JPH05293623A - Pump member for die casting and production thereof - Google Patents

Abstract

PURPOSE:To provide a pump member for die casting and a manufacturing method thereof which does not break by thermal stress at the time of internal chill does not develop fatigue breakage at the time of injecting and is not eroded by molten aluminum and can absorb thermal impact and the thermal stress acted to the insert member and prevent the erosion of a heat resistant cast iron member. CONSTITUTION:In pump member for die casting constituted with tubular insert members 7A, 10A as a passage for molten metal in the inner hole and the heat resistant cast iron members 7B, 10B casting-in the insert members, the insert member is composed of carbon fiber reinforced carbon material reinforced with the carbon fiber 16. The carbon fiber reinforced carbon material is constituted with carbon fiber spun yarn texture 200 as base material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot chamber die casting machine, and more particularly to an injection pump for pumping molten aluminum alloy, and more particularly to a structure of a pump member serving as a passage for the molten metal and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, the aluminum alloy die casting method is a cold chamber method.
There is no hot chamber type. The reason is that molten aluminum is eroded by all the metals and does not function as a pump member.

In order to make it possible to produce such an aluminum alloy in a hot chamber system, a pump member has conventionally been proposed in which a corrosion resistant member such as ceramics or graphite is cast in a portion in contact with the molten aluminum alloy ( For example, see Japanese Examined Patent Publication No. 55-49945).

That is, as shown in FIG. 10, a heat-resistant cast iron member 102 is used as a tubular insert member 101 made of porous ceramics or the like which is not affected by contact with the molten metal to form the passage 100 of the molten metal and has high strength. It had a cast structure.

[0005]

However, none of these techniques are currently in practical use.

[0006] The main reason for this is that there is a large difference in thermal expansion between the heat-resistant cast iron member 102, which is a cast-in-circle material, and the insert member 101, which is a material that is cast-in, so that the cast-in-wheel is affected by thermal shock and shrinkage stress during casting. Insert member 101
There was a problem that was destroyed.

For example, as a material of the insert member 101, Al ₂ O 3 is used as a ceramic that can withstand molten aluminum.
_{When using 3} , ZrO ₂ , Si ₃ N ₄ , SiC, etc.,
Since the material to be cast is generally heat-resistant cast iron, the casting temperature is about 1350 ° C., and the insert member 101 to be cast is set in a sand mold and is in a dried state at about 200 ° C. When pouring into the sand mold, there is a temperature difference of 1150 ° C. between the insert member 101 and the heat-resistant cast iron molten metal.
All 01 are destroyed by thermal shock.

Therefore, as shown in FIG. 11, the thermal shock absorbing material 103 made of a heat insulating ceramics sheet is wound around the surface of the insert member 101 so as to absorb the thermal shock and to be cast. If such a method is adopted, cracking does not occur during casting.

However, when this member is used as an injection pump member and is injection-molded for a long time at a casting pressure of 150 [Kgf / cm ² ] at the time of injection, the thermal shock absorbing material 103 is crushed into pieces and the insert member. 101 and heat-resistant cast iron member 102
A gap 104 is generated between them. Therefore, at the time of injection, an impact force acts on the insert member 101 and the insert member 101 is easily broken.

As a result, aluminum flows out from the fractured surface and corrodes the cast iron on the back surface.

Further, graphite has a small Young's modulus and good thermal conductivity. Therefore, the insert member 101 to be cast may be cast by using a graphite material having a large porosity. With this method, thermal shock can be mitigated and cracking does not occur during casting.

However, this graphite insert member 10
The tensile strength of 1 is 2 [Kgf / mm ² ] or less, and fatigue fracture occurs in a short time due to repeated stress during injection. If destroyed, the heat-resistant cast iron member 102 is easily eroded and melted as described above.

Further, there has been proposed a structure in which the insert member 101 is divided into a plurality of parts as shown in FIG. 12 in order to prevent thermal shock (see Japanese Patent Publication No. 56-26503). In this example of the divided structure, the connecting pipe 106 is divided into the dividing members 107, 10
8 is fitted to the outer periphery of the end portion of the member 8, and the gap g between the ends of the split members 107 and 108 absorbs the difference in thermal expansion in the axial direction between the insert member 101 and the heat-resistant cast iron member 102.

However, in such a divided structure, an abnormal pressure is applied to the joint between the divided members 107 and 108, so that the connecting pipe 106 swells as shown in FIG. Each split member 10 from the gap at both ends
The metal of the heat-resistant cast iron member 102 is melted and eroded by flowing into the boundary portion between the heat-resistant cast iron member 102 and the heat-resistant cast iron member 102 rapidly in the direction of the arrow in the figure. The finer the insert member 101 to be cast is, the more joints are formed, and the molten aluminum leaks from this joint portion at the time of injection to cause local erosion.

For this reason, a graphite member having a small Young's modulus is used to alleviate the thermal shock at the time of casting and to solve the leak of the joint with a screw structure. As a result, cracks occur, and as described above, the heat-resistant cast iron, which is the cast-molding material on the back side of the insert member, is eroded.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and the purpose thereof is not to be destroyed by the thermal stress at the time of casting, not to be fatigue-damaged at the time of injection, and to be melted. It is an object of the present invention to provide a pump member for die casting which can absorb the thermal shock and thermal stress acting on the insert member without being corroded by aluminum and can prevent the melting damage of the heat resistant cast iron member, and a method for manufacturing the same.

[0017]

In order to achieve the above object, according to the present invention, a tubular insert member having an inner hole serving as a passage for molten metal, and a heat-resistant member formed by casting the insert member. A die casting pump member formed of a cast iron member is characterized in that the insert member is made of a carbon fiber reinforced carbon material.

It is preferable that the carbon fiber reinforced carbon material is constituted by using a carbon fiber spun yarn woven fabric as a base material.

Further, in the method of manufacturing a pump member for die casting of the present invention, the shape of the insert member is formed by winding a carbon fiber spun yarn woven fabric in which a model core is impregnated with a thermosetting resin in multiple layers. A step of forming a first-stage intermediate molded body obtained by patterning; a step of heating the first-stage molded body to cure a thermosetting resin to form a second-stage intermediate molded body; A step of extracting a model core from the second-stage intermediate molded body and carbonizing it to obtain an insert member made of a carbon fiber reinforced carbon material, and completing the pump member by casting the insert member with heat-resistant cast iron. Characterize.

In the step of carbonizing the intermediate molded body in the second stage, it is preferable that the intermediate molded body is impregnated with pitch to carry out the carbonization treatment.

The term "aluminum alloy" described in this specification is used to mean not only an aluminum alloy but also aluminum alone.

[0022]

In the present invention, since a carbon material having a Young's modulus smaller than that of ceramics is used, the carbon material is strong against thermal shock during casting and is not likely to be damaged during casting.

Further, since it is reinforced with carbon fibers, it is strong against repeated stress due to injection and does not break even during injection.

As described above, since damage to the insert member can be prevented during casting and injection, the molten metal does not leak from the damaged part of the insert member, and the molten heat-resistant cast iron is melted by the molten aluminum for a long period of time. Loss can be prevented.

Further, by using the carbon fiber spun yarn fabric as the carbon fiber, the insert member can be integrally constructed.

Further, by using a woven fabric, the strength of the entire insert member can be averaged.

[0027]

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

FIG. 2 shows a pump portion of a hot chamber type die casting machine in which the pump member of the present invention is used. In the figure, 1 is an injection pump, which is arranged near a fixed base 3 to which a mold 2 is attached. Further, next to the injection pump 1, a melting furnace 4 for supplying molten metal to the injection pump 1 is arranged.

The injection pump 1 comprises a gooseneck portion 7 to which a molten metal 5 is supplied from a melting furnace 4 through a connecting pipe 6, and a pump drive portion 8 mounted on the gooseneck portion 7.
The nozzle portion 10 for discharging the molten metal 5 in the gooseneck portion 7 into the cavity 9 of the mold 2.

The gooseneck portion 7 is provided with a molten metal passage 11 for guiding the supplied molten metal 5 to the nozzle portion 10. Further, a vertical hole 12 for assembling the pump drive unit 8 is provided on the upper surface of the gooseneck portion 7, and an inlet of the molten metal passage 11 is opened at the bottom surface of the vertical hole 12. On the other hand, the outlet of the molten metal passage 11 is open to the side surface of the upper end portion of the gooseneck portion 7, and the nozzle portion 10 is connected to the outlet of the molten metal passage 11.
It is injected through 1 into the cavity 9.

The pump drive unit 8 has a cylinder 13 which is inserted into the vertical hole 12 and whose lower end is connected to the inlet of the molten metal passage 11, a plunger 14 which is slidably inserted into the cylinder 13, and a cylinder 13. And a hydraulic cylinder 15 attached to the upper end to reciprocate the plunger 14. A connecting pipe 6 for supplying the molten metal 5 from the melting furnace 4 is connected to a middle portion of the cylinder 13. The height of the connecting pipe 6 is equal to that of the molten metal 5 in the melting furnace 4.
The liquid level is lower than the liquid level in the melting furnace 4, and the molten metal 5 in the melting furnace 4 is automatically supplied into the cylinder 15 due to this head difference.

Thus, the molten metal passage 11 of the gooseneck portion 7
The molten metal 5 filling the inside is pumped into the cavity 9 of the mold 2 through the nozzle portion 10 by the plunger 14 driven by the hydraulic cylinder 15. During this injection operation, the connecting pipe 6, the gooseneck portion 7, and the nozzle portion 10 are held at 680 ° C. by the heaters 6H, 7H, 10H, respectively.

The present invention is particularly used for the gooseneck portion 7 and the nozzle portion 10 to which the injection pressure acts at the time of injection.

The gooseneck portion 7 and the nozzle portion 10 are
Insert members 7A, 1 as cast-molded members
0A and heat resistant cast iron members 7B and 10B that surround the insert members 7A and 10A.

The insert member which has been conventionally used is manufactured by firing powder of graphite or ceramics and is hard and brittle, so that it does not function as a cast-in member.

In the present invention, the insert members 7A, 1
0A is made of a carbon material reinforced with carbon fibers 16 as shown in FIGS.

When the carbon fiber reinforced carbon material is used as described above, since it is basically a carbon material, it has high thermal conductivity and low Young's modulus and thermal expansion coefficient. Therefore, it is strong against thermal shock during casting, and there is no possibility that the insert members 7A and 10A will be damaged during casting.

Further, since it is reinforced by the carbon fiber, it is strong against repeated stress due to injection and does not break even during injection.

Particularly, in this embodiment, the carbon fiber 16 is made into the carbon fiber spun yarn fabric 200, and the carbon fiber spun yarn fabric 2 is obtained.
00 has a multi-layer structure in which the carbon material is laminated in the thickness direction, and the tensile strength and the breaking strain can be made larger than that of a simple carbon material structure such as graphite.

Incidentally, according to the experiment, the thermal conductivity is 0.2.
[cal / cm ・ sec ・^. c] and Young's modulus is 3000 [kgf / mm
² ], the coefficient of thermal expansion is also 1 to 3 × 10 ^-6 [1 / ^. c] and a low value could be obtained. On the other hand, the tensile strength is 15-
A large value of 20 [kgf / mm ² ] and a breaking strain of 0.5 to 1.0% could be obtained.

Further, since it is reinforced by the carbon fibers 16, the fracture mode is different from that of ceramics and graphite, and the fracture that separates into two does not occur. That is, even if a part is damaged by the impact, the damaged part reinforced by the carbon fiber 16 does not expand.

Next, a method of manufacturing the pump member of the present invention will be described with reference to FIGS.

First, a carbon fiber spun yarn woven fabric 200 is impregnated with a thermosetting resin 201 such as a phenol resin to obtain about 20
A carbon fiber woven tape 202 is formed by cutting into a width of [mm] (see FIGS. 4 (a) to 4 (c)).

The carbon fiber woven tape 202 is applied to the insert members 7A, 1 of the gooseneck portion 7 and the nozzle portion 10.
The model cores 203 and 204, which are modeled from 0A, are tape-wrapped to a predetermined thickness (10 mm) at an angle in the range of 30 to 40 degrees with respect to the axial direction, and the intermediate molded body 2 of the first stage is formed.
05 and 206 are molded (see FIGS. 4D to 4I).

Then, the thermosetting resin 201 such as phenol resin is heated in a furnace 216 to about 150 ° C., and the model cores 203 and 204 after curing are removed and the second core is removed.
Forming the molded bodies 207 and 208 of the stage (Fig. 5 (a)-
(See (c)). In the case of a complicated shape such as the model core 203 of the gooseneck portion 7, by forming the gooseneck portion 7 with, for example, a flexible material, it is possible to easily pull out after curing.

Next, the members 207 and 208 are carbonized in an inert gas atmosphere (for example, nitrogen gas N ₂ ) at about 1000 ° C. (see FIG. 6A). However, in this state, the porosity is so large that pitch 209 is impregnated and carbonized at the above temperature (see FIGS. 6 (b) and 6 (c)).

The impregnation of the pitch 209 is performed by vacuum suction, for example. First, the molded bodies 207 and 208
The outer circumference is covered with a pitch 209, and the blind lid 210 closes the openings at both ends of the molded bodies 207 and 208.
Next, air is sucked into the molded bodies 207, 208 from the suction holes 212 provided in the blind lid 210 by the vacuum suction source 211, and the pitch 209 is formed on the peripheral walls of the molded bodies 207, 208 by the pressure difference between the inside and outside of the molded bodies 207, 208. The holes are filled with pitch.

This operation was repeated 3 times to obtain a bulk specific gravity of about 1.
Set to 5. Insert member 7 manufactured in this way
A and 10A are used as the core of the gooseneck part 7 and the nozzle part 10 as a pump member, and are cast. Since the cast iron material requires strength at high temperatures, special cast iron containing chromium and molybdenum is used. About 1 for this cast iron material in a high frequency furnace
Melts at a temperature of 500 ° C.

Also, insert members 7A, 1 to be cast
For example, taking the insert member of the gooseneck portion 7 as an example, 0A is set in the sand mold 213 as shown in FIG. The mold 213 is dried to about 150 ° C., the moisture of the insert member 7A which is to be cast is completely removed, and then the cast iron is poured from the runner 214. In the figure, reference numeral 215 is a feeder for pushing the poured molten metal.

The members thus cast were used as the gooseneck portion 7 and the nozzle portion 10 of the die casting machine shown in FIG. Both are pump members having an aluminum molten metal passage that is repeatedly subjected to high injection pressure.

The injection test was carried out by incorporating the gooseneck portion 7 and the nozzle portion 10 thus molded into a die casting machine. The conditions of die casting are as follows.

Casting pressure 100 to 200 [kgf / cm ² ], casting speed 0.2 to 0.6 [m / sec], casting material ADC12
(JIS standard), a casting temperature of 650 ° C., a life test was performed under the conditions of a heating and holding temperature of 680 ° C. for the nozzle portion 10, the connecting pipe 6, and the gooseneck portion 7.

As a result, no problem such as breakage of the insert members 7A and 10A occurred even after molding about 80,000 times, and there was no abnormal erosion, and good results were obtained.

FIG. 8 is a micrograph of a cross section of the structure between the insert member 7A of the gooseneck portion 7 and the heat resistant cast iron member 7B after the life test.

In this photograph, A is the region of the carbon fiber reinforced carbon material forming the insert member 7A, B is the boundary layer region of the heat resistant cast iron and the carbon fiber reinforced carbon material, and C is the region of the heat resistant cast iron. is there. According to the photograph, the boundary layer area B is about 1 mm
As a result of analysis, it was revealed that the boundary layer region B was a uniform Fe—Al alloy layer as shown below.

FIG. 9 shows the alloy layer in the boundary layer region B as a-
It shows the result of scanning along the line a (see FIG. 8) and analyzing with an X-ray microanalyzer.

This X-ray micro-analyzer counts the number of pulses peculiar to each element when the X-ray beam is applied to each element. As analysis elements, iron (Fe) that constitutes the heat-resistant cast iron part, It is aluminum (Al), which is a constituent of the injected molten metal. The vertical axis of the chart is 2500,
15,000 [cps / 25mm], chart horizontal axis is 100 [μm
/ 30mm].

According to this diagram, the amounts of Fe and Al are almost constant throughout the boundary layer region B. this is,
Although the molten aluminum permeates the carbon fiber reinforced carbon material region A of the insert member and diffuses to the heat resistant cast iron region C side, the amount of diffusion is completely saturated, which means that the diffusion does not proceed any further. It can be seen that the corrosion of the heat-resistant cast iron by the molten aluminum could be completely prevented.

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

According to this analysis result, the Al component was 52.8% in the central part and 45.0% in the carbon fiber side, and it was found that they were almost uniform, and the analysis result by the X-ray microanalyzer was obtained. The same result was obtained. It should be noted that in the photograph of FIG. 8, the circled portion is the central portion where the quantitative analysis was performed.

[0061]

According to the present invention having the above-described structure and operation, since the insert member is formed of a carbon material having a large thermal conductivity and a small thermal expansion coefficient, damage due to thermal shock during casting can be prevented.

Further, by using a carbon fiber reinforced carbon material as the carbon material, the carbon material is strong against repeated injection pressure, and there is no fear of damage during injection.

As described above, since it is possible to prevent the insert member from being damaged during casting and injection, it is possible to prevent melting loss of the heat-resistant cast iron and to realize a die casting pump member having excellent durability. You can

[0064]

[Table 1]

[Brief description of drawings]

FIG. 1 shows a pump member for die casting according to an embodiment of the present invention. FIG. 1 (a) is a sectional view of the pump member, and FIG. 1 (b) is a joining of an insert member and a heat-resistant cast iron member. It is a partial three-dimensional sectional view of the part.

FIG. 2 is a schematic sectional view of a hot chamber type die casting machine.

3 (a) and 3 (b) are sectional views showing only the insert member of the pump member shown in FIG. 1, and FIG. 3 (c) is a partially cutaway enlarged perspective view schematically showing the structure of the insert member. It is a figure.

4 (a) to 4 (g) are explanatory views of the winding process of the carbon fiber woven fabric, FIG. 4 (h) is an enlarged sectional view taken along line HH of FIG. 4 (e),
(I) is an enlarged sectional view taken along line I-I of (g).

5 (a) to 5 (c) are explanatory views of a hardening process of a thermosetting resin and a model core extracting process.

FIG. 6 (a) is an explanatory view of a carbonization treatment step, and FIG. 6 (b).
, (C) are explanatory views of the step of impregnating the molded body with pitch.

FIG. 7 is a cross-sectional view of a sand mold in which an insert member is cast with heat-resistant cast iron.

FIG. 8 is a copy of a micrograph showing a boundary layer between an insert member and a heat-resistant cast iron member.

9 is a cross-sectional view taken along line aa of the photomicrograph of FIG.
It is a figure which shows the result of the line analysis by the line microanalyzer.

FIG. 10 is a schematic sectional view of a conventional pump member.

11 is a cross-sectional view showing a melted state of the pump member of FIG.

FIG. 12 is a schematic cross-sectional view of another conventional pump member.

13 is a cross-sectional view showing a melted state of the pump member of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Injection pump 2 Mold 3 Fixing stand 4 Melting furnace 5 Molten metal 6 Connecting pipe 7 Gooseneck part (pump member) 7A Insert member 7B Heat resistant cast iron member 8 Pump drive part 10 Nozzle part (pump member) 10A Insert member 10B Heat resistant cast iron member 11 Molten metal passage 13 Cylinder 15 Hydraulic cylinder 16 Carbon fiber 200 Carbon fiber spun yarn woven fabric

[Procedure amendment]

[Submission date] February 22, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Figure 8

[Correction method] Change

[Correction content]

FIG. 8 is a boundary layer between an insert member and a heat-resistant cast iron member.
3 is a copy of a micrograph showing the metallographic structure of FIG.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenji Niijima 234 Takaishi, Uechikari, Nagaizumi-cho, Sunto-gun, Shizuoka Prefecture Toho Rayon Co., Ltd. Research Institute (72) Masahiro Hayashi, Takaishi, Nagaizumi-cho, Sunto-gun, Shizuoka Address 234 Toho Rayon Co., Ltd.

Claims (4)

[Claims] 1. A pump member for die casting, which comprises a tubular insert member that serves as a passage for molten metal and on which an injection pressure upon injection acts, and a heat-resistant cast iron member that is formed by casting the insert member, A pump member for die casting, wherein the insert member is made of a carbon fiber reinforced carbon material. 2. The pump member for die casting according to claim 1, wherein the carbon fiber reinforced carbon material is constituted by using a carbon fiber spun yarn woven material as a base material. 3. A first-stage intermediate molded body having a shape of an insert member formed by winding a carbon fiber spun yarn woven fabric, in which a thermosetting resin is impregnated in a model core, in multiple layers. And a step of heating the first-stage molded body to cure the thermosetting resin to form a second-stage intermediate molded body, and a model core from the second-stage intermediate molded body. A step of extracting and performing carbonization treatment to obtain an insert member made of a carbon fiber reinforced carbon material, and a method for manufacturing a pump member for die casting, which comprises casting the insert member in heat-resistant cast iron to complete the pump member. 4. The method for producing a die casting pump member according to claim 3, wherein in the step of carbonizing the intermediate molded body in the second stage, the intermediate molded body is impregnated with pitch to carry out the carbonization treatment.