JPH02229663A - Stoke - Google Patents

Abstract

PURPOSE:To improve pressure-proof property by constituting inside layer of burnt refractory of SiC material and/or Si3N4 material, internal layer of iron (alloy) and outside layer of ceramic fiber insulating material and protecting the surface of the outside layer with monolithic refractory material of SiC and/or Si3N4 material. CONSTITUTION:The inside layer 1 of a stoke is constituted of the burnt material containing SiC and/or Si3N4 material as essential component. This has little reactivity with molten metal 9 of Al (alloy) and resist the large flowing speed. At least the part open from the molten metal 9 in the internal layer 2 of the stoke is constituted of the high m. p. metal tube of stainless steel, ordinary steel, etc., to prevent leakage of pressure at the time of pressurizing. The outside layer of the stoke is constituted of the ceramic fiber insulating material 3 and the protecting layer is formed of the monolithic material containing SiC and/or Si3N4 material as essential component on the surface 7 thereof. Even if the pressurizing force is high, such as about 1.5kg/cm<2>, this is fit for use.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a casting stalk used in a low-pressure casting machine for molten aluminum or a light alloy mainly composed of aluminum.

(Prior Art) A low-pressure casting machine casts molten metal in a lower part of the mold by pressurizing the molten metal surface into a mold installed in the upper part.

The stalk is used as a runner for feeding the molten metal during this time. The stalk materials used here are generally cast iron pipes, titanium alloy pipes, or pipes whose inner and outer surfaces are coated with an inorganic material such as graphite as a surface protective film, or silicon carbide and/or nitride. A silicone refractory is used.

(Problem to be solved by the invention) However, the former has a high degree of chemical reaction with the molten metal, and the reaction products are mixed into the molten metal as impurities, leading to a decrease in quality, causing problems in terms of properties, and shortening the service life. It is short and requires frequent replacement work, which has a negative impact on productivity. In addition, the latter porous refractories mainly composed of silicon carbide and/or silicon nitride are significantly improved in terms of durability and the presence of impurities in the molten metal, but because they are porous, they have high air permeability and air infiltration during casting. This causes pressure leakage and bubbles inside the product, which poses major problems both in terms of operation and product quality. Recently, a stalk has been proposed that improves air permeability by creating a void in the core of the stalk and inserting a low-melting point metal into the void, but if a crack develops on the inside or outside of the stalk, the low-melting point metal inside is There is a strong desire for a stalk that improves these points, as it easily leaks out, and it can leak out by penetrating into minute cracks in the ceramic material, contaminating the molten metal that performs the stalk's function. is the current situation.

Currently, porous refractories (ceramics) are used.The reason for this is that during operation, the lower part is immersed in the molten metal, the upper part is in contact with the outside air, the furnace lid, and the mold, and is cooled from this contact area, and the inside is immersed in the molten metal. Because of the passage of the stalk, there is a large temperature difference in each part of the stalk itself, and there is a very high risk of cracking and cracking. Therefore, due to the characteristics of the stalk, it is required that there be absolutely no cracking or cracking. As mentioned above, this causes operational problems due to pressure leakage, air entrainment, and the occurrence of pinholes in 11 products. (Means for solving the problems) The present invention has been made to improve these problems, and
The inner layer is made of a fired refractory material mainly composed of SiC material and/or Si3N, the inner layer is made of iron and its alloy at least in the part exposed from the molten metal, and the outer layer is made of a heat insulating material mainly made of ceramic fiber material. The surface of the heat insulating material mainly made of ceramic fiber material is protected with an amorphous refractory material mainly made of SiC and/or Si3N4 material to form a multilayer structure.

That is, the stalk of this invention has the following multilayer structure.

■ The inner layer of the stalk is a sintered material mainly composed of Si3N and/or SiC material. (
It has low reactivity with molten metal, can withstand flow rates, and minimizes contamination. ) ■ Internal (core) layer of the stalk High-melting point metal tube such as stainless steel or steel [Pressure leakage during pressurization (prevents air permeation)] ■ Outer layer of the stalk ■ Ceramic fiber blanket, paper-like material If necessary, use adhesive to wrap it up to a predetermined thickness.

◎ A molded body made of ceramic fibers is attached through mortar.

Each of the outer layer materials using ceramic fibers such as ■ and ◎ is constructed, and a protective layer is formed on the outer layer using an irregularly shaped material (coating material) mainly made of SiC and/or Si3N4 material to form a stalk.

Incidentally, if a thermal expansion coefficient adjusting material is required between (1) and (2) above, a noncombustible material, ceramic fiber, etc. can also be used.

In this way, by composing the inner layer, inner layer, and outer layer with materials that maintain the needs for use, the original performance of the stalk can be sufficiently maintained, resulting in long life and extremely safe operation. It provides a stalk that can solve various problems. (Note that the stainless steel and heat-resistant steel used inside the device should be installed at least in areas where the molten metal is exposed during use.) [Example] Next, the drawings will be explained using examples.

Table 1 Table 2 Table 4 The materials shown in Tables 1 to 3 above are combined as shown in Table 4.

In the figure, 4 is a setting mortar, 5 is a ceramic fiber molded body, 6 is a ceramic fiber bracket, 7 is a ceramic coating material, 8 is a flange, and 9 is a molten metal surface.

For the pressure leak test, keep the top and bottom ends airtight, fill them with water, and apply a vacuum using a vacuum pump. At this time, the value at which air bubbles are generated in the water is defined as the pressure leakage value. In this test result, the part of the product of the present invention in which the stainless steel material is internally formed is under vacuum (760 m/Hg), but no bubbles are generated, while the comparative product is 230 m/Hg and bubbles are generated. It was confirmed that the passage of air from the outside was observed and that it produced a great effect.

(Effect of the invention) Casting test results Based on the above results, the products of the present invention and comparative products of Examples ① and ② were actually used in an aluminum low-pressure casting machine. The results of { are shown in Table 5 below. (Indicated by the yield rate of the presence or absence of bubble generation) The drawings show an embodiment of the stalk of this invention.
Q9 in the figure is a vertical sectional view of a comparative product, and FIG. 2 is an explanatory diagram of a construction example of this invention.

1...Inner layer, 2...Inner layer, 3...Outer layer, 4
... Mortar for setting, 5... Ceramic fiber molded body, 6... Ceramic fiber blanket, 7...
・Ceramics coating material, 8...Flange, 9
...Mold surface, Patent applicant: Tokyo Ceramics Co., Ltd. As shown in the above results, when the pressurizing pressure becomes high, it becomes impossible to cast with current materials (good products cannot be obtained), but the product of the present invention can improve the internal stainless steel pipe. All of them were able to withstand sufficient use without any abnormalities, and were able to cast products without bubbles, and were able to fully achieve their effects.

[Brief explanation of the drawing]

(stomach) C threat-Jt”) No. figure (mouth (Example λ冫 (c) (Hiho Town No. figure /． ．． inner layer Ko. ．． inner layer 3. ．． outer layer

Claims (1)

[Claims] In the stalk used for pressure casting of aluminum and molten metal mainly composed of aluminum, the inner layer is made of SiC.
It is a fired refractory material mainly made of Si_3N_4 material, the inner layer is made of iron and its alloy at least in the part exposed from the molten metal, and the outer layer is made of a heat insulating material mainly made of ceramic fiber material. 1. A stalk for low-pressure casting, characterized in that it has a multilayer structure in which the surface of a heat insulating material mainly composed of is protected by a monolithic refractory material mainly composed of SiC and/or Si_3N_4 material.