Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to an improvement of
a fastening device having toothed engaging surfaces and more
particularly to an improvement of a fastening device including
bolts, nuts, and the like having lower engaging surface pro-
jections with teeth constructed to afford material resistance
to loosening of the fastening device after being brought into
pressure engagement with an adjacent surface of a work piece
by the tightening of the fastening device.
An object of the present invention is to provide
an improved fastening device such as nut or bolt head having
a toothed engaging surface to effect the requirement of re-
lease torque value to loosen the fastening device which ex-
tremely exceeds the application torque required for tightening
it.
Another object of the present invention is to pro-
vide an improved engaging surface of a threaded fastening
device having ratchet-like projections in the form of double-
edged sword, whereby when the fastening device is turned in a
loosening direction an adjacent work piece surface is cut by the
projections and engaged with the latter without abrasion or
injury of the points of the projections, thereby obtaining
; locking action of the fastening device.
It is another object of the present invention to
provide an integrally formed threaded fastening device having
engaging surface provided with a number of ratchet-like pro-
jections to cause, on an adjacent work piece, two group of
engaging sections divided inward and outward so as to provide
a good locking action when the fastening device is rotated
in a loosening direction.
Still another object of the present invention is to
provide an unique construction of the toothed engaging surface
of a fastening device providing higher release torque to
application torque ratio characteristics than generally known
lock nut or bolt having engaging projections.
In one aspect of the present invention there is
provided a fastening device comprising: a body having an en-
gaging surface and threads concentric with the axis thereof,
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a plurality of ratchet-like projections formed on the engaging
surface in the form of a sawtooth in cross section; each
of said projections having a first side edge and a second side
edge with leading point which forms high end of the projections;
said points being lain on an lma~lnat~ve circle line on the
engaging surface and being faced to the opposite direction in
relation to the direction of tightening of the fastening device; ~-
each of said first side edge extending in a direction outward
from the circle line; each of said second edge extending in a
direction inward from the circle line; said circle line being
positioned near an inner edge of the engaging surface, whereby
length or cutting area of the first edges is larger than that of
the second edges at approximately a four or five to one ratio.
The other objects and advantages of the present in- -
vention will become apparent from the following detailed des-
cription illustrating the invention by way of example with
reference to the accompanying drawings, wherein:
Figure 1 is a side view showing the adaption of an
embodiment of this invention to a flanged nut;
Figure 2 is an end view of the flanged nut illustrated
in Figure l;
Figure 3 is a fragmentary enlarged end view of the
flanged nut:
Figure 4 is a fragmentary sectional view taken along
the line 4-4 in Figure 3;
Figure 5 is a fragmentary sectional view taken along
the line 5-5 in Figure 3;
Figure 6 is a sectional view of a somewhat modified
other embodiment which shows the relative position occupied by
the projections and the work piece when the nut is rotated in
loosening direction; and
Figures 7, 8 and 9 are respectively side view of other
embodiments of the present invention wherein Figure 7 is adapted
for a standard nut, Figure 8 being adapted for bolt having a
flanged head and Figure 9 being adapted for a standard bolt
having a head.
Referring to the drawing more in detail wherein I
have employed like characteristics to denote similar parts in
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the various figures it will be seen that one embodiment of the
present invention contemplates a threaded flange nut designated
by the numeral 10~
The nut 10 is provided with a body 11 having an
annular flange 12 formed at lower portion of the body, a threaded
bore 13 extending through the axis of the body and an engaging
end surface 14 having a number of ratchet-like projections 15.
Each of said projections has a first side edge 17
and a second side edge 18 defined by a leading point 19 which
is formed at high end of the projection. Each of said points
is lain on a circle line 16 and being faced to the direction
of tightening of the nut 10.
Said first side edges 17 extend in a direction outward
from the circle line 16 and the second surface or edge 18 being
extended in a direction inward from the circle line. The circle
line 16 is positioned near the inner edge 20 of the engaging
surface so that length of the first edges 17 are larger than
that of the second side edges 18, several times as large, pre-
ferably in a five to one ratio.
An angle X formed by the first and second edges 17,
18 is 65 to 90, preferably 72 to form sharp points, and pre-
ferably slowly inclined surfaces 22 and suddenly inclined sur-
faces 23 of the ratchet-like projection are intersected in sub-
stantially right angular relationship as shown in Figure 5.
In operation, it will be understood that the arcuate
angle points 19 of the projection on the engaging surface 14
serve as spearheads when the nut is turned in a clockwise
direction, that is, loosening direction as shown at numeral 21
in Figure 2, thereby cutting into the surface on an adjacent
work piece 24. In this case, the points easily bite into the
adjacent work piece by effect of double-edged sword of the
projections formed of the leading points 19 with the first and
the second edges 17, 18, thereby preventing abrasion of injury
of the pointed projections.
Furthermore, the cut material cut by the projections
is divided into two directions along the first and the second
side edges 17, 18 at shown arrows 25 and 26 in Figure 3. As
the cutting area of the first side edges are quintuple as large
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as that of the second side edges, a large quantity of cut material
is generated in the first side edges 17, and it serves as
material resistance. In general, the co-efficient of friction
of outer portion on the engaging surface 14 is larger than that
of inner portion on the engaging surface, so that the afore-
mentioned large material resistance generated by the first edges
17 serves as a large amount of locking resistance and is
effectively acted to prevent loosening of the nut.
In addition, each of said projections is compressed
between the both sides 17, 18 by said outer cut material and
inner cut material so as to cause a wedge effect of the pro-
jections, thereby increasing locking action of the nut. If,
as shown in Figure 6, the inner edge 20 of the engaging surface
14 is arranged near the threaded bore 13A, said inner cut mat-
erial 27 generated by the second edge 18 is compressed between
the projections and threads 28 of a bolt 29 and provides large
resistance to rotate loosening direction, thereby obtaining
high locking action of the fastening device.
Referring to the Figure 7, the present invention is
applied to a standard nut lOA in which projections 14A having
same construction of the projections 14 in the first embodiment
is provided to give the same locking action as in the case of
the first embodiment.
Figures 8 and 9 also illustrate other embodiments of
the present invention in which projections 14B similar to the
aforementioned projections in the first embodiment are formed
on the lower surface of a flange head 30 of a bolt 31 in Figure
8, and projections 14C similar to the projections 14 being
adapted to a standard headed bolt 32 in Figure 9. It will be
understood that the bolts illustrated in Figures 8 and 9 also
may be applied the same locking action as in the case of the
aforementioned first embodiment.
Changes and modifications will occur to those skilled
in the art, and the foregoing is not intended to limit the scope
of the present invention, which is defined by the following
claims.
