GB2024065A

GB2024065A - Runner pipe for a bottom pouring ingot mould plate

Info

Publication number: GB2024065A
Application number: GB7921110A
Authority: GB
Original assignee: Thyssen AG
Current assignee: Thyssen AG
Priority date: 1978-06-19
Filing date: 1979-06-18
Publication date: 1980-01-09
Also published as: DE2826606C2; FR2429054B3; DE2826606B1; GB2024065B; FR2429054A1

Abstract

A prefabricated runner pipe has thin-walled tubes (6) of high grade refractory material arranged end-to- end and surrounded by a jacket (7) of inexpensive mineral substances mixed with a binder. The unit is made in a mould whose cross-section is preferably slightly less than that of the plate or centre runner to be lined. When the jacket is at least partially set the entire runner pipe is inserted into the plate or runner, any voids between the plate or runner and the jacket (7) being filled with sand. <IMAGE>

Description

SPECIFICATION Method and unit for lining a bottom-pouring plate and/or a centre runner of a bottom pouring ingot mould assembly The present invention relates to a method and to a unit for lining a bottom-pouring plate or a centre runner of a bottom-pouring ingot mould assembly.

The insertion of conventional runner bricks into the bottom-pouring plate and of sleeve.

bricks onto the bottom-pouring plate and into the centre runner is very labour-intensive and time-consuming. Moreover, the radiation of heat can impose a great strain on the operating personnel: the bottom pouring plate becomes heated to a high temperature during the casting process and after the pouring it only cools slowly due to its high thermal capacity and relatively limited cooling surface.

In order to facilitate the bricklaying operation German Patent Specification 2,619;211 has proposed a bricklaying apparatus in which a plurality of individual runner bricks are preassembled to form a unit which is then lowered into the bottom pouring plate with the aid of the bricklaying apparatus. By means of an apparatus of this kind it is thus possible to make the job of lining bottom-pouring plates simpler to carry out.

In addition, it is well known that the dimensions of runner bricks and sleeve bricks are standardised in order to reduce the number of brick sizes (see "Stahl und Eisen"-1978pages 32-36). Thus, sleeve bricks have a standardised length of 270 and 330 mm and runner bricks a standardised length of 1 70 to 420 mm. Runner bricks usually have square outside dimensions. In order to reduce the cost of high grade refractory material it was proposed in the 1920's (German Patent Specifications 436,255 and 454,536) to construct runner bricks in two layers so as to provide a brick having only an inner core of high grade refractory material, while an outer jacket layer may consist of low grade material, for example loam. According to Specification No.

454,536 (which was a patent of addition) the core projects beyond one end face of the jacket, so that the runner bricks disposed endto-end one behind the other can be inserted into one another by means of a tongue and groove connection. These two-layer runner bricks have to be laid in a time-consuming manner on the warm or hot bottom-pouring plate, so that the well known inconvenience to the operating personnel cannot be avoided.

It is an object of the present invention to provide a method and means which, while considerably reducing the inconvenience to operating personnel, will make it possible for a bottom-pouring plate or a centre runner to be lined in an inexpensive and time-saving manner.

According to a first aspect of the present invention there is provided a unit for lining a bottom-pouring plate or a centre runner of a bottom-pouring ingot mould assembly, the unit including a plurality of thin-walled tubes of high grade refractory material arranged end-to-end and a casing of mineral material mixed with a binder, the casing forming a jacket around the tubes and having external dimensions which are equal to or are less than corresponding internal dimensions of the said bottom pouring plate or centre runner.

According to a second aspect of the present invention there is provided a method of lining a bottom pouring plate or a centre runner of a bottom pouring ingot mould assembly comprising the steps of: forming a jacket of mineral material mixed with a binder around a plurality of thin-walled tubes arranged end-toend and made of high grade refractory material, the jacket being formed in a mould whose internal dimensions are equal to or are less than the corresponding internal dimensions of the said bottom pouring plate or centre runner; and, when the mineral substances are at least partially set, transferring the unit comprising the tubes and the moulded jacket to the said bottom pouring plate or centre runner. Both the unit and the method of the present invention are particularly applicable to the bottom-casting of steel ingots.

The wall thickness of each individual tube is preferably selected so that during a casting the wear does not exceed the wall thickness of the tube. In typical embodiments the wall thickness of the high grade refractory material can amount to from 5 to 20 mm, particularly from 7 to 1 5 mm. The individual thin-walled tubes preferably have a tongue and groove connection. At least 40% by weight, prefera- bly from 40 to 60% by weight of the preassembled unit may consist of the mineral substance which is inexpensive.

The external dimensions of the shaped multi-layer preassembled unit are selected in dependence on the cross-sections of the bottom pouring plate or centre runner which is to be lined. The unit is preferably chosen so as to be slightly undersized so that it can easily be inserted. Any void between the jacket and the bottom pouring plate or centre runner can be filled with sand, for example. Depending on the length of a runner arm of the bottom pouring plate, a preassembled unit may have a length of more than 2 metres, or even of more than 3 metres.

One or more of sands, ashes, slags, and tuffs (porous rock material) can be used as inexpensive materials for the jacket of mineral material. The binder mixed with the mineral substances may be a water-binding or a chemical binder to ensure adequate strength in the jacket. It may be advantageous for reinforcement, particularly an iron reinforcement, to be additionally provided in the jacket, in order to improve the stability and strength of the preassembled units of larger size.

The mineral substances of the jacket can be mixed with heat insulating material. Thus, it may be advantageous for the jacket to contain from 10 to 40% by weight of heat insulating material (for example porous clay). The heat insulating material protects the steel flowing in the riser and runner system against excessive cooling.

In the production of the prassembled units it is possible for the centre runner to be given different internal cross-sections along the di reaction of flow of the steel, for each runner arm. Furthermore, it can be advantageous for the preassembled unit to be designed specifically for one type of ingot mould, so that the central position of the centre runner hole or holes can always be achieved. If desired the preassembled unit can have different diameters for the individual ingot moulds.

An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings, wherein: Figure 1 is a plan view of part of a bottom pouring plate; Figure 2 is a section on the line ll-ll in Fig.

1; Figure 3is a section on the line Ill-Ill in Fig. 1; and Figure 4 shows on a larger scale transverse cross-section through a preassembled unit.

Referring firstly to Figs. 1 and 2 a bottom pouring plate 1 has four runner arms 2 (only one of which is shown) and a centre runner 3 which is disposed at the centre of the pouring plate. The runner arm 2 is lined with a preassembled unit 4. The centre runner 3 is lined with a preassembled unit 5 (see also Fig. 3).

The preassembled unit 4 of the runner arm 2 constitutes a single unit of about 3.60 metres in length. In contrast, in the prior art method about twelve runner bricks would have to be inserted into the runner arm 2 in order to line it. A similar numerical comparison can be made between the prior art and the lining of the centre runner 3.

Referring now to Fig. 4 in addition to Figs.

1 and 2 the preassembled unit 4 has a multilayer construction comprising a plurality of thin-walled tubes 6 arranged end-to-end and surrounded by an outer jacket 7. High grade refractory material is used only for the individual inner tubes 6 which are joined by tongue and groove connections. The outer jacket 7 surrounding the tubes 6 consists essentially of inexpensive mineral substances, for example sand and slag. Porous clay for example can be added as a heat insulating material to the mineral substances. The substances are mixed with a binder and are shaped in a mould to form the preassembled unit 4. The mould is so shaped that it corresponds to the square cross-section of the runner arm 2 which is to be lined, but includes a small allowance so that the jacket is undersized.In each corner of the square cross-section of the jacket of mineral substances there is disposed a reinforcement 8 which increases the strength of the larger sized preassembled unit 4 so that it can be safely removed from the mould to the bottom pouring plate. Riser holes 9 are provided in the runner arm 2.

The refractory lining of the centre runner 3 is likewise in the form of a preassembled unit 5 of multilayer construction. Inner high grade tubes 6 are encased by a jacket 7 of inexpensive mineral substances. The jacket 7 of mineral material is continuous, so that the joints (not shown in the drawing) of the thin-walled individual tubes 6 are covered over and the breaking-out of the molten steel can thus be prevented.

It is thus possible with the present invention to produce away from the bottom pouring plate, an inexpensive preassembled unit without the need to use a constructionally expensive bricklaying apparatus. An operating team can insert the prefabricated unit into the runner or centre riser of a bottom-pouring plate in a short time and are considerably less inconvenienced by the heat of the plate.

Moreover the continuous nature of the outer jacket 7 eliminates the risk of a breakout of e.g. molten steel, which risk does not exist with a conventional tongue and groove connection. In addition the cost of the lining is substantially reduced as the use of expensive refractory material is decreased by as much as 40 to 60%.

Claims

1. A unit for lining a bottom pouring plate or a centre runner of a bottom pouring ingot mould assembly, the unit including a plurality of thin-walled tubes of high grade refractory material arranged end-to-end and a casing of mineral material mixed with a binder, the casing forming a jacket around the tubes and having external dimensions which are equal to or are less than corresponding internal dimensions of the said bottom pouring plate or centre runner.

2. A unit according to claim 1 wherein the mineral material comprises at least 40% by weight of the weight of the unit.

3. A unit according to claim 1 or claim 2 wherein the mineral material includes one or more of sand, ash, slag and tuffs.

4. A unit according to any one of the preceding claims wherein the jacket includes heat insulating material.

5. A unit according to any one of the preceding claims including one or more reinforcement members extending longitudinally through the jacket.

6. A unit according to any one of the preceding claims wherein the tubes each has a wall thickness in the range of from 5 to 20 mm, preferably in the range of from 7 to 1 5 mm.

7. A lining unit for a bottom-pouring plate or for a centre runner of a bottom pouring ingot mould assembly substantially as shown in and hereinbefore described with reference to Figs. 1 to 4 of the accompanying drawings.

8. A method of lining a bottom pouring plate or a centre runner of a bottom pouring ingot mould assembly comprising the steps of: forming a jacket of mineral material mixed with a binder around a plurality of thin-walled tubes arranged end-to-end and made of high grade refractory material, the jacket being formed in a mould whose internal dimensions are equal to or are less than the corresponding internal dimensions of the said bottom pouring plate or centre runner; and, when the mineral substances are at least partially set, transferring the unit comprising the tubes and the moulded jacket to the said bottom pouring plate or centre runner.

9. A method of lining a bottom pouring plate br a centre runner of a bottom pouring ingot mould assembly comprising transferring a unit according to any of claims 1 to 7 to the said bottom pouring plate or centre runner.

10. A method according to claim 8 or claim 9 including the step of filling voids present between the jacket of mineral substances and the said bottom pouring plate or centre runner with sand.

11. A method of lining a bottom pouring plate or a centre runner of a bottom pouring ingot mould assembly substantially as herein described with reference to Figs. 1 to 4 of the accompanying drawings.