U.S. patent number 3,563,439 [Application Number 04/737,900] was granted by the patent office on 1971-02-16 for powder actuated tool.
This patent grant is currently assigned to Omark Industries, Inc.. Invention is credited to Raymond V. Pomeroy.
United States Patent |
3,563,439 |
Pomeroy |
February 16, 1971 |
POWDER ACTUATED TOOL
Abstract
A captive piston type of powder actuated tool is provided with a
barrel pivotally engaged by the forward end of the tool housing so
that the breech end of the barrel can be upraised into a loading
position. A piston retractor is slidably carried on the barrel and
includes a member extending through a slot in the barrel for
engaging the head of the piston used for moving of a piston into a
firing position. The barrel may be pivotally returned to firing
position only after the piston retractor has been moved forwardly
and out of the way of piston movement in the subsequent firing of
the tool.
Inventors: |
Pomeroy; Raymond V. (Portland,
OR) |
Assignee: |
Omark Industries, Inc.
(Portland, OR)
|
Family
ID: |
27097220 |
Appl.
No.: |
04/737,900 |
Filed: |
June 18, 1968 |
Current U.S.
Class: |
227/8;
227/10 |
Current CPC
Class: |
B25C
1/18 (20130101); B25C 1/143 (20130101); B25C
1/146 (20130101) |
Current International
Class: |
B25C
1/14 (20060101); B25C 1/18 (20060101); B25C
1/00 (20060101); B25c 001/14 () |
Field of
Search: |
;227/8,9,10 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Custer, Jr.; Granville Y.
Claims
I claim:
1. A powder actuated tool comprising:
a housing including a rearward breech portion and a forward barrel
portion;
a breechblock carried by said breech portion;
a barrel cradled by said barrel portion when said barrel is in a
first position in substantial alignment with said breechblock;
said barrel being pivotally engaged by the barrel portion of said
housing at a location toward the muzzle end of said barrel so that
the breech end of said barrel can be upraised away from said
breechblock into a loading position;
a captive piston longitudinally slidable within said barrel and
movable in response to explosion of a power load for driving a
fastener element into a workpiece at the muzzle end of said barrel;
and
a piston retractor slidably carried by said barrel, said retractor
including a member extending into said barrel for engaging said
piston and a handle portion which is manually engageable for moving
said piston retractor and said piston to a firing position toward
the breech end of said barrel.
2. The tool according to claim 1 wherein said barrel is provided
with a longitudinal slot ending short of the breech and muzzle ends
of said barrel, and wherein said member for engaging said piston
extends through said longitudinal slot in said barrel for engaging
the head of said piston at the muzzle end thereof.
3. The tool according to claim 2 wherein the head of the piston is
provided with an ejector extending from the breech end of the
head.
4. The tool according to claim 2 wherein said barrel portion of the
housing is channel-shaped and open upwardly, said slot in said
barrel being located on the lower side of said barrel toward said
barrel portion of the housing.
5. The tool according to claim 1 including a power plug received in
the breech end of said barrel for receiving a power load cartridge,
with the breechblock being movable rearwardly within said breech
portion of said housing from an uncocked to a fully cocked or
triggerable position, and wherein the barrel, in addition to being
pivotally engaged by the barrel portion of said housing, is also
slidable with respect to the barrel portion of said housing into
full engagement with said breechblock and is further rearwardly
slidable for urging said breechblock into a cocked position in
response to pressure of the muzzle end of the barrel against a
workpiece.
6. The tool according to claim 5 wherein said captive piston
includes a head provided with an ejector extending from the breech
end of said head for ejecting a cartridge from the power plug when
said piston retractor moves the captive piston to the firing
position.
7. The tool according to claim 5 including a substantially
horizontal pin member carried by said barrel portion of said
housing at said location toward the muzzle end of said barrel, said
pin member being positioned at the lower side of said barrel, and a
matching slot in the underside of said barrel through which said
pin member extends, said last mentioned slot having a longitudinal
length along said barrel permitting longitudinal sliding movement
of the barrel for full engagement with the breechblock plus
movement of the breechblock into a cocked position.
8. The tool according to claim 1 wherein the barrel portion of the
housing is substantially semicircular in cross section for cradling
a cylindrical barrel, and is provided with an arched
barrel-retaining member proximate said location toward the muzzle
end of the barrel for substantially enclosing the upper side of the
barrel at such location, said arched barrel-retaining member having
an inner semicircular surface for substantially matching the
cylindrical barrel in an upraised position thereof and for limiting
the upward movement of the barrel.
9. The tool according to claim 8 including a substantially
horizontal pin member carried by said barrel portion of said
housing at said location toward the muzzle end of the barrel, and
at the lower side of said barrel, and a matching slot in the
underside of said barrel through which said pin member extends,
said last mentioned slot having a longitudinal length along said
barrel for permitting longitudinal slidable movement of the barrel
for full engagement with the breechblock plus movement of the
breechblock into a cocked position.
10. A powder actuated tool comprising:
a housing including a rearward breech portion and a forward barrel
portion;
a breechblock carried by said breech portion;
a barrel cradled by said barrel portion when said barrel is in a
first position in substantial alignment with said breechblock;
said barrel being pivotally engaged by the barrel portion of said
housing at a location toward the muzzle end of said barrel so that
the breech end of said barrel can be upraised away from said
breechblock into a loading position;
a captive piston longitudinally slidable within said barrel and
movable in response to explosion of a power load for driving a
fastener element into a workpiece at the muzzle end of said
barrel;
and a piston retractor ring slidably carried on said barrel, said
ring carrying a member for engaging the head of said captive piston
by engaging the head of said piston on the muzzle end thereof;
handle means extending outwardly from either side of said ring for
moving said ring and said piston to a firing position toward the
breech end of said barrel; and
said barrel being provided with a longitudinal slot ending short of
the breech and muzzle ends of said barrel, wherein said member for
engaging the head of said captive piston extends through said
longitudinal slot in said barrel.
11. The tool according to claim 1 wherein said barrel portion of
said housing matingly receives said piston retractor allowing
location of said barrel in said first position only when said
piston retractor is located far enough toward the muzzle end of
said barrel so that said member for engaging the captive piston
does not interfere with the movement of the captive piston in
driving said fastener element.
12. A powder actuated tool comprising:
a housing including a rearward breech portion and a forward barrel
portion;
a breechblock carried by said breech portion;
a barrel cradled by said barrel portion when said barrel is in a
first angular position in substantial alignment with said
breechblock;
said barrel being pivotally engaged by the barrel portion of said
housing at a location toward the muzzle end of said barrel so that
the breech end of said barrel can be upraised away from said
breechblock into a loading position;
said barrel also being slidable with respect to the barrel portion
of said housing in and out of cocked position;
a captive piston longitudinally slidable within said barrel and
movable in response to explosion of a power load for driving a
fastener element into a workpiece at the muzzle end of said
barrel;
a piston retractor slidably carried by said barrel, said retractor
including a member for engaging said piston for moving said piston
to a firing position toward the breech end of said barrel; and
said barrel portion of said housing including a recess for
receiving a portion of said piston retractor toward the muzzle end
of the barrel portion of the housing when said barrel is in said
first angular position, the piston retractor being restrained
between a portion of said barrel and said recess in the barrel
portion of said housing when said barrel is in its cocked position
so that said piston retractor will not be struck by movement of
said piston in response to explosion of the power load.
13. The tool according to claim 2 including a power plug received
in the breech end of said barrel for holding a power load, said
breechblock being movable within said breech portion of said
housing from an uncocked to a fully cocked or triggerable position,
wherein the barrel, in addition to being pivotally engaged by the
barrel portion of said housing, is also rearwardly slidable with
respect to the barrel portion of said housing into full engagement
with said breechblock and is further rearwardly slidable for urging
said breechblock into a cocked position in response to pressure of
the muzzle end of the barrel against a workpiece, and wherein said
barrel portion of said housing includes a recess for receiving said
piston retractor toward the muzzle end of the barrel portion of the
housing when said barrel is in said first position, the piston
retractor being restrained between the muzzle end of the slot in
the barrel and the rearward end of the recess in the barrel portion
of the housing when the barrel is in a cocked position.
14. The tool according to claim 1 including a power plug received
in the breech end of said barrel for receiving a power load, said
barrel having a substantially smooth inner bore at the breech end
thereof, with said power plug being slidably received therewithin
and yieldably retained within said inner bore.
15. The tool according to claim 14 wherein said power plug includes
a circumferential groove, and spring retaining means mounted within
said groove for bearing against the inner bore of said barrel.
16. A powder actuated tool comprising:
a housing including a rearward breech portion and a forward barrel
portion;
a breechblock carried by said breech portion;
a barrel cradled by said barrel portion when said barrel is in a
first position in substantial alignment with said breechblock;
said barrel being pivotally engaged by the barrel portion of said
housing at a location toward the muzzle end of said barrel so that
the breech end of said barrel can be upraised away from said
breechblock into a loading position;
a captive piston longitudinally slidable within said barrel and
movable in response to explosion of a power load for driving a
fastener element into a workpiece at the muzzle end of said
barrel;
a piston retractor slidably carried by said barrel, said retractor
including a member for engaging said piston and a handle portion
which is manually engageable for moving said piston retractor and
said piston to a firing position toward the breech end of said
barrel; and
said tool further including a slot in said barrel at least adjacent
the breech end of said barrel, said barrel portion of said housing
including a muffler recess communicating with said slot in said
barrel when said barrel is in said first position.
17. A powder actuated tool comprising:
a housing including a rearward breech portion and a forward barrel
portion;
a breechblock carried by said breech portion;
a barrel cradled by said barrel portion when said barrel is in a
first position in substantial alignment with said breechblock;
said barrel being pivotally engaged by the barrel portion of said
housing at a location toward the muzzle end of said barrel so that
the breech end of said barrel can be upraised away from said
breechblock into a loading position;
a captive piston longitudinally slidable within said barrel and
movable in response to explosion of a power load for driving a
fastener element into a workpiece at the muzzle end of said
barrel;
a piston retractor slidably carried by said barrel, said retractor
including a member for engaging said piston and a handle portion
which is manually engageable for moving said piston retractor and
said piston to a firing position toward the breech end of said
barrel;
said barrel being provided with a longitudinal slot ending short of
the breech and muzzle ends of said barrel, and wherein said member
for engaging said piston extends through said longitudinal slot in
said barrel for engaging the head of said piston at the muzzle end
thereof; and
said barrel portion of said housing including a muffler recess
communicating with said longitudinal slot in said barrel when said
barrel is in said first position, wherein explosive gases from said
barrel travel through said slot and into said recess as the head of
said captive piston moves past the breech end of said longitudinal
slot, said gases further passing along said longitudinal slot
toward the muzzle end of said barrel, and a muffler in said muffler
recess.
18. A powder actuated tool comprising:
a housing including a rearward breech portion and a forward barrel
portion;
a breechblock carried by said breech portion and movable within
said breech portion of said housing from an uncocked to a fully
cocked or triggerable position;
said breechblock also carrying a triggerable firing pin;
trigger means for operating said firing pin when said breechblock
is in a cocked position;
a barrel cradled by said barrel portion of said housing, when said
barrel is in a first position in substantial alignment with said
breechblock;
a substantially horizontal pin member carried by said barrel
portion of said housing at a location toward the muzzle end of said
barrel, said horizontal pin member being positioned at the lower
side of said barrel;
a power plug positioned at the breech end of said barrel having a
chamber communicating with said barrel for receiving a power load
adapted to be fired by said firing pin;
a matching first slot in the underside of said barrel through which
said horizontal pin member extends, said first slot having a
longitudinal length along such barrel permitting longitudinal
sliding movement of the barrel for full engagement of the power
plug with the breechblock plus movement of the breechblock into a
cocked position as the barrel is urged toward a workpiece;
said barrel being pivotable about horizontal pin member so that the
breech end of said barrel including said power plug can be upraised
away from said breechblock into a loading position when the barrel
carrying the power plug is withdrawn from engagement with said
breechblock;
said barrel portion of said housing being provided with an arched
barrel retaining member proximate and above the location of said
horizontal pin member for substantially enclosing the upper side of
the barrel proximate said location, said arched barrel retaining
member having an inner surface semicircular in cross section for
substantially matching the upper side of the barrel in an upraised
position of the barrel for limiting the upward movement of the
barrel;
said barrel having a longitudinal second slot on the underside of
the barrel ending short of the breech and muzzle ends of said
barrel;
a captive piston longitudinally slidable within said barrel and
movable in response to an explosion of the power load in the power
plug for driving a fastener element;
a ring-shaped piston retractor slidably carried on the exterior of
said barrel, said retractor including a member for engaging said
piston through a longitudinal second slot in the barrel and a
handle portion which is manually engageable for moving said piston
retractor and said piston to a firing position toward the breech
end of said barrel; and
said barrel portion of said housing including a recess for
receiving said piston retractor toward the muzzle end of the barrel
portion when the barrel is in a position of alignment with the
breechblock such that said piston retractor does not interfere with
the movement of said captive piston in response to explosion of the
power load.
19. The tool according to claim 1 further including means for
preventing movement of said barrel into said first position until
said piston retractor is positioned far enough toward the muzzle
end of said barrel so that said member for engaging said piston
does not interfere with the movement of said piston in driving said
fastener element.
20. A powder actuated tool comprising:
a housing including a rearward breech portion and a forward barrel
portion;
a breechblock carried by said breech portion;
a barrel carried by said barrel portion and provided with a
longitudinal slot ending short of the breech and muzzle ends of
said barrel and through which explosive gases may escape from said
barrel;
a captive piston longitudinally slidable within said barrel and
movable in response to explosion of a power load for driving a
fastener element into a workpiece at the muzzle end of said
barrel;
said barrel portion of said housing being provided with a muffler
recess communicating with said slot near the breech end thereof for
receiving expansion of explosive gases from said barrel as the head
of the captive piston passes the breech end of said longitudinal
slot; and
a muffler in said muffler recess, wherein said muffler comprises a
roll of sheet metal located in said muffler recess.
21. A powder actuated tool comprising:
a housing including a rearward breech portion and a forward barrel
portion;
a breechblock carried by said breech portion;
a barrel carried by said barrel portion and provided with a
longitudinal slot ending short of the breech and muzzle ends of
said barrel and through which explosive gases may escape from said
barrel;
a captive piston longitudinally slidable within said barrel and
movable in response to explosion of a power load for driving a
fastener element into a workpiece at the muzzle end of said
barrel;
said barrel portion of said housing being provided with a muffler
recess communicating with said slot near the breech end thereof for
receiving expansion of explosive gases from said barrel as the head
of the captive piston passes the breech end of said longitudinal
slot;
a muffler in said recess; and
wherein said barrel portion of said housing includes a longitudinal
slot matching the breech end portion of said longitudinal slot in
said barrel, said muffler recess being closed except for the
longitudinal slot in the barrel portion of the housing
communicating therewith.
22. The tool according to claim 21 wherein said muffler comprises a
loosely coiled roll of sheet metal disposed in said recess with the
axis of the roll in a direction longitudinal of said tool.
23. The tool according to claim 22 wherein an outer end of said
roll is oriented upwardly so the outer entrance of the passage
between the convolutions of the roll opens toward said first
mentioned longitudinal slot.
Description
BACKGROUND OF THE INVENTION
Piston type explosively actuated tools, e.g. for driving fastener
devices into concrete or masonry walls, conventionally employ a
blank cartridge for providing the explosive gases applied to drive
the fastener device. Such a tool is cocked by pressure of the
muzzle against a workpiece or wall, resulting in movement of the
tool's breechblock into a firing position. A cartridge may then be
fired to force the captive piston through the barrel and drive the
fastener device. After firing, the barrel and the breechblock are
conventionally separated so that a new cartridge or power load may
be inserted, and the captive piston must be returned to its firing
position. Various constructions have been employed heretofore to
facilitate the loading and piston return operations. The barrel may
be rotated laterally to the side of the tool facilitating the
removal of the captive piston to a firing position and insertion of
a new load. Alternatively, the barrel may be movable longitudinally
forward of the tool for retraction of the piston and reloading. In
the case of these constructions and other similar arrangements, the
tool mechanism is apt to be quite complex and/or somewhat
unbalanced.
SUMMARY OF THE INVENTION
According to the present invention a powder actuated tool comprises
a housing including a rearward breech portion and a forward barrel
portion. The tool's barrel is cradled by the barrel portion when
the barrel is in a first position in substantial alignment with the
tool's breechblock. The barrel is pivotally engaged by the barrel
portion at a forward location so that the breech end of the barrel
can be pivotally upraised away from the breechblock into a loading
position. The tool further includes a piston retractor slidably
carried by the barrel, which retractor includes a member for
engaging the piston, and a handle portion which is manually
engageable for moving the piston retractor. The piston may be moved
thereby to a firing position toward the breech end of the barrel.
The retractor and housing construction prevent the barrel from
being pivotable back into firing position in alignment with the
breechblock until such retractor is moved forwardly out of the way
of the captive piston, allowing firing of the tool. The tool is
compact, and movement of component parts thereof is reduced to a
minimum.
It is accordingly an object of the present invention to provide an
improved powder actuated tool of the captive piston type which is
better balanced, more compact, and more easily manufactured.
It is a further object of the present invention to provide an
improved powder actuated tool of the captive piston type wherein
movement of component parts of the tool relative to the housing
thereof is minimized.
It is another object of the present invention to provide an
improved powder actuated tool of the captive piston type which is
quiet in operation.
It is another object of the present invention to provide an
improved powder actuated tool of the captive piston type which is
easy to operate.
The subject matter which I regard as my invention is particularly
pointed out and distinctly claimed in the concluding portion of
this specification. The invention, however, both as to organization
and method of operation, together with further advantages and
objects thereof, may best be understood by reference to the
following description taken in connection with the accompanying
drawings wherein like reference characters refer to like
element.
DRAWINGS
FIG. 1 is a longitudinal cross section of a powder actuated tool
according to the present invention;
FIG. 2 is a lateral cross section of the FIG. 1 tool taken at 2-2
in FIG. 1;
FIG. 3 is a lateral view of the cross section of the FIG. 1 tool
taken at 3-3 in FIG. 1;
FIG. 4 is a top view partially broken away in horizontal cross
section of the FIG. 1 tool; and
FIG. 5 is a side view of the FIG. 1 tool in a loading position
thereof.
DETAILED DESCRIPTION
Referring to the drawings, an explosively operated tool includes a
housing generally indicated at 10 including a forward portion 12
which may be designated as a barrel portion and a rearward portion
13 which may be designated as a breech portion. Rearward portion 13
includes a handle portion or grip 118. Barrel portion 12 is
semicircular in cross section and cradles barrel 14 in a first
position thereof wherein the barrel is aligned with the breechblock
16 positioned in the breech portion of the housing. Barrel 14
extends from muzzle 15 rearwardly to a power plug 18 received in
the breech end of the barrel. The barrel is provided with an inner
bore 20 within which a captive piston 22 is slidable, such piston
having an enlarged piston head 24 which slides within inner bore 20
and a ram or plunger 26 adapted to contact and drive the head of a
fastener device (not shown) into a workpiece at the left end of
muzzle 15. Enlarged head 24 of the captive piston includes a
rearward head portion 25 and a forward head portion 27 slidably
engaged with the inside of the barrel bore. Head portion 25 is
suitably provided with a piston ring or seal 32 therearound to
prevent excessive escape of gas past head 24.
Power plug 18 is slidably positioned in the breech end of barrel
bore 20 wherein the bore 20 is substantially smooth. The outer
circumference of power plug 18 is grooved and provided with a
spring retainer 34 which releasably secures the power plug at the
end of the barrel. Power plug 18 includes a chamber 36 for the
receiving a power charge or cartridge.
Breechblock 16 is longitudinally slidable within breech portion 13
of the housing and is recessed at 38 to receive power plug 18 in
the firing position thereof. Breechblock 16 slidably carries firing
pin holder 40 in turn carrying a tapered firing pin 42. The firing
pin holder is normally held in a retracted position relative to
breechblock 16 by sear 44 which is urged at this time by spring 46
to a location adjacent an edge 48 of the breechblock. When the tool
is cocked and the breechblock is forced to the right into a cocked
position against the spring bias of springs 50 and 52, sear 44 will
be aligned with trigger bar 54 and can be moved upwardly by trigger
bar 54. When breechblock 16 is in such cocked position, firing pin
spring 56 is compressed, and upward movement of the sear 44 causes
tapered firing pin 42 to be driven by spring 56 into tapered bore
58 in the breechblock 16. The firing pin 42 is adapted to project
through tapered bore 58 and strike a rim fire power load or the
like positioned in chamber 36. To fire the tool, trigger 60 is
compressed against spring 62 moving trigger bar 54 upward into
contact with sear 44, providing the latter is in cocked position.
Trigger bar 54 is carried in a vertical slot in the trigger and is
pivoted at 57, being maintained in alignment with the trigger by
internal spring 59. This mechanism permits the trigger bar 54 to
turn in a clockwise manner without damage in the event that the
tool is cocked with the trigger compressed. In this event, trigger
bar 54 will merely rotate in a clockwise sense as the side of sear
44 contacts the same. The tool may then not be fired until the
trigger is released and compressed again.
The barrel portion 12 of the housing, being semicircular in cross
section, is substantially channel-shaped and open upwardly where it
receives or cradles cylindrical barrel 14 in the first position of
the barrel in alignment with breechblock 16. The barrel 14 is
pivotally engaged by the barrel portion 12 of the housing at a
location towards the muzzle end of the barrel so that the breech
end of the barrel can be upraised away from the breechblock into
loading position. A substantially horizontal pin member 64 is
carried by the barrel portion of the housing at the aforementioned
location toward the muzzle end of the barrel, pin member 64 being
positioned at the lower side of the barrel and extending
transversely of the tool. A pin-matching longitudinal and
transverse slot 66 is located on the underside of barrel 14 through
which pin member 64 extends. Slot 66 has longitudinal length along
the barrel permitting longitudinal sliding movement of the barrel
for full engagement of power plug 18 within recess 38 of
breechblock 16, as well as movement of the breechblock 16 within
breech portion 13 of the housing into the aforementioned cocked
position. Thus, in FIG. 1, dimension X substantially corresponds at
least to the depth of penetration of power plug 18 within recess
38, and dimension Y corresponds to the movement of breechblock 16
further to the right to the cocked position wherein sear 44 is
above trigger bar 54. Thus, barrel 14, when moved to the left by
the distance X, will clear power plug 18 from breechblock 16, and
when moved to the right by the distance Y, will compress
breechblock 16 against the bias of springs 50 and 52 until sear 44
is over trigger bar 54.
The barrel portion 12 is provided with an arched barrel retaining
member 68 proximate and above the location of pin member 64. The
arched barrel retaining member 68 has an inner surface 70
semicircular in cross section which substantially matches the
cylindrical barrel 14, but which is angled upwardly and to the
right in FIG. 1. It will be apparent that barrel 14 may be moved to
the left by a distance X whereby power plug 18 clears breechblock
16, and then the breech end of the barrel may be moved upwardly
into a loading position, with the barrel pivoting substantially
around pin member 64. At this time, arched barred retaining member
68 limits the upward movement of the barrel, and when barrel 14 is
upraised as far as it will go, the inner surface 70 of the
retaining member substantially matches or cradles the upper side of
barrel 14. Retaining member 68 prevents the barrel from moving away
from pin member 64 by a distance as great as the diameter of pin
member 64 so that the barrel pivots substantially around pin member
64.
The barrel 14 is provided with a longitudinal slot 72 on the
underside thereof or the side adjacent barrel portion 12 of the
housing. This longitudinal slot does not extend the full length of
the barrel, but stops short of the breech and muzzle ends thereof
as illustrated. Thus, ring 32 on piston head 24 is located a
predetermined distance toward power plug 18 from the breech end of
slot 72 in the firing position of the piston. Also, the muzzle end
of slot 72 is proximate an insert or stop 74 located at the left
end or muzzle end of barrel 14.
The tool is provided with a piston retractor 76 carried by the
barrel. This piston retractor comprises a ring slidably mounted on
the exterior of the cylindrical barrel and fitted on the outside of
the barrel for easy slidable movement therealong. The retractor 76
is provided with a pair of horizontal handles 78 and 80 extending
horizontally outwardly from the retractor and just above the upper
edges of barrel portion 12 of the housing toward the muzzle end
thereof adjacent retaining member 68. Retractor 76 includes a
member 82 for engaging piston head portion 27 as when the piston 22
has moved toward the muzzle end of the barrel. As illustrated in
FIG. 5, barrel 14 may be upraised by pivoting around pin member 64,
after which either of the handles 78 or 80 may then be grasped to
move retractor 76 to the right. Member 82 engages head portion 27
as retractor 76 is moved to the right, bringing with it piston 22
until the piston is returned to the right end or breech end of
barrel 14. Then, retractor 76 is moved to the left-hand position
illustrated in the drawings, and indeed must be before barrel 14
can be returned to a position in alignment with breechblock 16. The
barrel portion 12 of the housing is cut down at 90 to receive
handles 78 and 80 only when retractor 76 is in its forwardmost
position. Moreover, the barrel portion of the housing includes
wedge-shaped recess 92 for receiving a lower wedge-shaped portion
94 of the retractor only when the retractor is returned to its
left-hand position. Therefore, the retractor 76 is removed out of
the way of the movement of piston 22 when the tool is in firing
position, thereby avoiding danger to the operator of the tool from
undesired movement of retractor 76 when the tool is fired.
Lower wedge-shaped portion 94 of retractor 76 carries member 82 in
a vertical slot 96 at the middle thereof, with the L-shaped member
82 being pivotally secured in the slot at its rearward end by means
of horizontal pin 98. A setscrew 100 in wedge-shaped portion 94 of
the retractor normally maintains member 82 in its operating
position shown. However, for disassembly of the tool, the retractor
76 is moved rearwardly toward the breech end of the upraised barrel
(as illustrated in FIG. 5) and the setscrew 100 may be loosened
whereby member 82 can be pivoted out of engagement with slot 72 in
the barrel. This allows the retractor 76 to be slid off the
barrel.
Piston 22 is provided with an ejector 86 which may protrude into
chamber 36 for ejecting power load or cartridge 88. The ejector 86
is tapered at its rearwardmost end where it may extend into chamber
36. This tapered configuration acts to guide explosion gases along
the chamber with minimum lateral deflection of such gases during
firing of the tool to prevent chamber erosion. This construction is
more fully described in the copending application of Yung Shing Hsu
entitled, "Chamber Erosion Preventing Powder Actuated Tool," Ser.
No. 675,140, filed Oct. 13, 1967, and assigned to the assignee of
the present invention.
In barrel portion 12 of the housing underneath barrel 14 and
between recess 92 and breechblock 16 there is located a muffler
recess 102 extending longitudinally of the barrel portion of the
housing. This muffler recess 102 is closed at the top by liner 104,
forming a part of the barrel portion of the housing, and secured by
screw 106, except for longitudinal slot 108 substantially matching
slot 72 in the barrel. Muffler recess 102 is desirably provided
with an internal muffler 110 here comprising a loosely coiled roll
of sheet metal. The axis of the roll of sheet metal is disposed in
recess 102 in a direction longitudinal of the tool, and the outer
end of the roll of sheet metal is oriented upwardly toward slot
108, so the outer entrance of the passage between convolutions of
the roll opens toward such slot to receive the explosion gases. The
explosion gases tend to take a path between convolutions of the
roll, this circuitous path tending to dissipate the energy
thereof.
As the tool is fired, a power load explodes and combustion
explosion gases enter bore 20 of barrel 14 forcing piston 22 to the
left. As head portion 25 moves past the breech end of slot 72,
these gases are vented along slot 72 and leave around retractor 76.
However, to diminish the report of the tool when fired, these gases
also expand into recess 102 and through the muffler convolutions.
Such gases enter and eventually leave recess 102 through slot
108.
The captive piston 22 is tapered between head 24 and ram or plunger
26, and this tapered portion and head 24 have a low hardness and
high ductility as compared with a high hardness and little or no
ductility of stop 74. The hard metal stop 74 includes a long
cylindrical entrance bore 114 and a frustoconical die portion 116.
The bore 114 serves to slidably receive the muzzle end of the
piston head 24, to the left of head portion 25, should the captive
piston 22 be overdriven so that ram 26 extends outwardly at the
left of muzzle 15. Should the piston thus be overdriven, piston
energy is dissipated by extruding, by frustoconical die portion
116, the tapered portion of the captive piston 22. The construction
allows the dissipation of energy of an overdriven piston without
damage to the captive piston inasmuch as bore 114 laterally
supports the captive piston during overdriving so as to prevent
bending of the head portion of the piston. This energy-dissipating
mechanism is further described and claimed in the copending
application of Yung Shing Hsu and Raymond V. Pomeroy, Ser. No.
796,980, filed Feb. 6, 1969.
In the general operation of the tool according to the present
invention, a fastener device is inserted in muzzle 15 and the user
grasps a handle portion or grip 118 and forces the fastener device
against a workpiece such as a masonry wall or the like. Urging the
tool against a workpiece brings about full contact between power
plug 18 and breechblock 16, and further urges the breechblock
rearwardly of the tool into a cocked position, i.e. placing sear 44
above trigger bar 54. The trigger 60 may now be compressed raising
sear 44 such that firing pin 42 is driven to the left exploding a
cartridge or power load in chamber 36. Explosive gases enter the
inner bore of barrel 14 behind the head 24 of the captive piston
driving the captive piston to the left and forcing the fastener
device into the workpiece. As hereinbefore mentioned, explosive
gases leave through slot 72 as the head portion 25 passes the
breech end of slot 72 from what may be considered a combustion
chamber inside the barrel to the right of slot 72 in FIG. 1. These
gases leave directly through the length of slot 72, but muffler
recess 102 provides an expansion chamber for these gases which pass
through muffler 110 whereby the noise of the explosion is reduced.
The muffler breaks up the gas to muffle the sound.
To reload the tool, and return the captive piston to firing
position, the barrel is moved to the left in FIG. 1 by a distance,
X, and the breech end thereof is pivoted upwardly around horizontal
pin member 64. In practice, the tool may be grasped by means of
grip 118 and snapped in a downward direction causing the barrel 14
to lower and pivot around horizontal pin member 64 so that the
breech end of the barrel including power plug 18 tilts away from
the breechblock. With the barrel in the out-tilted position, a
handle 78 or 80 of the retractor 76 is grasped and pulled
rearwardly. As a result, member 82 engages the outer edge of head
portion 27 pulling the piston 22 to the right, back to a firing
position. The movement of the piston, as head portion 25 reaches
the breech end of slot 72, may force shell or power load 88 from
chamber 36. If ejection is not accomplished by air pressure, the
ejector contacts the cartridge for forcibly removing the same. The
retractor is then returned to its forwardmost position by means of
handles 78 or 80, and a new cartridge or power load is inserted in
chamber 36. The barrel 14 is then pivoted back into alignment with
breechblock 16 for the next operation. It is thus seen that the
operation of the tool according to the present invention is simple
and construction thereof is compact. The tool retains a compact and
balanced construction, and, since the weight of the tool is well
balanced, the tool is easy to handle.
It should be noted that when the tool is urged against a workpiece,
retractor 76 is automatically urged to the rear of wedge-shaped
recess 92, assuming the retractor is not already in such position.
With the tool forced against a workpiece, the retractor 76 is held
in position between the breech end of recess 92 and the muzzle end
of slot 72. The muzzle end of slot 72 engages the inwardly
extending portion of member 82. Therefore, when the tool is fired,
no undesired movement of retractor 76 will take place. It should be
noted that even if the piston 22 should be overdriven into stop 74,
the edge of head portion 27 will not strike or move member 82 with
the retractor 76 in its locked position between the edges of recess
92 and slot 72.
While I have shown and described a preferred embodiment of my
invention, it will be apparent to those skilled in the art that
many changes and modifications may be made without departing from
my invention in its broader aspects. I therefore intend the
appended claims to cover all such changes and modifications as fall
within the true spirit and scope of my invention.
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