GB2279595A

GB2279595A - Continuous casting using rollers having varying radii across their width

Info

Publication number: GB2279595A
Application number: GB9411938A
Authority: GB
Inventors: Graham Leslie Thompson; Anthony Futo
Original assignee: British Steel PLC
Current assignee: British Steel PLC
Priority date: 1993-07-06
Filing date: 1994-06-15
Publication date: 1995-01-11
Also published as: GB9411938D0

Abstract

A method of casting molten metal into an extended solid comprises casting the metal between pairs of collaborating moulded rollers in which the moulding radii vary across the width of the roller. Sections of metal are produced by being continuously cast between this pair of rotating rollers. The shape of the section produced may be for example angular or ellipsoidal and may be produced as a shape of an intermediate stage to be finished by a stage of conventional rolling. The maximum and minimum radii of the casting rollers are arranged to be respectively equal so as to minimise the strain in the metal being cast. <IMAGE>

Description

CASTING This invention relates to casting and particularly to continuous casting of molten metal.

The process of casting from hot metal directly to a continuous solid is well known, for example in the Concast process for the production of steel. Efforts have been directed over the years to the production of thin steel continuous castings using a pool of molten metal trapped in the nip of a pair of rotating rollers.

Such a process was proposed by Henry Bessemer in about 1860. A diagram of his proposed apparatus appears on page 706 of The Making, Shaping and Treating of Steel published by United States Steel (ninth edition).

The Bessemer method has been experimented with since his proposal and modern day technology is beginning to enable it to be used as a practical method. However as proposed and so far experimented with the method is used for the prodilction of rectangular cross sections of steel. In many cases the rectangular cross section steel is intended for further processing and in particular to produce sections which include both angled section and elliptical section. Therefore. if such sections could be produced in casting then manufacturing steps could be saved.

It is therefore an object of the present invention to provide a method of casting to produce a section.

According to a first aspect of the present invention there is provided a method of continuous casting of molten metal into an extended solid using a pair of collaborating moulding rollers having moulding radii varying across the width of the roller.

Preferably the moulding radii are arranged so that the maximum and minimwu radii on each roller are respectively substantially the same for each roller. The section produced may have an angular or elliptical cross section.

According to a second aspect of the present invention there is provided a method of making a section in which a casting produced by the method according to the first aspect of- the invention is further processed by rolling. According to a third aspect of the present invention there is provided a section produced by the method according to either the first or second aspect of the invention.

The invention will now be described by way of example and with reference to the accompanying drawings of which Figure 1 is a diagrammatic elevation of a continuous section caster Figure 2 is a diagrammatic plan view of one and Figure 3 is a diagram of the rolls necessary for a 130 angle casting and Figure 4 illustrates that combination of rolls in casting a 130 casting.

Turning now to Figure 1 a source of hot metal 1 feeds in one of a number of conventional ways, a pair of rollers 2. The hot metal forms a small pool in the nip of the rollers and is cast by falling into the gap between the rollers which rotate to assist the process. Diagrammatically. Figure 2 shows the plan view of the rollers 2 and it will be seen that an angle section is left by the gap between them. Roller 2a has a V shaped notch in its periphery and roller 2b has a knifed edyed periphery so as to form this V shaped section between them. The section emerges at 3 and is handled in a conventional manner. It should be noted that in Figure 2 particularly the full details of the containment of the metal have not been shown in order to illustrate the principle more clearly.

Turning now to Figure 3 the dimensions of a pair of rolls in section for casting a 1300 angular section in the manner of the invention are shown. The principle variation in detail from figure 2 is that the shape of the periphery of the two rolls have added edge sections 4 designed to mate and to provide the edges to the finished section. The rotational axes of the rolls are shown at 5 and the letters A-E represent the various diameters of the rolls for various points on the shaped peripheries.

In Figure 4 a portion of each of the rolls is shown to demonstrate how they come into contact to leave a space 6 between them in which the casting is made. The rolls rotate taking in liquid metal to the casting area and discharging it in a solidifying state underneath in the form of a section.

Obviously the rolls need not be of an angular shape and in Figure 5 the shape of a pair of rolls in a similar situation to Figure 4 is shown for the casting of a ellipsoidal section. The two rolls are at 8 and 9 and the space 7 from which the ellipsoidal section is cast is shown.

The process of continuous casting of sections does flave several problems and one is the fact that the linear velocities of the peri pheri es of the rolls varies according to the rad us from the centre at a constant speed. This means that there is inevitably some slippage and strain and therefore the process is not as straightforward as might be. The range of radii that can be accommodated on each of the rolls is limited and for this reason it is suggested that the principle use of the method of continuous casting of section is to produce an initial section which can be finished by further rolling. For example the 130section can be rolled into a 90 section comparatively easily in a conventional manner and the step of forming the initial 1302 section from flat material has been avoided thus saving considerable working and energy. In a similar manner an ellipsoidal or circular section can be used as the basis of very many further sections to be created by further downstream rolling stages especially as a feed to conventional rod and wire mills.

In this way the shapes of the sections to be continuously cast can be desiyned to be those which can be cast more easily and do not impose strains on the materials beyond acceptable limits.

It will further be appreciated that. even if the range of linear speeds to be accommodated in the process has been reduced by reducing the spread of radii on any one roller there is a choice to be made as to the comparative radii of the two rollers.

Obviously the two rollers of the same radii at A and C will easily roll together at the points where they come into contact.

However. the point 7 will be a point of comparatively high strain because this will be the point on the two rolls with the radius greatest in difference from the equi radial position. A different approach would be to equalise diameters B and E: this would reduce the strain very considerably at the point 7 but in the area 8 the strain would be increased beyond that which is necessary.

In Figure 4. the spread of moulding radii has been take and the equal radius plane 10 is arranged to be mid way between the extreme moulding radii, D and B by adjusting the roll radii.

The difference between the radii A and B is the same as the difference between radii D and E, so as to minimise the strain.

This means that the maximum and minimum radii on each respective roll are made equal. This minimises the strain for any given section.

Claims

1. A method of continuous casting of molten metal into an extended solid by casting the metal between a pairs of collaborating moulded rollers in which the moulding radii vary across the width the roller.

2. A method is claimed in claim 1 in which the moulding radii arranged so that the maximum and minimum radii on each roller are respectively substantially the same for each roller

3. A method as claimed in any preceeding claim in which a section has an angular cross-section.

4. A method as claimed in any preceeding claim in which the section has an elliptical cross-section.

5. A method of making a section in which a casting is prodiced by a method according to any preceeding claim arid is further processed by rolling.

6. A section produced by a method as claimed in any proceeding cl aim.