US 4,537,243 AGranted

Method of and apparatus for steam preheating endless flexible casting belt

AssigneeHazelett Strip-Casting Corporation

InventorsRobert W. Hazelett, John F. B. Wood

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Abstract

The casting belt is preheated with steam closely ahead of the entrance to the casting zone by providing wrap-around steam feed tubes having nozzles, such tubes being positioned in very deep circumferential grooves in input pulley or nip pulley which moves the casting belt into the input end of the casting zone. These circumferential grooves of the input or nip pulley also house wrap-around liquid coolant feed tubes for cooling the casting belt near the beginning of the casting zone. The wrap-around steam feed tubes also have radial ports positioned to direct steam toward the reverse side of the endless belt, with the port being spaced from the nozzle thereby providing a staged elevation of temperature in the flexible casting belt on the input or nip pulley, while the belt is in contact therewith before the belt reaches the casting zone. Elevating the temperature prior to the endless belt reaching the casting zone and then suddenly cooling the belt when the molten metal is applied thereto improves casting conditions in the operation of such thin, flexible casting belt and enhances and speeds up the casting process. There are several ways for preventing coolant water from cooling the steam header and tubes of the bottom nip pulley in a twin-belt machine.

Claims29

Dependent claims

In the continuous casting of molten metal wherein the molten metal is contained and moved along in a casting zone having an input end and an output end by at least one thin, flexible endless casting belt, said output end of said casting zone being downstream from said input end of said casting zone, said casting belt having a front surface carrying said molten metal in said casting zone and having a reverse surface and wherein the casting belt travels partially around curved guide means adjacent to the input end of the casting zone with the reverse surface of the belt being curved concave where the belt travels around said guide means, the improved method of preheating the casting belt before it reaches the input end of the casting zone comprising the steps of:

providing said guide means with deep circumferential grooves adjacent to said curved reverse surface of the casting belt,
conducting steam along confining passages within said deep grooves,
impinging first jets of steam directed radially outwardly from said confining passages in said deep grooves against the reverse surface of the belt for producing a first stage of elevation of the belt temperature before the belt reaches said input end of said casting zone,
said first jets of steam being located upstream of the input end of the casting zone by an angular distance of at least 45.degree. defined by the arc of a 45 degree angle as measured from said first jets to the input end of said casting zone with an axis of curvature of said guide means defining the apex of said angle,
impinging second jets of steam aimed downstream from said confining passages in said deep grooves contacting the reverse surface of the belt with the steam in said second jets travelling downstream for producing a second stage of elevation of the belt temperature following said first stage of elevation of the belt temperature in front of the position where the belt reaches said input end of said casting zone and for creating a downstream flow of steam in said deep grooves travelling downstream toward the input end of said casting zone,
said second jets of steam being angularly spaced downstream by a second angular distance of at least 20.degree. from said first jets,
conducting coolant liquid along other confining passages within said deep grooves, and
impinging jets of liquid coolant aimed downstream from said deep grooves striking the reverse surface of the belt at an angle of incidence less than 25.degree. near to the input end of the casting zone and travelling downstream along the reverse surface of the belt as the belt enters the casting zone.

5 more elements

In a machine for continuously casting molten metal wherein at least one thin, endless, flexible casting belt having a front face and a reverse face revolves around pulleys and passes along a casting zone having an input end and an output end, said output end of the casting zone being downstream from said input end, said belt moving along said casting zone from the input end to the output end of the casting zone for carrying the metal being cast against the front face of the casting belt through said casting zone, apparatus for preheating said casting belt with steam comprising:

an input pulley for moving said casting belt into the input end of said casting zone,
said input pulley having circumferential grooves therein underlying the reverse face of said casting belt as said casting belt revolves partially around said input pulley in moving toward and into the input end of the casting zone,
wrap-around steam feed tubes each having a nozzle on the end thereof, said steam feed tubes and nozzles being positioned in the respective circumferential grooves of said input pulley,
said steam feed tubes each having radial steam ports aimed toward the reverse face of the casting belt for applying steam from said radial ports to the reverse face of said endless belt near to the input end of the casting zone for preheating said belt before said belt enters the input end of said casting zone,
said radial steam ports being located upstream of the input end of the casting zone by a first angular distance of at least 45.degree. defined by an angular arc as measured from said first jets to the input end of said casting zone with an axis of rotation of said input pulley defining the apex of said angle,
said nozzles being located downstream from said radial ports by a second angular distance of at least 20.degree. from said radial ports, said second angular distance being defined by an angular arc as measured from said radial ports with said axis of rotation defining the apex thereof, and
said nozzles being aimed downstream for applying steam travelling downstream from said nozzles impinging against the reverse face of the belt nearer to the input end of the casting region than said radial ports for producing a second stage of preheating said belt before the belt reaches said input end of the casting zone,
said two stages of steam preheating reducing belt distortion caused by the tremendous heating effect of the molten metal for thereby enabling the speed of the casting machine to be increased.

5 more elements

Dependencies are inferred from the claim text.