What is the Gantry Mechanism in Electric Arc Furnace?
At present, electric arc furnaces use furnace top charging.
In the earliest days, the furnace top and the upper structure of the furnace such as the electrode lifting mechanism were installed on a gantry, like a gantry crane, which was driven out to the direction of the tapping slot, exposing the furnace, so that scrap steel could be added from the furnace top. The furnace body open type is that after the furnace top is raised, the furnace body mounted on the trolley is opened from the gantry frame and above the cradle, and opens towards the furnace door.
The top swing type has been widely adopted now, and the main advantage is that the metal structure of the furnace is the lightest in weight.
The top swing type can be divided into two types, namely floor type, and common platform type.
① There is a vertical rotating shaft in the furnace top lifting and turning mechanism installed on the foundation, which can lift the entire top structure of the furnace top, and then the rotating shaft rotates to unscrew the furnace top.
②The upper structure of the common platform furnace (electrode lifting and furnace roof lifting) is installed on the cantilever gantry. After the furnace roof is raised, the cantilever gantry rotates around the axis, and the wheels on the gantry can roll along the arc track on the platform.
On small stoves, the lifting and rotating mechanism of the roof is mounted directly on the furnace shell.
In this case, the furnace shell is subjected to heavy mechanical loads, and this part of the furnace shell has poor heat dissipation.
The result is a tendency to deform, requiring special cooling and reinforcement. Both floor-standing and co-platform solutions have a wide range of applications.
In contrast, the advantage of the floor type is that the electrode and the furnace top are not affected by the mechanical impact caused by the falling material during the top charging, and the problem lies in the conical column head on the upper end of the rotating shaft that lifts the upper structure of the furnace, which needs to be connected with the upper structure. Match the corresponding holes in the shelf.
In some cases, the shaft may be caught by the hole and cannot be dropped. When the furnace is rotating, the upper structure of the furnace must fit well with the furnace shell and must not move.
In principle, the furnace roof can also be turned away in the direction of the furnace door, but it is not suitable from a safety point of view.
Therefore, in most furnaces, the top of the furnace is turned about 70° to the tapping direction. 'Before the furnace top is turned away, it should be lifted upwards, 300~500mm away from the upper edge of the furnace shell.
On floor-mounted furnaces, the upper structure and the furnace roof are hard-connected and lift upwards together.
On the furnace with the common platform structure, there is another furnace roof lifting mechanism on the door frame, and the furnace roof is suspended by a chain.
The ease of roof replacement must of course also be considered when designing a furnace. Before the top of the furnace is turned away, the electrode needs to be raised so that its lower edge exceeds the upper edge of the furnace shell.
When the furnace top is turned to one side, the center of gravity of the furnace will move to this side. In order to prevent the electric furnace from tilting to the side, the furnace body and the column of the workshop should be locked before charging.
In order to prevent sideways tipping, the distance between the arc-shaped plates of the cradle of some large furnaces is wide, or the cradle is composed of three arc-shaped plates.