Field of the Invention
[0001] The invention relates to a punch unit according to the preamble of claim 1.
Background of the Invention
[0002] A punch unit of this type is known from U.S.-A-5,131,303. In this structure the back
end of the punch, which is provided with an exterior thread, is screwed into a threaded
bore at the front end of the punch driver. The threaded section at the back end of
the punch is provided with four axial, longitudinal grooves, and an open spring washer,
whose one end is radially bent inward and projects through a radial hole into one
of the axial grooves of the punch. The spring washer is seated on the exterior circumference
of the front end of the punch driver. In the assembled state the guide bushing is
frictionally connected via an O-ring with a washer seated on the punch driver underneath
the compression spring and prevents the spring washer from being able to yield radially
outward. In this way the punch and the punch driver are directly connected with each
other by the spring washer without being able to rotate.
[0003] When the punch is to be reground, the punch driver can be pulled away from the guide
bushing toward the rear, in the course of which the frictional connection at the O-ring
is released. After the spring washer has left the guide bushing, the threaded connection
between the punch and the punch driver can be released by relative rotation. Because
the radially inward bent end of the open spring washer has a point and the lateral
walls of the grooves are inclined, the free end of the spring washer is pushed out
of the groove in which it had been engaged when the punch is rotated in relation to
the punch driver and, with continued relative rotation, then engages the next groove.
Since the thread pitch is known, it is also known which change in the total length
of the punch and punch driver corresponds to the rotational angle between two grooves.
Because of this it is possible in a very simple way to reset the total length of the
punch and punch driver following the regrinding of the punch. As soon as the guide
bushing has subsequently again been pushed over the open spring washer and has been
frictionally connected with the punch driver via the O-ring, the screw connection
between the punch and the punch driver is again dependably blocked against relative
rotation because the guide bushing does not permit the open spring washer to widen
radially, so that therefore its radially inwardly bent end no longer can leave the
radial groove with which it is in engagement at that time.
[0004] Although the known punch unit assures a simple setting of the total length of the
punch and punch driver, it suffers from the essential disadvantage that the grooves
intended for safeguarding against relative rotation weaken the thread through which
the large punching forces are transmitted to the punch. This is of particular disadvantage
in connection with punches having a relatively small cross section, as finer adjustment
is required with decreasing cross section, because it is then necessary to have correspondingly
more grooves at the circumference.
Summary of the Invention
[0005] It is therefore the object of the invention to provide a punch unit of the initially
mentioned type wherein the weakening of the connection between the punch and the punch
driver is avoided and an adjustment of its total length in arbitrary small steps is
made possible.
[0006] The above object is attained in accordance with the invention by a punch unit according
to claim 1.
[0007] The arrangement is preferably selected to be such that at least one radial protrusion
is axially formed on the punch driver between the exterior back end of the punch and
the compression spring which protrusion, in the assembled state, is in engagement
with an axial groove, open at the back end, in the guide bushing.
[0008] The essential advantage is achieved by the invention in that axial grooves required
for an adjustable safeguarding against relative rotation or other safeguard elements
are disposed on or in a part which is unaffected by the punch forces, namely the guide
bushing, whose weakening is of no consequence. Simultaneously the further advantage
is achieved that, with the same punch cross section, the grooves are located on a
larger radius. It is, therefore, easily possible to dispose more grooves at the circumference,
and their angular accuracy is greater.
[0009] In view of the simplicity and the costs of the punch unit, a further advantage resides
in that no or only very small changes in the punch itself, which is a wear item, need
to be made for achieving the adjustable safeguard against relative rotation between
the punch and the punch driver, which in accordance with the invention is now assured
indirectly via the guide bushing. It is therefore not necessary to provide each replacement
punch again with grooves, because this part of the safeguard against relative rotation
is maintained together with the guide bushing when the punch is replaced.
[0010] In addition, the invention offers increased functional assurance. In connection with
the initially mentioned known punch unit it could be possible that the fact that the
spring washer constituting the safeguard against relative rotation was not in its
correct locking position, could have remained unnoticed. In that case the stress of
the punch force resulted in the destruction of the tool. In contrast thereto, with
the suggested punch unit it can be very clearly noticed whether the radial protrusion
on the punch driver has entered one of the grooves in the guide bushing or whether
the parts still are in their separated position required for a relative rotation.
[0011] In a preferred embodiment of the invention the radial protrusion is arranged on a
set collar which can be screwed onto a threaded section of the punch driver, can be
fixed in place in a defined position and represents the spring bearing. This is necessary
anyway and is also not a wear item. In this embodiment the punch itself does not require
any additional processing.
[0012] The invention will be explained in detail below by means of an exemplary embodiment
illustrated in the drawings.
Brief Description of the Drawings
[0013] There follows a detailed description of the preferred embodiments of the present
invention which are to be taken together with the accompanying drawings, wherein:
Figs. 1 and 2 are lateral views, partially in section, of a punch unit in the completely
assembled state, wherein the sectional planes through the punch in Figs. 1 and 2 are
offset by 45° in respect to each other and in relation to the center axis; and
Figs. 3 and 4 are views corresponding to Fig. 1 or Fig. 2 in a position of the parts
wherein they are sufficiently pulled apart axially so that a respective relative rotation
of the upper part in respect to the lower part is possible.
Detailed Description of the Preferred Embodiments
[0014] Referring now to the figures, like elements are represented by like numerals throughout
the several views.
[0015] The punch unit represented in Figs. 1 to 4 consists in a known manner of a punch
10 guided linearly displaceable in a guide bushing 12. A rotation of the punch 10
in relation to the guide bushing 12 is prevented by a pin 16, fixedly seated in a
radial bore 14 in the punch 10, which protrudes radially and engages an interior longitudinal
groove 18 in the guide bushing 12. This axial groove 18 is also radially outwardly
open over a portion of its length, so that a pin, not shown, or other securing member
can engage the groove 18 from the outside and can maintain the guide groove 18 or
bushing 12 non-rotatingly on the machine frame, not shown. In this respect, as well
as in relation to the disposition of a stripper ring 22 fastened on the lower end
of the guide bushing 12 by a securing or fixing washer 20, the disclosed punch unit
corresponds to conventional designs.
[0016] In further agreement with known punching tools, the back or upper end of the punch
10 is screwed together with a punch driver 24. In the exemplary embodiment represented,
the back end of the punch 10 is provided with a threaded bore 25 for this purpose,
into which the front end 26, which is provided with an exterior thread, of the punch
driver 24 is screwed. The total length of the punch 10 and the punch driver 24 is
set by screwing the front end of the punch driver 24 into the threaded bore 25 of
the punch 10 more or less deeply.
[0017] A set collar 28, provided with a corresponding interior thread, is located above
the punch 10 on the exterior thread of the front end 26 of the punch driver 24. Its
cross section is of a slightly smaller size than the punch 10, because during the
stroke of the punch it performs an axial relative movement in the guide bushing 12
together with the punch 10. An intermediate ring 30 is supported on the set collar
28 and is seated, freely displaceable, on the shaft of the punch driver 24 which adjoins
the front end 26 provided with the thread above or toward the rear. The set collar
28 forms a stop for the movement of the intermediate ring 30 in the axially forward
or downward direction of movement.
[0018] Between a base 32 disposed at the upper or back end of the punch driver 24 and the
intermediate ring 30, a compression spring 34 is clamped in a known manner, whose
pre-load can be set or adjusted in that the set collar 28 is screwed to a greater
or lesser extent on the exterior thread on the front end 26 of the punch driver 24
and is then fixed in place. The position secure against relative rotation of the set
collar 28 can be achieved, for example, by a securing screw (not shown) screwed into
a radial threaded bore and engaging the exterior thread on the front end 26 of the
punch driver 24.
[0019] The punch driver 24, together with the set collar 28 screwed on its front end 26
and the spring 34 maintained under pre-load by this and with the intermediate ring
30, forms a preassembled unit which is connected with the punch 10 seated in the guide
bushing 12 in that the front end 26, provided with the thread, of the punch driver
24 is screwed into the corresponding threaded bore in the back end of the punch 10.
This screw connection makes it possible to remove the punch 10 from the punch driver
24 for the purpose of regrinding. The smaller punch work piece makes the regrinding
process easier. In addition, the threaded connection at the front end 26 of the punch
driver 24 allows an increased length compensation of the shortening connected with
the regrinding of the punch 10.
[0020] In order to maintain a constant defined, set total length of the punch 10 and the
punch driver 24, it is necessary to prevent the relative rotation of these two parts
during punching. At the same time a very simple adjustment possibility of the length
is demanded, and finally the locking, secure against relative rotation, should not
weaken the greatly stressed parts and should have the lowest possible manufacturing
and assembly costs.
[0021] One or a plurality of longitudinal grooves 36, which are distributed over the circumference
and are open toward the top or the back, in the back end of the guide bushing 12 and
one or a plurality of radial protrusions 38 on the punch driver 24, which are to be
brought into engagement with these grooves, are sufficient in the punch unit shown
to achieve all these goals. The axial grooves 36, for example two, four or six grooves
cut evenly distributed over the circumference into the guide bushing in addition to
the slightly wider longitudinal groove 18 and whose length does not need to be much
greater than the maximum stroke of the punch, are located on a comparatively large
radius and only weaken the guide bushing 12, which is not stressed by the punch force.
Even with small punch cross sections it is possible to easily cut four, six or even
more grooves 36 in the interior circumference of the guide bushing 12. Only the manufacturing
costs of a comparatively long-lived part of the tool are increased by the work required
for the grooves 36, so that this cost is hardly of any consequence.
[0022] The radial protrusion 38 on the side of the punch driver 24 is preferably disposed
on the set collar 28. The protrusion can be formed, for example, by a set screw screwed
into a radial threaded bore in the set collar 28 - for example, even by the screw
by means of which the set collar 28 is maintained fixed against relative rotation
on the punch driver 24 - or by a pin pressed into a radial bore which, the same as
the set screw mentioned, protrudes radially in respect to the set collar 28 and can
be brought into engagement with one of the longitudinal grooves 36.
[0023] The punch unit shown has the particular advantage that changes of the total length
of the punch 10 and the punch driver 24 can be made very rapidly and simply. Starting
with the position represented in Figs. 1 and 2, it is only necessary to lift the punch
driver 24 together with the parts connected with it sufficiently far in relation to
the guide bushing 12 maintained on the machine frame, so that the radial protrusion
38 has left the groove 36, open at the top, which receives it, in a direction toward
the back or upward. This retracted position of the punch driver 24 is represented
in Figs. 3 and 4. Now if in this position, or in a position in which it is even further
lifted or retracted, the punch driver 24 is turned in one or the other direction,
while the punch 10, together with the guide bushing 12, is maintained fixed against
relative rotation by the engagement of the pin 16 with the groove 18, the engagement
length by which the front end 26, provided with the exterior thread, of the punch
driver 24 engages the threaded bore 25 in the back end of the punch 10 is changed.
Since the pitch of this thread is known, the value by which the total length of the
punch 10 and the punch driver 24 is changed, is also known if, together with the latter,
the radial protrusion 38 is rotated by the pitch angle between two grooves 36. It
is understood that with an increase in the number of grooves 36 distributed over the
circumference the adjustment accuracy is increased. In the course of this, for example,
there is also the option to embody the grooves 36 in the form of an interior toothing
and the exterior circumference of the set collar 28 in the form of an exterior toothing
which is to be brought into engagement with this interior toothing.
[0024] To ease the setting of the total length of the punch 10 and the punch driver 24,
it is possible to apply visible markers on the existing grooves 36 on the exterior
circumference of the guide bushing 12.
[0025] After having set the desired total length, it is only necessary to lower the punch
driver 24 back into the position shown in Figs. 1 and 2, in which the radial protrusion
38 is again in engagement with one of the grooves 36. In the embodiment shown, in
this position the intermediate ring 30, whose exterior diameter is greater than the
set collar 28, is seated in a widened bore section at the rearmost end of the guide
bushing 12. The intermediate ring 30 has an O-ring 40 in an annular groove on its
exterior circumference which, in the position shown in Figs. 1 and 2, is seated radially
compressed in the widened bore section at the rearmost end of the guide bushing 12.
A seal against the emergence toward the back of lubricant from the guide bushing 12
is provided in this way. In addition, the O-ring 40 constitutes an easily releasable
frictionally engaged connection between the guide bushing 12 and the punch driver
24. It can additionally be secured in that the widened bore section in the rearmost
end of the guide bushing 12 is embodied with an interior annular groove which is engaged
by the O-ring 40.
[0026] As can be seen from Figs. 1 and 2, during the stroke of the punch the pressure force
required for punching is transmitted via the continuous threads on the front end 26
of the punch driver 24 and in the axial threaded bore 25 in the back end of the punch
10. While being compressed during the stroke of the punch, the comparatively large
compression spring 34 is no longer supported via the intermediate ring 30 on the set
collar 28, which is only used for setting the pre-load, but in a known manner on the
back end of the guide bushing 12.
[0027] In the embodiment described above, the radial protrusion 38 is disposed on the set
collar 28 which, in turn, is seated on the punch driver 24 between the back end of
the punch 10 and the spring 34. It is understood that it is possible to directly or
indirectly dispose a radial protrusion 38, which is to be brought into engagement
with one or a plurality of grooves 36 in the back end of the guide bushing 12, on
the punch driver 24 even if, differently from the way shown in the drawings, the front
end of the latter is provided with a threaded bore into which the back end of the
punch 10, which is provided with an exterior thread, can be screwed. Also, the arrangement
of the radial protrusion and the grooves can be reversed in that a radially inward
extending protrusion is embodied or disposed at the back end of the guide bushing
12 which engages one of several axial grooves at the exterior circumference of the
set collar 28. In this case the radial protrusion should suitably be disposed on a
radius which is greater than the radius of the punch 10.
1. A punch unit comprising a punch driver (24) connected with the back end of a punch
(10) by means of a threaded connection (25, 26), releasable safeguarding members (36,
38) preventing relative rotation between said punch (10) and said punch driver (24)
during a stroke of said punch (10), and a compression spring (34) which is pre-loaded
between a base (32) at the back end of the punch driver (24) and a spring bearing
(30) disposed thereon and which during a stroke of said punch is compressible between
the base (32) and a guide bushing (12) which receives the punch (10) in an axially
displaceable manner, characterized in that the guide bushing (12) receives the punch (10) in a non-rotatable manner and the
safeguarding members (36, 38) are formed by an engagement interlocking in the circumferential
direction between said punch driver (24) and said guide bushing (12) in at least one
relative angular position in the axial area between the exterior back edge of the
punch (10) being in contact with an inner wall of the guide bushing (12) and the compression
spring (34).
2. The punch unit according to claim 1 wherein said safeguarding members (36, 38) comprise
at least one radial protrusion (38) axially arranged on said punch driver (24) between
said back edge of said punch (10) and said compression spring (34) and at least one
axial groove (36) in said guide bushing (12), said axial groove (36) being open at
said open end of said guide bushing (12).
3. The punch unit according to claim 2 wherein said spring bearing (30) comprises a set
collar (28) which is attachable by a threaded connection (26) to said punch driver
(24).
4. The punch unit according to claim 3 wherein said radial protrusion (38) comprises
a pin inserted into a radial hole in said set collar (28).
5. The punch unit according to claim 3 further comprising an intermediate ring (30) seated
on said punch driver (24) between said set collar (28) and said compression spring
(34), said intermediate ring (30) being axially supported on said set collar (28)
and on said guide bushing (12) and having, on an exterior circumferential face, a
radially protruding O-ring (40) which rests against an interior wall of said guide
bushing (12) when said radial protrusion (38) is in said axial groove (36), said O-ring
(40) being frictionally engageable with and axially releasable from said interior
wall.
6. The punch unit according to claim 2 wherein said guide bushing (12) includes more
than one axial groove (36) and said radial protrusion (38) or protrusions on said
punch driver (24) are fewer in number than said axial grooves (36).
7. The punch unit according to claim 2 wherein said axial grooves (36) are slightly longer
than the length of linear movement between said punch (10) and said guide bushing
(12) during a stroke of said punch (10).
8. The punch unit according to claim 2 wherein said punch driver (24) includes a shoulder,
said punch driver (24) and shoulder comprising a single-piece construction, said radial
protrusion (38) being mounted on said shoulder.
1. Stanzstempeleinheit mit einem Stempeltreiber (24), der mit dem hinteren Ende eines
Stempels (10) durch eine Gewindeverbindung (25, 26) verbunden ist, lösbaren Sicherungselementen
(36, 38), die eine Relativdrehung zwischen dem Stempel (10) und dem Stempeltreiber
(24) während eines Hubes des Stempels (10) verhindern, und einer Druckfeder (34),
die mit Vorspannung zwischen einem Kopf (32) am hinteren Ende des Stempeltreibers
(24) und einem an diesem angeordneten Federlager (30) eingespannt ist und während
eines Hubes des Stempels zwischen dem Kopf (32) und einer den Stempel (10) axial verschieblich
aufnehmenden Führungsbuchse (12) komprimierbar ist, dadurch gekennzeichnet, daß die Führungsbuchse (12) den Stempel (10) in unverdrehbarer Weise aufnimmt und die
Sicherungselemente (36, 38) einen formschlüssigen Eingriff in der Umfangsrichtung
zwischen dem Stempeltreiber (24) und der Führungsbuchse (12) in wenigstens einer relativen
Winkelstellung in einem Axialbereich zwischen der mit der Innenwandung der Führungsbuchse
(12) in Kontakt befindlichen, äußeren rückwärtigen Kante des Stempels (10) und der
Druckfeder (34) aufweisen.
2. Stanzstempeleinheit nach Anspruch 1, dadurch gekennzeichnet, daß die Sicherungselemente (36, 38) wenigstens einen am Stempeltreiber (24) zwischen
der Hinterkante des Stempels (10) und der Druckfeder (34) axial angeordneten Radialvorsprung
(38) und wenigstens eine Axialnut (36) in der Führungsbuchse (12) aufweisen, wobei
die Axialnut (36) am offenen Ende der Führungsbuchse (12) offen ist.
3. Stanzstempeleinheit nach Anspruch 2, dadurch gekennzeichnet, daß das Federlager einen Stellkragen (28) aufweist, der durch eine Gewindeverbindung
(26) an dem Stempeltreiber (24) anbringbar ist.
4. Stanzstempeleinheit nach Anspruch 3, dadurch gekennzeichnet, daß der Radialvorsprung (38) einen Stift aufweist, der in eine Radialbohrung in dem Stellkragen
(28) eingesetzt ist.
5. Stanzstempeleinheit nach Anspruch 3, dadurch gekennzeichnet, daß auf dem Stempeltreiber (24) zwischen dem Stellkragen (28) und der Druckfeder (34)
ein Zwischenring (30) sitzt, der axial an dem Stellkragen (28) und an der Führungsbuchse
(12) abgestützt ist und auf seiner äußeren Umfangsfläche einen radial vorspringenden
O-Ring (40) aufweist, der an der Innenwandung der Führungsbuchse (12) anliegt, wenn
der Radialvorsprung (38) sich in der Axialnut (36) befindet, wobei der O-Ring (40)
reibschlüssig an der Innenwandung liegt und axial von dieser lösbar ist.
6. Stanzstempeleinheit nach Anspruch 2, dadurch gekennzeichnet, daß die Führungsbuchse (12) mehr als eine Axialnut (36) umfaßt und weniger Radialvorsprünge
(38) als Axialnuten (36) vorgesehen sind.
7. Stanzstempeleinheit nach Anspruch 2, dadurch gekennzeichnet, daß die Axialnuten (36) geringfügig länger als die Länge der Linearbewegung zwischen
dem Stempel (10) und der Führungsbuchse (12) während eines Hubes des Stempels (10)
sind.
8. Stanzstempeleinheit nach Anspruch 2, dadurch gekennzeichnet, daß der Stempeltreiber (24) einen Absatz aufweist, wobei der Stempeltreiber (24) und
der Absatz eine einstückige Konstruktion bilden und der Radialvorsprung (38) an dem
Absatz angebracht ist.
1. Unité de poinçonnage comprenant un guide de poinçon (24) relié à l'extrémité arrière
d'un poinçon (10) au moyen d'une liaison filetée (25, 26), des éléments de garde de
sécurité amovibles (36, 38) empêchant une rotation relative entre le poinçon (10)
et le guide de poinçon (24) pendant une course du poinçon (10), et un ressort de compression
(34) pré-chargé entre une base (32) à l'extrémité arrière du guide de poinçon (24)
et un support de ressort (30) disposé sur celui-ci et qui, pendant une course du poinçon,
peut être comprimé entre la base (32) et un coussinet de guidage (12) recevant le
poinçon (10) d'une manière déplaçable axialement,
caractérisée en ce que
le coussinet de guidage (12) reçoit le poinçon (10) d'une manière non rotative, et
les éléments de garde de sécurité (36, 38) sont formés par un enclenchement d'engagement
dans la direction circonférentielle, entre le guide de poinçon (24) et le coussinet
de guidage (12) dans au moins une position angulaire relative dans la zone axiale
entre le bord arrière extérieur du poinçon (10) en contact avec une paroi intérieure
du coussinet de guidage (12), et le ressort de compression (34).
2. Unité de poinçonnage selon la revendication 1,
caractérisée en ce que
les éléments de garde de sécurité (36, 38) comprennent au moins une saillie radiale
(38) disposée axialement sur le guide de poinçon (24) entre le bord arrière du poinçon
(10) et le ressort de compression (34), ainsi qu'au moins une rainure axiale (36)
dans le coussinet de guidage (12), cette rainure axiale (36) étant ouverte à l'extrémité
ouverte du coussinet de guidage (12).
3. Unité de poinçonnage selon la revendication 2,
caractérisée en ce que
le support de ressort (30) comprend un collier de réglage (28) pouvant être fixé par
une liaison filetée (26) au guide de poinçon (24).
4. Unité de poinçonnage selon la revendication 3,
caractérisée en ce que
la saillie radiale (38) comprend une broche introduite dans un trou radial du collier
de réglage (28).
5. Unité de poinçonnage selon la revendication 3,
comprenant en outre un anneau intermédiaire (30) logé sur le guide de poinçon (24)
entre le collier de réglage (28) et le ressort de compression (34), cet anneau intermédiaire
(30) étant monté axialement sur le collier de réglage (28) et sur le coussinet de
guidage (12), en comportant, sur une face circonférentielle extérieure, un joint torique
faisant saillie radialement (40) qui repose contre une paroi intérieure du coussinet
de guidage (12) lorsque la saillie radiale (38) se trouve dans la rainure axiale (36),
le joint torique (40) pouvant s'engager en frottement et d'une manière axialement
amovible contre la paroi intérieure.
6. Unité de poinçonnage selon la revendication 2,
caractérisée en ce que
le coussinet de guidage (12) comprend plus d'une seule rainure axiale (36), et la
ou les saillies radiales (38) formées sur le guide de poinçon (24) sont en plus petit
nombre que les rainures axiales (36).
7. Unité de poinçonnage selon la revendication 2,
caractérisée en ce que
les rainures axiales (36) sont légèrement plus longues que la longueur du mouvement
linéaire entre le poinçon (10) et le coussinet de guidage (12) pendant une course
du poinçon (10).
8. Unité de poinçonnage selon la revendication 2,
caractérisée en ce que
le guide de poinçon (24) comprend un épaulement, ce guide de poinçon (24) et l'épaulement
constituant une construction d'une seule pièce, la saillie radiale (38) étant montée
sur l'épaulement.