U.S. patent application number 13/533208 was filed with the patent office on 2013-10-31 for process of and device for producing metal blanks with different thicknesses.
This patent application is currently assigned to MUHR UND BENDER KG. The applicant listed for this patent is Andreas Elvenkemper, Andreas Hauger. Invention is credited to Andreas Elvenkemper, Andreas Hauger.
Application Number | 20130283881 13/533208 |
Document ID | / |
Family ID | 46395522 |
Filed Date | 2013-10-31 |
United States Patent
Application |
20130283881 |
Kind Code |
A1 |
Hauger; Andreas ; et
al. |
October 31, 2013 |
Process of and Device For Producing Metal Blanks With Different
Thicknesses
Abstract
A process of producing metal blanks with different thicknesses
from a metallic material includes: producing sheet metal blanks
from a band material; changing the temperature of the metal blanks
such that, in the blanks, a plurality of regions is produced with
different temperatures; rolling the metal blanks having regions
with different temperatures in a rolling tool with a roll gap
setting, wherein the roll gap setting is kept constant during the
operation of rolling the metal blanks, wherein, due to the regions
with different temperatures in the sheet metal blanks, portions are
produced with different thicknesses. The invention also relates to
a suitable device for producing sheet metal blanks with different
thicknesses from a metallic material.
Inventors: |
Hauger; Andreas; (Attendorn,
DE) ; Elvenkemper; Andreas; (Gummersbach,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hauger; Andreas
Elvenkemper; Andreas |
Attendorn
Gummersbach |
|
DE
DE |
|
|
Assignee: |
MUHR UND BENDER KG
Attendorn
DE
|
Family ID: |
46395522 |
Appl. No.: |
13/533208 |
Filed: |
June 26, 2012 |
Current U.S.
Class: |
72/201 ;
72/200 |
Current CPC
Class: |
B21B 37/74 20130101;
B21B 2261/02 20130101; B21B 1/26 20130101; B21B 37/16 20130101 |
Class at
Publication: |
72/201 ;
72/200 |
International
Class: |
B21B 1/26 20060101
B21B001/26 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 27, 2011 |
DE |
102011051345.0 |
Claims
1. A process of producing metal blanks with different thicknesses
from a metallic material, comprising the following process stages:
producing metal blanks from a band material; changing the
temperature of the metal blanks such that a plurality of regions
with different temperatures is generated in the metal blanks;
rolling the metal blanks having regions with different temperatures
in a rolling tool with a roll gap setting, wherein the roll gap
setting is kept constant during the operation of rolling the metal
blanks, wherein, due to the regions with different temperatures in
the metal blanks, portions are produced with different
thicknesses.
2. A process according to claim 1, wherein changing the temperature
is effected such that of the regions with different temperatures,
at least one region with a constant temperature and/or at least one
region with a variable temperature is produced transversely to the
rolling direction.
3. A process according to claim 1, wherein changing the temperature
in regions of the blanks is achieved by heating or cooling at least
one region of the sheet metal blank, more particularly by means of
at least one punch which is moved into contact with the metal
blank, so that the sheet metal blank at least substantially assumes
the temperature of the punch.
4. A process according to claim 1, wherein changing the temperature
in regions of the metal blanks is achieved by induction-heating of
at least one region of the metal blank, wherein the metal blanks
are guided through current-conducting rolls, wherein the regions
with different temperatures are generated by varying the power of
the current-conducting rolls while the metal blanks are being
guided through.
5. A process according to claim 1, wherein changing the temperature
in regions of the metal blanks is effected by cooling at least one
region of the metal blanks, wherein the metal blanks are heated
homogenously to a first temperature prior to being cooled in said
at least one region.
6. A process according to claim 1, wherein the metal blanks are
heated after having been rolled, more particularly normalized.
7. A process according to claim 1, wherein after having been
heated, the metal blanks are hot-formed.
8. A process according to claim 1, wherein the metal blanks are
made of steel material and, after changing the temperature,
comprise high temperature regions which always comprise a
temperature in excess of 500.degree. C., more particularly in
excess of 600.degree. C., during the subsequent process stages of
rolling and heat treatment up to the stage of being inserted into
the forming tool.
9. A device for producing metal blanks with different thicknesses
from a metallic material, for carrying out the process according to
claim 1, wherein the device comprises: a tool for producing metal
blanks from a band material; a temperature-changing tool by means
of which regions in the metal blanks can be produced with different
temperatures; a rolling tool with a constant roll gap setting, by
means of which the metal blanks having different temperature
regions can be rolled, so that, due to the different temperature
regions, portions with different thicknesses are produced in the
metal blanks.
10. A device according to claim 9, wherein the temperature-changing
tool comprises at least one punch which can be heated or
cooled.
11. A device according to claim 10, wherein the punch comprises
temperature controlling means, wherein the temperature controlling
means are configured such that the temperature in at least one
portion of the punch can be set individually.
12. A device according to claim 11, wherein the punch comprises
channels through which a cooling medium can flow in order to cool
the punch, wherein, in particular, the through-flow speed of the
cooling medium through the channels is controllable.
13. A device according to claim 9, wherein a heat treatment device
is arranged downstream the rolling tool and in which the metal
blanks can be normalized.
14. A device according to claim 13, wherein, furthermore, it
comprises a forming tool which is arranged downstream the heat
treatment system, more particularly a hot forming tool in which the
metal blanks can be formed and at least partially hardened.
Description
BACKGROUND OF THE INVENTION
[0001] The invention relates to a process of producing metal blanks
which, along their length, comprise different thicknesses.
[0002] From DE 197 04 300 A1 a process is known of producing sheet
metal blanks with different thicknesses by deforming an
approximately uniformly thick starting material. The starting
material is first heated in an induction heating device to a
temperature above the re-crystallization temperature. Subsequently,
the starting material is subjected to a process of partial rolling
deformation wherein the thicknesses vary in the rolling
direction.
[0003] Document DE 198 46 900 A1 proposes a process of and device
for producing a metal band. The differently thick regions of the
band are produced by hot rolling in that portions of the band,
prior to the hot rolling process, are set to a different
temperature by being cooled or heated. As a result, the band, in
its individual portions, as a result of the different temperature
settings, is provided with different flow stress values, while
experiencing different thickness reduction rates with the rolling
force substantially remaining constant.
[0004] The disadvantage of the processes in use at present is the
high expenditure involved in heating the coils and the complexity
of the roll stands for rolling the coils and sheet metal blanks
heated to different degrees in certain regions for the purpose of
producing different thicknesses in certain regions.
SUMMARY OF THE INVENTION
[0005] It is the object of the present invention to propose a
simplified process of producing metal blanks with different
thicknesses, which process permits specific regional changing of
temperature of sheet metal blanks and rolling the sheet metal
blanks by means of a simple and cost-effective roll stand to
different thicknesses in different regions.
[0006] The objective is achieved by a process of producing metal
blanks with different thicknesses from a metallic material, having
the following process stages: [0007] producing metal blanks from a
band material; changing the temperature of the metal blanks
regionally such that regions with different temperatures are
produced in the metal blanks; and [0008] rolling the metal blanks
having regions with different temperatures in a rolling tool with a
roll gap setting, wherein the roll gap setting is kept constant
during the operation of rolling the metal blanks wherein, due to
the different temperature regions in the metal blanks, portions are
produced with different thicknesses.
[0009] The advantage of the process with the given sequence of
individual process stages consists in that a regional change in
temperature results in different temperature zones. As a result of
the different temperature zones, the different regions of the metal
blanks comprise different flow resistance values. The hotter
regions have a lower flow resistance and are therefore rolled down
to a greater extent than cooler regions of the sheet metal blanks.
During the subsequent rolling operation portions with different
thickness are produced in the sheet metal blank, due to the
different flow resistance values. The regions which, prior to the
rolling operation, were heated to a greater extent, comprise, after
the rolling operation a smaller thickness than the regions heated
to a lesser extent. Overall, the inventive process ensures that by
setting suitable temperature zones for the metal blank in advance
of the rolling process, there are obtained optimum blank
thicknesses after the rolling process, which thicknesses are
adapted to the subsequent component requirements.
[0010] A metal blank is meant to be a sheet metal element which is
produced from a band material or a coil, respectively. This means
that the process stage of regionally changing the temperature of
the metal blank is preceded by the production of the metal blank
from a band material. It is understood that between cutting
individual blanks from the band material and the regional change in
temperature of the blank, other process stages can take place, for
instance a heat treatment process. For producing the metal blanks
from the band material or coil, any method can be applied, which
method depends on the end contour of the blank to be produced. For
example, the metal blanks can be produced by simply cutting to
lengths the band material into individual elements with at least
two parallel side edges or by cutting or punching individual
elements with individual circumferential contours out of the band
material. Said cut-out elements with individual circumferential
contours can also be referred to as profile cuts or contour
cuts.
[0011] The advantage of using metal blanks for regionally changing
the temperature consists in that it is also possible to generate
temperature gradients transversely to the direction of production
and to the subsequent direction of rolling, respectively. During
rolling, said temperature gradients lead to blank deformation which
is asymmetric with reference to the direction of rolling, which
would not be the case with band material. Thus, in an advantageous
way, there is achieved a maximum degree of flexibility as regards
the geometry of the sheet metal blank to be produced and,
respectively, of the end product to be produced from the blank.
[0012] The rolling operation which takes place after the blanks
have been cut from the band material takes place with a constant
roll gap. This means that when the blanks pass through the rolling
tool, the roll gap setting remains substantially constant,
preferably in an uncontrolled process. In this context, roll gap
refers to the roll opening, including an expansion step, at the
faces of contact of the material to be rolled with the rolls along
the rolling bale length. Expansion step refers to an increase in
the roll opening when the material to be rolled passes through;
this is due to an elongation, respectively compliance of parts of
the roll stand. In contrast to the roll gap, the rolling force can
change when the sheet metal blank passes through. The transitions
between the blank portions with different thicknesses occur as a
result of the temperature distribution in the blank and can be kept
very short by suitably regionally changing the temperature prior to
the rolling operation, in contrast to controlled roll stands. The
force/work requirements are greatly reduced as a result of the
temperature-dependent flow resistance, so that sheet metal blanks
with different plate thicknesses can be produced economically in
wide widths.
[0013] According to a preferred embodiment, the different
temperature regions are produced in accordance with the required
thicknesses of the sheet metal blank. In principle, the shape and
extension of the temperature regions in the longitudinal and
transverse direction can be selected such that, after the rolling
operation, the blank has the required thickness profile.
[0014] More particularly, according to a simple first embodiment,
it is proposed that of the regions with different temperatures, at
least one region, preferably a plurality of regions, are heated or
cooled to a constant temperature transversely to the direction of
rolling. Thus, the blank regions which are positioned side by side
in the longitudinal direction of the blank and which each comprise
a different temperature relative to the adjoining region, lead to a
change in the thickness of the blank in the longitudinal direction,
respectively in the rolling direction of the blank during the
rolling process. The number and distribution of the regions with
different temperatures, respectively the temperature profile can,
in principle, be freely selected depending on the required
thickness profile of the blank, with the number, more particularly,
ranging between two and six.
[0015] According to a second possibility it is proposed that, at
least one region, if necessary also several regions, are subjected
to a variable temperature transversely to the direction of rolling.
In this way it is ensured that, during the subsequent rolling
process, the sheet metal blank experiences a respective change in
thickness transversely to the direction of rolling. In this case,
too, the number and distribution of the regions with different
temperatures can be set as a function of the required thickness
profile.
[0016] According to a third possibility, which constitutes a
combination of the first and of the second possibility, it is
possible to produce temperature regions which extend at a uniform
temperature transversely to the direction of rolling, as well as
temperature regions which comprise an additional temperature
gradient transversely to the direction of rolling. The latter third
possibility offers a maximum degree of flexibility in respect of
the later thicknesses of the sheet metal blank after the rolling
process in the longitudinal and transverse directions. More
particularly, it is possible to achieve a three-dimensional
thickness structure of the blank.
[0017] According to a first embodiment, the regional change in
temperature starts from a homogenous first temperature of the sheet
metal blank by heating at least one region of the blank to a higher
second temperature. In this regard, homogenous first temperature
means that prior to the regional change in temperature, the sheet
metal blank comprises the same temperature everywhere. "At least
one region" means that one region or several regions are heated to
an individual temperature. If exactly one region is heated, there
are obtained two regions whose temperatures differ from one
another. The temperature level to which the sheet metal blank is
heated essentially depends on the material and, respectively, on
the strength of the material. If a steel material is used, then at
least one region of the sheet metal blank is preferably heated to a
second temperature of 400.degree. C. to 1250.degree. C., more
particularly to 600.degree. C. to 800.degree. C. If an aluminum
material is used, the sheet metal blank is preferably heated to a
second temperature of 150.degree. C. to 500.degree. C.
[0018] The process of regionally heating the sheet metal blank can
be carried out for example by a punch which is moved into contact
with the blank such that the blank at least approximately assumes
the temperature of the punch, in which case the punch would be
provided in the form of a heating punch which preferably comprises
differently controlled temperature zones. Alternatively, regionally
heating can be effected by induction by one or several
current-conducting rolls through which the blanks are guided, and
more particularly it is proposed that the different temperature
zones of the sheet metal blanks are produced by varying the power
of the current-conducting rolls when the sheet meal blanks pass
through.
[0019] According to a second embodiment, the regional change in
temperature, while starting from a homogenous first temperature of
the blank, is effected by cooling. For this purpose, the metal
blanks are initially heated homogenously to a higher first
temperature prior to the temperature of certain regions of the
metal blank being varied. Subsequently, the regional change in
temperature takes place by cooling at least one region of the blank
to a lower second temperature. Because at least one region is
cooled, there occur at least two regions whose temperatures differ
from one another. It is understood that it is also possible to cool
any number of regions to an individual temperature. When a steel
material is used, the homogenous first temperature to which the
sheet metal blank is heated ranges between 950.degree. C. and
1250.degree. C. During the subsequent regional process of cooling
the regions, the temperatures are set to lower second temperatures
which, more particularly, range between 400.degree. C. and
950.degree. C., preferably between 600.degree. C. and 800.degree.
C.
[0020] The regional cooling of the metal blanks is preferably
carried out by a punch which is brought into contact with the blank
such that the blank at least approximately assumes the temperature
of the punch, in which case the punch would be provided in the form
of a cooling punch. The punch can preferably comprise individually
controllable cooling zones, so that the temperature zones of the
sheet metal blank can be adapted individually to the thickness
profile to be produced at a later state.
[0021] According to a preferred process which applies to both
embodiments, i.e. both to partial heating and also partial cooling,
the blanks are subjected to a heat treatment, preferably to
normalizing, after having been rolled. For this purpose, the
blanks, if a steel material is used, are preferably heated to a
temperature of 950.degree. C. and 1250.degree. C. and if an
aluminum material is used to a temperature of 150.degree. C. and
550.degree. C. Heating preferably takes place in a heating furnace.
This type of heat treatment ensures a uniform structure in the
sheet metal blank across all portions of different thicknesses.
[0022] After completion of the heat treatment, the sheet metal
blank is processed further into an end product. The subsequent
process stage preferably comprises a deformation process such as
deep drawing. Subsequently, the component can be hardened or
subsequently quenched and tempered. It is particularly advantageous
to use a hot forming process in the course of which the sheet metal
blank is formed in a hot forming tool into the proposed shape and
hardened. In connection with the hot forming process it is also
conceivable that only partial regions of the hot forming tool are
cooled, so that only those partial regions of the tool are hardened
which come into contact with the cooled partial regions of the hot
forming tool. The remaining partial portions of the tool retain
their low hardness level. For hot forming with simultaneous
hardening it is necessary to provide a cooled forming tool which,
in the blank portions to be hardened and, respectively, of the end
product to be produced therefrom, comprises cooled regions or,
optionally, is fully cooled.
[0023] Another solution to the above-mentioned objectives consists
in a device for producing metal blanks with different thicknesses
from a metallic material in accordance with the inventive process
with one or several of the above mentioned process stages, wherein
the device, in the sequence as given, comprises the following: a
tool for separating sheet metal blanks from a band material; a
temperature-changing tool by means of which regions with different
temperatures can be produced in the metal blanks; and a rolling
tool with a constant roll gap setting by means of which the
partially temperature-changed blanks can be rolled, so that, due to
the different temperature regions, portions with different
thicknesses can be produced in the sheet metal blanks.
[0024] The inventive device has the same advantages as the process
so that, to that extent, reference can be made to the above
description. More particularly, the constant roll gap setting of
the rolling tool, preferably in an uncontrolled process, is
advantageous in respect of a simple and effective production
process. The change in the material thickness is achieved entirely
as a result of the different roll expansion steps of the rolling
tool while the blanks pass through, which, in turn, is due to the
different flow resistance values in the blank material and to the
different temperatures of the material in certain regions. Because
a tool for separating band material into blanks is disposed
upstream the temperature-changing tool, there is achieved a maximum
degree of flexibility for the geometry of the sheet metal blank to
be produced and for the end product to be produced therefrom. It is
thus also possible to produce sheet metal blanks and products with
a variable thickness profile transversely to the direction of
rolling.
[0025] According to a preferred embodiment, the
temperature-changing tool comprises at least one punch which can be
heated or cooled. The punch is used to partially increase or
decrease the temperature of the sheet metal blank in one partial
region or several partial regions relative to other regions. The
size and shape of the punch preferably depends on the temperature
zones to be produced and on the thickness profile of the blank to
be produced in connection with the rolling process. The punch
preferably comprises a plurality of regions in which the
temperature can be set individually. It is thus possible to produce
different temperatures zones on the blank with one single
punch.
[0026] In a first possibility according to which the punch is
provided in the form of a heating punch, the punch is preferably
provided with heating wires which can heat the punch at least in
partial regions.
[0027] In a second possibility in the case of which the punch is
provided in the form of a cooling punch for partially cooling the
sheet metal blank, the punch preferably comprises channels through
which a cooling medium can flow in order to cool the punch. For
variably setting the different temperature zones in the blank it is
particularly advantageous if the through-flow speed of the cooling
medium through the channels can be controlled. In a preferred
embodiment, the punch is provided with a plurality of cooling
circuits through which the cooling medium flows. By individually
setting the through-flow speed of the cooling medium in every
single channel, it is possible, by means of one cooling punch, to
produce different temperature zones. It is thus possible, for
example, with one cooling punch to produce a first region with
600.degree., a second region with 750.degree. C. and a third region
with 900.degree. C. in the sheet metal blank. The same does, of
course, apply analogously to a heating punch according to the first
possibility which, accordingly, can comprise different heating
zones.
[0028] According to a preferred embodiment, which applies to both
possibilities, the at least one punch is produced from a metallic
material with a good thermal conductivity, more particularly from
copper or a copper containing material.
[0029] The rolling tool is preferably designed in such a way that
the gap width is constant during the rolling operation. As a
result, the force/work requirements can be kept very low, which
advantageously affects production costs and production times.
However, it is understood that it is also possible to use a tool
with flexible rolls by means of which a particularly high degree of
flexibility is achieved with reference to the thickness profile of
the blanks to be produced.
[0030] According to a preferred embodiment, the device furthermore
comprises a heat treatment facility which follows the rolling tool.
In the heat treatment facility which, more particularly, can be
provided in the form of a heating furnace, the sheet metal blanks
can be heat-treated, preferably normalized.
[0031] According to an advantageous further embodiment, the heat
treatment facility can be provided in the form of a forming tool
which is preferably provided as a hot forming tool in which the
sheet metal blanks can be formed and at least partially hardened.
The combination of changing the temperature of the blanks in
certain regions, of the subsequent rolling process, heating and hot
forming is particularly advantageous because it permits a very
efficient production of sheet metal blanks with variable
thicknesses along their length and width. The heat input into the
sheet metal blank during production, i.e. while the material passes
through the individual stations of the device can be kept low,
which, in turn, advantageously affects the production speed and
production costs. It is particularly advantageous if the sheet
metal blanks in those regions which, after the region-wise change
in temperature, comprise the highest temperatures always comprise a
temperature in excess of 500.degree. C., more particularly in
excess of 600.degree. C. for steel materials during the subsequent
process stages of rolling and heat treatment up to the point of
being inserted into the forming tool.
[0032] Various aspects of this invention will become apparent to
those skilled in the art from the following detailed description of
the preferred embodiment, when read in light of the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] FIG. 1 shows an inventive process for producing a sheet
metal blank with different thicknesses in a first embodiment:
[0034] a) with the individual process stages; [0035] b) the
temperature curve for two regions as a function of time.
[0036] FIG. 2 shows an inventive process for producing a sheet
metal blank with different thicknesses in a second embodiment:
[0037] a) with the individual process stages; [0038] b) the
temperature curve for two regions as a function of time.
[0039] FIG. 3, by way of example, shows a sheet metal blank
produced in accordance with a process and a device according to
FIG. 1 or FIG. 2 in a further embodiment: [0040] a) in a plan view
after the partial temperature treatment and prior to the rolling
process; [0041] b) a diagrammatic side view before the rolling
process; [0042] c) a diagrammatic side view after the rolling
process.
[0043] FIG. 4, by way of example, shows a sheet metal blank
produced in accordance with a process and a device according to
FIG. 1 or FIG. 2 in a further embodiment: [0044] a) in a plan view
after the partial temperature treatment and prior to the rolling
process; [0045] b) in a plan view after the rolling process; [0046]
c) a diagrammatic side view after the rolling process; [0047] d) in
a cross-sectional view after the rolling process through a portion
according to sectional line D-D of FIG. 4b).
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0048] FIG. 1 shows an inventive process for producing a sheet
metal blank 10. The sheet metal blank 10 is preferably produced
from a metallic material, for example from a steel material or
aluminum. It shows a process A.
[0049] "Metal blank 10", in this context, refers to a sheet metal
element which, more particularly, is produced from a band material,
respectively from a coil. The sheet metal blank can be produced by
simply cutting the band material into individual elements or by
cutting out or punching out individual elements from the band
material.
[0050] In process stage A1, the sheet metal blank 10 is treated by
a temperature-changing tool 30, with the blank 10 being given
various regions 11, 12, 21 which comprise different temperatures.
In the present example, the region 11 has a temperature of
800.degree. C., the second region 12 a temperature of 600.degree.
C. The transitional region 21 positioned between the first region
11 and the second region 12 comprises a variable temperature which
decreases from the first region 11 to the second region 12.
[0051] The temperature curve with a continuous line as shown in
FIG. 1b constitutes the temperature curve for the first region 11
as a function of time. It can be seen that the temperature,
starting from the starting temperature of 0.degree. C. initially
rises considerably until the target temperature T.sub.A1,11 of
800.degree. C. has been reached. Accordingly, the dashed line
constitutes the temperature curve for the second region 12. Here it
can also be been how the temperature rises as a function of time
until the target value T.sub.A1,12=600.degree. C. has been
reached.
[0052] After the sheet metal blank 10 has been temperature-treated
in certain regions, it is subjected to a rolling process in process
stage A2. This is carried out by means of a rolling tool 40 which
comprises a plurality of rolls 41, 42. As a result of the different
temperature regions 11, 12, 21 produced during process stage A1,
the sheet metal blank 10 comprises different flow resistance
values. The hotter first region 11 comprises a lower flow
resistance so that it is rolled down to a greater extent. Compared
thereto, the cooler second region 12 of the blank 10 comprises a
higher flow resistance, so that it is rolled down to a lesser
extent. As a result of said different flow resistance values, there
are produced portions 11.sub.2, 12.sub.2, 21.sub.2 with different
thicknesses in the blank 10. After the rolling process, the sheet
metal blank 10 is provided with subscripts 2. It can be seen that
after having passed through the rolling tool 40, the sheet metal
blank 10.sub.2 comprises a first portion 11.sub.2 with a smaller
thickness and a second portion 12.sub.2 with a greater sheet
thickness, as well as an intermediate transitional portion
21.sub.2.
[0053] When the sheet metal blank 10 passes through the rolling
tool 40, the roll gap setting remains constant, i.e. the distance
between the rolls while the sheet metal blank 10 passes through is
not changed. The thickness profile is obtained entirely as a result
of the different temperature regions 11, 12, 21 of the blank 10.
Overall, there is thus achieved a lower force/work effort. However,
it is understood that it is also possible to use a flexible rolling
process wherein the roll gap setting is varied during the rolling
process. This results in an even greater degree of flexibility and
further possibilities for producing different individual thickness
profiles in the sheet metal blank 10.
[0054] FIG. 1b) shows the temperature curve T.sub.A before, after
and during the rolling process. Again, the continuous line shows
the temperature curve for region 11 and for the portion 11.sub.2
obtained after the rolling process. Prior to the rolling operation,
the temperature increases slightly and decreases to a greater
extent during the rolling process until a temperature of
approximately 700.degree. has been reached. After the rolling
process, the rolled blank 10.sub.2 continues to cool, so that the
temperature is reduced accordingly. The temperature curve
T.sub.A2,12 for the second region 12 is largely parallel to the
temperature curve T.sub.A2,11 for the first region 11, with the
temperature being reduced by approx. 200.degree. C.
[0055] During the following process stage A3, the rolled sheet
metal blank 10.sub.2 is subjected to a heat treatment. After the
heat treatment the sheet metal blank and, respectively, its
portions are provided with the subscript 3. The heat treatment
preferably takes place in a furnace 50. As a result of the heat
treatment, any material solidifications which occurred during the
rolling operation are reduced or eliminated and the rolled sheet
metal blank 10.sub.3 again comprises a higher ductility and
elongation capacity. In consequence, the blank 10.sub.3 can be
processed more easily during the subsequent process stages, and in
addition, the material properties of the end product to be
manufactured are influenced positively. It is understood that the
heat treatment in process stage A3 is of an optional nature only,
which means that, in principle, the sheet metal blank 10.sub.2 can
be processed further without undergoing the subsequent heat
treatment.
[0056] As can be seen in FIG. 1b), the blank 10.sub.3 is heated to
approximately 950.degree. C., with the thinner first blank portion
11.sub.3 heating up more quickly than the thicker blank portion
12.sub.3.
[0057] After completion of the heat treatment according to process
stage A3, the blank 10.sub.3 can be processed further, one example
being a forming operation in a hot forming tool 60. In view of the
hot forming process, the sheet metal blank and its portions have
been provided with the subscript four. During the hot forming
process in accordance with process stage A4, the sheet metal blank
10.sub.4 is subjected to a forming operation and at the same time,
it is considerably cooled and hardened respectively. This is also
confirmed by the temperature curve which, for the thinner first
portion 11.sub.4 (temperature T.sub.A4,11) indicates a considerable
temperature drop from 950.degree. C. to below 200.degree. C. The
thicker second blank portion 12.sub.4 cools somewhat more slowly,
as indicated by the dashed line (Temperature T.sub.A4,12). It is
understood that other hot forming processes can also be used for
forming purposes. By way of example, pressing or deep-drawing
processes could be mentioned.
[0058] FIGS. 2a) and 2b) show an inventive process of producing a
sheet metal blank with different thicknesses according to a second
process stage B. This process largely corresponds to the processes
according to FIGS. 1a) and 1b), respectively, so that as far as
common features are concerned, reference is made to the above
description. Identical or modified components have been given the
same reference numbers as in FIG. 1. Substantially, only the
aspects in which the present process differs will be referred to
below.
[0059] A specific feature of process B according to FIG. 2 consists
in that the sheet metal blank is first heated in a process stage
B0. The temperature to which the sheet metal blank 10 is heated
depends on the material and strength of the material; for a steel
material it preferably amounts to 900.degree. C. to 950.degree. C.
After the blank has been heated during process stage B0, a partial
change in the temperature of the sheet metal blank 10 is carried
out during the subsequent process stage B 1. In the present
embodiment this is effected by cooling certain regions of the sheet
metal blank 10. In the present example, the sheet metal blank
10.sub.1 comprises a first region 11.sub.1 which is cooled down to
800.degree. C. and a second region 12.sub.1 which is cooled down to
600.degree. C. Between the two regions 11.sub.1, 12.sub.1 there
exists a transition region 21.sub.1 with a variable temperature
curve along its length and, respectively, in the subsequent
direction of rolling.
[0060] FIG. 2b) shows the temperature curve T.sub.B of the sheet
metal blank 10.sub.1 and, respectively, of the first region 11 and
of the second region 12 as a function of time. The continuous line
represents the temperature curve T.sub.B,11 for the first region
11.sub.1, whereas the dashed line represents the temperature curve
T.sub.B,12 as a function of time for the second region 12. With
reference to the second process stage B1 it can be seen that the
first region 11.sub.1 of the sheet metal plate 10.sub.1 is cooled
down from 950.degree. C. to approximately 800.degree. C.
(temperature curve T.sub.B1, 11). The second region 12.sub.1
experiences a higher cooling rate in that it is cooled to
approximately 600.degree. C. (temperature curve T.sub.B1, 12).
[0061] The product existing at this point in time corresponds to
the sheet metal blank 10.sub.1 originating from the first process
stage A according to FIGS. 1a), b) such as it takes place according
to the first process stage A1. The process stages B2, B3 and B4
following in accordance with the second process stage B correspond
to process stages A2, A3 and A4 according to FIG. 1, so that to
this extent reference is made to the above description.
[0062] Another specific feature of the present embodiment according
to FIG. 2 is that the regional change in temperature T.sub.B1 is
effected by cooling in process stage B1, wherein said regional
temperature change is effected after the heating process of process
stage B0 and starts from the homogenous first temperature. Said
process is advantageous in that it is possible to use the heat from
the preceding heating process according to process stage B0, so
that the present process is very effective. Regional cooling of the
plate metal blank 10 is preferably carried out by means of a punch
30 which is made to contact the blank 10 such that the blank 10
assumes the temperature of the punch 30. More particularly, the
punch 30 comprises a plurality of cooling zones which can be set
individually. By way of example, the punch 30 can comprise a
plurality of channels for allowing a cooling medium to flow through
for cooling said channels. For variably setting different
temperature zones in the sheet metal blank 10 it is proposed that
the through-flow speed of the cooling medium through the channels
is controllable. For producing different temperature regions in the
sheet metal blank 10, the punch 30 can comprises a plurality of
cooling circuits through which the cooling medium flows. By
individually setting the through-flow speed of the cooling medium
through each individual channel it is possible to produce different
temperature zones.
[0063] The punch is preferably produced from a metallic material
with a good thermal conductivity rate, for instance from copper or
from a copper-containing material.
[0064] It is understood that the two embodiments for the different
regions of the sheet metal blank 10 which are shown in FIGS. 1 and
2 are given by way of example only. In principle, the number and
distribution of the regions 11, 12, 21 with different temperatures
T.sub.11, T.sub.12, T.sub.21 is freely selectable and can be
adapted to the thickness profile of the workpiece to be produced.
The number of regions 11,12, 21 with different temperatures
T.sub.11, T.sub.12, T.sub.21 preferably ranges between two and six,
but a larger number of regions is also conceivable.
[0065] FIG. 3 shows a further example for a sheet metal blank after
the temperature has been partially changed in accordance with
process stage A1 and B1 respectively. It can be seen that in the
present embodiment, the blank 10 comprises six regions 11-16 each
with a different temperature T.sub.11-T.sub.16. These have been
shown in the form of white regions. Between the six regions 11-16
with substantially constant temperatures T.sub.11-T.sub.16 there
exist transition regions 21-25 in which the temperatures
T.sub.21-T.sub.25 are variable. Said transition regions 21-24 are
hatched. In said transition regions, the temperature from one
temperature region to the next changes continuously. The production
direction and subsequent rolling direction is indicated by an arrow
R.
[0066] FIG. 3b) shows the sheet metal blank 10 in a side view
before the rolling process, i.e. in profile in a greatly
exaggerated form. It can be seen that the blank 10 comprises a
uniform thickness along the length of same before rolling.
[0067] FIG. 3c) shows the sheet metal blank 10.sub.2 after having
been rolled in accordance with process stages A2 according to FIG.
1, respectively process stage B2 according to FIG. 2. It can be
seen in FIG. 3c that, as a result of the rolling operation, the
sheet metal blank 10.sub.2 has been given a variable thickness
profile along its length. Due to the temperature zones 11-16
produced prior to the rolling operation, the regions 13, 16 heated
to a greater extent were rolled to a greater extent than the cooler
regions 12, 15, which is due to the lower flow resistance values.
There is thus obtained the thickness profile of the sheet metal
blank 10 along its length, as illustrated diagrammatically in FIG.
3c).
[0068] FIGS. 4a and b), which will be described jointly below, show
a sheet metal blank 10 in a further possible embodiment after the
temperature has been regionally changed, prior to the rolling
process according to FIG. 4a) and after the rolling process
according to FIG. 4b). The distribution of the different
temperature regions largely corresponds to that shown in FIG. 3, so
that, as far their common features are concerned, reference is made
to the above description. A special characteristic of the present
embodiment consist in that the region 15 comprises a temperature
gradient transversely to the rolling direction R of the sheet metal
blank 10, which means that the temperature T.sub.15', on the one
side, amounts to approximately 600.degree. C. and on the opposite
side to approximately 800.degree. C. The remaining regions 11, 12,
13, 14 and 16 each comprise substantially uniform temperatures
transversely to the direction of rolling R.
[0069] Because the temperature in region 15 is variable in the
direction extending transversely to the direction of rolling, the
blank is rolled non-uniformly. It can be seen in FIG. 4b that,
after the rolling operation, the blank 10.sub.2 has experienced a
change in shape in the longitudinal direction. On side 18 of the
region 15 which is more intensely cooled to 600.degree. C., the
sheet metal blank 10.sub.2 is rolled to a lesser extent than on the
opposite side 19 which was cooled to 800.degree. C. only. In a plan
view of blank 10, there is thus obtained a kink in said portion
15.sub.1. The thickness profile along the length on side 18, whose
region 15 is cooled to a lesser extent, is shown in FIG. 4c). It
substantially corresponds to the profile according to FIG. 3c), but
in the present embodiment, the transition regions are thinner.
[0070] By producing different temperature regions T.sub.15, even
transversely to the rolling direction R, a maximum degree of
flexibility is achieved as regards the thickness profile. In an
advantageous way, the sheet metal blanks 10 to be produced can be
adapted individually to the thickness profile to be required for
the subsequent end product. The advantage of the process described
in connection with FIGS. 1 and 2 as well as of the associated
devices consists in that finish-formed cuts can be produced within
the framework of a short process chain with a high degree of
efficiency. More particularly, the combination of the process
involving a partial change in temperature according to process
stages A1 and B1 for the sheet metal blank 10 prior to being
rolled, followed by a normalizing and a subsequent hot forming
operation is particularly advantageous because the temperature
level in the sheet metal blank remains relatively high during the
complete process chain, more particularly over a temperature range
of 400.degree. C. to 500.degree. C., as a result of which the
energy input for production purposes is low. In this way, it is
possible to produce the formed cut sheet metal blanks by means of a
short process chain and thus with a high degree of efficiency.
LIST OF REFERENCE NUMBERS
[0071] 10--metal blank [0072] 11-16--region/portion [0073]
21-25--transition region/transition portion [0074]
30--temperature-changing tool [0075] 40--rolling tool [0076]
41--rolls [0077] 42--rolls [0078] 50--heating furnace [0079]
60--forming tool [0080] A--process sequence [0081] B--process
sequence [0082] D--thickness [0083] R--rolling direction [0084]
T--temperature
[0085] The principle and mode of operation of this invention have
been explained and illustrated in its preferred embodiment.
However, it must be understood that this invention may be practiced
otherwise than as specifically explained and illustrated without
departing from its spirit or scope.
* * * * *