Study Of Swirling Plasma Cutting Electrode Erosion And Cut Hardness

Plasma arc cutting has the advantages of wide application range, high precision and fast cutting speed as well as low cost; that's why it is widely used in ships, bridges, machinery and the manufacturing of other heavy equipment and steel structure. However, the currently used plasma cutting machine generally adopts DC power. But DC arc has the limitation of low arc compression level and weak arc axis directionality, which leads to that the incision always, has high hardness, wide heat affected zone (HAZ) range, and serious electrode ablation. Based on ultrasonic frequency pulsed plasma arc cutting system, this paper increases the arc stiffness and pressure by exerting an impulse of ultrasonic frequency on plasma arc cutting in order to achieve lower incision hardness, improve electrode using life and reduce the heat affected zone.This paper first proposed research purposes and content of this article, detailing the ultrasonic frequency plasma arc cutting principle and test system. Through process test, the electrical characteristics of ultrasonic frequency pulsed plasma arc were recorded and analyzed, including the current-voltage characteristics and power characteristics; the impact of pulse parameters on the electrode life, cut hardness, HAZ width were researched, thus its generation mechanism was analyzed from the view of micro-level.Utilizing double-vortex plasma cutting system, through the process test, the signal characteristics of arc were recorded and analyzed, and the impact of cutting conditions (including cutting current, cutting voltage, cutting speed, and cutting medium) on the incision hardness and the HAZ width were studied as well as its mechanism.The results showed that: In the ultrasonic frequency pulsed plasma arc cutting systems, because of the modulation of ultrasonic-frequency pulse, the degree of compression and stiffness of arc are enhanced, the arc heat transfer method and incision carburizing, nitrogen effect are changed, the hardness of incision and the HAZ width are significantly decreased and the electrode life is improved, particularly in the pulse amplitude of 1.5A, the frequency of 40K, electrode life is increased 47.8% compared with conventional cutting; in double-vortex plasma arc cutting systems, different types of gases lead to different arc power characteristics, and it is easier to obtain a higher incision hardness while oxygen as the air of plasma gas than air and HAZ width is larger; higher incision hardness is obtained in wet cutting than dry cutting, but the width of HAZ is smaller and the faster cutting speed, the smaller hardness and HAZ width of incision.