U.S. patent application number 17/401327 was filed with the patent office on 2022-08-04 for method for sealing high-temperature heat pipe.
This patent application is currently assigned to SOUTH CHINA UNIVERSITY OF TECHNOLOGY. The applicant listed for this patent is SOUTH CHINA UNIVERSITY OF TECHNOLOGY. Invention is credited to Zicong HE, Longsheng LU, Yong TANG, Zhenping WAN, Jinhu ZOU.
Application Number | 20220241909 17/401327 |
Document ID | / |
Family ID | 1000006474680 |
Filed Date | 2022-08-04 |
United States Patent
Application |
20220241909 |
Kind Code |
A1 |
WAN; Zhenping ; et
al. |
August 4, 2022 |
METHOD FOR SEALING HIGH-TEMPERATURE HEAT PIPE
Abstract
A method for sealing a high-temperature heat pipe includes: (1)
necking and reducing two ends of the heat pipe separately, so as to
obtain a necked end and a reduced end; (2) sealing the necked end
by laser welding or electron beam welding; (3) placing the heat
pipe in an inert gas glove box, and pouring a working medium
without impurities into the heat pipe; (4) heating the heat pipe,
connecting the reduced end to a vacuum pump, pumping gas inside the
heat pipe by the vacuum pump to vacuumize the heat pipe, such that
pressure in an inner cavity of the heat pipe reaches a target
pressure, and flattening the reduced end; and (5) sealing an
opening of the flattened reduced end by electron beam welding or
laser welding, so as to obtain the high-temperature heat pipe.
Inventors: |
WAN; Zhenping; (Guangzhou,
CN) ; HE; Zicong; (Guangzhou, CN) ; ZOU;
Jinhu; (Guangzhou, CN) ; LU; Longsheng;
(Guangzhou, CN) ; TANG; Yong; (Guangzhou,
CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SOUTH CHINA UNIVERSITY OF TECHNOLOGY |
Guangzhou |
|
CN |
|
|
Assignee: |
SOUTH CHINA UNIVERSITY OF
TECHNOLOGY
Guangzhou
CN
|
Family ID: |
1000006474680 |
Appl. No.: |
17/401327 |
Filed: |
August 13, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B23P 15/26 20130101;
B23P 2700/09 20130101 |
International
Class: |
B23P 15/26 20060101
B23P015/26 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 8, 2020 |
CN |
202010510277.4 |
Claims
1. A method for sealing a high-temperature heat pipe, comprising:
(1) necking and reducing two ends of the heat pipe separately, so
as to obtain a necked end and a reduced end; (2) sealing the necked
end by laser welding or electron beam welding; (3) placing the heat
pipe in an inert gas glove box, and pouring a working medium into
the heat pipe; (4) heating the heat pipe, connecting the reduced
end to a vacuum pump, pumping gas inside the heat pipe by the
vacuum pump to vacuumize the heat pipe, such that pressure in an
inner cavity of the heat pipe reaches a target pressure, and
flattening the reduced end; and (5) sealing an opening of the
flattened reduced end by electron beam welding or laser welding, so
as to obtain the high-temperature heat pipe.
2. The method according to claim 1, wherein step (1) of reducing
one end of the heat pipe comprises: (1-1-1) fixing the heat pipe to
a fixture of a lathe, and mounting a spinning reducing die in the
lathe; and (1-1-2) driving the spinning reducing die to rotate, and
simultaneously driving the heat pipe to move toward the spinning
reducing die axially so as to insert the heat pipe into the
spinning reducing die, so as to reduce one end of the heat
pipe.
3. The method according to claim 2, wherein the spinning reducing
die comprises a retainer and a plurality of steel balls, wherein
the plurality of steel balls are fixed in the retainer, so as to
form a reducing hole.
4. The method according to claim 1, wherein step (1) of necking the
other end of the heat pipe comprises: (1-2-1) fixing the heat pipe
to a fixture of a lathe, and mounting a spinning necking die in a
lathe chuck; and (1-2-2) driving the spinning necking die to
rotate, and simultaneously driving the heat pipe to move toward the
spinning necking die axially so as to insert the heat pipe into the
spinning necking die, so as to neck the other end of the heat
pipe.
5. The method according to claim 4, wherein the spinning necking
die in step (1) comprises an upper pressing die and a lower
pressing die, wherein a first groove is provided in one side of the
upper pressing die, a second groove is provided in one side of the
lower pressing die, the upper pressing die and the lower pressing
die are spliced, and the first groove and the second groove are
spliced to form a necking groove.
6. The method according to claim 1, wherein in step (4), after
vacuumizing, the pressure of the inner cavity of the heat pipe is
lower than 1.times.10.sup.-3 Pa.
7. The method according to claim 1, wherein in step (1), after
reducing, an outer diameter of the heat pipe is 6-8 mm.
8. The method according to claim 1, further comprising: cleaning to
remove surface oxide skin and lubricating oil of the heat pipe
subjected to necking and reducing between step (1) and step
(2).
9. The method according to claim 1, wherein in step (3), a water
content and an oxygen content of the inert gas glove box are both
lower than 0.5 ppm.
10. The method according to claim 1, wherein after step (5), the
method further comprises: placing the high-temperature heat pipe in
a pressure maintaining container with high-pressure helium for at
least 2 hours, then vacuumizing the pressure maintaining container,
and checking a quantity of the helium left in the pressure
maintaining container, wherein when partial pressure of the helium
in the pressure maintaining container is less than 1.times.10-3 Pa,
the high-temperature heat pipe is qualified.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of International Patent
Application No. PCT/CN2020/119392 with a filing date of Sep. 30,
2020, designating the United States, now pending, and further
claims priority to Chinese Patent Application No. 202010510277.4
with a filing date of Jun. 8, 2020. The content of the
aforementioned applications, including any intervening amendments
thereto, are incorporated herein by reference.
TECHNICAL FIELD
[0002] The present disclosure belongs to the technical field of
high-temperature thermal structures, and particularly relates to a
method for sealing a high-temperature heat pipe.
BACKGROUND
[0003] Heat pipes can be divided into the low-temperature heat
pipes (operating at -270.degree. C. to 0.degree. C.), the
normal-temperature heat pipes (operating at 200.degree. C. to
600.degree. C.) and the high-temperature heat pipes (operating at
600.degree. C. or above) according to their use temperatures. Since
the high-temperature heat pipes operate at extremely high
temperatures, a passive heat transfer mode is applied extensively
in the fields of aerospace, nuclear electric power generation and
military industry. With liquid metal or molten salt as a working
medium, the high-temperature heat pipes have good thermal stability
and low saturated vapor pressure at high temperatures. The
high-temperature heat pipes are made of stainless steel,
high-temperature alloys or refractory metal.
[0004] When the high-temperature heat pipes made of refractory
alloys are sealed, tube bodies and end caps are combined, and
valves need to be added at the end caps for subsequent pouring and
vacuum degassing, which is complicated. Part of the refractory
metal has high hardness and high brittleness, and thus is difficult
to machine. In addition, it is difficult and costly to manufacture
valves with end caps, thereby limiting the manufacturing efficiency
of the high-temperature heat pipes.
SUMMARY
[0005] The technical problem to be solved by the present disclosure
is to overcome the defect of a complicated process for
manufacturing a high-temperature heat pipe in the prior art. The
present disclosure provides a method for sealing a high-temperature
heat pipe, which may reduce cost and improve manufacturing
efficiency.
[0006] In order to solve the above technical problem, the present
disclosure employs the technical solution: the method for sealing a
high-temperature heat pipe includes:
[0007] (1) necking and reducing two ends of the heat pipe
separately, so as to obtain a necked end and a reduced end;
[0008] (2) sealing the necked end by laser welding or electron beam
welding;
[0009] (3) placing the heat pipe in an inert gas glove box, and
pouring a working medium without impurities into the heat pipe;
[0010] (4) heating the heat pipe, connecting the reduced end to a
vacuum pump, pumping gas inside the heat pipe by the vacuum pump to
vacuumize the heat pipe, such that pressure in an inner cavity of
the heat pipe reaches a target pressure, and flattening the reduced
end; and
[0011] (5) sealing an opening of the flattened reduced end by
electron beam welding or laser welding, so as to obtain the
high-temperature heat pipe.
[0012] Preferably, step (1) of reducing one end of the heat pipe
includes:
[0013] (1-1-1) fixing the heat pipe to a fixture of a lathe, and
mounting a spinning reducing die in the lathe; and
[0014] (1-1-2) driving the spinning reducing die to rotate, and
simultaneously driving the heat pipe to move toward the die axially
so as to insert the heat pipe into the spinning reducing die, so as
to reduce one end of the heat pipe.
[0015] Preferably, the spinning reducing die includes a retainer
and a plurality of steel balls, where the steel balls are fixed in
the retainer, so as to form a reducing hole.
[0016] Preferably, step (1) of necking the other end of the heat
pipe includes:
[0017] (1-2-1) fixing the heat pipe to a fixture of a lathe, and
mounting a spinning necking die in a lathe chuck; and
[0018] (1-2-2) driving the spinning necking die to rotate, and
simultaneously driving the heat pipe to move toward the die axially
so as to insert the heat pipe into the spinning necking die, so as
to neck the other end of the heat pipe.
[0019] Preferably, the spinning necking die in step (1) includes an
upper pressing die and a lower pressing die, where a first groove
is provided in one side of the upper pressing die, a second groove
is provided in one side of the lower pressing die, the upper
pressing die and the lower pressing die are spliced, and the first
groove and the second groove are spliced to form a necking
groove.
[0020] Preferably, in step (4), after vacuumizing, the pressure of
the inner cavity of the heat pipe is lower than 1.times.10.sup.-3
Pa.
[0021] Preferably, in step (1), after reducing, an outer diameter
of the heat pipe is 6-8 mm.
[0022] Preferably, the method further includes: cleaning to remove
surface oxide skin and lubricating oil of the heat pipe subjected
to necking and reducing between step (1) and step (2).
[0023] Preferably, in step (3), a water content and an oxygen
content of the inert gas glove box are both lower than 0.5 ppm.
[0024] Preferably, after step (5), the method further includes:
placing the high-temperature heat pipe in a pressure maintaining
container with high-pressure helium for at least 2 hours, then
vacuumizing the pressure maintaining container, and checking the
quantity of the helium left in the pressure maintaining container,
where when partial pressure of the helium in the pressure
maintaining container is less than 1.times.10.sup.-3 Pa, the
high-temperature heat pipe is qualified.
[0025] The present invention has the beneficial effects:
[0026] 1. by necking and reducing the two ends of the heat pipe
separately, and sealing the necked end of the heat pipe by laser
welding or electron beam welding, the working procedures for
manufacturing the high-temperature heat pipe are simplified and the
cost is reduced; and
[0027] 2. by flattening the reduced end of the vacuumized heat
pipe, the opening is rapidly and temporarily sealed; and by sealing
the opening of the flattened reduced end by electron beam welding
or laser welding, non-condensable gas in the high-temperature heat
pipe is effectively reduced, and the working medium is prevented
from being oxidized, so as to obtain the high-temperature heat pipe
with good gas tightness.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 is a schematic diagram of a heat pipe of the present
disclosure.
[0029] FIG. 2 is a schematic diagram of a spinning reducing die of
the present disclosure.
[0030] FIG. 3 is a schematic diagram of a spinning reducing
operation in the present disclosure, and an arrow in the figure
represents a feed direction.
[0031] FIG. 4 is a schematic diagram of a spinning necking die of
the present disclosure.
[0032] FIG. 5 is a schematic diagram of a spinning necking
operation in the present disclosure, and an arrow in the figure
represents a feed direction.
[0033] FIG. 6 is a schematic diagram of a working medium pouring
and sealing process of the heat pipe in the present disclosure.
[0034] FIG. 7 is a schematic diagram of sealing the heat pipe by
electron beam welding or laser welding in the present
disclosure.
[0035] Numerals of various components in the figures: 1. heat pipe,
2. inert gas glove box, 3. electric hydraulic clamp, 4. working
medium, 5. tubular heating furnace, 6. electron beam welding or
laser welding; 7. spinning reducing die, 7-1 retainer, 7-2 steel
ball, 7-3 reducing hole; 8. spinning necking die, 8-1 upper
pressing die, 8-2 lower pressing die, 8-3 necking groove, 8-3-1
first groove, 8-3-2 second groove.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0036] The objects of the present disclosure will be further
described in detail below with reference to the accompanying
drawings and specific embodiments, not all of the embodiments can
be described in detail herein, but the implementations of the
present disclosure are not therefore limited to the following
embodiments.
Embodiment 1
[0037] As shown in FIGS. 1-7, a method for sealing a
high-temperature heat pipe, provided in the present disclosure,
includes:
[0038] (1) neck and reduce two ends of the heat pipe 1, so as to
obtain a necked end and a reduced end, such that subsequent
flattening sealing and welding sealing are facilitated; clean to
remove surface oxide skin and lubricating oil of the heat pipe 1
subjected to necking and reducing such that non-condensable gas of
the high-temperature heat pipe may be effectively reduced, and the
surface oxide skin and the lubricating oil may be prevented from
affecting strength of subsequent flattening and welding.
[0039] (2) seal the necked end by laser welding or electron beam
welding 6;
[0040] (3) keep a water content and an oxygen content in an inert
gas glove box 2 lower than 0.5 ppm, then place the heat pipe 1 in
the inert gas glove box 2 to prevent a working medium 4 from being
oxidized in a pouring process, and pour the working medium 4
without impurities into the heat pipe 1;
[0041] (4) heat the heat pipe 1 by a tubular heating furnace 5;
connect the reduced end to a vacuum pump; pump gas inside the heat
pipe 1 by the vacuum pump to vacuumize the heat pipe, such that
pressure of an inner cavity of the heat pipe 1 is lower than
1.times.10.sup.-3 Pa; then flatten the reduced end by an electric
hydraulic clamp 3, where a tonnage of the electric hydraulic clamp
3 is larger than 12 T, and a radius of a cutting edge of a
flattening grinding tool is smaller than 10 mm; and enable a
heating temperature to be higher than a melting point of the
working medium 4, and carry out melting at a high temperature to
quickly discharge impurity gas in the working medium;
[0042] (5) seal an opening of the flattened reduced end by electron
beam welding or laser welding 6, so as to obtain the
high-temperature heat pipe;
[0043] (6) place the high-temperature heat pipe in a pressure
maintaining container with high-pressure helium for at least 2
hours, where pressure of the high-pressure helium in this
embodiment is 0.3-0.4 MPa; then vacuumize the pressure maintaining
container; and check the quantity of the helium left in the
pressure maintaining container, where when partial pressure of the
helium in the pressure maintaining container is less than
1.times.10.sup.-3 Pa, the high-temperature heat pipe is
qualified.
[0044] In step (1), after reducing, an outer diameter of the heat
pipe 1 is 6 mm.
[0045] In step (3), inert gas used in the inert gas glove box is
argon.
[0046] In step (4), the heating temperature is 250.degree. C., and
a length of a heated section of the heat pipe 1 is 100 mm.
[0047] The heat pipe 1 is made of a nickel-base high-temperature
alloy, and the working medium 4 sealed in the pipe is alkali metal.
A groove type capillary structure is designed on an inner wall of
the heat pipe 1. The capillary structure may reduce backflow
resistance of the liquid metal working medium 4 and increase
anti-gravity performance when the high-temperature heat pipe works.
The groove type capillary structure is manufactured by spinning,
has high machining efficiency, and is capable of effectively
reducing the backflow resistance of the liquid metal working medium
4.
[0048] As shown in FIG. 3, step (1) of reducing one end of the heat
pipe 1 includes:
[0049] (1-1-1) fix the heat pipe 1 to a fixture of a lathe, and
mount a spinning reducing die 7 in the lathe; and
[0050] (1 1 2) drive the spinning reducing die 7 to rotate, and
simultaneously drive the heat pipe 1 to move toward the die axially
so as to insert the heat pipe 1 into the spinning reducing die 7,
where a diameter of one end of the heat pipe 1 becomes smaller
along with reduction of a diameter of a reducing hole 7-3 of the
spinning reducing die 7, and after the diameter of one end of the
heat pipe is 6 cm, the diameter of the reducing hole 7-3 of the
spinning reducing die 7 is kept unchanged until the reduced end of
the heat pipe is obtained.
[0051] As shown in FIG. 2, the spinning reducing die 7 in step (1)
includes a retainer 7-1 and a plurality of steel balls 7-2, where
the plurality of steel balls 7-2 are fixed in the retainer 7-1, so
as to form the reducing hole 7-3.
[0052] As shown in FIG. 5, in step (1) of necking the other end of
the heat pipe 1 includes:
[0053] (1-2-1) fix the heat pipe 1 to a fixture of a lathe, and
mount a spinning necking die 8 in a lathe chuck; and
[0054] (1-2-2) drive the spinning necking die 8 to rotate, and
simultaneously drive the heat pipe 1 to move toward the die axially
so as to insert the heat pipe 1 into a necking groove of the
spinning necking die 8, where a wall at the other end of the heat
pipe is deformed along with rotation of the necking groove until
the other end of the heat pipe is sealed by necking.
[0055] As shown in FIG. 4, the spinning necking die 8 in step (1)
includes an upper pressing die 8-1 and a lower pressing die 8-2,
where a first groove 8-3-1 is provided in one side of the upper
pressing die 8-1, a second groove 8-3-2 is provided in one side of
the lower pressing die 8-2, the upper pressing die 8-1 and the
lower pressing die 8-2 are spliced, and the first groove 8-3-1 and
the second groove 8-3-2 are spliced to form the necking groove
8-3.
Embodiment 2
[0056] In this embodiment, the following technical features are
different from those of Embodiment 1, and the other technical
features are the same.
[0057] In step (1), after reducing, an outer diameter of a heat
pipe 1 is 7 mm.
[0058] In step (3), inert gas used in an inert gas glove box is
helium.
[0059] In step (4), a heating temperature is 275.degree. C., and a
length of a heated section of the heat pipe 1 is 200 mm.
[0060] The heat pipe 1 is made of a molybdenum alloy, and a working
medium 4 sealed in the pipe is molten salt. A wire mesh type
capillary structure is designed on an inner wall of the heat pipe
1. The wire mesh type capillary structure is easy to manufacture
and has certain anti-gravity performance.
Embodiment 3
[0061] In this embodiment, the following technical features are
different from those of Embodiment 1, and the other technical
features are the same.
[0062] In step (1), after reducing, an outer diameter of a heat
pipe 1 is 8 mm.
[0063] In step (4), a heating temperature is 300.degree. C., and a
length of a heated section of the heat pipe 1 is 300 mm.
[0064] The heat pipe 1 is made of a niobium alloy. A powder
sintered capillary structure is designed on an inner wall of the
heat pipe 1. The powder sintered capillary structure has high
anti-gravity performance.
[0065] The above specific implementations are preferred embodiments
of the present disclosure and may not be construed as limiting the
present disclosure, and any other changes or equivalent
substitutions without departing from the technical solution of the
present disclosure are included in the protection scope of the
present disclosure.
* * * * *