U.S. patent application number 15/544874 was filed with the patent office on 2018-01-25 for method for forming a tubular body, undulating tubular body and use of same.
The applicant listed for this patent is WOBBEN PROPERTIES GMBH. Invention is credited to Gerrit KUIPER, Falk MIDDELSTADT, Jochen ROER, Sven WOLLGAM.
Application Number | 20180021830 15/544874 |
Document ID | / |
Family ID | 54705649 |
Filed Date | 2018-01-25 |
United States Patent
Application |
20180021830 |
Kind Code |
A1 |
ROER; Jochen ; et
al. |
January 25, 2018 |
METHOD FOR FORMING A TUBULAR BODY, UNDULATING TUBULAR BODY AND USE
OF SAME
Abstract
A method for forming a tubular body, comprising the following
steps: making available a tubular body having a first and a second
tube end, filling the tubular body with a liquid, closing the
tubular body, and forming the tubular body.
Inventors: |
ROER; Jochen; (Ganderkesee,
DE) ; KUIPER; Gerrit; (Aurich, DE) ; WOLLGAM;
Sven; (Jade, DE) ; MIDDELSTADT; Falk; (Berlin,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
WOBBEN PROPERTIES GMBH |
Aurich |
|
DE |
|
|
Family ID: |
54705649 |
Appl. No.: |
15/544874 |
Filed: |
November 30, 2015 |
PCT Filed: |
November 30, 2015 |
PCT NO: |
PCT/EP2015/078078 |
371 Date: |
July 19, 2017 |
Current U.S.
Class: |
72/57 |
Current CPC
Class: |
B21D 26/033 20130101;
B21D 9/15 20130101; B21D 41/04 20130101; B21D 11/07 20130101; B21D
26/041 20130101; B21D 22/025 20130101 |
International
Class: |
B21D 11/07 20060101
B21D011/07; B21D 26/041 20060101 B21D026/041; B21D 9/15 20060101
B21D009/15; B21D 26/033 20060101 B21D026/033 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 22, 2015 |
DE |
10 2015 201 008.2 |
Claims
1. A method for forming a tubular body, the method comprising:
filling a tubular body with a liquid, the tubular body having a
first end, a second tube end, and a cross-sectional shape; closing
the tubular body, and forming the tubular body, wherein forming the
tubular body includes changing the cross-sectional shape of at
least a portion of the tubular body.
2. The method according to claim 1, comprising pressurizing the
liquid in the tubular body before forming the tubular body.
3. The method according to claim 2, wherein the liquid is subjected
to a pressure of 20 bar or more.
4. The method according to claim 1, wherein forming comprises
introducing one or more bending radii into the tubular body.
5. The method according to claim 4, wherein the one or more bending
radii is less than three times a diameter of the tubular body.
6. (canceled)
7. The method according to claim 1, wherein changing the
cross-sectional shape includes placing the tubular body in a die
and forming the tubular body to match the die by applying force to
the tubular body.
8. The method according to claim 1 further comprises: bending the
tubular body into a meandering shape, wherein the meandering shape
has one or more substantially uncurved tube segments, each of the
one or more substantially uncurved tube segments adjoin one or more
of the bending radii.
9. The method according to claim 1, comprising: discharging the
liquid from the tubular body when the pressure exceeds a
predetermined value during forming.
10. The method according to claim 1, comprising monitoring the
liquid pressure during forming.
11. The method according to claim 1, wherein the tubular body is a
steel material.
12. A meandering tubular body produced by a method according to
claim 1, the meandering tubular body comprising: a plurality of
bending radii with a bending radius of less than three times the
tube diameter, and a plurality of substantially uncurved segments
that adjoin the bending radii, wherein at least one of the uncurved
segments has a substantially polygonal cross section.
13. The meandering tubular body according to claim 12 in a
generator, wherein the generator is configured to produce an
electric current in a multi-pole synchronous generator of a wind
power plant, wherein: the generator has a plurality of grooves, in
which a winding is arranged, the tubular body has a plurality of
substantially uncurved tube segments having a substantially
polygonal cross section, wherein the substantially uncurved
segments of the tubular body are arranged in the grooves, the
tubular body including a cooling liquid flowing through said
segments.
14. The meandering tubular body according to claim 12, wherein a
stator of the generator has the plurality of grooves and the
winding is a stator winding.
15. The method according to claim 1, wherein changing the
cross-sectional shape of at least the portion of the tubular body
includes changing the cross-sectional shape of at least the portion
of the tubular body to a substantially polygonal cross-sectional
shape.
16. The method according to claim 15, wherein the polygonal
cross-sectional shape is a substantially rectangular
cross-sectional shape.
17. The method according to claim 7, wherein applying force to the
tubular body includes using a punch or a roll.
18. The method according to claim 9 wherein discharging the liquid
from the tubular body comprises using a pressure relief valve, if
the pressure exceeds a predetermined value during forming.
Description
BACKGROUND
Technical Field
[0001] According to a first aspect, the present invention relates
to a method for forming a tubular body. According to another
aspect, the invention relates to a meandering tubular body produced
by such a method. According to another aspect, the invention
relates to the use of a tubular body of this kind.
Description of the Related Art
[0002] Forming tubular bodies is a widely known process. After
being produced, tubular bodies are generally in an elongate,
substantially uncurved form. However, since tubular bodies are not
used only along straight delivery sections in practice, the
installation locations may sometimes require fluids to be delivered
along curved paths, e.g., around corners, by means of tubular
bodies, and it is not always possible or desirable to use branch
lines, flanged-on pipe elbows and the like in these situations,
there is, on the one hand, the need to be able to bend tubular
bodies, by means of forming for instance. On the other hand, there
is a need to be able to form tubular bodies in respect of their
cross-sectional shape in order to be able to lay them through
predefined opening cross sections or to be able to shape the cross
section of the tubular bodies as closely as possible to
predetermined opening cross sections. The latter is significant
especially when using the tubular bodies as cooling elements in
order to be able to achieve the best possible heat transfer between
the tubular body and the body to be cooled.
[0003] One particular challenge when forming tubular bodies is to
prevent collapse or buckling of the tubular body or unwanted
deformation of the tubular body in some other way and to obtain
only the deformation which is intended in the forming process. To
achieve this, sand is used as a filler in the prior art. The sand
fills the internal cross section of the tubular body and prevents
collapse or unwanted indentation of the tubular body during
forming, given an adequate packing density.
[0004] Even if this method is feasible for simple forming
processes, such as the production of individual bending radii or
the production of non-circular cross sections of the tube, there is
the problem, in the case of more complex forming processes, such as
the production of meandering tubular bodies, that it may no longer
be possible to remove the sand completely from the tubular body
after the forming process. Consequently, it is not possible in the
prior art to produce complex tubular body shapes, such as
meandering tubular bodies, in one piece.
[0005] In the German patent application on which priority is based,
the German Patent and Trademark Office identified the following
documents: DE 694 02 051 T2, DE 196 16 484 A1, EP 0 099 714 A1, DE
199 52 508 A1 and DE 10 2010 018 162 B3.
BRIEF SUMMARY
[0006] Provided is a method for forming tubular bodies which allows
higher flexibility for complexity in forming.
[0007] A method has the following steps: making available a tubular
body having a first and a second tube end, filling the tubular body
with a liquid, preferably water, closing the tubular body, and
forming the tubular body. Water can be removed from the tubular
body without leaving residues after the forming of said body,
especially in the liquid or gaseous state, irrespective of the
complexity of the tubular body, as long as one end or preferably
both tube ends are opened again after forming. Moreover, liquids,
such as water or suitable oils, can be compressed only with
difficulty and therefore ensure adequate stabilization of the
internal tube volume, despite being in the liquid state, if the
tube is completely filled and closed.
[0008] In a particularly preferred development of the method, this
method furthermore comprises the following step: pressurizing the
liquid in the tubular body before the forming step. Through the
pressurization of the liquid, the liquid is as it were preloaded.
Physically speaking, liquids are not completely incompressible.
However, it has been found that sufficient incompressibility or
sufficiently low compressibility for the purposes of the method is
available when using water, and this can be even further improved
by subjecting the water to pressure before forming. Pressurization
as it were provides an indicator of the complete filling of the
tubular body. One particular advantage associated with
pressurization is the following: if a leak, e.g., in the form of a
crack, develops during the forming of the tubular body, the
pressurized liquid would immediately escape from the interior of
the tubular body. This escape would be easy to detect. Thus,
pressure checking can simultaneously be performed during forming.
If no liquid escapes until the forming process is complete, the
operator knows immediately that the tube is pressure tight at least
up to the pressure to which the tubular body has previously been
subjected from the inside. This represents a significant economic
advantage.
[0009] The liquid is preferably subjected to a pressure of 20 bar
or more, particularly preferably in a range of from 50 bar to 200
bar.
[0010] In a preferred embodiment of the method, the forming step
comprises introducing one or more bending radii into the tube. In
brief, the advantage of using liquid as an internal stabilizer is
all the more effective, the more complex is the geometry of the
tubular body and consequently the more bending radii are introduced
into the tube.
[0011] In another preferred embodiment, the bending radius or at
least one of the plurality of bending radii, preferably a plurality
of the bending radii or all of the bending radii, is/are less than
three times the tube diameter. Whereas, in the case of conventional
tube bending methods in the prior art, a minimum bending radius of
about five times down to a maximum of easily three times the tube
diameter is taken as a basis, the method allows significantly
greater bending owing to the use of liquid, in particular
pressurized liquid, as an internal stabilizer, and this results in
significantly tighter possible bending radii. In preferred
embodiments, the achievable bending radius is in a range of from
less than three times the tube diameter to about twice the tube
diameter, wherein, as before, the bending radius also depends, as
is known, on the material used for the tubular body and especially
on the wall thickness thereof. In the case of a tube with a
diameter of 12 mm, a wall thickness of 1 mm and stainless steel as
a material, the abovementioned bending radii can be achieved, for
example.
[0012] In another preferred embodiment of the method, the forming
step comprises: changing the tube cross section of one or more
segments of the tubular body or of the entire tubular body,
preferably to a substantially polygonal cross-sectional shape,
particularly preferably to a substantially rectangular shape. A
substantially polygonal or substantially rectangular shape is taken
to mean that the angularity of the cross section is within the
range of what is technically possible. If a tube cross section is
deformed in such a way by means of forming that it has one or more
edges which give the cross section a polygonal, in particular
rectangular, shape overall, it must be expected that a small edge
radius will remain on the inside and on the outside. This can be
ignored for purposes of understanding the concept of the
substantially polygonal or substantially rectangular
cross-sectional shape.
[0013] Changing the tubular cross section into a substantially
polygonal or substantially rectangular cross-sectional shape is
preferably achieved by placing a segment or segments of the tubular
body or the complete tubular body in a die and then forming it to
match the die by the application of force. Force is applied either
externally to the die or the tubular body and/or by means of the
die itself, which acts in the manner of a punch, for example. There
is a preference, for example, for deforming the tubular body by
means of a punch or a roll, by means of levelling rolls for
instance.
[0014] In another embodiment, the method is developed in that a
plurality of bending radii is introduced into the tubular body and
in that the forming step furthermore comprises: bending the tube
into a meandering shape, wherein the meandering shape has one or
more substantially uncurved tube segments, which each adjoin one or
more of the bending radii.
[0015] As another preferred option, the method comprises the
following step: discharging liquid from the tubular body,
preferably by means of a pressure relief valve, if the pressure
exceeds a predetermined value during forming. This is preferably
carried out by closing at least one of the ends of the tubular body
using an excess pressure limiter valve, which discharges liquid
whenever the pressure rises significantly, preferably by 1 to 10%
or more, owing to the progress of forming. The following is thereby
achieved: when changing the tube cross section by applying force
from the outside, the volume of the tubular body is sometimes
reduced. To ensure that the liquid medium escaping from that
segment of the tubular body which has just been deformed does not
cause bulging or unwanted deformation of the tubular body at some
other point, liquid is selectively discharged according to this
embodiment in order to keep the pressure in the tubular body
substantially constant. Depending on the design of the tubular
body, different limit values can be defined here. At a wall
thickness of 1 mm and with stainless steel as a material, a limit
value for the pressure limit of about 50 bar has proven
appropriate, for example.
[0016] In another preferred embodiment, said method furthermore
comprises the following step: monitoring the liquid pressure during
forming, preferably by means of a pressure sensor. Apart from the
fact that visual monitoring of the liquid pressure can, of course,
take place through observation of the pressure relief valve, there
can also be a preference for quantitative detection of the pressure
rise within the tubular body for the sake of more accurate control
of the forming process, and a widely known pressure measuring
transducer is preferably used for this purpose.
[0017] The method has proven itself especially also with tubular
bodies which are formed by a steel material, in particular
stainless steel or structural steel.
[0018] According to the second aspect of the invention, provided is
a tubular body which is suitable for cooling a generator, wherein
the generator is used for producing an electric current, in
particular in the form of a multi-pole synchronous generator of a
wind power plant.
[0019] The meandering tubular body has a plurality of bending
radii, preferably with a bending radius of less than three times
the tube diameter, and a plurality of substantially uncurved
segments, which adjoin the bending radii, preferably without kinks,
wherein at least one, preferably a plurality or all, of the
substantially uncurved segments has/have a substantially
rectangular cross section.
[0020] Where substantially uncurved segments of the tubular body
are referred to above and below, this is to be taken to mean that
the tubular body is designed to be free from curves, i.e.,
straight, in these segments or at least has so little curvature
that it can be introduced into the groove of the generator and
preferably rests there against the opposite walls of the groove in
order to allow heat transfer. If there is a slight curvature in the
direction of the depth of the groove, the curvature is
insignificant here. Even if there is a slight curvature
transversely to the depth of the groove, i.e., in a direction
toward the groove walls or away from them, a substantially uncurved
segment is assumed if the segment can be moved into the groove by
elastic deformation.
[0021] The tubular body preferably has a wall thickness in a range
between 0.5 and 3.5 mm, particularly preferably in a range of from
1-2 mm.
[0022] As another preferred option, the tubular body is formed by a
steel material, in particular stainless steel or structural steel.
Admittedly, there are materials which allow significantly greater
changes in shape owing to higher ductility, e.g., copper tubes.
However, the preference is to design the tubular body with the
minimum possible electrical conductivity, especially for use in a
generator for producing electric current. Fundamentally, the
tubular body in its meandering shape also acts like a coil and,
during the operation of the generator, when the pole shoes are
moved past the grooves provided with the meander, can cause power
losses or interference fields, it being possible to keep these low
by a suitable choice of material.
[0023] Thus, according to the third aspect, the invention relates
to the use of a meandering tubular body according to one of the
embodiments described above in a generator.
[0024] In particular, the invention achieves implementing the
cooling of the generator by means which are as economical as
possible and of allowing coolant to be carried as far as possible
without leakage.
[0025] Given the above considerations, the use of the meandering
tubular body according to one of the preferred embodiments
described above is particularly preferred because the tubular body
has (implicitly) already been checked for pressure-tightness during
the production thereof.
[0026] The meandering tubular body is particularly preferably used
in a generator which is designed as a multi-pole synchronous
generator of a wind power plant. The generator, particularly
preferably the stator of the generator, has a multiplicity of
grooves, in which a winding, which is preferably the stator
winding, is arranged. The plurality of substantially uncurved tube
segments of substantially rectangular cross section of the tubular
body is introduced into the grooves. When cooling liquid then flows
through the tubular body, the heat produced by the stator winding
can be dissipated directly from the groove and, at the same time,
the development of heat in the stator can be stemmed.
[0027] In the case of a synchronous ring generator of a gearless
wind power plant, the term "multi-pole" is taken to refer to a
multiplicity of stator poles, in particular a design having at
least 48 stator teeth, often even with significantly more stator
teeth, in particular 96 stator teeth or even more stator teeth. The
magnetically active region of the generator, namely both of the
rotor, which can also be referred to as an armature, and of the
stator is arranged in an annular region around the axis of rotation
of the synchronous generator. Thus, in particular, a range of from
0 to at least 50 percent of the radius of the air gap is free from
materials which carry the electric current or electric field of the
synchronous generator. In particular, this internal space is
completely free and, in principle, can also be accessed. This
region can often also make up more than 0 to 50 percent of the air
gap radius, in particular up to 0 to 70 percent or even 0 to 80
percent of the air gap radius. Depending on the construction, there
may be a supporting structure in this inner region, but this can be
of axially offset design in some embodiments. By virtue of their
functioning, such synchronous generators of a gearless wind power
plant are slowly rotating generators. Here, the term "slowly
rotating" is taken to mean a speed of less than 40 revolutions per
minute, in particular of about 4 to 35 revolutions per minute,
depending on the size of the plant.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0028] The invention is described in greater detail below by means
of preferred illustrative embodiments with reference to the
attached figures, of which:
[0029] FIG. 1 shows a first method state during the production of a
meandering tubular body,
[0030] FIG. 2 shows a second method state of the method according
to FIG. 1, and
[0031] FIG. 3 shows a third method state of the method according to
FIGS. 1 and 2.
DETAILED DESCRIPTION
[0032] In its undeformed state, the tubular body 1 shown in FIGS.
1-3 has a substantially cylindrical cross section and is uncurved,
as can be seen in FIG. 1. To prepare the forming step, the tubular
body 1 is closed pressure tightly in a first end segment 2 by means
of a closure 3, e.g., a blind plug. A second closure 5 is fitted in
an opposite, second end segment 4. The second closure 5 is designed
as a check valve with an excess pressure limiter, for example.
[0033] The tubular body 1 is filled with liquid, preferably via the
second closure 5, and pressurized, e.g., with a pressure in a range
of from 50 to 200 bar. The tubular body is then closed pressure
tightly by means of the optionally provided check valve, wherein
the optionally provided pressure limiter is designed to discharge
liquid from the interior of the tubular body 1 if a predetermined
pressure within the tubular body 1 is exceeded.
[0034] It is then possible to carry out the forming step with the
filled and closed and preferably pressurized tubular body 1. In the
illustrative embodiment shown, the tubular body 1 is first of all
placed in a tube bending device 100, as shown in FIG. 1. The tube
bending device 100 holds a first leg of the tubular body 1 against
a stop 101. A lever 103 brings about the bending of the tubular
body 1 around a retention pin 105 in the direction of the arrow A.
Owing to the filling of the tubular body 1 with the liquid, tube
bending takes place without the tube cross section collapsing, and
a state as shown in FIG. 2 is achieved when the bending process is
carried out several times.
[0035] The tubular body shown in FIG. 2, which is bent in a
meandering shape and represents an intermediate product of the
method of the illustrative embodiment shown, has a plurality of
substantially uncurved segments 7, which are each arranged
adjoining the bending radii 9 without kinks.
[0036] Starting from the state shown in FIG. 2, the tube cross
sections of the substantially uncurved segments 7 are then
preferably changed. This is accomplished as shown in FIG. 3 by
placing the substantially uncurved segments 7 successively in a die
203 of a punching device 200. The die 203 consists of two parallel
bars, for example, which between them define a gap of rectangular
cross section, e.g., in the form of a square with the slot width C
and preferably the same slot depth.
[0037] By moving a punch 201 repeatedly up and down in the
direction of the arrows B, the tubular body 1 is subjected to an
external force in the die 203, said force leading to deformation in
such a way that the tube cross section is shaped to match the cross
section of the slot.
[0038] A pressure-measuring transducer 11, which is designed to
monitor the internal pressure of the liquid, is preferably arranged
on the second closure 5. If a predetermined pressure value is
exceeded, there is the possibility either of discharging liquid
manually or of automatic opening of a pressure relief valve if said
pressure is exceeded in order to take account of the reduction in
volume in the interior of the tubular body 1 due to the change in
shape brought about by the punching device 200.
[0039] As can be seen from the above illustrative embodiment, the
method can be used for both the combined bending and the changing
of the shape of the tube cross section. However, the advantages of
stabilizing the volume of the tubular body 1 by means of,
preferably pressurized, liquid also come into play in both
individual processing steps, i.e., when only bending of the tube
cross section is taking place or only a change in the shape of the
tube cross section is taking place. It has been found that the use
of water allows adequate stabilization, and the environmental
compatibility of water is regarded as advantageous for the use
thereof.
[0040] As an alternative, the use of oil or the like is likewise
envisaged.
* * * * *