DE2650916A1 - Covering metal melts with mineral fibre hoods - contg. a transversely oriented mineral fibre core coated with reinforced refractory mortar layers - Google Patents

Abstract

Mineral fibre hood for covering metal melts, to prevent rapid cooling, comprises an insulating mineral fibre layer which is arranged so that fibre direction runs transversely to hood surface. The hood is covered, on top and bottom, with a thin refractory mortar layer, which is reinforced by heat-stable mineral fibres. The high insulating activity of mineral wool layer is retained, and the soft mineral wool is protected by an impact-resistant, thin, strong surface. Frequent temp. changes do not affect heat-stability of hood, and the reinforcement of mortar layers allows a redn. in thickness.

Description

Cover hood for covering molten metal

To prevent rapid cooling of molten metal have been mostly so-called covering compounds are used. These were made on dle Gffle pans, slab molds etc. poured. The covering compound was heated to such an extent that it became a liquid Melt formed on the liquid metal, which largely prevented oxidation.

The unmelted layer of the covering compound on top prevented it the too rapid solidification of the molten metal, so that residual air bubbles (voids) could escape.

The disadvantage of this technique is that the covering compounds only Can be used once and there: 3 The melted, solidified covering layer after stripping, the shaped bodies are removed as slag with more or less effort must become. Furthermore, there are costs for the removal of the remaining covering compound at.

It has therefore been suggested that hoods made of mineral fibers to press that can be reused many times.

However, some skins had the disadvantage that the fibers were more open are less exposed, so that.3 they are easily exposed to mechanical and thermal effects could be destroyed. Furthermore, the manufacturing process requires the addition of a binder to the fiber and a certain compression, which makes the insulation value of the original present fiber material drops many times over.

Therefore, the present invention has set itself the task of such To make hoods much more resistant and durable than previously known and to make full use of the Isoller value of the fiber layer.

Mineral fiber made from minerals is used as an insulating layer which must correspond to the respective temperature.

It is also known to use sandwich components with a mineral fiber core, in which the fiber direction is set transversely to the surface, a very favorable one Behave in relation to compressive and tensile stress. To now this thought To be able to make use of the high-temperature-resistant insulating hood is according to the invention the insulating layer is composed of mineral fiber strips placed in a specific Width of a standard mineral fiber board or mat with parallel to Surface running in the direction of the grain are separated. These strips become like this arranged that the cut surfaces form the new surface of the insulating layer. The fiber direction is thus arranged transversely to the surface.

Such a fiber arrangement is referred to as fiber lamellae. The at Separating the set width of the strips thus results in the desired thickness of the Insulating layer.

However, the strips are not connected to one another in this arrangement. This is now produced according to the invention in that on the top and bottom a thin layer of refractory mortar is applied to the insulating layer, the Mineral fibers have been added as reinforcement. Such fiber-reinforced mortars have considerable tensile and flexural strengths even in very small thicknesses.

The mineral fibers used for reinforcement must be in their composition correspond to the expected temperature stress.

The sensitive insulating layer is created in this way according to the invention reliably protected against mechanical and direct thermal stress. In addition, such layers can be shaped as desired, so that cover hoods produced according to the system according to the invention in any shape and size can be.

The structure of such a cover is exemplified by the attached Sketches explained.

Fig. 1 shows the hood over a casting mold. Fig. 2 shows a cross section by Fig. 1 Here means (1) the insulating fiber lamellar core in which the Grain direction is set transversely to the surface; (2) is the surface coating on the inside, (3) the surface coating is on the outside, zen side; (4) are threaded sleeves with fastening and force insertion elements, such as those used for example in the manufacture of plastic components are known to the hood of movement devices to be able to attach; (5) means the molten metal '(6) represents schematically the mold.

Fig. 3 shows one of the many possibilities for producing a cover hood.

3a on the teaching form (7) is as the inside of the surface (2) with Mineral fibers mixed mortar applied.

3b Strip sections are placed on this still fresh layer of mortar (2) (6) from the mineral wool plate (9) placed close together, so that the insulating layer (1) is formed seamlessly, with the cut edges of the strips (8) in the fresh Mortar layer (2) are pressed; The width of the strip (s) corresponds to the desired one Thickness of the insulating layer (1).

3c The outer coating is placed on the insulating layer (1) thus created (3) Applied from refractory mortar, the mortar layer being expedient (3) is not quite brought up to the coating of the inner surface (2), so that a surrounding mortar-free strip is left on the edge of the hood.

At the same time, threaded sleeves can be worked into the outer layer (3) as shown in FIG.

The mortar of the outer surface (3) can have a lower temperature resistance have than the mortar of the inner surface (2).

The composition of the mortar of the surface coating can be very to be different. On the one hand, hydraulically setting mortar can be mixed with high-alumina cement can be used as a binder, a mortar made from phosphate binder is also suitable. Furthermore, the fiber-reinforced protective coating can also be used as a ceramic-setting compound be produced, with a solidification of the material by sintering at medium Temperatures can take place that are considerably below the subsequent exposure temperature lie.

It can also take into account the very rapid heating of the interior The surface of the hood is required when slipping it over the hot molten metal be to capillary the mortar of the protective layer to relieve vapor stress to avoid that would destroy a dense surface. Therefore you can use hydraulic setting mortar certain amounts of substances that swell strongly in water, such as methyl cellulose or add pore-forming substances. If applicable, there are also substances that leave pores after drying or heating, in phosphate binders and ceramic Mix in layers to set.

Furthermore, between the temperature-stressed inner layer and the exposed to room temperature, i.e. a relatively cold outer layer, the connection to interrupt in order to avoid unnecessary stresses due to the different thermal expansion to let occur.

Such differences in length change are due to the same pendulum supports acting fiber lamellas balanced without tension, without the cohesion between The outer and inner layers are affected.

The leaps and bounds of technical progress made with an inventive Cover hood is achieved, is based on the fact that - the high insulating effect of the mineral wool layer is retained because it is not interspersed with binding agent - the soft mineral wool due to a thin but very solid surface with stoXfesw «", viscoplastic behavior: largely protected against mechanical and direct thermal stress will, - A tensile strength due to the direction of the fibers across the surface Connection between the inner and outer surface is created, which makes one unusually stiff Body results, while on the other hand the fiber in the arrangement according to the invention like a pendulum support in the case of very large temperature differences between interior and the outer layer can yield without tension, so that temperature changes occur more frequently has no influence on the durability of the hood, - due to the fiber reinforcement of the Surface layers only a small layer thickness is required, so that the Total weight of the cover can be kept extremely low.

Claims (7)

PATENTANSPFLÜCHE 1. Mineral fiber cover to cover Metal melts to prevent rapid cooling, characterized in that the insulating mineral fiber layer is arranged in such a way that the fiber direction is transverse to the Surface of the hood runs and that the hood on the top and bottom is coated with a temperature-resistant mortar, which is replaced by temperature-resistant Mineral fiber is reinforced. 2. Cover hood according to claim 1, characterized in that the used Fiber type is selected according to the respective temperature stress. 3. Cover according to claim 1 and 2, characterized in that between the mortar layer on the upper side and the mortar layer on the underside are encircling Space is left to compensate for temperature-related differences in length. 4. Cover hood according to claim 1 to 3, characterized in that the Mortar of the covering surface layers using high-alumina cement is made with the addition of mineral fiber. 5. Cover hood according to claim 1 to 3, characterized in that the Mortar the covering surface layers using phosphate binders with Addition of mineral fiber is made. 6. Cover hood according to claim 1 to 3, characterized in that the Mortar of the covering surface layers made of ceramic-setting material Addition of mineral fiber is made. 7. Cover according to claim 1 to 6, characterized in that the Substances are added to the mortar of the covering surface layers, which after the Drying out or heating leaves capillary pores. ß. Covering hood according to Claims 1 to 7, characterized in that an Threaded sleeves are incorporated into the hood as attachment points.