After extensive research Vesuvius came up with a new generation of tube changer by modifying the older versions and making the new one more robust, simple having fewer parts and with more ease of installation and maintenance. The new mechanism can offer additional advantages of less air entrapment and operation in fully automatic mode for casting long sequences.
Tube changer design
Cassette
The cassette holds the refractory and the pressure loading device. The cassette has two variants one meant for normal operation having a bore size of less than 85mm and other meant for extra-long refractory having bore dia greater than 85 mm and offers a throughput greater than 4.5 tonnes per minute.
Monobloc inner nozzle plate clamping device
The clamping device ensures tight attachment of the monoblock inner nozzle plate to the mechanism having facility for argon purging. The design of this refractory piece has been calculated by finite element analysis. A canned nozzle plates design which has a parallelepiped flange with two 45 degree tapered faces ensures that the clamping forces are directed at 45 degrees towards the center. This strong design helps to maintain precise positioning of the refractory in the cassette and secured locking of the piece with the help of two rotary wedges pressing on two rockers. This type of clamping helps in the reduction of stress peaks and horizontal compression forces are directed towards the plate sector of the refractory elements.
Some of the pushing rockers are provided with an argon injection facility. The argon input holes with graphite gasket located at the tapered face of nozzle plate flange ensure airtight sealing when the rockers are in the pushing position and have provisions for two independent networks for argon filling in the nozzle plate as well as in the sealing groove located in the sliding surface. This brings about the exact tuning of argon flow in each zone.
Monobloc submerged entry nozzle design
The new monobloc SEN has a flange that looks similar to the inner nozzle plates. Six high-temperature resistant springs apply a direct force at 45° on the tube through six pushers (not rockers) and generate a combination of vertical and horizontal forces on the flange of the tube. The pusher elements can be easily removed from outside for inspection.
Blank plate
An emergency shut-off blank plate rests on the blank plate holder having a push bar provisions and can be immediately fired at the time of emergency thereby providing enhanced safety for operation.Tube/Blank submerged nozzle plate having a double stroke cylinder is a new concept developed for avoiding the need for a separate blank plate.
Two kinds of cassettes can be combined with different driving mechanisms, such as Pneumatic shifting drive with push-bar and side-mounted cylinder, hydraulic shifting drive with push-bar and side-mounted cylinder and manual swing arm mounted hydraulic shifting drive.
Pneumatic shifting drive with push-bar and side-mounted cylinder offers increased flexibility where the system is not powered by hydraulic supply and the cylinder is directly attached to the tube changer cassette. It is a simple control system, which facilitates automated tube change.
Hydraulic shifting drive with push-bar and side-mounted cylinder- The drive is attached to the tube changer cassette but the cylinder is detachable which remains either on the tundish car or on the mechanism. It is connected with quick couplings. It can bring about automated tube change
Installation on the tundish bottom
Similar to the TCD design, the new cassette is fixed by four studs welded directly to the tundish shell which enables any eventual tundish deformation to be accommodated without alteration of the tube changer cassette flatness. It is easier to install than a mounting plate.
