US3881545A

US3881545A - Apparatus for casting composite cast rolls

Info

Publication number: US3881545A
Application number: US439527A
Authority: US
Inventors: Heinz Dieter Braukmann; Wolfgang Hattwig
Original assignee: Rheinstahl Giesserei AG
Current assignee: Rheinstahl Giesserei AG
Priority date: 1974-02-04
Filing date: 1974-02-04
Publication date: 1975-05-06
Anticipated expiration: 1992-05-06

Abstract

An apparatus for casting composite cast rolls which have a hard outer shell and a soft core, comprises a bottom molding box which has a lower roll pin cavity for forming the lower roll pin and which supports a permanent mold for the roll body which has a molding part with an upper roll pin cavity for forming the upper roll pin part. A pouring conduit is connected laterally and tangentially into the bottom molding box for pouring the outer shell material into the mold. The bottom molding box is supported on a trestle and it has a slide valve with an opening for discharging the excess shell material from the bottom of the cavity after the solidification of the desired thickness of the shell. A refractory tubular drain brick is connected between the slide valve and the lower portion of the lower roll pin cavity, and it is filled with granular refractory material, such as sand. The drain brick is covered with a thin refractory plate which has a marginal thin edge which rests on the granular refractory material at the top of the drain brick and completely closes the interior of the drain brick.

Description

United States Patent 1 3,881,545 Braultmann et al. May 6, 1975 APPARATUS FOR CASTING COMPOSITE 57 ABSTRACT CAST ROLLS An apparatus for casting composite cast rolls which [75] Inventor Hein Di t B k D i have a hard outer shell and a soft core, comprises a W lf Haflwig Rheinkamp, bottom molding box which has a lower roll pin cavity Baerl, both of Germany for forming the lowerroll pin and which supports a permanent mold for the roll body which has a molding [73] Asslgnee' Rhemstahl Glebere' part with an upper roll pin cavity for forming the [22] Filed: Feb, 4, 1974 upper roll pin part. A pouring conduit is connected laterally and tangentially into the bottom molding box [21] Appl' 439527 for pouring the outer shell material into the mold. The bottom molding box is supported on a trestle and it 52 us. on 164/349; 164/94 has a slide valve with an Opening for discharging the [51] Int. Cl. B22c 9/28 excess Shell at ial fr m the bottom of the cavit [58] Field of S h 1 4/3 3 3 4 3 5 366, after the solidification of the desired thickness of the 164/23, 91, 108, 353, 354, 355, 356, 94, 95 shell. A refractory tubular drain brick is connected be- 348 349 350 351 tween the slide valve and the lower portion of the lower roll pin cavity, and it is filled with granular re- [56] R f e Cit d fractory material, such as sand. The drain brick is cov- UNITED STATES PATENTS ered with a thin refractory plate which has a marginal thin edge which rests on the granular refractory mate- 1 33: 3; i rial at the top of the drain brick and completely closes 3'279002 10/1966 Meves ....I:::::..............:::::.... 164/337 the interior Ofthe drain brick- Primary Examiner-Francis S. Husar Assistant Examiner-John S. Brown Attorney, Agent, or Firm-McGlew and Tuttle 6 Claims, 2 Drawing Figures APPARATUS FOR CASTING COMPOSITE CAST ROLLS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates in general to the construction of molds and, in particular, to a new and useful apparatus for casting composite cast rolls which have a hard outer shell and a soft core, and which includes a drain brick which is filled with a granular refractory material and is covered by a thin cover which completely closes the interior of the brick.

2. Description of the Prior Art The known devices for casting rolls which have a hard shell and a soft core comprises a bottom molding box for shaping the lower roll pin and a permanent mold which rests on the bottom box and serves to shape the roll body. The apparatus also includes a mold part inserted into the permanent mold and serves to provide the shape of the upper roll pin. A pouring conduit or funnel tube leads laterally to a tangential ingate of the bottom box. The bottom box is supported by a trestle and is provided at its base with a slide valve below which a ladle is located. In operation with the slide valve closed, the shell material is filled into the mold through the pouring gate up to the level of the roll body and thereafter, upon solidification of the shell in the desired thickness, the slide valve is opened and the remaining still molten portion of the shell material is discharged into the ladle. Finally, the slide valve is closed again and the core material is filled in.

In the known arrangements, a tubular drain brick is set in the base of the bottom box defining a communication between the mold cavity and the opening of the slide valve which is lined with a refractory material. In order to prevent the shell material from penetrating into the drain brick during the filling of the mold to a location where it would instantly solidify because of the small cross-section, the interior of the drain brick, as well as that of a portion of the refractory-lined slide valve opening which is adjacent to the drain brick, is filled up with a granular refractory material. This granular refractory material must be selected very carefully. In any case, it must be completely dry. It must neither sinter with the molten iron nor become agglomerated, and it must remain fluid to be able to immediately flow out as soon as the valve is opened and to clear the passage section. A choking of the drain brick may endanger the entire casting because, unlike ladles which are sometimes provided with similar slide valves, the choking in this case is difficult to remedy because of the trestle and the ladle underneath which impedes the access to the opening. In addition, it may happen that the drain brick has to be very long, for example 30 to 60 cm, if a short roll pin is to be provided. Among materials suited for the filling of the drain brick and the adjacent portion of the slide valve opening, dry quartz sand has proved to be very convenient. Experience has shown, however, that there is a danger of the sand being washed out of the drain brick by the cast material which enters through the lateral pouring gate and consequently, there is a danger that the molten iron penetrating into the drain brick and solidifying therein in a short time will form a plug which hinders a free passage of the shell material.

SUMMARY OF THE INVENTION The present invention provides a mold apparatus for forming roll pins of different layer hardness, which comprises a drain brick which is filled with a refractory material which is covered by a refractory plate of small thickness which rests on the granular refractory material and completely closes the interior of the brick. This cover plate which completely shields the filling of the drain brick and advantageously fits flush with the upper border thereof prevents the iron from getting into and solidifying with the brick.

In a development of the invention, the refractory cover plate is provided on its bottom surface with notches which preferably extend in a diametrical direction. These notches define rated break lines to facilitate the breaking up of the plate while the supporting sand filling is permitted to run out upon the opening of the slide valve.

According to a further development of the invention, the drain brick is flared upwardly, similar to a funnel. For such a construction, the drain brick is advantageously formed in two separate parts, one a funnelshaped part, and one a cylindrical part, and each such design is arranged to permit assembly of drain bricks of different lengths with the same funnel part. The funnel part of the drain brick makes it possible to use a larger refractory cover plate which under the weight of the metal column permits the breaking up of the plate in a corresponding better manner. In addition, the funnel facilitates the outflow of the material in excess.

Another advantageous feature of the invention is the provision of a burnable alcoholic liquid black wash on the upper surface of the cover plate as well as of the drain brick. This wash is burnt off immediately upon its application. After drying up, the black wash forms a sealing connection between the cover plate and the drain brick so that the plate is securely held in place against the infiowing iron which, in consequence, cannot penetrate between the cover plate and the drain brick. It is important to burn off the coating of black wash immediately after its application in order to prevent any portion of the liquid from passing between the plate and the brick into the loose sand where it would be held back and become disturbant, for example, causing the formation of lumps, etc.

Accordingly, it is an object of the invention to provide an improved casting apparatus having a bottom molding box with a roll pin cavity for forming a lower roll pin and a permanent mold for the roll body having a molding part with an upper roll pin cavity overlying the lower roll pin cavity and which includes a slide valve arranged at the lower end of the lower roll pin cavity having a tubular drain brick therein which is filled with a granular refractory material and which is covered by a cover plate which rests on the refractory material and is flush with the top of the drain.

A further object of the invention is to provide a casting apparatus which includes a drain pipe arranged at the lower end of the cavity which is filled with a refractory material and which is closed at its outer end by a valve which may be opened after casting and wherein the drain pipe includes a cover having break lines thereon defining weakened areas to permit the fractionating of the plate during the discharge of the material from the mold.

A further object of the invention is to provide a casting apparatus which is simple in design, rugged in construction and economical to manufacture.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the Drawings:

FIG. 1 is a vertical sectional view of the lower portion of a casting apparatus for casting rolls constructed in accordance with the invention; and

FIG. 2 is an enlarged bottom plan view of the cover plate shown in FIG. 1.

GENERAL DESCRIPTION OF A PREFERRED EMBODIMENT Referring to the drawings in particular, the invention embodied therein, comprises a casting apparatus, generally designated 50, having a lower end portion which includes a bottom mold box 1 having a lower roll pin cavity 2 therein for forming the lower roll pin portion of a roll. A permanent mold or top mold portion 4 includes an upper roll pin cavity 5 which overlies the cavity 2 and is concentrically arranged in respect thereto. Cavity 2 is formed centrally within a compacted lining portion 9 which is compacted around a drain pipe or drain brick, generally designated 8, which extends to the lower end of box 1 and whose top surface is substantially flush with a level 9a of the compacted lining. Drain brick 8 extends through a fixed portion 6a of a slide valve, generally designated 6, which includes a central moving portion 6b and a lower fixed portion 60. Valve 6 includes an operating mechanism 7 in the form of a piston rod movable in the directions indicated by arrows 7a to shift intermediate parts 6b so-that the opening therethrough 52 may be positioned to either align with or moved out of alignment with a drain opening 54.

In the embodiment of the invention shown, the refractory brick 8 is made up of a tubular portion 8a of uniform cylindrical configuration and a top portion or filling portion 812 which is made in the shape of a funnel with a wider mouth portion at its top. The upper edge of upper part 8b is flush with the compacted lining level 9a of bottom box 1.

In accordance with the invention, drain pipe 8 is filled with a filling material, such as a quartz sand filling 10, and the top of the drain pipe is closed by a cover 11, having an inner portion 11a which fits through the opening at the top of funnel section 8b of drain pipe 8 and which also includes a thin top rim 1 lb which is positioned over the top end of drain pipe 8, and is substantially flush with lining level 9a. The sand 10 in the drain pipe is dry quartz sand.

In accordance with the invention, cover plate 11 is of ceramic material, such as a fireproof clay and it makes a tight closure with the top of drain pipe 8. The plate may be made relatively thin, for example, from 3 to 5 mm, and it is provided on its bottom surface with two relatively deep grooves 12 of from I to 2 mm deep which define break lines extending along the diameters. In the embodiment shown, two such break lines which intersect at right angles are provided.

In accordance with a further feature of the invention, the upper surface of cover plate 1 l and the upper front face of drain brick 8b are coated with a burnable alcoholic liquid black wash 13 which is burnt off immediately after its application in order to prevent any penetration of the liquid into the quartz sand fillingl0.

The material for casting is the outer shell of the roll pin and is directed into the lower mold cavity 2 through a fill line opening 14 which defines a tangential ingate through which the casting material is supplied to the mold.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. An arrangement for casting composite cast rolls having a hard shell and a soft core, comprising a bottom molding box having a lower roll pin cavity for forming the lower roll pin, a permanent mold for the roll body having a molding part with an upper roll pin cavity for the upper roll pin and which overlies the lower roll pin cavity, a pouring conduit for the shell material connected laterally into said bottom molding box, a trestle supporting said bottom molding box, a valve connected to the lower end of said bottom mold box and having an opening for discharging the excess shell material after the solidification of the desired thickness of the shell to be formed, a refractory tubular drain brick connected between said slide valve and said lower roll pin cavity and being filled with a granular refractory material and being located in the bottom of said bottom molding box, and a thin refractory plate covering said drain brick and resting on the granular refractory material flush with the top surface of said drain brick and completely closing the interior of said drain brick.

2. An arrangement for casting composite cast rolls, according to claim 1, wherein the bottom surface of said refractory cover plate is provided with a notch defining a break line.

3. An arrangement according to claim 1, wherein said refractory cover plate includes a bottom surface having a plurality of notches extending diametrically there-along and defining break lines.

4. An arrangement according to claim 1, wherein said drain brick is flared upwardly and outwardly to form a filling funnel at the top thereof.

5. An arrangement according to claim 1, wherein said drain brick comprises a funnel-shaped upper portion and a cylindrical lower portion.

6. An arrangement according to claim 1, including a coating of burnable alcoholic liquid black wash over said cover plate and the top face of said drain brick which is burnt off immediately after its application.