US3892395A

US3892395A - Stopper rods

Info

Publication number: US3892395A
Application number: US400737A
Authority: US
Inventors: Ian James Hazlehurst
Original assignee: Foseco International Ltd
Current assignee: Foseco International Ltd
Priority date: 1972-09-28
Filing date: 1973-09-26
Publication date: 1975-07-01
Anticipated expiration: 1992-07-01
Also published as: GB1400248A; JPS50133931A; SE384333B; CA1002726A

Abstract

A stopper rod for use in regulating molten metal flow through an aperture is formed of a central metal bar, a refractory head, a plurality of refractory sleeves, and a plurality of fibrecontaining refractory rings filling the interstices between the head and the adjacent sleeve and between each of the sleeves.

Description

United States Patent Hazlehurst July 1, 1975 [54] STOPPER RODS 3,094,424 6/1963 Ratcliffe 266/38 X 3,5l L421 5/l970 Smith 266/38 X Inventor: Ian James Hallehurst, Guelph, 1 1 X Canada 3,6l6,l08 l0/l97l Whitehouse l. 266/38 X Assignee: Foseco lnernafional Limited 3,743,263 7/1973 Szekely 266/38 Birmingham, England FOREIGN PATENTS OR APPLICATIONS [22] Filed: Sept. 26, l973 1,168,351 lO/l969 United Kingdom 266/42 2,0l9,6l0 9/l97l Germany 266/38 App]. No.: 400,737

[30] Foreign Application Priority Data Sept 29, 1972 United Kingdom 44887/72 May 30. l972 United Kingdom 25862/72 [52] US. Cl. 266/38 [5 1] Int. Cl. F27d 3/15 [58] Field of Search 266/34 T, 34 V, 34 PT [56] References Cited UNITED STATES PATENTS 3,084,925 4/l963 Staulfer et al. 266/42 Primary Examiner-Gerald A. Dost Attorney, Agent, or FirmCushman, Darby & Cushman [57] ABSTRACT A stopper rod for use in regulating molten metal flow through an aperture is formed of a central metal bar, a refractory head, a plurality of refractory sleeves, and a plurality of fibre-containing refractory rings filling the interstices between the head and the adjacent sleeve and between each of the sleeves.

4 Claims, 4 Drawing Figures SHEET 1 STOPPER RODS This invention relates to stopper rods.

In various pieces of molten metal handling equipment, notably ladies and tundishes, an aperture is present in the base of a vessel through which molten metal may flow. One method of regulating such flow is to provide a stopper rod, the lower end of which may engage and block the aperture, and the upper end of which is held on a suitable framework. By means of levers or other mechanical linkages, the rod may be moved up or down to adjust the metal flow to the desired rate.

Naturally. in order to be able to withstand attack from molten metal, stopper rods must be made of refractory material. In order to give the desired strength, on the other hand, it is usual to provide the rod with a central steel member around which are located refractory sections. The lower end of the stopper rod is usually formed of fireclay or graphite.

The usual method of assembling such stopper rods is to slide fire clay cylinders onto a steel rod with an intermediate layer of mortar between each cylinder, to attach the graphite head to one end of the steel rod and then to compress the cylinders axially together by screwing a bolt onto the upper end of the steel rod. This compresses the mortar joints to give a satisfactory seal and the whole assembly is then dried in a furnace prior to use. After the mortar has set, the locking nut is slackened sufficiently to allow expansion of the refractory sleeves in use, and the stopper rod then installed. This method is time-consuming and cumbersome.

According to the present invention there is provided a stopper rod formed of a central metal bar, a head of refractory material and a plurality of sleeves of refractory material, the interstices between the head and the adjacent sleeve, and between each of the sleeves being filled with preformed rings of a fibre-containing refractory material, the assembly of head, sleeves and rings being held axially compressed.

The central bar is preferably of steel, the head of graphite and the sleeves of firebrick. The head may be made of one or more sections, for example an inner section which is fixed on the steel bar and an outer section which is thereafter fixed on the inner section. The rings may be made of a variety of compressible fibrecontaining refractory materials; for example, they may be formed of a compressible composition of refractory fibre, refractory filler and binder. A wide variety of such materials are known, and suitable compositions and methods of manufacture are accordingly not de scribed further here.

Stopper rods according to the invention are quick and easy to make and are ready for immediate use since no setting and drying of mortar are necessary. Instead, the members are merely assembled together and then axially compressed, e.g., by screwing a nut down along an upper threaded portion of the metal bar, until the seals between the sleeves and the lowest sleeve and the head are adequate to prevent molten metal penetration. A resilient member may be interposed between such a nut and the topmost sleeves, e.g., a compression spring or a compressible gasket. All joints between sleeves and between the lowest sleeve and the head, are thus held in compression. In use expansion of the sleeves is absorbed by compression of the gaskets. in the case where a compression spring is used between the nut and the topmost sleeve, there is a tendency, if

the spring is left unprotected, for the spring to anneal and so lose its springiness. To avoid this, such a spring may be surrounded with a protective shield, e.g., a reflective cylindercal can of steel or tinned steel. In order further to protect the spring, the space between the spring and such a shield may be filled, e.g., with a refractory heat insulating filler, refractory heat insulating fibres, or a mixture of these two. Suitable fillers are silica. Kieselguhr, perlite and others commonly used in the metallurgical industry, while suitable fibres are asbestos, slag wool, rock wool and mineral wool.

The following Examples will serve to illustrate the invention. In these Examples, reference is made to the accompanying drawings in which are shown:

FIG. I A stopper rod according to the invention, in axial section,

FIG. 2 A section of the upper end of the modified stopper rod,

FIG. 3 A section of the lower end of a further alternative form of rod FIG. 4 A section of the lower end of a further alternative form of rod.

EXAMPLE l In order to make the stopper rod shown in section in FIG. 1 and for use in a 125 ton ladle for steel casting, the following parts were used:

I. one steel rod 270 cm long, 5.7 cm diameter 2. one bonded graphite head, width 20 cm (2) 3. l0 firebrick sleeves, each of height 225 cm, outer diameter 20 cm and inner diameter 6.25 cm 4. l0 rings of heat insulating compressible material, each of uncompressed thickness 1.25 cm 5. one coverplate and 6. nut.

The parts were assembled as shown in the drawing and nut 6 screwed down until the total length of the sleeves 3 and rings 4 was 231 cm, Le, a compression of each ring 4 of 50%.

The stopper rod so made took about 7 minutes to assemble and could be used immediately. The rod stood up to as many casting cycles before being scrapped as a conventional rod made with mortar and furnace dry- The ring had the following composition (by weight):

aluminium silicate fibre 60% colloidal silica sol (30% SiO 16% phenolformaldehyde resin 2% calcined alumina 22% Alternatively, the rings used had a composition of (by weight):

aluminosilicute fibre colloidal silica sol (30% solids) the rings being of sufficient thickness that the final compression of each ring was of the order of In an alternative and preferably construction shown in FIG. 2, the topmost ring 4 was replaced by a compression spring 12 located between nut 6 and coverplate 5. A heat-reflective shield 20 surrounds the spring 12, and the space between the shield 20 and the spring 12 is filled with heat insulating material 22 such as a particulate refractory material or refractory fibrous or mixtures of these.

EXAMPLE 2 The stopper rod shown in FIG. 3 is made up in somewhat different fashion: Refractory sleeves 3 and rings 4 are first assembled on a steel rod 1 in much the same fashion as in FIG. 1, the sleeves and rings resting on a graphite end piece 7, which is sealed to the lowest sleeve 3 by a ring of sealant material 8, such as described in Example 1, and which is held in place by a nut 11 which engages on the lower end of the steel rod. The upper nut 6 is then threaded on to the steel rod and tightened down. A ring 4 is located below the lowest sleeve 3 and a graphite head 9, is then tightly screwed on to end piece 7 to complete the assembly of the stopper rod. Ring 8 is held tightly compressed, while rings 4 are only lightly compressed.

EXAMPLE 3 ln this construction, shown in FIG. 4, the mode of assembly is generally as for FIG. 2, save that in this case ring 8 and the lowest of rings 4 are replaced by a single disc seal 10. Sealing disc 10 may be made of either of the compositions specified in Example I. The inner portion of sealing disc 10 in contact with endpiece 7 is compressed harder than its outer annular portion.

I claim:

1. A stopper rod formed of a central metal bar threaded at one end and carrying at its other end a head of refractory material, a plurality of sleeves of refractory material, and a plurality of preformed rings of a fibre-containing refractory material filling the interstices between the head and the adjacent sleeve and between each of the sleeves, the assembly of head, sleeves and rings being held axially compressed by a nut engaged on the threaded end of the bar with a compression spring interposed between the nut and the adjacent sleeve, a heat-reflective shield surrounding said spring, the space between said shield and said plate being filled with a heat insulating material selected from the group consisting of particulate refractory material, fibrous refractory material and mixtures thereof.

2. A stopper rod according to claim 1 wherein the metal bar is of steel, the head of graphite and the sleeves of firebrick.

3. A stopper rod according to claim 1 wherein the head is formed of an inner section fixed to the metal bar and an outer section fixed on the inner section.

4. A stopper rod according to claim 1 wherein a compressible gasket is interposed between the nut and the adjacent sleeve.