JPH09277014A - Production of light alloy die cast product using resin core and hollow light alloy die cast product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cast a product without any trouble on the quality and to transfer a die to next shot without any trouble. SOLUTION: In a light alloy die casting producing method using a resin core, core print parts 4a of the resin core 4 are held and fixed with casting dies 1, 2, 3 and molten metal is poured into a cavity between the inner surface of the dies 1, 2, 3 and the outer surface of the resin core 4 to cast the product 5. Recessed parts 1a, 2a, 3a are formed on at least one side of the inner surfaces of the dies 1, 2, 3 and the outer surface of the resin core 4 so that projecting parts 5a surrounding the outer surface of a product corresponding part 4c of the core print parts 4a of the resin core 4 is formed to the product 5 to cast the product 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light alloy die casting manufacturing method using a resin core and a light alloy die casting product.

[0002]

The light alloy die casting method is well known as a method capable of mass-producing inexpensive aluminum castings because of its high mass productivity. The surface shape of the die cast casting can be designed quite freely, although there are restrictions due to the structure of the die. However, hollow thin-walled castings having a complicated internal structure have not been manufactured so far because the sand cores used in other casting methods cannot be used. This is because, compared to other casting methods, the pressure applied to the molten metal and the mold during casting is higher in the die-casting method, so in a normal sand core, the sand core is damaged by the high pressure during casting, and as a core, This is because the purpose could not be achieved.

For casting a light alloy die cast product having a complicated shape, a die cast using a resin core molded of a resin such as polycarbonate as a core material that can withstand high pressure during die casting and is inexpensive and reproducible. Technology is being developed. However, when the resin core comes into contact with a high-temperature molten metal, the surface temperature of the resin core rises and softens, so that there is a problem that the molten resin adheres to a product or a mold. That is, the resin core is set in the die-casting mold, the molten metal of the light alloy is poured, and after the curing is completed, the mold is opened and the cast product is taken out, but the resin core exudes during the curing, or It was found that the resin core melts out when opened.

This phenomenon will be described with reference to FIG. The fixed die 1, the movable die 2 and the sliding die 3 form a die. The resin core 4 is gripped and fixed by the skirting board portion 4a by these molds 1, 2 and 3, and the outer surface of the product corresponding portion 4c corresponding to the inner surface portion of the product other than the skirting board portion 4a of the resin core 4 is held. The product 5 is cast by injecting the molten metal into the cavity formed between the inner surfaces of the molds 1, 2, and 3. First, the holding time until the poured molten metal solidifies, that is, as a problem during the curing process, the poured light alloy shrinks as it solidifies, and the product 5 and the fixed die 1, the movable die 2, or the sliding die 3 There is a gap between them. As a result, for example, as shown in FIG. 5, the molds 1, 2, 3 and the resin core 4 are
In the part where the three of the product and the product 5 touch the boundary, the mold 1,
A bleeding 4d of the softened resin is generated in the gap between the products 2 and 3 and the product 5. In the product 5, the thicker the thickness of the portion 5b closer to the boundary, that is, the portion 5b closer to the skirting board portion 4a of the resin core 4, the larger the heat capacity of that portion, and the temperature of the resin on the inner surface is cured. It does not slowly decrease or rises. Therefore, molds 1, 2,
The resin bleeding 4d into the gap between the product 3 and the product 5 becomes extremely large.

The resin bleeding 4d adheres to the product 5 to impair the quality of the product 5, and also adheres to the molds 1, 2 and 3. The resin attached to the product 5 can be removed when the resin core 4 is removed. However, molds 1, 2, 3
The resin adhered to can not be easily removed, and it is not possible to move to the next shot without removing the work by interrupting the casting cycle or discarding several times. There was a problem that could not be done. In FIG. 4, the shaded portion of the core 4 indicates the skirting board portion 4a.

Further, as a problem at the time of opening the mold after curing and releasing the product, when the movable die 2 and the sliding die 3 are moved to open the die, and the product 5 is released by the extrusion pin,
Since the space which has been closed by the molds 1, 2 and 3 until then is opened, as shown in FIG. 6, melted-out resin 4e of the softened resin occurs in this opened space.

As shown in FIG. 7, the cast product immediately after being taken out from the casting machine has resin exudation 4d and melt-out 4e adhered to the portion where the resin core 4 and the product 5 are in contact with each other. There was a risk of causing a problem in the quality of No. 5. The resin attached to the product can be removed to some extent in the subsequent resin core removing step. However, the baseboard portion 4a of the resin core 4
Exuding resin 4 on the molds 1, 2 and 3 that hold the
There is a problem that d and the melted out 4e adhere, and these adhered matters must be removed every time the next shot is started, so that the casting operation cannot be performed steadily. Therefore, an object of the present invention is to provide a light alloy die-casting manufacturing method using a resin core which can cast a product having no problem in quality and can move to the next shot without any problem in the die. To do.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. That is, the core board portion of the resin core is gripped and fixed by a casting mold, and the inner surface of the mold and the resin core are fixed. In a light alloy die casting manufacturing method using a resin core, in which a molten metal is poured into a cavity formed between the outer surface of the child and a product, a product between the baseboard part of the resin core and the product corresponding part A resin core, characterized in that a recess is formed in at least one of the inner surface of the mold and the outer surface of the resin molding so that a protrusion that surrounds the outer surface is formed in the product, and the molding is performed. Is a light alloy die casting manufacturing method using.
Further, in a hollow light alloy die cast product cast by using a resin core, a projecting portion that surrounds the resin core is provided on the outer surface between the baseboard portion and the product corresponding portion of the resin core. It is a hollow light alloy die cast product that is cast using a resin core characterized by the above.

[0009]

Embodiments of the present invention will be described.
FIG. 1 shows an embodiment of a die casting method according to the present invention, in which a fixed die 1, a movable die 2 and a sliding die 3 form a die. The baseboard portion 4a of the resin core 4 is gripped and fixed by these molds 1, 2, and 3, and the outer surface of the product corresponding portion 4c other than the baseboard portion 4a of the resin core 4 and the mold 1,
The product 5 is cast by pouring the molten metal into the cavity between the inner surfaces of the two and three. In this embodiment, however, as shown in detail in FIG. 2, the inner surface of the mold 1, 2, 3 facing the protrusion corresponding portion 4b between the baseboard portion 4a of the resin core 4 and the product corresponding portion 4c. , Shallow recesses 1a, 2a, 3a are formed. As a result, the film-like projecting portion 5a reflecting the recesses 1a, 2a, 3a of the molds 1, 2, 3 is formed on the product 5, and the projecting portion 5a is machined after casting. Removed by.

The casting method according to this embodiment is carried out as described above, and since the projecting portion 5a attached to the product 5 has a small heat capacity, it solidifies in a short time during curing, and further the temperature is prompt after solidification. Fall to. Therefore, the protruding portion 5a
The temperature of the protrusion-corresponding portion 4b of the resin core 4 located on the inner surface of does not rise so much. As a result, even if the temperature of the resin core 4c located on the inner surface of the product 5 other than the projecting portion 5a rises sufficiently high and is melted, this high-temperature molten resin will not melt at a low temperature on the inner surface of the projecting portion 5a. The lid is covered with the unmelted resin 4b.

Therefore, even if the product 5 shrinks during curing and a gap is created between the molds 1, 2, 3 and the product 5,
Hot resin cannot seep into this gap. Similarly, even if the molds 1, 2 and 3 are opened, and further released, the high temperature molten resin is covered by the low temperature unmelted resin located on the inner surface of the protrusion 5a, High temperature resin cannot be melted out. Therefore, according to the casting method of this embodiment, as shown in FIG. 3, the resin does not adhere to the outer surface of the product 5 and the molds 1, 2 and 3, and the resin core 4 is used for casting without trouble. be able to.

In order to cover the high temperature resin with the low temperature resin, it is necessary that the temperature of the resin located on the inner surface of the film-shaped protrusion 5a does not rise so much, so that the temperature of the protrusion 5a of the product is high. Needs to be cooled rapidly. Therefore, in order to further enhance the effect of this embodiment, the protrusion 5a
Is preferably formed so that the thickness thereof decreases toward the tip. More specifically, the length a of the protrusion 5a is 5 to 30 mm, and the thickness b at the base of the protrusion 5a is b.
Is 1 to 2 mm, and the thickness c at the tip of the protrusion 5a is 0.
It is preferably 2 to 1 mm. Length a of protrusion 5a
The reason for setting 5 to 30 mm is that if the length is shorter than 5 mm, the molten resin does not solidify and is melted out from the tip portion, and if longer than 30 mm, extra casting burrs are formed. This is because it melts out from the protrusion 5. further,
The thickness c at the tip of the protruding portion 5a is set to 0.2 to 1 mm because the aluminum does not uniformly rotate on the protruding portion if it is thinner than 0.2 mm, and if the thickness is thicker than 1 mm, the resin is cooled. This is because it is insufficient and melts from the edge. In addition, DASII (secondary dendrite arm spacing) at the end of the cast product
Was measured, the DASII of the 5b portion in contact with the mold 1 at the end of the cast product was 3 to 7 μm, and the DASII of the root portion 5c of the protruding portion at the end was 8 to 14 μm. Further, in the present embodiment, the concave portions 1a, 2a, 3a are formed on the inner surfaces of the molds 1, 2, 3 in order to form the projecting portion 5a on the product 5, but in order to form the projecting portion 5a on the product 5, ,
It is also possible to form a recess on the outer surface of the baseboard portion 4a of the resin core 4 near the product 5.

Another embodiment of the present invention is shown in FIG. FIG.
In the above, since the uneven thickness retaining pins 1b and 2b are respectively projected from the fixed type and the movable type, even if a high pressure is applied at the time of filling the molten metal, the resin core 4 is not deformed and the uneven thickness of the product 5 does not occur.

[0014]

EFFECTS OF THE INVENTION According to the present invention, it is possible to cast a product that does not affect the quality even if a resin core is used, and the die can be moved to the next shot without any problem. The light alloy die casting can be efficiently manufactured.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing a main part of the embodiment.

FIG. 3 is a schematic plan view showing a cast product immediately after casting according to the embodiment.

FIG. 4 is a sectional view showing a conventional example.

FIG. 5 is a cross-sectional view of essential parts showing exudation of resin according to a conventional example.

FIG. 6 is a cross-sectional view of an essential part showing the dissolution of resin according to a conventional example.

FIG. 7 is a schematic plan view showing a cast product immediately after casting according to a conventional example.

FIG. 8 is a sectional view showing one embodiment of the present invention.

[Explanation of symbols]

1 fixed type, 1b eccentricity locking pin, 2 movable type,
3 Sliding type, 1a, 2a, 3a Recessed part, 4 Resin core, 4a Baseboard part, 4b Projected part corresponding part, 4c Product corresponding part, 5 product, 5a Projected part.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigetaka Morita 11 Kinugaoka, Moka City, Tochigi Prefecture Hitachi Metals Co., Ltd.

Claims (16)

[Claims] 1. A resin casting, in which a skirting part of a resin core is gripped and fixed by a casting mold, and a molten metal is injected into a cavity between an inner surface of the mold and an outer surface of the resin core to cast a product. In a light alloy die casting manufacturing method using a core, the inner surface of the mold and the resin core are formed so as to form a protrusion that surrounds the outer surface between the baseboard portion and the product corresponding portion of the resin core. A method for manufacturing a light alloy die casting using a resin core, characterized in that a recess is formed on at least one of the outer surface and casting is performed. 2. The method for producing a light alloy die casting using a resin core according to claim 1, wherein the thickness of the protruding portion is 1/3 or less of the thickness of the main portion of the product. 3. The method for manufacturing a light alloy die cast using a resin core according to claim 1, wherein the thickness of the protrusion is 3 mm or less. 4. The method for manufacturing a light alloy die casting using a resin core according to claim 1, wherein the protrusion is formed so that the thickness thereof decreases toward the tip. . 5. The length of the protrusion is 30 mm or less, and the thickness at the base of the protrusion is 2 mm or less,
The light alloy die casting manufacturing method using a resin core according to any one of claims 1 to 4, wherein the thickness of the tip of the protruding portion is 1 mm or less. 6. The method according to claim 1, wherein one or a plurality of uneven thickness retaining pins are projected and cast from the mold so as to come into contact with the product corresponding portion of the resin core.
A method for manufacturing a light alloy die casting using the resin core according to any one of 1. 7. The uneven thickness prevention pin abuts in the vicinity of an intermediate portion of a product corresponding portion, according to any one of claims 1 to 6.
A method for manufacturing a light alloy die casting using the resin core according to any one of 1. 8. The method for manufacturing a light alloy die casting using a resin core according to claim 7, wherein the uneven thickness locking pin is forcibly cooled by flowing a fluid inside thereof. . 9. The method for manufacturing a light alloy die casting using a resin core according to claim 1, wherein the protrusion is removed after casting. 10. A hollow light alloy die casting product cast using a resin core, wherein a protrusion surrounding the resin core is provided on an outer surface between the baseboard group and the product corresponding part of the resin core. A hollow light alloy die cast product that is cast using a resin core, characterized in that a portion is provided. 11. The wall thickness of the protrusion is ⅓ or less of the wall thickness of the main part of the product.
A hollow light alloy die cast product that is cast using the resin core described in 1. 12. The hollow light alloy die cast product cast using the resin core according to claim 10 or 11, wherein the thickness of the protrusion is 3 mm or less. 13. A hollow light alloy die casting using the resin core according to any one of claims 10 to 12, wherein the protrusion is formed so that the thickness thereof decreases toward the tip. Goods. 14. The protrusion has a length of 30 mm or less, and a thickness of a root portion of the protrusion is 2 mm or less.
11. The thickness at the tip of the protrusion is 1 mm or less.
A hollow light alloy die cast product that is cast using the resin core according to claim 13. 15. The protrusion has a length of 5 to 30 mm, and the protrusion has a root portion with a thickness of 1 to 2 mm.
The hollow light alloy die cast product cast using the resin core according to claim 14, wherein the thickness of the tip of the protrusion is 0.2 to 1 mm. 16. A resin core, wherein DASII at the root of the protrusion is 8 to 14 μm and DASII at the other portion is 3 to 7 μm in the structure of the end of the cast product. Hollow light alloy die cast product that is cast by.