Tactile engaging wrenching mechanism

A tactile engaging wrenching tool adapted for use in the installation of blind bolt fasteners. The wrenching tool includes a wrench adaptor for engaging the fastener screw and a nose-piece for holding the fastener head while the screw is turned to set the fastener. A clutch assembly is provided which transmits a light torque load to the wrench adaptor while the nose-piece is engaging the nut head. The clutch assembly is designed to provide a high torque load to the wrench adaptor to turn the screw and seat the fastener only after the nose-piece has been biased into a secure engagement with the fastener. The wrenching tool mechanism is especially well-suited for use in systems for automatic installation of blind bolt fasteners.

BACKGROUND OF THE INVENTION 
The present invention relates generally to mechanisms and tools for the 
installation of fasteners such as blind bolt fasteners or rivets. More 
particularly, the present invention relates to mechanisms for automatic 
installation of the fasteners. 
Blind bolt fasteners are commonly used for fastening sheet metal and other 
structures together. The fasteners typically includes a nut in which a 
screw is mounted. Installation of the fastener is accomplished by 
inserting the fastener into a common opening in the structure(s) to be 
fastened and turning the screw relative to the nut to deform the fastener 
in a manner to fasten the structures together. 
In general, the fastener must have two wrenching surfaces which are engaged 
by the installation tooling. These wrenching surfaces typically include 
two flat portions on the end of the screw and a Phillips-type recess in 
the head of the nut (see FIG. 1A). To install this type of fastener, a 
non-rotating nose-piece is inserted into the Phillips-type recess in the 
head of the nut and a rotating driver or wrench adaptor located inside of 
the nose-piece engages the flats on the screw. The screw is then rotated 
relative the nut-head to install the fastener. 
With hand-held tooling, the proper alignment of the nose-piece and wrench 
adaptor on the fastener presents no problem. The person installing the 
fastener inserts it in the hole in the sheet metal or other structure and 
then carefully adjusts the position of the nose-piece and wrench adaptor 
so that both wrenching surfaces are securely engaged. The air motor or 
other drive mechanism is then turned on to install the fastener. 
In many situations, automatic installation of fasteners is desirable. 
Automatic installation of the fasteners presents problems which are not 
encountered when the fasteners are manually installed. More particularly, 
during automatic installation of fasteners, the fastener is automatically 
placed in a pre-drilled hole in the sheet metal or other surface to be 
fastened. The wrench adaptor inside the nose-piece must be rotating when 
the wrenching tool is connected to the fastener in order to align its 
internal drive recess with the flats on the screw. When the wrench adaptor 
does engage the screw, it causes the fastener to rotate in the hole before 
the nose-piece engages the recess in the head of the nut. As the 
nose-piece moves into engagement with the spinning nut, the Phillips-type 
recess can be distorted and damaged. Many times, the nose-piece will strip 
or machine the Phillips-type recess to such an extent that the damaged 
fastener cannot be installed. When this happens, the automatic equipment 
must be shut down and the damaged fastener removed by hand. 
It would be desirable to provide a wrenching tool which can be used for 
automatic installation of fasteners which automatically and positively 
engage both the wrench adaptor and nose-piece with the fastener to drive 
the fastener into place without damaging the recess in the nut head. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, a tactile engaging wrenching tool 
is disclosed which is particularly well-suited for automatic installation 
of blind fasteners. The wrenching tool overcomes the above mentioned 
problems and provides a mechanism which automatically aligns with and 
positively engages both the fastener screw and nut to achieve automatic 
fastener installation without damaging the fastener. 
The present invention is based upon a tactile engaging wrenching tool which 
includes a wrench adaptor having a bottom end adapted to engage the wrench 
portion of the fastener screw to provide common only rotation of the screw 
and wrench adaptor. A nose-piece is provided having a bottom end adapted 
to engage the nut head recess to hold the nut head stationary while the 
wrench adaptor is engaged to and turns the screw to install the fastener. 
Means for biasing the nose-piece bottom end against the nut head recess to 
provide positive engagement of the nose-piece with the nut head is 
provided. The biasing means are operable between a biased position in 
which sufficient force is exerted by the nose-piece against the nut head 
recess to provide positive engagement and an unbiased position. 
The wrenching tool in accordance with the present invention further 
includes a drive motor which is connectable to the wrench adaptor to 
provide the necessary torque to turn the screw when the nut is held 
stationary. Variable torque transfer means are provided for connecting the 
drive motor to the wrench adaptor with the variable torque means being 
operable between a low torque transfer mode and a high torque transfer 
mode. As a particular feature of the present invention, the variable 
torque transfer means is operable in the high torque transfer mode only 
when the nose-piece biasing means is in the biasing position to ensure 
positive engagement of the nose-piece with the fastener. Prior to the 
positive engagement of the nose-piece with the nut head, the variable 
torque transfer means remains in the low torque transmission mode. In this 
low torque transfer mode, the wrench adaptor, when connected to the screw, 
turns the nut into alignment for engagement with the nose-piece. Once the 
nose-piece engages the nut, the wrench adaptor stops turning until the 
nose-piece is positively engaged with the nut. Once the nose-piece is 
positively engaged due to the nose-piece biasing means, greater torque 
transfer from the drive motor is provided by the variable torque means to 
turn the screw and seat the fastener. 
The above-discussed and many other features and attendant advantages of the 
present invention will become apparent as the invention becomes better 
understood by reference to the following detailed description when 
considered in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION 
An exemplary embodiment of a preferred tactile engaging tool for automatic 
installation of fasteners is shown generally at 10 in FIGS. 1 and 2. An 
exploded view of the wrenching tool mechanism is shown in FIG. 3. 
The wrenching tool is designed to install fasteners of the type shown 
generally at 12 in FIG. 1a. The fastener 12 includes a screw 14, nut 16 
and collar 18. The screw 14 includes a wrench portion 20 which has flats 
22. Screws having wrench portions with hexagonal cross sections or splines 
instead of flats are also suitable. The nut 16 includes a head portion 24 
in which a Phillips-type recess 26 is provided. The screw 14 is threaded 
through the nut 16 and connected at its lower end to collar 18. The nut 
can also be a hex head or other configuration which allows mating 
engagement with a socket. 
To install the fastener 12, it is first inserted into a common opening in 
the structures which are to be fastened together and then the screw 20 is 
turned relative the nut 16 to pull collar 18 up against the nut 16 to 
provide the desired deformation of the collar which results in fastening 
of the structures together. 
A fastener of the type shown in FIG. 1a is depicted in FIGS. 1 and 2 at 28. 
In FIG. 2 the fastener 28 is shown in position to fasten two plate 
structures 30 and 32 together. The fastener 28 is shown inserted through a 
common opening in plates 30 and 32 with the fastener nut being of 
sufficient length so that when the collar is deformed, it will securely 
fasten the plates together. 
The wrenching tool 10 is especially well-suited for use in the automatic 
installation of fasteners. Accordingly, an automatic positioning device 34 
is provided for positioning the fastener 28 for installation. Any suitable 
automatic positioning device can be utilized so long as it provides quick 
and accurate placement of the fastener 28 without interfering with the 
action of the wrenching tool 10 or the structure to be joined 30 and 32. 
The wrenching tool 10 basically includes an outer housing 36 which is 
connected to a drill motor 38 by way of a collar 40 and screws 42. The 
drill motor may be any suitable drive means such as an air driven or 
electrically driven drill. The drill motor 38 includes a rotor shaft 44 
which is connected by way of a threaded engagement to drive shaft 46. The 
drive shaft 46 includes an opening 48 which has a hexagonal cross section 
as best shown in FIG. 6. Hex spline 50 includes a main body portion 52, 
conical clutch face 54 and internal cavity 56. The main body portion 52 of 
the hex spline is hexagonally shaped so that it slidably fits within the 
drive shaft opening 48. A spring 58 is positioned within the internal 
cavity 56 to bias the conical clutch surface 54 against a mating conical 
clutch surface 60 in slip clutch or transfer shaft 62. 
The slip clutch 62 is connected for common rotation only to the wrench 
adaptor 64 by way of slip clutch adaptor 66 and connecting pins 68 and 70. 
The connecting pin 68 is mounted within groove 72 in the slip clutch. The 
groove is angled as best shown in FIG. 3 to absorb a portion of the shock 
transmitted from drive shaft 46 to the wrench adaptor 64 when the drive 
shaft 46 directly engages slip clutch 62 as will be described below. 
The slip clutch 62 includes an internal cavity 74 in which a spring is 
housed for biasing the conical clutch surface 60 against the conical 
clutch surface 54 of hex spline 50. 
As shown in FIG. 1, the drive shaft 46 is connected to the wrench adaptor 
64 through the clutch surfaces 54 and 60. The amount of torque transmitted 
from the drill motor 38 to the wrench adaptor 64 will therefore be 
determined by the nature of the surfaces, the contact surface area between 
the conical surfaces 54 and 60 and the amount of spring 75 biasing 
provided by springs 58 and 75. Preferably, the amount of torque 
transmitted through the conical clutch surfaces 54 and 60 to the wrench 
adaptor 64 should be sufficient to turn the screw 14 while the nut 16 is 
free to rotate. However, once the nut 16 is held stationary by engagement 
with the nose-piece 80, the conical clutch surfaces 54 and 62 should slip 
relative each other to reduce the possibility of damage to the 
Phillips-type recess 26 as the nose-piece 80 is inserted into the nut head 
24. 
The wrench adaptor 64 may be provided with any convenient means for 
engaging the fastener screw. Typically, the wrench adaptor 64 will have an 
oblong opening 78 as best shown in FIG. 12 for mating engagement with the 
flat portions, such as flats 22, on conventional fastener screws. 
The nose-piece 80 is securely mounted to the outer housing 36 by way of a 
threaded engagement with sliding housing 82. The sliding housing 82 is 
secured to the outer housing 36 by way of set screw 84 which is mounted 
within slot 86 to allow longitudinal movement only of the nose-piece 80 
relative the outer housing 36. The nose-piece 80 includes a lower portion 
having protrusions 88 designed to engage the Phillips-type recess 26 in 
fastener 28 (see FIGS. 13 and 14). The nose-piece 80 further includes a 
central passageway 90 through which the wrench adaptor 64 may travel 
longitudinally for engagement with the fastener screw 20. 
As shown in FIG. 1, the wrenching tool 10 is positioned over the fastener 
28 with the wrench adaptor being turned by the drill motor 38 via the 
above described clutch assembly arrangement. The nose-piece 80 does not 
rotate since it is securely connected to housing 36. The wrenching tool is 
moved downward toward the fastener so that the wrench adaptor 64 engages 
the fastener 28 as shown in FIG. 2. At this point, the entire fastener 
begins turning. The wrenching tool 10 is continually moved downward until 
the nose-piece 80 aligns with and engages the Phillips-type recess 26. At 
this point, the fastener is held stationary so that the conical clutch 
surface 54 which is driven by motor 38 begins to slip relative the conical 
clutch surface 60 which is now stationary. The amount of torque 
transmitted to the wrench adaptor will remain at this low level until the 
nose-piece 80 is biased securely into the Phillips-type recesses 26. 
Nose-piece biasing spring 92 is mounted within spring housings 94 and 96. 
Spring housing 96 is secured to outer housing 36 by way of set screw 98 
and slot 100. As the wrenching tool 10 is continually moved downward 
against fastener 28, the sliding housing 82 is forced against spring 
housing 96, resulting in compression of spring 92. The compression of 
spring 92 biases and holds the nose-piece 80 in its engagement with the 
fastener nut head 24. The spring 92 is designed to provide sufficient 
biasing when compressed (as shown in FIG. 2) to prevent the nose-piece 80 
from slipping out of or otherwise disengaging from the Phillips-type 
recesses in fastener 28. 
As the sliding housing 82 and spring housing 96 are moved upward into their 
compressed positions as shown in FIG. 2, the slip clutch 62 is also moved 
upward into contact with drive shaft 46. The slip clutch 62 includes tabs 
102 which are designed to engage slot 104 in drive shaft 46 (FIG. 3). The 
engagement of tabs 102 with slot 104 provides a direct connection between 
the drill motor shaft 44 and the wrench adaptor 64. The amount of torque 
provided by the drill motor is sufficient to turn the screw 20 while the 
nut 16 is being held stationary by nose-piece 80 to thereby deform the 
collar 18 into the desired shape for fastening. 
As can be seen, the above described mechanism provides the transfer of 
variable torque to the wrench adaptor 64. When the wrenching tool is in 
the position shown in FIG. 1, the amount of torque transferable to the 
wrench adaptor 64 is limited to a low level by the clutch-type engagement 
between hex spline 50 and slip clutch 62. When the wrenching tool 10 is 
moved to the position shown in FIG. 2, wherein the nose-piece 80 is 
positively and securely biased into the Phillips-type recesses in the nut 
16, the slip clutch 62 is directly connected to the drive shaft 46 to 
provide the increased torque necessary to deform the fastener. The direct, 
no slip engagement of slip clutch 62 to drive shaft 46 occurs only after 
the nose-piece 80 has been biased by spring 92 into positive engagement 
with the fastener 28. By applying increased torque to the screw only after 
secure positioning of the nose-piece into the Phillips-type recesses 
overcomes the previously mentioned problems wherein the fastener nut is 
damaged during insertion of the nose-piece into the fastener head. 
Having thus described exemplary embodiments of the present invention, it 
should be noted by those skilled in the art that the within disclosures 
are exemplary only and that various other alternatives, adaptations and 
modifications may be within the scope of the present invention. For 
example, instead of a recess being provided in the nut for engagement with 
the nose piece, the nut may be shaped as a hex head or other conventional 
nut head shape for engagement with a mating socket located on the nose 
piece. Accordingly, the present invention is not limited to the specific 
embodiments as illustrated herein, but is only limited by the following 
claims.