U.S. patent application number 11/101656 was filed with the patent office on 2005-10-13 for method for manufacturing a metal tubular blank, a tubular blank, and a product produced from said tubular blank.
This patent application is currently assigned to Corus Staal BV. Invention is credited to Kelder, Maarten Hendrik, Klaassen, Maria Gemma Othilde.
Application Number | 20050223768 11/101656 |
Document ID | / |
Family ID | 34928139 |
Filed Date | 2005-10-13 |
United States Patent
Application |
20050223768 |
Kind Code |
A1 |
Kelder, Maarten Hendrik ; et
al. |
October 13, 2005 |
Method for manufacturing a metal tubular blank, a tubular blank,
and a product produced from said tubular blank
Abstract
Disclosed is a method for manufacturing a metal tubular blank
suitable for forming into a product comprising the steps of:
providing an essentially planar blank, said planar blank having a
first surface and a second surface; and producing the tubular blank
from the planar blank whereby the second surface of the planar
blank becomes the outside of the tubular blank; wherein a first
layer with a first friction influencing function is applied to at
least part of the first side of the planar blank and/or a second
layer with a second friction influencing function is applied to at
least part of the second side of the planar blank prior to forming
the planar blank into a tubular blank, so as to influence the
friction between the tubular blank and forming tools which can be
used to form the tubular blank into the product, and wherein the
first and/or second layer are applied in the form of a foil, a dry
lubricant, a wax or an oil. Also disclosed is a tubular blank and a
product produced from such a tubular blank.
Inventors: |
Kelder, Maarten Hendrik;
(Amsterdam, NL) ; Klaassen, Maria Gemma Othilde;
(Purmerend, NL) |
Correspondence
Address: |
STEVENS DAVIS MILLER & MOSHER, LLP
1615 L STREET, NW
SUITE 850
WASHINGTON
DC
20036
US
|
Assignee: |
Corus Staal BV
Ijmuiden
NL
|
Family ID: |
34928139 |
Appl. No.: |
11/101656 |
Filed: |
April 8, 2005 |
Current U.S.
Class: |
72/46 |
Current CPC
Class: |
B21C 37/06 20130101 |
Class at
Publication: |
072/046 |
International
Class: |
B21C 037/06 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 9, 2004 |
EP |
04076086.0 |
Claims
1. A method for manufacturing a metal tubular blank suitable for
forming into a product comprising the steps of: providing an
essentially planar blank, said planar blank having a first surface
and a second surface; producing the tubular blank from the planar
blank whereby the second surface of the planar blank becomes the
outside of the tubular blank; wherein a first layer with a first
friction influencing function is applied to at least part of the
first side of the planar blank and/or a second layer with a second
friction influencing function is applied to at least part of the
second side of the planar blank prior to forming the planar blank
into a tubular blank, so as to influence the friction between the
tubular blank and forming tools which can be used to form the
tubular blank into the product, and wherein the first and/or second
layer are applied in the form of a foil, a dry lubricant, a wax or
an oil.
2. Method according to claim 1, wherein the blank is produced from
a coil and wherein the first and/or second layer is applied to the
coil prior to producing the blank.
3. Method according to claim 1, wherein the foil is a hydrocarbon
or a fluorocarbon.
4. Method according to claim 1, wherein the foil is a polyethylene
or a polytetrafluorethylene.
5. Method according to claim 1, wherein the planar blank is
essentially quadrangular.
6. Method according to claim 1, wherein the planar blank has an
essentially quadrangular shape selected from the group consisting
of essentially rectangular and essentially tapered.
7. Method according to claim 1, wherein the planar blank comprises
at least a first blank portion and a second blank portion and
wherein the first blank portion has different geometrical
dimensions than the second blank portion and/or wherein the first
blank portion is made from a different material than the second
blank portion and/or wherein the material of the first blank
portion has different properties than the material of the second
blank portion.
8. Method according to claim 2, wherein the planar blank comprises
at least a first blank portion and a second blank portion and
wherein the first blank portion has different geometrical
dimensions than the second blank portion and/or wherein the first
blank portion is made from a different material than the second
blank portion and/or wherein the material of the first blank
portion has different properties than the material of the second
blank portion.
9. Method according to claim 3, wherein the planar blank comprises
at least a first blank portion and a second blank portion and
wherein the first blank portion has different geometrical
dimensions than the second blank portion and/or wherein the first
blank portion is made from a different material than the second
blank portion and/or wherein the material of the first blank
portion has different properties than the material of the second
blank portion.
10. Method according to claim 4, wherein the planar blank comprises
at least a first blank portion and a second blank portion and
wherein the first blank portion has different geometrical
dimensions than the second blank portion and/or wherein the first
blank portion is made from a different material than the second
blank portion and/or wherein the material of the first blank
portion has different properties than the material of the second
blank portion.
11. Method according to claim 5, wherein the planar blank comprises
at least a first blank portion and a second blank portion and
wherein the first blank portion has different geometrical
dimensions than the second blank portion and/or wherein the first
blank portion is made from a different material than the second
blank portion and/or wherein the material of the first blank
portion has different properties than the material of the second
blank portion.
12. Method according to claim 1, wherein at least one of the layers
with a friction influencing function decreases the friction between
the tubular blank and the forming tools which can be used to form
the tubular blank into a product.
13. Method according to claim 2, wherein at least one of the layers
with a friction influencing function decreases the friction between
the tubular blank and the forming tools which can be used to form
the tubular blank into a product.
14. Method according to claim 3, wherein at least one of the layers
with a friction influencing function decreases the friction between
the tubular blank and the forming tools which can be used to form
the tubular blank into a product.
15. Method according to claim 4, wherein at least one of the layers
with a friction influencing function decreases the friction between
the tubular blank and the forming tools which can be used to form
the tubular blank into a product.
16. Method according to claim 5, wherein at least one of the layers
with a friction influencing function decreases the friction between
the tubular blank and the forming tools which can be used to form
the tubular blank into a product.
17. Method according to claim 6, wherein at least one of the layers
with a friction influencing function decreases the friction between
the tubular blank and the forming tools which can be used to form
the tubular blank into a product.
18. Method according to claim 12, wherein at least the second layer
with a friction influencing factor decreases the friction between
the tubular blank and the forming tools which can be used to form
the tubular blank into a product.
19. Tubular blank obtained using the method in accordance with
claim 1.
20. Product obtained by hydroforming a tubular blank according to
claim 10.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This claims priority from European patent application EP
04076086.0, filed 9 Apr. 2004, incorporated herein by reference in
its entirety.
FIELD OF THE INVENTION
[0002] The invention relates to a method for manufacturing a metal
tubular blank suitable for forming into a product. The invention
further relates to a tubular blank and a product produced from such
a tubular blank.
BACKGROUND OF THE INVENTION
[0003] In the industry, and in particular in the automotive sector,
forming is an important tool in manufacturing complex shapes with
as main materials steel and aluminium. Suppliers are urged to
improve the formability of their materials and to integrate their
processes because of, amongst others, costs and environmental
aspects. A part of this objective can be achieved using a relative
novel forming technology such as hydroforming. A tubular blank is
usually produced from a planar blank, which is cut from a metal
sheet. This planar blank is formed into a tube which is then laser
welded to form the tubular blank. In a typical hydroforming
operation a tube, or a tubular blank, is bent into the overall
shape desired for the final part, and then placed between a pair of
dies. The dies provide a cavity around the tube or tubular blank
which has an interior shape matching the exterior shape desired for
the part. Then, the ends of the tube or tubular blank are sealed
and it is internally pressurised to expand it into the shape of the
dies' cavity. By means of hydroforming different forming steps can
be integrated and much more complex shapes can be formed which in
turn saves costs and efforts compared with conventionally made
products. In order to obtain complex shapes, means to influence the
friction between the tube or tubular blank and the forming tools
are often used. These means may for instance comprise in-line
lubrication stations in the hydroforming line. Friction influencing
means may also be applied manually. These types of friction
influencing means are complicated and/or expensive.
SUMMARY OF THE INVENTION
[0004] It is an object of the invention to influence the friction
during forming which is economically attractive. It is also an
object of the invention to reproducibly influence the friction
during forming.
[0005] According to a first aspect of the invention, one or more of
the objects are reached by a method for manufacturing a metal
tubular blank suitable for forming into a product comprising the
steps of
[0006] providing an essentially planar blank, said planar blank
having a first surface and a second surface;
[0007] producing the tubular blank from the planar blank whereby
the second surface of the planar blank becomes the outside of the
tubular blank;
[0008] wherein a first layer with a first friction influencing
function is applied to at least part of the first side of the
planar blank and/or a second layer with a second friction
influencing function is applied to at least part of the second side
of the planar blank prior to forming the planar blank into a
tubular blank, so as to influence the friction between the tubular
blank and forming tools which can be used to form the tubular blank
into the product, and wherein the first and/or second layer are
applied in the form of a foil, a dry lubricant, a wax or an
oil.
[0009] By the method according to the invention, the tubular blank
is already provided with a layer with a friction influencing
function prior to entering the forming line. Consequently there is
no need to apply means with a friction influencing function, such
as a lubricant, in the forming line, making in-line stations or
manual application of means with a friction influencing function
obsolete. The method according to the invention also enables to
apply the means with a friction influencing function in a
controlled manner thereby making the application of the means more
reproducible, and thereby also making the behaviour of the tubular
blank during forming more reproducible. This increases the
stability and reproducibility of the forming process and results in
a more reproducible formed product. Application of the layers with
the friction influencing function to the planar blank is relatively
straightforward and easily controlled, leading to an improved
efficiency and quality of the friction behaviour of the tubular
blank during forming. By applying the first and/or second layer
with a friction influencing function in the form of a foil, a dry
lubricant, a wax or an oil, a very controlled and reproducible
application is obtained.
[0010] In an embodiment of the invention the planar blank is
produced from a coil and the first and/or second layer with a
friction influencing function is applied to the coil prior to
producing the planar blank. The first and/or second layer with a
friction influencing function may have been applied to the coil
immediately prior to forming of the planar blank, i.e. between
decoiling and blanking, but it may also have been applied prior to
coiling of the coil. The advantage of this embodiment is that the
first and/or second layer with a friction influencing function is
applied to a large surface, thereby facilitating quality control
and reproducible application of the layer or layers. This
embodiment also enables to produce planar blanks and hence tubular
blanks at a lower cost.
[0011] In an embodiment of the invention the foil is a hydrocarbon
such as a polymer, for example polyethylene or a fluorocarbon such
as polytetrafluorethylene. This type of layer with a friction
influencing function functions as a lubricant. The foil enables
easy application to the coil or the planar blank, for instance by
known methods such as laminating or co-extrusion of the foil,
whereas it provides excellent adhesion to the planar blank prior to
or during forming of the tubular blank and also during storage,
handling and forming of the tubular blank.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The sole FIGURE shows a tube 10 made according to the
present invention from a planar quadrilateral blank.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0013] In an embodiment of the invention the blank is essentially
quadrangular, such as essentially a parallelogram, essentially
rectangular or essentially tapered, for example, substantially
trapezoidal shaped or substantially trapezium shaped. This type of
lubricated blank will result in an essentially cylindrical tubular
blank or an essentially conical tubular blank. The latter
facilitates forming sloping shapes in the formed product. In this
specification the terms "essentially" and "substantially" are
interchangeable. For example, "essentially rectangular" encompasses
a perfect rectangle and a shape which is approximately a
rectangle.
[0014] In a further embodiment of the invention the planar blank
comprises at least a first blank portion and a second blank portion
and wherein the first blank portion has different geometrical
dimensions than the second blank portion and/or wherein the first
blank portion is made from a different material than the second
blank portion and/or wherein the material of the first blank
portion has different properties than the material of the second
blank portion. After producing a tubular blank from this planar
blank, this tubular blank enables combining portions having
different characteristics in terms of response to the forming
and/or the properties of the formed product. It will be clear that
the invention also encompasses tubular blanks made from planar
blanks having more than two blank portions, which blank portions
may all have different characteristics. In principle, there is no
limit to the number of blank portions in a planar blank for a
tailored tubular blank. The planar blanks comprising a plurality of
blank portions, i.e. at least two, can be produced by joining
together a corresponding number of planar blank portions, each
produced from metal sheet, by means of a joining technique such as
welding for example laser-welding.
[0015] This embodiment enables to choose the geometry, for instance
the thickness of the blank portion, or the type of material, or the
properties of the material, independently of the geometry, the type
of material, or the properties of the material of the second blank
portion. As an example, the strength of the first blank portion may
be chosen differently from that of the second blank portion because
of local strength requirements in the final formed product. Also,
it may be desired to use material for the first blank portion
having different resistance to corrosion than the material of the
second blank portion because of local requirements for corrosion
resistance in the final formed product. Again it will be clear that
the invention also encompasses tubular blanks made from planar
blanks having more than two blank portions, which blank portions
may all have different characteristics.
[0016] In an embodiment of the invention, the aim of at least one
of the layers with a friction influencing function is to decrease
the friction between the tubular blank and the forming tools which
can be used to form the tubular blank into a product. Decreasing
the friction facilitates forming the tubular blank into a product.
It may also reduce the forces required to form the tubular blank
into a product during the forming process. In a preferred
embodiment of the invention at least the function of the second
layer with a friction influencing factor is to decrease the
friction between the tubular blank and the forming tools which can
be used to form the tubular blank into a product. The second layer,
being on the outer surface of the tubular blank, is likely to
benefit from a reduced friction in terms of reducing the process
forces during forming, but also in terms of a reduced wear of the
outer surface and the forming tools.
[0017] In an embodiment of the invention the tubular blank,
manufactured as described hereinabove, is formed into a product at
least partly by hydroforming. The tailored friction on the inside
and/or the outside provides a hydroformed product with the required
surface, dimensions and properties.
[0018] According to a second aspect of the invention, a tubular
blank is provided which is obtained using the method in accordance
with any one of the methods described hereinabove. The sole FIGURE
shows a tubular blank 10 made according to the present invention
from a planar blank having a seam which is typically welded.
[0019] According to a third aspect of the invention, a product is
provided obtained by hydroforming a tubular blank which tubular
blank is obtained using any one of the methods described
hereinabove.
[0020] Specific embodiments of the present invention will now be
explained by the following non-limitative prophetic examples.
[0021] In the forming process of a bent tube, a tubular blank may
be produced from a planar blank produced from a metal sheet such as
a steel with a thickness of about 1.3 mm, which is provided with a
first layer with a first friction influencing function on the first
side of the planar blank and a second layer with a second friction
influencing function is applied to the second side of the planar
blank prior to forming the planar blank into a tubular blank. The
friction influencing function is chosen so as to reduce the
friction on the second surface (i.e. the outside of the tubular
blank) and to increase the friction on the first surface (i.e. the
inside of the tubular blank), so as to influence the friction
between the tubular blank and forming tools which can be used to
form the tubular blank into the product. When inserting a bending
rod into the tubular blank, the increased friction on the inside of
the tubular blank provides a firm grip of the bending rod to the
tubular blank, whereas the reduced friction on the outside of the
tubular blank provides a smooth surface. It should be noted that
there are also instances where bending requires low friction on the
inside of the tube. High friction levels on the outside may be
beneficial for obtaining more grip during bending. It will be clear
that the nature of the friction influencing layer may be chosen so
as to obtain the required friction properties during processing of
the tubular blank.
[0022] In the forming process of a hydroformed product, a tubular
blank may be produced from a planar blank, which is provided with a
layer with a friction influencing function on the second side of
the planar blank prior to forming the planar blank into a tubular
blank. The friction influencing function is chosen so as to reduce
the friction on the second surface (i.e. the outside of the tubular
blank) so as to influence the friction between the tubular blank
and the hydroforming tools used to form the tubular blank into the
hydroformed product. The reduced friction on the outside of the
tubular blank provides a smooth surface whilst also limiting the
process forces.
[0023] In the forming process of a hydroformed product, a tubular
blank may be produced from a planar blank, wherein the planar blank
has a plurality of blank portions. In a specific example, a planar
blank may comprise three blank portions, such as a first blank
portion of 2 mm aluminium with a proof stress of 150 MPa, a second
blank portion comprising a 1 mm high strength low alloy steel with
a tensile strength of above 600 MPa and a third blank portion
comprising an 1.5 mm austenitic stainless steel with excellent
corrosion resistance. The tubular blank, and the final product
which is made from it, is provided with a layer of friction
influencing function which is applied to the second surface of the
planar blank comprising a plurality of blank portions, and which
function is chosen so as to reduce the friction. When forming the
tubular blank into a product by hydroforming, the choice of the
layer with the friction influencing function, enables perfect
process control and yields a product with the required surface
properties, dimensions and properties.
[0024] It will be clear to the skilled person that the number and
characteristics of the blank portions is to be tailored to the
needs of the final product and the forming process.
[0025] In the forming process of a hydroformed product, a tubular
blank may be produced from a planar blank, which is provided on its
second surface with a first layer with a first friction influencing
function on part of the first side and with another layer with a
another friction influencing function on at least part of the
second surface wherein the two layers each with their respective
friction influencing function may at least partly overlap. This way
a combination of friction influencing functions may be obtained on
the same surface, thereby further extending the possibilities for
improvement of process control and quality of the hydroformed
product as to the required surface properties, dimensions and
properties.
[0026] It will be clear that similar or different combination of
friction influencing functions may be obtained on the first surface
as well. It is even possible to obtain similar or different
combination of friction influencing functions on both surfaces of
the tubular blank. This combination of friction influencing
functions on the same surface may also be combined with tubular
blanks made from planar blanks comprising a plurality, for instance
two, or three or four, or even more, blank portions. It may be
beneficial to choose a friction influencing function of a layer
depending on the properties or material of the respective blank
portion. It should be noted that it is also part of the invention
to provide one or more layers with a friction influencing function
on the first side or the second side of the planar blank only. This
enables a reduction in the use of the layer with a friction
influencing function such as a lubricant, thereby also reducing
costs.
[0027] It should be noted that the layer or layers with the
friction influencing function can be used to increase the friction
in certain areas of the tubular blank, thus enabling a controlled
material flow, which could be beneficial to reduce or increase
strain levels in certain areas of the product.
[0028] It is of course to be understood that the present invention
is not limited to the described embodiments and examples described
above, but encompasses any and all embodiments within the scope of
the description and the following claims.
* * * * *