LU84419A1 - PROCESS FOR MANUFACTURING CYLINDERS - Google Patents

Description

-ίο 2160/8110.

METALLURGICAL RESEARCH CENTER -CENTRUM. V00R RESEARCH IN DE METALLURGIE,

Non-profit association -Vereniging zonder winstoogmerk in BRUXELLES, (Belgium).

Method of manufacturing cylinders.

The present invention relates to a process for manufacturing rolls, such as those used in rolling mills, in particular in hot rolling mills, and continuous casting installations.

It is known that the rolls of hot rolling mills, as well as the support rolls of continuous casting plants, are subjected to high temperatures and to significant mechanical forces. The combined action of these two effects quickly leads to abrasion, deformation or deterioration of these cylinders. These degradations lead to frequent operating stoppages for the replacement of said cylinders, which increases production costs./·/ h a ÿ? j.

- 2 -

To overcome these drawbacks, the said cylinders or only their working surface are currently made from a special steel, the cost price of which is quite high, but which withstands a higher working temperature.

Although this special steel resists wear at a higher temperature than ordinary steel, it is not able to withstand the contact of metal brought to high temperature for the time necessary for its work and this requires the use a cooling fluid which dissipates the quantity of heat necessary, so that the temperature of the cylinder remains compatible with the mechanical resistance properties required of said cylinder.

This restriction which imposes the use of cooling fluids is acceptable in the case of support rollers in continuous casting installations, since the cast metal is being cooled and the fluid used also contributes to this effect. On the other hand, the use of a cooling fluid during these hot rolling operations has the consequence that the metal to be worked must be heated to a higher temperature, so as to compensate for the quantity of heat evacuated by said fluid.

This additional heat addition, as well as the use of cooling fluid, increase production costs.

The method of the present invention makes it possible to obtain cylinders which have an increased resistance to wear at high temperature and which, in many cases, no longer require the use of coolant.

The process of the invention is described below, with specific reference to the case of cylinders for hot rolling mills and for continuous casting plants. This reference is / in no way limitative and has the sole purpose of clearly explaining the process of the invention. In fact, the process of the invention can be extended to all types of cylinders which must withstand working at high temperature and / or have good abrasion resistance.

The process which is the subject of the present invention is essentially characterized in that at least part of the cylinder is made of refractory material.

According to the invention, can the cylinder be made entirely of refractory material? however, preferably, only its working surface, that is to say possibly the part of its surface subjected to high temperature wear, will be made of refractory material.

According to another embodiment of the method of the invention, the cylinder, or the cylinder part, made of refractory material is produced by an agglomeration - sintering process.

As an interesting example, these refractory elements can be produced by isostatic pressing.

According to another embodiment of the method of the invention, the cylinder, or the cylinder part made of refractory material, can be manufactured by electrofusion.

For the implementation of the process of the invention, it is advantageous to use a refractory material of high purity.

In this regard, it has been found particularly advantageous, according to the invention, to use a refractory material consisting, in whole or in part, of alumina and / or of ^ / zirconium oxide.

Preferably, the refractory material used contains, by weight, 50% of A ^ O ^, 32% of ZrO ^ and 16% of

SiO ^, the balance being constituted by inevitable impurities.

- 4 -

According to a preferred embodiment of the process of the present invention, the cylinder is composed of a steel core lined with at least one element made of refractory material.

According to the invention, said refractory element can be in the form of a tubular envelope surrounding the steel core of the cylinder.

"

Still according to the invention, the refractory envelope can be made up of several adjacent elements.

In this case, and still according to the invention, it is advantageous to provide, on the contiguous faces of these adjacent elements, at least one set of recesses and projections, in order to avoid any relative transverse displacement of said adjacent elements.

According to another variant implementation of the process of the invention, said steel core can carry, on its outer surface, a number of distinct refractory elements, fixed in any way to the core and arranged according to any suitable geometrical figure. .

Ψ

Claims (12)

1. A method of manufacturing cylinders subjected to high temperatures, such as cylinders of hot rolling mills or of continuous casting installations, characterized in that at least part of the cylinder is made of refractory material. 2. Method according to claim 1, characterized in that the cylinder, or the part of the cylinder, made of refractory material, is manufactured by an agglomeration-sintering process. " 3. Method according to claim 1, characterized in that the cylinder, or the part of the cylinder, made of refractory material, is manufactured by electrofusion. 4. Method according to either of claims 1 to 3, characterized in that one uses a refractory material composed in part or in whole of alumina and / or zirconium oxide. 5. Method according to claim 4, characterized in that the refractory material used contains, by weight, 50% of Al203, 32% of Zr02 and 16% of Si02, the balance being constituted by inevitable impurities. 6. Method according to either of claims 1 to 5, characterized in that only the working surface of the cylinder, that is to say the part of its surface subjected to high / temperature wear , is made of refractory material. ^ 1 / / - 6 - 7. Method according to either of claims 1 to 6 / characterized in that the cylinder is composed of a steel core and a lining of refractory material. 8. Method according to claim 7, characterized in that the said lining is in the form of a tubular envelope surrounding the steel core. 9. Method according to claim 7, characterized in that said lining forms an envelope made of plu-. several adjacent elements. 10. The method of claim 9, characterized in that the contiguous faces of said adjacent elements have at least one set of recesses and conjugate projections. 11. Method according to claim 7, characterized in that said lining consists of a number of distinct, non-contiguous elements, preferably arranged in a suitable geometric figure. Drawings: ______— plates ___pages of which ........ d ....... cover page .......... f ....... description pages ... ..... claims pages __descriptive Luxembourg, le 12 OCT. 1982 The agent: /] / Charles München