JP2004174602A - Method of producing hollow casting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means of producing a casting with a hollow part formed of a smooth wall part without increasing an environmental load in a production process. <P>SOLUTION: In the method of producing a hollow casting, after casting and molding by pouring molten metal into a mold, treatment for removing the remainder on the surface of a wall part forming the hollow part and treatment for smoothening the surface of the wall part forming the hollow part are simultaneously performed preferably by pouring a smoothening material into the hollow part and swinging the casting. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a casting having a hollow portion formed by a wall.
[0002]
2. Description of the Related Art When a molded body having a space inside (ie, having a hollow portion) like a gutter-like body or a pipe is manufactured by a simple casting method, in addition to a main mold, a mold is used. A core is used to create the hollow.
For example, to obtain a hollow casting 30 shown in FIG. 3, a mold 20 shown in FIG. 2 (perspective view) and FIG. 6 (cross-sectional view) can be used. The mold 20 includes an upper mold 21 and a lower mold 22 formed by sand casting and a core 23 made of sand, and a cavity 29 corresponding to the hollow casting 30 is formed.
In general, after a molten metal is poured into a cavity 29 and solidified, a hollow casting 30 can be obtained by collapsing the upper mold 21, the lower mold 22 and the core 23. Here, as the core 23, for example, a material obtained by solidifying sand or the like with a thermosetting resin as a binder to form a desired shape is used. However, when the shape of the hollow casting is more complicated, there is a problem to be solved that the production of the core and the removal after the casting are troublesome and the environmental load is high.
Hereinafter, as a hollow casting having a more complicated shape, an intake manifold, which is one of the ventilation system parts for vehicles, will be described as an example, and its problems will be described (refer to Patent Document 1 as a prior art document regarding the intake manifold). ). The intake manifold is an air supply pipe formed by using, for example, an aluminum alloy as a main raw material and supplying air to each cylinder of the engine.
FIG. 4 is a perspective view showing an example of an intake manifold. The intake manifold 40 is a supply pipe for a four-cylinder engine formed by dividing four branch pipes 49 connected to each intake port of a cylinder of the engine from the surge tank 48. In the intake manifold 40, in order to improve the suction efficiency of the mixed gas (gasoline and air, etc.) as viewed from the engine, the surface of the wall with respect to the hollow portion 46 is reduced so that the ventilation resistance in the hollow portion 46 is reduced. Is required to be smooth. In order to respond to this, conventionally, a core having a smooth surface has been used in casting the intake manifold.
However, in order to smooth the surface of the core, it is necessary to perform processing such as molding using sand or the like having a small particle size and applying a mold wash to the surface. Cores with a mold wash applied on the surface make it difficult for gas generated from the resin that solidifies sand, etc. to escape, and it is necessary to make the core as thin as possible and to make the core as hollow as possible. Cracks are easily formed on the surface during handling. In an intake manifold manufactured using a core having a crack on the surface, molten metal is inserted into the crack, and burrs are generated on the surface of the wall with respect to the hollow portion 46, and the surface is rather roughened. Therefore, there is a certain limit in the smoothness of the surface of the core, and there is also a limit in smoothing the surface of the wall with respect to the hollow portion of the intake manifold.
In the case of a hollow casting having a shape like the intake manifold 40, since the hollow portion is bent, merged, and dispersed, a part of the hollow portion remains in the hollow portion when the core is removed. easy. Therefore, it is necessary to remove the core once by breaking the core once by giving an impact to the hollow casting or sand baking or the like, performing an appearance finish or the like, and then removing the remaining core sand again. At that time, since core sand cannot be completely removed by simple shot blasting, conventionally, silica sand or beads are often removed by a honing finish or the like which is projected at a predetermined pressure (core sand removal method). (See Patent Document 2 as a prior art document of the above).
However, the initial equipment cost and operating cost of the compressor and the dust collector for performing honing and the like are increased, and in addition, it is necessary to dispose of the fine powder generated from the removed core sand and the honing material. . Furthermore, when performing cutting work in a later step, if there is a residue such as core sand, the cutting oil will be contaminated and the cutting machine blade will be damaged, and the frequency of replacement will be shortened, resulting in an increase in waste. I was
[0010]
[Patent Document 1]
JP-A-5-149204 [Patent Document 2]
JP-A-7-308751
As described above, the conventional problems have been described by exemplifying an intake manifold as a hollow casting. However, the present invention has been made in view of these problems. It is an object of the present invention to provide a means for producing a casting having a formed hollow portion and having a smooth wall portion forming the hollow portion without increasing an environmental load in a manufacturing process.
The conventional manufacturing method including the step of removing the core after casting was reviewed and studied repeatedly, and as a result, it was found that the above-mentioned object was achieved by the following means.
[0013]
That is, according to the present invention, there is provided a method for producing a casting having a hollow portion formed by a wall portion, the method comprising: casting a molten metal into a mold; There is provided a method for manufacturing a hollow casting, wherein a process of removing a residue on a surface of a wall portion forming a hollow portion and a process of smoothing a surface of a wall portion forming a hollow portion are simultaneously performed.
In the present invention, it is preferable to include a step of introducing a smoothing material into a hollow portion formed by the wall portion and swinging the casting after the casting. In other words, by throwing the smoothing material into the hollow portion and swinging the casting, the above-described removal of the residue and the smoothing of the surface of the wall forming the hollow portion can be realized.
In the present invention, it is preferable to use cast iron or a light alloy for casting as a main raw material of the molten metal.
According to the present invention, any one of the components selected from the group of vehicle ventilation system components including the intake manifold, the turbine housing, the compressor cover, the cylinder head, and the air duct manufactured by the above method for manufacturing a hollow casting. Provided.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the method for producing a hollow casting of the present invention will be described in detail, but the present invention should not be construed as being limited to the following description, and the scope of the present invention is not limited thereto. Various changes, modifications, and improvements can be made based on the knowledge of those skilled in the art without departing from the scope of the present invention.
The method for producing a hollow casting of the present invention is a method for producing a casting having a hollow portion formed by a wall portion by using a mold as a main mold and a sand mold as a core. The casting method does not limit the means, and includes a so-called die-casting method (high-speed injection) and a low-pressure casting method (low-speed injection), in which a molten metal (molten metal) is injected into a mold having a cavity having a predetermined shape and molded. Any method can be used. In the method for manufacturing a hollow casting according to the present invention, after casting and molding using a main mold and a sand core, the core is removed, and a wall portion forming a hollow portion (also referred to as a hollow casting inner surface) is removed. The feature is that the smoothing process is performed simultaneously.
As shown in FIG. 1, the method for producing a hollow casting according to the present invention includes, for example, a casting step 1, an external finishing step 2, and an inner finishing step 3. The outline of the manufacturing method including these steps is as follows.
First, a predetermined material is prepared as a raw material, melted to form a molten metal, and then subjected to a cleaning treatment as required. Then, the molten metal is poured into a mold and molded by cooling or the like (casting process 1). Next, burrs and the like generated on the obtained molded body (hollow casting) are removed and the outer shape is adjusted (appearance finishing step 2). Next, the core is broken and removed as much as possible. Then, a smoothing material composed of, for example, a metal ball and a cut wire is charged into the hollow portion of the hollow casting and shaken to remove the remaining sand and residue and to smooth the inner surface (inner surface finishing step 3). . Thereafter, heat treatment or the like may be performed as necessary to improve the mechanical properties of the hollow casting.
Hereinafter, the inner surface finishing step 3 will be described in detail. A smoothing material having a hardness suitable for the material forming the hollow casting is charged into the hollow formed by the wall, the opening is closed, and the hollow casting is rocked. Then, the smoothing material repeatedly collides with the inner surface of the hollow casting to peel off sand and residue remaining from the casting surface, and the smoothing material deforms the inner surface of the hollow casting by polishing or slightly crushing by sliding. And improve the smoothness of the inner surface of the hollow casting.
As the smoothing material, it is preferable to include a metal sphere (including a porous body) which is at least larger (smaller than the diameter of the hollow portion) or a cut wire smaller than the metal sphere. A metal ball or a cut wire may be used alone, or a mixture of two or more metal particles, abrasives or abrasives, dry sand, or the like may be used. More preferably, it is a mixture containing at least larger metal spheres. It is also preferable to use metal balls of different sizes. When smoothing materials having different sizes are mixed, the smoothing materials repeatedly collide with the inner surface of the hollow casting without leaking more uniformly, and the residue is easily removed. Further, when large metal spheres are mixed, the inner surface of the hollow casting is smoothened by being pressurized by the mixture.
The diameter of the metal sphere or the length of the cut wire, or the material forming the metal sphere or the cut wire may be determined in consideration of the raw material of the hollow casting, the sectional area of the hollow portion of the hollow casting, and the like. , But is not limited. For example, in the case of a ventilation system part for a vehicle in which the hollow casting is made of an aluminum alloy, a steel ball or a stainless steel ball of φ10 to 20 mm and a stainless steel of φ0.6 to 1.2 mm × length 0.6 to 1.2 mm are used. A cut wire made of a material can be preferably used.
The above-mentioned smoothing material is preferably introduced so as to have a volume of about 5 to 70% with respect to the volume of the hollow portion of the hollow casting. This is to ensure that the smoothing material moves freely in the hollow portion and that the number of collisions between the smoothing material and the inner surface of the hollow casting is ensured.
According to the method of manufacturing a hollow casting of the present invention described above, in order to remove the residual material, a honing treatment or the like is not performed as a separate step as in the related art, and the core is completely removed and the inner surface is removed. Is performed at the same time, the manufacturing process is shortened, and a compressor and a dust collector used for honing processing and the like are not required. In addition, since the fine powder generated by the honing process etc. does not adhere to the hollow part, it is difficult to contaminate the cutting oil or damage the blade of the cutting machine at the cutting process in the later process, and to generate waste. Suppress.
The present invention eliminates the need for a compressor and a dust collector, reduces the amount of energy used leading to the consumption of carbon dioxide, makes it difficult to contaminate the cutting oil, and prolongs the life of the cutting machine blade, thereby suppressing the generation of waste. It is useful regardless of the type of hollow casting to be produced in that it is a means of reducing environmental load.
Particularly, as a suitable use of the hollow casting produced by the present invention, a ventilation system part for a vehicle can be mentioned. The vehicle ventilation system components are components of a system that supplies air or a mixed gas of fuel and air up to an engine cylinder, and include, for example, an intake manifold, a turbine housing, a compressor cover, a cylinder head (a port for supply and exhaust). ), Air duct, etc. Since the method for producing a hollow casting of the present invention removes the residue from the hollow portion of the obtained hollow casting and smoothes the wall forming the hollow portion, the passage resistance of the fluid is reduced and the fluid is contaminated. It is suitable for these ventilation parts for vehicles.
Hereinafter, the vehicle ventilation system components will be described. FIG. 5 is a sectional view centering on the cylinder head of the engine. A cylinder head 52 having an intake port 54 and an exhaust port 55 is provided on a cylinder 51 in which a piston moves up and down, and further, an intake manifold 53 is connected. For example, the air filtered by an air cleaner (not shown) passes through the intake manifold 53 and is mixed with fuel by a fuel injection device or the like (not shown) to form a mixed gas. The mixed gas is supplied into the cylinder 51 by the opening operation of the intake valve via the intake port 54 of the cylinder head 52, and is burned by a spark plug (not shown). The air duct is an air supply pipe connecting the air cleaner and the intake manifold. The turbine housing is a vane chamber for converting exhaust gas into rotational power in an automobile equipped with a turbocharger. The compressor cover is an impeller chamber for pumping the intake gas.
Next, in the method for producing a hollow casting of the present invention, it is preferable to use cast iron or a light alloy for casting as a main raw material of a molten metal. The type of cast iron is not limited, but it is preferable to use spheroidal graphite cast iron having more excellent mechanical properties. Among the light alloys for casting, there are various types of aluminum alloys for casting depending on the presence or absence of heat treatment, contained other elements and their composition ratios, etc., but the type is not limited. It is preferable to use those specified by JIS symbol AC or the like according to Japanese Industrial Standards, and examples thereof include AC4C and AC3A.
[0030]
As described above, according to the present invention, the core can be removed while also performing the smoothing without using the conventional means such as the honing process and the like, and the surface is particularly smoothed. A hollow casting having a smooth wall surface can be obtained without using a core. Accordingly, the core can be manufactured at a lower cost, and the resulting hollow casting is less likely to cause problems such as generation of burrs derived from the core. Further, equipment and operating costs for honing processing and the like can be reduced, and the manufacturing process can be shortened. Furthermore, since the smoothing material can be repeatedly used and the frequency of replacement of the cutting oil and the blade of the cutting machine is increased in a later step, the amount of waste generated is reduced. And through these effects, it can contribute to reduction of environmental load.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a method for producing a hollow casting of the present invention, and is a block flow diagram of steps.
FIG. 2 is a transparent perspective view showing an example of a mold for a hollow casting.
FIG. 3 is a transparent perspective view showing an example of a hollow casting.
FIG. 4 is a perspective view showing an embodiment of an intake manifold which is an example of a hollow casting.
FIG. 5 is a cross-sectional view showing an embodiment of a cylinder head and an intake manifold as an example of a hollow casting.
FIG. 6 is a sectional view of the mold shown in FIG. 2;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Casting process, 2 ... Exterior finishing process, 3 ... Inner surface finishing process, 20 ... Mold, 21 ... Upper mold, 22 ... Lower mold, 23 ... Core, 24 ... Main mold, 29 ... Cavity, 30 ... Hollow casting, 35 ... wall part, 36 ... hollow part, 40, 53 ... intake manifold, 45 ... wall part, 46 ... hollow part, 48 ... surge tank, 49 ... branch pipe, 51 ... cylinder, 52 ... cylinder head, 54 ... intake port , 55 ... exhaust port.

Claims (4)

A method for producing a casting having a hollow portion formed by a wall portion, wherein after casting a melt by injecting a molten metal into a mold, a process of removing a residue on the surface of the wall portion forming the hollow portion and And a process of smoothing the surface of the wall forming the hollow portion at the same time. The method for producing a hollow casting according to claim 1, further comprising, after the casting, a step of introducing a smoothing material into a hollow portion formed by the wall portion to swing the casting. The method for producing a hollow casting according to claim 1, wherein a main raw material of the molten metal is cast iron or a light alloy for casting. Any one selected from the group of vehicle ventilation system components including an intake manifold, a turbine housing, a compressor cover, a cylinder head, and an air duct produced by the method for manufacturing a hollow casting according to any one of claims 1 to 3. 1 part.

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