Hand welding practice problem_v - Edwards @ Wiki

5 TIG welding and combination welding

Question 5.1 Equipment for TIG welding

1. Supply of mixed gas of Ar and He prevent oxidation and nitridation
2. Supplies electricity by drooping characteristics and constant current characteristics
3. Supplied molten metal is composed mainly of tungsten
   with high melting point and low consumption
4. Using supplied molten metal of almost the same quality as the base metal except thin plate

Question 5.2 Equipment for TIG welding

1. Supply gas is Ar or He
2. Penetration is low depth, welding is low speed
3. It is possible to use direct current exchange
4. Restrict spatter generation and improve bead appearance

Question 5.3 Characteristics of TIG welding

1. Welding to various metals by supply of inert gas
2. The occurrence of sputtering is restricted
3. Small occurrence of fume
4. Easy adjustment of weld metal by supplying filler rod into generated arc
5. Welding at low speed with respect to welding direction
6. Low efficiency by low penetration

Question 5.4 Additional characteristics of drooping characteristics
and constant current characteristic circuit to TIG welding

1. Supply current is constant for fluctuation of arc length
2. Prevents large current supply against short circuit in welding
3. Easy arc maintenance at low current due to high no-load voltage

Note:Gouging: Removal of defects and unnecessary parts using welding machine

Question 5.5 Additional characteristics of drooping characteristics
and constant current characteristic circuit to TIG welding

1. In the case of direct current welding,
   the molten metal supply side is welded at the negative electrode
2. Forming bead by pulse control for inverter voltage control
3. Even for AC power output, the arc starting high frequency generating circuit is interposed
4. Characteristics in low-frequency pulsed welding
   1. Effective for thin plate joining by melting and solidification mutual welding
   2. Suppresses flow of molten metal against longitudinal and lateral welding

Question 5.6 Control of TIG welding machine

1. Pre-flow: gas is discharged by processing of gas control circuit
   before starting welding machine
2. Crater processing function: Low current arc discharge function for welding end
3. After flow: release of protective gas to weld metal
   and electrode after arc extinguishment

Question 5.7 Control of TIG welding machine

1. Additional effect of preflow: impurity release in gas hose
2. Conversion to high frequency output: Arc can be generated omitting short circuit
3. Crater process: Current is reduced by manual control against weld ending
4. After flow: Cooling high temperature electrodes to prevent oxidation

Question 5.8 Effect on use of Ar

1. Ar is an inert gas with a mass higher than the atmosphere
2. Liquefied argon cylinder surface is gray and colored
3. Ar is high pressure filling
   with 14.71M~[Pa]\~fallingdotseq~14.71\times9.8~fallingdotseq~150~[kgf/cm^{2}]
4. Measures against falling by fixing against installation of cylinder

Question 5.9 How to handle welding rod

1. Attract welding defects due to grease or fouling

Question 5.10 Handling of filler rod

1. For welding rods for manual TIG welding, 1000 to [mm] is the standard dimension
2. Measures against rust prevention / pollution / grease against welding rods
3. Limited to fusion bonding with omission of energization
4. Rust prevention is realized by copper coating on welding rod for mild steel

Question 5.11 Application of electrode rod

1. Electrode rod component / mixture
   1. Pure tungsten
   2. Thorium oxide (thoria)
   3. Lanthanum oxide
   4. Cerium oxide

• DC welding: Oxidizing electrode rods are often used
  • Arc start is good
  • Arc concentration / stability is good
  • In the positive electrode, a large diameter electrode is selected

• AC welding: A lot of pure tungsten electrode rods are used
  • By omitting the DC output conversion circuit, the cleaning effect is good
  • Arc concentration improved by selection
    of lanthanum oxide / cerium oxide electrode
    • Compliant with triatungsten electrode for selection of oxidation electrode

Question 5.12 Coloring with respect to electrode rod termination

• Color is selected for the type / content of mixed components
  • YWP: pure tungsten electrode rod: green color
  • YWTh-1: 1 [\%] Tri-tungsten electrode rod: yellow color
  • YWTh-2: 2 [\%] Tri-tungsten electrode rod: red color
  • YWLa-1: 1 [\%] Lanthanum tungsten electrode bar: black color
  • YWLa-2: 2 [\%] Lanthanum tungsten electrode bar: black green color
  • YWCe-1: 1 [\%] Cerium tungsten electrode rod: pink color
  • YWCe-2: 2 [\%] Cerium tungsten electrode rod: gray color

Question 5.13 Types of TIG welding

1. DC Electrode Negative Electrode Welding: Penetration is Used for Large / Various Metals
2. DC electrode positive electrode welding: large amount
   of electrode exhaustion / cleaning effect combined
3. Pulse TIG Welding: Used for stainless steel etc.
4. AC welding: mainly used for aluminum alloy / with cleaning action

Question 5.14 Types of TIG welding

1. AC power supply: Pure tungsten electrode is often used for aluminum alloy
2. Low-frequency pulsed power supply: It is often used for thin plate joining
   by melting and coagulation repetition with respect to base metal
3. High frequency pulsed power supply: Since the arc is stable against low current,
   it is also applicable to thin plate bonding
4. DC power supply / electrode positive electrode: low erosion and cleaning effect combined

Question 5.15 Filling rod / electrode rod

1. Tungsten electrode: \Phi 0.5 to 6.4 [mm]
2. Tip: Process from 30 to 40 [^{circ}]
3. Nozzle: Metal formation used at high current for ceramic formation

Question 5.16 Definition of extra length of electrode rod

1. Distance from nozzle tip to electrode tip tip
2. Attract tungsten entrainment against surplus length excess
3. Adjust the extra length according to the state of the welded joint
4. Attract welding operation failure against surplus excess

Question 5.17 Tack welding

1. Reliable penetration
2. Tack weld required
3. Joining outside the groove joint
4. Combined use of backside gas

Question 5.18 Treatment for TIG welding without touch start function

1. At the same time as high frequency generation,
   an arc is generated by maintaining the distance between the tip
   of the electrode rod and the base metal at 3 [mm]
2. At the re-touch start, re-cutting the electrode rod and polishing the base material
3. Attract welding defect by melting rod tip against proximity of electrode rod base metal

Question 5.19 Treatment for TIG welding without touch start function

1. At the same time as high frequency generation, an arc is generated by maintaining the distance
   between the tip of the electrode rod and the base metal at 3 [mm]
2. The tip of the electrode rod is separated from the base material against arcing
3. At the re-touch start, re-cutting the electrode rod and polishing the base material
4. Attract welding defect by melting rod tip against proximity of electrode rod base metal

Question 5.20 Special note on welding condition

1. Strengthening control of grooves with proper current
2. Constrained arc length
3. The tip shape of the electrode rod acts on the back welding

Question 5.21 Treatment for TIG welding without touch start function

1. Inner wave welding of middle plate and thick plate is welded
   to the thin plate at the back of the groove
2. Strings and pitch suppressed against backwave welding
3. The first layer uniformly melts the base materials
   and continuously forms an appropriate molten pool
4. Secure adequate interlaminar welding for welding after the second layer