The water-cooled torch is designed for continuous high current welding and can be operated continuously with a welding current of up to 200 amps. Some are designed for a maximum welding current of 500 amps, which is heavier and more expensive than air-cooled torches.
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Principle Tungsten argon arc welding is a welding method in which a tungsten rod is used as an electrode and argon gas is used for protection. The method is as shown in the figure. During welding, argon gas is continuously ejected from the nozzle of the welding torch, and a protective layer is formed around the arc to block the air to prevent harmful effects on the tungsten electrode, the molten pool and the adjacent heat-affected zone, thereby obtaining a high-quality weld. During the welding process, the welding wire may or may not be filled according to the specific requirements of the workpiece.
Features This welding method has the following advantages and disadvantages because the arc is burned in argon:
1) Argon has excellent protection and can effectively isolate the surrounding air; it does not react with metal or dissolve in metal, which makes the metallurgical reaction in the welding process simple and easy to control, thus obtaining higher quality. The weld provides good conditions.
2) The tungsten arc is very stable, even under low current conditions (
3) The heat source and the filler wire can be separately controlled, so the heat input can be easily adjusted. This welding method can perform all-round welding, and is also an ideal method for realizing single-sided welding double-sided molding.
4) Since the filler wire does not pass current, no splash is generated and the weld bead is beautifully formed.
5) AC argon arc welding can automatically remove the oxide film on the surface of the weldment during the welding process. Therefore, some chemically active non-ferrous metals such as aluminum, magnesium and alloys can be successfully welded.
6) The tungsten current carrying capacity is poor. Excessive current will cause the tungsten electrode to melt and evaporate, and the particles may enter the molten pool and cause tungsten to be trapped. Therefore, the deposition rate is small, the penetration depth is shallow, and the productivity is low.
7) Argon gas is expensive, the deposition rate is low, and the argon arc welding machine is complicated. Compared with other welding methods (such as electrode arc welding, submerged arc welding, CO2 gas shielded welding), the production cost is high.
8) The argon arc is greatly affected by the airflow and is not easy to work outdoors.
Applicability TIG welding is suitable for manual or automatic operation and can be used for continuous welding, continuous welding (sometimes called 'jumping') and spot welding because the electrode rod is non-consumable, so it is not It is necessary to add the filler metal and only fuse the base metal for welding. However, for individual joints, it may be necessary to use a filler metal.
TIG welding is a full-position welding method and is particularly suitable for the welding of thin sheets - often as thin as 0.005 inches.
(a) Welded metal
The characteristics of tungsten argon arc welding make it suitable for the welding of most metals and alloys. The metals that can be welded by tungsten argon arc welding include carbon steel, alloy steel and stainless steel. "target=_blank> stainless steel, heat resistant alloy, difficult Fused metals, aluminum alloys, magnesium alloys, niobium alloys, copper alloys, nickel alloys, titanium alloys and zirconium alloys, and the like.
Lead and zinc are difficult to weld by tungsten argon arc welding. The low melting point of these metals makes welding control extremely difficult. Zinc vaporizes at 1663F, which is still much lower than the arc temperature, and the weld bead is volatilized by zinc. Poor, steel with lead, tin, zinc, cadmium or aluminum on the surface and other metals that melt at higher temperatures can be arc welded, but special procedures are required.
The weld bead in the plated metal is the result of the "interactive alloy". It is likely to have low mechanical properties to prevent the interaction of the alloy in the metallization of the coating. The surface coating of the area to be welded must be removed and repaired after welding.
Base metal thickness Tungsten argon arc welding can be applied to metal welding in a wide range of thicknesses. This method is very suitable for welding objects up to 3mm thick because its arc generates strong, concentrated heat, which produces high welding speed and uses molten metal. Can do multiple welding.
Although the base metal of a thickness of 6.25 mm or more is usually used in other welding methods. However, high-quality thick weldments require multi-layer welding using tungsten argon arc welding. For example, in the manufacture of 8m diameter rocket generators and 15mm thick casings, tungsten and argon arc welding uses filler metal for longitudinal and circumferential multi-pass welding, although this welding method is slower for this thick metal, but because TIG welding is used for the high quality requirements of the weld bead.
Tungsten argon arc welding can successfully weld a variety of "foil thickness" alloys, which require precision fixtures for metal foil thickness. Mechanical or automatic welding is required. "High temperature ion arc welding" is often referred to as a change in tungsten argon arc welding, which has more advantages for welding thin plates.
The shape of the work object prevents the use of hand-operated welds at complex shapes where automated methods are used. Hand operation is used for welding on irregular shaped articles that require short weld beads, or for welding in difficult to reach (inaccessible) areas, and hand operation is also suitable for full position welding.
Automatic equipment can be welded using curved and straight surfaces. For example, a special sinusoidal wave welding of the components at both ends of the corrugated titanium pole, for this sinusoidal welding, a mechanical guiding unit is designed to follow the metal template to guide the welding torch. For example, the manual operation of this welding, which is extremely difficult to control.
The basis of TIG is that in tungsten argon arc welding, the heat is generated between the rod and the workpiece, and the edge of the workpiece is melted and must be cleaned and joined together when the weld pool is solidified.
In order to obtain a good quality weld bead by tungsten argon arc welding, it is basically necessary to clean all surfaces and adjacent areas to be welded, and if the filler metal is used, it must be cleaned.
Another basic requirement is that the combination of components to be welded must be firmly held in the correct relevant position, when the combination is high and the work is thin and the shape is complicated. The fixture to be used when not using filler metal welding or when using automatic welding.
(a) Arcing
The usual method of "arcing" is to initiate the electron emission and gas ionization; the workpiece can be contacted via the energized electrode rod and quickly pumped back to its desired arc length, or using a pilot arc, or used in An auxiliary device for generating a high-frequency spark between the electrode rod and the workpiece induces an arc to obtain the energy of the radiation and ions; the mechanical rod is mechanically extracted from the workpiece only for the mechanized welding of the DC welding machine. However, the arc-initiating method can be used for hand operation and mechanized welding, but it is also limited to DC welding machines. The high-frequency spark arcing method can be applied to the hand-operated welding of AC or DC welding machines, and many welding machines have high production. The frequency sparking device performs arcing and stabilizes the arc.
(ii) Electrode rod and filler metal location
The position of the electrode rod and the filler metal in the hand-operated tungsten argon arc welding is shown in Fig. 1. Once the arc is held, the welding rod is kept at an angle of about 75o from the surface of the workpiece, and the welding direction is started, and the welding is started. At this time, the arc is usually moved in a circular motion until sufficient target metal is melted to produce a suitably sized molten pool (see Figure 1a). When proper fusion is achieved, the torch is gradually moved along the adjacent edges of the weld joint. Such a gradual fusion work, when the filler metal is added by hand operation, is often kept at an angle of about 15o from the surface of the workpiece, and slowly enters the molten pool (see Figure 1c), and must be carefully fed into the melt. The metal is used to avoid disturbing gas protection or contact with the electrode rods, and due to oxidation of the ends of the filler strips or contamination of the electrode rods. The filler metal strip can be continuously added or repeatedly "invaded" and "extracted".
The filler metal can be continuously added in such a manner that the weld filler strip and the weld bead are arranged in a line (usually using a multi-weld joint with a V-joint) or the molten filler strip is fed by the melt filler strip and the welding gun to swing left and right. Molten pool (a method of surface layering is often used).
When the welding is stopped, the molten metal is withdrawn from the molten pool, but temporarily maintained under gas protection. To prevent oxidation of the molten metal, then move the torch to the front edge of the bath before the arc is extinguished, and lift the torch to a height that is just enough to extinguish the arc but not enough to cause contamination of the puddle and electrode rod. The current is gradually reduced by the foot control method without raising the welding torch.
(iii) Arc length
In many fully automated TIG welding applications, the length of the arc used is approximately equal to 3/2 times the diameter of the electrode rod, but can vary depending on the particular application, depending on the welder's preferred choice. The longer the arc length, the higher the heat that diffuses into the surrounding atmosphere, and the long arc usually prevents (to some extent) the stability of the weld, with one exception being the "plug joint" in the pipeline to In the vertical position welding of the official shaft, a long arc can produce a smoother fillet weld than a short arc.
(iv) Manual and automatic operation
There is a difference between manual and fully automatic TIG welding, that is: manual welding is done by "welder", automatic welding is done by "operator"; for example, pedal control welding current and The improved method of manual welding of the transfer switch is a preliminary development towards automatic welding; using the holding and driving torch to move at a fixed speed or at a planned speed, and automatically adjusting the arc voltage (arc length), automatic switching and stopping equipment , which constitutes fully automatic welding.
(5) Welder technology
Operator selection and training is primarily dependent on the “automated degree†of the equipment used, as TIG welding is the most commonly used accessory for joining metal sheets, and because in its application, the welder can handle it fairly easily. Light and small components, so welders often spend part of their time cleaning, combined device fixation and virtual welding operations, and in addition to the need for high manual skills, patient training to obtain good quality weld bead, sometimes welders With mechanical techniques, the assembly to be welded is suitably assembled and fixed. The need for a particular welding technique will vary from one welding method to another. For example, a welder who is hand-operated with gas shielded welding needs additional training to qualify for TIG welding. Special techniques are required in certain applications, such as the placement of consumable backing rings and welding and repair welding.
(6) Inspection
Tungsten argon arc welding inspections include all non-destructive methods, from surface inspection of sheet metal welds to radiation (X-ray) and ultrasonic inspection of thicker welds to check that surfaces below (internal) are more likely to occur. Defects.
Welding current "current" is the most important operating condition in the control of any welding operation because it is related to the depth of penetration, welding speed, welding speed and quality of the weld bead; basically, there are three welding currents to choose from. : (a) DC positive polarity, (b) DC reverse polarity (c) AC (d). Adding high frequency currents to these three currents provides some of the desired effects. The current type test options for the various metal welds listed in Table 1 are shown.
(1) DC positive polarity
For the most widely used current mode for tungsten argon arc welding, a good weld bead can be produced in almost all commonly weldable metals and alloys; in dcsp (DC positive polarity) welding, the electrode is the negative electrode, the work object The metal is the positive electrode, so the electron flow is from the electrode to the working metal. Because 70% of the heat in all DC arcs is generated at the positive or anode ends of the arc, for the given size of the electrode rod, it can withstand more positive current, and can withstand less reverse polarity current, the same, If a hot arc is required for a particular size electrode rod, dcsp is the type of current that must be used.
A positive DC current can produce a deep narrow bead, and "infiltration" is superior to that provided by the other two currents, whereas narrow beading and deeper penetration cause difficulties in soldering thin metal objects in this dcsp; The difference between dcrp or ac is that dcsp cannot remove the surface oxide on aluminum, magnesium or beryllium copper, but if aluminum is soldered with dcsp, special welding method is required plus mechanical or chemical cleaning before welding.
The use of dcsp soldering requires more techniques than high frequency stabilized AC arc welding, mainly because dcsp does not have high frequency pilot discharge during arc ignition, so special equipment can be added to the standard machine to apply high frequency current. Attached to dcsp.
(2) DC reverse polarity
In the welding of dcrp (DC reverse polarity), the electrode is connected to the positive end of the welding machine, and the metal of the working object is connected to the negative end. Therefore, the electron flow from the working stream to the electrode rod; while generating high heat in the electrode, generating low heat in the work; at the same ampere and arc length, the voltage of the dcrp arc is slightly higher than the dcsp arc, so the dcrp arc has more Total energy.
Reverse polarity DC is the least used of the three current types because it produces flat, wide and shallow penetration welds. dcrp welding requires high technology because large diameters are required for the same low welding current values. Electrode rod. Therefore, it is usually not used, and the reverse polarity direct current has the "coldest" effective arc, but can provide superior characteristics of moving oxide from the surface of the workpiece.
Welding aluminum with dcrp is particularly difficult because the molten pool is easily attracted to the tip of the electrode rod and the electrode rod is contaminated with the aluminum when it is in contact with the aluminum. However, dcrp can be effectively used to bond thin aluminum sheets (0.6 mm). On the other hand, magnesium is rejected by the inherent arcing action of dcrp and thus has no contamination problems. dcrp can be used to weld magnesium metal up to 3 mm thick.
(3) Removing oxides with dcrp
There are several theories that explain why the reverse polarity DC current can remove oxides from certain parent metal surfaces. However, the accepted explanations are as follows:
When the polarity is positive, the ions of argon or helium are carried out to the surface of the base metal. On the surrounding inert gas mist, the charged gas cations are generated by the arc, and the gas ions have a considerable quality, and thus While rushing to the metal watch, a large amount of kinetic energy is obtained. When these ions collide with the metal surface, if there is a way of spraying, the particles of the oxide are removed and cleaned, and the particles generate heat on the metal base material than in the arc. The heat generated at the anode end is less, and the amount of penetration is relatively small. If the electrode rod is a negative electrode and the working object is a positive electrode, the ions travel toward the electrode rod without a cleaning effect on the working metal and the electron "bomb" is to weld the metal. This results in considerable heat and penetration of the working metal.
(4) Polarity judgment of the welding machine
In automatic tungsten argon arc welding, there is a danger of starting the welding operation with the wrong polarity, which is caused by repeated operations, but in hand-operated welding, only the connection of the end of the welding machine is changed by accident and the polarity is reversed. It is best to test the polarity before starting the soldering to avoid possible damage to the electrode (if the reverse polarity current is applied to the small electrode rod, damage will occur).
Use hand-welded arc welding of the handlebar wire on the line, test polarity, reverse polarity, all-position manual electrode arc welding electrode arcing (E6010 level), if the polarity is positive, the arc is strong and powerful Beep; the arc of the true reverse polarity E6010 does not have a strong hum.
(5) AC current
It can be said that a series of dcsp and dcrp interaction pulsing, and the current direction is changed 120 times per second. In alternating current, between each cycle, the voltage changes from the largest positive value to the largest negative value, and each time a change occurs. The arc is extinguished once; when soldering in inertia, the conventional arc welding transformer cannot produce a voltage that is high enough to establish an arc after the arc is extinguished, the same, unless a transformer with sufficient intrinsic voltage is used, otherwise A high frequency current must be applied to the arc to establish a welding arc every half cycle.
AC power provides good penetration and reduces (or reduces) surface oxides; ac tungsten argon arc welding produces welds that are wider and shallower than dcsp welds, but narrower and deeper than dcrp welds. Moreover, the bead reinforcement portion is larger than the bead reinforcement portion of dcsp or dcrp, so the alternating current is more suitable for welding aluminum, magnesium and beryllium copper.
(6) Prevention of rectification in AC power
Since the positive and negative half cycles of the voltage generate unequal current resistance across the alternating current arc, causing an unbalanced current sine wave, a rectification phenomenon occurs, because it generates a DC voltage portion in the ac arc, which is high enough to cause The arc is fluttering and unstable. Tungsten argon arc welding uses older transformers and is more likely to rectify because there are no new balanced waveform components.
The rectification occurs because the electrode rod and the welding metal emit unequal amounts of electrons. It is affected by the current density of the electrode rod end and the working object arc (the temperature of the current density control), and is also affected by the arc length and the shielding gas used to a certain extent, and the rectification will generate DC up to 12V. In the welding of aluminum in the voltage part, when the direct current portion is high, the bright molten pool of molten aluminum becomes dark and an oxide film is generated, which is proportional to the size of the direct current portion.
A balanced waveform transformer can be used to eliminate rectification and its detrimental effects. This component is added to a capacitor in series with the soldering circuit. The capacitance of this capacitor allows the AC welding current to flow effectively, but prevents partial circulation. These components are usually designed to An open circuit voltage with a range of 100-150 volts requires high frequency current arcing and is widely used for welding aluminum alloys and magnesium alloys.
(7) Pulsating current welding
Tungsten argon arc welding of pulsating current is operated with high current rise and decay rate and high repetitive pulsation rate. It is widely used with precision fittings. The pulsating current with slower current pulsation rate is used for mechanization. Pipe fitting and other mechanized welding applications.
At present, in order to develop a circuit capable of automatically and accurately controlling the arc voltage of the pulsating TIG, the arc voltage used by these circuits is generated by a high pulsating current and a lock control during the period of the residual portion, in a modified pulsating current welder. The following functions may be individual independent start parts
The advantages of pulsating current tungsten argon arc welding are as follows:
1 The ratio of “depth to width†of the weld bead is increased: using a short duration high current welding pulse and a small, pure tantalum tungsten electrode rod, in the stainless steel "target=_blank> stainless steel welding, the arc force will occur 2:1 depth to width ratio weld bead.
2 Eliminate the “falling†high current, short-duration pulse can “penetrate†the root weld bead or thin work metal and the molten pool becomes large enough to solidify before falling.
3 The heat affected zone is minimized: the heat affected zone can be minimized by the height and duration of the high pulse, and the appropriate ratio of the height and duration of the low pulse, sometimes setting the low pulse height to zero while maintaining high There is a limited spacing between current pulses.
4 Stirring in the molten pool: The arc and electromagnetic force generated by the high pulse of the current is much larger than that produced by the constant current welding. These high forces cause the agitation of the molten pool to be reduced, and pinholes and incomplete fusion may occur at the bottom of the joint. The pulsation produces a solid, stiff arc when used in low current welding, eliminating arc sag instability that can occur with low current constant current arcs.
The welding machine for tungsten welding of tungsten argon arc welding has: (a) transformer---rectifier type, DC output. (b) Transformer type, AC output (c) Power driven generator----electric motor drive. (only for ac output), or engine drive (for ac or dc output).
Transformers and rectifier welders have several advantages over power-driven generators: low initial cost, no current drop during warm-up, quiet operation, low maintenance and operating costs, no rotating parts, low power input at standstill, An advantage of an engine-driven generator is that it can be used in areas where power is supplied.
(1) High-frequency stability The large-flower gap or tubular oscillator is connected to the welding transformer circuit for arcing, and in some cases, it is also sustainable, and is stable at most high frequencies in most of the early days. AC power is used in TIG welding, and the "radio interference" occurs quite a bit of trouble. However, today, vibrating electro-hydraulics, "tube" brakes and unique phase high-frequency transformers supply sparks with weaker discharges, making " The phenomenon of wireless interference is reduced.
In order to modify some older transformers, install HF-stabilized circuits for contact arcing, and perhaps add a magnetic contactor to the AC welding machine to activate with the foot switch; use this type of installation. The welder can point the electrode rod to the underside of the workpiece at the position where it needs to start. Then, the foot switch is connected. When the electrode rod is lifted from the workpiece, the arc is started. This procedure is simpler, and when the welder wants to stop the welding current. Just release the foot switch.
The strength required for HF induced discharge depends on the joint design, the length of the electrode rod extension and the welder's ability to induce current arcing with minimal HF. If welding is performed in deep grooved joints, the HF current intensity must be low, otherwise The arc bridges the width of the groove without entering the root of the joint.
Excessive high frequency stability has the following adverse effects:
1. Operators are more likely to be shocked by electric shock.
2. The welding arc is unstable.
3. If a metal nozzle is used, it will “carry†to the nozzle.
4. Reduce the life of the welded cable because high frequencies will infiltrate the insulation.
5. Increase wireless reception interference.
If a high frequency circuit is added to the welding current, the most important thing is that the power must be turned off before placing or adjusting the electrode rod, or before placing or placing the metal part of the soldering tip, otherwise it will happen. Violent electric shock, especially when the operator is exposed to warm air near the work.
When the electrode is still hot at high frequency, when the electrode rod is still hot after arc extinction, the tip of the electrode appears purple halo. When the electrode rod cools, the purple halo violently fades, and when the electrode rod reaches a certain temperature, it suddenly disappears. When the viola is visible, there is still a considerable distance between the electrode rod and the workpiece, which will cause an arc, so special care must be taken to avoid sudden arcing and arcing at undesired locations.
(2) "Hot start" device For some welding, it is necessary to provide a current for accumulating (more than normal current) so that welding (starting arc) can be started in the shortest time delay. This is in automatic or semi-automatic welding. It is particularly helpful to connect the hot starter in the circuit to provide a start-up (arc starting) current-amplifying current, which is typically pre-adjusted for the required applied current and the required time amplitude.
(iii) Convergence of power generation In the case of high current values ​​with short durations and frequently started welding, an induction motor can be used to straddle (parallel) the terminal in the connection of the welding machine to alleviate the power increase in the line. Without external load, the rated horsepower of the motor must exceed the KVA rating of the welder, so that when the current is increased due to the short circuit in the arcing and the line voltage drops, there will be enough kinetic energy in the rotating armature to convert into a large amount of power. In the input line, a sharp drop in the line voltage causes the motor to slow down, and the rotational energy in the motor is converted into electrical energy, helping to keep the line voltage rising, unless it is used to slow down the line voltage drop during arcing. Otherwise, you must be careful about cost analysis before doing this type of installation.
(4) Reducing the current to make the crater filling In some applications, the bead terminal needs to be uniformly finished, and avoid sudden depression on the arc extinction point in the weld crater, welding in aluminum alloy and magnesium alloy. In the process, it is necessary to start to reduce the welding current before it is just finished. However, metals such as nickel-based and cobalt-based alloys are sensitive to "drum shock" unless they are extinguished by gradually reducing the current and assisting in the filling of the metal. Temperature welding (this can also be reduced from the molten pool) otherwise crater cracking will inevitably occur. In order to avoid "thirst" or depression in the puddle after arc extinction, the weld bead must continue over the bead terminal and must gradually Reducing the current to a value where the metal is not melting, otherwise a recess or arcing scar will form in the work when the arc stops acting. Such scars and perhaps microscopic cracks may increase the susceptibility to corrosion.
There are several ways in which various welders can gradually reduce the current:
(a) control method on the motor generator; (b)
(c) using a varactor control method on the rectifier;
(d) Isolating the primary and secondary coils using a motor or air driven cylinder on the movable coil of the control transformer and the saturable reactor.
The torch-manipulated TIG torch must be solid, lightweight and completely insulated. It must be held by the handle and supplied with shielding gas to the arc zone. It has a collet, collet or other means to firmly compress the tungsten. The electrode rod guides the welding current to the electrode rod. The torch combination generally includes various cables, hoses and welding guns to the power supply, gas and water fittings. Figure 3 shows a typical water-cooled hand-operated torch protective gas. The entire system that passes through must be airtight. Leakage in the hose joints can cause a large loss of shielding gas, and the molten pool cannot be adequately protected. Air inhalation into the gas system is often a major problem, requiring careful maintenance to ensure airtightness. Gas system.
TIG torches come in a variety of sizes and types, ranging in weight from three to two to almost one pound. The different torch sizes are based on the maximum welding current used, and can be used with different sizes of electrode rods. Different types and sizes of nozzles, the angle of the electrode rod and the handle varies with different welding guns. The most common angle is about 120°, but it is also a 90° head angle welding gun straight welding torch, or even an angle adjustable welding torch. Some welding guns have auxiliary switches and gas valves in their handles.
The main distinction between tungsten argon arc welding torches is air-cooled and water-cooled. Because most of the air-cooled cooling is provided by gas shielded welding. Therefore, the correct statement should be that GAS-COOLED real air cooling only radiates heat to the surrounding air. On the other hand, some cooling of the water-cooled welding torch is provided by the shielding gas, but others are supplemented by water circulating through the welding torch. (See Figure 3a)
Air-cooled torches are usually lightweight, small and solid, and are less expensive than water-cooled torches, but are generally limited to welding currents below about 125 amps, which are normally used for soldering sheets and have low utilization. Where, the operating temperature of the tungsten electrode rod is higher than that of the water-cooled welding torch, and because of this, when the pure tungsten electrode rod is used or when welding is performed near the rated current capacity, the tungsten particles are caused to fall off into the molten pool. in.
The water-cooled torch is designed for continuous high current welding and can be operated continuously with a welding current of up to 200 amps. Some are designed for a maximum welding current of 500 amps, which is heavier and more expensive than air-cooled torches.
The welding gun is connected to the water pipe and the related joint. Usually, the electric wire carrying the current to the electrode rod by the electric welding machine is enclosed in the outlet pipe of the water cooling water (see Fig. 3), which can provide cooling of the cable and allow for small use. Diameters, light-weight, wrapable wires, sometimes including mating parts and flow switches and fuses, leaking water or gas systems in the gun contain moisture that can contaminate the weld bead and can cause unsatisfactory operation.
Tungsten argon arc welding safety operation procedures
1. Please read the equipment manual and the corresponding training before using the equipment. You must obtain the consent of the equipment management personnel before using the equipment.
2. Before using the coolant, observe whether there is cooling water in the cooling water system. Ensure that there is enough cooling water and observe whether the circuit, gas path and waterway are connected as required.
3, argon arc welding has a higher UV intensity and a higher no-load voltage power supply, wear uniforms, caps and gloves when using the welder, personal protection should be done to avoid arcing, burns or burns.
4, close the main power switch, first start the cooling water, then open the argon cylinder valve, adjust the valve, keep a certain flow of argon, and then turn on the welding machine "target=_blank> machine power.
5, according to different welding samples using the corresponding welding specifications for welding, to ensure indoor air circulation during welding.
6, after welding, first turn off the welding machine "target=_blank> machine power, then close the cylinder valve, then turn off the cooling water, and finally turn off the total power.
Harmful factors and safety measures for argon arc welding (1) Harmful factors of argon arc welding
There are three aspects to the harmful effects of argon arc welding on the human body:
(1) The cesium in the radioactive strontium tungsten is a radioactive element, but the tungsten argon arc welding has a small radiation dose, and within the allowable range, the damage is not serious. If radioactive gases or particles enter the body as an internal source of radiation, it can seriously affect your health.
(2) When the high-frequency electromagnetic field adopts high-frequency arc striking, the intensity of the high-frequency electromagnetic field generated is between 60 and 110 V/m, which is several times higher than the reference sanitary standard (20 V/m). However, due to the short time, it has little effect on the human body. If the arc is frequently started, or if the high-frequency oscillator is used as a arc-stabilizing device during the welding process, the high-frequency electromagnetic field can be one of the harmful factors.
(3) Harmful gases - When the argon arc welding of ozone and nitrogen oxides, the temperature of the arc column is high. Ultraviolet radiation intensity is much greater than general arc welding, so a large amount of ozone and oxynitride are generated during the welding process; especially the concentration of ozone far exceeds the reference sanitary standard. If effective ventilation measures are not taken, these gases have a great impact on human health and are the most important harmful factors for argon arc welding.
(2) Safety protection measures
(1) Ventilation measures The argon arc welding work site should have good ventilation to discharge harmful gases and smoke. In addition to the ventilation of the plant, several axial fans can be installed to vent the outside air where the welding workload is large and the welding machine is concentrated.
In addition, local ventilation measures can be used to remove harmful gases around the arc, such as the use of open arc exhaust hoods, exhaust torches, and portable small fans.
(2) Shielding measures Measure the use of strontium tungsten poles with extremely low radiation dose. For the processing of tantalum tungsten and tantalum tungsten, seal or drafting wheel grinding should be used. Operators should wear personal protective equipment such as masks and gloves. Wash hands and face after processing. The tantalum tungsten and tantalum tungsten should be stored in an aluminum box.
(3) Measures to protect high frequencies In order to guard against and weaken the effects of high frequency electromagnetic fields, the measures taken are:
1) The workpiece is well grounded, and the torch cable and ground wire are shielded with metal braided wires;
2) Properly reduce the frequency;
3) Try not to use the high-frequency oscillator as a stabilizing arc device to reduce the high-frequency electric action time.
4) Other personal protective measures During argon arc welding, due to the strong action of ozone and ultraviolet rays, it is advisable to wear non-cotton overalls (such as acid resistant, silk, etc.). In the case where the container is welded and local ventilation cannot be used, personal protective measures such as a blower helmet, a blower cover or a respirator can be used.
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