U.S. patent application number 11/245733 was filed with the patent office on 2006-05-11 for automotive crush tip and method of manufacturing.
This patent application is currently assigned to Noble Metal Processing, Inc.. Invention is credited to Timothy P. Cripsey, Steven W. Jansen.
Application Number | 20060096099 11/245733 |
Document ID | / |
Family ID | 36314807 |
Filed Date | 2006-05-11 |
United States Patent
Application |
20060096099 |
Kind Code |
A1 |
Cripsey; Timothy P. ; et
al. |
May 11, 2006 |
Automotive crush tip and method of manufacturing
Abstract
Various structural features can be formed in the blank prior to
welding opposing walls of a blank together to form a tubular member
and/or can be formed simultaneously with forming a wall of the
tubular wall. Transverse collapse initiating features can be formed
by expanding the material of the wall. These features can be
located in a corner portion that connects two side wall portions of
the tubular member together and/or in a side wall portion thereof.
In cases where both are provided, the side wall and corner collapse
initiating features can be aligned with each other. Another portion
of the wall material can be free of strain hardening and/or
material thinning. A blank for the tubular member can be formed
from sub-blanks welded together, can have non-parallel opposing
side edges, and/or can have different thickness and/or different
material portions.
Inventors: |
Cripsey; Timothy P.;
(Rochester, MI) ; Jansen; Steven W.; (Northville,
MI) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Assignee: |
Noble Metal Processing,
Inc.
Warren
MI
|
Family ID: |
36314807 |
Appl. No.: |
11/245733 |
Filed: |
October 7, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10976964 |
Oct 29, 2004 |
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11245733 |
Oct 7, 2005 |
|
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PCT/US04/14278 |
May 7, 2004 |
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10976964 |
Oct 29, 2004 |
|
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|
60469029 |
May 8, 2003 |
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Current U.S.
Class: |
29/897.2 ;
293/102; 293/133 |
Current CPC
Class: |
Y10T 29/49622 20150115;
B21D 53/88 20130101 |
Class at
Publication: |
029/897.2 ;
293/102; 293/133 |
International
Class: |
B21D 53/88 20060101
B21D053/88 |
Claims
1. An automotive crush tip comprising: a tubular member having a
longitudinal weld seam joining the opposing side edges of an
integral blank together; a plurality of transverse collapse
initiating features located in the tubular member; wherein at least
a portion of the material of the integral blank and the tubular
member has not been strain hardened.
2. An automotive crush tip according to claim 1, wherein another
portion of the integral blank and the tubular member resulting
therefrom has been strain hardened.
3 An automotive crush tip according to claim 1, wherein a
cross-section of the tubular member varies along a length of the
tubular member.
4. An automotive crush tip according to claim 1, wherein the
integral blank and the tubular member resulting therefrom has a
portion that has one of a thickness, a material and a combination
thereof, that is different from another portion of the integral
blank.
5. An automotive crush tip according to claim 1, wherein the
integral blank and resulting tubular member is constructed of at
least two sub-blanks welded together.
6. An automotive crush tip according to claim 1, wherein the
tubular member further comprises an attachment feature formed
therein.
7. An automotive crush tip according to claim 6, wherein the
attachment feature is selected from the group consisting of a hole,
a flange and a combination thereof.
8. An automotive crush tip according to claim 1, wherein the
plurality of transverse collapse initiating features include a
substantially transversely aligned boundary.
9. An automotive crush tip according to claim 1, wherein the
plurality of transverse collapse initiating features are selected
from the group consisting of a depression, a projection, and a
combination thereof.
10. An automotive crush tip according to claim 9, wherein the
plurality of transverse collapse initiating features include a
substantially transversely aligned boundary.
11. An automotive crush tip comprising: a tubular member having at
least two side wall portions connected together by a corner portion
that is straight; wherein at least one of the at least two side
wall portions has an expanded material portion adjacent the
straight corner portion.
12. An automotive crush tip according to claim 11, further
comprising an unexpanded material portion located in any side wall
portion defined by the tubular member.
13. An automotive crush tip according to claim 11, wherein the
expanded material portion has a boundary that is substantially
transverse to a longitudinal axis of the tubular member.
14. An automotive crush tip according to claim 13, further
comprising a collapse initiating feature substantially aligned with
the boundary of the expanded portion.
15. An automotive crush tip according to claim 11, further
comprising a collapse initiating feature located in the straight
corner portion.
16. An automotive crush tip according to claim 11, wherein the
tubular member has a cross-section that varies along the length of
the tubular member.
17. An automotive crush tip according to claim 11, wherein tubular
member has a longitudinal butt weld seam joining together opposing
side edges of a blank having a portion that has one of a thickness,
a material and a combination thereof, that is different from
another portion of the blank.
18. An automotive crush tip according to claim 11, wherein the
tubular member has a longitudinal butt weld seam joining together
opposing side edges of a blank that is constructed of at least two
sub-blanks welded together.
19. An automotive crush tip according to claim 16, wherein the
expanded material portion is a transverse collapse initiating
feature having a boundary that is substantially transverse to a
longitudinal axis of the tubular member.
20. An automotive crush tip according to claim 19, further
comprising an additional expanded material portion forming an
additional collapse initiating feature located in the straight
corner portion and substantially aligned with the substantially
transverse boundary.
21. An automotive crush tip comprising: a tubular member having at
least one expanded wall area including a wall thickness that has
been thinned, and the tubular member having at least one unexpanded
wall area including a wall thickness that has not been thinned.
22. An automotive crush tip according to claim 21, wherein the
tubular member has a cross-section that varies along the length of
the tubular member.
23. An automotive crush tip according to claim 21, wherein tubular
member has a longitudinal butt weld seam joining together opposing
side edges of a blank having a portion that has one of a thickness,
a material and a combination thereof, that is different from
another portion of the blank.
24. An automotive crush tip according to claim 23, wherein the
blank is constructed of at least two sub-blanks welded
together.
25. An automotive crush tip according to claim 21, wherein the
expanded wall area is a transverse collapse initiating feature.
26. An automotive crush tip according to claim 21, wherein the
expanded wall area has a boundary that is substantially transverse
to a longitudinal axis of the tubular member.
27. An automotive crush tip according to claim 21, wherein the
tubular member further comprises a corner portion including an
additional expanded wall area including a wall thickness that has
been thinned.
28. An automotive crush tip according to claim 22, wherein the
additional expanded wall area is a transverse collapse initiating
feature.
29. An automotive crush tip according to claim 28, wherein the
expanded wall area is a transverse collapse initiating feature and
wherein at least one of the expanded wall area and the additional
expanded wall area has a boundary that is substantially transverse
to a longitudinal axis of the tubular member and that is
substantially aligned with the other of the expanded wall area and
the additional expanded wall area.
30. An automotive crush tip according to claim 29, wherein the
tubular member has a cross-section that varies along the length of
the tubular member.
31. A method useful for manufacturing an automotive crush tip,
comprising: forming a blank having opposing longitudinal side
edges; forming the blank into a substantially tubular member
wherein the opposing longitudinal side edges are adjacent each
other; welding the opposing longitudinal side edges of the blank
together; forming at least one structural feature in the blank
prior to welding the opposing longitudinal side edges together.
32. A method useful for manufacturing an automotive crush tip
according to claim 31, wherein forming the blank further comprises
forming opposing longitudinal side corner portions that are not
parallel with each other.
33. A method useful for manufacturing an automotive crush tip
according to claim 31, wherein forming the blank further comprises
welding at least two sub-blanks together.
34. A method useful for manufacturing an automotive crush tip
according to claim 31, wherein forming the blank further comprises
providing a portion of the blank with one of a material, a
thickness and a combination thereof that is different from another
portion of the blank.
35. A method useful for manufacturing an automotive crush tip
according to claim 31, wherein forming at least one structural
feature comprises forming one of a transverse collapse initiating
feature, an attachment feature, and a combination thereof.
36. A method useful for manufacturing an automotive crush tip
according to claim 31, wherein forming the blank into a shape of a
substantially tubular member comprises forming a substantially
straight corner portion between two side wall portions of the
substantially tubular member.
37. A method useful for manufacturing an automotive crush tip
according to claim 36, wherein forming the at least one structural
member comprises forming a collapse initiating feature in the
substantially straight edge.
38. A method useful for manufacturing an automotive crush tip
according to claim 36, wherein forming the at least one structural
member comprises forming a collapse initiating feature in at least
one of the two side wall portions of the substantially tubular
member.
39. A method useful for manufacturing an automotive crush tip
according to claim 37, wherein forming the at least one structural
member comprises forming a collapse initiating feature in at least
one of the two side wall portions of the substantially tubular
member.
40. A method useful for manufacturing an automotive crush tip
according to claim 39, wherein forming the blank further comprises
forming opposing longitudinal side edge segments that are not
parallel with each other.
41. A method useful for manufacturing an automotive crush tip,
comprising: forming a substantially flat blank having opposing side
edges; forming the substantially flat blank into a wall having a
partially tubular shape; forming the wall into a substantially
tubular shape wherein the opposing side edges are adjacent to each
other; welding the opposing side edges together to form the wall
into a tubular shape; and forming at least one structural feature
in the wall simultaneously with at least one of forming a
substantially flat blank, forming a partially tubular wall, and
forming a substantially tubular wall.
42. A method useful for manufacturing an automotive crush tip
according to claim 41, wherein forming at least one structural
feature comprises forming an attachment feature, a transverse
collapse initiating feature, and a combination thereof.
43. A method useful for manufacturing an automotive crush tip
according to claim 42, wherein forming at least one structural
feature comprises forming a transverse collapse initiating feature
in one of a depression, a protrusion, and a combination
thereof.
44. A method useful for manufacturing an automotive crush tip
according to claim 43, wherein the at least one structural feature
is located in a corner portion located between two side wall
portions of the wall.
45. A method useful for manufacturing an automotive crush tip
according to claim 43, wherein the at least one structural feature
is located in a side wall portion of the wall.
46. A method useful for manufacturing an automotive crush tip
according to claim 45, wherein at least one additional structural
feature is located in a corner portion located between two side
wall portions of the wall.
47. A method useful for manufacturing an automotive crush tip
according to claim 41, wherein forming the substantially flat blank
comprises providing one of the opposing longitudinal side edges
with a portion that is not parallel to the other of the opposing
longitudinal side edges.
48. A method useful for manufacturing an automotive crush tip
according to claim 41, further comprising forming the substantially
flat blank from at least two sub-blanks welded together.
49. A method useful for manufacturing an automotive crush tip
according to claim 41, wherein forming the substantially flat blank
comprises providing a portion of the blank having one of a
material, a thickness, and a combination thereof, that is different
from another portion of the blank.
50. A method useful for manufacturing an automotive crush tip
according to claim 49, wherein forming the blank further comprises
forming opposing longitudinal side edge segments that are not
parallel with each other.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S.
application Ser. No. 10/976,963 filed Oct. 29, 2003, which is a
continuation of International Application No. PCT/US2003/013278
filed May 7, 2003, which claims the benefit of U.S. Provisional
Application No. 60/639,029 filed May 8, 2003 and which claims
priority to U.S. application Ser. No. 10/757,967 filed Jan. 13,
2003, which claims the benefit of U.S. Provisional Application No.
60/339,907 filed Jan. 13, 2003. This application additionally
claims the benefit of U.S. Provisional Application No. 60/617,394,
filed on Oct. 8, 2003. The entire contents of the disclosures of
the above applications are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to tubular members designed to
collapse generally transverse to a longitudinal axis thereof in the
event of an impact thereto in order to absorb energy and
press-forming methods of manufacturing such tubular members.
BACKGROUND OF THE INVENTION
[0003] This patent application applies to automotive crush tips
which are integrated in an automotive structure to absorb energy in
the event of a collision. Crush tips are designed to collapse
generally along their length to absorb energy in the event of a
front or rear end collision, thereby minimizing damage to occupants
for both vehicles involved in the crash. Consequently, crush tips
have longitudinal axes which are generally oriented parallel with
the longitudinal axis of the vehicle between its front and
back.
[0004] Automotive crush tips are typically manufactured by MIG
welding two overlapping press formed C-channels. Using this
manufacturing process two separate C-channels are first formed.
Then they are brought together in facing relationship and
accurately positioned so that the ends overlap each other slightly.
Then a welding operation--typically MIG welding--is performed along
each of the overlapping ends to create two welded seams. Then
attachment flanges or other features are typically welded to the
C-channels to finalize the manufacturing process.
[0005] More recently, tube hydroforming has also been used as
another viable option for manufacturing automotive crush tips. In
this manufacturing process, a tube is first formed. The tube is
then subjected to a hydroforming process. During hydroforming,
fluid pressure is applied to the interior of the tube, causing the
tube to expand and conform to a surrounding mold cavity. Like the
C-channel process, attachment flanges or other features are then
typically welded to the hydroformed structure to finalize the
manufacturing process.
[0006] Each of these manufacturing processes has various
disadvantages. For example, they are both generally inefficient
and/or costly. For example, additional unnecessary weight results
from using overlapping C-channels. In addition, there can be
significant limitations in the geometry and/or structure of the
final product as a result of the manufacturing process. MIG welding
two seams can also create undesireable localized stresses, for
example, due to the heat involved. With hydroforming, for example,
large portions of the crush tube material are thinned and work
hardened, thereby decreasing its energy absorbing properties.
[0007] Further, they have various disadvantages when today's
high-strength steels are used to form the crush tips. For example,
hydroforming can require substantial forming pressures when
high-strength steel is used. In addition, many high strength steels
are not suitable for the typical MIG welding process.
SUMMARY OF THE DISCLOSURE
[0008] In one aspect of the disclosure an automotive crush tip
includes a tubular member having a longitudinal weld seam joining
the opposing side edges of an integral blank together. The
automotive crush tip includes a plurality of transverse collapse
initiating features located in the tubular member. At least a
portion of the material of the integral blank and the tubular
member has not been strain hardened.
[0009] In another aspect of the disclosure an automotive crush tip
includes a tubular member having at least two side wall portions
connected together by a corner portion that is straight. At least
one of the at least two side wall portions has an expanded material
portion adjacent the straight corner portion.
[0010] In an additional aspect of the disclosure an automotive
crush tip includes a tubular member having at least one expanded
wall area including a wall thickness that has been thinned, and the
tubular member having at least one unexpanded wall area including a
wall thickness that has not been thinned.
[0011] In yet another aspect of the disclosure a method useful for
manufacturing an automotive crush tip includes forming a blank
having opposing longitudinal side edges. In addition, the blank is
formed into a substantially tubular member wherein the opposing
longitudinal side edges are adjacent to each other. The opposing
longitudinal side edges of the blank are welded together. At least
one structural feature is formed in the blank prior to welding.
[0012] In a further aspect of the disclosure a method useful for
manufacturing an automotive crush tip includes forming a
substantially flat blank having opposing side edges. The
substantially flat blank is formed into a wall having a partially
tubular shape. The wall is formed into a substantially tubular
shape wherein the opposing side edges are adjacent to each other.
The opposing side edges are welded together to form the wall into a
tubular shape. at least one structural feature is formed in the
wall simultaneously with at least one of forming a substantially
flat blank, forming a partially tubular wall, and forming a
substantially tubular wall.
[0013] Further areas of applicability of the present invention will
become apparent from the detailed description provided hereinafter.
It should be understood that the detailed description and specific
examples, while indicating the preferred embodiment of the
invention, are intended for purposes of illustration only and are
not intended to limit the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The present invention will become more fully understood from
the detailed description and the accompanying drawings,
wherein:
[0015] FIG. 1 is a perspective view of an exemplary embodiment of a
crush tip from the front thereof;
[0016] FIG. 2 is a perspective view of the exemplary embodiment of
the crush tip of FIG. 1 from the back thereof;
[0017] FIG. 3 is a perspective view of an exemplary blank for
forming the crush tip of FIG. 1;
[0018] FIG. 4 is a perspective view of the blank of FIG. 3 after it
has been subjected to some initial press-forming operation(s);
[0019] FIG. 5 is a perspective view of the blank of FIG. 3 after it
has been subjected to some additional press-forming
operation(s);
[0020] FIG. 6 is a perspective view of the blank of FIG. 5 in the
form of a substantially tubular member;
[0021] FIG. 7 is a perspective view of the blank of FIG. 5 in the
form of a tubular member including a longitudinal weld seam;
[0022] FIG. 8 is a perspective view of another exemplary embodiment
of a crush tip from the front thereof;
[0023] FIG. 9 is a perspective view of the exemplary embodiment of
the crush tip of FIG. 8 from the back thereof;
[0024] FIG. 10 is a perspective view of an exemplary blank for
forming the crush tip of FIG. 8;
[0025] FIG. 11 is a perspective view of the blank of FIG. 10 after
it has been subjected to some initial press-forming
operation(s);
[0026] FIG. 12 is a perspective view of the blank of FIG. 11 after
it has been subjected to some additional press-forming
operation(s);
[0027] FIG. 13 is a perspective view of the blank of FIG. 12 in the
form of a substantially tubular member;
[0028] FIG. 13 is a perspective view of the blank of FIG. 13 in the
form of a tubular member including a longitudinal weld seam;
[0029] FIG. 15 is a top plan view of a third exemplary blank for
forming a crush tip;
[0030] FIG. 16 is a top plan view of a forth exemplary blank for
forming a crush tip; and
[0031] FIG. 17 is a flow chart describing a press-forming
manufacturing process for shaping substantially flat blanks into
additional embodiments of tubular crush tips.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0032] The following description of the preferred embodiment(s) is
merely exemplary in nature and is in no way intended to limit the
invention, its application, or uses. As but one example, although
the crush tip of the embodiments illustrated herein have tubular
members with a generally rectangular cross-section, other
cross-sectional shapes are possible such as circular, hexagonal,
square, and/or combinations thereof.
[0033] Referring to FIGS. 1 and 2, an exemplary embodiment of a
crush tip 10 is illustrated as a substantially tubular member 12
defined by two side walls 14, a top wall 16 and a bottom wall 18.
Each side wall 14 is connected to the bottom wall 18 along
respective corner portions 20, that can be straight. Each side wall
14 is also connected to the top wall 16 along respective corner
portions 20 that are comprised of two straight (generally
longitudinally oriented) segments 20' and 20'' joined together at
an angle with respect to each other. A longitudinal weld seam 21 is
provided in the top wall 16 as seen in FIG. 7. The cross-section of
the tubular member 12 defined by the walls 14, 16, 18 varies along
its longitudinal axis. In other words, the overall dimensions
and/or the overall shape of the transverse cross-section of the
tubular member 12 is different at different points along the length
of the tubular member 12.
[0034] The tubular member 12 includes a plurality of various
structural features. The structural features can be attachment
features and/or transverse collapse initiating features. With
respect to attachment features, for example, the side walls 14 of
the tubular member 12 include a plurality of openings 22. At least
some of these openings 22 can be used in attaching the crush tip 10
to components of an automobile. In addition, end flanges 24 or
other edge attachments can be provided for attaching the crush tip
10 to automobile components.
[0035] Another example of structural features that can be provided
are transverse collapse initiating features. These transverse
collapse initiation features help facilitate collapse of the crush
tip 10 in a direction that is generally transverse to a
longitudinal axis of the tubular member 12. These transverse
collapse initiating features can be protrusions or depressions that
are formed in a blank while it is in its flat configuration or as
the blank is being formed into a tubular member 12 as described
hereinafter.
[0036] For example, depressions 26 that extend inwardly can be
formed in the corner portions 20 connecting the two side walls 14
to the top wall 16 and the bottom wall 18 of the tubular member 12.
These depressions 26 are formed as darts that have boundaries that
can be substantially transverse to a longitudinal axis of the
tubular member 12. Such substantially transverse boundaries can aid
the generally transverse collapse of the crush tip 10. Because
these darts 26 are formed by expanding an area of material as
discussed hereinafter, the material can be thinned and/or strain
hardened relative to the surrounding material of the tubular member
12.
[0037] Collapse initiating features in the form of protrusions 28
that extend outwardly are also provided. Two protrusions 28 are
located in each side wall 14. Each of the protrusions 28 are
positioned in each side wall 14 adjacent at least one straight
corner portion 20. In this embodiment, the two protrusions 28 are
located in the side walls 14 adjacent the straight corner portions
20' connecting each side wall 14 with the bottom wall 18.
Additionally, the two protrusions 28 are located in each side wall
14 adjacent straight corner portions 20' connecting the side wall
14 with the top wall 16. Although. "side wall", "top wall", and
"bottom wall" are referred to herein to aid in clarity, each of
these walls 14, 16, 18 is also generically referred to herein as a
"side wall" or "wall" of the tubular member 12.
[0038] Like the depressions 26, these protrusions 28 can include at
least one boundary 28' that is substantially transverse to the
longitudinal axis of the tubular member 12. Each of the transverse
boundaries 28' of the protrusions 28 can be generally aligned with
one of the depressions 26 and visa versa. In addition, the
substantially transverse boundary 28' of the protrusion 28 can be
substantially aligned with a transverse boundary 26' of a
depression 26 or another collapse initiating feature. Such
alignment configurations can further facilitate collapsing of the
crush tip 10 generally along its longitudinal length as a result of
the crush initiation features 26, 28. These protrusions 28 can be
formed by expanding an area of material and the material can be
thinned and/or strain hardened relative to the surrounding material
of the tubular member 12 as a result.
[0039] Referring to FIG. 3, a blank 30 used to form an exemplary
embodiment of an automobile crush tip 10 is provided. The blank 30
can be initially substantially flat. The blank 30 includes portions
32' of opposing longitudinal side edges 32 that are not parallel
(i.e., they are angled) with respect to each other. Thus, the
portion of the flat blank 30 of this embodiment that corresponds to
the opposing longitudinal side edges 32' that are not parallel has
a generally trapezoidal shape. In addition, the blank 30 includes
portions 32'' of opposing longitudinal side edges 32 that are
parallel with each other. Thus, the corresponding portion of the
flat blank 30 has a generally rectangular shape. Because the flat
blank 30 includes opposing side edges 32' that are not parallel to
each other, the cross-section of the resulting tubular member 12
varies along its longitudinal length.
[0040] Various structural features can be formed in the blank 30 as
desired. One example of such structural features are attachment
features which can include attachment openings 22 and attachment
flanges 24. For example, attachment openings 22 can be formed as
part of the process of forming the blank 30 using a blanking die.
In addition, attachment features can include end flanges 24 that
can be formed as part of the process of forming the blank 30 using
a blanking die. These attachment features can alternatively be
formed as a separate step from that of forming the substantially
flat blank 30. For example, the attachment openings 22 can be
formed as a result of a separate piercing step. It can be
preferable to form all or most of these structural features prior
to welding the longitudinal seam 21 of the tubular member 12 as
described hereinafter.
[0041] Referring to FIG. 4, the blank 30 is illustrated as having
been subjected to a partial forming operation, resulting in a wall
having a partially tubular shape which can include one or more
separate steps. Several structural features have been at least
partially formed as a result of this partial forming operation,
which can occur as one simultaneous step or as sequential steps.
The end flanges 24 have been partially formed and trimmed as part
of a single step. Alternatively, the end flanges 24 may be
partially formed and trimmed as two separate steps. Similarly, the
longitudinal side edges 32 can be trimmed, for example, as part of
the blank 30 forming process or using a separate skiving
operation.
[0042] In this embodiment, two sections 16' of the top wall 16 are
bent up at roughly a 90 degree angle along each of the opposing
side edges 32. Thus, the bend forms a corner portion 20 between two
side wall portions 16'. The corner portion 20 can be formed as part
of a press-forming operation. In addition, the collapse initiating
depressions 26 can be formed in the corner portions 20.
Furthermore, the collapse initiating protrusions 28 can be formed
using appropriate male and female die components. It can be
preferable to form all of these components as part of a single die
strike that includes the wall press-forming operation.
Alternatively, multiple sequential die strikes and/or press-forming
operations can be used.
[0043] Referring to FIG. 5, the blank 30 is subjected to a
subsequent press-forming operation to create a corner portion 20
between each of the side walls 14 and the bottom wall 18 of the
blank 30. As part of this press-forming operation additional
collapse initiating depressions 26 can be press-formed into the
newly created corner portions 20 connecting the side walls 14 to
the bottom wall 18. Again, the wall formation and the collapse
initiating depression formation can occur simultaneously or
sequentially. Simultaneous forming of such features can be
preferred. The side edges 32 can be trimmed, if it has not already
been done. As illustrated in FIGS. 4 and 5, the substantially flat
blank 30 has been formed into a wall (comprised of top wall
sections 16', side walls 14 and bottom wall 18) having a partially
tubular shape.
[0044] Referring to FIG. 6, the side walls 14 are then moved
together so that the side edges 32 are located adjacent to each
other to form a substantially tubular member. Because the material
of the blank 30 has a tendency to spring back there is typically a
gap extending longitudinally between the opposing side edges 32. As
illustrated in FIG. 6, the wall (comprised of top wall sections
16', side walls 14 and bottom wall 18) has been formed into a
substantially tubular shape.
[0045] Referring to FIG. 7, an opposing force can be applied to
opposing side walls 14 of the substantially tubular member 12 to
bring the longitudinal side edges 32 into a zero gap configuration.
With the side edges 32 in this position, the side edges 32 are
welded together along weld line 21, thereby forming the tubular
member 12. Any suitable welding operation can be used, including
laser welding, gas metal arc welding, Tungsen inert gas, high
frequency welding, mash seam welding, friction stir welding, or the
like. Laser welding can be a preferred welding process. As
illustrated in FIG. 6, the wall (comprising top wall 16, side walls
14 and bottom wall 18) has been formed into a tubular shape,
thereby creating a tubular member 12.
[0046] As a result of this forming process, portions of the
material that define the crush tip 10 have been expanded, which can
result in the material being thinned and/or which can result in
strain hardening of the material. For example, the transverse crush
initiating features are protrusions 28 and/or depressions 26 that
are expanded from an initially substantially flat sheet of
material, thereby thinning and/or work hardening the material. The
remaining portions of the crush tip 10 can be made from material
that has not been expanded, thinned and/or work hardened.
[0047] In contrast, hydroforming typically provides more hardening
and/or material thinning. In fact, with hydroforming, material
thinning and/or strain hardening can extend over substantially the
entire surface area of the crush tip. Thus, hydroforming can result
in an all over reduction in capacity for absorbing energy. It can
be preferable that the expansion, work hardening and/or material
thinning of this press-forming process occurs over 75% or less of
the surface area or the crush tip 10; more preferably, 60% or less;
and even more preferably 50% or less. The press-forming process
also provides sharp feature realization and enhances the function
of structural features of the crush tip 10.
[0048] Also as a result of the above-described manufacturing
process, there can be no need to perform any post-welding shaping
operations. In many cases, the tubular member 12 that results from
welding the longitudinal seam 21 provides a crush tip 10 in its
substantially final shape. In other words, subsequent minor shaping
operations may occur, such as bending an attachment flange
outwardly. It can be preferred, however, that none of the material
expanding that results in material thinning and/or work hardening
occurs after the welding of the longitudinal seam 21.
[0049] Referring to FIGS. 8 and 9, another embodiment of an
exemplary crush tip 110 includes a first portion 112' of the
tubular member 112 that has one of a material, a thickness, or
both, that is different from another portion 112'' of the tubular
member 112. In this embodiment, the tubular member 112 can be
formed from a substantially flat blank that comprises two
sub-blanks as described hereinafter. Of course, the previous
embodiment could also be formed of two sub-blanks welded together.
The first sub-blank, and therefore a first portion 112' of the
tubular member 112, has a thickness that is different from the
second sub-blank, and therefore from a second portion 112'' of the
tubular member 112. In addition, the material of the first
sub-blank and corresponding tubular portion 112' is a different
material than the material of the second sub-blank and
corresponding tubular portion 112''.
[0050] Similar to the embodiment of FIGS. 1 and 2, the tubular
member of this embodiment includes transverse crush initiation
features in the form of depressions 126 as darts located in the
straight corner portion 120 joining the side walls 114 with the top
wall 116 and bottom wall 118. This embodiment also includes
attachment features in the form of attachment flanges 124 extending
from the ends of the tubular member. Each of the attachment flanges
124 includes an aperture 125 therein for receiving a fastener. The
attachment flanges 124 can be left in their generally
longitudinally extending direction as illustrated. Alternatively,
the attachment flanges 124 can be bent into a generally
transversely extending direction.
[0051] Referring to FIG. 10, a blank 130 used to form an exemplary
embodiment of the automobile crush tip 110 of FIGS. 8 and 9 is
illustrated. The blank 130 is initially flat and has a generally
trapezoidal overall shape including opposing side edges 132 that
are not parallel. This blank however, is formed from two sub-blanks
131, 133. The first sub-blank 131 is made from a material that is
different than that of the second-sub-blank 133. For example, the
first sub-blank 131 can be made of steel and the second sub-blank
133 could be made of a different, high strength, steel. An
alternative way to provide a first sub-blank 131 that is of a
different material than a second sub-blank 133 is to treat or
surface coat one of the sub-blanks 131, 133, thereby giving the
sub-blanks 131, 133 different material properties. As one possible
variant, one of the sub-blanks 131, 133 can be subjected to a heat
treating process that alters the structure of the steel.
[0052] In addition, the first sub-blank 131 can have a material
thickness that is thinner than that of the second sub-blank 133.
The first sub-blank 131' and the second sub-blank 133 can be welded
together along a boundary or joint line 137. Any suitable welding
operation can be used, including laser welding, gas metal arc
welding, Tungsen inert gas, high frequency welding, mash seam
welding, friction stir welding, or the like. Laser welding can be a
preferred welding process. As used herein, the term "sub-blank"
refers both to those instances where separate blanks are joined
together and to those instances where portions of a one-piece blank
are different from each other.
[0053] Attachment features in the form of apertures 122 can be
stamped along with the forming of the blank 130 or sub-blanks 131,
133. Alternatively, the apertures 122 can be formed as part of a
piercing operation. This piercing operation can be a completely
separate step, or it can be a part of a forming operation or
press-forming operation associated with forming up the walls (e.g.,
16', 16''). In addition the piercing operation can occur
simultaneously or sequentially with wall forming operations.
[0054] Referring to FIG. 11, the blank 130 is illustrated as having
been subjected to a partial wall forming operation, which can
include one or more simultaneous or sequential steps. Several
features have been formed as a result of this partial forming
operation. In this embodiment, two segments of the top wall 116',
116'' are bent up at roughly a 90 degree angle adjacent each of the
opposing side edges 132. Thus, the bend forms a corner portion 120
between two top wall portions 116', 116'' and the adjacent portion
of the blank 130. The corner portions 120 can be formed as part of
a press-forming operation. In addition, the collapse initiating
depressions 126 are formed in the corner portions 120. It can be
preferable to form all of these components as part of a single die
strike that includes the press-forming operation. Alternatively,
multiple die strikes and/or press-forming operations can be
used.
[0055] Referring to FIG. 12, the blank is subjected to a subsequent
press-forming operation to create a corner portion 120 between each
of the side walls 114 and the bottom wall 118 of the blank 130. As
part of this press-forming operation, additional collapse
initiating depressions 126 can be press-formed into the blank.
Alternatively these collapse initiating depressions 126 can be
formed separately from this press-forming operation forming the
corner portions 120. If it has not already been done, the opposing
longitudinal side edges 132 can then be trimmed, or subjected to a
skiving operation in order to ensure a good fit between the
opposing side edges 132.
[0056] Referring to FIGS. 13 and 14, the sides are then moved
together so that the opposing side edges 132 are located adjacent
to each other to form a substantially tubular member. An opposing
force can be applied to each of the opposing sides of the
substantially tubular member to bring the longitudinal side edges
132 into a zero gap configuration. With the side edges 132 in this
position, the side edges 132 can be welded or otherwise joined
together along a longitudinal joint line 121 as discussed
above.
[0057] FIGS. 15 and 16 illustrate various substantially flat blanks
230, 330 that can be used to create alternative crush tip
embodiments. These substantially flat blanks 230, 330 as
illustrated each include three sub-blanks 231, 233 and 235; and
331, 333, and 335, respectively. Boundary lines or joint lines 237,
337 define each sub-blank relative to the adjacent sub-blanks.
Joining separate sub-blanks together, for example, by welding, can
create the boundary lines or joint lines 237, 337. In addition, one
section of a single one-piece blank can be coated or otherwise
treated to provide a sub-blank having a different material than
that of another untreated portion defining another sub-blank. As
another alternative, different sections of a one-piece blank can be
rolled to different thicknesses to create the sub-blanks.
[0058] In all of the instances outlined above, the integral
substantially flat blank 230, 330 includes a boundary line or joint
237 and 337, respectively, line between the sub-blanks thereof. The
boundary lines 237, 337 can take on a variety of shapes. For
example, the boundary lines 237 of FIG. 15 are aligned
substantially transversely to the longitudinal axis of the blank
230. The boundary lines 337 of FIG. 16 have both lateral and
transverse directional components. Although the boundary lines 237,
337 of these embodiments are illustrated as being straight, the
boundary lines may also include arcuate shapes. In addition,
although the boundary lines 237, 337 of these embodiments are
illustrated as being parallel to the other boundary lines of the
blank 230, 330, a blank can include a boundary lines that are
different from the other boundary lines of a blank. Further, the
thickness of the boundary line can be variable. Thus, a large
degree of flexibility is provided to design the collapse
characteristics of a crush tip made using these blanks.
[0059] Referring to a specific embodiment of a blank 230 in
accordance with FIG. 15, the illustrated flat blank 230 is
comprised of three separate sub-blanks 231, 233, 235. Each of
sub-blanks 231 and 233 are rolled from a single piece of material,
but the material of sub-blank 231 is rolled to a thinner dimension
than that of sub-blank 233. Thus, a difference in thickness occurs
at boundary line 237 between sub-blank 321 and sub-blank 233.
Sub-blank 235 is initially formed from a separate piece of the same
material having the same thickness as that of sub-blank 233. The
material of this sub-blank 235, however, is subjected to a heat
treatment process which alters the material of the sub-blank 235.
Thus, sub-blank 235 has a different material than that of sub-blank
233 and has both a different material and a different thickness
than that of sub-blank 231. Sub-blank 235 can be welded to
sub-blank 233 along the corresponding joint or boundary line
237.
[0060] Referring to a specific embodiment of a blank 330 in
accordance with FIG. 16, the illustrated flat blank 330 is
comprised of three separate sub-blanks 331, 333, 335. Each of the
sub-blanks 331, 333, 335 can be stamped or otherwise formed from
flat sheets of different material having different thicknesses.
Each of the end sub-blanks 331 and 335 is then joined to the
central sub-blank 333 along a corresponding joint line or boundary
line 337. The sub-blanks 331, 333, 335 can be joined together by a
welding operation that is suitable for the material, including
laser welding, gas metal arc welding, Tungsen inert gas, high
frequency welding, mash seam welding, friction stir welding, or the
like.
[0061] Referring to FIG. 17, each of the blanks of FIGS. 15 and 16
can be formed into other embodiments of a crush tip using a
progressive or transfer die press-forming process as outlined
therein and as described above. As noted in block 40 a blank is
loaded or coil fed into a forming station. The blank referred to
therein is an integral, substantially flat blank from which the
tubular member is formed. As indicated in block 42, this integral
blank can be subjected to one or more operations, either
simultaneously or sequentially. For example, the integral blank can
be trimmed. Additionally, holes can be pierced or otherwise formed
therein. Further, structural features can be formed therein as a
result of a press forming operation. The structural features can
include attachment features and/or the transverse collapse
initiating features. In addition, wall components of the tubular
member can be partially formed by press-forming corner portions to
create wall sections separated thereby.
[0062] The integral blank discussed above with respect to blocks 40
and 42 can be formed from sub-blanks which may, themselves, have
been subjected to steps similar to those of blocks 40 and 42. For
example a blank for a sub-blank can be loaded or coil fed into a
forming station. This sub-blank can be trimmed, for example, prior
to joining with other sub-blanks. As discussed above, the
sub-blanks can then be joined together by welding to create an
integral blank having joint lines or boundary lines. Although the
sub-blank may be subjected to a piercing operation to form holes
therein and/or have features press-formed therein, it can be
preferred that these operations occur after the sub-blanks have
been joined together into an integral blank.
[0063] Referring to blocks 44 and 46, additional press forming
operations can be provided to form additional features, either
simultaneously or sequentially. For example, wall components of the
tubular member can be more completely formed by further
press-forming corner portions to create wall sections separated
thereby and to form the blank into a substantially tubular member.
Simultaneously or sequentially, further structural features can be
formed therein as a result of a press forming operation and/or
holes can be pierced or otherwise formed therein.
[0064] Referring to block 48, the substantially tubular member that
is formed above provides the opposing side walls adjacent to each
other with a small gap therebetween. Opposing forces can be applied
to the substantially tubular member to hold the gap closed and then
the opposing side edges can be welded together to form a
longitudinal butt weld seam. As indicated in block 50, the final
part is then unloaded. As noted above, it can be preferred that no
post welding forming steps occur. In some cases. holes or other
features can alternatively be created after the tube is formed;
particularly where tight tolerances are required.
[0065] The description of the invention is merely exemplary in
nature and, thus, variations that do not depart from the gist of
the invention are intended to be within the scope of the invention.
Such variations are not to be regarded as a departure from the
spirit and scope of the invention.
* * * * *