Efficient Roll Casting —
Low Cost, Low Energy, Low CO2

Mainstrip Design-Features

Casting Floor

The Mainstrip concept ensures optimal availability of the plant. It thus uses two casting heads, which allow quick change of the casting heads and maximum usage of the inline rolling mill and discharge, the expensive part of an installation.

Casting Floor

Each casting head is a fully autonomous unit, which can move from the preparation area to the casting position. The cover can be displaced automatically to the side, to give access to the various machine groups.

 

Quick Change Casting Head

Casting HeadEach independent casting head consists of the complete equipment for casting the strip. To have high availability of the equipment, it is a must to have this quick change solution. Mainstrip can replace the unit like a tundish change. Whilst one casting head is in operation, the second unit can be cleaned and if needed, the rolls are resurfaced or changed at the preparation area. A quick change casting head contains the casting rolls, side dams with adjustment and changing device on each side, roll cleaning, casting rolls and positioning, drives, primary and secondary inertisation containment and the required control and measuring equipment.

 

Metal delivery

1:1 water model

Metal DeliverySubstantial development has gone into the development of the metal delivery. For this, a 1:1 water model has been built and tested. In parallel, serious CFD modeling has been carried out at the Lucerne University of Applied Science. Main and the university were supported by the Swiss governement with 2 KTI / CTI projects (Commission for Technology and Innovation).

 

 

 

Tube nozzle during filling

Tube Nozzle Various solutions for the metal deliveriy have been developed to ensure a flat bath. The tube nozzle has been created, where the liquid metal is supplied from the center outwards in the horizontal tube on the lower side and distributed evenly upwards over the width towards the start of the crystallization front and towards the side dams. This solution offers a practically flat meniscus surface. The picture shows, the simulation of filling the SEN after 0,98s.

 

Ball type submerged entry

Substantail CFD water modeling and hot testing has been carried out with a ball type submerged entry nozzle, to have an efficient, low cost solution for a width up to 1300 mm.

Casting Roll

An important Mainstrip innovative invention is the casting roll with the static axle, which is positioned in the casting frame with self sealing water plates. The sleeve is tensioned in position and is driven by the torque motor, sitting on the axle.

Casting Roll and Drive

 

The profile of the casting roll is controlled by Active Profile Control APC-elements, supported on the static axle.

The design contains a future overwidth configuration of up to 3 m and over. 

Depending on quality requirements and productivity, the respective surface is selected. Cleaning and surface preparation (including machining of coat) is done in the casting head preparation area. The rolls with the automatically removed cover, are freely accessible and can be turned, surfaced and machined, driven by the onboard drives.

For mor informatiion please contact Main Switzerland.

Roll cleaning

In casting position, it is vital to keep the roll surface at constant conditions. For this, continuous roll surface cleaning and monitoring are important. It further is to be ensured, that the surface of the rolls enter into the top sealed inert zone, without any contamination. The picture shows the Mainstrip solution, cleaning the roll surface with scratchers, brushes, laser- and gas barriers. It also includes roll crack monitoring and surface and crack detection.

For mor informatiion please contact Main Switzerland.

 

Side dams

Side DamsThe Mainstrip concept allows to change the side dam bellow the casting floor. In this way the casting floor is free of side dam manipulators or robots, which could be damaged by steel splashes and male operation. 

 

Side Dam Configurations

Various side dam configurations have been developed, from the established Bor-Nitride solution to reusable side dams in order to keep operating costs down.

Long casting sequences of 8—20 h are more then desirable, to keep the cost on tundish-, metal delivery-, roll surface-, side dams- and inline rolling mill rolls down. For the side dam plates therefore, recouperable side dams must remain a possibility. Our target is to use a combination of high temperature alloy material, working against the roll neck and coated refractory inserts on the liquid steel side. The goal is to minimise wear against the roll neck and achieve continuous, consistent operation with the long casting sequences.

For mor informatiion please contact Main Switzerland.

Side Dam Oscillation

Side Dam Oscillating DriveOscillation of side dams can improve the strip edges. In our solution, a slight movement in the direction of the roll circumference and back is simply achieved. A small oscillation drive moves the side dams. With this measures, the strip edge can be improved and possible burrs, respectively tears of the edges, can be avoided.

 

Inertisation

Essential is a complete sealing of the metal delivery and liquid surface area. The shielded volume is fed by Argon- or an Argon Nitrogen mixture, which also allows to influence the heat extraction of the rolls. The Mainstrip concept ensures, that the rolls are kept inertized on the complete circumference.

From the point, where the formed strip is leaving the casting rolls, called kissing point, it is guided through the inertisation room, to the horizontal driven insulated pinch rolls, and further to the front pinch of the first inline 4-high rolling mill stand. The horizontal part of the inertisation box can be exchanged sideways, by an induction reheating / respectively cooling box.

For mor informatiion please contact Main Switzerland.

Twin Roll Casting Head with Inertisation Room

 

Casting head with inertisation room and horizontal position, with hot transport pinch.

Thermomechanical Rolling and Discharge

The cast strip is lead by the inline pinchroll to the first rolling mill stand. After the rolling mill stand(s) the respective water strip cooling and the guiding rolls to the edgers, shear and the two coilers form the plant to the end of the process.

Existing twin roll casting machines, typically employ a single inline 4-high rolling mill stand. Depending on product- and operating cycle range, a double 4-high rolling mill stand will give advantages in terms of temperature profile, product thickness, rolling mill roll change during casting and costs. 

 

Inline Rolling

Thermomechanical Rolling and Discharge

For a wider range and the possibility to change working rolls, two inline 4-high rolling mill stands may be used.

Thermomechanical treatment

Depending on configuration, holding, heating, or cooling may be applied. Setting the inline rolling mill stand(s) in its optimum position and achieving appropriate cooling strategy, ensures the correct thermo-mechanical treatment.

For mor informatiion please contact Main Switzerland.

Plant Layout

The layout section of a Mainstrip plant shows, that the length from the ladle turret to the discharge end in this case is around 90 m.

The section shows a Mainstrip casting installation with two inline rolling mill stands.

For mor informatiion please contact Main Switzerland.

A green field mini mill Mainstrip plant with small work force requirement has been worked out:

Plant Layout Top

The layout containes a common Main control room for the EAF, LF, VD / VOD and the Mainstrip Caster.