Joints and connections – Rod side to plate or side – Lapped rod ends
Reexamination Certificate
2000-02-24
2002-03-26
Browne, Lynne H. (Department: 3629)
Joints and connections
Rod side to plate or side
Lapped rod ends
C403S345000
Reexamination Certificate
active
06361244
ABSTRACT:
TECHNICAL FIELD
This invention relates to hydroformed tubular structures including hydroformed joints at which members or parts of the structures are fixed to one another and to methods of making such hydroformed joints. In particular, the invention involves hydroformed conjugate joints, such as might be used in vehicle structures.
BACKGROUND OF THE INVENTION
The application of hydroformed tubular components in vehicle structure assembly is attracting increasing interest in the automobile industry at this time. One of the important factors for successful applications of this technology is to effectively join two or more essentially closed box section components together in a manner which provides satisfactory structural performance as well as manufacturing and assembly efficiency.
Traditional joining methods for a typical lap joint are shown in
FIGS. 1 and 2
, and for a T-joint in
FIGS. 3 and 4
. These methods usually require relatively expensive secondary operations after the hydroforming process to end trim or cut the ends of the box sections of the joining members. A saw cut, plasma cut, or laser cut process is usually employed in these secondary operations which may involve significant tooling costs, require control of trimming quality and have excessive cycle time for completing these operations. In addition, the traditional hydroformed joint designs may have relatively weak stiffness of their box sections in resisting local buckling.
In a conventional lap joint
10
illustrated in
FIGS. 1 and 2
, a trimmed hydroformed end
12
of one member
14
is slid inside a trimmed hydroformed member
16
through a cutout
18
in a side
20
of the member
16
. The assembled components
14
,
16
are then fixed together, such as by through bolts or welding.
In a conventional T-joint
22
shown in
FIGS. 3 and 4
, one hydroformed tubular member
24
has opposite sides
26
cut out to form depending legs
28
. In assembly, the legs
28
straddle opposite sides
30
of a second hydroformed tubular member
32
to form the T-joint
22
, the members being preferably welded together. Both of these arrangements form box section structures with limited structural strength, particularly for bending and torsional loads.
SUMMARY OF THE INVENTION
The present invention provides improved joint structures for hydroformed tubular members in which the joint structures are formed by simplified manufacturing processes that reduce the cost of manufacturing. The strength of the resulting hydroformed tubular structure may also be increased.
For both lap joint and T-joint structures, a hydroformed tubular structure according to the invention connects at least two hydroformed members at a joint including, in at least one of the members, a flat portion at one end with an adjacent hydroformed conjugate portion. The conjugate portion is adapted to engage a recess in a second member and the flat portion is adapted to be secured to an adjacent portion of the second member.
In a preferred embodiment of a lap joint, two or more members having hydroformed conjugate ends may be formed from a single tubular member in a single hydroforming process. The resulting hydroformed ends each include a flattened portion offset toward one edge and having opposite sides smashed into engagement, and a hydroformed conjugate portion offset toward an opposite edge and having one side extending upward from the flat portion. The similarly formed ends are mated by having the raised conjugate portions of the two ends each engage the flat portions of the other member. The flat portions thus form the recesses in which the conjugate portions are received. The resulting joint may be held in assembly by bolts extending through openings in the conjugate portions and their associated flat portions or the joint may be secured by welding.
A method of making a hydroformed tubular structure with the lap joint as described above involves: placing in a hydroforming die a tubular member having opposite ends, filling the tubular member with hydroforming liquid prior to completely closing the die, flattening at least one portion of the tubular member between its ends by forcing opposite sides of the member into engagement upon completing closing of the die, and increasing the pressure of the liquid in the member to hydraulically expand or hydroform the member against the surrounding die to obtain a predetermined configuration. The hydroformed shape includes expanded conjugate portions adjacent the flattened portion. The engaged sides of the flattened portion must allow sufficient liquid flow therethrough to permit pressurizing the member from one of the ends. The flattened portions of the member are then trimmed to form a plurality of separated hydroformed parts, each having at least one flattened end portion with an adjacent expanded conjugate portion. Each joint is then formed by securing the flattened portion of a first one of the parts to a conjugate portion of a second part having a recess receiving the conjugate portion of the first part.
In forming a lap joint, the first and second parts may be formed from the same hydroformed member. The flattened portions are located at trimmed ends separated in the trimming step, the trimmed ends having interengaging expanded conjugate portions secured to the flattened portions of the other part to form the joint. In forming a T-joint, the first part includes a flattened end with an inwardly adjacent expanded conjugate portion and the second part is formed as a tubular hydroformed member with a recess in part of one side so that the flattened end is secured to that side adjacent the recess and the conjugate portion is received in the recess.
These and other features and advantages of the invention will be more fully understood from the following description of certain specific embodiments of the invention taken together with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIGS. 1 and 2
are pictorial views of a conventional prior art lap joint design illustrating the joint in respective exploded and assembled conditions;
FIGS. 3 and 4
are pictorial views illustrating a conventional prior art T-joint design in respective exploded and assembled conditions;
FIGS. 5 and 6
are pictorial views showing a hydroformed structure with a lap joint formed according to the invention and illustrated in respective exploded and assembled conditions;
FIG. 7
is a tubular hydroformed radiator support assembly including an upper frame assembly utilizing dual lap joints according to the invention;
FIG. 8
is an enlarged pictorial view of a hydroformed member having adjacent flattened and conjugate portions ready for trimming to form separate ends of parts to be assembled as a lap joint in a subsequent step;
FIG. 9
is a pictorial view showing an assembled lap joint made from the trimmed and cut ends formed from the hydroformed member of
FIG. 8
; and
FIGS. 10 and 11
are pictorial views illustrating a hydroformed tubular structure connected by a T-joint according to the invention and shown in respective exploded and assembled conditions.
REFERENCES:
patent: 1398695 (1921-11-01), Hull
patent: 1972309 (1934-09-01), McMurchy
patent: 2576049 (1951-11-01), Shott
patent: 2881017 (1959-04-01), Millar, Jr.
patent: 2982572 (1961-05-01), Farber
patent: 3253842 (1966-05-01), Rabe
patent: 3355195 (1967-11-01), Takayanagi et al.
patent: 3704849 (1972-12-01), Green
patent: 3927950 (1975-12-01), Herrmann et al.
patent: 4557622 (1985-12-01), Chalmers
patent: 5285612 (1994-02-01), Johnson
patent: 5720092 (1998-02-01), Ni et al.
patent: 5862877 (1999-01-01), Horton et al.
patent: 5927893 (1999-07-01), Imamura et al.
patent: 6098437 (2000-08-01), Kocer et al.
patent: 6227321 (2001-05-01), Frascaroli et al.
Bartholomew Thomas B.
Ni Chi-Mou
Peng Tehui
Browne Lynne H.
Cottingham John R.
General Motors Corporation
Hargitt Laura C.
LandOfFree
Hydroformed tubular structures and methods of making does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hydroformed tubular structures and methods of making, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hydroformed tubular structures and methods of making will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2859216