U.S. patent application number 10/353775 was filed with the patent office on 2003-09-04 for method of making a structural member for use in the automobile industry.
This patent application is currently assigned to BENTELER AUTOMOBILTECHNIK GMBH & CO. KG. Invention is credited to Gehringhoff, Ludger, Gosmann, Stefan, Reinhold, Patrick, Troster, Thomas.
Application Number | 20030163920 10/353775 |
Document ID | / |
Family ID | 27614268 |
Filed Date | 2003-09-04 |
United States Patent
Application |
20030163920 |
Kind Code |
A1 |
Gehringhoff, Ludger ; et
al. |
September 4, 2003 |
Method of making a structural member for use in the automobile
industry
Abstract
In a method of making a structural member for the automobile
industry, a blank of boron steel is pre-formed at ambient
temperature into an intermediary part of a configuration which
substantially corresponds to an end shape of a finished structural
member. The intermediary part is then coated with aluminum or an
aluminum alloy and exposed to a temperature above the upper
transformation line in the TTT curve. Subsequently, the
intermediary part is formed in a mold into the finished structural
member while being hardened at the same time.
Inventors: |
Gehringhoff, Ludger;
(Paderborn, DE) ; Reinhold, Patrick; (Unna,
DE) ; Troster, Thomas; (Salzkotten, DE) ;
Gosmann, Stefan; (Bad Wunnenberg, DE) |
Correspondence
Address: |
Henry M. Feiereisen
Suite 3220
350 Fifth Avenue
New York
NY
10118
US
|
Assignee: |
BENTELER AUTOMOBILTECHNIK GMBH
& CO. KG
Paderborn
DE
|
Family ID: |
27614268 |
Appl. No.: |
10/353775 |
Filed: |
January 28, 2003 |
Current U.S.
Class: |
29/897.2 |
Current CPC
Class: |
C23C 2/12 20130101; Y10T
29/49622 20150115; C23C 2/02 20130101 |
Class at
Publication: |
29/897.2 |
International
Class: |
B21D 053/88 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 6, 2002 |
DE |
102 04 969.6 |
May 7, 2002 |
DE |
102 20 323.7 |
Claims
What is claimed is:
1. A method of making a structural member for use in the automobile
industry, comprising the steps of: shaping a blank of boron steel
at ambient temperature into an intermediary part of a configuration
which substantially corresponds to an end shape of a finished
structural member; coating the intermediary part with aluminum or
an aluminum alloy; heating the intermediary part to a temperature
above the upper transformation line in a TTT curve; and forming the
intermediary part in a mold into the finished structural member at
simultaneous hardening of the structural member.
2. The method of claim 1, wherein the coating step is carried out
at a temperature of about 650.degree. C.
3. The method of claim 1, wherein the coating step is carried out
in a dipping process.
4. The method of claim 1, wherein the temperature above the upper
transformation line in a TTT curve is about 930.degree. C.
5. A method of making a structural member for use in the automobile
industry, comprising the steps of: shaping a blank of boron steel
at ambient temperature into an intermediary part of a configuration
which substantially corresponds an end shape of a finished
structural member; heating the intermediary part to a temperature
above the upper transformation line in the TTT curve; coating the
intermediary part in a melt at a temperature above the upper
transformation line in the TTT curve with aluminum or an aluminum
alloy; and forming the intermediary part in a tool into the
finished structural member at simultaneous hardening of the
structural member.
6. The method of claim 5, wherein the temperature above the upper
transformation line in a TTT curve is about 930.degree. C.
7. A method of making a structural member for use in the automobile
industry, comprising the steps of: shaping a blank of boron steel
at ambient temperature into an intermediary part of a configuration
which substantially corresponds an end shape of a finished
structural member; placing the intermediary part in a melt of
aluminum or an aluminum alloy at a temperature above the upper
transformation line in the TTT curve; coating the intermediary part
in the melt; and forming the intermediary part in a mold into the
finished structural member at simultaneous hardening of the
structural member.
8. The method of claim 7, wherein the temperature above the upper
transformation line in a TTT curve is about 930.degree. C.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims the priority of German Patent
Applications, Serial Nos. 102 04 969.6, filed Feb. 6, 2002, and 102
20 323.7, filed May 7, 2002, pursuant to 35 U.S.C. 119(a)-(d), the
disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates, in general, to a method of
making a structural member for use in the automobile industry.
[0003] Structural members for the automobile industry involve,
e.g., bumpers, side impact carriers or door pillars. A majority of
such structural members are made from boron steel that has been
coated with aluminum. The structural members are hereby made
directly from a heated blank into a finished shape. However,
structural members made of boron steel and coated with aluminum
cannot be made by a single process step into the final
configuration, when the structural members have a complex shape. In
this case, the manufacture of the structural members requires a
succession of cold-forming steps in two or more tools. As a
consequence, the aluminum coat ruptures during the forming process
so that the base material becomes exposed. The protective coating
is thus destroyed.
[0004] It would therefore be desirable and advantageous to provide
an improved method of making structural members for use in the
automobile industry, which method obviates prior art shortcomings
and which is suitable to manufacture even complex shapes of
structural members.
SUMMARY OF THE INVENTION
[0005] To ensure clarity, it is necessary to establish the
definition of important terms and expressions that will be used
throughout this disclosure. The term "ambient temperature" is used
to refer to "room temperature". The terms "TTT curve" or
"time-temperature-transformation curve" are generally known to the
person skilled in the art and relate to diagrams of the
transformation period of steel at different temperatures.
[0006] According to one aspect of the present invention, a method
of making a structural member for use in the automobile industry,
includes the steps of shaping a blank of boron steel at ambient
temperature into an intermediary part of a configuration which
substantially corresponds to an end shape of a finished structural
member, coating the intermediary part with aluminum or an aluminum
alloy, heating the intermediary part to a temperature above the
upper transformation line in the TTT curve, and forming the
intermediary part in a tool into the finished structural member at
simultaneous hardening of the structural member.
[0007] According to another aspect of the present invention, a
method of making a structural member for the automobile industry,
includes the steps of shaping a blank of boron steel at ambient
temperature into an intermediary part of a configuration which
substantially corresponds to an end shape of a finished structural
member, heating the intermediary part to a temperature above the
upper transformation line in the TTT curve, coating the
intermediary part in a melt with aluminum or an aluminum alloy at a
temperature above the upper transformation line in the TTT curve,
and forming the intermediary part in a tool into the finished
structural member at simultaneous hardening of the structural
member.
[0008] According to still another aspect of the present invention,
a method of making a structural member for the automobile industry,
includes the steps of shaping a blank of boron steel at ambient
temperature into an intermediary part of a configuration which
substantially corresponds to an end shape of a finished structural
member, placing the intermediary part in a melt of aluminum or an
aluminum alloy at a temperature above the upper transformation line
in the TTT curve, coating the intermediary part in the melt, and
forming the intermediary part in a tool into the finished
structural member at simultaneous hardening of the structural
member.
[0009] With a method according to the present invention, it is now
possible to make structural members that are made of boron steel
and coated with aluminum and aluminum alloy and that have a complex
configuration, without damage to the coating during the shaping
process.
[0010] 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.
BRIEF DESCRIPTION OF THE DRAWING
[0011] None
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0012] The described embodiments are to be understood as
illustrative of the invention and not as limiting in any way.
[0013] In accordance with a first variation of the present
invention, a blank of boron steel is cut from a coil and, depending
on its complexity, is shaped to an intermediary part in one or more
tools in succession, until the intermediary part has a shape that
substantially resembles the shape of the finished structural member
to be manufactured. Pre-forming of the blank of boron steel is
simple hereby in view of the absence of a coating. After being
shaped to the desired configuration, the intermediary part is
heated to a temperature of about 650.degree. C. and coated with
aluminum or an aluminum alloy, e.g. through a dipping process.
[0014] The intermediary part, after being coated with aluminum or
an aluminum alloy is then heated to a temperature above the upper
transformation line in the time-temperature-transformation curve
(TTT curve) and thereafter shaped in a tool into the end
configuration of the structural member while being hardened at the
same time. The heating temperature is about 930.degree. C.
[0015] In accordance with a second variation of the present
invention, the pre-formed intermediary part, produced by the
shaping process as described in the first variation, is now heated
to a temperature above the upper transformation line in the TTT
curve, e.g. at a temperature of 930.degree. C., and then coated in
a melt with aluminum or an aluminum alloy at a temperature also
above the upper transformation line in the TTT curve. Finally, the
intermediary part is shaped in a tool into the end configuration of
the structural member while being hardened at the same time.
[0016] In accordance with a third variation of the present
invention, the pre-formed intermediary part is heated in an
aluminum melt to a temperature above the upper transformation line
in the TTT curve, e.g. at a temperature of 930.degree. C., and then
shaped in a tool into the end configuration of the structural
member while being hardened at the same time.
[0017] Of course, it is certainly conceivable in all three
variations of a method according to the present invention to
further enhance the quality of the end product by applying an
additional process step, e.g. quenching and tempering.
[0018] 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 of the present
invention. The embodiments were chosen and described in order to
best 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.
[0019] What is claimed as new and desired to be protected by
Letters Patent is set forth in the appended claims and their
equivalents:
* * * * *