JP2003221639A - Exhaust manifold with built-in turbine housing and its manufacturing process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust manifold with a built-in turbine housing wherein the turbine housing part and the exhaust manifold body part each exhibits an appropriate heat resistance and durability. <P>SOLUTION: The exhaust manifold with a built-in turbine housing is made of globular graphite cast iron, wherein a turbine housing 11 and an exhaust manifold body 12 are formed by integral casting. The turbine housing 11 is cast from a first molten metal for globular graphite cast iron containing 2-3 wt.% C and 2.5-5.3 wt.% Si. The exhaust manifold body 12 is cast from a second molten metal for globular graphite cast iron containing 3.3-4.1 wt.% C and 3.3-4.3 wt.% Si. A boundary part 13 is cast from a mixture of the two molten metals wherein the difference between their Si contents is 0.5-2.0 wt.%. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbine housing integrated exhaust manifold made of spheroidal graphite cast iron in which a turbine housing of a supercharger and an exhaust manifold main body are integrally cast, and a method for manufacturing the exhaust manifold.

[0002]

2. Description of the Related Art Conventionally, an exhaust manifold integrated with a turbine housing of this type is disclosed in, for example, Japanese Patent Laid-Open No. 2000-19.
What is described in 9427 is known. This turbine housing-integrated exhaust manifold is, for example, 2.8-
3.4 wt% C, 3.75-4.5 wt% Si,
0.6% by weight or less of Mn, 0.02% by weight or less of S,
0.08% by weight or less P, 0.030% by weight or more M
g, a high Si spheroidal graphite cast iron composition containing 0.4 to 0.7% by weight of Mo. A turbine housing-integrated exhaust manifold made of such a high Si spheroidal graphite cast iron composition is formed by integrally casting a turbine housing and an exhaust manifold body, and then performing a machining process or the like to remove an excess portion from the cast product. It is manufactured by applying.

[0003]

By the way, the side of the exhaust manifold main body of the turbine housing-integrated exhaust manifold is connected to the cylinder head of the engine and is firmly fixed by bolts or the like. Further, the turbine housing side of the turbine housing integrated exhaust manifold is connected to the center housing of the supercharger (turbocharger) and is fastened by a ring member or the like. Then, the exhaust gas exhausted from the cylinder head of the engine flows from the exhaust manifold main body side of the turbine housing integrated exhaust manifold to the turbine housing side.

Since the turbine housing-integrated exhaust manifold is a component exposed to high temperature exhaust gas (for example, 900 ° C.), its heat resistance and durability must be sufficient. Further, since the exhaust manifold main body side is constrained more strongly than the turbine housing side, in consideration of thermal fatigue life (durability), it is necessary to form the material with a small thermal expansion coefficient. Further, on the turbine housing side, high-temperature exhaust gas flows in from the exhaust manifold body side in a state where the inflow area of the exhaust gas is narrowed, so the flow velocity of the exhaust gas increases and the turbine housing side does not It will be a heavy load. Therefore, further improvement in heat resistance and durability on the turbine housing side is required. Therefore, in the turbine housing-integrated exhaust manifold, the required performance differs between the turbine housing side and the exhaust manifold main body side.

However, the above-described conventional turbine housing-integrated exhaust manifold is formed of one kind of material having a high Si spheroidal graphite cast iron composition, and is formed on the turbine housing side and the exhaust manifold body side. Since the performance of heat resistance and durability are the same,
The turbine housing side and the exhaust manifold body side may not be able to exhibit heat resistance and durability performance suitable for each side.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a turbine housing-integrated exhaust manifold made of spheroidal graphite cast iron in which a turbine housing and an exhaust manifold body are integrally cast. An object of the present invention is to provide a turbine housing integrated exhaust manifold capable of exhibiting heat resistance and durability performance suitable for the housing side and the exhaust manifold main body side, respectively, and a method for manufacturing the exhaust manifold.

[0007]

As a result of earnest studies in view of the above-mentioned circumstances, the inventor of the present invention has found that the turbine housing side and the exhaust manifold main body side of the turbine housing integrated exhaust manifold are made of different materials (spherical). Graphite cast iron) and the difference in Si content between the turbine housing side and the exhaust manifold main body side is 0.5 to 2.0% by weight, or the turbine housing side and the exhaust side The difference in Ni content from the side of the manifold body is 16
It has been found that when the content is up to 36% by weight, heat resistance and durability performance suitable for the turbine housing side and the exhaust manifold main body side can be exhibited, and the spherical graphite of the present invention has been found. A cast iron turbine housing integrated exhaust manifold and a manufacturing method thereof have been completed.

That is, the turbine housing-integrated exhaust manifold according to the first aspect of the present invention is a turbine housing-integrated exhaust manifold made of spheroidal graphite cast iron in which the turbine housing and the exhaust manifold main body are formed by integral casting. 2. The turbine housing cast from a first spheroidal graphite cast iron melt containing C wt.% And 2.5-5.3 wt.% Si; 3.3-4.1 wt.% C; The exhaust manifold body cast from the second molten iron for spheroidal graphite cast iron containing 3 to 4.3% by weight of Si, and the two molten metals having a difference in Si content of 0.5 to 2.0% by weight. The gist is that it consists of a boundary part that is mixed and cast.

Here, in the first molten iron for spheroidal graphite cast iron, it is set to contain C in an amount of 2 to 3% by weight and Si in an amount of 2.5 to 5.3% by weight. This is because the heat resistance and durability of the turbine housing to be obtained and the oxidation resistance of the turbine housing are necessary to secure the clearance between the scroll portion of the turbine housing and the turbine blade of the turbine. Further, in the second molten iron for spheroidal graphite cast iron, it was set to contain 3.3 to 4.1% by weight of C and 3.3 to 4.3% by weight of Si in order to withstand high temperature exhaust gas. This is because heat resistance and thermal fatigue life (durability) of the obtained exhaust manifold body are required. Note that the first and second spheroidal graphite cast iron melts Si
When setting the content, the difference in Si content between the first spheroidal graphite cast iron melt and the second spheroidal graphite cast iron melt is set to 0.
It is necessary to set it to 5 to 2.0% by weight for the reason described below.

The difference in Si content between the turbine housing cast from the first spheroidal graphite cast iron melt and the exhaust manifold body cast from the second spheroidal graphite cast iron melt is 0.5 to 2.0 weight. If the amount is less than 0.5% by weight, the oxidation resistance of the turbine housing may be insufficient and the thermal fatigue life of the exhaust manifold body may be insufficient. If it exceeds the range, the castability of the molten metal that forms the turbine housing may deteriorate,
This is because the thermal fatigue life of the exhaust manifold main body may be insufficient.

According to the first aspect of the invention, the turbine housing made of the first spheroidal graphite cast iron melt and the second exhaust manifold body made of the spheroidal graphite cast iron melt are formed by casting. A boundary portion is formed at a boundary portion between the turbine housing and the exhaust manifold body, in which both the first and second spheroidal graphite cast iron melts are mixed. By forming the turbine housing and the exhaust manifold main body from mutually different spheroidal graphite cast iron materials in this way, it is possible to exhibit the performance according to each material. Therefore, even when hot exhaust gas flows through the turbine housing integrated exhaust manifold, unlike the prior art, the turbine housing side and the exhaust manifold body side have heat resistance and durability suitable for each side. The performance of the sex comes to be exhibited.

According to a second aspect of the present invention, there is provided a turbine housing integrated exhaust manifold made of spheroidal graphite cast iron in which a turbine housing and an exhaust manifold main body are integrally cast, and the exhaust manifold has a C content of 2 to 3% by weight and a weight of 18 to 36% by weight. % Of the first spheroidal graphite cast iron containing Ni, and 3.3 to 4.1% by weight of C, and second spheroidal graphite cast iron containing 2% by weight or less of Ni. The exhaust manifold body cast from the molten metal
The gist is that it consists of a boundary portion formed by mixing and casting the two molten metals having a difference in content of 16 to 36% by weight.

Here, in the first melt for spheroidal graphite cast iron, the content of C of 2-3% by weight and Ni of 18-36% by weight is set because the clearance between the scroll portion and the turbine blade is set. And the oxidation resistance of the turbine housing to ensure full performance of the turbocharger,
This is because high temperature strength of the turbine housing is required to satisfy the deformation limit. Further, in the second molten iron for spheroidal graphite cast iron, C is 3.3 to 4.1% by weight, and Ni is 2
Although the exhaust manifold main body does not require high-temperature strength, etc. as the turbine housing does, it is required to have excellent thermal fatigue life (durability) because it is strongly bound to the cylinder block of the engine. Because it is said. In addition, N of the first and second spheroidal graphite cast iron melts
When setting the i content, the difference in Ni content between the first spheroidal graphite cast iron melt and the second spheroidal graphite cast iron melt is set to 1
It is necessary to adjust the amount to 6 to 36% by weight for the reason described below.

The difference in Ni content between the turbine housing cast from the first spheroidal graphite cast iron melt and the exhaust manifold body cast from the second spheroidal graphite cast iron melt is 1
The range of 6 to 36% by weight is set so that if it is less than 16% by weight, the oxidation resistance of the turbine housing may be insufficient,
This is because the high temperature strength of the turbine housing may be insufficient, and if it exceeds 36% by weight, the castability of the molten metal forming the turbine housing and the exhaust manifold body may be deteriorated.

According to the second aspect of the present invention, the turbine housing made of the first molten spheroidal graphite cast iron is formed by casting, and the exhaust manifold main body made of the second molten spheroidal graphite cast iron is formed. A boundary portion is formed at a boundary portion between the turbine housing and the exhaust manifold body, in which both the first and second spheroidal graphite cast iron melts are mixed. By forming the turbine housing and the exhaust manifold main body from mutually different spheroidal graphite cast iron materials in this way, it is possible to exhibit the performance according to each material. Therefore, even when hot exhaust gas flows through the turbine housing integrated exhaust manifold, unlike the prior art, the turbine housing side and the exhaust manifold body side have heat resistance and durability suitable for each side. The performance of the sex comes to be exhibited.

According to a third aspect of the present invention, in the turbine housing integrated exhaust manifold according to the first or second aspect, the Cr content of the exhaust manifold main body is 0.2 wt% or less, and the turbine is Housing C
The r content is 1 than the Cr content of the exhaust manifold body.
The gist is that the content is up to 3% by weight.

Here, the Cr content of the exhaust manifold main body is set to 0.2% by weight or less because when it exceeds 0.2% by weight, the thermal fatigue life (durability) of the exhaust manifold main body decreases. This is because there is a risk that it will end up. In addition, the Cr content of the turbine housing is set to the Cr content of the exhaust manifold body.
It is preferable to set 1 to 3% by weight more than the content. By setting the Cr content to be 1 to 3 weights higher in this way, the turbine housing can obtain higher high-temperature strength than the exhaust manifold main body, and the turbine housing can exhibit higher durability.

According to the third aspect of the present invention, by setting the Cr content of the turbine housing and the exhaust manifold main body to the predetermined amount, the invention according to the first and second aspects is achieved. The same effect is more reliably achieved.

According to a fourth aspect of the present invention, there is provided the turbine housing-integrated exhaust manifold according to the first or second aspect, wherein the exhaust manifold main body has 0.8 wt% or less of Mo and 0.6 wt% or less. V, 0.6% by weight or less of Nb is contained, and when the respective contents of Mo, V, and Nb of the turbine housing are subtracted from the exhaust manifold main body, the difference in Mo content is 0.2. ~ 0.8% by weight, V
One or more of the three conditions in which the difference in content is 0.1 to 0.6 wt% and the difference in Nb content is 0.1 to 0.6 wt% are satisfied. It is a summary.

Here, in the exhaust manifold main body, M
o content is 0.8 wt% or less, V content is 0.6 wt%
Hereinafter, the reason why the Nb content is set to 0.6% by weight or less is that
If each content exceeds the predetermined amount, not only the heat resistance of the exhaust manifold main body cannot be effectively improved, but also the machinability of the exhaust manifold main body may be deteriorated.

When the respective contents of Mo, V and Nb in the turbine housing are subtracted (subtracted) from Mo, V and Nb in the exhaust manifold main body, the difference in Mo content is 0.2 to 0.
8% by weight, V content difference is 0.1 to 0.6% by weight, Nb
It is preferable that one or more conditions are satisfied among the three conditions in which the difference in content is 0.1 to 0.6% by weight.
By satisfying one or more of the above-mentioned three conditions, the heat resistance of the turbine housing can be sufficiently exhibited.

According to the invention described in claim 4, Mo, V, N of the turbine housing and the exhaust manifold main body are included.
By setting each content of b so as to be the predetermined amount, the same effects as those of the inventions according to claims 1 and 2 are more reliably exhibited.

According to a fifth aspect of the present invention, there is provided a turbine housing made of the first spheroidal graphite cast iron melt, a second exhaust manifold body made of the spheroidal graphite cast iron melt, the turbine housing and the exhaust manifold body. A method for manufacturing a turbine housing-integrated exhaust manifold made of spheroidal graphite cast iron, which comprises integrally forming a boundary portion formed by mixing the two molten metals at a boundary portion of 2 to 3% by weight of C, 2.5 ˜5.3 wt% Si, a first spheroidal graphite cast iron melt for casting the turbine housing and 3.3-4.1 wt% C, 3.3-4.3.
Preparation step containing Si in an amount of 0.5% by weight and adjusting the difference in Si content from the second molten iron for spheroidal graphite cast iron for casting the exhaust manifold body to 0.5 to 2.0% by weight. And pouring one of the first and second spheroidal graphite cast iron melts prepared in the preparation step from the first gate of the mold to the one side in the cavity through the first runner. The first pouring step and the first prepared by the preparation step
And the other of the second spheroidal graphite cast iron melts,
Second pouring from the second gate of the mold to the other side in the cavity through the second runner, and mixing the two melts of the first and second spheroidal graphite cast iron melts in the portion corresponding to the boundary portion And a solidification step of solidifying the first and second molten nodules for spheroidal graphite cast iron filled in the cavity by the first and second pouring steps, and The gist is that it comprises a removing step of removing an excessive portion from the cast product.

A fifth aspect of the present invention relates to a method of manufacturing an exhaust manifold integrated with a turbine housing according to the first aspect. In the preparation step of this manufacturing method, C of the first and second spheroidal graphite cast iron melts,
The reason for adjusting the content of Si to a predetermined amount is the same as that described in claim 1.

According to this manufacturing method, the first and second spheroidal graphite cast iron melts prepared in the preparing step are transferred from the first and second gates of the mold to the inside of the cavity through the first and second runners. The 1st and 2nd pouring process of pouring to the side and the other side is performed. In this case, in the cavity of the mold, the portion corresponding to the turbine housing is filled with the first spheroidal graphite cast iron molten metal, and the portion corresponding to the exhaust manifold body is filled with the second spheroidal graphite cast iron molten metal. And a portion corresponding to a boundary portion between the exhaust manifold main body and the exhaust manifold main body is in a state where both the first and second spheroidal graphite cast iron melts are mixed.

Next, a solidification step is performed in that state to obtain a cast product in which the turbine housing and the exhaust manifold body are integrally cast. Then, by performing a removing step of removing an excessive portion from the obtained cast product, a turbine housing made of the first spheroidal graphite cast iron melt, and an exhaust manifold main body made of the second spheroidal graphite cast iron melt, The turbine-manufacturing-integrated exhaust manifold according to claim 1, further comprising: a boundary portion formed by mixing both of the first and second spheroidal graphite cast iron melts at a boundary portion between the turbine housing and the exhaust manifold body. Will be obtained.

According to a sixth aspect of the present invention, there is provided a turbine housing made of the first spheroidal graphite cast iron melt, a second exhaust manifold body made of the spheroidal graphite cast iron melt, the turbine housing and the exhaust manifold body. Is a method for manufacturing a turbine housing-integrated exhaust manifold made of spheroidal graphite cast iron, which is formed by integral casting with a boundary portion formed by mixing both molten metals at a boundary portion of C, 18 to 36% by weight. A first spheroidal graphite cast iron melt for casting the turbine housing, containing 3.3% by weight of Ni; and C of 3.3 to 4.1% by weight, 2% by weight or less of Ni
And the difference in Ni content from the second spheroidal graphite cast iron melt for casting the exhaust manifold body is 16 to 3
A preparation step of 6 wt% and one of the first and second spheroidal graphite cast iron melts prepared by the preparation step are introduced from the first gate of the mold to the first runner. Through the first pouring step of pouring into one side of the cavity through the above, and the other of the first and second spheroidal graphite cast iron melts prepared in the preparing step described above, to the second gate of the mold. To the other side of the cavity through the second runner,
The cavity was filled by the second pouring step of mixing both the first and second spheroidal graphite cast iron melts in a portion corresponding to the boundary portion, and the first and second pouring steps. The gist of the present invention is to include a solidification step of solidifying the first and second spheroidal graphite cast iron melts, and a removal step of removing an extra portion from the cast product obtained by the solidification step.

A sixth aspect of the present invention relates to a method of manufacturing an exhaust manifold integrated with a turbine housing according to the second aspect. In the preparation step of this manufacturing method, C of the first and second spheroidal graphite cast iron melts,
The reason for adjusting the Ni content to a predetermined amount is the same as that described in claim 2.

According to this manufacturing method, the first and second melts for spheroidal graphite cast iron prepared in the preparing step are transferred from the first and second gates of the mold through the first and second runners to the inside of the cavity. The 1st and 2nd pouring process of pouring to the side and the other side is performed. In this case, in the cavity of the mold, the portion corresponding to the turbine housing is filled with the first spheroidal graphite cast iron molten metal, and the portion corresponding to the exhaust manifold body is filled with the second spheroidal graphite cast iron molten metal. And a portion corresponding to a boundary portion between the exhaust manifold main body and the exhaust manifold main body is in a state where both the first and second spheroidal graphite cast iron melts are mixed.

Next, a solidification step is performed in this state, whereby a cast product in which the turbine housing and the exhaust manifold main body are integrally cast is obtained. Then, by performing a removing step of removing an excessive portion from the obtained cast product, a turbine housing made of the first spheroidal graphite cast iron melt, and an exhaust manifold main body made of the second spheroidal graphite cast iron melt, The exhaust manifold with a built-in turbine housing according to claim 2, further comprising: a boundary portion formed by mixing both the first and second spheroidal graphite cast iron melts at a boundary portion between the turbine housing and the exhaust manifold body. Will be obtained.

According to a seventh aspect of the present invention, in the method for manufacturing an exhaust manifold with a turbine housing integrated according to the fifth or sixth aspect, when the first pouring step is performed, the inside of the cavity is The gist of the invention is to allow excess melt of the spheroidal graphite cast iron melt poured into one side to escape from the cavity to the melt escape portion.

According to the invention described in claim 7, in addition to the effects of the invention described in claims 5 and 6, when the first pouring step is carried out, it is poured into one side in the cavity. By escaping the excess molten molten spheroidal graphite cast iron from the cavity to the molten metal escaping portion, the spheroidal graphite cast iron molten metal is prevented from occupying a portion exceeding a predetermined volume on one side in the cavity. . In other words, the molten spheroidal graphite cast iron that is poured into one side of the cavity is poured into the portion of the cavity where the molten spheroidal graphite cast iron that is poured into the other side of the cavity is to be poured. It is supposed not to be done. Further, the molten metal escape portion also plays a role of escaping excess molten spheroidal graphite cast iron molten metal that is poured to the other side in the cavity from the cavity. Therefore, by letting the excess molten metal of the first and second spheroidal graphite cast iron melts escape from the cavity to the molten metal escape part, both the first and second spheroidal graphite cast iron melts are well mixed at a predetermined position. Since they match, a boundary portion formed by mixing both the first and second spheroidal graphite cast iron melts is surely formed at the boundary portion between the turbine housing and the exhaust manifold body.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION As shown in FIG. 1, a turbine housing integrated exhaust manifold made of spheroidal graphite cast iron in the present embodiment comprises a turbine housing 11 cast from a first spheroidal graphite cast iron melt, 2. Exhaust manifold body 12 cast from molten spheroidal graphite cast iron, and boundary portion between turbine housing 11 and exhaust manifold body 12, that is, a portion where turbine housing 11 and exhaust manifold body 12 are adjacent to each other and a portion in the vicinity thereof. And a boundary portion 13 formed by mixing and melting both the first and second spheroidal graphite cast iron melts in a region including.
The boundary portion 13 is a portion (exhaust merging portion) where the exhaust gas branched from the cylinder head of the multi-cylinder (four cylinders in this embodiment) engine flows through the exhaust manifold body 12 and then merges and gathers. Equivalent to.

The first spheroidal graphite cast iron melt for casting the turbine housing 11 contains 2 to 3% by weight of C and Si.
2 to 5 to 5.3% by weight or C to 2 to 3% by weight
It is necessary to satisfy at least one of two conditions, that is, wt% and Ni content of 18 to 36 wt%.
A preferable first molten iron for spheroidal graphite cast iron contains C in an amount of 2 to 3% by weight, Si in an amount of 2.5 to 5.3% by weight, and Ni in an amount of 18 to 36% by weight. In addition, the first spheroidal graphite cast iron melt is 1 to more than the second spheroidal graphite cast iron melt described later.
It is preferable to contain 3% by weight of Cr, or
When the Mo, V, and Nb contents of the first spheroidal graphite cast iron melt were subtracted from the Mo, V, and Nb contents of the first spheroidal graphite cast iron, the difference in Mo content was 0. 2-0.
8% by weight, V content difference is 0.1 to 0.6% by weight, Nb
It is preferable to satisfy one or more conditions among the three conditions in which the difference in content is 0.1 to 0.6% by weight. The first spheroidal graphite cast iron melt may contain Mn, P, S, Mg or the like in addition to Fe as the main component.

On the other hand, the second spheroidal graphite cast iron melt for casting the exhaust manifold body 12 contains C in the range of 3.3 to 4.
One of two conditions: 1 wt% and 3.3 to 4.3 wt% Si, or 3.3 to 4.1 wt% C and 2 wt% or less Ni. It is necessary to meet the above conditions. A preferable second molten iron for spheroidal graphite cast iron is 3.3 to 4.1% by weight of C and 3.3 to 4.3 of Si.
% By weight, and 2% by weight or less of Ni is contained. The second molten iron for spheroidal graphite cast iron contains 0.2% by weight or less of Cr, or 0.8% by weight or less of Mo,
It is preferable to contain 0.6% by weight or less of V and 0.6% by weight or less of Nb. Here, in the content of each component, the phrase "wt% or less" means that 0 wt% that does not contain the component is included. The second spheroidal graphite cast iron melt may contain Mn, P, S, Mg, and the like in addition to Fe as the main component.

When selecting and using the above-mentioned first and second melts for spheroidal graphite cast iron, one or more of the following two conditions (and) (,, +
) Must be met. The first condition is
The difference between the Si content of the first spheroidal graphite cast iron melt and the Si content of the second spheroidal graphite cast iron melt is 0.5.
To 2.0 wt% (), the second condition is that the Ni content of the first spheroidal graphite cast iron melt and the Ni content of the second spheroidal graphite cast iron melt are Ni. The difference in content is within the range of 16 to 36% by weight (). That is, among the three conditions of satisfying only the condition of, or satisfying only the condition of,
Only the first and second spheroidal graphite cast iron melts satisfying any one of them can be used.

Now, referring to FIG. 1, a method of manufacturing the exhaust manifold with a turbine housing integrated according to the present embodiment will be described.
The following is a description with reference to FIG. In this embodiment, the turbine housing 11 is formed on one side of the cavity 17 and the exhaust manifold main body 12 is formed on the other side of the cavity 17, but conversely,
The exhaust manifold body may be formed on one side of the cavity and the turbine housing may be formed on the other side of the cavity.

As shown in FIG. 2, the sand mold 14 as a mold used in the method for manufacturing the turbine housing-integrated exhaust manifold according to the present embodiment includes an upper mold 15 and a lower mold 16.
The sand mold 14 has a cavity 17 formed therein by combining the upper mold 15 and the lower mold 16. On one side of the sand mold 14, the first sprue 18 and the first runner 1
9 is formed, and the first sprue 18 communicates with one side in the cavity 17 via the first runner 19. A second gate 20 and a second runner 21 are formed on the other side of the sand mold 14, and the second gate 20 communicates with the other side of the cavity 17 via the second runner 21. . Cavity 17
One side inside corresponds to a portion where the turbine housing 11 is formed, and the other side inside the cavity 17 corresponds to a portion where the exhaust manifold body 12 is formed. Although the sand mold 14 is used as the mold in the present embodiment, a mold may be used.

Inside the cavity 17 of the sand mold 14, a core (not shown) for forming the hollow portions of the turbine housing 11 and the exhaust manifold main body 12 is set. Further, the sand mold 14 is provided with two molten metal detection sensors 22 and 23 utilizing an electrical short circuit. One end 22a of the molten metal detection sensor 22 has a first gate 18
The other end 22b of the molten metal detection sensor 22 is set at the bottom of the
Is set in a portion of the cavity 17 corresponding to the upper end of the turbine housing 11. One end 23a of the molten metal detection sensor 23 is set at the bottom of the second melt spout 20, and the other end 23b of the molten metal detection sensor 23 is set to the cavity 1
It is set in a portion corresponding to the center of the lower portion of the exhaust manifold body 12 in 7. Each molten metal detection sensor 22, 23
The molten metal comes into contact with both ends of the to be electrically connected to detect the flow position of the molten metal. Although the molten metal detection sensors 22 and 23 are used in the present embodiment, the molten metal detection sensors 22 and 23 may be omitted.

The first spheroidal graphite cast iron is provided between one side and the other side of the cavity 17, that is, a portion corresponding to a boundary portion (connection portion) between the turbine housing 11 and the exhaust manifold body 12 in the cavity 17. A molten metal escape portion 24 is formed so as to allow excess molten metal for use to escape from the cavity 17. The molten metal escape portion 24 is provided with the second spheroidal graphite cast iron when the second molten iron for spheroidal graphite cast iron is poured into the cavity 17.
It also serves to suppress the spheroidal graphite cast iron melt from pushing back the first spheroidal graphite cast iron melt toward the first gate 18. In other words, the excess melt of the second spheroidal graphite cast iron melt is similar to the first spheroidal graphite cast iron melt in the cavity 1.
The hot water escape section 24 is made to escape from inside 7. In this embodiment, the hot water escape portion 24 is formed, but the hot water escape portion 24 may not be formed.

First, some of the components described above are prepared by melting components such as Fe, C, Si, and Ni in, for example, a high-frequency induction furnace and performing a preparation step of adjusting the contents of C, Si, and Ni, and the like. The first and second spheroidal graphite cast iron melts satisfying the condition (1) are prepared.

Then, as shown in FIG. 3A, the prepared first spheroidal graphite cast iron molten metal 25 is passed from the first gate 18 of the sand mold 14 to one side of the cavity 17 through the first runner 19. The first pouring step of pouring is performed. In this case, the first melt 25 for spheroidal graphite cast iron is the end 22 of the melt detection sensor 22.
When reaching the other end 22b after reaching a, the one end 22a and the other end 22b of the molten metal detection sensor 22 are electrically connected to detect the flow position of the molten metal. At the same time when this detection is performed, the first pouring step is interrupted and the second pouring step described later is performed.

After the first pouring step, one side of the cavity 17, the first runner 19 and the first sprue 18 are filled with the first melt 25 for spheroidal graphite cast iron. Further, in the first pouring step, even if the first spheroidal graphite cast iron molten metal 25 is poured up to a portion exceeding the predetermined volume on one side in the cavity 17, it is poured to one side in the cavity 17. Excessive molten metal of the first spheroidal graphite cast iron molten metal 25 escapes from the cavity 17 to the molten metal escape portion 24. Therefore, the first melt 25 for spheroidal graphite cast iron is
Cavity 17 into which the molten iron for spheroidal graphite cast iron is to be poured
There will be no pouring on the other side.

Next, as shown in FIG. 3B, the prepared second spheroidal graphite cast iron melt 26 is added to the second gate 2 of the sand mold 14.
A second pouring step of pouring from 0 to the other side in the cavity 17 through the second runner 21 is performed. In this case, the second melt 26 for spheroidal graphite cast iron is the one end 23 a of the melt detection sensor 23.
When reaching the other end 23b after reaching, the one end 23a and the other end 23b of the molten metal detection sensor 23 are electrically connected to detect the flow position of the molten metal. And
After this detection is made, the interrupted first pouring process is restarted. The restart of the first pouring step is performed by pushing the first spheroidal graphite cast iron molten metal back toward the first gate 18 by the second spheroidal graphite cast iron molten metal poured in the second pouring step. Is to prevent.

After that, the excess melt of the second spheroidal graphite cast iron melt 26 is allowed to escape from the cavity 17 to the melt escape portion 24, and the second spheroidal graphite cast iron melt 26 is removed from the first melt.
The spheroidal graphite cast iron melt 25 of
Turbine housing 11 and exhaust manifold body 12 inside
Both the first and second spheroidal graphite cast iron melts 25 and 26 are mixed with each other at a portion corresponding to a boundary portion between and. Then, when the cavity 17 of the sand mold 14 is filled with the first and second spheroidal graphite cast iron melts 25 and 26, the first and second pouring steps are completed.

In this case, in the sand mold 14, one side of the cavity 17, the first runner 19 and the first gate 18 are filled with the first molten metal 25 for spheroidal graphite cast iron, and the other side of the cavity 17 The second runner 21 and the second sprue 20 are filled with the second molten iron for spheroidal graphite cast iron 26, and the space between the one side and the other side in the cavity 17 is the first and second molten spheroidal graphite cast iron 2.
Both molten metals of 5, 26 are filled in a mixed state. In addition, in the figure, a portion where both the melts of the first and second spheroidal graphite cast iron melts 25 and 26 are mixed is represented by a dotted pattern. In the molten metal escape part 24, a small amount of the first spheroidal graphite cast iron melt 25 is mixed with the second spheroidal graphite cast iron melt 26.

In the present embodiment, the above-mentioned first and second
Although the pouring was performed by the pouring method using the pouring step of, the first pouring step and the second pouring step are performed at the same time, or during pouring in the first pouring step. Alternatively, the second pouring step may be performed, and the pouring method of the present embodiment is not particularly limited. In short, in the cavity 17 after the first and second pouring steps, one side of the cavity 17 is filled with the first spheroidal graphite cast iron melt 25, and the other side of the cavity 17 is filled with the second spheroidal graphite cast iron. If it is filled with the molten metal 26, and the molten metal for the first and second molten spheroidal graphite cast irons 25 and 26 is mixed between the one side and the other side in the cavity 17, Such a pouring method may be used.

In the mode shown in FIG. 3B, the first and second
A casting is obtained by performing the solidification step of solidifying the spheroidal graphite cast iron melts 25 and 26. Finally, a removal step (eg machining) to remove excess parts from this casting
By doing so, an exhaust manifold with a turbine housing integrated as shown in FIG. 1 is obtained.

This turbine housing-integrated exhaust manifold comprises a turbine housing 11 made of a first spheroidal graphite cast iron melt 25 and a second spheroidal graphite cast iron melt 26.
The exhaust manifold main body 12 and the boundary portion 13 in which the first and second spheroidal graphite cast iron melts 25 and 26 are mixed at the boundary portion between the turbine housing 11 and the exhaust manifold main body 12. As described above, the turbine housing 11 and the exhaust manifold main body 12
The exhaust manifold with the integrated turbine housing of the present embodiment is manufactured by integrally casting and.

According to this embodiment described in detail above, the following effects can be obtained.

In this embodiment, the turbine housing 11 is cast from the first spheroidal graphite cast iron melt 25, and the exhaust manifold body 12 is cast from the second spheroidal graphite cast iron melt 26. By forming the turbine housing 11 and the exhaust manifold main body 12 from mutually different spheroidal graphite cast iron materials in this manner, the turbine housing 11 side and the exhaust manifold main body 12 side have heat resistance and heat resistance suitable for each side. You will be able to exert durability performance.

According to the manufacturing method of this embodiment, a turbine capable of exhibiting heat resistance and durability performance suitable for the turbine housing 11 side and the exhaust manifold body 12 side, respectively. A housing integrated exhaust manifold can be manufactured.

According to the present embodiment, excess melt of the first and second spheroidal graphite cast iron melts 25, 26 can be released from the cavity 17 to the melt escape portion 24. As a result, the first spheroidal graphite cast iron molten metal 25 and the second spheroidal graphite cast iron molten metal 26 are mixed in a predetermined region in the cavity 17, so that the boundary portion between the turbine housing 11 and the exhaust manifold body 12 is The boundary portion 13 can be reliably formed at the position.

The molten metal detection sensor 22 of this embodiment makes it possible to grasp the timing at which the first pouring process is interrupted. Further, the molten metal detection sensor 23 makes it possible to grasp the timing at which the first pouring process is restarted.

According to the manufacturing method of the present embodiment, the first
By restarting the pouring process of No. 1, the first spheroidal graphite cast iron melt 25 is pushed back toward the first gate 18 by the second spheroidal graphite cast iron melt 26 poured in the second pouring process. Can be prevented.

According to the present embodiment, in the cavity 17 of the sand mold 14, one side of the cavity 17 is first
Of the spheroidal graphite cast iron, the other side of the cavity 17 is filled with a second spheroidal graphite cast iron melt 26, and the first and second spheroidal graphite is provided between the one side and the other side of the cavity 17. Both of the cast iron melts 25 and 26 can be filled in a mixed state.

[0057]

EXAMPLES Examples 1 to 13 and Comparative Examples 1 to 18 which further embody the present invention will be described below. In addition, in Tables 1 to 4, the content of Fe (% by weight)
However, most of them are Fe except for the composition components shown in the table. In Tables 1 to 4, the first spheroidal graphite cast iron melt for casting the turbine housing is "T", and the second spheroidal graphite cast iron melt for casting the exhaust manifold body (exhaust manifold body). Was expressed as "E".

(Examples 1 to 13) In Examples 1 to 13, the first and second melts for spheroidal graphite cast iron were prepared so as to have the composition of each example shown in Table 1. Prepared. Next, the prepared first and second spheroidal graphite cast iron melts are used, and the turbine housing-integrated exhaust manifold of each example (see FIG. 1) is used according to the method for manufacturing the turbine housing-integrated exhaust manifold in the above-described embodiment. Manufactured).

[0059]

【table 1】

The turbine housing-integrated exhaust manifolds of Examples 1 to 13 were evaluated for heat resistance and durability. The evaluation method is to start the engine with the turbine housing-integrated exhaust manifold assembled to the actual vehicle, and to operate the engine with the turbine housing-integrated exhaust manifold flowing 900 ° C exhaust gas for a predetermined time, and then stop the engine. A series of operations of cooling the turbine housing-integrated exhaust manifold to 200 ° C. is set as one cycle, and is evaluated after 1000 cycles.

With the turbine housing-integrated exhaust manifolds of Examples 1 to 13, cracks did not occur in any part of the turbine housing, the exhaust manifold body, and the boundary even after 1000 cycles. That is, it was confirmed that the turbine housing-integrated exhaust manifolds of Examples 1 to 13 could sufficiently exhibit their heat resistance and durability.

(Comparative Examples 1 to 18) In Comparative Examples 1 to 18, for the first and second spheroidal graphite cast irons so that the component compositions of the respective comparative examples shown in Tables 2 to 4 are obtained. Each molten metal was prepared. Next, using the prepared 1st and 2nd spheroidal graphite cast iron melts, Example 1-Example 13
Similarly, the turbine housing integrated exhaust manifold (see FIG. 1) of each comparative example was manufactured according to the method for manufacturing the turbine housing integrated exhaust manifold in the above-described embodiment.

[0063]

[Table 2]

[0064]

[Table 3]

[0065]

[Table 4]

The turbine housing-integrated exhaust manifolds of Comparative Examples 1 to 18 were evaluated for heat resistance and durability. The evaluation method is the same as the evaluation method of the example.

In the turbine housing integrated exhaust manifolds of Comparative Example 1 to Comparative Example 14 and Comparative Example 16 to Comparative Example 18, cracks occurred in the turbine housing, and in the turbine housing integrated exhaust manifold of Comparative Example 15, the exhaust manifold main body. A crack has occurred in. From this, it is understood that the turbine housing integrated exhaust manifolds of Comparative Examples 1 to 18 have insufficient heat resistance and durability.

Besides, the technical idea which is not described in each claim of the claims and which is grasped from the above-described embodiment and the like will be described below together with its effect.

(A) A turbine housing integrated exhaust manifold made of spheroidal graphite cast iron in which the turbine housing and the exhaust manifold main body are integrally cast,
3 wt% C, 2.5-5.3 wt% Si, 18-3
The turbine housing cast from a first spheroidal graphite cast iron melt containing 6% by weight of Ni;
1% by weight C, 3.3 to 4.3% by weight Si, 2% by weight
The difference in Si content from the exhaust manifold body cast from the second molten spheroidal graphite cast iron containing Ni below is 0.5 to 2.0% by weight, and the difference in Ni content is 16%. A turbine housing-integrated exhaust manifold, comprising: a boundary portion formed by mixing and casting the molten metal of about 36% by weight.

According to this structure, heat resistance and durability performance suitable for the turbine housing side and the exhaust manifold main body side can be exhibited.

(B) A turbine housing made of the first spheroidal graphite cast iron melt, a second exhaust manifold main body made of the second spheroidal graphite cast iron melt, and both of them at the boundary between the turbine housing and the exhaust manifold main body. A method for manufacturing a turbine housing integrated exhaust manifold made of spheroidal graphite cast iron, wherein a boundary portion formed by mixing molten metal is formed by integral casting.
A first spheroidal graphite cast iron melt containing 5.3 wt% Si and 18 to 36 wt% Ni and 3.3 to 4.1 wt% C for casting the turbine housing. ．
3 to 4.3% by weight of Si and 2% by weight or less of Ni, and the difference in Si content from the second molten metal for spheroidal graphite cast iron for casting the exhaust manifold body is 0.5 to 2 .0
Wt%, a preparation step of adjusting the Ni content difference to be 16 to 36 wt%, and one of the first and second spheroidal graphite cast iron melts prepared by the preparation step, Of the first and second molten spheroidal graphite cast iron melts prepared by the first pouring step of pouring from the first gate of the mold through the first runner to one side in the cavity The other molten metal is poured from the second gate of the mold to the other side in the cavity through the second runner, and both the first and second spheroidal graphite cast iron molten metal of the portion corresponding to the boundary portion are poured. A second pouring step of mixing the molten metal; a solidification step of solidifying the first and second spheroidal graphite cast iron melts filled in the cavity by the first and second pouring steps; A removing step for removing an extra portion from the casting obtained from the solidifying step; Method for manufacturing a turbine housing integrated exhaust manifold and characterized in that it comprises.

By doing so, it is possible to obtain a turbine housing integrated exhaust manifold capable of exhibiting heat resistance and durability performance suitable for the turbine housing side and the exhaust manifold main body side, respectively. You can

(C) C of the second molten iron for spheroidal graphite cast iron
The r content is 0.2 wt% or less, and the Cr content of the first spheroidal graphite cast iron melt is 1 to 3 wt% higher than the Cr content of the second spheroidal graphite cast iron melt. The method for manufacturing an exhaust manifold with a turbine housing integrated according to any one of claims 5 to 7 and (b).

According to this configuration, claims 5 to 7,
The effect similar to that of the invention described in (b) above can be exhibited more reliably.

(D) The second spheroidal graphite cast iron melt contains 0.8% by weight or less of Mo, 0.6% by weight or less of V, and 0.
Containing 6% by weight or less of Nb, the second spheroidal graphite cast iron molten metal to the first spheroidal graphite cast iron molten metal Mo;
When the respective contents of V and Nb are subtracted, the difference in Mo content is 0.2 to 0.8% by weight, and the difference in V content is 0.1 to 0.
At least one of the three conditions of 6% by weight and the difference in Nb content of 0.1 to 0.6% by weight is satisfied. A method of manufacturing an exhaust manifold integrated with a turbine housing according to any one of (b).

According to this configuration, the fifth to seventh aspects,
The effect similar to that of the invention described in (b) above can be exhibited more reliably.

[0077]

According to the invention described in claims 1 to 4, it is possible to exhibit heat resistance and durability performance suitable for the turbine housing side and the exhaust manifold body side, respectively. it can.

According to the invention described in claim 5 or 6, it is possible to exhibit heat resistance and durability performance suitable for the turbine housing side and the exhaust manifold body side, respectively. A turbine housing integrated exhaust manifold can be obtained.

According to the seventh aspect of the present invention, in addition to the effects of the fifth and sixth aspects of the present invention, the boundary portion is surely formed at the boundary portion between the turbine housing and the exhaust manifold main body. You can

[Brief description of drawings]

FIG. 1 is a front view showing an exhaust manifold integrated with a turbine housing according to the present embodiment.

FIG. 2 is a cross-sectional view schematically showing the sand mold of the present embodiment.

FIG. 3 (a) is a cross-sectional view schematically showing a state in which the first spheroidal graphite cast iron molten metal has been poured into one side of the sand mold cavity, and (b) the other side of the sand mold cavity to the other side. It is sectional drawing which shows the state which poured the molten metal for spheroidal graphite cast iron of 2 typically.

[Explanation of symbols]

11 Turbine housing 12 Exhaust manifold body 13 border 14 sand mold 15 Upper mold 16 Lower mold 17 cavities 18 First gate 19 First runway 20 Second gate 21 Second runway 24 Hot water escape section 25 1st Spheroidal Graphite Cast Iron Molten Metal 26 Second spheroidal graphite cast iron melt

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B22D 19/00 B22D 19/00 X 19/16 19/16 Z C22C 37/08 C22C 37/08 Z F01N 7 / 10 F01N 7/10 7/16 7/16 F02B 39/00 F02B 39/00 DU

Claims (7)

[Claims] 1. A turbine housing-integrated exhaust manifold made of spheroidal graphite cast iron in which a turbine housing and an exhaust manifold main body are integrally cast, with 2-3% by weight of C and 2.5-5.3% by weight of Si. And a turbine housing cast from a first spheroidal graphite cast iron molten metal containing 3.3 to 4.1 wt% C, 3.3.
The exhaust manifold body cast from the second spheroidal graphite cast iron melt containing Si to 4.3 wt% and the two melts having a Si content difference of 0.5 to 2.0 wt%. An exhaust manifold integrated with a turbine housing, which comprises a boundary portion that is mixed and cast. 2. A turbine housing-integrated exhaust manifold made of spheroidal graphite cast iron, which is formed by integrally casting a turbine housing and an exhaust manifold main body, containing 2-3% by weight of C and 18-36% by weight of Ni. 1. The turbine housing cast from No. 1 spheroidal graphite cast iron melt, and the second cast from the second spheroidal graphite cast iron melt containing 3.3-4.1 wt% C, 2 wt% or less Ni. The difference between the exhaust manifold body and Ni content is 1
A turbine housing-integrated exhaust manifold, comprising a boundary portion formed by mixing and casting the molten metal of 6 to 36% by weight. 3. The exhaust manifold main body has a Cr content of 0.2 wt% or less, and a C content of the turbine housing.
The r content is 1 than the Cr content of the exhaust manifold body.
3 to 3% by weight more, Claim 1 or Claim 2 characterized by the above-mentioned.
An exhaust manifold with an integrated turbine housing according to claim 1. 4. The exhaust manifold body is 0.8% by weight.
When the following Mo, 0.6% by weight or less V, and 0.6% by weight or less Nb are contained, and the respective contents of Mo, V, and Nb in the turbine housing are subtracted from the exhaust manifold main body, , The difference in Mo content is 0.2 to 0.8% by weight,
One or more of the three conditions in which the difference in V content is 0.1 to 0.6 wt% and the difference in Nb content is 0.1 to 0.6 wt% are satisfied. An exhaust manifold integrated with a turbine housing according to claim 1 or 2. 5. A turbine housing made of a first spheroidal graphite cast iron melt, a second exhaust manifold body made of a second spheroidal graphite cast iron melt, and the two molten metals at a boundary portion between the turbine housing and the exhaust manifold body. A method for manufacturing a turbine housing integrated exhaust manifold made of spheroidal graphite cast iron, wherein a boundary portion formed by mixing is formed by integral casting, comprising: 2 to 3% by weight of C and 2.5 to 5.3% by weight. A first spheroidal graphite cast iron melt containing Si and 3.3 to 4.1 wt% C;
S with a second spheroidal graphite cast iron melt containing 3 to 4.3% by weight of Si for casting the exhaust manifold body.
A preparation step of preparing the i content to be 0.5 to 2.0% by weight, and one of the first and second spheroidal graphite cast iron melts prepared by the preparation step. A first pouring step of pouring from the first gate of the mold to one side of the cavity through the first runner, and the first and second spheroidal graphite cast iron melts prepared by the preparing step. The other of the melts is poured from the second gate of the mold through the second runner to the other side in the cavity, and the first and second spheroidal graphite cast iron melts in the portion corresponding to the boundary are poured. A second pouring step of mixing the two molten metals, and a solidification step of solidifying the first and second spheroidal graphite cast iron molten metals filled in the cavity by the first and second pouring steps , A removal step of removing an excess portion from the casting obtained by the solidification step. A method of manufacturing an exhaust manifold integrated with a turbine housing, comprising: 6. A turbine housing made of a first spheroidal graphite cast iron melt, a second exhaust manifold body made of a second spheroidal graphite cast iron melt, and the two molten metals at a boundary portion between the turbine housing and the exhaust manifold body. A method for manufacturing a turbine housing integrated exhaust manifold made of spheroidal graphite cast iron, wherein the boundary portion formed by mixing is formed by integral casting, containing 2-3% by weight of C and 18-36% by weight of Ni. ,
A first spheroidal graphite cast iron melt for casting the turbine housing, 3.3-4.1 wt% C, 2 wt%
A preparation step containing the following Ni so that the difference in the Ni content from the second spheroidal graphite cast iron melt for casting the exhaust manifold body is 16 to 36% by weight; The first pouring for pouring one of the first and second spheroidal graphite cast iron melts prepared in accordance with (1) to one side in the cavity from the first gate of the mold through the first runner. Step, and pouring the other of the first and second spheroidal graphite cast iron melts prepared in the preparation step from the second gate of the mold to the other side in the cavity through the second runner. Then, a second pouring step of mixing both the first and second spheroidal graphite cast iron melts corresponding to the boundary portion into the cavity by the first and second pouring steps. The first and second spheroidal graphite cast iron melts filled are solidified. Solidification process and method for producing a turbine housing integrated exhaust manifold, characterized by comprising a removing step of removing the excess portion from the casting, wherein obtained from the solidification process that. 7. When the first pouring step is performed, an excess of the spheroidal graphite cast iron molten metal that has been poured into one side of the cavity is allowed to escape from the inside of the cavity to the molten metal escape portion. The method according to claim 5 or 6, wherein the exhaust manifold is integrated with the turbine housing.