Why the correct matching of high frequency welding machine is very important

During solid state high frequency welding, the ability to deliver all of the welder's power to the work coil is determined by the match between the impedance (load) of the coil and the ratio of the transformer's maximum output voltage to maximum output current .

If these values are not adjusted to be equal, it is impossible for the welder power to be fully output to the coil. A 400kW welder might only be delivering 200kW to the coil if the match between the load and the drive is reduced by 50%. In this way, the production speed of the unit will be lower than that achieved if the welder load is perfectly matched. The specific performance is that the speed of the car cannot be driven up.

The coil as a part of the resonant oscillating circuit determines the welding frequency. If the coil inductance required by the frequency converter is poorly matched, a welding machine designed to work at 300KHz may only run at 200KHz because 50% of it is not matched. Will seriously affect the quality of welded pipes.

Why is matching important at all power levels?

We all know that in the process of high-frequency welding, the production line is subject to various load changes, and the quality of the weld changes with the change of load. What we need is a constant and stable output, which is a must for high-quality welds.

In the actual production process, welding speed (vehicle speed), welding frequency, welding power, opening angle, position of resistor, working condition of resistor, size of magnetic flux, thickness of steel strip, diameter of welded pipe, cooling water temperature, and even Deburring and the habits of operators in different teams all affect the load matching, so maintaining the best matching is the premise to ensure the consistent welding quality of welded pipes. Any of the above changes in the welded pipe production process will cause changes in the load of the welder, which is why a high-frequency welder with an automatic matching system is the best solution to ensure high-quality weld quality. For manufacturers pursuing high-quality welded pipes, no matter how the external factors (load) of the production line change, a high-frequency welding machine can intelligently enlarge the process window, and it is the most scientific and convenient way to digest these load changes through automatic matching .

Can a voltage inverter welder perform load matching as accurately as a current inverter welder?

Most voltage inverter welding machines match the load by changing the contact points on the RF transformer. If you want to perform load matching, you need to continuously change the contacts of the transformer, which is basically impossible to adjust when the welder is working continuously.

For the current inverter welding machine, through the automatic matching system, the load matching is automatically maintained without the participation of the operator, and the welding machine can always work in the best load matching state to ensure stable weld quality of the welded pipe.

Sematur speed power control system (automatically adjust output power according to unit speed) and Sematur automatic matching system (Auto-Match) will automatically correct load changes throughout the production process, when the welding machine is working and load matching At the same time, the output power and welding frequency can meet the requirements accurately and maintain dynamic maintenance, so that corrections can be made when the welding load changes to ensure consistent weld quality.

Why is welding frequency such an important parameter?

From the history of the development of high-frequency welding machines, the frequency of around 400KHz has been proved to be the best frequency for the induction welding process. The welding frequency determines the width and extrusion of the steel strip, and these parameters are necessary conditions to achieve good welding quality. High frequency can reduce the depth of current penetration, this phenomenon is called "Skin Effect (Skin Effect)". The skin effect concentrates the heat at the edge of the weld near the surface, resulting in a quality forge weld with minimal pinching. On the contrary, the low frequency causes more places to be heated at the edge of the weld, and in severe cases, it will cause embrittled cast welds. Only the reduction of the width of the steel strip used will save the cost of raw materials for the manufacturer by hundreds of thousands of yuan. The welding frequency also interacts with the set parameters of the unit, such as profile, opening angle and other roll geometry parameters. In addition, the high-frequency welding process will be more sensitive to the settings of the above parameters in the low-frequency state. If the cooperation is not good, it will cause more substandard products and unstable welding quality.

Besides the mechanical parameters of the unit, what else is related to the frequency?

The performance of the impedance is also frequency dependent. All resistors are limited by their saturation flux density, the so-called flux conduction capability. If this limit is exceeded, the resistor will stop working. The magnetic flux in the resistor changes with frequency conversion. For example, a normal working impedance will withstand twice the magnetic flux at 200KHz than at 400KHz. Reducing the welding frequency may require adding more impedance materials (magnetic rods). When welding small-diameter thick-walled pipes, the quality and magnetic flux of the impedance (magnetic rods) are particularly important due to the limitation of actual space conditions.