JPH0890145A - Forming mold, manufacture thereof and casting method using the forming mold - Google Patents

Abstract

PURPOSE: To provide a forming mold for forming the outer surface which can easily and simply cast a cast product having complicate outer surface shape. CONSTITUTION: The forming mold 20 for forming the outer surface is fitted on the inner surface of the cavity of a metallic mold. The forming mold 20 has a square cylindrical state forming mold body 21, and many through-holes 22 are arranged between the fitting surface 25 and the inside surface 26 of the forming mold body 21. In the fitting surface 25, grooves 23 communicated with the through-holes 22 are arranged. The forming mold 20 is made of powdery graphite and a plastic material for sticking mutually powdery graphite.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die, a method for manufacturing the same, and a casting method using the molding die.

[0002]

2. Description of the Related Art Generally, when an aluminum casting is produced by a die casting method or the like, molten aluminum is injected into the casting die. In this case, the outer surface shape of the aluminum casting is the cavity inner surface of the casting die. Is molded by. When the outer surface shape of the aluminum casting is flat or has a simple shape, the outer surface shape of the aluminum casting can be easily formed by the inner surface of the cavity of the casting die.

When the outer surface of the aluminum cast product has a predetermined shape, the inner surface of the cavity is formed to match the outer shape of the cast product.

[0004]

Conventionally, when it is desired to finish the outer surface of an aluminum cast product into a more complicated shape, after the aluminum cast product is once cast by a casting die, the outer surface of the aluminum cast product is ground or cut. It is processed into a desired outer surface shape.

However, when grinding or cutting an aluminum cast product, the number of processes is increased by that much, and the work efficiency is reduced. In addition, it may be difficult to obtain a desired outer surface shape by grinding or cutting.

The present invention has been made in view of the above points, and a molding die capable of easily and easily casting a cast product having a desired outer surface shape without grinding or cutting. It is an object to provide a manufacturing method and a casting method using a molding die.

[0007]

The invention according to claim 1 is composed of powdered graphite and a plastic material for adhering the powdered graphite to each other, and is mounted on at least a part of the inner surface of the casting mold cavity, and cast. It is a forming die for forming an outer surface of an outer surface of a cast product cast by a die.

The invention according to claim 3 comprises a step of kneading the powdery graphite and the plastic material while heating, and a step of injecting the kneaded powdery graphite and the plastic material into an injection mold. It is a method for producing the molding die described in 1.

According to a fourth aspect of the present invention, there is provided a step of mounting a molding die for outer surface molding according to the first aspect on an inner surface of a cavity of a casting mold, and a molten metal is injected into the cavity of the casting mold to obtain a casting product. An outer surface molding comprising the steps of: molding the product, removing the cast product and the mold from the casting mold, immersing the cast product and the mold in a solvent, leaching the mold and removing it from the cast product. It is a casting method using a mold for molding.

[0010]

According to the present invention, a mold for outer surface molding is mounted on at least a part of the inner surface of the cavity of the casting mold,
Molten metal is injected into the cavity to form a casting.
In this case, the outer surface of the cast product is molded by the molding die.
After molding the cast product, the cast product and the molding die are removed from the casting mold. In this case, since the graphite component of the mold has excellent lubricity and releasability, the cast product and the mold can be easily taken out from the casting mold. Then, when the casting and the molding die are immersed in a solvent, the plastic component of the molding die is dissolved in the solvent. On the other hand, since the graphite component of the mold has excellent lubricity and peelability, it easily flows out of the casting into the solvent.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 9 are views showing an embodiment of the present invention.

First, the outline of an aluminum die casting apparatus will be described with reference to FIGS. 2 and 3. As shown in FIG. 2 and FIG. 3, the aluminum die casting apparatus includes a fixed mold 11,
Movable mold 1 movably arranged with respect to fixed mold 11.
2 and a cavity 15 is formed in the movable mold 12. Further, the fixed mold 11 is adapted to seal the cavity 15 in the movable mold 12, and a concave portion 17 is formed on the surface of the fixed mold 11 on the movable mold 12 side. A gate 18 communicates with the recess 17, and an introduction passage 18a having an inlet 19 for molten aluminum communicates with the gate 18.

Further, a metal core 13 protruding from the movable mold 12 is provided in the cavity 15 of the movable mold 12, and a space 43 of an aluminum casting 40 described later is formed by the metal core 13 ( (See FIG. 6). The fixed mold 11, the movable mold 12, and the metal core 13 are all made of steel.

As shown in FIGS. 3 (a) and 3 (b), the cavity 15 of the movable mold 12 has a rectangular shape when viewed from the fixed mold 11 side, and in the rectangular cavity 15, A molding die 20 for molding the outer surface of the aluminum casting 40 is fitted. In this case, the mold 2
0 has a rectangular tubular shape corresponding to the rectangular shape of the cavity 15, and the four side surfaces 20 of the molding die 20 are mounting surfaces and are in contact with the four side surfaces 15a of the cavity 15. 3A is a view of the movable mold 12 as seen from the fixed mold 11 side, while FIG. 3B is a view of the fixed mold 11 as seen from the movable mold 12 side.

Further, as shown in FIG. 3 (a), the rectangular cylindrical molding die 20 is composed of four parts joined by a joining surface 29.

Next, a molding die 20 for molding the outer surface will be described with reference to FIGS. 1, 4 and 5. As shown in FIGS. 1, 4 and 5, the mold 20 has a square tubular shape and is made of powder graphite and a plastic material such as a polycarbonate material for adhering the powder graphite to each other. .

The mold 20 comprises a mold body 21, which has a mounting surface 25 in contact with the side surface 15a and an inner side surface 26 facing the inside of the cavity 15. Further, the molding die body 21 is provided with a large number of through holes 22 penetrating the mounting surface 25 and the inner side surface 26. Of these, the inner surface 26 of the molding die body 21 is an aluminum casting 40.
The outer surface of the case body 41 (FIG. 6) is molded,
The through hole 22 is the outer protruding portion 45 of the aluminum casting 40.
Is molded.

A groove 23 and a collecting groove 24 are formed on the mounting surface 25 of the molding die body 21. Of these, the groove 23 extends parallel to the central axis L of the rectangular tubular molding die 20, and the collecting groove 24 extends orthogonally to the groove 23. Further, the through holes 22 penetrating the molding die body 21 are provided on the mounting surface 25 of the molding die body 21 such that the through holes 22 are provided side by side vertically and horizontally in the shape of a base. It communicates with the groove 23. That is, this groove 23
Are arranged corresponding to each row of the through holes 22, and
Reference numeral 4 extends in a substantially central portion of the mounting surface 25 of the molding die body 21 so as to be orthogonal to the groove 23.

For this reason, the molding die 2 is introduced from the inside of the cavity 15.
The molten aluminum that has passed through the through hole 22 of
3 and then gathered in the gathering groove 24 to form the molding die 20.
It is designed to enter the air reservoir 27 provided at the end of the. A total of eight air reservoirs 27 are provided for both ends of one mounting surface 25, and a total of eight forming dies 20 are provided to receive gas such as air in the cavity 15 during casting. Further, the air reservoir 27 is provided with a reinforcing plate 30 that reinforces the molding die 20. Since the aluminum casting 40 in the air reservoir 27 has many voids, it is removed after casting.

Next, a method for manufacturing the molding die 20 will be described. The mold 20 is manufactured by injection molding using a graphite-containing plastic pellet material. First, the outline of the manufacturing process of the plastic pellet material containing graphite will be described.

As shown in FIG. 8, in the extruder 110, a hopper 123 is first filled with a raw material 125 made of polycarbonate pellets and powder graphite. The weight ratio between the polycarbonate pellets and the powdered graphite in the hopper 123 is in the range of 90:10 to 10:90 corresponding to the weight ratio between the polycarbonate component and the graphite component of the graphite-containing plastic pellet material 117 described later. It is in. Next, the raw material 125 in the hopper 123 is transferred to the cylinder 1
26, the raw material 125 is pressurized in the cylinder 126 as the screw 128 rotates, and is heated by the heater 127.

When the raw material 125 is heated and compressed in the cylinder 126, the polycarbonate pellets are melted and mixed with the powder graphite, and the head 12 of the extruder 110 is melted.
9 flows out through the die 111 (FIG. 7).

Since graphite does not chemically react with synthetic resin under environmental conditions of 1000 ° C. or less, in a mixture of polycarbonate and graphite, polycarbonate and graphite independently exist with their own properties. .

Next, as shown in FIG. 7, the polycarbonate and graphite kneaded in the extruder 110 form a strand-like mixture 112 and are sent from the die 111 into the pelletizer 116. In the pelletizer 116, the strand-shaped mixture 112 is sent to the rotary blade 115 side by the feed rolls 113 and 114, and is finely broken by the rotary blade 115 to obtain a graphite-containing plastic pellet material 117 having a diameter of 1 to 2 mm. The plastic pellet material 117 contains a polycarbonate component and
It is a mixture with the graphite component, and the weight ratio of the polycarbonate component and the graphite component is 90:10 as described above.
It is within the range of 10:90. When the weight ratio of the polycarbonate component and the graphite component is more than 90:10, the release property of the product obtained by injection molding is slightly inferior.

When the weight ratio of the polycarbonate component to the graphite component is more than 10:90, the toughness of the product obtained by injection molding is poor.

By the way, the combination of the polycarbonate component and the graphite component is determined as follows. That is, when an injection molded product having a simple structure and a large volume is prepared, a combination of a polycarbonate component and a graphite component having a relatively large graphite volume% is selected from the table below.
In this case, for example, if a combination of 70% by volume of graphite is selected, 1540 g of graphite and 360 of polycarbonate are selected.
are mixed with g. The table below shows the total volume of 1000c.
The blending amount (g) of graphite and polycarbonate corresponding to the graphite volume% in the case of m ³ is shown.

On the other hand, when an injection molded product having a complicated structure and a small volume is produced, a combination of a polycarbonate component and a graphite component having a relatively small graphite volume% is selected.

[Table 1]

Next, a method of manufacturing the molding die 20 using the plastic pellet material 117 containing graphite thus obtained will be described with reference to FIG.

As shown in FIG. 9, the injection molding machine 130 includes an injection ram 1 slidably provided in an injection cylinder 134.
35 and a hydraulic motor 137 that rotationally drives the injection ram 135 via the drive shaft 138. A screw 132 is connected to the injection ram 135, and the screw 132 is arranged in the barrel 136. Further, a graphite-containing plastic pellet material 117 is supplied from the hopper 131 to the screw 132. Further, a nozzle 139 is provided at the tip of the screw 132, and the nozzle 139 is connected to an injection mold including a fixed mold 40 and a movable mold 141.

Next, the injection molding method of the molding die will be described. First, the hopper 131 is filled with the graphite-filled plastic pellet material 117, and then the hydraulic motor 137 rotates the screw 132 via the injection ram 135. During this time, the graphite-containing plastic pellet material 117 is supplied into the screw 132,
By rotation of graphite pellets made of plastic 11
Of the 7, the polycarbonate component is melted. Next, a mixture of powdered graphite mixed in the molten polycarbonate,
It is injected into the cavity between the fixed mold 140 and the movable mold 141 through the nozzle 139, and thus the molding mold 20 made of polycarbonate and powder graphite is obtained.

Among the components of the mold 20, polycarbonate has excellent heat resistance and high toughness. On the other hand,
The powdered graphite is a hexagonal material, has a hardness of 1.5 and a specific gravity of 2.
It is 2. Graphite has excellent heat resistance as well as excellent lubricity (peelability) due to its crystal structure. Graphite has high mechanical strength at high temperatures and is insoluble in both inorganic and organic solvents. It has characteristics.

Further, polycarbonate and graphite exist with their respective unique characteristics without causing a chemical reaction with each other as described above.

From the above, the molding die 20 made of polycarbonate and powdered graphite is an injection molded product having excellent heat resistance and lubricity. In this case, of the components of the mold 20, polycarbonate plays a role of adhering the powdery graphites together.

Next, a casting method using the forming die for forming the outer surface having the above-mentioned structure will be described.

First, as shown in FIG. 2, a plastic cylindrical square mold 20 is placed in the cavity 15 of the movable mold 12.
Is inserted. In this case, the central axis L of the mold 20 coincides with the central axis of the metal core 13.

Next, the movable mold 12 approaches the fixed mold 11, and the cavity 15 of the movable mold 12 is fixed to the fixed mold 11.
Sealed by. In this state, molten aluminum is introduced into the introduction passage 18a from the introduction port 19, and the molten aluminum is introduced from the introduction passage 18a through the gate 18 into the cavity 15
Is injected into. The molten aluminum flowing into the cavity 15 from the gate 18 is atomized and the temperature is about 6
It becomes 00 ° C.

As shown in FIGS. 4 and 5, the gate 18
Molten aluminum flowing into the cavity 15 from
After that, the metal core 13 is brought into contact with the metal core 13 and flows toward the molding die 20.
Molten aluminum in the forming die 20 forms the forming die body 2
1 through the through hole 22 from the inner surface 26 side of the molding die body 2
It reaches the mounting surface 25 side of No. 1 and contacts the movable mold 12. Thereafter, the molten aluminum passes through the groove 23 extending parallel to the central axis L of the forming die 20 on the mounting surface 25, and then enters the collecting groove 24 extending orthogonally to the groove 23. Molten aluminum is collected by this collecting groove 24, and the collecting groove 2
After that, the gas flows into the air reservoirs 27 provided in the molding die 20 by eight.

During this time, gas such as air in the cavity 15 is extruded from the through hole 22 into the groove 23 by the molten aluminum, and flows from the groove 23 into the air reservoir 27 through the collecting groove 24.

Next, the molten aluminum filled in the cavity 15 is rapidly cooled by the fixed mold 11 and the movable mold 12 to form an aluminum casting 40.

In this case, heat is also transferred from the molten aluminum to the molding die 20 side made of powdered graphite and polycarbonate. However, the heat conductivity of the mold 20 made of powdered graphite and polycarbonate is extremely smaller than that of the stationary mold 11 and the movable mold 43 made of steel, and therefore the amount of heat transferred from the molten aluminum to the mold 20 is extremely high. Get smaller. Therefore, the mold 20 made of powdered graphite and polycarbonate does not melt during casting, and therefore, the aluminum casting 40 having excellent shape accuracy is obtained.
Can be molded.

By applying a strong heat-resistant silicone rubber (not shown) to the surface of the mold 20 near the thick portion of the aluminum casting 40, the heat escape from the thick portion of the aluminum manufactured article is delayed. However, the mold 20 does not melt.

Next, the movable die 12 is separated from the fixed die 11, and the aluminum casting 40 is taken out together with the forming die 20 from the cavity 15 formed in the movable die 11.

In this case, since the molding die 20 has excellent lubricity and peelability due to the graphite component, the cavity 15
The molding die 20 can be easily and easily taken out together with the aluminum casting 40, and the molding die 20 does not partly adhere or stick to the inside of the cavity 15. Therefore, it is not necessary to clean the inside of the cavity 15 every time the aluminum die casting is performed, and the aluminum die casting can be fully automated. Next, the aluminum casting 40 and the molding die 20 are heated at about 300 ° C. to form the molding die 2
Of 0, the polycarbonate component is melted and allowed to flow out from the outer surface of the aluminum casting 40.

Next, as shown in FIG. 6, the aluminum product 40 is immersed in the solvent 51 in the container 50 together with the mold 20. In FIG. 6, the aluminum casting 40 is shown for the sake of convenience when the mold 20 is removed. By thus immersing the aluminum casting 40 and the molding die 20 in the solvent 51, the remaining polycarbonate component of the molding die 20 can be dissolved by the solvent 51 and completely removed from the aluminum casting 40. On the other hand, the graphite component of the molding die 20 is excellent in lubricity and peelability, so that it is easily and easily removed from the aluminum casting 40 and precipitates in the solvent 51 at the bottom. The polycarbonate component dissolved in the solvent 51 is
Surface up.

Therefore, the graphite component precipitated on the bottom of the solvent 51 and the dissolved polycarbonate component floating on the surface of the solvent 51 can be easily and easily separated in the solvent, and the waste treatment can be facilitated.

Further, by arranging an ultrasonic wave generator (not shown) in the solvent 51 in the container 50, ultrasonic waves can be generated in the solvent 51, whereby the molding die 20 can be moved more quickly. Can be dissolved and removed.

As the solvent for dissolving and removing the polycarbonate mold 20, the following hydrocarbon solvents are used.

Methylene chloride (dichloromethane or methylene chloride), NMP (N-methyl-2-olefin), DMP (NN-dimethylformamide), MFK
(Methyl ethyl ketone), ethyl acetate (ester).

As shown in FIG. 6, a cast aluminum product 4
0 stores electrical products (not shown) inside,
Although it is a heat dissipation case that radiates the heat generated from this electric product to the outside, it may be used for other purposes. The aluminum casting 40 has a space 43 formed therein and has one side 43.
The case main body 41 has an opening a, and a large number of outward protruding portions 45 provided on four side surfaces of the case main body 41 and protruding outward from the case main body 41. A convex portion 42 that slightly protrudes outward is provided on the bottom of the case body 41.

Of these, the space 43 of the case body 41 is molded by the metal core 13, and the outer surface of the case body 41 (the base end surface of the outward protruding portion 45) is the inner surface 26 of the molding die 20.
Is molded by. Further, a large number of outward projecting portions 45 projecting from the case body 41 are molded by the molding die 20 through holes 22, and the convex portion 42 at the bottom of the case body 41 is
It is molded by the recess 17 of the fixed mold 11.

Further, each of the outward protruding portions 45 is connected at the tip thereof by a connecting plate 46, and the connecting plate 46 is molded by the groove 23 and the collecting groove 24 of the molding die 20.

After that, the connecting plate 46 may be ground if necessary, and the connecting plate 4 is ground by grinding the connecting plate 46.
6 and the casting in the air reservoir 27 can be removed. On the other hand, when the connecting plate 46 is not ground, each outer protrusion 45 is reinforced by the connecting plate 46 in terms of strength. Even if the connecting plate 46 is not ground, the cast product in the air reservoir 27 is removed because the voids are generated.

As described above, according to this embodiment, after casting the aluminum casting 40 using the molding die 20 made of powdered graphite and polycarbonate, the aluminum casting 40 together with the molding die 20 is immersed in the solvent 51. Only then, the mold 20 can be easily dissolved and removed from the aluminum casting 40. Therefore, it is possible to easily and easily obtain the aluminum casting 40 having a complicated outer surface shape in which a large number of outward projecting portions 45 are provided on the four side surfaces of the case body 41 without performing grinding or cutting.

Modifications Next, modifications of the present invention will be described. In the above embodiment, the molding die 20 has a rectangular cylindrical shape that is in contact with the four side surfaces of the cavity 15. However, the molding die is not limited to this, and the rectangular molding die is divided into quarters with the joint surface 29 as a boundary. It is also possible to use the one mounted on only one side surface of the cavity 15. In this case, the molding die 20 is mounted on one side surface of the cab 15 via one mounting surface.

Also, an example in which the mold 20 made of powdered graphite and polycarbonate is used as the mold 20 is shown, but the mold is not limited to this, and another thermoplastic resin may be used instead of the polycarbonate. Good. In this case, as the thermoplastic internal resin, a fluororesin such as tetrafluoroethylene resin (polyfluoroethylene resin), a polyimide resin, a polyamide-imide resin, or a polysulfone resin,
Examples thereof include vinyl chloride resin, polyamide resin (nylon resin), polypropylene resin, polyethylene resin, polyester resin (tetron resin), and polysulfone sun resin.

Further, the molding die 20 is composed of a plurality of parts, the thick and simple shape part of each part has a large graphite component to reduce the plastic component, and the thin and complicated part has a graphite part. It is possible to reduce the components and increase the plastic components. By increasing the graphite component in the thick-walled and simple-shaped portion in this manner, the amount of solvent used can be reduced and the molding die 20 can be easily removed from the aluminum casting 40.

In the above embodiment, the case of performing aluminum die casting as one of the casting methods has been described, but it can be applied to the gravity casting method, the low pressure casting method, the precision casting method and other casting methods. it can. Further, the cast product is not limited to aluminum, and lead, subsalt, magnesium, manganese, or alloys thereof can be used.

[0058]

As described above, according to the present invention,
After casting a cast product using a mold, the mold and mold can be removed from the casting mold, and then the mold and mold can be removed from the cast product by simply immersing the cast product and mold in a solvent. It is possible to easily and easily obtain a cast product having a different outer surface shape. In this case, since the graphite component of the molding die is excellent in lubricity and releasability, the cast product and the molding die can be easily taken out from the casting mold. Further, the plastic component of the molded product can be dissolved in the solvent and the graphite component can be made to flow out into the solvent simply by immersing the cast product and the molded product in the solvent. Graphite precipitates at the bottom in the solvent, and the dissolved plastic component floats on the surface of the solvent, so both can be easily separated in the solvent.

[Brief description of drawings]

FIG. 1 is a perspective view showing an outer surface forming mold according to the present invention.

FIG. 2 is a side sectional view of a movable mold and a fixed mold showing a state in which a molding die is mounted in a cavity.

FIG. 3 is a front view showing a movable mold and a fixed mold.

FIG. 4 is an enlarged sectional view taken along line A of FIG.

FIG. 5 is an enlarged side sectional view showing the inside of the cavity of the movable mold seen from the same direction as in FIG.

FIG. 6 is a perspective view showing an aluminum cast product.

FIG. 7 is a diagram showing a method of manufacturing a plastic pellet material containing graphite.

FIG. 8 is a detailed view showing the extruder.

FIG. 9 is a diagram showing a method for manufacturing a molding die.

[Explanation of symbols]

 11 Fixed Mold 12 Movable Mold 13 Metal Core 15 Cavity 20 Mold 21 Mold Main Body 22 Through Hole 23 Groove 24 Assembly Groove 25 Mounting Surface 26 Inner Side 40 Aluminum Cast Article 41 Case Main Body 45 Outer Projection 46 46 Connecting Plate 110 Extruder 116 Pellet 117 Graphite-containing plastic pellet material 130 Injection molding material 140 Fixed mold 141 Movable mold

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B22D 29/00 DA A // B29C 45/00 8823-4F

Claims (5)

[Claims] 1. An outer surface of a cast product, which is made of powdered graphite and a plastic material for adhering the powdered graphite to each other, is attached to at least a part of the inner surface of the cavity of the casting mold, and is cast by the casting mold. Mold for outer surface molding. 2. The molding die according to claim 1, wherein the weight ratio of the plastic component and the graphite component is in the range of 90:10 to 10:90. 3. The molding die according to claim 1, comprising a step of kneading the powdery graphite and the plastic material while heating, and a step of injecting the kneaded powdery graphite and the plastic material into an injection mold. Method of manufacturing. 4. A step of mounting a molding die for outer surface molding according to claim 1 on an inner surface of a cavity of a casting die, and a step of injecting molten metal into the cavity of the casting die to form a cast product, Use a mold for outer surface molding that consists of the steps of removing the cast product and mold from the casting mold, and immersing the cast product and mold in a solvent to dissolve the mold and remove it from the cast product. Had a casting method. 5. The method further comprising the step of heating the cast product and the forming die before melting the cast product and the forming die in a solvent to melt and remove the plastic component of the forming die. 4. The casting method according to 4.