JP2879492B2 - Molten metal transfer pipe and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molten metal passage for a low-pressure casting machine or a die casting machine for electromagnetic hot water supply, and more particularly to a molten metal transfer pipe for transferring a molten aluminum alloy and a method of manufacturing the same.

[0002]

2. Description of the Related Art A conventional casting apparatus for casting an aluminum alloy is, for example, a die casting machine using an electromagnetic pump as shown in FIG.

[0003] A die casting machine equipped with an electromagnetic pump comprises a mold 100 and an injection sleeve 10 connected to the mold 100.
1, an injection plunger 103 for feeding the molten metal 102 fed into the injection sleeve 101 into the mold 100, an electromagnetic pump 105 for feeding the molten metal 102 from the melting furnace 104 to the injection sleeve 101, and an electromagnetic pump 105. And a molten metal transfer pipe 106 for connecting the injection sleeve 101.

[0004] A molten metal transfer pipe 1 constituting a molten metal passage.
As a material of No. 06, nitride-based or carbide-based ceramics such as silicon carbide and silicon nitride and mullite-based ceramics have been used.

[0005] As another conventional casting apparatus, there is a low-pressure casting machine as shown in FIG. This low-pressure casting machine comprises a furnace 108 in which a molten metal 107 is stored, and a molten metal transfer pipe 110 whose lower end is immersed in the molten metal 107 of the furnace 108 and whose upper end is connected to a mold 109 arranged above the furnace 108. Then, the molten metal 107 is transferred to the mold 109 through the molten metal transfer pipe 110 by the gas pressure of the inert gas introduced into the furnace 108.
Was to be supplied inside.

As a material of the molten metal transfer tube 110, graphite, silicon nitride, and mullite ceramics have been used.

[0007]

However, since the molten metal transfer pipes 106 and 110 of any of the above-mentioned casting apparatuses have low strength and are brittle, they have a problem that they are easily broken by dropping during handling.

In particular, since ceramics such as mullite contain silica (SiO ₂ ) as an impurity, they react with aluminum to form slag at the ceramics interface, narrowing a molten metal passage, resulting in poor precision in supplying molten metal. Become.
For this reason, a maintenance operation for cleaning the interior every month is forced. In addition, when the slag is removed, problems such as chipping and cracking of the ceramics may occur, so that the operation must be performed carefully.

In addition, since both ceramics and graphite are brittle in material, there is a problem that mechanical coupling is difficult. Therefore, when the transfer passage is long, a long molten metal transfer pipe 106,
110 needs to be prepared.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and it is an object of the present invention not to be broken at the time of handling, not to react with molten aluminum, and to be easily mechanically joined. An object of the present invention is to provide a molten metal transfer pipe and a method for manufacturing the same.

[0011]

In order to achieve the above object, according to the present invention, in a molten metal transfer pipe of a casting apparatus, a carbon fiber having a passage member for transferring molten metal in a woven cloth shape is provided.
A carbon fiber reinforced carbon material having pores in its structure is carbonized, and the outside of the passage member is made of heat-resistant cast iron.

Further, the surface of the carbon fiber reinforced carbon material constituting the passage member is coated with silicon carbide, and is cast with heat-resistant cast iron.

[0013] Further, the production method is characterized in that a carbon fiber filament or a carbon fiber spun yarn woven fabric is molded into an intermediate molded body having a predetermined shape with a material impregnated with a thermosetting resin, and the intermediate molded body is carbonized. And forming a passage member made of a carbon fiber reinforced carbon material, and then casting the passage member with heat-resistant cast iron to manufacture a molten metal transfer pipe.

[0014] Further, the present invention is characterized in that the carbonized molded article obtained by carbonizing the intermediate molded article is further impregnated with pitches and re-carbonized to densify the structure. Also, the heat resistance
Silicon carbide added to carbonized molded body before being cast with cast iron
It is characterized by having been coated.

Here, the term “aluminum alloy” described in the present specification is used in a sense including not only an aluminum alloy but also aluminum alone.

[0016]

In the molten metal transfer pipe of the present invention, since the outside of the passage member is made of heat-resistant cast iron, there is no destruction due to falling or the like.

Further, the carbon fiber in which the molten metal passage has a woven fabric shape is used.
Carbonized carbonaceous material with pores in its tissue
Since it is a carbon fiber reinforced carbon material , it does not react with the molten aluminum, and slug does not adhere to the inner periphery of the passage.

Since the outside is made of heat-resistant cast iron, mechanical connection such as flange connection is facilitated, and a short transfer pipe may be connected without using a long transfer pipe.

Since a high-precision carbon fiber reinforced carbon material is used for the molten metal passage and the outside thereof is made of heat-resistant cast iron, there is no occurrence of cracks, chips, etc., and there is no reaction with the molten aluminum. Can be reliably supplied.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments.

FIG. 1 schematically shows a molten metal transfer pipe according to one embodiment of the present invention, and 1 indicates the entire molten metal transfer pipe. The molten metal transfer pipe 1 is provided with a passage member 3 serving as a molten metal passage 2.
And a heat-resistant cast iron member 4 which is formed by casting the outside of the passage member 3.
It is composed of

As the material of the passage member 3 to be cast, a carbon material reinforced with carbon fibers 5 is used. In this embodiment, as shown in FIG. 2, the carbon fiber 5 is embedded in a carbon material as a carbon fiber spun yarn fabric 6. Since the surface of the carbon fiber reinforced carbon material has appropriate irregularities, the heat-resistant cast iron member 4 penetrates into the irregularities on the surface of the carbon fiber reinforced carbon material constituting the passage member 3 to form a mechanically strong bond.

Next, a method of manufacturing the molten metal transfer pipe 1 will be described.

First, a prepreg (precursor) obtained by impregnating a carbon fiber filament or a carbon fiber woven fabric with a thermosetting resin is molded into a predetermined shape following the shape of the passage member 3 to produce an intermediate molded body.

In this embodiment, a prepreg material 11 of carbon fiber reinforced carbon material, which is a woven cloth impregnated with a thermosetting resin such as phenol resin, is applied to a core 10 made of plastic to a predetermined thickness. After winding and thermosetting, the core 10 is removed to form the intermediate molded body 12 of the passage member (see FIGS. 3A and 3B).

Next, carbonization is performed in the furnace 18 at 1000 ° C. in an inert atmosphere (for example, nitrogen gas) (FIG. 3C).
reference). In this state, since the carbonized carbon material structure has many pores, a so-called densification step of impregnating the pitch 14 and re-carbonizing is performed several times to set the porosity to 5 to 30%, thereby completing the passage member 3. (See FIG. 3 (d)).

The pitch is impregnated by, for example, vacuum suction as shown in the figure. First, the outer periphery of the carbonized intermediate molded body 13 is covered with the pitch 14, and the openings at both ends of the carbonized intermediate molded body 13 are closed with the blind lid 15. Next, the air in the carbonized intermediate molded body 13 is sucked from the suction hole 17 provided in the blind lid 15 by the vacuum suction source 16, and the pitch 14 is changed by the pressure difference between the inside and the outside of the carbonized intermediate molded body 13. The pores in the peripheral wall are filled.

Next, without machining the outside of the passage member, the heat-resistant cast iron material is used as it is. Since this heat-resistant cast iron material requires strength at high temperatures, a special cast iron material containing chromium and molybdenum, for example, the composition (C;
3.5%, Si; 2.4%, Mn; 0.6%, Cr;
0.3%, Ni; 0.3%, Mo; 0.8%).

The passage member 3 to be cast is set on a sand mold 20 as shown in FIG. After the sand mold 20 is dried to completely remove the water in the passage member 3, the cast iron is poured into the cavity 22 from the runner 21.

Since the surface of the carbon fiber reinforced carbon material constituting the passage member 3 has appropriate irregularities, the heat-resistant cast iron penetrates the irregularities and forms a strong mechanical bond.

Opening these members into a predetermined shape, FIG.
Or as an aluminum molten metal transfer pipe shown in FIG.

In the molten metal transfer pipe 1 of the present invention, the molten metal passage 2 is made of a carbon material, and therefore does not react with the molten aluminum like ceramics. Also, the mechanical strength is 15 ~
Since it is as large as 20 [kgf / mm ² ], there is no occurrence of cracks, cracks, etc. Further, when used for a long time, aluminum penetrates into the pores of the carbon material, and the carbon material is less oxidatively deteriorated. In particular, when oxidation is extremely difficult, oxidation can be completely eliminated by coating with SiC (silicon carbide). This S
The iC coating can, for example, reduce the carbon component to about
The coating can be applied by converting the surface into SiC in a SiCl ₄ atmosphere maintained at a temperature of ° C. After applying the SiC coating in this way, it is cast with heat-resistant cast iron.

The pressure of the molten metal acting on these molten metal transfer pipes 1 used in the electromagnetic hot water supply die casting machine and low pressure casting machine shown in FIGS. 7 and 8 is 1 kgf / cm ² or less, and there is no problem even after 10,000 hours of use. Five times longer life than conventional members.

After using for 10000 hours, the molten metal transfer pipe 1 was cut and inspected. As shown in the micrograph of FIG. 5, the joint of heat-resistant cast iron and carbon fiber reinforced carbon material had a uniform thickness of about 1 mm. An Fe-Al alloy layer was formed.

This layer is a layer in which the Fe content is completely saturated, and this layer impedes the permeation of aluminum, resulting in such a good result.

FIG. 5 is a photomicrograph of a cross section of the structure between the passage member 3 of the molten metal transfer pipe 1 and the heat-resistant cast iron member 4 after the life test.

In this photograph, A is a region of the carbon fiber reinforced carbon material constituting the passage member 3, B is a boundary layer region between the heat-resistant cast iron and the carbon fiber reinforced carbon material, and C is a region of the heat-resistant cast iron. is there. According to the photograph, the boundary layer region B is a uniform layer of about 1 mm. As a result of the analysis, it is apparent that the boundary layer region B is a uniform Fe-Al alloy layer as shown below. became.

FIG. 6 shows the result of analyzing the alloy layer in the boundary layer region B by an X-ray microanalyzer.

This X-ray microanalyzer counts the number of pulses peculiar to each element when an X-ray beam is applied to each element. The analysis elements include iron (Fe) constituting a heat-resistant cast iron part, Aluminum (Al) which is a component of the molten metal to be injected. The vertical axis of the chart is 2500,
15000 [cps / 25mm], the horizontal axis of the chart is 100 [μm
/ 30mm].

According to this diagram, the amounts of Fe and Al are almost constant over the entire boundary layer region B. this is,
Although the molten aluminum diffuses through the carbon fiber reinforced carbon material region A of the passage member and diffuses toward the heat-resistant cast iron region C, the amount of the diffusion is completely saturated, meaning that diffusion does not proceed any more. It can be seen that the erosion of the heat-resistant cast iron by the molten aluminum was completely prevented.

Table 1 shows the results of quantitative analysis of the Fe-Al alloy layer by a wavelength dispersive X-ray analyzer.

According to the analysis results, the Al component was 52.8% at the center and 45.0% at the carbon fiber side, and was found to be almost uniform. The same results were obtained. FIG.
In the photograph of, the part indicated by a triangle indicates the central part where the quantitative analysis was performed.

[0043]

The present invention has the above-described structure and operation. Since the outside of the passage member is made of heat-resistant cast iron having high strength, there is no destruction due to dropping or the like. In addition, the molten metal passage is made of woven cloth carbon fiber that has been carbonized.
Tissue does not react with molten aluminum for carbon fiber-reinforced carbon material was present pores, since slug in the circumferential path does not adhere, over a hot water supply amount of precision without changing a passage cross-sectional area for long-term maintenance Maintenance work such as cleaning the inside of the passage is unnecessary.

Furthermore, since the outside is made of heat-resistant cast iron, mechanical connection such as flange connection is facilitated, and a short transfer pipe can be connected without using a long transfer pipe.

[0045]

[Table 1]

[Brief description of the drawings]

FIG. 1 shows a molten metal transfer pipe according to one embodiment of the present invention. FIG. 1 (a) is a longitudinal sectional view, and FIG. 1 (b) is a partially broken enlarged perspective view schematically showing a structure. FIG.

2 (a) is a longitudinal sectional view showing only a passage member of the molten metal transfer pipe of FIG. 1, and FIG. 2 (b) is a partially broken enlarged perspective view schematically showing a structure.

FIGS. 3 (a) to 3 (d) are explanatory views schematically showing steps of manufacturing a passage member.

FIG. 4 is a sectional view of a sand mold in which a passage member is cast with heat-resistant cast iron.

FIG. 5 is a diagram showing a metal in a boundary layer between a passage member and a heat-resistant cast iron member.
It is a microscope picture which shows a structure .

FIG. 6 is a cross-sectional view taken along line aa of the micrograph of FIG. 5;
It is a figure which shows the result of line analysis with the line microanalyzer.

FIG. 7 is a schematic sectional view of an electromagnetic hot water supply die casting machine using a conventional molten metal transfer pipe.

FIG. 8 is a schematic sectional view of a low-pressure casting machine using another conventional molten metal transfer pipe.

[Explanation of symbols]

 Reference Signs List 1 molten metal transfer pipe 2 molten metal passage 3 passage member 4 heat-resistant cast iron member 5 carbon fiber 6 carbon fiber spun yarn fabric 10 core 11 prepreg 12 intermediate molded body 13 carbonized intermediate molded body 14 pitch 20 sand mold

Continuation of the front page (51) Int.Cl. ⁶ Identification code FI B22D 35/00 B22D 35/00 G C04B 35/83 C04B 35/52 E (72) Inventor Kenji Niijima Kamitsuji character in Nagaizumi-cho, Sunto-gun, Shizuoka Prefecture No. 234, Takaishi Jihoho Rayon Co., Ltd. (72) Inventor Masahiro Hayashi, No. 234, Takatsugi, Kamichi-cho, Nagaizumi-cho, Sunto-gun, Shizuoka Pref. A) JP-A-50-47825 (JP, A) JP-A-3-169465 (JP, A) JP-A-63-11583 (JP, A) JP-A-56-140080 (JP, A) JP-A-1 −143759 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B22D 19/00 B22D 17/20 B22D 18/04 B22D 19/14 B22D 35/00

Claims (5)

(57) [Claims] 1. A molten metal transfer pipe of a casting apparatus, wherein a carbon fiber having a passage member for transporting the molten metal is woven.
A molten metal transfer pipe comprising a carbon fiber reinforced carbon material that has been subjected to a chemical treatment and has pores in its structure, and wherein the outside of the passage member is filled with heat-resistant cast iron. 2. The molten metal transfer pipe according to claim 1, wherein the surface of the carbon fiber reinforced carbon material constituting the passage member is coated with silicon carbide and then cast with heat-resistant cast iron. 3. A carbon fiber filament or carbon fiber spun yarn woven fabric is molded into an intermediate molded body having a predetermined shape by using a material impregnated with a thermosetting resin, and the intermediate molded body is subjected to a carbonization treatment. A method for manufacturing a molten metal transfer tube, comprising: forming a passage member made of a material; and casting the formed passage member with heat-resistant cast iron to manufacture a molten metal transfer tube. 4. The method for producing a molten metal transfer pipe according to claim 3, wherein a pitch is further impregnated into the carbonized molded body obtained by carbonizing the intermediate molded body to perform a carbonization treatment to densify the structure. 5. A carbonization treatment before casting with said heat-resistant cast iron.
4. The molded article further provided with a silicon carbide coating.
Or the method for producing a molten metal transfer pipe according to 4.