Advantages of the hottest medium frequency inverte

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Advantages of intermediate frequency inverter resistance welding

compared with power frequency AC resistance welding power supply, the former has higher welding control accuracy and welding quality, which can reduce production costs and save basic investment. Medium frequency inverter DC resistance welding will become the development trend of resistance welding industry

resistance welding is a welding process that uses current to generate heat through the resistance of workpiece and welding contact surface, and applies pressure to the welding place at the same time. It has the characteristics of high production efficiency, low cost, material saving and easy automation. It is widely used in aviation, aerospace, energy, electronics, automobile, light industry and other industries. According to the nature of the power supply, it can be divided into power frequency AC welding machine, secondary rectifier welding machine, three-phase low-frequency welding machine, DC shock wave welding machine, capacitor energy storage welding machine and inverter welding machine. As a new type of control power supply, inverter resistance welding power supply has become the development direction of resistance welding power supply with its remarkable characteristics of high quality and low consumption

introduction to control system

1 The power frequency AC resistance welding control power supply

adopts two thyristors in reverse parallel connected in series with the primary winding of the welding transformer and then connected to power. Using the trigger control device, the two thyristors are powered on respectively in the positive and negative half cycles of AC. By changing the conduction angle of the thyristor, the secondary output current of the welding transformer can be adjusted

because the design principle of power frequency AC power supply is relatively simple, one parameter can be changed once, the component production technology is mature, and the manufacturing cost is low, it occupies the largest share in the resistance welding power supply

2. Medium frequency DC resistance welding control power supply

the medium frequency inverter DC resistance welding control power supply is composed of three-phase AC through the rectifier circuit into pulsating DC, and then through the inverter circuit composed of power switching devices into medium frequency square wave, which is connected to the transformer, and then rectified into less pulsating DC after voltage reduction, which is supplied to the electrode for welding the workpiece. Inverter usually adopts current feedback pulse width modulation (PWM) to obtain stable constant current output. The following is a comparison of the schematic diagrams of power frequency AC and medium frequency inverter DC welding (Figures 1 and 2)

Figure 1 power frequency AC welding principle

Figure 2 Intermediate Frequency Inverter DC welding

advantage comparison

1 Compared with the traditional SCR resistance welding machine

(1) 3-phase balanced load

3-phase balanced load, which reduces the power requirements of the power supply system and does not automatically clear any measurement system; A single phase causes peak overload, which meets the requirements of preferential electricity tariff

(2) the power factor is close to 1

there is no inductance component, and there is no need to adjust the power factor, which is much higher than the 60% efficiency of the traditional 50Hz SCR resistance welding machine. Therefore, the energy and power cost of product welding is significantly reduced

(3) eliminate the pollution to the power supply, which is clean welding

it is not necessary to provide a separate power supply, and it can be used together with the robot/welding tooling control system

(4) reduce power consumption, save energy and reduce consumption

the power demand of the workshop is low, only 2/3 of that of the traditional SCR secondary rectifier resistance welding machine, reducing the need and cost of cables. As the effective value of welding current is greatly increased, the actual welding time can be reduced by more than 20%, and the demand for welding pressure can be greatly reduced

2. Compared with AC gb/t 17657 (1) 999 test method transformer for physical and chemical properties of wood-based panel and veneer wood-based panel,

is only 1/3 of the mass and volume of AC transformer, which is light and fast; The heat input efficiency is improved; The output of welding transformer is DC voltage, without the disturbance of inductance; Pure DC has no trouble of zero crossing, and the efficiency of heat is greatly improved; The unique circuit can protect the inverter and transformer

3. Compared with traditional resistance welding

(1) the welding control current is more accurate

the inverter system is hardly affected by the power supply system, and the welding current accuracy can be controlled at 2% even under the condition of voltage fluctuation ± 15%; It is not affected by the shape and material of the workpiece (no inductance loss); The adjustment accuracy and monitoring accuracy are 20 times higher than AC 2. Power supply problem: turn on the experimental motor source system

(2) increase the stability of welding process

DC welding is technologically friendly and has a wider application prospect than AC; The secondary current can really maintain a constant current

(3) digital control improves the current control and measurement accuracy more

(4) the accuracy of welding time is milliseconds, and the welding time can be controlled arbitrarily

the traditional 50hzscr resistance welding controller, in addition to having certain advantages in price, cannot achieve ideal welding stability in the field of high quality requirements, and the quality of welding products cannot be compared with the medium frequency welding system

the use of energy-saving medium frequency inverter resistance welding products will greatly promote and promote the protection of the environment and ecological balance, as well as the regional economic development, with obvious social benefits and deeper significance. Therefore, from a long-term perspective, the application prospect of medium frequency inverter welding in related industries is considerable, and it will meet the new challenges of welding technology. (end)

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