U.S. patent number 3,816,902 [Application Number 05/290,349] was granted by the patent office on 1974-06-18 for method of magnetically shrink-fitting members.
Invention is credited to Andrew E. Beer.
United States Patent |
3,816,902 |
Beer |
June 18, 1974 |
**Please see images for:
( Certificate of Correction ) ** |
METHOD OF MAGNETICALLY SHRINK-FITTING MEMBERS
Abstract
Magnetostrictive fastener arrangement that relies upon the
fractional change in length of a ferromagnetic element under the
influence of a magnetic field (magnetostriction) to alter the
physical cooperating relationship between the element and a second
element. Each of the elements may exhibit the same or a different
magnetostrictive effect in the presence of a magnetic field, and
each of the elements is dimensioned so that a different physical
relationship between the elements is achieved when either or both
elements undergoes a fractional change in length.
Inventors: |
Beer; Andrew E. (New York,
NY) |
Family
ID: |
23115582 |
Appl.
No.: |
05/290,349 |
Filed: |
September 19, 1972 |
Current U.S.
Class: |
29/446; 114/116;
335/215; 411/259; 411/396; 411/929; 285/381.1; 29/525.02;
29/525.06; 29/525.08; 29/525.11; 29/426.6; 227/156; 403/273;
411/333; 411/548 |
Current CPC
Class: |
F16B
33/008 (20130101); F16B 39/00 (20130101); F16B
7/00 (20130101); F16B 1/0014 (20130101); F16B
15/00 (20130101); F16B 2/005 (20130101); F16B
4/004 (20130101); Y10S 411/929 (20130101); Y10T
29/49959 (20150115); Y10T 29/49863 (20150115); Y10T
403/48 (20150115); Y10T 29/49956 (20150115); F16B
2001/0035 (20130101); Y10T 29/49948 (20150115); Y10T
29/49824 (20150115); Y10T 29/49963 (20150115) |
Current International
Class: |
F16B
4/00 (20060101); F16B 7/00 (20060101); F16B
39/00 (20060101); F16B 33/00 (20060101); F16B
1/00 (20060101); F16B 15/00 (20060101); F16B
2/00 (20060101); B23p 011/02 () |
Field of
Search: |
;29/421M,446,447,426X,526X ;335/215X ;227/156X ;285/381X ;52/24X
;114/116X ;403/273X |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
"Magnetostriction Phenomena"-General Electric Review-Vol. 45, No.
3, pp. 161-163..
|
Primary Examiner: Moon; Charlie T.
Attorney, Agent or Firm: Brumbaugh, Graves, Donohue &
Raymond
Claims
I claim:
1. A method of engaging elements in cooperating physical
relationship at least one of which is formed of magnetostrictive
material comprising the steps of applying a magnetic field to the
magnetostrictive element to change a dimension thereof and alter
the physical cooperating relationship between the elements,
securing the elements together in a frictional engagement, and
removing the magnetic field to cause a fractional change in a
dimension of the element and provide a greater frictional
engagement between the elements to lock them together more
securely.
2. The method according to claim 1, wherein the magnetostrictive
element is a nail adapted to be driven into and engage the second
element in the presence of the magnetic field, the diameter of the
nail decreasing when the magnetic field is applied parallel to the
axis of the nail, whereby the diameter of the nail increases in the
absence of the magnetic field to provide a greater frictional
locking relationship between the nail and the second element.
3. The method according to claim 1, wherein the magnetostrictive
element is a screw adapted to be driven into and engage the second
element in the presence of the magnetic field, the diameter of the
screw decreasing when the magnetic field is applied parallel to the
axis of the screw, whereby the diameter of the screw increases in
the absence of the magnetic field to provide a greater frictional
locking relationship between the screw and the second element.
4. The method according to claim 1, wherein the magnetostrictive
element is a rivet adapted to be formed into engagement with other
elements in the presence of the magnetic field, the diameter of the
rivet decreasing when the magnetic field is applied parallel to the
axis of the rivet and whereby the diameter of the rivet increases
in the absence of the magnetic field to provide a tighter
engagement between the rivet and the other elements.
5. The method according to claim 1, wherein the magnetostrictive
element is a stud adapted to be inserted into and engage other
elements in the presence of the magnetic field, the diameter of the
stud decreasing when the magnetic field is applied generally
parallel to the axis of the stud, whereby the diameter of the stud
increases in the absence of the magnetic field to provide a greater
frictional locking relationship between the stud and the other
elements.
6. The method according to claim 1, wherein the magnetostrictive
element is a pipe adapted to be inserted into another pipe having a
coupling section, the diameter of the pipe decreasing when the
magnetic field is applied parallel to the axis of the pipe whereby
the diameter of the pipe increases in the absence of the magnetic
field to provide a greater frictional locking relationship between
the pipes.
7. The method according to claim 1, wherein the magnestrictive
element is a bolt and another element is a nut, the bolt adapted to
engage the nut in the presence of the magnetic field, the diameter
of the bolt decreasing when the magnetic field is applied parallel
to the axis of the bolt, whereby the diameter of the bolt increases
in the absence of the magnetic field to provide a greater
frictional locking relationship between the bolt and the nut.
8. The method according to claim 1, wherein the magnetostrictive
element is a bar and another element is a fitting, the bar adapted
to engage the fitting in the presence of the magnetic field, the
diameter of the bar decreasing when the magnetic field is applied
parallel to the axis of the bar, whereby the diameter of the bar
increases in the absence of the magnetic field to provide a greater
frictional locking relationship between the fitting and the
bar.
9. The method according to claim 1 wherein the magnetostrictive
element comprises a clutch formed with a receiving hole and another
element comprises a machine tool, the machine tool adapted to
engage the receiving hole of the chuck in the presence of the
magnetic field, the receiving hole increasing in size when the
magnetic field is applied, whereby the size of the receiving hole
decreases in the absence of the magnetic field to provide a greater
frictional locking relationship between the chuck and the machine
tool.
10. The method according to claim 1, wherein the magnetostrictive
element comprises a machine tool and another element comprises a
chuck formed with a receiving hole, the machine tool adapted to be
engaged by the receiving hole in the chuck, the dimensions of the
tool decreasing when the magnetic field is applied to the tool,
whereby the dimensions of the tool increases in the absence of the
magnetic field to provide a greater frictional locking relationship
between the machine tool and the chuck.
11. The method according to claim 1, wherein the magnetostrictive
element comprises a door having a lining made of magnetostrictive
material formed around the perimter of the door and another element
comprises a wall having an opening for the door, the size of the
door decreasing when the magnetic field is applied to the door,
whereby the size of the door increases in the absence of the
magnetic field to provide a greater frictional locking relationship
between the door and the wall.
12. The method according to claim 1, wherein the magnetostrictive
element comprises a wall with an opening having a lining made of
magnetostrictive material and another element comprises a door, the
size of the opening increasing when the magnetic field is applied
to the lining, whereby the opening decreases in the absence of the
magnetic field to provide a greater frictional locking relationship
between the door and the wall.
13. The method according to claim 1, wherein the magnetostrictive
element comprises a washer, another element comprises a bolt
adapted to be mounted within the washer and another element
comprises a receiving member having an aperture, the size of the
washer decreasing when the magnetic field is applied to the washer,
whereby the size of the washer increases in the absence of the
magnetic field to provide a greater frictional locking relationship
between the bolt and the receiving member.
14. The method according to claim 1, wherein the magnetostrictive
element comprises a normally curved cotter pin, partially formed of
a magnetostrictive material, and another element comprises a
receiving part having an aperture, the pin becoming straight when
the magnetic field is applied to the magnetostrictive material of
the cotter pin, whereby the length of the pin curves in the absence
of the magnetic field to provide a greater frictional locking
relationship between the cotter pin and the receiving part.
Description
BACKGROUND OF THE INVENTION
This invention relates to an improvement in fastening arrangements
and more particularly, to magnetostrictive fasteners that utilize
the principle of magnetostriction to provide enhanced holding
action.
Fasteners, such as screws, nails, studs, rivets, nuts and bolts and
the like are well known and extensively used to join materials
together. Such fasteners tend to loosen, however, especially where
the materials joined together undergo stresses and strains. Also,
certain types of fasteners are subject to corrosion. Such corrosion
action may cause the fastener to loosen because of the reduction in
its size or, may make the fastener difficult to take apart which is
necessary in the normal maintenance of machinery. Thermal expansion
of metals has been utilized to provide long term tightfitting
fasteners. For example, pipe connections are commonly made by
joining preheated and precooled pipes. There are practical
difficulties in applying the principle in other fastening
arrangements. The heating equipment needed to provide the required
temperature changes may be bulky and non-portable. Also, certain
elements to be secured, such as large metal pieces, may not readily
change their ambient temperature.
Therefore, a fastening arrangement that would fit tightly by
changing dimensions at the time of assembly or disassembly while at
the same time not requiring extensive, additional equipment would
be a valuable advance in the art of fasteners.
SUMMARY OF THE INVENTION
There is provided in accordance with the present invention a
fastener arrangement that overcomes the problems mentioned
previously. More particularly, the invention relates to a fastening
arrangement wherein at least one element of the fastener is at
least partially made of a magnetostrictive material that undergoes
shape changes in the presence of a magnetic field. Each of the
elements is so dimensioned that a different physical relationship
between the elements is implemented when either or both
magnetostrictive elements undergoes a fractional change in length
in the presence of a magnetic field of appropriate strength.
Where the fastener is a magnetostrictive screw, nail, stud, rivet,
bolt, washer, electrical connector or the like, removal of the
magnetic field after the fastener is in place causes an increase in
the diameter of the fastener. The result is that the fastener fits
more securely in the receiving holes in the elements to be held
together. Thus, the fit is more snug than with conventional
fasteners. The term fastener is meant to include any type of
arrangement where parts may be made rigid with respect to each
other. Also, a cotter pin may be made in part of a magnetostrictive
material so that the application of a magnetic field causes the
shaft of the pin to curve or be straight.
Corrosion may be reduced by fashioning the fastener of a
magnetostrictive material that has less tendency to rust. More
importantly, since the fit is more snug than conventional
fasteners, there is less tendency for corrosion because oxygen has
less surface area in which to oxidize. In addition, the usual
difficulty in removing corroded fasteners is minimized by the use
of magnetostrictive fasteners. To remove the fastener, a magnetic
field is applied to thereby decrease the diameter of the fastener
and thereby crack any corroded surface that may be present.
In another form of the invention the fastener may be a
magnetostrictive chuck for holding a machine tool in place or
alternatively, the tool itself may be made of a magnetostrictive
material. Additionally, doors with magnetostrictive lining may be
used to form a tight fitting fastening arrangement.
The additional equipment needed to cause the enhanced fastening
action consists of a suitable source of a magnetic field. Either
small permanent magnets or electromagnets may be used. In some
cases the device used to insert the fastener into place, such as a
screw driver or wrench, etc., may be modified so as to also
incorporate the source of the magnetic field .
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the invention, reference may be made
to the following descriptions of the exemplary embodiments taken in
conjunction with the following drawings in which:
FIG. 1 is a graph showing properties of some magnetostrictive
materials;
FIG. 2 is a schematic of a magnetostrictive nut and bolt
combination arranged according to the present invention;
FIG. 3 is a sectional view of magnetostrictive nut and bolt in
place arranged according to the present invention;
FIG. 4 is a sectional view of magnetostrictive rivet in place;
FIG. 5 is a sectional view of magnetostrictive nail in place;
FIG. 6 is a sectional view of a magnetostrictive screw in
place;
FIG. 7 is a view of a magnetostrictive pipe connection;
FIG. 8 is a magnetostrictive can arranged according to the present
invention;
FIG. 9 is a magnetostrictive fitting arranged according to the
present invention;
FIG. 10 is a sectional view of a magnetostrictive stud arranged
according to the present invention;
FIG. 11a is a partial sectional view of a machine tool held by a
chuck arranged according to the present invention;
FIG. 11b is a view of the machine tool and chuck taken along lines
11b of FIG. 11a;
FIG. 12 is a view of a magnetostrictive door arranged according to
the present invention;
FIG. 13 is a view of a bolt and magnetostrictive washer arranged
according to the present invention;
FIG. 14 is a view of a magnetostrictive cotter pin arranged
according to the present invention.
In the following descriptions of illustrative embodiments of
magnetostrictive devices arranged according to the present
invention, all are based on the novel application of the principle
of magnetostriction.
PRINCIPLES OF MAGNETOSTRICTION
Magnetostriction refers to the fractional change in length of a
ferromagnetic body under the influence of a magnetic field. The
three main kinds of magnetostriction are longitudinal
magnetostriction, transverse magnetostriction and volume
magnetostriction. Longitudinal magnetostriction may be either
positive (Fe-Co Alloys) or negative (Ni and Co) or may be positive
(elongate with increasing field) at low fields and negative for
large fields. Transverse magnetostriction is measured orthogonally
to the field and generally is equal to one half the longitudinal
magnetostriction and of opposite sign. Volume magnetostriction is
generally an order of magnitude smaller than longitudinal
magnetostriction.
While all ferromagnetic materials have magnetostrictive qualities,
the iron cobalt alloys (Fe-Co) appear to produce the greatest
effect. The curves of FIG. 1 indicative magnetostriction as a
function of field strength for three cold rolled Fe-Co alloys; for
the Fe 30 - Co 70 alloy, the magnetostriction is 1.2 .times.
10.sup.-.sup.4 in./in. at a field strength of 1,000 oersteds. The
thermal expansion for the same alloy for a 100.degree.F.
temperature change is 6 .times. 10.sup.-.sup.4 in./in.
Since the greatest amount of magnetostriction occurs as the
material approaches saturation, the magnet for producing the field
must be capable of producing a large enough field. The
magnetostrictive materials utilized in the present invention, such
as the Fe-Co alloys, generally do not require more than 1,000
oersteds to saturate them. When the alloys are not cold rolled, 200
oersteds may be sufficient. However, the shape of the
magnetostrictive material, which determines the demagnetization
factor, may necessitate the use of a much larger field to ensure
the magnetostrictive material is near saturation.
Permanent magnets are suitable in most applications for generating
the magnetic fields necessary to cause magnetostriction. Depending
on the application of the magnetostrictive material, various shaped
permanent magnets are available, such as horseshoe, bar, circular
or rod, depending on the direction of the magnetic field required
in relation to the structure of the magnetostrictive material.
Ceramic magnets, such as barriumferrite, are readily available and
provide field strengths from 2,000 to 3,000 oersteds. Also, Alnico
permanent magnets provide the same range of field strength. In some
applications it may be desirable to have higher field strengths.
The rare earth cobalt alloy magnets, such as platinum cobalt,
provide field strengths in excess of 3,000 oersteds.
Most permanent magnets provide the previously mentioned field
strengths in a relatively small volume of air. Therefore, where the
magnetostrictive material is relatively large, electromagnets with
or without an iron return circuit may be used. Air coils provide
field strengths of the order of 1,000 oersteds over a large volume.
Where higher fields are desirable, electromagnets with an iron
return circuit generate field strengths to 5,000 oersteds in a one
inch air gap. Electromagnets may be useful when the present
invention is utilized in industrial applications.
PREFERRED EMBODIMENTS
In the illustrative embodiment of a magnetostrictive fastening
arrangement according to the present invention, as shown in FIG. 2,
there is provided a nut and bolt combination for securing elements
(not shown) together. In the drawing, a bolt 10 with a head 11 and
external threads 12 and an internally threaded nut 14 are designed
for engaging relationship. With conventional nut and bolt
combinations, the inside diameter of the nut is somewhat larger
than the outside diameter of the bolt so that the two may be
readily joined together. Friction between the elements joined
together and the bolt and nut respectively is relied upon to
maintain a tight connection. However, in the present invention, the
bolt 10 is made of a magnetostrictive material, such as a Fe-Co
alloy, with an outside diameter that is approximately equal to the
inside diameter of the bolt. In this condition the two may not be
readily joined or if joined, separated.
A magnetic field is applied to the bolt 10 in a direction parallel
to its axis when the combination is to be assembled or separated.
This may be provided by an electromagnetic surrounding the bolt, a
specially designed tool or, where appropriate, by a permanent
magnet shaped as a horseshoe with one pole near the head 11 of the
bolt 10 and the other pole near the nut 14. The magnetic field
causes the length of the bolt to increase and the diameter to
decrease about half the increase in length. After the combination
is assembled and the field removed, the bolt 10 reassumes its
original shape. The transverse magnetostriction, along the
diameter, causes the nut and bolt to fit securely. In some
applications it may be desirable to have the nut 14 made of a
magnetostrictive material.
In FIG. 3, there is shown a sectional view of the bolt 10 and nut
14 holding a pair of elements 16 and 18 in place. Not only does
transverse magnetostriction enhance the holding action, but also,
longitudinal magnetostriction provides a tighter fit. Since the
length of the bolt 10 increases when a magnetic field is present,
the removal of the field after assembly causes the bolt 10 to
decrease its length and thereby causes greater holding pressure to
be exerted on the elements 16 and 18. Alternatively, the bolt 10
and the nut 14, instead of being formed with threads, may have
smooth engaging surfaces.
FIG. 4, indicates a magnetostrictive fastener in the form of a
rivet 20. A pair of elements 22 and 24 with matching holes receive
the rivet 20. The diameter of the rivet 20 is larger than the
diameter of the holes of the members 22 and 24. A magnetic field,
applied parallel to the length of the rivet 20, by a device similar
to that described in FIG. 2, decreases the diameter so that it may
be inserted into the bores in the elements 22 and 24. The head 20a
is then formed on the rivet in the usual manner, and when the field
is removed, the diameter of the rivet 20 increases while its length
decreases, thereby to hold the elements 20 and 24 in tighter
relationship.
As shown in FIG. 5, a nail 30 with a head 32 and a shaft 34 is made
of a magnetostrictive material. When the nail 30 is to be driven
into an element 36, such as wood, a magnetic field is provided
parallel to the shaft of the nail 30, thereby decreasing the
diameter of the nail. After the nail 30 is driven into the wood 36,
the magnetic field is removed to increase the diameter of the nail
30.
In similar manner, there is shown in FIG. 6 a magnetostrictive
screw 40. The screw 40 with threads 42 is made of a
magnetostrictive material and is shown seated in an element 44,
such as wood or metal. The screw is inserted while the magnetic
field is applied parallel to the shaft of the screw 40. The result
of this action, again after the field has been removed, is that the
screw fits more securely into the material 44 because of its
increased diameter. The magnetostrictive screw 40, along with the
other fastening arrangements, have the advantageous feature of
facilitating their removal if any corrosion should accumulate on
the fasteners over long time periods. The change in size of the
fasteners can cause the corrosion, including rust, to break
loose.
Referring to FIG. 7, there is shown an improved pipe connection
arranged according to the present invention. A pipe 52 has a
coupling section 54 adapted at one end to receive the end of
another pipe 56. In the present invention, an end 57 of the pipe 56
is made of a magnetostrictive material with a diameter
approximating the internal diameter of the coupling 54. When the
pipes are to be fitted together, a magnetic field is applied
parallel to the length of the pipe 56 which causes the end 57 of
the pipe to contract, as shown in FIG. 7, so as to allow the pipe
56 to be inserted into the coupling 54. After the magnetic field is
removed, the diameter of the end 57 of the pipe 56 increases to
cause a tight fitting pipe connection.
Referring now to FIG. 8, a can 56 has a top member 58 formed of
magnetostrictive material frictionally secured within the recess of
an interior lip 60 of the can. A permanent magnet 62 is located
adjacent the top 58 to generate a magnetic field perpendicular to
the surface of the top 58. The magnetic field causes the diameter
of the top 58 to decrease thereby causing the top member 58 to
separate from the lip 60. The top member 58 adheres to the magnet
62 after removal from the can 56.
In a fitting arranged according to the present invention as shown
in FIG. 9, a bar 66 is joined with another bar 68 by means of a
fitting 70. Ends 67 and 69 of the bars 66 and 68, respectively, are
made of a magnetostrictive material, and have a diameter slightly
greater than inner diameter 72 of the fitting 70. When joining the
rods 66 and 68, a magnetic field parallel to the axis of the rods
causes the diameter of the ends 67 and 69 of the rods 66 and 68,
respectively, to decrease, as shown in FIG. 9, so that the rods fit
into the fitting 70. When the field is removed, therods are held by
the fitting 70.
Referring now to FIG. 10, a threaded stud 74 made of a
magnetostrictive material is engaged with a nut 76 to hold the
elements 78 and 80 together. The external threads of the stud 74
match the internal threads of the element 80. Similarly, as in the
nut and bolt combination shown in FIG. 3, the holding action of the
stud is enhanced by both longitudinal and transverse
magnetostriction. Also, the stud 74, nut 76 and element 80 may be
formed without threads.
FIG. 11a and FIG. 11b show the application of the principle of
magnetostriction to a chuck adapted to hold a machine tool 82,
having a working end 84 and a securing end 86, is held by a chuck,
represented generally by the reference numeral 88. In one manner of
holding the tool 82 in place in the chuck 88, the securing end 86
is placed in a receiving hole 90 in the chuck 88 formed by a series
of three arcuate adjustable chuck sections 92, 94 and 96. The inner
edges of the sections 92, 94 and 96 form the receiving hole 90 and
by conventional adjustment techniques (not shown) these sections
may releasably grip the securing end 86 of the tool 82. The present
invention may either supplement or eliminate the adjustment
techniques.
In one form of the invention the sections 92, 94 and 96 are formed
of a magnetostrictive material. Thus, when it is desired to insert
the tool 82 into the chuck 88, a magnetic field, which may be
provided by either a permanent magnet or electromagnet, is applied
to the sections 92, 94 and 96 to cause them to alter their size and
thereby increase the size of the receiving hole 90 to allow the
securing end 86 to be inserted, as shown in FIG. 11a and FIG. 11b.
The magnetic field is then removed which causes the sections to
alter their dimensions so that they securely grip the tool 82. The
sections may also be adapted to hold the tool when a magnetic field
is applied to them and release the tool when the field is removed.
In this form, it may be more suitable to have the field producing
means be an appropriate electromagnet that is permanently affixed
to the chuck. Control of the tool may then be accomplished by
controlling electrical power to the electromagnet as with a
switch.
In another form of the invention the securing end 86 of the tool 82
may be formed of a magnetostrictive material with the receiving
hole 90 being of conventional design. To insert the tool 82 into
the chuck 88 a magnetic field is applied to the securing end 86 to
alter its dimensions to cause it to fit into the chuck. When the
field is removed, the tool assumes its original shape which results
in the tool being firmly held by the chuck.
Referring now to FIG. 12 a door 100 is mounted on a wall 102 by a
pair of hinges 104. The shape of the door is not critical and may
be square as shown, rectangular, or circular as with portholes on
ships. Mounted around the perimeter of the door 100 is a strip 106
of magnetostrictive material. To close the door 100 a magnetic
field is applied to the strip 106 to cause the strip to alter its
size and thereby slightly decrease the overall perimeter of the
door 100. The door 100 may then be swung into engagement with the
wall 102. The removal of the magnetic field causes the strip 106 to
assume its original dimensions which cause the door to fit snugly
within the wall. In an alternative form of this embodiment, the
strip 106 of magnetostrictive material may be placed along the
edges of the opening in the wall 102. The tight fitting arrangement
forms an excellent barrier for preventing leakage of water or air
and thus is applicable for use in ships and space vehicles where
tight fitting passageways are of utmost importance. The magnet may
be protable or permanently mounted within either the door or
wall.
In FIG. 13 a bolt 110, having a head 112 and a shaft 114, is
adapted to be inserted into an aperture 115 in a receiving member
116. A washer 118 made of a magnetostrictive material is rigidly
mounted on the shaft 114 of the bolt 110 due to the
magnetostrictive principle. An outermost portion 120 of the
receiving part 116 is also made of a magnetostrictive material. To
insert the bolt 110 into the aperture 115 of the receiving part 116
a magnetic field is applied to the washer 118 and the outermost
part 120 which causes the magnetostrictive materials to alter their
dimensions. Removing the magnetic field causes the magnetostrictive
materials to assume their original dimensions, the result being
that the washer 118 is too large to fit through the aperture formed
by the outermost portion 120. Thus, the bolt is secured within the
receiving part and may not be removed until a magnetic field is
applied to the magnetostrictive material. In some applications it
may be desirable to have only the washer 118 or only the outermost
portion 120 made of a magnetostrictive material.
Referring now to FIG. 14, a receiving part 122 has an aperture 124
with an outwardly flaring end section 126. A cotter pin 128 has a
head 130, and a shaft 132 with section 133 of the shaft being made
of a magnetostrictive material. The shaft 132 is curved as shown in
FIG. 14 absent any magnetic field. By applying a magnetic field to
the cotter pin, the shaft 132 becomes straight (not shown) whereby
the pin may be removed from or inserted into the receiving part
122. Thus the curved shaft 132 in conjunction with the shape of the
end section 126 of the aperture 124 causes the combination of the
cotter pin 128 and receiving part 122 to be held in tight
frictional relationship.
The present invention is applicable to increasing the frictional
holding relationship between electrical connectors, such as
electrical connectors that are inserted into switchboards. For
instance, in FIG. 14 the cotter pin 128 may be an electrically
conductive connector that may be inserted into the aperture 124
which may be a receiving hole on a switchboard. Similarly, the
embodiments shown in FIG. 9 and FIG. 13 may be modified for use as
electrical connectors.
The embodiments of the present invention described previously are
intended to be merely exemplary and those skilled in the art will
be able to make numerous variations and modifications without
departing from the spirit of the present invention. All such
variations and modifications are intended to be in the scope of the
invention as defined in the appended claims.
* * * * *