JPH0577022A - Ceramic stoke for low pressure casting - Google Patents

Abstract

PURPOSE:To restrain the sticking and the deposition of metals at the upper part in a hole of a stoke by making at least the exposed part from molten metal two layers of an inside layer and an outside layer, arranging gap part between two layers to make multi-layer structure and reducing heat radiation from the stoke itself. CONSTITUTION:In the ceramic stoke used at the time of executing the pressurize-casting to the molten aluminum or aluminum alloy, this is constituted with the two layer structure having the inside wall 2 and the outside wall 3. Further, this has the peculiarity of the multi-layer structure arranging the gap part 1 at between the two layers. By forming the structure providing the gap part at between the inside wall and the outside wall, the heat insulating effect is improved and the original performance is sufficiently held and the stoke for low pressure casting being solvable to various problems, such as the secureness of the long service and the safe operation, the improvement of the product quality and the yield, can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic stalk for pouring, which is used in a low-pressure casting machine for casting molten aluminum or aluminum alloy.

[0002]

2. Description of the Related Art A low pressure casting machine casts a molten metal surface in a molten metal container such as a lower crucible into a mold installed in an upper portion to cast the molten metal. The stalk is used as a pipe for connecting the molten metal of the molten metal container to the upper mold, that is, as a molten metal pouring runner. What is used as this stalk material is generally cast iron material, titanium, alloy material or graphite material on the inner and / or outer surface of these materials,
There is used a stalk made of a gold layer provided as a protective film on the outer surface with an inorganic coating material such as an oxide, or a ceramic material produced from a silicon carbide based material or a silicon nitride based material as a main raw material.

[0003]

However, the former has a high chemical reactivity with the molten metal, and the reaction product (melting substance) is mixed into the molten metal as an impurity, resulting in deterioration of quality and a problem in quality. It has a short service life and requires frequent replacement work, which adversely affects work efficiency. In the latter case, the ceramic material mainly composed of silicon carbide and / or silicon nitride has a great improvement effect in mixing impurities into the molten metal due to the stalk material and in terms of serviceability. In the upper part of the inner side, which is the runner, the adhesion phenomenon of metal is observed, and when the molten metal is transferred (casting), a turbulent flow is generated, or the deposited material is peeled off and mixed in the molten metal at the time of casting. It causes problems such as being mixed in.

The present invention is intended to solve the above-mentioned problems. As a result of various investigations and studies on the cause of this adhesion, as a result of pressurizing the molten metal surface in the molten metal container, the molten metal in the stalk is removed every time casting is performed. Enters, exits, fills, or empties the top of the stalk. During this time, the stalk itself dissipates heat, and the temperature of the stalk itself drops. In such a state of stalk, solidification and adhesion gradually overlaps due to repeated molten metal discharge (discharge) each time casting occurs, and a large amount of adhered material As a result, as described above, the molten metal flow is disturbed during casting, and the deposited deposits fall off and intervene in the product, resulting in a reduction in work surface and quality and a reduction in yield. Therefore, there is a strong demand for improving this phenomenon.

[0005]

As a result of various studies in order to improve these problems in view of the current situation, at least the portion exposed from the molten metal is divided into the inner wall layer and the outer wall layer in the stalk thickness direction. Layers, and by providing voids between these layers, providing multiple layers and voids enhances the heat insulating effect of the stalk itself, reduces the heat radiation transferred from the inner wall, and lowers the heat of the stalk material when the molten metal flows in and out. It is to prevent solidification and adhesion by preventing

The main purpose of the multi-layer structure of the present invention is to suppress the deposition of metal on the upper part of the stalk hole by suppressing the heat radiation from the stalk itself. Therefore, different materials may be used if they do not cause defects such as cracks due to the difference in thermal expansion coefficient at the joint between the inner wall material and outer wall material of the stalk, or they may be composed of the same material, It may be integrally formed at the time of manufacturing, or may be manufactured after the inner and outer layer materials are individually manufactured and then joined. Either method may be used for manufacturing, but it is to have a multi-layer structure in which voids are provided therein.

Further, the multi-layered structural portion configured to enhance the heat insulating property is provided at least in a portion exposed from the molten metal for its purpose and effect, but the void portion provided between the inner and outer wall layers may be in the same region all over. However, it is free to form a non-void portion such as providing a support portion for reinforcement of the inner wall member or for certainty for forming the inner and outer wall members as long as the effect of the present invention is not significantly impaired. It is only necessary to prevent the effect of preventing gold deposition.

In the present invention, the reason that the portion having a multi-layer structure, such as having a void portion, is provided at least in the exposed portion from the molten metal is to enhance the heat insulating effect and ensure the effect of the present invention. is there.

As described above, by providing the inner wall and the outer wall with the space between them, the original performance can be sufficiently maintained, the long life and safe operation can be performed, and the quality of the product, the yield, etc. can be improved. It is possible to provide a low pressure casting stalk capable of solving various problems such as measuring

Next, examples will be shown.

[0011]

[Table 1]

The stalk material used in the examples is shown below.
(Table -1) A material the SiC-Si ₃ N ₄ -Si material as a raw material in Table 1
The composition is adjusted at the ratio shown in (1) and molded by the slip casting method, and reactive sintering is performed in a nitrogen gas atmosphere to produce the product. This material was used as both the outer wall material and the inner wall material in the examples of the present invention. Material B is produced by using Sie-Si ₃ N ₄ —Y ₂ O ₃ material as a raw material, adjusting the compounding ratio in the ratio shown in Table 1, degreasing with a rubber press (CIP), and sintering in a nitrogen gas atmosphere. . This material is used as the inner wall material in the examples of the present invention.

[0013]

[Example] Inner diameter φ60 Outer diameter φ110 Length 1000 m When using a stalk with an upper flange of 30 mm x 30 mm, the molten metal immersion part is always 50 from the bottom of the stalk.
It is used in a state of being immersed for 0 mm. A use example is shown as a stalk for a low pressure casting machine. The void is formed 20 mm below the top of the stalk and 80 mm below the stalk. Next, the aspect of an Example is shown.

[0014]

[Table 2]

[0015]

[Table 3]

Results of use and practice
Used by mounting on a low pressure casting machine. Casting material Aluminum with 99% Al content Casting pressure 0.6 Kg / cm²20.03 Kg / c
m²  Molten metal temperature during casting 730 ° C ± 5 ° C

[Table 3] In a practical situation (8 hours a day operation), a comparative example and an actual operation are replaced for 320 hours and 40 days, but the product of the present invention operates for 150 days and 1200 hours.
It is as small as ~ 0.2mm and can be reused until the maintenance period.

In FIGS. 1 to 4, 1 is a void portion, 2
Is an inner wall, 3 is an outer wall, 4 is an adhesive, and 5 is a molten metal surface.

[0018]

EFFECTS OF THE INVENTION As shown in the above examples, the comparative product was operated for 8 hours a day, and adhesion was observed even after use for 2 days.
The amount of adhered deposits is 6.8 to 9.4 with a time difference of 320 hours for 0 days.
mm, 5.6 to 6.2 mm, which means that there is no choice but to replace it.
It is as small as 0.3 mm and is used further for about 6 months (1
Even after 50 hours 1200 hours), there is almost no difference in the amount of adhesion,
Reuse after regular maintenance. In addition, the defective rate of the cast product is 2.5% for the product of the present invention as compared with 10.8% to 9.2% for the comparative product.
It was very small (up to 2.1%), no problem was found during operation, and it was possible to achieve a great effect in terms of quality and yield.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a conventional product comparative example ceramic stalk.

FIG. 2 is an explanatory diagram of a conventional product comparative example ceramic stalk.

FIG. 3 is an explanatory view of a product example of the present invention and a ceramic stalk.

FIG. 4 is an explanatory view of a ceramic stalk according to an example of the present invention.

[Explanation of symbols]

 1 void part 2 inner side wall 3 outer side wall 4 adhesive 5 molten metal surface

Claims (1)

[Claims] A ceramic stalk used for pressure casting of molten aluminum or aluminum alloy has a two-layer structure of an inner wall and an outer wall, and has a multi-layer structure in which a void is provided between the two layers. A ceramic stalk for low pressure casting.