U.S. patent application number 10/450361 was filed with the patent office on 2004-06-03 for internal high pressure forming device and method and corresponding tool system.
Invention is credited to Winters, Andreas.
Application Number | 20040103707 10/450361 |
Document ID | / |
Family ID | 26007945 |
Filed Date | 2004-06-03 |
United States Patent
Application |
20040103707 |
Kind Code |
A1 |
Winters, Andreas |
June 3, 2004 |
Internal high pressure forming device and method and corresponding
tool system
Abstract
The invention relates to a hydroforming device and a
hydroforming process and also to a hydroforming die arrangement. To
make it possible to produce even complex three-dimensional
sheet-metal shapes while ensuring that the deformation process
takes place without disruption, the device comprises a die (5)
which is divided into two die halves (5a, 5b) along a die parting
plane, the two die halves (5a, 5b) forming at least one forming
chamber (6) which can be acted on by a hydrostatic internal
pressure (Pi) for forming purposes at a workpiece (7) which is to
be deformed, a die carrier (2), which for each die half (5a, 5b)
has at least one die carrier component (3, 4) assigned to this die
half (5a, 5b), each pair made up of die carrier component (3, 4)
and die half (5a, 5b) being assigned at least one fluid chamber (8)
which is formed from a piston component and a piston-receiving
component, and means being provided for producing a hydrostatic
fluid chamber pressure (Pa) which is at least equal to the
hydrostatic internal pressure (Pi) and, compensating for the
hydrostatic internal pressure (Pi), exerts a die-closing force on
the two die halves (5a, 5b).
Inventors: |
Winters, Andreas; (Solingen,
DE) |
Correspondence
Address: |
FOLEY & LARDNER
P.O. BOX 80278
SAN DIEGO
CA
92138-0278
US
|
Family ID: |
26007945 |
Appl. No.: |
10/450361 |
Filed: |
December 3, 2003 |
PCT Filed: |
December 3, 2001 |
PCT NO: |
PCT/DE01/04492 |
Current U.S.
Class: |
72/60 |
Current CPC
Class: |
B21D 26/031 20130101;
B21D 35/003 20130101 |
Class at
Publication: |
072/060 |
International
Class: |
B21D 022/10 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 12, 2000 |
DE |
100 61 884.7 |
Aug 2, 2001 |
DE |
101 37 476.3 |
Claims
1. Hydroforming device, comprising at least one die (5, 5') which
is divided into two die halves (5a, 5b) along a die parting plane,
the two die halves (5a, 5b) forming at least one forming chamber
(6) which can be acted on by a hydrostatic internal pressure (Pi)
for forming purposes at a workpiece (7) which is to be deformed, a
die carrier (2), which for each die half (5a, 5b) has at least one
die carrier component (3, 4) assigned to this die half (5a, 5b),
each pair made up of die carrier component (3, 4) and die half (5a,
5b) being assigned at least one fluid chamber (8) which is formed
from a piston component and a piston-receiving component, and means
being provided for producing a hydrostatic fluid chamber pressure
(Pa), which is at least equal to the hydrostatic internal pressure
(Pi), in each of the fluid chambers (8), which fluid chamber
pressure, compensating for the hydrostatic internal pressure (Pi),
exerts a die-closing force on the two die halves (5a, 5b) wherein
in each case a plurality of adjacent fluid chambers (8) are
provided on opposite sides of the die (5), and wherein the means
for producing the hydrostatic fluid chamber pressure (Pa) are
configured in such a way that the fluid chambers (8), partially
and/or jointly, can be acted on by an identical or different fluid
chamber pressure (Pa).
2. Device according to claim 1, in which at least one pair
comprising piston component and associated piston-receiving
component is formed by a die carrier component (3, 4) and the
associated die half (5a, 5b).
3. Device according to claim 1, in which at least one pair
comprising piston component and associated piston-receiving
component is formed by two die carrier fixtures (3a, 3b, 4a, 4b) of
the corresponding die carrier component (3, 4).
4. Device according to claim 3, in which, in the case of at least
one die carrier component (3, 4), one associated die carrier
fixture (3a, 4b) is provided with piston-like projections (14) in
order to form the piston component, and the other die carrier
fixture (3b, 4a) is provided with corresponding cavities (13).
5. Device according to claim 4, in which each pair of cavities (13)
or piston-like projections (14) in each case encloses a fluid
chamber (8).
6. Device according to anyone of the preceding claims, in which
there are means for guiding the die carrier components (3, 4).
7. Device according to anyone of the preceding claims, in which
fluid chambers (8) which are respectively assigned to two different
die halves (5a, 5b) are arranged opposite one another.
8. Device according to anyone of the preceding claims, in which
each pair comprising piston component and associated
piston-receiving component in each case forms a sealing unit which
seals off each fluid chamber (8) in a pressure-tight manner.
9. Device according to anyone of claims 1 to 8, in which the fluid
chambers (8), perpendicular to the piston axis, are each round or
oval in cross section.
10. Device according to anyone of claims 1 to 8, in which the fluid
chambers (8), perpendicular to the piston axis, are each triangular
or rectangular in cross section.
11. Device according to anyone of the preceding claims, in which
the means for producing the hydrostatic fluid chamber pressure (Pa)
are configured in such a way that the fluid chamber pressure (Pa)
which is produced in the fluid chambers (8) located opposite one
another is in each case identical.
12. Device according to anyone of the preceding claims, in which
the means for producing the fluid chamber pressure (Pa) are
configured in such a way that the forces exerted on the two die
halves (5a, 5b) by the fluid chamber pressure (Pa) are oppositely
directed and are of equal magnitude.
13. Device according to anyone of the preceding claims, in which
there is a control circuit for controlling the hydrostatic fluid
chamber pressure (Pa) as a function of the force exerted on the
corresponding die half (5a, 5b).
14. Device according to anyone of the preceding claims, in which
the die carrier (2) is integrated in a clamping table for clamping
the die halves (5a, 5b) in place.
15. Device according to anyone of the preceding claims, in which
between the two die halves (5'a, 5'b) of the die (5'), in the die
parting plane, there is a forming element (5'c), which together
with each of the die halves (5'a, 5'b), in each case forms a
forming chamber (6a, 6b) which can be acted on by a hydrostatic
internal pressure for shaping purposes at in each case one
workpiece which is to be deformed.
16. Device according to claim 15, in which the forming element
(5'c) is of mirror-symmetrical construction with regard to the die
parting plane.
17. Device according to claim 15 or 16, in which the forming
element (5'c) between the die halves (5'a, 5'b) is secured to a
frame which bears the die carrier (2).
18. Device according to claim 15 or 16, in which the forming
element (5'c) is surrounded in a pressure-tight manner by the die
halves (5'a, 5'b).
19. Device according to claim 18, in which the forming element
(5'c) is mounted in a floating position between the two die halves
(5'a, 5'b).
20. Device according to anyone of claims 15 to 19, in which a
plurality of dies (5) are arranged adjacent to one another in a
direction which is perpendicular to the die parting plane.
21. Device according to claim 20, in which in the die parting plane
of at least one of the dies (5), there is a forming element (5'c)
provided between the respective die halves (5'a, 5'b), which
forming element, together with each of the associated die halves
(5'a, 5'b), in each case forms a forming chamber (6a, 6b) which can
be acted on by a hydrostatic internal pressure for shaping purposes
at in each case one workpiece which is to be deformed.
22. Hydroforming device assembly, comprising at least two devices
according to anyone of claims 1 to 21, which form a functional
unit.
23. Hydroforming die arrangement (40-70), in which a plurality of
dies, which are in each case divided into two die halves along a
die parting plane, are arranged in a stacked arrangement in a
direction which is perpendicular to the die parting planes, in
which arrangement, during mounting of the die arrangement (40, 50,
60, 70) between in each case two adjacent die halves (41-71, 45-75,
46-76, 42-72) together with a workpiece which is to be deformed, a
pressure chamber (A), which can be acted on by a hydrostatic
internal pressure (Pi) for shaping purposes at the workpiece, is
formed by the workpiece and one die half, and a deformation chamber
(B) is formed by the workpiece and the other die half; and the
deformation chamber (B) being in fluid communication, via the
respectively adjacent die half, with the surroundings of the die
arrangement (40-80), so that when pressure is applied to the
pressure chamber (A), pressure is prevented from building up in the
deformation chamber (B).
24. Hydroforming die arrangement according to claim 23, in which
the die half which adjoins the corresponding deformation chamber.
(B) has outlet openings (101, 102, 201, 202, 301, 302) extending
from the surroundings of the die to the corresponding deformation
chamber (B).
25. Hydroforming die arrangement according to claim 24, in which
the outlet openings (101, 102, 201, 202, 301, 302) comprise at
least one outlet passage (101, 201) extending parallel to the die
parting plane and a plurality of outlet passages (102, 202)
arranged perpendicular thereto.
26. Hydroforming die arrangement according to claim 23 or 24, in
which the die half (300) which adjoins the corresponding
deformation chamber (B) is divided along the die parting plane at
least into two separate components (300a, 300b), which each have
outlet openings (301, 302) extending perpendicular to the die
parting plane toward the corresponding deformation chamber (B).
27. Hydroforming die arrangement according to anyone of claims 23
to 26, in which the stacked arrangement is such that in each case
one die half which in each case forms a deformation chamber (B)
with the adjacent workpieces (49-89) and one die half which in each
case forms a pressure chamber (A) with the adjacent workpieces
(49-89) are arranged adjacently, in an alternating sequence,
perpendicular to the die parting plane (FIGS. 10a, 10b).
28. Hydroforming die arrangement according to claim 27, in which at
least one of the die halves which in each case forms a pressure
chamber (A) with the adjacent workpieces (49-89) has a fluid
passage, which branches off towards the two workpieces (49-89), for
applying the hydrostatic internal pressure (Pi) to the pressure
chambers (A) (FIG. 10a).
29. Hydroforming die arrangement according to claim 27 or 28, in
which at least one of the die halves-which in each case forms a
pressure chamber (A) with the adjacent workpieces (49-89) has two
fluid passages which branch off in opposite directions for
independent application of the hydrostatic internal pressure (Pi)
to the corresponding pressure chambers (A) (FIG. 10b).
30. Hydroforming die arrangement according to anyone of claims 23
to 26, in which the stacked arrangement is such that in each case
one pressure chamber (A) and one deformation chamber (B) are formed
in an alternating sequence perpendicular to the die parting plane
(FIG. 10c).
31. Hydroforming process, in which in at least one die (5), which
is divided into two die halves (5a, 5b) along a die parting plane,
at least one forming chamber (6), which is formed by the die halves
(5a, 5b), is acted on by a hydrostatic internal pressure (Pi) for
shaping purposes at a workpiece (7) which is to be deformed, and in
which a hydrostatic fluid chamber pressure (Pa), which is in each
case at least equal to the internal pressure (Pi) and, compensating
for the hydrostatic internal pressure (Pi), exerts a die-closing
force on the two die halves (5a, 5b), is produced in fluid chambers
(8) which are formed from a piston component and a piston-receiving
component and are each assigned to one of the die halves (5a, 5b)
wherein in each case a plurality of adjacent fluid chambers (8) on
opposite sides of the die (5) are partially and/or jointly acted on
by an identical or different fluid chamber pressure (Pa).
32. Process according to claim 31, in which the hydrostatic fluid
chamber pressure (Pa) is controlled as a function of the force
which is exerted on the corresponding die half (5a, 5b) by the
fluid chamber (8).
33. Process according to claim 31 or 32, in which, in the die (5'),
two forming chambers (6'a, 6'b), which are arranged opposite one
another and are each formed by in each case one of the die halves
(5'a, 5'b) with a forming element (5'c) arranged in the die parting
plane between the two die halves (5'a, 5'b) of the die (5'), are
simultaneously acted on by a hydrostatic internal pressure.
34. Process according to claim 33, in which the forming element
(S'c) is arranged mirror-symmetric-ally with respect to the die
parting plane, and the two forming chambers (6a, 6b), in order to
form two identical components from workpieces which are in each to
be deformed, are simultaneously acted on by an identical
hydrostatic internal pressure (Pi).
35. Process according to claim 33 or 34, in which, in a plurality
of dies (5) which are arranged adjacent to one another
perpendicular to the respective die parting plane and have forming
elements (5'c) provided in the respective die parting plane between
the respective die halves (5'a, 5'b), a plurality of forming
chambers, which are in each case formed by in each case one of the
die halves (5'a, 5'b) and one of the forming elements (5'c), are
simultaneously acted on by a hydrostatic internal pressure.
36. Hydroforming process, in which, in a hydroforming die
arrangement (40-70) in which a plurality of dies which are in each
case divided into two die halves along a die parting plane are
arranged in a stacked arrangement in a direction perpendicular to
the die parting planes, the die arrangement (40, 50, 60, 70) is
equipped, between in each case two adjacent die halves (41-71,
45-75, 46-76, 42-72), with a workpiece which is to be deformed, so
that a pressure chamber (A) is formed by the workpiece and one die
half and a deformation chamber (B) is formed by the workpiece and
other die half; each of the pressure chambers is acted on by a
hydrostatic internal pressure (Pi) for shaping purposes at the
corresponding workpiece; and when pressure is applied to the
pressure chamber (A), a build-up of pressure in the deformation
chamber (B) is prevented by means of at least one fluid connection
between the respectively adjacent die half and the surroundings of
the die arrangement (40-80).
Description
[0001] The invention relates to a hydroforming device and a
hydroforming process and to a hydroforming die arrangement.
[0002] Hydroforming is used to deform workpieces by application of
hydrostatic pressure and is employed, for example, in the
automotive industry. In this case, the workpiece which is to be
processed is surrounded by a shaping, generally split die, which
has a fluid feed line for application of the hydrostatic pressure
which is required to deform the workpiece. The workpieces which are
to be deformed may, for example, be tubes or plates, the forming
chamber which is located in the interior of the die and is in
communication with the fluid feed line being designed to match the
desired shape of the deformed workpiece.
[0003] Since, on account of the hydrostatic pressure introduced,
the die halves which form the die endeavour to drift apart, a
closure-holding device, i.e. a die carrier for clamping the die in
place, and the closure-holding force which is exerted on the die by
the closure-holding components or die carrier components has to be
greater than or equal to the force which results from the
hydrostatic internal pressure which has been introduced into the
forming chamber. Depending on the level of the internal pressure
which is required for deformation of the workpiece, the
closure-holding forces required may be so great that elastic
deformations occur in the components of the die carrier, and these
are in turn transferred to the die halves. Consequently, the
precision positive lock of the die which is required for
hydroforming is no longer present, with the result that the
internal pressure can locally escape at the leaks which are formed,
and the deformation process is interrupted. This problem is
particularly serious if relatively complex deformation operations
are to be performed, in order, for example, to deform metal sheets,
e.g. for automotive bodywork parts, in a plurality of planes, since
the parting planes between the die halves are then
three-dimensionally curved, and the demands imposed on the
corresponding sealing surfaces which seal off the forming chamber
are correspondingly high. Consequently, deformation of complex,
three-dimensional sheet-metal geometries, for example for
automotive bodywork parts, is in practice possible with the known
hydroforming processes and devices.
[0004] A hydroforming device and hydroforming process in which the
closure-holding force required to compensate for the internal
pressure is produced by means of a cylinder assembly arranged
beneath a press platen are known. Moreover, by suitably connecting
and controlling the cylinders, it is possible to accurately
determine the closure-holding forces according to the demands
imposed on the die. To limit the influence of elastic deformations
in the die carrier components, it is provided with structural
reinforcements in the form of increases in the wall thickness. On
account of the deployment of large quantities of material required
for this purpose, however, the overall size, complexity and weight
of the die carrier are increased considerably, with the result that
on the one hand devices of this type are difficult and expensive to
procure, install and operate and, on the other hand, the
abovementioned high demands imposed on the sealing surfaces for
sealing off the deformation chamber when deforming complex
three-dimensional sheet-metal geometries are not satisfied.
[0005] DE 197 16 663 C1 has disclosed a device for the hydrostatic
deformation of cold-formable flat metallic material, in which the
sheet-metal body which is to be shaped is held between two female
die plates, one of which has an engraved structure corresponding to
the desired shape, a press ram which is mounted such that it can
move in the vertical direction acting on the upper female die
plate. At least one of the two female die plates is of flexible
design, and a layer which is clamped in place on all sides and has
a hydraulically passive action is arranged between the flexible
female die plate and the press ram.
[0006] Although the fact that the female die plate nestles against
the surface of the flat material which is to be deformed within a
certain pressure range alleviates the effects of deformation of the
female die plate on the seal during the deformation process, this
compensation is only sufficiently effective within a restricted
pressure range, meaning that when high die-closing forces are
required, additional structural reinforcements are also required in
order to maintain the required positive lock between the die
halves.
[0007] DE 198 34 471 A1 has disclosed a device for carrying out a
hydroforming operation which has a pressure vessel which is
arranged in a frame and comprises upper and lower vessel parts,
which each bear mould parts therein. Between the mould parts there
is a mould cavity in which a workpiece which is to be processed by
means of hydroforming is arranged. Furthermore, an expandable
bellows, into which a pressurized fluid is introduced while the
mould cavity is being acted on by likewise a pressurized fluid, in
order to prevent the mould parts from drifting apart, is arranged
between one or both mould parts and the associated upper and lower
vessel parts.
[0008] However, this device firstly has the drawback that the
flexible materials which are required to form the flexible bellows,
when high pressures are introduced, has the property of being able
to penetrate into any gaps, even extremely small ones, which form
in the device. Moreover, to allow the vessel part which is in each
case located above or below the bellows to move in the vertical
direction, it is for design reasons necessary to take account of a
gap dimension between the vessel part and the corresponding mould
part, with the result that the flexible, inflatable bellows can
work its way into the gap during the hydroforming operation and
will sooner or later be destroyed. Furthermore, in this device too,
elastic deformations to the corresponding vessel part are
transferred via the flexible bellows to the adjoining mould part,
so that given correspondingly high pressures the required precision
form fit between the die halves is no longer ensured. This is true
in particular if, as described above, complex sheet-metal
geometries are being shaped, since at the three-dimensionally
curved sealing surfaces which are then required, the flexible
bellows is insufficient to compensate for the said elastic
deformations.
[0009] Therefore, it is an object of the invention to provide a
hydroforming device and a hydroforming process with which even
complex, three-dimensional sheet-metal geometries can be achieved
while it is ensured that a deformation process takes place without
disruption.
[0010] This object is achieved in accordance with the features
given in the independent claims.
[0011] To this end, a hydroforming device comprises
[0012] at least one die which is divided into two die halves along
a die parting plane, the two die halves forming at least one
forming chamber which can be acted on by a hydrostatic internal
pressure for forming purposes at a workpiece which is to be
deformed,
[0013] a die carrier, which for each die half has at least one die
carrier component assigned to this die half,
[0014] each pair made up of die carrier component and die half
being assigned at least one fluid chamber which is formed from a
piston component and a piston-receiving component, and
[0015] means being provided for producing a hydrostatic fluid
chamber pressure, which is at least equal to the hydrostatic
internal pressure, in each of the fluid chambers, which fluid
chamber pressure, compensating for the hydrostatic internal
pressure, exerts a die-closing force on the two die halves.
[0016] On account of the fluid chambers according to the invention,
which can be acted on by a hydrostatic fluid chamber pressure which
compensates for the hydrostatic internal pressure in the forming
chamber, it is possible for the closure-bonding force which is
required for the purpose of maintaining a positive lock between the
die halves during the deformation process to the die halves without
elastic deformations of the die carrier components being
transferred to the die halves. This is because such deformations in
each case cancel one another out on the sides of the corresponding
die carrier components which face the die halves and therefor only
occur at those side faces of the die carrier which are remote from
the die halves, where they are, for example, dissipated into a
frame of the hydroforming device. In this way, the required
precision positive lock for ensuring that a deformation process
proceeds without disruption is guaranteed even when forming complex
workpieces, for example metal sheets with three-dimensionally
curved surfaces.
[0017] Since in this way the elastic deformations of the die
carrier components in the direction of the corresponding die halves
are compensated for in a self-regulating manner, the remaining
elastic deformations of the die carrier components have no effect
on the sealing during the deformation process, meaning that in
particular there is no need for any additional structural
reinforcements or increases to the wall thickness, but rather
devices can be produced in lightweight structure.
[0018] The device according to the invention or the corresponding
process also has the advantage that it is also possible for fluid
chambers of a plurality of die carrier components to be connected
next to one another in an assembly, so that it is possible to
produce devices with considerable overall sizes of a length of many
metres and with high closure-holding forces, which is important in
particular when deforming very large plates, e.g. for metal
cladding panels in the construction industry, but also for
aeronautics, marine engineering applications and rail-borne
transport.
[0019] According to an advantageous configuration, at least one
pair comprising piston component and associated piston-receiving
component is formed by two die carrier fixtures of the die carrier
component in question. However, it is also possible for at least
one pair comprising piston component and associated
piston-receiving component to be formed by a die carrier component
and the associated die half.
[0020] According to a further advantageous configuration, in the
case of at least one die carrier component the associated die
carrier fixture is provided with piston-like projections in order
to form the piston component, and the other die carrier fixture is
provided with corresponding cavities. In this case, each pair
comprising cavity and piston-like projection can in each case
enclose a fluid chamber, or alternatively it is possible to form a
single common fluid chamber by using the entire area which remains
between the cavities and the piston-like projections as a
hydraulically acting surface.
[0021] According to a further advantageous configuration, there are
means for guiding the die carrier components in the hydroforming
device, e.g. along a frame in the hydroforming device.
[0022] According to a further advantageous configuration, each die
half is assigned at least two adjacent fluid chambers, with in each
case a multiplicity of fluid chambers arranged in matrix form
preferably being provided on opposite die sides.
[0023] Consequently, the device according to the invention has
considerable flexibility with regard to the positioning of the die
halves in the die carrier, since the fluid chambers can be acted on
by the hydrostatic external pressure either jointly or
alternatively only partially, e.g. in a manner which is
synchronized to one another at the top and bottom. In this way,
there is no need for either central positioning of the die or a
certain minimum size of the die carrier components in order to
achieve a uniform closure-holding distribution, with the result
that it becomes considerably easier to mount the device according
to the invention compared with known devices.
[0024] According to a further advantageous configuration, fluid
chambers which are respectively assigned to two different die
halves are arranged opposite one another, so that it is ensured
that, given an identical application of pressure to the fluid
chambers lying opposite one another, an equal fluid chamber
pressure is generated on both sides.
[0025] According to a further advantageous configuration, each pair
comprising piston component and associated piston-receiving
component in each case forms a sealing unit which closes off each
fluid chamber in a pressure-tight manner. However, it is also
possible for only the outer edge region of the corresponding die
carrier component to be sealed, so that the entire space which
remains inside the seal between the die carrier fixtures of the die
carrier component can be used as a hydraulically acting
surface.
[0026] Perpendicular to the piston axis, the fluid chambers may in
each case have a cross section which is round, oval or of any other
desired form, e.g. triangular or square.
[0027] According to a further advantageous configuration, the means
for producing the hydrostatic fluid chamber pressure are configured
in such a way that the fluid chambers, partially and/or jointly,
can be acted on by an identical or different fluid chamber
pressure. In this way, it is possible to achieve a maximum degree
of flexibility with regard to the positioning of the die between
the die carrier components and therefore an easy mounting/handling
operation.
[0028] According to a further advantageous configuration, the means
for producing the hydrostatic fluid chamber pressure are configured
in such a way that the fluid chamber pressure which is produced in
the fluid chambers located opposite one another is in each case
identical. However, even more advantageously the means for
producing the fluid chamber pressure are configured in such a way
that the forces exerted on the two die halves by the fluid chamber
pressure are oppositely directed and are of equal magnitude.
[0029] According to a further advantageous configuration, there is
a control circuit for controlling the hydrostatic fluid chamber
pressure as a function of the force exerted on the corresponding
die half. In this way, it is possible to compensate for deviations
in the size of the active surfaces of the die carrier components,
for example resulting from manufacturing-related tolerances, so
that a defined force is exerted on the die half in question
irrespective of the size of the corresponding active surface.
[0030] According to a further advantageous configuration, between
the two die halves of the die, in the die parting plane, there is a
forming element, which together with each of the die halves, in
each case forms a forming chamber which can be acted on by a
hydrostatic internal pressure for shaping purposes at in each case
one workpiece which is to be deformed. The forming element is
preferably of mirror-symmetrical construction with respect to the
die parting plane.
[0031] In this way, it becomes possible, when in each case one
workpiece which is to be deformed is positioned in each of the two
forming chambers, to form two corresponding components in a single
production step by hydrostatic application of an identical
hydrostatic internal pressure to the two forming chambers, since
during the application of hydraulic force the forming element
exerts a shaping action on the workpiece located in each forming
chamber on both sides, i.e. in each of the two forming
chambers.
[0032] This firstly creates a particularly efficient production
process. Secondly, however, it is in this way possible to produce a
pair of accurately matching components in a simple way, which is
very important for example for the production of sandwich-like
structures of thin metal sheets which are to be formed with in each
case complex surface geometries.
[0033] According to a preferred embodiment, the forming element,
between the die halves, is secured to a frame which bears the die
carrier. This configuration is particularly advantageous since to
fit workpieces which are to be treated into the hydroforming device
and to remove them after the deformation operation, the two die
halves or the associated die carrier components can simply be slid
apart in the vertical direction while the forming element remains
in its defined position.
[0034] However, the forming element may also be surrounded in a
pressure-tight manner by the die halves, and in particular may also
be mounted in a floating position between the two die halves. The
"floating" mounting is in this case to be understood as referring
to the vertical direction facing the respective die halves, i.e.
the forming element which is surrounded by the die halves or
enclosed by them in a pressure-tight manner can be displaced in
this vertical direction, whereas in the horizontal direction it is
surrounded by the die halves and consequently retains a defined
position.
[0035] According to a further preferred embodiment, a plurality of
dies with a forming element provided in the die parting plane
between the respective die halves are arranged adjacent to one
another in a direction perpendicular to the die parting plane.
[0036] According to a further preferred embodiment, in the die
parting plane of at least one of the dies, there is a forming
element provided between the respective die halves, which forming
element, together with each of the associated die halves, in each
case forms a forming chamber which can be acted on by a hydrostatic
internal pressure for shaping purposes at in each case one
workpiece which is to be deformed.
[0037] According to a further advantageous configuration, the die
carrier is integrated in a clamping table (press platen) for
clamping the die halves in place. This is advantageous in
particular if an assembly is formed between a plurality of press
platens in order to achieve an increased overall size.
[0038] According to a further aspect of the invention, a plurality
of dies, which are in each case divided into two die halves along a
die parting plane, are arranged in a stacked arrangement in a
direction perpendicular to the die parting planes,
[0039] in which arrangement, during mounting of the die arrangement
between in each case two adjacent die halves together with a
workpiece which is to be deformed, a pressure chamber, which can be
acted on by a hydrostatic internal pressure for shaping purposes at
the workpiece, is formed by the workpiece and one die half, and a
deformation chamber is formed by the workpiece and the other die
half; and
[0040] the deformation chamber being in fluid communication, via
the respectively adjacent die half, with the surroundings of the
die arrangement, so that when pressure is applied to the pressure
chamber, pressure is prevented from building up in the deformation
chamber.
[0041] A hydroforming die arrangement of this type has the
advantage over a conventional hydroforming die that the number of
deformed workpieces ejected per operation is increased, since at
each deformation cycle in the hydroforming die arrangement, a
plurality of workpieces can be formed simultaneously. On account of
the fluid connection between each deformation chamber and the
surroundings of the die arrangement via the respectively adjoining
die half, it is in this case ensured that the deformation can take
place particularly easily, since a build-up of pressure in the
deformation chambers is effectively prevented during each
deformation process, i.e. during the application of hydrostatic
internal pressure to the pressure chambers.
[0042] In this way, it is possible to produce particularly large
numbers of workpieces per operation, which significantly increases
the economic viability of the arrangement. Therefore, the drawback
of relatively long cycle times which is usually cited in connection
with hydroforming in comparison with conventional processes, such
as deep-drawing or stamping, is considerably alleviated.
[0043] A hydroforming die arrangement of this type is particularly
suitable for use in the hydroforming device described above, but
can also be used in a conventional hydroforming device in which the
closure-holding force which is required to compensate for the
internal pressure is generated, for example, by means of cylinder
assemblies arranged beneath the press platen. The die arrangement
is suitable for use in a conventional hydroforming device in
particular if workpieces with a substantially planar geometry are
to be produced instead of complex three-dimensional sheet-metal
geometries.
[0044] According to a further preferred embodiment, the die half
which adjoins the corresponding deformation chamber has outlet
openings extending from the surroundings of the die to the
corresponding deformation chamber, in order to ensure the fluid
connection between the corresponding deformation chamber and the
surroundings of the die arrangement.
[0045] The outlet openings preferably comprise at least one outlet
passage extending parallel to the die parting plane and a plurality
of outlet passages arranged perpendicular thereto.
[0046] According to a further preferred embodiment, the die half
which adjoins the corresponding deformation chamber is divided
along the die parting plane at least into two separate components,
which each have outlet openings extending perpendicular to the die
parting plane towards the corresponding deformation chamber. This
type of design of the die half is particularly favourable in terms
of manufacturing technology, since, for example, the outlet
passages which are to be formed in each of the die halves
perpendicular to the die parting plane have a reduced length when
the die half is of two-piece design compared to a single-piece
design.
[0047] According to a further preferred embodiment, the stacked
arrangement is such that in each case one die half which in each
case forms a deformation chamber with the adjacent workpieces and
one die half which in each case forms a pressure chamber with the
adjacent workpieces are arranged adjacently, in an alternating
sequence, perpendicular to the die parting plane. A stacked
arrangement of dies in the hydroforming device of this type also
makes it possible to increase the number of workpieces which can be
produced per operation and therefore the economic viability of the
installation to a considerable extent.
[0048] According to a further preferred embodiment, at least one of
the die halves which in each case forms a pressure chamber with the
adjacent workpieces has a fluid passage, which branches off towards
the two workpieces, for applying the hydrostatic internal pressure
to the pressure chambers. This ensures that the respective pressure
chambers which are in communication with the branched fluid passage
can be acted on by an identical hydrostatic pressure in a
particularly simple way.
[0049] According to a further preferred embodiment, at least one of
the die halves which in each case forms a pressure chamber with the
adjacent workpieces has two fluid passages which branch off in
opposite directions for independent application of the hydrostatic
internal pressure to the corresponding pressure chambers. This
ensures that the corresponding pressure chambers are in
communication with separate fluid passages and can therefore be
acted on by different hydrostatic pressures.
[0050] According to a further preferred embodiment, the stacked
arrangement is such that in each case one pressure chamber and one
deformation chamber are formed in an alternating sequence
perpendicular to the die parting plane.
[0051] In the hydroforming process according to the invention, in
at least one die, which is divided into two die halves along a die
parting plane, at least one forming chamber, which is formed by the
die halves, is acted on by a hydrostatic internal pressure for
shaping purposes at a workpiece which is to be deformed, and a
hydrostatic fluid chamber pressure, which is in each case at least
equal to the internal pressure and, compensating for the
hydrostatic internal pressure, exerts a die-closing force on the
two die halves, is produced in fluid chambers which are formed from
a piston component and a piston-receiving component and are each
assigned to one of the die halves.
[0052] According to a further advantageous configuration, in each
case a plurality of adjacent fluid chambers on opposite sides of
the die are partially and/or jointly acted on by an identical or
different fluid chamber pressure.
[0053] According to a further advantageous configuration, the
hydrostatic fluid chamber pressure is controlled as a function of
the force which is exerted on the corresponding die half by the
fluid chamber.
[0054] According to a further preferred embodiment, in the die, two
forming chambers, which are arranged opposite one another and are
each formed by in each case one of the die halves with a forming
element arranged in the die parting plane between the two die
halves of the die, are simultaneously acted on by a hydrostatic
internal pressure.
[0055] The forming element is preferably arranged
mirror-symmetrically with respect to the die parting plane, and the
two forming chambers, in order to form two identical components
from workpieces which are in each case to be deformed, are
simultaneously acted on by an identical hydrostatic internal
pressure.
[0056] According to a further preferred embodiment, in a plurality
of dies which are arranged adjacent to one another perpendicular to
the respective die parting plane and have forming elements provided
in the respective die parting plane between the respective die
halves, a plurality of forming chambers, which are in each case
formed by in each case one of the die halves and one of the forming
elements, are simultaneously acted on by a hydrostatic internal
pressure.
[0057] According to a further aspect of the invention, in a
hydroforming process in which, in a hydroforming die arrangement in
which a plurality of dies, which are in each case divided into two
die halves along a die parting plane, are arranged in a stacked
arrangement in a direction perpendicular to the die parting
planes,
[0058] the die arrangement is equipped, between in each case two
adjacent die halves, with a workpiece which is to be deformed, so
that a pressure chamber is formed by the workpiece and one die half
and a deformation chamber is formed by the workpiece and other die
half;
[0059] each of the pressure chambers is acted on by a hydrostatic
internal pressure for shaping purposes at the corresponding
workpiece; and
[0060] when pressure is applied to the pressure chamber, a build-up
of pressure in the deformation chamber is prevented by means of at
least one fluid connection between the respectively adjacent die
half and the surroundings of the die arrangement.
[0061] Further configurations of the invention are to be found in
the following description and in the subclaims.
[0062] The invention is explained in more detail below on the basis
of exemplary embodiments illustrated in the appended figures, in
which:
[0063] FIG. 1 shows a diagrammatic side view, partially in section,
of a hydroforming device according to the invention;
[0064] FIG. 2 shows a cross-sectional view on section lines "A-A"
through the lower die carrier component of the hydroforming device
shown in FIG. 1;
[0065] FIGS. 3a and 3b show perspective views of the lower die
carrier component of the hydroforming device shown in FIG. 1;
and
[0066] FIGS. 4a-d show a plan view of various preferred embodiments
of a die carrier fixture which is used in the hydroforming device
shown in FIG. 1;
[0067] FIG. 5 shows a cross-sectional view through an alternative
embodiment of a die carrier component for the hydroforming device
according to the invention;
[0068] FIGS. 6 and 7 show diagrammatic illustrations explaining the
principle on which the hydroforming device according to the
invention is based without (FIG. 6) and with (FIG. 7) the
application of hydrostatic pressure;
[0069] FIG. 8 diagrammatically depicts an excerpt of a hydroforming
device in which a die in accordance with a further preferred
embodiment is provided;
[0070] FIG. 9 shows a diagrammatic cross-sectional view through an
assembly of two die carriers for a hydroforming device;
[0071] FIGS. 10a-d show various embodiments of hydroforming die
arrangements in accordance with a further aspect of the invention;
and
[0072] FIGS. 11a-c show various embodiments of die components for
use in one of the hydroforming die arrangements shown in FIG.
10.
[0073] In accordance with FIG. 1, a hydroforming device 1 according
to the invention comprises, in a preferred embodiment, a die
carrier 2, which comprises an upper die carrier component 3 and a
lower die carrier component 4. The die carrier 2 is held by a frame
(not shown here), which, in accordance with FIG. 9, may in a known
way be composed, for example, of horizontal connecting bars secured
to vertically arranged lamellae. The die carrier components 3, 4 of
the die carrier 2 are then guided in such a manner that they can
move in the vertical direction and be locked in place on the
vertical steel lamellae of the frame. In particular, the lower die
carrier component may be integrated in a clamping table (press
platen) of the hydroforming device 1.
[0074] The die carrier components 3, 4 each have an upper die
carrier fixture 3a and 4a, respectively, and a lower die carrier
fixture 3b and 4b, respectively. A die 5, which comprises an upper
die half 5a and a lower die half 5b, is mounted between the die
halves 3, 4. On its side which faces the upper die half 5a, the
lower die half 5b has an approximately centrally arranged recess,
so that when the die halves 5a, 5b bear areally against one
another, a forming chamber 6 is formed, in which a workpiece 7
which is to be deformed is arranged. The forming chamber 6 is
designed to match the desired shape of the deformed workpiece and
may also be provided at any other desired location between the die
halves 5a, 5b.
[0075] Furthermore, the die half 5a has a fluid passage which is in
communication with the forming chamber 6 and inside the die half 5a
leads laterally outwards (in accordance with the illustration in
FIG. 6). To process the workpiece 7, a preferably incompressible
fluid (e.g. water or oil) is fed to the forming chamber 6 via the
fluid passage by means of a hydraulic pump, with the result that an
internal high pressure Pi which is required for deformation of the
workpiece 7 is produced in the forming chamber 6.
[0076] In the process, the hydrostatic internal pressure Pi
produced in the interior of the forming chamber 6 produces an
outwardly directed force Fi=Pi.times.A, where A denotes the
projected surface area of the surrounding wall of the forming
chamber 6 onto the parting plane of the two die halves 5a, 5b,
acting on the two die halves 5a, 5b. To maintain a sealed, areal
contact between the die halves 5a, 5b, therefore, it is necessary
for a force Fa to act on the die halves 5a, 5b from the outside,
and the condition Fa.gtoreq.Fi has to be satisfied throughout the
entire deformation process.
[0077] In the hydroforming device 1 according to the invention,
fluid chambers 8 which are in each case provided in the upper and
lower die carrier components 3, 4 and the arrangement of which is
illustrated in more detail in the lower die carrier component 4 in
FIGS. 2 and 3a, b (the upper and lower die carrier components 3, 4
may be of identical construction) are used to produce the force Fa
which acts on the die halves 5a, 5b from the outside.
[0078] In accordance with FIG. 2 and FIGS. 3a, b, the upper die
carrier component 3 and the lower die carrier component 4 each
comprise a large number of fluid chambers 8 which are arranged in
matrix form and in the preferred embodiment illustrated are
arranged in such a way that in each case a fluid chamber 8 in the
lower die half 4 and a fluid chamber 8 in the upper die half 3 lie
opposite one another on a force line. In the exemplary embodiment
illustrated, each die carrier component 3, 4 in each case comprises
a 3.times.6 matrix of fluid chambers 8, although it is possible to
provide any desired number of fluid chambers 8. In this case,
however, the upper and lower die carrier components 3, 4 preferably
each comprises at least two adjacent fluid chambers 8, so that by
partial actuation of these chambers it is possible to increase the
flexibility with regard to the positioning of the die during
mounting of the hydroforming device.
[0079] In accordance with FIG. 1 (bottom right hand-part) as well
as FIGS. 2 and 3, each of the fluid chambers 8 is formed by the die
carrier fixtures 4a, 4b of the lower die half 4 having positively
and negatively shaped contours which correspond to one another and
substantially form a positive lock with one another. For this
purpose, in accordance with FIGS. 3a, b, the upper die carrier
fixture 4a has a piston-receiving component, and the lower die
carrier fixture 4b has a corresponding piston component.
[0080] The upper die carrier fixture 4a comprises, as a
piston-receiving component, a matrix-like arrangement (in the
exemplary embodiment illustrated a 3.times.6 matrix) comprising
substantially cylindrical cavities 13 which are open towards the
side facing the lower die carrier fixture 4b, whereas the lower die
carrier fixture 4b comprises, as piston component, a corresponding
matrix-like arrangement (in the exemplary embodiment illustrated
likewise a 3.times.6 matrix) of piston-like projections 14 which
correspond to the cavities 13. The piston-like projections 14 of
the lower die carrier fixture 4b are arranged at positions which
correspond to the cavities 13 of the upper die carrier fixture 4a,
so that the lower and upper die carrier components 4a, 4b engage
together in a substantially positively locking manner. The position
of the cavities 13 and of the piston-like projections 14 may also
be swapped over compared to the embodiment illustrated in FIGS. 3a,
3b, such that the cavities 13 are provided in the lower die carrier
fixture 4b of the lower die carrier component 4 (or in the upper
die carrier fixture 3a of the upper die carrier component 3).
[0081] Furthermore, the lower die carrier fixture 4b, to form fluid
passages 9, in accordance with FIG. 3b preferably has cylindrical
bores, which in the exemplary embodiment illustrated are in each
case arranged centrally in the corresponding piston-like
projections 14 and extend from that side of the corresponding
piston-like projection 14 which faces the corresponding cavity 13
to that side of the lower die carrier fixture 4b which is remote
from the cavity 13. However, the bores used to form the fluid
passages 9 may also be formed in a corresponding way in the upper
die carrier fixture 4a, i.e. leading from the outside to the
cavities 13.
[0082] To seal off the fluid chamber 8, each cavity 13 comprises a
groove 11 which, in the engaged position of the lower and upper die
carrier fixtures 4a, 4b, runs concentrically around the
corresponding piston-like projection 14 and in which a sealing ring
12 is accommodated to form a seal 10, so that the piston component
formed by one die carrier fixture 4b and the piston-receiving
component formed by the other die carrier fixture 4a form a sealing
unit which seals off each fluid chamber 8 in a pressure-tight
manner with respect to the outside.
[0083] As an alternative to the preferred embodiment illustrated,
it is possible for at least one pair comprising piston component
and associated piston-receiving component for forming the fluid
chambers 8 also to be formed by a die carrier component and the
associated die half. In this case, the die carrier component in
question can be of single-piece design and have piston-like
projections 14 corresponding to those shown in FIGS. 3a, 3b on that
side face of the die carrier component in question which faces the
respectively associated die half 5a, 5b, the corresponding cavities
13 then being provided in that side face of the corresponding die
half 5a or 5b which faces this die carrier component. This type of
design of the fluid chambers 8 can be selected on just one side of
the die or on both sides of the die. In this case, the cavities 13
may alternatively also be provided in the corresponding die carrier
component, and the piston-like projections 14 can be provided in
the corresponding die half 13.
[0084] Therefore, when the lower and upper die carrier fixtures 4a,
4b are in engagement with one another, a preferably incompressible
liquid can be fed via the fluid passages 9 to the space which
remains between the piston-like projections 14 and the
corresponding cavities 13, in order to apply a hydrostatic fluid
chamber pressure Pa to the fluid chambers formed there.
[0085] The piston-like projections 14 of the lower die carrier
fixture 4b and the corresponding cavities 13 of the upper die
carrier fixture 4a do not necessarily have to be of cylindrical
design, but rather may also adopt any desired surface-area shape.
By way of example, FIG. 4a illustrates an upper die carrier fixture
15 in which an inner partial region 15" which can be acted on by
hydrostatic pressure is divided from an outer partial region 15'
via a seal 15a of elongate, rounded surface-area form. FIGS. 4b, c
and d illustrate further possible embodiments of die carrier
fixtures 16, 17 and 18, partial regions 16", 17" and 18" which can
be acted on by hydrostatic pressure in each case being divided from
outer partial regions 16', 17' and 18' by seals 16a, 17a and 18a,
respectively, and the partial regions 16", 17" and 18" which can in
each case be acted on by hydrostatic pressure having an oval (FIG.
4b), hexagonal (FIG. 4c) and irregular (FIG. 4d) surface-area
form.
[0086] The hydrostatic fluid chamber pressure Pa required to
produce the required closure-holding force Fa is applied to the
fluid chambers 8 via the respective fluid passages 9 by a
preferably incompressible fluid, such as water or oil, being
supplied by means of a standard hydraulic pump or the like, it
being possible for the fluid chambers 8 to be acted on partially,
i.e. independently of one another, or alternatively jointly by the
same or a different fluid chamber pressure Pa. This allows flexible
positioning of the die halves 5a, 5b in the die carrier 2, since
the fluid chambers 8 can be actuated as a function of the position
of the die halves 5a, 5b in the die carrier 2, so that in
particular there is no need for the die 5 to be positioned
centrally. Furthermore, by partial actuation of the fluid chambers
8, it is even possible to produce a uniform distribution of force
for any position of the die 5 without, for example, a minimum size
of die carrier 2 being required for this purpose.
[0087] To ensure that the closure-holding force Fa exerted by the
die carrier components 3, 4 on the corresponding die halves 5a, 5b
by the hydraulic application to the fluid chambers 8 is always
greater than or equal to the force Fi which results from the
internal high pressure Pi and is active between the die halves 5a,
5b throughout the entire deformation process, it is particularly
advantageous for the forming chamber 6 and the fluid chambers 8 to
be acted on by a uniform pressure from the same pressure source
(e.g. hydraulic pump), since then the larger active surface area of
the die carrier fixtures 3b and 4a (relative to the wall
surrounding the forming chamber 6) then means that the
closure-holding force Fa is always greater than the force Fi acting
between the die halves 5a, 5b. However, it is also possible to use
separate pressure sources to apply pressure to the forming chamber
6 and the fluid chambers 8.
[0088] The hydraulic pump for applying pressure to the fluid
chambers 8 is preferably designed in such a way that the fluid
chamber pressure Pa produced in the fluid chambers 8 located
opposite one another on a force line is in each case identical.
This uses a relatively low structural outlay to ensure that, given
an identical application of hydrostatic pressure to the fluid
chambers 8, in each case the same hydrostatic fluid chamber
pressure is produced on both sides of the die 5.
[0089] However, deviations in the size of the active surface areas
of the die carrier fixtures 3b and 4a can lead to different forces
being exerted on the die 5, even though the hydrostatic fluid
chamber pressure Pa applied is identical on both sides of the die
5. To compensate for deviations of this nature, it is advantageous
to adjust the hydrostatic fluid chamber pressure Pa produced in the
corresponding fluid chambers 8 as a function of the force Fa which
is actually exerted on the die 5, a measure which can be achieved
by means of a simple control circuit (not shown), which as control
variable has the force Fa which is exerted on the die 5 by the
corresponding die carrier component 3 or 4. By means of a control
circuit of this type, it is also possible to compensate for any
pressure drop in the fluid chambers 8 which may occur during the
deformation process, since the fluid is tracked under control of
the fluid passages 9 and the pressure in the fluid chambers 8
and/or the force Fa exerted on the die 5 is kept constant. In this
case, the control circuit is preferably set in such a way that the
forces exerted on the corresponding die half 5a and 5b by the lower
die carrier fixture 3b of the upper die carrier component 3 and by
the upper die carrier fixture 4a of the lower die carrier component
4, respectively, are oppositely directed and of the same
magnitude.
[0090] The inventive way of designing the fluid chambers 8 by means
of the corresponding, substantially positively-locking cavities 13
and piston-like projections 14 which are present in the respective
die carrier fixtures 3a, 3b, 4a and 4b has the further effect that,
in the event of a relative movement between the respective die
carrier fixtures 3a and 3b and 4a and 4b, an integrated guide is
formed, ensuring a substantially defined direction of movement of
the die carrier fixtures 3a, 3b, 4a and 4b without further design
measures being required for this purpose, which likewise
contributes to maintaining the precision positive lock between the
die halves 5a, 5b which is required for a deformation process to
proceed without disruption.
[0091] FIG. 5 illustrates an alternative embodiment of a die
carrier component 19 with an upper die carrier fixture 19a and a
lower die carrier fixture 19b, in which the piston-like projections
of the lower die carrier fixture 19b and the cavities of the upper
die carrier fixture 19a are formed in such a way that, in the
engaged state of the die carrier fixtures 19a, 19b, a continuous
fluid chamber 20 is formed. The fluid chamber 20 can be uniformly
acted on from the outside by a preferably incompressible hydraulic
fluid via fluid passages arranged in each piston-like projection. A
seal 22 is in this case provided only in the outer edge region of
the die carrier component 19. The seal 22 may, for example, be
arranged in an encircling channel which surrounds the entire fluid
chamber 20. Consequently, the entire area between the upper and
lower die carrier components 19a, 19b surrounded by the seal 22 is
used as a hydraulically acting surface area. The interlocking
piston-like projections and cavities of the die carrier components
19a, 19b in this case in turn effect integrated guidance of the
relative movement between the two die carrier components 19a, 19b
throughout the application of hydraulic pressure.
[0092] The principle on which the hydroforming device according to
the invention and the corresponding process are based will now be
explained in more detail with reference to FIGS. 6 and 7.
[0093] For this purpose, the figures illustrate an excerpt 1' from
the hydroforming device 1 from FIG. 1 without (FIG. 6) and with
(FIG. 7) application of hydrostatic pressure, the elements of the
hydroforming device 1 which correspond to those shown in FIG. 1
being denoted by identical reference symbols. In particular, FIGS.
6 and 7 diagrammatically depict excerpts 3', 4' of the die carrier
components 3, 4 with corresponding excerpts 3a', 3b', 4a', 4b' from
the corresponding die carrier fixtures 3a, 3b, 4a, 4b, the excerpts
being selected in such a way that in each case one fluid chamber 8
with an associated fluid passage 9 is illustrated.
[0094] Once again, a die 5 with upper and lower die halves 5a, 5b
is illustrated between the excerpts 3', 4' of the die carrier
components 3, 4, with a fluid passage 23 which leads to the forming
chamber. 6 in the manner described above also being shown.
[0095] FIG. 7 diagrammatically depicts the effects of introducing a
hydrostatic internal pressure Pi into the forming chamber 6 and of
a hydrostatic fluid chamber pressure Pa into the fluid chambers 9.
The internal pressure Pi which is generated in the forming chamber
6 as a result of hydrostatic pressure being applied to the forming
chamber 6 via the fluid passage 23 is distributed uniformly over
the wall surrounding the forming chamber 6 and leads to an
outwardly directed force Fi on the die halves 5a, 5b, as
illustrated by the double arrows inside the forming chamber 6.
[0096] At the same time, the hydrostatic fluid chamber pressure Pa
which is produced inside the fluid chambers 8 by application of
hydrostatic pressure to the fluid passages 9 of the lower and upper
die carrier components 3, 4 is distributed uniformly over the walls
surrounding the fluid chambers 8, as likewise illustrated by double
arrows. In this context, it should be ensured that the force Fa
which corresponds to the hydrostatic fluid chamber pressure Pa is
always greater than or equal to the force Fi corresponding to the
hydrostatic internal pressure Pi throughout the entire deformation
process, so that the precision positive lock between the die halves
5a, 5b which is required continues to be ensured.
[0097] As is diagrammatically depicted in FIG. 7, elastic
deformations of the die carrier components 3', 4' occur only at
those side faces of the die carrier 2' which are remote from the
die 5 (this figure illustrates the position prior to the elastic
deformation by means of dashed lines) and therefore cannot be
transferred to the die 5 mounted between the die carrier components
3', 4'. Consequently, elastic deformations at the die 5 are
prevented, with the result that the precision positive lock between
the die halves 5a, 5b which is required in order to ensure that a
deformation process takes place without disruption continues to be
ensured.
[0098] If, in the event of an increase in the hydrostatic internal
pressure Pi in the forming chamber 6, an increase in the
hydrostatic fluid chamber pressure Pa should be required in order
to maintain the positive lock between the die halves 5a, 5b, the
dynamic volume compensation which takes place in the fluid chambers
8 leads to an increase in the elastic deformation on those side
faces of the die carrier components 3', 4' which are remote from
the die 5. The precision positive lock between the die halves 5a,
5b and therefore the pressure-tight seal throughout the entire
deformation process are consequently not adversely effected by the
elastic deformations of the die carrier components 3', 4', since
such deformations are instead dissipated to the outside, for
example into a frame of the hydroforming device 1'.
[0099] FIG. 8 diagrammatically depicts an excerpt from a
hydroforming device according to the invention in which a die 5' in
accordance with a further preferred embodiment is provided. The
other components, corresponding to the hydroforming device from
FIG. 6, are denoted by identical reference symbols.
[0100] In accordance with FIG. 8, the die 5' is designed in such a
way that a forming element 5'c is provided in the die parting plane
between the two die halves 5'a, 5'b of the die 5'. The forming
element 5'c may, for example, have the surface geometry shown in
FIG. 8 or alternatively any other desired surface geometry,
depending on the desired surface geometry of the workpiece which is
in each case to be deformed. The forming element 5'c in each case
forms a forming chamber 6a and 6b, which can be acted on by a
hydrostatic internal pressure Pi for shaping purposes at in each
case one workpiece which is to be deformed (not shown), with each
of the die halves 5'a, 5'b.
[0101] In order to achieve pressure-tight mounting of the forming
element 5'c between the die halves 5'a, 5'b, the die halves 5'a,
5'b, in accordance with the embodiment illustrated in FIG. 8,
preferably each have end-side shoulders facing the forming element
5'c, seals (not shown) in each case being provided between these
shoulders and the adjoining end sections of the forming element
5'c. In this case, the surrounding wall of each forming chamber 6a,
6b is formed by the end-side shoulders provided at the die halves
5'a, 5'b and the mutually facing side faces of the corresponding
die half 5'a, 5'b and the forming element 5'c.
[0102] In accordance with FIG. 8, both forming chambers 6a, 6b can
be acted on, in a similar manner to the embodiment illustrated in
FIG. 6, with a hydraulic internal pressure Pi via fluid passages
23a, 23b, which are connected, for example, to a hydraulic pump
(not shown).
[0103] When the embodiment illustrated in FIG. 8 is operating, the
opened hydroforming device is in each case fitted with a workpiece
which is to be deformed (not shown) between the forming element 5'c
and the associated die half 5'a or 5'b, whereupon the two die
halves 5'a, 5'b are brought into contact with the forming element
5'c at its end sections, leading to the formation of the forming
chambers 6a, 6b. Then, the deformation process is carried out by
application of hydraulic pressure to the forming chambers 6a, 6b
via the fluid passages 23a, 23b, in a similar manner to the
embodiment presented in conjunction with FIGS. 6 and 7. As has
already been described above, during this deformation process a
hydrostatic external pressure Pa which compensates for the
hydrostatic internal pressure Pi in the forming chambers 6a, 6b is
produced in the fluid chambers 8 by application of hydraulic
pressure to the fluid chambers 8, so that the required die-closing
force of the hydroforming device is ensured.
[0104] When the die is fitted with workpieces which are to be
deformed, each of the forming chambers 6a and 6b is divided into a
pressure chamber and a deformation chamber by the corresponding
workpiece. While the hydrostatic internal pressure Pi is applied to
the pressure chamber facing the corresponding fluid passage 23a,
23b, deformation takes place in the deformation chamber located on
the opposite side of the workpiece.
[0105] Moreover, the forming element 5'c preferably has outlet
openings (not shown), as will be explained in more detail in
connection with FIGS. 11a-c.
[0106] The forming element 5'c itself is preferably secured to the
frame, which also bears the die carrier 2.
[0107] To ensure that identical hydrostatic pressure ratios can be
produced in a simple way in the forming chambers 6a and 6b on both
sides of the forming element 5'c by the application of hydraulic
pressure, the forming element 5'c is of mirror-symmetrical
construction with regard to the die parting plane, so that forming
chambers 6a, 6b of corresponding geometry can be formed. In this
case, it is possible for both forming chambers 6a, 6b to be acted
on by an identical hydrostatic internal pressure Pi in a simple
way, so that two corresponding components are formed in a single
production step.
[0108] As can be seen from FIG. 9, with the hydroforming device
according to the invention it is also possible for the fluid
chambers of a plurality of die carrier components to be connected
next to one another in an assembly, so that devices with
considerable overall sizes of a length of many metres and high
closure-holding forces are obtained.
[0109] FIG. 9 illustrates the die carrier 2 from FIG. 1 assembled
with a further die carrier 24 of identical design and with die
carrier components 25, 26, each of the die carriers 2, 24 being
mounted in a frame 27 and 28, respectively. In this case, the lower
die carrier components 4 and 26 of the die carriers 2, 24,
respectively, are preferably in each case integrated in a clamping
table (press platen).
[0110] Each of the frames 27 and 28 is composed of horizontal
connecting bars 31 and 32 secured to vertical lamellae 29 and 30,
respectively, it being possible for the lamellae 29, 30 and the
connecting bars 31, 32 to be made, for example, from steel. The die
carrier components 3 and 4 and 25 and 26 of the die carriers 2 and
24, respectively, are once again guided on the vertical lamellae 29
and 30 in such a manner that they can move in the vertical
direction via guides (not shown) and can be locked in any desired
position and are otherwise constructed in accordance with the die
carrier components 3 and 4 of the embodiment illustrated in FIGS. 1
to 3.
[0111] The two frames 27 and 28 are positioned adjacent to one
another, in such a way that the die carrier components 3 and 25 and
4 and 26 received therein are in each case arranged adjacent to one
another. The two die carriers 2 and 24 form a functional unit to
the extent that they form a continuous die carrier with a
correspondingly enlarged horizontal cross-sectional area. The
result is a hydroforming device assembly comprising individual
hydroforming devices which form a functional unit.
[0112] Once again, a die 33 which is divided into die halves 33a,
33b is accommodated in the hydroforming device assembly comprising
the two die carriers 2 and 24 formed in this way, the die halves
33a, 33b forming a forming chamber 34 which can be acted on by the
hydrostatic internal pressure Pi via a fluid line 36 which leads to
a diagrammatically indicated hydraulic pump 35. In the exemplary
embodiment illustrated, the hydraulic pump 35 is likewise used to
apply the hydrostatic fluid chamber pressure Pa to the fluid
chambers 8. In the case of the assembly of die carriers 2, 24
illustrated in FIG. 9, the die 33, like the forming chamber 34
formed therein, can have an enlarged cross-sectional area parallel
to the horizontal connecting bars 31, 32 relative to the individual
die carrier 2, so that it is now also possible to process
correspondingly larger sheet-metal goemetries.
[0113] FIGS. 10a-10d illustrate various designs of die arrangements
40-70 in accordance with the invention in which a relatively large
number of workpieces can be deformed in a single production step,
so that the economics of the corresponding hydroforming device are
significantly improved.
[0114] In accordance with FIG. 10a, in a die arrangement 40 a
plurality of die components 41, 42, 45 and 46 are arranged in a
stacked arrangement in a direction which is perpendicular to the
die parting planes, in which arrangement in each case two adjacent
die components, such as for example the die components 41 and 45 or
45 and 46, can be considered die halves of one of a plurality of
dies of the die arrangement 40.
[0115] The die halves 41, 42, 45 and 46 are in this case designed
in such a way that die components 41, 42, which in a similar manner
to the embodiment illustrated in FIG. 6 and FIG. 7 each have a
fluid passage 43 and a seal 44 (which is only diagrammatically
depicted), are in each case arranged at the upper and lower ends of
the stacked arrangement 40. Between the die components 41, 42, die
components 45 which have a shaping action on both sides and die
components 46 which are provided with a supply of fluid on both
sides are arranged in an alternating sequence between the die
components 41, 42, each pair of adjacent die components 45, 46 in
each case forming a die. The die components 46 which are provided
with a fluid supply on both sides in each case have a fluid passage
47 which branches in a "T shape" in the direction towards the
adjacent die components 45, and also a diagrammatically depicted
seal 48.
[0116] The seals 44 and 48 can be of any desired configuration,
provided that it is ensured that, when the die arrangement 40 is
closed, the pressure chambers "A" are sealed off in a fluid-tight
manner. Alternatively, however, it is also possible to dispense
with the seals 44 and 48, in which case, when the die arrangement
40 is operating, any fluid which escapes from the pressure chambers
"A" is topped up via the fluid passages 43 and 47.
[0117] In accordance with FIG. 10a, the dies formed from the die
components or die halves 45, 46 are each equipped with a workpiece
49 which is to be deformed and is arranged in the associated die
parting plane, the workpieces 49 which are to be deformed being in
the form of planar metal sheets in accordance with FIG. 10a.
[0118] When workpieces 49 which are to be deformed are being
mounted in the die arrangement 40, with the die arrangement 40
closed, a pressure chamber "A", which can be acted on by a
hydrostatic internal pressure (Pi) for shaping purposes at the
workpiece 49 is in each case formed by each workpiece 49 and one
die half, e.g. the top die component 21, and a deformation chamber
"B" is formed by the workpiece 49 and the other die half, in this
example the die component 45, between in each case two adjacent die
halves 41 and 45, 45 and 46 or 45 and 42. Therefore, in the
embodiment illustrated in FIG. 10a, the sequence of pressure
chambers "A" and deformation chambers "B" can be schematically
described as " . . . A-B-B-A . . . ". The "T-shaped" branching of
the fluid passages 47 ensures that the respectively adjacent
pressure chambers "A" are acted on by an identical hydrostatic
internal pressure Pi.
[0119] With the die arrangement 40 closed, each deformation chamber
"B" is in fluid communication with the external surroundings of the
die arrangement 40 via outlet openings (not shown) in the
respectively adjacent die half. These outlet openings have the
effect that when pressure is applied to the pressure chamber "A", a
build-up of pressure in the adjacent deformation chamber "B" is
prevented. This facilitates the deformation of the workpiece 49,
since the movement of the workpiece 49 towards the deformation
chamber "B" which takes place during the deformation does not lead
to a build-up of a counter pressure despite the associated
reduction in volume of the deformation chamber "B".
[0120] The embodiment of a die arrangement 50 which is illustrated
in FIG. 10b, like the die arrangement 40 from FIG. 10a, is such
that in each case a die half which in each case forms a deformation
chamber "B" together the adjacent workpieces 49 and 59 and a die
half which in each case forms a pressure chamber "A" with the
adjacent workpieces 49 and 59 are arranged adjacent to one another
in an alternating sequence perpendicular to the die parting plane.
Moreover, the die arrangement 50 has the same sequence of pressure
chambers "A" and deformation chambers "B", namely " . . . A-B-B-A .
. . ". The embodiment of a die arrangement 50 which is illustrated
in FIG. 10b therefore substantially corresponds to the die
arrangement 40 shown in FIG. 11a, and consequently to this extent
the corresponding components are provided with corresponding
reference symbols.
[0121] Unlike in the case of the die arrangement 40, in the die
arrangement 50 the fluid-supplying die components 56 each have two
separate fluid passages 57a, 57b which branch off towards opposite
directions of the fluid-supplying die component 56, namely in each
case towards the adjacent workpieces 59. Therefore, the
respectively adjacent pressure chambers "A" can be acted on by
different hydrostatic pressures via the fluid passages 57a,
57b.
[0122] Of course, the die components or die halves 45 and 55 are
not necessarily of single-piece design, but rather may also be of
multi-piece design, in particular may for example be divided along
the die parting plane into two or more die component elements. A
division into separate die component elements of this type has the
advantage that the abovementioned outlet openings (not shown) in
the die components 45 and 55 for preventing a build-up of pressure
in the deformation chambers "B" can be produced more easily in
manufacturing technology terms, since for this purpose, by way of
example, outlet passages which are to be provided perpendicular to
the die parting plane only have to be of correspondingly reduced
length.
[0123] Accordingly, it is also possible for the two die halves
which are located between two forming elements and are in each case
assigned to the adjacent forming elements to be designed as
separate components or as a single piece.
[0124] Exemplary embodiments of die components 100, 200 and 300 are
illustrated in FIGS. 11a-c.
[0125] In accordance with FIG. 11a, these outlet openings may, for
example, comprise an outlet passage 101 extending parallel to the
die parting plane and a plurality of outlet passages 102 arranged
perpendicular thereto. By means of outlet passages 101, 102 of this
type, it is possible to ensure that, when the die component 100
which has been fitted in a hydroforming device according to the
invention is provided with a workpiece, a build-up of pressure in
the region between the workpiece and the adjoining die half is
prevented if the pressure chamber formed on the opposite side of
the workpiece is acted on by the hydrostatic internal pressure.
Depending on the specific requirements, in particular depending on
the geometry and/or dimensions of the workpieces which are to be
deformed, the outlet passages 101, 102 may have different
dimensions and/or geometries; by way of example, outlet passages
101, 102 in the form of cylindrical bores with a diameter in the
range from 0.1 mm to 1 mm may be suitable.
[0126] Furthermore, FIG. 11b illustrates an embodiment of a die
component 200 which only has a shaping action on one side, i.e. has
a shaping pattern for deformation of a workpiece in the
hydroforming device on only one side. Accordingly, an outlet
passage 201 extending parallel to the die parting plane is
provided, from which outlet passage 201 a plurality of outlet
passages 202, arranged perpendicular thereto, extend towards the
shaping side. To form a fluid-supplying side, a fluid passage 203
extends towards the opposite side of the die component 200 from
this shaping side, a seal 204 also being provided, in a similar
manner to in the embodiment described above.
[0127] FIG. 11c shows an embodiment of a die component 300 which is
divided in two along the die parting plane, i.e. is of two-piece
design. Otherwise, the die component 300 is designed to have a
shaping action on both sides, in a similar manner to the die
component 101 shown in FIG. 11a, i.e. it has in particular outlet
passages 301, 302 which extend toward the two opposite shaping
sides. The two-piece embodiment of the die component 300 is
advantageous in particular from a manufacturing technology
perspective, since the outlet passages 301, 302 running
perpendicular to the die parting plane have a length which is
shorter, in particular only half as great, as the corresponding
outlet passages 102 of the die component 100 have to be.
[0128] In accordance with the die arrangement 60 shown in FIG. 10c,
an upper die component 61 which has a shaping action on one side
towards the lower die component 62 and a lower die component 62 are
provided, the lower die component 62 having a seal 63 and a fluid
passage 64 in the direction of the upper die component 61. A
plurality of, in the exemplary embodiment a total of five,
identical die components 65 are arranged in a stacked form, in a
direction perpendicular to the die parting plane, between the die
components 61, 62. Each of the die components 65 has a fluid
passage 66 extending towards the upper die component and a seal 67
which is likewise arranged in this direction. The die arrangement
60 is likewise fitted with workpieces 68 arranged in the
corresponding die parting planes, so that in each case a pressure
chamber "A" and a deformation chamber "B" are formed in an
alternating sequence perpendicular to the die parting plane between
the workpieces 68 and the die components 61 and 65, 65 and 65 and
65 and 62. Therefore, in the die arrangement 60 illustrated in FIG.
10c, the sequence of pressure chambers "A" and deformation chambers
"B" can be schematically presented as " . . . A-B-A-B . . . ".
[0129] As can be seen from the embodiment of a die arrangement 70
illustrated in FIG. 10d, it is also possible for combinations of
die components to be arranged in a stacked arrangement in a
direction perpendicular to the die parting plane. The die
arrangement 70 has an upper die component 71 and a lower die
component 72.
[0130] The die components 71, 72 each have a fluid passage 73 and
75, respectively, and a seal 74 and 76, respectively, in a mutually
facing direction. Starting from the upper die component 71, the
following parts are arranged between the die components 71, 72, in
succession in a stacking direction perpendicular to the die parting
plane:
[0131] a die component 77 which has a shaping action on both
sides,
[0132] a die component 78 which has a fluid passage 79 extending
towards this die component 77 and a seal 80 which likewise faces in
this direction, and which is designed to have a shaping action on
one side, specifically the side facing away from this
direction,
[0133] a die component 81 with a fluid passage 82 which branches in
a T-shape and a seal 83 on both sides,
[0134] a further die component 77 which has a shaping action on
both sides, a further die component 78 with fluid passage 79 and
seal 80 which has a shaping action on one side,
[0135] a further die component 84 with fluid passages 84a, 84b
which are formed separately from one another and extend on both
sides, and a seal 85 on both sides, and
[0136] a further die component 77 which has a shaping action on
both sides.
[0137] The stacked arrangement is in this case selected in such a
way that, when the die arrangement 70 is fitted with workpieces 86,
once again a pressure chamber "A" and a deformation chamber "B" are
formed on opposite sides of the workpiece. Provided that this
sequence is ensured, the stacked sequence of pressure chambers "A"
and deformation chambers "B" in the die arrangement 70 can
otherwise be described as irregular, specifically, in the exemplary
embodiment illustrated, as "A-B-B-A-B-A-A-B-B-A-B-A-A-B-B-A".
[0138] In all the die arrangements 40-70 which have been
illustrated, it is possible for the die components which have a
shaping action on one side and/or the die components which have a
shaping action on both sides, on the side which is in each case
used for shaping purposes, to have any desired shaping structure on
the surface in question.
[0139] The individual forming chambers and/or the fluid passages
connected thereto can be acted on by the required hydrostatic
internal pressure from various pressure sources or from a single
pressure source (e.g. a hydraulic pump). Furthermore, these forming
chambers as well as the fluid chambers 8 which are provided for the
purpose of producing the required closure-holding force Fa in the
die carrier 2 can be acted on by a uniform pressure from the same
pressure source, which in turn ensures that, on account of the
larger active surface areas of the die carrier fixtures 3b, 3b' and
4a, 4a', the closure-holding force Fa is always greater than the
force Fi which is active inside the forming chambers. However, it
is also possible to use separate pressure sources to apply the
pressure to the forming chambers and the fluid chambers 8.
[0140] List of Reference Symbols
[0141] 1 Hydroforming device
[0142] 2 Die carrier
[0143] 3 Die carrier component
[0144] 4 Die carrier component
[0145] 3a, 4a Die carrier fixture
[0146] 3b, 4b Die carrier fixture
[0147] 5, 5' Die
[0148] 5a, 5'a Die half
[0149] 5b, 5'b Die half
[0150] 5'c Forming element
[0151] 6, 6a, 6b Forming chamber
[0152] 7 Workpiece
[0153] 8 Fluid chamber
[0154] 9 Fluid passage
[0155] 10 Seal
[0156] 11 Groove
[0157] 12 Sealing ring
[0158] 13 Cavities
[0159] 14 Piston-like projection
[0160] 15 Die carrier fixture
[0161] 16 Die carrier fixture
[0162] 17 Die carrier fixture
[0163] 18 Die carrier fixture
[0164] 15', 18' Partial region which can be acted on by hydraulic
means
[0165] 15"-18" Outer partial region
[0166] 15a-18a Seals
[0167] 19 Die carrier fixture
[0168] 20 Fluid chamber
[0169] 21 Fluid passage
[0170] 22 Seal
[0171] 23, 23a, 23b Fluid passage
[0172] 24 Die carrier
[0173] 25 Die carrier component
[0174] 26 Die carrier component
[0175] 27 Frame
[0176] 28 Frame
[0177] 29 Vertical lamellae
[0178] 30 Vertical lamellae
[0179] 31 Horizontal connecting bars
[0180] 32 Horizontal connecting bars
[0181] 33 Die
[0182] 33a, 33b Die halves
[0183] 34 Forming chamber
[0184] 35 Hydraulic pump
[0185] 36 Fluid line
[0186] 40 Die arrangement
[0187] 41 Die component
[0188] 42 Die component
[0189] 43 Fluid passage
[0190] 44 Seal
[0191] 45 Die component
[0192] 46 Die component
[0193] 47 Fluid passage
[0194] 48 Seal
[0195] 49 Workpiece
[0196] "A" Pressure chamber
[0197] "B" Deformation chamber
[0198] 50 Die arrangement
[0199] 51 Die component
[0200] 52 Die component
[0201] 53 Fluid passage
[0202] 54 Fluid passage
[0203] 55 Die component
[0204] 56 Die component
[0205] 57a, 57b Fluid passages
[0206] 58 Seal
[0207] 59 Workpiece
[0208] 60 Die arrangement
[0209] 61 Die component
[0210] 62 Die component
[0211] 63 Seal
[0212] 64 Fluid passage
[0213] 65 Die component
[0214] 66 Fluid passage
[0215] 67 Seal
[0216] 68 Workpiece
[0217] 70 Die arrangement
[0218] 71 Die component
[0219] 72 Die component
[0220] 73 Fluid passage
[0221] 74 Seal
[0222] 75 Fluid passage
[0223] 76 Seal
[0224] 77 Die component
[0225] 78 Die component
[0226] 79 Fluid passage
[0227] 80 Seal
[0228] 81 Die component
[0229] 82 Fluid passage
[0230] 83 Seal
[0231] 84 Die component
[0232] 85 Seal
[0233] 86 Workpiece
[0234] 100 Die component
[0235] 101 Outlet passage
[0236] 102 Outlet passage
[0237] 200 Die component
[0238] 201 Outlet passage
[0239] 202 Outlet passage
[0240] 203 Fluid passage
[0241] 204 Seal
[0242] 300 Die component
[0243] 301 Outlet passage
[0244] 302 Outlet passage
* * * * *