# Patent

## Title
Method of operating a reheating furnace in hot rolling line

## Abstract

This is a division, of application Ser. No. 523,753, filed Nov. 14, 1974, now U.S. Pat. No. 3,997,106.

## Background
1. Field of the Invention

The invention relates to an improved centrifuge rotor for use as part of a centrifuge.

2. Description of the Prior Art

In the prior art it has been known in various technical fields to utilize structural materials which are composed of laminations of several types of materials. The reasons for such laminations have been partially to provide greater resistance to structural loads as well as resistance to corrosion and partially to avoid any unnecessary use of costly materials.

Centrifugal rotors of the type described herein have never, insofar as I can determine, been produced as laminations of several types of materials. Up to the present no methods have been devised whereby such construction of centrifugal rotors would have been possible.

A centrifuge rotor for use as part of a rotating centrifuge which comprises a lamination of at least two layers of different materials, a first material forming an outermost layer, and a second material forming an innermost filler, the outermost layer being of greater mechanical strength than the innermost filler, and said innermost filler being preferably of a relatively chemically resistant material, such as a plastic material.

My invention also pertains to a method of manufacturing such laminated rotors for use as part of a rotating centrifuge comprising taking a cover configured in the shape of an outermost layer of the desired rotor, rotating said cover while simultaneously pouring filler material in a liquid state into said cover, continuing said rotation of said cover until the filler material is at least partially solidified to form an inner portion of a centrifuge rotor, and finishing the surfaces of said outermost and innermost layers to form said rotor.

With a rotor constructed according to my invention it is now possible to utilize the most up to date materials or a combination of known and new materials so as to achieve optimum strengths, resistance to corrosion, low specific gravity, and ease of finishing the materials such that they may be finally configured in the form of a rotor while maintaining the cost of manufacture and operation at extremely low levels.

It can be seen that the method of manufacturing the rotor according to my invention lends itself to various advantageous features which may or may not be utilized as part thereof. For example, the innermost material layer is preferably a plastic material which may be poured in liquid form into a rotating centrifuge cover in intermittent predetermined quantities (or batches) to form several laminations which cover each other and which are in adjacent relation to each other. By altering the direction of rotating of the cover between the pouring of each batch, it can be seen that a still greater reinforced structure of laminated materials will be possible.

Another advantageous feature in the practice of the method of my invention resides in heating an outermost layer in the form of a metallic cover while filling it with a liquid plastic material filler. Since the shrinkage of the metal during the subsequent cooling thereof normally exceeds the shrinkage of the plastic material, the metal cover will create biasing forces against the innermost plastic layer, thus providing inwardly directed forces which would affect the normally outwardly directed centrifugal forces to which the rotor is subjected during operation of the centrifuge.

Preferred embodiments of the invention are described hereinbelow with reference to the drawings wherein:

FIG. 1 illustrates a centrifuge rotor, partially in cross-section, and comprised of laminated structures according to the invention.

FIG. 2 illustrates an alternate embodiment of the rotor of FIG. 1.

FIG. 3 illustrates an alternate embodiment of the rotor of FIGS. 1 and 2.

FIG. 4 illustrates a view taken in the direction "A" of FIG. 3.

The rotor disclosed belongs to the so-called self-cleaning type of disc centrifugal separators. It is a matter of course that the invention is not limited to the said type of centrifugal separator.

The rotor consists of an upper part and an under part, 1 and 2, respectively, which are driven by a shaft 3 via a nut 4 and assembled by means of a nut 5. The upper part consists in this case of a cover 6 which may be of steel, and a filler 7 which may be plastics. The under part 2 consists of a cover 8 and a filler 9. Between the upper and the under parts 1, 2 is an ejection slot 10 which is opened and closed by means of an annular piston 11 with a sealing ring 12 which can be moved up and down in connection with springs 13 and a liquid chamber 14. A control liquid is conveyed through a stationary pipe 15 to the chamber 14. The rotor is further provided with known discs 16 between an upper and a lower partition plate, 17 and 18, respectively.

In operation, the centrifuge liquid enters the rotor through a stationary pipe 19, flows through bores 20, and past the lower partition plate 18 into a centrifuging chamber 21, from which the lighter phase leaves the rotor through bores 22 after passing the discs 16, whereas the heavier phase flows across the upper plate 17 and is ejected through bores 23.

Referring to FIG. 2 there is shown an alternate form of the rotor illustrated in FIG. 1 with the exception that it has a cylindrical, rather than the tapered/cylindrical configuration shown in FIG. 1. However like components bear the same identification numbers with the letter designation "a" added thereto.

FIGS. 3 and 4 illustrate alternate embodments of the rotor of FIGS. 1 and 2 wherein a wire material 24 is wound about the cover 8 of the lower part 2. The technique illustrated in these Figs.--while only shown with respect to the underpart 2 of the rotor--is also applicable to the upper part 1 of the invention. The wire material may comprise piano strings wound about the inner filler portion, or alternately the wire may be wound about a steel outermost layer. The steel outermost layer may be perforated to allow plastic material to adhere to the wire material or piano strings.

Also it should be noted that the innermost filler layer may be in the form of a plastic material having fibrous material interspersed throughout to reinforce the plastic filler material.

## Claims

1. A method of manufacturing a centrifuge rotor for use as part of a rotating centrifuge comprising taking a cover configured in the shape of an intermediate layer of said rotor and defining a plurality of perforations therein, winding an outermost layer in the form of wire material about the intermediate layer, rotating said cover while simultaneously pouring a relatively chemically resistant filler material in a liquid state into said cover at a predetermined speed and in such manner to cause a portion of the filler material to flow through the perforations defined by said intermediate layer and adhere to portions of the wire material forming said outermost layer, continuing said rotation of said cover until the filler material is at least partially solidified to form an inner layer of the centrifuge rotor, and finishing the surfaces of said outermost and innermost layers to form said rotor.

2. The method according to claim 1, further comprising prestressing said wire material about said intermediate layer to provide inwardly directed bias forces against said intermediate layer and said inner layer.

3. A method of manufacturing a centrifuge rotor for use as part of a rotating centrifuge comprising taking a metal cover having a predetermined configuration in the shape of an outermost layer of the rotor, preheating said metal cover, pouring a relatively chemically resistant filler material in a liquid state into said cover in a predetermined quantity less than the total quantity of said liquid filler material required, simultaneously rotating said cover in a given direction and at a predetermined rotational speed sufficient to place the cover in a stressed condition by outwardly directed bias forces which cause the filler material to compressively adhere to the inner surface of said cover while eliminating imperfections in the adhesion surface of said filler material, continuing said rotation of said cover in said given direction until the filler material is at least partially solidified to form an inner layer of said centrifuge rotor, continuing to pour intermittently, said liquid filler material into said rotating cover in predetermined quantities less than the total quantity of liquid filler material required, each quantity being permitted to at least partially solidify before pouring the next quantity of said liquid filler material, reversing the rotation of said cover as it is associated with the pouring of each quantity of liquid filler material so as to obtain a plurality of layers of filler material with each layer being formed in relation to a cover rotation opposite to that of the next adjacent layer, cooling said metal cover sufficient to cause the metal to shrink in excess of the shrinkage of the filler material so as to create bias forces against the innermost filler material layer capable of off-setting at least a portion of the centrifugal forces to which said centrifuge rotor is subjected during normal operation as part of a centrifuge, and finishing the surfaces of said outermost and inner layers to form said rotor.