1. What is a welding power source?
In an electric welding machine, the device that provides the electrical energy required for welding and has electrical characteristics suitable for the task is called a welding power source.
2. When the arc length changes, does the arc voltage also change?
The arc voltage in arc welding is determined by the external characteristics of the arc welding power source. The longer the arc, the higher the arc voltage, and the shorter the arc, the lower the arc voltage.
3. During CO2 welding , when the extension length of the welding wire changes, does the current display value also change?
The longer the welding wire extension length (i.e. dry extension length), the greater the resistance of the wire, which leads to greater current consumption for resistance heat, resulting in a lower displayed current value of welding and at a reduced actual welding current. .
To mitigate these effects, the welding wire extension length is typically set between 12 and 20 mm.
4. When CO2 / MAG/MIG welding, should the welding current and arc voltage be strictly matched?
During CO2 /MAG/MIG, it is important to adjust both the welding current (i.e., the welding wire feed speed) and the arc voltage (i.e., the welding wire melting speed). To obtain a stable arc welding process, the melting speed and welding wire feeding speed must be balanced.
(1) If the welding current is kept constant and the arc voltage is increased, the melting speed of the welding wire will also increase, leading to a longer arc length and the inability of the droplets to transfer normally. This often results in larger particles flying and increased spatter.
(2) On the other hand, if the welding current is kept constant and the arc voltage decreases, the melting speed of the welding wire will decrease, causing the arc length to become shorter and the welding wire to enter the melting pool. This results in increased spatter and poor weld formation.
(3) The best match between welding current and arc voltage will result in high droplet transfer frequency, minimal spatter and beautiful weld formation.
5. Is there any special requirement for arc welding power supply? What are the requirements?
To maintain a stable arc welding process and meet various welding requirements, an arc welding power source must have specific requirements.
(1) One of these requirements is the static characteristics (or external characteristics) of the arc welding power source, which refers to the relationship between the steady-state output current and the output voltage. There are two types of external characteristics: drop characteristics (constant current characteristics) and flat characteristics (constant voltage characteristics).
The external characteristics of power supplies for stick arc welding, TIG welding and carbon arc gouging are descending type (constant current). On the other hand, the external characteristic of power sources for CO2/MAG/MIG arc welding is flat type (constant voltage).
Related Reading: MIG vs TIG Welding
(2) Dynamic characteristics of arc welding power source: The dynamic characteristics of an arc welding power source refer to its ability to respond to load transients such as droplet short-circuit transitions, particles and jet transitions. This is characterized by the relationship between the output current, the output voltage and the time in which the charge state changes instantaneously.
(3) No-load voltage: Refers to the voltage displayed by the power supply before the arc starts.
(4) Regulation characteristics: Refers to the ability of the power source to adjust its external characteristics to meet the requirements of welding specifications.
6. What is arch stiffness?
Under the influence of thermal contraction and magnetic contraction, the arc is straight and runs along the axial direction of the electrode.
7. What are the phenomena of partial blowing of the welding arc?
During welding, the center of the arc may deviate from the electrode axis due to factors such as airflow interference, the effect of a magnetic field, or the impact of electrode eccentricity.
8. What is the positive connection?
During DC arc welding, the workpiece is connected to the positive terminal of the electric welding machine's output and the welding gun or clamp is connected to the negative terminal. This wiring method is known as the “positive connection method” or positive polarity.
9. What is the reverse connection?
During DC arc welding, the workpiece is connected to the negative terminal of the welding machine output and the welding gun or clamp is connected to the positive terminal. This is known as the “reverse connection method” or reverse polarity. Alkaline electrodes (such as E507), carbon arc gouging and CO 2 welding use the reverse connection method.
10. What is magnetic polarization?
During DC arc welding, arc blowing is caused by the action of electromagnetic force in the welding circuit. The effects of magnetic strike can be reduced by adjusting the position of the ground wire, decreasing the welding current and changing the electrode angle.
11. How long does the welding gun charge?
Refers to the ability of a welding gun to operate continuously at a specified current.
(1) For example, the 350kr welding gun has a rated load duration rating of 70% during CO2 welding and a rated current of 350A. When the actual charge duration rate is 100% (for automatic welding), the maximum welding current should not exceed 290A. For MAG welding, the rated load duration rating is 35%, and with an actual load duration rating of 100%, the maximum welding current should not exceed 207A.
(2) Another example is the 500kr welding gun, which has a rated load duration rating of 70% and a rated current of 500A when welding with CO2. When the actual charge duration rate is 100% (for automatic welding), the maximum welding current should not exceed 418A. In MAG welding, the rated load duration rate is 35%, and at an actual load duration rate of 100%, the maximum welding current should not exceed 296A.
12. Self-regulating characteristics of CO 2 arc power system? Why are thin wires used for CO 2 Welding?
Under the constant speed wire feeding system, changes in arc length result in changes in current and melting speed, making the role of arc length recovery a self-regulation function of the electric arc system.
When a smaller diameter welding wire is used, the arc self-regulation is stronger, leading to a more stable arc with less spatter. This is the principle behind the use of fine wire in CO 2 Welding.
Tangshan Panasonic CO. 2 The welding machine uses advanced control technology to achieve the best arc self-regulation and the most stable performance.
13. How long does the welding machine charge?
Load duration refers to the ability of a welding power source to operate continuously under a specific current.
According to national standards, the nominal load duration for manual welding is 60%, while for automatic or semi-automatic welding it is 60% and 100%, respectively.
For example, a 500KR2 welding machine has a rated current of 500A when its rated load duration is 60%. However, when the actual charge duration is 100% (during automatic welding), its maximum welding current should not exceed 387A.
14. What is arc spot welding?
For a thin plate lap joint, the TIG, MIG, MAG or CO2 welding method is used to create the surface nugget and join the top and bottom plates within a specified period of time using a designated welding current. .
15. How long is the delay?
In other words, once the welding arc is turned off, the shielding gas can persist for 0.3 to 5 seconds before the gas supply is stopped.
Typically, the delay time for stopping the shielding gas in TIG welding for aluminum, stainless steel, titanium and other metals is about 3 to 5 seconds.
