U.S. patent application number 11/664442 was filed with the patent office on 2008-01-10 for method and device for the deformation of semi-finished material in wire and rod form, close to the final dimensions, as well as a flat profile produced accordingly.
Invention is credited to Victor Blinov, Norbert Brachthauser, Heinz Hofinghoff, Hans-Toni Junius, Rudolf Kawalla.
Application Number | 20080006350 11/664442 |
Document ID | / |
Family ID | 35267631 |
Filed Date | 2008-01-10 |
United States Patent
Application |
20080006350 |
Kind Code |
A1 |
Junius; Hans-Toni ; et
al. |
January 10, 2008 |
Method and Device for the Deformation of Semi-Finished Material in
Wire and Rod Form, Close to the Final Dimensions, as Well as a Flat
Profile Produced Accordingly
Abstract
The invention relates to a method for shaping wire-shaped and
rod-shaped starting materials by rolling, especially for rolling
flat profiled elements consisting of a wire rod. The starting
material is heated in a heating station at a desired temperature,
shaped during at least one rolling process, and then cooled.
According to the invention, once the starting material has been
heated in the heating station, it is cooled in a cooling station to
a pre-determinable rolling temperature; it is then shaped into a
flat profiled element by rolling close to the gauge block, and then
cooled and/or subjected to a subsequent treatment according to
joining properties to be correspondingly adjusted. In this way, a
series of different methods can be carried out by means of an
installation for rolling starting materials with a patented
structure, an austenite structure, a bainite structure or an
undercooled austenite structure.
Inventors: |
Junius; Hans-Toni;
(Iserlohn, DE) ; Hofinghoff; Heinz; (Schalksmuhle,
DE) ; Brachthauser; Norbert; (Bochum, DE) ;
Blinov; Victor; (Herdecke, DE) ; Kawalla; Rudolf;
(Bobritzsch, DE) |
Correspondence
Address: |
WILLIAM COLLARD;COLLARD & ROE, P.C.
1077 NORTHERN BOULEVARD
ROSLYN
NY
11576
US
|
Family ID: |
35267631 |
Appl. No.: |
11/664442 |
Filed: |
September 13, 2005 |
PCT Filed: |
September 13, 2005 |
PCT NO: |
PCT/DE05/01599 |
371 Date: |
April 23, 2007 |
Current U.S.
Class: |
148/559 ;
266/103; 266/110; 266/112 |
Current CPC
Class: |
B21B 45/0224 20130101;
B21B 45/004 20130101; C21D 9/525 20130101; C21D 8/065 20130101;
B21B 2045/006 20130101; C21D 9/62 20130101; B21B 45/023 20130101;
B21B 1/18 20130101; C21D 9/5732 20130101; B21B 1/166 20130101 |
Class at
Publication: |
148/559 ;
266/103; 266/110; 266/112 |
International
Class: |
C21D 9/52 20060101
C21D009/52; C21D 1/63 20060101 C21D001/63; C21D 1/74 20060101
C21D001/74 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 2, 2004 |
DE |
10 2004 048 443.0 |
Claims
1. Method for deformation of semi-finished material (17) in wire or
rod form, by means of rolling technology, particularly for rolling
of flat profiles (18) from rolled wire, in which heating of the
semi-finished material (17) to a desired temperature takes place in
a heating station (5), the semi-finished material (17) is deformed
in at least one rolling process (7), and subsequently cooled,
wherein after heating of the semi-finished material (17) in the
heating station (5), which is brought about by means of supplying
electrical or thermal energy, the semi-finished material (17) is
subsequently cooled to a rolling temperature that can be
pre-determined, in a cooling station (14), for setting a
microstructure that can be predetermined, over a period of effect,
deformed into a flat profile (18) at this rolling temperature,
close to the final dimensions, and subsequently is cooled and/or
post-treated in accordance with the microstructure properties that
are to be set.
2. Method according to claim 1, wherein the heating of the
semi-finished material (17) takes place, in the heating station
(5), to a temperature above the A.sub.3 temperature of the .gamma.
mixed crystal (austenite).
3. Method according to claim 1, wherein the heating of the
semi-finished material (17) takes place, in the heating station
(5), to a temperature in the range of the .alpha./.gamma. mixed
crystal (ferrite/austenite).
4. Method according to claim 1, wherein the heating of the
semi-finished material (17) takes place in the heating station (5),
to a temperature in the range just below the A.sub.1 point.
5. Method according to claim 1, wherein round wire or oval wire is
used as the semi-finished material (17).
6. Method according to claim 5, wherein the round wire or oval wire
runs through the process as a semi-finished material (17) that can
be wound up.
7. Method according to claim 5, wherein the round wire or oval wire
runs through the process as a rod-like semi-finished material
(17).
8. Method according to claim 1, wherein unalloyed or low-alloyed
carbon steels are used as the semi-finished material (17).
9. Method according to claim 1, wherein cooling in the cooling zone
or cooling station (14) cools the semi-finished material (17),
before rolling (7), to a temperature for setting an austenite
microstructure, of only slightly above the A.sub.3 temperature, for
C 75 to a temperature of about 800.degree. C.
10. Method according to claim 1, wherein cooling in the cooling
zone or cooling station (14) cools the semi-finished material (17),
before rolling (7), to a temperature for setting a patenting
microstructure, for C 75 to a temperature between 400-550.degree.
C.
11. Method according to claim 1, wherein cooling in the cooling
zone or cooling station (14) cools the semi-finished material (17),
before rolling (7), to a temperature for setting a bainite
microstructure, for C 75 to a temperature between 275-370.degree.
C
12. Method according to claim 1, wherein cooling in the cooling
zone or cooling station (14) cools the semi-finished material (17),
before rolling (7), to a temperature for setting an undercooled
austenite microstructure, for C 75 to a temperature between
220-280.degree. C.
13. Method according to claim 1, wherein the semi-finished material
(17) is held at least at the temperature set in the cooling zone or
cooling station (14), after cooling of the semi-finished material
(17), during the rolling process (7).
14. Method according to claim 1, wherein the semi-finished material
(17) is subjected to further cooling (9, 10), particularly rapid
cooling (10), after the deformation (7) by means of roller
technology to produce a flat profile (18) close to the final
dimensions.
15. Method according to claim 1, wherein the rapid cooling (10)
cools the rolled flat profile (18) at least below the temperature
limit for the occurrence of oxidation processes at the surface of
the flat profile (18).
16. Method according to claim 9, wherein after rolling (7) of the
flat profile (18) in the temperature range of the austenite
microstructure, immediately afterward, cooling of the austenite
microstructure for conversion to a sorbite microstructure is
carried out.
17. Method according to claim 12, wherein after rolling (7) of the
flat profile (17) in the temperature range of the undercooled
austenite microstructure, and cooling in a cooling segment (9, 10)
with quenching of the undercooled austenite microstructure for
conversion into a martensite microstructure, immediately afterward,
an annealing treatment with cooling of the flat profile (18) before
it is wound up is carried out.
18. Method according to claim 12, wherein after rolling (7) of the
flat profile (18) in the temperature range of the undercooled
austenite microstructure, immediately afterward, a tempering
treatment without quenching of the undercooled austenite
microstructure, but with an annealing treatment for forming a
bainite microstructure, and an annealing treatment with cooling of
the flat profile (18) before it is wound up (11) is carried
out.
19. Method according to claim 12, wherein after rolling (7) of the
flat profile (18) in the temperature range of the austenite
microstructure, quenching of the austenite microstructure for
conversion into a martensite microstructure is carried out, and
afterward, an annealing treatment with cooling of the flat profile
(18) before it is wound up (11) is carried out.
20. Method according to claim 1, wherein the cooling of the
semi-finished material (17) takes place after it has passed through
the heating station (5) and before rolling (7), in a tempered metal
bath (14).
21. Method according to claim 20, wherein for cooling of the
semi-finished material (17) after it has passed through the heating
station (5), the semi-finished material (17) remains in the
tempered metal bath (14) for a period of time that can be
pre-determined, in particular, it passes through the tempered metal
bath (14) during a period of time that can be pre-determined.
22. Method according to claim 1, wherein the heating (5) of the
semi-finished material (17) takes place by means of inductive
heating and/or conductive heating (16) and/or by means of liquid
metal baths.
23. Method according to claim 1, wherein the heating (5) of the
semi-finished material (17) is carried out under the influence of
inert gas (6).
24. Method according to claim 1, wherein a uniformization device
(12) for temperature equalization within the heated semi-finished
material (17) is run through between heating station (5) and
cooling station (14).
25. Method according to claim 24, wherein the uniformization of the
temperature within the heated semi-finished material (17) is
carried out after it has passed through the heating station (5),
under the influence of inert gas (12).
26. Device (1) for carrying out a method according to claim 1,
wherein the device (1) has, in the pass-through direction of the
semi-finished material (17), a winding/take-off device (2, 3) for
unwinding the semi-finished material (17), which can be wound up,
or a feed device for the semi-finished material in rod form, a
heating station (5), a cooling zone or cooling station (14) for
setting a rolling temperature, a rolling station (7), a cooling
segment (9, 10), and a winding/take-off device (11) for winding up
the flat profile (18) that can be wound up, or a removal device for
the flat profile in rod form.
27. Device (1) according to claim 26, wherein the rolling station
(7) has at least one rolling device, preferably several rolling
devices switched one behind the other.
28. Device (1) according to claim 26, wherein a temperature
monitoring device (8) for detecting the temperature of the
semi-finished material (17) before and/or after rolling is disposed
in the region of the at least one rolling device (7).
29. Device (1) according to claim 26, wherein contact rollers (16)
through which current flows are disposed in the intake region of
the device (1) for the semi-finished material (17), for heating the
semi-finished material (17) by means of conductive heating.
30. Device (1) according to claim 26, wherein the cooling station
(14) has a tempered metal bath for setting a rolling
temperature.
31. Device (1) according to claim 30, wherein the tempered metal
bath (14) is a metal bath of a lead/bismuth alloy.
32. Device (1) according to claim 30, wherein the tempered metal
bath (14) is disposed ahead of and/or behind the rolling station
(7).
33. Device (1) according to claim 30, wherein the tempered metal
bath (14) has a winding device and/or deflection device (15), over
which the semi-finished material (17) can be guided during the
dwell time in the tempered metal bath (14).
34-41. (canceled)
42. Device (1) according to claim 27, wherein a tempered metal bath
(20) is disposed behind the rolling station (7).
43. Device (1) according to claim 27, wherein water cooling (10)
cools the flat profile (18) in the cooling segment (9, 10), at high
temperature gradients.
44. Device (1) according to claim 27, wherein another conductive
heating station (5') can be provided, for heating the flat profile
(18), for tempering that takes place after rolling (7).
45. Device (1) according to claim 44, wherein the heating (5') of
the flat profile (18) takes place for tempering under the influence
of inert gas (6).
46. Device (1) according to one of claim 27, wherein another
cooling segment (10) can be provided, for cooling the flat profile
(18) within the framework of tempering that takes place after
rolling (7).
Description
[0001] The present invention relates to a method for the
deformation of semi-finished material in wire and rod form, close
to final dimensions, in accordance with the preamble of claim 1, to
a device suitable for carrying out the method, in accordance with
claim 26, as well as to a flat profile produced according to the
method, in accordance with claim 38.
[0002] The production of relatively narrow and flat strips of steel
materials, referred to hereinafter as flat profiles, can take place
in different ways, depending on the material properties that are
required, the dimensions of the flat profiles to be produced, and
the purpose of use of the flat profiles. Flat profiles are usually
understood to mean profile shapes in which the width of the
cross-section is not greater than 10-20 times the thickness. Such
flat profiles are used for functional components and, in many
instances, also for wear components in technical devices, e.g. for
springs or similar components in the automotive, aircraft, and
space industry, in equipment construction, and in agricultural
machine construction. Also, such flat profiles are used as the
starting material for the production of saws, saw blades, bush
chains for motorcycles and bicycles, rollers, roller bearings, ski
edges, or also for piston rings. Frequently, these flat profiles
are components subject to great mechanical stress, whose strength
properties are of central significance, in addition to the
adherence to required cross-sectional shapes and dimensions.
[0003] In the case of properties that are usually required, such
flat profiles are frequently cut out of wide steel strips, by means
of dividing them lengthwise, making it possible to use commercially
available steel strips as the starting material, which can be
brought to the appropriate dimensions by means of known hot-rolling
and/or cold-rolling processes. Setting of the material properties
is generally also not problematic in the case of such steel strips,
since the material of the flat profiles does not change in
comparison with that of the steel strips when it is divided
lengthwise.
[0004] However, such flat profiles have the disadvantage of not
demonstrating certain configurations of the edges of the flat
profiles that are required or advantageous on the basis of the
later use of the flat profiles, which configurations certainly have
important advantages for the fitness for use and/or useful lifetime
of the components produced from them. Thus, after the lengthwise
division of steel strips from broad steel strips, an edge shaping
must be worked on, as an extra step, by means of additional
machining processes after the lengthwise division, and this causes
additional costs.
[0005] Another possibility for the production of such flat profiles
consists in drawing the materials, as wire, through appropriately
formed drawing dies, which produce the required profile
cross-sections and their precise geometry, as well as the edge
configuration, automatically. Problems in connection with the
drawing of corresponding flat profiles, which is otherwise
wide-spread for wire production, are, for one thing, the relatively
low drawing speeds that can be reached, due to the wear of the
drawing molds that otherwise occurs, and for another, the
cold-solidification of the materials that occurs when drawing
corresponding materials, because of transformation, which can only
be made retroactive again by means of complicated intermediate heat
treatments of the drawn wires. As a result, such production of flat
profiles is complicated and technically not without problems.
[0006] It is furthermore known to produce corresponding flat
profiles by means of cold-rolling, in that a starting material
structured as a round wire, for example, is gradually transformed
into a flat profile by means of cold-rolling, by means of
relatively slight reductions in cross-section, as a function of the
deformation, in each instance. In this connection, it is also
possible to guarantee the dimensions and the required edge
configurations by means of appropriate guidance of the technology.
However, as in the case of all cold-rolling methods, it is a
disadvantage that the cold-rolled materials are subject to
corresponding cold solidification, as in the case of drawing, and
therefore also have to undergo intermediate treatment, analogous to
the heat treatment that is necessary for drawing. Particularly in
the case of great changes in cross-section, however, this
frequently makes intermediate annealing of the materials necessary
during the course of cold-rolling.
[0007] Therefore, an approach for the further development of
rolling flat profiles from wire-like starting material has become
known, in which hot-rolling is carried out instead of cold-rolling,
according to EP 0 314 667 B2, in order to carry out the significant
cross-section changes during transformation of the wire-like
starting material in the hot state of the material, in which it is
significantly easier to deform. For this purpose, the wire-like
starting material is heated to a temperature of at most A.sub.1 or
to the conversion temperature, into the .gamma. region of the
alloy, and then rolled in a multiple frame. Subsequently, the
rolled flat profile can then be cooled. A disadvantage of this
method of procedure is that while it is possible to carry out the
deformation relatively true to final dimensions, control of the
material properties of the material is anything but simple-in the
case of such process management. Also, the processing of steel
materials is limited to only specific material classes.
[0008] It is therefore the task of the present invention to
indicate a method for the deformation of semi-finished material in
wire and rod form, close to final dimensions, which combines the
advantages of the hot-forming of semi-finished material in wire and
rod form with the adherence to the process management relevant for
the material characteristic values, and thereby allows the
production of a great number of different material and work piece
properties, which can nevertheless be set in very uniform
manner.
[0009] The solution for the task according to the invention is
evident, with regard to the method for continuous tempering of
strip steel, from the characterizing features of claim 1, with
regard to the device suitable for carrying out the method, from the
characterizing features of claim 26, as well as with regard to a
flat profile produced in such a manner, from the characterizing
features of claim 38, in interaction with the characteristics of
the related preamble, in each instance. Further advantageous
embodiments of the invention are evident from the dependent
claims.
[0010] The invention according to claim 1 proceeds from a method
for the deformation of semi-finished material in wire and rod form,
by means of roller technology, particularly for rolling of flat
profiles from rolled wire, in which heating of the semi-finished
material to a desired temperature takes place in a heating station,
the semi-finished material is deformed in at least one rolling
process, and subsequently cooled. A method of this type is further
developed in that after heating of the semi-finished material in
the heating station, the semi-finished material is cooled to a
rolling temperature, in a cooling station, deformed into a flat
profile at this rolling temperature, close to the final dimensions,
and subsequently is cooled and/or post-treated in accordance with
the microstructure properties that are to be set. By means of the
targeted cooling of the material to the desired rolling temperature
before the rolling process is carried out, it can be achieved,
despite the prior heating of the material to a temperature required
to trigger the desired microstructure conversions, which is
generally a higher temperature, that precisely the starting
microstructure can be set, before rolling of the semi-finished
material, which guarantees the desired microstructure properties of
the flat profile, together with the change in the material due to
rolling and any post-treatment that might follow the rolling. In
this connection, a corresponding microstructure conversion is
assured, by means of heating the semi-finished material to a
temperature that guarantees reliable austenitization, for example,
above the A.sub.3 temperature, which then sets a microstructure
state, by means of targeted cooling of the semi-finished material
to the temperature required for rolling, which essentially allows
the starting basis for changing the microstructure of the flat
profile to the finished cross-section, close to the final
dimensions. Here, additional post-treatments such as cooling and
hardening can also follow, which allow a further change in the
microstructure properties. With this, a possibility has been found
for combining deformation of flat profiles produced from steel
materials, in the hot state, close to final dimensions, with a
targeted adjustment of the microstructure with regard to
characteristic material values, which minimizes the post-treatment
of flat profiles produced in such a manner.
[0011] It is particularly advantageous if the heating of the
semi-finished material takes place in the heating station to a
temperature above the A.sub.3 temperature of the .gamma. mixed
crystal (austenite). In this way, the most varied microstructures
can be produced from the austenitized microstructure as the
starting microstructure, before rolling of the semi-finished
material, which correspond to the various properties of the steel
material required for the typical uses of the flat profile, and
thereby allow a broad area of use of flat profiles produced
accordingly.
[0012] Another embodiment of the method according to the invention
provides that the heating of the semi-finished material takes place
in the heating station to a temperature in the range of the
.alpha./.gamma. mixed crystal (ferrite/austenite). In this way, an
advantageous starting microstructure can be set for the subsequent
rolling, particularly for steels low in carbon.
[0013] It is also possible, in another embodiment, that the heating
of the semi-finished material takes place in the heating station to
a temperature just below the A.sub.1 point. In this way, other
different processes of the microstructure conversion can be
triggered during the rolling of the semi-finished material, which
leads to another spectrum of the microstructure configuration of
the rolled and possibly post-treated flat profile.
[0014] It is significantly advantageous for carrying out the method
if round wire or oval wire is used as the semi-finished material.
In this connection, round wire should be understood to be not only
wire having a circular cross-section, which can be produced by
means of rolling technology or drawing technology, for example, but
rather in general, wire having any cross-section that is suitable
for deformation into a flat profile by means of rolling technology.
In this connection, corresponding oval wires have an oval
cross-section. In this connection, the free spreading of the round
wire or oval wire during roller processing is generally utilized in
order to bring about required property changes with regard to the
geometry of the flat profile, on the one hand, and, on the other
hand, in order to bring about the required microstructure
properties and, with them, the material properties of the finished
flat profile. Such round wire or oval wire is a commercially
available semi-finished material, and can be purchased commercially
in many different compositions and alloys, thereby making the costs
for such round wire or oval wire relatively advantageous.
[0015] It is possible, in this connection, that the round wire or
oval wire runs through the process as a semi-finished material that
can be wound up. In this way, essentially continuous processing of
the round wire or oval wire, which is usually delivered on rings,
is possible, which wire can be processed further as a wound-up coil
of the finished flat profile, also as a finished material that can
be wound up. In another embodiment, however, it is also possible
that the round wire or oval wire runs through the process as a
rod-like semi-finished material, whereby the rod-like semi-finished
material also yields rod-like flat profiles, accordingly.
[0016] It is advantageous if unalloyed or low-alloyed carbon steels
are used as the semi-finished material. Such unalloyed or
low-alloyed carbon steels form the starting material for the
production of many different components, and offer a broad palette
of areas of use for flat profiles produced according to the
invention.
[0017] It is possible, in this connection, that the heating of the
semi-finished material in the heating station takes place to a
temperature above the A.sub.3 point. Such a temperature of the
semi-finished material clearly lies in the range of austenite for
the steels usually used in this connection, so that the
microstructure changes that occur during austenitization form the
basis for a number of usual changes in the material properties,
with regard to the material properties of the flat profiles that
are to be achieved.
[0018] A first embodiment of the method according to the invention
can be seen in that cooling in the cooling station cools the
semi-finished material, before rolling, to a temperature for
setting an austenite microstructure, of only slightly above the
A.sub.3 temperature of about 800.degree. C. In this way, the
rolling process itself is still carried out with the
characterization of the microstructure of the semi-finished
material as an austenite microstructure, which makes it possible
for diffusion processes to still take place in correspondingly
simple manner, and influencing of the intended microstructure
changes can be carried out in controlled manner.
[0019] For this purpose, in another advantageous embodiment of this
characterization of the method, cooling of the austenite
microstructure for conversion to a sorbite microstructure is
carried out immediately after rolling of the flat profile, in the
temperature range of the austenite microstructure. This sorbite
microstructure is configured with very fine lamellae, and offers
the best prerequisites for certain areas of use of such flat
profiles.
[0020] Another embodiment of the method according to the invention
can be seen in that cooling in the cooling station cools the
semi-finished material, before rolling, to a temperature for
setting a patenting microstructure, for example for a steel C75,
between 400-550.degree. C. Such a patenting microstructure is
formed from a fine-striped perlite, and is particularly suitable
for further cold-drawing of corresponding flat profiles, for
example, or also for areas of use of the flat profiles in which
great tensile strengths must be combined with good impact strength
of the materials. A correspondingly slow cooling of the patenting
microstructure from the perlite stage usually follows the rolling,
in this connection. The formation of a patenting microstructure
(the same holds true also for the bainite microstructure and
austenite microstructure indicated in the following), takes place,
in the case of every material that is relevant here, because of its
composition, at a different temperature, but this is known and
characteristic for each material. The connections between the
microstructure characterizations and the temperatures and kinds of
process management of the different materials, in each instance,
can be read off from the so-called time/temperature conversion
graphs (so-called TTC graphs), in this connection. Therefore, in
the following, the temperature for setting a patenting
microstructure (or a bainite microstructure or an austenite
microstructure, respectively) is understood to be a temperature
that, although it is different for every material relevant here, is
clear when a corresponding material is indicated, for which
concrete values are also given, purely as an example, for a steel
C75. For the remainder, a person skilled in the art knows what
temperatures he/she must set for setting a patenting microstructure
or a bainite microstructure or an austenite microstructure,
respectively, for every material that is relevant here.
[0021] Another embodiment of the method according to the invention
can be seen in that cooling in the cooling station cools the
semi-finished material, before rolling, to a temperature for
setting a bainite microstructure, for example for a steel C75,
between 275-370.degree. C. In this connection, the semi-finished
material, in contrast to the setting of a patenting microstructure,
is cooled even further, until rolling of the semi-finished material
is carried out in a microstructure state of the intermediate stage
microstructure bainite, in which diffusion processes are prevented,
to a great extent, because of the low temperature, and .alpha.
lattice regions form due to folding of austenite regions in the
material. This is where fine-grained cementite precipitates, with
the advantageous effects for the microstructure properties.
[0022] An alternative embodiment of the method according to the
invention can be seen in that cooling in the cooling station cools
the semi-finished material, before rolling, to a temperature for
setting an undercooled austenite microstructure, for example for a
steel C75, between 220-280.degree. C. By means of correspondingly
rapid cooling of the microstructure from the austenite, conversion
processes that occur otherwise are delayed, or cannot occur at all,
or not to a significant extent, so that rolling of such a rapidly
cooled, undercooled austenite microstructure offers the possibility
of carrying out the conversion to a martensite microstructure with
the known, needle-like hardening microstructure, thereby making it
possible to produce corresponding high-strength materials with
which, in a further embodiment, for example, an annealing
treatment, with cooling of the flat profile before it is wound up,
can be carried out immediately afterward, for example. By means of
the annealing treatment, the material is changed once again with
regard to hardness and impact strength, and thereby achieves great
hardness, while continuing to have good mechanical strength
properties.
[0023] However, in the case of rolling of the semi-finished
material as undercooled austenite, it is possible that after
rolling of the flat profile, directly following, a tempering
treatment is carried out, without quenching the undercooled
austenite microstructure, but with an annealing treatment, possibly
for the formation of a bainite microstructure, and an annealing
treatment with cooling of the flat profile before it is wound up.
In this connection, instead of the martensite formation described
above, the intermediate stage microstructure bainite is produced,
which has the advantageous properties also already above.
[0024] Furthermore, it would also be possible, without producing
undercooled austenite, to roll directly in the austenite phase, as
already described above, to quench after rolling of the flat
profile, in the temperature range of the austenite microstructure,
in order to form martensite, but directly afterward, to carry out
an annealing treatment and cooling of the flat profile before it is
wound up. In this way, an annealed martensite microstructure is
produced, which also has the advantages already mentioned.
[0025] It is advantageous in connection with all these different
kinds of process management if the semi-finished material is held
at least at the temperature set in the cooling station, after
cooling of the semi-finished material, during the rolling process.
In this way, the microstructure does not change during rolling, or
does not change greatly, so that rolling alone does not trigger any
changes in microstructure. For this purpose, depending on the
configuration of the rolling process, it might be necessary either
to remove heat from the rolling zone, in view of the deformation
work introduced into the semi-finished material in this connection,
and the temperature change in the semi-finished material that
occurs thereby, for example at high degrees of deformation, or, for
example in the case of slight deformations, to hold the
semi-finished material at the desired temperature by means of
providing heat, for example by means of tempering the rollers.
[0026] Furthermore, it is possible that depending on the selection
of the process management to be carried out, the semi-finished
material is subjected to further cooling, particularly rapid
cooling, after the deformation by means of roller technology to
produce a flat profile close to the final dimensions. For this
purpose, the material, which is already present as a flat profile,
can be subjected to water cooling, for example, or to similar known
cooling methods.
[0027] It can furthermore be practical if the rapid cooling cools
the rolled flat profile at least below the temperature limit for
the occurrence of oxidation processes at the surface of the flat
profile, and thereby ensures that oxidation processes or the like
can no longer occur, or can no longer occur to an impermissible
extent.
[0028] It is advantageous if the cooling of the semi-finished
material takes place after it passes through the heating station
and before rolling, in a tempered metal bath. Such tempered metal
baths are fundamentally known and tested, and offer the possibility
of tempering metal strips that pass through them in targeted and
precise manner, and also of holding them at a pre-determined
temperature, in order to allow corresponding equalization processes
to take place, without the surfaces of the metal strips being
exposed to impermissible oxidation.
[0029] Here, in a further embodiment, it can also be thought to
keep the semi-finished material in the tempered metal bath for a
period of time that can be pre-determined, to cool the
semi-finished material after it has passed through the heating
station, in particular, to allow it to pass through the tempered
metal bath during a period of time that can be pre-determined, in
order to allow the equalization processes that have already been
mentioned to take place, for tempering the entire cross-section of
the semi-finished material.
[0030] It is furthermore advantageous if heating of the
semi-finished material takes place by means of inductive heating
and/or conductive heating and/or by means of liquid metal baths. Of
course, other heating methods, not mentioned in detail here, are
possible; these are known and usual in metallurgy.
[0031] An improvement in the surface of the flat profile can be
achieved if the heating of the semi-finished material is carried
out under the influence of inert gas. In this way, oxidation
processes that already occur when the semi-finished material is
heated are prevented; of course these then cannot propagate through
the entire process management and therefore also cannot bring about
subsequent deviations from dimensions or surface defects.
[0032] It is furthermore possible that a uniformization device for
temperature equalization within the heated semi-finished material
is run through between heating station and cooling station, whereby
in a further embodiment, the uniformization of the temperature
within the heated semi-finished material can be carried out after
it has passed through the heating station, under the influence of
inert gas.
[0033] According to claim 26, the invention furthermore relates to
a device for carrying out the method according to claim 1, in which
the device has, in the pass-through direction of the semi-finished
material, a winding/take-off device for unwinding the semi-finished
material, which can be wound up, or a feed device for the
semi-finished material in rod form, a heating station, a cooling
station for setting a rolling temperature, a rolling station, a
cooling segment, and a winding/take-off device for winding up the
flat profile that can be wound up, or a removal device for the flat
profile in rod form. This basic configuration of the device allows
the fundamental method variants to be carried out, in which
targeted cooling of the semi-finished material is carried out,
after it has been heated, to a temperature that allows rolling of
the semi-finished material with a microstructure either as an
austenite microstructure, as a patenting microstructure, as a
bainite microstructure, or as an undercooled austenite. In this
connection, the corresponding microstructure can be set as a
function of the gradient of cooling and of the cooling time.
Additional post-treatments or also intermediate processes can be
carried out by means of the interposition or post-position of
corresponding additional device components, such as heat treatment
processes that follow rolling, for example, such as in the case of
annealing or also tempering processes, such as holding the
semi-finished material at a specific temperature over a defined
time span, in order to be able to allow equalization processes to
take place within the material.
[0034] It is advantageous if the rolling station has at least one
rolling device, preferably several rolling devices switched one
behind the other. In this way, gentle deformation of the
semi-finished material during rolling can be achieved in targeted
manner, by means of the targeted configuration and also the
arrangement of several rolling devices one behind the other.
[0035] It is furthermore possible that a temperature monitoring
device for detecting the temperature of the semi-finished material
before and/or after rolling is disposed in the region of the at
least one rolling device, with which temperature changes that are
impermissible with regard to the microstructure formation, for
example, can be recognized during rolling, and can be corrected by
means of targeted heat introduction into the rollers, for example
possibly by means of tempering the rollers.
[0036] For targeted heating of the semi-finished material, it is
advantageous if contact rollers through which current flows are
disposed in the intake region of the device for the semi-finished
material, for heating the semi-finished material by means of
conductive heating. Such conductive heating of the semi-finished
material, which is fundamentally known, allows heating that can be
controlled well, and therefore a microstructure conversion of the
semi-finished material that can be controlled well.
[0037] Particularly advantageous cooling of the semi-finished
material can be implemented if the cooling station has a tempered
metal bath for setting a rolling temperature. Such a tempered metal
bath, for example a metal bath composed of a lead/bismuth alloy, is
already used in many ways and is therefore known and tested, in
terms of its behavior. In this way, reliable tempering of the
semi-finished material can be guaranteed, even at relatively longer
pass-through times of the semi-finished material through such a
metal bath, while simultaneously preventing oxidation processes on
the surface of the semi-finished material.
[0038] It is possible, in this connection, that the tempered metal
bath is disposed ahead of and/or behind the rolling station.
Depending on the process management, rolling directly out of the
austenite phase is possible, with appropriate coordination of the
heating temperature in the heating station, so that the metal bath
then takes over the tempering of the rolled flat profile, for the
formation of bainite intermediate stage microstructure. In other
cases, the metal bath is used for targeted cooling of the
semi-finished material to the rolling temperature, and must, of
course, be disposed ahead of the rolling station then. In this
connection, in another embodiment, the tempered metal bath can have
a winding device and/or deflection device, over which the
semi-finished material is guided during the dwell time in the
tempered metal bath. The winding device or deflection device can
also take over a buffer function for subsequent device stations, in
this connection.
[0039] For specific variants of the process management, it is
advantageous if water cooling cools the flat profile in the cooling
segment, at high temperature gradients. In this way,
microstructures achieved after rolling are essentially frozen by
means of the rapid cooling, and are maintained even at lower
temperatures.
[0040] Within the framework of the post-treatment of rolled flat
profiles, it is advantageous if another conductive heating station
is provided for heating the flat profile for tempering that takes
place after rolling, in which station heating then can take place,
again, under the influence of inert gas, for example. Also, another
cooling segment can be provided, for example, for cooling the flat
profile within the framework of tempering that follows rolling.
[0041] According to claim 38, the invention furthermore describes a
flat profile produced according to the method according to claim 1.
It is advantageous if such a flat profile has an essentially
rectangular cross-section or a cross-section close to a rectangle,
whereby the most varied configurations of the edge region can be
set, depending on the later use of the flat profile.
[0042] It is advantageous if typical carbon steels, particularly
carbon steels having a carbon content between 0.10 and 1.35%,
particularly also C 10 to Ck 101/125 Cr1, can be processed. In this
connection, such flat profiles can preferably be processed in
dimensions between a thickness of 0.5-5 mm and a width of 4-25
mm.
[0043] A particularly preferred embodiment of the device according
to the invention, for carrying out the method according to claim 1,
is shown in the drawing.
[0044] This shows:
[0045] FIG. 1--a schematic representation of the fundamental
structure of a device for carrying out a method for hot-rolling
rolled wires, with the major device components,
[0046] FIG. 2--a continuous time/temperature conversion graph for
carrying out the method according to FIG. 1,
[0047] FIG. 3--a schematic representation of the fundamental
structure of a device according to claim 26, for carrying out the
method according to the invention, with cooling of the
semi-finished material before rolling, for the production of
patenting microstructure, bainite microstructure, or an undercooled
austenite microstructure,
[0048] FIG. 4--an isothermal time/temperature conversion graph for
carrying out the method according to FIG. 3, with indication of the
process management, in each instance, for the production of
patenting microstructure, bainite microstructure, or an undercooled
austenite microstructure,
[0049] FIG. 5--a modified device according to FIG. 3, for heat
treatment of an undercooled austenite microstructure, carried out
after rolling,
[0050] FIG. 6--a modified device according to FIG. 3, for heat
treatment of an austenite microstructure, carried out after
rolling, without a cooling device ahead of the rolling,
[0051] FIG. 7--a modified device according to FIG. 3, with cooling
device ahead of the rolling station, and devices for heat treatment
carried out after the rolling,
[0052] FIG. 8--a modified device according to FIG. 7, with cooling
device after the rolling station, and devices for heat treatment
carried out after the rolling.
[0053] FIG. 1 shows in a very schematic representation, the
structure of a device for carrying out a method for hot-rolling
rolled wire into flat profiles. This is a device for carrying out a
method, without any special devices for cooling the semi-finished
material before rolling.
[0054] In this connection, a flat profile 18 is understood to be
steel material whose width corresponds to maximally 10 to 20 times
its thickness, and that is usually used as the design basis for
components mainly subject to mechanical stress, such as springs,
piston rings, or the like, as well as also work pieces subject to
great stress, such as saw blades and others. The dimensions of such
flat profiles are rather slight, in contrast to rolled strip that
is produced otherwise, and typically lies in the range of up to 30
millimeters in width and 5 millimeters in thickness. The
semi-finished material 17 is usually passed to the system 1 as
round rolled wire, but of course can have other cross-sections, as
the starting material for rolling in a rolling device 7.
[0055] At system 1, the semi-finished material 17 is conveyed into
a device 5 for conductive heating of the semi-finished material 17,
from a reel having a coil run-off 2, by way of a caterpillar
take-off 3 and a directional device 4, whereby the conductive
device 5 has contact rollers 16 through which current flows, which
cause heating of the semi-finished material 17 by way of coupling
of the current into the semi-finished material 17, along the
conductive device 5. This heating takes place predominantly in an
inert gas channel 6, which prevents oxidation products from
occurring on the surface of the semi-finished material 17 during
heating. Subsequent to the second pair of contact rollers 16, a
channel 12, which is also channel-like and possibly flooded with
inert gas, is provided as an equalization zone, within which the
semi-finished material 17 heats up uniformly, also in the interior
region, by means of equalization processes, and thereby a uniform
temperature progression has been established within the
semi-finished material 17 before it enters into the rolling device
7. Within this equalization zone 12, the temperature of the
semi-finished material 17 drops from the end temperature that
occurs during heating between the contact rollers 16, of
1020.degree. Celsius, for example, to a lower temperature, so that
cooling of the semi-finished material 17 to a temperature just
slightly above the A.sub.3 temperature, for example, occurs within
the equalization zone 12. At this temperature, which is monitored
by means of a temperature measurement 8 implemented, possibly by
means of a radiation pyrometer, ahead of or behind the rolling
device 7, for example, the semi-finished material 17 enters into
the rolling device 7, and is rolled into a flat profile 18 there,
in one or more passes (in simplified manner, only one rolling
device 7 is shown, but several such rolling devices 7 can also be
set one behind the other), which profile is then cooled by means of
a cooling segment 9, with two rapid coolers 10 here, for example,
and applied to a pay-on reel 11 by way of a caterpillar take-off 3,
and wound into a coil there. The semi-finished material 17
therefore passes through the system 1 in the run-through direction
19, and is passed to the system 1 as a wound-up coil, for example
of a round rolled wire, and completed as a wound-up coil of a flat
profile 18.
[0056] Such a roller line 1 carries out a method that takes place
in accordance with the temperature management along the line 13,
according to FIG. 2, in a representation for a steel C 75 for the
production of bainite, in a continuous time/temperature conversion
graph. In this connection, the semi-finished material 17 is rolled
at a temperature just slightly below 800.degree. Celsius, and then
cooled along the line 13. The sorbite microstructure that is formed
in this connection ensures the corresponding properties of the flat
profile 18 produced in this manner. A disadvantage of this method
of procedure is that it is relatively complicated to regulate the
temperature of the semi-finished material 17, because cooling
occurs only in the equalization zone 12, and furthermore, the
temperature cannot be reduced to values that would be practical for
other kinds of process management.
[0057] Therefore a further development of the system 1 shown in
FIG. 1 is proposed, in that according to FIG. 3, the system 1 is
modified in such a manner that a cooling device 14, consisting of a
metal bath, for example a lead/bismuth bath, is set ahead of the
rolling device 7, for example, in which targeted cooling of the
semi-finished material 17 before it enters into the rolling device
7 is carried out, so that the microstructure of the semi-finished
material 17 corresponds to precisely defined conditions before it
enters into the rolling device 7, and therefore the deformation of
the semi-finished material 17 to produce the flat profile 18, if
applicable in combination with subsequent treatment processes that
will be described further below, results in the desired
microstructure of the flat profile 18 as well as the required
cross-sectional dimensions and cross-sectional shapes. For the
remainder, the system 1 of FIG. 3 essentially corresponds to the
system 1 of FIG. 1, so that in the following, only the differences
that exist will be discussed in greater detail.
[0058] In this connection, heating in the conductive device 5 can
take place in two or more stages, whereby a number of contact
rollers 16 are disposed behind one another, so that heating can be
carried out in multiple stages, possibly even using different
current intensities and therefore different temperature gradients
during heating. In general, this results in heating of the
semi-finished material 17 that can be controlled significantly
better, and furthermore, corresponding equalization processes
already occur during passage through the conductive device 5, so
that at the end of its passage through the conductive device 5, the
semi-finished material 17 is present very uniformly, for example at
the indicated temperature of 1020.degree. Celsius.
[0059] The metal bath 14 has a winding device 15 for passage of the
semi-finished material 17, in the form of rollers having a diameter
of one meter, for example, onto which the semi-finished material 17
is wound several times, and therefore remains within the metal bath
14, while passing through the metal bath 14, for a period of time
that can be pre-determined. In this connection, the metal bath 14
is tempered in such a manner that the desired starting temperature
for rolling of the semi-finished material 17 in the rolling device
7 occurs within the semi-finished material 17, and therefore
precisely the microstructure that is required for rolling within
the rolling device 7, in order to achieve the subsequent final
microstructure, can form within the semi-finished material 17. In
order to prevent impermissible surface changes of the semi-finished
material 17 after it exits from the conductive device 5 and while
it passes through the metal bath 14, inert gas channels 6 are also
disposed ahead of and behind the metal bath, so that the
semi-finished material 17 is heated and tempered almost completely
under an inert gas atmosphere.
[0060] After rolling in the rolling device 7, the flat profile 18
is cooled by way of a rapid cooler 10, by means of water cooling or
the like, and wound up as already described for FIG. 1.
[0061] In FIG. 4, various possible method sequences along the line
13', 13'', 13''' are shown in an isothermal time/temperature
conversion graph, for a steel C 75, which indicate the different
final microstructures of the flat profile 18 after rolling in the
rolling device 7. If, for example, the temperature of the
semi-finished material is reduced, within the cooling device 14, to
a value of about 500.degree. Celsius, and rolling then takes place,
a so-called patenting microstructure can be adjusted in the case of
this steel, according to the line 13', which allows particularly
great impact strength at very high tensile strength values. If, in
contrast, cooling in the cooling device 14 takes place even
further, to values of about 350.degree. Celsius, then a so-called
intermediate stage microstructure in the form of a bainite
microstructure will occur during rolling, according to the line
13''. A particularly interesting possibility for the production of
flat profiles 18 consists in carrying out cooling in the cooling
device 14 so quickly that one comes into the range below 300
degrees Celsius, of undercooled austenite, for rolling in the
rolling device 7, according to the line 13''', and then one can
carry out martensite hardening of this undercooled austenite, by
means of a corresponding post-treatment.
[0062] Thus, the placement of a cooling device 14 ahead of the
rolling in the rolling device 7 creates the possibility of
processing a very different type of materials into flat profiles 18
on a system 1, and, in this connection, of being able to conduct
the optimal process management according to the lines 13', 13'',
13''' in FIG. 4, in this connection.
[0063] A modification of the system for rolling undercooled
austenite as the microstructure of the semi-finished material 18,
described for FIG. 3, is shown in FIG. 5, in which what was said
above for FIG. 3 applies, except for the rollers in the rolling
device 7. After the rapid cooling 10 after rolling in the rolling
device 7, another conductive device 5' is disposed, which serves
for renewed heating of the flat profile 18 for tempering of the
microstructure of the flat profile 18, whereby again, heating takes
place conductively, and cooling takes place in a subsequent
rapid-cooling device 10. In this way, extensive control of the
properties of the semi-finished material 17 rolled as undercooled
austenite can be achieved.
[0064] FIG. 6 shows another modification of the system 1, in which
the rolling takes place without a separate cooling device,
according to line 3 in FIG. 4, and only after a certain cooling in
the equalization zone 12, and therefore the rolling is carried out,
in the rolling device 7, in the austenite range of the
microstructure of the semi-finished material 17. This flat profile
18, rolled and cooled in the cooling device 10 in such a manner, is
then annealed in a conductive device 5', by means of tempering
operations already described above with regard to FIG. 5, and
thereby its properties are changed once again.
[0065] According to FIG. 7 and 8, another two variants of system 1
according to FIG. 5 are shown, in which the cooling device 14 is
disposed once in front of and once behind the rolling device 7, so
that the temperature management of the semi-finished material 17
can be changed further, in the region of the rolling device 7, in
targeted manner, for example also after rolling in the rolling
device 17, by means of tempering of the flat profile 18 that has
been formed. In this connection, the cooling device 14 according to
FIG. 8 serves, for example, for correspondingly slow or targeted
tempering of the flat profile 18 after rolling, in order to bring
about a targeted change in the microstructure of the flat profile
18 that is present after rolling, without directly bringing about
overly rapid cooling of the flat profile 18.
REFERENCE SYMBOL LIST
[0066] 1--roller line/system [0067] 2--coil run-off [0068]
3--caterpillar take-off [0069] 4--directional device [0070] 5,
5'--conductive heating [0071] 6--inert gas channel [0072]
7--rolling device [0073] 8--temperature measurement [0074]
9--cooling segment [0075] 10--water cooling [0076] 11--pay-on reel
[0077] 12--equalization zone [0078] 13-13'''--temperature
management for method variants [0079] 14--cooling station/metal
bath [0080] 15--winding device [0081] 16--contact rollers [0082]
17--semi-finished material [0083] 18--flat profile [0084]
19--run-through direction, semi-finished material
* * * * *