U.S. patent application number 11/312185 was filed with the patent office on 2006-05-11 for joint structure and method for making a joint structure.
Invention is credited to Michael Braun, John W. JR. Cobes, Israel Stol, Greg S. White.
Application Number | 20060096100 11/312185 |
Document ID | / |
Family ID | 26942585 |
Filed Date | 2006-05-11 |
United States Patent
Application |
20060096100 |
Kind Code |
A1 |
Stol; Israel ; et
al. |
May 11, 2006 |
Joint structure and method for making a joint structure
Abstract
A joint structure is ideally suited for use in the manufacture
of assemblies and subassemblies in aluminum structures. More
particularly, the alternative joint structures and methods of
forming joint structures facilitate the assembly of a vehicle
body-in-white. The friction welded joints of this invention provide
assemblies in which lineals and sheet, cast, or extruded components
are joined together.
Inventors: |
Stol; Israel; (Pittsburgh,
PA) ; Cobes; John W. JR.; (Lower Burrell, PA)
; Braun; Michael; (Wendlehausen, DE) ; White; Greg
S.; (Mars, PA) |
Correspondence
Address: |
ECKERT SEAMANS CHERIN & MELLOTT, LLC;ALCOA TECHNICAL CENTER
100 TECHNICAL DRIVE
ALCOA CENTER
PA
15069-0001
US
|
Family ID: |
26942585 |
Appl. No.: |
11/312185 |
Filed: |
December 20, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09990807 |
Nov 20, 2001 |
6598923 |
|
|
11312185 |
Dec 20, 2005 |
|
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|
60252712 |
Nov 22, 2000 |
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Current U.S.
Class: |
29/897.2 |
Current CPC
Class: |
B62D 23/005 20130101;
Y10T 403/477 20150115; B62D 27/023 20130101; Y10T 29/49622
20150115; Y10T 403/473 20150115; Y10T 403/478 20150115 |
Class at
Publication: |
029/897.2 |
International
Class: |
B21D 53/88 20060101
B21D053/88 |
Claims
1. A method of forming a joint for a vehicle body-in-white
comprising the steps of: inserting a first component comprising a
lineal member having a pair of ends into an opening in a second
component having a surface and boss extending from the surface, the
opening extending through the boss, such that an end of the boss
and the one end of the lineal member are coterminous; and attaching
a cap member onto the coterminous one end of the lineal member and
the boss end.
2. The method of forming a joint according to claim 1, wherein said
step of attaching the cap member is accomplished by friction
welding.
3. The method of forming a joint according to claim 1, wherein a
gap is defined between the second component boss and the lineal
member, and said method further comprises the step of inserting a
sleeve into the gap.
4. The method of forming a joint according to claim 3, wherein the
sleeve comprises a non-continuous ring such that a diameter of the
sleeve is variable between a maximum and minimum limit.
5. The method of forming a joint according to claim 3, wherein the
sleeve has a first face and a second face such that when positioned
between the second component boss and the first component lineal
member, the second face is proximate said cap member.
6. The method of forming a joint according to claim 5, wherein the
sleeve second face defines a discontinuous surface.
7. The method of forming a joint according to claim 6, wherein the
sleeve discontinuous second face facilitates a break in the
continuity of an interface between the sleeve second face and the
cap member during the step of friction welding the joint.
Description
RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application Ser. No. 60/252,712 filed Nov. 22, 2000,
entitled "A Joint Structure and Method for Making a Joint
Structure" which became U.S. Ser. No. 09/990,807 filed Nov. 20,
2001, and issued as U.S. Pat. No. 6,598,923 on Jul. 29, 2003,
entitled "Joint Structure and Method for Making a Joint Structure"
and U.S. Ser. No. 10/108,040 filed Mar. 27, 2002 and issued as U.S.
Pat. No. 6,698,809 on Mar. 2, 2004, entitled "Joint Structure and
Method for Making a Joint Structure" and U.S. Ser. No. 10/770,623
filed Feb. 2, 2004, entitled "Joint Structure and Method for Making
a Joint Structure.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention generally relates to a joint structures and a
methods for forming a joint structures that are ideally suited for
use in a vehicle body-in-white. More specifically, the invention
provides both a friction welded joint assembly in which lineals and
sheet, cast or extruded components are joined together and a
structure and method for improving the stability of the joint
structure.
[0004] 2. Description of the Prior Art
[0005] It is known that various structural components for
automobiles and other vehicles can be made from aluminum and other
light metal alloys. Considerable development work is now underway
with an objective of utilizing aluminum and other light metal
alloys in the primary body structure of a vehicle or, as it is
often called, the "body-in-white". An automobile chassis or
body-in-white comprised of light metal alloys weights considerably
less than a steel frame that has been designed to satisfy the same
requirements of safety and durability. A vehicle utilizing such a
body-in-white produced from light metal alloys has improved fuel
efficiency without sacrificing performance. Moreover, if the alloy
utilized is an aluminum alloy, it is more easily recycled than a
steel frame vehicle, and it offers improved corrosion resistance.
In addition, it is known that a body-in-white utilizing space frame
technology will distribute and absorb the forces encountered in the
normal operation of an automobile as well as absorb and dissipate
the energy of a crash or rollover.
[0006] By way of brief explanation, the space frame is a latticed
framework of structural beams and columns that are joined together
at their ends. These structural components of the space frame,
which are sometimes referred to as lineals, are connected together
by mechanical means such as bolts, rivets and clinches, by welding
and adhesive bonding, and by a combination of the aforedescribed
methods. Another method for connecting the lineals of a space frame
is by the use of separate joining components or connecting members
which are often referred to as "nodes" into which the lineals are
designed to fit. The lineals are then securely attached to the
nodes by any of the known connecting methods referred to above. An
example of this technology is found in U.S. Pat. No. 4,618,163
which pertains to an automobile chassis that includes lineals and
nodes. This patent is incorporated herein by reference as if fully
set forth herein. If the lineals are to be joined by means of
connecting members or nodes, the nodes are typically cast or
otherwise formed in a separate manufacturing operation. If the
lineals are to be mechanically attached to each other or to nodes
by means of bolts or other fasteners appropriate holes must be
provided in the several components. In the alternative, or in
addition, welding, soldering, or adhesive bonding equipment and
materials may be required to effect the joining of the components.
Furthermore, the tolerances of the various components that are to
be assembled together must be exact, in order for holes to align
with other holes or with protrusions or in order for the surfaces
to fit together for welding, soldering or adhesive bonding.
Finally, the complete frame is assembled in a series of discreet
steps involving the joining of individual lineals to nodes or to
other lineals or components in order to form subassemblies and then
the subsequent joining of the various subassemblies to form the
entire body-in-white space frame. As noted above, U.S. Pat. No.
4,618,163 to Hasler et al., describes an automobile space frame
chassis that is made from a plurality of tubular light metal
lineals that are held together by connecting members also made from
light metal. Hasler et al. discloses the use of tubular members
assembled by inserting their end sections into recesses in the
connecting or receiving members. However, this technique has the
disadvantage that the last member to be mounted in an assembly or
subassembly could only be mounted by flexing or bending the
structure. The elongated frame members of Hasler et al. are secured
to the connecting members by welding, soldering or cementing or by
the use of mechanical fasteners such as bolts, screws, and
rivets.
[0007] U.S. Pat. No. 5,381,849 to Fussnegger et al. discloses a
method for casting a connecting member onto the end of a hollow
section such as an extruded aluminum frame member. According to
this method, an end of the hollow section is placed in a mold with
the end of the hollow section closed with a plug to prevent
penetration of cast material therein. This method is not used to
join extruded frame parts to each other but rather to join them to
a cast frame member. These cast frame members are complicated solid
structures that are formed in complicated molds. In addition,
because the Fussnegger et al. castings may be of considerable size,
they may add considerable weight to the frame structure formed by
this method. It clearly is desirable to join together the
components of a space frame by a simple process that minimizes
manufacturing steps, compensates for tolerances at the joints and
is economical to implement.
SUMMARY OF THE INVENTION
[0008] The invention provides a joint structure ideally suited for
use in the manufacture of assemblies and subassemblies in aluminum
structures. More particularly, the alternative joint structures and
methods of forming joint structures facilitate the assembly of a
vehicle body-in-white. The friction welded joints of this invention
provide assemblies in which lineals and sheet, cast, or extruded
components are joined together.
[0009] The invention includes a joint structure having a first
component with a lineal member having a pair of ends, at least one
second component having a surface and a boss extending from the
surface and terminating in a boss face, the second component
defining an opening extending through the boss, wherein the opening
receives one end of the lineal member such that the boss face and
the end of the lineal member are coterminous, and a cap member
adapted to be mounted onto the coterminous ends of the lineal
member and boss face. Preferably, the cap member is friction welded
to the end of the first component and the boss face. The boss has
an inside diameter which tapers from a first diameter proximate
said boss face, to a second diameter distal therefrom and a gap is
defined in the opening between the boss and the lineal member.
[0010] A sleeve may be received in the gap and has a first face and
a second face such that when positioned in the gap, the sleeve
second face is proximate the cap member. The sleeve preferably is
discontinuous such that a diameter of the sleeve is variable and
the second face may include means for removably engaging the sleeve
with said cap member inner face such as a plurality of teeth
adapted to contact the cap member. Suitable materials for the
sleeve include aluminum, steel, and plastic. When the sleeve first
diameter is smaller than the sleeve second diameter, the sleeve
outside surface tapers in a direction opposite from the direction
of taper of the boss inside diameter and includes a plurality of
raised members adapted to engage the boss.
[0011] The joint structure may include another second component
adapted to receive the other end of the lineal member, wherein the
first component and the two second components constitute a vehicle
subassembly. The first component may be an aluminum product form
such as a sheet product, an extruded product, and a cast product.
The second component may be an aluminum product such as a sheet
product, an extruded product, and a cast product. While at least
one end of the lineal member has a circular cross-section, a
mid-portion between the ends may have a different cross-sectional
configuration than the end having a circular cross-section. Lineal
members having non-circular cross-sectional configurations in their
mid-portion may be sheet products, extrusions or castings suitable
as components in a vehicle body-in-white subassembly. For sheet
product formed into a lineal member, a reinforcing means such as a
bead may be included proximate at least one end thereof.
[0012] The present invention also includes a method of forming a
joint for a vehicle body-in-white comprising the steps of (1)
inserting a first component having a lineal member with a pair of
ends into an opening in a second component having a surface and
boss extending from the surface, the opening extending through the
boss, such that an end of the boss and the one end of the lineal
member are coterminous; and (2) attaching a cap member onto the
coterminous one end of the lineal member and the boss end. The
attaching step preferably is accomplished by friction welding. A
gap may be defined between the second component boss and the lineal
member, and the method may further include a step of inserting a
sleeve into the gap. The sleeve may include a discontinuous ring
such that a diameter of the sleeve is variable between a maximum
and minimum limit. The sleeve has a first face and a second face
such that when positioned between the second component boss and the
first component lineal member, the second face is proximate the cap
member. The sleeve discontinuous second face facilitates a break in
the continuity of an interface between the sleeve second face and
the cap member during the step of friction welding the joint.
[0013] Also included in the present invention is an assembly of a
first component including a lineal member having a pair of ends, at
least one of the ends having a circular cross-sectional
configuration; a cap member having a body portion, a first face,
and a second face, the cap member being attached to the circular
cross-section end of the lineal member, preferably via friction
welding; a structural member having a body portion defining an
opening wherein the first component is received in the opening such
that the cap member is fixed to an inner surface of the structural
member body portion; and means for retaining the circular
cross-section end of the lineal member within the second component.
In one embodiment of the retaining means, a bore is defined in each
of the cap member body portion and the structural member body
portion and a bolt extends through the bores in the cap member and
the structural member to retain the circular cross-section end of
the lineal member within the structural member. Preferably, a nut
is threaded onto the bolt against an outer surface of the
structural member body portion. Alternatively, a stud extends from
the cap member and through a bore in the structural member body
portion and a nut threads onto the stud against an outer surface of
the structural member body portion. In another embodiment of the
retaining means, the circular cross-section end of the lineal
member is retained within the structural component via a joint such
as a friction stir weld, a laser weld, and a mechanical fastener
between the cap member and the structural component body
portion.
[0014] The cap member may include an annular rim extending from the
second face with the lineal member being friction welded to the
second face within the annular rim such that the rim extends along
an exterior of the lineal member. Alternatively, the annular rim
itself may be friction welded to the lineal member. In another
embodiment, the cap member includes an annular welding surface
extending from the cap member second face at a location spaced
apart from the rim, with the lineal member being friction welded to
the annular welding surface.
[0015] Finally, the present invention includes an energy absorbing
member for a vehicle incorporating the above-described friction
welded joints. The energy absorbing member includes an elongated
crash box having at least one end with a circular cross-section and
a bracket friction welded to the circular end. The bracket may
include a raised portion defining a chamber with the circular end
being received in the chamber and friction welded to the bracket
within the chamber. Each end of the crash box may have a circular
cross-sectional configuration and a bracket is friction welded to
each circular end. One of the brackets may be configured to be
attached to a vehicle and the other bracket may be configured to be
attached to a bumper.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The above as well as other features and advantages of the
present invention can be more fully appreciated through
consideration of the detailed description of the preferred
embodiment in conjunction with the several figures wherein like
reference characters identify like parts throughout and in
which:
[0017] FIG. 1 is a schematic illustration of a friction welding
apparatus as it could be used to manufacture the joint structure on
the instant invention;
[0018] FIG. 2 is a sub-assembly for a body-in-white structure
incorporating the joint structures of the instant invention;
[0019] FIG. 3 is a detailed, cross-sectional view of a joint
structure of the present invention;
[0020] FIGS. 4A and 4B are detailed isometric views of lineal
members for use in the joint structures of this invention;
[0021] FIG. 5 is an isometric view of an insertable sleeve in a
split-ring configuration;
[0022] FIG. 6 is a detailed, cross-sectional view of a joint
structure according to the instant invention incorporating an
insertable sleeve in the gap between a lineal member and a second
component;
[0023] FIG. 7 is an isometric view of an insertable sleeve
incorporating a non-continuous face;
[0024] FIG. 8 is a detailed, cross-sectional view of a joint
structure with the insertable sleeve as shown in FIG. 7 disposed
between first and second structural components;
[0025] FIG. 9 is a detailed, cross-sectional view of an insertable
sleeve removably engaged with the cap member or engagement member
of the joint of this invention;
[0026] FIGS. 10A and 10B are a cross-sectional, side elevation view
of an alternative embodiment of this invention incorporating a
tapered and striated insertable sleeve with a tapered and striated
and a cross-sectional detail of the striated insertable sleeve and
striated sleeve engaging surface;
[0027] FIGS. 11A, 11B, and 11C illustrate an assembly incorporating
the joint structure of this invention;
[0028] FIG. 12 is an isometric view of an assembly incorporating
the features of this invention;
[0029] FIGS. 13A and 13B illustrate other assemblies of this
invention;
[0030] FIGS. 14A, 14B, 14C, and 14D illustrate various embodiments
of a cap member joined to a lineal member;
[0031] FIGS. 15A and 15B illustrate arrangements for assembling the
joint structure;
[0032] FIG. 16 illustrates a bumper assembly having friction welded
joints; and
[0033] FIGS. 17A, 17B, and 17C, illustrate alternative friction
weld joints of a crash box assembly.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0034] For purposes of the description hereinafter, the terms
"upper", "lower", "right", "left", "vertical", "horizontal", "top",
"bottom" and derivatives thereof relate to the invention as it is
oriented in the drawing figures. However, it is to be understood
that the invention may assume various alternative variations and
step sequences, except where expressly specified to the contrary.
It is also to be understood that the specific devices and processes
illustrated in the attached drawings, and described in the
following specification, are simply exemplary embodiments of the
invention. Hence, specific dimensions and other physical
characteristics related to the embodiments disclosed herein are not
to be considered as limiting.
[0035] One joint structure of this invention includes the joining
of concentric parts with the use of a cap member via friction
welding. Friction welding is a solid state joint process that
produces coalescence of materials under compressive force contact
of work pieces rotating or moving relative to one another in order
to produce heat and plastically displace material from the faying
surfaces. Under normal conditions, the faying surfaces do not melt.
Filler metal, flux and shielding gases are not required with this
process. Typically, friction welding in production is an automatic
weld process essentially for use with circular components or more
appropriately components having a circular cross-section. The basic
steps in friction welding include the rotation of one work piece
while another work piece is held stationary. The two work pieces
are brought together in axial compressive force, that is a friction
welding force is applied. Rubbing of the faying surfaces heats the
work piece locally with the result that upsetting or change in
length of the components begins. The process is complete when
rotation of the one work piece stops and the upsetting ceases. The
weld produced is characterized by the absence of a fusion zone (the
narrow heat effective zone) and the presence of plastically
deformed material around the weld (i.e., a flash). Weld quality is
dependent upon the proper selection of material, joint design,
welding variables, and post welding processes. Acceptable welds can
be made in many materials using a wide range of weld parameters,
that is speed, force, and time of the welding operation. A cap
member is used in the present invention as a rotating work piece
for friction welding.
[0036] Turning to FIGS. 1-3, the fundamental concept of this
invention and its implementation are illustrated. A friction
welding apparatus as schematically illustrated is shown in FIG. 1
as connecting elements of a structural assembly 10 to be
incorporated into a vehicle body-in-white assembly. The structural
assembly 10 includes first and second joints 12 and 14. In the
structural assembly 10, a first component 16 is in the form of a
lineal member having a first end 18 and a second end 20. The first
and second ends 18 and 20 of the first component 16 are shown in
FIG. 1 as being friction welded to separate components at each end
thereof as at 22 on the right hand side and 24 on the left hand
side. Other than being disposed at opposite ends of the first
component 16, the components 22 and 24 may be substantially
identical and symmetrical. Accordingly, only one set of reference
characters will be used to describe like features of the right- and
left-handed components. It will be appreciated by those skilled in
the art that different or non-symmetrical components may be
attached at opposed ends of the first component 16 or that only one
end of the lineal member may have a second component attached to
it.
[0037] The second component 22 includes a body portion 26 with a
first face 28 and a second face 30. The body 22 defines an opening
32 extending from the first face 28 to the second face 30.
Preferably, a cylindrically shaped boss 34 extends from the first
face 28 and terminates in a boss face 42. The opening 32 extends
through the boss 34 such that the end 18 of the first component 16
is received therein. When properly arranged, the boss face 42 and
end 18 of the first component 16 are coterminous as at 44.
[0038] A third element of the joint 12 is a cap member 46. The cap
member 46 includes a body portion 48 having a first face 50, a
second face 52 and an edge portion 54. The cap member 46 is
friction welded onto the coterminous boss face 42 and the end 18 of
the first component 16 as at 44 by engaging the cap member 46 with
a friction welding apparatus F and rotating the cap member 46 under
pressure. The cap member 46 is rotated in the direction of arrow A
at a speed of about 200 to about 1000 revolutions per minute and
the second face 52 is urged in the direction of arrow B against the
coterminous boss face 42 and end 18 at a force of about 500 to
about 2000 pounds per square inch (referred to as the upset force)
for a period of about one minute. The speed of rotation of the cap
member 46, the upset force and the welding time may vary depending
on the materials used. The second face 52 of the cap member 46, the
boss face 42, and the end 18 may all be similar or dissimilar
materials, such as aluminum alloys, steel, or ceramics. The cap
member 46 may include an engaging means (not shown) such as a
hexagonal hole which is adapted to engage a friction welding
spindle of the friction welding apparatus F.
[0039] FIG. 2 shows a more complete subassembly S which may
consitute for example, the rear clip of a vehicle body-in-white.
Subassembly S may include a plurality of cast components C, a
plurality of lineal components L, and a plurality of extruded
components E in a spaced relationship. Lineal components L
correspond to the first component 16 described above with cast
component C and extruded components E correspond to the second
components 22 and 24. A plurality of cap members 46 secures the
components C, L, and E in a fixed relationship. In utilizing the
joint structure of this invention, the first component 16 or lineal
component L may be formed from either an extruded or sheet product
form. It will be shown below that this invention contemplates the
use of an improved processes and sheet product formation
methodology to create the lineal member end configuration to
cooperate in the joint structure of this invention. The second
component 22 of FIG. 1 may include, for example, a cast component C
or an extruded component E. In the use of the cast component C, the
boss 34 may be cast into the structure C. In the use of an extruded
component E, the boss 34 may be formed during the working of the
sheet metal or by the attachment of a cast or sheet formed or
extruded boss onto the face of the product C or E. As should be
appreciated, substantially all of the joints between components L
and each of components C and E shown in the subassembly S of FIG. 2
can be produced according to the present invention.
[0040] FIG. 3 shows an alternative cap member 46' used in the joint
12. The alternative embodiment cap member 46' includes body portion
48 with first face 50 and an annular second face 52' surrounding a
recessed portion 62. In all other respects, the annular second face
52' of the cap member 46' is attached to the coterminous faces of
the boss 34 and the first end 18 of first component 16 as described
for cap member 46. In this detailed cross-sectional view of joint
12, the first component 16 is shown to consist of a lineal member
having a non-constant cross-section. While a friction welded joint
requires that the coterminous ends (e.g., of boss 34 and end 18)
have circular cross-sections, it is possible to hydroform an
extruded member to have a non-constant cross-section.
[0041] Alternatively, the first component may be formed from a
sheet product. Turning to FIGS. 4A and 4B, several variations in
the structure and form of a lineal member are illustrated. In FIG.
4A, a first component 16' in a sheet product form has a first end
18 that is circular in cross-section. This alternative embodiment
of the lineal member 16' is shown having a generally rectangular
cross-section in at least a portion of its length as at 62. With
the end 18 formed into a circular cross-section, friction welding
may still be used in the attachment of this lineal member 16 to a
second component by means of cap member 46. It is preferred that a
first component 16 made from sheet product include a reinforcing
bead 64 to provide additional stiffness to the first component 16.
Such stiffness facilitates the friction welding of the first
component 16 during the formation of the joint. The bead 64 can be
formed in a sheet product by a stamping operation. As shown in the
detail of FIG. 4B, the first end 18 of first component 16 made from
a sheet product may include a cross-sectional junction as at 66. In
order to enhance the strength of this junction 66, which will
facilitate the friction welding of the first component 16 according
to the joint structure of this invention, it is preferred that the
ends of the sheet be overlapped as at 68 and 70. Assuming, for
example, that the rotation of the cap member during the friction
welding process is in a clockwise direction as the end 18 is viewed
in FIG. 4B, it is preferred that the overlapped portion 70 be
blunted or rounded off as at 72 in order to minimize the likelihood
of damage to the junction during the high speed rotation of the cap
member during the friction welding process. The overlapping end 68
need not be rounded or blunted as at 74.
[0042] The boss 34 shown in FIGS. 1 and 3 is integrally formed with
the second component 22. In other instances, as shown in FIG. 5, it
may be necessary to include a separate boss 80 that is fixed to the
component 22. The boss 80 may be a cast member and may be welded to
the component 22 to create a suitable boss face 42. It is another
preferred feature of the joint of the present invention to provide
means to transmit loading from the joint to the rest of the vehicle
structure of which the joint is a part. The joints shown in FIGS.
1, 3, and 4 define a gap between the first component 16 and the
boss 34 or 80. Gaps between the first component 16 and boss 34 or
80 may occur because of the compounding of the dimensional
tolerance build-up of parts when fixtured or clamped for final
joint formation through friction welding or alternative attachment
processes. Accordingly, a sleeve 82 shown in FIGS. 5 and 6 may be
used to substantially eliminate any gap existing between the first
component 16 and the boss 34 or 80 of the second component 22.
Referring to FIG. 5, sleeve 82 is inserted into a gap 84 between
the boss 80 and the first end 18 of the first component 16. In a
preferred embodiment, an inner face of the boss 80 tapers inwardly
from a first diameter proximate the boss face 42 to a second,
lesser diameter distal therefrom. As will be appreciated, several
embodiments of the sleeve 82 may be used in conjunction with the
joint structure of this embodiment.
[0043] As shown in FIG. 6, the sleeve 82 is a ring-like member that
may be discontinuous, that is, it may define a split 88 to permit
the sleeve 82 to have an inside diameter which is variable between
a minimum and maximum limit. The sleeve 82 is adapted to be
inserted between the boss inner face 86 and the first component 16
such that the cap member 46 retains the sleeve 82 thereinbetween.
As shown in FIG. 5, a first face 90 of the sleeve 82 may be
coterminous with the boss face 42 and the first end 18 of the first
component 16. During the attachment of the components of this joint
by means of the cap member 46, the sleeve 82 may be friction welded
in place. Alternatively, various other forms of joining may be used
to fixedly secure the components of this joint structure in
place.
[0044] It may be desirable to not involve the sleeve 82 in the
friction welding process. This may be accomplished using a sleeve
82' shown in FIG. 7. The alternative sleeve member 82' includes a
split 88 which permits the inside diameter of the sleeve 82' to
vary from a predetermined minimum to a maximum diameter. However,
unlike sleeve 82, sleeve 82' has a discontinuous outer face 90'
making sleeve 82' particularly well suited for friction welding of
the cap member 46. The discontinuous face 90' includes a plurality
of spaced apart teeth 92. The teeth 92 serve to break the
continuity of the interface between the first face 90' and the cap
member 46, thus leading to excessive oxide dragging into the
friction weld and premature bending of the teeth. This prevents the
formation of sound and strong welds between the cap member 46 and
the first face 90'. As a result, once the sleeve 82' is forced by
the cap member 46 during the friction welding cycle into intimate
contact with the boss inner face 86, the sleeve 82' stays in place
without being spun when the cap member 46 is rapidly decelerated.
In other words, the sleeve 82' is decoupled from the decelerating
cap member 46 by breaking the inferior welds formed between the
face 90 of the sleeve 82' and the cap member 46 during the final
stage of the friction welding cycle. As shown in FIG. 8, the sleeve
82' may be sized to extend slightly beyond the boss face 42, e.g.,
by about 0.5 mm. When the cap member 46 is placed against the boss
face 42 and end 18 of first component 16, the sleeve 82' is forced
against the tapered inner face 86 of the boss 80 until the ends of
the teeth 92 of the sleeve 82' are coterminous with the boss face
42 and the end 18.
[0045] An alternative cap member 46' is shown in FIG. 9 for use in
conjunction with the alternative sleeve 82'. The teeth 92 are
slightly compressed within the recessed portion 62, such
compression being facilitated by the split 88 in the sleeve 82'.
This embodiment may be assembled prior to the friction welding or
ultimate assembly process. This ensures that the sleeve 82' will be
inserted in the gap between the boss inner face 86 and the exterior
surface of the first component 16 while only the end 18 and the
boss face 42 contact the second face 52' of the cap member 46'.
[0046] Another embodiment of the invention is shown in FIGS. 10A
and 10B in which a second component 100 includes an integrally
formed ring 102 having a boss face 104. The first component 16 is
received within a tapered opening 106 in the ring 102 such that the
end 18 is coterminous with the boss face 104. An inner face 108 of
the ring 102 has a diameter which increases from a first dimension
proximate the boss face 104 to a second dimension distal therefrom.
A sleeve 110 is received within the opening 106 between the first
component 16 and the ring inner face 108. The sleeve 110 has a
tapered wall 112 which is sized to tightly fit within the tapered
opening 106. The wall 112 includes a plurality of serrations 114
which enhance the mechanical bond between the wall 112 and each of
the first component 16 and the ring inner face 108. This embodiment
is particularly suited for welding to a second component having
physical constraints which prevent the use of the arrangements
shown in FIGS. 1, 5, and 8.
[0047] Building on the concepts described above in connection with
the attachment of a cap member to a lineal member, what is
disclosed herein particularly in conjunction with FIGS. 11-15 is an
assembly approach in which lineals having end attachments secured
thereto are joined to other parts with which they form desired
automotive structures. More specifically, although the preferred
joining process for attaching the end attachments or cap members to
the lineals are friction welding and flash welding, it is to be
appreciated that the concept can also be implemented by employing
other joining processes that are cost-effective for given
applications and that minimize heat input into the lineals.
Examples of such processes include magnaforming, MIAB (magnetically
impelled act butt welding), laser welding, and low heat input types
of GMA (gas metal arc) welding. In its most basic construct, this
embodiment incorporates the steps of joining a cap member to a
lineal in which the cap member has certain further attachment means
incorporated thereinto and assembling the joined cap member/lineal
assembly to another component. These steps are shown in FIGS.
11A-11C in which a structural assembly generally indicated by the
reference character 210 (FIG. 11C) includes at least first and
second joints 212 and 214 between first component 216 (having a
first end 218 and a second end 220) and right- and left-handed
structural components 222 and 224. Additional joints are
illustrated but will not be discussed directly.
[0048] Returning to FIG. 11A, a cap member 246 includes a body
portion 248, a first face 250, a second face 252, and an edge
extending therebetween as at 254. The cap member 246 defines a bore
through which an attachment means, such as a bolt 256 extends and
is fixedly retained therein. Bolt 256 includes a threaded portion
258 that is configured to receive a nut 260. The bolt 256 may be
retained within the cap member 246 by any number of appropriate
processes including adhesive bonding and welding, by way of
example. Cap members 246 are joined to the first component 216 via
friction welding the first component ends 218 and 220 to faces 252.
As shown in FIG. 11B, a threaded nut 260 is provided to cooperate
with the threaded bolt 256. Assembly 210 can be formed for example
as shown in FIGS. 11C and 12. Each of the structural components 222
and 224 define openings in which first components 216 are received.
Here, two sets of first component 216 joined to cap member 246 are
disposed between structural components 222 and 224. Nuts 260 and
optional locking washer 266 in cooperation with bolts 256 secure
cap members 246 to the walls or body portions of structural members
222 and 224 to complete the assembly 210.
[0049] Turning to FIG. 13A, there is shown a portion of another
assembly 210' of this invention in which a compliant washer 268
(e.g., a Bellville washer) is disposed between first face 250 of
cap member 246 and an inner surface of structural member 222. The
compliant washer 268 allows the assembly 210' to accommodate
variations in the lengths of the first component 216. Another
mechanism for accommodating varying length of components in an
assembly 210'' is shown in FIG. 13B. A first component 216'
includes a deformed or bent portion 270. Bent portion 270 allows
the first component 216' to compress during construction of the
assembly 210''.
[0050] Turning to FIGS. 14A-14D, there are illustrated multiple
embodiments by which a cap member may be secured to a first
component for use for example in the assemblies shown in FIGS. 11C,
12, 13A and 13B. FIG. 14A shows a "T" joint 212a formed between cap
member 246a and first component 216 when the cap member 246a is
friction welded to the first component 216 by rotating the cap
member 246 against the first component 216 under pressure as
described above. In FIG. 14B, cap member 246b includes lip 272
having a rim 274 to which first component 216 is friction welded
thereby forming a butt weld 212b. As a result of friction welding,
flash may be formed exterior to the first component 216. It may be
desirable to avoid producing visible flash for either structural
and/or aesthetic reasons. Hiding of flash can be accomplished
through the use of alternative configurations shown in FIGS. 14C
and 14D. Referring to FIG. 14C, cap member 246c defines a recess
276 bounded by face 278 and into which first component 216 is
received. First component 216 abuts face 278 and is friction welded
thereto to form a "T joint". Flash formed in the friction welding
process is collected in the recess 276 between the first component
216 and rim 272 of cap member 246c. Alternatively, as shown in FIG.
14D, cap member 246d includes a joining member 280 extending from
face 278 which has substantially identical cross-sectional
dimensions as the first component 216. Joining member 280 and first
component 216 are friction welded together. Flash formed thereby
collects in recess 276 between rim 272 of cap member 246 and
joining member 280.
[0051] Other mechanisms for fixing a first component (lineal
member) prejoined to a cap member to other portions of an assembly
as alternatives to the mechanisms shown in FIGS. 11C, 12, 13A and
13B are depicted in FIGS. 15A-B. In the mechanism shown in FIG.
15A, a cap member 246' includes an integrally formed stud 256'
which may be threaded so as to receive thereon threaded nut 260.
Self-locking washer 266 may be disposed between the outer surface
of the structural member 224 and the nut 260. FIG. 15B shows the
use of cap member 246 friction welded to first component 216 as
described in reference to FIG. 14A. Face 50 of cap member 246 may
be fixed to an inner surface of structural component 224 at
locations 282 via friction stir welding (FSW), or laser welding
(LW) respectively. Bolting and riveting may also be used in lieu of
welding.
[0052] When the friction welding process is used to preassemble the
lineals 216, 216' with the cap members 246, 246' and these
components may be made from different materials that normally would
not be weldable. Examples of this include stainless steel cap
members attached to 6xxx or 7xxx lineals or 7xxx cap members
attached to 6xxx lineals. The flexibility of this invention
broadens the assortment of designs and joining options for
automotive structures that may incorporate in their body-in-white
the assembly and joint techniques of this invention.
[0053] The friction welded joints of the present invention are
particularly well adapted for use as in an assembly of an energy
absorbing member such as a bumper. The assembly may be more
readily, more easily, and more inexpensively produced than standard
assembly processes utilizing welding, bolting, or riveting. FIG. 16
shows an energy absorbing assembly 300 including a bumper beam 302,
with crash boxes 304 connected at one end to the bumper beam 302
via bumper brackets 306 and connected at the other end to
attachment brackets 308. Attachment brackets 308 are configured to
be removably mounted to a vehicle. The bumper brackets 306 are
fixed to the bumper beam 302 preferably via welding, such as GMA
(gas metal arc) welding as indicated at 310. The crash boxes 304
are cylindrical at least at their ends. As such, crash boxes 304
are friction welded to the bumper brackets 306 and attachment
bracket 308. The friction weld joint between a crash box 304 and an
attachment bracket 308 is shown in FIG. 17A. Flash 312 forms at the
location of the friction weld joint. The flash 312 can be
mechanically removed by subsequent process after the welding is
completed. Alternatively, as shown in FIG. 17B, an attachment
bracket 308' may be used which includes a raised portion 314 with
an opening therein extending into a recessed chamber 316 bounded in
part by welding surface 318. The crash box 304 is friction welded
to surface 318 within recessed chamber 316. Flash 312 created in
friction welding is retained within the recessed chamber 316.
Likewise, as shown in FIG. 17C, a bumper bracket 306' may include a
raised portion 320 with an opening therein extending into a
recessed chamber 322 bounded in part by welding surface 324. Flash
312 created when crash box 304 is friction welded to surface 324 is
retained within the recessed chamber 322.
[0054] Due to the principal dependence of the friction welding
process on the rapid and controlled application of rotational
(i.e., kinetic) energy and axial force (i.e., pressure) at the
faying surfaces being joined, the process achieves several key
results. First, the process yields extremely consistent joint
quality with aluminum. Typically, there are no objectionable
discontinuities in the joint. This results in a substantial
reduction in the required amount of both destructive and
non-destructive tests of these friction weld joints during
production. Obvious cost savings result from this quality welding
process. Secondly, the process has very little dependence on the
dimensional tolerances of the crash boxes and brackets. This
significantly reduces the need and cost of having to closely
maintain the tolerances of such parts. Cylindrical crash boxes can
simply be saw-cut in preparation for friction welded joining.
Thirdly, this process will minimize if not eliminate completely the
costly step of surface treating which is essential with other
welding processes. Additionally, because friction welding is a
low-heat input process with extremely firm and precise holding of
parts, there will be very small weld-induced distortions caused by
joining the crash boxes and brackets. In addition, close control
over stopping the cycle can yield plus or minus one percent angular
registration between joint brackets. This in conjunction with the
limited GMA welding of the bumper brackets to the bumper may quite
possibly make it feasible to accomplish all machine/drilling of the
components prior to assembly. Moreover, because friction welding
involves very rapid application of low heat to effect the joining,
it becomes practically alloy independent. Unlike the GMA welding
process which requires careful selection of base metals/filler
alloy combinations, friction welding enables joining the crash
boxes 304 to brackets 306 and 308 with almost any aluminum alloy
combination.
[0055] It should be appreciated that subframes and subassemblies
such as even, for example, engine cradles, that are based on the
use of tubular components friction welded to components with
multi-faceted (that is square or rectangular or combinations of
curvilinear portions) cross-sections, will facilitate a variety of
designs that are more economically produced and assembled.
Obviously, for the use of the friction welded process as disclosed
herein in combination with the various elements shown, tubular
aluminum components can consist of extrusions that are friction
welded to components with multi-faceted cross-sections. The joining
of bumper mounting brackets to the bumper can be done with riveting
or bolting instead of gas metal arc welding. The bumper mounting
brackets and attachment brackets may be produced from stampings,
castings, and/or extrusions. In the case of extrusions, straight
length extrusions could be simply cut to length.
[0056] It is to be appreciated since both the friction and flash
welding processes require minimal joint preparations, that is
joints as received and as saw-cut parts with minimal or no
cleaning, for the joining of the cap members to the respective
lineals, a significant cost reduction may be realized by adapting
the proposed assembly approach of this invention. Additionally, by
the provision of attachment means to the cap member, a further cost
reduction will be realized by using the very simple joining process
that is bolting or riveting during the final assembly stage.
[0057] It will be readily appreciated by those skilled in the art
that modifications may be made to the invention without departing
from the concepts disclosed in the foregoing description. Such
modifications are to be considered as included within the following
claims unless the claims, by their language, expressly state
otherwise. Accordingly, the particular embodiments described in
detail herein are illustrative only and are not limiting to the
scope of the invention which is to be given the full breadth of the
appended claims and any and all equivalents thereof.
* * * * *