Note: Descriptions are shown in the official language in which they were submitted.
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1
LOW FRICTION HOLE PUNCH ELEMENT
CROSS-REFERENCE TO RELATED APPLICATIONS
This is a continuation-in-part application of co-pending parent application
having
serial no. 11/215,423, filed August 30, 2005, whose entire contents are hereby
incorporated by reference.
FIELD OF THE INVENTION
The present invention relates to hole punching devices used to cut holes in
sheet
material. More precisely, the present invention relates to a punch pin and
support
stnicture.
BACKGROUND OF THE INVENTION
A paper punch is a coinmon device found in offices and schools. It is used to
cut
holes in paper under finger or hand pressure. Typically, a paper punch element
includes a
pin, and a fraine to support the pin over a paper slot. The pin moves axially,
or vertically,
into the papers. It is desirable to minimize the force required to cut a hole
into a stack of
papers since these tools are usually operated ttnder hand or finger pressure.
To be sttre,
even a motorized paper punching device benefits from reduced force since a
smaller motor
may be used.
One method to reduce this force is to cut progressively around the periineter
of a
hole rather than to cut the entire perimeter of the hole all at once. A well-
lcilown method
for making a progressive cut is with a "V" cut notch in the end face of the
pin. This
creates more than one cutting point. The notched end cuts from two opposed
sides of the
hole toward the center of the hole. The notched end provides two eelual
pointed ends of
the pin that press the paper stack simultaneously. Other designs use
asyinmetrical points
or three or more cutting points.
Another concern is jamming of the pin in the paper. Typically, as the pin
advances
into the hole, the inside diameter edge of the paper is stretched and dragged
down into the
hole along witll the pin. Then as the pin is withdrawn out of the hole, the
edges tend to flip
upward and press hard around the pin in a cam action. The hole effectively
acts as a one-
way cleat, with the hole imler diameter serving as a diaphragm to hold the pin
in the hole.
The hole diameter cut in the paper is in fact smaller than the diameter of the
pin.
Tlie prior art paper hole puncl7es typically conteinplate a eompression type
die
spring strong enough to overcome the highest anticipated pull out or
retraction force. The
pin can typically be retracted only by the spring. Therefore, the spring must
provide that
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ftuiction tulder all circtunstances. United States Patent No. 4,757,733
(Barlow) shows a
typical arrangement in Fig. 6. Ridge 40 transmits pressure to cap 47 atop each
pin (cutting
tool 15). Helical spring 45 surrounds the piii. When the pin does not retract
in this type of
design, the paper becomes jainined in the punching device since there is no
fiirther way to
force the pin out. This situation is familiar to most users of paper punches.
Also, the force
needed to coinpress the die spring directly adds to the hand or operating
force required to
cut the hole. When a small stack of papers is being cut, the spring force is
often greater
than the actual cutting force.
There are many hole punch tool and pin designs. For exainple, U.S. Patent
No. 5,730,038 (Evans et al.) shows a punch pin cutting end with specified
groove depth in
relation to a paper stack height, and a force sequence profile. U.S. Patent
No. 5,243,887
(Bonge, Jr.) shows a rectangular punch 18 fitted in the rectangular guide hole
of a fraine.
The punch is pivotably attached to a lever and secured axially by pin 24. U.S.
Patent No.
4,763,552 (Wagner) discloses a punch pin with a syrmnetric angled cutting end.
U.S.
Patent No. 4,713,995 (Davi) shows a conventional punch element design,
including a
helical return spring around the pin, and a lever that can only press, not
pull, the pin. U.S.
Patent No. 4,449,436 (Semerjian, et al.) shows a cylindrical punch pin that
includes a
slotted top. A lever rib normally engages the top of the punch pin. An
inoperative
position for the sheet punch is achieved by rotating the punch pin so that the
slot aligns
with the lever rib. The rib then moves into the slot rather than pressing the
top of the pin.
No apparerit mechanism is disclosed to keep the punch pin in its operative
rotational
position. The Semerjian '436 patent furthers shows an asyinmetrical pin with
one cutting
point longer than another.
U.S. Patent No. 4,257,300 (Muzik) discloses a cylindrical punch pin where the
pin
is secured axially at an aimular groove. A key fitted in a radial slot of the
pin positions the
pin rotationally. U.S. Patent No. 3,721,144 (Yainainori) shows a tubular punch
die
element with thin walls and a sharpened lower end. U.S. Patent No. 3,320,843
(Schott,
Jr.) shows a tubular punch element that is grotuid shaip at its cutting end.
U.S. Patent No.
4,594,927 (Mori) shows a punch pin held axially in two ways. In one
embodiment, a rod
10 passes tluough a drilled hole in the upper body of the punch pin.
Alternatively, an
amlular groove fits in a slot of a pressing plate. With the amzular groove,
the punch pin is
not rotationally fixed in position. The Mori '927 patent shows an inclined
base where the
pins cut holes in a progressing sequence. The angle is very slight, just
adequate to create
the sequential cuts while maintaining a reasonable heiglit to the punch
device. U.S. Patent
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No. 4,656,907 (Hymmem) shows a paper punch that may be disassenlbled for,
ainong
other reasons, to fix jainmed pins. U.S. Patent No. 4,240,572 (Mitsuhashi, et
al.) shows a
multi-pointed punch pin including a discussion of a punching sequence. U.S.
Patent No.
5,463,922 (Mori) shows a roller system for pressing ptuich pins in a sequence.
Japanese Patent Publication No. 64-087192 (Izumi, et al.) shows a punch pin
with
elongated cutting points, and a graph showing two force pealcs during the
punching
operation. Japanese Patent Publication No. 61-172629 (Yulcio) shows different
cutting end
profiles for a punch pin, including an asymmetrical end. U.S. Patent No.
4,829,867
(Neilsen) shows a fixed diameter sleeve type punch pin with a helical cutting
end. U.S.
Patent Nos. 6,688,199 (Godston, et al.) and 4,077,288 (Holland) disclose
punches with a
vertically oriented or upright paper slot. In the Godson '199 patent, the
surrounding
stn.icture 532 holds the papers away from the user. As illustrated in Figs. 4
and 9, slot 62
including floor 64 and ceiling 68 are peipendicular to the punch pin axis 50.
Conventional paper punches use hardened, non-coated or non-surface treated
steel
for the pins. The wear resistance and lubricity of the pin against paper are
liinited by
inherent sttrface properties of the steel material.
SUMMARY OF THE INVENTION
It is desirable to minimize the pealc forces to ctit a hole or holes in papers
or other
sheet media in a finger- or hand-pressure operated tool or in a coinpact
motorized tool.
The shape at the end of the punch pin is important. One approach is to cut the
notch so
that the pointed cutting ends are at different levels. Then the lowest pointed
end cuts into
the paper or sheet first before the higher pointed end, so the force required
is less than that
with two equal elevation ends cutting into the paper or sheet simultaneously.
One
approach to creating different levels for the cutting points is to locate tlie
notch in between
the cutting points off-center. Another approach is to provide an uneven punch
base so that
the pointed ends cut into the sloped sheet differently.
To ftu-t11er improve the efficiency of a hole punch, the pull out force of the
pin must
be reduced. One way to reduce the force is to malce the hole in the paper
larger than the
pin diameter. A non-circular imler circtunference can make it easier to expand
the hole
about a circular pin. For example, an oval hole in a sheet with its largest
diameter sized
greater than the punch pin diameter would allow the punch pin to pull out
easily. To
create an oval hole with a circular pin, in one embodiment, the base or anvil
of the frame
should be stibstantially uneven or angled. The paper flexes out of a flat
plane at the anvil.
The pin thereby presses the paper at a substantial angle off peipendicular to
the punch pin
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creating a sliglitly ovoid hole. With such an arrangemen.t, the smaller
dianleter of the
ovoid hole reinains equal or smaller than the pin diaineter, while the larger
diaineter of the
ovoid hole is larger than the pin diameter. The pin can easily force open the
nan-ow
direction of the hole when the paper is repositioned peipendicular to the pin
since the loose
fitting larger diaineter direction can flex toward the pin. The ovoid hole
becomes slightly
distorted into a round shape that is larger than the simple round hole that is
ordinarily
made by the pin.
Aiiother approach to ease the pin reinoval is to use an expanding pin. In such
an
exemplary embodiment, a thin-walled sleeve includes an angled cutting end. The
end is
ground to a sharp edge and may cut progressively from one side of a hole
toward the
opposite side. In a preferred einbodiment, the sleeve is formed from a sheet
metal blailk
into a hollow cylinder, and includes a longitudinal gap between the two
opposed edges of
the fonned blailk.
The sleeve is expandable whereby it has a larger diameter as it is forced into
the
paper and a smaller diameter as it is pulled out. The longitudinal gap becomes
larger
allowing the sleeve to expand. The sleeve at least partially surrounds a punch
pin. The
punch pin includes a head at the top. Once assembled, the pin is slidable
within the sleeve
wherein the head is normally spaced above the top of the sleeve. Pressing the
pin/sleeve
assembly at the pin head into the paper sheet causes the pin to slide down
with the head
moving toward the sleeve. A groove around the circumference of the pin
receives a
radially inward facing rib formed in the sleeve, or equivalent structure, so
that as the pin
slides within the sleeve, the rib slips out of the groove and expands the
diaineter of the
sleeve. During the downward cutting stroke, the expanded sleeve cuts a hole
with a larger
diaineter than the sleeve diaineter during the pull out stroke.
Al.i approach to reduce punching effort is to minimize the retuni spring
force. A
return spring is coirnnonly used to return the actuation handle back to the
start position and
to withdraw the punch pin from the pLuiched hole in the sheet material. A
first way to
achieve a lighter spring force is to reduce the pull out force described
above. A lighter
spring provides a particular advantage in liglit duty use, but is also
advantageous in any
type of punching application. A second way to reduce return spring force is a
simplified
linlcage that enables a user to directly pull out a pin from a punched hole.
The return
spring may then be just strong enough to retract the pin in most
circumstances; the retui7l
spring need not be so strong that it caiz retract the pin under the worst
case. Examples of
such worst cases include when ptuzching through a very thick stack of papers
when the
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papers have some glue or other containination, or when the pin has become dull
and draws
more paper edge into the hole. Iii such worst case instances, the user can
augment the
return spring power by pulling up upon an operating handle to retract the pin.
Accordingly
the spring force may be substantially reduced.
It is desirable to reduce friction and wear in the operation of the pin
through a low
friction interface. One exainple of such an interface includes a lubricant
such as grease.
More pennanent approaches include plating and surface treatments. Ainong
surface
treatments are polyiner iunpregnated resin coatings, titaniiun nitride,
carbon, and metal
plating. The treatinents may be applied electrically, chemically, electro-
statically, by ion
implantation, vapor deposition and other processes. Certain processes such as
ion
implantation do not change the dimensions of the coinponent being treated.
Other
processes add to the thicla-iess of the material to fihe component. Galvanic
electroplating,
such as nickel or chrome, provides some corrosion protection and limited
friction
reduction in some cases. However, electroplating does not precisely reproduce
the parent
surface.
Electroless nickel is a chemically based process that provides low friction,
low
wear properties on steel and other surfaces. It is especially economical on a
small part
such as the punch pin of a hole punch for instance, since electroless nickel
can be a batch
process with ininimal haridling of the small parts. Electroless nickel
accurately reproduces
the underlying surface too. For exainple, the cutting point may be ground
before the
plating is added so that the sharp cutting edges are substantially preserved.
In contrast,
galvanic electroplated nickel creates an uneven layer; in particular, shaip
outside edges
such as the cutting points of the pins cause concentration of material wherein
an enlarged,
rounded bulb or globule of niclcel or other plated metal grows at the edge or
corner. Such
a roLulded, distorted, blunted corner caiu-iot cut papers well.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a side elevational view of a punch eleznent with a pin shown in
hidden
view.
Fig. 2 is a partial cross-sectional front view of the punch element taken
along line
2-2 of Fig. 1.
Fig. 3 is a side, top perspective view of a pin and retaining clip assenibly.
Fig. 3A is a detail view of an alternative embodiment pin cutting end with a
"W"
shaped profile.
Fig. 4 is a side, bottom perspective view of a pin.
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Fig. 5 is a side, bottom perspective view of the punch element frame of Fig.
1.
Fig. 6 is a cross-sectional view of the pin within an oval hole formed in a
stack of
papers.
Fig. 7 is a partial cross-sectional view of the element of Fig. 1 with the pin
moved
down to an intermediate position.
Fig. 8 is a cross-sectional view of an altenlative embodiment hole punch
element
assembly.
Fig. 8A is a detail view of Fig. 8, showing the top portion of a ptulch sleeve
against
a pin head.
Fig. 8B is a detail view of Fig. 8, showing a rib of the sleeve pressing a
groove in
the pin.
Fig. 9 is a side elevational view of a pin and sleeve assembly.
Fig. 10 is a side, bottom perspective view of the pin and sleeve asseinbly of
Fig. 9.
Fig. 11 is a side elevational view of an altenlative embodiment punch element
wit11
an actuating bar engaging a pin and a retunz spring in hidden view, with the
assembly in an
intermediate position.
Fig. 12 is a partial cross-sectional view of the punch element of Fig. 11.
Fig. 13 is a rear, side perspective view of the punch element of Fig. 11.
Fig. 14 is a side elevational view of the punch eleinent of Fig. 11.
Fig. 15 is a rear side view of the punch pin of Figs. 11 to 14.
Fig. 16 is a perspective view of a double torsion return spring.
Fig. 17 is a detail view of a pin wit11 electroless nickel plating.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is directed to a hole punch element. A hole ptnlch
element
may be defined as the punch pin, or as the stntcture within the inunediate
region of the
hole punch device near the pin including the structures that guide the pin and
the sheet
media or substrate to be punched, sttch as a stack of papers. For exainple, a
die cast punch
suppoi.-t stntcture may guide pins as well as support an operating handle.
Figures 1 to 7 show one exeinplary embodiment of an improved punch element.
Pin 20 is vertically slidable and guided in fraine 10 along a longitudinal pin
axis, depicted
as a vertical, dashed line. In Fig. 1, pin 20 is shown in an intennediate
position between an
uppennost position and a lowennost position. Lower cutting point 21a of pin 20
is just
protruding into anvil cavity 13. Upper cutting point 21b of pin 20 has not
entered cavity
13 in Fig, 1.
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Tie bar 100 is linked to pin 20. Tie bar 100 is preferably a side facing "U"
chamlel
in the illustrated embodiment. Linlcages acting as the tie bar of other shapes
aside from a
"U" chamlel are coritemplated. 1ii a inultiple hole punch, such as a three
hole punch, tie
bar 100 actuates tllree punch elements spaced along a lengtll of tie bar 100.
Tie bar 100
links the pins to a ftu-ther actuating mechanism shown schematically as handle
107.
Handle 107 is pivotably attached to frame 10, either directly as shown at
pivot 104 or to a
housing body (not shown) that supports one or more fraines or punch element
portions and
an actuating lever system. Handle 107 is also pivotably attached to tie bar
100. Some
optional sliding motion is allowed at pivot 103 in the instance that handle
107 moves by
rotation as shown. lii the preferred embodiment, handle 107 can press downward
upon tie
bar 100 and optionally pull up on tie bar 100 via pivot 103.
Pin 20, tie bar 100, handle 107 or any combination of these components or
equivalent stilictures may be driven not only by direct manual force of a
user's hand but
also by a motor or by hydraulics. For example, a motor (not shown) may rotate
an
eccentric cam and the cam selectively engages tie bar 100 from above to force
tie bar 100
downward as in Fig. 1.
When a user depresses handle 107 which rotates about pivot 104, pivot 103
translates the rotational handle motion into a vertical translation of tie bar
100. Upper wall
102 of tie bar 100 presses atop pin 20 to urge pin 20 into papers 51 or otller
sheet material,
as seen Fig. 2. Still in Fig. 2, lower wall 104 includes recess 105 formed
into the lower
edge of tie bar 100 to at least partially sLu-round lower body portion 24 of
pin 20. Spring
clip 70 fits into circmnferential groove 25 of pin 20. Lower wall 104 of tie
bar 100 fits
under spring clip 70 at recess 105. Wit11 the contacts at pivot 103 and/or
spring clip 70, tie
bar 100 can press pin 20 in a downward stroke in response to a user's pressing
action upon
haiidle 107. Moreover, as tie bar 100 is raised by handle 107 via pivot 103,
tie bar 100
also lifts pin 20 in an upward stroke through the spring clip 70 liiikage at
recess 105.
Therefore, a user may easily lift pin 20 directly if the pin becomes stuck in
a hole that the
pin cut into the stack of papers 51. This capability contrasts with the
conventional light
duty hole punch where an operating handle can only press punch pins, but
camlot lift the
pins since there is no tensile liiAc to the pin to enable a retracting stroke.
The present invention exeinplary embodiment provides a much simpler lifting
mechanism than, for example, a pin that has a cross drilled hole holding a
dowel used to
attach the pin to a lifting arm to enable the lifting stroke. Cross drilling a
cylindrical pin
through its centerline is costly and difficult to manufacture.
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hi Figs. 2 and 5, shelf 17 provides an optional upper stop for spring clip 70.
Ii-i Fig.
2 it is seen that shelf 17 is similar in thiclaiess to lower wall 104 of tie
bar 100. As pin 20
inoves up to its upper niost position, spring clip 70 contacts shelf 17. A gap
remains to
allow lower wall 104 of tie bar 100 to fit in between ceiling 11 of frame 10
and spring clip
70. Therefore, if the punch element is removed, for exainple to change its
position from
two hole punching to tluee hole punching, the gap between ceiling 11 and
spring clip 70
remains so that the punch element can be reinstalled into recess 105 and
liiilced to tie bar
100. The present einbodiment thus benefits from quick and easy
interchangeability of the
punch elements. The gap also helps in initial manufacturing assembly of tie
bar 100 about
pin 20.
Frame 10 includes side walls and an opening facing rearward, in the leftward
direction in Fig. 5, to create an optional, partially enclosed space. Pin 20
is therefore
exposed rearward in frame 10. As best seen in Fig. 5, rearward is defined as
the direction
in which slot 19 tei7ninates, which is opposite to the direction toward which
slot 19 opens.
This arrangement allows lower wall 104 of tie bar 100 to engage pin 20 using a
simple
recess 105 foi7ned in an edge of tie bar 100. Accordingly, the aforementioned
einbodiment provides a punch pin that can be botli pressed into and pulled out
of sheet
media via a siinple lii-Acage systeiu.
Aiother feature of the prefeiTed embodiment is a reduction in force needed to
pull
out a pin from a hole the pin has made in a stack of papers 51. In the
embodiinent shown
in Fig. 2, slot 19 has upper floor 18a and lower floor 1 Sa'. Slot 19 includes
anvil cavity 13
fonned in angled section floor 18c. Angled section floor 18c stu-rounds or
nearly
surrounds anvil cavity 13. Collectively, the floor sections 18a, 18a' and 18c
forin ai1
uneven or stepped punch element floor. Preferably, angled section floor 1 8c
is at a slope
angle of about 5 to 25 inclusive across a diameter of pin 20, including all
angles
therebetween, relative to generally level floor 18a or l8a'. According to
basic
trigonometry, an angle of 25 across the pin diameter corresponds to an
elevation change
of about 50 % of the pin diameter. An angle of 5 corresponds to an elevation
change of
about 8 % of the pin diameter. A1tenlatively, the uneven or stepped floor may
be locally
steeper than the given range of 5 to 25 . In such an embodiment, a nearly
vertical or
entirely vertical region of anvil cavity 13 can be formed in an area sinaller
than the
diameter of pin 20 in combination with or in place of the larger-area, 5 -to-
25 sloped
section floor 18c. According to the trigonometric relationship described
above, in this
smaller area, the elevation change across the pin diaineter preferably ranges
inclusively
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fioin about 8 % to 50 % of the pin diaineter. In still other alten7ative
embodiments, sloped
section floor 18c may be angled anywhere from about 2 to 90 inclusive.
The distance between upper floor 18a and ceiling 18b may be a paper
thicl(lzess
limit. More generally, the smallest height of slot 19 can serve as the paper
thiclcness
limiter, and in Fig. 2, this is the height at the left side of slot 19 or the
distance between
18a and 18b. The paper thiclcless limit defines the capacity of the punch
element or hole
punch device and restricts the punch element or hole punch device to use with
a pre-
detennined nunlber of sheets of a given thiclaless paper. The capacity may be
selected to
match available leverage or pressing force, or for marlceting reasons.
Aiiother way to describe the locally angled or stepped section floor is in
relation to
a paper guide slot in a multi-element hole punch. In such an asseinbly of a
hole punch
structure (not shown), two or more punch elements are spaced side-by-side.
Each punch
element appears as in Fig. 2 to provide for separate holes in a stack of
papers. Slots 19 of
the two punch elements define the paper guide slot, with co-planar floors 18a
or 18a' being
the bottom of the slot. The paper normally lies in the plane defined by floors
18a or 18a'.
This plane may be called the "slot plane." This plane may be visualized in its
relevant
direction by extending the opposed edges of papers 51 of Fig. 2. It may be
described by a
general level for floors of adjacently spaced punch elements that liold the
position of
papers 51 as defined by the same position on each punch element, for example,
floor 18a'
of each punch element. Angled section 18c is therefore described as a bent
area local to
pin 20 that is sloped at about 5 to 25 out of plane, or comparably, an
elevation change of
about 8 % to 50 % of the pin diameter across pin 20. This local bent area in
floor 18c
guides and offsets the paper stack out of the slot plane near pin 20 when the
paper stack is
compressed by pin 20. In an alternative einbodiment, the slot floor may
include local
arcuate portions to create such an offset.
Notably, the term "plane" is intended to include a non-linear, sloped, and/or
arcuate
floor for the in and out direction, or left to right in Fig. 1. The "paper
path" defined by
floor 18a, 18a' and angled section floor 18c may alternatively be described as
a bent line
bisecting the respective pin axes of the multiple elements rather than a bent
plane
comlecting the nlultiple elements. The paper is bent to follow the uneven or
kinked paper
path as pins 80 of multiple punch elements press the paper against respective
bases of the
elements.
In a conventional, multiple punch element design, the floors define a
straight,
smooth, and slightly inclined path. hi contrast, angled or stepped section
floor 18c or
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equivalent structtue in the preferred embodiment of the present invention
defines an offset,
out-of-plane or out-of-line section from the generally straight inclined path
to create a local
bend in papers proximate to each pin. fi1 the instance of a smootll inclined
path, if ceilings
18b of the respective elements are at the saine level, then the slot heigllt
is different for
each element. Typically, the smallest height portion of the smallest slot 19
defines the
maximum paper thickness in the multiple-element hole punch device.
As seen in Fig. 2, when pin 20 presses on papers 51 held in slot 19, the
papers are
forced to bend to follow the surface contour of angled section 18c. As a
result, the angled
entry of pin 20 into the papers causes the apparent shape of pin 20 at the
papers to be an
oval. The resulting hole created by pin 20 in papers 51 is also an oval with
its long axis or
diaineter slightly larger than the actual diameter of pin 20.
Optionally, the entire surface of the floor may be angled as with angled
section
floor 18c to foim the out of path section. In this einbodiment, the fonnerly
level surfaces
of floors 18 and 18a' would now be sloped. This worlcs best if the floor
stuface generally
underlying the punch element is narrow from side to side to avoid a large
elevation change
from one side of the pin to the other. That local area generally underlying
the pin may
span a width of just smaller than the pin diameter to a width of up to about 5
pin diameters.
By fiirther extending the size of the angled section of floor 18a and 18c --
higher on the
left in Fig. 2 and lower on the rigllt -- papers 51 will be offset more than
necessary. The
extreme offset may be apparent to a user who might find the appearance
peculiar, and may
hinder the ease with which papers can be fed into slot 19. Consequently, the
extreme
offset requires an excessively tall slot 19 for clearance, which carries over
into undesired
increased bulk of the hole punch device.
Similarly, a highly inclined path coiulecting together multiple punch elements
can
provide oval holes. However, the resulting slot height at the lowest area of
the floor would
be unsatisfactory for typical spacing between multiple punch elements. It is
thus desirable
to have a substantially inclined floor or path, but with a size limited to the
immediate
vicinity of the pin. With this aiTangement can the hole be usefiilly oval
while maintaining
a reasonable slot height for all punch elements and suiTounding support
stnictures.
The force of adhesion of pin 20 wit11 the inside wall of the punched hole is
reduced
when the hole is oval shaped and the pin cross-section is a circle. The
benefit is greatest if
papers 51 are tilted from the angled position to a peipendicular position
about pin 20
before the pin is withdrawn. In the angled position, the oval hole remains
tightly fit
around the pin since the hole was created in this condition. But if the paper
is tilted to be
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substantially perpendicular to pin 20, the hole effectively expands to be
larger than the pin
diameter along the long axis of the oval hole. The short axis remains the
salne size relative
to the pin. As mentioned above, the slope of angle section 18c relative to
tlie liorizontal
floor 18a should preferably be greater than about 5 or the oval shape will be
too subtle to
be very effective. If the angle is greater than about 25 across the pin
diameter, pin 20
might slide along papers 51 more than actLially cutting through the papers.
Also, the pin
will be too strongly biased off the pin axis by the angled entry into the
papers and might
not properly enter anvil cavity 13. Through empirical observations, the slope
angle is
more preferably about 10 to 15 111cILlslve lllcludlllg all values between
the limits and
most preferably about 11 to optimize the above-mentioned benefits.
In Fig. 2, floor section 18c is angled off the perpendicular with respect to
the pin
axis, while ceiling 18b is horizontal. As pin 20 is withdrawn in an upward
stroke, papers
51 tend to adliere to the pin. The papers are pulled up against ceiling 18b.
At this
moment, papers 51 are tilted and re-oriented toward the perpendicular since
ceiling 18b is
perpendicular to the axis of pin 20. As a result and as shown in Fig. 6, oval
hole 50 then
has a loose fit about the circular cross-section of pin 20. In its more flat
orientation, oval
hole 50 is generally larger in area than pin 20 and contacts the pin only at
the two
tangential areas shown in Fig. 6. The hole is thus easily distorted toward a
round shape to
fit loosely about pin 20, enabling a low force withdrawal of pin 20 out of the
punched hole.
A conventional round hole or near-round hole that fits tightly around the
entire
circtmzference of the pin has no ability to be distol-ted for a loose fitment
around the pin,
other than by stretching or tearing the paper material. Hence, the force
needed to witlldraw
the present invention pin from the punched hole is thus reduced significantly.
An oval shaped pin with an oval anvil cavity 13 creates an oval hole in a
conventional punch device, but unless the hole is actually larger than the pin
as disclosed
here, there is minimal advantage in reducing pull out force. Thus, in one
alternative
embodiment, an oval pin (not shown) installed in the asselnbly of Figs. 1 and
2, with anvil
cavity 13 being similarly oval shaped would provide reduced pull out force.
Ili general, it
is not required that the pin be precisely round according to the present
invention.
The present invention fiu-ther colitelnplates an efficient hole pullcll design
that
enjoys reduced cutting forces. In particular, it is preferred that the pealc
forces are reduced.
In a preferred embodiment, an asynunetrical cutting end of the pin enables
such reduced
peak forces. In Figs. 2 and 4, it is seen that in the asyinlnetrical cutting
end, lower cutting
point 21a cuts papers 51 before upper point 21b by virtue of the cutting
poilits being at
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different heights or levels. Therefore, the two cutting points 21a, 21b cut
into papers 51
via different approaches and at different moments in time at any position of
pin 20. The
different engaging cuts of ctitting points 21a, 21b reduces the overall pealc
forces since the
pealc force is the sum of the forces acting on cutting points 21a, 21b and
upper vertex 21c,
and at a given position of lower point 21 a, its cutting action occurs vvllen
upper point 21b
is not perfoi7ning a difficult cutting action. In Fig. 2, lower poin.t 21 a
has broken through
the last page of papers 51 and entered anvil cavity 13. The force from lower
point 21 a is
past the break-through peak. At this moment, upper cutting point 21b is
perfonning the
pealc force entry cut. So the required force on pin 20 is primarily from only
one of the two
points, namely, upper point 21b in the position shown in Fig. 2.
Sequentially, the cutting force peaks when the point 21a first enters papers
51, then
second point 21b engages the papers, and finally when upper vertex 21c first
enters the
papers. In the interim, as the inteimediate pages are being cut, the force
encotultered by
pin 20 is lower. As lower point 21a cuts througli the intei7nediate pages,
upper point 21b
enters the first page. The two cutting points meet at upper vertex 21c. Upper
vertex 21c
may be off center as shown in Fig. 4 so that the two cutting points are at the
respective
high and low positions while the angle of the cut notch to make the points is
the saine to
each side of upper vertex 21c. Cutting points 21a and 21b are a specified
axial distance
from vertex 21c to define a groove height. Cutting forces may be minimized if
the groove
heigllt is preferably at least twice the miniinum slot height between floor
18a and ceiling
18b.
Figure 3a shows an alternative embodiment pin cutting end. Center point 21d
provides an additional cutting point and additional vertices to create an
approximate
inverted "W" profile as depicted in the drawing. The "W" profile provides a
smooth
cutting action near the end of a stroke of pin 20 since the additional
vertices are available
to shear papers. Also, the center vertex of the "W" profile is preferably
slightly off the
center axis of pin 20. hi various altenzative embodiments, the "W" profile may
be
modified with fewer or additional vertices with peaks of tulifonn or varying
amplitudes,
creating a serrated surface. The "W" profile of Fig. 3a optionally includes
asyinmetrical
outer cutting points 21a and 21b similar to the asyinmetrical ctitting points
21a, 21b of pin
20 shown in Fig. 4. ,
In Fig. 2, angled floor 18c may serve an additional fi.ulction to the redtlced
pin pull
out force discussed above. If a syinmetrical cutting end is used for pin 20
where cutting
points 21a and 21b are at the saine axial position or height on pin 20, the
syirunetrical
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cutting points can still cut sequentially, i.e., at different moments in time
since the point
adjacent to the higher level of floor 18a -- the left side in Fig. 2 -- cuts
first before the other
point. Therefore, the use of angled floor section 18c provides reduced cutting
force even
with syinmetrical cutting points. A syminetrical pin may then be used in
combination with
angled floor 18c to provide sequential cutting end action. Or a slightly
asynuiietrical pin
may be used and the angled floor eiillances the sequential cutting action.
It is desirable that pin 20 maintain a fixed rotational position in fraine 10,
especially when the floor of slot 19 is not peipendicular to the pin axis.
With a fixed
rotational pin position, a particular cutting point, 21a in this example,
always faces left in
Fig. 2 and into the page in Fig. 1 where the point is adjacent to the highest
part of anvil
cavity 13. One advantage of a fixed rotational position is to ensure the
sequential cutting
action described above. In Fig. 2, cutting points 21a and 21b are held to each
side of the
step in the floor of slot 19. So even if the cutting ends are at the same
level, the points still
cut in sequence: point 21a first and point 21b next.
In the Figs. 3 and 4 einbodiments, pin 20 has an optional flat outer surface
22.
Thus, pin 20 includes a wide, D-shaped transverse cross-sectional area in the
portion with
flat side surface 22 where flat surface 22 transitions to a curved outer
surface of pin 20.
Top hole 15 of frame 10 includes substantially flat interior surface 16 acting
as a keyway,
as best seen in Fig. 5. Surface 16 may be slightly arcuate. The respective
flats 16, 22 are
thus keyed to each other. When assembled together, pin 20 slides axially in
frame 10
while supported by top hole 15 and guide hole 14. Pin 20, however, caiulot
rotate because
the keyed flat side 22 engages corresponding flat surface 16.
In an alternative einbodiment, pin 20 may be keyed to frame 10 by means of a
protrusion fitted to a longitudinal groove of the pin (not shown). For
exainple, top hole 15
may have an inward extending tab and pin 20 may have a coiTesponding
longitudinal
groove to receive the tab. The keyed flats 16, 22 of the illustrated
einbodiment are easier
to manufacture than a groove machined into a pin since flat 22 is a single
surface extended
to connect two edges of the cylindrical outer surface of pin 20. Flat surface
22 can be cut
in a direction peipendicular to the pin axis. In contrast, a longitudinal
groove or keyway
must be milled along the direction of the pin axis increasing manufacturing
cost and
complexity.
When papers 51 are inconipletely punched, a paper chip can remain attached or
dan.gling from the stack of papers. In the prior art hole punches, this
condition often
causes a ja1n; the chip becomes wedged in slot 19 and the papers caiuiot be
removed from
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WO 2007/027444 _ 14 _ PCT/US2006/032151
the hole punch device. The present invention, on the other hand, contemplates
that if the
circular chip is cut in a predetermined direction, this ensures that the cllip
caiu-iot become
wedged.
To illustrate, in Fig. 7, a partially punched stack of papers is shown. Chip
53
represents the small, stacked, circle of paper that is to be cut out. The
individual chips are
incompletely severed from the stack of papers and are attached by tabs 52
dangling the
chips. In the exemplary embodiinent of the present invention, upper vertex 21c
is
rotationally oriented as shown witli the lowest part of vei-tex 21c preferably
positioned
away from the open end of slot 19, i.e., to the left in Fig. 7. The highest
end of vertex 21c
is thus rotationally oriented nearest tab 52. If there is incoinplete cutting,
tab 52 is most
likely located near the open end of slot 19. With this pin 20 and vertex 21c
orientation, if
chip 53 remains attached to the stack of papers at tab 52, papers 51 can still
be forcibly
removed from slot 19 after pin 20 is raised since tab 52 caiulot catch on any
part of pin 20
or the surrounding hole punch stitiicture. Further, cliip 53 flexes about tab
52 and swings
back in plane with the surrounding paper material as the papers are pulled
from slot 19,
i.e., toward the right in Fig. 7.
On the other hand, if vertex 21c were angled oppositely to that shown in Fig.
7,
with the lower part of vertex 21c located nearest to the open end of slot 19,
then chip 53
can becoine jainmed after a partial cut. Specifically, the chip edge presses
inside anvil
cavity 13 and the ch.ip may bend over into the 11ole. This can be visualized
by assunling
papers 51 are forced to move to the left in Fig. 7 (disregarding the
tenninating left side
wall of slot 19). Chip 53 would fold downward into cavity 13 and backward to
effectively
double the thiclu-less of the papers. The papers will no longer fit in slot 19
and will
become jammed. Empirical testing has confinned this jamming behavior.
The cutting end of pin 20 may coinprise different configurations beyond that
shown. For exainple, syinmetrical cutting ends may be used. If tlle floor of
slot 19 were
angled as discussed below for Fig. 14, then a symmetrical pin has the same
benefit as that
discussed for Fig. 7. To provide the anti jamming benefit, the last area to be
cut, and
therefore the highest cutting edge of pin 20 or lowest area of the floor,
should be facing at
least generally toward the open end of slot 19. To maintain this orientation
of the cutting
edge, a rotational positioning feature such as flats 22, 16 described above
may be used.
In summary, there are various possible cutting end designs for pin 20
including
syinmetrical and asyminetrical cutting points. These cutting ends may be used
with
various designs for the angled seginents in the floor of slot 19 such as
different angles or
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WO 2007/027444 - 15 - PCT/US2006/032151
shapes as discussed above. For each coinbination of these variables, an
optinlum
rotational position for pin 20 may be empirically detennined where januning as
described
in the preceding paragraph is minimized. Figure 7 shows one such combination
and
rotational orientation for pin 20. hi any combination, the stiLicture
described at the upper
portion of the pin can hold the pin cutting end in a selected orientation as
required.
In an alteniative embodiment, an expanding sleeve is used to redtice the pull
out
force of the pin. Figure 8 shows coinponents of a paper punch element
according to this
alternative einbodiment. Housing 160 includes slot 165 to fit an edge of a
stack of papers.
A pin assembly is slidably fitted in chainber 164. According to this
embodiment, the pin
assembly includes two components, central pin 120 fitted within sleeve 110.
Pin 120 at
the top end has pin head 124 with a slightly enlarged diameter and near the
bottom groove
122 forined around the circumference of the pin. Sleeve 110 has a
loiigitudinal gap 115
sparuiing end-to-end and an inward extending rib 113 fonned in the
circumference near the
bottom thereof.
Norinally, pin 120 is in a rest position witll a sliglltly raised position
relative to
sleeve 110 as seen by the space between sleeve top edge 114 and head lower
face 124a in
Fig. 8A. Also while in the rest position, rib 113 fits into groove 122, and
gap 115 is closed
or nearly closed. Pressing down upon pin head 124 forces sleeve cutting end
112 into the
papers (not shown). The resulting upward axial force on sleeve 110 and
downward force
on pin 120 cause pin 120 to slide farther down into sleeve 110, and the space
at edge 114
is reduced or eliminated. When the space at edge 114 is reduced or
eliininated, continuing
to drive down on head 124 concurrently displaces sleeve 110 downward.
Groove 122 of pin 120 includes top wall 123 and lower wall 126. As pin 120
slides down within sleeve 110, top wall 123 presses circuinferential rib 113.
The resulting
wedge action, as best seen in Fig. 8B expands sleeve 110 into a slightly
enlarged diameter.
Gap 115 splits farther open enabling the diametrical increase, as seen in
Figs. 9 and 10.
This diametrical expansion via increased gap 115 ranges between about 1% to 3
%
inclusive of the sleeve diameter. During the upward, pull out stroke, sleeve
110 is retained
on pin 120 by rib 113 engaging groove lower wall 126.
Sleeve cutting end 112 may be continuously cuigled so that the hole is cLlt
progressively from one side of the hole diameter to the opposite side. Or
cutting end 112
may include two or more cutting points. Sleeve 110 may be formed from sheet
steel,
where the sharp cutting edge shown is ground before the sleeve is rolled into
the tubular
shape shown. The sheet steel preferably has some elasticity or resilience.
Tllus, as the pin
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assembly of pin 120 and sleeve 110 is pressed tlirough the papers, sleeve 110
easily
expands. When the downward pressure is relieved, sleeve 110 contracts to its
rest position
due to springback, forcing pin 120 upward, restoring space at top edge 114,
and closing
gap 115. Sleeve 110 is then smaller in diaineter than the hole it just created
in the paper
enabling a low fiiction pull out of the pin assembly from the hole in the
paper. By
maintaining preferably about a 1 % to 3 % dialnetrical enlargeinent, gap 115
will not
become so large to inhibit cutting action of the lower edge of sleeve I10.
Lastly, it is
contemplated that the locations of the rib and the groove can be reversed so
that the groove
is fonned in the sleeve and the rib is fonned in the pin.
Figures 11 to 16 show an altenlative einbodiment of the solid-pin based punch
element of Figs. 1 to 7. In this einbodiinent as seen in Fig. 15, pin 80
includes transverse
slot 84 with step 83. Fraine 60 includes 'a hollow interior to fit retunz
spring 90. Retunl
spring 90 is preferably a torsion spring. The spring has upper end 91 and
lower end 93 and
preferably dual coils 92. Coils 92 are positioned remotely from pin 80 rather
than coaxial
with or adjacent to the pin as with prior art helical return springs. As
illustrated, coils 92
are housed within an enclosed space of frame 60 for improved appearance and
protection
of the spring. Of course, frame 60 may optionally include openings in front
wall 65 and/or
in one or more of the side walls. Face 85 of pin 80 contacts edge 61 of frame
60 in an
uppennost position of pin 80 (not shown) according to one einbodiznent of a
stop structure.
Upper spring end 91 engages slot 84 against step 83. As seen in Fig. 12, lower
end 93 fits into recess 62 of fiame 60. Lower end 93 preferably includes an
optional bent
segment as shown to extend into recess 62. Upper end 91 presses ceiling 84c of
slot 84 in
pin 80. Ceiling 84c is optionally angled as shown in Fig. 14 so that return
spring 90 is
biased to press against vertical shelf 83, to the left in Fig. 14. Retlinl
spring 90 therefore
provides a lifting bias to pin 80, which must be countered by the user during
a downward
punching stroke of the pin.
In a preferred enibodiment, return sprin.g 90 is a double torsion spring
including
two substantially concentric coils 92, but other spring configurations such as
a leaf spring
or cantilevered spring can be used. The fiuzction of coils 92 is provided by
the helical
coiled portion of the spring, wliere the helical coil for this puipose is the
coil of a torsion
spring. In the return spring 90 of Fig. 16, two arms 95 are joined by a com.-
iecting segment
at upper end 91. Anns 95 angle toward each other moving from upper end 91
toward coils
92. Anns 95 may then wrap circuinferentially around a portion of the body of
pin 80 to
retain the spring against the pin. This wrapping retention may act in addition
to or instead
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WO 2007/027444 _ 17- PCT/US2006/032151
of the angle bias discussed for ceiling 84c. Anns 95 inay include fiu-ther
distinct bends
(not shown) to more completely suiTound or wrap pin 80 from behind the pin.
Using the
upper and lower fi'tment of return spring 90 to frame 80 as described, the
spring is securely
held in the assembly.
Torsion spring coils 92 can store substantial energy in a coinpact space in
contrast
to conventional return springs. Such conventional springs have typically been
simple
colnpression springs sun'ounding the pin and pressing a spring clip that is
fitted around tlie
pin. With a lower energy helical compression spring as in the prior art, the
bias force
increases greatly as the pin is pressed downward. But the conventional
compression
spring camiot fit a large nuna.ber of coils in the limited space surrounding
the pin, and
fewer coils mean a higher spring constant k and a stiffer action. An
inescapable result of a
stiff action is that the force to operate the conventional hole punch is
needlessly high as an
operating handle is pressed downward toward its limit. This effect is
particularly evident
when fewer stacked paper sheets are being punched. With conventional hole
punches
then, most of the effort is used merely to overcome the force of the return
spring in many
applications. This is best obseived by pressing a conventional punch with no
papers
inserted yet the downward force on the handle is uiuiecessarily high.
In contrast, torsion spring coils 92 are positioned remotely from and are not
placed
coaxially with pin 80, as seen in Fig. 14. Aims 95 of spring 90 may be
relatively long.
Then a given pin displacement causes a relatively small angular deflection of
coil 92
resulting in a small increase in spring bias. This is a specific advantage of
a torsion spring
functioning as a return spring over a helical conlpression spring fitted
coaxially or in
parallel to the ptuich pin.
Optionally, a long, flat bar or other elongated, axially bendable spring may
be
attached to the punch device at a location remote from pin 80 and extended to
pin 80 to
bias the pin upward out of the punched hole. In still another alternative
embodiment, a
helical compression type spring may be remotely mounted from pin 80 with
extended
upper and lower arms stretching radially from the spring (not shown). More
precisely, a
helical spring coil may be situated axially parallel along side pin 80 but not
be mounted
coaxially to pin 80, while the coil tenninates in stranded wire arins at
respective upper and
low ends with the ternninal wires extending radially outward toward pin 80.
Here, the
helical spring is not placed primarily Lulder coinpression but rather bends
along its axis
during deflection as the extended anns move toward each other with pin 80. The
bending
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and biasing action of the helical spring as applied to this embodiment is
tllus similar to
coiled torsion spring 90.
As similarly discussed above for Figs. 1 to 7, pin 80 is axially movable or
slidable
in frame 60 within lower guide opening 68 and tipper gitide opening 64. The
pin is
rotatably fixed by flat 82 of pin 80 abutting flat 66 of opening 64, as best
seen in Fig. 13.
For manufacturing efficiency, slot 84 and flat surface 82 may extend
transversely in a
parallel direction as shown.
Pin 80 is further rotatably positioned by engagement with spring 90 as
described
above. The coiulecting seginent at upper end 91 optionally includes two
corners as shown.
As spring 90 wraps around pin 80, these two spring conzers of upper end 91
engage step
83 to hold pin 80 rotationally. In an alternative embodiment, pin 80 may be
positioned
primarily or entirely by engagement with spring 90. Other geometries may be
used to
rotatably lii-ik pin 80 to spring 90 or other type of rettun spring. For
example, a helical
spring may include one or more wires extending radially to engage recesses or
slots in a
pin and in frame 60. Alternatively, a flat leaf spring may contact pin 80 at
an edge of the
flat spring.
There are various constructions for lii-ilcing a punch pin to an actuating
mechanism
such as a lever or handle. For example, an aiulular groove on the pin may fit
into a slot of
an actuating meinber. However, the groove caiulot rotationally secure or
immobilize the
pin. To address this rotation, the pin may be notched as a keyway to accept an
extension
or key from the supporting fraine. This then rotationally fixes the pin. But
such a notch is
difficult to cut into the cylindrical surface of a typical pin. A dowel may
bisect the pin
through a drilled hole in the pin. This can rotationally secure the pin, but
again it is
difficult to manufacture. In particular, it is a complicated process to drill
through a
cylindrical part, and tedious to assemble a dowel into such an assembly.
In Figs. 12 and 14, tie bar 200 is shown with optional leg 201 extending into
slot
84. See also Fig. 15. Tie bar 200 is part of a hole punch device that includes
an actuating
handle (not shown) similar to handle 107 of Fig. 1. The handle is linlced to
tie bar 200 to
press downward upon the tie bar. The handle is also preferably linlced to tie
bar 200 so
that the tie bar may be pulled upward through, for example, a linkage shown as
lever 107
in Fig. 1. Other actuating devices may be used to move tie bar 200 such as a
cam, l~lob,
motor, or other user interfaces lczown in the art. Other configurations for
tie bar 200 may
be used as well, such as a "U" chaiuzel, "Z" fonn, a bent rod, or flat fonn.
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As tie bar 200 presses pin 80 downward, leg 201 presses lower horizontal wall
84a
of slot 84. When pulling upward upon pin 80, leg 201 presses upper horizontal
wall 84b of
slot 84. As discussed above, return spring 90 presses ceiling 84c immediately
above upper
wall 84b. The tenn "slot" is intended to encolnpass the various structures
just described
that provide the ftulctions of walls 84a and 84b and ceiling 84c. b1
alteniative
embodiments, the slot may be in the form of steps, ridges, teeth, serrations,
indentations,
grooves, or the like. Optionally, ceiling 84c and upper wall 84b may be a
coinlnon
surface. Then leg 201 reinains under retunl spring 90, but presses upward on
upper end 91
of spring 90 directly. Or alternatively, return spring 90 could be located
tuldenleath leg
201, and leg 201 presses lower wall 84a via a thickness or diameter of return
spring 90.
Spring 90 then biases pin 80 upward through a thiclc-iess of leg 201.
Slot 84 and flat 82 are preferably cut to a depth of about halfway througli
the
diameter of pin 80. This provides a substantial surface for the respective
actions of flat 66
and leg 201, as seen in Fig. 13. Flat 82 and slot 84 may be cut from the same
direction as
shown so that the tenninating wall of slot 84 and flat 82 face the same radial
direction.
Such a structure may be optimal for production since a single machining
operation can cut
all such features. Alteniatively, flat 82 and slot 84 may face opposite or
different radial
directions. Flat 82 may be modified to include an arcuate portion, curved
either along the
axial direction (side view) or along the radial direction (end view).
In another embodiment, spring 90 does not engage an individual pin 80. Rather,
a return spring acts to bias tie bar 200 upward. The tie bar in tuni biases
pin 80 upward by
pressing upper wall 84b. The retunl spring may be a torsion, helical, flat or
bar spring.
Tie bar 200 preferably links to and actuates more than one punch element. Of
course, the tie bar may optionally be linked to and operate a single punch
element. Lever
107 of Fig. 1 or like actuating devices operate tie bar 200 and tie bar 200 in
tuni actuates
either a single or nzultiple punch elements. The pullch elements are supported
by
stu-rounding hole punch structtues (not shown). Such stn.tctures normally
include, for
instance, an attaclunent member to hold the punch elenient or elements to the
device, a
lil-Jcage to an actuating handle or lever, a ruler with detents for precisely
spacing the punch
elements a specific distance apart, and a receptacle to receive cut out paper
chips.
In Figs. 11 to 13, frame 60 includes feed slot 69 with floor 69a and ceiling
69b.
Floor 69a may have a locally angled portion as described in colnlection with
Figs. 1 to 7.
Ti7 the embodiment shown in Fig. 12, however, the locally angled portion
includes a"V"
shaped indentation in floor 69a having sides 67 angled off the perpendicular
to the pin axis
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and meeting at vertex 67a. The "V" shaped indentation is foi7ned with opposed
sides 67
bending downward froin the generally flat surface of floor 69a; the legs of
the "V" span
the area of floor 69a local or proximate to each pin 80. In various preferred
embodiments,
the span of the legs of the "V" shaped indention falls within a range of about
just under 10
% of the pin diaineter up to 5 pin diameters. The indented sides 67 are partly
visible in
Fig. 13. In Fig. 12, papers 51 are deflected out of plane to approximately
follow the "V"
profile. As pin 80 is retracted after cutting a hole in papers 51, the papers
are slightly
lifted and flattened against ceiling 69b; this lifting and flattening re-
orients the angle of the
papers in the area of the pin to be approximately perpendicular to the pin's
elongate axis.
The punched hole is elongated on each side of the basic circular opening to
forin an
oval shaped hole similar to that shown in Fig. 6. The retraction or pull out
force is thus
reduced as discussed earlier. A1tenlatively, the indentation in floor 69a may
be a "U"
shape, a groove, a dip, a channel, a step down or other profile including
simply a lowered
central,area. For best performance, it has been enipirically detennined that
the angle of
sides 67 should be preferably between about 5 to 25 inclusive, includiiig
all angles
therebetween, relative to the surrounding floor 69a or relative to a
perpendicular off the
pin's elongate axis. hi still other altei77ative embodiments, the angle of
sides 67 may fall
within a range of about 2 to 90 inclusive. As discussed for Fig. 2, the
preferred angle
corresponds to a change in elevation. Across the pin diaineter the indented
design of Fig.
12 includes half the elevation change coinpared to a single angled seginent
for an eclual
angle of the segments. This is because the angle extends for half the
distance, one half the
pin diameter according to the current trigonometric relationships. Therefore,
to use the
figures from the discussion of Fig. 1 to 7, the angular range of 5 to 25
coiTesponds to a
vertex 67a that is lower than floor 69a by a depth ranging fiom about 4 % to
25 % of the
pin diameter.
Another way to describe the angled floor section is in relation to a paper
guide slot
in a multi-element hole ptulch. In an assembly of a hole punch structure (not
shown), two
or more punch eleinents like that shown in Fig. 12 are spaced side-by-side to
provide for
separate holes in a stack of papers. liidividual feed slots 69 of the two
punch elements
collectively define the paper guide slot, with at least one portion of floor
69a being the
bottom of the slot. The paper nonnally lies in the plane defined by a sanie
portion of the
floor 69a on each spaced punch element. This plane may be called the "slot
plane." The
slot plane may be visualized in its relevant direction by the extended
direction of papers 51
in Fig. 12. It is described by a general level for floors of adjacent spaced
elements to
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define the position of papers 51. Indented and sloped sides 67 have a local,
approximately
to 25 out of plane area or bend near to each pin 80. This local slope or bend
guides the
paper out of plane, or offset, near pin 80 when the paper is pressed by pin
80. The tenn
"plane" is intended to include a non-linear floor for the in and out
direction, i.e., left to
5 right in Fig. 11. The path defined by floor 69a and indented sides 67 may
alternatively be
characterized as a bent line bisecting the respective pin axes of the multiple
punch
elements rather than a bent plane comlecting the multiple punch elements.
A fiirther altenzative embodiment of the present invention is shown in Fig.
14.
Floor 369 is angled front-to-back into feed slot 69, i.e., side-to-side in the
profile view of
Fig. 14 or between closed rear end 69c of feed slot 69 and the opposed open
front end.
The angle of floor 369 may slope from low to high in the left-to-right
direction in Fig. 14
to provide a large open front end, or be sloped from high to low (not shown)
to provide a
small open front end.
Several benefits are realized with front-to-back angled floor 369. In Fig. 14,
pin 80
is shown in an intermediate position. In this exemplary embodiment, cutting
points 21 are
syinmetrical meaning that they are at the same axial position of pin 80.
However, for the
selected rotational position of pin 80 shown, the cutting points press into
the papers (not
shown) held in feed slot 69 in a sequence of right to left due to the angled
or sloped floor
369. The required force to cut a hole with this symmetrical pin is thereby
reduced
comparably as with an asyinmetrical pin.
A reduced cutting force can also be achieved if the "V" indentation of sides
67 of
Fig. 12 is located off center (not shown) with respect to the pin axis. In
such an
arrangement, a syinmetrical pin presses each side 67 and then the papers upon
the sides 67
in this sequence. These effects are similar to that discussed earlier for
angled floor section
18c in coiui.ection with Fig. 2. As suggested by the preceding discussion,
points of a punch
pin may cut in sequence througll one or a combination of an asyimnetrical pin
and/or a
non-perpendicular floor of a paper slot with respect to the pin axis. To
provide a distinct
sequence in pin cutting with a syininetrical pin, the angle of floor 369
slaould preferably be
greater than about 5 .
Another benefit of inward angled floor 369 is realized when the punch element
is
used with feed slot 69 in a vertical orientation. The angle of floor 369 makes
the fiill depth
of feed slot 69 more visible to a user when angled floor 369 optionally tilts
toward a user.
For example, a punclling device may be designed to fit the element in a
position rotated
90 clockwise froin the position shown in Fig. 14. The device may be designed
for use
CA 02619806 2008-02-19
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witli cutting points 21 nonnally facing the user. With this arrangement, feed
slot 69
extends and opens upward. Feed slot 69 also angles toward the user t11us ei-
diancing the
convenience for the user. Optional surrounding stntctures may ftu-ther guide
papers
toward and within feed slot 69.
In the exemplary embodiment of the present invention in Fig. 14, ceiling 69b
is
perpendicular to the pin axis. Optionally, ceiling 69b may angle in the same
direction as
floor 369 to more clearly define an insertion orientation for papers. Or
ceiling 69b of Fig.
14, or any other illustrated punch element, may angle away from floor 369, or
69a, to
provide a wider opening for feed slot 69 to facilitate inserting papers. In
either of these
examples, ceiling 69b is not perpendicular to the pin axis.
A still further benefit of angled floor 369 of feed slot 69 is that pin 80
creates an
oval hole in papers if the angle off perpendicular from the pin axis is
greater than about 5
and less than about 25 . The front-to-back angle of floor 369 may rise upward
toward rear
closed end 69c as shown in Fig. 14, or floor 369 may altenlatively angle
downward toward
closed end 69c. The cutting and pull out benefits as described are equal. This
pin pull-out
force reduction is analogous to the force benefits discussed in coiulection
with Fig. 2 and
side-to-side angled floor 18c, and with the indentation with sides 67 in the
Fig. 12
embodiinent. If ceiling 69b is perpendicular to the pin axis, then the pin
pull out force is
reduced as discussed in coiulection with Figs. 2 and 12.
Creating the oval hole using angled base 369 also allows a shaip angle while
maintaining a compact slot height because there is no cumulative increase in
height over a
long distance. As with angled section 18c of Fig. 2 or "V" sides 67 of Fig.
12, the angle of
base 369 and the associated elevation change are localized to each punch
element.
In Figs. 11 and 14, frame 60 includes an outer, upper, lead-in surface 65 that
is
angled and a lower lead-in surface 63. Upper lead-in surface 65 angles closer
to pin 80
when moving toward a tennination at slot 69. In Fig. 14, lead-in surface 65
provides a
paper lead-in guide into slot 69. hnportantly, lead-in surface 65 is angled
for substantially
the ftill height of franie 60 above slot 69. By contrast, conventional punch
element frames
include such a lead-in surface only as a filleted transition between the paper
slot and the
outer surface, similar to the area shown in Fig. 11 as the comer where upper
lead-in
surface 65 joins ceiling 69b. But upper lead-in surface 65 includes an angled
or curved
profile along most or all of the length of pin 80, unlike conventional
designs. Indeed,
frame 60 includes lower guide opening 68 and upper guide opening 64. Upper
lead-in
surface 65 includes a length parallel to the pin axis extending between near
the levels of
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WO 2007/027444 - 23 - PCT/US2006/032151
these respective openiulgs 68, 64. Along the length of upper lead-in surface
65, tlie surface
angles closer to pin 80 moving from the level of upper guide opening 64 down
toward
lower guide opening 68. Lead-in surface 65 may alteniatively form an enclosing
wall of
the enclosed space of fiaine 60 as shown. The upper lead-in stuface 65 tlius
provides an
effective guide to help position papers within slot 69 at tlie location of the
punch element.
In various alternative einbodiments, a low friction coating or material may be
added to pins 20 or 80. Pins 20 and 80 are preferably made from hardened
steel.
Electroless nickel optioiially coats the pin at least in the areas below
groove 25 (Fig. 3) or
slot 84 (Fig. 15). hi Fig. 17, plating 300 coats pin 20, 80.
Electroless ilickel plating is also known in the industry as cheinical or
autocatalytic
nickel plating. Unlike an electroplating (i.e., galvanic plating) teclulique,
electroless nickel
plating involves chemical nickel plating batlls that work without an extenlal
current
source. The plating operation is based on the catalytic reduction of nickel
ions on the
surface being plated. Electroless nickel has one advantage for plating tiny
contours of a
cutting pin: the coating grows at unifonn speed over the surface of the
component. Precise
contours can be covered evenly and those surface contours followed fairly
precisely.
Subsequent machining is not necessary.
Three common types of electroless nickel coatings are nickel-phosphorus,
nickel-
boron, and poly alloys. Nickel-phosphorous is the preferred type to plate hole
punch
coznponents. Typically, electroless nickel plating is deposited by the
catalytic reduction of
nickel ions with sodiuin hypophosphite in acid baths at pH 4.5-5.0, aiid at a
temperature of
about 85-95 C. The plating alloy obtained is dependent upon the chemical
composition of
the solution and the operating conditions. The phosphoitits content
significantly influences
its chemical and physical properties in both the as-plated condition and after
optional heat
treatment.
Electroless nickel plating with low phosphorus contents between about 3 % - 7
%
have high wear resistance and high surface hardness (e.g., up to 60 Roclcwell
C). A
phosphorus content of about 9 % - 12 % exhibits corrosion and abrasion
resistance, and
lower surface hardness (about 45-50 Rockwell C). Finally, a phosphoitits
content of about
10 % - 13 % produces a coating that is very ductile and corrosion resistant.
The higher
phosphorus content plating meets the demands for corrosion resistance against
chlorides
and simultaneous mechanical stresses.
Thus, electroless nickel when alloyed with or coii.taining phosphorus,
exhibits
increased wear resistance and chemical resistance. In the application for a
paper punch,
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WO 2007/027444 - 24 - PCT/US2006/032151
wear resistance is of interest. Percent phosphorus may range from about 2 % -
13 %,
inclusive of the upper and lower limits and all ainounts therebetween, with
lower ranges
tending to manifest better wear resistance aii.d lubricity. In the present
hole punch
application, the phosphoitiis content is more preferably about 4 % - 6 %.
Other hard low
friction surface treatments may be applied to the pin to provide a low
friction, low wear
interface between steel of the pin and edges of paper.
Electroless niclcel is preferably applied in a thickness of about 0.0001 -
0.001 inch,
inclusive of the upper and lower limits and all amounts tllerebetween,
although other
thiclalesses outside this preferred range are possible. The specified range of
thiclulesses
provide the desired improved properties without increasing the part dimension
excessively
or causing processing difficulties. More preferably, the electroless nickel on
a pin has a
plated thiclaless of about 0.0003 - 0.0006 inch.
Once the pin is plated, the electroless nickel provides an interface between
the pin
body and the edges of the paper at a punched hole. For example, the partial
hole of Fig. 2
in papers 51 includes paper edges pressing pin 20. As described above,
electroless nickel
is a low friction material, especially compared to the bare surface steel of
the pin.
Therefore, as plated pin 20, 80 slides within the hole, it moves into the hole
and retracts
out from the hole with reduced friction. With easier moveinent of plated pin
20, 80, the
handle force is redticed and the force of rettull spring 90 or the other
spring may be
reduced.
Cutting points 21a and 2lb of the pin 20, 80 remain shaip at plating edges or
points
320 in Fig. 17. Iii contrast, galvanic plating on a ptulch pin creates a
concentration or
globule of plating at edges 320, resulting in a rounded or blunted point. The
rounded point
reduces the effectiveness of the cutting action of the pin. Another advantage
of having a
hard, IUbrlclous, electroless nickel plating covering the sharp points is
reduced wear at
those points. The electroless nickel fonns a sharp cutting edge at the cutting
points as
shown in Fig. 17. Optionally, the pin may be ground or machined to create the
shaip
cutting points after the plating is applied. Sleeve 11'0 (Figs. 8-10) may also
be electroless
nickel plated, resulting in cutting end 112 remaining sharp and the sleeve
sliding more
easily on central pin 120.
It is understood that various changes and modifications of the preferred
embodiments described above are apparent to those skilled in the art. Such
chailges and
modifications can be made witllout departing from the spirit and scope of the
present
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WO 2007/027444 _ 25 _ PCT/US2006/032151
invention. It is therefore intended that such changes and modifications be
covered by the
following claims.
