Argon arc welding machine is usedArgon arc weldingHigh voltage breakdown arc starting mode is adopted for the machine.Argon arc weldingTungsten inert gas arc welding, refers to the use of industrial tungsten or active tungsten as the non melting electrode,inert gas（argon ）Welding method for protectionTIG。It is generally used for welding 6~lOmm thin plates andPlateSingle side welding and double side forming back welding.Commonly used welding machines include domestic YC-150 manual tungsten argon arc welding machine.[1]
Chinese name
Argon arc welding machine
Foreign name
TIG
Overview
Tungsten inert gas arc welding
Homogeneous differences
The main circuit and driving circuit are similar
Mainstream model
WSE series AC/DC multi-purpose argon arc welding machine
working principle
Arc starting mode with high-voltage breakdown
Operating Procedures
Argon arc welding must be operated by special personnel
Argon arc welding machines are divided into consumable electrode argon arc welding machines and non consumable electrode argon arc welding machines according to different electrodes.
Non consumable electrode argon arc welding
Non consumable electrode argon arc welding means that the arc burns between the non consumable electrode (usually tungsten electrode) and the workpiecewelding arc It flows around with a kind ofinert gas(usually argon), forming a protective gas hood to make the tungsten terminal head, arc and molten poolAnd hasMetal at high temperature is not in contact with air, which can prevent oxidation and absorptionHarmful gas。To form densewelded joint , whichmechanical property very nice.
Consumable electrode argon arc welding
The welding wire is fed through the wire wheel,Conductive nozzleConductive, atBase metalAn arc is generated between the welding wire and the welding wire to melt the welding wire and base metal, and inert gas is usedargon Protect the arc and molten metal for welding.It andArgon tungsten arc weldingOne is that the welding wire is used as the electrode, and it is continuously melted and filled into the molten pool, and the weld is formed after condensation;The other is to adoptShielding gasWith argon arc weldingTechnology application，Shielding gasVarious types of argon have been developedMixtureThe wide application of body, such asAr80%+CO220% argon rich shielding gas.Usually, the former is called MIG, and the latter is called MAG.Seen from its operation mode, semi-automatic MIG welding and rich argon mixed gas shielded welding are the most widely used, followed by automatic MIG welding.
Homogeneous differences
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Argon welding machine and manual arc welding machine in the main circuitAuxiliary power supply、drive circuit 、protection circuit And other aspects are similar.But it adds several controls on the basis of the latter: 1. manual switch control;2. High frequency and high voltage control;3. Pressurized arc starting control.In addition, on the output circuit, the argon arc welding machine adopts negative poleOutput mode, the output negative pole is connected to the electrode needle, and the positive pole is connected to the workpiece.
Mainstream model
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WSE5 series AC/DC square wave argon arc welding machine
WSE5 series AC/DCsquare waveArgon arc welding machine WSE series AC/DC multi-purpose argon arc welding machine (moving iron core silicon rectifier assembly)
WSM-160 inverter pulsed DC tungsten argon arc welding machine
WSM-200 inverter pulsed DC tungsten argon arc welding machine
WSM-250 inverter pulsed DC tungsten argon arc welding machine
WSM-315 inverter DC tungsten argon arc welding machine
WSM-400 inverter pulsed DC tungsten argon arc welding machine
WSM-500 inverter pulsed DC tungsten argon arc welding machine
working principle
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The argon arc welding adopts the arc starting mode of high-voltage breakdown（Tungsten needle）High frequency and high voltage are applied between the workpiece and the argon to make it conductive, and then continuous current is supplied to ensure the stability of the arc.
argonArc welding machineIn the main circuitAuxiliary power supply、drive circuit 、protection circuit The working principle of hand arc welding machine is the same as that of hand arc welding machine.It will not be described here, but will focus on the unique control function and arc starting circuit function of argon arc welding machine.
Manual switch control
The argon arc welding machine requires argon to come first and then go, while the current will go later (relative to gas), which is controlled by hand switch.
Figure 1
As shown in Figure 1, when the main switch of the welding machine is closed, the auxiliary power supply works, providing 24VDC。When the hand switch is not closed, 24V DC passes through the resistanceR5Make Q2Conduction, 8 pins of CW3525 chip pass through T-shapewave filter(composed of L5 and C5, used for anti-interference) is short circuited to the ground. At this time, CW3525 is in the sealed wave state, and the circuit has no output;When the hand switch is closed, 24V DC passes through resistance R4R8Make Q1 turn on, Q2 base is pulled down and turned off, 24V DC makes Q3 turn on relay J3A pull on through resistance R6, R7, so that control gas supplySolenoid valveWork to supply gas for welding.However, the 8-pin potential increases slowly due to the slow start resistance and the role of capacitance. After a certain period of time, CW3525 starts to work and the circuit beginsoutput power。In this way, the current delay supply delay time is determined by the slow start dynamic resistance and capacitance.
The solenoid valve supplies gasControl deviceWhen relay J3A is closedInductance coilObtaining currentMagnetic energyThe iron block is sucked away from the gas pipe orifice, and the gas is supplied for welding through the solenoid valve.
In the hand switch control circuit, the inductance coils L1~L4 and C1, C2 play the role of preventing interference and misleading the hand switch.
1. When the hand switch is closed, the solenoid valve opens the air supply because Q3 conduction relay J3A is closed.The auxiliary power supply charges capacitor C17.And becauseThermistorRT4RT5 current limiting prevents the hand switch from being damaged due to excessive current;
2. After the welding is completed and the hand switch is disconnected, Q2 is turned on, the potential of the eight pins of CW3525 is pulled down, and the circuit stops outputting, while C17 is still charged with electric energy, which is supplied to Q3 through R6 and R7 discharge, and the solenoid valve is kept on for delayed air supply.The control requirements of welding current and gas are realized.
Generation and control of high-frequency and high-voltage current
(1) Generation: The argon arc welding machine needs high voltage for arc starting. In order to generate high voltage based on the manual arc welding machine and send it to the output circuit, the circuit shown in Figure 2 is adopted.
(2) Operating principle:
Figure 2
1）step-up transformer；The transformer in Figure 2 is 24:70, which increases the voltage of 307 by about 3 times.2) Use 4 times of voltagerectifier circuit ；As shown in Figure 2 (C11~C14, D11~D14) to generate high voltage: ① When the primary of step-up transformer (T1) flows through a positivepulse currentHour（Voltage valueU), N2 generates oneUprightnessDownward negativeInduced electromotive forceAnd charge the capacitor C14terminal voltageAlso U, (see Figure 2 for direction);And because of the coilAfterflowAnd D14Main transformerC14 cannot discharge when there is no current flowing through; ②When the step-up transformer flows through an equivalent negative pulse current, it generates an induced electromotive force (U) of up negative and down positive on N2 to charge C11, making the voltage drop VC11=VC14+U induction=2V on C11. The direction is shown in Figure 2; ③When the step-up transformer T1 flows through a positive pulse current again, the upper positive and lower negative induced electromotive force is generated on N2. At this time, the capacitor C13 is charged, and the terminal voltage VC13=VC11+U induction - VC14=2V. The direction is as shown in Figure 2; ④The current direction of the step-up transformer is changed again, so that the induced electromotive force direction on N2 is negative up and positive down. At this time, the capacitor C12 gets electric energy, and VC12=VC13+VC14-VC11=2V. The direction is shown in Figure 2. In this way, a 4U voltage drop is formed between A and B.
(3) High frequency oscillationGenerator: (composed of L3 (N3), C5 and discharge nozzle)
① The pressure drop at two points A and B reaches 4V (V isinverteroutput voltage , about 1KV), charging capacitor C15;
② The discharge nozzle is discharged due to high-voltage breakdown. At this time, it is equivalent to short circuit L3 and C15;
③ L3 and C15 generate high-frequency oscillation, f=L/2 π√ LC
④ Due to the continuous supplement of output energy, L3 and C15 generate high frequency at regular intervalsOscillating currentAnd output to output via T4 secondary.Due to the high frequency and high voltage current on T4, its technical parameters are strictly required. Its quality is the decisive factor for the difficulty of arc starting and welding effect.
control
Figure 3
When there is high frequency and high voltage current in the output circuit, the arcing is guaranteed. However, if the protection is not proper, the high frequency and high voltage current willReverse breakdownIn secondary rectificationRectifier tube, or even damage the circuit connected to the primary coil of main transformer T1. Moreover, high-frequency and high-voltage are only used for arc startingBack of arc, it is no longer needed, so it needs to be disconnected in timeHigh frequency high voltage generatorIts control circuit is shown in Figure 3 ① Anti interference control:VaristorAs for the high frequency and high voltage current, it is equivalent to short circuit. At the same time, the positive and negative ends are connected with high frequency resistant inductance coils. In this way, the high frequency and high voltage current is controlled to reverse to the secondary rectification circuit, and only the output end forms a loop.At the same time, connect the positive andCasingThe resistance (voltage sensitive) and capacitance between can also effectively preventhigh-frequency currentAnd other interferences.
② Generation and switching off control of high frequency and high voltage current: the generation and switching off of high frequency and high voltage current are controlled by relay J. When the hand switch is fully turned on, S2 is turned on. At this time, the circuit works, and the output voltage is about 56 VDC voltage, which makes the relay act, closes JA, and makes the high frequencyHigh voltage circuitWhen working, high frequency and high voltage current output is generated, causing arc. Once the arc is caused, the output circuit will appearlarge current, flowing throughreactor(Inductive coil);Due to the continuous current effect of inductance, the positive terminal of reactor (in Figure 3Point A）The voltage drops to a very low potential (evennegative）At this time, the relay is reliably disconnected, and the high-frequency high-voltage generator stops working, completing the control of high-frequency high-voltage current.
Pressurized arcing control
To protect easy arcing, providewelding quality The argon arc welding machine also adds a device for boosting and arcing at the output end, which uses another set of secondary sides of the transformer of the high-frequency high-voltage generator asBooster transformerWhen the high frequency and high voltage generator works, it also raises the voltage at the output terminal to ensure arcing. After arcing, the booster device will also follow the high frequency and high voltageCurrent generatorThey are disconnected together.hisschematic diagramAs shown in Figure 2
Operating Procedures
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1. Argon arc welding must be carried out by specially assigned personOperation switch。
2. Check whether the equipment and tools are in good condition before work.
3. CheckWelding power supply, whether the control system hasground wireAdd lubricating oil to the transmission part.The rotation must be normal, and the argon and water sources must be unblocked.In case of water leakage, immediately notify for repair.
4. Checkwelding torchWhether it is normal and whether the ground wire is reliable.
6. Select the polarity according to the material of the workpiece, and connect the welding circuit. Generally, the material is DC positive connectionAluminum and aluminum alloyUse reverse connection orAC power supply。
7. Check weldinggrooveWhether it is qualified, the groove surface shall be free of oil stain, rust, etc., within 200 mm on both sides of the weldDegreasingRust removal.
8. ForPlacentaThe reliability shall be checked, and the preheating equipment and temperature measuring instrument shall be checked if the weldment needs preheating.
9. The argon arc welding control button shall not be far away from the arc, so that it can be closed at any time in case of failure.
10. High frequency arc starting must be adoptedFrequent inspectionWhether there is leakage.
11. In case of equipment failure, power shall be cut off for maintenance, and operators shall not repair by themselves.
12. It is not allowed to be naked or exposed to other parts near the arc. It is not allowed to smoke or eat near the arc to avoid ozone and smoke inhalation.
13. Wear masks and gloves when grinding thorium tungsten electrode, and observeGrinding machineOperating Procedures。It is better to use cerium tungsten electrode (less radiation).The grinder must be equipped with an exhaust device.
14、jockeyAlways wear static electricityAnti-dust masks。The high-frequency electric action time shall be minimized during operation.Continuous work shall not exceed 6 hours.
15. The argon arc welding site must be ventilated.The ventilation and detoxification equipment shall be started during work.Ventilation deviceIn case of failure, stop working.
16、Argon gas cylindersIt is not allowed to collide. There must be a support when it is placed vertically, and it must be 3 meters away from the open fire.
17. When argon arc welding is carried out inside the container, a special mask shall be worn to reduce the inhalation of harmful smoke.Personnel shall be arranged outside the container for supervision and cooperation.
18. ThoriumTungsten rodIt should be stored in a lead box to avoid that when a large number of thorium tungsten rods are gathered togetherradioactivityInjury caused by dosage exceeding safety regulations.
