An ultrasonic power supply system for casting and an automatic tracking method for resonant operating points

Abstract

The invention discloses an ultrasonic power supply system used in an aluminum alloy casting process and an automatic tracking method of resonance working points. The ultrasonic power supply system comprises a voltage transformation and adjustment unit, a single-phase full-bridge inversion unit, a high-frequency transformer, a tuning matching unit, an ultrasonic transducer, a driving circuit, a voltage detecting unit, a current detecting unit, a touch screen control panel, a communication interface, a control unit and an auxiliary power supply. The voltage transformation and adjustment unit is used for adjusting an inverter voltage to realize the output power adjustment of the ultrasonic transducer; the tuning matching unit is used for tuning the ultrasonic transducer in real time; the control unit is used for receiving voltage and current signals, controlling the driving frequency of the voltage transformation and adjustment unit, the tuning matching unit and the inversion unit according to an automatic tracking algorithm of the resonance working points, and guaranteeing that the ultrasonic transducer always works on the resonance points. In the aluminum alloy casting process, the ultrasonic power supply system is fast in tracking speed of the resonant frequency, wide in tracking range and high in stability.

Description

technical field [0001] The invention relates to the technical field of aluminum alloy casting technology control, in particular to an ultrasonic power supply system for applying ultrasonic vibration during the casting process. Background technique [0002] At present, in the aluminum alloy casting process, there is a method to improve the solidification structure of the metal by applying an external physical field before or during the solidification of the metal, so as to obtain high-performance casting products. Studies have shown that when ultrasonic vibration is applied to a metal melt, it will produce a series of nonlinear effects such as cavitation and acoustic flow, which will increase the nucleation rate of the metal and homogenize the overall temperature and chemical composition of the alloy. It will produce obvious grain refinement effect, which can improve the mechanical properties of aluminum alloy. [0003] The traditional ultrasonic generator adopts the self-ex...

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Problems solved by technology

[0003] The traditional ultrasonic generator adopts the self-excited oscillation analog method to generate ultrasonic waves, which rely on the self-excitation of the line to generate ultrasonic waves with a relatively narrow frequency band, and due to factors such as heat generation, aging, and load changes, the resonant frequency of the transducer will change. Deviation occurs, especially in the aluminum alloy casting process, because the tool head is immersed in the high-temperature molten immersion melt, the working temperature of the horn is high, the working environment is harsh, and the deviation of its natural frequency is greater, making the ultrasonic power supply The output power cannot be fully sent to the transducer, and the amplitude of the tool head is reduced

At present, the domestic conventional analog self-excited ultrasonic power supply is used in the aluminum alloy casting process. It is often self-excited and unreliable, and it needs to be turned on and off repeatedly. carry out

[0004] In the aluminum alloy ultrasonic casting process, depending on the casting process such as ingot specifications and temperatures, the depth of the tool head inserted into the molten aluminum will vary, which will lead to deviations in the load and resonance frequency of the transducer under different process conditions. If the ultrasonic system cannot quickly track the optimal resonance frequency point, the ultrasonic vibration will not be well applied to the solidification process of the metal, thus affecting the quality of the casting

[0005] The existing ultrasonic power supply system cannot meet the requirements of large resonance frequency deviation range and large load changes in the ultrasonic casting process

[0006] Patent CN201310524468.6 discloses a method of sweeping and searching according to the magnitude of the current effective value, but it is found through practice that the accuracy and reliability of this method need to be improved

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