A welding machine is a device that uses electrical energy or other energy sources to heat metals or other materials to a melting state and then joins them together. Various types of welding machines are categorized by different energy sources, currents, voltages, and arc types, such as arc welding machines, gas-shielded welding machines, resistance welding machines, laser welding machines, and electron beam welding machines. Among them, gas-shielded welding machines are commonly used. These machines use inert or active gases to protect the arc and weld pool from oxidation and contamination, improving welding quality. Gas-shielded welding machines can be divided into direct current (DC) gas-shielded welding machines and pulse gas-shielded welding machines. The latter is an advanced welding method that uses pulse current to achieve droplet transfer without spatter, providing deep penetration, fine grains, high weld strength, and suitability for all-position welding.
I. Pulse Function of Welding Machines
The so-called pulse function refers to the ability of a welding machine to output pulse current with a certain frequency and duty cycle, rather than a constant direct current (DC) or alternating current (AC). Pulse current consists of two different current levels: peak current and base current. The peak current is the higher current level in each pulse cycle, which generates enough heat to melt the metal and transfer droplets from the welding wire tip to the weld pool. The base current is the lower current level in each pulse cycle, maintaining arc stability and allowing the droplet to solidify during flight. By adjusting parameters such as pulse frequency, peak current, base current, and duty cycle, precise control over arc energy and droplet transfer can be achieved.
II. Advantages of Pulse Welding
Compared to traditional DC or AC gas-shielded welding, pulse welding has the following advantages:
Good Arc Starting Performance: The high peak voltage of the pulse current easily ignites a stable arc on the workpiece surface.
Good Adaptability of Welding Parameters to Workpieces: Pulse parameters can be adjusted according to factors like material, thickness, and position, achieving optimal welding results.
Minimal Heat Input: Each pulse cycle emits only one metal droplet from the wire tip, which solidifies during flight, meaning heat input depends only on peak current, not base current. This reduces the size of the heat-affected zone, minimizing distortion and residual stress.
Thin Workpieces with Thicker Wires: Welding The droplet size is unaffected by wire diameter, allowing for the use of thicker wires to weld thinner workpieces, enhancing welding efficiency and quality.
Low Spatter Across the Entire Pulse Power Range: Only one droplet is emitted per pulse cycle, solidifying in flight, which prevents spattering, even at high currents. This reduces cleaning work and improves weld appearance.
Good Resistance to Porosity: The droplet solidifies in flight, allowing trapped gases to escape easily, preventing porosity. High peak voltage can also break the oxide film on the weld pool surface, facilitating gas release.
Approximately 25% Higher Melting Efficiency in Spatial Welding Compared to DC Welding: Since most of the welding wire melts before reaching the weld pool, pulse welding is more efficient than DC welding, where wire melts in the pool, consuming more energy.
Good Corrosion Resistance: The droplet solidifies in flight, preventing oxidation and burn-off of alloy elements, and preserving the original composition and properties. In contrast, DC welding can cause alloy loss and degradation, reducing corrosion resistance.
III. Disadvantages of Pulse Welding
Despite its advantages, pulse welding also has the following disadvantages compared to traditional DC or AC gas-shielded welding:
High Equipment Cost: Pulse welding machines require inverter technology and digital control, increasing equipment complexity and cost.
High Operator Skill Requirement: Operators need to adjust pulse parameters according to different materials, thicknesses, and positions, requiring a high skill level and experience to achieve optimal results.
Sensitivity to Environmental Interference: Inverter and digital control technologies make pulse welding machines sensitive to power fluctuations, temperature changes, electromagnetic interference, and other environmental factors, potentially affecting stability and reliability.
In summary, the pulse function in welding machines represents an advanced welding technology, utilizing pulse current to achieve droplet transfer without spatter, offering deep penetration, fine grains, high weld strength, and suitability for all-position welding. However, it also involves higher equipment costs, greater operational skill requirements, and sensitivity to environmental factors. When using the pulse function, parameters should be adjusted according to various factors like material, thickness, and position to achieve the best welding results. Care should also be taken to protect the equipment from external influences.
For more information about the pulse function of welding machines and pulse welding, you can visit the official website of Shenzhen Megmeet Welding Technology Co., Ltd.. The company is a leading digital intelligent welding machine manufacturer in China, independently developing and producing a series of intelligent digital gas-shielded welding machines based on high-frequency power control. For eight consecutive years, it has been the market leader in welding power sources for arc welding robots in China. The company is committed to improving customer welding quality and optimizing welding efficiency, providing the best welding solutions for industries such as automotive, container, steel structure, construction materials, heavy equipment, wind power, pressure vessels, shipbuilding, home appliances, and mining machinery.
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