DESCRlPTION
IMPELLER, ROTARY MACHINE INCLUDING TilE SAME, AND METHOD FOR
MANUFACTURING IMPELLER
Technical Field
[0001]
The present invention relates to an impeller in rotary machines, such as a
centrifugal compressor, a rotary machine including the impeller, and a method for
10 manufacturing the impeller. Priority is claimed on Japanese Patent Application No.
2011-185838, filed August 29, 2011, the content ofwhich is incorporated herein by
reference.
15
Background Art
[0002]
As shown in FIGS. 12 and 14, generally, an impeller 101 used for rotary
machines, such as a centrifugal compressor, has a fixed hub portion 112 of a rotating
shaftS, a disc-shaped disc 107 that is provided integrally with the hub portion 112, a
shroud 108 that is arranged so as to be spaced apart from the disc 107 in the axial
20 direction of the central axis L, and a plurality of blades 106 that are provided in a
circumferential direction and connect the disc 107 to the shroud 108. In this type of
impeller, a portion surrounded by the side surfaces of the blades 106 and two mutually
facing surfaces ofthe disc 107 and the shroud 108 formed a flow passage 103 for
compressing air. Additionally, by shrink-fitting the hub portion 112 to the rotating shaft
25 S ofthe rotary machine, the impeller 101 is fixed to the rotating shaftS.
2
[0003]
The flow passage 103 opens toward a first end side of the central axis L on the
inner peripheral side, curves gradually so as to be directed to a radial outer peripheral
side, and opens toward the radial direction on outer peripheral side. That is, the flow
5 passage 103 is formed in a curved shape as viewed from the circumferential direction in
order to direct a fluid, which is introduced from the first end side along a second end side,
to the radial outer peripheral side (particularly, refer to FIG. 14). Moreover, as shown in
FIG. 13, as the blades 106 are obliquely connected to the disc 107, the compression
performance of the impeller 101 is improved, and thereby, the flow passage 103 assumes
10 a complicated three-dimensional shape.
[0004]
As a method for manufacturing the impeller 101, a method in which the blades
106 and one ofthe disc 107 and the shroud 108 are integrally formed, the other ofthe
disc and shroud is separately manufactured, and these disc and shroud are integrated by
15 welding or brazing, is known. Additionally, since the impeller requires high rigidity, a
one-piece impeller with high strength reliability is manufactured by shaving out the disc
107, the shroud 108, and the blade 106 from a single base material (for example, refer to
PTL 1).
20 Citation List
Patent Literature
[0005]
[PTL 1] Japanese Patent Application, First Publication No. 2010-285919
25 Summary of Invention
Problem to be solved by the Invention
[0006]
3
Incidentally, as described above, the flow passage 103 ofthe impeller 101 has a
complicated shape having a curved portion, and the inside of the flow passage is narrow.
5 Therefore, during the manufacture of the one-piece impeller 101, it is necessary to
perform complicated cutting while inserting, for example, machining members, such as
an electrode for machining, from positions to be used as an inlet and an outlet of the flow
passage 103. Additionally, in the manufacturing method as described in PTL 1, it is
necessary to form the flow passage using a special machining member and substantial
10 manufacturing costs are incurred.
[0007]
The present invention has been made in consideration of such a situation, and an
object thereof is to provide an impeller, a rotary machine including the impeller, and a
method for manufacturing the impeller that maintains the performance of the related art
15 while being capable ofbeing manufactured at low cost.
Means for solving the Problem
[0008]
In order to achieve the above object, an impeller related to a first aspect of the
20 present invention is an impeller including a plurality of blades disposed in a
circumferential direction of the impeller, in which each of the blades directs outward
from inward in a radial direction of the impeller; a shroud located close to a first end side
of an axis of the impeller with respect to the blades, and to which the blades are attached;
and a disk located close to a second end side of an axis of the impeller with respect to the
25 blades, to which the blades are attached, and configured to be attached to a rotating shaft.
5
4
A plurality of flow passages are formed by the blades, the disc, and the shroud. The
blades, the shroud and a first portion of the disk close to the second end side of the axis
of the impeller are integrated so as to form a first member. A second portion of the disk
close to the first end side of the axis of the impeller forms a second member.
[0009]
According to the first aspect of the present invention, when a flow passage
portion of the first member is formed by splitting the impeller into the first member and
the second member and making the second member into a part that constitutes the
portion of the disc on the first end side, the accessibility of the machining tool improves.
10 That is, when the machining tool is inserted from a position to be used as the outlet ofthe
flow passage, the machining when forming the flow passage becomes easy by making a
part that becomes an interference object, on the inner peripheral side, into a separate
second member. Additionally, when the machining tool is inserted from a position to be
used as the introduction port that is the inlet of the flow passage, the machining of the
15 introduction port becomes easy by making a part that becomes an interference object into
a separate second member. Thereby, the manufacturing time can be shortened, and the
manufacturing costs can be kept down.
[0010]
In a second aspect of the present invention, in the above impeller, at least one of
20 mutually facing. surfaces of the disc and the shroud in the first member is formed into a
flat surface.
[0011]
According to the second aspect of the present invention, the shape of the flow
passage defmed by the disc, the shroud, and the blades are further simplified. Therefore,
25 the accessibility of the machining tool can be improved and the man-hours of machining
5
when forming the flow passage can be further reduced.
[0012]
In a third aspect of the present invention, in the above impeller, both of the
mutually facing surfaces of the disc and the shroud in the first member are formed into
5 flat surfaces.
[0013]
According to the third aspect of the present invention, a curved portion is
eliminated in a cross-sectional shape when viewed from the circumferential direction in
the shape of the flow passage defined by the disc, the shroud, and the blades. Therefore,
10 the man-hours of machining when forming the flow passage can be further reduced.
15
20
25
[0014]
In a fourth aspect ofthe present invention, in the impeller of any one aspect of
the second and third aspects, the blades are provided within a range of the flat surface of
the disc or the shroud as viewed from the axial direction.
[0015]
According to the fourth aspect of the present invention, the shape of the flow
passage defmed by the disc, the shroud, and the blades are further simplified. Therefore,
the accessibility of the machining tool can be improved and the man-hours of machining
when forming the flow passage can be further reduced.
[0016]
In a fifth aspect ofthe present invention, in the impeller of any one aspect ofthe
first to four aspects, the surface of the second member that faces the first end side is
formed in a curved shape so as to be directed to the radial outer peripheral side as it goes
from the first end side to the second end side.
[0017]
5
6
According to the fifth aspect of the present invention, a fluid introduced into the
impeller can be guided to the flow passage without any delay by the surface of the
second member that faces the first end side. This can maintain the compression
performance of the impeller.
[0018]
In a sixth aspect of the present invention, in the impeller of any one aspect of the
first to fifth aspects, the first member has a fixed portion that is fixed to the rotating shaft.
[0019]
According to the sixth aspect of the present invention, the impeller can be more
10 firmly fixed to the rotating shaft compared to a case where the second member equivalent
to a hub portion of a disc of the related art is fixed to the rotating shaft after the first
member and the second member are integrated. That is, the impeller can be more firmly
fixed to the rotating shaft by directly fixing the first member, which has a weight more
than the second member, to the rotating shaft.
15 [0020]
In a seventh aspect of the present invention, in the impeller of any one aspect of
the first to sixth aspects, the surface of the blade that forms the flow passage is formed so
as to be orthogonal to the surface of the disc that faces the shroud.
[0021]
20 In the seventh aspect of the present invention, the shape of the blade is further
25
simplified as compared to a shape where the surface of the blade that forms the flow
passage inclines with respect to the disc. Therefore, the man-hours of machining when
forming the flow passage can be further reduced.
[0022]
Additionally, an eighth aspect of the present invention provides a rotary machine
5
7
including the impeller related to any one aspect of the first to seventh aspects.
By adopting the above impeller, the rotary machine can be provided at low
costs.
[0023]
Additionally, a method for manufacturing an impeller related to a ninth aspect of
the present invention is a method for manufacturing an impeller including a plurality of
blades disposed in a circumferential direction of the impeller, in which each of the blades
directs outward from inward in a radial direction of the impeller; a shroud located close
to a first end side of an axis of the impeller with respect to the blades, and to which the
10 blades are attached; and a disk located close to a second end side of an axis ofthe
impeller with respect to the blades, to which the blades are attached, a plurality of flow
passages being formed by the blades, the disc, and the shroud. The method for
manufacturing an impeller includes a first member forming step of performing cutting on
a base material for forming the second end side of the axis of the impeller to form the
15 flow passages, and forming a first member in which the blades, the shroud, and a first
portion of the disc close to the second end side. of the impeller are integrally formed; and
a second member forming step of forming a second member that constitutes a second
portion of the disc close to the first end side of the impeller.
20
[0024]
According to the ninth aspect of the present invention, after the impeller is split
into the first member and the second member, these members are formed in separate
steps, and the second member formed in the second member forming step is made into a
part that constitutes the portion of the disc on the first end side. This improves the
accessibility of a machining tool when a flow passage portion ofthe first member is
25 formed. That is, when the machining tool is inserted from a position to be used as the
8
outlet of the flow passage, the machining when forming the flow passage becomes easy
by making a part that becomes an interference object on the inner peripheral side into a
separate second member. Additionally, when the machining tool is inserted from a
position to be used as the introduction port that is the inlet of the flow passage, the
5 machining of the introduction port becomes easy by making a part that becomes an
interference object into a separate second member. Thereby, the manufacturing time
can be shortened, and the manufacturing costs can be kept down.
[0025]
In a tenth aspect of the present invention, in the above method for manufacturing
10 an impeller, in the second member forming step, the surface of the second member that
faces the first end side is formed with a curved portion that is directed to the radial outer
peripheral side as it goes from the first end side to the second end side.
[0026]
According to the tenth aspect of the present invention, the air introduced into the
15 impeller including the second member formed by the second member forming step can
be guided to the flow passage without any delay by the surface of the second member
that faces the first end side. Therefore, the performance of the impeller does not
degrade.
20 Advantageous Effects oflnvention
25
[0027]
According to the present invention, the accessibility of a machining tool
improves when a flow passage portion of the impeller is formed. Therefore, the
manufacturing time can be shortened and the manufacturing costs can be kept down.
9
Brief Description of Drawings
[0028]
FIG. 1 is a cross-sectional view showing a centrifugal compressor to which
impellers of an embodiment ofthe present invention is applied.
5 FIG. 2 is a perspective view showing an impeller of the embodiment of the
10
present invention.
FIG. 3 is an enlarged view of a part A of FIG. 2.
FIG. 4 is a cross-sectional view of the impeller of the embodiment of the present
invention.
FIG. 5 is an exploded cross-sectional view of the impeller of the embodiment of
the present invention.
FIG. 6 is a view showing a manufacturing step of the impeller of the
embodiment of the present invention.
FIG. 7 is a view showing a manufacturing step of the impeller of the
15 embodiment ofthe present invention.
20
FIG. 8 is a view showing a manufacturing step of the impeller of the
embodiment ofthe present invention.
FIG. 9 is a view showing a manufacturing step of the impeller of the
embodiment of the present invention.
FIG. 10 is a cross-sectional view showing another form ofthe impeller ofthe
embodiment of the present invention.
FIG. 11 is a cross-sectional view showing still another form of the impeller of
the embodiment of the present invention.
FIG. 12 is a perspective view showing an impeller of the related art.
25 FIG. 13 is an enlarged view of a part B ofFIG. 12.
5
10
FIG. 14 is a cross-sectional view of the impeller of the related art.
Description of Embodiments
[0029]
An embodiment of the present invention will be described in detail referring to
the drawings.
A centrifugal compressor 50 is shown as an example of a rotary machine of the
present embodiment in FIG. 1. The centrifugal compressor 50 is mainly constituted by
a rotating shaft S that is rotated around an axis P, impellers 1 that are attached to the shaft
10 Sand compress a fluid utilizing centrifugal force, and a casing 53 that rotatably supports
the rotating shaft S and is formed with flow passages 52 that allow the fluid to flow
therethrough from the upstream to the downstream.
[0030]
The casing 53 is formed so as to form a substantially columnar outline, and the
15 rotating shaftS is arranged so as to pass through the center of the casing. Journal
bearings 54 are provided at both axial ends of the rotating shaftS of the casing 53, and a
thrust bearing 55 is provided at one end of the rotating shaft. The journal bearings 54
and the thrust bearing 55 rotatably support the rotating shaftS. That is, the rotating
shaftS is supported by the casing 53 via the journal bearings 54 and the thrust bearing
20 55.
Additionally, a suction port 56 into which a fluid is made to flow from the
outside is provided on one end side of the casing 53 in the axial direction, and a
discharge port 57 through which the fluid flows out to the outside is provided on the
other end side. An internal space, which communicates with the suction port 56 and the
25 discharge port 57, respectively, and repeats diameter reduction and diameter increase, is
5
10
15
11
provided within the casing 53. This internal space functions as a space that
accommodates the impeller 1, and also functions as the above flow passages 52. That is,
the suction port 56 and the discharge port 57 communicate with each other via the
impellers 1 and the flow passages 52.
[0031]
A plurality of impellers 1 is arranged at intervals in the axial direction of the
rotating shaft S. In addition, although six impellers 1 are provided in the illustrated
example, at least one or more impellers may be provided.
[0032]
As shown in FIGS. 2 and 4, the impeller 1 has a substantially disc shape, and is
configured so tliat a fluid suctioned from an introduction port 2 that opens to a first side
in the direction (hereinafter referred to as an axial direction) of a central axis L is
discharged toward the radial outer peripheral side via flow passages 3 formed inside the
impeller 1.
In addition, in the following, the outer peripheral side of the impeller 1 in the
radial direction is simply referred to as outer peripheral side. Additionally, the inner
peripheral side of the impeller 1 in the radial direction is simply referred to as inner
peripheral side. Additionally, the upper side of FIGS. 2 and 4 that becomes the
upstream side of the fluid is referred to as a first end side, and the lower side of FIGS. 2
20 and 4 that becomes the downstream side of the fluid is referred to as a second end side.
[0033]
The impeller 1 of the present embodiment is equipped with a substantially
disc-shaped first member 4 that forms the second end side, and a substantially cylindrical
second member 5 that forms the first end side and that has an outer peripheral surface
25 that is gradually increased in diameter toward the second end side. A disc 7 that is fixed
12
to the rotating shaft S in the impeller 1, a plurality ofblades 6 that are provided in the
circumferential direction on the first end side of the disc 7 so as to be directed from the
inner peripheral side to the outer peripheral side, and a shroud 8 that is provided to face
the disc 7 on the first end side and is attached to the blades 6 are constituted by the first
5 member 4 and the second member 5. The first member 4 and the second member 5 are
not fixed to each other in the present embodiment but are fixed to the rotating shaft S,
respectively, whereby the introduction port 2 is defined between the first member 4 and
the second member 5, and the first member 4 and the second member 5 further defines a
suction portion 9 that connects the introduction port 2 and the flow passages 3.
10 [0034]
The first member 4 is arranged from the radial inner peripheral side toward the
radial outer peripheral side. The first member 4 is equipped with a plurality of blades 6
disposed in a circumferential direction of the impeller, a first portion 7a that is provided
on the second end side of the blades 6 and constitutes the second end side of the disc 7 to
15 which the blades 6 are attached, and the shroud 8 that is provided on the first end side of
the blades 6 and has the blades 6 attached thereto. That is, the shroud 8 is arranged so
as to be spaced apart from the first portion 7a of the disc 7 by a predetermined distance.
The first member 4 is formed from, for example, precipitation-hardened stainless steel.
20
[0035]
The first portion 7a of the disc 7 includes a fixed portion 12 that is fixed to the
rotating shaft S, and a disc body portion 11 that is formed integrally with the fixed
portion 12 and has a substantially disc shape.
The fixed portion 12 is formed in a cylindrical shape that has a fitting hole 13,
which penetrates in the axial direction, at a central portion thereof. The fitting hole 13
25 is a hole that is inserted and fitted to the rotating shaft S when the impeller 1 is fixed to
5
13
the rotating shaft S. The disc body portion 11 has a substantially circular shape as
viewed from the axial direction and is formed at one axial end of the fixed portion 12.
Additionally, one surface 11 a of the disc body portion 11 on the first end side is formed
into a substantially flat surface.
[0036]
In other words, the fixed portion 12 is a columnar part that protrudes to the
second end side in the central portion ofthe disc body portion 11. The fixed portion 12
protrudes to the second end side by a predetermined amount. This protruding amount is
appropriately set according to a fastening force required in order to shrink-fit and fix the
10 impeller 1 to the rotating shaftS.
[0037]
The plurality ofblades 6 are provided in the one surface 11a ofthe disc body
portion 11. The plurality of blades 6 have a constant plate thickness (blade thickness),
respectively, and are provided at regular intervals in the circumferential direction in a
15 substantially radial shape from the radial inner peripheral side toward the radial outer
peripheral side. Additionally, the blades 6 extend so as to curve toward one direction in
the circumferential direction as they go from the radial inner peripheral side ofthe disc 7
to the radial outer peripheral side, respectively.
20
[0038]
Additionally, an inner end portion 6a of the blade 6 on the radial inner peripheral
side is spaced apart from an inner peripheral surface 13a of the fitting hole 13 by a
predetermined distance G This distance G is appropriately set according to the shapes
or the like of the suction portion 9 and the flow passages 3 that communicate with the
suction portion 9, and is set so as to be located closer to the outer peripheral side than an
25 outer peripheral end of the second member 5.
14
[0039]
The shroud 8 is a substantially disc-shaped member that is provided integrally
with the blades 6 so as to cover the plurality of blades 6 from the first end side. The
shroud 8 is formed in the shape of a disc centered on the central axis L. Specifically,
5 the shroud 8 is formed in the shape of an umbrella that is gradually reduced in diameter
as it goes to the first end side. Additionally, the radial inner peripheral side of the
shroud 8 constitutes a cylindrical portion 14 that rises to the first end side. The
cylindrical portion 14 defmes the introduction port 2 together with a smaller-diameter
surface 17 (refer to FIG 5) of the second member 5 by combining the first member 4 and
10 the second member 5.
15
[0040]
Additionally, a range where the blades 6 are formed, in the other surface 8a of
the shroud 8 on the second end side, that is, the surface of the shroud 8 that faces the one
surface lla ofthe disc 7, is formed into a substantially flat surface.
That is, as for the other surface 8a of the shroud 8, a cross-section perpendicular
to the axial direction in the range where the blades 6 are formed can be drawn in a
straight line.
[0041]
As shown in FIG 3, the flow passage 3 is formed between the blades 6, the first
20 portion 7a of the disc 7, and the shroud 8. In other words, the flow passage 3 is
25
configured by a space surrounded by the one surface lla of the disc 7, the other surface
8a that is the surface of the shroud 8 on the second end side, and a surface 6b of one
blade 6 on the other circumferential side, and a surface 6c of the other blade 6 on one
circumferential side, in the blades 6 that are adjacent to each other.
[0042]
1S
Additionally, in the present embodiment, the blade 6 is provided so as to become
substantially perpendicular to the one surface 11 a of the disc 7. In other words, the
cross-sectional shape of the flow passage 3 defined by the blades 6, the disc 7, and the
shroud 8 becomes rectangular. That is, the surfaces of the blades 6 that form the flow
S passage 3 are formed so as to be substantially orthogonal to the one surface 11 a of the
disc 7.
[0043]
The second memberS has the second portion 7b of the disc 7, and is a
substantially cylindrical member centered on the central axis L. The second member S
10 has the outer peripheral surface 16 that is gradually increased in diameter toward the
second end side. A radial central portion ofthe second memberS is formed with a
second fitting hole 15 that has almost the same internal diameter as the fitting hole 13.
Additionally, the other end surface Sa of the second memberS is formed into a flat
surface.
1S
20
[0044]
The outer peripheral surface 16 of the second memberS includes the
smaller-diameter surface 17 and an increased diameter surface 18. The
smaller-diameter surface 17 including an end portion of the second member S on the first
end side is formed so as to have the same diameter along the axial direction.
The increased diameter surface 18 including an end portion ofthe second
member S on the second end side is formed into a curved surface that is gradually
increased in diameter toward the other end surface Sa. The smaller-diameter surface 17
and the increased diameter surface 18 are gently connected. Additionally, the increased
diameter surface 18 is formed so that the normal line of the increased diameter surface 18
2S substantially faces the axial direction on the other end portion.
5
16
That is, when the first member 4 and the second member 5 are combined, these
members are formed so that the increased diameter surface 18 and the one surface 11a of
the disc 7 are gently connected.
[0045]
Additionally, the diameter of the other end surface 5a of the second member 5 is
formed so as to become smaller than the internal diameter of the cylindrical portion 14 of
the shroud 8.
In addition, the shape of the increased diameter surface 18 may be an oblique
surface with a constant angle, without being limited to the curved surface as described
10 above. Additionally, and in particular the smaller-diameter surface 17 does not need to
be provided, and the outer peripheral surface 16 may be constituted only by the increased
diameter surface 18.
[0046]
Next, a method for assembling the impeller 1 of the present embodiment to the
15 rotating shaftS will be described. First, as shown in FIG. 5, the inner peripheral surface
of the fixed portion 12 of the first member 4 is fixed to the rotating shaftS by
shrink-fitting. Specifically, the inner peripheral surface of the fitting hole 13 of the first
member 4 is heated whereby the fitting hole 13 is increased in diameter, and in this state,
the fitting hole 13 is inserted through the rotating shaft S. Then, the first member 4 and
20 the rotating shaftS are integrally anchored by cooling the periphery of the fitting hole 13
to reduce the diameter thereof, and bringing the fitting hole 13 into contact with the outer
peripheral surface of the rotating shaftS.
[0047]
Next, similarly to the first member 4, the second member 5 is fixed to the
25 rotating shaftS by shrink-fitting. In this case, the shrink-fitting is performed after the
17
other end surface 5a of the second member 5 is made to abut against the one surface 11a
of the disc 7 of the first member.
In addition, the order of being fixed to the rotating shaftS is not limited to the
above-described order, and the first member 4 may be fixed to the rotating shaft S after
5 the second member 5 is fixed to the rotating shaft S.
[0048]
As described above, the impeller 1 is formed by the first member 4 and the
second member 5 that are assembled to the rotating shaftS. As the other end surface 5a
of the second member 5 and the one surface 11a of the first member 4 abut against each
10 other, the relative positions of the first member 4 and the second member 5 are
determined, and thereby, the introduction port 2 and the suction portion 9 are defined.
[0049]
In addition, the assembling method is not limited to the above-described method,
for example, a method for fixing the first member 4 and the second member 5 to the
15 rotating shaft S after the second member 5 is joined to the first member 4 by methods,
such as welding, may be used.
[0050]
In the impeller 1 shown above, a fluid that has flowed in from the introduction
port 2 is directed to the outer peripheral side from the inner peripheral side by the
20 increased diameter surface 18 of the second member 5 in the suction portion 9. Next,
the fluid that has flowed into the flow passages 3 from the suction portion 9 is
accelerated by a centrifugal force generated by the rotation of the rotating shaft S by a
driving source that is not shown, and is discharged from the outer peripheral ends of the
flow passages 3.
25 [0051]
5
18
A method for manufacturing the above-described impeller 1 of the present
embodiment will be described. The method for manufacturing the impeller 1 related to
the present embodiment has a first member forming step of forming the first member 4,
and a second member forming step of forming the second member 5.
[0052]
The first member forming step has a first base material forming step and a
cutting step. First, as shown in FIG 6, as the first base material forming step, a
substantially cylindrical base material 30, which is formed with the fitting hole 13
through which the rotating shaftS is inserted and the fixed portion 12, is forged. Then,
10 as shown in FIG 7, an inclined surface 8b that is the surface of the shroud 8 on the first
end side is formed by, for example, lathing or the like to form a disc body 32.
In addition, here, although the base material30 is subjected to lathing or the like
so as to form the disc body 32, the disc body 32 may be formed only by forging.
Additionally, here, although the cylindrical base material30 which is formed with the
15 fitting hole 13 and the fixed portion 12 by forging, is adopted, the fitting hole 13 and the
fixed portion 12 are subjected to lathing or the like, for example, using a disc-shaped
base material.
[0053]
Next, as shown in FIG 8, as the cutting step, the flow passage 3 is formed from
20 the outer peripheral side of the disc body 32. Specifically, the flow passage 3 is formed
by inserting an electrode 33 corresponding to the shape of the flow passage 3 from a
position to be used as an outlet ofthe flow passage 3, by a spark erosion method.
Here, the electrode 33 is a rectangular elongated member as viewed from the
cross-section thereof. Additionally, the electrode 33 has a shape having a height smaller
25 than the height of the flow passage 3, and has a curved shape and a width dimension
5
19
corresponding to a shape viewed from the axial direction of the flow passage 3.
Additionally, the electrode 33 is formed from, for example, graphite, copper, or the like,
and is attached to an electrical discharge machine that is not shown.
[0054]
As for spark erosion, first, the disc body 32 is dipped in, for example, spark
erosion oil that is not shown. Next, as shown in FIG 8, the disc body 32 and the flow
passage 3 are relatively moved in the radial direction and the circumferential direction,
respectively, while a portion that becomes the flow passage 3 are inserted using the
electrode 33. Additionally, the disc body is also moved in the axial direction if
10 necessary, and spark erosion is performed. In addition, in this case, the machining
15
conditions (a current, a voltage, a pulse, and a feed rate) ofthe spark erosion by the
electrode 33 may be appropriately changed.
A plurality of the flow passages 3 are formed by repeatedly carrying out the
steps shown above, regarding each flow passage 3 to be formed in the impeller 1.
[0055]
Next, as shown in FIG. 9, the electrode 33 is inserted from the first end side, and
the inner peripheral surface of the shroud 8 is machined.
In addition, in the present embodiment, spark erosion is performed by one type
of electrode 33. However, the electrode is not limited to this. For example, roughing,
20 intermediate machining, and fmishing may be performed using two or more types of
electrodes with different sizes or materials.
[0056]
Next, in the second member forming step, the second member 5 (refer to FIG. 5)
is formed by performing lathing of the cylindrical base material. In the second member
25 forming step, the outer peripheral surface 16 that has the curved increased diameter
5
20
surface 18 that goes to the radial outer peripheral side is formed as it goes from the
second direction to the first direction in the axial direction in the second member 5.
In addition, not only the second member 5 may be obtained by performing
lathing of the base material but the second member 5 may be formed only by forging.
[0057]
According to the above embodiment, the shape of the flow passage 3 formed by
the blades 6, the disc 7, and the shroud 8 of the first member 4 forms a substantially
straight shape as viewed from the circumferential direction. Therefore, the spark
erosion using the straight electrode 33 becomes easier. Since the second member 5
10 equivalent to a hub portion of related art for directing the air introduced in the axial
direction to the radial direction is a separate member, machining ofthe introduction port
2 in the vicinity of the impeller 1 becomes easier.
[0058]
In other words, when the flow passage 3 of the first member 4 is formed by
15 splitting the impeller 1 into the first member 4 and the second member 5 and making the
second member 5 into a part that constitutes the portion of the disc 7 on the first end side,
the accessibility of the electrode 33 improves. That is, when the electrode 33 is inserted
from a position to be used as the outlet of the flow passage 3, the machining when
forming the flow passage 3 becomes easy by making a part that becomes an interference
20 object on the inner peripheral side into a separate second member 5. Additionally, when
the electrode 33 is inserted from a position to be used as the introduction port 2 that is the
inlet of the flow passage 3, the machining of the introduction port 2 becomes easy by
making a part that becomes an interference object on the second end side into a separate
second member 5. Thereby, the manufacturing time can be shortened, and the
25 manufacturing costs can be kept down.
•
5
10
21
[0059]
Additionally, since the fluid introduced into the impeller 1 can be guided to the
flow passage 3 without any delay by the increased diameter surface 18 in the second
member 5, the compression performance of the impeller 1 can be maintained.
[0060]
Additionally, since the first member 4 and the second member 5 are separately
shrink-fitted and fixed to the rotating shaftS, respectively, the impeller 1 can be more
firmly fixed to the rotating shaft S as compared to a case where any member is fixed to
the rotating shaft S after the first member 4 and the second member 5 are integrated.
[0061]
Additionally, the surface of the blades 6 that forms the flow passage 3 are
formed so as to be orthogonal to the disc 7 whereby the shape of the blades 6 are further
simplified as compared to a shape where the surfaces of the blades 6 that form the flow
passage 3 inclines with respect to the disc 7. Therefore, the man-hours of machining
15 when the flow passage 3 is formed can be further reduced.
20
[0062]
In addition, the technical scope of the present invention is not limited to the
above embodiment, and various changes can be made without departing from the scope
of the present invention.
In the above embodiment, the other end surface 5a of the second r_nember 5 and
the one surface lla of the first member 4 are made into substantially flat surfaces,
respectively. In contrast, as shown in FIG 10, a configuration in which the other end
surface 5Ba of a second member 5B that constitutes an impeller lB is provided with a
convex portion 20 of a shape that extends the other end surface 5Ba to the second end
25 side, and a concave portion 21 corresponding to the convex portion 20 is provided in one
•
5
22
surface 11Ba of a first member 4B may be adopted.
Here, although the second member 5B and the first member 4B are fixed by
shrink-fitting or the like in the other end surface 5Ba of the second member 5B, it is not
necessary to fix the second member 5B and the rotating shaft S.
Since the outer peripheral side of the other end surface 5Ba of the second
member 5B does not have a thin-walled shape in such a configuration, machining of the
second member 5B becomes easy.
[0063]
Additionally, as shown in FIG 11, the first member 4C that constitutes the
10 impeller 1 C is not necessarily provided with a fixed portion that extends to the second
side of the disc 7C. In the case of this form, it is preferable that the dimension d from
the end portion of the second member 5C on the second end side be as great as possible
within a range where the fixation strength between the first member 4C and the rotating
shaft S can be sufficiently secured. As the dimension d is enlarged, the accessibility of
15 a machining member during machining of the flow passage 3C and the introduction port
2C is increased, which is preferable.
20
25
Moreover, in FIG 10, the fixed portion is not necessarily provided even in a case
where the second member 5B is, for example, shrink-fitted to the rotating shaftS and the
first member 4B.
[0064]
Additionally, the method for machining the flow passage or the like may not be
limited to the spark erosion, and a flow passage or the like may be worked by machining.
Industrial Applicability
[0065]
•
5
10
15
20
23
According to the impeller of the present invention, the accessibility of a
machining tool improves when a flow passage portion of the impeller is formed.
Therefore, manufacturing time can be shortened. Additionally, in the impeller of the
present invention, manufacturing costs can be kept down.
Reference Signs List
[0066]
S: ROTATING SHAFT
1: IMPELLER
3: FLOW PASSAGE
4: FIRST MEMBER
5: SECOND MEMBER
6: BLADE
7: DISC
8: SHROUD
8A: OTHER SURFACE
11: DISC BODY PORTION
llA: ONE SURFACE
12: FIXED PORTION
18: INCREASED DIAMETER SURFACE
50: CENTRIFUGAL COMPRESSOR (ROTARY MACHINE)

CLAIMS
1. An impeller comprising:
a plurality of blades disposed in a circumferential direction of the impeller, in
5 which each of the blades directs outward from inward in a radial direction of the
impeller;
a shroud located close to a first end side of an axis of the impeller with respect to
the blades, and to which the blades are attached; and
a disk located close to a second end side of an axis of the impeller with respect
10 to the blades, to which the blades are attached, and configured to be attached to a rotating
shaft; wherein
a plurality of flow passages are formed by the blades, the disk and the shroud,
the blades, the shroud and a first portion of the disk close to the second end side
of the axis of the impeller are integrated so as to form a first member, and
15 a second portion of the disk close to the first end side of the axis of the impeller
forms a second member.
2. The impeller according to Claim 1,
wherein at least one of the mutually facing surfaces of the disc and the shroud in
20 the first member is formed into a flat surface.
3. The impeller according to Claim 2,
wherein both of the mutually facing surfaces of the disc and the shroud in the
first member are formed into flat surfaces.
25
# 25
4. The impeller according to Claim 2,
wherein the blades are provided within a range of the flat surface of the disc or
the shroud as viewed from the axial direction.
5 5. The impeller according to Claim 1,
wherein the surface of the second member that faces the first end side is formed
in a curved shape so as to be directed to the radial outer peripheral side as it goes from
the first end side to the second end side.
10 6. The impeller according to Claim 1,
wherein the first member has a fixed portion that is fixed to the rotating shaft.
7. The impeller according to Claim 1,
wherein the surface of the blade that forms the flow passage is formed so as to
15 be orthogonal to the surface of the disc that faces the shroud.
8. A rotary machine comprising the impeller according to any one of Claims 1
to 7.
20 9. A method for manufacturing an impeller including a plurality of blades
disposed in a circumferential direction of the impeller, in which each of the blades directs
outward from inward in a radial direction of the impeller; a shroud located close to a first
end side of an axis of the impeller with respect to the blades, and to which the blades are
attached; and a disk located close to a second end side of an axis of the impeller with
25 respect to the blades, to which the blades are attached, a plurality of flow passages being
^ 26
formed by the blades, the disc, and the shroud, the method comprising:
a &st member forming step of performmg cutting on a base material for foraiing
the second end side of the axis of the impeller to form the flow passages, and forming a
first member in which the blades, the shroud, and a first portion of the disc close to the
5 second end side of the axis of the impeller are integrally formed; and
a second member forming step of forming a second member that constitutes a
second portion of the disc close to the first end side of the axis of the impeller.
10. The method for manufacturing an impeller according to Claim 9,
10 wherein, in the second member forming step, the surface of the second member
that faces the first end side is formed with a curved portion that is directed to the radial
outer peripheral side as it goes fi-om the first end side to the second end side.