U.S. patent application number 16/822057 was filed with the patent office on 2020-09-24 for method for piercing titanium alloy solid billet.
The applicant listed for this patent is Northwestern Polytechnical University. Invention is credited to Dong LIU, Jianguo WANG, Yanhui YANG.
Application Number | 20200298297 16/822057 |
Document ID | / |
Family ID | 1000004746117 |
Filed Date | 2020-09-24 |
United States Patent
Application |
20200298297 |
Kind Code |
A1 |
YANG; Yanhui ; et
al. |
September 24, 2020 |
METHOD FOR PIERCING TITANIUM ALLOY SOLID BILLET
Abstract
A method for piercing a titanium alloy solid billet, the method
including: 1) providing a Mannesmann rotary piercer including two
rollers, a feed channel, a plurality of centering devices, and a
mandril including a plug; fixing the mandril using the plurality of
centering devices, where the Mannesmann rotary piercer has a
feeding angle of 6-18.degree., a cross angle of 15.degree., and a
roll speed of 30-90 rpm; 2) heating a titanium alloy solid billet
to 930-990.degree. C.; 3) transferring the titanium alloy solid
billet to the feed channel of the Mannesmann rotary piercer; and 4)
aligning the titanium alloy solid billet with the plug of the
mandril, and driving the titanium alloy solid billet to pass
through the plug of the mandril, thereby piercing the titanium
alloy solid billet and yielding a titanium alloy tube.
Inventors: |
YANG; Yanhui; (Xi'an,
CN) ; LIU; Dong; (Xi'an, CN) ; WANG;
Jianguo; (Xi'an, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Northwestern Polytechnical University |
Xi'an |
|
CN |
|
|
Family ID: |
1000004746117 |
Appl. No.: |
16/822057 |
Filed: |
March 18, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B21C 23/085 20130101;
B21C 23/002 20130101 |
International
Class: |
B21C 23/08 20060101
B21C023/08; B21C 23/00 20060101 B21C023/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 18, 2019 |
CN |
201910201337.1 |
Claims
1. A method, comprising: 1) providing a Mannesmann rotary piercer
comprising two rollers, two guide plates, a feed channel, a
plurality of centering devices, and a mandril comprising a plug;
fixing the mandril using the plurality of centering devices;
wherein the Mannesmann rotary piercer has a feeding angle of
6-18.degree., a cross angle of 15.degree., and a roll speed of
30-90 rpm, and a plug advance of 5-15 mm; the feeding angle refers
to a projection of an included angle between an axis of one of the
two rollers and an axis of a billet along a connection line of
rotation centers of the two rollers, and the cross angle refers to
a projection of an included angle between the axis of one of the
two rollers and the axis of the billet on a plane formed by a
connection line of the rotation centers of the two rollers and the
axis of the billet; the plug advance refers to a distance between a
front end of the plug and a roll gorge along the axis of the
billet, the roll gorge refers to the position of a minimum distance
between the two rollers; a diameter reduction ratio of the billet
is set as 6-12%; 2) heating a titanium alloy solid billet to
930-990.degree. C.; 3) transferring the titanium alloy solid billet
to the feed channel of the Mannesmann rotary piercer; and 4)
aligning the titanium alloy solid billet with the plug of the
mandril, and driving the titanium alloy solid billet to pass
through the plug of the mandril, thereby piercing the titanium
alloy solid billet and yielding a titanium alloy tube.
2. The method of claim 1, wherein the mandril comprises a free end
and a fixed end, and the plug is disposed on the free end; the
centering device is installed in batches; a distance between a
first one of the plurality of centering devices and the fixed end
is (2/3).sup.nl, where n refers to batch of installation of the
centering devices, and l refers to a length of the mandril; the
plurality of centering devices is 2.sup.n-1 in number, and the
centering devices are exponentially added in each installation; a
distance between a second one of the plurality of centering devices
and the free end is 1/3.times.( ).sup.n-1l; when n is greater than
2, suppose a distance between two adjacent centering devices is a,
additional centering devices are disposed between the two adjacent
centering devices, and a distance between the additional centering
devices and one of the two adjacent centering devices close to the
free end is a.
3. The method of claim 1, wherein a heating time of the titanium
alloy solid billet is D.times.(1.2 to 2) min, where D is a diameter
of the titanium alloy solid billet with a unit of millimeter.
4. The method of claim 1, wherein the two rollers each are a
conical roll with double helix.
5. The method of claim 1, wherein the Mannesmann rotary piercer
comprises three cams for each centering device; an included angle
of each two of the three cams is 120.degree., and the mandril is
disposed in a hole enclosed by the three cams for each centering
device.
6. The method of claim 1, wherein the Mannesmann rotary piercer
comprises two guide plates disposed between the two rollers, and
the distance between the two guide plates is 1.05-1.1 times that of
the two rollers in a cross section perpendicular to the axis of the
billet, and a minimum distance between the two rollers is
D-(1-diameter reduction ratio), where D is the diameter of the
titanium alloy solid billet with a unit of millimeter.
7. The method of claim 1, further comprising cooling the titanium
alloy tube in air.
8. The method of claim 1, further comprising machining a head and a
tail of the titanium alloy tube.
9. The method of claim 1, wherein in 4), the titanium alloy solid
billet is pierced in the Mannesmann rotary piercer at a temperature
between 860 and 1000.degree. C.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Pursuant to 35 U.S.C. .sctn. 119 and the Paris Convention
Treaty, this application claims foreign priority to Chinese Patent
Application No. 201910201337.1 filed Mar. 18, 2019, the contents of
which, including any intervening amendments thereto, are
incorporated herein by reference. Inquiries from the public to
applicants or assignees concerning this document or the related
applications should be directed to: Matthias Scholl P.C., Attn.:
Dr. Matthias Scholl Esq., 245. First Street, 18th Floor, Cambridge,
Mass. 02142.
BACKGROUND
[0002] The disclosure relates to a method for piercing a titanium
alloy solid billet.
[0003] Compared with steel, titanium alloy has large elastic
modulus and high deformation resistance. Thus, in the process of
two-roll rotary piercing, the titanium alloy billet is too hard and
tends to be stuck in the rotary piercer, and the mandril for
piercing the billet tends to lose the working position. The
microstructure of titanium alloy is greatly affected by the
deformation process parameters, so it is important to set the
process parameters reasonably to obtain ideal microstructure.
SUMMARY
[0004] The disclosure provides a method for piercing a titanium
alloy solid billet, the method comprising:
[0005] 1) providing a Mannesmann rotary piercer comprising two
rollers, two guide plates, a feed channel, a plurality of centering
devices, and a mandril comprising a plug; fixing the mandril using
the plurality of centering devices; wherein the Mannesmann rotary
piercer has a feeding angle of 6-18.degree., a cross angle of
15.degree., a roll speed of 30-90 rpm, and a plug advance of 5-15
mm; the feeding angle refers to a projection of an included angle
between an axis of one of the two rollers and an axis of a billet
along a connection line of rotation centers of the two rollers, and
the cross angle refers to a projection of an included angle between
the axis of one of the two rollers and the axis of the billet on a
plane formed by a connection line of the rotation centers of the
two rollers and the axis of the billet; the plug advance refers to
the distance between the front end of plug and the roll gorge along
the axis of the billet; the roll gorge refers to the position of
minimum distance between the two rollers; a diameter reduction
ratio of the billet is set as 6-12%;
[0006] 2) heating a titanium alloy solid billet to 930-990.degree.
C.;
[0007] 3) transferring the titanium alloy solid billet to the feed
channel of the Mannesmann rotary piercer; and
[0008] 4) aligning the titanium alloy solid billet with the plug of
the mandril, and driving the titanium alloy solid billet to pass
through the plug of the mandril, thereby piercing the titanium
alloy solid billet and yielding a titanium alloy tube.
[0009] The mandril comprises a free end and a fixed end, and the
plug is disposed on the free end; the centering device is installed
in batches; a distance between a first one of plurality of
centering devices and the fixed end is (2/3).sup.nl, where n refers
to batch of installation of the centering devices, and l refers to
a length of the mandril; the plurality of centering devices is
2.sup.n-1 in number, and the centering devices are exponentially
added in each installation; a distance between a second one of the
plurality of centering devices the free end is 1/3.times.(
).sup.n-1l; when n is greater than 2, suppose a distance between
two adjacent centering devices is a, additional centering devices
are disposed between the two adjacent centering devices, and a
distance between the additional centering devices and one of the
two adjacent centering devices close to the free end is a. The
strength of the centering devices is checked. When the strength of
the mandril is not satisfied, the time (n+1) of installation of the
centering devices is provided until all the strength of the
centering devices is satisfied.
[0010] The heating time of the titanium alloy solid billet is
D.times.(1.2 to 2) min, where D is the diameter of the titanium
alloy solid billet with a unit of millimeter.
[0011] The two rollers each comprises a conical roll with double
helix.
[0012] The Mannesmann rotary piercer comprises three cams for each
centering device; an included angle of each two of the three cams
is 120.degree., and the mandril is disposed in a hole enclosed by
the three cams for each centering device.
[0013] The Mannesmann rotary piercer comprises two guide plates
disposed between the two rollers, and the distance (Ddx) between
the two guide plates is 1.05-1.1 times the distance (Dgx) of the
two rollers in a cross section perpendicular to the axis of the
billet, and a minimum distance between the two rollers is
D.times.(1-diameter reduction ratio), where D is the diameter of
the titanium alloy solid billet with a unit of millimeter.
[0014] The method further comprises cooling the titanium alloy tube
in air.
[0015] The titanium alloy solid billet is prepared by melting in
vacuum consumable electric arc furnace, forging and machining.
[0016] The method further comprises machining the head and tail of
the titanium alloy tube.
[0017] In 4), the titanium alloy solid billet is pierced in the
Mannesmann rotary piercer at the temperature between 860 and
1000.degree. C.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a flow chart of a method for piercing a titanium
alloy solid billet according to one embodiment of the
disclosure;
[0019] FIG. 2 is a schematic diagram of a Mannesmann rotary piercer
in one angle of view showing the feeding angle of two rollers
according to one embodiment of the disclosure;
[0020] FIG. 3 is a schematic diagram of a Mannesmann rotary piercer
in another angle of view showing the cross angle of two rollers
according to one embodiment of the disclosure; and
[0021] FIG. 4 is a sectional view taken from line A-A in FIG.
2.
DETAILED DESCRIPTION
[0022] To further illustrate, embodiments detailing a method for
piercing a titanium alloy solid billet are described below. It
should be noted that the following embodiments are intended to
describe and not to limit the disclosure.
[0023] As shown in FIG. 1, provided is a flow chart of a method for
piercing a titanium alloy solid billet. The method is detailed as
follows:
[0024] 1) Providing a Mannesmann rotary piercer comprising two
rollers 201, two guide plates 204, a feed channel, a plurality of
centering devices, and a mandril 202 comprising a plug 203; fixing
the mandril using the plurality of centering devices. Specifically,
three centering devices are provided, that is, one primary
centering device and two secondary centering devices. The mandril
comprises a free end and a fixed end. The distance between the one
primary centering device and the fixed end is approximately 513 mm.
The distances between the two secondary centering devices and the
fixed end and the free end are approximately 342 mm and 103 mm,
respectively. The uneven distribution of the centering devices
improves the stability of the mandril, and reduces the occurrence
of the rolling block phenomenon (the alloy billet is stuck in the
middle of the rotary piercer). The distance Ddx between the two
guide plates is 1.05-1.1 times the distance Dgx of the two rollers
in a cross section perpendicular to the axis of the billet, and a
minimum distance between the two rollers is D.times.(1-diameter
reduction ratio), where D is the diameter of the titanium alloy
solid billet with a unit of millimeter.
[0025] 2) As shown in FIGS. 2, 3 and 4, the Mannesmann rotary
piercer has a feeding angle of 6-18.degree., a cross angle of
15.degree., a diameter reduction ratio of 6-12%, a roll speed of
30-90 rpm, and a plug advance of 5-15 mm. Specifically, the
Mannesmann rotary piercer has a feeding angle .alpha. of
15.degree., a cross angle .beta. of 15.degree., a diameter
reduction ratio of 8%, and a roll speed of 60 rpm. The feeding
angle refers to the projection of an included angle between the
axis of one of the two rollers and the axis of the titanium alloy
solid billet along the connection line of rotation centers of the
two rollers, and the cross angle refers to the projection of an
included angle between the axis of one of the two rollers and the
axis of the titanium alloy solid billet on the plane formed by a
connection line of rotation centers of the two rollers and the axis
of the titanium alloy solid billet. The plug advance refers to the
distance between the plug nose and the roll gorge along the axis of
the billet; the plug nose refers to the front end of plug; the roll
gorge refers to the position of minimum distance between the two
rollers.
[0026] 3) Heating a titanium alloy solid billet to 930-990.degree.
C.
[0027] In this disclosure, the titanium alloy solid billet is
prepared by melting in vacuum consumable electric arc furnace,
forging and machining. Specifically, three titanium alloy solid
billets TC4 are provided, with dimension of .PHI.45.times.200 mm,
.PHI.45.times.280 mm, and .PHI.45.times.420 mm, respectively. The
microstructure of each part of the billets is even, and no defects
such as inclusions and pores are found. The phase transformation
temperature of the titanium alloy cylindrical billets is
1000.degree. C..+-.5.degree. C.; the initial microstructure of each
part of the cylindrical billets is bimodal microstructure with 44%
primary a phase, and the average grain size of primary a phase is
20 .mu.m.
[0028] The three titanium alloy cylindrical billets are heated in a
heating furnace. The heating temperature is 960.degree.
C..+-.10.degree. C. and the heating time is 60 min. The shape of
two rollers are all conical roll with double helix; The Mannesmann
rotary piercer comprises three cams for each centering device; the
included angle of each two of the three cams is 120.degree., and
the mandril is placed in the holes enclosed by three cams for each
centering device.
[0029] 4) Transferring the titanium alloy solid billet to the feed
channel of the Mannesmann rotary piercer. The transit time is less
than or equal to 5 seconds.
[0030] 5) Aligning the titanium alloy solid billet with the plug of
the mandril, and driving the titanium alloy solid billet to pass
through the plug of the mandril, thereby piercing the titanium
alloy solid billet and yielding a titanium alloy tube.
[0031] The rolling temperature of the titanium alloy solid billet
is 860-1000.degree. C.
[0032] Following 5), the titanium alloy tube is cooled in air, and
the head and tail of the titanium alloy tube are machined.
[0033] After the piercing, the dimensions of the head and tail of
the three titanium alloy tubes are shown in Table 1.
TABLE-US-00001 TABLE 1 Dimensions of three titanium alloy tubes
Head of Tail of titanium alloy tubes titanium alloy tubes Outer
Inner Wall Outer Inner Wall diameter diameter thickness diameter
diameter thickness Items (mm) (mm) (mm) (mm) (mm) (mm) .PHI.45
.times. 200 mm 47.10 19.90 13.20 46.90 19.80 13.55 .PHI.45 .times.
280 mm 47.20 20.10 13.40 47.00 20.00 13.50 .PHI.45 .times. 420 mm
47.00 19.80 12.70 46.80 19.80 13.8 Variance -- 0.09 0.01 0.05 0.02
0.03
[0034] As shown in Table 1, the variances between the inner
diameter and the wall thickness of the three tubes with different
lengths is less than 0.1, which indicates that the piercing method
of the disclosure is accurate and stable, and the tubes with a
diameter thickness ratio of about 3.5 are obtained.
[0035] The microstructure of different parts of the billet with a
length of 230 mm is studied. The samples are selected from the
head, middle part and tail of the tube for metallographic analysis.
Each sample is provided with three observation points which are
recorded as a, b and c along the radial direction and the
microstructure of the head, middle part and tail of the tube are
observed through the three observation points. The radial and axial
microstructure of the tube with bimodal microstructure is even
across the section. According to statistics, the primary a phase of
each part is about 30%, and the length-width ratio of the primary a
phase is the same.
[0036] The obtained titanium alloy tubes of the disclosure have a
bimodal microstructure. The primary a phase is equiaxed and
accounts for 15%-35%. The diameter-thickness ratio of the titanium
alloy bimodal microstructure tube is less than 4. The disclosure
adopts a conical roll with double helix, a large feeding angle and
cross angle, and the rolling parameters such as diameter reduction
rate and the roll speed are reasonably designed, which can
effectively avoid the temperature rise in the whole process of
rotary piercing, and obtain a titanium alloy tube with bimodal
microstructure.
[0037] By reasonably designing the feeding angle, cross angle, roll
speed, diameter reduction rate of the Mannesmann rotary piercer and
the length of the plug, the temperature rise of the alloy billet in
the process of rotary piercing can be effectively controlled,
thereby avoiding the formation of the Widmanstatten microstructure,
and improving the quality of the titanium alloy tube with bimodal
microstructure. The centering devices of the Mannesmann rotary
piercer are unevenly distributed, thus improving the strength and
rigidity of the centering devices acting on the mandril, and
reducing the occurrence rate of the rolling block phenomenon.
[0038] It will be obvious to those skilled in the art that changes
and modifications may be made, and therefore, the aim in the
appended claims is to cover all such changes and modifications.
* * * * *