U.S. patent application number 14/039268 was filed with the patent office on 2014-01-23 for method and tool for expanding tubular members by electro-hydraulic forming.
This patent application is currently assigned to Ford Global Technologies, LLC. The applicant listed for this patent is Ford Global Technologies, LLC. Invention is credited to John Joseph Francis Bonnen, Sergey Fedorovich Golovashchenko.
Application Number | 20140020441 14/039268 |
Document ID | / |
Family ID | 43755452 |
Filed Date | 2014-01-23 |
United States Patent
Application |
20140020441 |
Kind Code |
A1 |
Golovashchenko; Sergey Fedorovich ;
et al. |
January 23, 2014 |
Method and Tool for Expanding Tubular Members by Electro-Hydraulic
Forming
Abstract
An electro-hydraulic forming tool having one or more electrodes
for forming parts with sharp corners. The electrodes may be moved
and sequentially discharged several times to form various areas of
the tube. Alternatively, a plurality of electrodes may be provided
that are provided within an insulating tube that defines a charge
area opening. The insulating tube is moved to locate the charge
area opening adjacent one of the electrodes to form spaced
locations on a preform. In other embodiments, a filament wire is
provided in a cartridge or supported by an insulative support.
Inventors: |
Golovashchenko; Sergey
Fedorovich; (Beverly Hills, MI) ; Bonnen; John Joseph
Francis; (Milford, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ford Global Technologies, LLC |
Dearborn |
MI |
US |
|
|
Assignee: |
Ford Global Technologies,
LLC
Dearborn
MI
|
Family ID: |
43755452 |
Appl. No.: |
14/039268 |
Filed: |
September 27, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12563191 |
Sep 21, 2009 |
8567223 |
|
|
14039268 |
|
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Current U.S.
Class: |
72/62 |
Current CPC
Class: |
B21D 26/10 20130101;
B21D 26/041 20130101 |
Class at
Publication: |
72/62 |
International
Class: |
B21D 26/041 20060101
B21D026/041 |
Claims
1-17. (canceled)
18. A tool for forming a tubular part comprising: a tubular member;
an electro hydraulic forming (EHF) die into which the tubular
member is inserted; an electrode assembly having an electrode wire
having a positive lead and a negative lead, the electrode wire is
disposed within a cartridge that is filled with a first volume of
fluid, the assembly is inserted within the tubular member, a second
volume of fluid is provided within the tubular member and the dual
electrode assembly is submerged in the second volume of fluid; an
energy storage device; and a controller that discharges the energy
storage device to provide an electrical discharge to the positive
lead and the negative lead of the electrode wire in the electrode
assembly that provides a shock wave that passes through the fluid
to conform the tubular member with the electro hydraulic forming
die.
19. The tool of claim 18 wherein the electrode wire is helically
coiled and extends in two segments that extend substantially the
full length of the cartridge, the two segments are connected one to
each of the leads.
20. The tool of claim 19 further comprising an insulator that is
disposed between the two segments of the wire except at a distal
end of the wire where the two segments are reversely turned
relative to each other.
21. The tool of claim 18 wherein the cartridge is a plastic tube
that is destroyed when the electrical discharge is provided.
22. (canceled)
Description
BACKGROUND
[0001] 1. Technical Field
[0002] The present invention relates to electro-hydraulic forming
to expand a tubular member in a die.
[0003] 2. Background Art
[0004] In electro-hydraulic forming ("EHF"), an electric arc
discharge is used to convert electrical energy to mechanical
energy. A capacitor bank, or other source of stored charge,
delivers a high current pulse across two electrodes that are
submerged in a fluid, such as oil or water. Electric arc discharge
vaporizes the surrounding fluid and creates shock waves. A
workpiece that is in contact with the fluid may be deformed by the
shock wave to fill an evacuated die.
[0005] Electro-hydraulic forming may be used, for example, to form
a flat blank into a one-sided die. The use of EHF for a one-sided
die may save tooling costs and may also facilitate forming parts
into shapes that are difficult to form by conventional press
forming or hydroforming techniques. Electro-hydraulic forming also
facilitates forming high strength steel, aluminum and copper
alloys. For example, advanced high strength steel (AHSS) and ultra
high strength steel (UHSS) can be formed to a greater extent with
electro-hydraulic forming techniques when compared to other
conventional forming processes. Lightweight materials, such as AHSS
and UHSS and high strength aluminum alloys are lightweight
materials that are used to reduce the weight of vehicles.
[0006] The use of high strength, lightweight materials is
increasing and has been proposed for hydroforming tubes. Tube
hydroforming is a well-known technology that is currently used in
production. One problem with conventional hydroforming of tubes is
that increased pressure is required to fill sharp corners in local
areas of the tube. The reduced formability of high strength steel
and aluminum exacerbates the problems associated with forming sharp
corners in localized areas of the parts when compared with forming
such parts with mild steel. To form a tube having sharp corners,
increased pressure is required in the hydroforming liquid that must
be applied to all of the internal surfaces of the tube. To
withstand the increased pressure, it is necessary to employ high
tonnage presses and may require tens of thousands of pounds of
pressure.
[0007] The above problems are addressed by Applicants' invention as
summarized below.
SUMMARY
[0008] It is proposed to use electro-hydraulic forming instead of
or in addition to hydroforming to form high strength parts that
have sharp corners in highly formed localized areas. A pair of
electrodes can be positioned inside the tube and a number of
sequential discharges may be utilized to form various areas of the
tube when using electro-hydraulic forming.
[0009] In another embodiment, a single electrode may be moved to
various locations within the tube and an electric arc discharge may
be created between the electrode and part or die that are connected
to a second electrode.
[0010] In yet another embodiment, a plurality of electrodes may be
provided within the tube and an insulating shield may be moved to
permit an electric arc discharge between one of the electrodes and
the tube wall.
[0011] In a further embodiment, a discharge wire filament may be
provided in a water filled tube cartridge that may be inserted in
one or both ends of the tubular member. If a discharge wire
filament is used, a wider area of the tube may be formed by the
electric arc discharge through the wire.
[0012] In yet another embodiment, a discharge wire filament may be
held by an insulating support and placed in contact with a tube
wall.
[0013] The above embodiments may be inserted in a tubular member
from one or both sides of the tubular member.
[0014] The above embodiments are described in detail below with
reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1A is a diagrammatic view of a electro-hydraulic tube
forming tool with two electrodes submerged in the tube before
forming.
[0016] FIG. 1B is a diagrammatic view of a electro-hydraulic tube
forming tool with two electrodes submerged in the tube after
forming.
[0017] FIG. 2 is a diagrammatic view of the two electrodes of the
embodiment shown in FIGS. 1A and 1B.
[0018] FIG. 3A is a diagrammatic view of an electro-hydraulic tube
forming tool having one electrode submerged in the tube with the
other electrode being connected to the tube or the die before
forming.
[0019] FIG. 3B is a diagrammatic view of an electro-hydraulic tube
forming tool having one electrode submerged in the tube with the
other electrode being connected to the tube or the die after
forming.
[0020] FIG. 4 is a diagrammatic view of the electrode of the
embodiment of FIGS. 3A and 3B.
[0021] FIG. 5 is a diagrammatic view of an electro-hydraulic tube
forming tool having multiple electrodes and a movable insulation
tube.
[0022] FIG. 6 is a diagrammatic view of an electro-hydraulic tube
forming tool in which a cartridge including a filament is inserted
in the tube.
[0023] FIG. 7 is a diagrammatic view of an electro-hydraulic tube
forming tool having a single wire that contacts the tube and is
inserted with a support in a tube.
[0024] FIG. 8 is a diagrammatic view of a multiple wire
electro-hydraulic tube forming tool in which one or more wires are
positioned in a tube wherein multiple wires may be used to provide
several discharges within the tube.
[0025] FIG. 9 is a diagrammatic view of an electro-hydraulic tube
forming tool wherein opposite ends of the tube may receive a wire
on an insulating support to provide multiple discharges within the
tube.
DETAILED DESCRIPTION
[0026] Referring to FIGS. 1A and 1B, an electro-hydraulic forming
("EHF") tool 10 is shown diagrammatically to include an upper die
12 and a lower die 14. A tubular pre-form 16, or blank, is disposed
within the upper and lower dies 12 and 14 and is shown in its
unformed condition in FIG. 1A and is shown in FIG. 1B after forming
with the tube conforming to the die. It should be understood that
the tubular pre-form is initially smaller than the die cavity, but
then expanded as a result of one or more electro-hydraulic forming
discharges to fill the cavity defined by the upper and lower dies
12 and 14.
[0027] A first electrode 18 and a second electrode 20 are inserted
within the tubular pre-form 16 and are submerged in water or oil,
as is well known in electro-hydraulic forming processes.
[0028] The first and second electrodes 18 and 20 are replaceable
and are attached to the distal end of leads 22 that are each
covered by an insulating sleeve 24 to prevent arcing between the
leads 22.
[0029] An end electrode seal 26 is provided at one of the tool 10
that receives the leads 22 and insulating sleeves 24 of the first
and second electrodes 18 and 20. The end electrode seal 26 seals
the tubular pre-form 16 on one end while an end fill seal 28 is
provided at the other end of the tubular pre-form 16 to seal the
other end thereof. The end fill seal 28 includes a port 30 through
which a fluid, such as oil or water, is provided to the inside of
the tubular pre-form 16. The tubular pre-form 16 is evacuated
through the port 30 so that the pre-form 16 is substantially
completely filled with the fluid when the EHF tool 10 discharges
between the first and second electrodes 18 and 20.
[0030] After each discharge, additional fluid may be provided
through the port 30. The fluid is supplied to the tube 16 at a
pressure that is less than 20 psi to fill the tube. The pressure is
released after the tube is filled. The EHF tool 10 may be
discharged multiple times to form different localized areas of the
tubular pre-form 16. Multiple discharges between the first and
second electrodes 18 and 20 may be provided within tube 16 in a
contoured area 32 where sharp corners may be required to be formed
in the tubular member 16.
[0031] A stored charge circuit 36, or pulse generator, is
illustrated in FIG. 1. The stored charge circuit 36 is connected to
the lead 22. To perform an electro-hydraulic forming cycle, the
stored charge circuit 36 is actuated to create a discharge between
the first and second electrodes 18 and 20. After the tubular
pre-form 16 is fully formed, the fluid is drained through the port
30 and the die may be opened for removal of the fully formed
pre-form 16.
[0032] A linear drive 38 is provided to move the electrodes 18 and
20 within the tubular member 16. The linear drive 38 may be a
hydraulic cylinder, a pneumatic cylinder or motor drive that is
capable of moving the first and second electrodes 18 within the
tubular pre-form 16. The linear drive 38 moves the electrodes 18
and 20 within the contoured area 32 to be formed by the EHF
tool.
[0033] As shown in FIG. 2, when the electrodes 18 and 20 are
positioned adjacent to an area to be formed, the electrodes 18 and
20 are discharged in a discharge zone 40. The charge is conducted
from the stored charge circuit 36 through the leads 22 to the first
and second electrodes 18 and 20. An arc is formed between the first
and second electrodes 18 and 20 in the discharge zone 40.
[0034] Referring to FIGS. 3A, 3B and 4, an alternative embodiment
of an EHF tool 50 is shown to include an upper die 52 and a lower
die 54. A tubular pre-form 56 is received between the upper and
lower dies 52 and 54. A single replaceable electrode 58 is inserted
within the tubular pre-form 56. The electrode 58 is provided with
an insulating block 60 that insulates the electrode 58 and prevents
electrode 58 from contacting the wall of the tubular pre-form 56.
An insulating sleeve 62 is also provided to prevent arcing between
the lead 63 and the tubular member 56. A second lead 64 may be
connected to the upper die 52 or lower die 54 of the EHF tool 50.
As shown, the electrode 58 is the positive electrode, while lead 64
is the negative electrode. It should be understood that the
polarity of the electrodes can be reversed.
[0035] An end electrode seal 66 is provided within one end of the
tubular member 56 to provide a seal between the tubular member and
the insulating sleeve 62 of the lead 63.
[0036] An end fill seal 68 is provided at the opposite end of the
tubular pre-form 56 that seals the end of the tubular pre-form 56
when the EHF tool 50 is discharged. A port 70 may be received
within the end fill seal 68. Fluid may be introduced into the
tubular pre-form 56 through the port 70. If the fluid is water, it
should be understood that it may be an emulsion of water and a rust
preventative. In addition, air may be evacuated through the port 70
to assure complete filling of the tubular pre-form 56 with the
fluid. When the forming cycle is complete, the port 70 may be used
to drain the fluid from the tubular pre-form 56.
[0037] A contoured area 72 is shown provided in which the tubular
pre-form 56 is intended to be expanded by the EHF tool 50.
[0038] Referring to FIG. 3, a stored charge circuit 76, or pulse
generator, is shown as it is connected to the ends of the leads 63
and 64. The stored charge circuit 76 is preferably a capacitive
charge storage device, as is well known in the art. Alternatively,
an inductive charge storage device may be used instead of the
capacitive charge storage device.
[0039] With continuing reference to FIG. 3A, a linear drive 78 is
shown engaging the electrode 63. The linear drive 78 is used to
move the electrode within the tube 56, especially in the contoured
area 72 to provide an EHF pulse when the stored charge circuit 76
is actuated. A discharge zone 80 is also shown in FIG. 3 where the
electrode 58 arcs to the inside of the tubular pre-form 56. The
pressure created by the arc creates a shockwave that forms the
tubular pre-form against the upper and lower dies 52 and 54.
[0040] Referring to FIG. 4, the lead 63 and a replaceable tip 58 is
shown in greater detail. The lead 63 is enclosed by insulating
sleeve 62. The insulating sleeve 62 may extend to the electrode 58
and also may cover the distal end of the electrode to partially
insulate, or shield, the electrode. A threaded hole 84 may be
provided in the end of the lead 63. In addition, a threaded end 86
may be provided on the lead and a bolt 88 may be inserted through
the electrode 58 to secure the electrode 58 to the threaded end 86.
Advantageously, the threads of the threaded hole 84 and the
threaded end 86 of the lead 63 may be of different pitch to
effectively lock the electrode 58 on the end of the lead 63.
[0041] As is also shown in FIG. 4, the insulation block 60 prevents
contact between the electrode 58 and the tube 56. The insulation
block 60 and insulating sleeve 62 prevent any discharges between
the lead 63 and the tubular member 56 along the length of the lead
63.
[0042] Referring to FIG. 5, an alternative embodiment of an EHF
tool 90 is shown that includes a tubular pre-form 92, or blank, in
which a plurality of electrodes 94 are inserted. The electrodes 94
are secured to a lead 96. The tubular preform 92 is connected to
lead 98. An insulating sleeve 100 and an insulating spacer 102 are
provided on the lead 96 to prevent inadvertent discharge between
the lead 96 and the wall of the tubular pre-form 92. An insulation
tube 106 is provided between the lead 96 and the tubular pre-form
92. The insulation tube 106 is operatively connected to a linear
drive 107. The insulation tube 106 defines a charge area opening
108.
[0043] The insulation tube 106 prevents arcing between any of the
electrodes 94 except where the electrode 94 is disposed adjacent to
the charge area opening 108. A discharge area 110 is illustrated
diagrammatically by an arrow indicating where the arc is formed
between one of the electrodes 94 and the tubular pre-form 92
through the charge area opening 108. The insulation tube 106
prevents arcing between the other electrode 94 and the tubular
pre-form 92. The insulation tube 106 is movable to locate the
charge area opening 108 adjacent to at least one of the electrodes
94. The insulation tube 106 is movable to permit the tool 90 to act
upon several locations within the tubular pre-form 92.
[0044] Referring to FIG. 6, another alternative embodiment is shown
in which a tube 116 may be acted upon by an EHF tool, including an
upper and a lower die that are not shown in FIG. 6. However, it
should be understood that the EHF tool including an upper and lower
die as described with reference to FIGS. 3-4 may be used with the
cartridge 118 shown in FIG. 6. The cartridge 118 includes an
insulator tube 120 and a filament wire 122. A support 126 is
provided to support the filament wire 122 within the insulator tube
120. Fluid 128 is provided both within the cartridge 118 and
between the cartridge 118 and the tube 116.
[0045] The filament wire 122 is connected to a positive polarity
connection 130 and a negative polarity connection 132 on opposite
ends. The cartridge 118 may be inserted into the tube 116. A stored
charge circuit, such as that disclosed in FIG. 3, is provided to
generate an electrical pulse that is provided to the filament wire
122. Upon actuation of the stored charge circuit, the pulse
vaporizes the filament wire 122 creating an arc and a shockwave
through the fluid 128 causing the tube 116 to be expanded into
engagement with the upper and lower die of the EHF tool. The
filament 122 may be coiled or otherwise retained between a support
126 and the cartridge 118.
[0046] Referring to FIG. 7, another alternative embodiment is
diagrammatically shown wherein a tube 146 is provided in an EHF
tool having an upper and lower die similar to that illustrated in
FIG. 3. The discharge wire 148 is inserted from one end of the tube
and supported by an insulating wire support 150. As previously
described, the tube 146 would be filled with fluid and the
discharge wire is submerged within the fluid. One end of the
discharge wire 148 is placed in contact with the tube 146 at a wall
contact point 152. A negative return 154, or ground, is connected
to the tube 146.
[0047] The discharge wire and negative return 154, or ground, are
operatively connected to the stored charge circuit, as previously
described with reference to FIG. 3. Upon actuation of the stored
charge circuit 76, the electrical discharge through the discharge
wire 148 completes the circuit through the tube 146. Upon actuation
of the stored charge circuit, the discharge wire is vaporized
creating an arc that in turn creates a shockwave that forces the
tube 146 into engagement with the upper and lower dies of the EHF
tool.
[0048] Referring to FIG. 8, another alternative embodiment is shown
in which a tube 168 receives a first wire 170 and a second wire 172
on a wire support 174. As described previously with reference to
FIG. 3, an EHF tool including an upper die and a lower die and a
stored charge circuit would also be included as part of this
embodiment. An insulating support 174 supports the first and second
wires to permit multiple discharges within the tube 168.
[0049] Upon a first actuation of the stored charge circuit, the
first wire 170 receives the discharge and vaporizes to generate a
shockwave to drive the wall of the tube 168 into engagement with
the die. A second pulse may be provided by the stored charge
circuit to the second wire 172 to provide a further forming
operation on the tube wall. The insulating and isolating support
174 may be moved within the tube if desired to provide an
electro-hydraulic forming pulse in a range of locations within the
tube 168. While two wire loops are shown, it should be understood
that more wires could be provided within the scope of the
invention.
[0050] Referring to FIG. 9, a tube 178 is shown that may be formed
according to a further embodiment of this disclosure. In this
embodiment, a first wire 180 is supported by a first support 182.
The first wire 180 and first support 182 are inserted through a
first end 184 of the tube 178. A second wire 186 supported by a
second support 188 is inserted from a second end 190 of the tube
178. In this embodiment, both ends of the tube are used to receive
one of the wires 180, 186 from opposite ends.
[0051] The concept of providing a wire through opposite ends or of
providing an electrode assembly to opposite ends of the tube may be
implemented with any previously described embodiments with minor
modification. It would be necessary to incorporate an end fill seal
and port in one or both of the seals provided at the ends of the
tube. By permitting the electrode or electrodes to be inserted from
opposite ends of the tube, difficult to reach areas may be accessed
by the EHF tool.
[0052] While embodiments of the invention have been illustrated and
described, it is not intended that these embodiments illustrate and
describe all possible forms of the invention. Rather, the words
used in the specification are words of description rather than
limitation, and it is understood that various changes may be made
without departing from the spirit and scope of the invention.
* * * * *