Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
- :~2'~6;3~
~CF 036/040 P2 1-
B ADE ~OLDING DEVICE
Backqround of the Invention
The present invention relates to a device for
mounting and accurately seating a perforating or cutoff
hlade along a cylinder such as might be used for partially
or completely severing a web at a plurality of locations
along its length. Such devices are particularly useful in
machines for continuous printing or collating of paper
webs.
One of the requirements for such hlade mounting
arrangements is that the blade be capable of removal,
replacement and/or repositioning along the rotating blade
cylinder. From time to time during the operation of the
machine, it is necessary to remove the blade from the
cylinder, for instance, when it may be desired to print a
web without perforating or severing the same, or when
replacement of the blade is necessary due to dulling or
breakage of the blade.
A second requirement for such blade mounting
arrangements i5 that the cutting edge of a perforating
blade be capable o~ accurate seating against an anvil
surface. Otherwise, an uneven perforation will result,
with some sections of the perforation being too deep, or
some sections being too shallow, or both. This produces
variation in the tear strength along the perforation, with
resultant high probability of jamming in subsequent
printers or bursters. A backup or anvil cylinder may be
included for providing a hardened anvil surface, or
insert, or in some cases a die, to cooperate with the
sharpened edge of the properly seated blade in perforating
the pa~ssing web as the web moves between the rotating
blade cylinder and anvil or backup cylinder.
The blade is mounted to the rotating cylinder by
clamping the blade into a recess or slot cut generally
lengthwise into the cylinder periphery. Typically, the
37~
HCF 036/040 P2 -2-
recess is rectangular in cross section, and the blade may
be clamped against one of the side faces of the recess, or
against an intermediate supporting bar. Several
techniques are available, however, for providing proper
seating of the cutting edge of the blade against the anvil
surface.
Typically, when a perforating blade is
manufactured, it includes some variation in height from
its base to its cutting edge, as well as a tendency to bow
in a vertical direction. One method for seating the blade
is to use a blade which has been manufactured to very
close tolerances with respect to both height and bow. The
cylinder is provided with a recess that has been machined
also to very close tolerances with respect to a uniform
and specific depth. Seating of the blade is relatively
simple, since the blade is loaded into the recess, with
the base of the blade bottome~ along the base of the
recess, and is then clamped tightly in place.
Despite the simplicity of the seating process,
thi~s technique possesses several readily apparent
disadvantages. ~y requiring very close tolerances in
manuEacturing of the blades, the cost of the blades is
increased significantlyO Similarly, the cost of the
cylinder into which the recess is cut is also increased~
particularly in view of the fact that such cylinders
typically have as many as eight such recesses for mounting
up to eight blades at one time. Moreoever, in the event
that blade height or recess depth varies even slightly
~rom blade to blade or recess to recess, the cutting edge
30 ~ A hlade extending slightly further from the reces~s than
another will be dulled relatively quickly through contact
with the anvil surface.
A second technique is availabLe, in which a blade
having very loose height and bow tolerance may be used.
The blade is inserted into the recess, but is not bottomed
~IIL2~;3~
HCF 036/040 P2 -3-
against the base of the recess, and is secured somewhat
loosely along its length. The blade is then seated
against the anvil surface, through a procedure known as
"crash in". This procedure consists of rotating the blade
cylinder and anvil cylinder, with or without a web passing
therebetween, at inching speed through one revolution.
~he cuttin~ edge of the blade is free to move under the
seating force sufficiently into the recess, at whatever
locations are necessary to obtain a uniform seating of the
cutting edge against the anvil. While secured somewhat
loosely, the blade must be nonetheless held tight enough
to hold its seated position. The apparatus is then
stopped and the blade is securely clamped along its entire
length to prevent slip within the recess when the
apparatus is operated at higher speeds.
While this technique reqires a more complicated
blade seating technique, it allows the use of blades and
cylinders manufactured to much looser tolerances, with
substantial cost savings. A third technique, possessing
some of the advantages and disadvantages of both
techniques, utilizes a blade having close tolerance with
respect to height onlyO While the blade is bottomed
against the recess base, crash in is required to remove
vertical bow from the blade.
It will be noted that the foregoing discu~ssion is
equally applicable in the case of cuttoff blades.
A number of various devices for accurately
securing a blade within a recess, suitable for holding the
blade both for crash in and for clamping, are known. For
instance, the blade may be placed against a side wall of
the recess, and a bar inserted into the recess adjacent
the blade. A plurality of bolt members are threaded into
holes in the bar, extending from the side of the bar to
the recess side wall opposite the blade. To clamp the
blade9 the bolt members are driven in a direction
~Z~ 37~
HCF 036/040 P2 -4-
outwardly Erom the bar against the recess wall. Driving
of the bolt members forces the bar tightly against the
blade, thereby clamping it in place. In using such a
device, the bolt members may be partially tiyhtened,
allowing the blade limited movement for seating against
the anvil surface during crash in, and then the bolt
members may be completely tightened for clamping.
Several disadvantages are present in such a blade
holding device. In order to provide relatively uniform
cLamping force on the blade, a relatively large number of
the bolt members must be provided disposed along the
length of the bar. Thus~ the clamping operation becomes a
time-consuming process. Furthermore, positioning o~ the
bolt members for crash in must be fairly precise, since
there is a relatively narrow force range suitable for
crash in wherein the blade is held loosely enough for
movement during seating but tight enough to retain the
seated position. Furthermore, the bolt members also must
be finally tightened to a relatively uniform degree, or
uneven perforation will result where the blade is
inadequately clamped. Consequently, during crash in and
in clamping the blade, either a torque wrench must be
used, or the operator must through experience develop a
"feel" for the proper tightening of the bolt members.
In U. S. patent No. 4rl31rO47~ issued December
26, 1978, to Schriber et al, a blade holding device is
disclosed in which a wedge bar is provided for clamping
the blade into the cylinder recess. The blade is placed
against a side wall of the recess, and the wedge bar is
provided with a vertical taper, i.e., in a radial
direction ith respect to the cylinder. A non-rectangular
cross-sectional recess may be provided r or an intermediate
member placed between the blade and the wedge bar and
having a taper opposite the wedge bar may be provided,
along with a plurality of bolts extending through the
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HCF 036/040 P2 -5-
wedge bar and into the cylinder at the bottom of the
recess. By driving the bolts, the wedge bar is forced
into the recess in a direction toward the axis of the
cylinder, thereby securely clamping the blade into the
recess. Preloading springs may be provided to act on the
wedge bar with a force su~ficient to retain the blade
dllring crash in while allowing limited movement of the
hlade within the recess for seating. Following seating,
the bolts are tightened to firmly secure the blade.
By providing the preloading springs for supplying
s~fflcient clamping ~orce for seating of the blade, the
Schriber et al device eliminates the need for the operator
to manipulate the bolts during the crash in process.
Additionally, by providing bolts that are driven radially
with respect to the cylinder, rather ~han ~isposed within
the recess, access to the bolts is facilitated.
Nonetheless, the Schriber et al device utilizes a
plurality of bolts to provide a relatively uniform
clamping force on the blade. Moreover, since the bolts
are disposed along the entire length of the wedge bar, the
operator must reach along the full length of the cylinder
during the clamping process. Thus, even with the Schriber
et al blade holding device, the clamping process is both
time-consuming and awkward to ~erform.
In U. S. patent No. 2,832,411, issued April 29,
1958, to Richards et al~ another blade holding device is
disclosed, for use in conjunction witn a cylinder having a
recess that is at an angle with respect to the axis of the
cylinder. A pair of wedge bars, each extending for
substantially the full len~th of the recess, are located
within the recess with the blade inserted between the
barsO The ends of the cylinder are provided with collars,
each having a slot ad~acent the recess, into which a bolt
i~s fitted. The bolts each have a pair of flanges near the
head, and when the bolts are placed into the slots, the
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HCF 036/040 P2 -6-
flanges fit one on each side of the slot. Each bolt
e~tends into a threaded bore in an end of one of the wedge
bars, such that by rotating the bolts, each bar may be
moved in either direction along the cylinder recess. To
clamp the blade, the bolts are rotated such that the wedge
bars are driven into the recess so as to wedge the blade
into place. Notches or other indicia are provided along
the upper surface of one of the wedge bars and the
cylinder sur~ace, so that the relative movement of the bar
in relation to the cylinder for aligning the blade may be
easily determined.
The Richards et al device reduces the number of
bolts which must be manipulated during the clamping
process in comparison with the devices described above.
It is îndicated in the patent, however, that the primary
purpose of the device is to enable the angle of the blade
with respect to the direction of travel of the web to be
somewhat adjustable, although the device seems better
suited for adjusting the distance from the blade along the
cylinder periphery to a next following blade. In either
case, while such a feature may be desirable in
compensating for an improperly machined cylinder and/or
associated gears, it requires the operator o the device
during the clamping process to ensure that the blade is
mounted either precisely perpendicular to the web, or
precisely to the required spacing from perforation to
perforation or from separation to separation.
Consequently, any reduction in complexity or time obtained
through use of the Richards device is lost in the
necessary adjustment of the blade angle or radial
position. Further, by having bolt members extending from
each end of the cylinder, the operator is required to
travel around the machine during the clamping process as
blade angle and position adjustments are made. Finally,
use of the device requires a cylinder having a recess cut
i3~
HCF 036/0~0 P2 -7-
at an angle with respect to the cylinder axis. To use
this device, then, a specially constructed cylinder must
be used.
In addition, the Richards et al patent does not
address the problem of holding the blade for seating
cluring crash in, and in ~act, shows the blade bottomed on
the recess base. Moreover, the Richards device possesses
several disadvantages that make it impractical for use
with a blade that must be seated for uniform perforation.
Because the force exerted upon the blade must be
substantially uniform to ensure uniform perforation, the
fit of the wedge bars into the recess must be very
precise. Thus, very close tolerances must be provided in
the widths of the wedge bars, recess, and blade, since
variations in these dimensions will produce variations in
the "tightness" of the fit of the wedge bars within the
recess as the bars are wedged into place, thereby
producing variations in the force applied to blade~ As a
result, not only is manufacture of the bars, recess and
blade made difficult and expensive, but the slightest
mishandling of these parts during use may be sufficient to
misalign them to the extent that uniform force is no
lon~er attainable.
Further, since the range of force values
acceptable for crash in is relatively narrow, careful
positioning of the bars is required prior to crash in.
This requires the expenditure of significant amounts of
time, use of special tools, and/or the development of
specia] skills by the operator for proper adjustment of
the bars.
~ hat is needed, therefore, is a blade holding
device for use with a cylinder in which the blade may be
clamped in a relatively quick and simple rnanner. Such a
device should require manipulation of few parts during the
clampi~g operation, and should not require the use o~ any
3~
HCF 036/040 P2 -8-
special tools or special skills on the part of the
operator. The device should enable the blade to be
secured loosely into the cylinder with uniform securing
~orce, properly seated against an anvil surface, and then
tightly clamped into place. Clamping force should be
uniformly applied along the length of the blade. The
device should be relatively simple to manufacture, and
should not require unreasonably tight manufacturing
tolerances.
Summary of the Invention
The present invention provides a novel
arrangement for clamping a blade to a rotary cutter
cylinder. The blade is easily inserted into and held in
place by the device such that the blade may move as
lg necessary to seat against an anvil surface during crash
in, the blade being held such that it will be retained in
the seated position. I'hereafter, the blade holding device
can be tightened in order to secure the blade in the
seated positionO
~0 The blade holding device of the present invention
is for use in conjunction with a cylinder having a
longitudinal recess defi~ed in the periphery of the
cylinder parallel to the cylinder axis. Included in the
device are first and second wedge members that are
fittable within the recess, e~ch of the wedge members
having an inner wedge face and an outer ~ace. Each of the
wedge members is tapered in a direction longitudinally
alony the recess. The wedge members are insertable within
the recess such that the blade is disposed between the
~0 outer face of the first wedge member and one wall of the
recess. One of the wedge members is moved relative to the
other, such that the blade is wedged between the first
wedge member and the recess wall. The blade is first
secured sufficiently tight to allo~ seating of the blade
against the anvil surface, the blade i5 seated during
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H~F 036/OAO P2 -9
crash in, and then clamped securely.
To ensure uniform holding force against the blade
for crash in, at le~st one spring member is provided such
that the spring members may be disposed adjacent the outer
face of the first wedge member between the wedge member
and the blade. In a preferred embodiment~ a plurality of
spring members may be Belleville disc springs, although a
spring member in the form of a corrugated metal strip or
elastomeric strip, as well as other embodiments, may also
be used. The disc springs may be held in relative
positions, and the holding means may be a strip
constructed of a resilien~ material having a plurality of
holes along the length thereof. The disc springs are
mounted one each within each hole. The first wedge member
includes a relatively shallow channel defined along the
length of its outer face, so that the resilient strip may
be mounted along the ~hannel whereby the disc springs may
abut the perforating blade when the blade and first wedge
member are inserted into the recess of the cylinder.
Inclusion of the spring members provides a wide
range for relative positioning of the wedge members for
crash in. ~ecause the range of holding force exerted upon
the blade for proper seating is relatively narrow, the
spring members make application of the proper force
easier, faster, and more precise than in previously known
devices.
Spring members also allow a wider range of
tolerance for the slot width, wedge member width and blade
thickness, and produce more uniform crash in force along
3~ the entire length of the blade.
The relative movement of the wedge members within
the cylinder recess may be performed by providing an end
member mounted to one end of the cylinder adjacent the
recess. The end member includes an opening therein,
through which a bolt is extended. The bolt has at least
3L2~ 4
HCF 036/040 P2 -10-
one flange near its head, the flange being disposed on one
side of the opening ~or retaining the bolt in a position
relative to the end member. The bolt is further
engageable with one of the wedge members, so that by
rotating the bolt, the wedge member may be moved relative
to the cylinder, and hence relative to the o~her wedge
member.
The bolt may be engageable with an end of the
second wedge member, and the relative movement of the
wedge members is performed by moving the second wedge
member along the recess. The first wedge member is
captured between two end rings to prevent its movement
along the recess. Additionally, at least a portion of the
outer face of the first wedge member is roughened to
increase the holding force on the blade or to prevent
s].ippage of the blade within the recess.
Accordingly, it is an objec~ oE the present
invention to provide a blade holding device for use with a
perforating or cuttoff blade and a cylinder, wherein a
pair of wedge members is provided with a means for
effecting relative movement of the wedge members within a
recess in the cylinder periphery to clamp the blade
between one of the wedge members and a recess wall; to
provide such a device wherein the blade may initially be
secured sufficiently to allow seating against an anvil
surface, and then c].amped to secure the blade for
perforation of a web; to provide such a devi.ce which
exerts a uniform crash in or clamping force along the
entire length of the blade; to provi.de such a device which
is relatively ~uick and simple to operate; and to provide
such a device which is relatively easy to manufacture and
which may be used with cylinders having a standard
configuration for the recess defined therein.
Other objects and advantages will be apparent
from the following description, the accompanying drawings
;3 7~
~ICF O 3 6/0 40 P 2
and the appended claims.
Brief Descri~tion of the Drawings
... ~ ._
Fig, 1 is a perspective view of a portion of a
rotary cutter cylinder showing insertion into a recess
therein of a blade and the blade holding device of the
present invention;
Fig. 2 is a plan view of the cylinder showing the
blade and blade holding device in position;
Fig. 3 is a sectional view of a portion of one
lG end of the cylinder, showing the wedging mechanism for
operating the blade holding device with the blade firmly
clamped in place;
Fig. 4 is a view similar to Fig. 3 showing the
operation of the wedging mechanism and w~th the blade in
position for seating within the recess;
Fig. 5 is a graph showing the load applied to the
perforating blade as a function of displacement of a wedge
member along the recess, and as a fun~tion of the
compression of the wedge members and spring members across
the recess;
Fig. 6 is an enlarged cross-sectional view of a
segment of the cylinder, taken generally along line 6-6 of
Fig. 3:
Fig. 7 is a view similar to Fig. 6, taken
generally along Line 7-7 o Fig. 4;
Fig. 8 is a perspective view of a portion of a
wedge member, showing an alternative embodiment for the
spring member; and
Fig. 9 is a cross-sectional view similar to a
portion of Fig. 6, showing a further alternative
embodiment for the spring member.
Detailed Description of_the Preferred Embodiments
Fig. 1 shows a portion of a typical rotary cutter
cylinder 10 to which may be mounted a blade 12 of any
length up to and including the length of the cylinders.
i37gL
HCF 036/040 P2 -12-
Blade 12 is shown as a perforating blade, but may be a
cutoff blade as well. The cylinder 10 includes a
longitudinal recess 14 defined along the periphery of
cylinder 10. Recess 14 is preferably rectangular in
cross-section, and as seen in Fig. 6, includes a base 15
and opposed walls 16 and 18. Referring back to Fig. 1,
hlade 12 may be inserted into recess 14 of cylinder 10 for
mounting, although blade 12 is not bottomed against base
15, allowing space both for crash in and storage of blade
12 when not in use. slade 12 is held in position by the
blade holding device 20 of the present invention.
Blade holding device 20 includes a pair of wedge
members 22 and 24. Each wedge member 22 and 24 has an
inner wedge face 23 and 25, respectively, and an outer
15 face 26 and 27, respectively. As may be seen in Fig. 2,
wedge members 22 and 24 are tapered in a direction
longitudinally along the recess 14. Further, wedge
members 22 and 24 are insertable into recess 14 of
cylinder 10 with wedge faces 23 and 25 in mutual contact,
such that the blade 12 may be held between outer face 26
of wedge member 22 and wall 16 of recess 14. We~ge member
24 is moved relative to wedge member 22, applying a
wedging force against both walls 16 and 18 of recess 14,
thereby clamping blade 12 into position.
The means for effecting movement oE wedge member
24 with respect to wedge member 22 may be seen in Figs. 1,
3 and 4. Wedge member 24 is provided with a threaded bore
28 in one end thereof. Bolt 29, engageable with bore 28
incllldes a head 30 an~ a pair of flanges 32 and 34O An
annular collar 36 attached to one end of cylinder 10 by a
plurality of bolts 38 includes notch 40, communicatlng
with recess 14 of cylinder 10. When wedge member 24 is
inserted into recess 14, and bolt 29 is threaded into bore
28, notch 40 provides for extension of head 30 of bolt 29
beyond collar 36, so as to allow manipulation of bolt 29
3~4~
HCF 036/040 P2 -13-
from a position adjacent one end of cylinder 10.
Notch 40 of collar 36 includes a relatively
shallow portion 42 having a groove 44 defined therein. A
retaining member 46, having a groove 48, is mounted to
relatively shallow portion 42 by a pair of bolts 50.
Grooves 44 and 48 cooperate to define a hole, and bolt 29
is fittable within the hole such that flanges 32 and 34
are disposed on each side of the hole. Grooves 44 and 48
are sized accordingly such that flanges 32 and 34 retain
bolt 29 within the hole, but bolt 29 is freely rotatable
within the hole.
In the alternative, of course, it will be
recognized that bolt 29 may have a single flange, with the
single flange and bolt head 30 cooperating at opposite
15 ends of grooves 44 and 48 for retention of bolt 29 within
the hole defined by grooves 44 and 48.
The operation of bolt 29 for moving wedge member
24 relative to wedge member 22 may be seen by comparing
Figs. 3 and 4. E'ig. 3 illustrates the wedge members 22
20 and 24 wedged into recess 14 of cylinder 10 such that
blade 12 is securely held between outer face 26 of wedge
member 22 and wall 16 of slot 14. To release b]ade 12,
head 30 of bolt 29 is gripped by an appropriate tool (not
shown) and bolt 29 is rotated in the direction indicated
25 by arrow 52 in Fig. 4. It will be noted from arrow 52
that bolt 29 and bore 28 are provided with left-handed
threads, and bolt 29 may have multiple start threads for
faster movement of bolt 29 along bore 28, and hence,
faster operation of the blade holding device 20. By
rotating within threaded bore 28 oE wedge member 24~ bolt
2~ draws wedge member 24 in a direction toward collar 36
as indicated by arrow 53. As wedge member 24 is drawn
toward collar 36, wedge members 22 and 24 no longer apply
wedging force to the walls of recess 14, and blade 12 is
released and may be removed.
3637~
IICF 036/040 P2 -14-
It will be recognized that to move wedge member
24 for clamping blade 12 into recess 14, the opposite of
the operation described above is performed. solt 29 is
rotated in a direction opposite to that indicated by arrow
52, thereby moving wedge member 24 away Erom bol~ 29.
Wedge members 22 and 24 apply a wedging force to the walls
of recess 14, clamping blade 12 into place.
During either of these operations, wedge mernber
22 remains stationary within recess 14, retained by collar
36 and an annular end ring 54 mounted to the opposite end
of cylinder lO from collar 36.
It can easily be seen that the force or load
applied to blade 12 by blade holding device 20 is
dependent upon compression of wedge members 22 and 24
across recess 14~ which in turn is dependent upon the
di~placement of wedge member 24 along recess 14.
Accordingly, as an aid to the operator of the device 20 in
positioning wedge member 24 relative to wedge member 22,
which remains stationary, each wedge member is provided
with marks, notches or other indicia 55 to present a
visual indication of their relative movement.
To facilitate the movement of wedge member 24
relative to and in contact with wedge member 22 and recess
l~, any appropriate solid lubricant may be applied to the
25 wedge Eace 25 and outer face 27 of wedge member 24.
During crash in of blade 12 for proper seating
within recess 14 to provide a uniform perforation or
severing of a web passing along cylinder lO, force must be
applied to blade 12 by the blade holding device 20 within
a relatively narrow range of forces so that blade 12 is
held loosely enough to permit seating, yet tightly enough
to retain the seated position prior to final clamping. In
order to expand the range of positions of wedge member 24
relative to wedge member 22 and recess 14 wherein force
within the crash in range is applied to blade 12, a
~6;~74~
HCF 036/040 P2 -15-
relatively shallow channel 56 is defined along the length
of the outer face 26 of wedge member 22, as seen in Fig.
1. A plurality of Belleville disc springs 58 are disposed
along channel 56, and are held in relative position by a
rubber strip 60. Rubber strip 60 includes a plurality of
holes defined along its length, such that each spring 58
may be mounted within one of the holes and retained
thereby. Springs 58 may be he]d into the holes of strip
60 either by cementing them in place~ such as with a
rubber cement, or molding the strip 60 about the springs
58 so that they are retained in place. Strip 60 is
preferably mounted to channel 56 by a rubber cement
material.
As seen in Figs. 6 and 7, during clamping of
15 blade 12, springs 58, held in place by strip 60, are
gradually compressed against blade 12 as wedge member 24
is wedged into recess 14. Once springs 58 are compressed
to the point at which surfaces 61 of wedge member 22 are
in contact with blade 12, however, further movemen~ of
wedge member 24 results in blade 12 being c]amped
essentially by the wedge members 22 and 24 directly.
Surfaces 61 may be roughened or knurled to
provide increased holding force, by friction, for the
blade 12 to prevent its slippage within recess 14.
The operation of springs 58 for providing
relative ease in positioning wedge member 24 for crash in
of blade 12 may be seen by referring to Fig. 5, showing a
plot of the load (force per unit length) placed upon the
blade 12 by the blade holding device 20 as a function of
the displacement of wedge member 29 along recess 14, and
as a function of the compression of wedge members 22 and
24 and springs 58 across recess 14. It will be recognized
that the values presented along the load axis of Fig. 5
are pertinent to blades and blade holding devices in
general, independent of their lengthr and values presented
Ç6374
liCF 036/040 P2 -16-
along the compression axis are similarly independent of
the angle formed between the wedge face 25 and outer face
27 of the wedge member 24. Values presented along the
displacement axis of FigO 5, however, are dependent upon
the wedge member angle, and specific values in Fig. 5 are
based ~pon an exemplary angle of 1. It will be
nonetheless understood that the shapes and rela~ionships
of the curves presented are correct for any angle.
It has been found experimentally that the proper
load to be placed upon blade 12 for satisfactory crash in
is within thé approximate range of 231 to 475 lbs./in.,
indicated in Fig. 5 by arrow 64. For final clamping of
blade 12, a load of at least 1400 lbs~/in. mu.st be
applied, indicated at 66.
In the absence of springs 58, the load produced
by deflection of wedge member 24, corresponding to direct
compression of we~ge members 22 and 24, follows theOlinear
Hooke's law relationship for compression of an elastic
body, with wedge members 22 and 24 having an effective
20 force constant of 50,000 lbs./in.2, and is shown as
curve 68 of Fig. 5. For crash in, wedge member 24 must be
moved between approximately .03 and .~6 inches to produce
a load on blade 12 within the appropriate range. It can
easily be seen, however, that positioning of wedge member
24 must necessarily be relatively precise, i.e., to within
a range of .03 inch, in order to achieve the proper crash
in load. With such a small range, even indicia 55 are of
relatively little help for proper positioning. Thus,
special tools for adjusting bolt 29 must be used~ or the
operator of the device 20 must develop special skills or
expertise.
~ hen springs 58 are provided as illustrated
generally in Fig. 1, the displacement of wedge member 24
produces the load values indicated by curve 70 in E'ig. 5.
Initially, only springs 58 actually contact blade 12, as
~2~6374
HCF 036/040 P2 -17-
seen in Fig. 7, and as wedge member 24 is moved, springs
58 compress against blade 12. Springs 58 have a
significantly lower force constant (or, more properly
here, a spring constant), appro~imately 95,000
lbs./in.2, than wedge members 22 and 24, and the initial
portion of curve 70, indi~ated at 72, has a
proportionately reduced slope.
Once springs 58 are compressed such that s~rfaces
61 of ~edge member 22 contact blade 12, indicated at pOillt
74 on curve 70, further displacement of wedge member 24
causes increases in the load on blade 12 to be applied by
wedge members 22 and 24 directly. Accordingly, the final
portion 76 of curve 70 is of the same slope as curve 68.
The effect of springs 58 upon the operation of
blade holding device 20 for applying crash in force to
blade 12 may be appreciated by considering the crash in
load range 64. To apply the proper load, wedge member 24
must be moved between approximately .14 and .28 inches, or
within a range of .14 inch, as indicated at 77. Thus, a
relatively broad range of positions is available for wedge
member 24, making the use of indicia 55 much more
practical and helpful. Since positioning of wedge member
24 is no longer so critical, no special tools or operator
expertise is required for operating blade holding device
20.
After springs 58 are compressed such that
surfaces 61 of wedge rnernber 22 contact blade 12, further
~isplacement of wedge member 24 causes the load to
increase as shown by portion 76 oE curve 70. Since
portion 7~ has a siynificantly increased slope compared to
portion 72, relatively little additional displacement is
necessary to apply the final clamping load to blade 12.
An additional, if not more important, advantage
may be obtained through use of the spring members as
provided in any of the embodiments disclosed aboveO In
63~
E~CF 036/040 P2 18-
the absence of spring members, very close tolerances must
be provided to insure the uniformity o~ the widths of the
wedge members 22 and 24, the recess 14~ and blade 12, with
the a~tendant hiqh cost and extreme care required in
handling these parts. Otherwise, because of the relative
rigidity of wedge members 22 and 24, variation in these
dimensions may produce areas along blade 12 of varying
load exerted thereon, resulting in uneven perforation or
severing of the web. The required tolerance may be seen
from Fig. 5. The c~mpression rang~ within the cra~h in
range where wedge members 22 and 24 are used without
springs 58, shown on curve 68 as range 69, is between
.0005 and .0010 inch. If the tolerance on any one or a
cornbination of wedge members, blade or recess is such that
any area along blade 12 is compressed outside this range,
load applied will be outside the crash in range, seating
may not be accurate, and the resulting perforation or
severing may be uneven. Thus, the tolerance required is
.0010 inch - .0005 inch = .0005 inch.
Due to the relative flexibility imparted to the
blade holding device 20 by inclusion of one or more spring
members, however, these tolerances may be relaxed. As
shown at 77 along curve 70 of Fig. 5, when springs 58 are
used, the compression range of ~ledge members and springs
25 is between .0024 and .0050 inch. Thus, inclusion of
springs 58 allows wedge member, blade and recess tolerance
to be increased to .0026 inch, a five-fold increase, with
resulting significant cost savings in manufacture.
A number of alternative embodiments for the
spring members may be used in place of springs 58 and
rubber strip 60, each having the same operation as the
embodiment just disclosed and producing a
load-displacement curve of the same shape as curve 70. In
Fig. 8, a single corrugated metal strip 78 is provided,
35 fittable within channel 56 of wedge member 22. In Fig. 9t
~Z~63~
HCF 036/040 P2 -19-
a continuous elastomeric strip 80 is used, mounted to
channel 56 by a rubber cement material. A series of
slightly compressible rollers or balls may be placed
between the wedge members 22 and 24. Of course, it will
be recognized that numerous other alternatives exist and
may be used as well.
It will also be recognized that spring memhers
may be used that are characterized by a non-linear
compression load relationship. Such an embodiment will
produce a curve somewhat different from curve 70, in that
the portion corresponding to portion 72 will not be
linear, but will nonetheless result in expansion of the
compression and displacement ranges for crash in, thereby
obtaining the same advantages.
A still further alternative embodiment may be
used in which the spring members are effectively
"built-in" within wedge members 22 and 24. Either of
wedge members 22 or 24, or both, may be provided with
portions ~ormed of a weaker steel or other metal, or may
be provided with one or more cut-out sections along the
length of wedge member 22 or 24r the cut-out sections
being formed so that wedge member 22 or 24 remains as a
unitary piece. The effect of providing weakened portions
or cut-out sections is to reduce the force constant of
25 wedge members 22 and 24, with the result shown as curve 82
in FigO 5. Such an embodiment produces advantages
approximately midway between those obtained through the
wedge members with separate spring members and the wedge
members alone. It may be seen that the displacement range
available for crash in is greater than for the wedge
members alone, although it is not as great as when
distinct spring members are provided. Total displacement
for final clamping, however, is less than that required in
the separate spring members embodimentsr representing some
savings in time usec3 for manipulating bolt 29.
637~
~CF 036/040 P2 -20-
In a similar alternati~Je, weakened or cut-out
portions may be included along the slde walls of recess
14, particularly wall 18.
It will be recognized further that spring members
such as springs 58 may be used, and the advantages thereof
obtained, with embodiments for clamping a blade with one
or more wedge members other than the preferred, two
wedge-member embodiment disclosed herein. For example, in
one alternative embodiment, a wedge member is provided
having a taper in a direction raclial with respect to the
cylinder. The recess is cut to cooperate with the wedge
member such that movement of the wedge member within the
recess toward or away from the cylinder axis clamps or
unclamps the blade. See, for example, U. S. patent No.
15 4,131,047, issued December 26, 1978, to Schriber et al.
In such a case, the springs are provided between the wedge
member and the blade, although a bu~fer plate may also be
provided therebetween for facilitating retention of the
springs and/or blade in position.
It is common practice to rotate the cylinder 10
on occasions when it is desired not to perforate or sever
the web. In such a case, the blade holding device 20 is
unclamped, blade 12 is bottomed against recess base 15 so
that the cutting edge of blade 12 is below the surface of
cylinder 10, and the device 20 is reclamped. In the event
device 20 is inadvertently left unclamped, however, a
means for retaining wedge members 22 and 24 within recess
14 when unclamped is provided. In addition to collar 36
mounted to one end of cylinder 10, an annular ring 54 is
provided at the opposite end, seen in Fig. 2. Ring 54 is
attached to cylinder 10 by a plurality of screws 86 (only
one shown) and is of a radial width less than the depth of
recess 14. A retaining pin 88 is mounted near the lower
end of each of wedge members 22 and 24, such that when
35 wedge members 22 and 24 are inserted into recess 14,
! 6374
,
HCF 036/040 P2 -21-
retaining pins 88 extend from recess 14 under the ring
54. When cylinder lO is rotated with wedge mernbers 22 and
24 unclamped, retaining pins ~8 cooperate with ring 54 to
hold the wedge members in place. A similar retaining pin
88 is provided at the opposite end of wedge member 22, and
is inserted into a half-slot (not shown) defined within
collar 36. It will be seen that no retaining pin is
required for the opposite end oE wedge member 24, due to
its engagement with bolt 290
While the form of apparatus herein described
constitutes a preferred embodiment of this invention, it
is to be understood that the invention is not limited to
this precise form of apparatus, and that changes may be
made therein without departing from the scope of the
invention.
