Locking collar removal tool

A tool to remove a locked collar locked to the threaded shaft of a frangible fastener, having a collet with gripping means and inner grasping teeth has a segment removed to permit the collet to decrease in size. An outer cylinder with inner threads are sloped contrary to the threads locking the collar to the fastener shaft and a bottom inner tapered portion. An inner cylinder with matching threads and torquing means is torqued with respect to the outer cylinder to translate within the outer cylinder, urging the collet within into inner beveled portion of the outer cylinder thereby closing the collet to surround and grasp the locked collar. While the shaft of the fastener is held, further torquing imparts rotational force to the collar in an opening direction.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates generally to metal working tools used to 
remove fasteners and more specifically to tools used to remove locking 
collar fasteners. 
2. Description of the Related Art 
A locking collar fastener system, sometimes called a frangible fastener or 
"HI-LOK" is used in environments of high vibration, such as on aircraft. 
The locking collar fastener system is used wherever a rivet can be used to 
join parts together. 
The frangible fastener system utilizes a first piece comprising a threaded 
shaft on one end and an exposed retaining ring at the other end. A passage 
is drilled through the parts to be fastened, typically large sheets of 
metal, such as aircraft surfaces and boats. The threaded shaft portion of 
the fastener is inserted through the aligned passages to the exposed 
retaining ring. Often the surface of the part to be fastened is indented 
at the hole consistent with the retaining ring to provide a flat outer 
surface at the area of the retainer ring. A matching threaded locking 
collar is hand rotated upon the threaded portion of the shaft, then 
controllably torqued with a wrench. The threaded locking collar joins to a 
wrenching ring by a notched neck which shears from the collar at a 
predetermined torsional loading during the torquing. The threaded locking 
collar having an upset portion, usually a slightly elliptical shape 
provides a frictional spring lock to prevent the locking collar from 
untreading or loosening, even in environment of high vibration and stress. 
The collar remains locked to the fastener shaft even when the residual 
tension on the fastener is lost. Exposed on each side of the parts 
obscuring the passage, on one side is the outer portion of the retaining 
ring that may be recessed and on the other side, the almost round locking 
collar. 
The Problem of Removal 
The removal of the HI LOK and other frangible fasteners without damage to 
the part attached often presents a challenging problem but is needed for 
many useful reasons. nO the HI LOK type frangible fastener, an hexagonal 
opening at the end of the shaft of the locking collar fastener is 
sufficiently recessed in depth to receive a standard allen wrench for the 
purpose of retaining the shaft in position with respect to the locking 
collar during removal. 
The removal of the locked collar from the shaft is usually difficult, but 
necessary for repair and maintenance of the joined parts. To accomplish 
this, heretofore, drilling means such as a drill bit manual, electric or 
air-motor are used to drill out the center of the shaft portion or a 
cutting means such as a hack-saw is used to cut the collar. In either 
case, this activity weakens the fastener. Then the parts of the collar are 
pried, chiseled or twisted off to expose the shaft portion of the fastener 
within the passage. Then a knock-out pin is used to force the shaft from 
the passage. The problem with this method is the time it takes to drill or 
cut and manipulate the collar in order to expose then remove the shaft 
from the passage. Furthermore, scars from the removal operations and 
consequential weakening to the parts surrounding the passage may create 
problems in refastening the parts using the same passage. 
Ongoing efforts have been made to improve the means to remove these types 
of fasteners without causing damage. Such efforts have been addressed both 
to the general object of improving the manner of removal of the frangible 
fasteners as well as the speed that these fasteners may be removed without 
damage to the parts fastened. Because the frangible fasteners are designed 
to hold parts together under environments of extreme stress and vibration, 
until my invention no practical, universally adaptable tool was known to 
address the removal of frangible fasteners. 
BRIEF SUMMARY OF THE INVENTION 
My tool is designed to grasp the almost round collar then rotate it with 
respect to a shaft portion of the fastener until the collar disengages. 
The tool comprises an outer cylinder having a lower inner tapered section 
and an upper inner threaded portion, the taper section portion of the 
cylinder having a smaller diameter then the upper inner threaded portion 
of the outer cylinder. The inner cylinder is torqued with respect to the 
outer cylinder to turn the tool in the direction that will loosen the 
collar from the fastener. An inner cylinder having an circular lower 
portion and an upper outer threaded portion matching the upper inner 
threaded portion of the other cylinder translates movement of the inner 
cylinder within the outer cylinder, tapered within. A collet comprising a 
semi-cylindrical harden metal piece located at the bottom rim of the inner 
cylinder within the tool translates the movement of the inner cylinder 
with respect to the outer by moving through the bottom inner tapered 
section of the outer cylinder, to close. When the tool is in place, the 
collet seats to surround the collar, the torquing movement compresses the 
collet to surround and then compress the circumference of the collar, the 
collet locking onto the collar. Further torquing of the inner cylinder 
translates the torque tangentially to the collar to turn only the collar 
with respect to the shaft portion of the fastener. Teeth oriented within 
the collet further grasp the collar to prevent slippage. Outside 
stirations or indentations oriented parallel to the center axis of the 
collet along the outer service of the collet may be used to assist the 
collet to flex as it surrounds the collar. 
These features allow for a very short collet with a longitudinal slot along 
the entire length of the collet so that my tool can be short and squat to 
fit into any area that a locking collar is used. Furthermore, my tool 
provides a collet that flexes laterally instead of the longitudinally 
flexing teeth of other tools. This useful feature of my invention 
eliminates jamming and the use of spring loaded disks and knock-out pins 
of some other tools. With my invention, the collet is urged towards a 
taper area to pull the tool away from the fastened parts, instead of being 
pulled torward the fastened parts as other devices work. 
Accordingly, it is a general object of the present invention to provide a 
tool designed to remove frangible fasteners without damage to the parts 
fastened. 
More specifically, it is an object of the present invention to provide a 
means to torque the collar of the fastener with respect to the shaft 
portion of the fastener without cutting, bending or deforming the 
fastener. 
It is also an object to provide a tool that is small, can be conveniently 
stored when not in use, can be used with commonly available tools such as 
standard socket wrenches, allen wrenches and the like. 
It is another object of the present invention to attain the foregoing 
objects and also to provide an improved means to quickly remove a 
frangible fastener without need to use power tools, such as electric or 
air hammers, electric torquing means and the like using a compact unit 
that can be used many times without damage to the underlying parts. 
Further objects and advantages of my invention will become apparent from a 
consideration of the drawings and ensuing description thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIG. 1, my locking collar removal tool 1 features a recess 11 
to receive a standard rachet or wrench prong 31 of a rachet wrench 30 or 
similar levered tool outlined in this FIG. 1 and a set of standard 
hexagonal faces 12 around the circumference of the head 10 portion of the 
inner cylinder 2 to receive a standard open or closed head wrench 32. The 
head 10 of the inner cylinder 2 of the removal tool is conveniently 
torqued with either wrench 30 or 32. 
The typical HI LOK or collar fastener 4 has a shaft 42 with a recess 45 for 
hexagonal shaped allen wrenches 33 at a collar end. The length of the 
shaft could be of various lengths depending on the thickness of the parts 
50 and 51 joined. The fastener system comprises a threaded portion 41 of 
the shaft 42, a collar 40, a retaining ring 43 and a locking upset portion 
47 tapered at 27 to a bottom portion 48. The retaining ring 43 may have a 
beveled other end to permit the head of the retaining ring 43 to fit 
smoothly along the surface of part 51. 
The parts 50 and 51 were fastened by placing the shaft 42 of fastener 4 
within aligned passages 44, the shaft 42 inserted through up to the 
retainer ring 43 at the end of the fastener 4. FIG. 5 shows the surface 51 
cut away to permit the beveled portion of the fastener retaing ring to 
seat therein. A locking collar 40 with wrenching ring (not shown) was then 
torque on the threaded portion of the shaft, the collar 40 moving along 
the threaded portion of the shaft to the part 50. Further torquing then 
compressed part 50 to 51 to a predetermined shear torquing load that 
breaks the wrenching ring portion (not shown) from the collar, somewhat 
distorting the collar 40 leaving an upset portion 47 but resulting in a 
very strong fastener 4 holding the parts 50 and 51, with only the collar 
40 and upset portion 47 exposed. 
Refering to FIG. 2, counter-wise outer threads 13 on the mid-portion of the 
inner cylinder 2 match counter-wise inner threads 8 of the outer cylinder 
3, the cylinders sized so that the inner cylinder 2 can be threaded by 
rotation within the outer cylinder 3. The counter-wise direction of the 
threads refers to the direction of the slope of the threads for the 
fastener 4 to be opened. For example, if the fastener joins part 50 and 51 
by a clockwise rotation of the collar 40 along shaft 42 interacting with 
threads 41 to lock the collar, then the counter-wise outer threads 13 
would be counter-clock wise, that is in the opposite direction. This 
provides the tendency to unlock the collar at the time the tool is used, 
as will be described in the fullest details below. If the tool's threads 
13 and 8 were in the same direction as the fastener's threads 41, there 
would be a tendency to tighten the fastener 4 instead of unlocking the 
fastener 4. While the outer gripping grooves 9 are generally useful, in 
order to contruct a squat version of my tool 1, these may be eliminated. 
For example, FIG. 7 shows a squat version of my invention with the surface 
groves 9 missing, yet the outer cylinder 3 can be grasped by an open end 
wrench 32 while the inner cylinder 2 is torqued using another open end 
wrench. 
The outer cylinder shown generally as 3 having a set of standard hexagonal 
faces 6 form the outer circumference of the top portion of the outer 
cylinder to receive a standard open or closed head wrench such as 32. 
Outer gripping groves 9 form the outer circumference of the of bottom 
portion of the outer cylinder. The hexagonal faces 6 and gripping groves 9 
assists staying the outer cylinder 3 during the initial portion of the 
removal procedure and to assist the threading of inner cylinder 2 within 
the outer cylinder 3. The circumferential outer bottom edge 5 of the outer 
cylinder 3 tapered inward from the surface of the outer cylinder to the 
bottom rim 17 of the outer cylinder 3 to include a portion of the outer 
gripping groves 9. The circumferential inner bottom edge 7 (best viewed in 
FIG. 6) also tapers inward for a portion of the of the outer cylinder 3 to 
a size smaller than the outside diameter of the collar 40. The tapered 
portion 27 stops the removal tool 1 from directly contacting surface 50. 
The smooth, lower portion area 14 of the inner cylinder 2 extending from 
the threads 13 terminates to flat bottom rim 15. The diameter of the lower 
portion area 14 of the inner cylinder 2 is sized to impress upon a flat 
top rim 25, of a nearly circular collet 20 made of hardened material 
capable of a memory such as spring steel to permit the collet 20 to return 
to its original shape after deformation. This eases release of the collar 
after removal from the fastener. The collet has a outer tapered bottom rim 
24 and inner griping teeth 23 raised inward from the inner surface 22 of 
the collet 20. A gap 21 in the nearly circular configuration of the collet 
20 permits the collet to decrease in diameter when urged by the bottom rim 
15. Outer linear recesses, or flexibility indentations 28 along collet 
surface asists the harden material composing the collet to flex as it 
surrounds the collar 47. As the inner cylinder is turned counter-wise 
within the outer cylinder 3, the inner cylinder forces the collet 20 to 
move through the inner tapered bottom portion 7 of the outer cylinder 3 to 
close the gap 21 making the collet 20 smaller in diameter and to surround 
the upset portion 47. 
To operate, the tool 1 is placed verically above the fastener to be 
removed, bottom rim 17 placed to surround the upset portion 47 of the 
locked collar 40. The outer cylinder can be held in place by gripping the 
outer gripping groves 9 or if needed by use of a wench 32. A hexagonal 
shaped allen wrench 33 can be used to insert through the center opening of 
the collar 40 into the recess 45 to keep the fastener shaft 42 from 
turning as shown in FIG. 1. While holding the shaft 42 with the hexagonal 
wrench 33, the inner cylinder 2 is then torqued counter-wise using an 
open-end box wrench 32. This will force the inner cylinder 2 to move 
through the outer cylinder 3 forcing the collet 20 into the inner beveled 
portions 7 of the outer cylinder. The collet 20 continues to move within 
the beveled portion 7 until the collet completely closes upon the portion 
47 of the collar, the inner teeth 23 impressing upon the collar 40 to 
prevent slippage. Further torqueing of the inner cylinder 2 will translate 
into a torque movement to the collar 40. Since shaft 42 of the fastener is 
securly held using the allen wrench 33, the collar 40 unthreads from the 
threated shaft portion 41 of the fastener until it is off. The shaft 42 
with the collar 40 removed can then be easily removed from the parts 50 
and 51. 
Further optional features include a flexible cushion of protective material 
to cover the bottom rim 17 of the outer cylinder to reduce scratching of 
the parts 50 by the tool. The cushion prevents the bottom rim 17 from 
making direct contact with the part 50, if desired. 
Also, flexural assisting groves aligned along the outer surface of the 
collet 20 (not shown) would enable the collet 20 to flex as it changes in 
diameter through the tapered section of the outer cylinder. This may 
assist in the movement of the collet 20 through the tapered portion of the 
outer cylinder to surround the collar 40, but not necessary. 
While the above description contains many specifications, there should not 
be construed as limitations on the scope of the invention, but rather as 
an exemplification of one preferred embodiment thereof. Accordingly, the 
scope of the invention should be determined not by the embodiment 
illustrated, but by the appended claims and their legal equivalents.