U.S. patent application number 13/069545 was filed with the patent office on 2011-09-29 for side rail.
This patent application is currently assigned to Benteler Automobiltechnik GmbH. Invention is credited to Stefan Adelbert, Otto Buschsieweke, Christian Handing, Markus Pellmann, Martin Pohl, Martin Schroeter.
Application Number | 20110232806 13/069545 |
Document ID | / |
Family ID | 44585969 |
Filed Date | 2011-09-29 |
United States Patent
Application |
20110232806 |
Kind Code |
A1 |
Pellmann; Markus ; et
al. |
September 29, 2011 |
SIDE RAIL
Abstract
A side rail made of sheet steel includes a first region which
underwent heat treatment, a second region which is not
heat-treated, and a transition zone between the first and second
regions. The transition zone is hereby defined by a width which is
smaller than or equal to 50 mm. An additional component can be
coupled to the side rail to form a side rail assembly.
Inventors: |
Pellmann; Markus;
(Sassenberg, DE) ; Pohl; Martin; (Altenbeken,
DE) ; Schroeter; Martin; (Paderborn, DE) ;
Adelbert; Stefan; (Delbruck, DE) ; Buschsieweke;
Otto; (Paderborn, DE) ; Handing; Christian;
(Langenberg, DE) |
Assignee: |
Benteler Automobiltechnik
GmbH
Paderborn
DE
|
Family ID: |
44585969 |
Appl. No.: |
13/069545 |
Filed: |
March 23, 2011 |
Current U.S.
Class: |
148/328 |
Current CPC
Class: |
C21D 9/0068 20130101;
B62D 21/157 20130101; C21D 2221/00 20130101; B62D 25/025 20130101;
C21D 1/673 20130101; B62D 29/007 20130101 |
Class at
Publication: |
148/328 |
International
Class: |
C22C 38/00 20060101
C22C038/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 25, 2010 |
DE |
102010012833.3-21 |
Claims
1. A side rail made of a sheet steel, said side rail having a first
region which underwent heat treatment, a second region which is not
heat-treated, and a transition zone between the first and second
regions, said transition zone defined by a width which is smaller
than or equal to 50 mm.
2. The side rail of claim 1, said side rail produced by hot-forming
and press-hardening of a steel sheet blank, said first region
undergoing heat treatment after press-hardening.
3. The side rail of claim 1, wherein the width of the transition
zone is less than 30 mm.
4. The side rail of claim 1, wherein the width of the transition
zone is less than 20 mm.
5. The side rail of claim 1, further comprising joining flanges
having at least one region which is heat-treated
6. The side rail of claim 1, said side rail having openings having
at least one area which is heat-treated.
7. The side rail of claim 1, said side rail having recesses having
at least one area which is heat-treated.
8. The side rail of claim 1, wherein the first region of the side
rail is an end region, said side rail further comprising a joining
flange arranged on the end region, wherein the joining flange is
not heat-treated.
9. The side rail of claim 1, wherein the first region has
spot-shaped zones defined by a size which is less than 50 mm.
10. The side rail of claim 1, wherein the first region has
spot-shaped zones defined by a size which is less than 30 mm.
11. The side rail of claim, wherein the first region is defined by
a yield strength between 300 N/mm.sup.2 and 1300 N/mm.sup.2.
12. The side rail of claim 1, wherein the first region is defined
by a yield strength from 400 N/mm.sup.2 to 800 N/mm.sup.2.
13. The side rail of claim 1, wherein the first region is defined
by a yield strength from 400 N/mm.sup.2 to 600 N/mm.sup.2.
14. The side rail of claim 1, wherein the first region is defined
by a tensile strength between 400 N/mm.sup.2 and 1600
N/mm.sup.2.
15. The side rail of claim 1, wherein the first region is defined
by a tensile strength from 500 N/mm.sup.2 to 1000 N/mm.sup.2.
16. The side rail of claim 1, wherein the first region is defined
by a tensile strength from 550 N/mm.sup.2 to 800 N/mm.sup.2.
17. The side rail of claim 1, wherein the first region is defined
by a ductility between 10% and 20%.
18. The side rail of claim 1, wherein the first region is defined
by a ductility from 14% to 20%.
19. The side rail of claim 1, wherein the transition zone has a
yield strength or a tensile strength, or both, decreasing with a
gradient of more than 100 N/mm.sup.2 per 1 cm.
20. The side rail of claim 1, wherein the transition zone has a
yield strength or a tensile strength, or both, decreasing with a
gradient of more than 200 N/mm.sup.2 per 1 cm.
21. The side rail of claim 1, wherein the transition zone has a
yield strength or a tensile strength, or both, decreasing with a
gradient of more than 400 N/mm.sup.2 per 1 cm.
22. The side rail of claim 1, wherein the heat treatment of the
first region includes heating to a heat-up temperature, holding the
heat-up temperature during a holding time, and cooling down from
the heat-up temperature in at least two phases.
23. The side rail of claim 22, wherein the heat-up temperature
ranges between 500.degree. C. and 900.degree. C.
24. The side rail of claim 22, wherein the first region is heated
to the heat-up temperature at a time interval of up to 30
seconds.
25. The side rail of claim 22, wherein the first region is heated
to the heat-up temperature at a time interval of up to 20
seconds.
26. The side rail of claim 22, wherein the first region is heated
to the heat-up temperature at a time interval of up to 10
seconds.
27. The side rail of claim 22, wherein the first region is heated
to the heat-up temperature at a time interval of up to 5
seconds.
28. The side rail of claim 22, wherein the holding time is up to 30
seconds.
29. The side rail of claim 22, wherein the holding time is up to 20
seconds.
30. The side rail of claim 22, wherein the holding time is up to 10
seconds.
31. The side rail of claim 22, wherein the holding time is up to 5
seconds.
32. The side rail of claim 22, wherein a first phase of the two
cooldown phases has a duration which is longer than a duration of a
second phase of the two cooldown phases.
33. The side rail of claim 32, wherein the duration of the second
phase is up to 120 seconds.
34. The cross member of claim 32, wherein the duration of the
second phase is up to 60 seconds.
35. A side rail assembly, comprising a side rail made of a sheet
steel, said side rail having a first region which underwent heat
treatment, a second region which is not heat-treated, and a
transition zone between the first and second regions, said
transition zone defined by a width which is smaller than or equal
to 50 mm; and an additional component coupled to the side rail.
36. The side rail assembly of claim 35, wherein a coupling region
between the side rail and the additional component has at least one
area which is heat-treated after coupling.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims the priority of German Patent
Application, Serial No. 10 2010 012 833.3-21, filed Mar. 25, 2010,
pursuant to 35 U.S.C. 119(a)-(d), the content of which is
incorporated herein by reference in its entirety as if fully set
forth herein.
[0002] This is one of five applications all filed on the same day.
These applications deal with related inventions. They are commonly
owned and have the same inventive entity. These applications are
unique, but incorporate the others by reference. Accordingly, the
following U.S. patent applications are hereby expressly
incorporated by reference: "CROSS MEMBER", representative's docket
no.: PELLMANN-2; "TRANSMISSION TUNNEL", representative's docket
no.: PELLMANN-4''; "AUTOMOBILE COLUMN", representative's docket
no.: PELLMANN-5; and "METHOD FOR PRODUCING A MOTOR VEHICLE
COMPONENT, AND A BODY COMPONENT", representative's docket no.:
PELLMANN-6.
BACKGROUND OF THE INVENTION
[0003] The present invention relates to a side rail, and more
particularly to a side rail for installation in a motor
vehicle.
[0004] It would be desirable and advantageous to provide an
improved a side rail which obviates prior art shortcomings and can
be produced at low cost in industrial-scale production while still
being reliable in operation.
SUMMARY OF THE INVENTION
[0005] According to one aspect of the present invention, a side
rail is made of sheet steel and includes a first region which
underwent heat treatment, a second region which is not
heat-treated, and a transition zone between the first and second
regions. The transition zone is defined by a width which is smaller
than or equal to 50 mm.
[0006] In accordance with the present invention, the material
property in certain regions of the side rail of the invention can
be produced with a reliable process and with desired properties.
After hot-forming and press-hardening of a steel sheet blank made
from high-strength hardenable steel, a particular area of the side
rail is targeted to undergo a heat treatment. Heat-treating a
particular area of a component, such as the cross member, will
hereinafter also be referred to a "partially" heat-treating or
"partial" heat treatment of a component or an area of a component.
By the partial heat treatment below the austenitic transition
temperature, ductile material structures are produced in the
heat-treated regions of the side rail.
[0007] According to an advantageous feature of the present
invention, in the targeted heat-traded regions an intentional
deformation may be facilitated in the event of a crash, without
causing cracks to form in these regions or elements to be torn off.
The energy dissipation capability of the side rail is hence
increased with simultaneously high stiffness. As a result, a large
amount of energy is absorbed in a motor vehicle equipped with a
side rail according to the invention by converting kinetic energy
from the impact into deformation energy, with simultaneously high
stiffness of the passenger compartment. The side rail can
conceivably also used be as an engine support or in the region of
the luggage compartment, where possibly a higher energy absorption
capacity is required than in the region of the passenger
compartment. By targeted adjustment of the heat-treated region, the
heat-treated regions may be applied, for example, in form of zebra
stripes which are oriented in the direction of the vehicle over the
length of the side rail. In this way, the side rail can fold much
like an accordion in the event of a crash.
[0008] According to another advantageous feature of the present
invention, the width of the transition zone may be less than 30 mm,
currently preferred less than 20 mm. Within the context of the
present invention, the transition zone from a heat-treated region
to a non-heat-treated region is comparable to a zone affected by
heat from a weld seam. Moreover, the material structure is changed
in the transition zone which may not always be desirable.
[0009] According to another advantageous feature of the present
invention, a small-size transition zone may be created in the side
rail according to the invention. A transition zone of less than 15
mm may advantageously be realized on the side rail. Accordingly,
those regions on the individual components, in particular on the
side rail, which are designed to deform in the event of a crash and
those regions which can essentially retain their shape in the event
of a crash, can be clearly assigned during the manufacture of a
crash-optimized motor vehicle body.
[0010] According to another advantageous feature of the present
invention, the width of the heat-treated region may correspond to
0.2-times to 3.0-times the width and/or the height of the
heat-treated region. In relation to the distribution of the total
stress inside the component, a particularly advantageous embodiment
for the crash and stiffness structure of the motor vehicle body is
attained.
[0011] According to another advantageous feature of the present
invention, joining flanges may be partially heat-treated. The
heat-treated region, suitably embodied as joining flange, is
advantageous for the crash property and stiffness of the body, such
as an exemplary integral body-frame body. A joining flange of a
side rail is the region that is coupled with other components.
[0012] A joining flange refers to, for example, the attachment
region to the vehicle roof and/or the splash guard, but also to a
rocker panel. The coupling can be produced by gluing, riveting,
welding, brazing or similar coupling processes.
[0013] The region which has been partially heat-treated does not
have a tendency to tear or detach in the event of the accident and
therefore holds the surrounding connected structural and safety
components together. This particular advantageous for protecting
occupants in a passenger compartment.
[0014] Another advantage relates to regions subjected to an
intentional deformation in the event of an accident. The regions
defined for intentional deformation can be deformed without
cracking. This also increases the overall energy absorption
capability of the entire motor vehicle body accompanied by a small
penetration depth into the passenger compartment.
[0015] Another application is, for example, the intentional
deformation of individual regions to reduce the repair costs after
an accident. This deformation is intended to transfer energy to be
dissipated into the body, thereby once more improving the safety
for the vehicle occupants in the event of a crash.
[0016] The regions heat-treated with the method of the invention
can deform in the event of a crash so as to produce intentional
wrinkles accompanied by absorption of energy. Additionally, the
heat-treated regions tend to form less cracks due to their ductile
structure compared to the hot-formed and press-hardened, hard and
brittle structure.
[0017] The partial heat treatment of joining flanges has the
additional advantage that the joining flanges have ductile material
properties. With a material connection produced by thermal joining,
a structural change takes place in a subsequent process in the zone
affected by heat generated by the joining method. A ductile section
of the side rail is particularly advantageous for the welding
process and the material structure created in the zone affected by
heat of the welding process. This is particularly advantageous for
the durability of the connected weld seams of the motor vehicle in
the event of an accident.
[0018] According to another advantageous feature of the present
invention, openings in the side rail may be partially heat-treated.
These openings may be incorporated in the component, for example,
to reduce weight or for passing through other components, for
example a door hinge or wiring harness and the like. Cracks can
form in an accident particularly in the region of the openings and
also in the end region of openings due to stress in the components,
in particular surface stress, which can extend over the entire
component. By reducing the surface stress, a ductile material
structure is obtained in this region. This counters the formation
of cracks and hence also an accidental deformation of the side
rail.
[0019] According to another advantageous feature of the present
invention, an end region of the side rail may be partially
heat-treated, whereas a joining flange arranged on the end region
is not heat-treated. This has the advantage that by incorporating
the side rail in a motor vehicle body, the heat-treated regions can
attenuate loads caused by reverse bending stresses, which may be
introduced into the body by, for example, body torsion or other
driving parameters, for example drive train vibrations and the
like. This has a beneficial effect particularly with respect to the
durability of the motor vehicle body by reducing the surface stress
in the end regions, positively affecting the required crash
properties of the joining flanges connected to the motor vehicle
body that are not heat-treated.
[0020] According to another advantageous feature of the present
invention, spot-shaped regions of the side rail may be partially
heat-treated, wherein the spot-shaped regions have dimensions of
less than 50 mm, suitably less than 30 mm. For connecting the side
rail to a motor vehicle body, these spot-shaped regions may
advantageously be intentionally heat-treated, thereby allowing spot
welding or other local laser welding in the spot-shaped regions, as
frequently performed in the production of motor vehicles. In the
event of a motor vehicle crash, the side rail with the coupled
components has again high connection strength in these connected
spot-shaped regions. Crack formation or tearing and/or detachment
are significantly reduced with the heat-treated spot-shaped
regions.
[0021] According to another advantageous feature of the present
invention, the heat-treated regions may have a yield strength
between 300 N/mm.sup.2 and 1300 N/mm.sup.2, suitably 400 N/mm.sup.2
to 800 N/mm.sup.2, currently preferred 400 N/mm.sup.2 to 600
N/mm.sup.2. In addition, the heat-treated regions may
advantageously have a tensile strength between 400 N/mm.sup.2 and
1600 N/mm.sup.2, suitably 500 N/mm.sup.2 to 1000 N/mm.sup.2.
Currently preferred is a tensile strength of 550 N/mm.sup.2 to 800
N/mm.sup.2, and advantageously a durability between 10% and 20%,
and currently preferred 14% to 20%. The material still has the
required high-strength mechanical properties; however, due to the
reduced tensile strength, elongation limit and the increased
durability the material is sufficiently ductile to produce
wrinkles, instead of breaking or tearing, under a suitable load.
This advantageously counters potential crack formation in the
heat-treated region of the material.
[0022] According to another advantageous feature of the present
invention, the yield strength and/or tensile strength may decrease
in the transition zone from heat-treated region to non-heat-treated
region with a gradient of more than 100 N/mm.sup.2 per 1 cm,
suitably of more than 200 N/mm.sup.2 per 1 cm. Currently preferred,
the gradient is more than 400 N/mm.sup.2 per 1 cm. Advantageously,
very small local regions may be heat-treated, whereas the
transition zones are kept smaller in relation thereto. The
transition zone resulting from the gradient between the hot-formed
and press-hardened, non-heat-treated region and the partially
heat-treated region has a therefore a dimension of less than 50 mm,
particularly preferred between 1 mm and 20 mm. This produces small
local heat-treated regions with sharp edges and smaller transition
zones compared to the heat-treated regions.
[0023] According to another advantageous feature of the present
invention, the side rail may be partially heat treated by heating
the region to be heat-treated to a heat-up temperature, holding the
heat-up temperature during a holding time, and cooling down from
the heat-up temperature in at least two phases.
[0024] According to another advantageous feature of the present
invention, the component may be heated up to and in held at the
heat-up temperature in a temperature range between 500.degree. C.
and 900.degree. C. The temperature range between 500.degree. C. and
900.degree. C. for heat-up and holding the heat-up temperature
intentionally and reliably reduces stress in the heat-treated
regions during production.
[0025] According to another advantageous feature of the present
invention, heat-up may occur over a time period of up to 30
seconds, suitably of up to 20 seconds or of up to 10 seconds.
Currently preferred is a time period of up to 5 seconds. The short
heat-up phase for reaching the heat-up temperature is, in
combination with a subsequent holding phase, particularly
advantageous for the process reliability of the produced
component.
[0026] According to another advantageous feature of the present
invention, the holding time may extend over a time period of up to
30 seconds. Advantageously, the holding time may extend over a time
period of up to 20 seconds, suitably of up to 10 seconds. Currently
preferred is a time period of up to 5 seconds. Within the context
of the invention, the hardening and tempering process can be
particularly reliably performed by intentionally controlling the
material structure transformation at a constant temperature and is
only affected by the duration of the holding time. The attained
heat-up temperature is held substantially constant.
[0027] According to another advantageous feature of the present
invention, the first cooldown phase may have a longer duration than
the second cooldown phase. This is particularly advantageous for
the material structure to be produced and for the related
processing steps. The side rail according to the invention can be
post-processed immediately following processing. It is therefore
feasible within the context of the invention that the heat-treated
regions as well as the side rail have a component temperature of
200.degree. C. when transferred to a post-processing process.
[0028] Moreover, the second phase may advantageously be performed
in a time period of up to 120 seconds, suitably of up to 60
seconds.
[0029] According to another aspect of the invention, a side rail
assembly has a side rail made of a sheet steel. The side rail has a
first region which underwent heat treatment, a second region which
is not heat-treated, and a transition zone between the first and
second regions. The transition zone is defined by a width which is
smaller than or equal to 50 mm. The side rail assembly further
includes an additional component coupled to the side rail.
[0030] According to another advantageous feature of the present
invention, the side rail assembly with the side rail and the
coupled component may be partially heat-treated in the coupling
regions. This has the particular advantage that the side rail with
the coupled regions does not tend to tear off or detach in the
event of a vehicle crash. The components coupled to the side rail
may include, for example, engine support components. This may be,
for example, milled, cast or welded components.
[0031] Another advantage is that engine support components have a
longer service life because the coupled regions between the side
rail and the motor mount component better attenuate vibrations
originating at the engine due to a partial heat treatment. The
susceptibility for fatigue cracks at the coupling locations is
hereby significantly reduced.
BRIEF DESCRIPTION OF THE DRAWING
[0032] Other features and advantages of the present invention will
be more readily apparent upon reading the following description of
currently preferred exemplified embodiments of the invention with
reference to the accompanying drawing, in which:
[0033] FIG. 1 shows a detail of a side rail according to the
invention;
[0034] FIG. 2 shows a side rail according to the invention;
[0035] FIG. 3 shows a side rail assembly according to the
invention; and
[0036] FIGS. 4a), b), c) show different temperature curves during
manufacture of the side rail.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0037] Throughout all the figures, same or corresponding elements
may generally be indicated by same reference numerals. These
depicted embodiments are to be understood as illustrative of the
invention and not as limiting in any way. It should also be
understood that the figures are not necessarily to scale and that
the embodiments are sometimes illustrated by graphic symbols,
phantom lines, diagrammatic representations and fragmentary views.
In certain instances, details which are not necessary for an
understanding of the present invention or which render other
details difficult to perceive may have been omitted.
[0038] Turning now to the drawing, and in particular to FIG. 1,
there is shown a detail of a side rail. As can be seen, a
heat-treated region WB according to the present invention is formed
in a non-heat-treated region NWB. A transition zone UB is disposed
between the non-heat-treated region NWB and the heat-treated region
WB. A material structure having the tendency to be ductile is
created in the heat-treated region WB, whereas the material
structure in the non-heat-treated region NWB is hard and brittle.
The transition zone UB is inherently created during treatment of
the heat-treated region WB. In the context of the present
invention, the transition zone UB has essentially a width a, which
extends from the heat-treated region WB to the non-heat-treated
region NWB, which is particularly small in relation to the
heat-treated region WB and which has substantially sharp edges.
[0039] FIG. 2 shows a side rail 1 according to the invention. The
side rail 1 has beads 2, openings 3 and recesses 4. The side rail 1
according to the invention has joining flanges 5 in its marginal
regions. Depending on the requirements, the beads 2, openings 3 and
recesses 4 and the joining flanges 5 are each partially
heat-treated after hot-forming and press-hardening of the side rail
1 according to the invention.
[0040] FIG. 3 shows a side rail assembly 6. The side rail assembly
6 consists of an upper hot-formed, press-hardened side rail 1 which
is partially heat-treated after press-hardening, and a lower
hot-formed, press hardened component 7 which is also partially
heat-treated after press-hardening. The side rail 1 and the
component 7 are coupled to one another at their side regions by way
of joining flanges 5. The coupling locations 8 are, according to
the invention, partially heat-treated after the joining process,
for example a thermal joining process.
[0041] FIG. 4a shows a temperature curve as a function of time,
with the time intervals heat-up time (t1), holding time (t2),
cooldown time first phase (t3) and cooldown time second phase (t4).
Also shown on the temperature axis are the heat-up temperature (T1)
and a first cooldown temperature (T2).
[0042] Starting with a blank of sheet steel which is hot-formed and
press-hardened to produce a side rail which is essentially at a
temperature below 200.degree. C., this vehicle component is heated
during the heat-up time to the heat-up temperature (T1). With a
starting temperature of below 200.degree. C., but still above room
temperature, the residual thermal energy from the hot-forming and
press-hardening process is used for the partial heat treatment
within the context of the invention.
[0043] Heat-up includes a linear temperature increase as a function
of time. After the heat-up time (t1), the heat-up temperature (T1)
is maintained during a holding time (t2). The heat-up temperature
(T1) is held essentially constant during the entire holding time
(t2). Temperature variations in form of a temperature increase or a
temperature decrease are not illustrated, but may be implemented
within the context of the invention during the holding time (t2) to
affect the desired changes in the material structure, but also for
cost reasons of the production process.
[0044] At the end of the holding time (t2), a first cooldown to a
cooldown temperature (T2) occurs. The temperature hereby decreases
linearly during the cooldown time of the first phase (t3) to the
cooldown temperature (T2). The cooldown temperature (T2) may be in
a range between 100.degree. C. and a heat-up temperature (T1).
[0045] In an immediately following second cooldown phase, an
additional linear temperature decrease takes place during the
cooldown time of the second phase (t4). The temperature can hereby
essentially be lowered to room temperature or to a desired
(unillustrated) target temperature. It would also be feasible
within the context of the invention to include additional cooldown
phases, which are not illustrated.
[0046] FIG. 4b shows a substantially similar temporal arrangement
of the heat treatment, with the difference to FIG. 4a that the
temperature increases progressively during the heat-up time (t1),
whereas the temperature steadily decreases with time (t3, t4)
during the first and second phase of the cooldown.
[0047] FIG. 4c shows, in addition to FIGS. 4a and 4b, that the
temperature curve has a diminishing temperature increase during the
heat-up time (t1) and that the functional dependence of the
temperature decrease over time (t3, t4) is progressive during each
of the various cooldown phases.
[0048] In the context of the invention, it would also be feasible
to combine the temperature dependence over time in mixed forms,
such as progressive, linear and diminishing, and to realize a
temperature change with progressive, diminishing or linear
functional dependence during the holding time (t2).
[0049] While the invention has been illustrated and described in
connection with currently preferred embodiments shown and described
in detail, it is not intended to be limited to the details shown
since various modifications and structural changes may be made
without departing in any way from the spirit and scope of the
present invention. The embodiments were chosen and described in
order to explain the principles of the invention and practical
application to thereby enable a person skilled in the art to best
utilize the invention and various embodiments with various
modifications as are suited to the particular use contemplated.
[0050] What is claimed as new and desired to be protected by
Letters Patent is set forth in the appended claims and includes
equivalents of the elements recited therein:
* * * * *