U.S. patent application number 14/913624 was filed with the patent office on 2016-07-14 for stamping arrangement and use thereof.
This patent application is currently assigned to Julia Vanderpool. The applicant listed for this patent is Julia VANDERPOOL. Invention is credited to Albrecht Schneider.
Application Number | 20160199898 14/913624 |
Document ID | / |
Family ID | 49084756 |
Filed Date | 2016-07-14 |
United States Patent
Application |
20160199898 |
Kind Code |
A1 |
Schneider; Albrecht |
July 14, 2016 |
STAMPING ARRANGEMENT AND USE THEREOF
Abstract
In a stamping arrangement, during stamping a stamping punch
makes contact, in the region of a punch shoulder, with a holding
plate or a pressure plate between the stamping punch and holding
plate. The stamping punch has a punch head and the holding plate
has a receptacle for the punch head. Means for fastening the punch
head to the holding plate have a pocket made in the punch head, a
clamping screw screwed into a threaded bore of the holding plate, a
pressure piece arranged in the axial direction of the clamping
screw between the latter and the pocket, and a holding screw for
the pressure piece, wherein the holding screw passes through a bore
of the clamping screw and is screwed with a threaded portion into a
threaded bore of the pressure piece. With the clamping screw in a
screwed-in position, areal contact is made, on a side of the pocket
that faces away from the punch shoulder, between a conical portion
of the pressure piece and a conical portion of the pocket, and the
punch shoulder bears against the holding plate or the pressure
plate, wherein a screw head of the holding screw is arranged with
axial play with respect to the clamping screw.
Inventors: |
Schneider; Albrecht;
(Oberursel, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
VANDERPOOL; Julia |
Oberursel |
|
DE |
|
|
Assignee: |
Vanderpool; Julia
Oberursel
DE
|
Family ID: |
49084756 |
Appl. No.: |
14/913624 |
Filed: |
August 15, 2014 |
PCT Filed: |
August 15, 2014 |
PCT NO: |
PCT/EP2014/002241 |
371 Date: |
February 22, 2016 |
Current U.S.
Class: |
72/352 |
Current CPC
Class: |
B21D 22/02 20130101;
B21D 37/14 20130101; B21D 28/343 20130101 |
International
Class: |
B21D 22/02 20060101
B21D022/02 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 23, 2013 |
EP |
13181503.7 |
Claims
1. A stamping arrangement having a stamping punch and a holding
plate for the stamping punch, wherein the stamping punch, in a
stamping stroke, makes contact in the region of a punch shoulder
with the holding plate, or with a pressure plate disposed between
the stamping punch and the holding plate, and the stamping punch
has a punch head and the holding plate has a receptacle for the
punch head, and means for fastening the punch head to the holding
plate are provided, wherein the means have: a pocket made in the
punch head, a clamping screw screwed into a threaded bore of the
holding plate, a pressure piece arranged in the axial direction of
the clamping screw between the clamping screw and the pocket, and a
holding screw for the pressure piece, wherein the holding screw
passes through a bore of the clamping screw and is screwed with a
threaded portion into a threaded bore of the pressure piece,
wherein, in a screwed-in position of the clamping screw, on a side
of the pocket that is facing away from the punch shoulder, a
conical portion of the pressure piece makes full-faced contact with
a conical portion of the pocket, and, in this screwed-in position
of the clamping screw the punch shoulder bears against the holding
plate or the pressure plate, and a screw head of the holding screw
is arranged with axial play with respect to the clamping screw.
2. The stamping arrangement as claimed in claim 1, wherein an end
of the pressure piece that is facing toward the pocket is of
frustoconical configuration, and a peripheral region which is
present there, in the region of its free end, has a flattened
contact surface for the purpose of contact with the pocket.
3. The stamping arrangement as claimed in claim 2, wherein the
pocket is configured as a frustoconical recess, tapering in the
direction of a floor in the pocket and having a contact surface,
disposed in a peripheral region for the purpose of contact with the
pressure piece.
4. The stamping arrangement as claimed in claim 3, wherein the
frustoconical recess defined by the pocket has an oval cross
section.
5. The stamping arrangement as claimed in claim 3, wherein the
pressure piece, in the screwed-in position of the clamping screw,
is arranged at a distance to the floor of the pocket.
6. The stamping arrangement as claimed in claim 1, wherein means
for orienting the pressure piece in a rotational direction of the
pressure piece relative to the conical portion of the pocket are
provided.
7. The stamping arrangement as claimed in claim 1, wherein the
clamping screw has a screw head having an outer polygon for
cooperating with a screwing tool.
8. The stamping arrangement as claimed in claim 7, wherein the
screw head of the clamping screw, in the screwed-in position of the
clamping screw, protrudes beyond the holding plate.
9. The stamping arrangement as claimed in claim 1, wherein the
screw head of the holding screw has an inner polygon, and wherein
the screw head is disposed within the clamping screw.
10. The stamping arrangement as claimed in claim 1, wherein the
pressure plate is connected to the holding plate and is provided
with a long hole which passes through the punch head.
11. The stamping arrangement as claimed in claim 1, wherein two
pockets are made in the punch head, and a corresponding pressure
piece cooperates with a respective pocket, and a clamping screw and
a holding screw cooperate with the corresponding pressure
piece.
12. The stamping arrangement as claimed in claim 11, wherein the
pockets are identical, the clamping screws are identical, the
pressure pieces are identical, and the holding screws are
identical.
13. The stamping arrangement as claimed in claim 1, wherein the
holding plate has two receptacles and the punch head has two head
portions, wherein a respective head portion is inserted into a
respective receptacle and each head portion has a pocket.
14. The stamping arrangement as claimed in claim 1, wherein the
punch head is guided in the holding plate in the spatial directions
arranged perpendicular to the direction of insertion into the
holding plate.
15. Use of the stamping arrangement as claimed in claim 1 in a
stamping unit with a stripping force per stamping punch greater
than about 50 kN and less than about 100 kN.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This United States non-provisional application is the
national stage of International Application No. PCT/EP2014/002241
filed on Aug. 15, 2014, which claims the benefit of priority to
European Application No. EP 13181503.7 filed on Aug. 23, 2013, the
entire disclosures of which are incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] The invention relates to a stamping arrangement having a
stamping punch and a holding plate for the stamping punch.
BACKGROUND OF THE INVENTION AND RELATED ART
[0003] Stamping punches are used in so-called "prog dies" and
"multiple die presses". Tools of this type work as sets comprising,
in some circumstances, a plurality of sister tools in multiple-die
presses with high punching force.
[0004] The main field of application of such punching tools is
automobile construction, in particular the construction of chassis
and bodywork.
[0005] A "prog die" of this type, of small to medium size, has
external measurements of about 1,600 mm.times.1,200 mm, comprising
a multiplicity of forming punches, for instance about 20 forming
punches. In this case, stamping punches are generally arranged
spatially close together, surrounded by piping which serves to
monitor the pressures of installed gas pressure springs by means of
manometers built into the tool.
[0006] As a result of the ever more advancing use of high-strength
sheets in automobile construction, the necessary stamping
pressures, and thus also the stripping forces which act on the
stamping punch and the anchorage thereof in its holding plate in
the return and thus stripping operation, are increasing. In this
context, a maximum load of these stripping forces of about 100 kN
(10 tonnes) per forming punch can reasonably be assumed for the
"prog die". A stamping force of 1,000 kN (100 tonnes) is herein
adopted as the basis. A stamping punch absorption system which is
to be designed for this particular application must be able to
absorb these tensile forces in the return or stripping operation
with appropriate certainties.
[0007] A significantly reduced working life of the arrangement is
obtained if a play-afflicted mounting of the stamping punch in the
holding plate in the return or stripping operation has to be
registered. In this case, very high bending and gravitational
forces act on the connection of stamping punch and holding
plate.
[0008] Furthermore, regard must be paid to the spatial
relationships in the tool. The possibility must be given of being
able to change the stamping punches in the cramped lateral working
space brought about by the arrangement. In particular, this should
be possible quickly and without removal of the holding plate in the
event of wear or breakage of the punch.
OBJECT AND SUMMARY OF THE INVENTION
[0009] The object of the present invention is to provide a stamping
arrangement in which the working life of the arrangement, due to a
play-free mounting of the stamping punch in the holding plate in
the return or stripping operation, is significantly high.
[0010] The object is achieved by a stamping arrangement which is
configured according to the features of the invention disclosed
herein.
[0011] The stamping arrangement according to the invention has a
stamping punch and a holding plate for the stamping punch, wherein
the stamping punch, in a stamping stroke, makes contact in the
region of a punch shoulder with the holding plate, or with a
pressure plate disposed between the stamping punch and the holding
plate. The stamping punch has a punch head and the holding plate
has a receptacle for the punch head. In addition, means for
fastening the punch head to the holding plate are provided. These
means have according to the invention: [0012] a pocket made in the
punch head, [0013] a clamping screw screwed into a threaded bore of
the holding plate, [0014] a pressure piece arranged in the axial
direction of the clamping screw between the latter and the pocket,
[0015] a holding screw for the pressure piece, wherein the holding
screw passes through a bore of the clamping screw and is screwed
with a threaded portion into a threaded bore of the pressure
piece.
[0016] In this case, in a screwed-in position of the clamping
screw, on a side of the pocket that is facing away from the
shoulder, a conical portion of the pressure piece makes full-faced
contact with a conical portion of the pocket. In this screwed-in
position of the clamping screw, the punch shoulder bears against
the holding plate or the pressure plate, and a screw head of the
holding screw is arranged with axial play with respect to the
clamping screw.
[0017] In this configuration of the stamping arrangement, in
particular of the means for fastening the punch head to the holding
plate, it is ensured that the stamping punch is pretensioned with
its punch shoulder in a play-free manner against the holding plate
or the pressure plate. In the stamping stroke, it is thus ensured
that the stamping forces are transmitted between punch shoulder and
holding plate or punch shoulder and pressure plate. The stamping
pressure is thus not absorbed by the pressure piece. Related to the
return stroke or stripping operation of the stamping punch, this
has the result that the holding plate and the stamping punch are
moved in a play-free manner, since this freedom from play is
guaranteed by the inventive design and arrangement of the pressure
piece. There is thus no play-afflicted connection present between
holding plate and stamping punch and it is ensured that no loose
connection between holding plate and stamping punch arises. A loose
connection of this kind, which brings about an imprecise guidance
of the stamping punch, would result in the stamping punch deforming
or damaging the stamped sheet in the course of the return stroke or
stripping operation. Apart from this, a play-afflicted connection
of this kind leads to increased mechanical load upon the connection
region of holding plate and stamping punch, resulting in a shorter
working life. In particular, there is the danger of the stamping
punch breaking in the region of the punch head.
[0018] Since the pressure piece does not make contact with a recess
in the punch head, which recess passes fully through the punch
head, but instead a pocket is provided in the punch head, increased
forces can be transmitted via the punch head in the course of the
return stroke or stripping operation.
[0019] In the stamping arrangement according to the invention, by
means of the clamping screw, via the pressure piece, such a
pretensioning can be generated between punch shoulder and holding
plate or pressure plate, which pretensioning guarantees that the
stamping punch, following a theoretically possible setting
operation, is still firmly seated and thus no play can arise
between punch shoulder and holding plate or pressure plate.
[0020] In order that the stamping punch can be removed, it is
necessary to pull the pressure piece wedged in the pocket out of
this pocket. This is realized on the basis of the inventively
provided connection which the holding screw establishes between the
clamping screw and the pressure piece. If the clamping screw is
turned in the unscrewing direction, this leads to the axial play
between the screw head in the holding screw and the clamping screw
being reduced until the screw head of the holding screw bears
against the clamping screw, and then, upon further unscrewing of
the clamping screw, due to the form closure between the screw head
of the holding screw and the clamping screw, the pressure piece is
jointly moved, out of the clamping position with respect to the
pocket.
[0021] Preferably, means for orienting the pressure piece in a
rotational direction of the pressure piece relative to the conical
portion of the pocket are provided. As a result, a loose
precentering of the pressure piece is guaranteed, whereby it can be
readily ensured that, upon the advancement of the clamping screw,
the conical portion of the pressure piece makes full-faced contact
with the conical portion of the pocket.
[0022] According to one embodiment, it is provided that the
described arrangement for holding the stamping punch in the holding
plate is doubly provided. Thus two pockets are made in the punch
head, and a pressure piece cooperates with the respective pocket,
and a clamping screw and a holding screw cooperate with the
pressure piece. In this respect, reference is made to the preceding
statements. In this case, in particular these pockets are
identically configured, also these clamping screws are identically
configured, also these pressure pieces are identically configured,
and finally these holding screws are identically configured.
[0023] The stamping arrangement according to the invention is used,
in particular, in a "prog die" or multiple die press, having a
multiplicity of stamping and/or pressing tools, with a stripping
force >50 kN, in particular in a multiple die press with a
stripping force up to 100 kN.
[0024] Further features of the stamping arrangement according to
the invention are shown and described hereafter in the description
of exemplary embodiments of the invention, the accompanying drawing
figures and the description of the drawing figures, wherein it is
noted that all individual features and all combinations of
individual features are to be considered various aspects and
embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
[0025] In the accompanying drawing figures, the invention is
represented on the basis of various exemplary embodiments when used
in a "prog die", without the invention being restricted to these
embodiments and use, and wherein like reference character in the
various figures represent like or similar parts.
[0026] FIG. 1 represents a top view of a "prog die" fitted with a
multiplicity of forming punches, of which three are stamping
arrangements according to a first exemplary embodiment the
invention.
[0027] FIG. 2 represents a stamping arrangement according to the
invention in a three-dimensional view.
[0028] FIG. 3 represents the stamping arrangement according to FIG.
2 in an exploded representation.
[0029] FIG. 4 represents the stamping arrangement according to FIG.
2 in a view IV in FIG. 5.
[0030] FIG. 5 represents the stamping arrangement in a view V in
FIG. 4.
[0031] FIG. 6 represents a section through the stamping arrangement
according to the line VI-VI in FIG. 4.
[0032] FIG. 7 represents the region A according to FIG. 6 in
enlarged representation, wherein in FIG. 7 a pressure piece of the
stamping arrangement is illustrated in its clamping position.
[0033] FIG. 8 represents a section according to FIG. 7, illustrated
with the pressure piece of the stamping arrangement having been
moved out of a pocket.
[0034] FIG. 9 represents a holding plate of the stamping
arrangement in a three-dimensional view.
[0035] FIG. 10 represents the holding plate in a view X according
to FIG. 11.
[0036] FIG. 11 represents the holding plate in a view XI according
to FIG. 10.
[0037] FIG. 12 represents the holding plate in a view XII according
to FIG. 11.
[0038] FIG. 13 represents a stamping punch of the stamping
arrangement in a three-dimensional view.
[0039] FIG. 14 represents the stamping punch in a view XIV
according to FIG. 15.
[0040] FIG. 15 represents the stamping punch in a view XV according
to FIG. 14.
[0041] FIG. 16 represents the stamping punch in a view XVI
according to FIG. 14.
[0042] FIG. 17 represents the region B according to FIG. 15 in
enlarged representation.
[0043] FIG. 18 represents the functional unit formed from a
clamping screw, the pressure piece and a holding screw, in a
three-dimensional representation.
[0044] FIG. 19 represents the functional unit in a view XIX
according to FIG. 20.
[0045] FIG. 20 represents the functional unit in a view XX
according to FIG. 19.
[0046] FIG. 21 represents the holding screw in a three-dimensional
view.
[0047] FIG. 22 represents the holding screw in a view XXII
according to FIG. 23.
[0048] FIG. 23 represents the holding screw in a view XXIII
according to FIG. 22.
[0049] FIG. 24 represents the clamping screw in a three-dimensional
view.
[0050] FIG. 25 represents the clamping screw in a view XXV
according to FIG. 26.
[0051] FIG. 26 represents the clamping screw in a view XXVI
according to FIG. 25.
[0052] FIG. 27 represents the pressure piece in a three-dimensional
view.
[0053] FIG. 28 represents the pressure piece in a view XXVIII
according to FIG. 29.
[0054] FIG. 29 represents the pressure piece in a view XXIX
according to FIG. 28.
[0055] FIG. 30 represents for a second embodiment a modified
stamping arrangement in a sectional representation according to
FIG. 7.
[0056] FIG. 31 represents in a three-dimensional view the pressure
piece shown in FIG. 30.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION
[0057] FIG. 1 shows the top side of a "prog die" stamping unit 1
which is provided with a multiplicity of forming punches,
specifically eighteen forming punches. These are mounted in a
common unit, which, in small to medium size, has dimensions of
about 1,600.times.1,200 mm. This stamping unit 1 is mainly used in
automobile construction, in particular in the manufacture of
chassis and bodywork.
[0058] From FIG. 1 it can be seen that the eighteen forming punches
are arranged spatially close together, surrounded by piping 3,
which serves to monitor the pressures of built-in gas pressure
springs 4 by means of manometers built into the tool.
[0059] Three of the forming punches which are used in the stamping
unit 1 are configured in accordance with the a first exemplary
embodiment of a stamping arrangement 2 according to the
invention.
[0060] This stamping arrangement 2 according to the first
embodiment is illustrated in FIGS. 2 to 29.
[0061] The stamping arrangement 2 has a stamping punch 5 and a
holding plate 6 for the stamping punch 5. The stamping punch 5 has
a punch part 7, by means of which the actual stamping is realized,
as well as a punch head 8 connected to the punch part 7. The punch
head 8 is of plate-like configuration. On the side facing toward
the punch head 8, the punch part 7 has a punch shoulder 9.
[0062] Between the stamping punch 5, specifically the punch
shoulder 9, and the holding plate 6 is arranged a pressure plate
10. The pressure plate 10 has a long hole 11 which passes through
it. On both sides of the long hole, the pressure plate is provided
with recesses for the reception of screws 12, wherein the
(non-illustrated) heads of these screws 12 are sunk in the region
of the bottom side of the pressure plate 10. By means of these
screws 12, the pressure plate 10 is fastened to the bottom side of
the holding plate 6, specifically is screwed into the threaded
bores 13 which are present there. The long hole 11 has such
dimensions that the punch head 8 passes through the pressure plate
10 with low play in the two spatial coordinates running
perpendicular to the direction of insertion of the punch head
2.
[0063] Viewed in the direction of stamping, the holding plate 6,
the pressure plate 10 and the punch part 7 have an identical
cross-sectional shape, namely in the form of a rectangle with
beveled corners. The surface areas of holding plate 6 and pressure
plate 10, viewed in the direction of stamping, are equal, while the
surface area of the punch part 7 in this direction is smaller.
[0064] The holding plate 6 has in the region of the four corners
bores for the reception of screws 14, wherein the respective screw
head, on that side of the holding plate 6 that is facing toward the
pressure plate 10, is sunk in a recess. By means of these screws
14, the holding plate 6 is connected to a base plate 15 of the
stamping unit 1. Two dowel pins 16 mounted in the holding plate 6
serve for the guidance of the holding plate 6 in the positioning of
the holding plate 6 with respect to the base plate 15.
Correspondingly, the base plate 15 is provided not only with
threaded bores for the screwing-in of the screws 14, but also with
receptacles for the insertion of the dowel pins 16.
[0065] The holding plate 6 has two receptacles 17 and an
intervening crosspiece 18. In this case, the receptacles 17 pass
through the holding plate 6, while the crosspiece 18 extends only
roughly over half of the thickness of the holding plate 6, in that
region of the holding plate 6 that is facing away from the pressure
plate 10. Correspondingly, the punch head 8 has two head portions
19, between which a recess 20 is formed. The respective head
portion 19 is inserted into a receptacle 17 assigned thereto. In
this case, the crosspiece 18 passes through the recess 20.
Consequently the stamping punch 5 is positioned in the region of
the punch head 8 in the two coordinate directions perpendicular to
the direction of stamping, largely without play, in the receptacles
17 of the holding plate 6, and is also oriented with respect to the
crosspiece 18 of the holding plate 6.
[0066] In that position of the stamping punch 5 in which it is
inserted in the holding plate 6 and in which the stamping punch 5
passes with the punch head 8 through the pressure plate 10 and the
pressure plate 10 is screwed to the holding plate 6 and this is
screwed to the base plate 15 of the stamping unit 1, said
components form a functional unit. In this case, the stamping punch
5 bears in the direction of stamping in a play-free manner against
the pressure plate 10 in the region of the punch shoulder 9.
[0067] Owing to the described arrangement, the stamping punch 5 can
be removed or exchanged without the need for removal of the
pressure plate 10 from the holding plate 6.
[0068] The stamping punch 5 is held in the holding plate 6 by
doubly provided means 21 for fastening the punch head 8 to the
holding plate 6. The respective means 21 has a pocket 22 made in
the punch head 8, a clamping screw 24 screwed into a threaded bore
23 of the holding plate 6, a pressure piece 25 arranged in the
axial direction of the clamping screw 24 between the latter and the
pocket 22, and a holding screw 26 for the pressure piece 25. The
holding screw 26 passes through a bore 27 of the clamping screw 24
and is screwed with a threaded portion 28 into a threaded bore 29
of the pressure piece 25. In a screwed-in position of the clamping
screw 24, on a side 30 of the pocket 22 that is facing away from
the punch shoulder 9, a conical portion 31 of the pressure piece 25
makes full-faced contact with a conical portion 32 of the pocket
22. In this screwed-in position of the clamping screw 24,
illustrated in detail in FIG. 7, the punch shoulder 9 bears
squarely against the pressure plate 10. In this case, a screw head
33 of the holding screw 26 is arranged with axial play, illustrated
by the gap 34, with respect to the clamping screw 24.
[0069] In detail, that end of the pressure piece 25 that is facing
away from the pocket 22 is configured as a rotationally symmetrical
cylinder 35 and that end of the pressure piece 25 that is facing
toward the pocket 22 is configured as a truncated cone 46. A
peripheral region of the truncated cone 46 has in the region of its
free end a flat contact surface 36 for the purpose of contact with
the pocket 22. The pocket 22 is configured as a frustoconical
recess, tapering in the direction of a floor 37 of the pocket 22
and having a flat contact surface 38, disposed at least in a
peripheral region of the truncated cone, for the purpose of
full-faced contact with the contact surface 36 of the pressure
piece 22. In this case, the pocket 22, thus the frustoconical
recess, has an oval, in particular slightly oval cross section. The
extent of the pocket 22 transversely to the direction of stamping
of the stamping punch 5 or in the return direction thereof is less
than the extent of the pocket 22 perpendicular to this direction.
This allows a certain tolerance compensation in the transverse
extent, thus in the direction of the distance apart of the two
pockets 22, from the aspect of production inaccuracies.
[0070] Solely for reason of simplified production, on the conical
part of the pressure piece 25 there is likewise provided, also in
the diametral region, a face 39.
[0071] As can be seen in particular from FIG. 7, the pressure piece
22, in the screwed-in position of the clamping screw 24, is
arranged at a distance to the floor 37 of the pocket. The clamping
screw 24 has a screw head 40 having an outer polygon, configured as
a hexagon. In the screwed-in position of the clamping screw 24, the
screw head 40 protrudes beyond the holding plate 6, so that,
without the need for considerable installation space next to the
stamping arrangement 2, simple actuation of the screw head 40 by
means of a screwing tool is possible. The holding screw has a screw
head having an inner polygon, in particular a hexagon, wherein the
screw head 41 is disposed within the clamping screw 24.
[0072] FIG. 2 shows one clamping screw 24 in its screwed-in
position (in accordance with FIG. 7) and the other clamping screw
24 in a partially unscrewed position (in accordance with FIG.
8).
[0073] In the stamping arrangement 2, two pockets 22 are thus made
in the punch head 8, and a pressure piece cooperates with the
respective pocket 22, and a clamping screw 24 and a holding screw
26 cooperate with the pressure piece 25. The pockets 22 are
identically configured, just as the clamping screws 24 are
identically configured, the pressure pieces 25 are identically
configured, and the holding screws 26 are identically
configured.
[0074] In the stamping arrangement 2 according to the invention,
the stamping punch 5 is placed through the pressure plate 10 and
screwed to the holding plate 6. The precise location positioning is
realized by two fits in the X and Y direction. By the two means 21,
the stamping punch 5 is secured against being pulled out in the Z
direction. This type of securement or fastening enables rapid
changing of the stamping punch 5. In the clamped state, as is
illustrated in particular in FIG. 7, the respective pressure piece
25 bears against the end face of the clamping screw 24 and is
pressed via its external thread into that milled recess in the
punch head 8 which corresponds to the geometry of the pressure
piece 25. Via the bevel on the end of the pressure piece 25, the
punch shoulder 9 is drawn against the pressure plate 10 by means of
the counter bevel in the punch head 8, so that the stamping punch 5
can be pressed by means of the two provided means 21, counter to
the direction of stamping, with pretension against the pressure
plate 10, which can then absorb the stamping pressure.
[0075] For the removal of the stamping punch 5 in the direction of
stamping, the respective clamping screw 24 is loosened and,
following contact of the bottom part of the screw head 41 of the
holding screw 26 for the pressure piece 25 with the countersink in
the clamping screw 24, the pressure piece 25 is pulled by means of
the holding screw 26 out of the milled recess in the punch head 8.
Upon further rotations of the clamping screw 24, the pressure piece
25 frees the stamping punch 5, specifically the punch head 8, after
the pressure piece 25 is moved completely out of the punch head
8.
[0076] A further function of the clamping screws 24 is the
absorption of the stripping pressure following stamping when the
stamping punch 5 leaves the stamped sheet in the direction of the
upper dead center. This is effected by the pressing of the
respective head portion 19 against the opposite wall of the
receptacle of the holding plate 6 by means of the clamping screws
24, and by the shearing resistance of the cross section of the
engaged pressure pieces 25.
[0077] The forces which arise in the course of the stripping after
the stamping can in this case amount to up to 100 kN.
[0078] The use of a plurality of clamping screws, in the present
case the two clamping screws 24, enables narrow tolerance ranges to
be managed both in the series arrangement of the clamping screw
threads in respect of the holding plate 6, and of the milled
recesses in the punch head 8, by which bevels in the milled recess
in the punch head 8 and also on the front part of the pressure
piece 25 are compensated without impairment of a clamping screw 24
in terms of its function of pressing the punch shoulder 9.
[0079] The clamping screw 24 is constituted, for instance, by a M16
screw, the holding screw 26 by a M4 screw. The pressure piece has,
for instance, a diameter of 13 mm, wherein the conical portion 31
runs at an angle of 5.degree. to the pocket axis. The oval conical
pocket 22 has, for instance, dimensions of 14 mm/12 mm, with a 6 mm
depth.
[0080] A second exemplary embodiment according to FIGS. 30 and 31
differs from the first embodiment only in terms of the
configuration of the pressure piece 25 and means for the loose
precentering of the pressure piece 25. In this respect, for the
avoidance of repetitions, reference is made to the basic statements
concerning the first embodiment.
[0081] In the second embodiment according to FIGS. 30 and 31, the
cylindrical portion 35 of the pressure piece is provided with a
groove 42 which runs in the axial direction and is open radially
outward. This groove extends from that end of the pressure piece 25
that is facing away from the contact surface 36 to almost into the
region of the contact surface 36. The groove 42 is arranged such
that the extension of the groove 42 coincides with a line of
symmetry of the contact surface 36, so that an orientation of the
groove 42 corresponds to a corresponding orientation of the contact
surface 36. Cooperating with the groove 42 is a setscrew 43, which
in the region of its end facing toward the pressure piece 25 has a
dog point 44. The diameter of the dog point 44 is slightly smaller
than the width of the groove 42. The setscrew 43 is screwed into a
threaded bore 45 of the holding plate 6. The setscrew 43 with dog
point 44 enables a loose precentering of the pressure piece 25. It
can thus easily be ensured that, when the clamping screw 24 is
screwed in, the pressure piece 25, in the region of its contact
surface 36, is exactly oriented with respect to the conical portion
32 in the pocket 22.
[0082] In the preassembly of the holding plate 6, the respective
pressure piece 25 is oriented once with its groove 42 and the
setscrew 43 is screwed in to the point where its dog point 44
engages in the groove 42 without a tensioning between the dog point
44 and the pressure piece 25. The pressure piece 25 is thus fixed
with play. Neither the groove 42, nor the turned end of the
setscrew 43, i.e. the dog point 44, are subjected to load, since
the precentering function is fulfilled with the threading of the
faces of the pressure piece 25 into the associated pocket 22 in the
holding plate 6.
* * * * *