JPS583788B2 - Renzokuntensuruchiyuzokikaiyouobijyoukanagata - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a strip mold for a continuously operating casting machine, which has a coating layer of particles of ceramic material on the surface of the strip mold facing the melt.

In continuous casting methods, such as those carried out in known Hazelet casting machines, flowing metals such as aluminum, zinc, copper, steel and their alloys are
It is cast between two endless strip molds and often carries a ceramic layer.

These strip molds, generally made of steel, are guided and driven over deflection rollers and support rollers, thus creating a casting gap into which the flowing metal is introduced.

After that, solidification takes place between the two band-shaped molds.

The cooling and solidification of the melt can be controlled by a ceramic layer attached to the side facing the melt.

Controlling the cooling in this manner has a significant effect on the surface quality and metal structure of the cast strip.

The coating layer that must be applied to the endless strip molds of such casting machines has several features in order to be suitable for the production of high-quality strip castings, such as is required in the aluminum industry, for example. Required conditions must be met.

Although the above conditions are described here for the purpose of casting aluminum, it should be understood that they include both pure aluminum and aluminum alloys.

1. The layer must be resistant to high temperatures since it is brought into contact with the fluidized aluminum to be solidified.

2. Since the solidification of the molten material into the band is carried out uniformly and in a controlled manner so that the solidified shell does not form unevenly from the endless band-shaped mold, the above-mentioned layer has a thermally insulating effect. There is.

Furthermore, it must be avoided that the endless strip mold becomes overheated due to direct contact with the melt.

Overheating will distort the endless mold, so that contact with the solidifying metal and thus heat extraction is interrupted.

Distortion of the endless strip mold therefore results in the production of a cast strip that is unsuitable for use.

Thermal insulation provided by the layer prevents the steel mold from overheating.

The thermal resistance of the layer is, according to the invention, between 10-4 and 10-3 m. to obtain good results. h. It needs to be within the range of °C/Kcal.

3. The layer and the molten or solidified metal must not stick to each other.

In other words, the ability of the layer to be wetted by liquid aluminum and its tendency to stick to solidified metal must be extremely small.

If this were not the case, the produced band castings would have deposits of layer particles, which is absolutely unacceptable for high-quality products.

Furthermore, excessive adhesion between the metal being cast and the layer may cause the layer to tear.

4. The layer must resist temperature changes.

This is because when in contact with the fluid metal, this layer heats up to a high temperature very quickly, and after the coated steel strip mold is removed from the solidified strip casting, it is rapidly cooled again by cold water. This is because it is cooled.

5. The layer must also have a certain flexibility so that the coated steel mold can be guided over the deflection rollers.

6. The layer must have good adhesion to the steel strip mold in which it is applied.

The surface of the strip steel mold is roughened to increase its adhesion.

7. No particles must be transferred from the layer to the casting strip.

After all, if this happens, the quality of the band-shaped casting will be significantly reduced.

8. The degree of surface roughness of the above-mentioned layer is extremely small, and the band-shaped casting must always maintain a smooth surface so as not to interfere with processing.

9. The coating must be able to be applied to a uniform thickness so that heat transmission is uniform throughout the mold strip.

If this is not the case, serious defects will result in the strip casting.

10. The lifetime of the layer should be several hours, preferably one shift time, ie more than 8 hours.

Now, a number of layers are known that meet some of these requirements.

However, these layers do not simultaneously satisfy all of the above requirements.

Certain layers may consist of silicone resin combined with various inorganic fillers, such as, for example, ceramic materials or diatoms.

However, all these resins used as binding agents are
Insufficient temperature resistance.

Excessive temperature loads can thereby lead to cracking of the organic resin, which destroys the layer and renders it inoperable.

The several components of the layer then result as a mixture or with a corresponding heat transmission index.

You may be forced to create different layers. Now, the problem underlying the present invention is to overcome all of the above-mentioned requirements imposed on known band-shaped molds, to achieve a quality that is comparable to that achieved hitherto, and on the other hand, to achieve a high quality band-shaped mold with minimal fractures. The object of the present invention is to provide a strip mold for a continuously running casting machine, which has a long service life and, on the other hand, guarantees better quality of the strip castings.

The above object is achieved according to the invention in that the particles are at least partially welded to the band surface and are bonded to each other by phosphorization and/or fusion.

Obviously, due to the porosity that occurs during thermal coating, 60
The flexibility available up to relatively large layer thicknesses of up to 0 μm makes it possible to produce layer thicknesses with the required thermal transmission index for the majority of ceramic materials.

For example, Al2O3, CaZrO3, Al2O3, Mn
According to the invention, several 80-2 ceramic layers consisting of O, ZrSiO4 or Al2O3.TO02
10 thin layers of 50 μm, preferably 100-200 μm
It is mounted on an endless strip mold until the desired thickness is reached, yielding the desired thermal resistance in the range -4 to 10-3 m2.h.C/Kcal.

The main advantages of the ceramic coating layer of the present invention, in contrast to known coatings, are that, in addition to its high temperature resistance, it does not shatter, making it possible to produce high-grade strip castings free of coating particles. This results in a significantly improved service life and therefore effective protection of expensive strip steel molds.

With a ceramic coating, preferably applied by thermal spraying, the casting operation can be carried out continuously without interruption for many days.

The surface of the layer applied by the thermal spraying method described above may be mechanically polished, e.g., to create a uniform roughening of the mold surface and a wetting relationship between the layer and the solidified aluminum. It can be advantageously processed by

Such processing makes it possible to significantly improve the quality of the aluminum strip for special purposes, since the surface roughness and thus the solidification conditions can be changed.

Therefore, if part of the above layer is used by the particulate diffusion method, the lifespan of the layer will be slightly increased since it will be protected against direct contact with the liquid metal; We must bear the risk of causing the rupture of the material.

The coating layer of ceramic material carried by the thermal injection gun according to the invention has a certain porosity so that large amounts of moisture can move freely around the sides of the casting machine. , it can absorb moisture.

As a result, the service life of the strip mold is significantly reduced.

Now, in order to eliminate such drawbacks, the ceramic layer of the band-shaped mold of the present invention is coated with a sealing body made of an organic resin, at least one fine inorganic substance, or a colloidal lubricant. was taken.

Next, the operation and effects of the present invention will be explained in more detail with reference to the drawings showing embodiments of the present invention.

As shown in FIG. 3, the device for coating the band-shaped mold includes a tensioning cylinder 9 driven by an electric motor and a plasma injection device 10.
and a device 11 for roughening the surface of the band-shaped mold, such as side blasting, and the stretching cylinder 9 is heated at a speed of, for example, 12-14 m/min by an electric motor together with the band-shaped mold.
The vehicle is subjected to a slow rotational motion corresponding to the traveling speed of the vehicle.

On one side of the rotating barrel, use corundum with a particle size of 200-700 μm, preferably 200-400 μm, and
It operates at an injection pressure of 6 to 6, preferably 4-5 atmospheres.

A device 11 is provided for roughening the surface of the band-shaped mold.

Immediately following the roughening of the surface, a ceramic layer is applied to this part of the mold strip using a plasma gun.

Please refer to Table 1 attached at the end. The powder used for the ceramic coating preferably has a particle size of 10-100, especially 20-50 μm.

When the tension drum rotates, the plasma device generates about 8-
The coating is applied to a 20 mm wide strip.

By simultaneously moving the plasma device perpendicular to the direction of rotation of the cylinder, i.e. parallel to its axis, at a rate of advancement of 4 to 1.2 mm per rotation of the tension cylinder, the entire surface of the strip-shaped mold is Evenly coated with ceramic mass.

Argon is advantageous as a plasma gas;
For powder injected at a rate of up to 5 kg/h at a pressure of 3 atmospheres.

It can also be used as a carrier gas. A spray distance of 100 to 120 mm is advantageous.

The thickness achieved in aluminum oxide at a deposition rate of 4 mm per rotation of the tension cylinder is, for example, 250 μm.

By applying several layers of coating, the desired final thickness, preferably 200-500 .mu.m, is finally reached and thus the desired thermal resistance is obtained.

For example, for aluminum oxide with a layer thickness of 300 μm, this resistance is approximately 4-10-4 m2·h·°C/Kca
It becomes l.

In order to obtain the desired surface effect, the ceramic layer is
It is then subjected to mechanical processing, for example polishing.

The additional processing of the surface influences, among other things, the solidification conditions.

After all, the method of wetting and the transfer of heat between the liquid metal and
This is because it can be changed along with the surface roughness of the coating layer.

Following the above, the coated strip mold is attached to a casting machine/machine and can be used for continuous production of strip castings.

Polyphenylsulfide, polybenzimidazole, polyvinylpyrrolidone, polyimide, silicone resins or trace amounts of at least one inorganic substance such as graphite, zirconium silicate, hexagonal boron nitride, talc, ceramically compounded aluminum. or by the attachment of a thin layer of fiber flux of carborundum, or by the injection of lubricants such as graphite, magnesium hydroxide, electrostatically attached silicon dioxide,
The sealing of the numerous pores in the ceramic layer shown in FIG. 2 prevents the entrapment of moisture and thus the generation of vapors upon contact with liquid metal.

At the same time, the degree of wetting of the coating by the solidifying metal changes, resulting in a smooth and clean surface of the strip casting.

The relationship between the porosity of the coating layer, the moisture in the air, the sealant, and the wetting or surface quality of the strip casting has not yet been completely clarified.

However, as a result of experiments, it has been confirmed that the use of a sealant prevents the occurrence of elution scratches and improves the surface of the band-shaped casting.

The above-mentioned sealing material adheres very well to the pores of the ceramic coating layer and, even after partial burn-out, as occurs with resins, it does not cause any quality-degrading fractures on the casting strip. will not occur.

With the exception of the fiber flux layer, the thickness of the sealing layer should not exceed the average roughening depth of the ceramic layer.

The depth of the roughening is estimated to be 1 to 20 μm.

In no case should the sealing layer have a closed surface covering the surface of the ceramic covering layer. 1 to 10, in contrast to a conventional chemically bonded coating layer according to number 11.

In this case, the following measurements were carried out, namely: 1) Thermal resistance including steel plate (10-5 m2·h.℃/Kc
al), 2) Mechanical and thermal resistance of the adhesion force under operating load, in this case the symbols M and T represent the following values:

M: Ceramic material, T: Separation layer, 3) Fractures, GB = Harmful fractures observed on aluminum strip castings, TA = Comparative weight loss (g) measurements using a Taber scraper according to ASTM C501-66.

(Standard test method for the resistivity to abrasion of matte ceramic tiles with a Taber scraper) With the strip mold according to the invention it is now possible to operate casting machines continuously for many days in an advantageous manner. It became possible to do so.

This is because there is no longer a need to replace the strip mold during casting.

On the one hand, this saves operating costs and, on the other hand, ensures the production of uniformly high-quality strip castings.

[Brief explanation of drawings]

1 is a side view of a continuous casting machine with a running strip mold provided with the coating layer of the present invention; FIG. 2 is an enlarged view of the coated steel mold; and FIG. 1 is a side view of an apparatus for coating a mold; FIG. In the figure, 1... molten metal, 2... strip mold, 3...
Support and direction conversion roller, 5... Cooling water hole, 6... Molten metal feeding pipe, 8... Sealing layer, 9... Tension cylinder, 10... Plasma injection device, 11... Surface roughening device.

Claims (1)

[Scope of Claims] 1. A strip mold for a continuously operating casting machine, which has a coating layer of particles of ceramic material on the surface of the strip mold facing the melt, in which said particles are at least partially Strip molds for continuously operating casting machines, characterized in that they are fused to the surface of the strip and are interconnected by sintering and/or welding. 2. The band-shaped mold according to claim 1, characterized in that a sealing layer is attached on the coating layer.