Note: Descriptions are shown in the official language in which they were submitted.
CA 02475640 2004-07-21
THREADED FASTENER NUT
WITH ANTI-CROSS THREADING RADIUSED FEATURES
AND TACTILE FEEDBACK FEATURES
CROSS-REFERENCE TO OTHER APPLICATIONS
[0001] This application is related to Canadian Patent Application Serial No.
2,401,641
filed September 6, 2002.
TECHNICAL FIELD
[0002] The present invention relates generally to threaded fasteners such as
screws, bolts
and nuts and, more particularly, to anti-cross threading fasteners.
BACKGROUND OF THE INVENTION
[0003] Threaded fasteners are used in the construction or fabrication of most
articles of
manufacture such as machines, automobiles, trains, planes, engines, etc., and
such
threaded fasteners may take the form of bolts, screws, studs, rods (all of
these terms being
used interchangeably herein) or other substantially round members having
uniform, non-
uniform or tapered external helical threads that are threadedly engaged into
mating
threaded fasteners such as nuts, bolts or holes having substantially matching
internal
helical threads. To ensure proper engagement between externally and internally
threaded
fasteners, it is important that the longitudinal axes of these parts are in
substantially
collinear alignment before threaded engagement occurs in order to prevent the
occurrence
of cross threading.
[0004] Cross threading generally occurs when there is a misalignment between
the
externally threaded member, typically a screw or bolt, and the internally
threaded
member, typically a nut or other threaded hole. Specifically, ciross threading
is the result
of the threads of the two members attempting to engage each other when out of
alignment. When this occurs, the two members are not; collinear with each
other and
I
CA 02475640 2007-03-22
wedging of the threads will occur as the threaded helixes are rotated against
each other.
If the rotation continues, as is often the case, the threads on one or both
members will
become structurally damaged.
100051 While the problem of cross threading is significant under any
circumstances in
terms of engendering costly downtime and disruption in production, the problem
of cross
threading is compounded in situations where either the threaded stud or nut is
first
attached, for example by welding, to a large panel-like or other structural
member which
then facilitates threaded attachment of another part thereto. In other words,
it is typical
for weld nuts to be welded to such panels or structural members in one
production step
(e.g. during the manufacture of an automotive vehicle) to provide an
internally threaded
means for securing another member to the first mentioned member in a
subsequent
manufacturing step. In this subsequent step, the cross threading problem is
particularly
significant since it requires the first mentioned structural member to be
repaired and
recycled for the purpose of reuse at a later time.
SUMMARY OF THE INVENTION
[0006] The present invention seeks to provide an anti-cross threading nut that
prevents
cross threading engagement of a correspondingly threaded shank member with an
inlet
opening of the nut. Preferably, the nut is configured to allow its threads to
engage the
matching threads of the threaded shank member only if the shank member is
introduced
into the inlet opening of said nut at an entry angle not greater than an
acceptable
misalignment angle, e.g., 5 .
100071 It is another aspect of the present invention to provide an anti-cross
threading nut
which has not only the anti-cross threading feature but also tactile feedback
features that
induce noticeable vibrations that alert the operator that he/she is attempting
to introduce
the shank member into the nut at an off-angle, i.e., an entry angle that is
greater than an
acceptable misalignment angle, e.g., 5 . Preferably, the tactile feedback
features act to
provide vibrations without affecting the anti-cross threading feature.
2
CA 02475640 2007-03-22
[0005] The anti-cross threading feature of the present invention can be used
alone or
together with the tactile feedback feature.
100091 These and other aspects of the present invention are achieved by an
anti-cross
threading nut comprising a nut body having first and second open ends at
opposite sides
thereof and a generally cylindrical passage extending between the first and
second open
ends. A plurality of threads extend over a predetermined axial extent of the
passage to
define a threaded region. A remaining portion of the passage is unthreaded up
tb the first
end to define an unthreaded counterbore. The first end defines an inlet
opening into the
passage for receiving a correspondingly threaded shank member. The inlet
opening is
radiused or chamfered to prevent cross threading engagement of the shank
member with
the inlet opening. Advantageously, the shank member proceeds through the
unthreaded
region which forces the shank to become substantially collinearly aligned with
the
threaded region of the nut before actual threaded contact occurs. In this
manner, cross
threading is effectively minimized or eliminated.
[0010] In a preferred embodiment, the first inlet opening is radiused.
Optionally, though
preferably, a second lead-in radius is disposed at the intersection between
the threaded
region and the unthreaded counterbore. This second lead-in radius fiirther
minimizes the
possibility of cross threading by providing a smooth transition for the
threads of the
shank member to pass through the unthreaded counterbore into proper threaded
engagement with the threaded region.
[U011] The length and diameter of the unthreaded counterbore is structured to
limit
misalignment between the threaded region and the correspondingly threaded
shank
member to less than about IO , preferably less than about 7 , and more
preferably less
than about 5 . As a result of extensive testing, it has been determined that
there is a
significant reduction in cross threading at less than such angles of
nusalignment.
100121 According to one aspect of the present invention, the design of the
counterbore is
controlled by the thread pitch. In a preferred embodiment, the axial extent or
depth of the
unthreaded counterbore is equal to at least about four times the thread pitch.
This tends
to force the before mentioned stud member and threaded region of the nut into
correct
3
CA 02475640 2004-07-21
collinear alignment wherein the threads of the stud and nut members will
rotationally
engage each other to properly fasten as intended.
100131 The first lead-in radius is preferably at least about 1.5 times the
pitch of the nut
tbreads. This enables the thread surface of the stud to smoothly pass into the
entrance
opening of the unthreaded counterbore without binding or cross threading
contact
therebetween.
[0014] The diameter of the counterbore is machined to equal the nominal
diameter of the
threaded region plus about 10% of the thread pitch in order to ensure
sufficiently snug
guiding contact which will enable the aforesaid substantially collinear
alignment to occur
at the time of threaded engagement.
[00151 The above mentioned features may be used in any type of nut
applications, such
as hex nuts, hex flange nuts, or even one or both ends of a rod coupler. In
one preferred
embodiment of the present invention, however, the above menltioned anti-cross
threading
features are formed in a weld nut that includes weld protrusions on a side
thereof
including the first open end. This enables the nut to be welded to a
structural member to
facilitate subsequent threaded connection of this member to another member by
means of
a connecting threaded stud. In this type of environment in which the nut is
previously
securely welded to a larger structural member, the anti-cross threading
features of the
invention are particularly important since cross threading has more damaging
and costly
consequences.
100161 In weld nut applications, the first open end is preferably formed on an
elongated
pilot section containing the unthreaded counterbore so as to axially offset
the open end
from the weld protrusions in a direction away from the threaded region of the
nut. This
pilot section advantageously prevents weld spatter from entering the
unthreaded counter
bore and possibly contaminating the threads.
[0017] In this weld nut embodiment, the weld nut is preferably formed with a
material
that has been hardened during the nut manufacturing process such as by
application of
heat in a known manner. By hardening the nut material, the nut threads also
become
4
CA 02475640 2007-03-22
llardened to provide added strength. In accordance with another feature of the
invention,
however, the hardened weld protrusions are selectively annealed to enable the
weld
protrusions to function properly to obtain appropriate welded contact between
the nut and
a supporting structural member. It will be appreciated that the feature of
selectively
annealing the weld protrusions in an otherwise hardened nut may be used with
or without
the above mentioned anti-cross threading features.
[0018] Accordingly, in accordance with a different aspect of the invention,
there is
provided a weld nut comprising a nut body formed with at least one weld
protwion, and
wherein the nut body includes hardened material and the weld protrusion is an
annealed
portion. According to this aspect of the invention, the entire nut body,
including the weld
protrusion, is preferably formed from the same hardened material and the weld
protrusions are then selectively annealed to form the annealed portion.
[0019] A method of correcting misalignment between a stud and a nut of a
threaded
fastener assembly is also disclosed. In accordance with this aspect of the
invention, the
method comprises relatively inserting a threaded end of a stud into a radiused
or
chamfered entrance opening of a pilot member disposed forwardly adjacent the
nut. If
there is misalignment, the stud threads contacting the radius or chamfered
opening will
not cross thread therewith. The threa.ded end of the stud is then relatively
axially
advanced through the pilot member which is not correspondingly threaded in
relation to
the stud thread. This relative axial advancement occurs over a predetermined
axial
distance that forces the stud axis to enter into substantially collinear
alignment with the
thread axis of the nut before the stud thread affects threaded cofltact with
the nut thread.
Relative rotation between the nut and stud will subsequently cause proper
threaded
engagement to occur without cross threading.
[0020] The above-mentioned and other aspects of the present invention are also
achieved
by an anti-cross threading nut, comprising a nut body having first and second
open ends
at opposite sides thereof and a passage extending between the first and second
open ends,
atid a plurality of threads extending over a predetermined axial extent of the
passage to
define a threaded region, a remaining portion of the passage being unthreaded
up to the
CA 02475640 2007-03-22
first end to define an unthreaded counterbore. The first end defines an inlet
opening into
the unthreaded counterbore for receiving a correspondingly threaded shank
member. The
inlet opening includes cross threading engagement preventing means for
preventing cross
threading engagement of the shank member with the inlet opening when the shank
member is inserted in the inlet opening at an off-angle greater than an
acceptable
misalignment angle, and tactile feedback providing means fbr causing the nut
member to
vibrate when the nut member is driven onto the shank member at an off-angle.
100211 The above-mentioned and other aspects of the present invention are also
achieved
by an anti-cross threading nut, comprising a nut body having first and second
open ends
at opposite sides thereof and a passage extending between the first and second
open ends,
and a plurality of threads extending over a predetermined axial extent of the
passage to
define a threaded region, a remaining portion of the passage being unthreaded
up to the
first end to defme an unthreaded counterbore. The first end defines an inlet
opening into
the unthreaded counterbore for receiving a correspondingly threaded shank
member. The
inlet opening including alternating peaks and valleys, wherein either the
peaks or the
valleys are radiused and define a lead in radius to prevent cross threading
engagement of
the shank member with the inlet opening. The radiused peaks or valleys
function as the
anti-cross threading feature, while the others function as the tactile
feedback features.
[0022] In accordance with the present invention, the tactile feedback features
may or may
not extend into the counterbore. The tactile feedback features may be concave
(valleys) or
convex (peaks). The tactile feedback features may be rounded or square or
rectangular.
[0023] Other and further aspects, features and advantages will become apparent
from the
following description of the presently preferred embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The present invention is illustrated by way of example, and not by
limitation, in
the figures of the accompanying drawings, wherein elements having the same
reference
numeral designations represent like elements throughout, and wherein:
6
CA 02475640 2004-07-21
[0025] Fig. 1 is a schematic cross sectional elevational view of an anti-cross
threading
nut in accordance with a fnst embodiment of the present invention;
[0026] Fig. 2 is a schematic cross sectional elevational view of an anti-cross
threading
nut in accordance with a second embodiment of the present invention with an
internal
lead in radiused portion;
[0027] Fig. 3 is a schematic cross sectional elevational view showing an
acceptable level
of misalignment between the nut of the present invention and a correspondingly
threaded
shank member;
[00281 Fig. 4 is a perspective view of an anti-cross threading nut in
accordance with a
third embodiment of the present invention with concave tactile feedback
features;
[0029] Fig. 5 is a fragmental, cross sectional view taken along line V-V in
Fig. 4, Figs.
5A and 5B are views similar to Fig. 5 showing a bolt being introduced into the
nut of the
present invention at various entry angles;
[0030] Fig. 6 is a perspective view of an anti-cross threading nut in
accordance with a
fourth embodiment of the present invention with convex tactile feedback
features, Figs.
6A-6B show fragmental, cross sectional views taken along line VI-VI in Fig. 6
in
accordance with various aspects of the present invention;
[0031] Fig. 7 is a perspective view of an anti-cross threading nut in
accordance with a
fifth embodiment of the present invention with rectangular tactile feedback
features;
[0032] Fig. 8 is a top view of an anti-cross threading nut iin accordance with
a sixth
embodiment of the present invention;
[0033] Fig. 9 is a cross sectional view taken along line IX- IX in Fig. 8; and
[0034] Fig. 10 is a bottom view of the anti-cross threading nut of Fig. 8.
7
CA 02475640 2004-07-21
DETAILED DESCRIPTION OF THE INVENTION
[0035] Before the embodiments of the invention are explained in detail, it is
to be
understood that the invention is not limited in its application to the details
of construction
and the arrangements of components set forth in the following description or
illustrated in
the drawing. The invention is capable of other embodiments and of being
ptacticed or
being carried out in various ways. Also, it is understood that the phraseology
and
terminology used herein are for the purpose of description and should not be
regarded as
limiting. The use of letters to identify steps of a method or process is
simply for
identification and is not meant to indicate that the steps should be performed
in a
particular order.
Anti-Cross Threading Feature
[0036] Fig. 1 is an illustration of an anti-cross threading nut 10 having
novel and unique
anti-cross threading and self alignment features constructed in accordance
with the
principles of the present invention. In the threaded fastener environment in
which one
embodiment of the invention is intended to be used, when the opposing thread
helixes
address each other, there is a natural tendency to collinearly align their
respective mating
planes during rotation. However, if the initial misalignment lbetween the
longitudinal
axis of an external threaded fastener and the internal threads of the
corresponding nut is
significant, then this misalignment will disadvantageously cause the threads
to engage
each other in a structurally deforming manner that causes undesirable cross
threading to
occur and which prevents proper threaded engagement between the fastener
parts.
[0037] To eliminate cross threading, a nut 10 according to one aspect of the
present
invention is formed with a radiused or chamfered inlet or entrance opening 12
through
which the external thread (e.g., 314 shown in Fig. 3) of the stud or first
member (e.g., 300
shown in Fig. 3) initially enters the nut. If there is misalignment between
axis L' of the
first member 300 and nut axis L, there will be a tendency for the external
fastening
threads 314 to contact the edges defining the entrance opening 12. If these
edges are
sharp, the external threads 314 could deformably engage with the entrance
opening 12
and such engagement could cause structural damage to one or both of the
opening 12 and
8
CA 02475640 2004-07-21
the external threads. To minimize this type of cross threading, the edge
surfaces defining
the entrance opening 12 to the nut threads 14 are preferably radiused to
present a smooth
rounded surface that will be resistant to such undesirable binding or cross
threading
contact with the leading and subsequent threads of the external threaded
fastener.
Preferably, the radius is at least 1.5 times the pitch of the external or nut
thread 14. Fig. 3
shows an acceptable level of misalignment (i.e., entry angle y(Fig. 3) is less
than 100,
preferably less than 7 , and more preferably less than 5 ) between the nut of
the present
invention and a correspondingly threaded stud 300 having an axis L'.
[003$] It may be possible to form the entrance or inlet opening 12 with a
chamfered
surface (not shown in detail) instead of a radiused surface so long as the
transitional
angles between the respective surfaces defining the chamfer do not give rise
to binding
contact.
[0039) According to another aspect of the present invention, the nut 10
includes an
unthreaded counterbore 16 extending a predetermined axial distance between the
entrance end 12 of the nut and the leading axial nut thread 14a. The purpose
of the
unthreaded counterbore 16 is to gently but firmly force the threaded fastener
into
substantially collinear alignment with the nut thread axis L before threaded
engagement
actually occurs. As a result of experimentation, it has been discovered that
the axial
length (or depth) of the unthreaded counterbore 16 should preferably be at
least four (4)
times the pitch of the nut thread 14 and that the diameter of the unthreaded
counterbore
be equal to at least the nominal diameter of the nut thread plus about 10% of
the thread
pitch. In this manner, at the time of actual threaded engagement, the external
threaded
fastener is aligned with the nut thread axis L to an acceptable level (e.g. 10
, preferably
, or less) so that cross threading will not occur once threaded engagement
commences.
By making the length of the unthreaded counterbore 16 longer, in accordance
with the
principles of the present invention, it will now be appreciated that even
greater alignment
can occur between the external threaded fastener and the nut threads 14, thus
further
reducing the possibility of cross threading. Although the length and diameter
of the
counterbore 16 has been described in terms of their relationship to the thread
pitch, it is
9
CA 02475640 2004-07-21
understood that the length and diameter of the counterbore 16 can be
controlled by other
fastener characteristics.
[0040] Optionally, though preferably, the intersection between the trailing
end of the
unthreaded counterbore with the threaded region 14 of the nut 10 is preferably
formed
with a second lead in radiused portion 18 (Fig. 2) which may have the same
curvature
characteristics as the first lead in radius opening 12 to provide a continued
smooth
transition, free of sharp protruding surfaces, that will enable the leading
thread of the
external threaded fastener to enter into smooth threaded engagement with the
leading
threads 14a of the internal thread region within the nut. Due to the relative
recessed
placement of the second lead in or entrance portion 18 relative to the
entrance or inlet
opening 12, it is also possible to form the second lead ixi radius with a
different curvature.
Desirably, this different curvature is at least 0.6 times the thread pitch.
[0041] As discussed extensively above, the foregoing features force the
external threaded
fastener to align within the bore 16 prior to threaded engagement and, once in
the bore,
tend to limit the entry angle to less than about 10 , preferably less than
about 5 , where
cross threading is significantly reduced.
[0042] The foregoing anti-cross threading features may be utilized in any type
of nut
fastener as mentioned above. However, these anti-cross threading features will
find
particular preferential use in nuts 10 that are attached to large structural
components
before subsequent threaded attachment to another structural coniponent occurs,
such as in
the manufacture, for example, of automotive and other types of vehicles or
large
machinery. In this type of environment, it will be particularly appreciated
and
understood by persons skilled in the art that disadvantageous cross threading
between
mating threaded fasteners could have highly undesirable consequences. For
example,
once the nut formed with the cross threading features of the invention is
securely fastened
to one structural component during an earlier manufacturing step, any
subsequent cross
threading occurring in a later manufacturing or assembly step will necessitate
a disruption
in the production cycle and perhaps require either scrapping of the damaged
cross
threading components or costly repair in order to make reuse possible at a
subsequent
CA 02475640 2004-07-21
time. Therefore, in accordance with another aspect of this invention, the anti-
cross
threading features of the present invention find highly preferred use in weld
nuts which
are formed with weld protrusions 20 to facilitate welding of' the nut to a
structural
member (not shown but easily accomplished in a manner known to persons skilled
in this
art). In a weld nut environment, the inlet or entrance opening 12 as well as
the leading
portion of the unthreaded counterbore 16 is preferably formed in a pilot
section 22 that is
axially offset from the weld protrusions 20 in a direction facing away from
the nut
threads 14. With this feature, weld splatter that occurs during the welding
process is not
likely to enter into the unthreaded counterbore 16 where it might otherwise
disadvantageously coat the nut threads 14 and cause cross threading to occur.
The axial
length of the pilot section 22 from the surface 24 of the weld protrusion 20
preferably is
equal to or less than the thickness of the panel material to which the nut 10
is being
attached in order to prevent the pilot section from protruding f7rom the
opposite side of
the panel surface.
(0043] It is highly desirable in certain applications to form the weld nut 10
with a
hardened material in order to improve thread strength and the extent to which
torque may
be applied to provide secure fastening engagement. However, since it may be
disadvantageous to equally harden the material forming the weld protrusion 20,
another
preferred feature of this invention is the selective annealment of the weld
protrusions so
that these protrusions are not as hard as the remaining material of the nut
body including
the threads 14. While this aspect of the invention is preferably used in
combination with
the anti-cross threading features disclosed hereinabove, it is also within the
scope of this
specification to provide a weld nut formed with selectively annealed weld
protrusions
that do not necessarily include the anti-cross threading features of this
invention.
Tactile Feedback Feature
[0044] When a nut is fastened to a matching bolt, the incomplete thread(s),
i.e., typically
the first threads on the bolt or leading threads 14a of nut 10 (Fig. 1) which
go from no
thread to full diameter in 1 to 3 revolutions, act as a ramp. Also, when the
threads of the
nut and bolt do not engage immediately, the bolt, usually driven by a powered
driving
11
CA 02475640 2004-07-21
tool, turns one more revolution and tries to catch the threads of the nut
again. Both of
these mechanisms add to vibration during the installation of the fastener
including the nut
and the bolt. As a result of extensive testing, it has been detennined that at
approximately 5 (for header point bolts and standard nuts), this vibration is
at its peak.
The above-mentioned catching and re-catching of the threads at large off-
angles are not
only the source of vibration, but also of cross threading.
[0045] In anti-cross threading nut 10 of the present invention, the deep,
tightly toleranced
counterbore 16 reduces or even eliminates possibilities of cross threading. It
has been
found via extensive testing that if the bolt was driven at less than 5 off
axis, the
occurrences of cross threading were greatly reduced. In other words, the
geometry of
counterbore 16 preferably prevents the first threads of nut 10 and matching
bolt 300 from
engaging, unless bolt 300 is introduced into counterbore 16 at about or less
than 5 off
axis. Thus, when an off-angle, i.e., an entry angle (y, Fig. 3) which is
greater than an
acceptable misalignment angle (in this case, 5 ), is being attempted,
counterbore 16
prevents the threads of nut 10 and matching bolt 300 from engaging. Continued
forcing
the bolt in without changing the entry angle can result in slamming the parts
together, or
the nut slips off the bolt, depending on the amount of entry angle and end
load. Thus,
there is a need for a mechanism, or tactile feedback feature, that alerts the
operator that an
off-angle is being attempted.
[0046] Reference is now made to Fig. 4 which is a perspective view of an anti-
cross
threading nut 410 provided with tactile feedback features 401 in accordance
with a third
embodiment of the present invention. Inlet opening 412 includes radiused
regions or
"peaks" 402 that define the first lead in radius as described with respect to
the anti-cross
threading nut of Fig. 1. Inlet opening 412 further includes tactile feedback
features 401
that are concave and create "holes" or "valleys" (best seen as 403, Fig. 4)
into which the
bolt falls, thereby creating vibrations of an amplitude greater than otherwise
observed in
an anti-cross threading nut having a smooth inlet opening 12 as shown in Fig.
1. At a
large entry angle (or off-angle), which, in this case, is greater t.han 5 ,
the vibrations are
intensified and become noticeable to the operator who is utilizing a powered
driving tool
to fasten the bolt with nut 410. The induced vibrations alert the operator of
the
12
CA 02475640 2004-07-21
unacceptably large off-angle. The configuration of valleys 401, e.g., the
length of the
valleys in the circumferential direction of inlet opening 412, is structured
so that, at entry
angles less than 5 , the bolt will not or will only slightly engage the holes
or valleys, i.e.,
little vibration indicates on-axis driving.
[0047] This will be best explained with reference to Figs. 5A and 5B, which
are
fragmental, cross sectional views of nut 410 and show a bolt 300 being
introduced into nut
410 at various entry angles y defined by axis L of the nut and axis L' of the
bolt. In Fig. 5A,
when bolt 300 is introduced at an excessive entry angle (or off-angle), a
portion (generally
designated at 581) of threads 314 of bolt 300 falls into one of holes or
valleys 401. When
nut body 410 is driven by a power driving tool, the bolt 300 repeatedly
strikes walls 451
(Fig. 4) of valleys 401, causing the nut body 410 to strongly vibrate. The
operator feels the
vibrations and attempts to reduce the entry angle as shown in Fig. 5B.
Although the nut
body 410 has been described as being driven onto bolt 300, it is envisioned
that the bolt 300
can be driven into the nut body 410 in accordance with the principles of the
present
invention. In Fig. 513, a portion (generally designated at 582) of threads 314
of bolt 300
might still fall into one of holes or valleys 401. However, thread portion 582
in Fig. SB is
smaller than thread portion 581 in Fig. 5A, and therefore, vibrations induced
in the situation
of Fig. 5B is not as strong as the vibrations induced in the situation of Fig.
5A. If the
operator continues to reduce the entry angle 7, threads 314 of bolt 300 will
eventually be
allowed to engage with inner threads 14 of nut 410, completing the fastening
process
without the risk of cross threading.
[0048] For an M8 size nut, length l of each valley 401 is about 5.5 mm. Depth
d (Fig. 5)
of valley 401 is at least .25 mm. As can be seen in Fig. 5, the tactile
feedback features or
valleys 401 do not extend into counterbore 16, an imaginary cylindrical
extension 516 of
which creates with bottom 404 of tactile feedback features 401 an angle P.
However, it is
within the scope of the present invention to. provide an anti-cross threading
nut having
tactile feedback features extending into counterbore 16 which is a generally
cylindrical
bore. The tactile feedback features should not extend too deep into
counterbore 16
because, otherwise, some protection against cross threading may be lost.
13
CA 02475640 2004-07-21
[0049] In addition, Fig. 5 shows valleys 401 having a conical bottom surface
at 404.
Preferably, the entireties of all valleys 401 are machined, forged or
otherwise fonned to
reside in a single surface. Angle (3 then presents the angle of the surface,
which is preferably
from about 20 degrees to about 70 degrees. Other methods may be used to
manufacture nut
410. It is also within the scope of the present invention to provide valleys
401 with planar
(703, Fig. 7) bottom surfaces and other shaped surfaces.
[0050] Fig. 6 shows a fourth embodiment of the present invention which is a
"reverse"
version of Fig. 4. In particular, Fig. 6 is a perspective view of an anti-
cross threading nut
610 provided with tactile feedback features 601. Inlet opening 612 includes
radiused
regions or "valleys" 602 that defme the first lead in radius as described with
respect to the
anti-cross threading nut of Fig. 1. Inlet opening 612 further includes tactile
feedback
features 601 that are convex and create raised bumps or "peaks." The
embodiment
depicted in Fig. 6 functions generally in a similar manner to Fig. 4. As can
be seen in Fig.
6, bumps or peaks 601 preferably have roiinded, or otherwise curved, external
surfaces to
avoid cross threading engagement of a bolt, such as bolt 300, with inlet
opening 612 of
nut 610. Figs. 6A and 6B show possible configurations of bumps 601 which may
(Fig. 6B)
or may not (Fig. 6A) project through imaginary (e.g., cylindrical) extension
616 of
counterbore 16. However, in the embodiment shown in Fig. 6B, bumps 601 should
not
obstruct entry of a bolt into inlet opening 612 of nut 610.
[0051] Fig. 7 is a perspective view of an anti-cross threading nut 710
provided with
tactile feedback features 701 in accordance with a fifth embodiment of the
present
invention. Like Fig. 4, inlet opening 412 includes radiused regions or "peaks"
702 that
define the first lead in radius as described with respect to the anti-cross
threading nut of
Fig. 1, and further includes tactile feedback features 701 that are concave
and create
"holes" or "valleys." However, valleys 701 have square or rectangular (rather
than
rounded or curved as illustrated in Fig. 4) bottoms 703 which may be planar.
[0052] Figs. 8-10 depict an anti-cross threading nut 810 of a particularly
preferred
embodiment (sixth embodiment) of the present invention which is similar to the
third
embodiment of Fig. 4. The top view in Fig. 8 shows nut 810 having flange 820
and internal
14
CA 02475640 2004-07-21
threads 814. Threads 814 extend only for a part of the intemal passage of nut
810, leaving
the remainder of the passage unthreaded as illustrated in Fig. 9 at 816. The
intersection
between threads 814 and counterbore 816 may or may not include a second lead
in radius
818 similar to element 18 of Fig. 1. Threads 814 have an end 824 chanifered at
45 . Flange
820 has a planar top surface designated at 822. As can be seen from the bottom
view in Fig.
10, inlet opening 812 of nut 810 has radiused regions or "peaks" 802 that
define the first
lead in radius as described with respect to the anti-cross threading nut of
Fig. 1, and further
includes tactile feedback features 801 that are concaVe and create "'holes'
or "valleys" The
peaks and valleys are altematingly arranged in the circumferential direction
of inlet opening
812. Valleys 801 are spaced regularly angularly from each other, i.e., by
a=120 as shown
in Fig. 10. Each valley or tactile feedback feature 801 does not extend into
generally
cylindrical counterbore 816. Nut 810 functions in the same manner as nut 410,
i.e., valleys
801 and peaks 802 create noticeable vibration at large off-angles, and much
less vibration at
entry angles of about or less than a predetermined acceptable inisalignment
angle. The
larger the off-angle, the larger the vibrations induced by the tactile
feedback features of the
present invention.
[00531 This is another important aspect of the present invention. When the nut
is
introduced over the bolt at a greater than acceptable entry angle, vibrations
are induced in
the system and provide tactile feedback to the operator that he/she is
attempting to fasten the
nut to the bolt at an off-angle, and that the operator needs to correct the
entry angle. If the
operator corrects the entry angle in the wrong direction, i.e., he/she makes
the entry angle
larger, vibrations will become stronger. When the operator feels the stronger
vibrations
he/she will know the entry angle should be corrected in the opposite direction
in order to
fasten the parts.
100541 The anti-cross threading feature of Fig. 1 can be used with or without
the tactile
feedback features of Figs. 4-10. The nut can be a weld nut (Fig. 1). The anti-
cross
threading feature functions when either of the nut or the bolt rotates.
However, the tactile
feedback feature functions best when the nut is driven by a powered driving
tool to rotate.
The operator may not feel tactile feedback if he or she uses a traditional nut-
runner.
CA 02475640 2004-07-21
100551 Variations and modifications of the foregoing are within the scope of
the present
invention. It is understood that the invention disclosed and defmed herein
extends to all
altemative combinations of two or more of the individual features mentioned or
evident
from the text and/or drawing. All of these different combinations constitute
various
altemative aspects of the present mvention. The embodiments described herein
explain
the best modes known for practicing the invention and will enable others
skilled in the art
to utilize the invention. The claims are to be construed to include
alternative
embodiments to the extent permitted by the prior art.
[0056] Various features of the invention are set forth in the following
claims.
16
