JPS5919789B2 - How to repair sliding nozzle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sliding nozzle for molten metal, and more particularly, to a method for repairing the upper nozzle of the sliding nozzle.

As is well known, sliding nozzles are attached to pots, tundishes, and the like for storing molten metal such as molten steel, to flow out, stop, or control the amount of molten metal flowing out.

FIG. 1 is a cross-sectional structural diagram showing a well-known general sliding nozzle.

In the figure, the sliding nozzle includes an upper nozzle holding hardware 2 connected to the bottom iron shell 1a of a pot or tundish (hereinafter simply referred to as the pot 1), an upper plate 3 held by the holding hardware 2, and a pot nozzle brick. It consists of an upper nozzle 4 fitted into the upper nozzle 1b, a lower plate 5 that slides in contact with the lower surface of the upper plate, and a lower sliding metal fitting 7 that integrally surrounds the lower nozzle 6.

The lower sliding hardware 7 is connected to a drive device 9 such as a cylinder device via a link mechanism 8, and moves forward and backward by driving the drive device 9 to open and close the nozzle hole 10.

Incidentally, in the sliding nozzle, the upper nozzle 4 is significantly worn out due to the outflow of molten metal.

For this reason, in the past, for example, the upper nozzle 4 was manufactured from a highly corrosion-resistant material, or it was made into a two-layer structure in which a highly corrosion-resistant material was mixed on the inside and a normal material was mixed on the outside and molded at the same time. was proposed and attempts were made to put it into practical use.

However, with none of the above conventional means, a significant extension of the life can be expected, and rather the problem is that the unit cost of the furnace material rises due to an increase in the unit price of the upper nozzle 4.

The present invention was devised to fundamentally solve the above-mentioned problems, and is intended to significantly extend the service life of the upper nozzle and significantly reduce the unit consumption of furnace materials. Its purpose is to provide a repair method.

Hereinafter, the present invention will be described in detail based on figures showing examples.

Now, FIGS. 2 and 3 show one embodiment of the present invention, with FIG. 2 being a diagram showing the state of the poling process, and FIG. 3 being a partial sectional view showing the upper nozzle after the repair is completed.

In FIG. 3, reference numeral 11 indicates a refractory sleeve prepared in advance, and the refractory sleeve 11 is fitted inside the upper nozzle 4 which has been subjected to a polling process.

If the upper nozzle 4 is worn out due to the outflow of molten metal, for example, as shown in FIG. 1 is tilted, and the inside 4a of the upper nozzle 4 is cut (poled) using a boring machine 12 until it reaches a predetermined inner diameter.

This poling process may be performed when the wear of the upper nozzle 4 reaches the permissible amount by predetermining an allowable amount of decrease in wall thickness (hereinafter simply referred to as allowable amount) due to the wear of the upper nozzle 4.

The above-mentioned allowable amount takes into account the size of the upper nozzle 4 and the joint structure with the upper plate 5, etc., and reduces the remaining wall thickness of the nozzle 4 to prevent the upper nozzle 4 from cracking due to leakage of molten metal or thermal stress. It may be set as appropriate within a range that has reasonable physical strength and within a range that allows the fireproof sleeve 11 to be easily manufactured.

Therefore, it is called periodically or each charge (one cycle in which the entire amount of molten metal stored in the pot is discharged).

), the wear amount of the upper nozzle 4 is measured and inspected, and the timing of polling processing is set.

The fireproof sleeve 11 is made to conform to the above-mentioned tolerance, that is, to have an outer diameter that is approximately the same as the inner diameter of the upper nozzle 4 that has been finished by polling, and the same as the designed inner diameter of the father upper nozzle 4 (initial inner diameter without wear). Manufactured to the same inner diameter.

However, in the experience of the present inventors, when the fireproof sleeve 11 and the upper nozzle 4 are loosely fitted, cracks occur in the fireproof sleeve 11 due to movement of the fitted fireproof sleeve 11 or thermal shock caused by repeated application of high temperature and room temperature. However, sufficient effects could not be obtained.

Based on this knowledge, as a result of repeated experimental research, it was confirmed that the above-mentioned problem can be effectively solved by urgently fitting the fireproof sleeve 11 to the upper nozzle 4.

In other words, by tightly fitting the refractory sleeve 11, the upper nozzle 4 can firmly hold the refractory sleeve 11, and as a result, the physical strength of the refractory sleeve 11 against thermal shock etc. is significantly improved, and the life of the refractory sleeve 11 is increased. Upper nozzle 4
It has become possible to significantly extend the lifespan of.

As described above, the present invention predetermines the allowable amount of wall thickness reduction due to upper nozzle wear, and when the wear of the upper nozzle 4 reaches the above-mentioned allowable amount, the inside of the upper nozzle 4 is polled to achieve a uniform inner diameter. After that, the upper nozzle 4 is regenerated by tightly fitting the refractory sleeve 11 on the inside.If the timing of the polling process is properly determined, the refractory sleeve 11 can be simply replaced. The upper nozzle 4 can be used repeatedly, and as a result, the service life of the upper nozzle 4 is greatly extended, making it possible to drastically reduce the furnace material consumption in the pot 1.

Incidentally, the fireproof sleeve 11 may be made of the same material as the upper nozzle 4, or may be made of a higher quality material that has better corrosion resistance, abrasion resistance, etc. than the upper nozzle 4.

Furthermore, in addition to preparing only one type of fireproof sleeve 11 with the same outer diameter, by preparing several types of fireproof sleeves 11 with different outer diameters within the above-mentioned allowable range, it is possible to reduce the polling of the upper nozzle 4. Processing can be minimized,
It is an effective method.

The refractory sleeve 11 fitted into the upper nozzle 4 is tightly fitted as described above, and its lower surface is held by the upper plate 3, so simply fitting it inside the upper nozzle can achieve the above effect. However, as shown in Fig. 3, for example, it is possible to coat or fill the outer and upper surfaces of the refractory sleeve 11 with mortar 13 or the like to make the fit more secure, and this may be adopted as appropriate. Good.

Now, in one embodiment in which the present invention is applied to a 185 ton molten steel ladle, the service life of the conventional ladle was only 15 charges at most, but the present invention has made it possible to greatly extend the service life to 32 charges or more, and the sliding nozzle It was confirmed that the basic unit of furnace material for the molten steel ladle alone can be significantly reduced by 24%, and for the entire molten steel ladle by 19%.

In this example, the inner diameter of the upper nozzle 4 after polling is 91 to 92 mm, and the outer diameter of the fireproof sleeve 11 is 90 mm.
m, and the gap was as small as about 0.5 to 1 mm.

As described above, the practical effects of the present invention are very significant.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional structural diagram showing a well-known general sliding nozzle, and FIGS. 2 and 3 are a diagram showing a poling process according to an embodiment of the present invention, and a partial cross-sectional view showing the upper nozzle after repair. be. 1... Pot, 2... Holding hardware, 3...
...Top plate, 4...Top nozzle, 5.
... lower plate, 6 ... lower nozzle,
7...Lower sliding hardware, 8...Link mechanism, 9...Drive device, 10...Nozzle hole, 11...Fireproofing Sleeve, 12...
Boring machine, 13... mortar.

Claims (1)

[Claims] 1. For the upper nozzle of a sliding nozzle for molten metal, an allowable amount of decrease in wall thickness of the upper nozzle due to wear due to molten metal outflow is determined, and when the wear of the upper nozzle reaches the above-mentioned allowable amount, the inside of the upper nozzle is polled. death,
A method for repairing a sliding nozzle for molten metal, comprising tightly fitting a refractory sleeve inside the nozzle to regenerate the upper nozzle.