Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
- ~0685~6
h,
The present invention relates to an assembly adapted
for use in substantially increasing the accuracy of a reusable
type punching system features a floating locater or guide
templet and associated stripper-punch tip guide element to
accurately, positionally locate a punch relative to an :
associated die part.
BACKGROUND OF THE INVENTION
Prior U.S. Patent 3,125,917 discloses a punch and
10 die assembly comprising upper and lower plates or templets ~:~
serving to positionally locate the upper and lower ends of -.
punch and die elements in supported engagement with punch aid .
die shoes, respectively, an intermediate plate or templet fixed ` .
~ .".
C
~068596
to the die shoe via lower portions of shoe guide device and
serving to positionally locate the dies of the die elements;
and a moveable plate means or locater templet means movably
suspended below the punch shoe via upper portions of the punch
shoe guide devices and carrying a plurality of guide elements
or buttons having openings sized to slideably recelve the
punching or tip ends of the punch elements in order to orient
same relative to their associated dies. Stripper devices in
the form of coil type compression springs dispose concentrically
of the die elements for opposite end bearing engagement with
a lower surface of the upper plate and an upper surface of an
associated guide button. The spring devices, working through --
the guide buttons, additionally function to normally bias remov-
able plate means to bottom out against an abutment defined by
upper portions of a shoe guide devices.
In one embodiment of the assembly, lower surfaces of
the guide buttons project below a lower surface of the moveable
plate means for stripping engagement with a workpiece.
The moveable plate means is illustrated and described
as including two or more identical plates or templets, which
are clamped in surface-to-surface engagement and appear to
individually be of a thickness corresponding t~ that of the
upper, lower and intermediate plates, such thickness being
as to permit punch forming of the guide or locater apertureS
1068596 ~ ~
in such plates. Apparently, as workpieces of increasing
thickness are to be punched, the number of plates comprising
the moveable plate means must be increased for stiffening pur-
poses.
; Applicant became aware of U.S. Pat. No. 3,125,917 as
; a result of prosecution of his above mentioned patent application, ~
and subsequently conducted tests in an effort to compare the ~-
performance capabilities of the patented system with those of the --
system disclosed in his application.
In that the patented system was not available for test
purposes~ Applicant's system was modified in an effort to
simulate operational conditions of the patented system. In this
respect, Applicant's die set was modified by removing stripper
sleeves 138, and by modifying pin support devices 82j such that
they supported templet 80 to position guide elements or buttons 90
in essential surface-to-surface abutting engagement with the
lower ends of stripper sleeves 60, when the punch shoe 20 is
disposed in an operative or die set open condition. As modified
pin supports 82 and strlpper sleeves 60 are believed to function-
~, 20 ally replace the abutment device defined by said screw 47 and ;
shoulder 40 and stripping springs 65 of the system disclosed in
, U.S. Pat. No. 3,125,917.
~,', ".
.. ', ~ '~ .
. . ,. i
:
. .
.
~ iO68596
For reference test ~urposes, die set illustrated in
Applicant's application was set up to ensure that the spacing
between guide sleeves 126 and guide bushings 132 permitted com-
pression o stripper sleeves 138 no later than stripper sleeves
60, when a stock or workpiece thickness of 0.1 inch was being :~
punched; this dictating that the initial spacing of approximately . .
0.1 inch is present between the bottom of stripper sleeves 60 ~.
and the upper surfaces of their associated guide buttons 90,
when the latter are fully seated relative to templet 80.
- . .
. 10 A series of four reference tests were conducted with
first and second tests using 0.001 inch thick stock or workpiece
material and difering from one another only in that in a first
test the stock was "full-sized" to permit all punches to be :
simultaneously operative and in a second test the stock was
"half-sized", so that only one half of the punches arranged on .
one side or half of the die set were operative. The third
and fourth tests were conducted using 0.1 inch thick stock or
workpiece material with the "full and half sized" punching
. , .
- conditions of the first and second tests being repeated, respec-
tively. Results of the referenced tests demonstrated the sub-
stantially increased accuracy described in Applicant's patent
application~
~ .
'
.: .
' ' '
~. 30
:
'' . '
- ,
.: -4-
- 1(~68596 - ~
A series of four comparison tests were conducted ~
- using Applicantls die set modified in the manner described -
above with stock thicknesses and sizes identical to those used ~`-
in the referenced tests. In conducting the comparison tests, -
the same punch and die elements were used, as those used in the
referenced tests; such punch and die elements having been
inspected prior to conducting the comparison tests and no damage
or wear being noted as a result of the reference tests. Also,
in conducting the comparison tests, the single, thin locater
- 10 templet used in referencs tests was used in place of the
multiple thickness moveable plate means disclosed in U.S. Pat.
No. 3,125,917.
The results of the first three comparison tests were
found to be comparable to the results of the first three
; reference tests. Howe~er, when the fourth comparison test was
conducted on 0.1 inch stock, using a "half-size" workpiece, it
was found that the punch tips of the operative punches failed
during the first press stroke; such failure being in the form
of a shearing away of a portion of the cutting edge or corner
of each of the operable punches, due to misalignment between
such operable punches and their assorted dies. A sheared portion
=~ of the punches was left, as a deposit on the workpiece, and its
~ presence was readily detectable by visual observation.
' .
~ ' '
,:
-
'.
.
~' '
; _5_
." ' .
' ' ~
1068596 - ~
Failure of punches during the fourth comparison test -~
is attributable to "cocking" or the non-parallel relationship
of the guide templet xelative to the die templet, during the
punching operation. This results from failure of the prior
patented system to provide support, i.e. clamp, to corners of
the guide templet prior to compression of the stripped sleeves
associated with the punches.
- The reason for conducting the second and forth tests
using "half-sized" workpieces, and thus rendering only one half
, . . ~ .
' lO of the available punches operative at a given time, was to
permit simulation of "multi-station" operation of the die set.
In this connection, it will be understood that it is conventional
to design a single die set with its punches and die elements
;~; arranged to create multiple stations, whenever it is desirable
to provide for multiple hits to be performed on a single work-
piece, as when the holes required to be formed in such work-
piece are too close together to permit punching in a single
operation, or where it is desired to punch different hole
patterns in a plurality of small workpieces, which may vary in
thickness, within a single press.
. SUMM~R~ OF THE INVENT ION
The present invention is directed toward a system
adapted to substantially increase the accuracy of or reduce the
center-to-center tolerances achievable with reusable punching
systems of the type disclosed for instance in V.S. Pat. Nos.
2,364,834; 3,089,376; and 3,782,186.
. '` .
,...
3o
:.
.; .
:.
-6-
.
. -
.. ..
68596
According to the prevent invention there is provided in
a system for punching workpieces including a die set including
punch and die shoes, said punch shoe being mounted for vertical ~
. movement relative to said die shoe between open and closed positions; `
... . .
a punch templet in the form of a metal plate fixed to said punch
shoe having a plurality of guide openings and a plurality of
- retainer openings; a die templet in the form of a metal plate
fixed to said die shoe and having a plurality of guide openings _:
and a plurality of retainer openings, the pattern and center-to-
. 10 center spacing between said openings of said punch and die templets `
being equal and associated ones of said openings of said punch and
die templets being disposed in vertical alignment; a plurality of
s~: '
punch parts positionally located one within each of said punch
: templet retainer openings, each of said punch parts including a
punch fixed within its associated punch templet retainer opening .
and a resiliently deformable stripper device, said punch extending
towards said die templet and terminating in a punch tip; a plura-
.. . . .
lity of die parts positionally located one within each of said die
templet retainer openings and associated one with each of said
, 20 punch parts, each of said die parts including a die bushing formed
with an opening sized and shaped to receive said punch tip of an :
: associated punch part for effecting punching of said workpieces in
: alignment therewith during movement of said shoes into said closed
... .
position; a guide templet having a plurality of guide openings and
a plurality of locat~r openings characterized as having a pattern :-~
and center-to-center spacing equal to said guide and retainer
openings of said punch and die templets; a plurality of guide
elements slidably received one within each of said locator openings
for association one with each of said punch parts, each of said :.
guide elements having an upper surface, a lower surface, a supporting
portion and a guide opening sized and shaped to slidably receive
said punch tip of its associated punch part, said guide elements
.. .
.~. - 7 -
:, .
,, ~ : ,~ , : : .
. ~ . , . -
1~368596
`~eing insertable into their associated locator openings to place
said supporting portion in engagement with an upper surface of said
guide templet and said lower surface relatively below a lower sur-
face of said guide templet; supporting means for normally su~pending
said guide templet from said punch shoe for vertical movement there-
with while permitting movement of said punch templet relative to
said guide templet when it is in a lower-operative position thereof,
: said guide templet being arranged horizontally intermediate said
punch and die templets with each of said guide elements positionally
i 10 locating said punch tip of its assocaited punch part within the
guide opening thereof and being arranged for upper and lower surface
engagement with said stripper device of its associated punch part
and said workpieces arranged in alignment therewith, respectively,
during movement of said punch shoe towards closed position and a
plurality of guide assemblies, each of said guide assemblies inclu-
ding a guide pin having an upper end portion fixed to said punch
sh~e and a lower end portion, a guide sleeve fixed to said die shoe
and a guide bushing, said guide sleeve and said guide bushing having
centrally located guide openings sized to slidably receive said
20 lower end portion of said guide pin, said upper end portion of said
; guide pin, said guide sleeve and said guide bushing being position-
ally located within associated ones of said guide openings of said
. punch, die and guide templets, respectively, characterized in that
receipt of the guide pin lower end portions within their associated
guide sleeve openings at least during a portion of the movement of
said punch shoe towards closed position serves to vertically align
~: said guide openings of said guide templet with said guide openings
of said die templet, whereby said guide templet and said guide
elements are operative to position the punch tips in vertical
alignment with the openings of their associated die bushings, the
. improvement in combination for punching workpieces ranging in
thickness up to a maximum thickness and selectivity in a single or
:
. L
~ ~ - 7a -
~68596
`, :.multiple station operation; said guide templet is in the form of a
metal plate having a tllickness corresponding to the thickness of :
said plates forming said punch and die templets, said guide templet
when suspended by said supporting means spacing said upper surface .:
of each of said guide elements from its associated stripper device
through a distance essentially equal to said maximum thickness,
when the supporting portions of said guide elements engage with an
upper surface of said guide templets, said guide pin of each of
said guide assemblies is of stepped diameter having a relatively
large diameter upper end portion and a lower relatively small
diameter end portion, and each of said guide assemblies additionally
includes a resiliently deformable stripper device arranged for
opposite end engagement with said upper end portion of said guide
pin and said guide bushing, said guide bushing being engagable
with their associated guide sleeves during a further portion of
movement o~ said punch shoe towards closed position to arrest
moVement of said guide templet relative to said die templet to
define said lower-operative position of said guide templet and to -~
initiate deformation of said stripper device of each said guide :.
assembly, said distance between said upper surface of each of said -~
guide elements and its associated stripper device accommodating
for engagement therebetween and initiation of resilient deformation
. .: ,. .of such stripper device during movement of said punch shoe towards
closed position no sooner than initiation of deformation of the
stripper devices of said guide assemblies, and said punch tips
`~ being forced to move relative to said guide elements and into said
: openings of their associated die bushings to effect punching of
"
said workpiece, during a still further portion of the movement of
said punch shoe into closed position.
The present invention provides the means for intercon-
necting said punch, die and guide templets includes a plurality of
guide assemblies, each of said guide assemblies including a stepped
,`'',' '~
"
~ 7b -
.
` ` 1~68596
diameter guide pin having a relatively large diameter upper end
portion fixed to said punch shoe and a lower relatively small .
diameter end portion, a guide sleeve fixed to said die shoe and
slidably receiving said lower end portions, a guide bushing slidably --
~supported on said lower end portion and a resiliently deformable
stripper device arranged for opposite end engagement with said
upper end portion of said guide pin and said guide bushing, said
upper end portion of said guide pin, said guide sleeve, and said
guide bushing being positionally located within aligned guide
openings formed in said punch, die and guide templet, respectively,
the guide bushings of said guide assemblies being maintained at
least in proximate surface engagement with their associated
stripper devices by said guide templet when suspended in said rest
position, and said guide bushings engaging with their associated
guide sleeves to arrest movement of said guide templet.
The present invention still further provides a method of
increasing the accuracy of a conventional reusable system employed
in the punching of workpieces, having a given range of thicknesses
up to and including a maximum thickness in either a single or
multiple station operation, wherein said reusable syst.em includes
in combination punch and die shoes wherein said punch shoe is
mounted for vertical movement relative to said die shoe between
open and closed positions; a punch templet, said punch templet
having a plurality of retainer openings; a die templet, said die :-
templet having a plurality of retainer openings arranged in a
pattern and center-to-center spacing corresponding to the pattern ~;
and center-to-center spacing of said retainer openings of said
punch templet; means to fix said punch and die templet to said
punch and die shoes, respectively, whereby to arrange associated
ones of said retainer openings of said punch and die templets in
vertical alignment; a plurality of punch parts positionally located
one within each of said punch templet retainer openings, each of .
.
,:"', ~$
- 7c -
.,
s ` 1068596
said punch parts including a punch and a resiliently deformable
stripper device disposed concentrically of said punch, said punch
having an upper end centrally located within its associated retainer .-
opening and extending in a direction towards said die templet to
terminate in a punch tip extending below said stripper device; a --
plurality of die parts positionally located one within each of said .
die templet retainer openings in vertical alignment with an assoc-
.: iated one of said punch parts, each of said die parts including a
die bushing formed with a centrally located opening sized and shaped
to receive a punch tip of an associated punch part, associated ones
of said punch and die parts having their punch tips and die bushing
openings vertically aligned to a degree sufficient to effect -.
punching of said workpiece when arranged intermediate said punch ' :
and die templets during movement of said punch shoe into said
: closed position; a guide templet fabricated simultaneously with
said pun~h and die templets by stacking said punch, guide and die
templets in juxtaposition and simultaneously forming a plurality
. of aligned guide openings in the stackedtemplets and simultaneously
forming a plurality of other aligned openings in the stacked templets
wherein associated ones of said other openings of said templets
define said retainer openings of said punch and die templets and
locator openings of said guide templet, wherein the pattern and
center-to-center spacing of said guide and retainer openings of
said punch and die templets is identical to the pattern and center-
,
to-center spacing of said guide and locator openings of said guide
temple-t; and a plurality of guide elements slide fitted one within
. each of said locator openings, each of said guide elements having .
.. a supporting portion and a through guide opening sized and shaped
to slidably receive an associated one of said punch tips determined
3Q by that one of said punch parts received within that one of said
retainer openings with which its locator opening is associated,
said method comprising the steps of providing a relatively tight
.~' ~
.
~ 1068596
. slide fit for said guide elements within their associated locator
openings; arranging said guide templet intermediate said punch and
guide templets at least when said punch shoe is in said open posi-
tion to insert said punch tips within their associated guide element
openings and to provide for initial vertical spacing between said
guide elements when said supporting portion is engaged with an
upper surface of said guide templet and said stripper devices
essentially equal to said maximum thickness; moving said guide
templet with said punch templet downwardly towards said die templet
as said punch shoe is moved towards closed position sufficiently to
bring lower su.rfaces of said guide elements into engagement with
said workpieces when aligned therewith and effect sliding movement
.~ of engaged ones of said guide e~ements upwardly within said locator
openings through a distance correspoinding essentially to the
: thickness of said workpieces with which they engage, whereby
engaged ones of said guide elements are caused to assume operative
,~, positions thereof; locating said guide openings of said guide
- templet in vertical alignment with said guide openings of said "
die templet at least during the step of moving said guide templet
towards said die templet and prior to movement of said guide
. elements into said operative positions thereof, whereby to locate
said punch tips in vertical alignment with their associated die
bushing openings; continuing movement of said punch shoe into
closed positior through a vertical distance sufficient to effect
resilient deformation of said stripper devices due to engagement
with their associated engaged ones of said guide elements and to
'- force said punch tips to project downwardly below their associated
guide elements to effect punching of said workpieces when aligned
~ therewith; arresting movement of said guide templet relative to
.` 30 said die templet during said continuing movement of said punch shoe
no later than initiation of resilient deformation of said stripper
devices and continuing to arrest movement of said guide templet
'',: .
... . . .
- -` 1068596 ` -
relative to said die templet during return movement of said punch
shoe towards open position at least until termination of resilient -
deformation of said stripper devices; and thereafter lifting said
guide templet for movement with said punch templet during continued
movement of said punch shoe into open position, characterized in
that said guide elements tend to remain in said operative positions
thereof during subsequent closing and opening movements of said
punch shoe for performing punching operations on successive work- _ -
pieces of the same thickness.
In particular, the present invention features the provi-
sion of a floating locat~r or guide templet, which is adapted to be
positioned intermediate the punch and die templets of a die set and
serves to positionally locate and slideably support a stripper-punch
tip guide element or but for free floating movement normal to the
plane of the locator templet. The guide element is formed with a
~- through opening sized to slideably receive the tip end of a punch
element and arranged for opposite surface engagement with a
resiliently deformable stripper sleeve and a workpiece to be punched.
, .
The locator or guide templet is in the form of a single thicknessmetal
plate, whose thickness corresponds essentially to the thickness of
the punch and die templets.
During a punching operation, corner located guide assem-
; blies serve to positionally located the locator templet relative to
the punch and die templets, whereby to provide for accurate align-
ment of the tip ends of the punch element relative to their associ-
ated dles.
The present system employs stripper sleeve disposed con-
centrically of the guide assemblies for bearing engagement with the
locator templet and strippersleeves disposed concentrically of the
punch elements for bearing engagement with guide elements or stripper
buttons. The parts are sized to insure substantially simultaneous
compression of both sets of
- 7f -
1068596
stripper sleeves when a given ~aximum thickness workpiece is
being punched and to provide an initial spacing between the
lower ends of the stripper sleeves surrounding the punch
elements and the upper surfaces of their associated guide elements,
when fuIly seated relative to the locater templet, correspond-
ing essentially to such maximum thickness. Thus, when a work-
piece being punched is of a thickness less than such maximum
thickness, compression of the stripper sleeves associated with
the guide assemblies is initiated before compression of the
stripper sleeves associated with the punch elements. In all
; cases, the guide elements move vertically relative to the
: locater templet by an amount equal to the thickness of the work- ;~
piece being punched thereby and remain in such displaced position
; during punching of subsequent workpieces of like thickness.
Utilization of an assembly formed in accordance with
the present invention in an otherwise conventional reusable
punching system permits reduction in obtainable center-to-center
tolerances from about plus or minus 0.005 inch to about plus or
,.. ~. ,
minus 0.001 inch, and therefore greatly increases the versatility -~
of such conventional system.
Moreover, the system of the present invention consti-
tues an improvement over that described in U.S. Pat. No. 3,125,
917 from the standpoint, that is capable of being employed to
perform either single or multiple station punching operations
on workpieces of substantially varying thickness without resort
- to thick or multiple piece locater templets.
RAWINGS
The nature and mode of operation of the present inven-
tion will now be more fully described in the following detailed
description taken with the accompanying drawings whérein:
Fig. 1 is a perspective view of a press in open condi-
tion showing the assembly of the present invention employed with
, ,
:' ~
.. . . .. .
1068596 `
a conventional reusable type system;
: Fig. 2 is a partially sectionalized side elevational
- view taken generally alon~ the line 2-2 in Fig. l; and
` Fig. 3 is a view similar to Fig. 2, but showing the
press in closed condition.
DET~ILED DESCRIPTION
Reference is first made particularly to Fig. 1,
wherein a die set is generally designated as 10 and shown as
mounting therewithin assembled, reusable punch and die units
12 and 14, respectively, and a close tolerance punching assembly,
which is formed in accordance with the present invention and
generally designated as 16. A workpiece, such as a piece of
: sheet metal, on which a punching operation is to be performed,
~' is generally designated at 18.
i .
Now makIng reference to`Fi~s 1-3, it will be
" ,
understood that die set 10 is conventional from the standpoint
that it includes a punch shoe 20, which is adapted to be suitably
secured to a press ram 22; a die shoe 24, which is adapted to
, .,
~ be suitably secured to a press bolster 26; a plurality of shoe
~,......................................................................... .
guide assemblies 28, which include die shoe mounted guide posts
30 and punch shoe mounted guide post receiving bushings 32.
Punch and die units 12 and 14 are conventional from
- the standpoint that they include punch and die templets 34 and
36, which are in the form of flat metal plates removably secured
or attached to punch and die shoes 20 and 24. In the illustrated
construction, clampin~ devices in the form of posts 38 and 40
threadably attached to the punch and die shoes and templet clamp-
ing screw devices 38a and 40a loosely received within punch and
die templet openings 34a and 36a are employed to secure the
templets to their respective shoes. Punch anddie units 12 and
14 are also shown as including cooperating pairs of punch and die
parts 42 and 44, which are positionally located for relatlve
, `
_g _
': .
~)68S96 ` .
'." '
vertical alignment b~ retainer openings or holes 46 and 48
formed in the punch and die temylets. Die unit 14 would
normally include a plurality of gauge members 50, which are
fixed to upstand from die templet 36 and serve to positionally
locate workpiece 18 relative to the punch and die parts during
a punching operation. It will be understood that the specific
design of the punch and die unlts will vary with press setup
requirements and may incorporate diverse cooperating pairs of
; metal forming parts, such as may be required to additionally
permit embossing, lancing, ~orming, severing etc. of workpiece ;
18.
By now referring to Figs. 2 and 3, it will be under-
stood that each of punch parts 42 would normally include a
punch holder 52, which is positionally located by punch templet -
opening 46 and in turn formed with a centrally located opening
52a sized to receive the upper end portion of a punch 54; and -
a stripper device 56, which includes a header 58 and a dependent,
resiliently deformable stripper sleeve 60. Punch holder 52 may
be releasably attached to punch shoe 20 by a magnet device, not
shown, and suitable means, such as set screws 62 and 64, may
be employed to releasably clamp punch 54 relative to punch
holder 52 and header 58, respectively. Further, each of die
parts 44 would normally include a die holder or body portion 70,
- which is shaped to supportingly receive a die bushing 72 having
a centrally located opening 74 sized and shaped to receive the
tip or punching end portion 76 of punch 54. Die bushing 72
is positionally located by die templet opening 48, and the force
of gravity is normally employed to maintain die holder 70 in
supported engagement with the upwardly facing surface of die
shoe 24.
It will be understood that reusable punching systems
of the type thus far described are conventional and disclosed,
1 0--
.~ . . , . . -, . ........................... .. . .
.. , . . . -. ,. .. . , . . ... :, . :
- 10685g6
as by way of example, in U.S. Pat, Nos. 3,089!376 and 3,782,166
whose disclosures are incorporated herein by reference. It
will be also understood that with reusable systems of this
type, the above described locater devices are employed to
vertically align templet openings 46 and 48, such that the
` punches and die bushings positioned thereby are arranged in
vertical alignment to a degree sufficient to permit the simul-
taneous punching of multiple holes in workpiece 18 upon converg-
ing movement of punch and die shoes 20 and 24 from their open
position shown in Fig. 2 into their closed position shown in
Fig. 3.
; As a practical matter, the characteristics of reusable
~, , .
systems are such as to prevent a punching operation from being
~; perormed with the same accuracy as a conventional "ixed"
punching system, and thus reusable systems are not now recom-
mended for use where center-to-center tolerances below about
plus or minus 0.005 inch must be maintained. Further, with pre-
sent reusable systems, it is difficult to maintain concentricity
between the punch tip and opening of the die bushing and thus
it is normally necessary to provide a relatively "loose" 0.003
inch total tolerance between these elements. The lack of con-
centricity between these elements and their relatively "loose"
fitting relationship has heretofore prevented reusable systems
from being employed in the punching of sheet materials having
thicknesses below about 0.023-0.024 inch.
... .
Reference is again made to Figs. 1-3, wherein a close
.":'
tolerance punching assembly 16 formed in accordance with the
present invention is shown as including a guide or locater tem-
plet 80 in the form of a flat metal plate, which is sized to
extend essentially coextensive with punch and die templets
34 and 36. Guide templet 80 is best shown in Figs. 2 and 3 as
: being loosely suspended from punch templet 34 to lie essentially
.:
.. ' --11--
- .:
1068S96
.'
par~llel and vertically intermediate the punch and die templets
by a plurality of supporting plns 82, which loosely extend
through openings 84 and 86 in the punch and guide templets '- -
and have their opposite ends fitted with snap ring retainers 88.
Assembly 16 additionally includes a plurality of strip~
per-punch tip guide elements or buttons 90, which are slidably
received within locator openings 92 of guide templet 80; and
a plurality of guide assemblies 94, which are received within
guide openings 96, 98 and 100 of templets 34, 80 and 36, ~-
respectively.
Guide elements 90 are shown in Figs.2 and 3 as being
formed with a centrally located guide opening 102, which is
sized and shaped to slidably receive punch tip 76; and an
enlarged upper rim portion 104, which serves to prevent move-
ment of the guide elements downwardly through their associated
locator openings 92. As will be apparent from viewing Figs. 2
and 3, the upper and lower surfaces of guide elements 90 are
arranged for engagement with the lower ends of the stripper
sleeves 60 of the punch parts with which they are associated
and workpiece 18, respectiveiy.
` Guide assemblies 94 are also best shown in Figs. 2
and 3 as generally including a stepped diameter guide pin 120
having a relatively small diameter lower end portion 120a and a
relatively large diameter upper end portion 120b, which is
positionally received within punch templet guide opening 96
and removably adjustably fixed to punch shoe 20 by means of a
spacer device 122 and clamping bolt 124; a guide sleeve 126,
;- which is positionally received with die templet guide opening
100 and removably adjustably fixed to die shoe 24 by means of
spacer device 128 and clamping bolt 130; a guide bushing 132,
which is positionally located within guide templet guide opening
98; and a stripper device 134, which is disposed concentrically
:',
: -12-
` 1068596
.:
of guide pin lower end portion 120a and vertically intermediate
guide pin upper end portion 120b and guide bushing 132. Guide
sleeve 126 and ~uide bushing 132 are formed with centrally
located guide openings 126a and 132a, respectively, which are
sized to slidably receive guide pin lower end portion 120a.
.
Guide bushing 132 may, if desired, be releasably constrained
against axial movement within guide templet guide opening 98 by
means of a snap ring retainer 136.
Stripper device 134 is shown as including a resiliently
deformable stripper sleeve 138 having its ends snap-fitted or
otherwise fixed to a pair of end bearing caps 140, such device
being suitably removably fixed to guide pin 120, as by a set
screw 142. Preferably, stripper sleeves 60 and 138 would be
formed from the same resiliently deformable material and possess
essentially the same resistance to deormation.
In accordance with a preferred form of the present
invention, a user would be supplied with "blank" punch, die and
guide templets of essentially like thickness on the order of
about 0.164 inch, wherein the punch, die and guide templets are
accurately pre-bored to define guide openings 96, 100 and 98,
respectively. The user would complete the manufacturing opera-
tion by stacking the templets and then inserting conventional
templet clamping plugs, not shown, through associated ones of
guide openings 96, 100 and 98 in order to clamp the templets in
juxtaposition and place associated ones of the guide openings
in accurate vertical alignment, and finally boring the clamped
.:
templets to form associated ones of openings 46, 48 and 92, in
.:.
` a number, size and pattern determined by press setup requirements.
Fabrication o~ the templets In this manner serves to eliminate
horizontal or center-to-center tolerances between their respective
~4
holes. Openings 34a, 36a, 84 and 86 may be provided in the
'Iblank'' templets or subsequently bored by the user, as desired.
-13-
.-
11:)68596
Alternatively, the punch, die and guide templets may be sup-
plied to a user with all holes pre~bored. `
The punch and die units would then be assembled and
the punch and die templets fixed to the punch and die shoes using
conventional installation techniques in order to arrange
associated ones of retainer openings 46 and 48 and associated
ones of guide openings 96 and 100 in accurate vertical alignment.
More specifically, the asse~bled punch unit is lifted tc place : -
guide pin upper end portions 120b within guide openings 96, and
the punch unit firmly clamped in place by means of clamping
scr~ws 38a. The assembled die units is then lowered to insert
guide sleeves 126 within guide openings 100, and the die unit -
firmly clamped in place by means of clamping screws 40a.
Installation of the assembled punch and die units in this manner
serves to essentially align punch tips 76 with their associated
die bushing openings74 and guide pin end portion 120a with guide -~
sleeve opening 126a. Conventional techni~ues may be employed
to provide for accurate alignment of guide pins 120 and guide
' sleeves 126.
It will be understood that guicle pin upper end portions
120b and guide sleeves 126 functionally replace locator bushings
used in prior reusable systems to align the punch and die tem-
plets; such bushings having been formed with ~hreaded openings
in their facing ends to receive clamping screws identical in
function to clamping screws 38a and 3~b. Thus, an important
, .
feature of the invention ls that customers may have their pre-
sent reusable systems modified to accommodate assemblv 16 by
, " .
simply replacing their locator bushings with the guide pin and
- the guide sleeve of the present invention. It is further en-
visioned that the illustrated holder post and clamping screw
arrangement may be dispensed with in favor of guide pin ;:nd guide
sleeve mounted snap ring retainers, not shown, arranged to engage
-14-
` 1068596
.
with the lower and uppex surfaces of the punch and guide
templets, respectively.
Assembly 16 is completed by attaching stripper de-
vices 134 to their associated gui~e pins 120; inserting guide
elements 90 and guide bushings 132 w~thin their associated
templet openings 92 and 98; placing guid~- templet 80 within die
set 10, while t is in its open condition, shown in Fig. 2,
, and elevating the guide templet to successively insert guide pin
lower ends 120a within guide bushing openings 132a and punch
tips 76 within guide element openings 102; and finally suspend-
ing the guide templet from punch templet 34 by means of support~
ing pins 82.
Upon completion of the punch setup operation described
abo~e, the several parts of the reusable system incorporating
the present invention initially assume the respective positions
shown in Fig. 2. At this point it will be understood that an
initia~ spacing exists between the upper surfaces of guide
elements 90 and their associated stripper sleeves 60, which is
intended to correspond essentially to the maximum thickness of
a given range of thickness of a workpiéce or workpieces to be
punched. Also, it will be understood that the axial dimension
of guide bushing 132 is chosen to insure that when the press
is first closed to effect punching of a workpiece of maximum
thickness, the guide bushing will abut or engage with sleeve
guide 126 to arrest movement of the guide templet relative to
the die templet and initiate compression of stripper sleeve 138
at essentially the same time, but no later than the time, that
the guide elements engaged with such workpiece are being forced
upwardly from their inltial or installed position shown in
Fig. 2 to engage with their associated stripper sleeves 60 and
initiate compression thereof. When workpieces being punched
are of a thickness less than such maximum thickness, compression
-15-
- \ :
1068596
of stripper sleeves 138 occurs in advance of stripper sleeves
60, that is, templet 80 is arrested before stripper sleeves 60
have been moved downwardly sufficiently to engage with their
associated guide elements.
As a practical matter, an initial spacing between the
: guide elements and their stripper sleeves of 0.1 inch will
normally permit punching o~ stock material varying in thickness
between about 0.001 and 0.1 inch without causing deflection or
resilient deformation of guide templet 80 sufficient to adversely
10 effect the desired degree of alignment of punch tip 76 and die
bushing opening 74 or binding of the punch tip within guide
: opening 102. .
When stock materials in a greater range of thicknesses :
are to be punched, a di~ferently sized guide bushing 132 must
normally ~e provided and/or spacers, not shown, added to
increase the axial length of the original guide bushing to insure
. compression of stripper sleeves 138 immediately precedent to or
essentially simultaneous with compression of stripper sleeves : :-
`i 60. In any event, the initial spacing between guide elements
. 20 90 and stripper sleeves 60 and the axial length of the guide
element would preferably be such as to prevent punch tip
` penetration of the workpiece before initiation of compression
of stripper sleeve 60.
- :` As will be apparent from viewing Fig. 2 and 3, the
: construction of assembly 16 is such as to cause guide pins lower
end portions 120a to engage within guide sleeve openings 126a
immediately prior to engagement of guide elements 90 with work-
piece 18, whereby to provide for slight horizontal shifting of
.~ guide templet 80, as may be required to bring guide openings 98
- 30 and 100, and thus openings 92 and 48, into accurate vertical
alignment. In that punch tip guide openings 102 are centered
. within their associated guide elements and openings 74 centered
,. ~
-16-
- , ............. .. . . .................. .
.:
1068596
within their associated ~ie bushings~ the above described
i hcrizontal shifting of gu~de te~ple* 80 and resultant h~rizontal
moVement of punch tips 76 serves to greatly increase the degree ~
of concentricit~ of the associated punch tips and die bushing -
openings immediately prior to and during each punch tip ~- -
penetration of workpiece 18. Alternatively, guide pins 120
could be lengthened to continuously engage with guide sleeves
126, but this construction would necessitate opening of the press
beyond its normal die set open position in order to permit
insertion/removal of the guide templet and/or alterations in
the illustration construction of assembly 16.
After proper alignment of punch tips 76 has been
achieved, continued downward movement of punch shoe 20 into die
set closed position serves in succession to cause guide templet
80 t~ move downwardly relative to the guide elements until guide
bushing 132 abuts against guide sleeve 126 whereb~ to define the
, "lower-operative" position of the guide templet and initiate
compression of stripper sleeves 138, and to place guide elements
90 in engagement with workpiece 18 whereby to arrest further down-
ward movement thereof and cause the guide elements to assume
"operative" positions relative to the guide templet, as shown
in Fig. 3; and finally to effect compression of stripper sleeve
60, as actual punching of the workpiece is effected. Upon die
set opening movements of punch shoe 20, guide elements 90 and
guide templet 80 are initially maintained in their positions
shown in Fig. 3 by the bias of stripper sleeves 60 and 138, as
- punch tips 76 are drawn into guide element openings 102, whereby
to effect stripping of workpiece 18 there~rom. After the punch
shoe 20 has been moved upwardly through a distance sufficient
to permit the stripper sleeves to fully expand, supporting pins
82 become effective to support ~uide templet 80 and subsequently
lift same for return with punch templet 34 to its initial position
-17-
:~ i
~ ` ~
~068596
shown in Fig. 2. The guide templet when supported by pins ''
82 may be considered as residing in its "rest" position.
Thus, it will be noted that guide templet 80 and guide
elements 90 cooperate to retain punch tips 76 accurately located
relative to one another and to provide for horizontal movements
of the punch tips as may be required to bring same into accurate
alignment with the die bushing openings, whereas the guide '
elements act independently of the guide templet in connection -
with the clamping and subsequent stripping of workpiece 18. '
This arrangement coupled with the above described operation of
.. . . . . .
' stripper sleeves 60 and 138 serves to prevent the application of ' ~'~
workpiece stripping forces to the relatively thin gage templet,
, which might otherwise cause deformation thereof and resultant
; misalignment of the punch tip and die bushing and/or excessive '''
, binding between and wearing away of the punch ,tips and guide
' elements. `'~
, It will be understood that the displacement of guide
', elements 90 between their initial or installed positions shown ~' '
' in Fig. 2 and their operative positions shown in Fig. 3 corres- -
' 20 ponds to the thickness of workpiece being punched. Further, it
'- will be understood that guide elements tend to remain in such
` operative positions, during subsequent punching operations which
,', a given press setup is intended to perform on a series of work- ,
:~ pie~es having the same thickness. This is due to the provision
of a relatively tight sliding fit between the guide elements and
their associated templet openings'and to the lack of any attach-
, ment between the guide elements and their associated stripper
' sleeves. This is a particularly desirable feature of the
'present construction, since the ability of the guide e,lements
to remain in their operative positions after the initial punching
.,
operation prevents tolerance change producing wear at the inter-
; faces of the guide elements and the guide templet. Also, once
~,. . .
-18-
. ~ - ,
068596
. , -,- ;
the present system is set up to punch workpieces falling
within a given range of thicknesses, e.g. between about O.O01 ~
~; and 0.1 inch, the individual guide elements may automatically - ~ -
adjust themselves relative to the guide templet, as required to
accommodate for multiple-station punching operations performed
on workpieces of different thickness falling within such given
range.
As indicated above, by the utilization of assembly
~' 16, punched hole center-to-center tolerances of plus or minus
0.001 inch are now readily achievable with a conventional reusable
punching system heretofore capable of consistently obtaining
- center-to-center tolerances only of about plus or minus 0.005
inch. The substantial increase in the degree of concentricity
of the punch tips and their associated die bushing openings,
which is now obtainable by a conventional reusable system incor~
porating assembly 16, yields the additional advantage of allowing ;
such system to be employed in the punching of thinningstock material
than heretofore possible.
:,
~ 20 ,
;'~ ' ',
.. . .
~.
. '
..''
; ' -19-
"
