Welding equipment

1. What is a welding power supply? Answer: In an electric welding machine, a device that supplies the electrical energy required for welding and has electrical characteristics suitable for welding is called a welding power supply.

2. Why are there special requirements for arc welding power supplies? What are the requirements? Answer: In order to ensure the stable burning of the welding arc and adapt to various welding process requirements, arc welding power supplies have the following special requirements: 〈1〉 The static characteristics (or external characteristics) of the arc welding power supply - that is, the relationship between the steady-state output current and the output voltage, there are falling characteristics (constant current characteristics) and flat characteristics (constant voltage characteristics). A. The external characteristics of arc welding, TIG welding and carbon arc gouging power supplies are falling (constant current) characteristics; B. The external characteristics of CO2/MAG/MIG arc welding power supplies are flat characteristics (constant voltage characteristics). 〈2〉Dynamic characteristics of arc welding power supply——When the load state changes instantaneously (such as short-circuit transition of molten droplet, particle transition, jet transition, etc.), the relationship between the output current and output voltage of the arc welding power supply and time is used to characterize the response ability to load transients (i.e. dynamic response ability), referred to as "dynamic characteristics". 〈3〉No-load voltage——The voltage displayed by the power supply before arc ignition. 〈4〉Regulation characteristics——Change the external characteristics of the power supply to meet the requirements of welding specifications.

3. Why does the arc voltage change when the arc length changes? Answer: It is determined by the external characteristics of the arc welding power supply. The longer the arc, the higher the arc voltage; the shorter the arc, the lower the arc voltage.

4. Why does the current display value change when the wire extension length changes during CO2 welding? Answer: The longer the wire extension length (i.e. dry extension length), the greater the resistance of the wire, the greater the current consumed by resistance heat, the smaller the welding current display value, and the actual welding current also becomes smaller. Therefore, the wire extension length is generally set within the range of 12--20mm.

5. Why do the welding current and arc voltage have to be strictly matched during CO2/MAG/MIG welding? Answer: During CO2/MAG/MIG welding, adjust the welding current, that is, adjust the wire feeding speed; adjust the arc voltage, that is, adjust the wire melting speed; obviously, the wire melting speed and feeding speed must be equal to ensure stable arc welding. 〈1〉 When the welding current is constant, if the arc voltage is adjusted to a higher level, the wire melting speed will increase, the arc length will increase, the molten droplets will not transfer normally, and they will generally fly out in large particles, and the spatter will increase. 〈2〉 When the welding current is constant, if the arc voltage is adjusted to a lower level, the wire melting speed will decrease, the arc length will shorten, the wire will penetrate into the molten pool, the spatter will be large, and the weld will be poorly formed. 〈3〉 The best matching effect of welding current and arc voltage: high droplet transfer frequency, minimal spatter, and beautiful weld formation.

6. What is arc stiffness? Answer: The degree to which the arc is straightened along the electrode axis under the effects of thermal contraction and magnetic contraction.

7. Why does the welding arc have a blow phenomenon? Answer: During the welding process, the arc center deviates from the electrode axis due to the interference of airflow, the effect of magnetic field or the influence of electrode eccentricity.

8. What is magnetic blow? Answer: Arc blow caused by the electromagnetic force in the welding circuit during DC arc welding. The influence of magnetic blow can be weakened by changing the position of the ground wire or reducing the welding current and changing the electrode angle.

9. What is the self-regulation characteristic of the CO2 power source arc system? Why is CO2 welding with thin wire? Answer: Under the constant speed wire feeding system, when the arc length changes, the current and melting speed change, and the arc length recovery effect becomes the self-regulation effect of the power source arc system. The thinner the wire diameter used, the stronger the self-regulation effect of the arc, the more stable the arc, and the less spatter. This is the principle of using thin wire for CO2 welding. Tangshan Panasonic CO2 welding machine uses advanced control technology, the arc self-regulation function is the best, the performance is the most stable.

10. What is the load duration of the welding machine? Answer: The load duration refers to the ability of the welding power supply to work continuously under a certain current. The national standard stipulates that the rated load duration of manual welding is 60%, and that of automatic or semi-automatic welding is 60% and 100%. For example: the rated current of the 500KR2 welding machine at the rated load duration of 60% is 500A, and when the actual load duration is 100% (automatic welding), its maximum welding current is ≤387A.

11. What is the load duration of the welding gun? Answer: It refers to the ability of the welding gun to work continuously under a certain current. 〈1〉 For example: the rated load duration of the 350KR welding gun in CO2 welding is 70%, and the rated current is 350A; when the actual load duration is 100% (automatic welding), its maximum welding current is ≤290A. In MAG welding, the rated duty cycle is 35%, and when the actual duty cycle is 100%, the maximum welding current is ≤207A. 〈2〉 For example, the rated duty cycle of a 500KR welding gun in CO2 welding is 70%, and the rated current is 500A; when the actual duty cycle is 100% (automatic welding), the maximum welding current is ≤418A. In MAG welding, the rated duty cycle is 35%, and when the actual duty cycle is 100%, the maximum welding current is ≤296A.

12. What is the positive connection method? Answer: In DC arc welding, the connection method of connecting the workpiece to the positive pole of the output terminal of the welding machine and the welding gun (welding clamp) to the negative pole of the output terminal is called "positive connection method" or positive polarity.

13. What is the reverse connection method? Answer: In DC arc welding, the connection method of connecting the workpiece to the negative pole of the output terminal of the welding machine and the welding gun (welding clamp) to the positive pole of the output terminal is called "reverse connection method" or reverse polarity. Alkaline electrodes (such as 507), carbon arc gouging, and CO2 welding all use the reverse connection method.

14. What is the delayed gas stop time? Answer: It means that after the welding arc is extinguished, the shielding gas delays for 0.3-5 seconds before stopping the gas supply; generally, the delayed gas stop time of TIG welding of aluminum, stainless steel, titanium and other metals is as long as 3-5 seconds.

15. What is arc spot welding? Answer: For thin plate lap joints, use TIG/MIG/MAG/CO2 welding methods, use a certain welding current, form a surface molten core within a set time, and connect the upper and lower plates.