U.S. patent application number 12/563184 was filed with the patent office on 2011-03-24 for method and tool for contracting tubular members by electro-hydraulic forming before hydroforming.
This patent application is currently assigned to FORD GLOBAL TECHNOLOGIES, LLC. Invention is credited to Sergey Fedorovich Golovashchenko.
Application Number | 20110067467 12/563184 |
Document ID | / |
Family ID | 43708076 |
Filed Date | 2011-03-24 |
United States Patent
Application |
20110067467 |
Kind Code |
A1 |
Golovashchenko; Sergey
Fedorovich |
March 24, 2011 |
METHOD AND TOOL FOR CONTRACTING TUBULAR MEMBERS BY
ELECTRO-HYDRAULIC FORMING BEFORE HYDROFORMING
Abstract
A tubular preform is contracted in an electro-hydraulic forming
operation. The tubular preform is wrapped with one or more coils of
wire and placed in a chamber of an electro-hydraulic forming tool.
The electro-hydraulic forming tool is discharged to form a
compressed area on a portion of the tube. The tube is then placed
in a hydroforming tool that expands the tubular preform to form a
part.
Inventors: |
Golovashchenko; Sergey
Fedorovich; (Beverly Hills, MI) |
Assignee: |
FORD GLOBAL TECHNOLOGIES,
LLC
Dearborn
MI
|
Family ID: |
43708076 |
Appl. No.: |
12/563184 |
Filed: |
September 21, 2009 |
Current U.S.
Class: |
72/56 |
Current CPC
Class: |
Y10T 29/49805 20150115;
B21D 26/12 20130101; Y10T 29/49803 20150115 |
Class at
Publication: |
72/56 |
International
Class: |
B21D 26/06 20060101
B21D026/06 |
Claims
1. A method comprising: encircling an exterior surface of a tube
with at least one wire loop; loading the tube and wire into an
electro-hydraulic forming tool having a chamber that contains a
liquid; discharging a stored power source through the wire loop to
create a shockwave in the liquid; compressing the tube in a
localized area with the shockwave; and hydroforming the tube by
expanding the tube to form a part.
2. The method of claim 1 wherein the step of encircling the tube
further comprises providing a single turn of the wire.
3. The method of claim 1 wherein the step of encircling the tube
further comprises providing a plurality of turns of the wire.
4. The method of claim 1 wherein the step of discharging the stored
power source further comprises actuating a capacitor circuit.
5. The method of claim 1 wherein the step of compressing the tube
in a localized area further comprises compressing the tube to a
uniform extent around the circumference of the tube in the
localized area.
6. The method of claim 1 wherein the tube initially has an average
cross-section, and wherein the cross-section of the localized area
of the part is less than the average cross-section of the tube.
7. A tool for forming a tube comprising: a first tool part that
defines a first part of a chamber; a second tool part that defines
a second part of the chamber, wherein the second tool part engages
the first tool part to define the chamber; a liquid disposed in the
chamber; a single loop of wire disposed about a portion of the tube
that is submerged in the liquid in the chamber; a source of
electrical energy that may be rapidly discharged through the wire;
and wherein the source of electrical energy is connected to the
wire to create a shockwave that compresses the portion of the
tube.
8. (canceled)
9. A tool for forming a tube comprising: a first tool part that
defines a first part of a chamber; a second tool part that defines
a second part of the chamber, wherein the second tool part engages
the first tool part to define the chamber; a liquid disposed in the
chamber; a wire disposed about a portion of the tube that is
submerged in the liquid in the chamber, wherein the wire is a coil
of wire that includes a plurality of loops; a source of electrical
energy that may be rapidly discharged through the wire; and wherein
the source of electrical energy is connected to the wire to create
a shockwave that compresses the portion of the tube.
10. The tool of claim 9 wherein the diameter of the loops of wire
are the same.
11. The tool of claim 9 wherein the diameter of the loops of wire
are varied to control the intensity of the shockwave and the extent
of compression of the tube.
12. The tool of claim 7 further comprising a seal that is provided
between the first and second tool parts.
13. The tool of claim 7 wherein the chamber is cylindrical and the
tube and the wire are disposed coaxially relative to each other and
the cylindrical chamber.
14. A tool for forming a tube comprising: a first tool part that
defines a first part of a chamber; a second tool part that defines
a second part of the chamber, wherein the second tool part engages
the first tool part to define the chamber; a liquid disposed in the
chamber; a wire disposed about a portion of the tube that is
submerged in the liquid in the chamber, wherein the wire is wound
in a helical coil around the tube; a source of electrical energy
may be rapidly discharged through the wire; and wherein the source
of electrical energy is connected to the wire to create a shockwave
that compresses the portion of the tube.
15. A tool for forming a tube comprising: a first tool part that
defines a first part of a chamber, wherein the first tool part has
a first port through which a liquid is provided to the chamber and
a second port through which air is evacuated from the chamber; a
second tool part that defines a second part of the chamber, wherein
the second tool part engages the first tool part to define the
chamber; a liquid disposed in the chamber; a wire disposed about a
portion of the tube that is submerged in the liquid in the chamber;
a source of electrical energy that may be rapidly discharged
through the wire; and wherein the source of electrical energy is
connected to the wire to create a shockwave that compresses the
portion of the tube.
16. The tool of claim 15 wherein the first and second tool parts
define two end openings that are provided at spaced locations and
the tube is received in the openings with the portion of the tube
that is submerged in the liquid being disposed between the two end
openings.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] The present invention relates to electro-hydraulic forming
to contract 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. The electric arc
discharge vaporizes some of the surrounding fluid and creates shock
waves in the fluid. A workpiece that is in contact with the fluid
may be deformed by the shock waves to fill an evacuated die.
[0005] Electro-hydraulic forming may be used, for example, to form
a flat blank in 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 these high strength, lightweight materials is
increasing and has been proposed for hydroforming tubes. Tube
hydroforming is well-known technology that is currently used in
production. One problem with hydroforming tubes is that the tube
tends to thin in areas that are formed to a greater extent.
[0007] The above problems are addressed by Applicant's invention as
summarized below.
SUMMARY
[0008] The method and tool disclosed and claimed in this
application provide increased opportunities for hydroforming parts
from ductile steel and also high strength materials that have
reduced formability. By applying the method, larger diameter
tubular preforms can be used to form parts having smaller diameter
cross-sections in localized areas. Generally, the tube blank is
selected to correspond to the average perimeter of the final part.
The tube blank provides material that is worked in the hydroforming
process. The hydroforming process is generally used to expand the
tubular blank with pressure that is exerted from the inside of the
tube. With expansion hydroforming, the size of the tube is limited
to the minimum perimeter of the smallest cross-section of the
finished part. This limits the quantity of material that is
available for the hydroforming operation and, in turn, limits the
extent to which the tube can be expanded.
[0009] According to the method, a tube or tubular preform is first
formed to a reduced diameter in an electro-hydraulic forming
process that applies an impact force to the outer surface of the
tube. The partially contracted tube is then loaded into a
hydroforming tool and formed by the application of fluid pressure
to the inner side of the tube to expand the tube and form the tube
against the hydroforming die.
[0010] The tool that is illustrated to compress or contract the
tubular preform includes two parts that together define a chamber.
A portion of the tube is first encircled with a wire and then
placed in the chamber. The chamber is filled with a fluid, such as
water or oil, and sealed. The wire is selectively connected to a
source of stored electrical energy, such as a capacitor circuit, to
cause an electrical discharge in the fluid in the chamber that
forms the portion of the tube radially inward to a reduced
cross-sectional area. The balance of the tube may be maintained at
full cross-sectional area size. The tubular preform is later formed
by expanding in a hydroforming operation in the full
cross-sectional area. The portion of the tube that was compressed
may be expanded from the reduced cross-sectional area.
[0011] Other aspects of Applicant's concept will be better
understood in view of the attached drawings and detailed
description of the illustrated embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a diagrammatic cross-sectional view of an
electro-hydraulic forming tool that is used to contract the
diameter of a tube prior to hydroforming.
[0013] FIG. 2 is a cross-sectional view taken along the line 2-2 in
FIG. 1.
[0014] FIG. 3 is a cross-sectional view similar to FIG. 2, but
showing an alternative embodiment wherein variable diameter coils
are used to contract the tube to different extents along different
portions of the tube.
[0015] FIG. 4 is a diagrammatic cross-sectional view of an
alternative embodiment of the electro-hydraulic forming tool
wherein a single loop of wire is provided in the electro-hydraulic
forming tool.
[0016] FIG. 5 is a diagrammatic cross-sectional view of a tube
showing the tube before contraction and after contraction.
[0017] FIG. 6 is a flowchart illustrating the steps of the method
of compressing a tubular preform in an electro-hydraulic forming
tool prior to forming the tubular preform by expanding the tube in
a hydroforming operation.
DETAILED DESCRIPTION
[0018] Referring to FIG. 1, an electro-hydraulic forming tool 10 is
used to contract a tubular preform 12 prior to hydroforming the
tubular preform is diagrammatically illustrated. A wire coil 14 is
wrapped in a spaced relationship around the tubular preform 12 and
submerged in a liquid 18, such as water or oil. The liquid 18 is
contained within a chamber 20 defined by a first tool part 22 and a
second tool part 24. The chamber 20 must be sealed, as shown by
first seal 26 and second seal 28. The chamber 20 is filled by an
upper port 30 and a lower port 32. It should be understood that a
single fill/evacuation port could be provided instead of the two
ports as illustrated.
[0019] Tubular preform 12 and wire coil 14 are preassembled and
then inserted into the chamber 20 defined by the first tool part 22
and the second tool part 24. When assembled, the first seal 26
engages a second seal 28. The chamber 20 is filled through the
lower port until the liquid flows out of upper port 30.
[0020] Referring to FIG. 2, the electro-hydraulic forming tool 10
is shown with the second tool part 24 (shown in FIG. 1) removed.
The tubular preform 12 is encircled by the wire coils 14 and
immersed in the liquid 18. The first tool part 22 retains the first
seal 26 to seal the chamber 20 as described with reference to FIG.
1 above. The seal 26 extends about the periphery of the forming
chamber 20 and on one side of the tubular perform 12. (The seal 26
is not visible behind the tubular perform 12 as viewed in FIGS.
2-5.)
[0021] A capacitor circuit 36 that comprises a stored power source
is connected to opposite ends of the wire coil 14 by a positive
electrode 38 and a negative electrode 40. Alternatively, the stored
power source may be an induction circuit that could be used instead
of the capacitor circuit. When the capacitor circuit 36 is
actuated, the wire coil 14 is energized to create a shockwave
within the fluid 18 that is imparted to the tubular member 12. The
tubular member in the area where the wire coil 14 encircles the
tubular member is compressed from an initial tube section 42 shown
in solid line to a contracted tube section 44 shown in phantom
lines.
[0022] FIG. 3 is a view similar to FIG. 2 that shows an alternative
embodiment wherein reduced diameter wire loops 46 are provided as
part of the wire coil 14. The tubular preform 12 is shown wrapped
by the wire coil 14 including the reduced diameter wire loops 46
and is submerged in the fluid 18. The wire coil 14 is connected to
a capacitor circuit, as previously described with reference to FIG.
2. When the capacitor circuit 36 is discharged, the more closely
wrapped wire loops 46 are closer to the tubular preform 12 and, as
a result, exert a greater contraction force on the tubular member
12. This greater contraction force compresses that portion of the
tube to a greater extent compared to the contraction force applied
by the other loops of the wire coil 14.
[0023] Referring to FIG. 4, an alternative embodiment of the
electro-hydraulic forming tool is shown in which a single loop wire
48 is provided. In the embodiment shown in FIG. 4, the same
reference numerals are used as previously described with reference
to FIGS. 1-3. The single loop of wire 48 is wrapped in a spaced
relationship around the tubular preform 12 and immersed within the
liquid 18 in the chamber 20. Only one part of the chamber 20 is
shown in FIG. 4 which is that part defined first tool part 22 with
its associated seal 26. The second tool part 24 and the second seal
28 are also included in this embodiment, but are not illustrated to
better illustrate the tool.
[0024] Referring to FIG. 5, the embodiment of FIG. 4 is shown
including the tubular preform 12 with a full diameter wall section
illustrated by reference numeral 38 and a contracted wall section
shown in phantom lines and identified by reference numeral 40. The
single loop wire 48 may be used to act on a smaller portion of the
tubular member 12 than in the embodiment shown in FIGS. 1-3.
[0025] Referring to FIG. 6, a flowchart is illustrated that shows
the steps of the process used to initially contract portions of a
tube prior to hydroforming to expand the tube into a desired part
shape. In many instances, the tube is preformed by bending to form
the tube to a desired shape along its length. The first step in the
process may follow the preform bending and comprises wrapping the
coiled wire around the tube at 50. The coil and tube are then
inserted into the electro-hydraulic forming tool at 52. The
electro-hydraulic forming tool is discharged to compress a
localized area of the tube at 54. The wire is destroyed by the
discharge and essentially vaporizes creating a shockwave in the
electro-hydraulic forming tool chamber 20 that impacts the tubular
preform to compress it in a localized area. The tube may then be
removed from the electro-hydraulic forming tool at 56. The tubular
preform with the contracted localized area is then inserted into a
hydroforming tool at 58. The hydroforming tool forms the tubular
preform at 60 expanding appropriate portions of the tube including
portions of the tube that were not contracted. The portions of the
tube that were contracted or compressed in the electro-hydraulic
forming tool may also be expanded in the hydroforming operation at
60. The tubular preform is compressed to the minimum diameter of
the part to be formed.
[0026] 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.
* * * * *