U.S. patent application number 10/780334 was filed with the patent office on 2004-11-18 for hollow section and a process for its manufacture.
This patent application is currently assigned to Alcan Technology & Management Ltd.. Invention is credited to Chitic, Valentin, Kohler, Peter.
Application Number | 20040226250 10/780334 |
Document ID | / |
Family ID | 32683505 |
Filed Date | 2004-11-18 |
United States Patent
Application |
20040226250 |
Kind Code |
A1 |
Chitic, Valentin ; et
al. |
November 18, 2004 |
Hollow section and a process for its manufacture
Abstract
A hollow section made of a metal alloy and having at least one
hollow space which is delimited by walls featuring end lengths
forming corner regions. The walls exhibit at least in part
different thicknesses in cross-section. The thickness of the end
length of the walls diminishes in a continuous manner to a smaller
thickness. The facing and approximately parallel outer walls of the
hollow section are joined on the inside by at least one integral
inner wall. The outer walls along with the inner walls delimit a
plurality of hollow chambers and the walls of each chamber exhibit
in each case a middle length of constant thickness and at both ends
thereof an end length of increasing thickness.
Inventors: |
Chitic, Valentin; (Lauffen
am Neckar, DE) ; Kohler, Peter; (Schaffhausen,
CH) |
Correspondence
Address: |
OSTROLENK FABER GERB & SOFFEN
1180 AVENUE OF THE AMERICAS
NEW YORK
NY
100368403
|
Assignee: |
Alcan Technology & Management
Ltd.
|
Family ID: |
32683505 |
Appl. No.: |
10/780334 |
Filed: |
February 17, 2004 |
Current U.S.
Class: |
52/633 |
Current CPC
Class: |
B21C 37/155 20130101;
B21C 23/14 20130101; B21C 37/151 20130101; B60R 19/34 20130101 |
Class at
Publication: |
052/633 |
International
Class: |
E04C 003/30 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 17, 2003 |
DE |
103 06 749.3 |
Apr 9, 2003 |
DE |
103 16 516.9 |
Claims
1. A hollow section comprising walls that delimit a hollow space,
the walls having end lengths that form corner regions, the end
lengths have a cross-sectional thickness that diminishes in a
continuous manner to a smaller thickness.
2. The hollow section according to claim 1, wherein the thickness
of the end length of one wall of the hollow section is constant
over a length starting from a corner region and begins to have a
narrowing cross-section at a bottom end point of the length.
3. The hollow section according to claim 1, wherein one wall has a
thickness reduced in a constant manner from one corner region to
another corner region of the hollow section.
4. The hollow section according to claim 2, wherein the length of
the end length of the wall corresponds to one third to one quarter
of an overall length of the wall.
5. The hollow section according to claim 1, wherein the end length
of one wall which diminishes in cross-sectional thickness from one
corner region of the hollow section joins a length of the wall that
increases in thickness.
6. The hollow section according to claim 5, wherein the walls
include having a wall section with an end length of constant
thickness that connects with a transverse wall at one end, and
tapers in cross-section to a smaller thickness in a continuous
manner starting from an end point of the end length.
7. The hollow section according to claim 6, wherein another
transverse wall intersects the wall provided with an end length of
constant thickness.
8. The hollow section according to claim 1, wherein each wall of
the hollow section has a length of constant thickness in a middle
region between two end lengths of diminishing thickness to each
other.
9. The hollow section according to claim 1, wherein two facing
outer walls of the hollow section are connected on an inner side by
at least one integral inner wall.
10. The hollow section according to claim 9, wherein the two facing
walls are substantially parallel to each other.
11. The hollow section according to claim 9, wherein the outer
walls along with the inner walls delimit a plurality of hollow
chambers, the walls of each chamber having a middle part of
constant thickness and at both ends of the middle part an end part
of increasing thickness.
12. The hollow section according to claim 9, wherein the outer
walls define a rectangular cross-section with a center in a region
of crossing of a pair of inner walls.
13. The hollow section according to claim 11, wherein the
cross-sectional length of the middle part corresponds to
approximately double the cross-sectional length of the integral end
part.
14. The hollow section according to claim 1, wherein the walls have
end parts with a wall thickness that increases in a continuous
manner up to the corner region.
15. The hollow section according to claim 9, wherein a wall
thickness of an end part of the inner wall increases in a
continuous manner up to the outer wall whereby a central plane
forms a plane of symmetry.
16. The hollow section according to claim 8, wherein a maximum wall
thickness of an end part of a wall is at least 5% greater than a
thickness of a part of the wall neighboring the end part of the
wall.
17. The hollow section according to claim 16, wherein the maximum
wall thickness of the end part is at least 15% greater than the
thickness of the neighboring part of the wall.
18. The hollow wall section according to claim 17, wherein the
maximum wall thickness of the end part is at least 20% greater than
the neighboring part of the wall.
19. The hollow section according to claim 8, wherein a maximum wall
thickness of an end part of the wall is at most 200% greater than a
thickness of a part of the wall neighboring the end part of the
wall.
20. The hollow section according to claim 19, wherein a maximum
wall thickness of the end part is at most 100% greater than the
thickness of the neighboring part of the wall.
21. The hollow section according to claim 20, wherein a maximum
wall thickness of the end part is at most 60% greater than the
thickness of the neighboring part of the wall.
22. The hollow section according to claim 8, wherein an average
wall thickness of an end part of the wall is at least 5% greater
than an average thickness of the wall part neighboring the end part
of the wall.
23. The hollow section according to claim 22, wherein the average
thickness of the end part is at least 15% greater than the average
thickness of the neighboring wall part.
24. The hollow section according to claim 23, wherein the average
wall thickness of the end part is at least 20% greater than the
average thickness of the neighboring wall part.
25. The hollow section according to claim 8, wherein an average
wall thickness of an end part of the wall is at most 200% greater
than an average thickness of a part of the wall neighboring the end
part of the wall.
26. The hollow section according to claim 25, wherein the average
thickness of the en d part is at most 100% greater than the average
thickness of the neighboring wall part.
27. The hollow section according to claim 26, wherein the average
thickness of the end part is at most 60% greater than the average
thickness of the neighboring wall part.
28. The hollow section according to claim 8, wherein the wall
thickness of the wall length neighboring the end lengths of the
wall is uniform.
29. The hollow section according to claim 8, wherein each wall has
an outer face that is flat and a corresponding inner wall face in
end regions of the wall has a slope with respect to the outer face
which increases the wall thickness.
30. The hollow section according to claim 9, wherein a maximum wall
thickness of an end part of a wall is at least 5% greater than a
thickness of a part of the wall neighboring the end part of the
wall.
31. The hollow section according to claim 30, wherein the maximum
wall thickness of the end part is at least 15% greater than the
thickness of the neighboring part of the wall.
32. The hollow wall section according to claim 31, wherein the
maximum wall thickness of the end part is at least 20% greater than
the neighboring part of the wall.
33. The hollow section according to claim 9, wherein a maximum wall
thickness of an end part of the wall is at most 200% greater than a
thickness of a part of the wall neighboring the end part of the
wall.
34. The hollow section according to claim 33, wherein a maximum
wall thickness of the end part is at most 100% greater than the
thickness of the neighboring part of the wall.
35. The hollow section according to claim 34, wherein a maximum
wall thickness of the end part is at most 60% greater than the
thickness of the neighboring part of the wall.
36. The hollow section according to claim 9, wherein an average
wall thickness of an end part of the wall is at least 5% greater
than an average thickness of the wall part neighboring the end part
of the wall.
37. The hollow section according to claim 36, wherein the average
thickness of the end part is at least 15% greater than the average
thickness of the neighboring wall part.
38. The hollow section according to claim 37, wherein the average
wall thickness of the end part is at least 20% greater than the
average thickness of the neighboring wall part.
39. The hollow section according to claim 9, wherein an average
wall thickness of an end part of the wall is at most 200% greater
than an average thickness of a part of the wall neighboring the end
part of the wall.
40. The hollow section according to claim 39, wherein the average
thickness of the en d part is at most 100% greater than the average
thickness of the neighboring wall part.
41. The hollow section according to claim 40, wherein the average
thickness of the end part is at most 60% greater than the average
thickness of the neighboring wall part.
42. The hollow section according to claim 9, wherein the wall
thickness of the wall length neighboring the end lengths of the
wall is uniform.
43. The hollow section according to claim 9, wherein each wall has
an outer face that is flat and a corresponding inner wall face in
end regions of the wall has a slope with respect to the outer face
which increases the wall thickness.
44. A process for shape forming a hollow section comprising walls
that delimit a hollow space, the walls having end lengths that form
corner regions, the end lengths have a cross-sectional thickness
that diminishes in a continuous manner to a smaller thickness,
comprising the step of deforming the shallow section by creating
high internal pressure in an interior of the section by means of a
medium capable of flow.
Description
BACKGROUND OF THE INVENTION
[0001] The invention relates to a hollow section or similar
workpiece having a hollow space delimited by walls featuring end
lengths which together form corner regions. In particular, the
invention relates to a hollow section made of a metal alloy. The
invention further relates to a process for manufacturing the hollow
section.
[0002] According to the state of the art, tube-shaped or
hollow-section-like deformation elements are employed to
accommodate the energy of impact acting on them from the front end.
The absorption of the energy of impact takes place by the section
walls folding uniformly when the deformation element is crushed.
Thus, for example, CH-A 691 721 describes a vehicle with a bumper
which is attached to longitudinal beams via deformation elements.
The deformation elements comprise multi-chamber hollow sections
that have at least one longitudinal internal strut. A part of the
energy of impact is absorbed by bellow-like folding as the
deformation element is crushed in the longitudinal direction of the
section.
[0003] Such deformation elements should exhibit the maximum
possible specific absorption of energy i.e. as much energy as
possible per unit mass should be absorbed. Only then is it possible
to meet the requirements for the lightest and simultaneously safe
vehicles--i.e. vehicles fitted with energy-absorbing
structures.
[0004] German reference DE 35 32 499 C1 describes a process and
device for hydraulic expansion of a length of tube by means of a
plug-like probe that can be inserted into the tube and which,
because of sealing rings that are spaced apart, forms a ring-shaped
space along with the length of tube that is to be expanded. This
space is filled with a compressive medium for expansion of the tube
length. Each of the sealing rings is situated in the probe in a
ring-shaped groove which is U-shaped in cross-section and
initially, on insertion of the probe into the tube, has an outer
diameter that corresponds at most to the outer diameter of the
probe. Before the expansion process begins, a compressive medium is
applied to them in order to seal off the ring-shaped gap formed
between the probe and the tube. The compressive medium is fed to
the grooves by means of a medium feed-line with connecting line
attached. The supply of compressive medium to the ring-shaped space
takes place exclusively via at least one of the grooves and is
channeled through a sealing ring serving as a valve body which
closes off an opening between the groove and the ring-shaped space
until it has achieved its sealing property as a result of elastic
expansion. At its edge neighboring the ring-shaped space, that
groove is provided with at least one sloping cut. If the pressure
in the ring-shaped space between the two seals is increased, the
wall of the tube begins to expand in this region.
[0005] When calibrating, corners or sudden changes in wall
thickness cause non-uniform deformation. Also, walls of different
thickness expand non-uniformly under high internal pressure
forming. If two such walls begin from a corner, then both walls are
pressed onto the shaping tool as a result of the high internal
pressure. The thicker wall remains there while the thinner wall--as
a result of the smaller moment of resistance--is drawn into the
corner. This leads to a thinning of the thinner wall towards the
corner region.
[0006] In order to counter the risk of cracking due to weakening of
the component, and in order to achieve a constant wall thickness
for thermal connections, German reference DE 198 51 326 C1
proposes--on the thicker of the two walls, viz., end wall and side
wall, forming the corner--an end length of thinner wall extending
from the corner to the thinner wall, the thickness of which
corresponds approximately to that of the thicker wall. The
thickness of the end length is constant and, at an inner step, this
changes over to the thinner region of the thin wall. Foreseen in
another version is a corner that becomes thinner in cross-section
from the thicker wall, or an end length is curved in cross-section
between the thicker wall and the thinner wall and then preferably
features an arc-shaped inner contour of that cross-section or a
parabola-shaped inner contour.
SUMMARY OF THE INVENTION
[0007] In view of the above, the object of the present invention is
to provide a hollow section of the kind mentioned above, which
exhibits a higher specific absorption of energy than a conventional
deformation element. Furthermore, the resistance to rupture of such
hollow sections during forming and in use should be improved.
[0008] Pursuant to this object, and others which will become
apparent hereafter, one aspect of the present invention resides in
the thickness of the corner part of the wall joining up to the
corner region being reduced continuously to a smaller thickness
i.e. the cross-section of the wall decreases without steps--which
would form potential weak points. Two forms of design have proven
to be particularly favorable in this respect; in one case the
thickness of the end part of the wall of the hollow section is kept
constant over a length starting from the corner and begins to
diminish continuously at the foot of this end length; in the other
case the thickness of the wall diminishes constantly from one
corner region to the other corner region of the hollow section.
[0009] According to another feature of the invention, the length of
the above mentioned end part of the wall--in particular a section
side wall--amounts to about one third to one quarter of the wall
length.
[0010] Preferred is that a length of wall that becomes thicker is
joined up to--and runs counter to--the end length of wall which
narrows in cross-section from a corner region of the hollow
section. This wall consists, therefore, of two parts that become
thicker running counter to each other; the transition between these
has no steps and offers thereby the above mentioned advantages.
Likewise, the other shape can also be employed if a wall section,
featuring an end length of constant thickness that connects up with
a transverse wall at one end and tapers to a smaller thickness in
cross-section in a continuous manner from the other end, is
extended further by an integral wall section in the form of a wall
which in cross-section runs counter to the other transverse wall.
The other transverse wall may feature or be without an end length
of constant thickness.
[0011] In a further version of the hollow section according to the
invention the outer wall of the hollow section exhibits a middle
part of constant thickness, in each case between two end lengths of
diminishing thickness running counter to each other;. These end
lengths therefore flank the middle part and together with the
middle part produce an outer face on a common plane.
[0012] Also within the scope of the invention is that two facing
outer walls of the hollow section--preferably running parallel to
each other--are joined on the inside by at least one integral inner
wall. Thereby the outer walls along with the inner walls delimit a
plurality of hollow spaces and the walls of each section space
exhibit a middle length of constant thickness and increasing
thickness in both of its end lengths.
[0013] According to a further feature, the outer walls of the
hollow section exhibit a rectangular cross-section, the center of
which being the region where two inner walls cross each other. The
cross-sectional length of the middle part should thereby be about
double the cross-sectional length of the integral end part.
[0014] Usefully, the wall thickness of the end part of the outer
wall near the corner region increases in a continuous manner,
whereby a middle plane of the wall forms a plane of symmetry.
[0015] It has been found favorable for the maximum wall
thickness--or the average wall thickness--of the end length of the
section wall to be at least 5%, preferably at least 15%, and in
particular at least 20% greater than the wall thickness of the
length of section wall neighboring the end length of section wall,
or the maximum or average wall thickness of the end length of
section wall should be at most 200%, preferably at most 100%, in
particular at most 60% greater than the minimum wall thickness of
the length of section wall neighboring the end length of section
wall.
[0016] Finally, according to another feature of the invention, the
thickness of the length of section wall neighboring the end length
of section wall is uniform or constant. Also, the outer face of the
section wall should be flat and its inner section wall face in the
end lengths of section wall should exhibit a slope with respect to
the outer face which increases the wall thickness.
[0017] In each case the result is a new type of hollow section that
achieves the set objective in an attractive manner.
[0018] Of particular significance for the invention is that the
above mentioned hollow section should be shape-formed by means of a
high internal pressure in the section interior using a medium
capable of flow viz., so-called high internal pressure forming
(HIP-Process). With this method the hollow section is expanded
outwards by internal pressure. Further, the hollow section may be
subjected to compression by at least one tool which acts on the
workpiece at the end. This way the workpiece may be widened,
compressed or expanded.
[0019] For a more complete understanding of the hollow section and
a process for its manufacture of the present invention, reference
is made to the following detailed description and accompanying
drawings in which the presently preferred embodiments of the
invention are illustrated by way of example. That the invention may
be embodied in several forms without departing from the spirit or
essential characteristics thereof, it is expressly understood that
the drawings are for purposes of illustration and description only,
and are not intended as a definition of the limits of the
invention. Throughout the following description and drawings,
identical reference numbers refer to the same component throughout
the several views.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Further advantages, features and details of the invention
are revealed in the following description of preferred exemplified
embodiments and with the aid of the drawing which shows in:
[0021] FIG. 1: a perspective view of a single-chamber hollow
section of approximately rectangular cross-section;
[0022] FIG. 2: enlarged front elevation of the section shown in
FIG. 1;
[0023] FIG. 3: front elevation of a multi-chamber hollow section;
and
[0024] FIG. 4: cross-section through a further single-chamber
hollow section.
DETAILED DESCRIPTION OF THE INVENTION
[0025] In so-called high internal pressure forming (HIP) a hollow
section 10 made of an aluminum alloy and manufactured by extrusion
is expanded by means of pressure created in its hollow chamber 12.
This single-chamber hollow section 10 of approximately rectangular
cross-section of breadth b and height h features two transverse
walls 14 as base wall or end wall and side walls 16 connecting the
transverse walls 14. The section's straight outer faces 15, 17
delimit rounded section corners 30 which run parallel to the
longitudinal axis A of the section.
[0026] The inner faces 15.sub.i, 17.sub.i of the walls 14, 16--of
outer length b and h resp.--have, with respect to the neighboring
outer face 15, 17 a parallel middle part which delimits a wall
length 14.sub.m, 16.sub.m of constant thickness e, e.sub.i and
length a, c. Connecting up to the middle wall length 14.sub.m,
16.sub.m at each end is an end part 14.sub.e, 16.sub.e of uniformly
increasing thickness f, f.sub.1. Thereby, the wall thickness e,
e.sub.1, f, f.sub.1 are measured perpendicular to the wall middle
face E, E.sub.1 in question.
[0027] FIG. 3 shows a multi-chamber section 11 of breadth b and
height h with four chambers 12; connecting up with the inner faces
15.sub.i, 17.sub.i of transverse walls 14 and side walls 16--in
each case in the middle--are inner walls 26, 28, which cross in the
center Q of the hollow section and in cross-section form a central
crossing region 27. Both crossing beams of this symmetrical cross
form the inner walls of the four section chambers or spaces 12,
their outer limit being given by the outer walls 14, 16.
[0028] The outer walls formed by the transverse walls 14 and the
side walls 16 feature generally flat faces 15, 17 between the
corners 30 of the section. In this design each of the wall lengths
delimiting the section chambers 12 is, as described in FIG. 2, made
up of the middle parts 14.sub.m, 16.sub.m--here of length a.sub.1
or c.sub.1--and the end parts 14.sub.e, 1.sub.e. Likewise, the
inner section walls or inner walls 26, 28--corresponding to the
outer walls 14, 16 described above--are divided into section wall
middle lengths 26m, 28m of length n, n.sub.1 and constant thickness
g, g.sub.1, and end lengths 26.sub.e, 28.sub.e of increasing
thickness i, i1. For the latter a middle plane M, M1 forms a plane
of symmetry i.e. the end lengths 26.sub.e, 28.sub.e broaden out
conically until meeting up with the integral outer walls 14,
16.
[0029] The end lengths 26.sub.e, 28.sub.e of the inner section
walls 26, 28 close to the above mentioned center Q form the central
crossing or nodal region 27. The other end lengths 26.sub.e,
28.sub.e of the inner section walls 26, 28 represent outer nodal
regions 32, 34 at the intersection with the outer section walls 14,
16.
[0030] The hollow section 10.sub.a in FIG. 4 is likewise a single
chamber section and exhibits an upper transverse wall 18 or end
wall of constant thickness e.sub.2 of 3.+-.0.2 mm which lies
opposite--an outer distance q here of approx. 75 mm from--a
parallel base wall 14 of smaller constant thickness e.sub.3. Both
are integrally joined to a side wall 20 running perpendicular to
both walls 18, 14. The overall length h.sub.1 of this side wall 20,
which features an extension rib 19, is here approx. 95 mm. For
reasons of clarity a co-ordinate cross X, Y lying parallel to the
wall 18 and the side wall 20 is shown in the drawing.
[0031] The length t, approx. 51 mm, of the base wall 14 is slightly
smaller than the length t.sub.1, approx. 58 mm, of the wall 18,
with the result that the second side wall 22 of the hollow section
10a is inclined at an angle w of approx. 85.degree. to the plane of
the shorter base wall 14. The end length 22e of the sloping section
wall 22, which meets up with the wall 18 forms an upper section
corner 30, is of length g.sub.1=15 mm and thickness y=2.0.+-.0.2
mm. Joining up at the bottom end point 24 of the end of length
22.sub.e is an inner face 23.sub.i which is inclined to the outer
face 23 of side wall 22 and defines the thickness z=2.0.+-.0.2 mm
in the lower corner 30.sub.t of the section 10.sub.a.
[0032] The inner face 21.sub.i of the left wall 20 in the drawing
is as a whole, from its top region of thickness y.sub.1 neighboring
the wall 18 to its lower section corner 30.sub.t, inclined with
respect to the outer face 21 of this side wall 20. At the lower
end, the thickness z.sub.1 of the side wall 20 likewise measures
2.0.+-.0.2 mm.
[0033] The transition between the end length 22.sub.e of the side
wall 22 and the end wall 18 is likewise rounded as is the
transition between the end wall 18 and the other side wall 20.
[0034] The different cross-sectional shape of the left side wall 20
in FIG. 4 on the one hand and the right side wall 22 featuring the
end length 22.sub.e on the other hand is shown by way of example in
a hollow section 10.sub.a. It is, however, also possible to select
one or the other shape for both facing walls 20, 22 of a hollow
section.
[0035] Not shown is another shape of hollow section in which the
cross-sectional shape of the side wall 20 or 22 runs counterwise in
an extended part of the side wall, which again increases the
smaller thickness z continuously to a greater thick-ness y.sub.1.
In this design it is also possible to include a second end length
of constant thickness y.
[0036] Although the present invention has been described in
relation to particular embodiments thereof, many other variations
and modifications and other uses will become apparent to those
skilled in the art. It is preferred, therefore, that the present
invention be limited not by the specific disclosure herein, but
only by the appended claims.
* * * * *