JPH0531761A - Manufacture of engine air suction system part - Google Patents

Abstract

PURPOSE:To manufacture a product of uniform wall thickness even of a three- dimensional shape by using injection molds as a master of a core. CONSTITUTION:Injection molds 11 and 12 for forming the outer shape of an engine air suction system part of three-dimensional shape are formed and a master 16 of a core is formed by using said molds. Skin is peeled off the surface of the master by the wall thickness of a molded product, and a sand mold or a metal mold for the core is manufactured by using the master 16 of the core. Low melting point cores are manufactured by using the mold, which are disposed in the injection molds 11 and 12, and resin is injection molded to form resin layers on the peripheries of mold melting point cores. Then, the cores are released out of the injection molds 11 and 12, and the low melting point cores are melted to manufacture an engine suction system part.

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 or the like through which air for sending into an automobile engine is passed.

[0002]

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

The intake pipe is conventionally made by die casting of an aluminum alloy, but in order to reduce the weight of automobiles in recent years, for example, JP-A-58-82059 is used.
As disclosed in the publication, it has been proposed to make a synthetic resin by injection molding.

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

First, before injection molding, a hollow core made of a low melting point alloy (for example, 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 is made to match the inner surface shape of the synthetic resin intake pipe to be made.

As a method of manufacturing this core, for example, there is a method shown in FIGS. First, a sand mold 1 for a core that bends in a three-dimensional direction and two sand molds 3 and 5 for an outer mold are made by a conventional method.

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

Then, the sand molds 1, 3, 5 are broken and the hollow core is taken out. Next, the hollow core thus formed is placed in a forming die having an inner surface shape that matches the outer surface shape of the intake pipe to be made, and in this forming die, A synthetic resin having a high melting point, for example, nylon 66 containing glass fiber (for example, a melting point of 240 ° C.
The above) is injected and solidified in the gap (cavity) between the inner surface of the mold and the outer surface of the core. The temperature of the molten synthetic resin injected into the cavity is higher than the melting point of the low melting point alloy that constitutes the core, but the temperature is immediately increased by contacting the core with a large heat capacity and good heat transferability. Since the temperature decreases, part of the core is not melted 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 the three-dimensional direction, the core is built in the intake pipe. It will remain as it is.

Therefore, in order to take out the core, the temperature of the synthetic resin and the core taken out from the molding die is 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. It is heated to <240 ° C.) to melt the core made of a low melting point alloy, and the intake pipe made of synthetic resin is removed from the inside.

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

[0012]

However, in the above-mentioned conventional method, the injection mold and the sand mold for the core are manufactured in different steps, and therefore, there are tolerances in the processing steps. However, there is a problem in that the injection mold and the sand mold for the core do not match, and it is difficult to obtain a uniform wall thickness after molding.

As described above, if the thickness is uneven, the pressure resistance and heat resistance are poor, which is not preferable. In addition, there is a problem that a product with a large uneven thickness cannot be used as a product, the yield is poor, and the productivity is poor.

The present invention has been made to solve such conventional problems, and an object thereof is to provide a method of manufacturing an engine intake system component capable of preventing uneven thickness of products. .

[0015]

According to a first aspect of the present invention, an injection molding die for producing an outer shape of a three-dimensional engine intake system component is produced, a master of a core is produced by using the injection die, and molding is performed from the surface thereof. Peel only the thickness of the product, make a core sand mold or mold using this core master, use this to make a low-melting core, place it in the injection mold, Is formed by injection molding to form a resin layer around the low melting point core, and the resin layer is taken out from 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 the outer shape of a three-dimensional engine intake system component is prepared, and a sheet having a thickness corresponding to the thickness of the molded article is attached to the injection molding die. Make a core master, use this gypsum core master to make a sand mold or mold for a core, and then use this to make a low-melting core, which is a sheet equivalent to the thickness of the molded product. Is placed in an injection molding die from which the resin has been removed, a resin is injection-molded to form a resin layer around the low-melting core, the resin layer is taken out from the injection molding die, and the low-melting core is melted.

[0017]

According to the first aspect of the present invention, first, an injection mold for forming the outer shape of the three-dimensional engine intake system component is manufactured,
Next, a core master is made using this injection mold.
Then, the surface of the master of the core is peeled by the thickness of the molded product. This peeling forms the thick part of the product. Then, a sand master or mold for cores is made using the master of the cores that have been peeled from this surface, and a low-melting core is made using the sand mold or sand molds for cores. Next, the low melting point core is placed in an injection molding die, and then a resin is injection molded into the injection molding die to form a resin layer around the low melting point core. After that, the low melting point core having the resin layer formed thereon is taken out from the injection molding die, and the low melting point core is melted.

According to the second aspect of the present invention, first, an injection molding die for forming the outer shape of the engine intake system component having a three-dimensional shape is prepared, and then the inner surface of the injection molding die is equivalent to the thickness of the molded product. , And make a plaster core master using this injection mold. The plaster core master is thinned from the surface by the thickness of the molded product. This thinning forms a thick portion of the product. After that, a sand mold or die for core is made by using the master of the thinned core, and a low-melting core is made by using the sand mold or die for core. Then, the low melting point core is placed in an injection molding die from which a sheet corresponding to the thickness of the molded product is removed, and then a resin is injection-molded in the injection molding die to form a resin layer around the low melting point core. To form. After that, the low melting point core having the resin layer formed thereon is taken out from the injection molding die, and the low melting point core is melted.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 6 show a case of application to a hollow three-dimensional engine intake pipe according to claim 1.

First, as shown in FIG. 1, injection molding dies 11 and 12 for making the outer shape of a three-dimensional engine intake pipe 10 are made based on a design drawing. At the same time, as shown in FIG. 2, the engine intake pipe 1 having a three-dimensional shape is designed based on the design drawing.
The wooden molds 13 and 14 for making the outer shape of 0 are made.

Next, as shown in FIG. 3, this injection molding die 1 is used.
1 and 12 are used to make a gypsum core 15, and then the meat of about 3 mm is stripped from the surface over the entire circumference,
Make the master 16 of the core.

Next, as shown in FIG. 4, sand masters 17 and 18 for cores are made using the master 16 of the core made of gypsum. Next, as shown in FIG. 5, the molding part 1 of the wooden molds 13 and 14
Put sand in 3a and 14a. Then, a wire 19 for taking out sand is embedded in the center of the one wooden mold 14. Wooden pattern 1
An adhesive is applied to the sand-bonding surfaces of the molded parts 13a, 14a of 3,14.

After that, both are put together and bonded. Then, the wooden molds 13 and 14 are removed. Next, a release agent is applied to the molded sand core 20. Next, as shown in FIG. 6, a core 2 for a three-dimensional engine intake pipe made of a low melting point alloy is manufactured by using core sand molds 17 and 18 made from a core master 16.
Make 3.

First, the sand core 20 is replaced with the sand mold 17 for the core.
Set in 18. Then, the melted low melting point alloy is poured from the sprue 21 provided in the core sand mold 17. Leave as it is to solidify the low melting point alloy.

After that, the sand core 20 whose periphery is covered with the low melting point alloy 22 is taken out. Then, the wire 19 embedded in the sand core 20 scrapes out the sand forming the sand core 20.

In this way, the three-dimensional engine intake pipe core 23 made of the low melting point alloy can be obtained. According to a conventional method, the three-dimensional engine intake pipe core 23 made of the low melting point alloy is placed in the injection molding dies 11 and 12 shown in FIG. 1 and then has a melting point higher than that of the low melting point alloy. Injection mold 1 with synthetic resin, for example, nylon 66 containing glass fiber (eg, melting point of 240 ° C. or higher) is injected.
It is solidified in a gap (cavity) between the inner surface of the engine 1 and 12 and the outer surface of the engine intake pipe core 23. The temperature of the molten synthetic resin injected into the cavity is higher than the melting point of the low melting point alloy that constitutes the core, but the temperature is immediately increased by contacting the core with a large heat capacity and good heat transferability. Since the temperature decreases, part of the core is not melted with the injection of the molten synthetic resin.

Then, after the synthetic resin in the injection molds 11 and 12 is solidified, the injection molds 11 and 12 are opened to take out the intake pipe 10. Since the intake pipe 10 is bent in the three-dimensional direction. 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 from the injection molds 11 and 12 and the engine intake pipe core 23 are higher than the melting point of the low melting point alloy and have a melting point of the synthetic resin. The temperature is lowered to a temperature T (for example, 150 ° C. <T <240 ° C.) to melt the core made of the low melting point alloy, and the intake pipe 10 made of synthetic resin is removed from the inside.

As a result, the outer surface shape is the injection molding die 11, 1.
The intake pipe 10 made of synthetic resin having the same inner surface shape as that of No. 2 and the inner surface shape matching the outer surface shape of the engine intake pipe core 23 is obtained.

As described above, according to this embodiment, the injection molding dies 11 and 12 for forming the outer shape of the engine intake pipe 10 having a three-dimensional shape are made, and the injection molding dies 11 and 12 are used. Make Master 16 of the child, Master 1 of this core
From the surface of No. 6, the skin is peeled off by the thickness of the molded product, and the sand masters 17 and 18 for the core are made using the master 16 of the core that is skinned from this surface. To produce the engine intake pipe core 23 made of a low melting point alloy, the engine intake pipe core 23 made of the low melting point alloy is placed in the injection molds 11 and 12, and the resin is injection-molded to make the low melting point alloy core 23. A resin layer is formed around the core 22 for the engine intake pipe,
Since the engine intake pipe core 23 made of the low melting point alloy and having the resin layer is taken out from the injection molding dies 11 and 12, and the low melting point alloy is melted, the injection molding dies 11 and 12 and the low melting point are formed as in the conventional method. Compared to the case where the alloy sand molds 17 and 18 for engine intake pipe cores are manufactured in a separate process, the error is significantly reduced, and the resin layer formed by injection molding can have a uniform thickness. Becomes

Further, the gypsum core master 16 is obtained by peeling off meat of about 3 mm over the entire surface of the gypsum core 15 made directly from the injection molds 11, 12. The master 16 made of gypsum has the following advantages.

That is, since the injection molds 11 and 12 are directly manufactured, the shape conforms to the design specifications. Moreover, since the stripped off meat of about 3 mm corresponds to the resin layer to be covered in the subsequent step, the sand molds 17 and 18 made of the plaster core master 16 correspond to the resin layer. It will include the wall thickness. 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 in which the thickness corresponding to the resin layer is removed. As a result, when the resin layer is formed after being set in the injection molding dies 11 and 12, the shape of the resin layer has a wall thickness conforming to the design specifications.

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

7 to 11 show a case where the invention is applied to a hollow three-dimensional engine intake pipe according to claim 2. Also in this embodiment, similar to the above embodiment,
First, as shown in FIG. 1, injection molding dies 11 and 12 for making an outer shape of a three-dimensional engine intake pipe 10 are made based on a design drawing.

Next, as shown in FIGS. 7 and 8, the injection molds 11 and 12 are used to make a master 24 of a plaster core shown in FIG. For that purpose, first, as shown in FIG. 7, the forming surfaces 11a and 12a of the injection molds 11 and 12 are formed.
Then, a resin having a low molecular weight is uniformly applied to a thickness of 3 mm to be solidified to form a resin layer 25, or a film having a thickness of 3 mm is attached to form the resin layer 25.

Then, as shown in FIG. 8, both injection molding dies 1
After assembling 1, 12, pour high-grade plaster inside,
It is solidified to obtain a gypsum core master 24. Both injection molds 11 and 12 are used as injection molds after the resin layer 25 on the forming surfaces 11a and 12a is peeled off.

Next, as shown in FIG. 9, a three-dimensional engine intake pipe core 31 made of a low-melting point alloy shown in FIG. 11 is produced by using the gypsum core master 24. For that purpose, as shown in FIG. 10, first, using the master 24 of the plaster core, in the same manner as in FIG.
Make 27.

The sand mold 26 for the core made as described above is provided with the sprue 28 and the gas vent hole 29. After assembling the sand molds 26, 27 for both cores, the melted low melting point alloy is poured from the sprue 28. Leave as it is to solidify the low melting point alloy.

After cooling, the core sand molds 26, 27 are destroyed to obtain a three-dimensional engine intake pipe core 31 made of a low melting point alloy. According to a conventional method, the three-dimensional engine intake pipe core 31 made of the low melting point alloy is placed in the injection molds 11 and 12 shown in FIG. 1 and has a melting point higher than that of the low melting point alloy according to a conventional method. A synthetic resin, for example, nylon 66 containing glass fiber (for example, a melting point of 240 ° C. or higher) is injected, and an injection molding die 11,
It is solidified in the gap (cavity) between the inner surface of 12 and the outer surface of the engine intake pipe core 29. The temperature of the molten synthetic resin injected into the cavity is higher than the melting point of the low melting point alloy that constitutes the core, but the temperature is immediately increased by contacting the core with a large heat capacity and good heat transferability. Since the temperature decreases, part of the core is not melted 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 to take out the intake pipe 10. Since the intake pipe 10 is bent in the three-dimensional direction. 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 from the injection molds 11 and 12 and the engine intake pipe core 31 are higher than the melting point of the low melting point alloy, and the melting point of the synthetic resin. The temperature is lowered to a temperature T (for example, 150 ° C. <T <240 ° C.) to melt the core made of the low melting point alloy, and the intake pipe 10 made of synthetic resin is removed from the inside.

As a result, the outer surface shape is the injection mold 11,1.
The intake pipe 10 made of synthetic resin having the inner surface shape of No. 2 and the inner surface shape that 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 made, and the injection molds 11 and 12 are used to make the plaster. A core 24 made of a core made of gypsum is made, sand molds 26, 27 for a core are made by using the master 24 made of a plaster, and an engine intake made of a low melting point alloy is made by using the sand molds 26, 27 for a core. The core 31 for the engine intake pipe made of the low melting point alloy is placed in the injection molds 11 and 12, and the resin is injection molded to surround the core 31 for the engine intake pipe made of the low melting point alloy. A resin layer is formed on the core, and the engine intake pipe core 31 made of a low melting point alloy and having the resin layer formed is taken out from the injection molding dies 11 and 12, and the low melting point alloy is melted. Molds 11 and 12 and low melting point alloy engine 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 also used.
However, when the master 24 of the gypsum core is made, the resin layer 25 is formed on the inner surface, and when the resin layer is formed on the surface of the engine intake pipe core 31 made of a low melting point alloy, the inner surface is formed. The resin layer 25 formed in the above is removed and used. That is, one set of injection molding dies 11 and 12 can be used for two purposes, one for core molding and the other for resin layer molding.

Further, in the gypsum core master 24,
It is possible to make the sand molds 26 and 27 any number of times. still,
Although the sand molds 26 and 27 are made using the plaster core master 24 in the above embodiment, a mold may be made instead of the sand molds 26 and 27.

[0046]

As described above, according to the present invention, since the injection molding die is used as the master of the core, a molded product having a uniform thickness can be obtained even if it has a three-dimensional shape. In addition, it is no longer necessary to separately manufacture the injection mold and the sand mold.

[Brief description of drawings]

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

FIG. 2 is an explanatory view showing a process of making a wooden mold according to an embodiment of claim 1;

FIG. 3 is an explanatory view showing a step of producing a plaster core according to an embodiment of claim 1.

FIG. 4 is an explanatory view showing a step of making a sand mold from a plaster core according to an embodiment of claim 1.

FIG. 5 is an explanatory view showing a process of making sand products according to an embodiment of claim 1.

FIG. 6 is an explanatory view showing a step of producing a core made of a low melting point alloy according to an embodiment of claim 1;

FIG. 7 is an explanatory diagram showing a pre-process for making a master of a plaster core according to an embodiment of claim 2;

FIG. 8 is an explanatory view showing a process of making a plaster core according to an embodiment of the present invention.

9 is a perspective view showing a master of a gypsum core obtained in the step of FIG. 7. FIG.

FIG. 10 is an explanatory diagram showing a process of making a three-dimensional engine intake pipe core made of a low melting point alloy using the gypsum core master shown in FIG.

11 is a perspective view showing a three-dimensional engine intake pipe core made of a low melting point alloy obtained in the step of FIG. 5. FIG.

FIG. 12 is an explanatory view showing a process of making a core by a conventional method.

13 is a cross-sectional view of FIG.

[Explanation of symbols]

10 engine intake pipe 11,12 Injection mold 16,24 Gypsum core master 17, 18, 26, 27 Sand type for cores 23,31 Low melting point alloy core

Claims (2)

[Claims] 1. An injection molding die (11, 12) for forming an outer shape of a three-dimensional engine intake system part is produced, and a core master (16) is made by using the injection molding die (11), and a molding product is formed from the surface thereof. Peel only the thickness of the
6) is used to make a sand mold or core (18, 19) for a core, and a low-melting core (22) is made by using this, and the core is placed in an injection molding die (11, 12). Is formed by injection molding to form a resin layer around the low melting point core (22), and the resin layer is taken out from the injection molding die (11, 12) to obtain the low melting point core (2).
2. A method for manufacturing an engine intake system component, which comprises melting 2). 2. An injection molding die (11, 12) for making an external shape of a three-dimensional engine intake system component is prepared, and a sheet (23) corresponding to the thickness of the molded article is attached to this injection molding die (11, 12). A gypsum core master (24) is made by using the plaster core master (24) and a sand mold or core (25, 26) for the core is made by using the plaster core master (24). A core (29) is prepared, and the core (29) is placed in an injection molding die (11, 12) from which a sheet (23) corresponding to the thickness of a molded product is removed, and a resin is injection-molded to form a low melting core (29). ) Is formed around the resin layer, the resin layer is taken out from the injection mold (11, 12), and the low-melting core (29) is melted.