time switch, and one of the transformer (TN) coils of the condenser block (CP) at the operating spark (SZK), the other at the condenser block (CS) ferrite core transformer (TF) primer is connected to one end of the coil of the latter transformer (TF) by one end of the cap (KU), the other end is connected to the positive polarity connection point (P) of the serial switching capacitor (PC) and discharge resistor (PR), which is a serial connection end of arc arc electrode (I) and rectifier (PE) while the pilot current capacitor (PC) and the discharge resistor (PR) are connected in series with the serially connected contacts (KPS2, KPS3) of the pilot current condenser discharge switch (KE) on the one hand and the capacitor block (CB) on the other side of the capacitor group. coupled to the positive polarity connection point (P) of said positive polarity (P) and to the positive polarity (+) of the rectifier (PE), the serially connected work contacts (KP2, KP3) of the pilot current capacitor (KP) arranged in the switching unit (KE) are inserted; the positive polarity connection point (+) of the rectifier (PE) also forms a common point with the clamping device, the arc-generating electrode (I) and the cap (KU) are connected to a safety spark (BSZ).

Field of the Invention The present invention relates to a circuit arrangement for the production of a plasma arc, in which an ionized space between an electrode and a cap in a gun is formed and then a plasma arc is formed. In the switching arrangement, a rectifier connected to a main transformer connected to an electrical network, followed by an arc-forming electrode connected to it, and a pilot current generating circuit, and a high-frequency high-voltage generating circuit connected to the latter.

The field of application of the subject matter of the present invention is any place where the so-called prior art is known. flame cutting, or arc cutting.

The use of plasma cutting has spread in recent years, as it has significant advantages over flame cutting, e.g. less heat input into the structure of the metal to be cut, which results in less energy consumption at the same time, while the size accuracy of the metal structure is better maintained due to lower heat input, less deformation.

Previously used plasma cutting devices were operated with a mixture of argon and hydrogen gas, which could be realized with complex and expensive gas mixing devices. In addition, air plasma cutting at irregular times has spread. In the case of airplane cutting equipment, however, a lighter and more complex ignition circuit had to be implemented. Ignition circuits are ancillary circuits with electronic circuits that provide a stable pilot current. The disadvantage of these is that the high current required for the ignition and the high frequency high voltage occurring are often destroyed.

U.S. Pat. No. 4,594,498 discloses the use of argon and carbon dioxide in a specified mixing ratio. pulse welding equipment - not cutting - is described. This device does not generate a pilot current, there is no pilot current capacitor, but high-voltage high voltage is connected to the pulse generator-controlled pulses.

Ignition is made to touch between the automatic wire to be conveyed and the object being held. This apparatus is preferably e.g. suitable for welding aluminum objects.

U.S. Pat. No. 4,225,769 discloses so-called. plasma welding equipment - not cutting - is described. The pilot current is generated from a power source, there is no pilot current condenser, and a plasma transformer controlled auto transformer is used to produce the plasma arc and then the device is welded to the plasma state. Due to the design of the device, its preferred application is e.g. Welding Welding or Relatively Low Power Welding.

In known equipment for producing plasma arc, the high-frequency high-voltage, inevitable, ionized space, radiation, high pilot current, etc., inevitably occur. Despite significant filtering, they have a detrimental effect on and often destroy the operation and protection circuits of semiconductor electronic circuits. However, after frequent switching on and off, a cap burns in the cap and these craters greatly reduce the cutting quality.

At the same time, due to the high energy of the pilot stream, the catalyst materials in the gun cap degrade the safety of the ignition as they wear out very quickly.

It is an object of the present invention to overcome the disadvantages described and to provide a switching arrangement that reduces the duration of high-energy ignition, uses less catalyst material while substantially increasing the safety of the ignition and operation by creating circuitry that does not respond to power changes and interference.

The invention is based on the discovery that the firing of the plasma arc with a condenser pilot circuit and the relay, switch and actuator reacting only to the actuating switch signal for operation of the apparatus is performed.

The circuitry of the individual circuits is determined by a switching arrangement that is absolutely necessary and sufficient, with significant energy savings, and high ignition and operating safety without reacting to power changes and external interference. the ignition time and catalyst wear are significantly reduced.

In the switching arrangement according to the invention, a control transformer is connected to the switching unit, the connection points of one of its secondary windings being connected to the solenoid valve via the air valve closure contact and the air pressure switch contact and the thermal switching contact on the other, the output points of the latter being connected to a relay unit operable in connection with the switching unit. and also the output connection points of the second secondary coil of the control transformer are coupled to the high-frequency high-voltage transformer at the contact of the ignition time switch, and a condenser block is coupled in parallel with the secondary winding of the transformer, and one of the capacitor block outlets at the end of the primary coil of the ferrite core transformer. joins which the secondary transformer of the latter transformer is connected to one end of the cap, the other end is connected to the positive polarity connection point of the serial current of the condenser and discharge resistor, the other end of the serial circuit is connected to the common point of the arc generating electrode and the rectifier, while the pilot current is connected in parallel with the serial connection of the capacitor and the discharge resistor. on the one hand, the serially connected contacts of a pilot current condenser discharge switch arranged in the switching unit, on the other hand, a capacitor block built from a capacitor group, between the said positive polarity connection point and the positive polarity connection point of the rectifier, the pilot circuitry capacitors of the pilot current arranged in the switching unit are connected in series with the rectifier a positive-polarity point also has a joint point with a clamping mechanism this is a spark gap between the arc electrode and the cap.

The invention will now be described with reference to the drawings. In the drawings, Fig. 1 shows the circuit arrangement for producing the plasma arc, Fig. 2 shows the relay unit, Fig. 3 shows the switching circuit part of the switching unit, and Fig. 4 shows the ideal time course of the switching process. 1-3. FIG.

In the coupling arrangement for producing the plasma arc shown in Figure 1, the primary side of the TI main transformer having double primary coils is coupled to the terminals R, S, T through the KE switching unit.

The output of the PE rectifier output of the D1 ... D6 diodes connected to the secondary part of the ATI main transformer is connected to an arc electrode I. The primary coil of the TV control transformer is connected to S °, T ° phase terminals via the K switch K5 of the KE switch unit. One of the secondary coils A, B of the TV control transformer, on the one hand, by opening an air valve KL switch (see Figure 3) through the work contact of the KL1, by inserting an MSZ solenoid valve, on the other hand, by inserting the working contact of the air pressure switch NK and the thermal contact jai between the AC side of the JE actuator. They are connected to relay J. The relay J is connected to the KE switching unit by a two-way connection.

The second secondary winding of the TV control transformer XY connecting points to the TN transformer of the high frequency high-voltage unit NF is connected via a KN1 contact switch of the ignition time switch KN (see Figure 3) with a secondary coil coupled to the CP capacitor block. The latter secondary coil is connected to one of the branches by a spark gap SZK on one branch and through a block of CS capacitor blocks on the other end of a ferrite core TF transformer. One end of the secondary winding of the TF transformer is connected to the KU cap, and the other end is connected to the positive polarity P connection point of the PC pilot current capacitor and PR discharge resistor, the other end of which is connected to the common, negative polarity - connection point of the arcing electrode I and the PE rectifier.

In parallel with the serial connection of the PC pilot current capacitor and the PR discharge resistor, the pilot current capacitor discharging KPS switch (see Fig. 3) arranged in the KE unit is connected to the serially connected KPS2, KPS3 contacts, and a CB capacitor block is connected. Between said positive polarity P point and the positive polarity + connection point of the PE rectifier, the pilot current capacitor charge KP switch in the KE switching unit (see Figure 3) is connected to the serially connected KP2, KP3 contacts, and the positive polarity + connection point is also clamped. structure. Between the arcing electrode I and the KU cap, there is an SPS spark gap. In the KE switching unit, there is a non-sketched main power switch, which is connected to the S °, T ° phase connector by means of the ON switch, which can be switched on by means of the ON button, and its self-maintaining state through the contact circuit K4, while the terminals R, S, T are OFF, K2, K3. connected to contacts. With the K5 contact, the TV control transformer is connected to the T ° -S ° phase connectors, where two M _b M ₂ air motors are connected between the S ° phase connector and the O terminals. The connection points R ', S', Τ ', or R', S ', T' of the KF switch (see Figure 3) arranged in the KE switch unit (see Figure 3) are also one of the primary coils of the primary transformer TI. or other primary connection points. The capacitor block CB, CS, CP is preferably a series of two capacitor connections 3

HU 209 714 ából or their parallel connection. Fig. 2 shows a CSZ filter capacitor in one of the branches between the C and D connection points of the J relay unit shown in Fig. 2, the other branch on the NU starter switch contacts in the gun and the leading JPS relay in the third branch with the anode of the positive polarity coupling D13, a pilot current condenser discharge JPS relay. Serial connection of PS1 working contact and delay JL relay, fourth branch D14 pilot current capacitor discharger JPS relay PS2 work contact, R3 resistor, main transformer starter JF relay serial, fifth branch D15 diode, main transformer starter JF relay FI contact, R5 resistor, main transformer RF starter JF relay F2 work contact and pilot current capacitor charger JF relay serial connection, sixth branch Dl6 diode, pilot current capacitor charger JP relay Pl work contact, R8 resistor R7 resistor, pilot bar Amp condenser charger JP relay closed contact P2 and high voltage generator starter JN relay is connected.

The diodes D13, D14, D15, D16 connect with their anodes to the positive polarity C point. Diodes D7, D8, D9, D11, D12 connected to the negative polarity D-point are connected in parallel with their anodes via JPS, JL, JF, JP, JN relays. In parallel with the delayed JL relay, a serial connection of a resistor R2 and a capacitor CL1 is connected. In parallel with the main transformer trigger JF, a serial cassette coupling of a D10 diode connected to a CPS capacitor is connected to its cathode, and a serial connection of the resistor JPS relay PS3 of the resistor JPS relay is connected parallel to the CPS capacitor. A CF capacitor is connected between the pilot current charger and the relay JP resistor R6, the common point of the connected F2 working contact and the R5 resistor, and the negative polarity D point.

In parallel with the high-voltage starter JN relay, a resistor R9, and a CN2 capacitor are connected in parallel, the JN relay, the serially connected contact P2 and the resistor R7 are bridged by a CN1 capacitor. Capacitors Cl, C2, C3, C4, C7, and C5, C6 are connected in parallel with the NU starter switch, the working contacts PS1, PS2, F2, Pl, and the FI, P2. Fig. 3 shows the serial connection of the pilot current condenser discharge KPS switch and the main transformer starter KFF switch KF1 to the KPS1 and KFF1 working contacts controlled by the KPS1 and KFF1 switches in one branch of the KE switching unit, with the pilot flow capacitor discharging JPS relay in the second branch PS4 workstation pilot current condenser discharge KPS serial coupling with KPS switch inlet coil, third line delay JL relay JL1 working contact air valve opening KL coupling with feed coil, fourth branch main transformer starter JF relay F3 work contact and KL air valve KL switch KL2 work contact and main transformer start KFF switch Serial connection of feeder coil, Fifth branch, pilot flow capacitor P3 of pilot pilot capacitor JP3 s KP serial coupling with the retractor coil, sixth branch of the high-voltage starter JN relay JN1 working contact and pilot current charge KP switch KP1 working contact is connected to the pick-up switch CN switching time switch.

The circuit arrangement for producing the plasma arc according to the flow diagram of FIG. 4 is as follows.

By actuating the mains switch and the main switch, operated by the ON button of the two-phase switch K, preferably by the addition of an additional controlled KF main switch, the mode selection switch receives the electrical voltage which is switched to the first or second primary coils of the main transformer TI according to the load conditions. Simultaneously with the operation of the K switch, the mains voltage is supplied by the TV control transformer and at the same time connected to the circuit of the primer, preferably two Ml and M2 fan motors. The TV control transformer receives power from the KN1 contacts through the high frequency and high voltage TN transformer and the JE relay power supply from which the J relay unit operates. The JE relay power supply will only receive the alternating voltage if the TH contact of the thermal switch and the NK contact of the air pressure switch are in the starting position. The thermal switch serves to heat the TI main transformer, and the air pressure switch is closed when the airflow is in operation. The Plasma Cutter Arrangement, when pressed on the trigger of the NU start-up switch, located on the gun, pulls the pilot flow capacitor discharging JPS relay, which, via its PS1 work contact, pulls the delayed JL relay, which delays the air blowing delay when released to cool down the gun after switching off. the delayed JL relay provides airflow through the MSZ solenoid valve. The pilot current condenser discharging JPS relay PS4 contacts the pilot current condenser discharging KPS switch, the KPS2 and KPS3 contacts open and prepare the PC pilot current capacitor for charging.

The JF relay triggering the main transformer activation is triggered by a delay corresponding to the time constant of the CPS capacitor and the resistor R3 via a pilot flow capacitor discharger JPS relay, which has a CF contact capacitor, F2 contact lock, FI contact terminator, and a pilot flow capacitor charger JP relays. with the R5 resistance-CF condenser with a time constant corresponding to the time constant. At the same time as the JP relay, the main transformer starter KFF is pulled, and the KFF switch on the control KF pulls the control switch KF1. The JP relay P3 contact closes the pilot circuit capacitor charger KP switch circuit by pulling on and KP2

PC 209 714 Β and KP3 are used to charge the PC pilot current capacitor. This makes the unit ready for cutting, because the air is secured, the appropriate coils of the main transformer TI are energized, the pilot-current capacitor is charged, but then no current could be generated because the high-voltage circuit parts have not yet been energized, i.e. a negative potential connection point, i. e. the air space between the arcing electrode I and the KU cap is not yet ionized.

The high-voltage starter JN relay circuit is configured to hold for a very short time. When the JP relay is tightened, a contact contact P2, a contact lock P1, is charged via a capacitor R8 and a CN1 capacitor. After releasing the JP relay, contact P1 opens, contact P2 closes, but the JN relay does not pull immediately, but only when the CN2 capacitor has reached the voltage level of the JN relay.

By tightening the JN relay, the JN1 contact closes the ignition switch CN switching circuit, which receives voltage at the contact of the KN1 via the high frequency and high voltage TN transformer, the secondary circuit of which is a high frequency, approx. It produces a high voltage of 10 kHz, which is superimposed on the pilot voltage through the TF ferrite core transformer and ionizes the airspace between the KU cap and the arc arc electrode. When the ion conductor is of sufficient size, the PC pilot current condenser discharges between the arcing electrode I and the KU cap, the initial flow of which decreases rapidly but ignites the cutting current. The resulting plasma arc deflects to the workpiece as a result of air blowing and starts the cutting process, which lasts until the release of the trigger trigger triggered on the gun, and then switches to all basic positions, and after 35 seconds the airflow disappears and the system can be restarted. The role of the SPS spark gap occurs when the gun cap needs to be replaced.

Pressing the ON button causes the plasma arc to form between the arc electrode I and the gun nozzle. Since the value of the BSC is set to 2 mm for sparks, the PC pilot current condenser is discharged through it, thus ensuring that the gun cannot be damaged if the cap is replaced. Fig. 4 illustrates the time course of the operation described above, i.e. the JPS, JL, JP, JF, JN, state of the UU starter switch and JPS, JL, JP, JF, JN relays. In the time shown in the figure, it can be clearly seen in the process that the PC pilot current condenser discharge current takes a very small amount of time for the nozzle, which thus does not suffer any adverse change, thereby ensuring a reliable and stable cut, less zirconia being used.

The structure with electromechanical elements is safe, with high reliability and practical tests with less energy.

Claims (2)

PATENT CLAIMS A circuit arrangement for the manufacture of a plasma arc, the main transformer (TI) of which is connected via a switching unit (KE) to an electrical network, preferably having a dual primary winding, a rectifier (PE) constructed of diodes (D1 ... D6) and a arcing electrode connected thereto. (I), on the other hand, has a pilot current generating circuit and a high frequency high voltage generating circuit connected to the latter, having a control transformer (TV) connected to the switching unit (KE) having one of its secondary winding terminals (A, B) ) via a solenoid valve (MSZ) and through an air pressure switch contact (NK) and a thermal switch contact (ΊΉ) to a relay power supply (JE), the latter output terminals (C, D) of which are connected to a switching unit (J) KE) has actuators in addition, the output terminals (X, Y) of the other secondary winding of the control transformer (TV) are connected to a high-frequency high-voltage transformer (TN) through a switch on the ignition time switch (KN1) and are parallel to the secondary winding of the transformer (TN) coupled, one of the terminals of the capacitor block (CP) being connected to one end of the primary winding of a ferrite-core transformer (TF) via an operating spark gap (CS) and the other terminal of the latter to the secondary (K) end of the secondary winding of the latter transformer (TF) one end of which is connected to a positive polarity connection point (P) of a series current of a pilot current capacitor (PC) and a discharge resistor (PR), the other end of which is connected to a common point of the arc generator (I) and rectifier (PE) (PC) and discharge e In parallel with the series switching of the standby (PR), on the one hand, the series connected terminals (KPS2, KPS3) of the pilot current capacitor discharge switch arranged in the switching unit (KE), and a capacitor block (CB) (PE) has a positive polarity connection point (+) connected in series to the pilot current capacitor charge switch (KP) in the switching unit (KE), and the rectifier (PE) positive polarity connection point (+) also has a common clamping device A spark gap (BSZ) is connected between the arc generating electrode (I) and the cap (KU). Circuit arrangement according to Claim 1, characterized in that between the positive and negative polarity connection points (C and D) of the relay unit (J) on the contacts of a filter capacitor (CSZ) and a trigger switch (NU) arranged in a gun, respectively. a pilot current capacitor discharge relay (JPS) is connected via a resistor (R1); also a positive polarity connection point (C) with anode diode (D13), pilot current capacitor discharge EN 209 714 Β relay (JPS) work contact (PS1) and delay relay (JL) connected in series; between the same points a further working contact (PS2) of a pilot current capacitor discharge capacitor (JPS) of a diode (D14), a resistor (R3), a series connection of the main transformer starter relay (JF); and a series connection of a diode (D15), a main transformer start relay (JF) contact (FI), a resistor (R5), a working contact (F2) of the former relay (JF) and a pilot current capacitor charging relay (JP); and a series connection of a diode (D16), pilot current capacitor charge relay (JP) contact (P1), resistor (R8), resistor (R7), pilot current capacitor charge relay (JP) contact (P2), and high voltage generator starter relay (JN). ; the diodes (D13, D14, D15, D16) connect with their anodes to the positive polarity connection point (C), one diode (D7, D8, D9, Dll), respectively, connected to the relays (JPS, JL, JF, JP, JN), D12) is connected to their anodes connected to the negative polarity connection point (D), in parallel to the delay relay (JL), a resistor (R2) and a capacitor (CL1) are connected in series, parallel to the main transformer start relay (JF), A (CPS) connected diode (D10) is connected in series and its common point is connected to the negative polarity connection point (PS) of the resistor (R4) and pilot current capacitor discharge relay (JPS) operating parallel to the capacitor (CPS); a resistor (R6) is connected in parallel with the pilot current capacitor charging relay (JP), the same relay (JP) and a working contact (F2) connected in series with it with a capacitor (CF) and a resistor (R9) with the high voltage relay (JN). ) and a capacitor (CN2) is connected in parallel, the same relay (JN) is connected in series with its contact (P2) and resistor (R7) with a capacitor (CN1), the starter switch (NU) and the work contacts (PS1, PS2, F2, P1) and capacitors (C1, C2, C3, C4, C7 and C5, C6) are connected in parallel to the contacts (FI, P2) at the connection points (S °, O) of the switching unit (KE). ) serial connection of a pilot current capacitor discharge switch (KPS) and a master transformer start switch (KFF) to the operating contacts (KPS1) and (KFF1) of the controlled main switch (KF) coil; and serially coupling the pilot current capacitor discharge relay (JPS) work contact (PS4) to the pilot current capacitor discharge switch (KPS) inductor; and serially connecting the delay contact relay (JL) working contact (JL1) to the air valve switch (KL) inductor; and serially connecting the main transformer start relay (JF) work contact (F3) with the air valve switch (KL) work contact (KL2) and the main transformer start switch (KFF) feed coil; and serially coupling the pilot current capacitor charge relay (JP) working contact (P3) to the pilot current capacitor charge switch (KP) inductor; and serial connection of the high voltage starter relay (JN) work contact (JN1) to the pilot current capacitor charge switch (KP) work contact (KP1) and the ignition time switch (KN) inductor.