Note: Descriptions are shown in the official language in which they were submitted.
HIGH EFFICIENCY TORSION SPRING TACKER
FIELD OF THE INVENTION
[0001] The present invention relates to spring energized tackers. More
precisely, the present
invention relates to a tacker with improved efficiency of assembly and
operation.
BACKGROUND
[0002] Staple gun tackers and the like with energy storage via a power
spring are known. A spring
is deflected to store energy for sudden release to impact and drive a fastener
into a work piece. Most
commonly associated with manually operated hand tools such as a staple gun, a
power spring based
driving tool may also operate with a motorized system. A power spring may
include a compression
type, elongated bar, or torsion wire spring. With manual staple guns, a tool
housing may include
formed sheet metal, die cast, or resin molded. The sheet metal construction
has most often been
associated with compression springs and, less often, bar springs. One example
of a sheet metal bodied
staple gun is the T-50 brand of tacker, while many other such tackers are also
known. Torsion springs
are generally associated with molded or die cast housings; these are effective
for providing the
supports and guides for operating torsion springs.
[0003] The various springs may be used in a low start tacker, wherein the
striker starts an
operating cycle from a normal rest position in front of the staple or fastener
track, and a high start
where the striker normally rests above the staple track to start an operating
cycle. In either case, there
must be a release system to suddenly release the striker to instantly move
down under the spring bias
to eject a fastener. It is common that the release for one or both are
imprecise and a source of force-
adding friction.
1
Date Recue/Date Received 2020-09-02
[0004] A guide track for staples or fasteners is located along a bottom of
the tool. Staples may be
inserted from the rear or at the bottom among other known arrangements. Rear
loading designs are
prone to jamming since the staples cannot be easily accessed near the track
front where jams may
occur. Bottom loading exposes the full staple storage area for access as the
track slide out rearward.
A track pull with a latching structure is required to hold the track in its
operative position. Such
latches can be unwieldy and require aesthetic compromise.
SUMMARY OF THE INVENTION
[0005] In various preferred embodiments, the present invention is directed
to a spring energized
fastening tool with compact, low friction working elements. In the preferred
high start embodiment, a
torsion power spring includes at least two forward extending arms with the
arms pressing each other
proximate a front distal end of the spring. One embodiment has a rigid and
movable four bar assembly
that links the handle to the power spring and deflects the spring to separate
and deflect the arms
immediately upon pressing the handle. A further embodiment has a cantilevered
lever engaging the
spring adjacent to the striker. A release link preferably nests within a front
portion of the handle
whereby the release moves directly with the handle about a common pivot hinge
during a release
portion of the handle stroke. This structure provides reliable and repeatable
release action.
[0006] Various preferred structures are provided to enable fitment with a
formed sheet metal
handle and housing. The illustrated structures are compatible to fit within
the confines of a standard
T-50 type tacker, for example, while also being well suited to other sheet
metal, molded and die cast
bodied tackers. As fitted, the fastening tool is particularly simple to
assemble, powerful, and of low
operating effort.
[0007] In the preferred embodiment, a bottom loading staple track is
compatible with a sheet metal
housing among other housing structures. The track unlatches and opens through
a simple pulling-out
action.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a partially cross-sectioned, side elevational view of a
fastening tool in a rest
condition according to one embodiment.
[0009] FIG. lA is a detail view of FIG. 1 showing a lower front corner
area.
2
Date Recue/Date Received 2020-09-02
[0010] FIG. 2 is a rear, top perspective view of the fastening tool of FIG.
1.
[0011] FIG. 3 is the tool of FIG. 1 in a pressed condition.
[0012] FIG. 3A is a detail view of a top front area of the tool of FIG. 3.
[0013] FIG. 4 is the tool of FIG. 1 in a pre-release condition.
[0014] FIG. 4A is a detail view of a top front area of the tool of FIG. 4.
[0015] FIG. 4B is a partial transverse cross-sectional view of a front area
of the tool of FIG. 4.
[0016] FIG. 5 is the tool of FIG. 1 in a released condition.
[0017] FIG. 5A is a detail view of a top front area of the tool of FIG. 5.
[0018] FIG. 6 is a front perspective view of the tool of FIG. 5.
[0019] FIG. 7 is a front top perspective view of a handle link pivot
support.
[0020] FIG. 8 is a front perspective view of a handle to lever link.
[0021] FIG. 9 is a rear perspective view of a release latch.
[0022] FIG. 10 is a top front perspective view of a lever.
[0023] FIG. 11 is a rear bottom perspective view of a striker.
[0024] FIG. 12 is a front top perspective view of a link bar.
[0025] FIG. 13 is a top front perspective view of a front cover.
[0026] FIG. 14A is a side elevational view of a power spring in a rest
condition.
[0027] FIG. 14B is the spring of FIG. 14A with the spring partly deflected
in phantom and the
spring in a pressed condition.
[0028] FIG. 14C is a top perspective view of the spring of FIG. 14A.
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Date Recue/Date Received 2020-09-02
[0029] FIG. 15 is atop, front perspective view of an absorber assembly.
[0030] FIG. 16 is a side elevational view of a fastening tool in a rest
condition showing operative
parts according to an alternative embodiment.
[0031] FIG. 17 is a cropped side elevational view of the tool of FIG. 16 in
a pre-release condition.
[0032] FIG. 18 shows an assembly step of an upper handle sub-assembly to a
lower tacker
structure.
[0033] FIG. 19 is a detail view in perspective showing a handle and lever
linkage during an
assembly step.
[0034] FIG. 20 is a rear top perspective view of a rear handle link pivot
support according to the
alternative embodiment.
[0035] FIG. 21 is rear perspective view of a handle to lever link according
to the alternative
embodiment.
[0036] FIG. 22 is a side, rear perspective view of a lever according to the
alternative embodiment.
[0037] FIG. 23 is a rear elevational view of the link of FIG. 21.
[0038] FIG. 24 is a side, bottom perspective view, partly in cross-section,
of a track chamber
subassembly.
[0039] FIG. 24A is a top, side perspective detail view of the subassembly
of FIG. 24.
[0040] FIG. 25 is a rear detail view of the subassembly of FIG. 24 with the
track in a de-latched
condition and moving to open.
[0041] FIG. 25A is atop, side perspective detail view of the subassembly of
FIG. 25.
[0042] FIG. 25B is the view of FIG. 25A with the track moving to the closed
position.
[0043] FIG. 26 is a side, front perspective view of the subassembly of FIG.
24 with the track
pulled out for staple loading.
4
Date Recue/Date Received 2020-09-02
[0044] FIG. 27 is a bottom, front perspective view of a track pull.
[0045] FIG. 28 is a bottom front perspective view of a track pull bias
spring or latch spring.
[0046] FIG. 29 is a side, bottom perspective view of track guide chamber.
[0047] FIG. 30 is a side, bottom perspective view of a staple track.
[0048] FIG. 31 is a bottom, side perspective view of a tacker inverted in
position in preparation for
bottom loading of staples and fasteners, with the track in its closed
operative position.
[0049] FIG. 32 is a cropped view of the tacker of FIG. 31 with the track
pull de-latched.
[0050] FIG. 32A is a detail view of the tacker of FIG. 32.
[0051] FIG. 33 is the tacker of FIG. 32 with the track partly opened to
expose a staple loading
chamber.
[0052] FIG. 34 is a detailed top rear perspective view of the tacker of
FIG. 33, in the upright
position.
[0053] FIG. 35 is a handle force F (y axis) versus travel distance D (x
axis) plot illustrating the
performance advantages of a rigid handle-to-spring linkage.
Date Recue/Date Received 2020-09-02
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0054] The present invention is directed to a compact, efficient spring
energized tacker that may
operate and be fitted within a formed sheet housing body or like standardized
body. The drawings
show a preferred embodiment tacker that has a body sized and shaped similarly
to a known
commercially available tacker operable with T-50 style staples up to 1/2" or
9/16" long. However, the
features of the present invention function with tackers of other shapes,
sizes, and constructions
including molded resin and die cast. For example, one or both of housing 10
and handle 20 may
include sheet metal, molded resin, and/or die cast metal. In describing a
tacker, such term may include
staple guns, nail guns and equivalent fastening tools whether motorized or
manually powered to
energize a power spring.
[0055] In the preferred embodiment tacker of Fig. 1, for example, the
length of the tool from the
rear end to front end is 7-1/4 inches long. In Fig. 4B, housing 10 totals
approximately 0.9 inch wide at
the dimension W (W being doubled from approximately 0.45 inch to include the
opposed housing side
that is not shown). Other sizes, shapes and dimensions of the housing, handle,
and other operating
parts are contemplated.
[0056] In the assembly drawings Figs. 1 to Fig. 6, a right side of the
housing is removed and
handle 20 is depicted in cross-section to show internal components. Housing 10
has a front (right side
of Fig. 1), a rear, a top, and a bottom. Fig. 1 shows a rest condition of the
tacker. Handle 20 is in an
upper position above housing 10, and it is pivotally attached to housing 10 at
a handle/housing pivot,
here hinge pin 110 near the top of the housing. At the bottom of housing 10 is
a staple track 180 that
supports staples biased forward by spring-driven pusher 400. Handle link pivot
support 28 includes
pivot hinge 22. Link 30 has pivot 32 fitted to hinge 22 defining an upper end
or equivalent location of
a linkage assembly. A lower end of link 30 includes slot 33 to engage hinge 43
of lever 40. See also
Figs. 7 to 15 for the individual components. Lever 40 includes pivot tab 45 to
engage groove 65 of
link bar 60. Link bar 60 engages pivot, hinge pin or hinge element 96 of power
spring 90 at link bar
hole 66. Hole 66 may define a lower end or equivalent structure of the linkage
assembly that begins at
hinge 22. The linkage lower end is below and substantially forward from the
linkage upper end. As
seen in Fig. 1, imaginary vertical line L between the pivot structures of
hinge pin 110 and element 96
is well forward of hinge 22; as illustrated, line L is close to the forward
structure or blade of striker 70.
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Date Recue/Date Received 2020-09-02
[0057] As seen in Figs. 2 and 3, the power spring 90 pivots about mandrel
106. Power spring arm
94 extends from spring coil 93 to spring arm tip 95. Tip 95 engages opening 79
of striker 70,
preferably directly as shown or through another linking member in the
immediate local position.
Latch 50 is preferably pivotally attached to the tool assembly by recess 57 at
handle hinge pin 110. In
Fig. 3A, tab 54 of the latch 50 engages opening or edge 74 of the striker 70
to selectively immobilize
the striker.
[0058] The motions of the parts described above are shown by comparing
Figs. 1 and 3. Pressing
handle 20 about hinge pin 110 causes link 30 to move downward. Lever 40 pivots
about hinge 41 to
cause link bar 60 to move downward. The linkage assembly thus forces spring
arm 92 to deflect
downward or equivalent direction. Striker 70 cannot move downward from the
action at latch 50, so
spring arm 94 remains in an upper position as seen in the pressed position of
Fig. 3. Power spring 90
becomes deflected with spring arm 92 spaced away from spring arm 94. Power
spring 90 is thereby
energized for an operating cycle to eject fasteners from track 180. In Fig.
3A, hinge pin 22 has just
made contact with tab 53 of latch 50 while handle 20 is in a low but not
lowest position. Moving the
handle farther toward the lowest position of Fig. 4 starts the latch 50
rotating to disengage striker 70 as
described next.
[0059] In Figs. 4 and 4A, the pre-release condition has latch 50 disengaged
from striker 70. Tab
54 is moved away from opening 74 so striker 70 is now free to move down. It is
preferred that the
release of striker 70 occur as close as possible to the handle's lowest
position. This handle lowest
position, Fig. 4, is defined by contact to bumper 25 of handle 20 against a
surface of housing 10 or
equivalent action. Thus, there is minimal jump or jerking of the handle 20
upon release for reduced
operator fatigue. Further, the force of an operator's hand presses directly on
the housing body 10
through bumper 25 to help hold down the tacker as it fires. To move the latch
50 as described, the pin
or equivalent structure of hinge 22 presses tab 53 of the latch. The latch 50
rotates about hinge pin
110 to slide tab 54 out from the striker 70. The preferred latch motion is
precise, reliable and
repeatable since it is directly tied to a short portion of the handle motion;
the latch begins to move only
during a late part of the handle stroke so its release motion is relatively
fast during the relevant handle
motion. Specifically, the latch release motion occurs only between the pressed
handle position of Fig.
3 and the pre-release position of Fig. 4, this being about 1/2" at the handle
rear for the exemplary model
shown. With all of the latch release motion concentrated near the end-of-
stroke, any tolerance
7
Date Recue/Date Received 2020-09-02
variation of the pre-release handle position will be confined to a pre-
determined position within this
small portion of the handle motion. The latch 50 operates about a common pivot
to the handle 20 so
there is no tolerance variation of intervening components; the latch and
handle move in unison during
release. There is also minimal net vertical force on hinge pin 110 since
handle 20 and latch 50 pull
oppositely on the pin. Therefore, the pin 110 can rotate with handle 20 about
its mounting on housing
with little force and friction at the housing mounting. This unified motion
reduces friction between
the latch 50 and the pin 110 as demonstrated in a working model and through
empirical testing.
[0060] In Figs. 4A, 9, the exemplary embodiment tab 54 has a preferred
acute angle of
approximately 89 degrees relative to an imaginary radial line extending from
hinge pin 110. An angle
within approximately 2 to 5 degrees of 90 degrees can be suitable to hold the
latch 50 stable on the
striker with minimal force on the latch required to move the latch as
described. Through empirical
observation, with the exemplary angle of 89 degrees, in the release action,
rotating latch 50 under load
as between Figs. 3 and 4, adds less than 1 lb., being about 1/2 lb., to a peak
handle force. This force is
effectively undetectable to a user. When measured at the handle rear in the
position of Fig. 4, the
required total force is approximately 15 to 16 lbs. to provide power
sufficient to drive 1/2-inch T-50
type staples flush in common construction wood applications, for example,
Douglas fir wood.
Therefore, the tacker provides tremendous staple driving energy while the
handle deflection effort as
perceived by the user is very low and smooth.
[0061] The linkage between handle 20 and striker 70 is substantially rigid
through the structures
described here. In the spring rest condition of Figs. 1, 14A and 14C,
pivot/support element 96 presses
spring arm 94 to hold power spring 90 preloaded. Figs. 3 and 14B show the
power spring deflected
and energized. Pivot element 96 is preferably a laterally extending portion of
a spring arm and may be
referred to as a "location of preload" or of preload force for the spring,
such location being spaced
from coil 93 to enable a preload torque on the coil. The lateral direction is
into the page in Figs. 1 and
18, being preferably, but not necessarily, perpendicular to arm 94 in Fig.
14C. This spring arm
crossing, Fig. 14C, may be at shallower angles. The pressing is preferably
directly between the
respective arms 92, 94 while the arms may also press in the local area through
further elements. Pivot
element 96, preferably but not necessarily along with tip 91, forms a hook to
hold the spring in the
preloaded condition at the location of preload. As the handle is pressed by
the user, pivot element 96
is forced downward. The force on striker 70 at tip 95 increases from near zero
to a final maximum at
8
Date Recue/Date Received 2020-09-02
the pre-release position of Fig. 4. This force is a torque on spring arm 94.
The spring arms 92, 94 are
of a functionally and intentionally resilient material being normally of a
same wire as the coil.
However, flexing forward of the location of preload is not useful as discussed
below; hence the length
of the portion forward of pivot element 96 is minimized in the preferred
embodiment.
[0062] To demonstrate this minimized forward portion length, in Figs. 1,
14A to 14C, spring arm
94 flexes in proportion to the length of the unsupported cantilevered segment
between pivot/support
element 96 and the striker location at tip 95. This effect is illustrated in
Fig. 14B: in phantom lines,
support element 96 is pressed down slightly from Fig. 14A until element 96 no
longer presses spring
arm 94. Spring arm 94 flexes as shown until support element 96 is no longer in
contact at Si. With
the loss of support at Si, the support shifts farther forward to the striker
at S2. This flexing to remove
the preload translates to handle 20 as a mushy start to the stroke and lost
energy input as discussed
below relative to Fig. 35. It is thus desirable to have Si be as close as
practicable to S2 as shown and
separately discussed to minimize the effect of this flexing.
[0063] As illustrated in Fig. 1, a distance between mandrel pin 107 or
equivalently a central axis of
the coil, or a spring coil central location, and striker 70 is approximately
2.06 to 2.11 inches. Most
preferably, this is a distance of approximately 2.11 inches, and is denoted by
dashed line Li in Fig. 1.
In this context, the striker location is defined as the rear plane of the
blade of the striker at engaged
opening 79. From support element 96 to striker 70 is a distance of
approximately 0.43 inch, as
denoted by line L2 in Fig. 1. L3 is the distance between mandrel pin 107 and
support element 96, and
L3 in this embodiment is approximately 1.70 inch. There is a distance ratio
L3/L1 of about 80% (i.e.,
1.70 in./2.11 in.). Therefore, the location of preload is forward of the coil
location about 80% of the
length of dashed line Ll. In Fig. 4 this distance places support element 96
adjacent to striker 70 in the
pressed spring condition, preferably clear of sidewalls 72 or other striker
structure by not more than
one spring wire diameter, although other spacings to the striker are
contemplated. A distance ratio
L3/L1 of more than 50% is preferable, while a distance ratio of more than
about 60 or 70%, is more
preferable to have spring arm 92 terminate adjacent the striker and thereby
see the benefits described
below, based on empirical observation. Other dimensions are contemplated in
proportion to other
overall tool sizes. The foregoing ratios or proportions are with reference to
the rest position of Fig. 1
although they are not substantially different in the released position of Fig.
5.
9
Date Recue/Date Received 2020-09-02
[0064] Flexing of cantilevered spring arm 94 as described above is felt as
a "dead bounce" at the
handle ¨ a mushy feel that is minimized in the present invention as discussed
above regarding Fig.
14B. Based on empirical observation and mechanical principles, this flex is a
waste of handle travel
and useable energy input as illustrated in the x-y plot of Fig. 35 discussed
in further detail below.
With such flex minimized, handle 20 is effectively rigidly linked to power
spring 90 at a location just
approximately 0.43 inch from striker 70 through the four bar style
cantilevered linkage, or an
alternative linkage arrangement, discussed below. With the short cantilever L2
of the "beam" of
spring arm 94 as described, there is minimal beam flexing and no perceived
dead bounce. Therefore,
user effort on the handle is perceptibly reduced, and the smooth operation of
the handle greatly
improves the feel of the tool for the user.
[0065] Figs. 14A to 14C show various views of a preferred embodiment power
spring 90. In Figs.
14A and 14C power spring 90 is in a preloaded rest condition. Pivot/support
element 96 is pressing
spring arm 94 in proportion to a preload selected for the particular power
spring characteristics.
Accordingly, there is a free position (i.e., unflexed) for the spring wherein
spring arm 92 is preferably
angled upward and pivot element 96 is spaced above arm 94 relative to the view
of Fig. 14A. A pre-
assembly step has link bar 60 (Figs. 1, 2, 12) assembled to power spring 90
with pivot element 96
passing through hole 66 in link bar 60. In the pre-assembly step, the spring
arms are then forcibly
moved from the free position to the position depicted in Figs. 14A and 14C to
form a sub-assembly of
link bar 60 and power spring 90 wherein the spring is preloaded. Tip 91 of
power spring 90 preferably
passes beside spring arm 94 to secure spring arm 94 on pivot element 96 and to
hold the assembly
stable. The assembly preferably has tip 91, link bar 60, and spring arm 94
laterally adjacent each other
along pivot element 96.
[0066] An alternative embodiment tool may use a power spring in the form of
a single or assembly
of flat bar springs instead of a coiled wire torsion spring. The bar spring
includes cantilevered legs
and is preloaded similar to Figs. 14A to 14C. The bar spring is mounted to a
mandrel 107 or like
fixture inside the housing.
[0067] In the present embodiment tool, a "four bar" or equivalent rigid
linkage forms the linkage
assembly to connect the rigid steel handle or equivalent rigid structure to
pivot element 96 of power
spring 90. In the four bar assembly, lever 40 is pivotally mounted at its rear
at hinge 41, depicted in
Date Recue/Date Received 2020-09-02
Fig. 1. Link 30 presses lever 40 toward a central portion of lever 40 at hinge
43 and the lever presses
link bar 60 at a front distal end of lever 40. Lever 40 is cantilevered
forward from its links at hinges
41 and 43 and therefore lever 40 can extend forward to a striker proximate
position. In this manner, a
vertical linear motion from the handle at link hinge 22 may be enhanced at
pivot tab 45, and thus on
pivot element 96 or equivalent structure, through cantilevered lever 40. As
shown between Figs. 1 and
3, the vertical travel at link hinge 22 is about doubled at pivot tab 45 since
the lever is pressed near its
center. However, if hinge 41 were located farther rearward in housing 10, this
doubled travel
decreases, with a factor of 1.1 still allowing usable lever geometries. Spring
pivot element 96 and
lever pivot tab 45 are substantially vertically aligned so pivot element 96
maintains the preferable, at
least 80% distance ratio discussed above. Thus, pivot element 96 is also
proximate the striker as
described.
[0068] All of the linking elements of the linkage assembly described here
may be made of steel so
there is no obvious or perceptible give or play in the system beyond that used
to store spring energy. It
is apparent from the above geometries that handle 20 should rigidly link to
power spring 90 at a most
forward position of the power spring. As shown in Fig. 1, this link at the
location of preload adjacent
to pivot element 96 is substantially aligned vertically with handle hinge 110,
indicated by vertical line
L in Fig. 1, whereby there is a position of line L that passes through or near
tangent with both pivot
element 96 and hinge 110. Described another way, line L is substantially
vertically coincident with
each of hinge 110 and pivot element 96 (preload location). Similar
considerations apply to Fig. 16 for
example. Similarly, link bar 60 extends vertically in or near alignment below
handle hinge 110, being
vertically coincident in this alignment as shown wherein a top view has some
structures of hinge 110
overlapping structures of element 96.
[0069] In the four bar system depicted in Figs. 1, 2 and discussed above,
there is a rear bar
including the structure of housing 10 supporting spring mandrel 106 and hinge
41, a front bar in the
form of link bar 60, a top bar being lever 40, and a bottom bar being spring
arm 92. Link bar 60 is
pivotally guided within this four bar system by pivot element 96 of the power
spring, Fig. 4B. The
torsion spring as described is thus particularly suited for the present four
bar system. Spring arm 92
provides both an interface to energize the spring and also a functionally
rigid member of the four bar
system to guide the lower end of link bar 60. These combined functions are not
possible, for example,
with a compression spring which is inherently unstable in lateral directions.
11
Date Recue/Date Received 2020-09-02
[0070] Fig. 35 is an x-y plot depicting empirical observations of
unexpected results and benefits of
the rigid structure described above. The plot shows comparative test results
from working models of
torsion spring tackers with similar tacking performance. It is based on
measurements of force F at the
distal or rear end of a handle (y axis) versus the distance D (x axis) that
the handle moves, with initial
handle free play omitted, but "dead bounce" included. The areas under the
respective curves
correspond to energy stored in the power spring. The "Long Arm" sample plot
has a first spring arm
pressed in preload by a second arm about halfway between the coil and the
striker, an arrangement that
would have L2 and L3 of Fig. 1 being close in value. In contrast, the "Short
Arm" sample plot has the
¨80% ratio discussed above, being pressed in preload closer to the striker. A
steep initial slope in the
Short Arm plot indicates a stiff linkage with reduced dead bounce and a quick
start to energy storage
(as shown in phantom in Fig. 14B and discussed above). The shallower slope of
the Long Arm plot
shows extra flexing or give between the handle and the power spring. As seen,
there is substantial
wasted handle motion up to about 0.4 inches of travel for the Long Arm, so the
Long Arm tacker
requires a higher handle force for similar performance. Accordingly, the
exemplary embodiment
Short Arm tacker enjoys measurable performance advantages over Long Arm tacker
designs.
[0071] The exemplary embodiments disclosed herein include a tensile link
between the striker and
the handle while enabling easy assembly of the tacker tool. This is further
advantageous in that if the
striker becomes stuck in a lower position, it is possible to forcibly move the
striker upward by pulling
the handle with a tensile force. As seen in Fig. 1, the link between link bar
60 and power spring 90 at
hole 66 is inherently multi-directional. The next connection is between link
bar 60 and lever 40. This
connection is between pivot tab 45 and groove 65 of link bar 60. During
assembly, lever 40 is rotated
counterclockwise about this connection to engage tab 68 above catch 48. The
tab and catch remain
engageable for all operative positions ¨ compare Figs. 1 and 3A for example.
There is a small
clearance to tab 48 to ensure normal compressive operation has only pivot tab
45 and groove 65
engaged. When lever 40 is pulled upward, catch 48 presses tab 68 from below to
pull link bar 60, and
thus the power spring and striker, upward.
[0072] Re-set spring 190 biases the relevant moving parts toward the rest
condition, Figs. 1 and 2,
in normal use. The re-set spring 190 pivots about leg 194 in hole 157 of
absorber 150, as per Figs. 1
and 15. In Fig. 2, absorber 150 is omitted to show underlying elements. In
Fig. 4B, at its upper end,
12
Date Recue/Date Received 2020-09-02
angled leg 193 engages opening 67 of link bar 60, with an angle of leg 193
biasing spring arm 192 to
be retained in the opening.
[0073] The components including everything below link 30 are preferably
initially assembled so
that the lower tacker structure is complete, including both housing halves and
front cover 12. Only
parts associated with the handle remain to be attached so that there is no
need to hold various lower
parts in position as the handle is manipulated into the assembly. This eases
assembly effort for
volume production.
[0074] An upper subassembly includes handle 20, bumper 25, link support 28,
latch bias spring
130, and link 30, as in Figs. 1, 2. Latch bias spring 130 is supported about
hinge pin 22 at spring coil
133 and held in position at rear end 134, as in Fig. 3A. These parts are pre-
assembled to handle 20.
Link 30 hangs loosely from handle 20 about link hinge 22 before installation
to the lower tool
structure. In Fig. 2, link hinge pin 22 naturally forms a multidirectional
link within respective holes of
the two connected parts. Pin 22 also supports latch bias spring 130 in this
pre-assembly. As the
handle sub-assembly is installed, the elements of the lower structure are in
the rest condition of Fig. 1.
Latch 50 is placed atop lever 40 to rest against angled face 75 of striker 70,
in the approximate
position shown in Fig. 1. The tacker body and handle are positioned with the
tool front angled upward
to allow a lower end of link 30 to drop over hinge 43 at slot 33 of the link.
Hinge pin 43 (Figs. 3A,
10) is a pre-installed pin of lever 40. Rotating the link allows the handle to
line up at hinge pin 110 at
which point pin 110 is installed to support both latch 50 and handle 20. This
process is demonstrated
to be effective in a working model. In Fig. 3A, it is seen that rib 37 of the
link now cooperates with
lever tab 47 so that pulling up on handle 20 causes rib 37 to press tab 47
from below to transmit a jam-
releasing tensile force. Therefore, the preferred embodiment tacker benefits
from an anti-jam tensile
force available to link striker 70 to handle 20 operated by the user.
Optionally, some or all the
functions of link support 28 may be integrated into a handle structure, for
example, in association with
a molded polymer composite handle. For example, recesses in sidewalls of the
handle could support
link hinge pin 22 with latch bias spring 130.
[0075] The staple is driven from the present invention tool, and now in a
re-set action, striker 70
moves from its low released position of Fig. 5 to its upper rest position of
Fig. 1. In Fig. 5A, it is seen
that moving striker face 75 upward will cause latch 50 to rotate
counterclockwise in the view. This
13
Date Recue/Date Received 2020-09-02
cam action persists until latch tab 54 lines up with striker opening 74, such
as Fig. 3A. Latch 50 then
rotates clockwise under the bias of re-set spring 130 as the tab enters
opening 74 to assume the
position of Fig. 1. Latch 50 now selectively holds striker 70 in its upper
position. Tabs 55 contact
face 75 to hold latch 50 in a position in opening 74 that clears a radius at
the base of tab 54, as in Fig.
1. In the conditions shown in Figs. 5A and 6, striker 70 is down and out of
engagement to latch 50.
As handle 20 rises in the re-set stroke, the latch tends to rotate clockwise
from re-set spring 130. In
Fig. 3A, latch 50 has a stop against the housing formed by housing notch 11
against latch tab 56 to
limit this rotation to the operative position shown in the drawing when the
striker is not present. Thus,
tab 54 of latch 50 remains in a position forward of face 75 whereby the re-set
cam action of the latch
and striker may occur.
[0076] In Fig. 5, striker 70 includes a blade or plane defined by its
position at 78 immediately in
front of track 180. It is preferable to minimize any element of the tool that
extends forward past this
position 78 to ensure a staple can be installed reasonably near a confining
wall, corner, or like
obstruction. Further, a compact front of the tool maintains a beneficial line
of sight for the user for
aiming the tool. In Figs. 1, 5A and 13, the tool includes an optional hump 12b
in front cover 12 to
clear power spring arm tip 95. Also handle 20 extends forward in its pressed
position, Fig. 5A, but no
farther than hump 12b. To limit the handle or like extension, latch 50 engages
striker 70 at a position
behind blade 78 of striker 70. To do this as seen in Fig. 4A, striker 70
includes a dogleg or offset bend
76 whereby opening 74 is preferably spaced rear of blade 78 or main striker
structure. Latch 50 then
may rest and move rearward of the blade and/or cover 12, as in Fig. 1. Latch
50 is located near or at a
top of striker 70 as shown in Figs. 1, 2. Latch 50 being disposed in the upper
location of the tool is
clear of the area occupied by re-set spring 190, absorber 150, and tabs 71, as
discussed below. By
utilizing this arrangement, there is abundant space in the front lower area of
the housing behind the
striker for these further parts to be assembled, to operate, and to function
well.
[0077] In Fig. 2, to provide an impact stop against absorber 150, striker
70 includes horizontal tabs
71 bent from side walls 72. These tabs 71 contact absorber 150 in the low
striker position of Fig. 5
where striker end 78 is at a bottom of the tacker body. In Figs. 6, 11, to
reinforce tabs 71, striker 70
includes extensions 72a in contact with blade 78 at 70a immediately above the
tabs 71. These
extensions 72a provide a direct force path from the moving bodies of striker
70 and power spring tip
95 to tabs 71 to reduce bending stresses on the blade structure where the tabs
meet side walls 72.
14
Date Recue/Date Received 2020-09-02
[0078] It is common in a torsion spring tacker design that an absorber acts
directly on an arm of
the power spring ¨ in particular, that a dry fire, without staples, has the
absorber directly stopping an
arm of the spring rather than the striker. This causes an undesirable reversal
of forces in the spring
arm type absorber. In normal use when the tool is fired, spring arm tip 95
presses down at the striker
hole 79 (Figs. 6, 11) to install staples. But with the spring arm to absorber
contact structure in a dry
fire there is a reversal of force at the spring arm/striker interface. The
spring arms stops first, and the
striker overshoots the spring arm a small distance at hole 79 and impacts the
spring arm at the top of
the hole to be indirectly stopped by the absorber.
[0079] This overtravel action causes wear at hole 79 from both top and
bottom, leading to a
stretched, distorted, or enlarged hole, added tensile stress on the striker,
and increased vertical free
play of the striker about the spring arm. In the extreme, the hole is so ovoid
that spring arm will not be
able to raise striker high enough to set the latch or reach a release height.
As described herein,
absorber 150 acts directly on striker 70. Therefore, striker 70 is always one
of accelerating, pressing a
staple, or pressing the absorber. Spring arm 94 at tip 95 thereby always
presses down within hole 79
and thus wears the hole in only one direction with minimal tensile stress on
the striker in this area.
From empirical observations, this arrangement improves longevity and operating
life of the tool.
[0080] Further, in the case of a spring wire/absorber interface, the wire
spring arm provides a
small impact target for the absorber leading to high stress in that contact
area. In the present preferred
embodiment, any target area on power spring arm 94 is further interrupted by
the useful forward
location of pivot element 96 at the front distal end of spring arm 92,
corresponding to a short L2 length
in Fig. 1. While keeping this segment L2 short, which is useful as discussed,
it provides a small
absorber target. With the absorber contact being against a structure of or
affixed to the striker, the
absorber can directly vertically underlie the distal end of arm 92, for
example, at pivot element 96. As
best seen in Figs. 1 and 5, absorber 150 extends rearward of pivot element 96.
This structure may be
described as having an alignment along a vertical line of at least absorber
150 and the distal end of arm
92 with handle hinge 110 also preferably so aligned above absorber 150, and
with spring coil 93
rearward of this alignment. In an alternative embodiment, there may be an
additional or only absorber
contacting arm 94 or other structures that move with the striker.
Date Recue/Date Received 2020-09-02
[0081] As shown in Fig. 11, the impact stop (horizontal tabs 71) are bent
directly from the material
of the striker 70 to preferably minimize weight and inertia of the
reciprocating impact parts, although
separate components may be used. It is desirable that the mass of the striker
and any other parts that
move in the impact or firing stroke be minimized. When these parts are kept
light weight, the tacker
installs staples and the like more effectively, especially when the tacker is
actuated with a single hand.
Consequently, the body including housing 10 will not jump substantially upward
as the staple exits
since the body is very heavy compared to the fast moving but light weight
striker. This gives the user
a damped, less jarring feel from the tool with reduced hand fatigue. As shown
in Fig. 11, striker 70
includes optional openings above and below spring opening 79 to further reduce
its weight.
[0082] Housing 10 preferably includes two halves. A left half is shown in
the views of Figs. 1 to
6. The halves must be secured in a properly spaced relation for effective tool
function. In Figs. 1 and
2, mandrel 106 is supported by pin 107. This pin 107 may be a screw or rivet
to compress the housing
about the mandrel. Mandrel 106 thus holds the housing securely spaced apart
for operating clearance
for spring 90 and further holds the housing halves from sliding relative to
each other. At the lower
front of the housing in Figs. 1 and 2, plate 155 holds the housings apart
while front cover 12 clamps
the housing from in front. Housing plate 155 preferably supports rubber
absorber 150 in an absorber
assembly, shown in Fig. 15. In the cut away cross-section of Fig. 1, track
chamber tab 129 extends
within slot 156 of plate 155. Fig. 2 also shows these parts with absorber 150
omitted for clarity. Tab
129 in Fig. 1 provides an accurate rear limit position relative to track
chamber 120 for striker 70 in its
upper rest position. In Fig. 2, striker 70 is laterally positioned by edges
157 of plate 155. To register
plate 155 to track chamber 120 laterally, tab 129 is a close fit in notch 156.
Thus, there is essentially
no tolerance build up from a more indirect link of the plate to the striker
and track through the housing
enclosure.
[0083] At the front top there is minimal room for a similar plate since,
for example, latch 50 is
advantageously located there. Preferably, as seen in Figs. 6 and 13, front
cover 12 includes
registration notches 19 to cooperate with housing tabs 17 during assembly.
With tabs 17 secure in
notches 19, the housing is held accurately spaced part in this area.
[0084] In the drawings and disclosure, a single power spring is shown. In
alternative
embodiments, there may be two or more of such springs. For example, two coiled
power springs 90
16
Date Recue/Date Received 2020-09-02
may be vertically stacked with a second mandrel 106 below the first mandrel,
in front of grip opening
18 in housing 10. Pivot element 96 of this second spring engages a second link
bar hole 66 (not
shown) below the first. In this alternative embodiment, the horizontal
distance between mandrel pin
107 and hole 66 (for both springs) is close to the same as that between hinge
41 and pivot tab 45. This
ensures that pivot tab 45 and both holes 66 remain aligned through their
motions to prevent binding.
In another alternative embodiment, two power springs 90 may be installed side
by side axially on a
common mandrel 106. As with the other disclosed embodiments, power spring 90
is pivotally
attached to the housing near or forward of a front of grip opening 18 whereby
arms 92 and 94 form
torque arms and extend from this position to striker 90. With relatively short
torque arms, there is
high force available at striker 70 for useful work, and further there is
minimal vibration in the arm
action as the short arms operate. If desired, longer arms may be used, with a
more rearward mounting.
Arm 94 may be described as a first spring arm while arm 92 may be described as
a second spring arm.
[0085] In Figs. lA and 13, front cover 12 includes raised bottom front edge
12a. This raised
portion may extend along the side walls of cover 12 rearward across striker
slot 13. In use, a tacker is
often held at an angle to the work with the rear end held up. With the
clearance described here, the
striker end 78 (Fig. 5) can still extend close to the work piece with front
cover 12 out of the way. This
front edge 12a may be raised by approximately 0.020 inch for example. With the
light weight
reciprocating compact parts discussed above and the tight contact here,
ordinary stapling will easily
produce driven staples that are flush with the work surface. Workpieces having
such fully installed
staples will hold the work more tightly and have a higher quality workmanship.
[0086] Figs. 16 to 23 show a second exemplary embodiment of the present
invention. Many
elements may be shared with the first embodiment described above and the
mechanical actions of
power spring 90, striker 70 and latch 50a are or may be equivalent. Distance
ratios described in
connection with the first embodiment may be employed in this second embodiment
as well. Also, the
geometries that the handle should rigidly link to the power spring at a most
forward position,
proximate vertical line L, may be applied in this embodiment. Finally, the
part count, friction, and
complexity are or may be reduced in the second exemplary embodiment.
[0087] In Fig. 16, handle 20 to lever link 330 pivotally connects handle
link support 328 to lever
340. Lever 340 directly engages pivot element 96 of power spring 90 at opening
366. Opening 366
17
Date Recue/Date Received 2020-09-02
may be elongated to provide for longitudinal (left-right on the page) motion
of power spring 90
relative to lever 340 at this location. Lever pivot 341 operates rearward of
spring coil 93 while lever
340 extends along a lever length forward past spring coil 93 to be disposed
adjacent to striker 70.
Link 330, at hinge 333, presses lever 340 at central lever pivot 343 toward a
central location of the
length of lever 340. Lever 340 is thus cantilevered forward from central lever
pivot 343 to the spring
location of preload on pivot element 96. In this manner, opening 366 is
proximate the location of
preload, being laterally adjacent (into the page of Fig. 16) along pivot
element 96. At least one of
spring arms 92 and 94 are likewise cantilevered forward from spring coil 93
whereby each of power
spring 90 and lever 340 are cantilevered forward to the location of preload.
As shown in Figs. 16-18,
both spring arms 92, 94 are so cantilevered.
[0088] The second exemplary embodiment depicted in Figs. 16 to 23 may
provide further reduced
friction and increased rigidity over that of the first exemplary embodiment in
Figs. 1 to 6. While the
first embodiment is substantially rigid, as seen in Fig. 35, the second
embodiment has one less
component between handle 10 and power spring 90, and thereby fewer pivotal or
other connections to
introduce flex or free play motions. Lever 340 is also longer than lever 40
and therefore rotates
through a smaller angle about its rear pivot 341 to move power spring 90. From
empirical
observations, it is about 12 degrees for the second embodiment versus 20
degrees of pivoting for the
first embodiment. With less motion there is less friction at the hinge of the
rear pivot.
[0089] A similar effect operates when comparing the central pivots of 43
and 343, respectively. In
Fig. 18, lever front opening 366 rotates in a same direction as spring pivot
element 96 to reduce sliding
there between, thereby reducing friction over the structure of Fig. 1 where
link bar 60 does not
substantially pivot along with pivot element 96. Whether considering the
second embodiment, Figs.
16 to 23, or the first embodiment of Figs. 1 to 6, each provides substantial
improvements and benefits
in function and utility over the prior art, for example, through a rigid
linking system as disclosed.
According to this rigid linkage system, the lever front end presses the second
arm at a lengthwise
position substantially closer to the striker than to the spring mandrel
center. This pressing occurs at a
front end of lever 40, seen in Fig. 1, or lever 340, seen in Fig. 16.
[0090] The second embodiment of Figs. 16 to 23 further enjoys simplified
assembly. In Figs. 19
and 23, link 330 is installed at hem 332 or equivalent structure into slots
329 of handle link support
18
Date Recue/Date Received 2020-09-02
328 while the parts are loose as depicted in Figs. 20 and 21. Link support 328
is then fastened to
handle 20 by riveting or the like, as in Fig. 16. Link 330 is thereby
pivotally confined on handle 20.
Hem or top end 332 presses and pivots against an underside of the handle as in
Fig. 17. This pivoting
is minimal, about 4 degrees as shown, so friction is low and slot 329 can be
narrow. With the upper
and lower respective assemblies prepared, seen in Fig. 18, the handle assembly
is lowered into
position as shown. Link 330 is held about at the angle shown to align with the
front wall of notch 344.
Link 330 is held out of the page in Fig. 18, and/or lever 340 pressed in, so
that the link may pass
beside lever 340 to assume the position of Fig. 19. In both Figs. 18 and 19,
handle 20 to body pivot 27
is forward of its final position. In Figs. 21 and 22, tab 335 of link 330 can
be seen able to enter notch
344 of lever 340. As seen in Fig. 19, handle 20 is then moved rearward to its
final position at pivot 27
as link 330 rotates to be guided by edge 348. Edge 348 then locks link 330
laterally, in a notch of the
link at tab 335, to a pivoting relation on the lever with respect to the side
views. Link 330 holds lever
340 stable laterally through a triangular geometry "T", as seen in Fig. 23.
Hem 332 presses inside
handle 20 to form a stable base of the triangle. The pivoting is at link hinge
333 against central lever
pivot 343, as seen comparing Figs. 16 and 17. A tensile link between handle 20
and power spring 90
operates through link 330 at slot 329 and edge 348 to enable the handle to
pull up on the spring and
striker in an event of a staple jam or the like.
[0091] Spring arm tip 95 is preferably on center with respect to a front
view to press striker 70 at
its center line, although an off-center alignment can also be functional.
Lever 340 therefore presses
spring element 96 off center at pivot 366 in a similar position as link bar
60; see Fig. 4B for this
analogous position at 66 in the first embodiment. Lever 340 is therefore
preferably off center, into the
page in Fig. 16, at its three operative pivots 341, 343, and 366 to form a
stable plane of action.
Segment 349 may be on center, out of the page in Fig. 18, to keep its
optionally exposed portion at a
clean joint line of housing 10.
[0092] In Fig. 16, latch 50a operates similarly to latch 50 as disclosed
with the first embodiment.
Rear end 53a selectively contacts handle 20 to cause the release action. In
Fig. 19, link tab 322
supports latch bias spring 130 at coil 133.
[0093] Figs. 24 to 34 show an exemplary embodiment staple guide track and
loading system
preferably used with the first and second embodiment tackers described above
while also providing
19
Date Recue/Date Received 2020-09-02
advantage for use with other tacker devices. The subassembly shown provides
for bottom loading
staples or other fasteners, as in Figs. 31-33. As seen in Fig. 33, track 180
selectively extends rearward
to expose staple holding channel 128. The track can extend farther wherein
track guide tab 188
contacts stop rib 125 of track chamber 120 or equivalent structure.
Preferably, the full extension has
tabs 188 at least about 4 inches rearward of front cover 12 to fit a standard
staple rack 405 of that
length. In Fig. 33, staple rack 405 is shown in position to be placed in track
chamber 120. Rack 405
is shown as about half standard length corresponding to the partially extended
track shown.
[0094] This exemplary embodiment bottom loading system is advantageous over
a rear staple
insertion system, because bottom loading keeps any staple readily accessible
when needed. For
example, it is much simpler to clear a staple jam or malfunction because, as
seen in Fig. 33, the staple
channel may be exposed for easy manipulation or extraction of such staples. In
contrast, a rear loading
system requires dismantling the track subassembly to access any jammed staples
at the front of the
tool.
[0095] The structure of the present track subassembly is suited for use
with a sheet metal bodied
tacker, although it is not limited to that application. For example, it may be
used with die cast or
molded bodied tackers. The preferred embodiment track subassembly includes
closely integrated
track pull 160 which de-latches track 180 from its operative position of Figs.
24 and 31, for example,
to its de-latched position of Fig. 25 through a simple pull rearward. Grasping
and pulling track pull
160 (Fig. 27) causes it to rotate about pivot 161 against a bias from latch
spring 140, discussed below,
to the position of Figs. 25 and 32A. Continuing the same pulling action causes
track 180 to move to
the extended position of Fig. 33 while the track pull preferably returns to
its normal upright or
equivalent position under the latch spring bias. Pushing track pull 160
inward, to the right in the
views, moves track 180 to its closed, operative position as in Fig. 31. The
track becomes latched to be
retained in position while the track pull remains upright or otherwise in its
normal position relative to
the track through a latching action.
[0096] The views of Figs. 24 and 25 have track 180 and track chamber 120
shown in lengthwise
cross-section to expose the internal workings. The latched track condition is
seen in Figs. 24 and 24A.
Rib 184 of track 180 (see also Fig. 30) engages detent 124 of track chamber
120 or equivalent
structure (housing 10, for example). In Figs. 24 and 28, spring front end 146
is held on at track
Date Recue/Date Received 2020-09-02
support 181 and held centrally at spring loop 143 by fulcrum 186. See also
Fig. 33 for fulcrum 186.
Latch spring 140 is therefore cantilevered at rear end 147. Cantilevered
spring rear end 147 presses
downward (upward in the page of the inverted views of Figs. 31-33) on track
spring contact tab 126,
Fig. 24. This is beneficial because track 180 is thus resiliently urged upward
relative to the track
chamber to press track rib 184 against detent 124. Upward in this context
means toward the handle
from the track area for any view orientation. Preferably, track pull arm 167
also contacts spring end
147 in the fully closed track condition so that the track pull does not
rattle.
[0097] Track pull 160 is pulled rearward to open track 180 to the position
of Figs. 33, 34. It is
natural to squeeze and pull it at sides 166 or pull the front edge in this
area, near part number "166" in
Fig. 24A. Track pull 160 rotates about hinge 161 to the position of Figs. 25,
25A. In Fig. 25, arm 167
has deflected spring 140 upward at end 147. Pulling outward on track 180,
indicated by an arrow in
Fig. 25, causes a downward bias on the track by a cam action from the angle of
detent 124 and rib 184.
Spring 140 does not resist this down motion since the spring is deflected off
of tab 126 by arm 167.
As a result, track 180 clears detent 124 as shown and is free to slide
rearward to the position of Fig.
26.
[0098] It is not required that the track pull rotate to deflect the latch
spring. Optionally, the track
can be directly pulled down to deflect the spring and clear detent 124 before
pulling out, for example,
through a track pull interface that cannot rotate. While this optional
structure does function, it requires
two steps. In contrast, the preferred track pull 160 provides an automatic cam
action that provides the
down motion automatically through a single step of an intuitive outward pull.
These features have
been demonstrated in a working model.
[0099] As best seen in Fig. 32A, track pull 160 is positioned laterally by
arm edges 167a within
track wall portions 185. The track pull is preferably a closely integrated fit
to the housing body as
seen in Figs. 1 and 31. The tool maintains a clean profile in the rear area,
being absent any track
release access cavity, for example. Track pull 160 may include or comprise
sheet metal, die cast,
plastic molded construction, or any combination thereof. In any embodiment,
the staple track remains
easy to operate by a simple pulling action as discussed.
[00100] As track 180 is closed, following the arrows in Fig. 25B, latch spring
140 is deflected by
the cam action at detent 124 and rib 184b causing the track to move down
toward tab 126. The tab
21
Date Recue/Date Received 2020-09-02
deflects the spring and moves the spring away from arm 167. In this manner
track pull 160 remains,
or at least may remain, in its upright position as an operator pushes the
track pull in a normal manner.
If, for example, the track pull required rotating outward during this motion
it would oppose the
operator's inward pushing force and would tend to lock up the system. Instead,
the track pull remains
stable, the action intuitive, and the closing operation ends in a satisfying
and positive click.
[00101] Latch spring 140 in Fig. 28 may be a simple wire form as shown. As
discussed above,
front spring end 146 rests on track support 181. Notch 186 in Fig. 33 forms a
fulcrum to hold spring
loops 143 whereby spring 140 is preferably preloaded in its rest condition of
Fig. 24 to keep the track
pull rattle free and to hold the track securely in the closed position. As
further seen in Figs. 24, 25,
25B, latch spring 140 is slightly bent concave upward from the preload so that
it is in contact or near
contact with both arm 167 and tab 126. Pusher spring 200 biases staple rack
pusher 400 toward the
front of the track, thus urging the staple rack toward the striker.
[00102] Pusher spring 200 is attached in a known manner to pusher 400. The
rear end of pusher
spring 200 is preferably fitted to latch spring 140 at loop 202 as shown in
Fig. 25. To install the latch
spring to the track, track spring 140 is inserted to loop 202 and then guided
by grasping pusher spring
200. Latch spring 140 is pressed into the channel of track 180 to deflect the
cantilevered arms of
spring 140 toward each other. When loops 143 are aligned with notches 186, the
latch spring snaps
into position. This has been demonstrated in a working model. A pulley at
recess 189 (Fig. 30) may
guide the pusher spring at front. Recess 189 forms an upward facing edge to
support a shaft of the
pulley in the track channel. In this manner, the pulley can be installed from
top into the channel to rest
on the edges of recess 189 rather than being installed from a side.
[00103] In track 180, notches 182 provide clearance for stop ribs 125 as the
track is deflected
downward, this being up on the page in the inverted tool view of Fig. 32. As
seen in Fig. 32, stop ribs
125 have entered notches 182. Similar clearance is created at notches 183
(Fig. 32A) to clear spring
contact tab 126 as the track pull is deflected. Notches 182 and 183 preferably
include a ramp at the
front as shown so that ribs 125 and 126 are guided out of the notch as the
track moves outward.
[00104] In a front most position track foot 187 contacts stop edge 123a, as in
Figs. 29 to 32.
Preferably, this contact is configured to hold pressure at the cam contact
area of rib 184 and detent
124, i.e., the rear cam feature presses foot 187 against edge 123a. Track
chamber tab 127a engages an
22
Date Recue/Date Received 2020-09-02
opening of front cover 12 to hold a position of the track chamber at front,
Fig. 127a. At rear the
chamber is held to the housing by a fastener in hole 127. Side channels 122 of
the track chamber
guide track feet 187. At the rear end of the track, tabs 187a preferably fold
across the track and may
be spot welded or the like to reinforce the track structure. Ribs 125 and tabs
126 are formed as part of
track chamber 120. The features of the track chamber may instead be formed
from a structure of
housing 10, for example, a sheet metal tab of the housing and the like for a
steel housing.
[00105] Staples are normally and properly installed into bottom-positioned
staple channel 128, as in
Fig. 33. However, it is possible that an operator may attempt to load the
staples from top onto the
exposed track of Fig. 34. In particular, if the staples are able to enter the
housing or tool interior on
the track from here, an operator may reasonably assume it is supposed to
function this way. Of course,
it cannot, as seen in Fig. 26; the staples would be rearward of pusher 400
with no way to reach the
front of the track for use. Negative user reviews of products that have this
defect affirm this issue.
[00106] To address improper staple loading, as seen in Fig. 34, there is an
optional staple blocker
16 that protrudes into the channel of track 180. It is an element of housing
10 although other
structures are contemplated. Also, it is both physically and visually clear to
the user that installing
staples from the rear is impossible, and the reason is readily seen.
Installing this way is clearly
improper, informing the user that the staples "go somewhere else" upon which
the bottom staple
channel is readily discovered. A blocking tab of the housing, or track
chamber, may extend inward
from a side to abut the outer side face of track 180 in this area. This is
seen as tab 16a in Fig. 34. It is
preferable that a blocker be visible at the tool exterior so that there is no
ambiguity to the staple
exclusion. Further, Fig. 34 shows optional track tab 184a. Track tab 184a
extends outward whereby a
staple rack cannot fit upon or past it. In the case of a full 4-inch staple
rack, tab 184a makes it
obviously impossible to place staples on the track from this direction. A
shorter rack such as 2 inches
may fit in the track portion in front of tabs 184a, but with tabs 184a and 16
collectively making
placement here clearly impractical, the message to the user to look elsewhere
in reinforced.
[00107] While the particular forms of the invention have been illustrated and
described, it will be
apparent that various modifications can be made without departing from the
spirit and scope of the
invention. It is contemplated that elements from one embodiment may be
combined or substituted
with elements from another embodiment.
23
Date Recue/Date Received 2020-09-02
