U.S. patent application number 14/900588 was filed with the patent office on 2016-05-26 for process and installation for producing a press-hardened sheet steel component.
This patent application is currently assigned to Daimler AG. The applicant listed for this patent is DAIMLER AG. Invention is credited to Peter FEUSER, Bohuslav MASEK, Thomas SCHWEIKER.
Application Number | 20160145707 14/900588 |
Document ID | / |
Family ID | 50736038 |
Filed Date | 2016-05-26 |
United States Patent
Application |
20160145707 |
Kind Code |
A1 |
FEUSER; Peter ; et
al. |
May 26, 2016 |
Process and Installation for Producing a Press-Hardened Sheet Steel
Component
Abstract
A method and a system for producing a press-hardened sheet steel
component is disclosed. The method includes: a) heating of a
component blank formed from a hot-formable steel material at least
to the austenitising temperature of the steel material by a heating
device; b) hot forming of the component blank by a forming tool; c)
cooling of the component blank in the forming tool to a temperature
above the material-specific martensite finish temperature; d)
bringing of the component blank from the forming tool to a warming
device; and e) annealing of the component Hank, stabilizing the
austenite in the component blank by the warming device. The
component blank is brought directly from the forming tool to the
waning device, preventing a cooling of the component Hank to less
than the material-specific martensite finish temperature.
Inventors: |
FEUSER; Peter;
(Unterensingen, DE) ; MASEK; Bohuslav; (Kaznjov,
CZ) ; SCHWEIKER; Thomas; (Fellbach, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DAIMLER AG |
Stuttgart |
|
DE |
|
|
Assignee: |
Daimler AG
Stuttgart
DE
|
Family ID: |
50736038 |
Appl. No.: |
14/900588 |
Filed: |
May 17, 2014 |
PCT Filed: |
May 17, 2014 |
PCT NO: |
PCT/EP2014/001337 |
371 Date: |
December 21, 2015 |
Current U.S.
Class: |
148/653 ;
266/259 |
Current CPC
Class: |
C22C 38/002 20130101;
C21D 9/46 20130101; C21D 6/008 20130101; C21D 8/0452 20130101; C21D
7/13 20130101; C22C 38/001 20130101; C22C 38/32 20130101; C22C
38/06 20130101; C21D 8/0447 20130101; C21D 8/0221 20130101; C21D
8/0205 20130101; C21D 6/002 20130101; C21D 1/673 20130101; C22C
38/28 20130101; C22C 38/02 20130101; C22C 38/38 20130101; C22C
38/34 20130101; C22C 38/04 20130101; C21D 6/005 20130101; C21D 1/06
20130101 |
International
Class: |
C21D 9/46 20060101
C21D009/46; C21D 6/00 20060101 C21D006/00; C21D 1/06 20060101
C21D001/06; C21D 1/673 20060101 C21D001/673; C22C 38/38 20060101
C22C038/38; C22C 38/00 20060101 C22C038/00; C22C 38/32 20060101
C22C038/32; C22C 38/28 20060101 C22C038/28; C22C 38/06 20060101
C22C038/06; C22C 38/04 20060101 C22C038/04; C22C 38/02 20060101
C22C038/02; C21D 8/02 20060101 C21D008/02; C22C 38/34 20060101
C22C038/34 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 28, 2013 |
DE |
10 2013 010 946.9 |
Claims
1-6. (canceled)
7. A method for producing a press-hardened sheet steel component,
comprising the steps of: a) heating of a component blank formed
from a hot-formable steel material at least to an austenitising
temperature of the steel material by a heating device; b) hot
forming of the component blank by a forming tool; c) cooling of the
component blank in the forming tool to a temperature above a
material-specific martensite finish temperature; d) bringing the
component blank from the forming tool to a warming device; and e)
annealing of the component blank by the warming device which
stabilizes an austenite in the component blank; wherein the
component blank is brought directly from the forming tool to the
warming device preventing a cooling of the component blank to less
than the material-specific martensite finish temperature.
8. The method according to claim 7, wherein the component blank is
quenched in step e) in the forming tool to a temperature in a range
from 200.degree. C. to 500.degree. C. inclusive.
9. The method according to claim 7, wherein the component blank is
heated in step a) to a temperature between 800.degree. C. and
1000.degree. C.
10. The method according to claim 7, wherein the steel material is
an alloy having: 0.2 to 0.5% by weight carbon; 0.5 to 2.9% by
weight silicon; 0.7 to 4.1% by weight manganese; up to 0.1% by
weight phosphorous; up to 0.1% by weight sulphur; 0.0001 to 0.5% by
weight aluminum; 0.1 to 1.5% by weight chromium; 0.001 to 0.2% by
weight titanium; 0.001 to 0.03% by weight boron; and up to 0.025%
by weight nitrogen.
11. The method according to claim 7, wherein the warming device
heats the component blank in step e) relative to a temperature to
which the component blank is cooled in step c).
12. A system for producing a press-hardened sheet steel component,
comprising: a heating device, wherein the heating device heats a
component blank formed from a hot-formable steel material at least
to an austenitising temperature of the steel material; a forming
tool, wherein the component blank is hot formed by the forming tool
after the heating device heats the component blank and wherein the
forming tool cools the component blank to a temperature not below
200.degree. C. in the forming tool after the component blank is hot
formed; and a warming device, wherein the component blank is
annealed by the warming device to stabilize an austenite in the
component blank after the forming tool cools the component blank;
wherein the warming device is connected directly to the forming
tool such that the component blank is transferable directly from
the forming tool to the warming device to prevent a cooling of the
component blank to less than 200.degree. C.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
[0001] The invention relates to a method to produce a
press-hardened sheet steel component as well as a system to produce
such a press-hardened sheet steel component.
[0002] From the mass production of motor vehicles, in particular
passenger vehicles, the use of hot-formed components made from the
material 22MnB5 is sufficiently known. Such hot-formed components
made from hot-formable steel, in particular from 22MnB5, are
installed at the present time internationally and across
manufacturers in quantities of more than 100 million pieces per
year. Press-hardened sheet steel components are used in bodies of
motor vehicles which, in the event of an accident, are to have a
high stability and no or only very slight deformations.
[0003] However, the relatively low elongation at break of the
press-hardened components made from 22MnB5, which, for example,
lies in a range from 5 to 7%, is critical here. Therefore, kinetic
energy or accident energy can only be dissipated in very low
quantities by plastic deformation of the press-hardened components.
An overloading of the components can therefore, for example, lead
to tearing of the respective component or to a failure of this.
[0004] Therefore, for vehicle applications with requirements for a
particularly high deformation capability, completely hardened
components made from 22MnB5 cannot be used. At the current time,
alternatives to this are hot-formed components made from
microalloyed steel or from tailored welded blanks with regions made
from microalloyed steel which is able to be press hardened. The low
strength of the microalloyed steel after the hot-forming is,
however, disadvantageous in this approach. Therefore, the strength
after the hot forming amounts, for example, to only approximately
600 megapascals. Therefore, greater sheet thicknesses are required
in comparison to stronger materials with similar ductility.
[0005] Sheet or sheet steel components which have a high elongation
or elongation at break of 10% or more--measured in conformity with
ISO 6892-1--as well as a high strength, for example in a range from
1,200 to 2,000 megapascals inclusive, are desirable for vehicle
applications. Due to such a high elongation or elongation at break
and due to the high strength, such components would have very good
accident properties and are suggested for the implementation of
shell constructions in light-weight construction, in particular in
the field of passenger motor vehicles and commercial vehicles. Such
mechanical properties would enable a clearly greater absorption of
impact energy in the event of an accident, whereby a particularly
high passenger protection would result. At the same time, however,
the achievement of only a low carbon content is desirable in
comparison to components of forging, in order to ensure
weldability.
[0006] A practical development of such sheet steel components was
previously not possible (or only with a very high expenditure) due
to the unavailability of corresponding semi-finished products or
component blanks and system techniques for the processing of the
components.
[0007] US 2012/0273096 A1 discloses a device and a method to
produce a press-hardened sheet steel component, wherein a component
blank formed from a hot-formable steel material, from which
component blank the sheet steel component is produced, is heated at
least to the austenitising temperature of the steel material by
means of a heating device. Then the component blank is hot formed
by means of a forming tool. Then the component blank is cooled in
one component region to at least 200.degree. Celsius in the forming
tool, wherein a different component region is kept at a temperature
above 200.degree. Celsius by tool measures. In a further step, the
component blank is brought from the forming tool to a warming
device. Finally, the component blank is annealed by stabilizing the
austenite by means of the warming device.
[0008] The processing route proposed in US 2012/0273096 A1 in
combination with the proposed tool, however, does not represent a
solution to the problem described at the beginning concerning the
production of a homogenous component with particularly high
elongation as well as, at the same time, particularly high
strength. In particular, such component regions which are quenched
according to US 2012/0273096 A1 to a temperature below 200.degree.
C. have a very high strength on the finished part in combination
with a very low elongation at break of less than 10%. It is
additionally disadvantageous in US 2012/0273096 A1 that tool
regions must be warmed to 550.degree. C. in order to cause an
increase of the ductility in partial regions by bainitic or
perlitic ferritic phase transformations. Such a tool temperature
has the consequence that specific and comparably expensive tool
materials must be used. Besides the costs for the heat energy, a
further disadvantage exists in the extended cycle time for the
production of such a component. As the bainitic and/or perlitic
ferritic phase transformations clearly proceed more slowly in
comparison to martensitic transformation, the dwell time of the
component in the tool is extended. The cycle time is reduced by
exactly this proportion, which causes additional costs.
[0009] It is therefore the object of the present invention to
further develop a method and a system of the type referred to at
the beginning in such a way that press-hardened sheet steel
components having particularly high ductility and at the same time
particularly high strength can be produced in a simple, time- and
cost-effective manner.
[0010] In order to create a method, by means of which
press-hardened components can be produced having a particularly
high ductility and, at the same time, having a particularly high
strength in a time- and cost-effective manner, it is provided in
the method according to the invention that the component blank is
brought directly from the forming tool to the warming device,
preventing a cooling of the component blank to less than the
martensite finish temperature Mf, preferably to less than
200.degree. Celsius. Due to this direct bringing or due to the
direct transfer from the forming tool to or into the warming device
for annealing, an excessive cooling of the component blank can be
prevented. Due to very high cooling rates during forming, i.e.
during press-hardening of the component with an extremely quick
transfer into an isothermal holding phase at defined temperatures,
the transfer from the hot forming tool into the warming device for
annealing and the prevention of the cooling of the component blank
to less than 200.degree. Celsius plays an important role in order
to be able to produce press-hardened components having a high
ductility and a high strength in the scope of mass production in a
cost-effective manner. This is achievable by means of the method
according to the invention such that press-hardened components
having a high ductility, for example having an elongation at break
of 10% or more, as well as having a high strength, for example
having a strength in a range from 1,200 megapascals to 2,000
megapascals inclusive can be produced in a time- and cost-effective
manner. In particular, an elongation at break in a range from 10%
to 20% inclusive can be achieved. As a consequence of the high
elongation at break or the high ductility, the press-hardened sheet
steel components which are able to be produced by means of the
method according to the invention have a very high energy
absorption capability as a consequence of plastic deformation, such
that they, for example in the event of an accident of a motor
vehicle, can convert a particular high amount of impact energy into
deformation energy. At the same time, the press-hardened sheet
steel components have an improved crash robustness due to the
improved ductility, from which a particularly advantageous accident
behavior results to achieve very good passenger protection. In
comparison to components produced in another way, for example by
roll forming of martensite phase steels, an improved passenger
protection can therefore be achieved with the same or even lower
individual part weight. Compared to hot-formed components made from
22MnB5 and in particular from microalloyed steel, the wall
thickness can be further reduced such that press-hardened sheet
steel components can be implemented having a very low wall
thickness and therefore having a very low weight.
[0011] In comparison to conventional sheet steel components, the
method according to the invention enables a further increase of the
strength by the use of martensitic steel. The usual martensitic
structure is the hardest structure variant for steels. At the same
time, a purely martensitic structure is very brittle and, depending
on the carbon content, only enables a low deformation, such that
elongation values or elongation at break values usually lie below
7%.
[0012] The invention is therefore based on the idea and the
knowledge that for an increase of the elongation or elongation at
break, it is required to reduce the tension between the martensitic
needles and thereby to achieve better conditions for plastic
behavior of the sheet steel components. A possibility for this
consists in forming thin austenitic foils between the martensitic
needles. This is, for example, technically possible due to an
incomplete conversion from the austenitic phase to the martensite.
In the case of an interruption in the cooling above the so-called
martensite finish temperature Mf, the austenite converts into
martensite, but a small proportion of the austenite remains. The
martensite finish temperature Mf is therein the temperature at
which the greatest part of the martensite conversion is concluded.
If, directly after this, the structure of the sheet steel component
or of the component blank is kept at a slightly increased
temperature, the carbon migrates from the supersaturated martensite
by diffusion into the austenite. In order to achieve this, the
formed component blank is transferred directly from the hot forming
tool in a warming direction, wherein a cooling of the component
blank to less than 200.degree. Celsius is prevented. The austenite
can hereby be particularly well stabilized as, due to the direct
bringing, residual heat from the hot forming process can be used
during annealing. Due to the direct transfer of the component blank
from the hot forming tool into the warming device (used to anneal
the component), the austenite in the component blank is stabilized
and also remains in the component structure after a further cooling
of the component blank or of the completely produced sheet steel
component to room temperature. This so-called residual austenite
reduces the tension between the martensite needles and causes the
structure to have substantially better elongation or ductility
compared to the martensite at the same time as high strengths. The
use of a steel alloy having the following alloy elements has been
shown to be particularly advantageous as a starting material for
the production of the component blank: [0013] carbon (C) in a range
from 0.2 to 0.5 percent by weight (% by weight) inclusive, [0014]
silicon (Si) in a range from 0.5 to 2.9% by weight inclusive,
[0015] manganese in a range from 0.7 to 4.1% by weight inclusive,
[0016] up to 0.1% by weight phosphorous (P), [0017] up to 0.1% by
weight sulphur (S), [0018] aluminum (Al) in a range from 0.001 to
0.5% by weight inclusive, [0019] chromium (Cr) in a range from 0.1
to 1.5% by weight inclusive, [0020] titanium (Ti) in a range from
0.01 to 0.2% by weight inclusive, [0021] boron (B) in a range from
0.01 to 0.03% by weight inclusive, [0022] and up to 0.025% by
weight nitrogen (N).
[0023] A system is included in the invention, wherein it is
provided according to the invention that the warming device is
indirectly connected to the forming tool such that the component
blank is able to be brought directly from the forming tool to the,
and in particular into, the warming device, preventing a cooling of
the component blank to less than 200.degree. Celsius. Advantageous
embodiments of the method according to the invention can be viewed
as advantageous embodiments of the system according to the
invention and vice versa. Press-hardened sheet steel components
having a particularly high strength and at the same time having a
particularly high ductility can be produced in a simple, time- and
cost-effective manner, in particular in the scope of mass
production, by means of the system according to the invention. In
particular it is possible to prevent a particularly high number of
pieces with only a low level of rejection, as an excessive cooling
of the component blank is prevented after the cooling in the
forming tool and before the annealing.
[0024] Compared to conventional press-hardening, for example of
components made from 22MnB5, the warming device is provided as a
further heating device to stabilize the residual austenite. The
warming device is preferably a roller hearth furnace or walking
beam furnace.
[0025] The forming tool is, in the method, preferably able to
anneal to temperatures in a range from 25.degree. to 500.degree.
Celsius inclusive in order to thereby control and targetedly adjust
the quenching temperature and therefore the residual austenite
content of the component blank functioning as a semi-finished
product. During transfer from the forming tool to or into the
warming device, the cooling of the component blank by measures such
as radiant heaters and/or deflector plates can be prevented or kept
low such that a cooling of the component blank to less than
200.degree. Celsius is prevented.
[0026] In the warming device, the component blank(s) can be
supported on goods carriers, by means of which, for example, the
component blank or the component blanks is or are conveyed through
the heating device. The goods carrier can thereby preferably
counteract a thermal distortion of the component.
[0027] The following steel alloys have proved to be particularly
advantageous as materials for the component blank and therefore for
the sheet steel component or sheet component:
[0028] (0.25-0.35)% by weight C+(0.5-0.7)% by weight Mn+(1.5-2.5)%
by weight Si+(0.5-1.5)% by weight Cr+(0.001-0.008)% by weight
B+max. 0.01% by weight N+(0.015-0.08) % by weight Al+(0.001-0.009)%
by weight Ti+(0.010-0.025)% by weight P+max. 0.010% by weight
S,
[0029] or
[0030] (0.25-0.35)% by weight C+(1.2-1.8)% by weight Mn+(1.0-2.0)%
by weight Si+(0.3-1.0) % by weight Cr+(0.001-0.008)% by weight
B+max. 0.01% by weight N+(0.015-0.08)% by weight Al+(0.001-0.009)%
by weight Ti+(0.010-0.025)% by weight P+max. 0.010% by weight
S,
[0031] or
[0032] (0.25-0.35)% by weight C+(1.2-1.8)% by weight Mn+(1.0-2.0) %
by weight Si+(0.10-0.30)% by weight Cr+(0.001-0.008)% by weight
B+max. 0.01% by weight N+(0.015-0.08)% by weight Al+(0.001-0.009)%
by weight Ti+(0.010-0.025)% by weight P+max. 0.010% by weight
S.
[0033] Further advantages, features and details of the invention
result from the following description of preferred exemplary
embodiments as well as by means of the drawings:
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] FIG. 1 is a schematic depiction of a method and a system to
produce press-hardened sheet steel components, having a forming
tool to form a component blank and having a warming device to
anneal the component blank, which is brought from the forming tool
into the warming device, wherein the warming device connects
directly to the forming tool such that the component blank is
brought directly from the forming tool to the warming device,
preventing a cooling of the component blank to less than the
martensite finish temperature, preferably to less than 200.degree.
Celsius;
[0035] FIG. 2 is a schematic time-temperature course of the
component blank in the scope of the implementation of the method
according to a first embodiment;
[0036] FIG. 3 is a schematic depiction of the system according to a
second embodiment;
[0037] FIG. 4 is a schematic depiction of the system according to a
third embodiment; and
[0038] FIG. 5 is a schematic time-temperature course of the
component blank in the scope of the implementation of the method
according to its second embodiment.
DETAILED DESCRIPTION OF THE DRAWINGS
[0039] In the Figures, identical or functionally identical elements
are provided with the same reference numeral.
[0040] FIG. 1 shows, in a schematic depiction, the sequence of a
method to produce a press-hardened sheet steel component in the
form of a sheet component made from a component blank which is
formed from a hot-formable steel material. The component blank is
also referred to as a semi-finished product. For reasons of
clarity, the method is described by means of the production of a
sheet steel component or sheet component made from a component
blank. The method is, however, readily particularly well suited for
the mass production of such press-hardened sheet steel
components.
[0041] To implement the method, a system referred to in FIG. 1 as a
whole with 10 is provided. By means of the system 10, the component
blank undergoes the method, wherein the component blank is heated
and cooled in the course of the method. This heating and cooling is
particularly well recognizable from FIG. 2. FIG. 2 shows a diagram
12 in which a time-temperature course of the component blank is
recorded. The time t is laid out on the abscissa 16 of the diagram
12, wherein the temperature is laid out on the ordinate 18 of the
diagram 16. It is therefore recognizable by means of the
time-temperature course at which temperature the component blank is
heated or cooled respectively and how long the component blank is
held, if necessary, at a respective temperature.
[0042] As is recognizable from FIG. 1, the system 10 includes a
heating device 20, for example in the form of a furnace, in
particular a rolling hearth furnace, wherein the component blank is
brought into the heating device 20 and if necessary is conveyed
through this. As is recognizable when viewed together with FIG. 2,
in a first step S1 of the method, the component blank is heated at
least to, preferably above, the austenitising temperature of the
steel material from which the component blank is formed by means of
the heating device 20. In other words, the heating device 20 serves
to austenitise the component blank in the first step S1.
[0043] The component blank can, for example, be present in the form
of a plate.
[0044] As is recognizable from FIG. 2, the component blank is
heated by means of the heating device 20 to a temperature above
900.degree. Celsius, wherein in FIG. 2, the temperature of
900.degree. Celsius is marked by means of a dashed line 22.
[0045] The system 10 furthermore comprises a forming tool 24 which,
for example, is integrated into a hydraulic press. The heated
component blank is brought, in particular conveyed, from the
heating device 20 or from this to the forming tool 24 or into this,
and is hot formed by means of the forming tool 24 in a second step
S2 of the method. In the course of this hot forming and in the
subsequent maintenance phase, the hot-formed component blank is
cooled in the forming tool 24, however not cooled below 200.degree.
Celsius (step S3). It can therefore be provided that the component
blank is cooled to a temperature between 200.degree. Celsius and
500.degree. Celsius. In other words, the component blank is cooled
in such a way that the component temperature is not less than
200.degree. Celsius and not more than 500.degree. Celsius after the
forming.
[0046] The system 10 additionally comprises a further heating
device in the form of a warming device 26 which can be formed as a
furnace. The heating device 20 and/or the warming device 26 can be
a rolling hearth furnace, a lifting beam furnace, a chain conveyor
furnace or a rotary hearth furnace. However, the use of other
heating devices is also conceivable. For example, other
possibilities such as contact plate heating, heating by radiant
heaters, inductive heating, conductive heating, infrared heating
are likewise possible in order to heat up or to heat the component
blank. In particular in the case of the use of furnaces, the
warming device 26 can be heated by exhaust heat of the heating
device 20.
[0047] After the cooling of the component blank in the forming tool
24 (step S3), the component blank is brought from the forming tool
24 to or into the warming device 26 (step 24). The warming device
26 therein connects directly to the forming tool 24 such that the
component blank is brought directly from the forming tool 24 to or
into the warming device 26, preventing a cooling of the component
blank to less than 200.degree. Celsius. This transfer can thereby
preferably be carried out by multi-axle industry robots or feeder
systems.
[0048] The warming device 26 can in particular be designed as a
continuous furnace such that the component blank is conveyed
through the warming device 26. The component blank is annealed by
means of the warming device 26 in a fifth step S5 of the method,
stabilizing the austenite in the structure of the component blank.
In order to prevent intake of atomic hydrogen, the dew point in the
heating device and in the warming device is preferable controlled
and adjusted to values smaller than 5.degree. C. Preferably to
values smaller than -5.degree. C.
[0049] As is by the warming device from FIG. 2, the component blank
is heated again slightly in the scope of the annealing from the
temperature to which the component blank was cooled in the third
step S3. Presently, the component blank is cooled to 250.degree.
Celsius, wherein it is heated in the fifth step S5 to more than
200.degree. Celsius and less than 500.degree. Celsius and is held
in this temperature range for a time period between 2 and 15
minutes.
[0050] After the annealing, the component blank is brought from the
warming device 26 to or into a cutting device 28 of the system 10,
wherein the component blank, in particular in the form of a plate,
is cut by means of the cutting device 28 and is cooled in this to
room temperature (sixth step S6). Finally, the component blank is
brought from the cutting device 28 in the scope of a chain link to
a final trimming device 30 and is finally trimmed and cleaned by
means of this in a seventh step S7 of the method.
[0051] The time-temperature course 14 illustrates the method
according to a first exemplary embodiment, wherein other
temperatures can also be adjustable.
[0052] Therefore, direct or indirect press-hardening of the
component blank is able to be depicted by means of the method,
which is preferably formed from a boron-manganese steel. The
component blank can therein be uncoated or coated. Preferably the
component blank is aluminized or galvanized. The sheet thickness of
the component blank can lie in a range from 0.5 millimetres to 3
millimetres inclusive. Press-hardened sheet steel components having
a high elongation at break and therefore ductility as well as at
the same time having a very high strength are able to be produced
in a cost-effective as well as time-effective manner.
[0053] FIG. 3 shows the system 10 according to a second embodiment.
A so-called passage direction of the component blank is illustrated
in FIG. 3 by directional arrows, in which the component blank
passes through the system 10.
[0054] The system 10 according to the second exemplary embodiment
includes a receiving roller bed 32 arranged in the passage
direction before the heating device 20 for austenitising, by means
of which receiving roller bed 32 the component blank is conveyed
into the heating device 20. An emitting roller bed 34 connects to
the heating device 20, by means of which emitting roller bed 34 the
component blank is conveyed from the heating device 20. The
receiving roller bed 32 and the emitting roller bed 34 can therein
be components of the heating device 20.
[0055] Furthermore, the system 10 according to the second exemplary
embodiment includes a receiving roller bed 36, by means of which
the component blank is conveyed into the warming device 26 after
the cooling, i.e. after the forming tool 24. A further emitting
roller bed 36 connects to the warming device 26, by means of which
the component blank is conveyed from the warming device 26 after
the annealing. The receiving roller bed 36 and the emitting roller
bed 38 can also be components of the warming device 26. Therefore,
the component blank can be brought from the forming tool 24 into
the warming device 26 for austenite stabilization directly after
the cooling and without being cooled to less than 200.degree.
Celsius.
[0056] FIG. 4 shows the system 10 according to a third embodiment
in which further presses 40, 42, 44 are connected to the emitting
roller bed 38 to process the component blank. The component blank
is, for example, perforated by means of the press 40. The component
blank is trimmed by means of the press 42, wherein the component
bank is trimmed a further time by means of the press 44.
[0057] FIG. 5 shows the time-temperature course 14 for the method
according to a second exemplary embodiment. In the first step S1,
the component blank is heated to the austenitising temperature
referred to with A with a heating rate T.sub.target1 for the
austenitising and is kept at the austenitising temperature A during
an austenitising time B. A cooling rate is referred to with
T.sub.target2 with which the component is cooled during and/or
after its forming, i.e. during the second step S2 and/or during the
third step S3, wherein a critical cooling rate for the development
of martensite is marked with T.sub.crit-MS.
[0058] After the forming and after the cooling, the component blank
is kept in the forming tool 24 at a maintenance temperature C
during a maintenance time D1. Subsequently, the component blank is
transferred from the forming tool 24 into the warming device 26,
wherein this transfer lasts for a transfer time D2. During this
transfer time D2 it is prevented that the component blank cools to
less than 200.degree. Celsius.
[0059] The component blank is heated to an annealing temperature E
in the warming device 26 with a heating rate T.sub.target3 and is
kept at the annealing temperature E during an annealing time F.
After the annealing, the component blank is cooled with a cooling
rate T.sub.target4, for example to room temperature.
* * * * *