U.S. patent application number 10/940250 was filed with the patent office on 2005-04-21 for vehicle structural beam and method of manufacture.
This patent application is currently assigned to Pullman Industries, Inc.. Invention is credited to Bladow, Jeffrey L., Hackstock, Gerald, McNulty, Frank G..
Application Number | 20050082346 10/940250 |
Document ID | / |
Family ID | 26905828 |
Filed Date | 2005-04-21 |
United States Patent
Application |
20050082346 |
Kind Code |
A1 |
McNulty, Frank G. ; et
al. |
April 21, 2005 |
Vehicle structural beam and method of manufacture
Abstract
A vehicle structural beam, such as a door intrusion beam, which
possesses an elongate tubular beam part which at opposite ends is
provided with mounting flanges for securement to a vehicle frame.
The elongate tubular beam part and the flanges provided at opposite
ends are defined by an integral, one-piece, monolithic steel
structure which has been initially roll-formed from an elongate
flat metal sheet to define the closed tubular structure of the
tubular beam part, and which has been subjected to heating and
quenching so that the elongate tubular beam part is of relatively
high strength steel throughout its entire length, whereas the
integrally and monolithically joined end flanges remain as lower
strength steel which has been significantly unaffected by the heat
treatment and quenching so as to permit appropriate shaping thereof
and ease of welding to the vehicle frame.
Inventors: |
McNulty, Frank G.;
(Rochester Hills, MI) ; Hackstock, Gerald; (Clay
Township, MI) ; Bladow, Jeffrey L.; (West Bloomfield,
MI) |
Correspondence
Address: |
FLYNN THIEL BOUTELL & TANIS, P.C.
2026 RAMBLING ROAD
KALAMAZOO
MI
49008-1699
US
|
Assignee: |
Pullman Industries, Inc.
|
Family ID: |
26905828 |
Appl. No.: |
10/940250 |
Filed: |
September 14, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10940250 |
Sep 14, 2004 |
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10200546 |
Jul 22, 2002 |
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6793743 |
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10200546 |
Jul 22, 2002 |
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09777379 |
Feb 6, 2001 |
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6454884 |
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60211100 |
Jun 12, 2000 |
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Current U.S.
Class: |
228/173.4 |
Current CPC
Class: |
B60J 5/0437 20130101;
B21D 53/88 20130101; B21D 5/086 20130101; B60J 5/0444 20130101;
Y10S 148/902 20130101 |
Class at
Publication: |
228/173.4 |
International
Class: |
B23K 001/20 |
Claims
1-24. (canceled)
25. A method of forming a metallic item comprising the steps of:
trimming the opposed lateral edges of a continuous metal blank to
create a plurality of cut-outs in the opposed lateral edges;
forming the continuous metal blank into a tubular shape; welding
along the length of the tubular shape, whereby the lateral edges
are joined only in the areas between the cut-outs; cutting the
welded tubular shape in the areas of the cut-outs thereby creating
a plurality of items; and opening an end of each item to create a
non-tubular portion on the item.
26. A method as defined in claim 25 wherein said step of opening an
end further comprises the step of angling a portion of the end.
27. A method of forming an item comprising the steps of: trimming a
continuous metal strip to form a plurality of indentations in the
opposed lateral edges; rollforming the continuous metal strip into
a continuous tubular shape wherein the opposed lateral edges engage
each other; welding the engaging untrimmed lateral edges of the
continuous tubular shape; cutting the welded continuous tubular
shape in the area of the indentations thereby creating a plurality
of items; and opening an end of each item to create a non-tubular
end.
28. A method as defined in claim 27 wherein said opening step
includes opening both ends of each item to create non-tubular
ends.
29. A method as defined in claim 27 further comprising the step of
forming an angled bracket from the end.
30. A method of forming doorbeams comprising the steps of:
providing a continuous web of flat stock having a pair of opposed
linear edges; trimming at least one of the linear edges at spaced
locations along the length of the flat stock creating trimmed edges
and leaving untrimmed edges; forming the trimmed flat stock into a
generally tubular shape with the untrimmed linear edges engaging
one another; welding the engaging untrimmed lateral edges of the
generally tubular shape; severing the welded tubular shape in the
area of the trimmed lateral edges thereby creating a plurality of
tubular lengths; and opening at least one end of each tubular
length in the area of the trimmed edges to create a bracket.
31. The method of claim 30 wherein said step of opening at least
one end of the tubular length further comprises a final forming
step of forming a relatively flat end on the tubular length in the
area of the trimmed edges.
32. The method of claim 31 further comprising the step of angling
the relatively flat end.
33. A method of forming doorbeams comprising the steps of:
providing a continuous web of sheet stock having a pair of lateral
edges; forming the continuous web into a generally closed
configuration with at least portions of the lateral edges engaging
one another; joining the engaging portions of the lateral edges in
first longitudinal segments separated by unjoined portions of the
lateral edges in second longitudinal segments; severing the joined
closed configuration in the unjoined second longitudinal segments
thereby creating a plurality of lengths; and opening at least one
end of each length to create a bracket.
34. The method of claim 33 further comprising the step of forming a
relatively flat bracket.
35. The method of claim 33 further comprising the step of forming
an angled portion in the bracket.
36. The method of claim 33 wherein said step of joining the lateral
edges includes welding.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This invention relates to co-pending U.S. provisional
application Ser. No. 60/211 100, filed Jun. 12, 2000, the entire
disclosure of which is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention relates to a structural beam, particularly
for a vehicle such as an automobile or truck, and to an improved
beam construction and an improved process for manufacture
thereof.
BACKGROUND OF THE INVENTION
[0003] Automotive vehicles such as automobiles and trucks employ a
significant number of different structural beams associated with
the vehicle frame to provide strength and rigidity. Many such beams
are intended to provide increased protection for the vehicle
occupants in the event of a collision or other accident. For
example, a conventional door for a vehicle such as an automobile or
truck has a hollow frame with vertical side rails, a bottom rail
and a top rail. A structural door intrusion beam is typically
disposed interiorly of the frame at a location spaced upwardly from
the bottom rail and extends generally horizontally between and has
opposite ends fixed to the side rails. The door intrusion beam thus
provides improved strength against side impact on the vehicle door
so as to provide improved protection for a passenger in the event
of a collision. The door intrusion beam is desirably constructed of
a material and/or configuration so as to maximize its strength and
effectiveness in the event of a collision. There is, however, a
continuing need to improve manufacturing processes to permit the
beam to be formed in an economical manner while at the same time
providing a beam having desirable impact strength while at the same
time minimizing weight.
[0004] Numerous beam constructions and manufacturing processes have
been developed or formulated in order to attempt to provide a
strong intrusion beam, and in particular permit manufacture of a
strong intrusion beam from less expensive materials, and in this
respect intrusion beams have been developed which involve a wide
variety of cross sections, including beams wherein the main
elongate beam body has a hat-shaped cross section, an H-shaped
cross section, a longitudinally grooved cross section, a hollow
tubular cross section, and other complex cross-sectional shapes. In
these known beams, the main elongate beam body is provided with
flanges at opposite ends which are suitably shaped to enable them
to be fixedly secured to the side frames of the door, which fixed
securement preferably involves welding. Such flanges are thus
preferably of lower grade or lower strength steel in view of the
difficulty of welding high strength materials. Hence, many of the
known intrusion beams have necessarily involved a multi-piece
construction, namely an elongate beam body of one material or shape
so as to provide one property, and separate flanges of a different
material or property to facilitate attachment to the door frame.
These beams and the manufacturing processes affiliated therewith
are typically of greater complexity and cost than is desired.
[0005] For example, in one known construction, the elongate beam
body is formed as a hollow tubular member which is roll-formed to
define an elongate tubular element, with the material used for
forming the roll-form being of lower strength. Following
roll-forming and welding, the elongate sheet is then subjected to
intermittent heating and quenching at selected lengths therealong
so as to provide for strength increases in the element at selected
locations. The element is cut to length to define a beam part.
Separate preformed end flanges of lower strength steel are then
welded to the ends of the elongate center beam body, which ends
have not been heat treated. This overall forming process is,
however, unnecessarily complex due to the way in which the
quenching of the roll-formed tubular section is heat treated in an
intermittent manner at select locations, which also causes loss in
strength adjacent the beam ends, and wholly separate end flanges
are separately manufactured and thereafter secured to the ends of
the tubular beam.
[0006] Examples of various door intrusion beam constructions, and
the manufacturing processes therefor, are illustrated by U.S. Pat.
Nos. 4,090,734, 4,599,843, 4,708,390, 4,838,606, 5,080,427,
5,124,186, 5,232,261, 5,272,841, 5,370,437, 5,404,690, 5,466,032,
5,540,016, 5,600,931, 5,756,167, 5 785,376, 5,813,718, 5,813,719,
5,868,456, 5,884,960, 5,887,938.
[0007] Vehicles such as automobiles and trucks also employ numerous
other types of structural beams for defining part of the vehicle
for structural and/or safety purposes, and examples of such beams
are bumpers, roof bows, etc. These beams desirably provide high
strength, but the need to provide weldable mounting flanges often
compromises the selection of beam material and the overall strength
of the beam, thus resulting in undesired increases in beam size
and/or wall thickness, and consequent increases in weight.
[0008] Accordingly, it is an object of this invention to provide an
improved method of manufacturing a structural beam for a vehicle,
and an improved beam structure, which in one embodiment comprises a
door intrusion beam, and which improves on and overcomes many of
the constructional or processing disadvantages associated with
conventional processes and constructions.
[0009] More specifically, the present invention relates to an
improved structural beam, particularly for a vehicle, which
possesses an elongate tubular beam part which at opposite ends is
provided with suitably shaped mounting flanges for securement to a
vehicle frame. The elongate tubular beam part and the flanges
provided at opposite ends thereof are all defined by an integral,
one-piece, monolithic steel structure which has been initially
roll-formed from an elongate flat metal sheet so as to define the
closed tubular structure of the tubular beam part, and which has
been subjected to heating and quenching so that the elongate
tubular beam part is of relatively high strength steel throughout
its entire length, whereas the integrally and monolithically joined
end flanges remain as lower strength steel which has been
significantly unaffected by the heat treatment and quenching so as
to permit appropriate shaping thereof and ease of welding to the
vehicle frame. This beam is particularly desirable for use, for
example, as a door intrusion beam, a roof bow beam, or an exterior
vehicle bumper.
[0010] The present invention also relates to an improved process
for forming the structural beam, as aforesaid, which process
involves forming beams by providing an elongate sheet of relatively
flat low-strength steel, subjecting the sheet to appropriate
notching and/or slitting operations in those areas of the sheet
which will ultimately be formed into the end flanges, then feeding
the elongate sheet through a roll-forming mill so that the sheet is
transversely deformed (i.e. rolled) into an elongate profile having
a reshaped cross section which includes a substantially closed
tubular cross section which extends along the un-notched region of
the sheet to define the elongate center tubular beam part, with the
notched regions of the sheet failing to define a closed tubular
section due to the presence of the notches. The roll-formed profile
is supplied to an induction heater followed by a quencher to effect
heating of solely the closed tubular section so that this section,
when quenched, results in the elongate tubular beam part being of
relatively high strength. The heating and quenching, however, is
ineffective in significantly modifying the properties of the
notched regions, and hence they retain their lower strength. These
regions are then suitably shaped to define the desired end flanges,
which are integrally and monolithically joined to opposite ends of
the high-strength elongate tubular beam part, whereupon the
finished structural beam can be more easily welded to the vehicle
frame, and the flanges also more readily accommodate tolerance
variations and distortions which are typically experienced with
respect to the frame.
[0011] The process of the present invention, as briefly summarized
above, preferably effects notching of a substantially continuous
sheet at defined intervals therealong to define notched and
un-notched regions in a defined arrangement lengthwise along the
sheet, with the sheet thereafter being roll-formed to define said
profile as an elongate and continuous structure which is still
joined to the flat steel sheet. Abutting or contacting edges of the
sheet at least through the closed tubular sections are then welded
together, and the continuous profile thereafter sequentially moved
into and through the induction heater and the quencher. The
elongate profile is, after quenching, transversely cut or severed
at the notched region to define separate beams having end flanges
at opposite ends thereof as defined by the notched regions. The end
flanges can be appropriately reshaped, if necessary, as by stamping
or the like, to provide the desired configuration.
[0012] The improved beam of this invention, and the improved
process for forming the beam, both as summarized above, according
to a preferred embodiment relate to a door intrusion beam for a
vehicle door, whereas alternate embodiments relate to a roof bow
beam for a vehicle roof or a vehicle bumper beam.
[0013] Other objects and purposes of the invention will be apparent
to persons familiar with structures and processes of this general
type upon reading the following specification and inspecting the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a diagrammatic elevational view illustrating a
vehicle door frame having a door intrusion beam attached
thereto.
[0015] FIG. 2 is a view taken generally along line 2-2 in FIG. 1
and illustrating the intrusion beam separated from the door
frame.
[0016] FIG. 3 is a side elevational view which illustrates solely
the door beam of the present invention.
[0017] FIG. 4 is an enlarged sectional view of the door beam as
taken generally along line 4-4 in FIG. 2.
[0018] FIG. 5 is a diagrammatic representation of the forming
process and apparatus according to the present invention for a
structural beam, for example the door intrusion beam of FIGS. 3 and
4, with the diagrammatic representation being illustrated from one
side of the initially supplied steel sheet.
[0019] FIG. 6 is a diagrammatic representation of the process and
apparatus of FIG. 5 but being taken from a view looking down onto
the upper surface of the flat sheet.
[0020] FIG. 7 is an enlarged fragmentary plan view of a length of
the sheet following slitting and notching thereof, but prior to
roll-forming thereof.
[0021] FIG. 8 is a fragmentary top view showing the formed sheet as
it departs from the rolling mill.
[0022] FIG. 9 is an enlarged cross-sectional view taken generally
along line 9-9 in FIG. 8.
[0023] FIG. 10 is an enlarged cross-sectional view taken generally
along line 10-10 in FIG. 8.
[0024] FIG. 11 is a fragmentary view which corresponds generally to
FIG. 7 but illustrates a variation in the notching and slitting of
the sheet during the manufacturing process.
[0025] FIG. 12 is a view similar to FIG. 2 but illustrates a
cross-sectional view of the door intrusion beam formed utilizing
the modified process of FIG. 11.
[0026] FIG. 13 is a diagrammatic view of a vehicle (i.e. an
automobile) and illustrating a roof bow beam according to the
present invention associated with the vehicle roof.
[0027] FIG. 14 is a fragmentary perspective view showing one end of
the roof bow beam of FIG. 13.
[0028] FIG. 15 is a cross-sectional view of the roof bow beam as
taken along line 15-15 in FIG. 14.
[0029] FIG. 16 is an enlarged fragmentary plan view of a length of
metal sheet after cutting and notching, but prior to roll-forming
thereof, as used for forming the roof beam of FIGS. 14 and 15.
[0030] FIG. 17 is a fragmentary top view of the profile after the
sheet of FIG. 16 has passed through and been reshaped in the
rolling mill.
[0031] FIG. 18 is an enlarged cross-sectional view of the notched
region of the profile as taken along line 18-18 in FIG. 17.
[0032] Certain terminology will be used in the following
description for convenience and reference only, and will not be
limiting. For example, the words "upwardly", "downwardly",
"rightwardly" and "leftwardly" will refer to directions in the
drawings to which reference is made. The word "forward" will also
be used to designate the direction of movement of the sheet
material during the forming process, which direction is designated
by the arrows in FIGS. 5 and 6. Said terminology will include the
words specifically mentioned, derivatives thereof, and words of
similar import.
DETAILED DESCRIPTION
[0033] The improved process for forming a structural beam, and the
improved structural beam construction of this invention, will now
be described with particular reference to FIGS. 1-10. The
structural beam illustrated in FIGS. 1-10 is, according to a
preferred embodiment of the invention, a door intrusion beam for a
vehicle.
[0034] In FIG. 1, there is diagrammatically illustrated a frame 10
of a vehicle door, such as for an automobile or truck. Such frame
typically has a bottom frame rail 11 which at opposite ends is
rigidly joined to upwardly projecting side rails 12 and 13, which
side rails in turn are generally rigidly joined by a top rail 14.
The frame is conventionally configured with an opening 15 in the
upper portion thereof for accommodating a window. The frame, except
for the area of the window, is conventionally covered with a thin
exterior skin (not shown), such as sheet metal. This thin skin, and
the necessity of maintaining significant open space in the bottom
of the door frame to accommodate an openable window, hence results
in the door having minimal side impact strength.
[0035] To improve upon the side impact strength of the door, it is
conventional to include a side impact beam which extends across the
lower hollow frame portion and joins to the side rails. In this
respect, there is illustrated a side impact beam 20 constructed
according to the present invention, which beam is disposed within
the hollow frame in upwardly spaced relation to the bottom rail 11,
and is fixedly coupled at opposite ends thereof to the frame side
rails 12 and 13.
[0036] In the illustrated embodiment, the intrusion beam 20 has an
elongate tubular center beam part 21 which, at opposite ends, is
provided with flanges 22 and 23. These flanges may assume a wide
variety of different shapes suitable for accommodating the
configuration of the door frame and permitting securement thereto,
such by welding. In the illustrated embodiment the one flange 22
has a generally flat plate-like shape which enables it to overlap a
surface, such as one side surface of rail 13, whereas the other end
flange 23 is illustrated as being of a generally L-shaped cross
section so that one leg thereof will overlap an inner surface and
permit welded securement to the other side rail 12. It will be
appreciated, however, that the shape of the flanges 22 and 23 can
be varied and determined in accordance with the shape of the door
rails and the specific desired configuration for attachment to the
door frame rails, and thus other shapes for the flanges 22 and 23
can be provided without departing from the present invention.
[0037] The door beam 20 in a preferred construction, as illustrated
by FIG. 4, has the elongate center tubular beam part 21 provided
with a generally four-sided configuration, specifically a
trapezoidal cross section defined by a front wall 26 which is
generally parallel with but of greater transverse width than the
rear wall 27, with these walls 26 and 27 being integrally and
monolithically joined together by side walls 28 and 29 which
project transversely rearwardly from the front wall 26 and are
inwardly inclined so that they generally converge as they project
rearwardly for connection with the back wall 27, whereby the
trapezoidal configuration of the beam part 21 is thus generally
symmetrical about a vertically extending centerline in FIG. 4.
[0038] In the improved intrusion beam 20 of the present invention
as illustrated by FIGS. 3 and 4, the elongate tubular center part
21 is, throughout the length thereof, of a relatively high strength
steel so that the material properties, coupled with the closed
tubular configuration of the beam part 21, thus provide the beam
part with significant impact resistance when an impact load is
imposed transversely to the longitudinal length of the beam part.
The end flanges 22 and 23, however, are of a relatively softer and
lower-strength steel in relationship to the center beam part 21. In
fact, the strength of the center beam part 21 is significantly
greater than the strength of the end flanges 22-23. These latter
flanges can thus be more easily and conveniently shaped or formed
so as to accommodate and conform to the configuration of the door
frame side rails, and can obviously be much more easily welded to
the door frames because of the lower strength and hardness
properties of the flanges. Even though the flanges 22-23 have
significantly different strength and hardness properties in
comparison to the center beam part 21, these flanges 22 and 23 are
nevertheless integrally and monolithically joined to the center
beam part 21, and in fact beam part 21 and flanges 22-23 are all
initially formed from a monolithic one-piece flat sheet of steel,
preferably low grade (i.e., relatively low strength and low
hardness) steel.
[0039] Forming the steel sheet so as to result in a monolithic
structural beam, specifically a door intrusion beam, having the
construction and properties summarized above will be hereinafter
described.
[0040] There is provided a supply station 31 for supplying sheet
steel, preferably a substantially continuous and elongate strip of
sheet steel S. The sheet steel at supply station 31 is preferably
provided in the form of a conventional coil 32 wherein the sheet
steel is effectively spirally wound, with the coil being
appropriately rotatably supported on a conventional coil stand 33.
The thin and relatively flexible sheet steel S is withdrawn from
the coil 32 and fed into and through a sheet driving station or
device 35, such being conventional and typically employing upper
and lower drive rolls which drivingly engage opposite sides of the
steel sheet S for advancing the sheet forwardly into and through
the subsequent forming and processing stations. The sheet steel is
advanced from the driving station 35 to a station 41, such as a
punching press or the like, which effects forming of notches as
well as cuts or slits in the flat sheet S fed therethrough. The
station 41 can effect this operation either while the sheet S is
momentarily stopped, as controlled by the drive station 35, or in a
continuous and sequential manner as the sheet is fed through the
station 41 by forming the station 41 with forming or cutting dies
mounted on appropriate moving punching heads. In its passage
through the station 41 the flat sheet S is appropriately punched,
cut or slit at spaced intervals so that the sheet S' departing the
station 41 possesses un-notched or uncut portions 42 (FIG. 7)
disposed generally in uniformly spaced relationship along the sheet
S', with the un-notched portions 42 being joined by notched
portions 43 which alternate with the un-notched portions 42. The
notches, cuts and/or slits as formed at station 41 are selected so
as to provide the configuration of the structural beam being
formed, such as the door intrusion beam in this described
embodiment.
[0041] As illustrated in FIG. 7, the alternating un-notched and
notched portions 42 and 43 respectively define successive but
integrally connected sheet lengths L which are defined between
generally parallel planes 44 which effectively perpendicularly
intersect adjacent notched portions 43. While these planes 44 in
the illustrated embodiment extend generally through the centers of
the notched portions 43 when viewed longitudinally of the sheet, it
will be appreciated that the planes can be offset in a direction
toward either side of this center location if desired, so long as
the uniformity of the sheet module length L is maintained.
[0042] The cutting and notching which occurs at station 41 (which
may involve one or more simultaneous or sequential operations), and
which results in the notched portions 43, causes each notched
portion 43 to be defined by cuts or slits which extend through the
thickness of the material, with slits 45 and 46 extending inwardly
from one side edge 47 of the sheet and projecting inwardly toward
but terminating short of the longitudinally extending centerline 48
of the sheet. A further pair of cuts or slits 51 and 52 also extend
through the thickness of the material and project transversely
inwardly from the other side edge 53 of the sheet, with slits 51
and 52 also projecting inwardly but terminating short of the
longitudinal centerline 48. The slits 45 and 51 at their inner ends
are generally aligned and separated by a transverse unslit region
having a transverse dimension D, and a similar relationship exists
between the opposed inner ends of the slits 46 and 52.
[0043] The station 41 in the illustrated embodiment also effects
forming of notches or cutouts at the notched portion 43, including
specifically a first notch or cutout 55 which is defined by a cut
line 54 which is spaced inwardly a small distance from and
approximately parallel with the side edge 47 and which extends
transversely between and intersects the slits 45, 46, thereby
creating a substantially rectangular notch or cutout region 55
which projects inwardly a defined distance from the free edge 47 of
the sheet and extends lengthwise between the slits 45 and 46.
[0044] A similar cutout or recess 56 is defined in the notch
portion 43 adjacent the other sheet side edge 53. This notch 56
again projects inwardly a limited distance from the sheet side edge
53, and terminates at an inner cut line or edge 57 which extends
generally transversely between and intersects the slits 51 and 52.
The notched portion 43 thus has a width extending perpendicularly
between the cut edges 54 and 57 which is, due to the presence of
the cutouts or recesses 55 and 56, less than the width W of the
sheet, which width is defined across the un-notched portions
42.
[0045] As will be apparent from the following description, the
un-notched portion 42 defines the elongate center beam part 21,
whereas the notched portion 43 in this embodiment defines flange
parts for two adjacent beams, one side of the notched portion
defining the flange 22 at one end of one beam, and the other side
of the notched portion defining the end flange 23 of an adjacent
beam.
[0046] The formed sheet S' departing the forming station 41, and
having alternating notched and un-notched portions as illustrated
by FIG. 7, is then fed into a conventional roll-forming mill 61
which includes a plurality of sequential rolling stations 62 which
include opposed upper and lower forming rollers which engage
opposite sides of the sheet to progressively deform the sheet from
its flat condition into a desired three-dimensional shape or
profile. In the present invention, the rolling mill 61
progressively deforms the sheet S' which, when fed into the first
station of the mill is of a relatively flat sheetlike
configuration, into a three-dimensional configuration which, upon
leaving the mill, has a generally closed tubular cross section or
profile throughout at least the un-notched portions 42 of the
sheet. The formed, non-flat, three-dimensional profile as it
departs the rolling mill is designated P in FIGS. 5 and 6 since the
steel sheet is no longer flat.
[0047] Upon departing the rolling mill 61, the formed
three-dimensional profile P has, throughout the un-notched portions
42, a substantially closed tubular cross section as designated 62
in FIG. 9. The overall un-notched portion 42 of the sheet has been
suitably reshaped or reformed by the mill 61 into a tubular cross
section so that the side edges 47 and 53 of the original un-notched
portions 42 of the sheet substantially meet or contact one another,
thereby effectively defining a seam 63 which runs longitudinally
throughout the closed tubular section 62.
[0048] Since the notched portions 43 are subjected to the same
roll-forming operations in the mill 61 as the un-notched portions
42, the notched portions 43 in this illustrated embodiment upon
departing the mill have also been formed into a three-dimensional
shape or profile 64 (FIG. 10) which, rather than being a closed
tube, instead resembles a partially open channel, or as shown by
FIG. 10 resembles a closed tube having an open slot extending
longitudinally therealong, such slot being indicated at 65 with
opposite sides thereof being defined by the cut edges 54 and 57.
This roll-formed sheet section 64 thus has an open cross-sectional
configuration due to the presence of the slot 65.
[0049] The construction and operation of the rolling mill 61 is
conventional and well known, and further description thereof is
believed unnecessary.
[0050] The three-dimensional roll-formed profile P departing the
rolling mill 61 thus has alternating closed tubular sections 62 and
open sections 64, which sections respectively have lengths
corresponding to the longitudinal lengths of the un-notched sheet
portions 42 and notched sheet portions 43. These alternating
profile portions 62 and 64 define a continuous formed profile P
which is then fed into a seaming station 71, such as a conventional
resistance seam welder which rolls along the seam 63 of the
workpiece portions 62 so as to effect welding together of the
meeting edges 47 and 53 to thereby form a fixed closed tubular
cross section. The welding of the seam 63 occurs substantially
continuously as the formed profile P is moved through the welding
station 71. As the open profile sections 64 move through the
welding station 71 and in particular pass beneath a welding wheel,
the welding wheel will be located in alignment with the air gap 65
which extends longitudinally of the workpiece sections 64, and thus
no welding operation will occur. Because of this air gap 65,
however, the welding wheel can remain continuously energized, and
hence complex on-off controls for the welding station are not
required.
[0051] The continuous elongate formed profile P having alternating
welded closed tubular sections 62 and open or nontubular sections
64 is then successively fed into and through a heating station 72
and a quenching station 73 so that the welded closed tubular
sections 62 of the profile P, upon departing the quench station 73,
will be of significantly higher strength and hardness.
[0052] More specifically, the heating station 72 comprises a
conventional electric induction heating oven which, as is well
known, includes a heating tunnel defined by an electrically
energized heating coil through which the profile P is passed. Due
to the inductive field created by the electrical inductive heating
coil and the continuous peripherally closed wall defined by the
welded tubular profile sections 62, these sections 62 act like the
secondary windings of a transformer and are rapidly heated to a
high temperature sufficient to cause a change in the properties of
the steel, such being conventional and well known, whereupon when
these heated sections 62 then immediately move into the quench
station 73, they are rapidly cooled by being sprayed with a cooling
fluid such as water or other known quenching fluids such that the
temperature of the sections 62 is rapidly decreased, thereby
changing the properties of the steel defining the tubular sections
62 so that these sections now have a strength and hardness
characteristic which is significantly greater than the strength and
hardness characteristic of the steel prior to entering the heating
station 72.
[0053] As to the open profile of the workpiece sections 64,
however, the air gap or slot 65 which extends longitudinally of
these sections 64 effectively creates a short circuit in the
peripheral direction of the workpiece sections 64 and hence
prevents any significant inductive heating of the material of these
sections by the surrounding inductive coil. These open workpiece
sections 64, in contrast to the closed workpiece sections 62, thus
experience very little increase in temperature, and hence do not
undergo any significant change in their material properties. Upon
departing the quench station 73, the open workpiece sections 64
hence maintain physical properties which generally correspond to
their physical properties upon entering the heating station 72,
namely these sections 64 remain of relatively low strength and low
hardness. The formed profile P' departing the quench station 73
hence now has workpiece sections 62 which are of a closed tubular
cross section and have relatively high strength and hardness, and
alternating open workpiece sections 64 which are of significantly
lower strength and hardness in that these properties more closely
resemble the physical properties of the original steel sheet
material S.
[0054] The heating station 72 and quenching station 73 can, if
desired, be positioned within a single and substantially continuous
enclosure or shroud 74 if desired.
[0055] The continuous three-dimensional heat treated profile
departing the quenching station 73, which heat treated profile is
designated P', is then fed to a conventional cutting station 75
which sequentially causes the continuous profile P' to be
transversely cut or severed into individual elongate workpieces W
which have the predefined module length L. The cutting at
workstation 75 will normally be carried out at planes which
correspond to the predefined transverse planes 44, whereby the cuts
thus occur within the non-heat treated profile sections 64 at a
location spaced between the longitudinal ends thereof. This results
in each severed workpiece W having an elongate closed tubular
center part 77 which is defined by the heat treated profile section
62 and hence corresponds to the center beam part 21 of the finished
door intrusion beam 20. The center workpiece part 77 has end
workpiece parts 78 and 79 at opposite ends thereof, the latter
being parts from the non-heat treated open profile sections 64
which, of course, correspond to the un-notched sections 43. These
end parts 78 and 79 of the workpiece can be of the same or
different lengths, depending upon the selected position of the
cutting plane and the desired shape and size of the end flanges 22,
23.
[0056] The individual elongate workpiece W is then fed to a forming
station 76 which effectively reshapes the workpiece ends 78 and 79,
either simultaneously or sequentially. More specifically, the one
end part 78, which has an open channel-like configuration, can be
suitably flattened so as to define the desired flange configuration
such as the flange 22, and the other end part 79 is also suitably
reformed so as to define the desired shape of the other end flange
23. The station 76, which may comprise one or more sequential
forming operations or stations, hence effects necessary pressing,
stamping and reforming so that the open channel-like end parts 78
and 79 are appropriately reshaped into the desired configurations
of the end flanges 22 and 23. Since the end parts 78 and 79 have
not been heat treated and hence possess relatively low strength and
low hardness material properties, the reshaping of the end parts
78-79 so as to form the end flanges 22-23 can be relatively easily
accomplished.
[0057] The workpiece departing the forming station 76 thus
constitutes the finished structural intrusion beam 20. Such
structural beam 20 thus possesses end flanges 22 and 23 which are
of relatively low grade steel in that they possess lower strength
and lower hardness, and thus they not only can be more readily
welded to the vehicle (i.e. door) frame, but they also will more
readily deform so as to compensate for distortions and the like
which are typically encountered in vehicle (i.e. door) frames. The
center beam part 21, on the other hand, has a closed tubular cross
section throughout, and the material of this center part 21 is of
high strength and hardness, namely having a strength which is
significantly greater than that of the end flanges 22, 23, whereby
the center beam part 21 thus possesses significantly increased
strength so as to withstand side impact forces thereagainst, such
as due to a collision-caused side impact against the vehicle
door.
[0058] The transverse slits 45-46 and 51-52 which effect a
separation line between the notched and un-notched portions 42-43,
whereby these portions are joined together solely through the small
strip of material at the dimension D, which strip D effectively
defines the base wall 26 of the finished door beam, enables the
transition from the high-strength material of the tubular beam part
21 to the low-strength material of the flanges 22-23 to occur over
a very short transitional distance, whereby the desired high
strength of the beam part 21 hence can be achieved over
substantially the entire length of the beam part 21 so as to
maximize the strength thereof.
[0059] If necessary or desired, the width of the slits 45-46 and
51-52 can be increased, such as by making the slits as narrow slots
or notches, if such is necessary or desirable to improve the
isolation between the adjacent notched and un-notched sections 64
and 62 as they progress through the induction heating station.
[0060] As an example of the expected materials usable for forming
the improved structural beam and specifically a door intrusion beam
and in accordance with the improved forming process, the sheet
steel S will preferably be relatively low grade and hence
low-strength steel so as to minimize initial cost thereof. As an
example, the initial low grade steel will normally have a yield
strength in the range of 27,000 to 35,000 psi, with a possible
upper limit being no more than about 50,000 psi. After the profile
P' of the present invention has been heat treated and quenched at
stations 72 and 73, however, the steel defining the closed tubular
sections 62 will now preferably have a yield strength in the range
of from about 120,000 psi to about 200,000 psi, with the desired
yield strength range being from about 160,000 to about 180,000 psi.
The open profile section 64, however, will still have a yield
strength property which will be similar to or only slightly greater
than that of the originally supplied steel, with any increase being
due primarily to the cold working thereof in the roll mill. The
heat treated sections 62 will thus have a yield strength which will
typically be more than double the yield strength of the non-heat
treated sections 64. The resulting structural beam 20 thus has a
closed tubular beam part 21 of high-strength steel which rapidly
and integrally transitions into end flanges 22, 23 of low-strength
steel.
[0061] The sheet steel used for forming the intrusion beam 20 will
typically have a thickness in the range of from about 0.090 inch to
about 0.150 inch, with the preferred thickness being in the
neighborhood of about 0.120 inch.
[0062] Further, the width of the sheet steel S will normally be
selected so that same is sufficient to be formed into a
three-dimensional profile having the desired cross section of the
finished beam, yet avoid having to effect any significant removal
of edge material as waste. Under most circumstances it is
anticipated that the sheet steel S for forming a door intrusion
beam will have an initial maximum width in the range of about 6 to
8 inches.
[0063] FIGS. 11 and 12 illustrate a variation of the embodiment of
FIGS. 1-10 with respect to the manner in which the sheet is notched
and cut at station 41. As illustrated by FIG. 11, particularly in
comparison to FIG. 7, the sheet is provided with notches or
cut-outs 81 which are disposed at spaced intervals along the sheet
and generally centered along the centerline 48 thereof. These
cut-outs 81 are generally of a rectangular profile, and opposite
ends of each notch 81 are defined by cut lines 82 which project
transversely outwardly on opposite sides of the recess 81 in a
direction toward the opposite free edges 83 of the steel sheet.
These cut lines 82, however, terminate short of the side edges 83
by a distance which is generally designated D/2. The overall
dimensions of the recess 81 thus generally corresponds to the
combined dimension of the recesses 55 and 56 in FIG. 7, thereby
resulting in alternating notched and un-notched sheet portions 87
and 86 which thus correspond to the respective portions 43 and 42
in FIG. 7.
[0064] With the sheet S' notched as illustrated in FIG. 11, the
sheet is processed in the same manner as described in FIGS. 5 and 6
above, except that during the roll-forming of the sheet the opposed
edges 83 meet throughout the entire length of the formed profile
and thus are seam welded together by means of a continuous seam
welding operation as the elongate profile is fed through the
welding operation. This thus results in the closed tubular sections
as defined by the un-notched regions 86 again having the same
closed tubular profile as illustrated in FIG. 12, but in this
variation the welded meeting edges 83 and the resulting seam weld
84 occur on the wider outer or bottom wall of the closed tube,
rather than at the top wall as in the previous embodiment. Other
than the weld seam being along the outer wider bottom wall, rather
than in the top wall, the variation illustrated by FIGS. 11 and 12
is in all other respects the same as described above since the
cut-outs 81 will again appear in alternating fashion along the top
wall of the formed profile so as to define alternating closed
tubular and open profile sections which will undergo heat treating
of solely the closed tubular sections in the same manner as
discussed above. This thus permits forming of vehicle structural
beams, such as door intrusion beams, having substantially the same
structure and using substantially the same process as described
above relative to FIGS. 1-10.
[0065] Referring to FIGS. 13 to 18, there is illustrated a second
embodiment of a structural vehicle beam according to the present
invention, which beam is manufactured according to the process of
this invention. This embodiment, which comprises a roof or bumper
beam for a vehicle, incorporates many of the same structural and
functional features as the embodiment of FIGS. 1 to 12, and is
manufactured by means of the same basis process. Corresponding
parts of the embodiment of FIGS. 13 to 18 are thus designated by
the same reference numerals used in FIGS. 1 to 10 but with a prime
(') added thereto.
[0066] FIG. 13 diagrammatically illustrates a vehicle, namely an
automobile 100, having one or more structural roof beams 20' (often
referred to as a roof bow or a roof header) associated therewith in
a generally conventional manner. The roof beam 20' extends
transversely across the roof and has end flanges which are fixed,
as by welding, to the side frame elements (not shown) of the
roof.
[0067] The roof beam 20' has an elongate tubular center section 21'
which at opposite ends is integrally and monolithically joined to
platelike end flanges 22' which in turn are used to effect
securement to the vehicle frame (i.e., the side frame rails of the
roof).
[0068] The tubular center section 21' is defined by a bottom wall
26' which at opposite ends joins to upstanding sidewalls 28' and
29'. These sidewalls 28', 29' at upper ends thereof are joined by a
top wall which includes two wall sections 101 and 102 which project
inwardly from the respective sidewalls and are laterally spaced
apart. The top wall sections 101 and 102 at inner ends thereof are
joined respectively to downwardly projecting inner sidewalls 28"
and 29" . These latter sidewalls at lower ends thereof are joined
to a third top wall section 103 which is spaced downwardly from and
substantially spans the gap between the top wall sections 101 and
102. The wall section 103 is spaced upwardly above the bottom wall
26' by a small clearance distance. The top wall section 103 is
defined by wall portions which are defined adjacent the sheet edges
(i.e. edges 47' and 53' in FIG. 16) which, during roll forming,
substantially abut to define a closed tubular cross section with
these edges being welded together as indicated at 63' to define a
closed tube. This closed tube, as shown in FIG. 15, has generally
hollow boxlike tube sections 104 which extend lengthwise along
opposite sides of tube part 21' in generally parallel relationship,
and which are joined together by wall 103, thereby defining a
channel-like recess 62' between tube sections 104.
[0069] The top wall sections 101 and 102, in the illustrated
embodiment, have strengthening grooves 106 extending lengthwise
therealong. The wall sections 101 and 102 are substantially
coplanar and, in the illustrated embodiment, each wall section
101,102, and 103 extends across about one-third the width of the
beam.
[0070] The channel or U-shaped configuration of the tubular section
21' of the beam, and the resulting channel or U-shaped hollow
interior, results in the beam having significant strength,
particularly against bending, while having a small size and
profile, and being of light weight.
[0071] The beam 20' in this FIGS. 13-18 embodiment has the end
flanges 22' formed as substantially flat plates which are coplanar
with and project outwardly from the bottom wall 26'. The end
flanges 22' are shown as having a width which slightly exceeds the
width of bottom wall 26', but this dimension as well as the shape
of the end flanges can vary depending on the shape of the side
frame rails of the vehicle roof and the nature of the connection
therebetween.
[0072] The roof beam 20' as described above is formed by the same
process as illustrated in FIGS. 5 and 6 and as described above. The
forming of the roof beam 20' will, however, be briefly described
with reference to FIGS. 5 and 16 for purposes of completeness.
[0073] The steel sheet as supplied from the supply station 31 (FIG.
5) is appropriately notched and/or cut at defined intervals
therealong so that the continuous sheet has alternating un-notched
and notched regions 42' and 43' respectively, which ultimately
respectively define the center tubular part and the end flanges of
the structural beam. The notches 55', 56' in this embodiment, as in
FIG. 7 as described above, open inwardly from the side edges 47',
53' of the sheet. The side edges 45', 46' and 51', 52' of these
notches project inwardly a small distance beyond the notch bottom
wall 54', 57', and in this embodiment the slits defining the notch
sides are defined as narrow slots or cutouts to thus define both a
rounded corner and a small space or distance 107 between the end of
the center beam part and the main body of the end flanges, which
space is bridged by an extension of the respective end flange.
[0074] In the beam of FIGS. 13 to 18, the end flange 22' has a
width which slightly exceeds the width of the bottom wall 26' of
the tubular part, whereby during rolling of the profile P', the
notched sections 43' will be formed into a shallow channel-shaped
cross section as illustrated in FIG. 18. After the profile P' has
been heated and quenched, which resulted in a substantial increase
in the strength and hardness of only the closed tubular sections
62', then the notched sections 64' can be physically reformed or
reshaped, as desired, to define the desired shape and/or size of
the end flanges. This reshaping of the end flanges will typically
occur after the profile is transversely cut along lines 44' to
effect forming of the individual beam members of length L', but
such reshaping of the end flanges could take place prior to such
cutting if appropriate.
[0075] As illustrated in FIG. 13, the present invention also
permits forming of a bumper beam 20" which, as illustrated, is
similar in cross section to roof beam 20', although it will be
appreciated that the structural beam of this invention may assume
other configurations particularly in cross section.
[0076] While the invention as described above relates to vehicle
beams such as door intrusion, roof and bumper beams, it will be
appreciated that these are merely exemplary of the present
invention, and that the invention is also applicable for forming a
wide range of beam sizes, shapes and configurations, particularly
structural beams intended for incorporation into a vehicular
structure. For example, beams constructed in accordance with this
invention can be used at least in part in the construction of the
space frame or structural cage as proposed for vehicle
constructions so as to optimize strength while minimizing weight,
and can also be used as structural reinforcements for floors and
rocker panels of vehicles.
[0077] Although a particular preferred embodiment of the invention
has been disclosed in detail for illustrative purposes, it will be
recognized that variations or modifications of the disclosed
apparatus, including the rearrangement of parts, lie within the
scope of the present invention.
* * * * *