Note: Descriptions are shown in the official language in which they were submitted.
CA 02511722 1997-06-12
CURVED SCRIEWSTRIP
This application is a divisional of Canadian Patent Application Serial No.
2,207,647, filed June 12, 1997.
Scope of the Invention
This invention relates generally to a screwdriver for driving collated screws
which are joined together in a strip, and, more particularly, to a power
screwdriver
with a nose portion which renders the screwdriver adaptable for use in driving
screws
having different lengths and diameter screw heads.
Background of the Invention
Collated screwstrips are lrnown in which the screws are connected to each
other by a retaining strip of plastic material. Such strips are taught, for
example, by
U.S. Patent 4,167,229 issued September il, 1979 and its related Canadian
Patents
1,040,600 and 1,054,982 as well as U.S. Patent 4,930,630. Screws carried in
such
screwstrips are adapted to be successively incrementally advanced to a
position= in
alignment with and to be engaged by a bit of a reciprocating, rotating power
screwdriver and screwed into a workpiece. In the course of the bit engaging
the screws
and driving it into a workpiece, the screw becomes detached from the plastic
strip
leaving ihe strip as a continuous length.
In the use of such collated screwstrips in screwdrivers, the strip serves
a fimction of assisting in guiding the screw into a workpiece and, to
accomplish this,
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the strip is retained against movement towards the workpiece. In the
screwstrip, each
screw to be driven has its threaded shaft threadably engaged in a threaded
sleeve of the
strip such that on the screwdriver engaging and rotating each successive
screw, the
screw turns within the sleeve which acts to guide the screw as it moves
forwardly into
threaded engagement into the workpiece. Preferably, only after the tip of the
screw
becomes engaged in the workpiece, does the head of the screw come into contact
with
the sleeves. Further, forward movement of the screw into the workpiece then
draws the
head downwardly to engage the sleeve and to rupture the sleeve by reason of
the
forward movement of the head with the strip retained against movement towards
the
workpiece. The sleeve preferably is configured to have fragile strips which
break on
the head passing through the sleeve such that the strip remains intact as a
continuous
length. Since the strip is a continuous length, on advancing the screwstrip
with each
successive screw to be driven, it necessarily results that portion of the
strip from which
each screw has been driven are also advanced to exit from the power
screwdriver.
Known power screwdrivers for driving such collated screwstrips include
U. S. Patent 4,146,871 to Mueller et al, issued March 27, 1976, and U.S.
Patent
5,186,085 to Monaceli, issued February 16, 1993. Such known power screwdrivers
include a rotatable and reciprocally moving screwdriver shaft which is turned
in
rotation by an electric motor. A screwdriving bit forms a forwardmost portion
of the
shaft for engaging the head of each successive screw as each screw is moved
into a
driving position, axially aligned under the screwdriver shaft.
An important aspect of such power screwdriver is the manner and
accuracy with which the screws are advanced and positioned so as to be
properly
aligned axially under the screwdriver shaft for successful initial and
continued
engagement between the bit and the screwdriver head in driving a screw fully
down
into a workpiece. In the device of Mueller et al, a guide channel is provided
through
which the screwstrip is advanced. The guide channel is sized to receive screws
of
specific head size and minimum length. The guide channel is formed as an
integral
part of a sliding body which also carries other components of a screw advance
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mechanism including a feed pawl to engage the screwstrip and thereby advance
successive screws in the screwstrip. The screws are successively advanced into
position in alignment with the screwdriver shaft with the heads of the screws
being
urged into abutment with a stop which is to locate the screw head. The stop
typically
defines a radial extent of a boreway through which the shaft and screw head
axially
move as the screw is driven.
The shaft is axially movable in the boreway in a reciprocal manner to
engage the screw and drive it into a workpiece. After each screw is driven the
shaft
retracts and a subsequent screw carried on the screwstrip is advanced sideways
into
the boreway, engaging the stop so as to be aligned under the shaft.
A disadvantage with screwdrivers such as taught by Mueller et al and
others is that the screwdrivers are not adapted to drive different sized
screwstrips or
screws. Known screw drivers have a guide channel which is sized to receive
only
screws of certain dimensions. Similarly, the screw advance mechanism is
adapted
only to advance screws by contacting screws and/or the strips at certain
places
determined by the size of the screws and configuration of the screwstrips. As
well,
the screw advance mechanism is adapted only to advance the screwstrip a
certain
maximum stroke determined by one pre-selected spacing of the screws on the
strip.
Any stop provided to locate screw heads if adjustable, is typically only
adjustable to
accommodate screws of slightly varying head sizes. The construction of most
known
screwdrivers and particularly of their screw guide channels, screw advance
mechanisms and screw locating stops has the disadvantage of not permitting one
screwdriver to practically be adjusted to drive screwstrips and/or screws of
different
sizes. Another disadvantage is that most screwdrivers cannot drive the last
screw in
a strip. Most screwdrivers suffer the disadvantage of requiring a number of
moving
parts to locate each screw to be driven.
Summary of the Invention
To at least partially overcome these disadvantages of the prior art, the
present invention provides in one aspect a screwdriver for driving screws, in
which
a removable nose portion is provided to be removable from the screwdriver for
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replacement by other nose portions. The nose portion carries a guide channel
through
which screws are advanced, a locating guide which holds each successive screw
in
axial alignment with the drive shaft to drive the screw and/or a screw advance
mechanism to incrementally advance the screws in the guide channel into the
locating
guide.
An object of the present invention is to provide a screwdriver for
driving screws having different lengths and/or screw head diameters, wherein
the
screwdriver may be quickly and inexpensively customized for optimal placement
and
driving of various screws having other lengths and/or screw head diameters.
A further object, is to provide a power screwdriver adapted for driving
different screwstrip having different sizes of threaded fasteners collated
together in
a parallel spaced orientation on a retaining strip.
This invention provides in one aspect a driver attachment for a collated
screwstrip in which a slide body is slidable in a housing parallel a
longitudinal axis
about which drive shaft is rotatable. The slide body has a rear portion and a
removable nose portion. The housing and rear portion of the slide body form an
integral part effectively permanently assembled and including a screw feed
activation
mechanism coupled between the housing and rear portion and which translates
relative
sliding movement and positioning of the rear portion of the slide body
relative the
housing. The nose portion is removable from the rear portion for ease of
replacement
with other nose portions adapted for use with the same or different sized
screwstrips
and/or screws. The nose portion includes a channel to guide a collated
screwstrip
generally transversely to the longitudinal axis of the drive shaft. The nose
portion
includes a guide mechanism to locate each successive screw advanced through
the
channel into axial alignment with the drive shaft for engagement therewith.
The nose
portion also includes a screw feed advance mechanism to advance the screwstrip
through the channel when activated by the screw feed activation mechanism. The
screw feed advance mechanism readily uncouples from and couples with the screw
feed activation mechanism on uncoupling and coupling of the nose portion with
the
rear portion.
Accordingly, in one aspect, the present invention provides an apparatus
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for driving with a power driver a screwstrip comprising threaded fasteners
such as
screws or the like, which are joined together in a strip comprising:
housing means;
elongate drive shaft means for operative connection to a power driver
for rotation thereby about a longitudinal axis;
slide body means coupled to the housing means for displacement
parallel to the axis of the drive shaft means between an extended position and
a
retracted position;
spring means biasing said body means forwardly relative to the housing
means parallel the longitudinally axis to the extended position;
the slide body means having a rear portion and a forward nose portion,
the nose portion removably coupled to the rear portion;
the nose portion having:
(a) guide channel means for said screwstrip extending through said
nose portion,
(b) guide means to locate successive of the screws advanced via the
guide channel means to be axially in alignment with said drive shaft means for
engagement in driving of the screws from the guide means by the drive shaft
means,
and
(c) screw feed advance means carried by the nose portion to engage
the screwstrip and successively, incrementally advance screws on the
screwstrip
through the guide channel means,
screw feed activation means coupled between the rear portion of the
slide body means and the housing means and, when the nose portion is coupled
to the
rear portion, removably coupling with the screw feed advance means whereby
displacement of the slide body means relative the housing means between the
extended position and the retracted position activates the screw feed
activation means
to move the screw feed advance means and thereby advance successive screws;
wherein the nose portion removably couples to and is removable from
the rear portion for replacement with other nose portions adapted to receive
the same
or different sized screwstrips and/or screws; and
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wherein on the nose portion coupling to or being removed from
coupling with the rear portion, the screw feed advance means correspondingly
removably coupling to or being removed from coupling with the screw feed
activation
means.
Another object of the present invention is to provide a power
screwdriver adapted to drive the last screw in a screwstrip.
Another object is to provide a power screwdriver adapted for use with
short segments of screw strips, permitting quick insertion and changing of the
screwstrips.
Another object is to provide an improved configuration for a screwstrip
which assists the strip in being self-supporting as for use as a short
segment.
Another object is to provide a canister to carry a coil of screwstrips
which is mounted to the slide body.
This invention provides in a second aspect a driver attachment for a
collated screwstrip in which a slide body is slidable in a housing parallel a
longitudinal axis about which drive shaft is rotatable. The slide body has a
nose
portion. A screw feed activation mechanism coupled between the housing and the
slide body translates relative sliding movement and positioning of the slide
body
relative the housing. The nose portion includes a channel to guide a collated
screwstrip generally transversely to the longitudinal axis of the drive shaft.
The nose
portion includes a guide mechanism to locate each successive screw advanced
through
the channel into axial alignment with the drive shaft for engagement
therewith. A
strip carrying screws is advanced into the guideway via an entranceway and the
spent
strip from which the screws have been driven exits from the guideway via an
exitway
which encircles the spent strip. A slotway is provided on one side of the
guideway
extending between the entranceway and exitway and sized to receive the strip
which
is deflected laterally into the slotway on the head of the screw being driven
in the
guideway past the strip.
This invention provides in the second aspect a screwdriver assembly
to drive screws collated together in a strip spaced in parallel relation from
each other,
the screwdriver comprising:
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a cylindrical guideway to receive a screw coaxially therein,
a screw-and-strip entranceway opening generally radially into the
guideway on a first side thereof,
a strip exitway opening generally radially out of the guideway on a
second side thereof opposite the entranceway,
the guideway, the entranceway and the exitway juxtapositioned to
permit screws collated in a strip spaced in parallel relation from each other
to be
successively advanced through the entranceway radially into the guideway to
locate
each successive screw coaxially within the guideway with portions of the strip
from
which screws have been driven extending from the guideway via the exitway,
elongate, rotatable driver shaft means having at a forward end bit
means, the shaft means reciprocally movable axially in the guideway to engage
the
screw with the bit means and drive the screw axially forwardly from the
guideway
into a workpiece,
the exitway having an axially, rearwardly directed strip supporting
surface axially forward of the strip for engagement by the strip to support
the strip
against movement forwardly on the shaft means driving a screw axially
forwardly;
the exitway encircling the strip with the exitway having an axially
forwardly directed surface axially rearward of the strip and side surfaces on
either
side of the strip extending between the rearwardly directed surface and the
forwardly
directed surface,
the guideway having an inner diameter marginally greater than a
diameter of a head of a screw to be driven therein and a screw locating
sidewall about
portions of the guideway to engage the head of a screw and coaxially locate
the screw
in the guideway,
a lateral strip receiving slotway cut from sidewall on one side thereof
extending normal the axis of the guideway from the entranceway to the exitway
opening at each of its ends as part of the entranceway and exitway,
the slotway sized to receive the strip therein radially to one side of the
guideway when the head of the screw being driven passes through the guideway
past
the strip.
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Another object of the present invention is to provide a screwscrip with a
curved beam holding the screws.
The invention provides in one aspect, a screwscrip comprising a beam
member having a first surface and a second surface, the first surface
including a
plurality of holding members capable of securing fasteners having a head and a
tip in
side-by-side relation, with each head extending beyond a first side of said
first surface
and each tip extending beyond a second side of said first surface, the beam
member
having a curved shape such that a plurality of fasteners secured in said beam
member
have heads provided about a first radius, and said plurality of fasteners have
tips
provided about a second radius greater than said first radius. Preferably, the
beam is
formed of plastic. Preferably, the beam defines a substantially constant
radius,
preferably between 12 inches and 36 inches. Preferably, a longitudinal axes of
each of
the plurality of fasteners lie in substantially a single preferably flat
plane.
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Brief Description of the Drawings
Further aspects and advantages of the present invention will appear
from the following description taken together with the accompanying drawings,
in
which:
Figure 1 is a pictorial view of a power screwdriver in accordance with
a first preferred embodiment of the present invention;
Figure 2 is an exploded pictorial view of the housing and slide body
shown in Figure 1;
Figure 3 is a pictorial view of the opposite side of the slide body to
that shown in Figure 2 but with a screwstrip positioned therein;
Figure 4 is a schematic partially cross-sectional view of the driver
attachment of Figure 1 in a fully extended position as seen in Figure 1
through a
plane passing through the longitudinal axis of the drive shaft and centrally
of the
screws in the screwstrip;
Figure 5 is a view identical to Figure 4 but with the drive attachment
in a partially retracted position in driving a screw into a workpiece;
Figure 6 is an end view of the nose portion of Figure 2;
Figure 7 is a pictorial view of the nose portion shown in Figure 2 but
modified in accordance with a second embodiment of the invention to provide a
retractable screw locating plate;
Figure 8 is a cross-sectional view through section VIII-VIII' in Figure
7;
Figure 9 is a pictorial view of an optional clutch drive shaft in
accordance with another aspect of the invention;
Figure 10 is a cross-sectional view of the drive shaft of Figure 9
passing through the longitudinal axis in Figure 9 and with the drive shaft in
a
disengaged position;
Figure 11 is a view identical to that of Figure 10 but with the drive
shaft in an engaged position;
Figure 12 is a schematic pictorial view of a second version of a
removable nose portion;
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Figure 13 is a partially cut-away pictorial view of the nose portion of
Figure 12 from a different perspective;
Figures 14, 15, 16 and 17 are similar views of the nose portion of
Figure 12 shown with the last screw in a strip in successive positions as it
is driven
from the nose portion;
Figure 18 is a cross-sectional side view of the nose portion of Figure
14 along vertical section 18-18';
Figure 19 is a vertical cross-section of the nose portion of Figure 14
along vertical cross-section 19-19';
Figure 20 is a horizontal cross-section along section line 20-20' of
Figure 19;
Figure 21 is a vertical cross-section of the nose portion of Figure 17
along vertical section line 21-21';
Figure 22 is a horizontal cross-section along section line 22-22' in
Figure 21.
Figure 23 is a schematic pictorial view similar to Figure 13 but of a
third version of a removable nose portion;
Figure 24 is a pictorial view of a power screwdriver similar to that in
Figure 1 but driving a screwstrip of fixed length having a curved
configuration;
Figure 25 is an exploded pictorial front view similar to Figure 2 but
of a second embodiment of driver attachment in accordance with this invention;
Figure 26 is a rear view of the components of the driver attachment of
Figure 25 assembled; and
Figures 27 and 28 are pictorial views from opposite angles of a driver
assembly utilizing the driver attachment of Figure 25.
Detailed Description of the Drawings
Reference is made to Figure 1 which shows a complete power
screwdriver assembly 10 in accordance with the present invention. The assembly
10
comprises a power driver 11 to which a driver attachment 12 is secured. The
driver
attachment 12 carries a cartridge 9 containing a coil of a collated screwstrip
14 with
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spaced screws 16 to be successively driven.
Reference is made to Figure 2 showing an exploded view of major
components of the driver attachment 12 as housing 18 and a slide body
comprising
a rear portion 22 and a removable nose portion 24. Figures 4 and 5 show in
cross-
section the interaction of these components.
As seen in Figure 4, the rearmost end 26 of the housing 18 has a
rearwardly directed socket 27 with a longitudinal slot 28 in its sidewall to
receive and
securely clamp the housing 18 onto the housing 30 of the power driver 11 so as
to
secure the housing 18 of the driver attachment to the housing 30 of the power
driver
against relative movement. The power driver 11 has a chuck 32 rotatable in the
driver housing 30 by an electric motor (not shown). The chuck 32 releasably
engages
the driver shaft 34 in known manner. The housing 18 is provided with a lateral
flange 36 at its rear end to which a known screwstrip containing cartridge 9
is
secured in a conventional manner.
As seen in Figure 4, the slide body 20 is slidably received in the
housing 18 with the driver shaft 34 received in a bore passing through the
rear
portion 22 and nose portion 24 of the slide body 20. A compression spring 38
disposed between the housing 18 and the rear portion 22 coaxially about the
driver
shaft 34 biases the slide body away from the housing 18 from a retracted
position
towards an extended position. As shown, the spring 38 is disposed between the
housing 18 and the rear portion 22. Slide stops 25, best shown in Figure 2,
are
secured to the rear portion 22 of the slide body. Two slide stops 25 slide in
two
longitudinal slots 40 on each side of the part cylindrical sidewall 42 of the
housing
18 to key the rear portion 22 of the slide body to the housing 18 against
relative
rotation and to prevent the slide body being moved out of the housing 18 past
a fully
extended position.
The rear portion 22 comprises a generally cylindrical element 44 with
a radially extending flange element 46 on one side. A lever 48 is pivotally
mounted
to the flange element 46 by bolt 50 for pivoting about an axis 51 of bolt 50
normal
to a longitudinal axis 52 which passes centrally through the drive shaft 34
and about
which the drive shaft is rotatable. Lever 48 has a forward arm 54 extending
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forwardly to its front end 56 and a rear arm 58 extending rearwardly to its
rear end
60. A cam follower 62 has its forward end 63 mounted to the rear end 60 of the
rear
arm 58 by a bolt 64 being received in a slot 65 extending longitudinally in
the rear
end of the rear arm 58. The cam follower 62 has at its rear end 66 two cam
rollers
67 and 68 rotatable on pins parallel to the axis of bolts 50 and 64.
As seen in Figures 2 and 4, the housing 18 carries a camming channel
70 in which the cam rollers 67 and 68 are received. The camming channel 70 is
disposed to one side of the driver shaft 34 and extends generally parallel
thereto. The
camming channel 70 has opposed camming surfaces 71 and 72 at least partially
closed
by sidewalls 73 and 74.
The camming channel 70 extends rearwardly beside the socket 27 of
housing 18 and thus rearwardly past the chuck 32 of the power driver 11 to one
side
thereof. This configuration permits the use of a housing 18 which is of a
lesser
length parallel longitudinal axis 52 for a given length of the cam follower 62
and of
the lever 48, rearward of bolt 50.
A spring 69 wound about bolt 50 is disposed between the flange
element 46 and the forward arm 54 of the lever 48 to bias the lever in a
clockwise
direction as seen in Figure 4. The effect of spring 69 is to urge the cam
roller 67
into engagement with cam surface 71 and to urge cam roller 68 into engagement
with
cam surface 72.
With relative sliding of the slide body 20 and the housing 18 between
the extended and the retracted positions, the cam follower 62 translates the
relative
movement and positioning of the slide body 20 and housing 18 into relative
pivoting
and positioning of the lever 48 about the axis 51. The ability of bolt 64 to
slide
longitudinally in the longitudinal slot 65 provides a lost motion linkage as
is known
and is advantageous such that the relative timing of pivoting of the lever 48
varies as
compared to the relative location of the slide body 20 and housing 18 in
moving
towards an extended position as contrasted with moving towards a retracted
position.
The nose portion 24 has a generally cylindrical screw guide element
or guide tube 75 arranged generally coaxially about longitudinal axis 52 and a
flange-
like screw feed channel element 76 extending radially from the guide tube 75.
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The guide tube 75 has a cylindrical portion 77 at its rear end with a
cylindrical exterior surface sized to be closely received, preferably in a
friction fit,
within a forwardly opening cylindrical bore 78 in the forward end of the rear
portion
22. A radially extending key 80 is provided to extend from the cylindrical
portion
77 of the nose portion 24 to be received in a correspondingly sized keyway
slot 82
in the rear portion 22 as best seen in Figure 4 and 7 to secure the nose
portion 24 to
the rear portion 22 against relative pivoting about the longitudinal axis 52.
The guide tube 75 has a cylindrical bore or guideway 82 extending
axially through the guide tube with the guideway 82 delineated and bordered by
a
radially extending cylindrical sidewall 83 and open at its forward axial end
84 and at
its rearward axial end 85.
The guide tube 75 has a rearward section adjacent its rear end 85 in
which the sidewall 83 extends 360 about the guideway 82. Forward of the
rearward
section, the guide tube has a forward section best seen in Figure 4 and which
has an
access opening 86, shown in the drawings as being on the right hand side of
the guide
tube 75. Screw access opening 86 is provided to permit the screwstrip 14
including
retaining strip 13 and screws 16 to move radially inwardly into the guideway
82 from
the right as seen in Figure 4 and 5. Each screw preferably has a head 17 with
a
diameter marginally smaller than the diameter of the sidewall 83. It follows
that
where the head of the screw is to enter the guideway 82, the screw access
opening
must have circumferential extent of at least 180 . Where the shank 208 of the
screw
is to enter the guideway, the screw access opening may have a lesser
circumferential
extent.
In the forward section, the sidewall 83 of the guide tube 75 engages
the radially outermost periphery of the head 17 of the screw 16, to axially
locate the
screw head 17 coaxially within the guideway 82 in axial alignment with the
drive
shaft 34. In this regard, the sidewall 83 preferably extends about the screw
sufficiently to coaxially locate the screw head and thus preferably extend
about the
screw head at least 120 , more preferably, at least 150 and most preferably
about
1800.
An exit opening 87, shown towards the left hand side of the guide tube
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75 in Figures 4 and 5, is provided of a size to permit the spent plastic strip
13 from
which the screws 16 have been driven to exit from the guideway 82. Forwardly
of
the exit opening 87, the sidewall 83 of the guide tube 75 is shown as
extending
greater than about 180 about the longitudinal axis 52 so as to continue to
provide a
sidewall 83 which can assist and positively coaxially guiding the head 17 of a
screw
16 being driven.
The screw feed channel element 76 is best seen in Figures 3 and 4 as
providing a channelway 88 which extends radially relative the longitudinal
axis 52 to
intersect with the guideway 82 in the guide tube 75. In this regard, the
channelway
88 opens to the guideway 82 as the screw access opening 86. The channelway 88
provides a channel of a cross-section similar to that of the screw access
opening 86
from the screw access opening 86 to a remote entranceway opening 90. The
channelway 88 is defined between two sidewalls 91 and 92 joined by a top wall
93.
The major sidewall 91 is shown as extending from the heads 17 of the screws 16
forwardly to at least partially behind the plastic retaining strip 13. The
lesser
sidewall 92 is shown as extending from the heads 17 of the screws 16 forwardly
to
above the plastic strip 13. Stopping the lesser sidewall from extending down
over the
strip 13 assists in reducing friction between the strip 13 and the lesser
sidewall. The
sidewalls 91 and 92 define the channelway 88 with a cross-section conforming
closely
to that of the screwstrip 14 and its strip 13 and screws 16 with an enlarged
width
where the heads of the screws are located and an enlarged width where the
retaining
strip 13 is provided about the screws. The sidewalls 91 and 92 also have an
enlarged
funnelling section at the entranceway opening 90 which tapers inwardly to
assist in
guiding the screwstrip to enter the channelway.
As best seen in Figure 3, the major sidewall 91 is provided on its
exterior back surface with a raceway 94 extending parallel the channelway 88
and in
which a shuttle 96 is captured to be slidable towards and away from the guide
tube
75 between an advanced position near the guide tube and a withdrawn position
remote
from the guide tube. The shuttle 96 has a rear surface 97 in which there is
provided
a rearwardly directed opening 98 adapted to receive the front end 56 of the
forward
arm 54 of lever 48 so as to couple the shuttle 96 to the lever 48 for movement
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therewith.
Shuttle 96 carries a pawl 99 to engage the screwstrip 14 and with
movement of the shuttle 96 to successively advance the strip one screw at a
time. As
seen in Figure 6, the shuttle 96 has a fixed post 100 on which the pawl 99 is
journalled about an axis parallel the longitudinal axis 52 about which the
driver shaft
34 rotates. The paw199 has a strip pusher arm 101 which extends through a slot
103
in the major sidewall 91 to engage and advance the screwstrip. The pawl 99 has
a
manual release arm 102 away from pusher arm 101 and which extends out through
a slot 104 in the shuttle 96. A torsional spring is disposed about post 100
between
pawl 99 and shuttle 96 and urges the pusher arm 101 clockwise as seen in
Figure 6.
The spring biases the pusher arm 101 into the screwstrip 14. The engagement of
release arm 102 on the right hand end of slot 104 limits the pivoting of the
paw199
clockwise to the position shown in Figure 6.
The pusher arm 101 of the paw199 has a cam face 107. On the shuttle
moving away from the guide tube 75 towards the withdrawn position, i.e., to
the left
in Figure 6, the cam face 107 will engage the screws 16 and/or the strip 13
and
permit the pusher arm 101 to pivot about post 100 against the bias of spring
so that
the pusher arm 101 may move with the shuttle to the left.
The pusher arm 101 has an engagement face 108 to engage the screws
16 and/or strip 13. On the shuttle moving towards the guide tube 75 towards
the
advanced position, i.e., to the right in Figure 6, the engagement face 108
will engage
the screws 16 and/or strip 13 and advance the screwstrip to the right as seen
in
Figure 6 so as to position a screw 16 into the guideway 82 in a position to be
driven
and to hold the screwstrip 14 against movement towards the left. Preferably,
as
shown in Figure 4, the engagement face 108 of the pusher arm engages the screw
between its head 17 and the strip 13 as this has been found advantageous,
particularly
to avoid misfeeding with a nose portion 24 as shown with engagement of the
screw
heads in the channelway 88 and engagement of the spent strip 13' with the
support
surface 125.
The release arm 102 permits manual withdrawal of the screwstrip 14.
A user may with his finger or thumb manually pivot the release arm 102 against
the
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bias of spring so that the pusher arm 101 and its engagement face 108 is moved
away
from and clear of the screwstrip 14 whereby the screwstrip may manually be
withdrawn as may be useful to clear jams or change screwstrips.
With the nose portion 24 coupled to the rear portion 22, the lever 48
couples to the shuttle 96 with the forward arm 54 of lever 48 received in the
opening
98 of the shuttle 96. Sliding of the slide body 20 and the housing 18 in a
cycle from
an extended position to a retracted position and then back to an extended
position
results in reciprocal pivoting of the lever 48 about axis 51 which slides the
shuttle 96
between the advanced and withdrawn position in its raceway 94 and hence
results in
the paw199 first retracting from engagement with a first screw to be driven to
behind
the next screw 16 and then advancing this next screw into a position to be
driven.
The nose portion 24 is removable from the rear portion 22. The nose
portion 24 and rear portion 22 may be coupled together by axially inserting
the
cylindrical portion 77 of the guide tube 75 into the bore 78 in the rear
portion 22 with
the key 80 aligned with the keyway slot 82 and with the front end 56 of the
forward
arm 54 of the lever 48 aligned with the opening 98 in the shuttle 96. Thus,
the
removable nose portion 24 may be coupled to the rear portion 22 merely by
axially
aligning the nose portion and the rear portion and moving the two elements
together
in a direction parallel the longitudinal axis 52.
With the nose portion 24 held on the rear portion 22 by a friction fit,
the nose portion 24 can manually be removed by a user merely by the manual
application of force. The nose portion 24 is removable from the rear portion
22
without disassembly or uncoupling of any of the remainder of the screwdriver
assembly 10. Thus, the nose portion 24 is removable without uncoupling of the
rear
portion 22 relative any of the housing 18, spring 38, power driver 11, driver
shaft
34 or the screw feed activation mechanism comprising amongst other things the
lever
48 and cam follower 62 and without uncoupling of the cam follower 62 in
camming
channel 70 of the housing 18.
The nose portion 24 carries the guide tube 75 with its screw locating
guideway 82, the screw feed channel element 76 with its channelway 88, and
screw
feed advance mechanism with the reciprocating shuttle 96 and pawl 99 to
advance the
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screwstrip 14 via the channelway 88 into the guideway 82. Each of the guideway
82,
channelway 88 and shuttle 96 are preferably customized for screwstrips and
screws
or other fasteners of a corresponding size. In this context, size includes
shape, head
diameter, shaft diameter, retaining strip configuration, length, spacing of
screws
along the retaining strip and the presence or absence of washes amongst other
things.
Different nose portions 24 are to be configured for different screwstrips and
screws.
The different nose portions 24 are each compatible with the same rear portion
22 and
are readily exchangeable so as to permit the driver attachment to be readily
adapted
to drive different screwstrips and screws.
Many changes can be made to the physical arrangement of the nose
portion 24 to accommodate different screws and fasteners. For example, the
cross-
sectional shape of the channelway 88 can be changed as can the diameter of the
guideway 82. The length of the sidewalls 91 and 92 about the channelway 88 can
be varied to accommodate different size screws which may require greater or
lesser
engagement.
To adjust for different spacing between screws in different screwstrips,
the stroke of the shuttle 96 in reciprocating back and forth can be shortened
or
lengthened by varying the distance from the axis 51 of the lever 48 to where
the
shuttle 96 engages the forward arm 54 of the lever 48. For example, placing
the
same shuttle 96 in a raceway 94 spaced further from the axis 51 will increase
the
length of the stroke of the shuttle 96 for the same arc of pivoting of lever
48.
Similarly, using the same shuttle 96 in the same raceway 94 but having the
opening
98 in the shuttle 96 to engage the lever 48 farther from the axis 51 will also
increase
the length of the stroke of the shuttle 96 for the same arc of pivoting of
lever 48.
In contrast with the removable nose portion 24 which is intended to be
provided in many different replaceable configurations, the remainder of the
driver
attachment is preferably of a constant unchanged configuration. In this
regard, the
remainder of the driver attachment may be characterized by the housing 18,
rear
portion 22 of the slide body 20, drive shaft 34 and spring 38 together with a
screw
feed activation mechanism comprising the lever 48 cam follower 62 interacting
between the rear portion 22 and the housing 18. This screw feed activation
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mechanism is activated by relative movement of the housing 18 and rear portion
22
and serves to engage and move the screw feed advance mechanism comprising the
shuttle 96 and pawl 99 carried on the nose portion 24.
The construction of the housing 18 and slide body 20 provide for a
compact driver attachment.
The housing 18 has a part cylindrical portion formed by sidewall 301.
The slide body 20 as best seen in Figure 3 comprising the rear portion
22 and nose portion 24, has a part cylindrical portion of a uniform radius
sized to be
marginally smaller than the sidewall 301 of the housing 18. The sidewall 301
extends
circumferentially about the part cylindrical portion of the slide body 20 to
retain the
slide body 20 therein.
The housing has a flange portion 302 which extends radially from one
side of the part cylindrical portion and is adapted to house the radially
extending
flange 46 of the rear portion 22 and the screw feed activation mechanism
comprising
the camming channel 70 interacting with the lever 48 and cam follower 62. The
flange portion 302 is open at its front end and side to permit the screw feed
channel
element 76 to slide into and out of the housing 18. Concentrically located
about the
drive shaft 34 is the spring 38, the part cylindrical portions of the slide
body 20, and
the part cylindrical portions of the housing 18.
The driver attachment is provided with an adjustable depth stop
mechanism which can be used to adjust the fully retracted position, that is,
the extent
to which the slide body 20 may slide into the housing 18. The adjustable depth
stop
mechanism is best seen in Figures 2 and 3 as comprising an elongate rod 110
slidably
received in an elongate open ended bore 111 provided in the sidewall 42 of the
housing 18 and extending parallel to longitudinal axis 52.
A depth setting cam member 114 is secured to the housing 18 for
rotation about a pin 116 parallel the longitudinal axis 52. The cam member 114
has
a cam surface 115 which varies in depth, parallel the longitudinal axis 52,
circumferentially about the cam member 114. A portion of the cam surface 115
is
always axially in line with the rod I 10. A spring 113 biases the rod 110
rearwardly
such that the rear end 117 of the rod engages the cam surface 115. The spring
112
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is disposed between the housing and a pin 113 on the rod. By rotation of the
cam
member 114, the extent to which the rod 110 may slide rearwardly is adjusted.
The rod 110 has a front end 118 which extends forwardly from bore
111 for engagement with rearwardly directed annular stop surface 119 provided
on
the nose portion 24 of the slide body. The slide body 20 is prevented from
further
sliding into the housing 18 when the front end 118 of the rod 110 engages the
stop
surface 119. The extent the slide body 20 may slide into the housing 18 is
determined by the length of the rod 110 and the depth of the cam member 114
axially
in line with the rod. The cam member 114 is preferably provided with a ratchet-
like
arrangement to have the cam member 114 remain at any selected position biassed
against movement from the selected position and with circular indents or
depressions
in the cam surface 115 to assist in positive engagement by the rear end 117 of
the
rod. The cam member 114 is accessible by a user yet is provided to be out the
way
and not interfere with use of the driver attachment. The depth stop mechanism
controls the extent to which screws are driven into a workpiece and thus
controls the
extent of countersinking. As the depth stop mechanism controls the distance
from the
workpiece the bit 122 must stop, a given countersink setting will be effective
even if
strips are switched to use screws of a different length. Adjustment is not
required
merely because different length screws are to be used.
The nose portion 24 may be customized for use in respect of different
size screws by having the location of the stop surface 119 suitably provided
axially
on the nose portion 24 as may be advantageous for use of different size
screws.
The driver shaft 34 is shown in Figures 4 and 5 as carrying a split
washer 120 engaged in an annular groove near its rear end 121 to assist in
retaining
the rear end of the driver shaft in the socket 27 of the housing 18. The
driver shaft
34 is provided with a removable bit 122 at its forward end which bit can
readily be
removed for replacement by another bit as for different size screws. Such bits
include sockets and the like in any replacement bits will preferably be of an
outside
diameter complementary to the inside diameter of the guideway 82 in a
corresponding
replacement nose portion adapted for use with a corresponding sized screws. To
accommodate bits of increased diameter over the bit shown in Figures 4 and 5,
the
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guideway 82 of the guide tube 75 may be provided with an increased radius, at
least
commencing at the location where the bit may have an enlarged diameter and
extending forwardly therefrom. The guideway 82 in the guide tubes 75 may thus
have a step configuration with the sidewall 83 being of a reduced diameter
where the
driver shaft 34 enters the rear of the guide tube 75 and the sidewall 83 may
then
increase to an enlarged diameter forwardly to accommodate an enlarged bit such
as
a socket.
The rear portion 22 is shown in Figures 4 and 5 as having a radially
inwardly extending annular flange 19 which provides the end of the forwardly
opening bore 78 as well as the end of a rearwardly opening bore 79 within
which the
spring 38 is received. The annular flange 19 has an opening therethrough of a
diameter slightly larger than the diameter of the driver shaft 34 so as to
assist in
journalling the driver shaft therein. The opening through the annular flange
19 may
however be increased so as to facilitate the use of driver shafts 34 having
enlarged
diameters as well as a driver shafts 34 having reduced diameters.
Insofar as the driver shaft 34 has a removable bit 122, it is preferred
that as shown, when the driver attachment 12 is in the fully extended position
and the
nose portion 24 is removed, the bit 122 be readily accessible for removal and
replacement. In this regard, it is preferred that the nose portion 124 have a
guideway
82 of a minimum diameter throughout its length at least equal to the diameter
of the
bit 122 such that the nose portion 24 may be removed from the rear portion 22
without the need to remove the bit 122 as may otherwise be the case in the
event the
guideway 82 may have a stepped configuration.
Operation of the driver attachment is now explained with particular
reference to Figures 4 and 5. As seen in Figure 4, the screws 16 to be driven
are
collated to be held parallel and spaced from each other by the plastic
retaining strip
13.
In operation, a screwstrip 14 containing a number of screws 16 collated
in the plastic retaining strip 13 is inserted into the channelway 88 with the
first screw
to be driven received within the guideway 82. To drive the first screw into
the
workpiece 124, the power driver 11 is activated to rotate the driver shaft 34.
The
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driver shaft 34 and its bit 122, while they are rotated, are reciprocally
movable in the
guideway 82 towards and away from the workpiece 124. In a driving stroke,
manual
pressure of the user pushes the housing 18 towards the workpiece 124. With
initial
manual pressure, the forward end 25 of the nose portion engages the workpiece
124
to compress spring 38 so as to move slide body 20 relative the housing 18 into
the
housing 18 from an extended position shown in Figure 4 to a retracted
position. On
release of this manual pressure, in a return stroke, the compressed spring 38
moves
the slide body 20 back to the extended position thereby moving the housing 18
and
the driver shaft 34 away from the workpiece.
In a driving stroke, as the driver shaft 34 is axially moved towards the
workpiece, the bit 122 engages the screw head 17 to rotate the first screw to
be
driven. As is known, the plastic strip 13 is formed to release the screw 16 as
the
screw 16 advances forwardly rotated by the driver shaft 34. Preferably, the
screw
tip will engage in a workpiece before the head of the screw engages the strip
such
that engagement of the screw in the workpiece will assist in drawing the screw
head
through the strip to break the fragible straps, however, this is not necessary
and a
screw may merely, by pressure from the drive shaft, be released before the
screw
engages the workpiece. Preferably, on release of the screw 16, the plastic
strip 13
deflects away from the screw 16 outwardly so as to not interfere with the
screw 16
in its movement into the workplace. After the screw 16 is driven into the
workpiece
124, the driver shaft 34 axially moves away from the workpiece under the force
of
the spring 38 and a successive screw 16 is moved via the screw feed advance
mechanism from the channeiway 88 through the access opening 86 into the
guideway
82 and into the axial alignment in the guideway with the driver shaft 34.
The screw 16 to be driven is held in position in axial alignment with
the driver shaft 34 with its screw head 17 abutting the sidewall 83 in the
guideway
82. As a screw 16 to be driven is moved into the cylindrical guideway 82, a
leading
portion of the strip 13' from which screws have previously been driven extends
outwardly from the guideway 83 through the exit opening 87 permitting
substantially
unhindered advance of the screwstrip 14.
To assist in location of a screw to be driven within the guide tube 75,
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in the preferred embodiment the exit opening 87 is provided with a rearwardly
facing
locating surfaced 125 adapted to engage and support a forward surface 222 of
the
strip 13. Thus, on the bit 122 engaging the head of the screw and urging the
screw
forwardly, the screw may be axially located within the guide tube 75 by reason
not
only of the head of the screw engaging the sidewall 83 of the guideway but
also with
the forward surface 222 of the strip 13 engaging the locating surface 125 of
the exit
opening 87. In this regard, it is advantageous that the forward surface 222 of
the
retaining strip 13 be accurately formed having regard to the relative location
of the
screws 16 and particularly the location of the their heads 17. The forward
surface
222 of the strip 13 may be complementary formed to the locating surface 125
and if
desired indexing notches or the like may be provided in the forward surface
222 of
the strip 13 to engage with complementary notches or indents on the locating
surface
125 of the entranceway to assist in indexing location of the strip 13 relative
the
locating surface and enhance the location thereby of the screw 16 within the
guide
tube 75.
Reference is now made to Figures 7 and 8 which show an alternate
embodiment of a removable nose portion which provides another mechanism to
locate
each successively advanced screw axially aligned with the driver shaft 34. The
alternate embodiment includes a retractable foot plate similar to that taught
in U.S.
Patent 4,146,871 to Mueller et al. The foot plate 128 is provided to engage
and fix
the position of a screw adjacent the screw which is to be driven. As seen, the
modified nose portion is provided with a slot 129 which extends rearwardly
parallel
longitudinal axis 52. The foot plate 128 has a general L-shape with a slide
portion
130 axially slidably received within the slot 129 to slide therein in a
direction parallel
longitudinal axis 52. A spring 131 biases the foot plate 128 out of the slot
129 and
while not shown, a suitable stop mechanism is provided to limit the foot plate
128 to
extend from the slot 129 to a maximum distance.
The foot plate 128 has a foot portion 132 which extends normal to the
longitudinal axis 52 and provides in a rearwardly facing surface 133 a conical
recess
134. This recess 134 is located to be axially in line with the tip 15 of a
"next" screw
16 in the screwstrip 14 adjacent the screw 16 to be driven.
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CA 02511722 1997-06-12
In use of a driver attachment with a modified nose portion 24 as shown
in Figures 7 and 8, the foot plate 128 is the first element of the attachment
to engage
the workpiece. On engaging the workpiece, the foot plate 128 slides rearwardly
into
the slit 129 and thus retracts into the nose portion 24. The foot portion 132
in
moving rearwardly engages the tip 15 of the "next" screw 16 next to the screw
16 to
be driven and accurately locates the tip 15 within the conical recess 134. The
foot
portion 132 applies a force to such next screw pushing the screw rearwardly so
that
the head 17 of the screw bears on the flat top wall 93 in the channelway 88.
By
reason of such next screw being firmly clamped between the foot plate 128 and
the
top wall 93 of the channelway, the screwstrip 14 is effectively locked into
position
and thereby assists in positioning the screw 16 which is to be driven axially
aligned
with the longitudinal axis 52. It is to be appreciated that different
removable nose
portions 24 may be provided with different foot plates 128 having appropriate
relative
location of the foot portion 132 and its conical recess having regard to the
length of
the screw and to the spacing between the screws along the retaining strip 13.
In
known manner, the foot plate 128 may be provided to be adjustably located on
the
nose portion 24.
Figures 7 and 8 show an embodiment of the nose portion 24 utilizing
in combination three different mechanisms whereby a screw to be driven
advanced
through the screw guide channel mechanism is to be located axially in
alignment with
the driver shaft 34. The three mechanisms are the engagement of the screw head
with the sidewall 83, the engagement of the spent strip 13' on the locating
surface
125 of the exit opening 87, and the clamping of the next to be driven screw by
the
foot plate 128. Only one or more of these mechanisms need be provided
particularly
insofar as the channelway 88 may be precisely configured for specific sized
screws
16 and screwstrips 14 and provide by itself generally increased support and
location
of the screwstrip 14 without restricting free sliding of the screwstrip and
its screws
therethrough. With an improved correspondence in sizing between the screwstrip
14
and the channelway 88 and the radial extent of the channelway effectively
locating the
screwstrip and its screws in a plane intersecting the longitudinal axis 52, a
simple
guide mechanism may be provided focussing principally on constraining the
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CA 02511722 1997-06-12
screwstrip 14 or its screw against movement radially relative the channelway
88.
In the embodiment of the nose portion 24 shown in Figures I to 6, on
the bit 122 engaging the head 17 of the screw 16 and urging it forwardly in
the
guideway 82, the strip 13 is preferably held against movement forwardly
firstly by
the forward surface 222 of the strip engaging locating surface 125 and,
secondly, by
the under surfaces of the heads 17 of screws in the channelway 88 engaging on
the
rearwardly directed shoulders provided on each of the sidewalls 91 and 92
where the
enlarged width cross-section of the channelway 88 accommodating the head of
the
screws reduces in width as seen in Figure 3. Together with the location of the
head
17 of a screw 16 coaxially in the guideway, the screw 16 to be driven is
located
axially aligned with the driver shaft without any moving parts other than the
advance
shuttle 96.
The driver attachment 12 disclosed may be provided for different
applications. In a preferred application, the driver may be used for high
volume
heavy load demands as, for example, as in building houses to apply sub-
flooring and
drywall. For such a configuration, it is preferred that with the power driver
11
comprising a typical screw gun which inherently incorporates a friction clutch
and
thus to be extent that a screw is fully driven into a workpiece, the clutch
will, on the
forces require to drive the screw becoming excessive, slip such that the bit
will not
be forced to rotate an engagement with the screw head and thus increase the
life of
the bit.
The driver attachment in accordance with the present invention is,
however, adaptable for use with conventional power drills which are similar to
screw
guns yet do not incorporate a clutch mechanism. The driver attachment may be
suitably used with a drill without a clutch preferably with the user
manipulating the
drill and driver attachment in use to reduce the likelihood of bit wear by the
bit
rotating relative the screw head in a jamming situation. Figures 9, 10 and 11
show
an optional form of a driver shaft 34 which provides a simple clutch
arrangement as
for use with a power drill which does not have a clutch.
Referring to Figures 9 to 11, the modified driver shaft 34 has a rear
body 136 whose rear end is to be secured in the chuck 32 of a power drill in a
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CA 02511722 1997-06-12
normal manner. The driver shaft 34 has a front slide 137 which is axially
slidable
relative the rear body 136.
The front slide 137 includes a cylindrical rod 138 of reduced diameter
which extends forwardly into a forwardly opening cylindrical bore 140 in the
rear
body. The bore 140 in the rear body has at its forward end a radially inwardly
extending shoulder 141. A split ring 142 carried on the rod 138 is received in
an
annular groove 143 about the rod 138. The split ring 142 is provided such that
the
split ring may be compressed into the groove 143 to permit the rod 138 to be
inserted
into the bore 140. Once inside the bore 140, the split ring 142 expands
outwardly
and will engage with the shoulder 141 so as to retain the rod 138 in the bore
140
against removal. A spring 144 is provided within the bore 140 and biases the
front
slide 137 forwardly away from the rear body 136.
The rear body 136 and front slide 137 have opposed clutch surfaces
147 and 148 which when urged together cause the rear body and front slide to
rotate
in unison. However, when the clutch surfaces are disengaged, the rear body 136
may
rotate without rotation of the front slide 137. As shown in the drawings, the
clutch
surfaces comprise complementary teeth and slots on the opposed axially
directed end
surfaces of the rear body 136 and the front slide 137. For example, a tooth
145 on
rear body 136 is adapted to be received within a slot 146 on front slide 137.
While
axially directed clutch surfaces with teeth may be provided, there are a wide
variety
of known clutch surfaces which may provide tooth and/or frictional surfaces
engagement to transfer rotational forces from the rear body 136 to the front
slide 137
when the clutch surfaces are urged axially into each other. Other preferred
surfaces
include conical surfaces.
In use of a driver attachment with the clutch driver shaft 34 shown in
Figures 9 to 11, when a screw with initially engaged by the bit of the driver
shaft and
a person using the screwdriver assembly pushes down on the screw, the downward
pressure applied by the user compresses the spring 144 and the rear surfaces
148 of
the front slide 137 engage the front surfaces 149 of the rear body 136 in the
manner
that they are coupled together for rotation. The coupled position is shown in
cross
section in Figure 11. In this collapsed and engaged position, a screw 16 may
be
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CA 02511722 1997-06-12
driven. On the screw being driven down into a workpiece, the depth stop
mechanism
including for example the rod 110 may be utilized to stop the rear body 136
from
moving further towards the workpiece. The rear body 136 stops from further
movement towards the workpiece at a position that the screw is almost fully
driven
into the workpiece. At this point, with further rotation of the driver shaft
34, as the
screw is driven by the rotation of the driver shaft 34 further downward into
the
workpiece, the screw is drawn away from the rear body 136. Spring 144 to some
extent assists in ensuring that the bit remains engaged in the head of the
screw. Once
the screw head is further advanced into the workpiece an axial distance
greater than
the axial height of the teeth 145 then the teeth 145 will become disengaged
from the
slots 146 and the rear body 136 will rotate driven by the power drill freely
relative
to the front slide 137. It is to be appreciated that by suitably selecting the
depth at
which the housing 18 and therefore the rear body 136 is stopped relative the
workpiece, the front slide 137 can be permitted to disengage from rotation
with the
rear body 136 at a position that the screw becomes screwed into the workpiece
a
desired extent.
The preferred embodiment illustrated in Figure 1 shows a screwdriver
assembly as including a known cartridge 9 which has a hinge door 150
permitting the
insertion of a coil of the screwstrip 14 containing, for example, up to 1000
screws.
It is to be appreciated that the use of such a cartridge is not necessary. For
example,
rather than provide such a cartridge, lengths of the screwstrip could be
provided for
example, one or two feet long which could merely be manually fed into the
channelway 88 when desired.
The driver attachment may be constructed from different materials of
construction having regard to characteristics of wear and the intended use of
the
attachment. Preferably, a number of the parts may be molded from nylon or
other
suitably strong light weight materials. Parts which are subjected to excessive
wear
as by engagement with the head of the screw may be formed from metal or
alternatively metal inserts may be provided within an injection molded plastic
or
nylon parts. The provision of a removable nose portions 24 also has the
advantage
of permitting removable nose portion to be provided with surfaces which would
bear
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CA 02511722 1997-06-12
the greatest loading and wear and which nose portions may be easily replaced
when
worn.
The screw feed advance mechanism carried on the nose portion has
been illustrated merely as comprising a reciprocally slidable shuttle carrying
a pawl.
Various other screw feed advance mechanisms may be provided such as those
which
may use rotary motion to incrementally advance the screws. Similarly, the
screws
feed activation mechanism comprising the lever 48 and the cam follower have
been
shown as one preferred mechanism for activating the screw feed advance
mechanism
yet provide for simple uncoupling as between the shuttle 96 and the lever 48.
Other
screw feed activation means may be provided having different configurations of
cam
followers with or without levers or the like.
In the preferred embodiment, the screwstrip 14 is illustrated as having
screws extending normal to the longitudinal extension of the strip 13 and in
this
context, the channelway 88 is disposed normal to the longitudinal axis 52. It
is to be
appreciated that screws and other fasteners may be collated on a screwstrip in
parallel
spaced relation however at an angle to the longitudinal axis of the retaining
strip in
which case the channelway 88 would be suitably angled relative the
longitudinal axis
so as to locate and dispose each successive screw parallel to the longitudinal
axis 52
of the driver shaft.
A preferred collated screwstrip 14 for use in accordance with the
present invention is as illustrated in the drawings and particularly Figure 3
and are
substantially in accordance with Canadian Patent 1,054,982. The screwstrip 14
comprises a retaining strip 13 and a plurality of screws 16. The retaining
strip 13
comprises an elongate thin band formed of a plurality of identical sleeves
interconnected by lands 106. A screw 16 is received within each sleeve. Each
screws 16 has a head 17, a shank 208 carrying external threads 214 and a tip
15. As
shown, the external threads extend from below the head 17 to the tip 15.
Each screw is substantially symmetrical about a central longitudinal
axis 212. The head 17 has in its top surface a recess 213 for engagement by
the
screwdriver bit.
Each screw is received with its threaded shank 208 engaged within a
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CA 02511722 1997-06-12
sleeve. In forming the sleeves about the screw, as in the manner for example
described in Canadian Patent 1,040,600, the exterior surfaces of the sleeves
come to
be formed with complementary threaded portions which engage the external
thread
214 of the screw 16. Each sleeve has a reduced portion between the lands 206
on
one first side of the strip 13. This reduced strength portion is shown where
the strip
extends about each screw merely as a thin strap-like portion or strap 220.
The strip 13 holds the screw 16 in parallel spaced relation a uniform
distance apart. The strip 13 has a forward surface 222 and a rear surface 223.
The
lands 106 extend both between adjacent screws 16, that is, horizontally as
seen in
Figure 3, and axially of the screws 16, that is, in the direction of the
longitudinal
axes 212 of the screws. Thus, the lands comprise webs of plastic material
provided
over an area extending between sleeves holding the screws and between the
forward
surface 222 and the rear surface 223. A land 206 effectively is disposed about
a
plane which is parallel to a plane in which the axes 212 of all the screws
lies. Thus,
the lands 206 comprise a web which is disposed substantially vertically
compared to
the vertically oriented screws as shown in the figures. The lands 206 and the
sleeves,
in effect, are disposed as continuous, vertically disposed strip 13 along the
rear of the
screws 16, that is, as a strip 13 which is substantially disposed about a
plane which
is parallel to a plane containing the axes of all screws.
A preferred feature of the screwstrip 14 is that it may bend to assume
a coil-like configuration due to flexibility of the lands 206, such that, for
example,
the screwstrip could be disposed with the heads of the screws disposed into a
helical
coil, that is, the plane in which all the axes 212 of the screws lie may
assume a
coiled, helical configuration to closely pack the screws for use. Having the
lands 206
and sleeves as a vertically extending web lying in the plane parallel that in
which the
axes 212 permits such coiling.
The invention is not limited to use of the collated screwstrips
illustrated. Many other forms of screwstrips may be used such as those
illustrated
in U.S. Patents 3,910,324 to Nasiatka; 5,083,483 to Takaji; 4,019,631 to
Lejdegard
et al and 4,018,254 to Delcaro.
Reference is now made to Figures 12 to 22 illustrating a second
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CA 02511722 1997-06-12
embodiment of a removable nose portion 24 which is adapted for substitution
with the
nose portion 24 illustrated in Figures 1 to 6. Throughout Figures 12 to 22,
similar
reference numbers are used to refer to similar elements in Figures 1 to 11.
For
simplicity, the nose portion 24 shown in Figures 12 to 22 is shown merely in
the
context of the nose portion and/or with a screwstrip 14 including retaining
strip 13
and screws 16. Other elements such as the shuttle 96, the shuttle pawl 99, the
lever
48, the drive shaft 24, the bit 122 and the workpiece 124 are not shown for
the
purposes of simplicity. However, operation and interaction of various parts is
substantially the same.
The nose portion 24 of Figures 12 to 21 is identical to the nose portion
24 of Figures 1 to 6 other than in the configuration of a passageway for the
screwstrip radially through the guide tube 75 from the screw access opening 86
to the
exit opening 87.
In Figures 1 to 6, the guide tube 75 has an outboard side which is
completely cut away between the screw access opening 86 and the exit opening
87.
In Figures 12 to 22, the guide tube 75 is not completely cut away on its
outboard side
but rather has a continuous portion 382 of its outer wall which separates the
screw
access opening 86 from the exit opening 87 on the outboard side of the guide
tube 75.
As used herein, the outboard side is the side to which the strip 13 is
deflected when
a screw 16 is separated from the screwstrip 14.
To accommodate deflection of the strip 13 away from a screw 16
towards the outboard side, the passageway which extends from the screw access
opening or entranceway 86 to the exit opening or exitway 87 is provided on its
outboard side with a lateral strip receiving slotway 304 cut to extend to the
outboard
side from the cylindrical guideway 82. The slotway 304, as best seen in
Figures 18,
19 and 20, is bounded on the outboard side by side surface 306, at its forward
end
by ramped surface 308 and forward surface 125, and at its rear end by rear
surface
312. Figure 20 shows the sidewall 83 of the guideway 82 and with the side
surface
306 of the slotway 304 spaced towards the ouboard side by the width of the
ramped
surface 308.
The access opening 86 forms an entranceway for the screwstrip 14
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generally radially into the guideway 82 on one side. The exit opening 87 forms
an
exitway for portions of the strip 13 from which screws 16 have been driven,
such
portions being referred to as the spent strip 13'.
The exit openings or exitway 87 is shown as adapted to encircle the
spent strip 13' with the exitway 87 bordered by rearwardly directed forward
surface
125, forwardly directed rear surface 312, inboard side surface 314 and
outboard side
surface 316.
As seen in Figures 12 and 13, ramped surface 308 is an axially
rearwardly directed surface which angles forwardly from the forward suface 125
towards the entranceway. As seen in Figure 19, the ramped surface 308 also
angles
forwardly with increasing distance from the axis of the guideway 82.
The ramped surface 308 extends forwardly from forward surface 125
at juncture 218, with the ramped surface following the curvature of the
sidewall 83
as a ledge of constant width forming a curved sidewall portion 320 merging
tangentially into side surface 306.
Figures 18, 19 and 20 illustrate the nose protion 24 with a screw 16
coaxially disposed within guideway 82 ready to be driven by the screwdriver
bit.
Figure 18 is a cross-section through the screw feed channel element 76 and
shows
head 17 of the screw as positioned when the screw 16 has extended from the
channelway 88, through the entranceway 86 and into the guideway 82. Figure 18
also shows clearly how, in respect of screws in the channelway 88, the under
surfaces
of the head 17 are to be engaged on rearwardly directed shoulders 198. Figure
19
is a cross-section through the axis of the guideway 82 and shows the guideway
82
having an inner diameter marginally greater than the diameter of the head 17
of the
screw 16 to be driven therein and with the sidewall 83 about portions of the
guideway
82 adapted to engage the head 17 of the screw 16 and assist in coaxially
locating the
screw 16 in the guideway. As seen in Figures 18 and 19, the forward surface
222
of strip 13 engages the forward surface 125 of the exitway 87.
Figures 14, 15, 16 and 17 illustrate successive positions the screwstrip
14 assumes in driving the last screw 16 from the strip 13. Figure 14 shows the
position the last screw assumes when advanced into the guideway 82 by the
shuttle
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96 (not shown). The screw 16 of Figure 14 is subsequently engaged by the bit
122
of the driver shaft 34 (not shown) to be rotated and pushed forwardly, whereby
the
screw 16 rotates within the strip 13 toward assuming the position shown in
Figure 15
with the head 17 of the screw 16 near to engaging the strip 13. With continued
downward movement of the screw from the position of Figure 15, the underside
of
the head 17 exerts downward pressure on the strip 13, with the strip 13 to
pivot about
the radially inner edge of the forward surface 125 such that the strip 13
comes to
have its terminal end 322 drawn downwardly with the strip to assume the angled
orientation as shown in Figure 16.
The extent to which the strip may pivot about the radially inner edge
of the forward surface 125 may be limited by the engagement of the rear
surface 223
of the strip with the rear surface 312 of the exitway 87. The ramped surface
308
preferably is selected to angle forwardly from the forward surface 125 such
that the
ramped surface 308 is below, preferably only marginally below, the forward
surface
222 of the strip 13 and disposed at substantially the same angle as the
forward surface
222 of the strip 13.
In Figure 16, the screw head 17 urges the strip 13 downwardly into the
angled configuration shown with the straps 220 continuing to extend about the
shaft
of the screw but becoming tensioned and/or stretched. With further driving of
the
screw 16 forwardly, with the strip 13 being retained in the angled position
against
further forward movement, the forward movement of the head 17 breaks the
straps
220 and the head 17 pushes the strip 13 laterally to the outboard side in the
head 17
passing forwardly in the guideway 82 past the strip 13. As seen in Figure 21,
the
strip 13 is located outboard of the guideway 82 and screw 16 in the slotway
with head
17 of the screw free to pass forwardly therepast in the guideway.
Figure 22 is a top cross-sectional view of Figure 21. Figure 22 shows
the strip 13 as deflected to the outboard side into the slotway. Figure 22
also shows
the strip 13 as having its terminal end 322 located towards the outboard side
compared to the leading end 324 of the spent strip 13'. The spent strip 13'
can adopt
various positions where it exits the exitway 87. The entire strip 13' can
assume a
more outboard position as with the strip's outboard surfaces assuming the
position of
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CA 02511722 1997-06-12
the dotted line 326 in Figure 22. The entire strip 13' can assume a position
in which
its leading end 324 extends more inboard, as with the strip's outboard
surfaces,
assuming the position of the dotted line 328 in Figure 22, with the spent
strip 13' to
extend diagonally through the exitway 87.
With the inner edge 330 of forward surface 125 curving rearwardly as
seen in Figure 22, engagement between the inner edge 330 and the forward
surface
222 of the strip tends to pivot the strip to move its terminal end 322 to the
outboard
side which is advantageous to assist in urging the strip 13 into the slotway.
As best seen in Figure 21, the ramped surface 308 angles forwardly
with increased radius from the axis of the guideway. This assists in
engagement
between the ramped surface 308 and the forward surface 222 of the strip
tending to
urge the strip 13, or at least the strip's forward surface 222, sideways
towards the
outboard side and away from the screw 16 as is advantageous to reduce the
likelihood
of jamming of the strip under the head 17 of the screw as between the head 17
and
the sidewall 83.
Figure 23 shows a third embodiment of a nose portion 24 identical to
the nose portion of Figure 13 but in which the forward surface 125 towards the
outboard side angles forwardly as an angled surface portion 332 initially at
an angle
similar to that of ramped surface 308, then merging into a surface portion 334
forward of surface 125.
On the strip 13 being drawn downwardly into the angled configuration
as shown in Figure 16, the angled surface portion 332 and the more forward
surface
portion 334 assist in urging the strip 13 towards the outboard side and into
the
slotway. The rear surface 312 of the exitway 87 could also be configured such
that
when the strip 13 is angled upwardly, the engagement between the rear surface
232
of the strip 13 and the rear surface 312 may urge the strip 13 towards the
outboard
side. Figure 22 shows in dotted lines as 313 an alternate location of rear
surface 312
which angles rearwardly toward the outboard side.
In Figures 14 to 22, the screwstrip 14 has been shown in a preferred
form for screwstrips which are to comprise discrete length segments. The
strip, as
seen in Figures 12 and 20, has lands 106 of relatively constant cross-section
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throughout the length of the strip, with an enlarged flange 107 extending
along the
outboard side of the strip. This structure and particularly the enlarged
flange 107
assists in malcing the strip self-supporting, that is, so that a segment will
support the
weight of the screws against bending. Flange 107 extends in the axial
direction of
the screw at least half the height of the lands. The strip 13 has been shown
with a
terminal end 322 which typically would extend from the last screw, about one
half
the distance between screws.
The strip 13 typically would be of a length of at least six inches and
may be very long in the case of a coiled screwstrip. The leading end 324 is
shown
at a location where the strip 13 has ceased to be drawn in the drawings.
The nose portion 24 is shown as removable for use in an assembly as
illustrated. It is to be appreciated that the particular features of the
exitway,
entranceway and guideway specifically disclosed to assist in driving the last
screw in
a strip could be used in other guide tubes such as those which are not
removable and
which may or may not have an associated channelway.
The driver attachment 12 in accordance with this invention and the
nose portion 24 described herein are particularly adapted for driving
screwstrips 14
in the form of short segments, preferably in the range of about six to
eighteen inches
in length. One preferred length is about twelve inches so as to hold, for
example,
about 32 screws of, for example, drywall screws or wood screws. To provide
each
segment with sufficient rigidity to be self-supporting, it is preferred to
provide the
strip 13 to have increased dimensions normal the axis of the screw on the
outboard
side of the screws as, for example, with the lands 206 extending as a
continuous web
along the outboard side of the screws as seen in Figure 20. Reinforcing rib or
flange
107 may be provided along the entire length of the lands 206 as seen in
Figures 19
and 20. Such a reinforcing flange 107 or rib is of assistance in maintaining
the axis
of the screws in the same plane against coiling. The enlarged slotway in the
nose
portion of Figure 12 is readily adapted to accommodate strips with such lands
206
and ribs 336 of increased width.
When, as shown in Figure 14, the last screw 16 in a strip is located in
the guideway, the fact that the exitway 86 encloses the spent strip 13'
prevents the
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CA 02511722 1997-06-12
strip from rotating about the axis of the guideway to an orientation in which
the screw
16 might be able to drop out of the guideway or the screw when driven is
increasingly likely to jam. The spent strip 13' may extend from the exitway 87
at
various angles limited only by the location of the side surfaces 314 and 316.
Surface
314 extends radially away from the guideway and towards the inboard side.
The configuration of Figures 12 to 23 is advantageous to better ensure
that the last screw 16 in any screwstrip 14 is driven and to generally assist
in
reducing the likelihood of any screw 16 being driven becoming jammed in the
guideway with the strip 13.
Preferred strip segments for use with the drive attachment in
accordance with this invention are as shown in Figure 12, segments of discrete
length
in which the axis of all strips lie in the same flat plane and in which the
heads 17 of
the screws are all located in a straight line.
Figure 24 schematically shows a driver assembly similar to that in
Figure 1 but adapted to drive a screwstrip of a segment 340 of discrete
length, but
which is curved in the sense that the heads (and tips) of the screws lie in a
curved
line at a constant radius from a point 338. Preferably, all of the axis of the
screws
lie in the same plane. Each screw 16 preferably extends radially from point
338.
The advantage of the curved discrete segment 340 is that the tips of screws 16
which
are yet to be driven are spaced further rearward from a workpiece than tips of
screws
which are all in the same straight line. Having the tips of screws 16 spaced
from the
workpiece can be of assistance in preventing the tips of screws not yet driven
from
marking the surface of a workpiece.
A preferred radius of curvature may be in the range of twelve to thirty-
six inches. Depending upon the curvature of the segment 340, the screw feed
channel
element 76 and its channelway 88 may be adapted to correspondingly adopt a
similar
radius of curvature or have sufficient space to accommodate both straight and
curved
strips.
Reference is now made to Figures 25 to 28 showing a modified form
of a canister 400 to contain a coil of a collated screwstrip 14 and a system
to mount
the canister 400 to the driver attachment. In Figures 25 to 28, the same
reference
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CA 02511722 1997-06-12
numbers are used to refer to the same elements as in the other figures.
Figure 25 illustrates an exploded view of the housing 18 and slide body
components similar to the view shown in Figure 2. The individual elements of
the
two embodiments are very similar. Figure 25 shows the use of a nose portion 24
with an enclosed exit opening 86 and with the guide tube having the axially
extending
continuous portion 302 outboard of the passageway to receive the strip. The
support
surface 125 is shown to be normal the axis of the guideway.
Reference is made in Figures 25 and 26 to the slide stops 25 which are
secured to the rear portion 22 of the slide body by bolts 402 such that the
slide stops
25 slide in longitudinal slots 40 on each side of housing 18 to key the rear
portion to
the slide body and to prevent the slide body being moved out of the housing
past a
fully extended position.
Each slide stop 25 carries a coupling shoe generally indicated 404 by
which a canister 400 may be mounted to the the driver attachment. The canister
400
is shown in Figures 27 and 28 to include a bracket 406 with two spaced
parallel arms
408 and 410. Each arm 408 and 410 is adapted to be secured to a coupling shoe
404
on the slide stops 25. In particular, the arms 408 and 410 have slots (not
shown) in
their inner surfaces complementary to the shape and profile of the coupling
shoe.
These slots have an open forward end and a closed rear end complementary in
profile
to the curved rear end 412 of the coupling shoe 404. A bolt 414 extends
through
each of arms 408 and 410 into a nut 416 in each shoe 404 to secure each arm to
its
respective shoe 404. Each shoe 404 has a longitudinal rib 418 spaced from the
surface of the housing 18 and a keyway in the slots of the arms 408 and 410 is
adapted to receive this rib 418 to positively provide against spreading of the
arms
apart independently of the bolts 414. A bolt 415 is provided to secure the
rear
portion 22 to the nose portion 24 with bolt 415 screwing through the shoe 404,
and
the rear portion 22 into the cylindrical portion 77 on the nose portion 24.
The bracket 406 carrying the canister 400 can readily be removed from
the slide stops 25, for example, by removing bolts 414 and sliding the arms
axially
rearward relative the shoes 404.
The bracket 406 has a screw carrying tray 420 coupled to it. A
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CA 02511722 1997-06-12
mounting flange 422 on the bracket 406 carries a slide key 424 engaged
slidably in
a keyway 426 on the tray 420. By tightening or loosening bolt 428, the tray
420 can
be located at desired positions forwardly and rearwardly relative the
longitudinal axis
of the guideway. The tray is preferably positioned such that coiled screws
sitting
with their tips on the bottom surface 430 of the tray have their heads 17
disposed at
the same plane as heads of screws received in the channelway 88 of the screw
feed
channel element 76. The tray has a rearwardly extending sidewall 431 directing
screws to exit via an exit port 432 directly in line to the channelway 88.
The nose portion 24 and the canister 400 are both coupled to the rear
portion 22 and thus move together as parts of the slide body 20. The tray and
screwstrip are always in a constant aligned position relative the nose portion
24 in all
positions in sliding of the slide body 20 relative the housing 18. This is in
contrast
with the cartridge 9 in Figure 1 which is mounted to the housing 18 and the
screwstrip 14 must flex with each cycle of in and out sliding of the housing
18
relative the slide body 20.
Figure 26 shows an advantageous configuration for the shuttle 96 in
being provided with a fixed post 432 opposed to the manual release arm 102 to
permit
pivoting of the release arm 102 by drawing the release arm 102 towards the
fixed post
432 by pinching them between a user's thumb and index finger.
Mounting of the canister 400 to the slide stops 25 permits the slide
body 18 to be fully retractable within the housing without the screwstrip
being flexed
in each reciprocal stroke.
As seen in Figure 26, a stop member 40 is mounted to housing 18 to
engage a stop flange 442 on the slide stop 25 and provide increased surfaces
to bear
stopping load forces. A longitudinal rib 444 extends along the side of housing
18 and
a complementary slotway is provided in each stop flange 442 closely sized
thereto to
assist in longitudinal parallel sliding and engagement.
Referring to Figure 18 and 26, the guide tube 75 has a forward surface
446 which is a segment of a spherical surface of a radius centered on the axis
of the
guideway such that screws being driven may be driven into a workpiece a
relatively
constant distance even if the guideway is disposed at a slight angle to the
normal
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CA 02511722 1997-06-12
relative the workpiece.
The preferred slotway illustrated in Figures 12 to 22 shows the slotway
bounded forwardly by the ramped surface 308 which slopes relative the axis of
the
guideway both forwardly towards the entranceway and with increased radial
distance
from the axis of the guideway. It is to be appreciated that the slotway may be
bounded forwardly by surfaces normal the axis of the guideway as, for example,
an
extension of support surface 125 and such a configuration is shown in Figure
25.
While the invention has been described with reference to preferred
embodiment, the invention is not so limited. Many variations and modifications
will
now occur to persons skilled in the art. For a definition of the invention,
reference
is made to the appended claims.
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