JP3250763B2 - Nozzle for casting containing carbon - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon-containing casting nozzle used for casting a molten metal such as steel.

[0002]

2. Description of the Related Art Ceramic fibers are widely used as heat insulating materials for casting nozzles because of their low thermal conductivity, light weight, flexibility and other properties.

[0003] The casting nozzle is preheated at the time of casting in order to prevent the occurrence of cracks due to a rapid rise in temperature of the refractory constituting the nozzle. In order to prevent spalling of the refractory due to the temperature drop from the end of the preheating to the start of casting, and also to reduce the temperature of the nozzle bore due to heat dissipation from the nozzle outer peripheral surface during casting, the solidification of steel into the bore, A ceramic fiber is provided on the outer periphery or between the outer periphery and the inner hole in order to prevent clogging of the inner hole such as precipitation of alumina clusters as intermediate inclusions.

[0004]

However, conventionally used ceramic fibers have the following problems. One is industrial hygiene. There is no free silica in the ceramic fiber before use,
It is known that when heated to 000 ° C. or higher, the surface portion gradually changes to cristobalite, a kind of free silicic acid. Free silicic acid is a typical substance causing pneumoconiosis, and the control concentration is set for mineral dust containing it. There is also a problem in the function at the time of use.
Due to the tendency of small-quantity, high-mix production of steel, there are many cases in which several steel types are cast in one cast. When the steel type is switched, the inside of the mold is maintained. At that time, the immersion nozzle is taken out of the mold and cooled, and there is a fear of spalling. The ceramic fiber has low corrosion resistance to components such as Fe and Na in the mold powder, and also shrinks due to heat load, and disappears once cast. In the case of a long nozzle, it may disappear due to scattered slag.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems of industrial hygiene of conventionally used ceramic fibers, functional problems such as spalling, low corrosion resistance, shrinkage and disappearance due to heat load, and the like. It is to provide a nozzle.

[0006]

The object of the present invention has been achieved by providing a heat insulating layer made of a heat-insulating castable refractory over a part or the entire outer peripheral surface of a carbon-containing casting nozzle.

The castable refractory used for forming the heat insulating layer has a thermal conductivity of 0.5 kc at 500 ° C. or more.
Use al / m · h · ° C or less. Above that point, it makes no sense as a substitute for ceramic fiber.

[0008] The thickness of the heat insulating layer is preferably 1 mm to 30 mm. If it is 1 mm or less, the heat insulating effect is small, and if it is 30 mm or more, there is a restriction in use in terms of continuous casting equipment.

When a heat-insulating castable is used as a heat-insulating layer, the heat-insulating castable is integrated with a nozzle in advance, and after casting the heat-insulating castable, it is set using a refractory mortar or pins, screws, or the like. In the integrated one, a mold is provided outside the nozzle, and a heat-insulating castable is cast between the nozzle and the mold. In this case, the mold may be a metal case for supporting the nozzle.

[0010]

[Action] Insulated castable refractories themselves do not cause industrial hygiene problems and disappearance such as ceramic fibers,
Compared to ceramic fiber, it is superior in heat spalling resistance and shrinkage resistance, and by applying the function of this heat-insulating castable refractory itself to a carbon-containing casting nozzle, problems in industrial hygiene and concerns about spalling, Solves functional problems such as shrinkage and loss due to low corrosion resistance heat load.

[0011]

1 to 4 show a longitudinal sectional structure of an embodiment in which the present invention is applied to an immersion nozzle and a long nozzle for continuous casting, respectively.

Embodiment 1 FIG. 1 shows the immersion nozzle body 1 having a nozzle hole 7 including the lower part of the discharge port 4 of the body part 3 below the upper wide part 2.
An example in which a heat insulating layer 5 made of an irregular refractory is provided on the outer peripheral surface is shown. In the immersion nozzle shown in FIG. 1, the main body 1 was formed of an alumina graphite material, and the portion 11 of the main body 1 which was in contact with the powder was formed of a refractory having a blend of zirconia graphite material. Further, the heat insulating layer 5 formed on the outer periphery of the body 3 of the main body 1 over the entire length thereof is made of a high alumina material containing alumina cement as a binder.
Thermal conductivity at 00 ° C or higher is 0.5 kcal / m · h
An amorphous refractory at a temperature of ° C. was formed to a thickness of 30 mm. The amount of heat transferred to the outside of the immersion nozzle was tested under the same conditions as those used. A, B, and C shown in the figure indicate temperature measurement points. When the nozzle inner hole 7 was maintained at 1550 ° C. and the inner surface A of the nozzle inner hole was 1550 ° C., the temperature at the measurement point C on the outer peripheral surface of the nozzle body was 1351 ° C. The outer surface B of the heat-insulating layer 5 made of a heat-insulating castable at that time was 1060 ° C. Thus, the amount of heat transferred to the outside was reduced by 60%.

This indicates that the heat-insulating layer 5 made of a heat-insulating castable can be sufficiently used for a carbon-containing casting nozzle as an alternative to the conventional heat-insulating ceramic fiber.

Embodiment 2 FIG. 2 shows an example in which the present invention is applied to a long nozzle having a discharge port 4 opened at the lower end. The entire outer peripheral surface of the main body 1 including the upper wide portion 2 is irregularly shaped. A heat insulating layer 5 made of a refractory is provided. Reference numeral 6 denotes a metal case provided on the upper wide portion 2 for protecting the heat insulating layer 5 with an irregular refractory. The metal case 6 may not be required depending on load conditions such as impact during use.

The inner diameter shown in FIG.
A comparison was made between an example in which a heat insulating layer 5 made of a heat insulating castable was provided in a 0 mm long nozzle and a conventional long nozzle using ceramic fibers as the heat insulating layer 5. The effective thickness of ceramic fiber is reduced with use time due to slag scattering in the TD and shrinkage due to heat load. However, the heat-insulating layer made of the heat-insulating castable according to the present invention has excellent slag resistance and shrinkage due to heat load. It was minor.

Embodiment 3 FIG. 3 shows an example in which the present invention is applied to a long nozzle body 1 having a steepest thermal gradient during casting. As shown in FIG. 1, a heat insulating layer 5 made of an irregular refractory is provided only at a position above an outer peripheral surface of a body portion 3 located below an upper wide portion 2 of a main body 1. Thereby, it is possible to sufficiently cope with a thermal gradient at the time of casting.

[0017]

According to the present invention, it is possible to obtain a casting nozzle in which a sanitary heat insulating layer is used instead of ceramic fiber which has been conventionally used as a heat insulating material.

[Brief description of the drawings]

FIG. 1 shows a first embodiment in which the present invention is applied to an immersion nozzle.

FIG. 2 shows a second embodiment in which the present invention is applied to a long nozzle.

FIG. 3 shows a third embodiment in which the present invention is applied to a long nozzle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nozzle main body 11 Zirconia-graphite refractory 2 Nozzle wide part 3 Nozzle body 4 Molten steel discharge port 5 Heat insulation layer 6 Metal case 7 Nozzle hole

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-245951 (JP, A) JP-A-4-224062 (JP, A) JP-A-2-11255 (JP, A) JP-A-1- 180761 (JP, A) JP-A-3-94966 (JP, A) JP-A-2-295655 (JP, A) JP-A-63-160761 (JP, A) JP-A-64-76975 (JP, A) JP-A-60-216972 (JP, A) JP-A-62-192254 (JP, A) JP-A-62-158564 (JP, A) Japanese Utility Model Application Sho 60-34354 (JP, U) Japanese Utility Model Application Utility Model No. 4-6352 (JP, U) Japanese Utility Model Showa 55-43616 (JP, U) Japanese Utility Model Showa 62-19234 (JP, U) Japanese Utility Model Utility Model 1-96248 (JP, U) Japanese Utility Model Showa 62-6346 (JP, U) JP 49-48047 (JP, B1) JP 52-20007 (JP, B1) JP 49-28568 (JP, B1) JP 2-503886 (J , A) (58) investigated the field (Int.Cl. ^7, DB name) B22D 11/10 330 B22D 41/54 C04B 35/66

Claims (1)

(57) [Claims] 1. A carbon-containing casting in which a heat-insulating layer made of a heat-insulating amorphous refractory having a thermal conductivity of 0.5 kcal / m · h · ° C. or less at 500 ° C. or more is provided on the outer peripheral surface of a body portion of a nozzle body. Nozzle.