U.S. patent application number 15/507610 was filed with the patent office on 2017-10-19 for ring molded article manufacturing method.
The applicant listed for this patent is HITACHI METALS, LTD., Hitachi Metals MMC Superalloy, Ltd.. Invention is credited to Yuji ISHIWARI, Jun OHSONE.
Application Number | 20170297080 15/507610 |
Document ID | / |
Family ID | 55439729 |
Filed Date | 2017-10-19 |
United States Patent
Application |
20170297080 |
Kind Code |
A1 |
ISHIWARI; Yuji ; et
al. |
October 19, 2017 |
RING MOLDED ARTICLE MANUFACTURING METHOD
Abstract
A ring molded article manufacturing method capable of reliably
and efficiently producing a ring molded article in which dead metal
regions are reduced, is provided. In the present invention, a
material is processed by first forging so as to be shaped in a
shape including a bottom which is formed in a substantially disk
shape, and a peripheral wall which is inclined to a direction from
a center of the bottom toward an outer periphery thereof, in a
direction from the outer periphery of the bottom toward one side in
a direction of a center axis of the bottom, the bottom of a first
forged article obtained by the first forging is drilled, a drilled
article obtained by the drilling is ring-rolled, a ring material
obtained by the ring rolling is placed inside two molds, the ring
material is then processed by second forging so as to be pressed by
the two molds in a direction of a center axis of the ring material,
and the ring molded article is thus produced.
Inventors: |
ISHIWARI; Yuji; (Saitama,
JP) ; OHSONE; Jun; (Saitama, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hitachi Metals MMC Superalloy, Ltd.
HITACHI METALS, LTD. |
Saitama
Tokyo |
|
JP
JP |
|
|
Family ID: |
55439729 |
Appl. No.: |
15/507610 |
Filed: |
August 27, 2015 |
PCT Filed: |
August 27, 2015 |
PCT NO: |
PCT/JP2015/074182 |
371 Date: |
February 28, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B21J 5/02 20130101; F01D
5/02 20130101; F05D 2230/25 20130101; F05D 2230/26 20130101; B21K
1/761 20130101; B21K 21/06 20130101; B21K 1/32 20130101; B21B 5/00
20130101; B21B 15/00 20130101; B21J 5/025 20130101; F02C 7/00
20130101; B21H 1/06 20130101 |
International
Class: |
B21H 1/06 20060101
B21H001/06; B21J 5/02 20060101 B21J005/02; B21K 1/32 20060101
B21K001/32; F01D 5/02 20060101 F01D005/02 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 1, 2014 |
JP |
2014-177026 |
Claims
1. A ring molded article manufacturing method comprising: a step of
performing first forging on a material such that the material is
formed in a shape including a bottom which is formed in a disk
shape, and a peripheral wall which is inclined to a direction from
a center of the bottom toward an outer periphery thereof, in a
direction from an outer periphery of the bottom toward one side in
a direction of a center axis of the bottom; a step of drilling the
bottom of a first forged article obtained by the step: of
performing the first forging; a step of ring-rolling a drilled
article obtained by the step of drilling; and a step of producing a
ring molded article in which a ring material obtained by the step
of ring-rolling is placed inside two molds, the ring material is
then processed by second forging so as to be pressed by the two
molds in a direction of a center axis of the ring material, and the
ring molded article is thus produced.
2. The ring molded article manufacturing method according to claim
1, wherein the ring molded article includes two convex portions
which respectively protrude on both sides of the ring molded
article in a direction of a center axis thereof and extend in a
direction of a circumference of the ring molded article, concave
portions respectively corresponding to the convex portions of the
ring molded article are formed on the two molds respectively, and
the ring material placed inside the two molds is supported by a
region located on an outer peripheral side from an outer peripheral
side corner m the concave portion of one of the two molds and a
region located on an inner peripheral side from an inner peripheral
side corner in the concave portion of another of the two molds.
3. The ring molded article manufacturing method according to claim
1, wherein in the step of performing the first forging, if a one
half section of the peripheral wall is divided into a one side
region and an another side region in the direction of the center
axis of the first forged article based on a middle of a maximum
height of the first forged article in the direction of the center
axis of the first forged article, a straight line passing through a
center of gravity of the one side region and a center of gravity of
the another side region is inclined by an angle relative to the
center axis of the first forged article, of which a range is 7
degrees to 40 degrees.
4. The ring molded article manufacturing method according to claim
1, wherein if a one half section of the ring material placed inside
the two molds is divided into a one side region and an other side
region in the direction of the center axis of the ring material
based on a middle of a maximum height of the ring material in the
direction of the center axis of the ring material, a straight line
passing through a center of gravity of the one side region and a
center of gravity of the another side region is inclined by m angle
relative to the center axis of the ring material, of which a range
is 7 degrees to 40 degrees.
Description
TECHNICAL FIELD
[0001] The present invention relates to a ring molded article
manufacturing, method is which forging is used.
BACKGROUND ART
[0002] For example, in an engine used for an aircraft or the like,
a plurality of turbine disks are arranged side by side such that
their center axes are positioned along one another, and a plurality
of turbine blades are attached to each turbine disk so as to be
apart from one another in a direction of a circumference of each
turbine disk. In particular, in an engine used in an aircraft,
high-temperature and high-pressure combustion gas, which is
generated inside the engine, flows in a direction of the center
axes from a front stage side of the turbine disks toward a rear
stage side thereof, on peripheral portions of the turbine disks,
and thus, the turbine disks, together with the turbine blades,
rotate at a high speed around their center axes. The driving force
generated by this rotation is transmitted to a compressor and fans
which are located on the front stage side of the turbine disks in
the direction of the center axes, and compressed air necessary for
continuous combustion of the gas and propulsion are thus
obtained.
[0003] Generally, a turbine disk is produced by an operation in
which a molding article formed in a substantially ring-like shape
(hereinafter referred to as a "ring molded article"), is subjected
to cutting or the like. In this ring molded article, typically,
convex portions respectively protrude on both sides of the ring
molded article in a direction of a center axis thereof, and
furthermore, the convex portions extend in a direction of a
circumference of the ring molded article.
[0004] An outer periphery of the turbine disk is exposed to
combustion gas, and a temperature thereat becomes as high as
approximately 600 degrees C. to 700 degrees C. Meanwhile, a
temperature at an inner periphery thereof is lower than that at the
outer periphery. Thermal stress is generated in an inside of this
turbine disk because the engine is repeatedly started and stopped.
Therefore, it is desired for the turbine disk to have excellent low
cycle fatigue characteristics. Furthermore, centrifugal force is
applied to the outer periphery of the turbine disk according to a
high-speed rotation around the axis thereof at high temperatures.
Therefore, it is desired for the turbine disk to further have a
high creep strength characteristic. In addition, it is desired for
the turbine disk to have a high tensile strength and a high yield
strength. Therefore, it is desired for the ring molded article used
in the turbine disks, to have a sufficiently high mechanical
strength appropriate for the above desires.
[0005] Accordingly, in an example of a ring molded article
manufacturing method, the following is performed to secure
mechanical strengths of a ring molded article. A cylindrical billet
is processed by first forging so as to be pressed by two molds from
a direction of a center axis of the billet, and a first forged
article which is formed in a disc-like shape, is thus produced. The
first forged article is drilled such that a through hole in an
axial direction of the forged article is formed, and a drilled
article is thus produced. The drilled article is processed by ring
rolling, and a material which is formed in a substantially
ring-like shape (hereinafter referred to as a "ring material"), is
thus produced. Next, the ring material is placed inside the two
molds on which concave portions corresponding to the convex
portions of the ring molded article are formed respectively, and
the ring material is then subjected to second forging so as to be
sandwiched and pressed between the two molds. In the second forging
process, the ring material in the form of fluid fills in the
concave portions of the two molds to form the convex portions of
the ring molded article, and the ring molded article is thus
obtained (for example, see Patent Literatures 1 and 2). In the
second forging, strain is imparted to the ring molded article, the
crystal grains which form the ring molded article, are thus
refined, and thereby, mechanical strengths, such as a tensile
strength and a fatigue strength, can be in particular improved. For
equipment used for the second forging, a hydraulic-control forging
press machine which can strictly control a speed of the forging,
has often been used. In addition, the ring molded articles produced
by the example of the above manufacturing method, have often been
used for producing large turbine disks.
CITATION LIST
Patent Literature
[0006] Patent Literature 1: JP S52-131967 A
[0007] Patent Literature 2: JP 2011-079043 A
SUMMARY OF INVENTION
Technical Problem
[0008] However, in the above example of the ring molded article
manufacturing method, it is necessary to remove a large amount of
the material of the first forged article to form a through hole in
the first forged article which is formed in a cylindrical shape.
This causes a problem in a view of efficiently producing the ring
molded article.
[0009] In addition, regarding the second forging process, it
becomes difficult to impart strain to a surface region of the ring
material which is in contact with the molds, particularly in an
initial stage of the second forging, because the material adheres
to the molds. Furthermore, in the second forging process, a
temperature of the surface region of the ring material which is in
contact with the molds, is decreased in comparison with a
temperature of a central region of the ring material according to
influence from heat release to the mold which is primarily made of
a metal. According to these factors, a region of the ring molded
article corresponding to the surface region which is in contact
with the mold particularly at the initial stage of the second
forging, may have a rough structure in comparison with the
structure of the central region of the ring molded article, and
thus, it becomes difficult for this region to obtain desired
mechanical characteristics. The above region is known as a "dead
metal" region. It is desired to avoid this dead metal remaining in
a region of the ring molded article which is used as a turbine disk
(hereinafter referred to as a "turbine disk region"). To prevent
the turbine disk region from including the dead metal region, an
excess portion of the ring molded article is previously provided
such that a thickness thereof is increased, and the excess portion
is then removed by a cutting after the second forging.
[0010] However, in the above example of the ring molded article
manufacturing method, at start of the second forging and at the
initial stage of the second forging, the ring material, which is
placed inside the two molds, is in contact with an entirety of
regions which range from an opening of the concave portion of the
mold to both inner peripheral and outer peripheral sides of the
concave portion, respectively. As a result, it becomes difficult to
impart strain to a wide range of the surface region of the ring
material, a temperature in a wide range of the surface region of
the ring material may easily decrease, and thus, the dead metal
regions may be increased in the ring molded article which is
produced in the above manner. It is necessary to increase an amount
of the excess portions of the ring molded article corresponding to
the dead metal regions and then remove large amounts of excess
portions. Accordingly, it is desired to provide near-net-shape
forging in which the dead metal regions can be reduced so that the
excess portions can be reduced.
[0011] Furthermore, in the above example of the ring molded article
manufacturing method, it is difficult for the ring material in the
form of fluid to fill an inside of the concave portion of the mold
in the second forging process, if the two convex portions of the
ring molded article to be produced, are offset relative to each
other in a radial direction of the ring molded article. As a
result, it becomes difficult to form the convex portions of the
ring molded article, it becomes difficult to produce the ring
molded article, and thus, a problem arises.
[0012] The present invention has been made in consideration of the
above-described circumstances, and an object of the present
invention is to provide a ring molded article manufacturing method
capable of reliably and efficiently producing a ring molded article
in which dead metal regions are reduced.
Solution to Problem
[0013] To solve the above-described problem, according to a ring
molded article manufacturing method is an aspect of the present
invention, the method includes a step of performing first forging
on a material such that the material is formed in a shape including
a bottom which is formed in a disk shape, and a peripheral wall
which is inclined to a direction from a center of the bottom toward
an outer periphery thereof, in a direction from an outer periphery
of the bottom toward one side in a direction of a center axis of
the bottom, a step of drilling the bottom of a first forged article
obtained by the step of performing the first forging, a step of
ring-rolling a drilled article obtained by the step of drilling,
and a step of producing a ring molded article in which a ring
material obtained by the step of ring-rolling, is placed inside two
molds, the ring material is then processed by second forging so as
to be pressed by the two molds in a direction of a center axis of
the ring material, and the ring molded article is thus
produced.
Advantageous Effects of Invention
[0014] According to the ting molded article manufacturing method in
an aspect of the present invention, the ring molded article in
which dead metal regions are reduced, can be reliably and
efficiently produced.
BRIEF DESCRIPTION Of DRAWINGS
[0015] FIG. 1 is a plan view schematically showing a ring molded
article which is produced by a manufacturing method according to a
First Embodiment of the present invention.
[0016] FIG. 2. is a half sectional view of the ring molded article
which is produced by the manufacturing method according to the
First Embodiment of the present invention.
[0017] FIG. 3 is a flow chart for explaining the manufacturing
method according to the First Embodiment of the present
invention.
[0018] FIG. 4 is a full sectional view schematically showing a
billet to be subjected to rough forging in the manufacturing method
according to the First Embodiment of the present invention.
[0019] FIG. 5 is a plan view schematically showing a rough-forged
article made by rough forging in the manufacturing method according
to the First Embodiment of the present invention.
[0020] FIG. 6 is a full sectional view schematically showing a
drilled article made by a drilling process in the manufacturing
method according to the First Embodiment of the present
invention.
[0021] FIG. 7 is a diagram for explaining ring rolling in the
manufacturing method according to the First Embodiment of the
present invention.
[0022] FIG. 8(a) is a half sectional view schematically showing a
condition of arrangement of a ring-rolled article immediately
before start of finishing forging in the manufacturing method
according to the First Embodiment of the present invention.
[0023] FIG. 8(b) is a half sectional view schematically showing a
condition immediately after the finishing forging is completed.
[0024] FIG. 9 is a half sectional view schematically showing the
ring-rolled article of FIG. 8(a).
DESCRIPTION OF EMBODIMENTS
[0025] A method for manufacturing a ring molded article according
to First to Third Embodiments of the present invention will be
described below with reference to FIGS. 1 to 9. Note that in the
First to Third Embodiments of the present invention, the following
expressions are used for a section of an article which is
substantially symmetric based on a center axis (hereinafter
referred to as a "symmetric article"), and drawings which show such
sections. Among sections obtained by cutting a symmetric article
along a plane passing through the center axis, one of which will be
referred to as a "half section", and a drawing, such as FIGS. 2, 8,
and 9, showing this half section will be referred to as a "half
sectional view". An entire section of a symmetric article obtained
by cutting the symmetric article along a plane passing through the
center axis will be referred to as a "full section", and a drawing,
such as FIGS. 4 to 6, showing this full section will be referred to
as a "full sectional view".
First Embodiment
[0026] A ring molded article produced by a manufacturing method
according to the First Embodiment of the present invention will be
described below. A ring molded article is used for producing a
turbine disk in an engine for an aircraft or the like. Furthermore,
the turbine disk is produced by an operation in which a ring molded
article after molding is processed by heat treatment, an operation
in which an excess portion of a ring molded article is removed, and
the like. Typically, a ring molded article is made of metals, and
in the present Embodiment, a ring molded article is produced of
Ni-base alloy718. However, the present invention is not limited to
this. More specifically, any metal which enables manufacturing of a
ring molded article having high strength at high temperatures, can
be used. As an example, a ring molded article may be produced by
using a Ni-base alloy, a Fe-base alloy, a Co-base alloy, or the
like which has high strength at high temperatures.
[0027] As shown in FIGS. 1 and 2, the ring molded article includes
a base portion 1b which is formed in a substantially ring-like
shape around a center axis 1a thereof. The ring molded article 1
includes a one side convex portion 1c and an another side convex
portion 1d which protrude from the base portion 1b on both sides of
the ring molded article 1 in a center axis direction thereof,
respectively. The two convex portions 1c and 1d are formed so as to
extend in a direction of a circumference of the ring molded article
1. Note that in FIG. 2, the one side convex portion 1c and the
another side convex portion 1d of the ring molded article 1
substantially coincide with each other in a radial direction of the
ring molded article 1. However, in an alternative feature, the one
side convex portion 1c and the another side convex portion 1d of
the ring molded article 1 can be offset relative to each other in
the radial direction of the ring molded article 1.
[0028] An outline of the above method for manufacturing the ring
molded article 1 will be described with reference to FIG. 3. A
billet 2 (shown in FIG. 4) is subjected to rough forging as first
forging, and thus, a rough-forged article 3 (shown in FIG. 5) is
produced as a first forged article (Rough forging step S1). The
rough-forged article 3 is processed by drilling so that a drilled
article 4 is made (shown in FIG. 6). Note that the drilled article
4 may be further processed by intermediate ring rolling if
necessary (drilling step S2). The drilled article 4 is ring-rolled
so that a ring-rolled article 5 (shown in FIGS. 8(a) and 9)
configured as a ring material, is made (ring rolling step S3). The
ring-rolled article 5 is processed by finish forging as second
forging so that the above ring molded article 1 configured as a
second forged article, is made (finishing forging step S4).
[0029] Details of each step in the method for manufacturing the
ring molded article 1 will be described below.
Regarding the Rough Forging Step S1
[0030] Details of the rough forging step S1 will be described
below. As shown in FIG. 4, the billet 2 formed in a substantially
cylindrical shape around a center axis 2a as a material to be
processed by rough forging, is produced by using Ni-base alloy718,
and then, the billet 2 is pressed by using molds and the like so
that the rough-forged article 3 shown in FIG. 5 is produced. As an
example, if the billet 2 is to be produced by using Ni-base alloy
718, it is preferable that a heating temperature for the billet 2
used in the rough forging step S1 be in a range of 900 degrees C.
to 1075 degrees C. However, the present invention is not limited to
this. More specifically, if the billet 2 is to be produced by using
a metal other than Ni-base alloy718, the heating temperature may be
set so as to be adapted to rough forging which is performed on the
above billet.
[0031] As shown in FIG. 5, the rough-forged article 3 is formed so
as to include a bottom 3b which is formed in a substantially
disc-like shape around a center axis 3a, and a peripheral wall 3c
which is inclined to a direction from a center of the bottom 3b to
an outer periphery thereof, in a direction from the center of the
bottom 3b to one side of a center axis direction of the bottom 3b.
Note that in FIG. 5, a broken line indicates a boundary between the
bottom 3b and the peripheral wall 3c. In the drilling process
described below, the bottom 3b is removed along the broken line. In
the above rough-forged article 3, if a half section of the
peripheral wall 3c is divided into a one side region 3e and an
another side region 3f in a center axis direction of the
rough-forged article 3 based on a middle line 3d for a maximum
height h1 of the rough-forged article 3 in the center axis
direction thereof, a straight line 3i which passes through a center
of gravity 3g of the one side region 3e and a center of gravity 3h
of the another side region 3f, is inclined by an angle .cndot.1
relative to a parallel line 3j which is in parallel with the center
axis 3a of the rough-forged article 3, i.e., relative to the center
axis 3a of the rough-forged article 3. It is preferable that the
angle .cndot.1 be in a range which is 7 degrees to 40 degrees.
Regarding Drilling Step S2
[0032] Details of the drilling step S2 will be described below. The
rough-forged article 3 is processed by drilling, such as punching
out with press working, cutting with a water cutter, or the like,
such that the bottom 3b of the rough-forged article 3 shown in FIG.
5 is removed. As a result, the drilled article 4 including a
through hole 4b which is formed along a center axis 4a, is produced
as shown in FIG. 6. The drilled article 4 includes a peripheral
wall 4c corresponding to the peripheral wall 3c of the rough-forged
article 3. If necessary, the drilled article 4 may be processed by
intermediate ring rolling.
Regarding Ring Rolling Step S3
[0033] The ring rolling step S3 will be described below. In the
ring rolling step S3, as an example, a ring rolling apparatus 11
shown in FIG. 7 is used. The ring rolling apparatus 11 includes a
main roll 12 which is located on an outer periphery side of the
drilled article 4, and a mandrel roll 13 which is located on an
inner periphery side of the drilled article 4. The outer peripheral
surface of the main roll 12 and that of the mandrel roll 13 face
each other. The main roll 12 is configured so as to be rotatable
around a rotational axis 12a which passes through a center of the
main roll 12 and extends substantially parallel with the center
axis 4a of the drilled article 4. The outer peripheral surface of
the main roll 12 is inclined so as to correspond to an outer
peripheral surface of the ring-rolled article 5 to be produced. The
mandrel roll 13 is also configured so as to be rotatable around a
rotational axis 13a which passes through the center of the mandrel
roll 13 and extends substantially in parallel with the center axis
4a of the drilled article 4. The outer peripheral surface of the
mandrel roll 13 is inclined so as to correspond to an inner
peripheral surface of the ring-rolled article 5 to be produced.
However, the present invention is not limited to this. More
specifically, the main roll and the mandrel roll may be formed in a
substantially cylindrical shape and the rotational axis of the main
roll and the mandrel roll may be respectively arranged so as to be
inclined in correspondence with the outer peripheral surface and
the inner peripheral surface in the ring-rolled article 5 to be
produced. In addition, the ring rolling apparatus 11 includes a
pair of axial rolls 14, 15 located on both sides of the drilled
article 4 in a center axis direction thereof. An outer peripheral
surface of the axial roll 14 and that of the axial roll 15 face
each other. Each of the axial rolls 14, 15 is configured so as to
be rotatable around a rotational axis 14a, 15a which passes through
the center of the corresponding axial roll.
[0034] In the ring rolling step S3 in which the above ring rolling
apparatus 11 is used, first, the drilled article 4 is charged into
the ring rolling apparatus 11. As an example, if the drilled
article 4 is to be produced by using Ni-base alloy718, it is
preferable that a heating temperature for the drilled article 4 to
be charged into the ring rolling apparatus 11, be in a range of 900
degrees C. to 1050 degrees C. However, the present invention is not
limited to this. More specifically, if the drilled article 4 is to
be produced by using a metal other than Ni-base alloy718, the
heating temperature may be set so as to be adapted to ring rolling
performed on the above drilled article 4. The outer peripheral
surface of the main roll 12 is brought into contact with the outer
peripheral surface of the drilled article 4, the outer peripheral
surface of the mandrel roll 13 is brought into contact with the
inner peripheral surface of the drilled article 4, and furthermore,
the outer peripheral surfaces of the axial roll pair 14, 15 are
respectively brought into contact with both surfaces of the drilled
article 4 in the center axis direction thereof. While the main roll
12 and the mandrel roll 13 are turned around the rotational axis
12a, 13a, respectively, the main roll 12 and the mandrel roll 13
sandwich and press the drilled article 4 in a radial direction of
the drilled article 4. In addition, while the axial rollers 14, 15
are turned around the rotational axis 14a, 15a, respectively, the
pair of axial rolls 14, 15 sandwich and press the drilled article 4
in the center axis direction of the drilled article 4. As a result,
the ring-rolled article 5 is produced.
[0035] The ring-rolled article 5 is formed so as to be shaped in a
substantially ring-like shape around a center axis 5a of the
ring-rolled article 5, and a half section of the ring-rolled
article 5 is formed so as to be inclined. More specifically, as
shown in FIG. 9, if the half section of the ring-rolled article 5
is divided into a one side region 5c and an another side region 5d
in a center axis direction of the ring-rolled article 5 based on a
middle line 5b for a maximum height h2 of the ring-rolled article 5
in the center axis direction thereof, a straight line 5g which
passes through a center of gravity 5e of the one side region 5e and
a center of gravity 5g of the another side region 5d, is inclined
by an angle .cndot.2 relative to a parallel line 5h which is in
parallel with the center axis 5a of the ring-rolled article 5, i.e.
relative to the center axis 5a of the ring-rolled article 5. It is
preferable that the angle .cndot.2 be in a range of 7 degrees to 40
degrees. Furthermore, it is more preferable that the angle .cndot.2
be in a range of 10 degrees to 25 degrees. This is because if the
angle .cndot.2 is in the above range, sufficient amount of strain
can be imparted to the material in the finishing forging step S4
described below so that the material may be appropriate,
particularly as a material for aircraft turbine disks. The angle
.cndot.2 in the one half section of the ring-rolled article 5 may
be either the same as or different from the angle .cndot.1 in the
one half section of the peripheral wall 3c of the rough-forged
article 3. If the angle .cndot.2 is different from the angle
.cndot.1, the drilled article 4 may be ring-rolled: such that the
above angle is changed.
[0036] In addition, as an example, the outer peripheral surface of
the ring-rolled article 5 may be formed in a substantially arc-like
shape which protrudes from the inner periphery of the ring-rolled
article 5 toward the outer periphery thereof. Furthermore, to form
the outer peripheral surface of the ring-rolled article 5 which is
formed in the substantially arc-like shape, the outer peripheral
surface of the main roll 12 may be formed in a substantially
arc-like shape which recesses from the inner periphery of the
ring-rolled article 5 toward outer periphery thereof so as to
correspond to the outer peripheral surface of the ring-rolled
article 5. The inner peripheral surface of the ring-rolled article
5 may be formed in a substantially arc-like shape which protrudes
from the outer periphery of the ring-rolled article 5 to the inner
periphery thereof. Furthermore, to form the inner peripheral
surface of the ring-rolled article 5 which is formed in the
above-described substantially arc-like shape, the outer peripheral
surface of the mandrel roll 13 may be formed in a substantially
arc-like shape which recesses from the outer periphery of the
ring-rolled article 5 to the inner periphery thereof so as to
correspond to the inner peripheral surface of the ring-rolled
article 5.
Regarding Finishing Forging Step S4
[0037] The finishing forging step S4 will be described below. In
the finishing forging step S4, a one side mold 16 and an another
side mold 17, shown in FIGS. 8(a) and 8(b), are used. The one side
mold 16 includes a concave portion 16a which corresponds to the one
side convex portion 1c of the ring molded article 1, and an opening
side concave portion 16b which corresponds to the one side region
in the base portion 1b of the ring molded article 1. The another
side mold 17 includes a concave portion 17a which corresponds to
the another side convex portion 1d of the ring molded article 1,
and an opening side concave portion 17b which corresponds to the
another side region of the base portion 1b of the ring molded
article 1.
[0038] In the finishing forging step S4, the ring-rolled article 5
is placed in the above two molds 16, 17, and then, the ring-rolled
article 5 is sandwiched and pressed by the two molds 16, 17 in a
center axis division of the ring-rolled article 5. As an example,
if the ring-rolled article 5 is produced by using Ni-base alloy718,
it is preferable that a heating temperature for the ring-rolled
article 5 placed in the two molds 16, 17 be in a range of 900
degrees C. to 1050 degrees C. However, the present invention is not
limited to this. More specifically, if the ring-rolled article 5 is
produced of a metal other than Ni-base alloy718, the heating
temperature may be set to a temperature adapted to the finishing
forging performed on the ring-rolled article 5.
[0039] In conditions in which the above ring-rolled article 5 is
arranged, the ring-rolled article 5 is supported by a region which
is located on the outer peripheral side from an outer peripheral
side corner 16c in a concave portion 16a of the one side mold 16
(this region will be hereafter be referred to as an "outer
peripheral side supporting region"), and a region which is located
on the inner peripheral side from an inner peripheral side corner
17c in a concave portion 17a of the another side mold 17 (this
region will he hereafter referred to as an "inner peripheral side
supporting region") Note that the above expression "outer
peripheral side corner 16c in the concave portion 16a" indicates a
corner located between an outer peripheral surface 16a1 in the
concave portion 16a of the one side mold 16 and an outer peripheral
side bottom surface 16b1 in the opening side concave portion 16b
thereof, and the above expression "inner peripheral side corner 17c
in the concave portion 17a" indicates a corner located between an
inner peripheral surface 17a1 in the concave portion 17a of the
another side mold 17 and an inner peripheral side bottom surface
17b1 in the opening side concave portion 17b thereof. Furthermore,
it is preferable that the ring-rolled article 5 be arranged so as
to be apart from regions other than the outer peripheral side
supporting region of the one side mold 16 and the inner peripheral
side supporting region of the another side mold 17. In other words,
both ends of the ring-rolled article 5 in a direction of the
inclined straight line 5g are in contact with the two molds 16, 17,
respectively, and the ring-rolled article 5 is restricted by the
two molds 16, 17 in the center axis direction of the ring-rolled
article 5 and in the radial direction of the ring-rolled article
5.
[0040] In particular, in the present Embodiment, as shown in FIG.
8(a), the ring-rolled article 5 is supported by the outer periphery
side bottom surface 16b1 and the outer peripheral surface 16b2 in
the opening side concave portion 16b of the one side mold 16 and
the inner peripheral side bottom surface 17b1 and the inner
peripheral surface 17b2 in the opening side concave portion 17b of
the another side mold 17. Furthermore, it is preferable that the
ring-rolled article be arranged so as to be apart from regions
other than the outer periphery side bottom surface 16b1 and the
outer peripheral surface 16b2 in the opening side concave portion
16b of the one side mold 16 and the inner peripheral side bottom
surface 17b1 and the inner peripheral surface 17b2 in the opening
side concave portion 17b of the another side mold 17.
[0041] Furthermore, in the finishing forging, the ring-rolled
article 5 in the form of fluid fills the concave portion 16a and
the opening side concave portion 16b of the one side mold 16 and
the concave portion 17a and the opening side concave portion 17b of
the another side mold 17. As a result, the ring molded article 1 is
produced.
[0042] According to the above method for manufacturing the ring
molded article 1 in the present Embodiment, the billet 2 is
processed by the rough forging so as to be formed in a shape
including the bottom 3b which is farmed in the substantially
cylindrical shape, and the peripheral wall 3c which is inclined to
the direction from the center of the bottom 3b toward the outer
periphery thereof, in the direction from the outer periphery of the
bottom 3b toward the one side in the direction of the center axis
of the bottom 3b, the rough-forged article 3 is thus produced, and
the bottom 3b of the rough-forged article 3 is drilled.
Furthermore, the ring-rolled article 5 is placed in the two molds
16, 17 on which the concave portions 16a, 17a respectively
corresponding to the convex portions 1c, 1d of the ring molded
article 1, the ring-rolled article 5 is then processed by the
finishing forging so that the ring-rolled article 5 is pressed by
the two molds 16, 17 in the direction of the center axis of the
ring-rolled article 5, and the ring molded article 1 is thus
produced. In particular, in the finishing forging step S4, when
placing the ring-rolled article 5 in the two molds 16, 17, the
ring-rolled article 5 is supported by the outer periphery side
supporting region of the one side mold 16 and the inner peripheral
side supporting region of the another side mold 17, and
furthermore, the ring-rolled article 5 is arranged so as to be
apart from the regions other than the outer periphery side
supporting region of the one side mold 16 and the inner peripheral
side supporting region of the other side mold 17. An outer
peripheral shape of the rough-forged article 3 is tapered from a
top thereof to the bottom 3b thereof, and dimension area of the
bottom 3b can be reduced. As a result, an amount of the bottom 3b
to be removed in the drilling step S2 can be reduced. Accordingly,
the ring molded article 1 can be efficiently produced. In addition,
in the finishing forging step S4, the contact area between the
ring-rolled article 5 and the two molds 16, 17 can be reduced, and
as a result, regions that the material of the ring-rolled article 5
adhere to the two molds 16, 17, can be reduced at the start of the
finishing forging and the initial stage of the finishing forging,
and thus, sufficient strain can be imparted to the ring molded
article 1 to be produced. In addition, it can be prevented that the
temperature of the surface regions of the ring-rolled article 5 is
reduced according to heat release to the two molds 16, 17, and
thus, it can be prevented that crystals of metal structure in the
surface regions of the produced ring molded article 1 is coarsened.
Accordingly, the ring molded article 1 in which dead metal regions
are reduced, can be reliably and efficiently produced. In addition,
the excess portions of the ring molded article 1 which is provided
in correspondence with the dead metal regions, can be reduced, and
thus, near-net-shape forging can be implemented. Furthermore, even
if the one side convex portion 1c and the another side convex
portion 1d of the ring molded article 1 are offset relative to each
other in the radial direction of the ring molded article 1, the
ring-rolled article 5 in the form of fluid securely fills into the
concave portions 16a, 17a of the two melds 16, 17, and thus, the
two convex portions 1c, 1d of the ring molded article 1 can be
securely formed.
[0043] According to the method for manufacturing the ring molded
article 1 in the present Embodiment, the inclination angle .cndot.1
of the one half section of the peripheral wall 3e is within the
range of 7 degrees to 40 degrees. Accordingly, since the
inclination angle .cndot.1 is 7 degrees or more, in the finishing
forging step S4, buckling of the ring-rolled article 5 can be
prevented. Furthermore, since the inclination angle .cndot.1 is 40
degrees or less, the size of the rough-forged article 3 can be
reduced, and furthermore, in the finishing forging step S4, a
phenomenon in which a desired shape cannot be obtained according to
unstable finishing forging caused by turning of the ring-rolled
article 5 (this phenomenon will hereafter be referred to as
"phenomenon of turning of the ring-rolled article 5"), can be
prevented. Accordingly, the ring molded article 1 in which the dead
metal regions are reduced, can be reliably and efficiently
produced.
[0044] According to the method for manufacturing the ring molded
article 1 in the present Embodiment, the inclination angle .cndot.2
of the ring-rolled article 5 which is placed in the two molds 16,
17, is within the range of 7 degrees to 40 degrees, at the start of
the finishing forging and the initial stage of the finishing
forging. Accordingly, since the inclination angle .cndot.2 is 7
degrees or more, in the finishing forging step S4, buckling of the
ring-rolled article 5 can be prevented. Furthermore, since the
inclination angle .cndot.2 is 40 degrees or less, the phenomenon of
turning of the ring-rolled article 5 can be prevented. Accordingly,
the ring molded article 1 in which the dead metal regions are
reduced, can be reliably and efficiently produced.
Second Embodiment
[0045] A method for manufacturing a ring molded article according
to a Second Embodiment of the present invention will be described.
Basic features of the ring material used for manufacturing the ring
molded article according to the present Embodiment are
substantially the same as those of the First Embodiment described
above. However, the method for manufacturing the ring molded
article according to the present Embodiment is different from the
method of the First Embodiment in the following.
[0046] Although not shown in the drawing, in the ring-rolled
article configured as the ring material, a recess section is formed
so as to correspond to the outer peripheral side corner of the
concave portion in the one side mold. As an example, the recess
section may be formed by machine working, such as cutting, press
working, or the like, after the ring rolling. In the finishing
forging step, this ring-rolled article is supported by the outer
peripheral side corner in the concave portion of the one side mold
which engages the recess section, and also supported by the inner
peripheral side bottom surface and the inner peripheral surface in
the opening side concave portion of the another side mold.
Furthermore, it is preferable that the ring-rolled article be
arranged so as to be apart from regions other than the outer
peripheral side corner in the concave portion of the one side mold
and the inner peripheral side bottom surface and the inner
peripheral surface in the opening side concave portion of the
another side mold.
[0047] According to the above method for manufacturing the ring
molded article in the present Embodiment, in addition to the
advantageous effects obtained by the First Embodiment, the
following advantageous effects can be obtained. That is to say,
since the recess section of the ring-rolled article engages the
outer peripheral side corner in the concave portion of the one side
mold, the ring-rolled article can be stably supported inside the
two molds. Accordingly, the ring-rolled article in which the dead
metal regions are reduced can be reliably and efficiently
produced.
Third Embodiment
[0048] A method for manufacturing a ring molded article according
to a Third Embodiment of the present invention will be described.
Basic features of the method for manufacturing the ring molded
article are substantially the same as those of the First Embodiment
described above. However, the method for manufacturing the ring
molded article according to the present Embodiment is different
from the method of the First Embodiment in the following.
[0049] Although not shown in the drawing, in the ring-rolled
article configured as the ring material, recess sections are formed
which respectively correspond to an outer peripheral side corner in
the concave portion of the one side mold and to an inner peripheral
side corner in the concave portion of the another side mold. As an
example, the recess sections may be formed by machine working, such
as cutting, press working, or the like, after the ring rolling. In
the finishing forging step, this ring-rolled article is supported
by the outer peripheral side corner in the concave portion of the
one side mold which engages the corresponding recess section of the
two recess sections, and also supported by the inner peripheral
side corner in the concave portion of the another side mold.
Furthermore, it is preferable that the ring-rolled article be
arranged so as to be apart from regions other than the outer
peripheral side corner in the concave portion of the one side mold
and the inner peripheral side corner in the opening side concave
portion of the another side mold.
[0050] According to the above method for manufacturing the ring
molded article in the present Embodiment, in addition to the
advantageous effects obtained by the First Embodiment, the
following advantageous effects can be obtained. That is to say,
since the recess sections of the ring-rolled article engage the
outer peripheral side corner in the concave potions of the one side
mold and the inner peripheral side corner in the concave potions of
the another side mold respectively, the ring-rolled article can be
stably supported inside the two molds. Accordingly, the ring-rolled
article in which the dead metal regions are reduced can be reliably
and efficiently produced.
[0051] The Embodiments of the present invention are as described
above; however, the present invention is not limited to them. More
specifically, the present invention can be implemented by various
modifications and alterations based on the technical idea of the
present invention.
[0052] For example, as a modification of the present invention, the
following feature may be employed. That is to say, in this feature,
if the concave portions 16a, 17a of the two molds 16, 17 which are
used in the finishing forging step S4, are offset in the radial
direction of the ring molded article 1 so as to correspond to the
one side convex portion 1c and the another side convex portion 1d
in the ring molded article 1 which are offset in the radial
direction, the ring-rolled article 5 can be supported in a
condition in which the one half section of the ring-rolled article
5 is not inclined, i.e., in a condition in which the inclination
angle .cndot.2 for the one half section is 0 degrees. In this
feature, for example, the one half section of the ring-rolled
article 5 may be formed in a substantially rectangular shape, and
furthermore, an amount of offset between the concave portions 16a,
17a of the two molds 16, 17 in the radial direction of the
ring-rolled article 5 may be less than a thickness of the one side
surface in the radial direction of the ring-rolled article 5. In
this feature, the ring-rolled article 5 can be supported by the
outer peripheral side supporting region of the one side mold 16 and
the inner peripheral side sup porting region of the another side
mold 17. If the above feature is employed, the forging can be
implemented such that the phenomenon of dead metal is suppressed.
However, in view of stable arrangement of the ring-rolled article 5
and freedom of shape of the ring-rolled article 5, it is preferable
to employ the feature in which the one half section of the
ring-rolled article is inclined.
EXAMPLE
[0053] An EXAMPLE of the present invention will be described. In
the present EXAMPLE, the ring molded article 1 to be produced has
dimensions with a maximum outer diameter of 1090 mm, a maximum
thickness in the radial direction of 120 mm, and a maximum height
in the direction of the center axis of 110 mm. In the finishing
forging step S4 used for producing this ring molded article 1, the
finishing forging step S4 is performed in a plurality of
arrangement conditions, respectively, in which the inclination
angle .cndot.2 for the inclined one half section of the ring-rolled
article 5 is set at 5 degrees, 7 degrees, 10 degrees, 20 degrees,
25 degrees, 30 degrees, 40 degrees, 45 degrees, or 50 degrees. In
the forging step for each arrangement condition, it is examined
whether buckling of the ring-rolled article 5 occurs. In addition,
in the forging step for each arrangement condition, it is examined
whether the phenomenon of turning of the ring-rolled article 5
occurs.
[0054] As a result of the above examination, in a ease in which the
inclination angle .cndot.2 is 5 degrees, buckling of the
ring-rolled article 5 occurs. In each of eases in which the
inclination angles .cndot.2 are 45 degrees and 50 degrees
respectively, the phenomenon of turning of the ring-rolled article
5 occurs. On the other hand, in each of cases in which the
inclination angles .cndot.2 are 7 degrees, 10 degrees, 20 degrees,
30 degrees, and 40 degrees, respectively, the ring molded article 1
in which dead metal regions are reduced, can be reliably and
efficiently produced. In each of cases in which the inclination
angles .cndot.2 are 10 degrees, 20 degrees, and 25 degrees
respectively, in particular, the ring molded article 1 in which
strain appropriate for applying to a material of aircraft turbine
disks is sufficiently imparted and the dead metal regions are
reduced, can be more reliably and more efficiently produced.
REFERENCE SIGNS LIST
[0055] 1 Ring Molded article [0056] 1a Center axis [0057] 1c One
side convex portion [0058] 1d Another side convex portion [0059] 2
Billet [0060] 3 Rough-forged article [0061] 3a Center axis [0062]
3b Bottom [0063] 3c Peripheral wall [0064] 3d Middle line [0065] 3e
One side region [0066] 3f Another side region [0067] 3g, 3h Center
of gravity [0068] 3i Straight line [0069] 3j Parallel line [0070] 4
Drilled article [0071] 5 Ring-rolled article (Ring material) [0072]
5a Center axis [0073] 5b Middle line [0074] 5e One side region
[0075] 5d Another side region [0076] 5e, 5f Center of gravity
[0077] 5g Straight line [0078] 5h Parallel line [0079] 16 One side
mold [0080] 16a Concave portion [0081] 16c Outer peripheral side
corner in the concave portion [0082] 17 Another side mold [0083]
17a Concave portion [0084] 17c Inner peripheral side corner in the
concave portion [0085] h1, h2 Maximum height [0086] .cndot.1,
.cndot.2 Angle [0087] S1 Rough forging step (First forging step)
[0088] S2 Drilling step [0089] S3 Ring rolling step [0090] S4
Finishing forging step (Second forging step)
* * * * *