U.S. patent number 3,920,169 [Application Number 05/499,642] was granted by the patent office on 1975-11-18 for driving tool mechanism.
This patent grant is currently assigned to Textron Inc.. Invention is credited to Charles J. DeCaro.
United States Patent |
3,920,169 |
DeCaro |
November 18, 1975 |
Driving tool mechanism
Abstract
A mechanism for feeding a strip of metal fasteners to an impact
tool for driving the fasteners into a workpiece includes a barrel,
a magazine for holding and feeding the strip to a piston in the
barrel and a bushing within the barrel. The bushing is adapted to
float between a first position where it engages the strip while a
fastener is separated from the strip and driven and a second
position where it disengages the strip to permit the strip to be
advanced by the magazine to align a successive fastener with the
driving piston of the impact tool and to exit the used strip
through an opening in the barrel. The strip is held between the
bushing and the barrel or between the bushing and a portion of the
magazine which extends into the barrel.
Inventors: |
DeCaro; Charles J. (Brighton
Township, Allegheny County, PA) |
Assignee: |
Textron Inc. (Providence,
RI)
|
Family
ID: |
27016078 |
Appl.
No.: |
05/499,642 |
Filed: |
August 22, 1974 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
397998 |
Sep 17, 1973 |
|
|
|
|
Current U.S.
Class: |
227/136; 227/120;
227/95 |
Current CPC
Class: |
B25C
1/005 (20130101) |
Current International
Class: |
B25C
1/00 (20060101); B25C 001/00 () |
Field of
Search: |
;227/66,93,95,120,136 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Custer, Jr.; Granville Y.
Attorney, Agent or Firm: Webb, Burden, Robinson &
Webb
Parent Case Text
This application is a continuation-in-part of my earlier filed,
copending application, filed Sept. 17, 1973, bearing Ser. No.
397,998, now abandoned .
Claims
I claim:
1. A mechanism for feeding a strip of metal fasteners to an impact
tool having a reciprocable piston for driving the fasteners through
an impact stroke into a workpiece comprising:
A. a barrel including an exit means extending through a wall
thereof for attachment to the impact tool;
B. a magazine for holding the strip and disposed with respect to
the barrel to feed the strip into the barrel in driving position
with respect to the piston; and
C. a bushing disposed and secured within an end of the barrel and
having an end positioned with respect to the strip to retainably
engage edges of the strip between the bushing and the barrel wall
adjacent the exit means during the impact stroke of the piston to
permit separation of the fastener from the edges of the strip and
to disengage from the strip after impact to permit advancement of
the strip into the barrel and through the exit means.
2. The mechanism of claim 1 wherein a rail of the magazine extends
into the barrel and the strip is retained between the bushing end
and the rail.
3. A mechanism as set forth in claim 1 wherein the bushing is
secured within the barrel by a set screw extending through a wall
of the barrel and into a slot formed in a wall of the bushing.
4. A mechanism as set forth in claim 1 wherein the bushing
comprises a tubular shank having an enlarged head positioned
outside the barrel and a shank disposed within the barrel of the
mechanism.
5. A mechanism as set forth in claim 4 including a spring
positioned between the enlarged head of the bushing and the barrel
so as to urge the bushing into an extended position.
6. A mechanism as set forth in claim 1 wherein the edges of the
strip comprise a pair of plastic rails between which the fasteners
to be driven are held, and the bushing includes a tubular shank
having cutting edges on its upper end for engaging the strip rails
during driving of the fastener by the tool and for facilitating
separation of the fastener.
7. A mechanism as set forth in claim 1 wherein the magazine
includes a strip trackway and a feeder mechanism having finger
means for engaging the strip and a spring loaded pivotable cam
means engageable by a sleeve surrounding the barrel during the
impact stroke to slide the finger means rearward over the strip and
to permit engagement of the strip thereby for advancement along the
trackway into the barrel.
8. The mechanism of claim 7 wherein the cam means includes a disc
off center rotatably connected to the feeder mechanism so as to be
adjustable through rotation about the connection.
9. In a mechanism for feeding metal fasteners to an impact tool for
driving into a workpiece, which mechanism comprises a barrel having
a reciprocable piston actuatable by the tool and a magazine for
feeding a strip of fasteners through an entry slot of the barrel
for impacting by the piston, the improvement comprising a bushing
comprising a tubular shank having an enlarged head at its lower
end, an entry slot in registry with the barrel entry slot and edges
on the upper end for holding the strip during impacting, said shank
being disposed within the end of the barrel removed from the tool
and movable between a first position where the edges engage the
strip during impacting of the fastener and a second position after
impacting where the edges of the bushing are disengaged from the
strip.
10. A mechanism as set forth in claim 9 wherein a slot is provided
in the shank of said bushing for admitting a fastener to the
driving position within the barrel, the bottom of the slot being
tapered inwardly toward the center of the bushing to facilitate
alignment of the fastener with the piston during driving of the
fastener.
11. A mechanism as set forth in claim 9 wherein said bushing head
is threaded to the lower end of the tubular shank whereby the
length of the bushing can be changed to maintain the effective
length of the stroke despite any change in the length of the
driving piston.
12. A mechanism as set forth in claim 9, said bushing having a slot
in the tubular shank adjacent the barrel wall and a screw extending
through the wall into the slot in the bushing shank to limit
movement of the bushing within the barrel.
13. The mechanism as set forth in claim 12 wherein said bushing
slot is helically formed so that the bushing rotates during
movement between the first and second position thereby positioning
the bushing entry slot out of registry with the barrel entry
slot.
14. A mechanism as set forth in claim 9, said bushing including a
stop means positioned on the end of the shank opposite the head and
away from said magazine to stop the movement of the strip between
successive impact strokes.
15. A mechanism as set forth in claim 9 wherein the enlarged head
of said bushing includes a contoured work contacting surface.
Description
This invention relates to a tool and particularly to a mechanism
for an impact tool which rapidly feeds fasteners from plastic
strips into position for driving and which enables the fasteners to
be disengaged from the strip in a continuous manner.
Power driven impact tools are used to drive metal fasteners in a
variety of industrial applications. To increase the speed at which
the fasteners can be driven and for the operator's convenience, a
plurality of fasteners have been mounted on a single strip, usually
made of plastic material; the strip has been fed to an impacting
means, such as a pneumatic gun, and the fasteners have been driven
successively from the strip into a workpiece. Recently, an improved
plastic strip has been introduced in which the fasteners are
positioned on the strip between two rails of plastic. It is an
object of this strip construction that when a fastener is driven,
it carries with it a thin plastic part of the strip in which it is
embedded between the rails and that the thin plastic part serves as
a washer to seal the fastener with the workpiece.
In order to drive such a fastener it is important to design a
mechanism which can rapidly and effectively engage and disengage
the fastener strip to permit the fastener to be properly driven
into the workpiece.
Attempts have been made to develop suitable mechanisms for feeding
a strip of fasteners to an impact tool which can be easily loaded
with the strip and which will not be jammed by the strip which is
required to carry the fastener and in certain applications provide
a sealing washer on the driven fastener. One of these attempts
involved the use of a standard pneumatic impact gun and an
impacting piston or driver which extended within a cylindrical
barrel connected to the barrel of the gun. A magazine, comprising a
strip-carrying channel and slide means for advancing the strip, was
mounted perpendicular to the piston and barrel. The leading end of
the magazine was cammed to cooperate with the cylindrical barrel
such that upon impact of the gun, the piston separated a fastener
from the strip with its plastic washer, the strip rails fed through
the barrel of the mechanism and another fastener was aligned with
the piston for driving on the next stroke. There were several
drawbacks in this design, however, including the fact that the
first fastener in the magazine had to be aligned by hand with the
impact piston to start the strip through the gun. In addition, it
was difficult to feed the strip into the tool because of the close
tolerances required in the barrel opening to support and hold the
strip during the driving operation. Due to the relative softness of
the plastic strip, the fasteners were not cleanly separated from
the strip and the deformed plastic interferred with continuous
operation of the feed mechanism. Since in this design the slide of
the magazine could not be removed from the mechanism, the operator
often was required to try to realign the deformed strip with the
impact piston using one hand, working in the confined space between
the barrel and the magazine slide. Another disadvantage of this
type of mechanism was that very close manufacturing tolerances were
required to insure that the strip was fed smoothly to the impact
piston, properly held during driving of the fastener and advanced
to align the next fastener with the piston.
A further development in such mechanisms included extending the
walls of the piston-carrying barrel so that the magazine was guided
accurately with respect to the channel in which the strip was
carried to prevent the strip from jamming in the mechanism. To do
this, however, required even stricter tolerances and did not
overcome the problems previously mentioned.
I have invented a feed mechanism for an impact tool which includes
a magazine for holding a replaceable strip of fasteners and means
for separating the fasteners from a part of the strip upon impact.
The magazine holds and feeds the strip to the piston in the barrel.
The means for separating the fasteners from the strip comprises a
floating bushing which carries strip-holding edges at an end
adjacent the strip. The bushing has limited movement in the barrel
from a first position for holding the rails of the strip to a
second position where it is disengaged from the strip to permit the
strip to be advanced to align a new fastener with the driving
piston. The rails are held between the bushing and the barrel or
the bushing and a portion of the magazine which extends into the
barrel. In a modification of the bushing, I have provided means,
such as a ramped surface, for better aligning a fastener as it is
driven under impact of the tool and cutting edges for facilitating
removal of the washer portion from the rail portion of the strip.
In another modification, the bushing is made of a plurality of
parts, adjustable with respect to each other, to change the
effective length of the bushing and consequently to determine the
effective length of the stroke of the piston to control the action
of the driven fastener. The bushing can likewise be rotated to
position its fastener opening within the barrel. The bushing is
readily interchangeable so that the workpiece contacting surface of
different bushings may vary to conform to different workpiece
profiles. The strip moving mechanism can be made adjustable to
accommodate different strips and tolerance accumulations.
My invention enables a strip of fasteners to be initially properly
loaded in an impact tool with substantial repeatability, and the
fasteners to be driven without malfunction of the mechanism and in
less time. In addition, the bushing retains the fastener in
position and prevents the fastener from jamming within the driving
tool.
I have further disclosed my invention in the description which
follows, taken with the accompanying drawings in which:
FIG. 1 is a side elevational view of the mechanism of my invention
showing the tool prior to impact;
FIG. 2 is a partial end view of the magazine;
FIG. 2A is an enlarged end view of a portion of the magazine and
slide;
FIG. 3 is a view taken along lines III--III of FIG. 2;
FIG. 4 is an enlarged side view of the floating bushing of the
invention showing its relation to a strip of fasteners;
FIG. 5 is an enlarged end view similar to FIG. 4;
FIG. 6 shows a modification of the bushing of FIGS. 4 and 5;
FIG. 7 is a top view of the bushing of FIG. 6;
FIG. 8 shows the mechanism of FIG. 1 in position immediately after
impact of the piston;
FIG. 9 shows a further modification of the bushing;
FIG. 9A is a plan view of the bushing of FIG. 9;
FIG. 10 shows the bushing with a modified works contacting
head;
FIG. 11 is a side elevational view of a modified tool;
FIG. 12 is an end view of a portion of the modified tool;
FIG. 13 is a section through an adjustable stop for the driving
piston;
FIG. 14 is a section through the strip moving mechanism of the
modified tool;
FIG. 15 is a section through the strip moving mechanism in an
extended position;
FIG. 16 is an elevational view of a bushing having a cutting edge;
and
FIG. 17 is a schematic of a bushing having a helical slot.
Referring to FIG. 1, mechanism 10 for holding and feeding a
fastener disposed in strip material is connected by screw threads
12 of a sleeve 14 to a conventional impact driving tool 16. A
barrel 18 is moveably disposed within the sleeve and carries a
reciprocable piston 20 actuatable by impact of the tool to drive a
fastener, such as a nail, into a workpiece. The cross-sectional
configuration of the barrel and slide is not critical, but I prefer
a square cross-section for both because of the inherent strength
characteristics. A coil spring 22 is disposed between an end of the
barrel 18 and the end of the sleeve 14 to urge the barrel in a
direction away from the impact tool. However, if the gun is used in
a vertical position the spring may be eliminated. A floating
bushing 24 fits within the end of the barrel as will be explained
in further detail hereinafter.
A magazine 15 extends perpendicular to the end of the barrel which
carries the floating bushing. The sidewall of the barrel and the
bushing opposite the magazine 15 are open and aligned to permit a
fastener to be advanced by the magazine into alignment with the
piston for driving by the impact tool.
The magazine 15 (FIGS. 2, 2A and 3) comprises a U-shaped frame 25
having upstanding legs 27 with opposed longitudinal grooves 29
extending toward the barrel 18. A clip 26 having a pair of
outwardly extending lugs 31 engageable in grooves 29 is removably
mounted on the frame. The clip includes two outer C-shaped channels
30 for receiving strip 32 and for guiding the strip to the driving
piston 20. The strip 32 is advanced (so that successive fasteners
36 can be driven) by a slide 28 which includes means such as lugs
38 which are engageable between the legs 27 of frame 25 and the
C-shaped channels 30 permitting the slide to move toward and away
from the barrel 18, FIG. 2A. Claw means 40 are secured to the top
of the slide 28 and engageable with the strip 32. The claw means 40
includes a hook-shaped member 42 which is adapted to engage the
strip 32 and which is resiliently attached to the slide 28 by flat
spring 44 such that the hook-shaped member 42 disengages and rides
over the strip 32 upon retraction of the slide 28 and engages the
strip 32 upon advancement of the slide 28 to advance the strip 32
into alignment with the driving tool 16. The slide 28 is biased by
at least one coil spring 46 (see FIG. 1) which is attached to the
slide 28 and to the magazine 15 to urge the slide 28 along frame 25
of the magazine such that, after each impact, strip 32 is advanced
by the slide 28 to present a new fastener 36 from the strip 32 to
the impact piston 20. The slide 28 is retracted during each impact
by the action of the sleeve 14, the leading edge 48 of which is
rounded to engage a cammed surface 50 on the leading edge of the
slide 28 to drive the slide 28 away from the barrel 18, the strip
32 being held in place by the floating bushing 24, as described
hereinafter.
As the strip 32 advances and successive fasteners 36 are driven
separating them from the strip 32 with a washer, two rails 52 are
formed which advance through spaced openings 54 in the barrel 18,
FIG. 3. After the strip 32 is exhausted of fasteners, the rails 52
fall out or are manually removed from openings 54 and
discarded.
The floating bushing 24 (FIGS. 4 and 5) comprises tubular shank 56
and an enlarged head 58. The shank 56 is disposed in the end of the
barrel 18 opposite the tool 16 and the enlarged head 58 is
positioned immediately outside of barrel 18. The edges 60 on the
end of the shank 56 opposite head 58 are adapted to engage the
strip rails 52 to hold the strip 32 between the edges 60 and the
barrel 18 adjacent the openings 54 during impact of the tool 16 to
drive a fastener, FIGS. 3 and 5. The shank 56 of the bushing 24 has
a longitudinal opening 62 to permit a fastener 36 to pass through
it into alignment with the piston. The bushing 24 is retained in
the barrel 18 by a set screw 64 (FIG. 1) which extends through the
barrel 18 into a slot 66 in the sidewall of the bushing 24 opposite
the opening 62. The length of the slot 66 determines the
permissible movement of the bushing 24 in the barrel 18.
The bushing may be spring loaded multiple pins which engage rails
52, but preferably the bushing is made in one piece or as shown in
FIG. 6, the enlarged end 58 may be threadably secured to the shank
56, thus making it possible to adjust the length of the bushing and
thereby the effective length of the stroke of the driving piston.
For example, if the end of a worn out piston is ground to provide a
better contact surface with the fasteners to be driven, the head
may be adjusted on the shank of the bushing to shorten it thereby
maintaining the overall stroke as it was before the grinding. It is
important to properly control the length of the stroke so as to
properly drive a fastener into a workpiece without driving it short
or driving it through the plastic washer.
The bushing may also include an edge ramp 68 (FIGS. 6 and 7) which
is tapered inwardly and downwardly of the bushing sidewall to
assist in alignment of any fastener during impact.
The bushing 24 may also include the stop 70 for the strip 32, FIG.
9. In the earlier embodiments the strip 32 was stopped when the
washer carrying the fastener engaged the barrel 18, and the rails
52 of the strip 32 advanced through the spaced openings 54, FIG. 3.
Stop 70 is merely an upward extension of part of the wall thickness
of shank 56' so the stop 70 does not interfere with the movement of
the piston 20 which passes through the central passageway of shank
56', FIG. 9A. By including the stop 70 with the bushing, the spaced
openings can be replaced by a large slot (not shown) in the barrel
to further simplify the loading and operation of the strip. The
stop can be constructed to accommodate various strip
configurations.
The head 58 of the bushing 24 may be configured to conform with the
particular environment in which the fasteners are to be used. For
example, where corrugated metal roofing is being installed, a
bushing having a convexly contoured work contacting surface 72 can
be employed to easily fit within the valleys of the corrugations,
FIG. 10. The bushing is readily interchangeable by merely loosening
the set screw 64, FIG. 1.
In operation, a plastic strip 32 of fasteners 36 is slipped into
channels 30 such that the lead fastener 36 is positioned in
alignment with the driving piston 20. The slide 28 of the magazine
15 is pushed forwardly on the frame 25 until it engages the barrel
18 and the spring 46 is attached to the magazine 15 to maintain its
forward position under the bias of the spring 46. The impact tool
16 is then positioned such that the head 58 of the floating bushing
24 is secure against the workpiece. The continued downward movement
of the tool 16 after bushing 24 is secure against the workpiece
causes the top edge 60 of the bushing 24 to engage the strip 32
along the strip rails 52 for purposes of supporting and maintaining
the strip 32 in fixed position during driving. The impact tool 16
is triggered to drive the piston 20 against the fastener 36,
causing a part of the strip 32 to separate with the fastener 36 and
to form a sealing washer for the fastener adjacent the workpiece
under the impact. During driving the sleeve 14 abuts the cammed
surface 50 of the magazine slide 28 causing it to overcome the bias
of spring 46 as shown in FIG. 8. In addition, as the tool 16
impacts and the piston 20 is driven against the fastener, the edges
of the strip are maintained straight by the top edge 60 of the
bushing 24 pressing against the lower edge of the strip. Upon
completion of the impact stroke, the tool is removed from the
workpiece and the floating bushing 24 which is now free to move
(float) downward disengages from the strip 32. In addition sleeve
14 retracts relative to barrel 18 and under bias of the coil spring
22. As the sleeve 14 retracts the slide 28 of the magazine 15 is
urged forward by the spring 46 with the claw means 40 advancing the
strip to align the next fastener in the strip with the piston 20
while the side rails of the strip advance through the barrel
18.
The bushing moves, in any one stroke, between a first position
wherein it supports and holds rails 52 of the strip 32 against the
barrel 18 in the area adjacent openings 54 during impact and a
second position (FIG. 3) where it is disengaged from the rails 52
permitting the strip 32 to be advanced freely by the magazine slide
28 until the next impact.
I have illustrated a modified tool in FIGS. 11-16 wherein certain
like parts are identified with like numerals followed by a
prime.
The modified tool includes the barrel 18' over which sleeve 14'
slides when impacted by piston 20', FIG. 11. The magazine 15',
however, is substantially altered from the earlier embodiment.
Magazine 15' is secured to the barrel 18' and includes upper spaced
and parallel rails 76 for accommodating the strip 32. Rails 76
through a rail extension 105 curve about and are secured to the
bottom rail mount 92 by a set screw 78 which can also accommodate
setting fixtures (not shown). Guide posts 77 extend upwardly from
rails 76 to guide the side rails 52 of strip 32. Rails 76 extend
all the way into the barrel 18', FIG. 14. Mounted atop of rails 76
within barrel 18' are C-shaped trackways 88 which accommodate the
side rails 52 of strip 32. The rails 76 and trackways 88 are
aligned with the top surface of the bushing 74, FIGS. 12 and 14, so
that the side rails 52 of strip 32 can be engaged by the bushing 74
during impact, FIG. 15. During impact the rails 52 are retained
between the bushing 74 and the upper inner surface 99 of trackways
88.
The slot 100 through which passes the exiting rails 52 is a single
opening rather than spaced openings 54 as in the earlier
embodiment. Therefore, the positioning of the fastener 36 by the
feeder mechanism 75 is critical since there is no stop against
which the washer portion 94 of the strip 32 abuts as described
hereinbefore.
The feeder mechanism 75 is pivotably secured to the bottom rail
mount 92 by pivot pin 101, FIG. 12. The strip 32 is engaged by
spaced fingers 42' which are connected to a finger plate extension
86 which in turn is pivotally mounted to the feeder mechanism 75 by
pin 87. Return spring 84 connected between the finger plate
extension 86 and the feeder mechanism 75 urges the fingers 42' into
engagement with the strip 32 during operation.
This operation is best illustrated in FIGS. 14 and 15. During an
impact stroke, sleeve 14' moves down over barrel 18'. Sleeve 14'
engages cam disc 80 which is secured to feeder mechanism 75. As
sleeve 14' engages cam disc 80, feeder mechanism 75 pivots about
pin 101 and the fingers 42' slide back over the strip 32 to engage
the strip 32 for its next advancement. After impact, flat spring 79
connected between cam disc 80 and rails 76 urge the feeder
mechanism 75 forward as the sleeve 14' moves up over barrel 18'. As
feeder mechanism 75 advances forward the strip 32 now engaged by
the fingers 42' advances into the barrel 18' and positions the next
fastener 36 into position, FIG. 14.
I have provided two adjustments on my feeder mechanism 75 to
accommodate tolerance accumulations and different fastener 36 or
washer 94 spacings, FIG. 11. Cam disc 80 is mounted off center by
cam screw 82 which also extends through cam washer 81 and
threadably engages the feeder mechanism 75. By rotating cam disc 80
the positioning of the fasteners 36 within the bushing 74 is
altered. I have also mounted an L-shaped bracket 83 atop the feeder
mechanism 75. A bolt 93 extends through bracket 83 and contacts
barrel 18' to control the spacing between the barrel 18' and the
feeder mechanism 75. Bolt 93 threadably engages adjusting nut 85 so
as to permit adjustment for the desired spacing.
To further assure proper alignment of the fastener 36, I have
provided an aligning pad 89 within the barrel 18' to lightly
frictionally engage the top of the fastener 36 as it enters the
barrel 18', FIG. 12. This frictional engagement merely removes any
fastener cant and assists in directing the fastener 36 along the
center line of the barrel 18'.
The bushing 74 can be spring loaded, FIG. 14, by positioning a coil
spring 90 between the enlarged head 58' and a counterbore 91 in the
bottom of the barrel 18'. This permits the tool to be efficiently
used in the horizontal as well as vertical position.
In the bushing 74 illustrated in FIG. 16, the upper edge 95 is
formed so as to form a knife edge to facilitate removal of the
washer portion 94 from the rails 52. Such a construction is
particularly useful where a soft plastic is utilized in forming the
strip 32.
The bushing 74' can also be constructed so as to rotate during its
axial movement, FIG. 17. The slot 66' in the shank 56' is helically
formed so that as pressure is placed on the tool, the bushing 74'
overcomes the frictional engagement of the head 58' to the
workpiece and the bushing 74' rotates about the set screw 64'. The
effect of this is to position the fastener entry slot 62' out of
registry with the barrel opening for the fasteners. This eliminates
the possiblity of the fastener being driven out of the barrel if it
is misaligned. The remaining operation, namely that of the bushing
relative to the plastic strip 32, can be in accordance with any of
the earlier embodiments.
* * * * *