Note: Descriptions are shown in the official language in which they were submitted.
CA 02544242 2006-04-28
r P804094/WO/1
- 1 -
Tool and method for the internal high pressure forming of
a hollow section
The invention relates to a tool for forming a hollow
section by the internal high pressure forming process
according to the preamble-of claim 1 and to an associated
method according to the preamble of claim 8.
DE 197 33 477 A1 discloses a tool and a method for
forming a hollow section of the type mentioned at the
beginning. The forming tool has at least one embossing
punch which is displaceable transversely to the
longitudinal extent of the hollow section and which makes
an embossment on the outside of the hollow section after
the forming operation. In addition, at least one
perforating punch is arranged in the embossing punch
coaxially thereto, this perforating punch perforating the
hollow section after the embossing operation.
US 6,470,546 Bl discloses a further tool and a further
method for forming a hollow section, in which the forming
tool has a wall section at which a side facing the hollow
section is designed as a shaping die wall and which is
displaceable transversely to the longitudinal extent of
the hollow section. This wall section contains an
embossing punch, by means of which a hole can be embossed
in the hollow section after the forming operation.
DE 197 24 037 Al discloses a tool for the internal high
pressure forming of a hollow body and for cutting a
flange on this hollow body. To this end, the tool has a
cutting device which runs parallel to the longitudinal
extent of the hollow section and has a cutting edge which
is displaceable in the transverse direction of the hollow
AMENDED SHEET
CA 02544242 2006-04-28
P804094/WO/1
- 2 -
section. At the same time, a side of the cutting device
facing the hollow section forms a shaping die wall,
against which the hollow section bears during the
internal high pressure forming.
DE 100 30 882 Al discloses a further method for cutting a
hollow body produced according to the internal high
pressure forming process.
The present invention deals with the problem of
specifying a method for internal high pressure forming
with which in particular a rationalized production
process can be achieved. Furthermore, a tool suitable for
the abovementioned method is to be provided with which in
particular various method steps can be combined.
This problem is solved according to the invention by the
subject matters of the independent claims. Advantageous
embodiments are the subject matter of the dependent
claims.
The invention is based on the general idea of designing a
tool for forming the hollow section according to the
internal high pressure forming process and also for
making an embossment on the outside of the hollow section
and additionally for perforating the hollow section and
furthermore also for cutting a flange on the hollow
section. To this end, the tool has at least one embossing
punch displaceable transversely to the longitudinal
extent of the hollow section and also at least one
perforating punch arranged coaxially in the embossing
punch.
In addition, according to the invention, the embossing
AMENDED SHEET
CA 02544242 2006-04-28
P804094/WO/1
- 3 -
punch is arranged in such a way that it crosses and
passes through a cutting device of the tool in a
corresponding opening during the embossing operation,
this cutting device extending parallel to the
longitudinal extent of the hollow section and being
displaceable in the transverse direction of the hollow
section. In particular when a side of the cutting device
facing the hollow section is designed as a shaping die
wall, against which the hollow section bears at least
during the internal high pressure forming, this results
in simplified kinematics for the tool, and these
kinematics can be used for shorter cycle times.
The solution according to the invention therefore offers
the advantage that three method steps, namely the
internal high pressure forming, the embossing and the
perforating, can be carried out in a single tool, so that
in particular no tool change is necessary, thereby
resulting in a rationalized production sequence. The
solution according to the invention therefore helps to
streamline the production process and thus achieve time
or cost advantages. In addition, the solution according
to the invention ensures that the holes produced by the
perforating punch have a very high accuracy of position
and shape relative to the embossing and thus the quality
of the hollow sections produced can be markedly
increased. Compared with previous production methods in
which the embossments andJor the holes are subsequently
made in the already finish-shaped hollow sections,
subsequent deformation and thus dimensional inaccuracy of
the hollow section can now be avoided. Even for the case
where the embossing is effected after the production of
the holes, the solution according to the invention offers
the great advantage that the embossing punch does not
AMENDED SHEET
CA 02544242 2006-04-28
P804094/WO/1
- 4 -
adversely affect the dimensional accuracy, that is to say
the position and shape of the holes produced, by the
embossing. In principle, with the tool according to the
invention, first perforating and then embossing can be
carried out after the internal high pressure forming, or
m ce versa.
According to another development of the solution
according to the invention, the tool has a bottom die and
a top die which are displaceable relative to one another.
The embossing punch may be expediently mounted in a
displaceable manner on or in one of these dies. In this
way, a defined relative position prevails between the
embossing punch and the respective die, a factor which
improves the accuracy of the production process. In
addition, the cutting device may either be integrated in
one of the dies, the cutting edge then forming an
integral part of the respective die, or else the cutting
device may be designed as a separate component and be
fastened to one of the dies in a fixed position, or the
cutting device may be arranged on one of the dies in such
a way as to be adjustable in stroke. The variants
described of the arrangement of the cutting device on the
tool already shows the wide range of possibilities that
the invention opens up with regard to process-optimized
arrangement variants of the cutting devices. For example,
a design of the cutting device as a separate component
which is fastened to one of the dies in a fixed position
offers the advantage that, after a relatively large
number of cutting operations, the cutting device or the
cutting edge can be exchanged simply and quickly and thus
the maintenance cost of the tool can be reduced. If the
cutting device is arranged on one of the dies in such a
way as to be adjustable in stroke, a markedly smoother
AMENDED SHEET
CA 02544242 2006-04-28
- 5 -
mode of operation of the tool is obtained on account of the
lower weight, to be moved, of the cutting device compared
with the top or bottom die. On the other hand, the
integration of the cutting device in one of the dies or the
design of the cutting edge as an integral component offers
the advantage that an especially precise and powerful
cutting operation can be achieved as a result. Due to the
many possible ways of arranging the cutting devices on one
of the dies, the solution according to the invention
therefore makes it possible to react in a flexible manner
to the most varied requirements with regard to the material
and/or workpiece to be processed.
According to a preferred embodiment of the invention; at
least one hold-down, which fixes the flange of the hollow
section at least during the cutting operation, is provided
in the region of the cutting edge. Such a hold-down, in
combination with a positioning device which, before and
during the cutting and forming operation, presses
the hollow section against that side of the cutting device
which faces the hollow section, ensures that the
hollow section is held in a fixed position during
the cutting operation and thus ensures an exact cut of
high quality. In addition, the hold-down provides
for always identical positioning of the hollow section
inside the tool, as a result of which a high reproducible
dimensional accuracy and thus uniformity of the hollow
CA 02544242 2006-04-28
P804094/WO/1
- 5a -
sections to be produced is achieved.
Further important features and advantages of the
invention follow from the subclaims, from the drawings
and from associated descriptions of the figures with
respect to the drawings.
It goes without saying that the abovementioned features
and the features still to be explained below can be used
not only in the respectively specified combination but
also in other combinations or on their own without
departing from the scope of the present invention.
Preferred exemplary embodiments of the invention are
shown in the drawings and are described in more detail
below, identical reference numerals relating to identical
or functionally identical or similar components.
In the drawing:
fig. 1 shows a cross section through a tool according to
the invention with inserted hollow section, before
the cutting or forming operation,
fig. 2 shows an illustration as in fig. l, but with
actuated positioning device,
fig. 3 shows a cross section through the tool according
to the invention after the cutting and forming
operation and before the embossing or perforating
operation,
fig. 4 shows an illustration as in fig. 3 but with
embossing and perforating operation completed,
CA 02544242 2006-04-28
P804099/WO/1
- 6 -
fig. 5 shows a cross section through the tool with opened
top and bottom dies.
According to fig. l, a tool 1 according to the invention,
which is designed for cutting a flange 3 on a -hollow
section 2, has a bottom die 7 and a top die 8, which are
displaceable relative to one another. Here, according to
the illustrations in figs 1 to 5, the top die 8 is
displaceable toward the bottom die 7. In general,
however, it is also conceivable for the bottom die 7 to
be displaceable toward the top die 8 or for both to be
mounted in an displaceable manner.
To cut the flange 3 on the hollow section 2, the tool 1
has at least one cutting device 4, which runs parallel to
the longitudinal extent, has a cutting edge 5 and is
displaceable relative to the hollow section in the
transverse direction of the hollow section 2. In this
case, the cutting device 4 may be integrated in one of
the dies 7 or 8, the cutting edge 5 then forming an
integral part of the respective die 7 or 8.
Alternatively, the cutting device 4 may also be designed
as a separate component which is fastened on one of the
two dies 7 or 8~ here the top die 8, in a fixed position.
As a third variant, the cutting device 4 may be arranged
on one of the dies 7 or 8 in such a way as to be
adjustable in_stroke relative to the respective die 7, 8.
In the case of a cutting device 4 integrated in one of
the dies 7 or 8, the flange 3 can be cut off or severed
in an especially powerful and thus precise manner, as a
result of which the quality of a subsequent end product
can be markedly increased. On the other hand, the
CA 02544242 2006-04-28
P804094/WO/1
embodiment of the cutting device 4 as a separate
component, which is fastened on one of the two dies 7 or
8 in a fixed position, offers the great advantage that
the cutting edge 5, which may be designed, for example,
as a parting blade, can be exchanged in a simple and
cost-effective manner. Hardened metals, fo-r example,
which have an especially long service life, are suitable
as cutting edge 5. The third embodiment variant, in which
the cutting device 4 together with the cutting edge 5 is
arranged in a displaceable manner on one of the dies 7 or
8, offers the advantage that the cutting operation can be
isolated from a closing operation of the tool l, i.e.
from a movement of the top die 8 and the bottom die 7
toward one another.
According to fig. l, a shaping die wall 17 is formed on a
side 6 of the cutting device 4 facing the hollow section
2, the hollow section 2 bearing against this die wall 17
after the cutting operation and during the subsequent
internal high pressure forming. In this case, according
to the illustrations in figs 1 to 5, the tool 1 is
designed in cross section, for example, in such a way
that the top die 8 and the bottom die 7 each have an L-
shaped form, and these L-shaped forms, when they meet,
form a cavity 14 in which the hollow section 2 can be
shaped by internal high pressure. This cavity 14 is in
this case defined at least on one side by the die wall 17
of the cutting device 4.
According to fig. 1 and fig. 2, a positioning device 9 is
provided on the tool l, which positioning device 9,
before the cutting and forming operation, presses the
hollow section 2 against that side 6 of the cutting
device 4 which faces the hollow section 2, that is to say
CA 02544242 2006-04-28
P804094/WO/1
g _
against the die wall 17 of the cutting device 4. In this
case, the positioning device 9 may be designed, for
example, as a punch which is acted upon by spring force
or hydraulic pressure and which is arranged so as to be
extendable and retractable in one of the dies 7 or 8,
here in the bottom die 7. According to fig. 2, the
positioning device 9 is actuated and, in the actuated
state, presses the hollow section 2 against the side 6 of
the cutting device 4.
Provided in the region of the cutting edge 5 is at least
one hold-down 10 which fixes the flange 3 of the hollow
section 2 at least during the cutting operation.
According to the illustrations in figs 3 and 4, a second
hold-down 10' can also be provided by a stepped design of
the cutting edge 5, this second hold-down 10' fixing the
hollow section 2 in position during the forming operation
or embossing and perforating operation following the
cutting operation.
According to the illustration in fig. 3, an embossing
punch 11 is provided which is displaceable transversely
to the longitudinal extent of the hollow section 2 and
provides an embossment (cf. fig. 4) on the outside of the
hollow section 2 after the forming operation. In this
case, the embossing punch 11 can preferably be actuated
hydraulically and acts during the embossing against an
internal high pressure pi which prevails inside the hollow
section 2. The embossing punch 11 may expediently be
mounted in a displaceable manner on or in one of the dies
8 and be arranged in such a way that it crosses and
passes through the cutting device 4 in a corresponding
opening 12 after the cutting operation and during the
embossing operation. During the cutting operation, the
CA 02544242 2006-04-28
P804094/WO/1
- 9 -
embossing punch 11 moves with the cutting device 4 or the
top die 8 transversely to its embossing direction. It is
conceivable in this case, for example, for an embossing
surface 15 formed on the end face of the embossing punch
11 to be part of the shaping die wall 17 of the cutting
device 4.
As mentioned above, the embossing of the hollow section 2
is effected against the internal high pressure pi and
after the cutting operation, so that, with the embossing,
an additional but facultative processing step can be
carried out with the tool 1.
According to figs 3 and 4, at least one perforating punch
13, which perforates the hollow section 2 after the
completed embossing operation, is provided in the
embossing punch 11 and coaxially thereto. An embossing
direction of the embossing punch 11 is in this case
parallel to a direction of movement of the perforating
punch 13. Due to the embossing punch 13, a further
likewise facultative processing step, namely the
perforating of the hollow section 2, is integrated in the
tool 1, as a result of which the production process can
be additionally rationalized.
In addition, the embossing or the perforating against the
internal high pressure pi offers the advantage that
embossments produced beforehand are not adversely
affected by the perforating or perforations produced
beforehand are not adversely affected by the embossing on
account of the internal high pressure pi, so that a high
quality of the hollow sections 2 produced can be
achieved.
CA 02544242 2006-04-28
P804094/WO/1
- 10 -
One possible method of cutting the hollow section 2 or of
forming, embossing and/or perforating the hollow section
2 is to be briefly explained below:
According to fig. 1, the hollow section 2 is inserted
into the tool l, the two dies 7 and 8 being in the open
state, that is to say being positioned at a distance from
one another. After the insertion of the hollow section 2,
which at this stage is still a hollow section blank (not
designated in any more detail), the positioning device 9,
according to fig. 2, pushes the hollow section 2, still
before the cutting and forming operation, against that
side 6 of the cutting device 4 which faces the hollow
section 2, that is to say against the die wall 17. During
the positioning, the tool, according to fig. 2, is still
in a partly open state, so that a simple adjustment of
the hollow section 2 in the direction of the cutting
device 4 is possible.
The cutting operation is effected after the positioning.
To this end, according to fig. 3, the top die 8 moves
towards the bottom die 7 and cuts off the flange 3 of the
hollow section 2 by means of the cutting edge 5, situated
at the front on the cutting device 4 in the direction of
movement. At least during the cutting operation, at least
one hold-down 10 arranged in the region of the cutting
edge 5 fixes the flange 3 of the hollow section 2. After
the cutting operation has been completed, a second hold-
down 10' fixes the remaining flange stub of the hollow
section 2 and thus fixes the hollow section 2 in its
position. After the cutting operation, cutting scrap (not
shown) falls through an ejection shaft 16, which
according to figs 1 to 5 runs out vertically in the
bottom die 7 in the direction of movement of the cutting
CA 02544242 2006-04-28
P804094/WO/1
- 11 -
device 4.
It can be seen from figs 2 and 3 that the cutting of the
flange 3 is effected by the closing of the tool l, that
is to say by a movement of the top die 8 toward the
bottom die 7. It is also conceivable in this case for the
cutting operation to be effected only after the closing
of the tool, that is to say when the top die 8 bears
against the bottom die 7, by a cutting device 4 which is
adjustable in stroke and is designed, for example, as a
separate component.
After completion of the cutting operation, the hollow
section blank 2' is formed by internal high pressure
forming and in the process changes in size and form in
accordance with the illustration in fig. 3. During the
internal high pressure forming, the positioning device 9
is actively shifted back or passively thrust back to a
corresponding extent, that is to say the holding or
positioning force of the positioning device 9 is
(markedly) smaller than the forces which occur during the
forming and which widen the hollow section 2.
After the forming of the hollow section 2, an embossing
punch 11 displaceable transversely to the longitudinal
direction of the hollow section 2 can make an embossment
on the outside of the hollow section 2 according to fig.
4. In this case, such an embossing operation is
optionally selectable. Embossing is effected according to
fig. 4 by the embossing punch 11 moving transversely to
the longitudinal extent of the hollow section 2 through
the opening 12 in the cutting device 4 and embossing a
recess in an outer wall of the hollow section 2 by means
of the embossing surface 15 provided at the front in the
CA 02544242 2006-04-28
P804094/WO/1
- 12 -
embossing direction.
In addition to or as an .alternative to the embossing
operation, a perforating punch 13 arranged in the
embossing punch 11 coaxially thereto can perforate the
hollow section 2 after the embossing operation has been
completed (cf. fig. 4). To this end, the perforating
punch 13 travels transversely to the direction of
movement of the cutting device 4 and parallel to the
embossing direction of the embossing punch 11 and pierces
the outer wall of the hollow section 2. According to figs
3 and 4, in each case one perforating punch 13 is
provided here. However, it is also possible for a
plurality of perforating punches 13 to be arranged. It is
also conceivable for perforating to be effected without
embossing of the hollow section 2. On account of the
embossing punch 11 or perforating punch 13 acting against
the internal high pressure pi, it is possible to carry out
both the embossing and the perforating on the hollow
2_0 section 2 without these processing steps adversely
affecting one another as in a conventional method of
production in a plurality of steps.
In this case, the embossing surface 15 of the embossing
punch 11, this embossing surface 15 being arranged by way
of example in the opening 12 of the cutting device 4, may
form part of that side 6 of the cutting device 4 which is
designed as a shaping die wall 17. However,._ it is also
conceivable for the opening 12 not to open until during
an embossing or perforating operation and for it to be
closed during the cutting operation or during the forming
operation, as a result of which the shaping die wall 17
is formed completely by that side 6 of the cutting device
4 which faces the hollow section 2.
CA 02544242 2006-04-28
P804094/WO/1
- 13 -
According to fig. 5, the tool 1 is opened after the
cutting and forming operation and/or embossing operation
and/or perforating operation by the top die 8 moving away
from the bottom die 7. In the process, the embossing
punch 11 and also the perforating punch 13 are retracted
into the tool 1 or the cutting device 4 at least to such
an extent that the two dies 7 and 8 can move apart
without any problems and the hollow section 2 can be
removed from the tool 1.
In summary, the essential features of the solution
according to the invention can be characterized as
follows:
In a tool 1 which is designed for forming a hollow
section 2 according to the internal high pressure forming
process, the invention makes provision for an embossing
punch 11 for making an embossment and for a perforating
punch 13 therein for making a hole in the hollow section
2. In addition, a cutting device 4 having a shaping die
wall 17 may be provided.
The invention thus enables a plurality of processing
steps to be combined, for example the trimming, the
forming, the embossing and the perforating of the hollow
section 2, in one production station, so that, with the
tool 1 according to the invention, a plurality of
processing steps hitherto separate from one another can
be effected promptly and without removal of the hollow
section 2 from the tool 1. In addition, the processing
steps of embossing and perforating can be carried out
optionally, so that, for example, cutting of the flange 3
and subsequent forming and/or subsequent embossing and/or
CA 02544242 2006-04-28
P804094/WO/1
- 14 -
subsequent perforating can be carried out with the tool 1
according to the invention.
That side 6 of the cutting device 4 which is designed as
a shaping die wall 17 provides for multifunctional use of
the cutting device 4, the cutting device 4 being simple
to realize from the design point of view and at the same
time constituting an especially successful design
solution. In addition, due to the embossing punch 11 or
perforating punch 13 acting against the internal high
pressure pi, exact embossing or perforating of the hollow
section 2 can be effected, during which the embossing and
the perforating do not adversely affect one another, so
that an end product of high quality can be achieved
overall.
