Electrode translation control system for an electric arc furnace

An electric arc furnace electrode lift subsystem, comprising:

• (a) three electrodes,
• (b) an independently operable electrode lifting hydraulic cylinder for each electrode, and
• (c) an electrode vertical translation control system for independently controlling each electrode lifting hydraulic cylinder, the electrode vertical translation control systems in fluid communication with a common pump for pumping hydraulic fluid from a reservoir to the electrode lifting hydraulic cylinder and each electrode vertical translation control system including at least:
• (i) a primary single action proportional control valve in hydraulic communication between the pump and the electrode lifting hydraulic cylinder via a first hydraulic line and in hydraulic communication between the electrode lifting hydraulic cylinder and the reservoir via a second hydraulic line, the primary single action proportional control valve operable for (A) effecting controlled hydraulically powered vertical lifting of the attached electrode when actuated into a first position whereby hydraulic fluid is pumped via the first hydraulic line into the electrode lifting hydraulic cylinder, and (B) effecting hydraulically unpowered gravity induced vertical dropping of the attached electrode when actuated into a second position whereby hydraulic fluid flows under force of gravity via the second hydraulic line from the electrode lifting hydraulic cylinder to the reservoir, and
• (ii) a secondary proportional valve in fluid communication with the second hydraulic line between the primary single action proportional control valve and the reservoir operable for effecting controlled gravity induced flow of hydraulic fluid from the electrode lifting hydraulic cylinder to the reservoir through the second hydraulic line so as to effect controlled drop of the attached electrode.

An electric arc furnace electrode lift subsystem, comprising:

• (a) three electrodes,
• (b) an independently operable electrode lifting hydraulic cylinder for each electrode, and
• (c) an electrode vertical translation control system for independently controlling each electrode lifting hydraulic cylinder, each electrode vertical translation control system including at least:
• (i) a pump for pumping hydraulic fluid from a reservoir to the electrode lifting hydraulic cylinder,
• (i) a primary single action proportional control valve in hydraulic communication between the pump and the electrode lifting hydraulic cylinder via a first hydraulic line and in hydraulic communication between the electrode lifting hydraulic cylinder and the reservoir via a second hydraulic line, the primary single action proportional control valve operable for (A) effecting controlled hydraulically powered vertical lifting of the attached electrode when actuated into a first position whereby hydraulic fluid is pumped via the first hydraulic line into the electrode lifting hydraulic cylinder, and (B) effecting hydraulically unpowered gravity induced vertical dropping of the attached electrode when actuated into a second position whereby hydraulic fluid flows under force of gravity via the second hydraulic line from the electrode lifting hydraulic cylinder to the reservoir, and
• (iii) a secondary proportional valve in fluid communication with the second hydraulic line between the primary single action proportional control valve and the reservoir operable for effecting controlled gravity induced flow of hydraulic fluid from the electrode lifting hydraulic cylinder to the reservoir through the second hydraulic line so as to effect controlled drop of the attached electrode.