JP3308565B2 - Manufacturing method of engine intake system parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an engine intake system component, and more particularly, to a method of manufacturing a synthetic resin intake pipe through which air is fed to an automobile engine.

[0002]

2. Description of the Related Art Air to be supplied to an automobile engine is taken from an air cleaner, passes through a duct and an intake pipe, and is supplied with gasoline supplied by a fuel injection device or a carburetor provided at a downstream end of the intake pipe. After being mixed, it passes through an intake manifold and is fed into a cylinder of an automobile engine.

Conventionally, the above-mentioned intake pipe has been made by die-casting of an aluminum alloy. However, in order to reduce the weight of automobiles in recent years, for example, Japanese Patent Application Laid-Open No. 58-82059.
As disclosed in Japanese Patent Application Laid-Open Publication No. H11-264, it has been proposed to produce a synthetic resin by injection molding.

On the other hand, since the intake pipe is hollow and the outer and inner surfaces are bent in a three-dimensional direction, it cannot be produced by an injection molding apparatus having a simple split mold as is generally used. Therefore, when an intake pipe having a shape bent in a three-dimensional direction is manufactured by injection molding of a synthetic resin, it is performed as follows.

First, prior to injection molding, a hollow core made of a low melting point alloy (for example, having a melting point of 130 ° C. to 150 ° C.) such as an alloy of Bi and Sn or an alloy of Bi, Sn and Pb is used. prepare. The outer surface shape of this core matches the inner surface shape of the synthetic resin intake pipe to be made.

As a method of manufacturing this core, for example,
There is shown in 10 and 11. First, a sand mold 1 for a core bent in a three-dimensional direction and two sand molds 3 and 5 for an outer mold are formed according to a conventional method.

Next, after the three-dimensional core sand mold 1 is disposed in the two outer mold sand molds 3 and 5, both ends of the core sand mold 1 are fixed. Then, the melted low melting point alloy is injected into a gap (cavity) 7 between the wall surfaces 4, 6 of the two outer mold sand molds 3, 5 and the wall surface 2 of the three-dimensional core sand mold 1, A low melting point alloy layer 8 is formed around the wall 2 of the three-dimensional core sand mold 1.

Thereafter, the sand molds 1, 3, and 5 are broken, and the hollow core is taken out. Next, in a state where the thus formed hollow core is disposed in a molding die having an inner surface shape that matches the outer surface shape of the intake pipe to be made, in this molding die, the lower than the low melting point alloy. Synthetic resin having a high melting point, for example, nylon 66 containing glass fiber (for example, having a melting point of 240 ° C.)
Above) and solidified in the gap (cavity) between the inner surface of the mold and the outer surface of the core. Although the temperature of the molten synthetic resin injected into the cavity is higher than the melting point of the low melting point alloy constituting the core, the temperature is immediately increased by contacting the core with a large heat capacity and good heat transfer. Since the core is lowered, a part of the core does not melt with the injection of the molten synthetic resin.

After the synthetic resin in the mold is solidified, the mold is opened and the intake pipe is taken out. Since the intake pipe is bent in a three-dimensional direction, the core is built in the intake pipe. It is in the state of being left.

Therefore, in order to remove the core, the synthetic resin and the core taken out of the mold are subjected to a temperature T higher than the melting point of the low melting point alloy and lower than the melting point of the synthetic resin (for example, 150 ° C. <T). <240 ° C.) to melt the low-melting alloy core, and remove the synthetic resin intake pipe from the inside.

As a result, an intake pipe made of synthetic resin whose outer surface shape matches the inner surface shape of the mold and whose inner surface shape matches the outer surface shape of the core is obtained.

[0012]

However, in the above-described conventional method, the injection mold and the core sand mold are manufactured in separate steps, and therefore, each has a different tolerance in the processing steps. This causes a problem that the injection mold and the core sand mold do not match, and it is difficult to obtain a uniform thickness after molding.

As described above, if the thickness is uneven, the pressure resistance and heat resistance are poor, which is not preferable. Further, there is a problem that a material having a large uneven thickness cannot be used as a product, has a low yield, and lacks productivity.

SUMMARY OF THE INVENTION The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide a method of manufacturing an engine intake system component capable of preventing uneven thickness of a product. .

[0015]

A first aspect of the present invention is to form an injection mold for forming an external shape of a three-dimensional engine intake system component, use the mold to form a core master, and mold the core from its surface. Peel only the thickness of the product, make a core sand mold or mold using this core master, make a low-melting core using this, place it in the injection mold, Is formed by injection molding to form a resin layer around the low melting point core, which is taken out of the injection molding die, and the low melting point core is melted.

According to a second aspect of the present invention, an injection molding die for forming an external shape of a three-dimensional engine intake system part is formed, a sheet corresponding to the thickness of the molded product is affixed to the injection molding die, and a plaster made of gypsum is used. Make a core master, use this plaster core master to make a core sand mold or mold, use this to make a low-melting core, and use this as a sheet equivalent to the wall thickness of the molded product Is placed in an injection molding die from which the resin has been removed, and a resin layer is formed around the low melting point core by injection molding of the resin, taken out of the injection molding die, and the low melting point core is melted.

[0017]

According to the first aspect of the present invention, first, an injection mold for forming an external shape of a three-dimensional engine intake system component is formed,
Next, a core master is made using this injection mold.
Then, the surface of the core master is peeled by the thickness of the molded product. This stripping technique to form a thick portion of the product. Thereafter, a core sand mold or die is made using the core master whose skin has been peeled off from the surface, and a low-melting core is made using this core sand mold or mold. Next, after disposing the low-melting core in an injection mold, a resin is injection-molded in the injection mold to form a resin layer around the low-melting core. Thereafter, the low-melting core having the resin layer formed thereon is removed from the injection mold, and the low-melting core is melted.

According to a second aspect of the present invention, first, an injection mold for forming an outer shape of a three-dimensional engine intake system part is formed, and then an inner surface of the injection mold corresponds to a thickness of the molded product. And a plaster core master is made using this injection mold. The gypsum core master is made thin from the surface by the thickness of the molded article. This thinning forms a thick part of the product. Thereafter, a core sand mold or a mold is made using the thinned core master, and a low-melting core is made using the core sand mold or the mold. Next, after disposing the low-melting core in an injection molding die from which a sheet corresponding to the thickness of the molded product has been removed, a resin is injected into the injection molding die to form a resin layer around the low-melting core. To form Thereafter, the low-melting core having the resin layer formed thereon is removed from the injection mold, and the low-melting core is melted.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 to 4 show a case where the present invention is applied to a hollow three-dimensional engine intake pipe according to the first aspect.

First, as shown in FIG. 1, injection molds 11 and 12 for forming an outer shape of a three-dimensional engine intake pipe 10 are made based on a design drawing.

Next, as shown in FIG. 2, the injection mold 1
A plaster core 15 is made using 1, 12 and thereafter, about 3 mm of meat is peeled off from the surface over the entire circumference,
Make the master 16 of the core.

Next, as shown in FIG. 3 , sand molds 17 and 18 for cores are made using the gypsum core master 16.

Next, as shown in FIG. 4 , a three-dimensional engine intake pipe core 23 made of a low melting point alloy is manufactured by using core sand molds 17 and 18 made from a core master 16.

First, a sand core 2 made by a conventional method is used.
0 is set in the core sand molds 17 and 18. Then, the molten low melting point alloy is poured from the gate 21 provided in the core sand mold 17. Leave as it is to solidify the low melting point alloy.

Thereafter, the sand core 20 whose periphery is covered with the low melting point alloy 22 is taken out. Then, the sand forming the sand core 20 is scraped out by the wire 19 buried in the sand core 20.

Thus, a three-dimensional engine intake pipe core 23 made of a low melting point alloy can be obtained. In the following, after the low-melting alloy three-dimensional engine intake pipe core 23 is disposed in the injection molds 11 and 12 shown in FIG. 1 according to a conventional method, the core 23 has a higher melting point than the low-melting alloy. A synthetic resin, for example, nylon 66 (for example, having a melting point of 240 ° C. or more) containing glass fibers is injected, and an injection mold 1 is formed.
It is solidified in a gap (cavity) between the inner surfaces of the cores 1 and 12 and the outer surface of the engine intake pipe core 23. Although the temperature of the molten synthetic resin injected into the cavity is higher than the melting point of the low melting point alloy constituting the core, the temperature is immediately increased by contacting the core with a large heat capacity and good heat transfer. Since the core is lowered, a part of the core does not melt with the injection of the molten synthetic resin.

After the synthetic resin in the injection molds 11 and 12 is solidified, the injection molds 11 and 12 are opened and the intake pipe 10 is taken out. Since the intake pipe 10 is bent in a three-dimensional direction. Thus, the engine intake pipe core 23 remains in the intake pipe 10.

Therefore, in order to take out the engine intake pipe core 23, the synthetic resin taken out of the injection molds 11 and 12 and the engine intake pipe core 23 must be separated from each other by a temperature higher than the melting point of the low melting point alloy. By heating to a lower temperature T (for example, 150 ° C. <T <240 ° C.), the core made of the low melting point alloy is melted, and the synthetic resin intake pipe 10 is removed from the inside.

As a result, the outer surface of the injection molds 11 and 1
2, the synthetic resin intake pipe 10 whose inner surface shape matches the outer surface shape of the engine intake pipe core 23 is obtained.

As described above, according to the present embodiment, the injection molds 11 and 12 for forming the outer shape of the three-dimensional engine intake pipe 10 are formed, and the injection molds 11 and 12 are used to form the medium. Make a child master 16 and make this child master 1
6 is peeled from the surface of the molded product 6 by the thickness of the molded article, core sand molds 17 and 18 are formed by using the core master 16 whose skin is peeled from the surface, and these core sand molds 17 and 18 are used. Then, a core 23 for an engine intake pipe made of a low-melting-point alloy is prepared, and the core 23 for an engine intake pipe made of a low-melting-point alloy is disposed in the injection molds 11 and 12, and resin is injection-molded to form a low-melting-point alloy. A resin layer is formed around the core 23 for the engine intake pipe,
The core 23 for the engine intake pipe made of the low melting point alloy having the resin layer formed thereon is taken out of the injection molding dies 11 and 12 and the low melting point alloy is melted. Compared with the case where the sand molds 17 and 18 for the engine intake pipe core made of an alloy are manufactured in a separate process, the error is extremely reduced, and the thickness of the resin layer formed by injection molding can be made uniform. Becomes

The gypsum core master 16 is formed by peeling off approximately 3 mm of meat over the entire surface of the gypsum core 15 directly formed from the injection molds 11 and 12. Since the gypsum core master 16 is used, there are the following advantages.

That is, since the injection molding dies 11 and 12 are made directly, the shape conforms to the design specifications. Also, since the stripped-out meat of about 3 mm corresponds to the resin layer to be coated in a later step, the sand molds 17 and 18 made by the gypsum core master 16 correspond to the resin layer. To be included. Therefore, the core 23 for the engine intake pipe made of the low melting point alloy made of the sand molds 17 and 18 has a shape excluding the thickness corresponding to the resin layer. As a result, when this is set in the injection molds 11 and 12, and a resin layer is formed, the resin layer has a thickness conforming to the design specification.

Further, since the gypsum core master 16 is used to make the sand molds 17 and 18, it can be used any number of times. In the above embodiment, a sand mold 17 and a sand mold 17 were used by using a gypsum core master 16.
Although the case of making the mold 18 has been described, a mold may be made instead of the sand molds 17 and 18.

FIGS. 5 to 9 show a case where the present invention is applied to a hollow three-dimensional engine intake pipe according to the second aspect. In this embodiment, similarly to the above embodiment, first, as shown in FIG. 1, an injection mold 1 for forming an outer shape of a three-dimensional engine intake pipe 10 based on a design drawing.
Make 1,12.

Next, as shown in FIGS. 5 and 6 , a gypsum core master 24 shown in FIG. 7 is made using the injection molds 11 and 12. As shown in FIG. For this purpose, first, as shown in FIG. 5 , the forming surfaces 11a and 12a of the injection molds 11 and 12 are formed.
Then, a low-molecular-weight resin is uniformly applied to a thickness of 3 mm to form a solidified resin layer 25, or a 3 mm-thick film is adhered to form the resin layer 25.

[0036] Then, as shown in FIG. 6, both the injection mold 1
After assembling 1,12, pour high-grade plaster inside,
It is solidified to obtain a gypsum core master 24. The two injection molding dies 11 and 12 are used as injection molding dies after the resin layer 25 on the forming surfaces 11a and 12a is peeled off.

Next, as shown in FIG. 7 , using a gypsum core master 24, a three-dimensional engine intake pipe core 31 made of a low melting point alloy shown in FIG. 9 is produced. For this purpose, as shown in FIG. 8, first, the plaster of the core master 2
4 with, in the same manner as in FIG. 3, the core sand mold 26, 27
make.

A gate 28 and a gas vent hole 29 are provided in the core sand mold 26 produced as described above. Then, after assembling the sand molds 26 and 27 for both cores, the molten low melting point alloy is poured from the gate 28. Leave as it is to solidify the low melting point alloy.

After cooling, the core sand molds 26 and 27 are broken to obtain a three-dimensional engine intake pipe core 31 made of a low melting point alloy. In the following, after the low-melting-point alloy three-dimensional engine intake pipe core 31 is placed in the injection molds 11 and 12 shown in FIG. 1 according to a conventional method, it has a higher melting point than the low-melting-point alloy. A synthetic resin, for example, nylon 66 containing glass fiber (for example, having a melting point of 240 ° C. or higher) is injected, and injection molding dies 11 and
12 is solidified in a gap (cavity) between the inner surface of the core 12 and the outer surface of the engine intake pipe core 31 . Although the temperature of the molten synthetic resin injected into the cavity is higher than the melting point of the low melting point alloy constituting the core, the temperature is immediately increased by contacting the core with a large heat capacity and good heat transfer. Since the core is lowered, a part of the core does not melt with the injection of the molten synthetic resin.

After the synthetic resin in the injection molds 11 and 12 is solidified, the injection molds 11 and 12 are opened and the intake pipe 10 is taken out. Since the intake pipe 10 is bent in a three-dimensional direction. Thus, the engine intake pipe core 31 remains in the intake pipe 10.

Therefore, in order to take out the engine intake pipe core 31, the synthetic resin taken out of the injection molding dies 11 and 12 and the engine intake pipe core 31 are made to have a melting point higher than the melting point of the low melting point alloy. By heating to a lower temperature T (for example, 150 ° C. <T <240 ° C.), the core made of the low melting point alloy is melted, and the synthetic resin intake pipe 10 is removed from the inside.

As a result, the outer surface of the injection molding dies 11 and 1
2 is obtained, and the synthetic resin intake pipe 10 whose inner surface shape matches the outer surface shape of the engine intake pipe core 31 is obtained.

As described above, according to this embodiment, the injection molds 11 and 12 for forming the outer shape of the three-dimensional engine intake pipe 10 are formed, and the plasters are formed by using the injection molds 11 and 12. The core 24 made of a low melting point alloy is made using the gypsum core masters 24 and 27, and the sand molds 26 and 27 are formed using the plaster core 24. A pipe core 31 is formed, and the low-melting alloy engine intake pipe core 31 is disposed in the injection molds 11 and 12, and resin is injection-molded to surround the low-melting alloy engine intake pipe core 31. Since the resin layer is formed on the core, the core 31 for the engine intake pipe made of the low melting point alloy having the resin layer formed thereon is taken out of the injection molds 11 and 12 and the low melting point alloy is melted. Molds 11 and 12 and low melting point alloy As compared with the case of producing a sand mold 26, 27 of the core for emission intake pipe in a separate step, very error is reduced, it becomes possible to make uniform the thickness of the resin layer formed by injection molding.

In this embodiment, the injection molds 11 and 12 are used.
However, when the gypsum core master 24 is made, the resin layer 25 is formed on the inner surface and used. On the other hand, when the resin layer is formed on the surface of the low melting point alloy engine intake pipe core 31, the inner surface is formed. The resin layer 25 formed above is used after being removed. That is, one set of the injection molds 11 and 12 can be used for two purposes, namely, for core molding and resin layer molding.

Further, in the gypsum core master 24,
Sand molds 26 and 27 can be made any number of times. still,
In the above embodiment, the case where the sand molds 26 and 27 are formed using the gypsum core master 24 has been described. However, a mold may be formed instead of the sand molds 26 and 27.

[0046]

As described above, according to the present invention, since the injection mold is used as the core master, a molded article having a uniform thickness can be obtained even in a three-dimensional shape. Further, it is no longer necessary to separately manufacture a wooden mold for an injection mold and a wooden mold for a sand mold.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a step of making an injection mold according to an embodiment of the present invention.

FIG. 2 shows a gypsum core according to one embodiment of the present invention.
It is explanatory drawing which shows a process.

FIG. 3 shows a plaster core to sand according to an embodiment of the present invention.
It is explanatory drawing which shows the process of making a type | mold.

FIG. 4 shows a core made of a low melting point alloy according to one embodiment of the present invention.
It is explanatory drawing which shows the process of making.

FIG. 5 shows a gypsum core according to an embodiment of the present invention.
It is explanatory drawing which shows the front process which makes a master.

FIG. 6 shows a plaster core according to one embodiment of the present invention.
It is explanatory drawing which shows the process of making.

FIG. 7 shows the gypsum core obtained in the steps of FIGS. 5 and 6.
It is a perspective view which shows a master.

FIG. 8 shows a low-priced core using the plaster core master shown in FIG . 7;
Making core for engine intake pipe of three-dimensional shape made of melting point alloy
It is explanatory drawing which shows a process.

9 is made of a low melting point alloy obtained in the same manner as in the step of FIG .
FIG. 3 is a perspective view showing a three-dimensionally shaped engine intake pipe core.
You.

FIG. 10 is an explanatory view showing a step of manufacturing a core by a conventional method.
It is.

FIG. 11 is a sectional view of FIG . 10;

[Explanation of symbols]

 Reference Signs List 10 Engine intake pipe 11, 12 Injection mold 16, 24 Gypsum core master 17, 18, 26, 27 Core sand mold 23, 31 Low melting point alloy core

────────────────────────────────────────────────── (5) References JP-A-58-82059 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 45/00-45/84

Claims (2)

(57) [Claims] 1. An injection molding die (11, 12) for forming an external shape of a three-dimensional engine intake system part, and a core master (16) is formed using the injection molding die. Peel only the thickness of this core, this core master (1
6) is used to make a core sand mold or a mold (17, 18), and using this, a low melting point core (23) is made, and this is placed in an injection mold (11, 12). Is injection molded to form a resin layer around the low melting point core (23). The resin layer is taken out of the injection molds (11, 12), and the low melting point core (2 ) is removed.
3) A method for manufacturing an engine intake system component, which comprises: 2. An injection molding die (11, 12) for forming an outer shape of a three-dimensional engine intake system component is prepared, and a sheet (25) corresponding to the thickness of the molded product is affixed thereto. A gypsum core master (24) is made using the gypsum core master (24), and a sand mold or mold (26, 27) for a core is made using the gypsum core master (24), and a low melting point A core (31) is prepared, and the core (31) is placed in an injection mold (11, 12) from which a sheet (25) corresponding to the thickness of a molded product is removed, and a resin is injection-molded to form a low-melting core (31). A) forming a resin layer around it, removing the resin layer from the injection molds (11, 12), and melting the low-melting core (31).