U.S. patent application number 16/196015 was filed with the patent office on 2020-05-21 for thermal-assisted multiple sheet roll forming.
The applicant listed for this patent is GM GLOBAL TECHNOLOGY OPERATIONS LLC. Invention is credited to John E. Carsley, Anil K. Sachdev, Robert N. Saje.
Application Number | 20200156134 16/196015 |
Document ID | / |
Family ID | 70470670 |
Filed Date | 2020-05-21 |
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United States Patent
Application |
20200156134 |
Kind Code |
A1 |
Sachdev; Anil K. ; et
al. |
May 21, 2020 |
THERMAL-ASSISTED MULTIPLE SHEET ROLL FORMING
Abstract
A thermal-assisted method deforms a sheet metal assembly having
constrained ends. A focus bending area located between the
constrained ends is heated. The focus bending area is bent while
the sheet metal assembly is within an elevated bending temperature
range. A sheet metal assembly may be formed by this method, which
includes an outer metal sheet and an inner metal sheet fixed
together to form constrained ends. The sheet metal assembly has a
bend formed therein between the first and second constrained ends,
wherein each metal sheet is bent at the bend with a maximum gap
between the inner and outer metal sheets at the bend. The maximum
gap is no greater than five times the thickness of one of the inner
and outer metal sheets, and the bend has a radius less than three
times the thickness of one of the inner and outer sheets.
Inventors: |
Sachdev; Anil K.; (Rochester
Hills, MI) ; Carsley; John E.; (Oakland, MI) ;
Saje; Robert N.; (Shelby Township, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GM GLOBAL TECHNOLOGY OPERATIONS LLC |
Detroit |
MI |
US |
|
|
Family ID: |
70470670 |
Appl. No.: |
16/196015 |
Filed: |
November 20, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B32B 15/012 20130101;
B21D 5/008 20130101; C21D 1/667 20130101; B21D 35/005 20130101;
B21D 5/08 20130101; B21D 35/007 20130101; B32B 15/011 20130101;
C21D 1/34 20130101; C21D 2251/02 20130101; B21D 37/16 20130101;
C21D 2221/00 20130101 |
International
Class: |
B21D 5/08 20060101
B21D005/08; C21D 1/667 20060101 C21D001/667 |
Claims
1. A method of forming a sheet metal assembly, the method
comprising: providing a sheet metal assembly, the sheet metal
assembly including at least an outer metal sheet and an inner metal
sheet, the outer and inner metal sheets being fixed together to
form a constrained first end and a constrained second end, the
sheet metal assembly having an initial temperature; heating a focus
bending area of the sheet metal assembly to at least a bending
temperature range that is greater than the initial temperature, the
focus bending area being located between the constrained first and
second ends of the sheet metal assembly; and bending the focus
bending area of the sheet metal assembly while the sheet metal
assembly is within the bending temperature range.
2. The method of claim 1, wherein the step of bending includes
rolling a roller tool against the sheet metal assembly to form a
bend in the focus bending area, the bend having an outer side and
an inner side.
3. The method of claim 2, further comprising disposing a heat
source adjacent to the outer sheet at the focus bending area prior
to performing the heating step, and heating the focus bending area
via the heat source.
4. The method of claim 1, wherein the step of heating includes
applying a laser beam to the focus bending area.
5. The method of claim 1, further comprising: providing the inner
metal sheet as being formed of a first material; and providing the
outer metal sheet as being formed of a second material, the first
and second materials being different from one another.
6. The method of claim 1, further comprising: providing one of the
inner and outer metal sheets as being formed of an aluminum alloy;
and providing the other of the inner and outer metal sheets as
being formed of steel.
7. The method of claim 1, further comprising: providing the inner
metal sheet having a first thickness; and providing the outer metal
sheet having a second thickness, the first and second thicknesses
being unequal.
8. The method of claim 1, wherein the step of bending comprises
forming a bend at the focus bending area, the method further
comprising maintaining a maximum gap between the inner and outer
metal sheets at the bend, the maximum gap being no greater than
five times the thickness of one of the inner and outer metal
sheets.
9. The method of claim 8, wherein the maximum gap is no greater
than half the thickness of one of the inner and outer metal
sheets.
10. The method of claim 1, further comprising quenching the sheet
metal assembly rapidly after bending to retain a high-temperature
phase structure at room temperature.
11. The method of claim 1, wherein the step of bending comprises
forming a bend at the focus bending area, the bend having a radius
less than three times the thickness of one of the inner and outer
metal sheets.
12. The method of claim 1, further comprising providing the inner
and outer metal sheets having substantially equal thicknesses.
13. The method of claim 2, further comprising providing a die
having a die bend formed therein, wherein the step of bending
includes rolling the sheet metal assembly against the die bend with
the roller tool to form a part bend in the sheet metal
assembly.
14. A sheet metal assembly comprising: an outer metal sheet; and an
inner metal sheet, the outer and inner metal sheets being fixed
together to form a constrained first end and a constrained second
end, the sheet metal assembly having a bend formed therein between
the first and second constrained ends, wherein each metal sheet is
bent at the bend with a maximum gap between the inner and outer
metal sheets at the bend, the maximum gap being no greater than
five times the thickness of one of the inner and outer metal
sheets, the bend having a radius less than three times the
thickness of one of the inner and outer metal sheets.
15. The sheet metal assembly of claim 14, the inner metal sheet
being formed of a first material, and the outer metal sheet being
formed of a second material, the first and second materials being
different from one another.
16. The sheet metal assembly of claim 15, one of the inner and
outer metal sheets being formed of an aluminum alloy, and the other
of the inner and outer metal sheets being formed of steel.
17. The sheet metal assembly of claim 14, the inner metal sheet
having a first thickness, and the outer metal sheet having a second
thickness, the first and second thicknesses being unequal.
18. The sheet metal assembly of claim 14, wherein the maximum gap
is no greater than half the thickness of one of the inner and outer
metal sheets.
19. The sheet metal assembly of claim 14, at least one of the inner
and outer metal sheets retaining a high-temperature phase structure
at room temperature.
20. The sheet metal assembly of claim 14, the inner and outer metal
sheets having substantially equal thicknesses.
Description
FIELD
[0001] The present technology relates generally to metal forming
and, more specifically, the present technology relates to a
heat-assisted metal forming process for a constrained sheet metal
assembly.
INTRODUCTION
[0002] Roll forming at a production facility is normally done at
room temperature using a series of progressively different rollers
to bend and plastically deform a single sheet of material into a
desired form. The process is continuous and at high speed, and the
result is a sheet material bent into a particular profile for a
particular purpose.
[0003] Future products are, however, being designed with higher
strength materials, while sophisticated computer analysis is
driving profile designs with increasingly greater complexity often
demanding sharp corners that are also high-strength. These two
factors work counter to each other and regions subjected to the
large strains fracture when bending high-strength materials.
[0004] To add difficulty, when two sheets are welded at their
edges, the entire sheet metal assembly needs to move as one unit.
If the two metal sheets, which may not have a neutral axis at their
mating surfaces, are attempted to be bent, the metal sheets attempt
to separate at the bend due to compressive stresses on the inner
side of the neutral axis and tensile stresses on the outer side of
the neutral axis. The result is that the inner sheet will be pushed
inward and the sheets will not stay together at the bend.
SUMMARY
[0005] The present disclosure provides a system and method that
enables deformation of a sheet metal assembly having attached
constrained ends around a tight bend without the sheet metal
separating at the bend, as well as a sheet metal assembly that has
a sharp bend with sheet metal pieces that substantially stay
together at the bend.
[0006] In one form, which may be combined with or separate from the
other forms disclosed herein, a method of forming a sheet metal
assembly is provided. The method includes providing a sheet metal
assembly, the sheet metal assembly including at least an outer
metal sheet and an inner metal sheet, where the outer and inner
metal sheets are fixed together to form a constrained first end and
a constrained second end. The sheet metal assembly has an initial
temperature. The method also includes heating a focus bending area
of the sheet metal assembly to at least a bending temperature range
that is greater than the initial temperature. The focus bending
area is located between the constrained first and second ends of
the sheet metal assembly. Additionally, the method includes bending
the focus bending area of the sheet metal assembly while the sheet
metal assembly is within the bending temperature range.
[0007] In another form, which may be combined with or separate from
the other forms disclosed herein, a sheet metal assembly is
provided that includes an outer metal sheet and an inner metal
sheet. The outer and inner metal sheets are fixed together to form
a constrained first end and a constrained second end. The sheet
metal assembly has a bend formed therein between the first and
second constrained ends. Each metal sheet is bent at the bend with
a maximum gap between the inner and outer metal sheets at the bend.
The maximum gap is no greater than five times the thickness of one
of the inner and outer metal sheets. The bend has a radius less
than three times the thickness of one of the inner and outer metal
sheets.
[0008] Additional features may be provided, including but not
limited to the following: wherein the step of bending includes
rolling a roller tool against the sheet metal assembly to form a
bend in the focus bending area, the bend having an outer side and
an inner side; disposing a heat source adjacent to the outer sheet
and/or the inner sheet at the focus bending area prior to
performing the heating step; heating the focus bending area via the
heat source; wherein the step of heating includes applying a laser
to the focus bending area; providing the inner metal sheet as being
formed of a first material; providing the outer metal sheet as
being formed of a second material; the first and second materials
being different from one another or the same; providing at least
one of the inner and outer metal sheets as being formed of an
aluminum alloy; providing at least one of the inner and outer metal
sheets as being formed of steel; providing the inner metal sheet
having a first thickness; providing the outer metal sheet having a
second thickness; the first and second thicknesses being unequal;
the first and second thicknesses being substantially equal to one
another; maintaining a maximum gap between the inner and outer
metal sheets at the focus bending area; the maximum gap being no
greater than five times the thickness of one of the inner and outer
metal sheets; the maximum gap being no greater than half the
thickness of one of the inner and outer metal sheets; quenching the
sheet metal assembly rapidly after bending to retain a
high-temperature phase structure at room temperature or to obtain a
different phase structure based on a controlled cooling rate based
on equilibrium phase transformations; wherein bending the sheet
metal assembly further comprises forming the bend to a radius less
than three times the thickness of one of the inner and outer metal
sheets; providing a die or an opposing roller tool having a bend
formed therein; wherein the step of bending the sheet metal
assembly includes rolling the sheet metal assembly against the die
bend with the roller tool to form a part bend in the sheet metal
assembly; and/or at least one of the inner and outer metal sheets
retaining a high-temperature phase structure at room
temperature.
[0009] Further features and advantages of the technology, as well
as the structure and operation of various examples of the
technology, are described in detail below with reference to the
accompanying drawings. It is noted that the technology is not
limited to the specific examples described herein. Such examples
are presented herein for illustrative purposes only. Additional
examples will be apparent to persons skilled in the relevant art(s)
based on the teachings contained herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The drawings described herein are for illustration purposes
only and are not intended to limit the scope of the present
disclosure in any way.
[0011] FIG. 1 is a schematic cross-sectional view showing an unbent
sheet metal assembly in a first step of a method of forming the
sheet metal assembly, according to the principles of the present
disclosure;
[0012] FIG. 2 is a schematic cross-sectional view of the unbent
sheet metal assembly of FIG. 1 with accompanying tools for forming
the sheet metal assembly, in accordance with the principles of the
present disclosure;
[0013] FIG. 3 is a schematic cross-sectional view of the sheet
metal assembly of FIGS. 1 and 2 in a partially bent configuration,
in accordance with the principles of the present disclosure;
[0014] FIG. 4 is a schematic cross-sectional view of the sheet
metal assembly of FIGS. 1-3 having a bend formed therein, in
accordance with the principles of the present disclosure;
[0015] FIG. 5 is a schematic cross-sectional view of a bent sheet
metal assembly after performing steps as illustrated in FIGS. 1-4,
in accordance with the principles of the present disclosure;
and
[0016] FIG. 5A is a schematic cross-sectional view of another
variation of the bent sheet metal assembly after performing steps
as illustrated in FIGS. 1-4, in accordance with the principles of
the present disclosure.
DETAILED DESCRIPTION
[0017] While the present technology is described herein with
illustrative examples for particular applications, it should be
understood that the technology is not limited thereto. Those
skilled in the art with access to the teachings provided herein
will recognize additional modifications, applications, and examples
within the scope thereof and additional fields in which the
technology would be of significant utility.
[0018] The present disclosure discloses a thermal-assisted method
for plastically deforming a sheet metal assembly. Thus, the method
relates to forming a sheet metal assembly having a bend
therein.
[0019] A sheet metal assembly 10 is provided that includes at least
an "outer" metal sheet 12 and an "inner" metal sheet 14. The metal
sheet 12 is referred to as an "outer sheet," and the metal sheet 14
is referred to as an "inner sheet," because the metal sheet 12 will
be located on an outer side of a bend and the metal sheet 14 will
be located on an inner side of a bend, which will be described
below. Additional metal sheets may also be included in the sheet
metal assembly 10, if desired. Therefore, the sheet metal assembly
10 could have two, three, four, five, or any desired number of
metal sheets.
[0020] The outer and inner metal sheets 12, 14 are fixed together
to form a constrained first end 16 and a constrained second end 18.
For example, the outer and inner metal sheets 12, 14 may be fixed
together by welding, brazing, rivets, or in any other desired
manner. In the illustrated example, weld joints 20 attach the outer
and inner metal sheets 12, 14 together at the first and second
constrained ends 16, 18.
[0021] The sheet metal assembly 10 has a certain temperature,
referred to as the initial temperature, prior to bending. The
initial temperature may be room temperature, by way of example.
[0022] Each metal sheet 12, 14 may be formed of the same or
dissimilar materials. For example, both metal sheets 12, 14 could
be formed of steel, or one of the metal sheets 12, 14 could be
formed of steel and the other 12, 14 of aluminum or an aluminum
alloy. Each metal sheet 12, 14 may be either coated or
uncoated.
[0023] If alloyed, the aluminum alloy may include at least 85 wt %
aluminum. Some notable aluminum alloys that may constitute the
coated or uncoated aluminum substrate are an aluminum-magnesium
alloy, an aluminum-silicon alloy, an aluminum-magnesium-silicon
alloy, and an aluminum-zinc alloy. If coated, the aluminum metal
sheet may include a surface layer of a refractory oxide material
(native and/or produced during manufacture when exposed to
high-temperatures, e.g., mill scale) comprised of aluminum oxide
compounds and possibly other oxide compounds such as, for example,
those of magnesium oxide if the aluminum substrate contains
magnesium. The aluminum metal sheet may also be coated with a layer
of zinc, tin, or a metal oxide conversion coating comprised of
oxides of titanium, zirconium, chromium, or silicon, such as
described in U.S. Pat. No. 9,987,705. The aluminum metal sheet may
be provided in wrought or cast or extruded forms. For example, the
metal sheet may be composed of a 2xxx, 3xxx, 4xxx, 5xxx, 6xxx, or
7xxx series wrought aluminum alloy sheet layer, extrusion, forging,
or other worked article. Alternatively, the metal sheet may be
composed of a 4xx.x, 5xx.x, 6xx.x, or 7xx.x series aluminum alloy
casting. Other aluminum alloys that may be used include, but are
not limited to, AA5754 and AA5182 aluminum-magnesium alloy, AA6111
and AA6022 aluminum-magnesium-silicon alloy, AA7003 and AA7055
aluminum-zinc alloy, and Al-10Si-Mg aluminum die casting alloy. An
aluminum metal sheet may further be employed in a variety of
tempers including annealed (O), strain hardened (H), an unstable
condition (W), and solution heat treated (T), if desired. When more
than one aluminum metal sheet is used in the sheet metal assembly
10, the aluminum metal sheets may be the same or different in terms
of their compositions, thicknesses, and/or form (e.g., wrought or
cast).
[0024] One or both metal sheets 12, 14 may be formed of a steel
having any of a wide variety of strengths and grades that is either
coated or uncoated. The steel sheet may be hot-rolled or
cold-rolled and may be composed of steel such as mild steel,
interstitial-free steel, bake-hardenable steel, high-strength
low-alloy (HSLA) steel, dual-phase (DP) steel, complex-phase (CP)
steel, martensitic (MART) steel, transformation induced plasticity
(TRIP) steel, quenched and partitioned steel (Q&P), twining
induced plasticity (TWIP) steel, and boron steel such as when the
steel sheet includes press-hardened steel (PHS). If coated, the
steel sheet may include a surface layer of zinc (e.g., hot-dip
galvanized or electrogalvanized), a zinc-iron alloy (e.g.,
galvannealed or electrodeposited), a zinc-nickel alloy, nickel,
aluminum, an aluminum-magnesium alloy, an aluminum-zinc alloy, or
an aluminum-silicon alloy.
[0025] Either of the metal sheets 12, 14 (and additional sheets, if
included) may be a cold rolled sheet metal, for example aluminum of
strength greater than 300 megapascal (MPa), preferably greater than
500 MPa, or steel of strength greater than 1000 MPa, preferably
greater than 1500 MPa.
[0026] The method disclosed herein is used to ultimately form the
sheet metal assembly 10 into an assembly having a bend in it. Each
of the metal sheets 12, 14 may have unequal thicknesses t1, t2,
respectively, or the thicknesses t1, t2 may be substantially equal
to one another. The thicknesses t1, t2 may be in the range of
0.2-4.0 mm, by way of example. In cases where t1 and t2 are
unequal, a neutral axis N is not located at the interface between
one of the metal sheets 12, 14, but rather, the neutral axis N runs
through one of the metal sheets 12, 14 (in this case, sheet 12).
Accordingly, the entire inner sheet 14 will be in compression when
the sheet metal assembly 10 is bent, and the outer sheet 12 will
have portions 13 that are in compression and portions 15 that are
in tension when the sheet metal assembly 10 is bent.
[0027] To ultimately form the sheet metal assembly 10 into an
assembly having a bend in it, the method includes heating a focus
bending area 22 of the sheet metal assembly 10 to at least a
bending temperature range that is greater than the initial
temperature. The focus bending area 22 may be heated, for example,
by a heat source 24 disposed adjacent to the outer metal sheet 12
so that the outer metal sheet 12 at the focus bending area 22
becomes ductile and can stretch around a bend. The heat source 24
is disposed adjacent to the outer sheet 12 at the focus bending
area 22 prior to performing the heating step. The focus bending
area 22 is located between the constrained first and second ends
16, 18 of the sheet metal assembly 10. In the alternative, the heat
source 24 could be disposed adjacent to the inner sheet 14 at the
focus bending area 22 so that the heat is applied from the inside
of the resulting bend.
[0028] The heat source 24 may be a laser heat source, such as a
laser scanning beam, by way of example. Accordingly, the step of
heating the focus bending area 22 may be accomplished by applying a
laser beam 25 to the focus bending area 22. Other examples of
heating may be induction, flame, focused halogen, high intensity
infra-red sources, conduction heating, or resistance heating, in
which a current would pass from one roller tool in contact with one
side of the sheet through the sheet thickness to a second roller in
contact with the other side of the sheet. In resistance heating,
the resistance of the material to the flow of electrical current is
what causes the heating effect. The heating is then used to assist
the bending of the sheet material. In conduction heating, one or
more rollers may be heated by external sources (not shown), such
that the material is heated by contact and bent as the material
passes through these roller dies.
[0029] Once the focus bending area 22 reaches the bending
temperature range, the focus bending area 22 of the sheet metal
assembly 10 is bent to form a bend within the sheet metal assembly
10. The bending is accomplished while the sheet metal assembly 10
is within the bending temperature range. In some examples, the
bending temperature range is within a two-phase sub-critical
temperature region or above the critical temperature, but
preferably above the critical temperature. Therefore, the actual
bending temperature range depends on the material used for the
metal sheets 12, 14. In some examples, the heat source 24,
preferably laser, heats the sheet metal 12, 14 to a solutionizing
or austenitizing temperature.
[0030] Referring now to FIGS. 2 and 3, in some examples, to
accomplish the bending of the sheet metal assembly 10 in the
bending temperature range, a roller tool 26 is rolled against the
sheet metal assembly 10 to form a bend 28 in the focus bending area
22. The sheet metal assembly 10 may be rolled by the roller tool 26
against a die 30 having a die bend 32 formed therein. In such an
example, the sheet metal assembly 10 is bent by rolling the sheet
metal assembly 10 against the die bend 32 with the roller tool 26
to form the bend 28 in the sheet metal assembly 10. The heat source
24 preferably is disposed directly adjacent to the roller tool 26
so that the focus bending area 22 is maintained within the bending
temperature range while the sheet metal assembly 10 is bent by the
roller tool 26.
[0031] As a result, as shown in FIGS. 4 and 5, a sharp bend 28 is
formed in the sheet metal assembly 10, which is formed in both the
outer and inner metal sheets 12, 14. The bend 28 has an outer side
34 formed in the outer sheet 12 and an inner side 36 formed in the
inner sheet 14. Thus, the bend 28 is comprised of both an outer
bend 38 in the outer sheet 12 and an inner bend 40 in the inner
sheet 14. The outer and inner bends 38, 40 fit snugly together to
form the bend 28 in the sheet metal assembly 10. In some examples,
the outer and inner bends 38, 40 have no gap between them and
contact each other, as shown in FIG. 5. The heating of the focus
bending area 22 reduces forces on the portion 15 of the outer sheet
12 that is subject to tensile forces and helps balance the forces
in the inner and outer bends 40, 38.
[0032] Referring now to FIG. 5A, in other examples, there is a gap
g between the outer and inner bends 38, 40; in other words, there
is a gap g between the outer and inner metal sheets 12, 14 at the
bend 28 of the sheet metal assembly 10. By way of example, the gap
g may be, no greater than five times the thickness t2, t1 of one of
the inner and outer metal sheets 14, 12. Thus, in this example, the
outer sheet 12 is thicker than the inner sheet 14, so the gap g is
no greater than fives times t1. In other examples, the gap g may be
much smaller, such as no greater than one half of the thickness t1,
t2 of one of the outer and inner sheets 12, 14, or zero as shown in
FIG. 5.
[0033] Because of the high intensity heating according to the
present technology, the sheet metal assembly 10 can be bent to a
small radius that is one to three times the thickness of the
assembly 10 or of one of the individual sheets 12, 14. Thus, the
bend 28 may be a sharp bend having a radius of curvature r that is
less than three times the thickness of t1, t2 of one of the outer
and inner metal sheets 12, 14 or of the assembly 10 as a whole.
Accordingly, in one example, if the outer sheet 12 is thicker than
the inner sheet 14, then the bend 28 may have a radius of curvature
r that is no greater than three times t1, where the radius of
curvature r is measured from a center C of the curve of the bend 28
to a neutral axis N of the sheet metal assembly 10. In other
examples, the radius r is no greater than the thickness t1, t2 of
one of the outer and inner sheets 12, 14, or no greater than twice
the thickness t1, t2 of one of the outer and inner sheets 12,
14.
[0034] Cold rolled sheet metal exhibits elasticity and tends to
spring back after bending, resulting in a radius of curvature that
is greater than an initial bending radius. The use of intense laser
heating with the present technology can essentially eliminate or
greatly reduce the springback action of the sheet material, since
springback is related to strength and the strength during bending
at an elevated temperature is greatly reduced. The result is that
the radius of curvature r is substantially similar to what is
provided by the tooling system 26, 30 without the need for any post
processing. Thus, the resulting radius r with the present
technology can be smaller, such as between one to three times the
thickness t1, t2, or t1+t2.
[0035] Although a single roller 26 is illustrated as rolling the
sheet metal assembly 10 against the die 30, it should be understood
that any other bending process, such as that using a plurality of
rollers may be used to accomplish the bending when the sheet metal
assembly 10 is in the bending temperature range. For example, the
sheet metal assembly 10 may be continuously fed through parallel
rollers on a roll-forming production line. In some examples, the
sheet metal assembly 10 may be bent into the desired shape through
several bending steps, with each bending step being performed with
multiple roller dies. Additional heat sources may be used to heat
the sheet metal assembly 10 prior to each rolling step, where the
additional heat sources could be placed just before each set of
rollers.
[0036] After forming the bend 28 in the sheet metal assembly 10,
the method may include a rapid quenching. The rapid quenching can
be done through a plurality of cold air jets, through a liquid
spray (of water, oil, etc.), through quenching by contact (e.g.,
with roller tools), self-quench from the mass of the cold rolled
sheet metal, gas jet, or a combination of these quenching methods.
The rapid quenching avoids precipitation or any transformation in
the sheet metal assembly 10. The rapid quench allows the alloys
that demonstrate subsequent precipitation hardening, such as
aluminum or magnesium, to retain the high-temperature phase
structure at room temperature; the high-temperature phase will
transform upon reaching room temperature to other higher strength
phases, such as retained austenite, martensite, and/or bainite as
in the case of steels. After the heating and quenching, the roll
forming may continue with another set of roller dies, if
desired.
[0037] The detailed description and the drawings or figures are
supportive and descriptive of the many aspects of the present
disclosure. The elements described herein may be combined or
swapped between the various examples. While certain aspects have
been described in detail, various alternative aspects exist for
practicing the invention as defined in the appended claims. The
present disclosure is exemplary only, and the invention is defined
solely by the appended claims.
* * * * *