U.S. patent application number 11/003657 was filed with the patent office on 2005-07-14 for composited cast member, iron-based porous substance for composited cast members, and pressure casing processes for producing the same, constituent member of compressors provided with composited cast members and the compressors.
Invention is credited to Fukanuma, Tetsuhiko, Kinoshita, Kyoichi, Miyoshi, Manabu, Sugiura, Manabu, Tanizawa, Motoharu, Yoshikawa, Genki.
Application Number | 20050153156 11/003657 |
Document ID | / |
Family ID | 34594010 |
Filed Date | 2005-07-14 |
United States Patent
Application |
20050153156 |
Kind Code |
A1 |
Miyoshi, Manabu ; et
al. |
July 14, 2005 |
Composited cast member, iron-based porous substance for composited
cast members, and pressure casing processes for producing the same,
constituent member of compressors provided with composited cast
members and the compressors
Abstract
A pressure casing includes a composited cast member. The
composited cast member includes an iron-based porous substance
whose major component is Fe and which has a large number of pores,
and a cast-wrapping member whose major component is a light metal
and which cast-wraps a part of the iron-based porous substance at
least. The iron-based porous substance includes a connector
disposed adjacent to a boundary between the iron-based porous
substance and the cast-wrapping member and exhibiting a larger
porosity, and a high-strength reinforcer disposed in the iron-based
porous substance free from the connector and exhibiting a smaller
porosity. The connector is impregnated with the cast-wrapping
member, and solidifies therewith, thereby firmly bonding the
iron-based porous substance and the cast-wrapping member in the
composited cast member. The pressure casing secures strength with
the reinforcer, and secures adhesiveness with the connector.
Inventors: |
Miyoshi, Manabu;
(Kariya-shi, JP) ; Kinoshita, Kyoichi;
(Kariya-shi, JP) ; Tanizawa, Motoharu;
(Kariya-shi, JP) ; Yoshikawa, Genki; (Kariya-shi,
JP) ; Fukanuma, Tetsuhiko; (Kariya-shi, JP) ;
Sugiura, Manabu; (Kariya-shi, JP) |
Correspondence
Address: |
Morgan & Finnegan, L.L.P.
3 World Financial Center
New York
NY
10281-2101
US
|
Family ID: |
34594010 |
Appl. No.: |
11/003657 |
Filed: |
December 3, 2004 |
Current U.S.
Class: |
428/613 ; 164/98;
419/6 |
Current CPC
Class: |
B22F 7/004 20130101;
B22F 7/004 20130101; B22F 3/1109 20130101; B22F 2998/10 20130101;
B22F 2998/10 20130101; F04B 39/121 20130101; B22F 3/1134 20130101;
B22D 19/14 20130101; Y10T 428/12479 20150115; F04B 39/12
20130101 |
Class at
Publication: |
428/613 ;
164/098; 419/006 |
International
Class: |
B22D 019/02; B22F
007/02 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 4, 2003 |
JP |
2003-406415 |
Dec 4, 2003 |
JP |
2003-406418 |
Claims
What is claimed is:
1. A composited cast member, comprising: an iron-based porous
substance comprising iron (Fe), and having a large number of pores;
and a cast-wrapping member comprising a metal whose major component
is at least one member selected from the group consisting of
aluminum (Al) and magnesium (Mg), and cast-wrapping a part of the
iron-based porous substance at least; the iron-based porous
substance further comprising a connector disposed adjacent to a
boundary between the iron-based porous substance and the
cast-wrapping member and exhibiting a predetermined porosity, and a
high-strength reinforcer disposed in the iron-based porous
substance free from the connector and exhibiting a porosity smaller
than that of the connector; and the connector being impregnated
with the cast-wrapping member, and solidifying therewith, thereby
firmly bonding the iron-based porous substance and the
cast-wrapping member.
2. The composited cast member set forth in claim 1, wherein the
connector exhibits a porosity of from 25 to 50% by volume, and the
reinforcer exhibits a porosity of from 5 to 25% by volume.
3. The composited cast member set forth in claim 1, wherein the
porosity decreases from large to small in a gradient manner from
the connector to the reinforcer.
4. The composited cast member set forth in claim 1, wherein the
iron-based porous substance comprises an iron-based porous sintered
substance which is made by sintering a powder compact formed by
pressing a ferrous powder whose major component is Fe.
5. The composited cast member set forth in claim 1, wherein the
iron-based porous substance is formed as a cylinder-shaped member
in which the connector is disposed on an outer peripheral side and
the reinforcer is disposed on an inner peripheral side, and the
reinforcer is subjected to an internal pressure.
6. A process for producing the composited cast member set forth in
claim 1, the process comprising the steps of: impregnating an
iron-based porous substance with a molten metal for making a
cast-wrapping member by pouring the molten meal into a cavity of a
mold in which the iron-based porous substance is disposed, the
iron-based porous substance comprising a connector whose major
component is Fe, having a large number of pores and exhibiting a
predetermined porosity, and a high-strength reinforcer exhibiting a
porosity smaller than that of the connector, the molten metal
comprising a metal whose major component is at least one member
selected from the group consisting of Al and Mg, thereby
impregnating the iron-based porous substance with the molten metal
inward from the connector into the iron-based porous substance; and
solidifying the molten metal by cooling after the impregnating
step; thereby producing a composited cast member in which the
iron-based porous substance is firmly bonded to the cast-wrapping
member at the connector, and is cast-wrapped by the cast-wrapping
member.
7. An iron-based porous substance used in the composited cast
member set forth in claim 1, the iron-based porous substance
comprising Fe, having a large number of pores and being
cast-wrapped by a cast-wrapping member comprising a metal whose
major component is at least one member selected from the group
consisting of Al and Mg, and the iron-based porous substance
further comprising: a connector disposed adjacent to a potential
boundary between the iron-based porous substance and the
cast-wrapping member, and exhibiting a predetermined porosity; and
a high-strength reinforcer disposed in the iron-based porous
substance free from the connector, and exhibiting a porosity
smaller than that of the connector.
8. A process for producing the iron-based porous substance set
forth in claim 7, the process comprising the steps of: laminating a
first powder compact exhibiting a predetermined porosity, the first
powder compact formed by pressing a ferrous powder whose major
component is Fe, on a second powder compact exhibiting a smaller
porosity than that of the first powder compact, the second powder
compact formed by pressing the ferrous powder, thereby making a
laminated powder compact; and sintering the laminated powder
compact, thereby producing an iron-based porous sintered substance
comprising a connector formed of the first powder compact and
exhibiting a predetermined porosity, and a high-strength reinforcer
formed of the second powder compact and exhibiting a smaller
porosity than that of the connector.
9. A process for producing the iron-based porous substance set
forth in claim 7, the process comprising the steps of: producing a
powder compact by pressing a first powdery portion comprising a
mixture powder of a ferrous powder whose major component is Fe and
a pore-making material forming pores by disappearing when being
heated at temperatures of a sintering temperature of the ferrous
powder or less, and a second powdery portion comprising the ferrous
powder more than the first powdery portion does and the pore-making
material less than the first powdery portion does; and sintering
the powder compact, thereby producing an iron-based porous sintered
substance in which the first powdery portion is turned into a
connector exhibiting a predetermined porosity and the second powder
portion is turned into a high-strength reinforcer exhibiting a
smaller porosity than that of the connector.
10. A pressure casing, at least a part of the pressure casing
comprising a composited cast member, the composited cast member
comprising: an iron-based porous substance comprising Fe and having
a large number of pores; and a cast-wrapping member comprising a
metal whose major component is at least one member selected from
the group consisting of Al and Mg and cast-wrapping a part of the
iron-based porous substance at least; the iron-based porous
substance further comprising a connector disposed adjacent to a
boundary between the iron-based porous substance and the
cast-wrapping member and exhibiting a predetermined porosity, and a
high-strength reinforcer disposed in the iron-based porous
substance free from the connector and exhibiting a porosity smaller
than that of the connector; and the connector being impregnated
with the cast-wrapping member, and solidifying therewith, thereby
firmly bonding the iron-based porous substance and the
cast-wrapping member.
11. The pressure casing set forth in claim 10, wherein the
iron-based porous substance and the composited cast member are
formed as a cylinder-shaped member, respectively, and the pressure
casing is subjected to an internal pressure exerted from an inner
peripheral side of the composited cast member.
12. The pressure casing set forth in claim 11, wherein the
iron-based porous substance comprises the connector disposed on an
outer peripheral side, and the reinforcer disposed on an inner
peripheral side; and the composited cast member comprises the
iron-based porous substance, and the cast-wrapping member
cast-wrapping around the connector of the iron-based porous
substance.
13. A process for producing the pressure casing set forth in claim
10, comprising the steps of: impregnating an iron-based porous
substance with a molten metal for making a cast-wrapping member by
pouring the molten meal into a cavity of a mold in which the
iron-based porous substance is disposed, the iron-based porous
substance comprising a connector whose major component is Fe,
having a large number of pores and exhibiting a predetermined
porosity, and a high-strength reinforcer exhibiting a porosity
smaller than that of the connector, the molten metal comprising a
metal whose major component is at least one member selected from
the group consisting of Al and Mg, thereby impregnating the
iron-based porous substance with the molten metal inward from the
connector into the iron-based porous substance; and solidifying the
molten metal by cooling after the impregnating step; thereby
producing a pressure casing partially provided with a composited
cast member in which the iron-based porous substance is firmly
bonded to the cast-wrapping member at the connector, and is
cast-wrapped by the cast-wrapping member.
14. A constituent member of compressors which compress an intake
working fluid and discharge the highly pressurized working fluid,
at least a part of the constituent member comprising: a composited
cast member comprising: an iron-based porous substance comprising
Fe and having a large number of pores; and a cast-wrapping member
comprising a metal whose major component is at least one member
selected from the group consisting of Al and Mg, and cast-wrapping
a part of the iron-based porous substance at least; the iron-based
porous substance further comprising a connector disposed adjacent
to a boundary between the iron-based porous substance and the
cast-wrapping member and exhibiting a predetermined porosity, and a
high-strength reinforcer disposed in the iron-based porous
substance free from the connector and exhibiting a porosity smaller
than that of the connector, the connector being impregnated with
the cast-wrapping member and solidifying therewith, thereby firmly
bonding the iron-based porous substance and the cast-wrapping
member in the composited cast member.
15. A compressor, comprising: the constituent member set forth in
claim 14.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a composited cast member in
which an iron-based porous substance is wrapped with a light alloy,
an iron-based porous substance used in the composited cast member,
a pressure casing provided with the composited cast member,
processes for producing the same, a constituent member of
compressors, an example of the composited cast member or pressure
casing, and the compressors.
[0003] 2. Description of the Related Art
[0004] In view of weight saving, outputting higher power and
recycling, raw materials for various component parts are changing
from iron-based materials, such as iron, steels and cast steels, to
light metallic materials, such as aluminum alloys and magnesium
alloys. However, when such light alloy materials substitute for the
entire component members, it is difficult to secure strength,
rigidity, slidability, wear resistance and durability. Accordingly,
composited cast products have been used which are made by
cast-wrapping light-metal molten alloys around composite materials
or iron-based component parts disposed only at parts which require
a high sliding characteristic, for example. Note that the
"composited cast member" set forth in the present specification
includes the composited cast products. The composite materials
comprise host materials composed of light metals, and reinforcement
members, such as ceramic fibers and ceramic particles, dispersed in
the host materials.
[0005] As for actual applications, there are the cylinder blocks of
engines, especially, the cylinder liners. In the cylinder blocks,
the weights have been saved by using aluminum cast products as the
bodies, and simultaneously the required wear resistance and seizure
resistance have been secured by using the aforementioned composite
materials the cylinder liners or cast-wrapping sleeves made of cast
steels with the composite materials.
[0006] However, it cannot necessarily be said that the weight
saving of cylinder blocks is fully achieved when sleeves made of
cast steels are cast-wrapped by light metallic materials. Moreover,
in this instance, the adhesiveness is poor at the interface between
cast-steel sleeves and cast-wrapping members composed of light
metallic material, such as aluminum alloys, for example, and
consequently the cast-steel sleeves and cast-wrapping members might
be separated at the interface during the service as cylinder
blocks. In order to satisfy the weight saving and adhesive
requirements at the same time, iron-based porous substances have
been disposed in aluminum alloy cast products, that is, iron-based
porous substances have been cast-wrapped in aluminum alloy cast
products. Japanese Unexamined Patent Publication (KOKAI) No.
7-124,738, Japanese Unexamined Patent Publication (KOKAI) No.
9-24,456, Japanese Unexamined Patent Publication (KOKAI) No.
2003-181,620 and Japanese Unexamined Patent Publication (KOKAI) No.
2003-181,622 deal with such technologies.
[0007] As for the applications of composite materials, Japanese
Examined Patent Publication (KOKOKU) No. 63-40,943 sets forth the
applications of composite materials to cylinder liners. Japanese
Unexamined Patent Publication (KOKAI) No. 11-293,364 sets forth the
applications of composite materials to the swash plates of swash
type compressors.
[0008] In the case of composited cast members in which iron-based
porous substances are cast-wrapped with cast-wrapping materials
composed of light alloys, it is expected that the iron-based porous
substances upgrade the strength of the composited cast members.
When the porosity of iron-based porous substances is large, that
is, when the volume fraction of iron (V.sub.f) is less, such
iron-based porous substances cannot demonstrate a sufficient
reinforcement effect naturally. On the other hand, when the
porosity of iron-based porous substances is small, that is, when
the volume fraction of iron (V.sub.f) is much, the strength of
composited cast members upgrades, but cast-wrapping materials are
less likely to impregnate into iron-based porous substances.
Accordingly, the adhesiveness between iron-based porous substances
and cast-wrapping members are likely to degrade. When separations
occur between iron-based porous substances and cast-wrapping
members, or when one of them comes off from the other, only
iron-based porous substances are responsible for the strength
substantially. Consequently, it is hardly possible to expect to
strengthen composited cast members as a whole.
[0009] Japanese Unexamined Patent Publication (KOKAI) No. 7-124,738
and Japanese Unexamined Patent Publication (KOKAI) No. 9-24,456
suggest to add beryllium (Be) into molten metals in an appropriate
amount in order to improve the adhesiveness. However, it is not
preferable to add harmful Be. Japanese Unexamined Patent
Publication (KOKAI) No. 2003-181,620 and Japanese Unexamined Patent
Publication (KOKAI) No. 2003-181,622 disclose composited cast
members in which porous substances made of stainless steels are
cast-wrapped with aluminum alloys. However, the V.sub.f of the
porous substances is as low as from 10 to 30% by volume. As a
result, although the resulting composited cast members can secure
wear resistance as cylinder liners, it is hardly expected for the
porous substances to produce the reinforcement effect as expected
from composited cast members as a whole.
[0010] The use of composite materials is not suitable for
mass-produced products which are required to be produced at low
cost, because ceramic fibers, the reinforcement members, are
expensive. Moreover, component parts using composite materials
exhibit poor processability, because ceramic fibers are very
hard.
SUMMARY OF THE INVENTION
[0011] The present invention has been developed in view of the
aforementioned circumstances. It is therefore an object of the
present invention to provide a composited cast member in which an
iron-based porous substance demonstrates the reinforcement effect
fully while securing firm adhesiveness between the iron-based
porous substance and a cast-wrapping member.
[0012] Moreover, it is another object of the present invention to
provide an iron-based porous substance used in composited cast
members, and a pressure casing provided with a composited cast
member. It is a further object of the present invention to provide
processes for producing the same. It is a furthermore object of the
present invention to provide a constituent member of compressors,
an example of pressure casings, and the compressors.
[0013] Hence, the present inventors have been studying earnestly in
order to solve the problems, and have been repeated trials and
errors. As a result, they have thought of changing the porosity of
iron-based porous substances at parts thereof, iron-based
substances which are cast-wrapped in cast-wrapping members. Based
on the idea, they have arrived at completing the present
invention.
(Composited Cast Member)
[0014] For example, a composited cast member according to the
present invention comprises:
[0015] an iron-based porous substance comprising iron (Fe), and
having a large number of pores; and
[0016] a cast-wrapping member comprising a metal whose major
component is at least one member selected from the group consisting
of aluminum (Al) and magnesium (Mg), and cast-wrapping a part of
the iron-based porous substance at least;
[0017] the iron-based porous substance further comprising a
connector disposed adjacent to a boundary between the iron-based
porous substance and the cast-wrapping member and exhibiting a
predetermined porosity, and a high-strength reinforcer disposed in
the iron-based porous substance free from the connector and
exhibiting a porosity smaller than that of the connector; and
[0018] the connector being impregnated with the cast-wrapping
member, and solidifying therewith, thereby firmly bonding the
iron-based porous substance and the cast-wrapping member.
[0019] Note that the term, "metal," herein means pure metals and
alloy. Moreover, the compositions of the iron-based porous
substance and cast-wrapping member depend on actual
applications.
[0020] Firstly, the iron-based porous substance according to the
present invention exhibits a large porosity at the connector making
the boundary between the iron-based porous substance and the
cast-wrapping member. Accordingly, when the iron-based porous
substance is actually cast-wrapped in the cast-wrapping member, the
connector is impregnated with a large amount of the molten metal of
the cast-wrapping member, and solidifies therewith. As a result, a
great anchor effect arises at least between the cast-wrapping
member and the connector of the iron-based porous substance so that
a mechanically firm bond is established between the iron-based
porous substance and the cast-wrapping member. Of course, it is
believed that a chemical bond might possibly be established between
them. Anyway, the iron-based porous substance and the cast-wrapping
member are bonded or joined firmly at the boundary of the
iron-based porous substance which contacts with the cast-wrapping
member directly. Consequently, separations are fully inhibited from
occurring between the iron-based porous substances and
cast-wrapping members, and one of them is also fully inhibited from
coming off from the other.
[0021] Secondly, the iron-based porous substance according to the
present invention comprises the reinforcer in addition to the
connector. The reinforcer exhibits high strength, because it
exhibits a smaller porosity and higher density, that is, because
the V.sub.f of the reinforcer is high. Therefore, the iron-based
porous substance comprising the reinforcer can fully reinforce the
cast-wrapping material of relatively low strength. Note that the
reinforcer is disposed in the iron-based porous substance free from
the connector, but all of the iron-based porous substance free from
the connector cannot necessarily be turned into the reinforcer. As
far as the strength required for composited cast members is secured
depending on their applications, the position or proportion of the
reinforcer do not matter. For example, when the entire surface of
the iron-based porous substance is cast-wrapped by the
cast-wrapping member completely, the connector can be disposed on
the entire outer peripheral surface of the iron-based porous
substance, and the reinforcer can be disposed at the center or in
the middle of the iron-based porous substance. When only one of the
opposite surfaces of the iron-based porous substance is
cast-wrapped by the cast-wrapping member, the connector can be
disposed on the opposite surface of the iron-based porous
substance, and the reinforcer can be disposed on the other one of
the opposite surfaces of the iron-based porous substance.
[0022] Thus, the present composited cast member fully secures the
adhesiveness between the iron-based porous substance and the
cast-wrapping member. Simultaneously therewith, the iron-based
porous substance demonstrates the reinforcement effect stably and
securely, because the iron-based porous substance comprises the
high-strength reinforcer.
(Process for Producing Composited Cast Member)
[0023] It is possible to grasp the present invention not only as
the above-described composited cast member but also as a process
for producing the same. For instance, the present invention can be
adapted to a process for producing a composited cast member, the
process comprising the steps of:
[0024] impregnating an iron-based porous substance with a molten
metal for making a cast-wrapping member by pouring the molten meal
into a cavity of a mold in which the iron-based porous substance is
disposed, the iron-based porous substance comprising a connector
whose major component is Fe, having a large number of pores and
exhibiting a predetermined porosity, and a high-strength reinforcer
exhibiting a porosity smaller than that of the connector, the
molten metal comprising a metal whose major component is at least
one member selected from the group consisting of Al and Mg, thereby
impregnating the iron-based porous substance with the molten metal
inward from the connector into the iron-based porous substance;
and
[0025] solidifying the molten metal by cooling after the
impregnating step;
[0026] thereby producing a composited cast member in which the
iron-based porous substance is firmly bonded to the cast-wrapping
member at the connector, and is cast-wrapped by the cast-wrapping
member.
(Iron-Based Porous Substance for Composited Cast Members)
[0027] It is possible to grasp the present invention not only as
the above-described composited cast member but also as an
iron-based porous substance used in the same. For example, the
present invention can be adapted to an iron-based porous substance
comprising Fe, having a large number of pores and being
cast-wrapped by a cast-wrapping member comprising a metal whose
major component is at least one member selected from the group
consisting of Al and Mg, and the iron-based porous substance
further comprising:
[0028] a connector disposed adjacent to a potential boundary
between the iron-based porous substance and the cast-wrapping
member, and exhibiting a predetermined porosity; and
[0029] a high-strength reinforcer disposed in the iron-based porous
substance free from the connector, and exhibiting a porosity
smaller than that of the connector.
(Process for Producing Iron-Based Porous Substance for Composited
Cast Members)
[0030] It is possible to grasp the present invention not only as
the above-described iron-based porous substance for composited cast
members but also as a process for producing the same.
[0031] (1) For instance, the present invention can be adapted to a
process for producing an iron-based porous substance for composited
cast members, the process comprising the steps of:
[0032] laminating a first powder compact exhibiting a predetermined
porosity, the first powder compact formed by pressing a ferrous
powder whose major component is Fe, on a second powder compact
exhibiting a smaller porosity than that of the first powder
compact, the second powder compact formed by pressing the ferrous
powder, thereby making a laminated powder compact; and
[0033] sintering the laminated powder compact, thereby producing an
iron-based porous sintered substance comprising a connector formed
of the first powder compact and exhibiting a predetermined
porosity, and a high-strength reinforcer formed of the second
powder compact and exhibiting a smaller porosity than that of the
connector.
[0034] In the present production process, the powder compacts whose
porosities differ with each other are formed independently of each
other. Accordingly, the degree of freedom enlarges in controlling
the porosities, or in selecting raw materials to be used. As a
result, the porosities or strengths can be controlled with ease
depending on the parts of the resulting iron-based porous sintered
substance, and consequently it is easy to produce the iron-based
porous sintered substance whose porosity or strength is optimized.
Note that the laminated powder compact produced after the
laminating step and the iron-based porous sintered substance
comprise two layers at least, but can naturally comprise three
layers or more.
[0035] (2) Moreover, the present invention can be adapted to a
process for producing an iron-based porous substance for composited
cast members, the process comprising the steps of:
[0036] producing a powder compact by pressing a first powdery
portion comprising a mixture powder of a ferrous powder whose major
component is Fe and a pore-making material forming pores by
disappearing when being heated at temperatures of a sintering
temperature of the ferrous powder or less, and a second powdery
portion comprising the ferrous powder more than the first powdery
portion does and the pore-making material less than the first
powdery portion does; and
[0037] sintering the powder compact, thereby producing an
iron-based porous sintered substance in which the first powdery
portion is turned into a connector exhibiting a predetermined
porosity and the second powder portion is turned into a
high-strength reinforcer exhibiting a smaller porosity than that of
the connector.
[0038] In the present production process, the pore-making material
is mixed abundantly in the portion (i.e., the first powdery
portion) which is turned into the connector in the powder compact
so that the portion is adapted to the connector whose porosity is
larger after sintering. In the present production process, it is
possible to readily control the porosity of the iron-based porous
sintered substance produced after sintering by changing the mixing
proportion of the pore-making material. Moreover, not only it is
easy to control the porosity of the iron-based porous sintered
substance, but also it is easy to control the strength of the
iron-based porous sintered substance at parts thereof. In addition,
the present production process is very efficient, because the
forming step can be finished at once in the following manner.
Specifically, the ferrous powder and pore-making material whose
mixing proportions are changed at the parts of the resulting
iron-based porous sintered substance are formed by simply pressing
them immediately after filling them into the cavity of forming
molds.
[0039] Note that, in the present production process as well, the
mixing proportions of the ferrous powder and pore-making material
can be changed stepwise not only in two stages but also in three
stages or more. Moreover, the mixing proportions can be changed
from the first powdery portion to the second powder portion
gradiently. In addition, the second powdery portion can include a
trace amount of the pore-making material, but the content of the
pore-making material can be none.
[0040] The pore-making material herein can be metallic powders
which exhibit melting points lower than the sintering temperature
of the ferrous powder, or can be those which burn in
high-temperature ranges (e.g., around the sintering temperature of
the ferrous powder) and dissipate so that they can be removed by
emission. For example, the former can be at least one member
selected from the group consisting of Cu, Sn, Pb, Zn, Ag, Mg, Ca,
Sr and Al powders, and the latter can be at least one member
selected from the group consisting of binders, lubricants and
resinous powders. Note that the phrase, "the pore-making material
disappears," means not only that the components of the pore-making
material are removed out of the iron-based porous sintered
substance completely, but also that the pore-making material melts
to adhere onto the particulate surface of the ferrous powder or to
diffuse into Fe, be taken therein or be alloyed therewith
eventually.
(Pressure Casing)
[0041] It is possible to grasp the present invention as a pressure
casing, an application of the above-described composited cast
member. For example, a pressure casing according to the present
invention, at least a part of the present pressure casing comprises
a composited cast member, the composited cast member
comprising:
[0042] an iron-based porous substance comprising Fe and having a
large number of pores; and
[0043] a cast-wrapping member comprising a metal whose major
component is at least one member selected from the group consisting
of Al and Mg and cast-wrapping a part of the iron-based porous
substance at least;
[0044] the iron-based porous substance further comprising a
connector disposed adjacent to a boundary between the iron-based
porous substance and the cast-wrapping member and exhibiting a
predetermined porosity, and a high-strength reinforcer disposed in
the iron-based porous substance free from the connector and
exhibiting a porosity smaller than that of the connector; and
[0045] the connector being impregnated with the cast-wrapping
member, and solidifying therewith, thereby firmly bonding the
iron-based porous substance and the cast-wrapping member.
[0046] The present pressure casing fully secures the adhesiveness
between the iron-based porous substance and the cast-wrapping
member in the same manner as the above-described composited cast
member. Simultaneously therewith, the iron-based porous substance
demonstrates the reinforcement effect stably and securely, because
the iron-based porous substance comprises the high-strength
reinforcer. Thus, the present pressure casing effects not only the
advantages of weight saving but also sufficient strength.
[0047] The pressure casing according to the present invention can
be pressure vessels, such as tanks and bombs, which hold highly
pressurized fluids (e.g., gases and liquids) therein, can be
cylinders for engines and compressors, or can be pipes for
plumbing. The pressure casing forms an enclosed space as a whole,
because it accommodates highly pressurized fluids therein. However,
it is not required that the entire pressure casing comprises a
single component part. For example, like cylinders or housings for
engines and compressors, the pressure casing can comprise a
cylinder-shaped component part (e.g., cylinder bore), a piston, a
cylinder head or a valve plate to form the enclosed space. Note
that any one of the component parts can comprise the present
pressure casing.
[0048] However, a representative example of the present pressure
casing can be cylinders themselves, or cylinder-shaped component
parts, such as cylinder blocks and housings, which surround the
cylinders. If such is the case, the present iron-based porous
substance or the present pressure casing is adapted to
cylinder-shaped component parts. In this instance, note that an
internal pressure acts outward from the inner peripheral side of
the pressure casing. Accordingly, in such cylinder-shaped component
parts, the inner peripheral surface is likely to be subjected to
the maximum stress. Consequently, the inner peripheral surface can
preferably be reinforced by the reinforcer of the iron-based porous
substance effectively. Therefore, it is appropriate that the
iron-based porous substance of the present pressure casing can
comprise the connector disposed on an outer peripheral side, and
the reinforcer disposed on an inner peripheral side; and
[0049] the composited cast member comprises the iron-based porous
substance, and the cast-wrapping member cast-wrapping around the
connector of the iron-based porous substance.
(Process for Producing Pressure Casing)
[0050] Not limited to the above-described pressure casing, it is
possible to grasp the present invention as a process for producing
the same. For instance, the present invention can be adapted to a
process for producing a pressure casing comprises the steps of:
[0051] impregnating an iron-based porous substance with a molten
metal for making a cast-wrapping member by pouring the molten meal
into a cavity of a mold in which the iron-based porous substance is
disposed, the iron-based porous substance comprising a connector
whose major component is Fe, having a large number of pores and
exhibiting a predetermined porosity, and a high-strength reinforcer
exhibiting a porosity smaller than that of the connector, the
molten metal comprising a metal whose major component is at least
one member selected from the group consisting of Al and Mg, thereby
impregnating the iron-based porous substance with the molten metal
inward from the connector into the iron-based porous substance;
and
[0052] solidifying the molten metal by cooling after the
impregnating step;
[0053] thereby producing a pressure casing partially provided with
a composited cast member in which the iron-based porous substance
is firmly bonded to the cast-wrapping member at the connector, and
is cast-wrapped by the cast-wrapping member.
(Constituent Member of Compressors)
[0054] A representative example of the above-described present
pressure casing can be compressors and their constituent members.
Hence, not limited to the present pressure casing using the present
composited cast member, it is possible to grasp the present
invention as a constituent member of compressors using the
composited cast member.
[0055] For example, the present invention can be adapted to a
constituent member of compressors which compress an intake working
fluid and discharge the highly pressurized working fluid, at least
a part of the constituent member comprising:
[0056] a composited cast member comprising:
[0057] an iron-based porous substance comprising Fe and having a
large number of pores; and
[0058] a cast-wrapping member comprising a metal whose major
component is at least one member selected from the group consisting
of Al and Mg, and cast-wrapping a part of the iron-based porous
substance at least;
[0059] the iron-based porous substance further comprising a
connector disposed adjacent to a boundary between the iron-based
porous substance and the cast-wrapping member and exhibiting a
predetermined porosity, and a high-strength reinforcer disposed in
the iron-based porous substance free from the connector and
exhibiting a porosity smaller than that of the connector, the
connector being impregnated with the cast-wrapping member and
solidifying therewith, thereby firmly bonding the iron-based porous
substance and the cast-wrapping member in the composited cast
member.
(Compressor)
[0060] Not limited to the above-described constituent member of
compressors, it is possible to grasp the present invention as a
compressor comprising the constituent member. For instance, the
present invention can be adapted to a compressor which compress an
intake working fluid and discharge the highly pressurized working
fluid, at least a part of the constituent member comprising:
[0061] a composited cast member comprising:
[0062] an iron-based porous substance comprising Fe and having a
large number of pores; and
[0063] a cast-wrapping member comprising a metal whose major
component is at least one member selected from the group consisting
of Al and Mg, and cast-wrapping a part of the iron-based porous
substance at least;
[0064] the iron-based porous substance further comprising a
connector disposed adjacent to a boundary between the iron-based
porous substance and the cast-wrapping member and exhibiting a
predetermined porosity, and a high-strength reinforcer disposed in
the iron-based porous substance free from the connector and
exhibiting a porosity smaller than that of the connector, the
connector being impregnated with the cast-wrapping member and
solidifying therewith, thereby firmly bonding the iron-based porous
substance and the cast-wrapping member in the composited cast
member.
[0065] Note that the extent of porosity and the magnitude of
strength according to the present invention are the relative
relationships between the connector and reinforcer of the
iron-based porous substance.
BRIEF DESCRIPTION OF THE DRAWINGS
[0066] A more complete appreciation of the present invention and
many of its advantages will be readily obtained as the same becomes
better understood by reference to the following detailed
description when considered in connection with the accompanying
drawings and detailed specification, all of which forms a part of
the disclosure.
[0067] FIG. 1 is a perspective view for illustrating an outline of
a housing of a compressor according to Example No. 1 of the present
invention.
[0068] FIG. 2 is an enlarged view of the housing designated at "2"
of FIG. 1.
[0069] FIG. 3 is a schematic diagram for illustrating an iron-based
porous sintered substance according to Example No. 1 of the present
invention, wherein FIG. 3(a) is the perspective view; and FIG. 3(b)
is the cross-sectional view of the iron-based porous sintered
substance along the center axis.
[0070] FIG. 4 is a metallographic photograph of a composited cast
member according to Example No. 1 of the present invention, and
shows a portion adjacent to a connector of the iron-based porous
substance.
[0071] FIG. 5 is a side view for illustrating an outline of a
housing according to Example No. 2 of the present invention for
compressors.
[0072] FIG. 6 is a front view for illustrating an outline of a
housing according to Example No. 3 of the present invention for
compressors.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0073] Having generally described the present invention, a further
understanding can be obtained by reference to the specific
preferred embodiments which are provided herein for the purpose of
illustration only and not intended to limit the scope of the
appended claims.
[0074] The present invention will be hereinafter described in
detail with reference to specific embodiments of the present
invention. However, it should be noted that, not to mention the
following descriptions on the specific embodiments, descriptions
set forth in the present specification are appropriately applicable
not only to the composited cast member according to the present
invention but also to the iron-based porous substance, pressure
casing and processes for producing the same according to the
present invention, and further to the compressor and constituent
members thereof according to the present invention. Moreover, it
should be also noted that it depends on objects and performance
requirements which one of the following specific embodiments is
optimal.
(1) Iron-Based Porous Substance
[0075] The shapes and production processes of the present
iron-based porous substance for composited cast members do not
matter as far as the present iron-based porous substance comprises
the connector and the reinforcer. A representative example of such
an iron-based porous substance for composite cast members is
iron-based porous sintered substances. One of the iron-based porous
sintered substances will be hereinafter described in detail.
[0076] The iron-based porous sintered substance is made by
sintering a powder compact comprising a ferrous powder. The powder
compact is produced by pressing a ferrous powder filled in a cavity
of molds. The composition of the ferrous powder used herein can be
selected appropriately depending on the strength and service
environments of the iron-based porous sintered substance. For
example, when intending to upgrade the strength by heat treatments,
it is advisable to use ferrous powders with the compositions of
various alloy steels. When intending to enhance the corrosion
resistance, it is advisable to use ferrous powders with the
compositions of stainless steels. Additionally, the ferrous powder
can be pure iron powders, or ferrous powders with the compositions
of carbon steels. Note that the ferrous powder can be an
independent single powder, or a mixture powder in which a plurality
of powders are mixed.
[0077] The powder used herein can be either elemental powders or
alloy powders. The types of using powder can be either atomized
powders or reduced powders. The particulate shapes of using powder
do not matter. Moreover, the compositions or types of the ferrous
powder can be changed depending on parts of the iron-based porous
sintered substance. In particular, when it is desirable to enlarge
the porosity, it is not preferable to use fine powders having
extremely small particle diameters. However, it is preferable to
use a ferrous powder whose average particle diameter falls in a
range of from 50 to 150 .mu.m approximately, for instance. Note
that the particle diameter of constituent particles can be
determined by analyzing the two-dimensional images, but can be
determined with ease by using sieving methods.
[0078] The ferrous powder is not limited to metallic powders, but
can be mixture powders which include the above-described
pore-making material in addition to lubricants and additives.
Moreover, the ferrous powder can further include compound powders,
such as powders composed of ceramic particles serving as
reinforcement particles.
[0079] Note that the porosity of the iron-based porous sintered
substance can be determined by the following equation using the
apparent density p and the true density .rho..sub.0of constituent
materials:
Porosity={1-(.rho./.rho..sub.0)}.times.100(%)
[0080] For reference, the right side of the equation,
{1-(.rho./.rho..sub.0)}.times.100(%), specifies the volume fraction
of the iron-based porous sintered substance (V.sub.f).
[0081] It is appropriate that the porosity can fall in a range of
from 20 to 50% by volume, more appropriately from 35 to 45% by
volume, at the connector. When the porosity is to small, no
sufficient adhesiveness is obtained because the bondability of the
iron-based porous sintered substance was poor to the cast-wrapping
member. It is difficult to produce iron-based porous sintered
substances whose porosity is too large, and it is less likely to
secure the strength for serving as the connector. On the other
hand, the porosity of the reinforcer can appropriately fall in a
range of from 5 to 25% by volume, more appropriately from 5 to 15%
by volume. When the porosity of the reinforcer is too large, the
strength of iron-based porous sintered substances degrades so that
the reinforcer is less likely to demonstrate the reinforcement
effect. Moreover, it is not efficient to make the porosity of the
reinforcer too small, because it is required to press a raw
material powder with high pressures.
(Process for Producing Iron-Based Porous Substance)
[0082] It does not matter that the present iron-based porous
substance is produced by whatever production processes.
Specifically, the present iron-based porous substance can be
produced by the following production processes. For example, it is
possible to use a process for producing an iron-based porous
substance being cast-wrapped. This production process comprises the
steps of:
[0083] laminating a first powder compact exhibiting a predetermined
porosity, the first powder compact formed by pressing a ferrous
powder whose major component is Fe, on a second powder compact
exhibiting a smaller porosity than that of the first powder
compact, the second powder compact formed by pressing the ferrous
powder, thereby making a laminated powder compact; and
[0084] sintering the laminated powder compact, thereby producing an
iron-based porous sintered substance comprising a connector formed
of the first powder compact and exhibiting a predetermined
porosity, and a high-strength reinforcer formed of the second
powder compact and exhibiting a smaller porosity than that of the
connector.
[0085] In the present production process, the powder compacts whose
porosities differ with each other are formed independently of each
other. Accordingly, the degree of freedom enlarges in controlling
the porosities, or in selecting raw materials to be used. As a
result, the porosities or strengths can be controlled with ease
depending on the parts of the resulting iron-based porous sintered
substance, and consequently it is easy to produce the iron-based
porous sintered substance whose porosity or strength is optimized.
Note that the laminated powder compact produced after the
laminating step and the iron-based porous sintered substance
comprise two layers at least, but can naturally comprise three
layers or more.
[0086] Moreover, it is possible as well to use another process for
producing an iron-based porous substance being cast-wrapped. For
instance, the production process comprises the steps of:
[0087] producing a powder compact by pressing a first powdery
portion comprising a mixture powder of a ferrous powder whose major
component is Fe and a pore-making material forming pores by
disappearing when being heated at temperatures of a sintering
temperature of the ferrous powder or less, and a second powdery
portion comprising the ferrous powder more than the first powdery
portion does and the pore-making material less than the first
powdery portion does; and
[0088] sintering the powder compact, thereby producing an
iron-based porous sintered substance in which the first powdery
portion is turned into a connector exhibiting a predetermined
porosity and the second powder portion is turned into a
high-strength reinforcer exhibiting a smaller porosity than that of
the connector.
[0089] In the present production process, the pore-making material
is mixed abundantly in the portion (i.e., the first powdery
portion) which is turned into the connector in the powder compact
so that the portion is adapted to the connector whose porosity is
larger after sintering. In the present production process, it is
possible to readily control the porosity of the iron-based porous
sintered substance produced after sintering by changing the mixing
proportion of the pore-making material. Moreover, not only it is
easy to control the porosity of the iron-based porous sintered
substance, but also it is easy to control the strength of the
iron-based porous sintered substance at parts thereof. In addition,
the present production process is very efficient, because the
forming step can be finished at once in the following manner.
Specifically, the ferrous powder and pore-making material whose
mixing proportions are changed at the parts of the resulting
iron-based porous sintered substance are formed by simply pressing
them immediately after filling them into the cavity of forming
molds.
[0090] Note that, in the present production process as well, the
mixing proportions of the ferrous powder and pore-making material
can be changed stepwise not only in two stages but also in three
stages or more. Moreover, the mixing proportions can be changed
from the first powdery portion to the second powder portion
gradiently. In addition, the second powdery portion can include a
trace amount of the pore-making material, but the content of the
pore-making material can be none.
[0091] The pore-making material herein can be metallic powders
which exhibit melting points lower than the sintering temperature
of the ferrous powder, or can be those which burn in
high-temperature ranges (e.g., around the sintering temperature of
the ferrous powder) and dissipate so that they can be removed by
emission. For example, the former can be at least one member
selected from the group consisting of Cu, Sn, Pb, Zn, Ag, Mg, Ca,
Sr and Al powders, and the latter can be at least one member
selected from the group consisting of binders, lubricants and
resinous powders. Note that the phrase, "the pore-making material
disappears," means not only that the components of the pore-making
material are removed out of the iron-based porous sintered
substance completely, but also that the pore-making material melts
to adhere onto the particulate surface of the ferrous powder or to
diffuse into Fe, be taken therein or be alloyed therewith
eventually.
(2) Cast-Wrapping Member
[0092] The cast-wrapping member comprises at least one member
selected from the group consisting of pure Al, Al alloys, pure Mg
and Mg alloys. The compositions of alloys do not matter, however,
it is possible to use various wrought alloys as stipulated in
Japanese Industrial Standards. Appropriate alloys can be selected
depending on the specifications of composite cast members, pressure
casings and compressors. The following methods are available for
casting: gravity casting; pressure casting; sand casting; and die
casting, for example. However, it is preferable to carry out
pressure casting using a mold, especially, liquid forging, in order
to securely impregnate iron-based porous substances with molten
alloys for making the cast-wrapping member. However, taking the
mass-producibility into consideration, die casting can be used. The
following solidifying step can be carried out by natural cooling.
However, when cooling methods, such as water cooling, whose cooling
rates are fast, the cast structure of the cast-wrapping member is
micro-fined so that it is possible to upgrade the strength of the
resulting composited cast member as a whole.
(3) Applications
[0093] The present composited cast member can be used in various
component parts and apparatuses. In particular, the present
composite cast member is appropriate for component parts which
require higher strength than that of cast products comprising the
cast-wrapping member alone, because the present composited cast
member is reinforced by the iron-based porous substance. For
example, such component parts can be cylinder blocks, various
housings of compressors, bone structural component parts, inner
shells or outer shells of pressure containers, and pipes for
plumbing.
[0094] Note that, when the present composited cast member is
adapted to component parts which are formed as cylinder shapes and
are subjected to internal pressures, for instance, bulkheads of
pressure vessels, the iron-based porous substance can appropriately
be formed as a cylinder shape in which the connector is disposed on
the outer peripheral side and the reinforcer is disposed on the
inner peripheral side. This is because the maximum stress arises on
the inner peripheral side of the present composited cast member or
iron-based porous substance.
[0095] The present pressure casing can be adapted to cylinder
sleeves, cylinder blocks and housing, which are used in pumps,
compressors or engines, bulkheads, and pipes for plumbing, in
addition to various pressure vessels. Note that the present
compressor and its constituent members are some of specific
embodiments of the present pressure casing.
EXAMPLES
(Example No. 1)
(Outline)
[0096] FIGS. 1 and 2 illustrate a cylinder-shaped housing 1 for
compressors, Example No. 1 of the present invention. Note that the
present composited cast member, constituent members of compressors
or pressure casing include the cylinder-shaped housing 1. FIG. 2 is
an enlarged view of an opposite end surface of the cylinder-shaped
housing 1 designated at "2" in FIG. 1. Moreover, as illustrated in
FIG. 1, the cylinder-shaped housing 1 is made on the assumption
that an internal pressure "P" resulting from a working fluid acts
outward from the inner peripheral side.
[0097] The housing 1 is a composited cast member which comprises a
cylinder-shaped iron-based porous sintered substance 11, and a
cast-wrapping member 12. The cast-wrapping member 12 is made by
casting a casting aluminum alloy around the outer peripheral
surface of the iron-based porous sintered substance 11. As
illustrated in FIG. 2, the iron-based porous sintered substance 11
comprises a reinforcer 11a, and a connector 11b. The reinforcer 11a
is disposed on the inner peripheral side of the iron-based porous
sintered substance 11, and exhibits a smaller porosity, that is,
exhibits a larger V.sub.f. The connector 11b is disposed on the
outer peripheral side of the iron-based porous sintered substance
11, and exhibits a larger porosity, that is, exhibits a smaller
V.sub.f. Moreover, the pores of the iron-based porous sintered
substance 11 are impregnated with the molten metal for making the
cast-wrapping member 12, and solidify therewith. In particular, in
the pores disposed in the connector 11b, the cast-wrapping member
12 has solidified firmly after the impregnation. Thus, the
iron-based porous sintered substance 11 and the cast-wrapping
member 12 are bonded firmly by an anchor effect.
(Production of Iron-Based Porous Sintered Substance)
[0098] The above-described cylinder-shaped iron-based porous
sintered substance 11 was produced as hereinafter described. As raw
material powders, the following powders were prepared: a reduced
iron powder serving as the ferrous powder; graphite (C); stearic
acid; a lubricant for powder metallurgy; and a copper powder. The
reduced iron powder comprised pure iron, was "KIP240M" made by
KAWASAKI SEITETSU Co., Ltd., and had an average particle diameter
of 75 .mu.m. The stearic acid had a melting point of 60.degree. C.
The lubricant was "W-02" made by DAIWA WAX Co., Ltd. The copper
powder was "CE-5" made by FUKUDA KINZOKU Co., Ltd., and had an
average particle diameter of 80 .mu.m. These raw material powders
were used to prepare a first mixture powder and a second mixture
powder (i.e., mixing step). Note that the first mixture powder
comprised 74% by mass Fe, 0.8% by mass C, and 3% by mass stearic
acid. The second mixture powder comprised 87% by mass Fe, 0.8% by
mass C, 2% by mass Cu, and 3% by mass stearic acid. Each of the
first mixture powder and the second mixture powder was mixed for 1
hour using a milling apparatus.
[0099] The first mixture powder was filled into a cylinder-shaped
cavity of a first mold (i.e., filling step), and was then formed by
pressing (i.e., forming step). Thus, a first powder compact was
produced whose inside diameter was .phi. 90 mm, outside diameter
was .phi. 100 mm and length was 50 mm. The second mixture powder
was filled into a cylinder-shaped cavity of a second mold (i.e.,
filling step), and was then formed by pressing (i.e., forming
step). Thus, a second powder compact was produced which was fitted
into the first powder compact and whose inside diameter was .phi.
80 mm, outside diameter was .phi. 90 mm and length was 50 mm. The
resulting first powder compact (i.e., outer shell) and second
powder compact (i.e., inner shell) were laminated by fitting the
second powder compact into the first powder compact, thereby making
a double-structured powder compact (i.e., laminating step).
[0100] The resultant powder compact was put in an electric furnace,
and was sintered by heating it at 1,100.degree. C. for 30 minutes
in an inert or vacuum atmosphere (i.e., sintering step). Thus, the
iron-based porous sintered substance 11 was produced whose inside
diameter was .phi. 80 mm, outside diameter was .phi. 100 mm and
length was 50 mm. The outer peripheral side of the iron-based
sintered porous substance 11 comprised the sintered first powder
compact, and exhibited a porosity of about 27% by volume. Note that
the connector 11b according to the present invention includes the
outer peripheral side of the iron-based sintered porous substance
11. The inner peripheral side of the iron-based sintered porous
substance 11 comprised the sintered second powder compact, and
exhibited a porosity of about 13% by volume. Note that the
reinforcer 11a according to the present invention includes the
inner peripheral side of the iron-based sintered porous substance
11. FIG. 3 illustrates schematically how the iron-based porous
sintered substance 11 appeared. Note that FIG. 3(a) is the
perspective view of the entire iron-based porous sintered substance
11; and FIG. 3(b) is the cross-sectional view of the iron-based
porous sintered substance 11 along the center axis.
(Production of Composited Cast Member)
[0101] The iron-based porous sintered substance 11 was cast-wrapped
with an aluminum alloy as per Japanese Industrial Standards 2024
which turned into the cast-wrapping member 12. Thus, a
cylinder-shaped composited cast member, that is, the housing 1, was
produced. The molten metal of the aluminum alloy was poured inward
from the outer peripheral side of the iron-based porous sintered
substance 11, that is, from the side of the connector 11b. In this
instance, the casting conditions were set so that the temperature
of the molten metal was 750.degree. C., the temperature of the mold
was 200.degree. C., the iron-based porous sintered substance 11 was
preheated to 300.degree. C., and the molten metal was pressurized
to 100 MPa. Thus, the iron-based porous sintered substance 11 was
impregnated with the molten metal of the aluminum alloy inward from
the connector 11b to the reinforcer 11a. Thereafter, the mold was
water-cooled to solidify the molten metal, thereby completing the
cylinder-shaped composited cast member.
[0102] FIG. 4 shows a metallographic photograph of the composited
cast member which was observed with an optical microscope after
cutting the composited cast member adjacent to the connector 11b
and etching the cut cross section of the metallic structure with 3%
alcoholic nitrate solution (or nital) for 15 seconds. From the
metallographic photograph, it is appreciated that the pores of the
connector 11b was densely impregnated with the molten metal of the
aluminum alloy and solidified therewith, and that the bonding was
firm between the iron-based porous sintered substance 11 and the
cast-wrapping member 12 (i.e., matrix).
[0103] Moreover, it is believed that the Cu powder (i.e.,
pore-making material), which had been mixed in the second powder
compact, was melted by heat in the sintering and contributed to the
formation of the pores in the connector 11b. In addition, it is
understood that the Cu powder itself melted in the sintering,
flowed into voids made when the Fe powder was sintered, and filled
the voids. Note that the composited cast member exhibited a tensile
strength of from 535 to 564 MPa. The tensile strength was 546 MPa
on the average when being measured three times.
(Example No. 2)
[0104] FIG. 5 illustrates a cylinder-shaped housing 2 for
compressors, Example No. 2 of the present invention. Note that the
present constituent members of compressors or pressure casing
include the cylinder-shaped housing 2. The housing 2 was made by
changing the shape of the iron-based porous sintered substance 11
in Example No. 1 to a trough-shaped iron-based porous sintered
substance 21 whose cross section was formed as a semicircle, and by
cast-wrapping the outer periphery of the iron-based porous sintered
substance 21 with a cast-wrapping member 22. In Example No. 2, the
inner peripheral side of the iron-based porous sintered substance
21 is turned into the reinforcer, and the outer peripheral side
thereof is turned into the connector. Example No. 2 is effective
when a high strength is required at the top of the inner peripheral
side of the housing 2 in the drawing alone.
(Example No. 3)
[0105] FIG. 6 illustrates a cylinder-shaped housing 3 for
compressors, Example No. 3 of the present invention. Note that the
present constituent members of compressors or pressure casing
include the cylinder-shaped housing 3. The housing 3 was made by
changing the shape of the iron-based porous sintered substance 11
in Example No. 1 to a trough-shaped iron-based porous sintered
substance 21 whose cross section was formed as a semicircle, and by
cast-wrapping the inner periphery of the iron-based porous sintered
substance 31 with a cast-wrapping member 32. In Example No. 3, the
outer peripheral side of the iron-based porous sintered substance
31 is turned into the reinforcer, and the inner peripheral side
thereof is turned into the connector. In Example No. 3, note that
the iron-based porous sintered substance 31 was not disposed over
the entire length of the housing 3, but was disposed in the middle
of the housing 3 only. Example No. 3 is effective when a high
strength is required at the top of the outer peripheral side of the
housing 2 and in the middle thereof in the drawing alone.
[0106] Not limited to the above-describe examples, it is possible
to think of a variety of many other examples depending on the types
and specifications of compressors and the applications and forms of
pressure casings.
[0107] Having now fully described the present invention, it will be
apparent to one of ordinary skill in the art that many changes and
modifications can be made thereto without departing from the spirit
or scope of the present invention as set forth herein including the
appended claims.
* * * * *