METHOD AND MACHINE FOR MAKING A FINNED BODY

Europäisches Patentamt
(19)
European Patent Office
*EP000938391B1*
Office européen des brevets
(11)
EP 0 938 391 B1
EUROPEAN PATENT SPECIFICATION
(12)
(45) Date of publication and mention
of the grant of the patent:
28.08.2002 Bulletin 2002/35
(21) Application number: 97913616.5
(22) Date of filing: 12.11.1997
(51) Int Cl.7:
B21D 15/06
// B21D53/06
(86) International application number:
PCT/SE97/01898
(87) International publication number:
WO 98/020990 (22.05.1998 Gazette 1998/20)
(54) METHOD AND MACHINE FOR MAKING A FINNED BODY
VERFAHREN UND VORRICHTUNG ZUR HERSTELLEN EINER RIPPENKÖRPER
PROCEDE ET MACHINE SERVANT A FABRIQUER UN CORPS PRESENTANT DE FINES ARETES
(84) Designated Contracting States:
DE ES FR GB IT SE
(30) Priority: 12.11.1996 SE 9604122
(43) Date of publication of application:
01.09.1999 Bulletin 1999/35
(73) Proprietor: Interproperty N.V.
1640 Saint-Genesius-Rode (BE)
• ÖHMAN, Richard
S-141 44 Huddinge (SE)
(74) Representative: Nyberg, Bengt et al
c/o Roels, Wauters & Co. S.P.R.L.,
Place Guy d’Arezzo, 17/8
1180 Bruxelles (BE)
(56) References cited:
CH-A- 274 921
DE-B- 1 265 696
(72) Inventors:
EP 0 938 391 B1
• GILLBRAND, Per
S-647 00 Mariefred (SE)
Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give
notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in
a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art.
99(1) European Patent Convention).
Printed by Jouve, 75001 PARIS (FR)
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EP 0 938 391 B1
Description
[0001] This invention relates to making a finned body
of a high-ductility material.
[0002] More particularly, the invention relates to a
method of making a finned body having a multiplicity of
thin, closely spaced fins, such as a finned body having
a fin density of at least one fin per millimetre, e.g. 1,5 or
more fins per millimetre, and a fin height to thickness
ratio of at least 5.
[0003] The invention also relates to a machine for
making a finned body of this kind.
[0004] Such finned bodies find use in heat transfer
structures, such as heat exchangers of the kind in which
heat is transferred through the fins between a liquid or
gaseous first fluid flowing in the passages defined and
separated by the fins and a second fluid flowing through
other passages in the finned body. The finned body often is generally cylindrical with the fins extending radially
outwardly generally transversely to the axis of the body
and may be made of aluminium or other light metal material of high heat conductivity.
[0005] In a known class of heat exchangers of this
kind (see, for example, WO86/0039 or U.S. Patent No.
4,923,003) the fins and the intervening gaps are dimensioned and designed such that the fluid flows in laminar
fashion in the gaps or passages defined between the
fins. In these heat exchangers the fins are very thin and
very closely spaced: the fins may have a thickness of a
few tenths of a millimetre, e.g. about 0.2 mm, and may
be separated by a gap of approximately the same width,
e.g. about 0.2 or 0.3 mm, and the height of the fins may
be greater by one order of magnitude, e.g. about 3 mm.
[0006] As is readily appreciated, the forming of the
fins on such heat exchanger bodies presents special
problems, particularly where the finned body is made of
a soft material, such as aluminium or some other light
metal. For example, machining of such materials is often
troublesome, because the material tends to stick to the
machining tool and possesses poor chip breaking properties and because the surface finish tends to be poor.
Moreover, because of the small fin thickness the fins
easily deform or rupture under the influence of the forces
to which they are subjected in the fin forming operation
[0007] A method and apparatus according to the precharacterising parts of the independent claims are
known from DE-B-1265696.
[0008] A primary object of the invention is to provide
a method and a machine for making a finned body of
the kind indicated above.
[0009] In accordance with the invention, a method of
making a finned body from a blank of a high-ductility material comprises the steps defined in claim 1.
[0010] In the case of a tubular blank the outer surface
of which is a surface of revolution, the method preferably
includes mounting the blank for rotation about an axis
contained in a plane which also contains the axis of rotation of the forming tool. The cyclical movement of the
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forming tool then is a unidirectional rotational movement
in which the forming discs progressively penetrate into
the outer surface layer of the body and cause the material in that layer to flow outwardly in the gaps between
adjacent forming discs.
[0011] Using the method according to the invention it
is possible in an economical manner to make finned
bodies in which the fin dimensions and the fin density
are as indicated above.
[0012] Preferably, a lubricating fluid is supplied to the
points or areas where the forming discs engage the
blank.
[0013] In order that the working of the blank may be
smooth even if the force acting between the blank and
the forming tool vary during the cyclical relative movements, e.g. as a consequence of discontinuities in the
blank surface being worked, it is preferred to provide for
a positive control of the transverse displacement of the
forming tool relative to the blank so that the rate of displacement is not affected by variations in the resistance
to the penetration of the blank by the forming discs. Such
positive control can be accomplished by using a hydraulic actuator device to displace the forming tool and controlling the displacement through controlled bleeding of
hydraulic fluid from the actuator device.
[0014] According to the invention, a machine for making a finned body from a blank of a high-ductility material, comprises the combination of features defined in
claim 12.
[0015] The invention will be fully understood from the
following detailed description with reference to the accompanying drawings.
Fig. 1 is a side view of an exemplary finned body
which can be made using the method and the machine according to the invention;
Fig. 1A is an enlarged representation of the area
marked by a circle 1A in Fig. 1;
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Fig. 2 is an end view of the finned body shown in
Fig. 1;
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Fig. 3 is a cross-sectional view of a blank from which
the finned body shown in Figs. 1 and 2 is made;
Fig. 4 is a diagrammatical view, partly in section, of
the method and the machine used for making the
finned body;
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Fig. 5 is a diagrammatical view showing the transverse displacement of the forming tool.
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2
[0016] The finned body shown in Figs. 1 and 2 is a
tubular, generally cylindrical heat exchanger body 12 of
circular cross-section. In an actual exemplary embodiment, the body is made of substantially pure aluminium
(e.g. of the grade carrying the U.S. standard designation
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EP 0 938 391 B1
AA 1050) but as will be appreciated it can also be made
of other suitable high-ductility and thus easily deformable materials.
[0017] A central axial passage 13 defines a flow path
extending through the heat exchanger body to pass a
first fluid, such as cooling water. The outer circumferential surface of the heat exchanger body 12 is provided
with a very large number of thin, closely spaced planar
fins 14 disposed in parallel planes which are perpendicular to the axis C of the heat exchanger body.
[0018] In the illustrated exemplary embodiment the
fins 14 are discontinuous. They accordingly do not extend continuously throughout the circumference of the
heat exchanger body. Instead, as shown in Fig. 2, each
of the said planes contains twelve fin sections separated
circumferentially from one another by small gaps 15
forming twelve axially extending fluid passages. These
gaps 15 and the axial passages they form have a technical function which is explained in WO86/00395. Two
of the axial passages formed by the gaps 15 are wider
than the other passages and also serve to form diametrically opposite distribution and collection passages for
a second fluid, e.g. oil to be cooled.
[0019] In operation, the heat exchanger body 12 is enclosed in a housing (not shown) such that direct fluid
communication between the central axial passage 13
and the space between the housing and the outer side
of the heat exchanger body is prevented. Together with
the housing the narrow gaps 16 between adjacent fins
14 define a flow path for the second fluid.
[0020] In Figs. 1A and 3 the size and spacing of the
fins 14, notably the fin thickness and the width of the
gaps 16 separating adjacent fins, are heavily exaggerated; in the aforesaid exemplary embodiment these dimensions actually are only a few tenths of a millimetre.
[0021] Referring to Figs. 3 to 5, the fabrication of the
heat exchanger body 12 shown in Figs. 1 and 2 and the
machine used therefor will now be described.
[0022] Fabrication starts from a blank 12' in the form
of a length of an extruded rod having the cross-sectional
shape shown in Fig. 3. The blank 12' exhibits the central
axial passage 13; this passage remains more or less
unaffected by the forming of the fins. Moreover, the
blank 12' exhibits straight axial grooves 15' corresponding to the gaps 15 of the finished heat exchanger body.
The outer diameter of the blank is slightly smaller than
the outer diameter of the finished heat exchanger body
as measured across the fins 14 thereof.
[0023] The blank 12' is first journalled to rotate, preferably freely, about its axis C in a blank holding device
diagrammatically indicated at 17 in Fig. 5. The structure
for journalling the blank is constructed such that it is capable of absorbing the forces acting transversely on the
blank without allowing transverse displacement of the
axis C of the blank, i.e. the axis of rotation of the blank.
Suitably, the blank is mounted on a mandrel N (indicated
in Fig. 4) which is rotatable about a stationary axis, not
shown, and fits snugly in the central axial passage 13
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of the blank.
[0024] The fins 14 are formed in a machine which
comprises a generally cylindrical forming tool, designated by 18 in Figs. 4 and 5. This tool is arranged to be
rotated unidirectionally by a motor M about a tool axis L
which is parallel to the axis C of the blank mounted on
the mandrel N. By means of a device which is not shown
in detail, the forming tool 18 can be displaced transversely toward and away from the blank 12' while maintaining the parallel disposition of the axes C and L and
without changing its axial position relative to the blank.
In Fig. 5 this transverse displacement of the forming tool
18 is indicated by pairs of double arrows D pointing away
from the tool axis L.
[0025] The forming tool 18 comprises a shaft 20 and
a set of flat circular forming discs 19 centered on the tool
axis L and disposed in planes which are perpendicular
to the tool axis. The forming discs 19 are spaced apart
axially by fixed distances such that adjacent discs define
between them a gap the width of which corresponds to
the thickness of the fins to be formed on the blank 12'.
All forming discs 19 are of the same diameter and their
thickness corresponds to the width of the gaps 16 between adjacent fins 14 on the finished heat exchanger
body 12. Their peripheral edges are rounded or slightly
chamfered.
[0026] The number of forming discs 19 of the set is
related to the number of fins 14 to be formed simultaneously on the blank 12' such that the number of gaps defined by adjacent forming discs corresponds to the
number of fins to be formed.
[0027] After the blank 12' has been mounted in the
machine as described above, the forming tool 18 is rotated and displaced toward the blank so that all forming
discs 19 will engage the circumferential surface of the
blank 12' simultaneously. The friction occurring upon engagement of the peripheral edge of the forming discs 19
with the circumferential surface of the blank 12' will
cause the blank to rotate. As the continued slow displacement of the forming tool 18 progresses continuously toward the axis C of the blank, the peripheral portion of each forming disc 19 will penetrate into the circumferential surface region of the blank 12' and force
the blank material in that region to flow first laterally a
small distance and then radially outwardly in the gaps
between the adjacent forming discs as shown in Fig. 4.
[0028] As the penetration of the blank 12' by the forming discs 19 progresses during the unidirectional continuous rotation of the forming tool and the blank, each
forming disc 19 forming its own groove in the blank, the
height of the fins 14 increases. Since in the illustrated
example the width of the gaps between adjacent forming
discs 19 is smaller than the forming disc thickness, the
height of the fins 14 will increase more rapidly than the
penetration depth. With the exemplary dimensions of
the gap width and the disc thickness given above, the
height of the fins 14 will be approximately 2.5 times the
depth of penetration, that is, the distance through which
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EP 0 938 391 B1
the forming tool 18 is displaced toward the axis C while
in engagement with the blank.
[0029] When the blank 12' and the forming tool 18 are
in engagement with one another and rotate, a lubricating
fluid should be supplied to the areas of engagement of
the forming discs 19 to reduce the friction, thereby to
reduce the danger of tearing the fins being formed.
Means for supplying the lubricating fluid is indicated at
21 in Fig. 5.
[0030] The speed at which the forming tool 18 is displaced when in engagement with the blank 12' must be
adapted to the material of the blank, the thickness of the
fins 14 to be formed and that of the forming discs 19 and
also to the peripheral speeds of the forming tool and the
blank. A certain trial and error adjustment of the speed
of displacement may be required. Generally, however,
the displacement must be slow; a displacement speed
of 0.5 to 1 mm/minute has been found to be suitable for
materials like pure aluminium at peripheral speeds of
100 to 300 m/minute.
[0031] Whenever the forming tool 18 is in engagement with the blank 12', the transverse displacement of
the tool should be effected smoothly so that sudden variations of the force with which the forming discs 19 press
against the blank will be minimized. Using a blank of the
design illustrated and described above, the discontinuities formed by the axial grooves 15' make a complete
elimination of such variations very difficult or impossible.
[0032] However, in accordance with a preferred feature of the invention the variations can be kept within
acceptable limits by positively controlling the speed of
displacement such that it will not be affected by any occurring variations in the aforementioned force.
[0033] Such positive control can suitably be effected
in the manner diagrammatically illustrated in Fig. 5.
[0034] In Fig. 5 a pair of hydraulic cylinders of a first
hydraulic actuator are represented by two parallel arrows 22 and act in the direction of the blank axis C in
the plane containing that axis and the tool axis L. The
first hydraulic actuator operates to apply a force FA tending to displace the forming tool 18 toward the stationary
blank axis C while maintaining the parallel orientation of
the tool axis L relative to the blank axis.
[0035] This displacement is counteracted by a second
hydraulic actuator which is similarly represented by two
parallel arrows 23 which are aligned with the arrows 22
but directed oppositely. Naturally, the parallel displacement of the forming tool is also opposed by the force,
represented by arrows FC, which acts between the blank
12' and the forming discs 19 of the forming tool in the
plane containing the axes C and L. When the opposing
forces are balanced, FA is equal to the sum of FB and FC.
[0036] The speed at which the first hydraulic actuator
can displace the forming tool 18 toward the axis C of the
blank 12' is determined by the rate at which hydraulic
liquid is allowed to bleed from a cylinder compartment
of the second actuator. This rate in turn is determined
by a restrictor device (not shown) of constant-flow type,
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that is a restrictor device which passes a hydraulic fluid
flow the volumetric flow rate of which is always substantially constant and thus substantially independent of the
pressure drop across it.
[0037] Accordingly, the speed of displacement of the
forming tool 18 is substantially independent of any variations of the force FA.
[0038] Preferably, the arrangement is such that the
force FA is many times, e.g. 10 to 15 times, the force FC
so that the difference between the forces FA and FB is
only a small fraction of each of these forces.
Claims
15
1.
providing a fin-forming tool (18) having an axis
of rotation (L) and comprising a set of flat circular spaced-apart forming discs (19) centered on
and disposed side by side at fixed intervals
along said axis of rotation (L) and in planes perpendicular thereto,
rotating the forming tool (18) at a peripheral
speed of 100 to 300 m/minute while causing it
to perform cyclical movements over a surface
of the blank (12') characterised by said planes
being maintained in a constant orientation and
position relative to the blank, and
relatively displacing the forming tool (18) and
the blank (12') at a rate of 0.5 to 1 mm/minute
at right angles to the axis (L) of rotation of the
forming tool (18) to cause the peripheral portions of the forming disks (19) during said cyclical movements of the forming tool (18) progressively to penetrate into the blank (12') and
cause blank material to flow into the gaps separating the forming disks (19) and form planar
fins (14) such that the fin density is at least one
fin per millimetre and the ratio of the fin height
to the fin thickness is at least 5.
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2.
A method as claimed in claim 1 in which the blank
(12') is tubular, including the step of mounting the
blank for rotation about an axis (C) which is contained in a plane which also contains the axis (L) of
rotation of the forming tool (18), said surface of the
blank being a surface of revolution and the axis (C)
of rotation of the blank being parallel to the axis (L)
of rotation of the forming tool.
3.
A method as claimed in claim 2 in which the blank
(12') is tubular and mounted on a mandrel (N) with
substantially zero play between the blank and the
mandrel.
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A method of making a finned body (12) from a blank
(12') of a high-ductility material, comprising the
steps of
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4.
A method as claimed in claim 2 or 3 in which said
surface of the blank (12') is generally cylindrical.
5.
A method as claimed in any one of claims 2 to 4 in
which the forming tool (18) is rotated unidirectionally.
6.
7.
8.
9.
A method as claimed in any one'of claims 2 to 5 in
which the blank (12') is rotated by frictional engagement with the forming tool (18).
A method as claimed in any one of claims 1 to 6
including the step of supplying a lubricating fluid to
the sites of contact between the forming discs (19)
and the blank (12').
A method as claimed in any one of claims 1 to 6 in
which the relative displacement of the forming tool
(18) and the blank (12') is effected by means of a
first hydraulic actuator (22) applying to the forming
tool a first force (FA) directed toward the blank (12')
and a second hydraulic actuator (23) applying to the
forming tool (18) an oppositely directed second
force (FB) which is smaller than the first force (FA),
whereby the forming tool (18) applies a differential
force (FC) to the blank (12').
A method as claimed in claim 8 in which the magnitude of the oppositely directed force (FB) is controlled by controlled bleeding of hydraulic fluid from
the second actuator (23).
10. A method as claimed in claim 8 or 9 in which the
first force (FA) is several times, preferably at least
ten times, the differential force (FC).
blank (12'), and
means for maintaining the forming discs (19)
in a constant orientation and axial position relative
to the blank (12').
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13. A machine as claimed in claim 12 in which the blank
holding device (17) includes a rotatable mandrel (N)
for supporting the blank for rotation about a blank
axis (C) of rotation.
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14. A machine as claimed in claim 12 or 13 including
means (21) for supplying a lubricating fluid to the
forming discs (19).
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15. A machine as claimed in any one of claims 12 to 14
in which the displacement mechanism comprises a
first hydraulic actuator (22) connected to the forming tool (18) to apply to it a displacement force (FA)
directed toward a blank held by the blank holding
device (17) and a second hydraulic actuator (23)
connected to the forming tool (18) to apply to it an
oppositely directed force (FB) which is smaller than
the displacement force (FA).
16. A machine as claimed in claim 15 including means
for controlled bleeding of hydraulic fluid from the
second hydraulic actuator (23).
17. A machine as claimed in claim 15 or 16 in which the
second actuator (23) is adapted to apply the oppositely directed force (FB) with a magnitude thereof
which is of the same order of magnitude as the displacement force (FA).
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Patentansprüche
11. A method as claimed in any one of claims 1 to 10
in which the blank (12') is a metal body, preferably
a light metal, such as essentially pure aluminium.
1.
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12. A machine for making a finned body (12) from a
blank (12') of a high-ductility material, comprising
a blank holding device (17) for supporting the
blank (12'),
a forming tool (18) which is mounted for rotation about a tool axis (L) and displacement transversely to the tool axis (L) and comprising a set of
flat circular spaced-apart forming discs (19) centered on and disposed side by side at fixed intervals
along the tool axis (L) and in planes perpendicular
thereto,
a motor for rotationally driving the forming tool
(18), characterised by
a displacement mechanism (22,23) for relatively displacing the forming tool (18) and the blank
holding device (17) perpendicularly to the tool axis
(L) during rotation of the forming tool to cause the
forming tool to move cyclically over a surface of the
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Verfahren zur Herstellung eines gerippten Körpers
(12) aus einem Rohling (12') aus hoch verformbarem Material, das folgende Schritte umfasst:
Bereitstellen eines rippenformenden Werkzeugs (18), das eine Drehachse (L) aufweist
und einen Satz flacher, kreisförmiger, beabstandeter Formscheiben (19) umfasst, die auf
der Drehachse (L) zentriert sind und daran entlang in zu dieser senkrechten Ebenen nebeneinander in festen Abständen angeordnet sind,
Drehen des Formwerkzeugs (18) mit einer Umfangsgeschwindigkeit von 100 bis 300 m/Minute, wobei man es zyklische Bewegungen über
eine Oberfläche des Rohlings (12') ausführen
lässt,
55
dadurch gekennzeichnet, dass
die Ebenen in einer konstanten Ausrichtung und
Position im Verhältnis zu dem Rohling gehalten
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EP 0 938 391 B1
werden, und
das Formwerkzeug (18) und der Rohling (12') mit
einer Geschwindigkeit von 0,5 bis 1 mm/Minute im
rechten Winkel zu der Drehachse (L) des Formwerkzeugs (18) relativ zueinander verschoben werden, um die Randbereiche der Formscheiben (19)
während der zyklischen Bewegungen des Formwerkzeugs (18) dazu zu bringen, zunehmend in den
Rohling (12) einzudringen, und das Material des
Rohlings dazu zu bringen, in die Lücken zu fließen,
welche die Formscheiben (19) trennen, und ebene
Rippen (14) zu bilden, sodass die Rippendichte
mindestens eine Rippe pro Millimeter beträgt, und
das Verhältnis der Rippenhöhe zur Rippendicke
mindestens 5 beträgt.
2.
3.
Verfahren nach Anspruch 1, bei dem der Rohling
(12') röhrenförmig ist, umfassend den Schritt des
Befestigens des Rohlings zur Drehung um eine
Achse (C), die in einer Ebene enthalten ist, welche
auch die Drehachse (L) des Formwerkzeugs (18)
enthält, wobei diese Oberfläche des Rohlings eine
Drehfläche ist und die Drehachse (C) des Rohlings
parallel zu der Drehachse (L) des Formwerkzeugs
liegt.
Verfahren nach Anspruch 2, bei dem der Rohling
(12') röhrenförmig ist und auf einem Dorn (N) befestigt ist, wobei im Wesentlichen kein Spiel zwischen
dem Rohling und dem Dorn vorhanden ist.
4.
Verfahren nach Anspruch 2 oder 3, bei dem die Fläche des Rohlings (12') im wesentlichen zylindrisch
ist.
5.
Verfahren nach einem der Ansprüche 2 bis 4, bei
dem das Formwerkzeug (18) in nur einer Richtung
gedreht wird.
6.
Verfahren nach einem der Ansprüche 2 bis 5, bei
dem der Rohling (12') durch Reibkopplung mit dem
Formwerkzeug (18) gedreht wird.
7.
Verfahren nach einem der Ansprüche 1 bis 6, umfassend den Schritt des Abgebens einer Schmierflüssigkeit an die Kontaktstellen zwischen den
Formscheiben (19) und dem Rohling (12').
eine (FC) auf den Rohling (12') ausübt.
9.
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8.
Verfahren nach einem der Ansprüche 1 bis 6, bei
dem die relative Verschiebung des Formwerkzeugs
(18) und des Rohlings (12') mittels eines ersten hydraulischen Aktuators (22) durchgeführt wird, der
auf das Formwerkzeug eine erste Kraft (FA) ausübt,
die zum Rohling (12') hin gerichtet ist, und eines
zweiten hydraulischen Aktuators (23), der auf das
Formwerkzeug (18) eine entgegengesetzt gerichtete zweite Kraft (FB) ausübt, die kleiner ist als die
erste Kraft 1: (FA), wodurch das Formwerkzeug (18)
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Verfahren nach Anspruch 8, bei dem die Größe der
entgegengesetzt gerichteten Kraft (FB) durch gezieltes Ablassen hydraulischer Flüssigkeit aus dem
zweiten Aktuator (23) gesteuert wird.
10. Verfahren nach Anspruch 8 oder 9, bei dem die erste Kraft (FA) einem Mehrfachen, bevorzugt mindestens dem Zehnfachen, der Differenzkraft (FC) entspricht.
11. Verfahren nach einem der Ansprüche 1 bis 10, bei
dem der Rohling (12') ein Metallkörper ist, bevorzugt ein Leichtmetall, wie etwa im wesentlichen reines Aluminium.
12. Maschine zur Herstellung eines gerippten Körpers
(12) aus einem Rohling (12') aus einem hoch verformbaren Material, umfassend
eine Rohlinghaltevorrichtung (17) zum Tragen des
Rohlings (12'),
ein Formwerkzeug (18), das zur Drehung um eine
Werkzeugachse (L) und zur Verschiebung quer zu
der Werkzeugachse (L) montiert ist, und einen Satz
flacher, kreisförmiger, beabstandeter Formscheiben (19) umfasst, die auf der Werkzeugachse (L)
zentriert und an dieser entlang und in dazu senkrechten Ebenen nebeneinander in festen Abständen angeordnet sind,
einen Motor zum Drehantrieb des Formwerkzeugs
(18),
gekennzeichnet durch
einen Verschiebungsmechanismus (22, 23) zum relativen Verschieben des Formwerkzeugs (18) und
der Rohlinghaltevorrichtung (17) senkrecht zur
Werkzeugachse (L) während der Drehung des
Formwerkzeugs, um das Formwerkzeug zyklisch
über eine Fläche des Rohlings (12') zu bewegen,
und
Mittel zum Festhalten der Formscheiben (19) in einer konstanten Ausrichtung und axialen Position im
Verhältnis zu dem Rohling (12').
45
13. Maschine nach Anspruch 12, bei der die Rohlinghaltevorrichtung (17) einen drehbaren Dorn (N)
zum Tragen des Rohlings zur Drehung um eine
Rohlingdrehachse (C) umfasst.
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14. Maschine nach Anspruch 12 oder 13, umfassend
Mittel (21) zum Abgeben einer Schmierflüssigkeit
an die Formscheiben (19).
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15. Maschine nach einem der Ansprüche 12 bis 14, bei
welcher der Verschiebungsmechanismus einen ersten hydraulischen Aktuator (22), der an das Formwerkzeug (18) angeschlossen ist, um darauf eine
Verschiebungskraft (FA) auszuüben, die zu einen
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EP 0 938 391 B1
Rohling hin gerichtet ist, der von der Rohlinghaltevorrichtung (17) gehalten wird, und einen zweiten
hydraulischen Aktuator (23) umfasst, der an das
Formwerkzeug (18) angeschlossen ist, um darauf
eine entgegengesetzt gerichtete Kraft (FB) auszuüben, die kleiner ist als die Verschiebungskraft (FA).
16. Maschine nach Anspruch 15, umfassend Mittel zum
gezielten Ablassen hydraulischer Flüssigkeit aus
dem zweiten hydraulischen Aktuator (23).
17. Maschine nach Anspruch 15 oder 16, bei der das
zweite Betätigungsgerät (23) dazu ausgebildet ist,
die entgegengesetzt gerichtete Kraft (FB) in einer
Größe auszuüben, die in der Größenordnung der
Verschiebungskraft (FA) liegt.
étant parallèle à l'axe (L) de rotation de l'outil de formage.
3.
Procédé selon la revendication 2, dans lequel
l'ébauche (12') est tubulaire et montée sur un mandrin (N) avec un jeu sensiblement nul entre l'ébauche et le mandrin.
4.
procédé selon la revendication 2 ou 3, dans lequel
ladite surface de l'ébauche (12') est généralement
cylindrique.
5.
Procédé selon l'une quelconque des revendications
2 à 4, dans lequel l'outil de formage (18) est mis en
rotation de manière unidirectionnelle.
6.
Procédé selon l'une quelconque des revendications
2 à 5, dans lequel l'ébauche (12') est mise en rotation par contact à frottement avec l'outil de formage
(18).
7.
Procédé selon l'une quelconque des revendications
1 à 6, incluant l'étape consistant à délivrer un fluide
de lubrification aux sites de contact entre les disques de formage (19) et l'ébauche (12').
8.
Procédé selon l'une quelconque des revendications
1 à 6, dans lequel le déplacement relatif de l'outil
de formage (18) et de l'ébauche (12') est effectué
au moyen d'un premier vérin hydraulique (22) appliquant à l'outil de formage une première force (FA)
dirigée vers l'ébauche (12') et un second vérin hydraulique (23) appliquant à l'outil de formage (18)
une seconde force (FB) dirigée en sens opposé qui
est plus faible que la première force (FA), avec pour
effet que l'outil de formage (18) applique une force
différentielle (FC) à l'ébauche (12').
9.
Procédé selon la revendication 8, dans lequel la
grandeur de la force (FB) dirigée en sens opposé
est commandée par un écoulement commandé du
fluide hydraulique depuis le second vérin (23).
5
10
15
Revendications
20
1.
2.
Procédé de fabrication d'un corps à ailettes (12) à
partir d'une ébauche (12') d'un matériau à ductilité
élevée, comprenant les étapes consistant à
fournir un outil de formage d'ailettes (18)
ayant un axe de rotation (L) et comprenant un ensemble de disques de formage (19) circulaires plats
espacés centrés sur ledit axe de rotation (L) et disposés côte à côte à des intervalles fixes le long de
celui-ci et dans des plans perpendiculaires à celuici,
faire tourner l'outil de formage (18) à une vitesse périphérique de 100 à 300 m/minute tout en
lui faisant effectuer des déplacements cycliques sur
une surface de l'ébauche (12') caractérisé en ce
que lesdits plans sont maintenus à une orientation
et une position constantes par rapport à l'ébauche,
et
déplacer relativement l'outil de formage (18)
et l'ébauche (12') à une vitesse de 0,5 à 1 mm/minute à angle droit par rapport à l'axe (L) de rotation
de l'outil de formage (18) pour amener les parties
périphériques des disques de formage (19) pendant lesdits déplacements cycliques de l'outil de formage (18) à pénétrer progressivement dans l'ébauche (12') et amener le matériau d'ébauche à s'écouler dans les espaces séparant les disques de formage (19) et à former les ailettes planes (14), de
sorte que la densité d'ailettes est au moins d'une
ailette par millimètre et que le rapport de la hauteur
d'ailette à l'epaisseur d'ailette est d'au moins 5.
Procédé selon la revendication 1, dans lequel
l'ébauche (12') est tubulaire, incluant l'étape consistant à monter l'ébauche en rotation autour d'un axe
(C) qui est contenu dans un plan qui contient également l'axe (L) de rotation de l'outil de formage
(18), ladite surface de l'ébauche étant une surface
de révolution et l'axe (C) de rotation de l'ébauche
12
25
30
35
40
45
50
55
7
10. Procédé selon la revendication 8 ou 9, dans lequel
la première force (FA) est plusieurs fois, de préférence au moins dix fois, la force différentielle (FC).
11. Procédé selon l'une quelconque des revendications
1 à 10, dans lequel l'ébauche (12') est un corps métallique, de préférence un métal léger, tel que de
l'aluminium essentiellement pur.
12. Machine pour fabriquer un corps à ailettes (12) à
partir d'une ébauche (12') d'un matériau à ductilité
élevée, comprenant
un dispositif de maintien d'ébauche (17) pour
supporter l'ébauche (12'),
un outil de formage (18) qui est monté en ro-
13
EP 0 938 391 B1
tation autour d'un axe de l'outil (L) et ayant un déplacement transversal à l'axe de l'outil (L) et comprenant un ensemble de disques de formage (19)
plats circulaires espacés centrés sur ledit axe de
rotation (L) et disposés côte à côte à des intervalles
fixes le long de celui-ci et dans des plans perpendiculaires à celui-ci,
un moteur pour entraîner en rotation l'outil de
formage (18), caractérisé par
un mécanisme de déplacement (22, 23) pour
déplacer relativement l'outil de formage (18) et le
dispositif de maintien d'ébauche (17) perpendiculairement à l'axe de l'outil (L) pendant la rotation de
l'outil de formage pour amener l'outil de formage à
se déplacer cycliquement sur une surface de
l'ébauche (12'), et
un moyen pour maintenir les disques de formage (19) en une orientation et une position axiale
constantes par rapport à l'ébauche (12').
5
10
15
20
13. Machine selon la revendication 12, dans laquelle le
dispositif de maintien d'ébauche (17) inclut un mandrin rotatif (N) pour supporter l'ébauche en rotation
autour d'un axe de rotation d'ébauche (C).
25
14. Machine selon la revendication 12 ou 13, incluant
un moyen (21) pour délivrer un fluide de lubrification
aux disques de formage (19).
15. Machine selon l'une quelconque des revendications 12 à 14, dans laquelle le mécanisme de déplacement comprend un premier vérin hydraulique
(22) raccordé à l'outil de formage (18) pour appliquer à celui-ci une force de déplacement (FA) dirigée vers une ébauche maintenue par le dispositif
de maintien d'ébauche (17) et un second vérin hydraulique (23) raccordé à l'outil de formage (18)
pour appliquer à celui-ci une force (FB) dirigée en
sens opposé qui est plus petite que la force de déplacement (FA).
30
35
40
16. Machine selon la revendication 15, incluant un
moyen pour l'écoulement commandé du fluide hydraulique à partir du second vérin hydraulique (23).
45
17. Machine selon la revendication 15 ou 16, dans laquelle le second vérin (23) est propre à appliquer la
force (FB) dirigée en sens opposé de pour celle-ci
une grandeur qui est du même ordre de grandeur
que la force de déplacement (FA).
50
55
8
14
EP 0 938 391 B1
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EP 0 938 391 B1
10