U.S. patent number 3,821,991 [Application Number 05/252,479] was granted by the patent office on 1974-07-02 for fastener tool.
This patent grant is currently assigned to Rockwell International Corporation. Invention is credited to Robert H. Alexander.
United States Patent |
3,821,991 |
Alexander |
July 2, 1974 |
FASTENER TOOL
Abstract
A tool including a fastener rotating output member and mechanism
for indicating if a fastener rotated by said output member has been
tightened to a prescribed torque and/or for providing an indication
of the length of time for which the fastener was tightened.
Inventors: |
Alexander; Robert H. (Columbia,
SC) |
Assignee: |
Rockwell International
Corporation (Pittsburgh, PA)
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Family
ID: |
26801295 |
Appl.
No.: |
05/252,479 |
Filed: |
May 11, 1972 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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104209 |
Jan 6, 1971 |
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Current U.S.
Class: |
173/180; 91/1;
73/862.23; 173/20 |
Current CPC
Class: |
B25B
23/1456 (20130101); B25B 23/145 (20130101) |
Current International
Class: |
B25B
23/14 (20060101); B25B 23/145 (20060101); B25b
023/14 () |
Field of
Search: |
;91/1,59 ;81/52.5R
;173/12,20 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Purser; Ernest R.
Parent Case Text
This application is a continuation-in-part of copending U.S. Pat.
application No. 104,209 filed Jan. 6, 1971.
Claims
What is claimed and desired to be secured by Letters Patent is:
1. A tool for tightening fasteners comprising: an output member
adapted to have a fastener engaging member attached thereto; a
motor; means drive-connecting said motor to said output member;
means for supplying operating energy to the motor; torque
responsive means operable as the fastener being tightened reaches a
selected torque to concomitantly produce a signal to indicate that
the fastener has been tightened to the selected torque and to
interrupt the flow of operating energy to the motor; and means
activatable by the signal generated by the signal generating means
to provide on or in the proximity of the fastener which has been
tightened a visual indication of the reaching of the selected
torque by the fastener.
2. A tool for tightening fasteners comprising: a housing; a
fastener rotating output member rotatably supported from said
housing; means in said housing for rotating said output member; and
torque responsive means in said housing which is operable when the
fastener being tightened has reached a selected torque to produce
an electrical signal to indicate that the fastener was tightened to
the selected torque, said signal generating means comprising a
switch and means for actuating said switch when said selected
torque is reached and the means for actuating said switch
comprising an actuator movable toward and away from said switch,
means biasing said actuator away from said switch, passages through
which an operating fluid can flow to said actuator to move it
toward said switch against the force exerted by said biasing means
and thereby actuate said switch, and means for so controlling the
flow of fluid through said passages to said switch actuator that
the actuator is displaced to actuate the switch when said selected
torque is reached.
3. A tool for tightening fasteners comprising: a fastener rotating
output member; means for rotating said output member; and means
operable when the fastener being tightened has reached a selected
torque to produce one signal to indicate that the fastener has been
tightened to the selected torque and a second signal indicative of
the length of time for which the output member was rotated, said
second signal thereby providing a differentiation between properly
and improperly tightened fasteners.
4. A tool for tightening fasteners comprising: a fastener rotating
output member; means for rotating said output member; torque
responsive means operable when the fastener being tightened has
reached a selected torque to terminate the rotation of the output
member and prevent further tightening of the fastener; and means
operable to produce a signal indicative of the length of time for
which the output member was rotated, said signal thereby providing
a differentiation between properly and improperly tightened
fasteners.
5. The tool of claim 4, wherein the signal producing means further
includes means for producing a second signal when said fastener
reaches the selected torque which will provide an indication that
the fastener has been tightened to the selected torque.
6. The tool of claim 4, wherein the means for rotating the fastener
includes a motor which is energizable to rotate the output member
and de-energizable to stop the rotation of said member and wherein
said signal generating means comprises a timer means; means for
actuating said timer means concurrently with the energization of
said motor; and means for terminating the timing action of said
timer means concurrently with the deenergization of said motor.
7. The tool of claim 6, wherein said timer means is electrically
operated; wherein said tool further comprises circuit means for
connecting said timer means across an electrical power source;
wherein the means for actuating said timer means comprises a first
switch and means for so actuating said first switch as to complete
the continuity of said circuit means when said motor is energized;
and wherein the means for terminating the timing action of the
timer means comprises a second switch and means for so actuating
said switch when said selected torque is reached as to interrupt
the continuity of said circuit means.
8. The tool of claim 7, wherein said first and second switches are
magnetically actuatable; wherein said signal generating means
further comprises first and second magnetic switch actuators
mounted in said tool for movement toward and away from said first
and second switches, respectively, means biasing said actuators
away from said switches, and passages through which an operating
fluid can flow to said actuators to move them toward said switches
against the forces exerted by said biasing means and thereby
actuate said switches; and means for so controlling the flow of
fluid through said passages to said switch actuators that the first
actuator is displaced to actuate the first switch when the motor is
energized and the second actuator is displaced to actuate the
second switch when the motor is de-energized.
9. The tool of claim 8, wherein said motor is a pneumatic motor and
wherein the means for controlling the flow of operating fluid
comprises a first valve which is manually actuatable to allow
operating fluid to flow to and energize said motor and to flow to
and displace said first switch actuator in the switch actuating
direction and a second valve automatically operable when the
selected torque is reached to terminate the flow of operating fluid
to and de-energize said motor and to so effect the flow of fluid to
said second actuator as to displace said second actuator in the
switch actuating direction.
10. The tool of claim 9, together with means including said first
valve which is manually actuatable following the actuation of at
least one of said switches to so alter the flow of fluid to the
actuator associated with each actuated switch as to permit the
associated biasing means to displace the actuator away from and
effect the deactuation of the switch.
11. The tool of claim 10, together with means for resetting said
second valve.
12. The tool of claim 11, together with means from which it can be
ascertained if said second switch means has been actuated prior to
the actuation of the resetting means, whereby said signal
generating means further provides a signal indicating whether the
fastener was tightened to the selected torque.
13. A tool for tightening fasteners comprising: a housing, a
fastener rotating output member rotatably supported from said
housing; a pneumatic motor in said housing; means drive-connecting
said motor to said output member; means for supplying operating
fluid to said motor; means for generating a signal; and means for
both shutting off the supply of fluid to the motor and actuating
the signal generating means when a fastener being tightened has
been tightened to a selected torque, said signal generating means
comprising means providing a path through which the operating fluid
can flow to generate a pneumatic signal and a fluid actuatable
valve means movable between first and second positions in which it
respectively interrupts and permits the flow of fluid through said
path.
14. The tool of claim 13, together with means providing a flow
passage through which operating fluid can flow to said motor and to
said fluid actuatable valve and means providing a valve seat in
said passage and wherein the means for actuating the signal
generating means comprises a valve member disposed in said passage
and movable toward and away from said valve seat to control the
flow of operating fluid through said passage; a valve stem means
supporting said valve member in said passage; an actuator; means
biasing said actuator to a position in which said actuator so
engages said valve stem means as to hold the valve member away from
the valve seat; and means operable as the fastener is tightened to
the selected torque to move said actuator out of engagement with
said valve stem means and thereby free said valve member for
movement toward said seat.
15. The power-operated tool of claim 14, together with a wall means
surrounding said valve member and cooperating with said member to
restrict the flow of operating fluid through said passage, whereby
there is a pressure drop across said valve member which generates a
force for moving the valve member toward the valve seat in the
absence of a restraint on the valve member.
16. The tool of claim 13, wherein said operating fluid supply means
comprises a first valve which is manually displaceable to an open
position to allow operating fluid to flow into the interior of the
tool housing; and wherein the means for actuating the signal
generating means and shutting of the flow of operating fluid to the
motor comprises a second, normally open valve movable to a closed
position when said selected torque is reached, said tool further
including means through which said fluid can so flow as to maintain
said fluid actuatable valve means in said first position when said
first and second valves are open and as to displace said valve
means to said second position when the selected torque is
reached.
17. The tool of claim 16, together with means operable following
the displacement of said fluid actuatable valve means to said
second position and the subsequent closing of the first valve to
return said fluid actuatable valve means to its first position and
said second valve to its open position.
18. A tool for tightening fasteners comprising: a housing; a
fastener rotating output member rotatably supported from said
housing; a pneumatic motor in said housing; means drive-connecting
said motor to said output member which comprises means operable
beginning with the exertion of a rotation resisting force by the
fastener being tightened to brake and thereby reduce the speed and
absorb the kinetic energy of the rotating drive component(s) of the
tool and thereby keep said energy from being applied to and
overtightening the fastener engaged by the output member; means for
supplying operating fluid to said motor; means for generating a
signal, and means for both shutting off the supply of air to the
motor and actuating the signal generating means when a fastener
being tightened has been tightened to a selected torque.
19. A tool for tightening fasteners comprising: a housing, a
fastener rotating output member rotatably supported from said
housing; a pneumatic motor in said housing; means drive-connecting
said motor to said output member; means for supplying operating
fluid to said motor; means for generating a signal; and means for
both shutting off the supply of air to the motor and actuating the
signal generating means when a fastener being tightened has reached
a selected torque, said signal generating means comprising flow
means through which the operating fluid can flow to generate a
pneumatic signal, a fluid actuatable valve means movable between a
first position in which said valve means permits flow of the
pneumatic fluid to said motor and inhibits the flow of said fluid
to said flow means and a second position in which said valve means
terminates the flow of the pneumatic fluid to the motor and removes
the inhibition on the flow of the fluid through the flow means, and
means for effecting the movement of the valve means from the first
to the second of the positions thereof when said selected torque is
reached.
20. The tool of claim 19, together with selectively operable means
which, when operated, will result in the interruption of the flow
of pneumatic fluid through said flow means.
21. A tool for tightening fasteners comprising: a housing; a
fastener rotating output means rotatably supported from said
housing: a pneumatically activatable marking means for providing on
or in the proximity of the fastener being tightened a visual
indication of the reaching of a selected torque by the fastener,
said marking means being housed at least in part in said rotatably
supported output means; a pneumatic motor in said housing; means
drive-connecting said motor to said output means; means for
supplying operating fluid to said motor; flow means through which
operating fluid can flow to activate said marking means; valve
means operable when actuated to both shut off the supply of
operating fluid to the motor and effect a flow of fluid through
said flow means; and means for automatically actuating said valve
means when the fastener being tightened has reached the selected
torque.
22. The tool of claim 21, wherein said marking means comprises a
member which, when displaced, will result in the producing of said
visual signal, means including a slidably mounted piston for
displacing said member, and means providing fluid communication
between said flow means and said piston so that said operating
fluid will operate upon said piston and cause the piston to
displace said member and activate said marking means.
Description
The present invention relates to tools, and more specifically, to
novel, improved, fastener tools which generate a signal when a
fastener being tightened reaches a prescribed torque and/or
generate a signal indicative of the length of time for which the
fastener was tightened.
Among the devices heretofore proposed for providing an indication
that a fastener has been tightened to a selected torque are those
disclosed in U.S. Pat. Nos. 3,009,371 issued Nov. 21, 1961, to
Hines; 3,389,623 issued June 25, 1968, to Gill; 3,472,102 issued
Oct. 14, 1969, to Dunlap et al.; and 3,523,471 issued Aug. 11,
1970, to Lance. None of these tools provide an indication of the
length of time for which the fastener was tightened.
Devices similar in some respects to those discussed in the
preceding paragraph are disclosed in U.S. Pat. Nos. 2,901,934
issued Sept. 1, 1969, to Dunham and 3,581,607 issued June 1, 1971,
to Rogers. However, the device disclosed in the Dunham patent
merely provides an indication that a wrench has been applied to a
fastener; it does not indicate whether or not the fastener is
tightened to the selected torque or the length of time for which
the fastener is tightened. Rogers' tool generates a signal when the
fastener is set to a desired depth; but this signal is employed to
actuate a motor shut-off mechanism and not to provide an indication
that the desired depth has been reached. The Rogers tool does not
produce a torque indicative signal or one indicative of the length
of time for which a fastener is set.
One primary object of the present invention resides in the
provision of novel fastener tools capable of providing a signal
indicating that a fastener has been tightened to a selected torque
which are superior to those heretofore available in one or more
respects such as reliability and/or ease of operation, capacity,
service life, cost, ease of maintenance, etc.
In some circumstances a torque responsive mechanism can be
triggered to generate a signal of the character just described even
though the fastener has not been properly tightened. This may occur
if a fastener is cross threaded on a bolt or stud or if the threads
are too tight, for example. In both of these exemplary cases the
resistance to rotation can increase to the level at which the
torque responsive mechanism will respond in many less turns than
are needed to fully tighten the fastener.
Another important and primary object of the invention accordingly
resides in the provision of novel tools capable of generating a
signal by which properly tightened fasteners can be distinguished
from those which are not correctly tightened but nevertheless offer
sufficient resistance to turning to trigger a torque responsive,
signal generating mechanism.
Typically, the signal will be indicative of the length of time for
which the fastener has been tightened. The length of indicated time
can be compared with a standard time for tightening the particular
type of fastener involved, making it possible to readily ascertain
whether the fastener has been properly tightened.
Another important but more specific object of the invention
accordingly resides in the provision of novel fastener tools
capable of generating a signal indicative of the length of time for
which a fastener has been tightened.
Still another important object of the invention resides in the
provision of novel tools which perform both of the functions
indicated above; that is, which produce a signal or combination of
signals indicative of the tightening of a fastener to a selected
torque and of the length of time for which the fastener is
tightened.
The signals generated by typical tools in accord with the present
invention will be electrical or pneumatic. These signals can be
processed to provide a temporary indication and/or permanent record
of the time for which the fastener was tightened and/or of whether
the fastener was tightened to the selected torque. The signal may
also be utilized to actuate or operate a paint squirting or other
device capable of producing on or adjacent the fastener a visual
indication showing that the fastener has been tightened in a manner
which will produce a satisfactory joint.
Typically, tools of the type with which the present invention is
concerned will be motor driven; and they will have a torque
responsive mechanism for automatically shutting off the motor when
the fastener is tightened to the selected torque (exemplary of the
tools of this general character are those disclosed in U.S. Pat.
No. 3,195,704 issued July 20, 1965, to Linsker and in parent U.S.
Pat. application No. 104,209). In tools of this character in accord
with the present invention the signal generating mechanism is
actuated at the same time the motor is shut off if a torque
responsive signal is wanted or both when the motor is energized and
shut off if a time indicative signal or signals indicative of both
time and the reaching of a selected torque are desired.
Air or other pneumatic motors can be used to advantage in tools in
accord with the present invention. In such tools the operating
fluid may be employed to open and close appropriate switches and
thereby produce torque, time, or torque and time indicative,
electrical signals. Or the operating fluid may be used to generate
a pneumatic signal or signals.
Other important but more specific object of the invention
accordingly reside in the provision of novel tools capable of
providing a signal which is indicative of a fastener having been
tightened to a selected torque and/or for a specified period of
time and is:
1. readily processable to provide a temporary indication and/or
permanent record of whether the fastener was correctly torqued
and/or tightened for a satisfactory period of time.
2. capable of actuating a visual marking unit to produce a visual,
torque and/or time indicative mark on or adjacent the fastener.
Still other important but specific objects of the invention reside
in the provision of novel tools capable of providing a signal
indicative of a fastener having been tightened to a selected torque
and/or for a specified period of time;
3. which are motor driven and which have a torque responsive
mechanism automatically operable when the selected torque is
reached to shut off the motor and to actuate a signal generating
mechanism to produce a torque indicative signal.
4. which are motor driven and which include a timing mechanism, a
torque responsive mechanism for stopping the motor when a fastener
is tightened to a selected torque, and an arrangement for starting
and stopping the timing sequence as the motor is started and
stopped to provide an indication of the length of time for which
the motor was run to tighten a fastener.
5. which, in conjunction with the preceding object, are also
capable of producing a signal when the torque responsive mechanism
stops the motor which will indicate that the fastener has been
tightened to the selected torque.
6. which are driven by a pneumatic motor and in which the operating
fluid is utilized to generate a pneumatic signal or signals.
7. which are driven by a pneumatic motor and in which the operating
fluid is utilized to generate an electrical signals or signals.
8. which have various combinations of the attributes to which the
objects previously set forth are directed.
Other important objects and featues and further advantages of the
invention will become apparent from the appended claims and as the
ensuing detailed description and discussion proceeds in conjunction
with the accompanying drawing, in which:
FIG. 1 is a partially sectioned side view of a signal generating
fastener tool constructed in accord with the principles of the
present invention with the signal generating mechanism in its
unactuated configuration;
FIG. 2 is a view similar to FIG. 1 of the rear end of the tool with
the signal generating mechanism in its actuated configuration;
FIG. 3 is a side view of a second form of fastener tool in accord
with the principles of the present invention;
FIG. 4 is a view similar to FIG. 2 of a third form of tool in
accord with the principles of the invention but with the signal
generating mechanism in its unoperated configuration; and
FIG. 5 is a schematic of electrical circuitry employed in the tool
of FIG. 4.
Referring now to the drawing, FIGS. 1 and 2 illustrate a
power-operated fastener tool 20 of the nut runner type, which is
constructed in accord with the principles of the present invention.
Tool 20 includes an air motor 22 housed in a casing 24 having
motor, intermediate, and angle head sections 24a, 24b, and 24c. The
motor is connected through a brake or energy absorbing device 26 to
a rotatably mounted output member 28 which is adapted to have a
socket or other fastener engageable component.sup.1 secured to it.
It is the function of brake 26 to gradually slow down and absorb
kinetic energy from the rotating motor and other tool components as
a fastener is being tightened so that the kinetic energy will not
be transmitted to and overtighten the fastener.
Tool 20 also includes a torque responsive shut-off mechanism 30 for
automatically terminating the flow of air to motor 22 when the
fastener being tightened reaches a preselected torque.
The tool further includes a novel signal generating mechanism 32
which is actuated as the shut-off mechanism terminates the flow of
air to motor 22. The generation of a signal is accordingly an
indication that the fastener has been tightened to the selected
torque.
In tool 20, the signal is a pulse of compressed air which is
applied to a marking unit 34 to propel a small quantity of marking
ink or dye through output member 28 onto the fastener. Thus, one
can readily ascertain by visual inspection that the fastener has
been tightened to the selected torque.
Referring again to the drawing, air motor 22 is of a commercially
available type and, will not be described in detail herein.
Briefly, however, the air motor includes a casing 36 in which a
rotor 38 is rotatably supported by bearings 40 and 42.
Air is supplied to a motor 22 through a line (not shown) connected
to a fitting 44 which communicates with an aperture (not shown)
through the rear end of casing section 24a. From the fitting and
aperture the air flows through a passage 46, around a manually
displaceable valve 48, and through passages 50 and 52 into a
chamber 54 formed in a valve block 56 in casing section 24a. From
chamber 54, the air flows around a disc type valve member 58, which
is a component of automatic shut-off mechanism 30, and, as shown by
arrows 60, then through communicating passages 62, 64, and 66 into
motor 22 to drive rotor 38.
The manually displaceable valve member 48 which controls the flow
of air to the interior of the tool is biased against a seat 68 at
the inlet end of passage 50 and also laterally positioned by
springs 70 and 72. These springs are kept in place by a threaded
retainer 74.
The valve member may be displaced from the seated or closed
position (FIG. 2) to an open position (FIG. 1) to allow air to flow
from passage 46 into passage 50 and then to motor 22 by depressing
a lever 76 pivotally fixed to the motor section 24a of the tool
casing as by pivot pin 78. Lever 76 engages a plunger 80 slidably
mounted in a guide or fitting 82 disposed in casing section 24a.
When lever 76 is depressed toward casing section 24a, plunger 80
unseats valve member 48.
The subsequent release of lever 76 allows spring 72 to reseat valve
member 48, restoring plunger 80 and lever 76 to the positions shown
in FIG. 2. This terminates the flow of air into the tool.
The rotor 38 of air motor 22 has a shaft 84 with a hexagonally
configured section 86. This shaft section extends through a
matching, hexagonally configured bore 88 in end member 90 of an
input assembly 92 which is a component of brake 26. Thus, rotor
shaft 84 supports one end of the input assembly. The arrangement
just described also drive connects the input assembly to the motor
shaft.
In addition to the input assembly, brake 26 includes an output
shaft 96. At one end the output shaft is supported by rotor shaft
84, which has a circularly sectioned end portion 98. This end
portion of the shaft extends into a similarly configured recess 100
in the output shaft, leaving shaft 96 free to rotate relative to
shaft 84 and input assembly 92.
The other end of shaft 96 is rotatably supported in a bearing 102
by a tubular drive member 103 housed in the angle head section 24c
of casing 24.
Shaft 96 supports the end of input assembly 92 opposite that
supported by rotor shaft 84 through an operator 104. The operator
is a component of torque responsive shut-off mechanism 30 and is
threaded on shaft 96. This support arrangement also permits the
output shaft to rotate relative to the input assembly.
The brake 26 also includes a torsion type energy absorbing device
in the form of a clock-type spring 105. The outer end of the spring
is fixed in any convenient fashion to an intermediate member 106 of
input assembly 92. The inner end of the spring is fixed to output
shaft 96. Thus, the spring provides a drive connection from the
input assembly 92 of the brake to its output shaft 96.
Referring again to FIG. 1, the output shaft 96 of brake 26 has a
hexagonal end 108 which fits into a matching recess 110 in the end
of drive shaft 103. This rotatably connects the two shafts so that
shaft 103 is driven by motor 22 through brake 26.
Drive shaft 103 is rotatably supported in casing section 24c by
bearing 102 and by a bearing (not shown) which surrounds a bevel
pinion 114 threaded into the right-hand end of the shaft.
Pinion 114 meshes with a bevel gear 116 mounted on the transversely
extending spindle or output member 28 mentioned above. This shaft
is rotatably supported in member 24c by bearings 118 and 120 and is
secured in place by a locking member 124 threaded into the lower
end of the casing section. A spring loaded detent 122 at the lower
end of shaft 28 secures a socket or other fastener engaging
component (not shown) to the shaft for rotation therewith.
To review the operation of tool 20 as thus far described, the
fastener tightening operation is initiated by depressing lever 76
to admit air to the motor 22, rotating its rotor 38. Rotor shaft 84
accordingly rotates the input assembly 92 of energy absorbing
device 26. Input assembly 92 rotates output shaft through spring
105; and the output shaft rotates the drive shaft 103 to which it
is connected. This shaft rotates output shaft 28, causing the
latter to rotate the fastener engaging component (not shown)
secured to it by detent 124 to tighten the fastener.
As the fastener begins to tighten, it exerts a torque on shaft 28
which resists or opposes the torque generated by motor 22. This
resisting torque is transmitted back through drive shaft 103, and
spring 105 begins to "wind up" from an initial, relaxed condition.
As it does so, it begins to absorb kinetic energy from rotor 38 and
the other rotating components of the motor and tool and reduces the
speed of rotation of these components.
As the fastener continues to tighten, spring 105 continues to wind,
further decreasing the speed of motor 22 and the other rotating
components and reducing their kinetic energy until the fastener has
been tightened to the selected torque..sup.2 At this point the
supply of air to motor 22 is automatically terminated to prevent
further tightening of the fastener by torque responsive shut-off
mechanism 30.
Shut-off mechanism 30 includes the disc valve member 58 around
which the air flows to motor 22. Valve 58 is supported in the
chamber 54 in valve block 56 by the left-hand end of valve stem
assembly 126.
The valve stem assembly extends from valve block 56 through rotor
38 with its right-hand end (as shown in FIG. 1) abutting the free
end of a bifurcated pawl or actuator 128. The pawl is pivotally
supported in a slot 130 formed in the output shaft 96 of energy
absorbing device 26 by a transversely extending pivot pin 132. Pawl
128 is biased to the valve stem engaging position shown in FIG. 1
by a spring-loaded pin 134 seated in a recess 136 in shaft 96.
In this position, the valve stem assembly is held to the left as
shown in FIG. 1. This keeps valve 58 in the open position shown in
that figure.
To shut off the supply of air to motor 22, pawl 128 is pivoted in a
clockwide direction as shown in FIG. 1 out of engagement with the
right-hand end of valve stem assembly 126. This creates a force
differential which moves valve 58 to the closed position.
More specifically, the annular passage 138 between the periphery of
the chamber 54 in valve block 56 and valve member 58 is relatively
narrow; and the face 140 of the valve member is relatively large in
comparison. Accordingly, there is a relatively large pressure
differential across the valve member. Therefore, when the restraint
offered by pawl 128 is removed, valve 58 is moved to the closed
position by the larger force acting against valve face 140.
Pawl 128 is pivoted in the valve stem freeing direction by the
previously mentioned operator 104 threaded on the output shaft 96
of brake 26.
Specifically, operator 104 is connected to the input assembly 92 of
the brake for rotation therewith by pins 142 which are fixed to the
operator and extend through apertures 143 in endpiece 144 of the
input assembly. Operator 104 accordingly rotates with but is free
to move longitudinally relative to input assembly 92. A compression
spring 145 surrounding operator 104 and disposed between a snap-in
retainer 146 on the latter and the endpiece 144 of the input
assembly insures that components 92 and 104 stay in the proper
spatial relationship during the operation of tool 20.
As the spring 105 of brake 26 winds, input assembly 92 rotates
relative to output shaft 96 as described above. This creates
relative rotation between components 92 and 96.
As it is rotatably connected to the input assembly, operator 104
rotates relative to and moves to the left along output shaft 96 due
to the threaded connection between these two components. As this
occurs, the operator pushes the lower leg 147 of pawl 128 to the
left, pivoting the pawl clockwise.
As the fastener reaches the preselected torque, upper leg 148 of
the pawl finally rides upwardly off of the end of valve stem
assembly 126. This frees valve 58 for movement to its closed
position in the manner discussed above, terminating the flow of air
to and the operation of motor 22. Thus, the tightening of the
fastener is automatically terminated by the torque responsive
shut-off mechanism when the fastener reaches the selected
torque.
Referring again to the drawing, the signal generating mechanism 32
is actuated concurrently with the closing of disc valve 58 to
provide a signal which indicates that the fastener has been
tightened to the selected torque. As mentioned above, this signal
is utilized in the illustrated tool 20 to actuate a marking unit
34, causing a small quantity of dye or ink to be placed on the
fastener and provide a visual indication that the fastener has been
properly tightened.
The signal generating mechanism includes a valve assembly 150
slidably mounted in a bore 152 formed in the valve block 56 in
casing section 24a. A peripheral seal 154 carried by the main body
member 156 of the assembly keeps air from leaking past it.
Valve assembly 150 is biased to the left to the position shown in
FIG. 1 by a spring 158. This spring engages the right-hand end of
the assembly and is seated in a recess 160 formed in the rear wall
162 of air motor casing 36.
With tool 20 in operation as shown in FIG. 1, line pressure air
flows to the right-hand side of the valve assembly through passage
62, reinforcing the bias of spring 158. An oppositely acting force
is exerted on the valve assembly by air flowing from chamber 54
through passage 164. However, this line pressure air acts on a much
smaller surface than that flowing through passage 62; and the force
exerted by it is not sufficient to overcome the forces exerted on
the right-hand side of the valve assembly. Thus, the valve assembly
remains in the FIG. 1 position.
In its left-hand position valve assembly 150 vents an air supply
line 166 incorporated in marking unit 34 to atmosphere through
passage 168 in casing section 24a, an aperture 170 in valve block
56, the bore 152 in the valve block, and communicating apertures
172 and 174 in the valve block and casing, respectively. Air cannot
flow into the supply line while valve assembly 150 is in the FIG. 1
position. The air flow path from passage 164 through bore 152 to
passages 170 and 168 is blocked by valve member 176 of the valve
assembly, which is engaged with a seat 178 formed in valve block
56. Valve member 176 also keeps air in the interior of the tool
from flowing through the vent passages to the exterior of the
tool.
Supply line 166 continues to be vented until the fastener being
tightened reaches the selected torque and the torque responsive
shut-off mechanism 30 closes valve 58 (see FIG. 2), interrupting
the flow of air to the right-hand side of valve assembly 150
through passage 62. At this point the pressure on the right-hand
side of valve assembly 150 decreases to atmospheric because the air
remaining in passage 62 escapes through passages 64 and 66 and
motor 22 to the exterior of the tool.
Line pressure continues to be exerted on the left-hand side of the
valve assembly by air flowing through passage 164. The force
exerted by this air overcomes the oppositely directed force exerted
by spring 158. Accordingly, the valve assembly shifts to the right
from the FIG. 1 position to that shown in FIG. 2.
With the valve assembly in the FIG. 2 position, valve member 180 of
the assembly engages a seat 182 in valve block 56. This interrupts
the flow path between air supply line 166 and vent passage 174 and
permits air to flow from chamber 54 through passage 164, the bore
152 in valve block 56, passages 170 and 168 in the valve block and
casing section 24a, and elbow fitting 183 into the supply line.
The illustrated marking unit 34 is actuated by this flow of air
under pressure into supply line 166. The marking unit is of a
commercially available construction and will, accordingly, not be
described in detail herein. Generally speaking, however, it
includes supply line 166; a reservoir 184 fixed to the angle head
section 24c of casing 24; and a valve 186, which is mounted in the
lower end of the tool spindle 28. A centrally located passage 188
provides communication between the interior of the reservoir and
valve 186. A threaded cap 189 can be removed to fill the reservoir
with an ink, dye, or other marking fluid.
A free piston 190 is slidably mounted in the reservoir. An O-ring
192 carried by the piston keeps the marking fluid from leaking past
it into air supply line 166, which extends through end wall 194 of
the reservoir to its interior. The O-ring similarly keeps air from
leaking past the piston into the reservoir.
The compressed air which flows into supply line 166 when the
fastener being tightened reaches its selected torque and valve
assembly 150 is moved to the right to the FIG. 2 position continues
though the supply line to the interior of reservoir 184. Here, it
impinges upon piston 190, moving the latter to the right in the
reservoir as shown in FIG. 1. This forces a small amount of fluid
from the reservoir through passage 188 and past valve 186 onto the
fastener. This provides a visual indication that the fastener has
been correctly tightened.
The tightening of the fastener and operation of the shut-off and
signal generating mechanism and marking unit 34 is followed by the
release of lever 76, which stops the flow of air to the tool, and
the removal of the tool from the fastener.
When lever 76 is released, the interior of the tool is vented to
atmosphere through a passage 198 in casing section 24a and passages
200 and 202 in fitting 82 because the release of the lever moves an
annular recess 204 in the plunger into alignment with passage 200
(see FIG. 2), permitting the air to flow around the plunger through
the passage. As the pressure in the tool drops to atmospheric, the
force keeping valve assembly 150 in the FIG. 2 position decreases;
and spring 158 shifts the valve assembly to the left to the FIG. 1
position. This vents marking unit supply line 166 in the manner
discussed previously, terminating the operation of the marking unit
because there is no longer any energy available to force the
marking liquid past valve 186.
In addition to resetting valve assembly 150, the release of lever
76 and consequent venting of the tool interior permits valve disc
58 to return to the open position shown in FIG. 1. Specifically,
the valve stem assembly 126 is biased to the left as shown in FIG.
1 by a weak spring (not shown). The force exerted by this spring is
not sufficient to overcome the valve-closing force exerted on the
valve disc when line pressure is present on valve face 140.
However, when the tool is vented and the pressure on valve face 140
drops to atmospheric, the spring can exert sufficient force to open
the valve.
The final step in the fastener tightening cycle, the removal of the
tool from the fastener, resets torque responsive shut-off mechanism
30. When the tool is removed from the fastener, spring 105 unwinds;
and input assembly 92 of brake 26 rotates relative to output shaft
96 in the direction opposite to that producing the energy absorbing
function. This threads operator 104 to the right along output shaft
96, returning the operator to the position shown in FIG. 1.
As this occurs, spring loaded pin 134 pivots pawl 128 in a
counterclockwise direction until operator 104 reaches the FIG. 1
position. Here the pin biases lower leg 147 of the pawl against an
annular ledge 205 in the operator. This aligns upper leg 148 of the
pawl with the right-hand end of previously reset valve stem
assembly 126 to keep valve disc 58 open until the torque responsive
shut-off mechanism in again actuated.
One of the important and novel features of the tool 20 just
described is that marking unit 34 cannot be actuated to provide a
visual indication of a tightened fastener even though the operator
may accidentally or purposely release lever 76 before the operating
cycle is completed. Unless the fastener is tightened to the
selected torque, the torque responsive shut-off mechanism 30 cannot
actuate and valve 58 cannot close. Thus, irrespective of the
improper manipulation of lever 76, valve assembly 150 will stay in
the FIG. 1 position; marking unit supply line 166 will remain
vented to atmosphere; and there will be no force available to expel
the marking fluid past valve 186.
As indicated previously, a visual mark of the type just discussed
may be placed alongside the fastener instead of directly on it.
FIG. 3 illustrates a tool 206 which provides the latter type of
marking. This tool is quite similar to the tool 20 described
previously except for its marking unit 208. Accordingly, tool 206
will be described only to a limited extent.
Like that identified by reference character 34, marking unit 208 is
of a commercially available type. And its details are not critical
to the practice of the present invention. Therefore, it similarly
will not be described in detail.
Referring now to FIG. 3, marking unit 208 includes a pump unit 210
connected to a marking fluid reservoir (not shown). The pump unit
is also connected to a line 212 terminating in a tip 214 in which a
jet orifice is formed. The tip of the supply line is secured to the
right angle section 24c of the tool casing by a strap or band
216.
Marking unit 208 is actuated in the same manner as marking unit 34;
i.e., by supplying a pulse of air under pressure to the marking
unit when the fastener being tightened reaches the selected torque.
This causes pumping unit 210 to propel a small quantity of marking
fluid from the reservoir through line 212 and the jet orifice in
tip 214 onto the workpiece adjacent the fastener which has been
tightened.
In the embodiments of the invention described previously a
compressed air signal is generated when the fastener being
tightened reaches the selected torque. In contrast, in the tool 218
shown in FIG. 4, an electrical signal is produced to indicate that
the fastener has been tightened to the correct torque.
Tool 218 also provides a signal indicative of the length of time
for which the fastener was tightened. As discussed above, such a
signal is beneficial in that it can be employed to differentiate
cross threaded and other improperly tightened fasteners from those
which have been correctly tightened to the selected torque.
In most respects, fastener tool 218 is similar to the tool 20
described previously. To the extent that the two tools are alike,
the same reference characters will be employed to identify their
components.
The most significant difference in tools 20 and 218 is in their
signal generating units. The major components of the signal
generating system 220 employed in tool 218 are two reed switches
222 and 224, reed switch actuators 226 and 228, and a timer which,
in the illustrated embodiment of the invention, is an R-C timing
circuit including a resistor 230 and a capacitor 232 (see FIG.
5).
Reed switches 222 and 224 (shown only diagrammatically in FIG. 4)
are mounted in recesses 234 and 236 formed in valve block 56.
Actuators 226 and 228 are slidably mounted in these passages in
alignment with the reed switches. Each of the actuators carries on
O-ring 238, which keeps air from leaking past it.
The actuators are biased to the left as shown in FIG. 4 by
compression springs 240 and 241. These springs extend between
annular ledges 242 on the actuators and internal shoulders 244 and
246 in bores 234 and 236, respectively.
The right-hand portions 247 of actuators 226 and 228 are made of a
magnetic material. The magnets are so poled with respect to
switches 222 and 224 that the displacement of an actuator to the
right will cause the associated switch to transfer from the
position shown in full lines in FIGS. 4 and 5 to the position shown
in dotted lines. The subsequent return of the actuator to the
position shown in FIG. 4 allows the associated reed switch to
restore to the full line position.
Tool 218 operates in generally the same manner as the tools 20 and
206 described above. Depression of lever 76 toward tool casing 24
allows air to flow from hose 248 through fitting 44 and past valves
48 and 58 into the motor 22 of the tool. Air also flows from the
chamber 54 in valve block 56 through passages 249 and 250,
producing line pressure against the left-hand ends of switch
actuators 226 and 228.
On the right-hand side of actuator 226, the passage 234 in which it
is mounted is vented to atmosphere through a passage 251 extending
through valve block 56 and casing section 24a to the exterior of
the tool. Accordingly, there is only atmospheric pressure on the
right-hand side of the actuator. There is consequently a force
differential which moves the actuator to the right against the bias
exerted by spring 240, causing switch 222 to transfer to the dotted
line position.
Line pressure is exerted on the right-hand as well as the left-hand
side of switch actuator 228 when lever 76 is depressed as the
compressed air flows past disc valve 58 and through passage 252
into passage 236 on the right-hand side of the actuator. Thus, the
line pressure generated forces are substantially equal on both
sides of actuator 228; and spring 241 keeps this actuator in the
illustrated position. Switch 224 accordingly remains in the
untransferred, full line position.
With switches 222 and 224 positioned as just described the R-C
timing circuit is connected across a six volt voltage source
254.sup.3 by lead 256, switch 222, lead 258, switch 224, and lead
260. Therefore, concurrently with the energization of motor 22,
capacitor 232 begins to charge. Capacitor 232 continues to charge
as the fastener is tightened.
When the fastener reaches the selected torque, disc valve 58 is
closed by operation of a torque responsive shut-off mechanism as in
the embodiments of the invention described previously. This shuts
off the supply of air to the motor and prevents further tightening
of the fastener.
Also, with valve 58 seated, air can no longer flow through passage
252 to the right-hand side of switch actuator 228. Instead, the
pressure on this side of the actuator drops to atmospheric, the air
bleeding from passage 236 through passage 252; passages 62, 64, and
66; and motor 22 to the exterior of the tool.
As this occurs, a force differential is created across actuator 228
as line pressure continues to be applied to its left-hand end. The
actuator accordingly moves to the right against the bias exerted by
spring 241. This causes switch 224 to transfer to the dotted line
position of FIGS. 4 and 5.
The transferring of switch 224 interrupts the continuity of the
charging circuit. Accordingly, capacitor 232 is left with a charge
which constitutes a signal indicative of the length of time for
which motor 22 has been run and the fastener been tightened. Also,
the transfer of switch 224 is a second signal which indicates that
the fastener has been tightened to the selected torque and the
shut-off mechanism actuated.
The length of time for which the motor 22 was run and the fastener
tightened can be ascertained by measuring the voltage across
terminals 262 and 264. This will typically be done automatically by
an appropriate computer, which will also record the running time.
Alternate schemes for measuring the running time or for both
measuring and recording it may, however, equally well be employed.
For example, the running time can be ascertained simply by
connecting a voltmeter calibrated in time across the terminals; and
the time can be recorded manually.
Whether or not the shut-off mechanism has actuated and switch 224
transferred is determined by completing a circuit across terminals
266 and 268. If actuation has occured, continuity can be
established in and current will flow through a circuit across power
source 254 which includes lead 256, lead 270, the two terminals,
lead 272, switch 224, and lead 260.
Again, a computer will typically be utilized to complete the
circuit across the contacts and to then determine and record
whether there is a 6 volt signal indicative of shut-off mechanism
actuation and correct torquing of the fastener. The computer can
easily be programmed to identify the joint as suspect if the 6 volt
signal does not appear, to subsequently ascertain the running time
if the signal does appear, and to then identify the joint as
suspect if the running time is not within established limits or as
satisfactory if the running time is within those limits.
Again, alternative methods of ascertaining whether the fastener was
tightened to the selected torque can be utilized. For example, a
meter can be connected across terminals 266 and 268 and the
presence or absence of current flow through the circuit noted and
manually recorded. Or, if recording is not required, the sequence
of steps described in the preceding paragraph and the
identification of satisfactory and suspect joints can be
accomplished by using relatively simple logic circuits.
As will be apparent from the foregoing, tool 218 in simple fashion
makes it possible to readily ascertain that the fastener tightened
is at least obstensibly correctly torqued. The time for which the
fastener was tightened can be ascertained with equal ease.
Accordingly, both correct torquing and differentiation between
correctly tightened and cross threaded or otherwise improperly
tightened fasteners are furnished by tool 218.
As with the tools described previously, the release of manual
operating lever 76 and the subsequent removal of the tool from the
fastener reset the internal components for a subsequent cycle of
operation.
When handle 76 is released, all air passages on the left-hand side
of the previously closed disc valve 58 are discharged to
atmosphere. Specifically, line pressure air is exhausted through
passage 198 in valve block 56 and passages 200 and 202 in plunger
guide 82 because continuity is established in passage 200 through
the annular recess 204 in plunger 80 as the latter is returned to
the illustrated position by spring 72.
Springs 240 and 241 return actuators 226 and 228 to the left to the
illustrated positions; and switches 222 and 224 accordingly
transfer back to their full line positions. The transfer of the
switches permits capacitor 232 to discharge through a circuit
including the lead 256 in which the capacitor and resistor are
interposed; switch 222; and leads 272, 274, and 256.
The subsequent removal of the tool from the fastener effects the
reopening of disc valve 58 and the resetting of the shut-off
mechanism in the manner discussed above in conjunction with tool
20.
As in the case of tool 20, the generation of the signals indicative
of a correctly tightened fastener cannot be adversely effected by
the improper manipulation of lever 76, either accidentally or
purposely. Switch 224 cannot be transferred to indicate the correct
torquing of a fastener until the torque responsive shut-off
mechanism operates. Consequently, unless the fastener is tightened
to the selected torque, this mechanism is not actuated, regardless
of the number of times lever 76 is depressed and released.
Therefore, manipulation of lever 76 will not, without more, result
in the generation of a signal indicating that a fastener has been
correctly torqued.
Also, if the operating lever is improperly released, switch
actuator 226 restores to the position illustrated in FIG. 4 in the
same manner as when the lever is properly released at the end of
the tightening cycle. Capacitor 232 then discharges and can charge
again only when the lever is subsequently depressed.
Thus, if the lever is released before the end of the tightening
cycle, the running time indicative charge on the capacitor will be
much lower than if the lever had been properly manipulated. When
the shut-off mechanism is eventually actuated and the running time
determined, the running time will indicate that the joint is
suspect. The joint can, accordingly, be checked to ascertain
whether the unduly short running time is a result of improper
manipulation of the tool or of the presence of a cross threaded
fastener or other defective joint.
It will be apparent to those skilled in the arts to which the
present invention pertains that the pneumatic and electrical
signals generated in the above-described tools do not necessarily
have to be utilized as described or suggested above. For example,
both the pneumatic and electrical signals generated by the
illustrated tools may be employed to operate a punch or a plunger
driven applicator of the type described in the Lance and Dunlap
patents identified above or be otherwise employed.
Or signals of one character may be generated while the fastener is
being tightened and signals of a diverse character generated when
the torque responsive mechanism is actuated. As an example, the
exhaust side of the motor 22 in tool 20 can be connected through a
line to aperture 174 in casing section 24a. In this modification a
relatively low, exhaust pressure signal is supplied to line 166
until torque responsive shut-off mechanism 30 actuates. Upon
actuation of the shut-off mechanism a higher, line pressure signal
is supplied to the supply line in the manner described above in
conjunction with the operation of tool 20.
Also, signals other than those of electrical or pneumatic character
may be generated as long as the tool in which the invention is
realized is capable of generating a signal which will indicate that
a fastener has been tightened to a selected torque or will generate
such a signal in combination with one indicative of the length of
time for which the fastener was tightened. Furthermore, it will be
apparent that the principles of the present invention can be
employed in fastener tools generally, not just in the nut runners
illustrated and described herein.
Accordingly, to the extent that embodiments of the invention other
than those described above and illustrated in the drawing are not
expressly excluded from the appended claims, they are fully
intended to be covered therein.
The invention may be embodied in other specific forms without
departing from the spirit or essential characteristics thereof. The
present embodiments are therefore to be considered in all respects
as illustrative and not restrictive, the scope of the invention
being indicated by the appended claims rather than by the foregoing
description, and all changes which come within the meaning and
range of equivalency of the claims are therefore intended to be
embraced therein.
* * * * *