JPH0237952A - Molten metal injection equipment for centrifugal casting molds - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention is aimed at preventing non-metallic inclusions such as slag from being mixed in the molten metal when the molten metal in a ladle is injected into a centrifugal casting mold via a molten metal injection device. Cast into the mold together with molten metal,
The present invention relates to a molten metal injection device for centrifugal casting molds that can effectively avoid minute defects inherent in cast products that adversely affect quality.

BACKGROUND OF THE INVENTION Centrifugal casting is widely used as a means of casting dense castings with few casting defects such as cavities and blowholes. In this centrifugal casting method, a centrifugal casting mold placed horizontally or vertically is rotated at high speed, and molten metal is poured into the mold through a pouring spout. This is a method for manufacturing hollow cast products such as pipes, tubes, and ball valves by closely adhering them in layers and then cooling and solidifying them.

Note that a molten metal injection device generally called a boring cup is used to inject the molten metal into the centrifugal casting mold. In this case, the molten metal (molten metal) 10 is placed in a ladle 1 as shown in FIG.
After being injected into the mold 14, the molten metal is transported to a foundry where a centrifugal casting mold 14 is installed, where it is poured into the pouring port 18 of the mold 14 via a molten metal injection device 16. The molten metal injection bag W16 is composed of a cup body 20 that directly receives the molten metal 10, and a molten metal injection pipe 22 that pours the molten metal 10 from the body 20 into the pouring port 18 of the mold 14.

Problems to be Solved by the Invention The above-described centrifugal casting method is excellent in that hollow cast products with a dense structure can be easily cast. However, the molten metal poured into the centrifugal casting mold tends to contain a small amount of non-metallic inclusions such as slag floating therein, so if these non-metallic inclusions are poured into the mold together with the molten metal, micro defects inherent in the cast product may occur. This is known to have an unfavorable effect on product quality.

However, even if the non-metallic inclusions are cast into a centrifugal casting mold together with the molten metal, since the mold is rotated at high speed, the light-weight non-metallic inclusions are mainly deposited inside the hollow cast product. It will be unevenly distributed. Moreover, in many cases
Since the inside and outside of the cast product are removed by cutting as post-processing, it is relatively unlikely that a large amount of the non-metallic inclusions will be incorporated into the metal structure of the cast product. .

However, all of the nonmetallic inclusions are concentrated and unevenly distributed inside the cast product, and it is not possible to remove them almost completely by cutting, and they often remain inside the cast product as minute defects. It is possible. The remaining of such minute defects becomes a major problem when the cast product is required to have a high degree of reliability and durability.
Confirmation of internal quality through radiological inspection is mandatory.

Conventional methods are not sufficient to deal with this.

Furthermore, when the molten metal is injected into a centrifugal casting mold using the molten metal injection device, the molten metal often scatters and dances inside the mold due to the head difference. At this time, the molten metal comes into contact with oxygen in the atmosphere to promote oxidation, producing oxidation products as the nonmetallic inclusions, which have also been found to be a cause of microdefects.

Purpose of the Invention The present invention has been proposed in view of the above-mentioned problems, and is aimed at reducing the amount of non-metallic inclusions mixed in the molten metal when the molten metal is injected from a ladle into a centrifugal casting mold using a molten metal injection device. An object of the present invention is to provide a molten metal injection device that can effectively avoid unfavorable effects on strength and other quality deterioration of cast products by preventing as much as possible from injecting materials into a centrifugal casting mold together with molten metal. Another object of the present invention is to prevent the molten metal from coming into contact with the atmosphere as much as possible when pouring the molten metal from a ladle into a mold, thereby suppressing the occurrence of product defects due to atmospheric oxidation.

Means for solving the problemsTo overcome the above problems and suitably achieve the intended purpose1
As a result of various studies, the inventor of the present application focused on the fact that non-metallic inclusions such as slag are extremely light compared to the molten metal, so they float on the surface of the molten metal, and the molten metal poured from the ladle was A predetermined amount is stored in the cup body of the molten metal injection device, and the nonmetallic inclusions are suspended on the surface layer of the molten metal, and the molten metal is poured only from the lower part of the molten metal where nonmetallic inclusions are not present through the injection pipe. It was found that casting of molten metal free of non-metallic inclusions could be achieved by drawing it out and injecting it through the spout of the centrifugal casting mold. That is, the present invention
In a molten metal injection device consisting of a cup body that directly receives molten metal poured from a ladle and a molten metal injection pipe that pours the molten metal in the cup body into the spout of a centrifugal casting mold, the molten metal injection pipe is arranged in an inverted U shape. The injection tube is bent so that one open end faces downward near the bottom of the cup body, and the main body of the injection tube is led out of the cup body, and the other open end It is characterized in that it is configured to face the spout of the centrifugal casting mold.

Embodiment Next, a preferred embodiment of the centrifugal casting mold molten metal injection device according to the present invention will be described below with reference to the accompanying drawings. Note that the same members as those described in connection with FIG. 5 are indicated by the same reference numerals. The molten metal injection device 16 schematically shown as a preferred embodiment in FIG. 1 basically consists of the cup body 2o and the molten metal injection pipe 22, as described above. However, the molten metal injection pipe 22 that is connected to the cup body 20 is bent into an inverted U shape at one body portion 22a, and one open end 22b thereof is directed downward, so that the molten metal injection pipe 22 is connected to the cup body 20 near the bottom. I am making it happen. Further, the main body part 22a of the molten metal injection pipe 22 is led out of the cup main body 20 and extends downward, and the other open end part 22a is led out of the cup main body 20 and extends downward.
2c is configured to face the spout 18 of the centrifugal casting mold 14 arranged vertically.

Note that it is preferable that a heat-resistant filter 24, for example, a ceramic filter, be disposed at one open end 22b of the molten metal injection pipe 22 facing into the cup body 20 to filter out non-metallic inclusions mixed in the molten metal. .

FIG. 2 is a longitudinal sectional view showing a state in which the molten metal injection device according to the embodiment is used to pour molten metal into a horizontal centrifugal casting mold whose rotation center extends horizontally. In this case, the cup body 2
The other open end 22c of the molten metal injection pipe 22 drawn outward from the mold 14 faces the pouring port 18 of the mold 14.

According to the above-described configuration, as will be explained later, the molten metal 10 can be poured into the centrifugal casting mold 14 with almost no non-metallic inclusions such as slag mixed in the molten metal 10. However, in the configuration shown in FIG.
2c and the inner bottom 14a of the centrifugal casting mold 14, there is a considerable head difference. Therefore, the molten metal 10 discharged from the injection pipe 22 to the pouring port 18 of the mold 14 comes into contact with the atmosphere while being discharged and falls, and
It scatters and dances at a, producing oxidation products as described above and causing micro defects.

Therefore, as shown in FIG. 3, the length of the main body part 22a where the molten metal injection pipe 22 extends outward from the cup main body 20 is set to be sufficiently large, and the open end 22c is connected to the vertical centrifugal casting mold 14. It is proposed that the vicinity of the inner bottom 14a be exposed through the pouring spout 18 of the molten metal. According to this, the opportunity for the molten metal 10 discharged through the injection pipe 22 to come into contact with the atmosphere can be minimized, and the generation of micro defects due to oxidation products is prevented.

Further, in the molten metal injection pipe 22 in which the length of the main body portion 22a is set to be sufficiently large, as shown in FIG.
If the tube end 22c is bent radially outward and configured to follow the vicinity of the inner bottom 14a of the centrifugal casting mold 14, the molten metal 1 is discharged from the injection tube 22 into the mold 14.
0 diffuses while being guided radially outward at the inner bottom 14a of the mold 14, thereby avoiding the disadvantageous phenomenon of accelerated oxidation due to scattering at the inner bottom 14a of the mold.

Furthermore, as in the configuration shown in FIG. 3 or FIG. 4, with the pipe end 22c of the molten metal injection pipe 22 facing the spout 18 of the centrifugal casting mold 14, argon is added to the inside of the mold 14. It is preferable to pour the molten metal 10 under a condition in which the mold is filled with an inert gas such as the like, and air is expelled from the inside of the mold.

Function of the Embodiment Next, the function of the molten metal injection device for the centrifugal casting mold according to the present embodiment will be explained. As shown in FIG. 1, after the open end 22c of the injection pipe 22 led out of the molten metal injection device 16 is vertically faced to the pouring port 18 of the vertically arranged centrifugal casting mold 14, the molten metal 10 is poured. The ladle 12 that has been poured into the cup body 20
Tilt it above. As a result, the molten metal 10 is poured into the cup body 2o of the molten metal injection device 16, and the liquid level gradually rises. The molten metal 10 also enters one open end 22b of the molten metal injection pipe 22 facing near the bottom of the cup body 20, and the liquid level rises to a level L at the inverted U-shaped bent part of the injection pipe 22. When it reaches this point, the injection tube body 22
a flows down and is poured into the centrifugal casting mold 14 through the pouring spout 18.

In this case, the main body part 22a of the molten metal injection pipe 22 is bent into an inverted U shape and led out from the cup main body 20, so that one open end 22b facing the vicinity of the bottom of the cup main body 20 The molten metal in the cup body 20 continues to flow out from the pipe body 22 as long as the level b of the other open end 22c facing the pouring port 18 of the mold 14 is located below the level L of the mold 14. Further, since the injection of the molten metal 10 from the ladle 12 into the cup body 2o continues, the level of the molten metal 10 in the cup body 20 continues to rise to near the limit, and the molten metal 10
Non-metallic inclusions such as slag float in a separated layer near the top.

However, the molten metal 10 is pumped out only from the open end 22b of the molten metal injection pipe 22 located at the lower layer where the non-metallic inclusions are not mixed, that is, level B near the bottom of the cup body 20. Therefore, centrifugal casting mold 1
The molten metal 10 injected into the molten metal 4 contains almost no nonmetallic inclusions such as slag, and the resulting cast product is prevented from having minute defects caused by the nonmetallic inclusions. Although there are some nonmetallic inclusions in the first part of the molten metal 10 that rises in the cup body 20 and enters the open end 22b of the injection tube 22, as described above, the open end 2
If, for example, a ceramic filter 24 with high heat resistance is disposed in the filter 2b, the non-metallic inclusions associated with the initial contamination can be removed by filtration, which is preferable. Further, when the hot water supply from the ladle 12 is cut off and the liquid level of the molten metal 1o in the cup body 20 drops to the illustrated level L, the outflow is stopped.

As shown in FIG. 2, the molten metal injection device 16 according to this embodiment can be applied to injection of molten metal into the horizontal centrifugal casting mold 14 by only slightly changing the shape of the main body of the molten metal injection pipe 22. . According to the molten metal injection apparatus shown in FIGS. 1 and 2, the molten metal 10 injected into the centrifugal casting mold 14 is
However, if the structure shown in FIGS. 3 and 4 is adopted in addition to this configuration, the molten metal 10 will come into contact with the atmosphere and oxidation products will be generated. It is also possible to effectively prevent the phenomenon that causes .

Effects of the Invention As explained above, according to the molten metal injection device for a centrifugal casting mold according to the present invention, when molten metal in a ladle is injected into a centrifugal casting mold via the molten metal injection device, there is a primary injection into the cup body. Of the molten metal stored in the molten metal, it is pumped out only from the lower layer where non-metallic inclusions such as slag are hardly mixed due to the difference in specific gravity. No defects will occur. Therefore, there is a beneficial advantage in that undesirable effects on the strength and quality of the casting can be effectively avoided.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing the schematic configuration of a molten metal injection device according to a preferred embodiment of the present invention in a used state, and FIG. 2 is a horizontal centrifugal casting using the molten metal injection device according to the embodiment. FIGS. 3 and 4 are vertical cross-sectional views showing a state in which metal is being poured into a mold. When pouring molten metal into a centrifugal casting mold from a molten metal injection device according to an embodiment, contact with the atmosphere is minimized. Fig. 5 is a longitudinal cross-sectional view showing a structure that can prevent the occurrence of micro defects due to oxidation. FIG. 10... Molten metal 12... Ladle 14... Centrifugal casting mold 16... Molten metal injection device 18... Pouring port 22... Molten metal injection pipe 22a.
...Body portions 22b, 22c...Open end portion 24...Heat-resistant filter

Claims (1)

[Scope of Claims] [1] A molten metal pouring device comprising a cup body that directly receives molten metal poured from a ladle, and a molten metal injection pipe that pours the molten metal in the cup body into a spout of a centrifugal casting mold, comprising: The molten metal injection pipe is bent into an inverted U-shape so that one open end faces downward near the bottom of the cup body, and the main body of the injection pipe is directed outward from the cup body. A molten metal injection device characterized in that the molten metal is drawn out and the other open end faces the pouring spout of the centrifugal casting mold. [2] A claim in which a filter made of a highly heat-resistant material is provided at one open end of the molten metal injection pipe facing into the cup body, thereby making it possible to filter out nonmetallic inclusions mixed in the molten metal. Item 2. A molten metal injection device for the centrifugal casting mold according to item 1. [3] A claim in which the length of the main body of the molten metal injection pipe extending outside the cup body is set sufficiently large, and the open end thereof is exposed to the vicinity of the bottom of the mold through the pouring spout of the centrifugal casting mold. Item 3. A molten metal injection device for a centrifugal casting mold according to item 1 or 2. [4] The centrifugal tube according to claim 1 or 3, wherein the molten metal injection tube has a sufficiently large length in the main body, and the tube end is bent radially outward near the bottom of the centrifugal casting mold. Molten metal injection device in casting mold. [5] After the pipe end of the molten metal injection pipe faces the spout of the centrifugal casting mold, the centrifugal casting mold is filled with an inert gas, and the molten metal is poured under the filled state of the inert gas. The apparatus for injecting molten metal into a centrifugal casting mold according to claim 1.