Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION: NAILER WITH RATCHET-PROVIDED PLUNGER
MECHANISM
FIELD OF THE INVENTION
The present invention relates to fastener discharge mechanisms, and more
particularly
to a miler for hardwood flooring having a ratchet-provided plunger mechanism
allowing a user to
strike multiple mallet blows on the plunger until the fastener has been driven
completely into the
workpiece.
BACKGROUND OF THE INVENTION
Hardwood flooring generally consists of a number of juxtaposed elongated
tongue-
io and-groove planks interlocked with each other, and then fastened in
position to a subjacent subfloor.
To fasten these hardwood planks to the subfloor of a room (composed for
example of plywood
plates and/or floor joists), it is known to use hardwood flooring milers. Such
milers can either be
manually or pneumatically operated.
Manually-operated milers generally comprise a main body with a floor-
engageable
i5 sole mounted to its bottom surface, upon which the tool rests against a
hardwood plank prior to
discharging a fastener in the latter. These milers also comprise a magazine
containing a frangible
strip of collated metallic fasteners, such as L- or T-shaped barbed cleats or
U-shaped staples, fed to a
fastener discharge mechanism. A plunger having an impact-receiving head member
at an outer free
end thereof is slidably mounted to and extends out of the miler's main body,
and a recoil spring
2 o biases the plunger away from the miler's main body into its extracted
position where it is extended
out of the miler's main body. The fastener discharge mechanism is activated
when the plunger's
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head member is struck with a mallet to cause the plunger to slidably retract
inside the miler's main
body to impact on a selected fastener of the fastener strip and drive this
fastener out of the miler and
into the subjacent workpiece. The fastener is fully driven into the workpiece
only if the plunger has
been struck hard enough so as to have retracted inside the miler's main body
up to a determined
retracted limit position.
After the plunger is struck, the recoil spring is used to resiliently bias the
plunger
head back to its initial extracted position.
In using the above described manual nailing machines, problems occur if the
user
does not strike the plunger with enough force to retract the plunger up to its
retracted limit position
io in which the fastener is fully driven into the workpiece. For instance, to
drive a partially driven
fastener the rest of the way into the workpiece, the user must again apply
enough force to the
plunger head to recompress the recoil spring. Accordingly, recompressing the
recoil spring several
times over the course of a flooring job can cause the workman to become
prematurely exhausted.
Furthermore, weaker users who are unable to retract the plunger all the way to
its
i5 retracted limit position with a single mallet blow may not be able to use
the miler at all.
To remedy this problem, certain prior art milers are provided with a ratchet
mechanism holding the plunger in intermediate positions after it is struck
with a mallet, until the
plunger reaches its retracted limit position, at which point the ratchet
mechanism is released and the
recoil spring is allowed to urge the plunger back to its rest or neutral
position. This feature gives the
2 o user the opportunity to strike multiple mallet blows on the plunger head
member to gradually move
towards the retracted limit position, in which the fastener has been driven
completely into the
workpiece. However, existing ratchet-provided milers have been found to wear
out or break too
rapidly.
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SUMMARY OF THE INVENTION
The present invention relates to a miler for driving a fastener into a
workpiece,
comprising:
- a main body defining a fastener ejection channel for accommodating a
fastener;
- a plunger movably carried by said main body and defining a first end for
receiving forceful
blows and a second end for engaging the fastener, said plunger carrying first
ratchet means and
defining a longitudinal cavity extending from said first end towards said
second end, said
plunger being movable relative to said main body between a first position in
which said plunger
second end clears said fastener ejection channel, and a second position in
which said plunger
to second end engages said fastener ejection channel for ejecting the fastener
from said miler;
- a stem member carried by said main body and penetrating said plunger
longitudinal cavity, said
stem member carrying second ratchet means capable of unidirectional releasable
interlocking
engagement with said first ratchet means; and
- a plunger biasing member continuously biasing said plunger towards said
first position;
i5 wherein upon a forceful blow being applied to said plunger first end, said
plunger will be forced
from said first towards said second positions and wherein if said plunger is
forced to an intermediate
position between said first and said second positions, said first and second
ratchet means will
cooperate in unidirectional releasable interlocking fashion to retain said
plunger in said intermediate
position against the bias of said plunger biasing member whereby said plunger
may be gradually
2o moved with several forceful blows from said first to said second position
without moving back
towards its first position until it reaches said second position.
In one embodiment, said first ratchet means comprises sets of alternating
teeth and
grooves made on a peripheral wall of said plunger longitudinal cavity, and
said second ratchet
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means is a spring-loaded pawl pivotally mounted to said stem member and having
a pawl tip
lockingly engageable in said grooves.
In one embodiment, said main body comprises an elongated plunger socket
defining
top and bottom walls and an elongated peripheral wall extending therebetween,
said plunger socket
s having an opening at said top wall thereof, said plunger socket comprising a
tubular liner extending
from said socket bottom wall to said top wall about said socket opening, said
plunger being slidably
received in said liner, and said stem member being located within said liner
and resting against said
socket bottom wall.
In one embodiment, said stem member comprises a lumen in which an elongated
io pawl spring and a ball are coaxially nested, said pawl spring continuously
biasing said ball towards
said pawl in order for said pawl to be continuously biased towards a neutral
position.
In one embodiment, said pawl is pivoted to a first pawl position when said
plunger is
moved from said first position to said second position and is located
therebetween, and when said
pawl is in said first pawl position, said pawl will cooperate with said teeth
and said grooves in
i5 unidirectional releasable interlocking engagement to prevent said plunger
to move towards said first
position. In this embodiment, said plunger cavity peripheral wall comprises a
first release clearance
registering with said pawl tip when said plunger is in said second position,
such that said pawl tip
can partially extend into said first release clearance when said plunger is in
said second position so
as return from said first pawl position to a neutral position, to allow said
plunger biasing member to
2o urge said plunger towards said first position without hindrance from said
pawl when said plunger
reaches said second position.
In one embodiment, said first release clearance is a release notch made
through said
plunger cavity peripheral wall at a position intermediate said set of teeth
and said plunger first end.
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In one embodiment, said pawl is pivoted to a second pawl position when said
plunger
is moved from said second position to said first position and is located
therebetween, and when said
pawl is in said second pawl position, said pawl will cooperate with said teeth
and grooves in
unidirectional releasable interlocking engagement to prevent said plunger to
move towards said
s second position. In this embodiment, said plunger cavity peripheral wall
comprises a second release
clearance registering with said pawl tip when said plunger is in said first
position, such that said
pawl tip partially extends into said second release clearance when said
plunger is in said second
position so as return from said second pawl position to said neutral position,
to allow said plunger to
be urged towards said second position without hindrance from said pawl when
said plunger is in
io said first position.
In one embodiment, said second release clearance is a gap formed beyond said
plunger second end.
In one embodiment, said main body further comprises a guide roller attached to
said
plunger socket and rollably engaging a guiding groove made on an outer surface
of said plunger.
i5 In one embodiment, said plunger further comprises a hammer blade at said
second
end, said hammer blade positioned so as to sweep said fastener ejection
channel when said plunger
is moved from said first to said second positions.
In one embodiment, said plunger biasing member is a spring linked to said
plunger
and said stem member.
2 o The present invention also relates to a ratchet-provided plunger mechanism
for
installation on a miler, comprising:
- a plunger for movable attachment to the miler main body and defining a first
end for receiving
forceful blows and a second end for engaging a fastener to be discharged by
the miler, said
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plunger carrying first ratchet means and defining a longitudinal cavity
extending from said first
end and towards said second end;
- a stem member for installation on a main body of the miler, said stem member
carrying second
ratchet means, wherein said second ratchet means are capable of unidirectional
releasable
s interlocking engagement with said first ratchet means, said stem member
penetrating said
plunger longitudinal cavity, said plunger being telescopically movable
relative to said stem
member between a first position in which said plunger is telescopically
extended away from said
stem member for said plunger second end to clear a fastener ejection channel
of the miler main
body, and a second position in which said plunger is telescopically retracted
towards said stem
io member for said plunger second end to engage the fastener ejection channel;
and
- a plunger biasing member for continuously biasing said plunger towards said
first position;
wherein upon a forceful blow being applied to said plunger first end, said
plunger will be forced
from said first towards said second positions and wherein if said plunger is
forced to an intermediate
position between said first and said second positions, said first and second
ratchet means will
i5 cooperate in unidirectional releasable interlocking fashion to retain said
plunger in said intermediate
position against the bias of said plunger biasing member whereby said plunger
may be gradually
moved with several forceful blows from said first to said second position
without moving back
towards its first position until it reaches said second position.
In one embodiment, said first ratchet means comprises sets of alternating
teeth and
2 o grooves made on a peripheral wall of said plunger longitudinal cavity, and
said second ratchet
means is a spring-loaded pawl pivotally mounted to said stem member and having
a pawl tip
lockingly engageable in said grooves.
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In one embodiment, said stem member comprises a lumen in which an elongated
pawl spring and a ball are coaxially nested, said pawl spring continuously
biasing said ball towards
said pawl in order for said pawl to be continuously biased towards a neutral
position.
In one embodiment, said pawl is pivoted to a first pawl position when said
plunger is
s moved from said first position to said second position and is located
therebetween, and when said
pawl is in said first pawl position, said pawl will cooperate with said teeth
and said grooves in
unidirectional releasable interlocking engagement to prevent said plunger to
move towards said first
position. In this embodiment, said plunger cavity peripheral wall comprises a
first release clearance
registering with said pawl tip when said plunger is in said second position,
such that said pawl tip
io can partially extend into said first release clearance when said plunger is
in said second position so
as return from said first pawl position to a neutral position, to allow said
plunger biasing member to
urge said plunger towards said first position without hindrance from said pawl
when said plunger
reaches said second position.
In one embodiment, said first release clearance is a release notch made
through said
i5 plunger cavity peripheral wall at a position intermediate said set of teeth
and said plunger first end.
In one embodiment, said pawl is pivoted to a second pawl position when said
plunger is moved from
said second position to said first position and is located therebetween, and
when said pawl is in said
second pawl position, said pawl will cooperate with said teeth and grooves in
unidirectional
releasable interlocking engagement to prevent said plunger to move towards
said second position. In
2o this embodiment, said plunger cavity peripheral wall comprises a second
release clearance
registering with said pawl tip when said plunger is in said first position,
such that said pawl tip
partially extends into said second release clearance when said plunger is in
said second position so
as return from said second pawl position to said neutral position, to allow
said plunger to be urged
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towards said second position without hindrance from said pawl when said
plunger is in said first
position.
In one embodiment, said second release clearance is a gap formed beyond said
plunger second end.
s In one embodiment, said plunger comprises a guiding groove made on an outer
surface thereof for engagement by a guide roller carried by the miler main
body.
In one embodiment, said plunger further comprises a hammer blade at said
second
end, said hammer blade being for sweeping the fastener ejection channel of the
miler main body
when said plunger is moved from said first to said second positions.
io DESCRIPTION OF THE DRAWINGS
In the annexed drawings:
Figure 1 is a front perspective view of a hardwood flooring miler according to
the
present invention, sitting above a number of interlocked tongue-and-groove
flooring workpieces
which are in turn laid atop a subfloor;
i5 Figure 2 is a side elevation of the miler of figure 1, the plunger socket
being partly
broken for showing a cross-sectional view of the inside content thereof;
Figures 3-6 are enlarged front cross-sectional views of the plunger socket and
its
inner content, sequentially showing the movement of the plunger between its
extracted and retracted
positions and showing the various configurations of the ratchet mechanism
lodged therein during the
2o movement of the plunger;
Figure 7 is a front perspective view of the plunger slipped around the stem
lodged
within the plunger socket of the miler; and
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Figure 8 is an enlarged view of the area circumscribed within circular line
VIII-VIII
of figure 2.
DETAILED DESCRIPTION OF THE EMBODIMENTS
Figures 1-8 illustrate a miler 10 provided with a ratchet mechanism (concealed
in
s figure 1 but shown in figures 2-6) for preventing the return of a partially
driven plunger. Nailer 10
includes a main body 12 made of moulded cast aluminium for example.
Main body 12 comprises a shoe 13 destined to be horizontal when miler 10
operatively sits on the ground, with shoe 13 defining opposite front and rear
ends 13a, 13b; a
magazine 15 extending upwardly away from the shoe front end 13a in an inclined
fashion; a plunger
i o mechanism 17 extending upwardly away from the shoe front end 13 a and at a
90° angle from
magazine 15; and a handle bar 19 extending away from magazine 15 and being
elbowed so as to
define a handle 14 which is, as shown, preferably parallel to shoe 13.
A planar sole 16 is mounted to the shoe 13 of main body 12, parallel thereto.
During
use of miler 10, sole 16 sits on the upper surface of a flooring workpiece W
which is in turn laid
i5 above a subfloor S. Main body 12 also comprises an ejection cap 18 at the
shoe front end 13a
including an inner plate 18a and an outer plate 18b (best shown in figure 8),
made of a very rigid
material such as tempered steel, superimposed and attached to each other.
Ejection cap 18 is
attached to main body shoe 13, adjacently to sole 16, so as to be arranged
obliquely, for example at
45° with respect to the horizontal direction. A bottom edge portion of
ejection cap 18 protrudes
2o downwardly beyond the undersurface of sole 16; this downward projection
portion will be referred
to as nose 23.
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Inner plate 18a defines a bottom edge near sole 16 and an opposite top edge,
and
comprises a groove extending from its top edge to its bottom edge that forms a
fastener ejection
channel 20 (figure 8). Fastener ejection channel 20 opens outwardly of plate
18 at a fastener ejection
opening 22 situated at the tip of nose 23.
s Main body 12 further defines a magazine chamber 24 in magazine 15 in the
form of
an elongated channel, which is intended to accommodate fasteners F, for
example a strip of collated
L- or T-shaped cleats or U-shaped staples. Magazine chamber 24 communicates
and is aligned with
fastener ejection channel 20 of ejection cap 18. Furthermore, a feeder bar 26
(figures 1-2) is inserted
in magazine chamber 24, and a magazine spring 28 is attached to and tensioned
between feeder bar
i o 26 and miler main body 12. When fasteners F are loaded within magazine
chamber 24, magazine
spring 28 pulls feeder bar 26 into pressing engagement against the last
fastener fed into magazine
chamber 24. This forces the fasteners F to be serially admitted into the
fastener ejection channel 20,
prior to being successively discharged out of miler 10 through fastener
ejection opening 22 at the tip
of nose 23, driven through the subjacent workpiece W and into the underlying
subfloor S.
i5 Plunger mechanism 17 defines an elongated hollow plunger socket 30
extending
frontwardly obliquely of miler 10, in alignment with the front end of magazine
chamber 24 and
perpendicular to magazine 15. Plunger socket 30 comprises a longitudinal
central cavity 32 of
rectangular cross-section, which defines opposite top and bottom walls 33a,
33b and a peripheral
wall 29. Top wall 33a has a rectangular recess 31a within which a smaller
rectangular opening 31 is
2o made, and bottom wall 33b has a rectangular recess 34 that is aligned and
registers with top wall
recess 31a. A stationary cross-sectionally rectangular tubular liner 36 - made
of tempered steel for
example - snugly sits within and extends between top and bottom recesses 31 a
and 34 of plunger
socket 30. A blade opening 35 (figure 8) is made in main body 12, which
extends from the bottom
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wall of recess 34 in longitudinal cavity 32 to magazine chamber 24 in
alignment with fastener
ejection channel 20.
Plunger mechanism 17 comprises an elongated stem member 40, illustrated in
figure
7, which abuts against socket cavity bottom wall 33b, in the recess 34
thereof, so as to be confined
s within tubular liner 36; stem member 40 is coaxial with elongated liner 36.
Stem member 40 can be
made from a very rigid material such as tempered steel. Stem member 40 defines
a foot member 42
bearing upon the bottom wall of recess 34 of socket cavity 32, with foot
member 42 defining an
indentation 43 registering with blade opening 35. A tubular sleeve portion 46
extends upwardly
from foot member 42, and a spring post portion 44 extends upwardly in turn
from sleeve portion 46,
io coaxially therewith. A shoulder 45 is formed at the junction between sleeve
portion 46 and the
relatively narrower spring post portion 44.
Sleeve portion 46 defines an elongated lumen 48 which opens outwardly of stem
40
at a bottom opening 50 traversing foot member 42, lumen 48 opening also at its
opposite end into
two diametrically opposite pawl windows 52 made through the peripheral wall of
tubular sleeve
i5 portion 46, in the vicinity of shoulder 45.
Stem member 40 carries first ratchet means in the form of a spring-loaded pawl
mechanism nested within its tubular sleeve portion 46. More particularly, a
pivot pin 62, friction
fitted at both ends into corresponding holes made in the peripheral wall of
sleeve portion 46,
pivotally carnes a pawl 60 such that the latter is held within sleeve lumen 48
with only a radially
2o projecting pawl tip 61 thereof sticking out of sleeve portion 46 through
one of windows 52. Apart of
pawl tip 61, pawl 60 is substantially cylindrical, although it defines a
flattened rocking surface 60a
that is angularly offset of 90° relative to pawl tip 61.
Biasing means are also provided to bias pawl 60 towards a neutral position (as
detailed herein after); more particularly, a spring member 64 is forcibly
compressed between a ball
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68 nested in lumen 48 adjacent pawl 60 and a pair of set screws 66 threadingly
engaging the bottom
end portion of sleeve lumen 48 - i.e. the end portion of sleeve lumen 48
adjacent bottom opening
50. Spring member 64 continuously biases ball 68 towards and against pawl 60.
Since the pivot pin
62 carrying the pawl 60 is centered within lumen 48, and since the lower
rocking surface 60a of
s pawl 60 that is engaged by ball 68 is only slightly convex, if not
substantially flat, the spring biased
engagement of ball 68 against pawl 60 will result in pawl 60 being
continuously biased towards the
neutral position shown in figures 3 and S, wherein pawl tip 61 extends at a
right angle relative to the
longitudinal axis of lumen 48 and stem member 40. Indeed, in this neutral
position of pawl 60, since
the spring-biased ball 68 engages the pawl rocking surface 60a at a right
angle relative thereto and in
to an aligned fashion relative to the pawl pivot pin 62, pawl 60 is not
subjected to any off centered
moment of force from the spring-biased ball 68. However, if pawl 60 is forced
away from this
neutral position against the spring biased action of ball 68 (figures 4 and
6), then the spring-biased
engagement of ball 68 on the pawl rocking surface 60a will be off centered
relative to the pawl pivot
axis 62, creating a moment of force on pawl 60 that will force pawl 60 towards
its neutral position.
i5 It is noted that the position of set screws 60 can be adjusted along sleeve
lumen 48, in
order to adjust the tension in spring member 64. This allows adjustment of the
biasing force applied
by spring member 64 on ball 68 and thus on pawl 60.
Plunger mechanism 17 further comprises a plunger 70, made of a rigid material
such
as tempered steel, that is also received in the plunger socket 30 of the
miler's main body 12. Plunger
20 70 has a shank portion 74 defining distal and proximal ends 74a and 74b
respectively, and a head
portion 72 integrally connected to the proximal end 74b of shank portion 74.
Head portion 72 has a
discoid impact-receiving top surface 73 destined to receive mallet blows.
Shank portion 74 is hollow
and defines an inner longitudinal central cavity 76, and can for example be of
rectangular cross-
section to fit snugly yet slidably into cross-sectionally rectangular liner
36. Shank portion
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longitudinal cavity 76 is penetrated by stem member 40 that loosely fits
centrally within shank
portion longitudinal cavity 76, and plunger 70 is thus telescopically mounted
on stem member 40. In
the embodiment shown in the drawings, shank portion longitudinal cavity 76 is
of rectangular cross-
section, and defines an inner peripheral wall 81 thus having four
longitudinally extending flat wall
s portions.
A blade groove 78 (figure 7) is made on one 77a of the four outer side walls
77 of
plunger shank portion 74, and a roller groove 79 (figure 2) is made on the
side wall 77b opposite
side wall 77a. Roller groove 79 extends longitudinally along side wall 77b and
defines rounded
distal and proximal ends 79a and 79b that are located short of the plunger
shank portion distal and
io proximal ends 74a, 74b respectively. Roller groove 79 is rollably engaged
by a guide roller 80;
roller 80 is housed in a relatively larger roller cavity 85 made in plunger
socket 30, and is mounted
to a gudgeon 82 fixedly yet releasably carried by and extending across the
miler's plunger socket 30
(see figures 1 and 2) and held in position by a locking pin 83. This rollable
engagement by roller 80
on the plunger's roller groove 79 serves to guide and limit the axial sliding
motion of plunger 70
is relative to liner 36 between limit positions defined herein after, as the
roller groove distal and
proximal ends 79a, 79b will abut against roller 80 in these limit positions.
An elongated replaceable hammer blade 84 (see figures 2 and 8) is releasably
friction
fitted in blade groove 78, so as to be in parallel alignment with plunger
shank portion 74 and so as to
extend well beyond the shank portion distal end 74a. Hammer blade 84 is
positioned so as to have
20 one of its extremities register with and extend through blade opening 35.
Shank portion distal end
74a may of course be equipped with any suitable alternate fastener driving
member that is intended
to extend into blade opening 35. Mounted around the shank portion proximal end
74b is a donut
shock absorber and blade retainer 90, made of rubber for example. Since donut
90 is located
between plunger head portion 72 and plunger socket 30, it prevents plunger
head portion 72 from
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directly striking plunger socket 30 as the plunger head portion 72 is driven
towards the free end of
main body plunger socket 30 under a mallet blow. Also, since donut 90 is
wrapped around the
proximal end 74b of plunger shank portion 74 and the registering end portion
of hammer blade 84, it
retains hammer blade 84 within blade groove 78.
s One flat wall portion 81 a of the inner peripheral wall 81 of shank portion
longitudinal
cavity 76 comprises second ratchet means in the form of a number of teeth 92
formed thereon, with
grooves 93 being formed between pairs of consecutive teeth 92. More
particularly, grooves 93 are
cut away directly into the shank cavity flat wall portion 81 a so that each
groove 93 is substantially
straight and extends along flat wall portion 81 a perpendicularly to the
longitudinal axis of plunger
l0 70. Each tooth 92 being formed between consecutive pairs of grooves 93,
teeth 92 also extend along
flat wall portion 81a perpendicularly to the longitudinal axis of plunger 70.
Within liner 36, teeth
and grooves 92 and 93 are in facing alignment with pawl tip 61, and grooves 93
are engageable by
pawl tip 61 to prevent the return of the partially driven plunger 70, as
detailed hereinafter.
Moreover, a release clearance in the form of a release notch 96 is formed
through the flat wall
15 portion 81 a of peripheral wall 81 of plunger shank portion 74 at a
position intermediate teeth 92 and
shank proximal end 74b.
A plunger biasing member in the form of a compressed coil spring 98 is nested
within
the inner cavity 76 of plunger shank portion 74. Coil spring 98 abuts at one
end on the end of inner
cavity 76 located at shank portion proximal end 74b, and at the opposite end
on stem shoulder 45.
2 o Coil spring 98 is penetrated by stem spring post portion 44 and is for
recoiling plunger head portion
72 away from plunger socket 30, as described hereinafter.
Plunger 70 is movable between two limit positions:
~ a first extracted position (figure 3) where plunger shank portion 74 is
partly extracted from
socket member 30, plunger 70 is telescopically extended away from stem member
40, the inner
CA 02517798 2005-09-O1
wall 81 of shank portion 74 is located spacedly above and completely clears
pawl 60, and guide
roller 80 abuts against the rounded distal end 79a of roller groove 79 to
prevent complete egress
of plunger 70 from plunger socket 30; and
~ a second retracted position (figure S) where plunger shank portion 74 is
fully inserted in socket
s member 30, plunger 70 is telescopically retracted towards stem member 40,
donut 90 abuts
against the upper free end of plunger socket 30, pawl tip 61 extends through
release notch 96
made in plunger shank portion 74, and guide roller 80 abuts against rounded
proximal end 79b
of roller groove 79.
In use, miler 10 - with its plunger 70 in its extracted position - is
positioned
io against the upper surface of a tongue-and-groove flooring workpiece W so
that nose 23 of ejection
cap 18 is placed above the tongue T of the workpiece. The user then forcibly
strikes the impact-
receiving surface 73 of plunger head portion 72 with a mallet M. This urges
plunger 70 into a
downstroke where it progressively retracts into liner 36, against the bias of
coil spring 98, and
concomitantly urges hammer blade 84 to move downwardly and sweep fastener
ejection channel 20,
i5 in order to strike a fastener F positioned therein. The frangible
attachment of fastener F to the
adjacent fastener strip will yield to allow fastener F to be fully driven into
the workpiece W and into
the subfloor S by hammer blade 84 only when plunger 70 has reached its
retracted limit position.
During this downstroke of plunger 70, plunger shank portion 74 retracts into
liner 36
and plunger 70 telescopically retracts around stem member 40 towards stem foot
member 42, and
2o pawl tip 61 serially engages and slides over teeth 92 made on the inner
wall of shank portion 74 and
into the lateral grooves 93 formed therebetween. More particularly, during the
downstroke of
plunger 70 where plunger 70 moves from its extracted towards its retracted
limit position, pawl tip
60 is pivoted downwardly in a downstroke position under the action of the
downwardly moving
distal end 74a of plunger shank portion 74, which engages and abuts against
pawl tip 61. As shown
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in figure 4, pawl 60 will remain inclined in this downstroke position as
plunger shank portion
continues to move downwardly, with pawl tip 61 sequentially abutting against
teeth 92 that prevent
pawl 60 from reaching its neutral position. Indeed, it is recalled that the
spring biased ball 68
continuously forces pawl 60 towards its neutral position, and thus pawl tip 61
will upwardly abut
s against teeth 92. It is noted that grooves 93 and teeth 92 are sized and
disposed in such a manner to
prevent pawl 60 from pivoting freely to its neutral position, i.e. whenever
pawl tip 61 clears a given
tooth 92, the serially subsequent tooth 92 intercepts pawl tip 61 before pawl
60 reaches its neutral
position.
If plunger 70 is only partially driven into plunger socket 30 after a mallet
blow, i.e. it
io has been urged downwardly but not sufficiently so as to have reached its
retracted limit position,
pawl tip 61, which is pivoted in its downstroke position, unidirectionally
lockingly engages one of
the teeth 92 to prevent plunger 70 from recoiling out of plunger socket 30
under the biasing
influence of the compressed coil spring 98. The engagement of pawl 60 on a
tooth 92 thus maintains
plunger 70 in a static intermediate position between its extracted and
retracted limit positions which
i5 prevents another fastener from loading into fastener ejection channel 20
since the latter is at least
partially occupied by hammer blade 84 and by the upper extremity of the partly
discharged fastener
as shown in figure 8. The user can thus pound repeatedly on the plunger with
his mallet to gradually
move it to its retracted limit position, without the plunger recoiling back
under the influence of coil
spring 98 to its extracted limit position between each mallet blow. The user
can thus drive the
2 o fastener into the subjacent workpiece W with a number of mallet blows that
each move plunger 70 a
fraction of the way towards its retracted limit position.
When plunger 70 reaches its retracted limit position, pawl tip 61 clears teeth
92 and
enters the pawl release clearance formed by release notch 96 in plunger shank
portion 74, where the
spring member 64 / ball 68 combination pivots pawl 60 about pivot pin 62 from
its downstroke to its
CA 02517798 2005-09-O1
17
neutral position, as shown in figure 5. Indeed, release notch 96 is sized and
configured to allow free
and unhindering pivotal movement of pawl tip 61 therein.
When pawl 60 is at this neutral position, coil spring 98 is allowed to
decompress in
order to recoil plunger 70 towards its extracted limit position without
hindrance from pawl 60.
Indeed, during the upstroke of plunger 70 where it moves under the bias of
coil spring 98 from its
retracted to its extracted limit position, pawl tip 61 will abut against the
lower edge of release notch
96 and pawl 60 will pivot against the action of spring-biased ball 68 into an
upstroke position (as
illustrated in figure 6). As pawl tip 61 thereafter slides along the inner
wall portion 81 a of plunger
shank 74, it will sequentially engage teeth 92 as shown in figure 6. Since
teeth 92 and grooves 93
i o are sized and configured to force pawl tip 61 to engage another tooth 92
as it clears a previous tooth
92 as stated herein above, pawl 60 will remain upwardly inclined in this
upstroke position and pawl
tip 61 will not hinder the upward movement of plunger shank portion 74.
However, plunger 70
cannot be moved again towards its retracted limit position until it has
reached its extracted limit
position and pawl tip 61 clears the plunger shank portion central cavity 76,
since pawl tip 61 would
i5 then lock against one of teeth 92. This is desirable since plunger 70 must
reach its extracted limit
position for blade 84 to clear fastener ejection channel 20 and for another
fastener F to be admitted
in fastener ejection channel 20.
Once plunger 70 reaches its extracted limit position, pawl tip 61 clears the
plunger
shank central cavity 76 and is free to pivot to its neutral position as shown
in figure 3. It can thus be
a o said that the gap formed beyond plunger shank portion lower end 74b is a
pawl release clearance of
the same nature as release notch 96, i.e. allowing pawl 60 to return from a
pivoted position to its
neutral position under the influence of spring-biased ball 68. Another
fastener can then load into
fastener ejection channel 20, and miler 10 may be used again to drive this new
fastener out of miler
with a single or multiple mallet blows.
CA 02517798 2005-09-O1
18
One important advantage of the present miler is the fact that all the
interacting ratchet
components are contained within plunger mechanism 17, and more particularly
within plunger
cavity 76 and the stem sleeve 46. Plunger 70 and stem sleeve 46 being made
from very rigid
materials, they are not prone to deformation during use of the miler;
consequently, alignment
s between the teeth and grooves made on plunger 70 and pawl 60 carned by stem
40 are likely to
remain properly aligned after repeated use and ageing of the miler.
In prior art milers, some of the ratchet components are carried directly by
the miler's
main body, which is typically made of aluminium - a material that is
relatively soft and likely to
bend and deform after repeated use of the miler. Accordingly, as use of the
miler goes on, its main
io body progressively locally bends and deforms, the pawl and the
teeth/grooves hence eventually
become misaligned, and the ratchet mechanism thus ceases to function properly.
This problem is
obviated in the present invention by providing all elements of the ratchet
mechanism on the plunger
and stem, which are typically made of very sturdy and bend-resistant
materials.
Moreover, the ratchet-provided plunger of the present invention can be
retrofitted on
i5 existing manual milers that do not include any ratchet mechanism. A kit
comprising the hollow
plunger with teeth and grooves made on its inner surface, the stem provided
with a spring-loaded
pawl, the coil spring destined to be compressed between the stem and the
plunger, and the hammer
blade, could be sold as a retrofittable kit for installation on an existing
miler having a plunger socket
of compatible dimensions and configuration. This retrofit installation is
possible since the miler's
2 o main body need not be modified to accommodate any element of the ratchet
mechanism, since the
ratchet mechanism parts operate from within the longitudinal cavity of the
plunger shank portion.
Moreover, the attachment of the ratchet mechanism to miler body 12 is obtained
through the
instrumentality of guide roller 80 that prevents plunger 70 from complete
axial egress out of the
socket member cavity 32 due to the abutment of the plunger roller groove
distal end 79a on guide
CA 02517798 2005-09-O1
19
roller 80. Stem member 40 is maintained in position simply under the bias of
coil spring 98, that is
compressed between the stem member 45 and plunger head 72, stem member 40 thus
being
continuously biased towards and resting against the socket cavity bottom wall
recess 33b.
To install a ratchet-provided plunger mechanism according to the present
invention
on an existing miler, locking pin 83 (see figures 1 and 3-6) retaining roller
gudgeon 82 on plunger
socket 30 is removed, and roller gudgeon 82 is in turn removed from plunger
socket 30. This causes
roller 80 to be freely released inside the relatively larger roller cavity 85,
and causes it to be allowed
to clear the roller guiding groove made on the side of a plunger previously
installed inside plunger
socket 30. This allows removal of any previously installed plunger mechanism
out of plunger socket
io 30 and this plunger mechanism removal procedure is known in the art. The
ratchet-provided
plunger / stem / coil spring kit of the present invention can then be inserted
in plunger socket 30,
within liner 36. This insertion is accomplished by simply sliding the plunger
and stem assembly into
socket 30, with stem foot 92 coming to bear against the bottom wall 34 of
plunger socket cavity 32.
Plunger 70 is then partly moved towards its retracted position until roller
groove 79 registers with
i5 roller 80. Plunger 70 is then maintained in this position, while gudgeon 82
is reinserted across
plunger socket 30 and through guiding roller 80, and locking pin 83 is
reinserted through the pierced
outer free end of gudgeon 82 protruding outwardly of plunger socket 30. This
allows the removal of
prior art non-ratchet-provided mechanisms from milers, to replace them with a
ratchet-provided
plunger mechanism including a plunger 70 and a stem member 40, without any
further modification
2o to the miler body 12.
It is understood that the above-described embodiment of the present invention
is
exemplary, and that modifications could be made thereto without departing from
the scope of the
appended claims. For example:
CA 02517798 2005-09-O1
the position of cooperating first and second ratchet means could be inverted.
For example, in an
alternate embodiment, the pawl could be carried by the plunger and the teeth
and grooves could
be made on the stem; what matters is that the first and second ratchet means
be capable of
unidirectional releasable interlocking engagement;
5 ~ the spring member and ball assembly biasing the pawl in a given pivotal
direction could be
replaced with any suitable resilient biasing member;
~ coil spring 98 could be replaced by any alternate biasing member. It is
noted that coil spring 98
could rest against miler main body 12 instead of against stem member 40, as
long as it acts on
plunger 70; and
to ~ liner 36, plunger socket 30 and plunger shank portion 74 could be have
any suitable cross-
sectional shape, such as a round cross-sectional shape.
