Side dam with insert

Abstract

A composite side dam for a continuous twin roll caster includes a substrate made of a refractory material capable of withstanding casting temperature and having edge portions adapted to engage casting rolls and having a nip portion adjacent a nip between casting rolls and upper portions extending across the side dam to form a lateral restraint for a casting pool, an insert of at least 10 mm in thickness positioned in a pocket in the substrate and extending to engage the molten metal and extending from the upper portions of the substrate and positioned in the pocket to within 30 mm from the nip portion by insertion adjacent the upper portions of the substrate, and the insert adapted to fit into the pocket of the substrate to form a side dam formed of a refractory material having consumption rate less than 10 mm per hour. The material forming the insert may be between 40 and 60% SiAlON material and the remainder hBN material, or mullite material as described by FIG. 11, or between about 60 and 63 mole percent Al2O3 and the remainder SiO2, or fused silica, such as between 40 and 60% fused SiO2 and the remainder hBN material.

Description

BACKGROUND AND SUMMARY[0001]This invention relates to the casting of metal strip by continuous casting in a twin roll caster.[0002]In a twin roll caster, molten metal is introduced between a pair of counter-rotated casting rolls that are cooled so that metal shells solidify on the moving roll surfaces and are brought together at a nip between them. The term “nip” is used herein to refer to the general region at which the rolls are closest together. The molten metal may be delivered from a ladle into a smaller vessel or series of smaller vessels from which it flows through a metal delivery nozzle located above the nip, forming a casting pool of molten metal supported on the casting surfaces of the rolls immediately above the nip and extending along the length of the nip. As the molten metal formed into shells are joined and pass through the nip between the casting rolls, a thin metal strip is cast downwardly from the nip.[0003]The casting pool is usually confined between side dams he...

AI Technical Summary

Benefits of technology

This patent describes a way to increase the lifespan of side dams in a twin roll caster by using a composite side dam. This composite side dam is made of a refractory material that can withstand the high temperatures of a twin roll caster. The composite side dam has edge portions that engage with the casting rolls and a nip portion that helps to control the flow of molten metal in the caster. Additionally, an insert is used that engages the molten metal and helps to protect the casting rolls. By using a composite side dam, the lifespan of the side dams is increased and the cost of casting thin strip is reduced.

Problems solved by technology

As the casting rolls are rotated, the side dams experience frictional wear, causing arc-shaped grooves to form in the side dams along the circumferential surfaces of the casting rolls.

Wear and replacement of the side dams has usually limited the casting campaign, where the casting campaign was typically stopped and the worn side dams replaced.

The core nozzles and tundish with remaining useful life were typically replaced at the same time so the length of the next campaign is not limited, with attendant waste of useful life of refractories and increased cost of casting steel.

Also, the side dams wear independently of the core nozzles and tundish, and independently of each other.

The biasing forces applied to the side dams may be reduced after an initial wear-in period, but there continued to be significant wear of the side dams throughout the casting operation.

The useful life of the side dams has remained a limiting factor in the length of casting campaigns and the cost of casting thin strip.

The consumption rate due to contact with molten metal of the refractory material forming the insert may be at least as great as the wear rate due to abrasive contact with the casting rolls of the material forming the substrate.

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