Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Hydroforming device and hydroforming process and
hydroforming die arrangement
The invention relates to a hydroforming device and a
hydroforming process and to a hydroforming die arrangement.
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.
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,
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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.
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.
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
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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.
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.
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.
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
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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.
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.
This object is achieved in accordance with the features
given in the independent claims.
To this end, a hydroforming device comprises
- 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,
- a die carrier, which for each die half has at least
one die carrier component assigned to this die half,
- 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
- means being provided for producing a hydrostatic
fluid chamber pressure, which is at least equal to
the hydrostatic internal pressure, in each of the
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fluid chambers, which fluid chamber pressure,
compensating for the hydrostatic internal pressure,
exerts a die-closing force on the two die halves.
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.
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.
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
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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.
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.
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.
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.
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.
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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.
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.
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.
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.
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
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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.
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.
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.
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.
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
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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.
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.
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.
However, the forming element may also be surrounded in a
pressure-tight manner by the die halves, and in particular
may also be maunted 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.
According to a further preferred embodiment, a plurality of
dies with a forming element provided in the die parting
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plane between the respective die halves are arranged
adjacent to one another in a direction perpendicular to the
die parting plane.
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.
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.
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,
- 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
- 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
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chamber, pressure is prevented from building up in
the deformation chamber.
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.
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.
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.
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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.
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.
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.
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.
According to a further preferred embodiment, at least one of
the die halves which in each case forms a pressure chamber
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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.
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.
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.
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.
According to a further advantageous configuration, in each
case a plurality of adjacent fluid chambers on opposite
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sides of the die are partially and/or jointly acted on by an
identical or different fluid chamber pressure.
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.
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.
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.
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.
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,
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- 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;
- each of the pressure chambers is acted on by a
hydrostatic internal pressure for shaping purposes
at the corresponding workpiece; and
- 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.
Further configurations of the invention are to be found in
the following description and in the subclairns.
The invention is explained in more detail below on the basis
of exemplary embodiments illustrated in the appended
figures, in which:
Figure 1 shows a diagrammatic side view, partially in
section, of a hydroforming device according to the
invention
Figure 2 shows a cross-sectional view on section lines "A-A"
through the lower die carrier component of the hydroforming
device shown in Figure 1;
Figures 3a and 3b show perspective views of the lower die
carrier component of the hydroforming device shown in Figure
1; and
Figures 4a-d show a plan view of various preferred
embodiments of a die carrier fixture which is used in the
hydroforming device shown in Figure 1;
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Figure 5 shows a cross-sectional view through an alternative
embodiment of a die carrier component for the hydroforming
device according to the invention;
Figures 6 and 7 show diagrammatic illustrations explaining
the principle on which the hydroforming device according to
the invention is based without (Figure 6) and with (Figure
7) the application of hydrostatic pressure;
Fig. 8 diagrammatically depicts an excerpt of a hydroforming
device in which a die in accordance with a further preferred
embodiment is provided;
Fig. 9 shows a diagrammatic cross-sectional view through an
assembly of two die carriers for a hydroforming device;
Figs. l0a-d show various embodiments of hydroforming die
arrangements in accordance with a further aspect of the
invention; and
Figs. lla-c show various embodiments of die components for
use in one of the hydroforming die arrangements shown in
Fig. 10.
In accordance with Figure 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.
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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, 9. 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.
Furthermore, the die half 5a has a fluid passage which is in
communication with the farming 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.
In the process, the hydrostatic internal pressure Pi
produced in the interior of the forming chamber 6 produces
an outwardly directed force Fi = Pi x 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 Sa,
5b, therefore, it is necessary for a force Fa to act on the
die halves 5a, 5b from the outside, and the condition Fa >_ Fi
has to be satisfied tf~roughout the entire deformation
process.
In the hydroforming device 1 according to the invention,
fluid chambers 8 which are in each case provided in the
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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 Figures 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.
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 3x6
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.
In accordance with Figure 1 (bottom right hand-part) as well
as Figures 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
Figures 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.
The upper die carrier fixture 4a comprises, as a
piston-receiving component, a matrix-like arrangement (in
the exemplary embodiment illustrated a 3x6 matrix)
18
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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 3x6
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).
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.
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
CA 02440722 2003-09-12
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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.
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.
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.
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, Figure 4a illustrates
an upper die carrier fixture 15 in which an inner partial
CA 02440722 2003-09-12
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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. Figures 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 (Figure 4b),
hexagonal (Figure 4c) and irregular (Figure 4d) surface-area
form.
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.
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
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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.
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.
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
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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.
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.
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
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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.
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 Figures 6
and 7.
For this purpose, the figures illustrate an excerpt 1' from
the hydroforming device 1 from Figure 1 without (Figure 6)
and with (Figure 7) application of hydrostatic pressure, the
elements of the hydroforming device 1 which correspond to
those shown in Figure 1 being denoted by identical reference
symbols. In particular, Figures 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.
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.
Figure 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
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- 25 -
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.
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.
As is diagrammatically depicted in Figure 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.
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
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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'.
Figure 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. 5, are denoted by identical
reference symbols.
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.
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
CA 02440722 2003-09-12
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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.
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).
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.
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.
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Moreover, the forming element 5'c preferably has outlet
openings (not shown), as will be explained in more detail in
connection with Figs. lla-c.
The forming element 5'c itself is preferably secured to the
frame, which also bears the die carrier 2.
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.
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.
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).
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,
CA 02440722 2003-09-12
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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.
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
ad j acent 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.
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.
Figs. l0a-lOd illustrate various designs of die arrangements
40-70 in accordance with the invention in which a relatively
CA 02440722 2003-09-12
r t . 30 -
large number of workpieces can be deformed in a single
production step, so that the economics of the corresponding
hydroforming device are significantly improved.
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.
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.
The seals 44 and 48 can be of any desired configuration,
provided that it is ensured that, when the die arrangement
is closed, the pressure chambers "A" are sealed off in a
fluid-tight manner. Alternatively, however, it is also
35 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.
CA 02440722 2003-09-12
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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.
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.
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".
CA 02440722 2003-09-12
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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. lOb therefore substantially corresponds to the die
arrangement 40 shown in Fig. 10a, and consequently to this
extent the corresponding components are provided with
corresponding reference symbols.
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.
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.
CA 02440722 2003-09-12
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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.
Exemplary embodiments of die components 100, 200 and 300 are
illustrated in Figs. lla-c.
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.
Furthermore, Fig. llb 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
CA 02440722 2003-09-12
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also being provided, in a similar manner to in the
embodiment described above.
Fig. llc 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.
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 hav ing
a seal 63 and a fluid passage 64 in the direction of the
upper die component 61. A plurality of, in the exempl ary
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 seque nce
of pressure chambers "A" and deformation chambers "B" can be
schematically presented as "...A-B-A-B...".
CA 02440722 2003-09-12
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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.
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:
- a die component 77 which has a shaping action on
both sides,
- 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,
- a die component 81 with a fluid passage 82 which
branches in a T-shape and a seal 83 on both sides,
- 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,
- 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
- a further die component 77 which has a shaping
action on both sides.
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
CA 02440722 2003-09-12
' - 36 -
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".
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.
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.
CA 02440722 2003-09-12
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List of Reference Symbols
1 Hydroforming device
2 Die carrier
3 Die carrier component
4 Die carrier component
3a, 4a Die carrier fixture
3b, 4b Die carrier fixture
5, 5' Die
5a, 5'a Die half
5b, 5' b Die half
5'c Forming element
6, 6a, 6b Forming chamber
7 Workpiece
8 Fluid chamber
9 Fluid passage
10 Seal
11 Groove
12 Sealing ring
13 Cavities
14 Piston-like projection
15 Die carrier fixture
16 Die carrier fixture
17 Die carrier fixture
18 Die carrier fixture
15', 18' Partial region which can be acted on by
hydraulic means
15" -18" Outer partial region
15a-18a Seals
19 Die carrier fixture
20 Fluid chamber
21 Fluid passage
22 Seal
23, 23a, 23b Fluid passage
24 Die carrier
25 Die carrier component
26 Die carrier component
27 Frame
46
CA 02440722 2003-09-12
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28 Frame
29 Vertical lamellae
30 Vertical lamellae
31 Horizontal connecting bars
32 Horizontal connecting bars
33 Die
33a, 33b Die halves
34 Forming chamber
35 Hydraulic pump
3f Fluid line
40 Die arrangement
41 Die component
42 Die component
43 Fluid passage
44 Seal
45 Die component
46 Die component
47 Fluid passage
48 Seal
49 Workpiece
"A" Pressure chamber
"B" Deformation chamber
50 Die arrangement
51 Die component
52 Die component
53 Fluid passage
54 Fluid passage
55 Die component
56 Die component
57a, 57b Fluid passages
58 Seal
59 Workpiece
60 Die arrangement
61 Die component
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62 Die component
63 Seal
64 Fluid passage
65 Die component
66 Fluid passage
67 Seal
68 Workpiece
70 Die arrangement
71 Die component
72 Die component
73 Fluid passage
74 Seal
75 Fluid passage
76 Seal
77 Die component
78 Die component
79 Fluid passage
80 Seal
81 Die component
82 Fluid passage
83 Seal
84 Die component
85 Seal
86 Workpiece
100 Die component
101 Outlet passage
102 Outlet passage
200 Die component
201 Outlet passage
202 Outlet passage
203 Fluid passage
204 Seal
300 Die component
301 Outlet passage
302 Outlet passage
48
