U.S. patent number 3,572,572 [Application Number 04/843,665] was granted by the patent office on 1971-03-30 for fluid pressure operated fastener driving device.
This patent grant is currently assigned to Textron Inc.. Invention is credited to Walter G. Lemos, Peter A. Readyhough.
United States Patent |
3,572,572 |
Readyhough , et al. |
March 30, 1971 |
FLUID PRESSURE OPERATED FASTENER DRIVING DEVICE
Abstract
A fastener driving device having a fluid pressure operated
system for moving a fastener driving element through repeated
cycles each of which includes a drive stroke during which a
fastener is driven and a return stroke, the main control valve for
effecting the cycle of operation being moved by pilot pressure
within a pilot chamber acting on a pilot piston forming part of the
main control valve, the pilot chamber being communicated with
reservoir pressure through a restricted orifice and the exhaust of
the pilot chamber being under the control of an auto-fire valve
operable to prevent exhaust of the pilot pressure in response to
the establishment of a pressure signal in the return plenum chamber
at the end of the drive stroke and operable to permit exhaust of
the pilot pressure in response to a low pressure signal from the
return plenum chamber toward the end of the return stroke. The
device also includes an interlock lever pivoted intermediate its
ends to the depending stem of the actuating valve and having its
ends connected respectively to the trigger member and a motion
transmitting member, which, in turn, is connected through a spring
to the work contacting member so as to prevent undesired movement
of the actuating valve into its closed position as a result of
recoil movement of the device when the fastener driving element
completes its drive stroke.
Inventors: |
Readyhough; Peter A.
(Barrington, RI), Lemos; Walter G. (Riverside, RI) |
Assignee: |
Textron Inc., (Providence,
RI)
|
Family
ID: |
25290655 |
Appl.
No.: |
04/843,665 |
Filed: |
July 22, 1969 |
Current U.S.
Class: |
227/8;
227/130 |
Current CPC
Class: |
B25C
1/008 (20130101); B25C 1/041 (20130101) |
Current International
Class: |
B25C
1/04 (20060101); B25C 1/00 (20060101); B27f
007/06 () |
Field of
Search: |
;227/7,8,130 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Custer, Jr.; Granville Y.
Claims
We claim:
1. A fastener driving device comprising:
a housing having means defining a pressure reservoir for receiving
and containing fluid under pressure supplied thereto from a source
of fluid under pressure;
means defining a drive track for receiving successive fasteners to
be driven from a supply of such fasteners fed thereto;
fastener driving means carried by said housing for movement from a
fastener receiving position through said drive track in a drive
stroke into a fastener driven position and from said fastener
driven position through a return stroke into said fastener
receiving position;
means within said housing defining a driving pressure chamber
disposed in fluid communicating relation to said fastener driving
means;
main control valve means movable between a first position
communicating said driving chamber with the atmosphere and closing
communication between said driving chamber and said reservoir and a
second position communicating said driving chamber with said
reservoir and closing off communication of said driving chamber
with the atmosphere so that said fastener driving means will be
moved through said drive stroke in response to the movement of said
main valve means into said second position and through said return
stroke in response to the movement of said main valve means into
said first position;
means defining a pilot pressure chamber;
a pilot pressure actuated member disposed in pressure communicating
relation with said pilot chamber for movement from a first position
into a first position in response to the communication of pilot
pressure within said pilot chamber and from said second position
into said first position in response to the exhaust of said pilot
chamber to atmosphere;
means operable in response to the movement of said pilot pressure
actuated member into said first position for effecting movement of
said main valve means into said second position and operable in
response to the movement of said pilot pressure actuated member
into said second position for effecting movement of said main valve
means into said first position;
means defining a restricted orifice continuously communicating said
reservoir with said pilot chamber;
means defining an exhaust outlet for said pilot chamber of a size
greater than said restricted orifice;
manually operable valve means mounted for movement between a
normally closed position preventing communication of said pilot
pressure chamber with said exhaust outlet and a manually actuated
opened position communicating said pilot chamber with said exhaust
outlet;
auto-fire valve means arranged in series with said manually
operable valve means between said pilot chamber and said exhaust
outlet for controlling communication of said pilot chamber and said
exhaust outlet when said manually operable valve means is disposed
in said manually actuated opened position;
said auto-fire valve means including a valve member mounted for
movement between an opened position communicating said pilot
pressure chamber with said exhaust outlet when said manually
operated valve means is disposed in said manually actuated opened
position and a closed position preventing communication of said
pilot chamber with said exhaust outlet when said manually operated
valve means is disposed in said manually actuated opened
position;
first pressure surface means operatively associated with said valve
member and disposed in pressure communicating relation with said
pilot chamber operable to bias said valve member into said opened
position in response to the communication of pressure in said pilot
chamber therewith;
second pressure surface means operatively associated with said
valve member of an effective area sufficiently greater than the
effective area of said first pressure surface means to bias said
valve member into said closed position in response to the
communication of signal pressure therewith with a force greater
than the force acting on said first pressure surface means biasing
said valve member into said opened position; and
means for communicating with said second pressure surface means a
signal pressure, separate from said pilot pressure, established as
a result of the movement of said pilot pressure actuated member
into said second position, which signal pressure is dissipated as a
result of the movement of said pilot pressure actuated member into
said first position so that when said manually operable valve means
is disposed in said manually actuated opened position said autofire
valve means is operable to effect movement of said fastener driving
means through continuous drive stroke and return stroke cycles
until said manually operable valve means is moved into said closed
position.
2. A fastener driving device as defined in claim 1 including:
means defining a return plenum chamber;
means for charging said return plenum chamber with fluid under
pressure when said fastener driving means has moved through its
drive stroke;
means for communicating the fluid pressure charge of said plenum
chamber with said fastener driving means to effect the return
stroke thereof in response to the movement of said main valve means
into its first position;
means for exhausting the fluid pressure charge of said plenum
chamber when said fastener driving means has completed its return
stroke; and
wherein said signal pressure communicating means include means
defining a passageway communicating said plenum chamber with said
second pressure surface means so that the fluid pressure charge of
said plenum chamber constitutes said signal pressure.
3. A fastener driving device as defined in claim 2 including a flow
restricting member adjustably mounted within said passageway for
determining the rate at which said signal pressure is communicated
with and dissipated from said second pressure surface means to
thereby determine the rate of the continuous drive stroke and
return stroke cycles.
4. A fastener driving device as defined in claim 3 wherein said
valve member comprises a flexible annular diaphragm mounted with
its periphery in confined relation, one surface of said diaphragm
defined by the peripheral confinement thereof constituting said
second pressure surface means, a central portion of the opposite
surface of said diaphragm being engageable with an annular valve
seat and constituting said first pressure surface means.
5. A fastener driving device as defined in claim 1 wherein said
driving chamber defining means comprises a cylinder, said housing
including a main casting having a bore extending downwardly from
the upper end portion thereof receiving said cylinder, and a cap
assembly fixedly secured to said main casting above said cylinder,
said auto-fire valve means being carried by said cap assembly.
6. A fastener driving device as defined in claim 5 wherein said
means for effecting movement of said main valve means in response
to the movement of said pilot pressure actuated member comprises an
elongated member mounted within said housing with its longitudinal
axis parallel with the axis of said cylinder, said elongated member
having a piston portion formed integrally on the lower end thereof
which constitutes said pilot pressure actuated member, the lower
surface of said piston portion being in communication with said
pilot chamber and the upper surface thereof being in communication
with said reservoir, said main valve means including an annular
inlet valve element of an effective diameter less than said piston
portion carried by said elongated member in upwardly spaced
concentric relation to said piston portion and having an upwardly
facing annular surface for engaging an annular valve seat fixed
with respect to said housing in a position between said reservoir
and the upper end of said cylinder and an annular exhaust valve
element of a diameter less than said inlet valve element carried by
said elongated member in upwardly spaced concentric relation to
said inlet valve element for engaging an annular valve seat fixed
with respect to said housing in a position between the upper end of
said cylinder and a portion of said cap assembly having an exhaust
opening therein.
7. A fastener driving device as defined in claim 1 wherein said
housing includes a handle portion arranged to be gripped by the
hand of an operator and a nose piece defining operatively fixed
surface means engageable with a workpiece when said housing is
manually moved by the operator into operative relation with a
workpiece;
said fluid pressure operated fastener driving means includes a
fastener driving element having a fastener engaging end spaced
outwardly beyond said work engaging surface means when said
fastener driving means is disposed in said fastener driven
position;
a work contacting member carried by said housing for limited
movement between a normal inoperative position and an operative
position, said work contacting member including work engaging
surface means disposed outwardly of said fixed surface means when
said work contacting member is disposed in said inoperative
position a predetermined distance beyond the position of said
fastener driving element when the latter is disposed in said
fastener driven position and in alignment with said fixed surface
means when said work contacting member is in said operative
position;
a motion transmitting member carried by said housing for limited
movement between a normally inoperative position and an operative
position;
spring means operatively connected between said members for
transmitting the movement of said work contacting member from said
inoperative position generally through said predetermined distance
to said motion transmitting member to move the latter from said
inoperative position to said operative position and for yielding
during the remainder of the movement of said work contacting member
into said operative position while said motion transmitting member
remains immobile;
a trigger carried by said housing in a normal limited inoperative
position operable to be engaged by a finger of the operator when
said handle portion is manually gripped for manual movement into a
limited operative position; and
interlock means operatively connected between said trigger and said
motion transmitting member for effecting movement of said manually
operable valve means into the opened position thereof in response
(1) to the simultaneous movement of said motion transmitting member
and said trigger into their operative position, (2) to the movement
of said motion transmitting member into its operative position when
said trigger is in its operative position or (3) to the movement of
said trigger into its operative position when said motion
transmitting member is in its operative position, the yielding
movement of said spring means preventing undesired movement of said
manually operable valve means into said closed position by a
relative movement of said work contacting member away from its
operative position as a result of a movement of the housing away
from the work piece against the manual pressure of the operator on
the handle portion by the action of the fastener driving element
moving into said fastener driven position.
8. A fastener driving device as defined in claim 7 wherein said
manually operable valve means includes an actuating member having a
depending end portion and wherein said interlock means includes an
elongated interlock member, means pivotally interconnecting said
interlock member intermediate its ends with the depending end
portion of said actuating member, means connecting one end of said
interlock member with said motion transmitting member for movement
thereby in response to the movement of said work contacting member
from said inoperative position to said operative position, and
means for connecting the other end of said interlock member with
said trigger for movement in response to the movement of said
trigger from said inoperative position to said operative
position.
9. A fastener driving device comprising a housing defining a handle
portion arranged to be gripped by the hand of an operator and a
nose piece defining operatively fixed surface means engageable with
a workpiece when said housing is manually moved by the operator
into operative relation with a workpiece;
fluid pressure operated fastener driving means including a fastener
driving element carried by said housing for movement from a
fastener receiving position through a drive stroke into a fastener
driven position and from said fastener driven position through a
return stroke into said fastener receiving position;
manually operable valve means normally disposed in an inoperative
position movable into an operative position to actuate said fluid
pressure operated means;
a work contacting member carried by said housing for a limited
movement between a normal inoperative position and an operative
position, said work contacting member including work engaging
surface means disposed outwardly of said fixed surface means when
said work contacting member is disposed in said inoperative
position a predetermined distance beyond the position of said
fastener driving element when the latter is disposed in said
fastener driven position and in alignment with said fixed surface
means when said work contacting member is in said operative
position;
a motion transmitting member carried by said housing for limited
movement between a normally inoperative position and an operative
position;
spring means operatively connected between said members for
transmitting the movement of said work contacting member from said
inoperative position generally through said predetermined distance
to said motion transmitting member to move the latter from said
inoperative position to said operative position and for yielding
during the remainder of the movement of said work contacting member
into said inoperative position while said motion transmitting
member remains immobile;
a trigger carried by said housing in a normal limited inoperative
position operable to be engaged by a finger of the operator when
said handle portion is manually gripped for manual movement into a
limited operative position; and
interlock means operatively connected between said trigger and said
motion transmitting member for effecting movement of said valve
means into the operative position thereof in response (1) to the
simultaneous movement of said motion transmitting member and said
trigger into their operative positions, (2) to the movement of said
motion transmitting member into its operative position when said
trigger is in its operative position or (3) to the movement of said
trigger into its operative position when said motion transmitting
member is in its operative position, the yielding movement of said
spring means preventing undesired movement of said valve means into
said inoperative position by a relative movement of said work
contacting member away from its operative position as a result of a
movement of the housing away from the work piece against the manual
pressure of the operator on the handle portion.
10. A fastener driving device as defined in claim 9 wherein said
work contacting member includes a vertically extending portion
mounted adjacent said nose piece, said motion transmitting member
includes a vertically extending portion disposed above said work
contacting member portion and said spring means comprises a coil
spring and means for mounting said coil spring between the
vertically extending portions of said members.
11. A fastener driving device as defined in claim 10 wherein said
coil spring mounting means includes a tab bent outwardly from each
vertically extending portion engaging an end of said coil spring
and a guide rod extending through said tabs and said coil
spring.
12. A fastener driving device as defined in claim 11 including a
housing plate secured to said nose piece generally enclosing said
vertically extending portions, said tabs, said guide rod and said
coil spring.
13. A fastener driving device as defined in claim 12 wherein said
motion transmitting member further includes a second portion
extending laterally outwardly through said housing place, a third
portion extending horizontally rearwardly from said second portion,
a fourth portion extending upwardly from said second portion, a
fifth portion extending laterally from said fourth portion and a
sixth portion extending upwardly from said fifth portion, a second
coil spring disposed in surrounding relation to said sixth portion
having its ends operatively engaged with said fifth portion and
said housing respectively so as to bias said motion transmitting
member into its inoperative position.
14. A fastener driving device as defined in claim 13 wherein said
manually operable valve means includes an actuating member having a
depending end portion and wherein said interlock means includes an
elongated interlock member, means pivotally interconnecting said
interlock member intermediate its ends with the depending end
portion of said actuating member, a lost motion connection between
one end of said interlock member and the upper end of the fifth
portion of said motion transmitting member and a lost motion
connection between the other end of said interlock member and said
trigger.
15. In a fastener driving device of the type including a housing,
fluid pressure operated fastener driving means carried by said
housing for movement through a fastener driving stroke and a return
stroke, valve means including a depending actuating member carried
by said housing for movement from a normally inoperative position
into an operative position for effecting the operation of said
fluid pressure operated means through said fastener driving stroke,
a work contacting member carried by said housing for movement from
an inoperative position to an operative position in response to the
movement of said apparatus into cooperating engagement with a work
piece, a trigger member carried by said housing for manual movement
from an inoperative position to an operative position, and
interlock means for effecting movement of said valve means into the
operative position thereof in response (1) to the simultaneous
movement of said work contacting and said trigger members into
their operative positions, (2) to the movement of said work
contacting member into its operative position when said trigger
member is in its operative position or (3) to the movement of said
trigger member into its operative position when said work
contacting member is in its operative position, the improvement
which comprises said interlock means including an elongated
interlock member, means pivotally interconnecting said interlock
member intermediate its ends with the depending end portion of said
valve means actuating member, means connecting one end of said
interlock member with said work contacting member for movement
thereby in response to the movement of said work contacting member
from said inoperative position to said operative position, and
means for connecting the other end of said interlock member with
said trigger member for movement in response to the movement of
said trigger member from said inoperative position to said
operative position.
16. A fastener driving device comprising a housing defining a
handle portion arranged to be gripped by the hand of an operator
and a nose piece defining operatively fixed surface means
engageable with a workpiece when said housing is manually moved by
the operator into operative relation with a workpiece;
fluid pressure operated fastener driving means including a fastener
driving element carried by said housing for movement from a
fastener receiving position through a drive stroke into a fastener
driven position and from said fastener driven position through a
return stroke into said fastener receiving position;
manually operable valve means normally disposed in an inoperative
position movable into an operative position to actuate said fluid
pressure operated means;
a work contacting member carried by said housing for limited
movement between a normal inoperative position and an operative
position, said work contacting member including work engaging
surface means disposed outwardly of said fixed surface means when
said work contacting member is disposed in said inoperative
position a predetermined distance beyond the position of said
fastener driving element when the latter is disposed in said
fastener driven position and in alignment with said fixed surface
means when said work contacting member is in said operative
position;
a motion transmitting member carried by said housing for limited
movement between a normally inoperative position and an operative
position;
spring means operatively connected between said members for
transmitting the movement of said work contacting member from said
inoperative position generally through said predetermined distance
to said motion transmitting member to move the latter from said
inoperative position to said operative position and for yielding
during the remainder of the movement of said work contacting member
into said inoperative position while said motion transmitting
member remains immobile; and
means operatively connected with said motion transmitting member
for effecting movement of said valve means into the operative
position thereof when said motion transmitting member is disposed
in its operative position.
Description
This invention relates to fastener driving devices and more
particularly to fastener driving devices of the type which are
operated by air under pressure.
Fluid pressure operated fastener driving devices are well known in
the art. The simplest form of a device of this type is provided
with a trigger which, when depressed by the finger of the operator,
actuates the fluid pressure system to move the fastener driving
element through its drive stroke during which a fastener fed from
the fastener magazine is engaged and moved outwardly into the
workpiece. When the trigger is released by the operator, the fluid
pressure system is operated to move the fastener driving element
through its return stroke.
A disadvantage of a simple trigger actuation is that the device is
capable of being fired when out of operative relationship with the
workpiece, thus presenting the possibility of a fastener becoming a
projectile which can cause injury to personnel and the like. In
order to overcome this disadvantage, it has been proposed to
provide a work contacting member or contact trip which is
interlocked with the trigger such that it is necessary for the
operator to both depress the trigger with his finger and to move
the entire device into engagement with the workpiece before
actuation can occur.
Various interlocking arrangements have been provided which afford
the operator essentially three different types or modes of
actuation: first, single firing in which the operator simple moves
the device into contact with the work and depresses the trigger and
after the drive stroke has been completed, lifts the device away
from the workpiece and releases the trigger; second, bump firing in
which the operator continuously depresses the trigger and by
successively moving the device into and out of engagement with the
workpiece at specified locations effects firing solely by the
movement of the work contacting member; and third, drag firing in
which the operator moves the device into contact with the work to
actuate the work contacting member and then moves the device along
the work in continuous contact therewith while successively
depressing and releasing the trigger to fire the device at spaced
locations along the work.
In recent years it has been found that in certain applications
where repeated firing is desired, the time required to operate
pneumatic fastener driving devices even when bump or drag fired can
be reduced by modifying the pneumatic system so that it will
automatically recycle, so long as the trigger is depressed and the
work contacting member (when provided) is in engagement with the
workpiece. This mode of operation has been called "auto-fire."
In some instances it is desirable to provide the fastener driving
element with a length sufficient to extend outwardly beyond the
work contacting surface of the nose piece when the fastener driving
element has reached the end of its drive stroke. A relationship of
this type has, in the past, actually aided in the bump firing
operation in that it has the effect of tending to move the entire
device against the manual pressure of the operator away from the
workpiece, thus insuring that the trigger valve will be moved to
its inoperative position to commence the return stroke immediately
after the drive stroke. However, where the pneumatic system of the
device is modified to automatically recycle, the movement of the
actuating valve into its inoperative position has the effect of
stopping the automatic recycle. Consequently, under auto-fire
actuation the provision of a work contacting member which may allow
the actuating valve to move into its inoperative position as a
result of recoil of the device following the completion of the
drive stroke can have the effect of disrupting the automatic cycle
of the device.
Accordingly, it is an object of the present invention to provide a
fastener driving device of the type described capable of being
operated in single fire, bump fire, drag fire and auto-fire fashion
and which prevents disruption of the auto-fire cycle due to recoil
while at the same time maintaining an overextended length of the
fastener driving element sufficient to insure full penetration of
the fasteners into the workpiece.
This result is achieved in accordance with the principles of the
present invention by providing a motion transmitting mechanism
between the work contacting member and trigger valve which includes
a motion transmitting member and a spring means between the work
transmitting member and the work contacting member. The work
contacting member extends outwardly beyond the end of the fastener
driving element when the latter is in its fastener driven position
a predetermined distance and the spring means is arranged to
transmit the inward movement of the work contacting member
generally through the predetermined distance to the motion
transmitting member, subsequent inward movement of the work
contacting member resulting solely in the yielding movement of the
spring without a corresponding movement to the motion transmitting
member. The movement of the motion transmitting member is utilized,
in conjunction with the movement of the trigger to effect movement
of an interlock member which, in turn, serves to move the actuating
valve into its operative position. In this way, when the fastener
driving element moves through its drive stroke any tendency for the
device to move away from the workpiece because of the extended
length of the fastener driving element will simply result in a
movement of the spring and work contacting member without an
attendant movement of the motion transmitting member thus insuring
that the trigger valve means will be maintained in its operative
position for auto-fire operation by the pneumatic system.
A further object of the present invention is the provision of a
fluid pressure operated fastener driving device of the type
described having an improved pneumatic system for effecting
autofire.
Another object of the present invention is the provision of a fluid
pressure operated fastener driving device of the type described
having an improved mechanical interlock linkage for effecting
movement of the actuating valve into its operative position in
response (1) to the simultaneous actuation of the work contacting
member and trigger, (2) to the actuating of the work contacting
member when the trigger is actuated, or (3) to the actuation of the
trigger when the work contacting member is actuated.
A further object of the present invention is the provision of a
fluid pressure operated fastener driving device of the type
described which is simple in construction, efficient in operation
and economical to manufacture and maintain.
These and other objects of the present invention will be come more
apparent during the course of the following detailed description
and appended claims. The invention may best be understood with
reference to the accompanying drawings wherein an illustrative
embodiment is shown.
In the drawings:
FIG. 1 is a side elevational view of a fluid pressure operated
fastener driving device embodying the principles of the present
invention with certain parts shown in vertical section, the trigger
and work contacting member being illustrated in their normal
inoperative position;
FIG. 2 is a view similar to FIG. 1 showing the trigger and work
contacting member in their operative position and the fastener
driving means in its fastener driven position at the end of the
work stroke;
FIG. 3 is a fragmentary side elevational view of the device
illustrating the side thereof opposite to that shown in FIGS. 1 and
2;
FIG. 4 is a sectional view taken along the line 4-4 of FIG. 1;
FIG. 5 is a sectional view taken along the line 5-5 of FIG. 1;
FIG. 6 is a fragmentary sectional view of the manually controlled
actuating mechanism showing the position of the parts when the work
contacting member is disposed in its operative position and the
trigger member is disposed in its inoperative position; and
FIG. 7 is a fragmentary sectional view of the manually controlled
actuating mechanism showing the position of the parts when the work
contacting member is disposed in its inoperative position and the
trigger member is disposed in its operative position.
Referring now more particularly to the drawings, there is shown
therein a fluid pressure operated fastener driving device,
generally indicated at 10, embodying the principles of the present
invention.
As a convenience, the device 10 will be described in an orientation
operable to drive fasteners downwardly into a horizontal workpiece,
although it will be understood that the device is not limited to
such application but can be used to drive fasteners into vertical
workpieces or beneath horizontal workpieces, as well as workpieces
of any other orientation. Consequently, it will be understood that
terms such as "vertical," "horizontal," "above," "below,"
"forward," "rearward," etc. as used herein are to be construed in
their relative sense.
The device 10 includes a housing 12 to which is connected by
suitable conventional means a magazine assembly, generally
indicated at 14, having a nose piece assembly, generally indicated
at 16, fixedly connected at its forward end to the magazine
assembly and defining a vertically extending drive track into which
successive fasteners are fed horizontally from the magazine
assembly in accordance with conventional practice. It will be
understood that the magazine assembly 14 may be of any known
construction for feeding successive fasteners of any known
construction as, for example, staples, T-head nails, pins, headed
nails and the like.
Mounted for movement through the drive track 18 is an elongated
fastener driving element 20 having a cross-sectional configuration
compatible with the cross-sectional configuration of the drive
track and the particular fastener which is fed thereto from the
magazine assembly 14. The housing 12 contains a fluid pressure
operated system, generally indicated at 22, for effecting movement
of the fastener driving element between fastener receiving and
fastener driven positions, through an operative cycle or cycles
under the manual control of an operator by an actuating mechanism,
generally indicated at 24.
The operating cycle of the fastener driving element 20 includes a
vertically downward drive stroke from the fastener receiving
position to the fastener driven position and a vertically upward
return stroke from the fastener driven position to the fastener
receiving position. During the drive stroke, a fastener, such as
designated by the reference character F in FIGS. 1 and 2, which has
been fed into the drive track 18 from the magazine assembly 14
prior to the commencement of the drive stroke is engaged by the
lower end of the fastener driving element and moved downwardly
through the drive track and outwardly therefrom into a workpiece
such as the workpiece designated by the reference character W in
FIG. 2. Thus, during each operating cycle of the fastener driving
element 20 a fastener F is fed to the drive track and driven
outwardly thereof by the fastener driving element into the
workpiece W.
The fluid pressure operated system 22 includes a fluid pressure
reservoir 26 defined by a generally horizontally extending hollow
handle portion 28 forming an integral part of a main casting of the
housing 12. In accordance with conventional practice, the rearward
end of the reservoir is provided with a fitting (not shown) adapted
to be connected with one end of a pressure line, the opposite end
of which is connected with a suitable source of fluid under
pressure as, for example, a compressor or the like (also not
shown).
The main casting of the housing 12 also includes a generally
vertically extending forward portion 30 within which a vertically
extending cylinder 32 is mounted. The cylinder 32 defines a
vertically extending cylindrical drive chamber 34 within which a
drive piston assembly 36 is slidably mounted. As best shown in
FIGS. 1 and 2, the drive piston assembly 36 is in the form of a
generally inverted cup-shaped piston member 38, having an annular
flange 40 extending radially outwardly from the lower end thereof.
The periphery of the annular flange is suitably grooved to receive
an O-ring seal 42 which slidably sealingly engages the interior
periphery of the cylinder 32. The interior central portion of the
piston member 38 has a downwardly facing annular recess formed
therein for receiving a disc-shaped pad 44, the central lower
portion of which is adapted to engage the upper end of the fastener
driving element 20. At a position spaced below the upper end of the
fastener driving element 20, the latter is apertured to receive
therethrough a pin 46 which, in turn, seats within an upwardly
facing recess 48 formed in a generally cylindrical pad 50. The
upper periphery of the pad includes a radially extending flange
portion 52 which is adapted to engage within a correspondingly
shaped annular recess 54 formed in the interior periphery of the
piston member 38.
The upper end of the drive chamber 34 is arranged to be alternately
communicated with the fluid under pressure within the reservoir 26
and with the atmosphere by the action of a main control valve,
generally indicated at 56. To this end, the main casting of the
housing 12 has a vertical bore 58 extending downwardly into
communication with the reservoir 26 in parallel relation to the
cylinder 32. A counterbore 60 is formed in the upper end of the
bore 58 and an annular valve insert 62 is engaged within both the
bore 58 and counterbore 60. The exterior periphery of the insert is
sealed with respect to the bore and counterbore by any suitable
means, such as an O-ring 64, as shown in FIGS. 1 and 2. The valve
insert 62 provides a lower relatively large inlet opening 66, the
lower end of which communicates with the reservoir 26 and provides
an annular valve seat 68 surrounding the inlet opening.
The upper end of the inlet opening 66 communicates with the central
interior of the valve insert 62 which has a lateral passage 70
extending horizontally therefrom which communicates with the upper
end of the drive chamber 34 through a correspondingly shaped
lateral passage 72 formed in the main casting of the housing 12.
The upper end of the valve insert 62 is formed with a relatively
small exhaust or outlet opening 74 concentric with the inlet
opening 66 which communicates at its lower end with the central
interior of the valve insert 62.
The main control valve 56 includes a main valve member 76 having an
annular flange 78 extending radially outwardly therefrom for
receiving an annular inlet valve element 80. The valve element 80
is retained in engagement with the flange 78 by a frustoconical
portion 82 having a valve stem portion 84 extending upwardly
therefrom. Formed on the upper end of the valve stem portion 84 is
an enlarged portion of a size to engage within the exhaust opening
84 having its exterior periphery formed with an annular groove to
receive an annular exhaust valve element 86 in the form of an
O-ring or the like.
The main control valve member 76 is mounted within the housing 12
for vertical reciprocatory movement between two limiting positions.
As shown in FIG. 1 in its upper limiting position, the inlet valve
element 80 engages the valve seat 68 closing off communication of
the fluid under pressure within the reservoir 26 from the drive
chamber 34, the exhaust valve element 86 extending above the
exhaust outlet 74 thus communicating the driving chamber with the
atmosphere in a manner hereinafter more fully described. As shown
in FIG. 2, when the main valve member 76 is in its lower limiting
position, the inlet valve element 80 is disposed away from the
valve seat 68 thus communicating the fluid under pressure within
the reservoir 26 with the drive chamber 34, the exhaust valve
element 86 being in sealing relation with the exhaust outlet
74.
The main valve member 76 is moved between those limiting positions
by a pilot piston 88 formed integrally on the lower end of the
valve member 76 and mounted within a cylindrical pilot pressure
chamber 90 formed in the adjacent portion of the main casting of
the housing 12. The pilot pressure within the pilot chamber 90 is
controlled by a manually actuated or trigger valve member 92 which
is normally biased, as by a coil spring 94 into a position
preventing the exhaust of pilot pressure from the chamber. Pilot
pressure for the pilot chamber 90 is obtained directly from the
reservoir 26 as by a restricted orifice 96 extending through the
periphery of the valve member 76.
Since the pilot piston 88 is of a diameter greater than the
effective diameter of the valve element 80 (the greatest diameter
dimension which contacts valve seat 68) and reservoir pressure acts
in opposite directions upon both of these diameters at all times,
pilot pressure acting on the piston 88 normally will effect
movement of the main valve into its uppermost limiting position,
closing off communication of the reservoir with the drive
chamber.
The trigger valve member 92 forms a part of the manually controlled
actuating mechanism 24 and is adapted to be moved from its normal
position closing off the exhaust of the pilot pressure within the
pilot chamber to an operative position communicating the pilot
chamber with the atmosphere by the operation of the manually
controlled actuating mechanism 24 in a manner to be hereinafter
more fully described.
As best shown in FIGS. 1 and 2, the actuating valve 92 is
preferably in the form of a cylindrical actuating member disposed
within a bore 98 formed in the main casting of the housing 12
concentric with the main control valve 56. An O-ring seal 100 is
mounted in an appropriate annular groove formed in the exterior
periphery of the cylindrical valve member for sealing engagement
with the bore 98. Formed in the upper end of the bore 98 is a
counterbore 102 surrounding the upper end of which is an upwardly
facing valve seat 104. The actuating valve 92 includes an exhaust
valve element 106 which is preferably in the form of an annular
seal of a size to engage the valve seat 104.
The counterbore 102 forms a part of an exhaust passageway for the
pilot chamber 90 which is controlled by an auto-fire valve,
generally indicated at 108, for alternatively opening and closing
the exhaust passageway to alternatively pressurize and exhaust the
pilot pressure to effect repeated movements of the main control
valve 56 between its limiting positions so long as the actuating
valve 92 is disposed in its operative position. To this end, the
exhaust passageway includes a lateral bore 110, which communicates
at one end with the lower end of the counterbore 102 and at its
other end with a vertical bore 112 formed in the main casting of
the housing 12. The upper end of the bore 112 communicates with a
registering opening formed in a lower gasket 114 which is
preferably of resilient material such as rubber, plastic or the
like. As best shown in FIGS. 1 and 2, the gasket 114 is mounted on
the upper end of the main casting of the housing 12, throughout the
periphery thereof, and in engagement with a shoulder 116 formed on
the upper, outer periphery of the valve insert 62.
Mounted above the lower gasket 114, in abutting relation thereto,
is a plate 118 having an opening, similar to the opening in the
gasket 114 which registers with the upper end of the vertical bore
112. Mounted in abutting relation to the upper surface of the plate
118 is an upper gasket 120, the entire sandwich including the upper
and lower gaskets 114 and 120 and the intermediate plate 118 being
detachably secured to the main casting by a cap member 122, as by a
plurality of bolts 124 or the like, extending through all of the
structure and threadedly engaged within the main casting of the
housing 12.
The auto-fire valve 108 is carried within the cap member 122 and
includes a downwardly facing counterbored recess defining a chamber
126 disposed inwardly of the counterbore of the recess. A circular
diaphragm 128 is disposed within the counterbored portion of the
recess and is retained therein by an annular exhaust valve member
130. The valve member 130 is formed with a central opening 140
which forms a part of the pilot pressure chamber exhaust passageway
having its lower end communicated with the vertical bore 112, as by
an elongated slot 142 formed in the upper gasket 120 with its ends
communicating respectively with the central opening 140 and the
vertical bore 112 through the registering openings in the plate 118
and lower gasket 114. The upper end of the opening 140 is defined
by an annular portion defining an upwardly facing annular valve
seat 144 adapted to be engaged by the central portion of the
diaphragm 128.
It can be seen that when chamber 126 is pressurized, diaphragm 128
will move into pressure engagement with the valve seat 144 closing
the pilot pressure exhaust passageway. When the chamber 126 is
exhausted to atmosphere, pilot pressure within the exhaust
passageway including the central opening 140 will move the
diaphragm 128 upwardly, thus communicating the pilot pressure with
the annular space between the valve member 130 and the diaphragm
128. This space is communicated with the atmosphere through a port
146 formed in the valve member 130 adjacent its periphery. The
upper gasket 120 includes an opening 148 which communicates with
the port 146 and with one end of an elongated slot 150 formed in
the plate 118 therebelow. The opposite end of the slot 150
communicates with a radial extension of an annular opening 152
formed in the upper gasket 120 concentric with the valve insert 62.
Preferably, the cap member 122 is apertured, as indicated at 154,
concentric with the valve insert 62 and an exhaust cap assembly 156
is mounted within the aperture 154 to deflect the air under
pressure exhausting to the atmosphere laterally away from the hand
of the operator through a discharge opening 157. The exhaust cap
assembly 156 also serves to protect the exhaust valve element 86 of
the main control valve 56 from damage.
As shown in FIGS. 1 and 2, the fluid pressure operated system 22
includes a conventional plenum chamber system for effecting the
return stroke of the fastener driving element 20. To this end, the
drive portion 30 of the housing 12 is formed with a plenum chamber
158 in surrounding relation to the exterior periphery of the
cylinder 32. The upper end of the plenum chamber is sealed with
respect to the cylinder by any suitable means, such as an O-ring
seal 160 mounted within an appropriate annular groove in the upper
interior periphery of the main casting of the housing 12 and
disposed in engagement with the exterior periphery of the cylinder
32.
As best shown in FIG. 4, the opposite lateral sides of the lower
end of the cylinder 32 are communicated directly with the lower end
of the plenum chamber 158. In this regard, it should be noted that
the main casting has a counterbored opening 170 formed in the lower
end portion thereof, concentric with the cylinder 32 within which
is engaged the lower end of a bumper pad 172. The bumper pad 172 is
formed with a central opening 174 of a size somewhat greater than
the size of the fastener driving element 20 so as to provide part
of an exhaust passageway for the bottom of the cylinder when the
fastener driving element 20 is disposed in its uppermost fastener
receiving position. Preferably, a plate 176 is secured to the main
casting below the bumper pad 172, the latter being detachably
secured to the main casting by a series of bolts 178 or the like
which also extend through the adjacent portion of the magazine
assembly to detachably secure the forward end of the latter to the
main casting of the housing 12. As best shown in FIGS. 1 and 2, the
plate 176 has a restricted passage 179 therein which forms the
remaining part of the exhaust passageway provided by the opening
174.
In accordance with conventional practice, the cylinder 32 is formed
with an opening 180 which is disposed in a position slightly above
the O-ring 42 of the piston assembly 36 when the latter is disposed
in its lowermost fastener driven position, as best shown in FIG. 2.
It will be understood that the plenum return system operates in
conventional fashion. Thus, during the drive stroke of the drive
piston assembly 36, the air within the cylinder below the piston is
initially, at least partially, discharged through the exhaust
passageway provided by the opening 174 and passage 179.
During the latter portion of the drive stroke, the air within the
cylinder 32 below the piston assembly 36 may be somewhat compressed
into the plenum chamber 158. When the piston assembly reaches the
end of its drive stroke, the engagement of the piston pad with the
pad 172 seals off any exhaust through the aforesaid exhaust
passageway while at the same time the air under pressure acting on
the upper surface of the piston enters opening 180 to immediately
pressurize the plenum chamber 158 to substantially full reservoir
pressure.
The charging of the plenum chamber 158 with fluid under pressure in
the manner indicated above, is used as a pressure signal to operate
the auto-fire valve 108. To this end, the diaphragm chamber 126
thereof is communicated with the plenum chamber 158 through a
series of passages including a vertical port 182, communicating
with the central portion of the chamber 126, a transverse port 184
communicating at one end with the port 182 and at its other end
with a vertical bore 186, the port 182 and bores 184 and 186 being
formed in the cap member 122. The lower end of the bore 186
communicates with the upper end of a vertical bore 188 formed in
the main casting through a series of registering openings 190
formed in the upper gasket 120, plate 118 and lower gasket 114. The
lower end of the bore 188 communicates with the upper end of the
plenum chamber 158.
Preferably, the bore 184 is counterbored as indicated at 192 to
threadedly receive an adjusting member 194 having a frustoconical
inner end portion 196 which is adapted to be positioned within the
adjacent end of the bore 184 to provide an adjustable restriction
to the flow of fluid from the plenum chamber 158 to the diaphragm
chamber 126 and vice versa.
Referring now more particularly to FIGS. 3 and 4, the manually
controlled actuating mechanism 24 preferably includes a trigger
member 198 which, as shown, is of generally U-shaped construction,
having a pair of forwardly extending tabs 200 which are apertured
to receive a pivot pin 202 extending through the upper end portion
of a pair of transversely spaced vertically extending ribs 204
forming an integral part of the main casting of the housing 12. The
trigger member 198 is biased by its own weight into a normally
inoperative limiting position wherein the bight portion of the
trigger engages the adjacent outer surface of the ribs 204, as
indicated at 206 in FIG. 1. The trigger member 198 is adapted to be
engaged by the finger of an operator whose hand is in engagement
with handle portion 28 and is mounted for pivotal movement about
the pivot pin 202 in a counterclockwise direction as viewed in FIG.
1 into an operative position wherein the bight portion of the
trigger engages a depending abutment 208 formed integrally on the
main casting of the housing 12 as best shown in FIG. 2.
The manually controlled actuating mechanism 24 also preferably
includes a work contacting member or contact trip element 210
which, as shown, is generally of L-shaped configuration including
an annular horizontally extending portion and having a lower work
engaging horizontal surface 212 and a vertical portion 214
extending upwardly therefrom.
The vertical portion 214 of the work contacting member 210 is
mounted for vertical reciprocating movement with respect to the
nose piece 16 between a lower normally inoperable limiting position
and an upper operative limiting position. To this end, it will be
noted that the nose piece includes a pair of cooperating vertically
extending plates 216 and 218, the plate 216 having a transverse
opening 220 formed therein through which the fasteners F from the
magazine assembly 14 are fed to the drive track 18, the latter
being defined by a slot formed in the plate 218 and the encompassed
surfaces of the plate 216. The lower ends of the plates 216 and 218
define horizontal surface means 222 adapted to engage the surface
of the workpiece W when the device 10 is disposed in operative
engagement therewith, as shown in FIG. 2.
The vertical portion 214 of the work contacting member 210 has one
surface thereof disposed in sliding engagement with the lower
central exterior surface of the plate 218. The vertical portion 214
of the work contacting member 210 is guided for vertical sliding
movement along the peripheral outer surface of the plate 218 by the
lower end portion of a housing plate 224, the housing plate 224
together with the plates 216 and 218 being detachably secured to
the magazine assembly 14 as by a pair of bolts 226.
The upper end of the vertical portion 214 has a tab 228 struck
therefrom and bent downwardly and outwardly. The tab 228 is
apertured to receive one end of a guide pin 230. Mounted in
surrounding relation to the guide pin 230, is a compression coil
spring 232 which is adapted to transmit the vertical movement of
the work contacting member 210 to a motion transmitting member,
generally indicated at 234. The motion transmitting member 234
includes a front vertically extending portion 236 mounted in
alignment with a vertical portion 214 of the work contacting member
210 in vertically spaced relation thereto. The upper end of the
front vertical portion 236 has a tab 238 struck therefrom and bent
downwardly and outwardly to engage the upper end of the coil spring
232 the lower end of which engages the tab 228. The tab 228 is
apertured to receive the upper end of the guide pin 230.
The motion transmitting member 234 also includes an elongated bent
section including a front portion 240 which extends laterally
outwardly from the one side of the vertical portion 236 adjacent
the lower end thereof, through an opening 242 in the housing plate
224, a rearwardly extending horizontal portion 244 and upwardly
bent vertical portion 246 and a horizontally extending portion 248.
Fixedly secured to the upper surface of the horizontal portion 248,
as by welding or the like, is a guide rod 250 having a coil spring
252 disposed in surrounding relation thereto. The upper end of the
guide rod 250 extends through an opening in a plate 254 mounted
between the ribs 204, the upper end of the spring 252 engaging the
plate 254 and the lower end of the spring engaging the portion 248
so as to resiliently urge the motion transmitting member 234
downwardly into a lower limiting position wherein the lower surface
of the horizontal portion 240 engages the adjacent surface of the
opening 242 formed in the housing plate 224.
The upper end of the guide rod 250 includes a cam surface 256,
which, when the member 234 is disposed in its normally biased
limiting position, is disposed in spaced relation below one end of
an interlock lever member 258. As best shown in FIGS. 1 and 2 the
interlock member 258 is generally of U-shaped cross-sectional
configuration having the central portion of its legs pivotally
connected with the lower end of the actuating member 92, as by a
pivot pin 260. The opposite end of the interlock member 258 has a
depressed portion 262 formed in the bight portion thereof which is
adapted to engage the adjacent surface of the trigger member
198.
OPERATION
It will be noted that when the device 10 is in an inoperative
condition as shown in FIG. 1, spring 94 acts to resiliently bias
the main valve 56 into its closed upper limiting position. The
spring 94 also serves to bias the actuating valve 92 into its
closed position. Trigger member 198 is biased by its own weight
into its inoperative position and spring 252 serves to bias the
motion transmitting member 234 into its lowermost limiting
position, spring 232 serving to likewise maintain the work
contacting member 210 in its lowermost limiting position.
When the device 10 is connected with a source of fluid under
pressure, reservoir 26 is immediately charged and this fluid
pressure is free to pass into the pilot chamber 90 through the
restricted orifice 96. Thus, the pressure within the pilot chamber
90 serves to maintain the main control valve 56 in its closed
position wherein the upper end of the drive chamber 34 is
communicated with the atmosphere through the open exhaust valve
element 86. It will also be understood that the drive piston
assembly 36 will normally be disposed in its uppermost limiting
position all as shown in FIG. 1.
The fluid pressure operated system 22 is actuated by moving the
actuating valve 92 from its normal inoperative closed position into
its operative open position. This actuation requires a manual
movement of the trigger member 198 and of the work contacting
member 210 into their operative positions. The operation of the
interlock lever 258 is such that the actuating valve will be moved
into its operative position in response to any one of the three
following conditions: (1) a simultaneous or concomitant movement of
the trigger member and contacting member 210 into their operative
positions; (2) a movement of the work contacting member 210 into
its operative position when the trigger member 198 is disposed in
its operative position; and (3) a movement of the trigger member
198 into its operative position when the work contacting member 210
is disposed in its operative position.
With reference to FIG. 6, it will be noted that a movement of the
work contacting member 210 into its operative position, while the
trigger member 198 is in its inoperative position, will merely
result in moving the cam surface 256 into engagement with or into
slightly spaced relation to the associated end of the interlock
member 258. Under these circumstances, a pivotal movement of the
trigger member 198 into its operative position will effect a
counterclockwise pivotal movement of the interlock member about the
cam surface 256 as a fulcrum, which movement will effect movement
of the trigger valve into its operative position, as shown in FIG.
2. Likewise, with reference to FIG. 7, it will be noted that a
movement of the trigger member 198, while the work contacting
member 210 is disposed in its inoperative position will result in a
counterclockwise pivotal movement of the interlock member 258 about
the pivot pin 260 without any corresponding movement of the
actuating valve 92. This pivotal movement of the interlock member
258 merely serves to move the end thereof which is normally spaced
from the cam surface 256 when the work contacting member 210 is
disposed in its normal inoperative position into engagement with or
into slightly spaced relation to the cam surface 256. Under these
conditions, movement of the work contacting member 210 into its
operative position will effect a pivotal movement of the interlock
member 258 about the projection 262 as a fulcrum, which movement
will effect the movement of the trigger valve into its operative
position as shown in FIG. 2.
The movement of the actuating valve 92 into its operative position
opens the pilot exhaust passageway. Pilot pressure enters the
counterbore 102, transverse bore 110, vertical bore 112, slot 142
and auto-fire valve opening 140. Since the diaphragm chamber 126 is
receiving an atmospheric pressure signal from the plenum chamber
158, the pilot pressure in opening 140 moves the diaphragm 128
upwardly permitting the pilot pressure to exhaust to atmosphere
through port 146, opening 148, slot 150, opening 152 and laterally
outwardly of the exhaust cap assembly 156 through opening 157.
It will be noted that the exhaust passageway provides a
cross-sectional area which is greater than the cross-sectional area
of the restricted orifice 96 and, consequently, the pilot pressure
within the pilot chamber 90 will exhaust substantially to
atmospheric conditions notwithstanding its continuous communication
with the reservoir 26 through the restricted orifice 96. As soon as
the pilot pressure drops, pressure within the reservoir 26 acting
on the upper surface of the pilot piston 88 will move the main
valve 76 downwardly into its lowermost position wherein the inlet
valve element 80 communicates the inlet 66 with the reservoir and
exhaust valve element 86 closes the outlet 74. Reservoir pressure
is then communicated to the upper end of the drive chamber 34
through openings 70 and 72 to effect the drive stroke of the piston
assembly 36 and fastener driving element 20 connected thereto.
As previously noted, when the drive stroke is completed and the
drive piston assembly 36 reaches its fastener driven position,
plenum chamber 158 is charged with reservoir pressure from the
drive chamber 34 through the opening 180. This pressure is
communicated as a signal past the metering element 196 to the
auto-fire valve diaphragm chamber 126. This pressure signal which
acts on the entire surface of the diaphragm urges the central
portion thereof into pressure-tight engagement with the annular
valve surface 144, thus closing the opening 140 of the pilot
exhaust passageway. The reservoir pressure entering the pilot
chamber 90 through the restricted orifice 96 can now build up in
the pilot chamber until it reaches a value sufficient to effect the
upward movement of the main valve 76 into its closed position as
shown in FIG. 1.
When the main control valve is in this position, the inlet valve
element 80 is disposed in engagement with the valve seat 68 closing
off communication between the reservoir and the drive chamber 34
while the outlet opening 74 is communicated past the open exhaust
valve element 86 to the atmosphere through the cap assembly 156
through opening 157. The exhaust of the fluid pressure above the
drive piston 36 permits the fluid pressure charge within plenum
chamber 158 to effect the rapid return stroke of the piston and
fastener driving element 20 connected thereto into its uppermost
position. During the latter portion of this movement the pressure
within the plenum chamber 158 is allowed to restrictively exhaust
to atmosphere through opening 174 and passage 179. The arrangement
of the exhaust passageway provided by the opening 174 and passage
179 provides a constant restriction to exhaust except when the pad
50 is actually in engagement with the bumper pad 172. It will be
understood that a variable restriction may be provided in
accordance with conventional practice, wherein a lesser restriction
taken place when the piston is adjacent its uppermost position.
The exhaust of the plenum chamber 158 serves as a pressure signal
to condition the auto-fire valve 108 to unblock the pilot chamber
exhaust passageway and thereby commence the drive stroke of the
next cycle. In this regard, it will be noted that as soon as the
pressure within the auto-fire valve diaphragm chamber 126 reduces
to a value sufficient to permit the pressure in the opening 140 to
move the diaphragm out of engagement with the seat 144, the pilot
chamber 90 will begin to exhaust which, when it reaches a
predetermined lower pressure condition, will permit the main valve
76 to be moved downwardly into its open position to commence the
drive stroke of the next cycle. Since the change in pressure within
the auto-fire valve diaphragm chamber 126 serves to initiate the
operations which effect automatic recycling and since the rate of
change of the pressure within the chamber 126 can be controlled by
adjusting the setting of member 194, the latter serves as a means
for controlling the rate of the cycle of operation. By adjusting
the member 194 to provide a greater restriction to air flow
thereby, the speed with which a cycle of operation is completed is
reduced. Conversely, by adjusting the member 194 so as to provide
less restriction to air flow thereby, the speed with which a cycle
of operation is completed is increased.
It will be understood that the device will continue to recycle
automatically so long as the actuating valve 92 is maintained in
its operating position by the actuating mechanism 24. In normal
auto-fire operation, the operator moves the device along the
surface of a workpiece W while continuously depressing the trigger
member 198 and maintaining the surface 222 of the nose piece 16 in
engagement with the surface of the workpiece W.
In accordance with conventional practice, it is sometimes desirable
to provide the fastener driving element with a length such that
when it is disposed in its fastener driven position, the lower
fastener engaging surface thereof extends outwardly beyond the
surface 222 of the nose piece 16 a predetermined distance, as, for
example, the distance designated by the reference character X in
FIG. 2. The work contacting surface 212 of the work contacting
member 210 when the latter is disposed in its normally biased
inoperative position, is disposed outwardly of the nose piece
surface 222, a distance which is generally equal to the distance X
plus the distance designated by the letter Y equal to the movement
of the motion transmitting member 234 necessary to effect the
movement of the trigger valve 92 into its operative limiting
position. It will be noted, however, that since the movement of the
work contacting member 210 is transmitted to the motion
transmitting member 234 by the spring 232, the total movement of
the motion transmitting member 234 can be less than that of the
work contacting member 210. Preferably, the total movement of the
motion transmitting member is generally equal to the distance Y and
it will be noted that the upper surface of the vertical portion 236
thereof will engage the adjacent lower surface of the plate 176
when the motion transmitting member 240 has moved with the work
contacting member through the distance Y. Subsequent movement of
the work contacting member through the distance X will result in a
yielding movement of the spring 232 without a corresponding
movement of the member 234.
With this arrangement, it will be noted that in the event that the
movement of the fastener driving element into its fastener driving
position should result in a recoil movement of the entire device
away from the work contacting surface in a range which is generally
equal to the distance X, the work contacting member 210 alone will
move under the action of spring 232 relative to the housing with
substantially no movement of member 234 thereby preventing any
undesired closing movement of the actuating valve 92 which would
have the effect of disrupting the automatic cycling of the fluid
pressure operating system 22.
It will be understood the operation of the spring 232 would have
the same advantages in a device, without fastener driving element
overtravel, which had sufficient recoil to cause the device to move
off of the workpiece. Moreover, such operation would have
advantages where the contact trip constitutes the only manual means
for actuating the device.
It will be understood that the time required to automatically cycle
the device is dependent upon the setting of the frustoconical
needle valve 196 within the bore 184. Moreover, by adjusting the
threaded member so as to provide the slowest speed of automatic
cycle, the operator is enabled to effect manual operation either in
single fire, bump fire or drag fire fashion before automatic
recycling will take place.
It thus will be seen that the objects of this invention have been
fully and effectively accomplished. It will be realized, however,
that the foregoing specific embodiment has been shown and described
only for the purpose of illustrating the principles of this
invention and is subject to extensive change without departure from
such principles. Therefore, this invention includes all
modifications encompassed within the spirit and scope of the
following claims.
* * * * *