U.S. patent application number 13/378873 was filed with the patent office on 2012-04-19 for zoning closed-die extruding device and method.
Invention is credited to Zhendong Chen, Qingping Lu, Yang Wang, Bojie Wu, Yongnian Yan, Renji Zhang, Xiaosong Zhang.
Application Number | 20120090375 13/378873 |
Document ID | / |
Family ID | 43355864 |
Filed Date | 2012-04-19 |
United States Patent
Application |
20120090375 |
Kind Code |
A1 |
Yan; Yongnian ; et
al. |
April 19, 2012 |
ZONING CLOSED-DIE EXTRUDING DEVICE AND METHOD
Abstract
A zoning closed-die extruding device comprises a closed female
die and a male die. which is disposed in a longitudinal direction
and configured to be mated with a closed cavity of the closed
female die to extrude a blank. The male die comprises an extruding
shaft portion and a stamp-extruding head portion, which is
connected with the extruding shaft portion and disposed below the
extruding shaft portion. A cross-sectional area of the
stamp-extruding head portion perpendicular to a longitudinal axis
of the closed female die is smaller than that of the extruding
shaft portion perpendicular to the longitudinal axis of the closed
female die. The male die is configured to rotate about the
longitudinal axis of the closed female die so that the blank is
sequentially and zonally deformed by the stamp-extruding head
portion inside the closed cavity of the closed female die.
Inventors: |
Yan; Yongnian; (Beijing,
CN) ; Zhang; Renji; (Jiangsu, CN) ; Lu;
Qingping; (Jiangsu, CN) ; Wu; Bojie; (Jiangsu,
CN) ; Chen; Zhendong; (Jiangsu, CN) ; Wang;
Yang; (Jiangsu, CN) ; Zhang; Xiaosong;
(Jiangsu, CN) |
Family ID: |
43355864 |
Appl. No.: |
13/378873 |
Filed: |
June 17, 2010 |
PCT Filed: |
June 17, 2010 |
PCT NO: |
PCT/CN2010/074026 |
371 Date: |
December 16, 2011 |
Current U.S.
Class: |
72/359 |
Current CPC
Class: |
B21J 5/008 20130101;
B21K 21/02 20130101; B21J 5/10 20130101; B21C 23/20 20130101 |
Class at
Publication: |
72/359 |
International
Class: |
B21J 9/02 20060101
B21J009/02; B21J 5/00 20060101 B21J005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 17, 2009 |
CN |
200910032470.5 |
Jun 17, 2009 |
CN |
200910032471.X |
Claims
1. A zoning closed-die extruding device, comprising: a closed
female die; and a male die disposed in a longitudinal direction and
configured to be mated with a closed cavity of the closed female
die to extrude a blank, wherein the male die comprises: an
extruding shaft portion; and a stamp-extruding head portion
connected with the extruding shaft portion and disposed below the
extruding shaft portion, in which a cross-sectional area of the
stamp-extruding head portion perpendicular to a longitudinal axis
of the closed female die is smaller than that of the extruding
shaft portion perpendicular to the longitudinal axis of the closed
female die; and the male die is configured to rotate about the
longitudinal axis of the closed female die so that the blank is
sequentially and zonally deformed by the stamp-extruding head
portion inside the closed cavity of the closed female die.
2. (canceled)
3. The zoning closed-die extruding device of claim 1, wherein the
extruding shaft portion comprises: a cylindrical shaft portion; and
a flange portion formed between a lower part of the cylindrical
shaft portion and the stamp-extruding head portion, in which the
cross-sectional area of the stamp-extruding head portion
perpendicular to the longitudinal axis of the closed female die is
smaller than that of the flange portion perpendicular to the
longitudinal axis of the closed female die.
4. The zoning closed-die extruding device of claim 1, wherein the
extruding shaft portion and the stamp-extruding head portion are
integrally formed, or the closed female die is a prestressed
extrusion die, and an inner diameter of the closed cavity of the
prestressed extrusion die is greater than a maximum radial
dimension of the extruding shaft portion and the stamp-extruding
head portion.
5. The zoning closed-die extruding device of claim 1, wherein a
cross section of the stamp-extruding head portion in a plane
perpendicular to the longitudinal axis of the closed female die is
of a rectangle shape, a long edge of the rectangle equals to a
diameter of the extruding shaft portion, and a ratio of a short
edge of the rectangle to the long edge thereof ranges from about
0.05 to about 0.95.
6. The zoning closed-die extruding device of claim 1, wherein a
ratio of the cross-sectional area of the stamp-extruding head
portion to the cross-sectional area of the extruding shaft portion
is within a range of about 0.1 to about 0.9.
7. The zoning closed-die extruding device of claim 1, wherein
during extruding, an extrusion force applied to the male die is
adapted to a width of the stamp-extruding head portion and a
diameter of the extruding shaft portion, or a central portion of
the stamp-extruding head portion is formed with a recess
portion.
8. (canceled)
9. (canceled)
10. A zoning closed-die extruding method, comprising: (1) placing a
blank formed with a central hole having a predetermined depth in a
closed female die and heating the blank to a temperature suitable
for closed die forging; and (2) sequentially and zonally extruding
the blank in the closed female die using a male die which is
rotatable about a longitudinal axis of the closed female die,
wherein the male die comprises: an extruding shaft portion; and a
stamp-extruding head portion connected with the extruding shaft
portion and disposed below the extruding shaft portion, in which a
cross-sectional area of the stamp-extruding head portion
perpendicular to the longitudinal axis of the closed female die is
smaller than that of the extruding shaft portion perpendicular to
the longitudinal axis of the closed female die.
11. The zoning closed-die extruding method of claim 10, wherein the
step (2) comprises: (2.1) extruding the blank along the central
hole using a predetermined extrusion force; (2.2) raising the male
die for restoration; (2.3) rotating the male die about the
longitudinal axis of the closed female die through a predetermined
angle; and (2.4) repeating the steps (2.1), (2.2) and (2.3).
12. The zoning closed-die extruding method of claim 10, wherein a
central portion of the stamp-extruding head portion is formed with
a recess portion.
13. The zoning closed-die extruding method of claim 10, wherein the
extruding shaft portion comprises: a cylindrical shaft portion; and
a flange portion formed between a lower part of the cylindrical
shaft portion and the stamp-extruding head portion, in which the
cross-sectional area of the stamp-extruding head portion
perpendicular to the longitudinal axis of the closed female die is
smaller than that of the flange portion perpendicular to the
longitudinal axis of the closed female die.
14. The zoning closed-die extruding method of claim 10, wherein in
the step (2), an extrusion force applied to the male die is adapted
to a width of the stamp-extruding head portion and a diameter of
the extruding shaft portion, and/or the extrusion force is about
1000 MN to about 1500 MN.
15. (canceled)
16. The zoning closed-die extruding method of claim 10, further
comprising: (3) finishing an inner surface of the sequentially and
zonally extruded blank in the step (2) along the central hole of
the blank using a finishing extrusion shaft so that the blank has
an even wall thickness.
17. The zoning closed-die extruding method of claim 16, wherein the
step (2) and the step (3) are alternately performed to extrude the
blank.
18. The zoning closed-die extruding method of claim 11, wherein the
predetermined angle is within a range of about 10 degrees to about
120 degrees.
19. The zoning closed-die extruding method of claim 11, wherein the
step (2) further comprises: finishing an inner surface of the
sequentially and zonally extruded blank along the central hole of
the blank using a finishing extrusion shaft so that the blank has
an even wall thickness.
20. The zoning closed-die extruding method of claim 16, wherein in
the step (2), a pressing displacement is within a range of about 2
mm to about 2000 mm, and a pressing displacement every time in the
step (3) is 0.01 times to 0.5 times as large as that in the step
(2).
21. (canceled)
22. The zoning closed-die extruding method of claim 10, wherein a
downward extrusion speed of the stamp-extruding head portion is
within a range of about 5 mm/s to about 90 mm/s when the blank is
made of a ferrous metal, or within a range of about 20 mm/s to
about 300 mm/s when the blank is made of a nonferrous metal.
23. The zoning closed-die extruding method of claim 10, wherein the
closed female die is a prestressed extrusion die, and an inner
diameter of the closed cavity of the prestressed extrusion die is
greater than a maximum radial dimension of the extruding shaft
portion and the stamp-extruding head portion.
24. The zoning closed-die extruding method of claim 10, wherein the
central hole with the predetermined depth is formed by closed
upsetting, impressing and hot piercing the blank in the closed
female die respectively, and the extruding shaft portion and the
stamp-extruding head portion are integrally formed.
25. (canceled)
26. The zoning closed-die extruding method of claim 10, wherein the
closed female die is a prestressed extrusion die, and an inner
diameter of the closed cavity of the prestressed extrusion die is
greater than a maximum radial dimension of the extruding shaft
portion and the stamp-extruding head portion, or a cross section of
the stamp-extruding head portion is of a rectangle shape, a long
edge of the rectangle equals to a diameter of the extruding shaft
portion, and a ratio of a short edge of the rectangle to the long
edge thereof is within a range of about 0.05 to about 0.95, or a
ratio of the cross-sectional area of the stamp-extruding head
portion to the cross-sectional area of the extruding shaft portion
is within a range of about 0.1 to about 0.9.
27. (canceled)
28. (canceled)
Description
FIELD
[0001] The present disclosure relates to the field of material
processing, and more particularly to a zoning closed-die extruding
device and a zoning closed-die extruding method.
BACKGROUND
[0002] Development of nuclear power has been one of the national
strategic goals and national development tasks, and a pressure
vessel for a nuclear reactor in a nuclear island urgently needs to
be domestically manufactured. The pressure vessel for the nuclear
reactor in Qinshan nuclear power station and Daya Bay nuclear power
station, China, are imported from Alstom, France and Nippon Steel
Corporation, which are very expensive. For the development of clean
energy and the reduction of CO.sub.2 emissions, by 2020, China
plans to add 80 million KW of nuclear power installed capacity, and
there is a need for about eighty one-million-KW class pressure
vessels. The total price for eighty 0.4 million KW-class pressure
vessels ranges from 40 billion yuan to 48 billion yuan. In China,
self-manufacturing of the pressure vessel for the nuclear reactor
needs to be urgently and quickly solved, which is a complex
engineering and technical issue.
[0003] The nuclear reactor pressure vessel is usually manufactured
by saddle forging, hollow ingot mandrel reaming, thick plate head
pressing and girth welding etc. Since the Chernobyl nuclear
accident in Soviet Union, longitudinal seam welding used for
forming the nuclear reactor pressure vessel has been banned.
Currently, the nuclear reactor pressure vessel is substantially
manufactured by the saddle forging as shown in FIG. 1. Firstly, as
shown in FIG. 1, five rings 100' are made, and then the five rings
100' are welded to form a straight cylinder portion of the pressure
vessel. Then, a head 200' or 200'' is formed by pressing or drawing
a thick plate, as shown in FIGS. 2-3. The straight cylinder portion
and the head are welded, heat treated and processed to obtain the
nuclear reactor pressure vessel 300', as shown in FIG. 4. However,
this process involves many steps which are complex with low
efficiency and low reliability. This is because, whether during the
process of forming the ring 100' or during the process of forming
the head 200' by pressing or drawing, the forming is not performed
in a three-directional compressive stress state, and in the forming
process, usually along with local tensile stress, there is a heavy
potential risk for closure and restoration of cracks and
defects.
[0004] In addition, currently, in a large number of nuclear power
heavy-duty forging process, the change in the shape of an anvil,
pressing and feeding processes etc. which are performed under a
pressing force of 10,000 to 20,000 tons, may also not produce
enough three-directional compressive stress and may also not reduce
or eliminate the tensile stress. In addition, the deformation
amount during the process is difficult to uniformize FIG. 5 is a
schematic view of a conventional rotary extruding press. As shown
in FIG. 5, a circular blank 103'' in FIG. 5 is forged by firstly
lifting an upper male die 101'' to a predetermined height, rotating
the upper male die 101'' by a certain angle and then lowering the
upper male die 101'' in a lower female die 102''. However, it has
been found through research that, in the open forging process,
because extruding force is merely applied to materials in one
direction as shown in FIG. 5 and the spherical tensor of stress
only reaches about 80 MPa, it is still difficult to close and
restore cracks and defects in the deformed materials.
SUMMARY
[0005] The present disclosure is directed to solve at least one of
the problems existing in the prior art. Accordingly, a zoning
closed-die extruding method may need to be provided, by which a
formed vessel may have an even wall thickness, a high reliability
and a high strength, and cracks and defects in the vessel may be
thoroughly closed and repaired. Further, a zoning closed-die
extruding device may also need to be provided.
[0006] According to an aspect of the present disclosure, a zoning
closed-die extruding device may be provided. The zoning closed-die
extruding device may comprise: a closed female die; and a male die
disposed in a longitudinal direction and configured to be mated
with a closed cavity of the closed female die to extrude a blank,
in which the male die comprises: an extruding shaft portion; and a
stamp-extruding head portion connected with the extruding shaft
portion and disposed below the extruding shaft portion, in which a
cross-sectional area of the stamp-extruding head portion
perpendicular to a longitudinal axis of the closed female die is
smaller than that of the extruding shaft portion perpendicular to
the longitudinal axis of the closed female die; and the male die is
configured to rotate about the longitudinal axis of the closed
female die so that the blank is sequentially and zonally by the
stamp-extruding head portion inside the closed cavity of the closed
female die.
[0007] In the zoning closed-die extruding device according to an
embodiment of the present disclosure, by sequentially and zonally
extruding the blank in the closed female die using the male die,
metal may flow in a radial direction to form a bottom of the vessel
and may rise along a generatrix of the vessel to form a cylindrical
portion of the vessel, so that one-step forming of the cylinder
body and the head of the vessel may be achieved without girth
welding. Therefore, this process may have reduced manufacturing
steps with reduced complexity, shortened production period and
enhance efficiency. In addition, because the metal is extruded in
the closed female die using the male die, the blank is
substantially deformed in a three-directional compressive stress
state, the tensile stress during the deforming process may be
reduced to a minimum extent or even eliminated, so that the vessel
may have an even wall thickness with high reliability and strength,
and cracks and defects etc. may be thoroughly closed and
restored.
[0008] According to an embodiment of the present disclosure, the
extruding shaft portion and the stamp-extruding head portion are
integrally formed.
[0009] According to an embodiment of the present disclosure, the
extruding shaft portion comprises: a cylindrical shaft portion; and
a flange portion formed between a lower part of the cylindrical
shaft portion and the stamp-extruding head portion, in which the
cross-sectional area of the stamp-extruding head portion
perpendicular to the longitudinal axis of the closed female die is
smaller than that of the flange portion perpendicular to the
longitudinal axis of the closed female die.
[0010] According to an embodiment of the present disclosure, the
closed female die is a prestressed extrusion die, and an inner
diameter of the closed cavity of the prestressed extrusion die is
greater than a maximum radial dimension of the extruding shaft
portion and the stamp-extruding head portion.
[0011] According to an embodiment of the present disclosure, a
cross section of the stamp-extruding head portion in a plane
perpendicular to the longitudinal axis of the closed female die is
of a rectangle shape, a long edge of the rectangle equals to a
diameter of the extruding shaft portion, and a ratio of a short
edge of the rectangle to the long edge thereof ranges from about
0.05 to about 0.95.
[0012] According to an embodiment of the present disclosure, a
ratio of the cross-sectional area of the stamp-extruding head
portion to the cross-sectional area of the extruding shaft portion
is within a range of about 0.1 to about 0.9. Then the blank may be
sequentially and zonally deformed with the stamp-extruding head
portion.
[0013] According to an embodiment of the present disclosure, during
extruding, an extrusion force applied to the male die is adapted to
a width of the stamp-extruding head portion and a diameter of the
extruding shaft portion.
[0014] According to an embodiment of the present disclosure, the
extrusion force is about 1000 MN to about 1500 MN.
[0015] According to an embodiment of the present disclosure, a
central portion of the stamp-extruding head portion is formed with
a recess portion.
[0016] According to another aspect of the present disclosure, a
zoning closed-die extruding method may be provided. The zoning
closed-die extruding method may comprise: (1) placing a blank
formed with a central hole having a predetermined depth in a closed
female die and heating the blank to a temperature suitable for
closed die forging; and (2) sequentially and zonally extruding the
blank in the closed female die using a male die which is rotated
about a longitudinal axis of the closed female die, in which the
male die comprises: an extruding shaft portion; and a
stamp-extruding head portion connected with the extruding shaft
portion and disposed below the extruding shaft portion, in which a
cross-sectional area of the stamp-extruding head portion
perpendicular to the longitudinal axis of the closed female die is
smaller than that of the extruding shaft portion perpendicular to
the longitudinal axis of the closed female die.
[0017] In the zoning closed-die extruding method according to an
embodiment of the present disclosure, by sequentially and zonally
extruding the blank in the closed female die using the male die, a
metal may flow in a radial direction to form a bottom of the vessel
and may rise along a generatrix of the vessel to form a cylindrical
portion of the vessel, so that one-step forming of the cylinder
body and the head of the vessel may be achieved without girth
welding. Therefore, this process may have reduced manufacturing
steps with reduced complexity, shortened production period and
enhance efficiency. In addition, because the metal is extruded in
the closed female die using the male die, the blank is
substantially deformed in a three-directional compressive stress
state, the tensile stress during the deforming process may be
reduced to a minimum extent or even eliminated, so that the vessel
may have an even wall thickness with high reliability and strength,
and cracks and defects etc. may be thoroughly closed and
restored.
[0018] According to an embodiment of the present disclosure, the
step (2) comprises: (2.1) extruding the blank along the central
hole using a predetermined extrusion force; (2.2) raising the male
die for restoration; (2.3) rotating the male die about the
longitudinal axis of the closed female die through a predetermined
angle; and (2.4) repeating the steps (2.1), (2.2) and (2.3).
[0019] According to an embodiment of the present disclosure, a
central portion of the stamp-extruding head portion is formed with
a recess portion.
[0020] According to an embodiment of the present disclosure, in the
step (2), an extrusion force applied to the male die is adapted to
a width of the stamp-extruding head portion and a diameter of the
extruding shaft portion.
[0021] According to an embodiment of the present disclosure, the
extruding shaft portion comprises: a cylindrical shaft portion; and
a flange portion formed between a lower part of the cylindrical
shaft portion and the stamp-extruding head portion, in which the
cross-sectional area of the stamp-extruding head portion
perpendicular to the longitudinal axis of the closed female die is
smaller than that of the flange portion perpendicular to the
longitudinal axis of the closed female die.
[0022] According to an embodiment of the present disclosure, the
extrusion force is about 1000 MN to about 1500 MN.
[0023] According to an embodiment of the present disclosure, the
zoning closed-die extruding method further comprises: (3) finishing
an inner surface of the zonally extruded blank in the step (2)
along the central hole of the blank using a finishing extrusion
shaft so that the blank has an even wall thickness.
[0024] According to an embodiment of the present disclosure, the
step (2) and the step (3) are alternately performed to extrude the
blank.
[0025] According to an embodiment of the present disclosure, the
predetermined angle is within a range of about 10 degrees to about
120 degrees.
[0026] According to an embodiment of the present disclosure, the
step (2) further comprises: finishing an inner surface of the
zonally extruded blank along the central hole of the blank using a
finishing extrusion shaft so that the blank has an even wall
thickness.
[0027] According to an embodiment of the present disclosure, in the
step (2), a pressing displacement is within a range of about 2 mm
to about 2000 mm.
[0028] According to an embodiment of the present disclosure, a
pressing displacement every time in the step (3) is 0.01 times to
0.5 times as large as that in the step (2).
[0029] According to an embodiment of the present disclosure, a
downward extrusion speed of the stamp-extruding head portion is
within a range of about 5 mm/s to about 90 mm/s when the blank is
made of a ferrous metal, or within a range of about 20 mm/s to
about 300 mm/s when the blank is made of a nonferrous metal.
[0030] According to an embodiment of the present disclosure, the
closed female die is a prestressed extrusion die, and an inner
diameter of the closed cavity of the prestressed extrusion die is
greater than a maximum radial dimension of the extruding shaft
portion and the stamp-extruding head portion.
[0031] According to an embodiment of the present disclosure, the
central hole with the predetermined depth is formed by closed
upsetting, impressing and hot piercing the blank in the closed
female die respectively.
[0032] According to an embodiment of the present disclosure, the
extruding shaft portion and the stamp-extruding head portion are
integrally formed.
[0033] According to an embodiment of the present disclosure, the
closed female die is a prestressed extrusion die, and an inner
diameter of the closed cavity of the prestressed extrusion die is
greater than a maximum radial dimension of the extruding shaft
portion and the stamp-extruding head portion.
[0034] According to an embodiment of the present disclosure, a
cross section of the stamp-extruding head portion is of a rectangle
shape, a long edge of the rectangle equals to a diameter of the
extruding shaft portion, and a ratio of a short edge of the
rectangle to the long edge thereof is within a range of about 0.05
to about 0.95.
[0035] According to an embodiment of the present disclosure, a
ratio of the cross-sectional area of the stamp-extruding head
portion to the cross-sectional area of the extruding shaft portion
is within a range of about 0.1 to about 0.9.
[0036] The zoning closed-die extruding method according to an
embodiment of the present disclosure may also be used for forming a
high-pressure or ultrahigh-pressure vessel with a high reliability
and a large volume such as a nuclear evaporator, a hydrogenation
reactor or a large-volume natural gas high-pressure vessel.
[0037] Additional aspects and advantages of the embodiments of the
present disclosure will be given in part in the following
descriptions, become apparent in part from the following
descriptions, or be learned from the practice of the embodiments of
the present disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] These and other aspects and advantages of the disclosure
will become apparent and more readily appreciated from the
following descriptions taken in conjunction with the drawings in
which:
[0039] FIG. 1 is a perspective view of a straight cylinder portion
for manufacturing a conventional pressure vessel;
[0040] FIG. 2 is a sectional view of a head of a conventional
pressure vessel manufactured by pressing;
[0041] FIG. 3 is a sectional view of a head of a conventional
pressure vessel manufactured by drawing;
[0042] FIG. 4 is a schematic view of a conventional nuclear reactor
pressure vessel;
[0043] FIG. 5 is a schematic view of a conventional rotary
extruding press;
[0044] FIG. 6 is a perspective view of a zoning closed-die
extruding device according to an embodiment of the present
disclosure;
[0045] FIG. 7 is a front view of a male die in a zoning closed-die
extruding device according to an embodiment of the present
disclosure;
[0046] FIG. 8 is a left view of a male die in a zoning closed-die
extruding device according to an embodiment of the present
disclosure;
[0047] FIG. 9 shows a zonally extruding step in a zoning closed-die
extruding method according to an embodiment of the present
disclosure;
[0048] FIG. 10 shows a finishing step in a zoning closed-die
extruding method according to an embodiment of the present
disclosure;
[0049] FIG. 11 is a schematic view of a blank in a zoning
closed-die extruding method according to an embodiment of the
present disclosure;
[0050] FIG. 12 shows that a blank is upset in a zoning closed-die
extruding method according to an embodiment of the present
disclosure;
[0051] FIG. 13 shows that a blank is impressed in a zoning
closed-die extruding method according to an embodiment of the
present disclosure;
[0052] FIG. 14 shows that a blank is hot pierced in a zoning
closed-die extruding method according to an embodiment of the
present disclosure; and
[0053] FIG. 15 shows that the blank is reamed after the hot
piercing step shown in FIG. 14.
DETAILED DESCRIPTION
[0054] Embodiments of the present disclosure will be described in
detail in the following descriptions, examples of which are shown
in the accompanying drawings, in which the same or similar elements
and elements having same or similar functions are denoted by like
reference numerals throughout the descriptions. The embodiments
described herein with reference to the accompanying drawings are
explanatory and illustrative, which are used to generally
understand the present disclosure. The embodiments shall not be
construed to limit the present disclosure.
[0055] The inventive concept of the present disclosure is that, by
largely increasing a pressing force and under the constraint of a
die, a zoning closed-die extruding method is used to increase a
three-directional compressive stress, reduce and eliminate a
tensile stress, and increase and uniformize deformation amount,
thus closing and repairing or restoring cracks and defects and
enhancing the reliability and the strength of a vessel. In
addition, in a deforming method and die according to an embodiment
of the present disclosure, the optimum condition for metal flowing
and segregation eliminating may be created.
[0056] It should be noted that, as used herein, the term "zoning
extruding" means that material is extruded sequentially in a
chamber or cavity region by region, neighboring or non-neighboring
and finally the material is sequentially deformed by a plurality of
sub-region or local deformations.
[0057] In the deforming process of the material, a spherical tensor
.sigma..sub.m of stress is usually used as a quantitative indicator
of a crack closing and/or soldering probability after the material
is deformed.
[0058] Particularly, in a deformed piece, a stress tensor
.sigma..sub.ij at any point may be a sum of two tensors, i.e., a
spherical tensor of stress .sigma..sub.m and a deviatoric tensor of
stress S.sub.ij.
[0059] The stress tensor .sigma..sub.ij is represented by a
formula:
.sigma. ij = .sigma. m .delta. ij + S ij [ .sigma. x .tau. xy .tau.
xz .tau. yx .sigma. y .tau. yz .tau. zx .tau. zy .sigma. z ] = [
.sigma. m 0 0 0 .sigma. m 0 0 0 .sigma. m ] + [ .sigma. x - .sigma.
m .tau. xy .tau. xz .tau. yx .sigma. y - .sigma. m .tau. yz .tau.
zx .tau. zy .sigma. z - .sigma. m ] ##EQU00001##
[0060] According to an embodiment of the present disclosure, by
sequentially and zonally extruding a blank in a closed female die,
a large and even spherical tensor of stress .sigma..sub.m may be
provided, thus ensuring the closure of microscopic defects and
cracks, acquiring an optimum soldering condition and creating a
superior thermo-mechanical coupling condition.
[0061] Hereinafter, a zoning closed-die extruding device and a
zoning closed-die extruding method according to an embodiment of
the present disclosure will be described in detail with reference
to the drawings, in which FIG. 6 is a perspective view of a zoning
closed-die extruding device 100 according to an embodiment of the
present disclosure; FIG. 7 is a front view of a male die 9 in a
zoning closed-die extruding device 100 according to an embodiment
of the present disclosure; and FIG. 8 is a left view of a male die
9 in a zoning closed-die extruding device 100 according to an
embodiment of the present disclosure.
[0062] According to an embodiment of the present disclosure, the
zoning closed-die extruding device 100 may comprise: a closed
female die 6; and a male die 9 disposed in a longitudinal direction
and configured to be mated with a closed cavity 61 of the closed
female die 6 to extrude a blank. The male die 9 may comprise: an
extruding shaft portion 92; and a stamp-extruding head portion 93
connected with the extruding shaft portion 92 and disposed below
the extruding shaft portion 92, in which a cross-sectional area of
the stamp-extruding head portion 93 perpendicular to a longitudinal
axis of the closed female die 6 is smaller than that of the
extruding shaft portion 92 perpendicular to the longitudinal axis
of the closed female die 6. According to an embodiment of the
present disclosure, the male die 9 is configured to rotate about
the longitudinal axis of the closed female die 6 so that the blank
is sequentially and zonally deformed by the stamp-extruding head
portion 93 inside the closed cavity 61 of the closed female die
6.
[0063] In the zoning closed-die extruding device 100 according to
an embodiment of the present disclosure, by sequentially and
zonally extruding the blank in the closed female die 6 using the
male die 9, metal may flow in a radial direction to form a bottom
of the vessel and may rise along a generatrix of the vessel to form
a cylindrical portion of the vessel, so that one-step forming of
the cylinder body and the head of the vessel may be achieved
without girth welding. Therefore, this process may have reduced
manufacturing steps with reduced complexity, shortened production
period and enhance efficiency.
[0064] In addition, because the metal is extruded in the closed
female die 6 using the male die 9, the blank is substantially
deformed in a three-directional compressive stress state, the
tensile stress during the deforming process may be reduced to a
minimum extent or even eliminated, so that the vessel may have an
even wall thickness with high reliability and strength, and cracks
and defects etc. may be thoroughly closed and restored or
restored.
[0065] According to an embodiment of the present disclosure, the
extruding shaft portion 92 and the stamp-extruding head portion 93
may be integrally formed. Alternatively, the extruding shaft
portion 92 and the stamp-extruding head portion 93 may be
separately formed, so that the stamp-extruding head portion 93 may
be conveniently replaced to reduce the manufacturing cost of the
male die 9. As shown in FIG. 8, the extruding shaft portion 92 may
comprise: a cylindrical shaft portion 921; and a flange portion 922
formed between a lower part of the cylindrical shaft portion 921
and the stamp-extruding head portion 93, in which the
cross-sectional area of the stamp-extruding head portion 93
perpendicular to the longitudinal axis of the closed female die 6
is smaller than that of the flange portion 922 perpendicular to the
longitudinal axis of the closed female die 6. Therefore, during the
forming process, only the flange portion 922 may contact with an
inner surface of the blank to be extruded, thus reducing the metal
deforming resistance during the forming process.
[0066] According to an embodiment of the present disclosure, the
closed female die 6 may be a prestressed extrusion die, thus
increasing the safety of the extruding process. An inner diameter
of the closed cavity 61 of the prestressed extrusion die is greater
than a maximum radial dimension of the extruding shaft portion 92
and the stamp-extruding head portion 93. The dimension difference
may be designed and determined according to a piece to be
extruded.
[0067] According to an embodiment of the present disclosure, a
cross section of the stamp-extruding head portion 93 in a plane
perpendicular to the longitudinal axis of the closed female die 6
is of a rectangle shape, a long edge of the rectangle equals to a
diameter of the extruding shaft portion 92, and a ratio of a short
edge of the rectangle to the long edge thereof is within a range of
about 0.05 to about 0.95, which may be selected according to
practical requirements.
[0068] According to an embodiment of the present disclosure, a
ratio of the cross-sectional area of the stamp-extruding head
portion 93 to the cross-sectional area of the extruding shaft
portion 92 is within a range of about 0.1 to about 0.9. Therefore,
the blank may be sequentially and zonally extruded using the
stamp-extruding head portion 93.
[0069] According to an embodiment of the present disclosure, during
the forming process, an extrusion force applied to the male die 9
is adapted to a width of the stamp-extruding head portion 93 and a
diameter of the extruding shaft portion 92.
[0070] According to an embodiment of the present disclosure, the
extrusion force is about 1000 MN to about 1500 MN, which is
different from the deforming force of about 100 MN to about 200 MN
used in the prior art. The extrusion force may be combined with the
abovementioned zoning closed-die extruding device, thus providing a
large extrusion stress to the blank during the forming process of
the blank so as to eliminate microscopic crystal defects and the
like during the deforming process.
[0071] According to an embodiment of the present disclosure, a
central portion of the stamp-extruding head portion 93 is formed
with a recess portion 94. In this way, during the extruding process
of the male die 9, the three-directional compressive stress may be
formed in the material received in the recess portion 94, as shown
in FIG. 9. Therefore, the tensile stress during the forming process
may be reduced to a minimum extent or even eliminated, so that the
vessel may have an even wall with high reliability and strength,
and cracks and defects etc. may be thoroughly closed and restored
or repaired.
[0072] According to an embodiment of the present disclosure, the
closed cavity 61 of the closed female die 6 may be circular,
rectangular or elliptic, and a cross section of at least part of
the extruding shaft portion 92 may be rectangular, polygonal or
elliptic.
[0073] During the operation process of the zoning closed-die
extruding device 100, because the cross-sectional area of the
stamp-extruding head portion 93 is smaller than that of the
extruding shaft portion 92, the extrusion force may be effectively
reduced, the extruding efficiency may be enhanced, and the ratio of
the cross-sectional area of the stamp-extruding head portion 93 to
the cross-sectional area of the extruding shaft portion 92 may be
in a function relation to the extrusion force. As described above,
the cross section of the stamp-extruding head portion 93 is of a
rectangle shape, the long edge of the rectangle equals to the
diameter of the extruding shaft portion 92, a ratio of the short
edge, i.e., the width, of the rectangle to the diameter of the
extruding shaft portion 92 is in a function relation to the
extrusion force, the closed female die 6, the extruding shaft
portion 92 and the stamp-extruding head portion 93 are coaxial, and
the closed female die 6 may be a cylinder having an upper opening
with an inner diameter larger than outer diameters of the extruding
shaft portion 92 and the stamp-extruding head portion 93. In use,
an upper end of the extruding shaft portion 92 is detachably fixed
on a pressing device of an extruding press (not shown), and a lower
end of the closed female die 6 is detachably fixed on a work table
of the extruding press. Because the metal is sequentially and
zonally extruded by the extruding shaft portion 92 and the
stamp-extruding head portion 93 in the closed cavity 61 of the
closed female die 6 under a huge three-directional compressive
stress, the metal may flow in the radial direction to form the
bottom of the vessel and may rise along the generatrix of the
vessel to form the cylindrical portion of the vessel as shown in
FIG. 9, so that one-step forming of the cylindrical vessel may be
achieved. Moreover, the metal is extruded under the
three-directional compressive stress, thus ensuring the strength of
the vessel 1.
[0074] Hereinafter, a zoning closed-die extruding method according
to an embodiment of the present disclosure will be described with
reference to the drawings.
[0075] The zoning closed-die extruding method according to an
embodiment of the present disclosure may comprise: (1) placing a
blank formed with a central hole having a predetermined depth in a
closed female die 6 and heating the blank to a temperature suitable
for closed extruding; and (2) sequentially and zonally extruding
the blank in the closed female die 6 using a male die 9 which is
rotated about a longitudinal axis of the closed female die 6, in
which the male die 9 comprises: an extruding shaft portion 92; and
a stamp-extruding head portion 93 connected with the extruding
shaft portion 92 and disposed below the extruding shaft portion 92,
in which a cross-sectional area of the stamp-extruding head portion
93 perpendicular to the longitudinal axis of the closed female die
6 is smaller than that of the extruding shaft portion 92
perpendicular to the longitudinal axis of the closed female die 6.
Herein, the male die 9 may be any one of the male dies 9 described
above.
[0076] In the zoning closed-die extruding method according to an
embodiment of the present disclosure, by sequentially and zonally
extruding the blank in the closed female die 6 using the male die
9, a metal may flow in a radial direction to form a bottom 11 of
the vessel and may rise along a generatrix of the vessel to form a
cylindrical portion 12 of the vessel, so that one-step forming of
the cylinder body and the head of the vessel may be achieved
without girth welding. Therefore, this process may have reduced
manufacturing steps with reduced complexity, shortened production
period and enhance efficiency. In addition, because the metal is
extruded in the closed female die 6 using the male die 9, the blank
is substantially deformed in a three-directional compressive stress
state, the tensile stress during the deforming process may be
reduced to a minimum extent or even eliminated, so that the vessel
may have an even wall with high reliability and strength, and
cracks and defects etc. may be thoroughly closed and restored or
repaired
[0077] The blank 1 formed with the central hole having the
predetermined depth will be described below with reference to the
drawings, in which FIG. 11 is a schematic view of a blank 1 in a
zoning closed-die extruding method according to an embodiment of
the present disclosure, FIG. 12 shows that a blank 1 is upset in a
zoning closed-die extruding method according to an embodiment of
the present disclosure; FIG. 13 shows that a blank 1 is impressed
in a zoning closed-die extruding method according to an embodiment
of the present disclosure; FIG. 14 shows that a blank 1 is hot
pierced in a zoning closed-die extruding method according to an
embodiment of the present disclosure; and FIG. 15 shows that the
blank 1 is reamed after the hot piercing step in FIG. 14.
[0078] Firstly, the refined blank 1 is provided and heated to a
temperature suitable for closed extruding, for example, a
temperature in a range of about 1050 Celsius degrees to about 1250
Celsius degrees. Then, according to practical requirements, a blank
riser 2 is removed using a flame cutting method with
oxygen-acetylene flame and the like. Sometimes, both the blank
riser 2 and a bottom of the blank 1 need to be removed. However,
whether the bottom of the blank 1 needs to be removed depends on
the practical refining quality of the bottom of the blank 1.
[0079] Then, the blank 1 is upset, as shown in FIG. 12. In FIG. 12,
the bottom of the blank 1 is formed with a centering portion 3. The
blank 1 is placed on an upsetting die 4 while an arc-shaped
protrusion 11 on the bottom of the blank 1 is just disposed in a
centering groove 41 of the upsetting die 4, and then force is
applied to an upper part of the blank 1 to upset the blank 1. In
this way, the regular centering portion 3 is formed from the
arc-shaped protrusion 11 on the bottom of the blank 1 while the
blank 1 is upset. The blank 1 may be open or closed upset in an
open or closed die respectively.
[0080] Then, the upset blank 1 may be impressed, as shown in FIG.
13. The blank 1 may be firstly centered using the centering portion
3 of the blank 1, and then an upper surface 13 of the blank 1 is
stamped by a central punch 5 having a guiding device to form a
central hole 12 having a predetermined depth and a predetermined
diameter.
[0081] Then, the blank 1 formed with the central hole 12 is hot
pierced. That is, the blank 1 formed with the central hole 12 is
fitted in place in the closed female die 6. A first pecker 7 moves
downwards to extrude the blank 1 while a center of the first pecker
7 is aligned with the central hole 12 in the upper surface 13 of
the blank 1, so that the depth and the diameter of the central hole
12 in the upper surface 13 of the blank 1 are increased to
predetermined values.
[0082] Then, the blank 1 is subjected to a sequential and zonal
extruding. As shown in FIG. 6, the blank 1 is placed in the closed
female die 6 and positioned using the centering portion 3 on the
bottom of the blank 1, with the centering portion 3 on the bottom
of the blank 1 facing down. The metal is extruded by the extruding
shaft portion 92 and the stamp-extruding head portion 93 along the
central hole 12 of the blank 1 under an extrusion force of about
1000 MN to about 1500 MN so that the metal may flow in the radial
direction to form the bottom 11 of the vessel and may rise along
the generatrix of the vessel to form the cylindrical portion 12 of
the vessel, and then the stamp-extruding head portion 93 moves
upwards for restoration along with the extruding shaft portion 92
and is rotated radially by a predetermined angle .alpha. along with
the extruding shaft portion 92. Afterwards, the metal is extruded
by the extruding shaft portion 92 and the stamp-extruding head
portion 93 along the central hole 12 of the blank 1 again, and the
above steps are repeated until an upper end face of an extruded
blank formed from the blank 1 becomes flat. In each process step,
the stamp-extruding head portion 93 is rotated through one
predetermined angle .alpha. along with the extruding shaft portion
92.
[0083] This process is as follows. The blank 1 is placed in the
closed female die 6 and sequentially and zonally extruded by the
extruding shaft portion 92 and the stamp-extruding head portion 93
repeatedly. After extruded by the stamp-extruding head portion 93,
the metal substantially radially flows towards a direction away
from the stamp-extruding head portion 93. According to the law of
least resistance on metal flowing proposed by Ivan Gubkin, a former
Soviet Union scholar, the metal flows most quickly in a position
where a distance between the stamp-extruding head portion 93 and an
inner wall of the central hole 12 of the blank 1 is largest. In
this way, when the central hole 12 of the blank 1 is extruded by
the stamp-extruding head portion 93, the flowing metal enters into
a clearance between the closed female die 6 and the extruding shaft
portion 92 to flow upwards along the generatrix of the vessel, so
that the height of a part of the cylindrical portion 12 of the
vessel at this position where the metal flows most quickly is
larger than that of other parts of the cylindrical portion 12 of
the vessel. Because the stamp-extruding head portion 93 is
unidirectionally and successively rotated in the central hole 12 of
the blank 1, and the stamp-extruding head portion 93 is rotated by
the predetermined angle .alpha. after each zoning extruding process
step, so that the upper end of the extruded blank formed from the
blank 1 finally becomes flat. Apparently, the smaller the
predetermined angle .alpha. by which the stamp-extruding head
portion 93 is radially rotated, the smaller the height difference
of the upper end of the extruded blank formed from the blank 1 is.
A plurality of zoning extruding process steps constitutes one
zoning extruding step. That is, one zoning extruding step comprises
a plurality of zoning extruding process steps. A zoning extruding
process step number=360/the predetermined angle .alpha..
[0084] After the above zoning extruding step, the blank 1 is
finished accordingly as shown in FIG. 10. An inner surface of the
extruded blank formed from the blank 1 is integrally extruded along
the central hole 12 of the blank 1 using a finishing extrusion
shaft 10 so that the inner cavity of the extruded blank formed from
the blank 1 has a flat surface and the extruded blank has an even
wall thickness. After raised and rotated properly, the finishing
extrusion shaft 10 performs extruding again to eliminate the
influence of the eccentricity of the finishing extrusion shaft 10
and enhance the finishing precision.
[0085] It should be noted that, the above zoning extruding step and
the finishing step may be alternately performed until the height,
the thickness and the end face flatness of the extruded blank
formed from the blank 1 reach desired predetermined values.
[0086] According to an embodiment of the present disclosure, when
the blank 1 is subjected to zoning extruding, a downward extrusion
speed at which the blank 1 is extruded by the stamp-extruding head
portion 93 along the central hole 12 of the blank 1 is associated
with the kind of the material of the blank 1. For example, the
downward extrusion speed of the stamp-extruding head portion 93 may
be controlled to be within a range of about 5 mm/s to about 90 mm/s
when the blank is made of a ferrous metal such as a
high-temperature metal or an alloy steel. For another example, the
downward extrusion speed of the stamp-extruding head portion 93 may
be controlled to be within a range of about 20 mm/s to about 300
mm/s when the blank is made of a nonferrous metal such as aluminum
or copper.
[0087] According to an embodiment of the present disclosure, when
the stamp-extruding head portion 93 is not contacted with the
metal, both a rising speed and a falling speed of the
stamp-extruding head portion 93 may be within a range of about 90
mm/s to about 300 mm/s.
[0088] When the blank 1 is subjected to zoning extruding, the
circumferential rotating angle .alpha. is within a range of about
10 degrees to about 120 degrees.
[0089] According to an embodiment of the present disclosure, in the
zoning extruding step, a pressing displacement is within a range of
about 2 mm to about 2000 mm.
[0090] A pressing speed of the finishing extrusion shaft 10 and a
rising speed and a falling speed of the finishing extrusion shaft
10 when the finishing extrusion shaft 10 is not contacted with the
metal in the finishing step may be the same as a pressing speed of
the stamp-extruding head portion 93 and the rising speed and the
falling speed of the stamp-extruding head portion 93 when the
stamp-extruding head portion 93 is not contacted with the metal in
the zoning extruding step respectively, but a pressing displacement
every time in the finishing step is 0.01 times to 0.5 times as
large as that in the zoning extruding step.
[0091] According to an embodiment of the present disclosure, after
the hot piercing step, a hot pierce reaming step may be further
performed. That is, the deepened central hole 12 of the blank 1 is
reamed by extruding the blank 1 downwards along the central hole 12
in the upper surface 13 of the blank 1 using a second pecker 8
having a radial diameter greater than that of the first pecker 7,
thus facilitating the subsequent deforming of the blank 1, as shown
in FIG. 15. It should be noted that, both the above hot piercing
step and the above hot piercing reaming step may be performed in
the closed female cavity 6.
[0092] The zoning closed-die extruding method according to an
embodiment of the present disclosure may also be used for forming a
high-pressure or ultrahigh-pressure vessel with a high reliability
and a large volume such as a nuclear evaporator, a hydrogenation
reactor or a large-volume natural gas high-pressure vessel, for
example, a water chamber head of a nuclear evaporator.
[0093] In all, in the zoning closed-die extruding device and the
zoning closed-die extruding method according to an embodiment of
the present disclosure, because a huge pressing force of about 1200
MN to about 1500 MN is provided and the constraint force is largely
improved and a superior constraint (heavy extruding and closed
upsetting/piercing) condition is provided when the metal is
deformed, a large and even spherical tensor of stress .sigma..sub.m
(generally reaching about 300 MPa to 400 MPa) may be provided, thus
ensuring the optimum condition for closing/soldering microscopic
defects and cracks on the blank 1 and creating a superior
thermo-mechanical coupling condition. In addition, by using the
zoning closed-die extruding device and the zoning closed-die
extruding method according to an embodiment of the present
disclosure, the manufacturing efficiency may be tremendously
enhanced, the rejection rate may be reduced, and the utilization
rate of the material may be improved accordingly.
[0094] Reference throughout this specification to "an embodiment",
"some embodiments", "one embodiment", "an example", "a specific
examples", or "some examples" means that a particular feature,
structure, material, or characteristic described in connection with
the embodiment or example is included in at least one embodiment or
example of the disclosure. Thus, the appearances of the phrases
such as "in some embodiments", "According to an embodiment of the
present disclosure", "in an embodiment", "an example", "a specific
examples", or "some examples" in various places throughout this
specification are not necessarily referring to the same embodiment
or example of the disclosure. Furthermore, the particular features,
structures, materials, or characteristics may be combined in any
suitable manner in one or more embodiments or examples.
[0095] Although explanatory embodiments have been shown and
described, it would be appreciated by those skilled in the art that
changes, alternatives, and modifications may be made in the
embodiments without departing from spirit and principles of the
disclosure. Such changes, alternatives, and modifications all fall
into the scope of the claims and their equivalents.
* * * * *