U.S. patent number 3,771,710 [Application Number 05/183,979] was granted by the patent office on 1973-11-13 for pneumatically powered fastener-driving tool.
This patent grant is currently assigned to Spotnails, Inc.. Invention is credited to Laurel I. Mitschelen, Garry R. Perkins.
United States Patent |
3,771,710 |
Perkins , et al. |
November 13, 1973 |
**Please see images for:
( Certificate of Correction ) ** |
PNEUMATICALLY POWERED FASTENER-DRIVING TOOL
Abstract
A pneumatically powered fastener-driving tool is provided which
includes a manually selective automatic recycling means. The speed
of recycling may be adjusted as desired, and the exhausted
compressed air is deflected so as to protect the operator, as well
as the workpiece.
Inventors: |
Perkins; Garry R. (Cary,
IL), Mitschelen; Laurel I. (Palatine, IL) |
Assignee: |
Spotnails, Inc. (Rolling
Meadows, IL)
|
Family
ID: |
22675113 |
Appl.
No.: |
05/183,979 |
Filed: |
September 27, 1971 |
Current U.S.
Class: |
227/130 |
Current CPC
Class: |
B25C
1/043 (20130101) |
Current International
Class: |
B25C
1/04 (20060101); B25c 001/04 () |
Field of
Search: |
;227/130 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Custer, Jr.; Granville Y.
Claims
We claim:
1. A pneumatically powered fastener-driving tool comprising a
hollow housing; an elongated cylinder mounted within said housing
and cooperating therewith to form a pair of longitudinally spaced
upper and lower cavities adjacent the exterior of said cylinder,
said cylinder being provided with a pair of longitudinally spaced
upper and lower openings, communicating respectively with the upper
and lower cavities, said upper cavity being continuously charged
with pneumatic pressure; a pneumatically responsive driver piston
mounted for reciprocatory movement within said cylinder between a
fully retracted position and a fully extended position, said piston
having a head in sliding sealing engagement with an upper portion
of the cylinder interior surface, and a flange spaced
longitudinally from said head and in sliding sealing engagement
with a lower portion of said cylinder interior surface and
cooperating with said head to form a pressure chamber therebetween;
the longitudinal spacing between said head and flange being greater
than the spacing between said upper and lower openings, the surface
of said head adjacent said pressure chamber having a greater area
than the corresponding surface of said flange, said driver piston
flange being disposed intermediate said upper and lower openings
when said piston is in said fully retracted position, and both said
upper and lower openings being in communication with said presssure
chamber when said piston is in said fully extended position, a
poppet valve mounted within said housing interior adjacent the
upper end of said cylinder for movement between open and closed
positions and biased to normally assume a closed position, said
poppet valve, when in open position, effecting communication
between the interior of said cylinder above the driver piston head
and said upper cavity whereby said piston moves from said fully
retracted to said fully extended positions, said poppet valve, when
in a closed position, interrupting communication between said upper
cavity and the interior of the cylinder above said driver piston
head and effecting exhaust of the cylinder interior above said
driver piston head whereby said driver piston automatically returns
to said fully retracted position; a manual trigger valve mounted on
said housing and when in an actuated position effecting a pressure
differential on opposite sides of said poppet valve wherein the
latter moves to said open position; and a manually adjustable
control valve mounted on said housing and having a first portion
for regulating the time interval for exhausting the cylinder
interior above said driver piston head subsequent to said poppet
valve assuming said closed position; said control valve having a
second portion, when in one position of adjustment, interconnecting
said lower cavity and housing interior above said poppet valve and
effecting continuous recycling of said driver piston when said
trigger valve is manually retained in said actuated position.
2. The pneumatically powered fastener-driving tool of claim 1
wherein the lower opening in said cylinder communicates with said
pressure chamber when the moving driver piston has reached a first
predetermined position relative to the upper end of said cylinder,
and said lower opening communicates with the exterior of said tool
when the moving driver piston has reached said fully retracted
position relative to said cylinder upper end.
3. The pneumatically powered fastener-driving tool of claim 1
wherein said manually adjustable control valve is located
intermediate said cylinder and said trigger valve.
4. The pneumatically powered fastener-driving tool of claim 3
wherein said adjustable control valve includes a deflector means
mounted on a component thereof.
5. The pneumatically powered fastener-driving tool of claim 11
wherein the interior of said cylinder above the driver piston head
is exhausted directly to the exterior of said tool when said poppet
valve is in said closed position.
6. The fastener-driving tool of claim 1 wherein said housing
includes a hollow handle wherein compressed air accumulates and is
in communication with said upper cavity and said trigger valve is
mounted on said hollow handle.
7. The fastener-driving tool of claim 6 wherein said housing
includes a fastener feed portion and said feed portion and hollow
handle are of monolithic construction.
Description
BACKGROUND OF THE INVENTION
Various fastener-driving tools with automatic recycling features
have heretofore been provided; however, because of certain design
characteristics they have been beset with one or more of the
following shortcomings: a. the housing in which the drive piston is
mounted is formed of a plurality of component parts which are
susceptible of becoming loose and out of adjustment due to
vibration forces caused particularly when the tool is operating at
high speeds over a prolonged period of time, b. there is no
accurate means provided for varying the speed of recycling of the
tool, c. the prior tools are position sensitive, that is to say
they worked properly only when held in a predetermined position by
the operator, d. the automatic recycling mechanism is located in an
awkward and somewhat inaccessible position on the tool, e. the
compressed air exhausted by the prior tools oftentimes has
entrained therein grease, dust, or other debris which is directed
towards the operator or workpiece thereby causing injury to the
operator or defacement to the exposed surface of the workpiece, f.
the prior tools are oftentimes of bulky, heavy construction thereby
causing fatique to the operator after only a short period of
use.
SUMMARY OF THE INVENTION
Thus, it is an object of this invention to provide a
fastener-driving tool which is of simple, lightweight, inexpensive
construction and yet has incorporated therein an effective
automatic recycling mechanism.
It is a further object of this invention to provide a
fastener-driving tool with automatic recycling having a monolithic
housing which significantly reduces maintenance costs.
It is a still further object of this invention to provide a driving
tool of the type described which incorporates safety features for
protecting the operator and workpiece against blasts of the
exhausted compressed air.
It is a still further object of this invention to provide a
fastener-driving tool having an automatic recycling mechanism which
may be readily adjusted to accurately vary the recycling speed.
Further and additional objects will appear from the description,
accompanying drawings, and appended claims.
In accordance with one embodiment of this invention a pneumatically
powered fastener-driving tool is provided comprising a hollow
monolithic housing having a chamber formed therein in which
compressed air is accumulated. Disposed within the housing is an
elongated cylinder having a pair of longitudinally spaced ports
formed in the wall intermediate the ends thereof. A poppet valve is
adjustably positioned adjacent one end of the cylinder and controls
the introduction of compressed air into the cylinder to effect
firing of a fastener-driving piston mounted for reciprocatory
movement within said cylinder. The poppet valve is mounted for
sliding sealing engagement within a cavity formed in a cap, the
latter being mounted on the end of the housing. The cylinder
cooperates with the housing interior to form a pair of
longitudinally spaced annular cavities. One of the cylinder wall
ports, closest to the poppet valve, communicates with one annular
cavity and the second wall port communicates with the other annular
cavity. The one annular cavity is in constant communication with
the housing chamber and thus, is continually charged with
compressed air. The outer periphery of the poppet valve projects
outwardly beyond the cylinder wall and is exposed to the said one
annular cavity. The housing is provided with first and second
passageways; the first passageway having one end thereof
communicating with the cap cavity. The first passageway end is
separated from the end of the cylinder by the poppet valve. The
opposite end of the first passageway terminates at a manually
adjustable trigger valve carried by the housing. The second
passageway has one end thereof communicating with the annular
cavity furthest removed from said poppet valve. The opposite end of
said second passageway communicates with said trigger valve.
Communication between the corresponding ends of the first and
second passageways is controlled by a manually adjusted spool
forming a part of the trigger valve. The driving piston is of a
double spool type and is provided with an enlarged head which is
disposed adjacent the poppet valve when said piston is in its fully
retracted position within said cylinder. Spaced longitudinally from
the enlarged head is an annular flange which is in sliding sealing
engagement with the cylinder interior wall. When the piston is in
its fully retracted position, the annular flange is positioned so
as to sealingly separate the longitudinally spaced ports formed in
the cylinder wall. When the driving piston is in its fully
extended, or drive, position, both of the longitudinally spaced
ports communicate with the spacing formed between the head and
flange of the piston. The buildup of compressed air pressure within
the spacing between the head and flange of the piston when the
latter is in its fully extended position is such that the piston
will be automatically returned to its fully retracted position.
A manually actuated automatic recycling valve is mounted on said
housing and, when in one position of adjustment, will cause
automatic recycling or repeated firing of the driving piston,
provided the trigger valve is depressed.
For a more complete understanding of the invention reference should
be made to the drawings wherein:
FIG. 1 is an elevational view of one form of the improved
fastener-driving tool.
FIGS. 2 and 3 are fragmentary vertical sectional views of the tool
of FIG. 1 and showing, respectively, the driving piston in its
fully retracted and fully extended positions.
FIG. 4 is a fragmentary sectional view taken along line 4--4 of
FIG. 2 and showing the automatic recycling valve in a non-recycling
position.
FIG. 5 is similar to FIG. 4, but taken along line 5--5 of FIG. 3
and showing the recycling valve in position for automatic recycling
of the piston.
FIG. 6 is similar to FIG. 2, but showing a modified form of the
improved fastener-driving tool.
FIG. 7 is similar to FIG. 5, but taken along line 7--7 of FIG. 6
and showing the recycling valve in position for automatic recycling
of the driving piston.
Referring now to the drawings and more particularly to FIGS. 1-5,
one form of a pneumatically powered fastener-driving tool 10 is
shown which comprises a monolithic, or one piece, housing 11. The
housing includes a hollow driving piston portion 12, a hollow
handle portion 13, and a fastener feed portion 14. The handle
portion 13 is provided, at its outer end, with a suitable connector
C to receive one end of an air hose. On the upper end of the
housing portion 12 is removably mounted a hollow cap 15. On the
opposite or lower end of portion 12 is mounted a nose section,
N.
Fixedly secured within housing portion 12 is an elongated cylinder
16 which has the upper interior portion 16a thereof of slightly
greater diamter than the lower interior portion 16b, as seen in
FIGS. 2 and 3. The exterior of cylinder 16 cooperates with the
hollow interior of housing portion 12 so as to form a pair of
vertically, or axially spaced annular cavities 17 and 18. Upper
cavity 17 is in continuous communication with the hollow interior
13a of the handle portion which, in turn, is charged with
compressed air.
The wall of cylinder 16 is provided with two sets 20 and 21 of
apertures which are arranged in axially spaced cylinder-encircling
rows. The row of apertures 20 is disposed adjacent the lower end of
the cylinder interior portion 16a and effects communication between
annular cavity 17 and the cylinder interior. The row of apertures
21, on the other hand, is located in the upper portion of the
cylinder interior 16b, see FIG. 2. Apertures 21 effect
communication between annular cavity 18 and the cylinder
interior.
Mounted for reciprocatory movement within cylinder 16 is a driver
piston 22 which, in the illustrated embodiment, is a double spool
type. The upper end of the piston is provided with an enlarged
annular head 23, the outer periphery of which is in sliding sealing
engagement with the cylinder interior portion 16a. Spaced axially
downwardly from head 23 is an annular flange 24 which is in sliding
sealing engagement with the cylinder interior portion 16b. The
spacing or pressure chamber S between head 23 and flange 24 is
greater than the spacing between the rows of apertures 20 and 21.
In normal operation, the row of apertures 20 is in continuous
communication with the portion (spacing S) of the cylinder interior
delimited at opposite ends by the head 23 and flange 24. The row of
apertures 21, on the other hand, is in communication with the
cylinder interior disposed beneath flange 24, when the piston 22 is
in its fully retracted or return position, see FIG. 2. When,
however, the drive piston 22 is in its fully extended or fire
position, see FIG. 3, apertures 21 communicate with the portion of
the cylinder interior disposed between the head 23 and flange 24,
see FIG. 3. The radius of head 23 is slightly greater than the
radius of flange 24 and thus, when both rows of apertures are in
communication with the spacing S, the force exerted by the
compressed air on the underside of the head 23 will be greater than
that exerted on the upper side of flange 24, because of the area
difference and thereby cause the drive piston to return to its
fully retracted position.
Depending axially from the underside of flange 24 is an elonagated
driver blade 25. The blade 25 extends through a central opening 26a
formed in a resilient ringlike bumper 26, the latter being
removably mounted within the housing interior at the lower end of
cylinder 16. The bumper is arranged in concentric relation with
respect to an opening 27 formed in the bottom of housing portion
12. The bumper may be readily replaced, when required, and serves
to cushion the impact of the flange 24 when the piston 22 reaches
the end of its drive stroke, see FIG. 3.
The lower end of the driver blade is adapted to to be quided by the
nose piece N so as to engage a fastener automatically fed from the
housing feed portion 14 and drive same into a workpiece.
Adjustably mounted on the upper end of the cylinder 16 and adapted
to overlie same is an annular poppet valve 28. The valve is adapted
to move between an open position, see FIG. 3, and a closed
position, see FIG. 2, with respect to the upper end of the
cylinder. The valve 28 is disposed within a suitable cavity 30
formed within the interior of the cap 15. Valve 28, when in its
closed position, has a portion of the underside of the outer
periphery thereof extending laterally beyond the cylinder upper end
into annular cavity 17 and thus, is exposed to the compressed air
accumulated therein. The outer periphery of valve 28 is in sliding
sealing engagement with the interior surface of cavity 30.
Extending upwardly from the central portion of valve 28 is a
cylindrical protuberance 31, the exterior of which is in sliding,
sealing engagement with a second cavity 32 formed in the cap
interior. Protuberance 31 is provided with an axial bore 33 which
extends through the entire valve 28. The valve 28 is biased in a
closed position with respect to the cylinder upper end by one or
more suitable coil springs 34.
Mounted at the upper end of the second cavity 32 is a disc-shaped
seal 35, which is adapted to be engaged by the upper end of valve
protuberance 31 and close off the upper end of bore 33, see FIG. 3,
when the poppet valve is in its open position.
Communicating with and extending laterally from the upper end of
the second cavity 32 is an air discharge port 36 formed in the cap
15. The lower end of the port 36 is aligned with an elongated
passageway 37 formed in the housing portion 12. The lower end of
passageway 37, in turn, terminates in a chamber 38, see FIGS. 2 and
4, formed in the housing and in which is adjustably positioned a
manual/automatic recycling valve 40. The chamber 38 is disposed to
one side of cylinder 16 and extends transversely of the axis of
said cylinder. Opposite ends 38a and 38b of the chamber are open to
the atmosphere. Chamber end 38a is the smaller of the two ends and
is adapted to accommodate in sliding, sealing engagement the small
end 40a of the valve 40.
Also communicating with chamber 38 are two additional passageways
41 and 42 which are formed in the housing interior. Passageway 41
interconnects chamber 38 with the lower annular cavity 18 which
encircles the lower portion of drive cylinder 16. Passageway 42, on
the other hand, interconnects the chamber 38 with a ported sleeve
43 which forms a part of a trigger valve 44 carried on the handle
portion 13 of the housing 11. The functions of the passageways 37,
41 and 42 with chamber 38 are in axially spaced relation, as seen
in FIG. 4. Valve 40 is manually adjustable axially within chamber
38. When the valve 40 is moved to the right to the position shown
in FIG. 4, passageways 37 and 42 are vented to the atmosphere and
passageway 41 is blocked. When the valve 40 is in the position,
shown in FIG. 4, the driver piston 22 will not recycle and continue
to fire, even though the trigger valve 44 is held in a depressed
condition.
As will be noted in FIG. 5, when valve 40 has been manually moved
inwardly to the fullest extent into the chamber 38, the inner end
40a of the valve 40 is provided with a reduced cross-sectional
portion 40c which will effect interconnection between passageways
41 and 42 and cause automatic recycling and continuous firing of
the driver piston 22, provided the trigger valve 44 is manually
held in a depressed state. The method by which automatic recycling
will occur will be described more fully hereinafter. As shown in
FIGS. 4 and 5, the central portion of valve 40 may be provided with
external threads 40d which are adapted to mesh with internal
threads formed in the wall of chamber 38.
Because of the discharge of compressed air out through the enlarged
end 38b of chamber 38, an annular deflector piece 45 is carried by
the exposed end 40b of valve 40, see FIGS. 4 and 5. The deflector
piece diffuses the blast of the discharged compressed air and thus
protects the operator of the tool and the workpiece into which the
fasteners are driven, against any foreign matter or debris, which
might be entrained in the air blast. Frequently droplets of oil or
similar fluid become entrained in the discharged air blast and if
left unchecked, might cause injury to or soiling of the face of the
operator or the exposed surface of the workpiece. It will be noted
that the exposed enlarged end 40b of the valve may be knurled to
facilitate manual manipulation of the valve. The location of the
valve 40 on the housing 11 may be varied from that shown without
departing from the scope of the invention. For example, if desired,
the valve 40 may be located in the cap 15.
The trigger valve 44, as aforementioned, is preferably located in
the handle portion 13 of the housing 11, see FIG. 2. The valve 44
includes the ported sleeve 43 which is shrunk-fit into a
cylindrical bore 46 formed in the handle portion. The upper end of
the sleeve is open and exposed to the handle chamber 13a in which
compressed air is accumulated. The sleeve 43 is provided with two
sets of apertures 47a and 47b which are in axially spaced relation.
Apertures 47a communicate with a passageway 48 formed in the
housing portion 11. Passageway 48, in turn, communicates with a
passageway 50 formed in cap 15 and leading to the upper end of
cavity 30 formed in the cap. Apertures 47b, on the other hand,
communicate with passageway 42.
Slidably mounted within sleeve 43 is a trigger valve piece 51. The
lower end 51a of the piece projects downwardly from the end of the
sleeve and is adapted to be manually depressed. The piece 51 may be
biased by a spring, to assume its downwardly extended position, see
FIG. 2. The valve piece 51 is retained in a conventional manner
within the sleeve 43 by means of the trigger lever, as seen more
clearly in FIG. 1. A portion 51b of the piece has a reduced cross
section. The axial length of portion 51b is greater than the axial
spacing between apertures 47a and 47b formed in sleeve 43. Adjacent
each end of portion 51b is an O-ring 52 and 53 which is in sliding
sealing engagement with the interior surface of sleeve 43. When the
tool is at rest, that is to say the trigger piece 51 has not been
manually depressed, as seen in FIG. 2, O-ring 52 is disposed
intermediate the sleeve apertures 47a and 47 b thereby preventing
interconnection between passageways 42 and 48. When the trigger
piece 51 is in said position, passageways 48 and 50, and the
portion of cavity 30 disposed above poppet valve 28, are charged
with compressed air because apertures 47a are in communication wit
the high pressure chamber 13a of the hollow handle portion 13 of
the housing 11 through the upper end of bore 46. The combination of
the air pressure within the upper portion of cavity 30 and the bias
of spring 34 exerted on poppet valve 28 are sufficient to hold the
latter in closed position over the upper end of cylinder 16 and
thus prevent firing of the driver piston 22.
Upon manual depressing of the trigger piece 51, as seen in FIG. 3,
communication between chamber 13a and passageway 48 is cut off by
the upper end of piece 51 and in place thereof portion 51b of the
piece interconnects passageways 42 and 48. Depending upon the
position of the recycling valve 40 in the chamber, the compressed
air within the upper portion of cavity 30 is vented through
passageways 50, 48, and 42 to the atmosphere out through the narrow
end 38a of chamber 38 (see FIG. 4), or is vented from passageway 42
by valve portion 40a to passageway 41 and then into annular cavity
18 and into the interior of cylinder 16 through ports 21. Once the
compressed air in the upper portion of cavity 30 has been vented to
the atmosphere, the force exerted on the underside of the outer
periphery of poppet valve 28, which extends beyond the cylinder 16,
by the compressed air in cavity 17, will overcome the bias of
spring 34 and raise the poppet valve off the upper end of the
cylinder and cause the compressed air to be exerted on the upper
surface of head 23 and move the piston 22 through its drive stroke.
Upon the compressed air entering th inerior of cylinder 16 beneath
flange 24, it will initially be exhausted to the atmosphere through
opening 27 at the lower end of the housing; however, as the driver
piston 22 moves downwardly, the apertures 21 will become registered
with the spacing S between the head 23 and flange 24 of the piston
22, which, in turn, will cause the cavity 18, passageways 41, 42,
48 and 50 and the upper portion of cavity 30 to once again be
charged with compressed air. Once this occurs, the poppet valve 28
closes and the driver piston 22 returns to its fully retracted
position. Upon the piston 22 reaching its fully retracted position,
the compressed air above the poppet valve is once again vented out
through housing opening 27 in a manner as previously described
provided the auto-recycling valve 40 is in the position shown in
FIG. 5.
The speed of return of the driver piston from its fully extended
position (FIG. 3) to its fully retracted position (FIG. 2) will
depend upon the speed with which the compressed air above the
piston head 23 is exhausted out through bore 33, passageways 36 and
37 and the enlarged end 38b of chamber 38. It will be noted in
FIGS. 4 and 5, that the portion 40e of valve 40, which is adjacent
the threading portion 40c, is outwardly tapered. Thus, as valve 40
is manually moved to the left or inwardly, as seen in FIG. 5, the
size of the exhuast passage E, which is formed between the interior
surface of chamber 38 and the exterior of the large end of the
valve 40, becomes increasingly more restricted. thus, upon rotating
valve 40 into chamber 38, a greater or lesser amount than shown in
FIG. 5, the operator can vary the speed of return or recycling, as
desired.
FIGS. 6 and 7 show a modified form of pneumatically powered tool
110 which is similar in construction to tool 10 except as to the
auto-recycle valve and the manner of controlling the air exhaust
from above the driver piston head. To simplify understanding of
tool 110, the corresponding parts thereof have been numbered the
same as tool 10 except in 100 series. In lieu of passageway 36 in
the cap 15 of tool 10, communicating with a passageway 37 formed in
the housing portion 12, tool 110 eliminates passageway 37 and in
place thereof passageway 136 is ported directly to the atmosphere.
Threadably mounted on cap 115 is an exhaust air regulator screw
200. The inner end 200a of the screw extends into passageway 136 so
as to restrict same. A deflector piece 201 is also mounted on cap
115 and diffuses the exhaust air discharged from passageway 136 so
as to prevent any debris entrained in the exhaust from striking the
operator or workpiece surfaces.
FIG. 7 shows a modified form of auto-recycle valve 140 which is
substituted for valve 40 shown in FIGS. 4 and 5. Valve 140 is
slidably disposed within a chamber 138, which is disposed to one
side of cylinder 116 and extends transversely with respect thereto.
Passageways 141 and 142 junction with chamber 138 in axially spaced
relation. The inner end portion of the valve 140 carries an O-ring
202 which is in sliding sealing engagement with the interior
surface of chamber 138. Disposed outwardly of O-ring 202 is a
portion 140a of reduced cross section, which, when the valve is
pushed inwardly relative to chamber 138 so that the O-ring 202 is
disposed between passageways 141 and 142, causes the passageway 142
to be vented to the atmosphere through flutes 203 formed in the
outer end portion of the valve. An annular collar 204 is formed on
the exterior of the exposed end of valve 140 to facilitate manual
manipulation thereof. Suitable stop means, not shown, may be
provided to limit the extent to which valve 140 can be withdrawn
from chamber 138 so as to render the tool on automatic
recycling.
As aforementioned, the location of the automatic recycling valve on
the tool may be varied from that shown so as to serve the
convenience of the operator.
Thus, it will be seen that a tool has been provided with an
automatic recycling feature which is of simple, sturdy construction
and may be readily adjusted by the operator to vary the speed of
recycling. The improved tool is provided with a safety feature
which diffuses the blast of exhaust air so as to protect the
operator, as well as the workpiece, from any debris which might be
entrained in the exhaust air. The improved tool has a monolithic
housing which materially reduces maintenance of the tool.
* * * * *