Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 022~4634 1998-11-27
TITLE OF THE INVENTION
Metallic Fastening Member and Fablication Method Thereof
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a metallic fastening member such as
a tee nut or a 1ivet having a flange portion extruding outwards from one
end of a hollow shaft portion, and a fablication method of such a metallic
fastening member. More particularly, the present invention relates to a
metallic fastening member including a relatively thin-walled portion to be
caulked at an end of a shaft portion opposite to the end of a flange portion,
and a fablication method of such a metallic fastening member.
Descliption of the Background Art
A conventional tee nut having a thin-walled portion to be caulked at
its shaft portion is disclosed in, for example, U.S. Patent No. 5,238,344 or
U.S. Patent No. 5,348,432.
A tee nu~t 11 defined in U.S. Patent No. 5,238,344 has a configuration
as shown in Figs. 40A and 40B. The tee nut is formed integrally by sheet
metal processing an iron metal plate, and includes a shaft portion 12 and a
flange portion 13 extruding outwards from a first end of shaft portion 12.
Shaft portion 12 has a hollow cylindrical shape of a uniform outer
diameter. At a second end of shaft portion 12 opposite to the first end, a
portion to be cauLked 14 is provided. In shaft portion 12 excluding portion
14 to be caulked, a female thread 15a is formed at the inner circumference
of a female thread formation portion 15. Portion 14 is made thinner than
the portion where female thread formation portion 15 is formed. This
provides the advantage that, in the formation of female thread 15a, the
threading work can be effected from either side of the first end or the
second end of shaft portion 12.
Flange portion 13 includes two pawls 16 formed by extruding
inwards a portion of the outer rim of flange portion 13 so as to protrude
towards the second end of shaft portion 12. The two pawls 13 are arranged
opposite to each other by 180 degrees. At the lim of flange portion 13, a
notch 17 having a cross section of substantially a semicircle is left as a
CA 022~4634 1998-11-27
result of formation of pawl 16.
Fig. 42A shows tee nut 11 in its usage state. Referring to Fig. 42A,
shaft portion lZ is inserted into a through hole 18 that is provided in
advance in a workpiece object of fixation 19 formed of resin or wood.
Portion 14 is subjected to a cauL~ing process by a caulking device, whereby
a caulked portion 14a is formed at one surface side of object 19 of fixation.
At the same time, pawl 16 digs into the other surface side of object 19.
Thus, fixation of tee nut 11 to object 19 is completed.
A tee nut 31 disclosed in U.S. Patent No. 5,348,432 has a
configuration as shown in Figs. 41A and 41B. Similar to the above-
described tee nut 11, tee nut 31 is integrally formed by applying a sheet
metal process on an iron type metal plate. Tee nut 31 includes a shaft
portion 32 and a flange portion 33 extruding outwards from one end of shaft
portion 32. Shaft portion 32 includes a female thread formation portion 35
having a female thread 36 formed at the inner circumference of shaft
portion 32. Shaft portion 32 includes a portion 34 to be caulked The
structure of tee nut 31 differs from tee nut 11 in that two pairs of pawls 37
and 38, and 39 and 40 extending from one end towards the second end are
arranged opposite in the radial direction of flange portion 33 at the outer
perimeter of flange portion 33. Flange portion 33 substantially has an
octagonal shape as a whole.
Such a tee nut 31 is generally referred to as a "hopper feed tee nut".
This is because tee nut 31 can be advanced smoothly along the supply track
in a nut fixation device to be fastened to an object of fixation. In other
words, the tee nut can be supplied automatically. Details of a form of a
hopper feed tee nut is disclosed in, for example, G. B. Patent No. 1,157,734.
In Fig. 41B, the aforementioned supply track 43 is depicted in fathom
lines. Supply track 43 includes a pair of guide rails 44 and 45 having a C-
shape cross section, arranged symmetrically facing each other. Tee nut 31
is moved taking a predetermined posture along supply track 43 while flange
portion 33 is received in each of guide rails 44 and 45 with pawls 37-40
therebetween. Although not depicted, supply track 43 is often bent to set
tee nut 1 at a desired posture, and has shaft portion 32 aligned in a hole
CA 022~4634 1998-11-27
formed in the workpiece object to be fastened (not shown).
As shown in Fig. 42B, for example, tee nut 31 is used in a manner
.similar to that of tee nut 11. More specifically, shaft portion 32 of tee nut
31 is inserted into a through hole 18 in an object of fixation 19. A caulking
process is applied on portion 34 to be caulked of tee nut 31 by a cauL~ing
device, whereby a caulked portion 34a is formed at one side surface of object
19. At the same time, pawls 37-40 dig into the other side surface of object
19.
Tee nut 31 is prevented from being detached from through hole 18 by
means of pawls 37-40 that prevent rotation of tee nut 31 with respect to
object 19 and by means of flange portion 33 and caulked portion 34a that
sandwich object 19. Tee nut 31 is firmly secured to object 19. The fixed
state is maintained substantially permanently.
Once either of the conventional tee nuts 11 and 31 is secured to
object 19 by means of cauL~ing, it is di~icult to detach the tee nut from
object 19 since~the fixation strength is extremely great. This is preferable
from the standpoint of holding the product to which tee nut 11 or 31 is
applied in a secure state.
However, when the product is no longer used and is to be dismantled
to recover the material forming object 19 for recycle pulposes, tee nut 11 or
31 must be unfastened from object 19. The application for recycle is
particularly required in the event that the material forming object 19 is a
resin. There is a demand for a tee nut that does not bar the separation
and recovery work of an object 19 for recycle usage in a product that was
fastened by caulking and is now to be dismantled.
Such a demand for facilitating the separation work for recycle usage
is not limited to a tee nut. There is a .~imil~l demand for any metal made
fastening member that is fixed by caulking to an object of fixation such as a
livet which is a member that does not have a female thread formed at the
inner peripheral surface of the shaft portion.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a metallic fastening
member such as a tee nut or a rivet including a portion to be caulked that is
CA 022~4634 1998-11-27
easily detachable from an object of fixation in an already-used product
without degrading the fixation strength to the object of fixation when in a
secured state by caulking.
The metallic fastening member of the present invention for att~ining
the above object is integrally formed of a metal material, including a
cylindlical shaft portion and a flange portion extruding outwards from a
first end of the shaft portion. The shaft portion includes a portion to be
caulked at a second end opposite to the first end, and a shaft main portion
continuous to the portion to be caulked and extending towards the second
end. The metallic fastening member is charactelized in that a thin-walled
portion were the wall of the shaft portion is partially reduced is provided
within the substantially annular region that forms the circumference of the
shaft portion at the flange portion side than the region bent corresponding
to the portion to be caulked. The thin-walled portion maintains strength
so that fracture will not occur with respect to the force in the direction of
the axis that is~exerted when in the state of usage corresponding to a fixed
state by caulking with respect to an object of fixation, and that will fracture
by effecting tensile force greater than a predetermined level in the direction
of the shaft to allow separation of the shaft portion into two parts.
According to the metallic fastening member of the present invention
having the above-described structure, a jig is used that causes tensile stress
in the direction of the center axis of the shaft portion at the groove portion
in the shaft portion with the object of fixation fastened by caulking. The
metallic fastening member can easily be separated into two parts by
fracture at the portion where the jig is used. As a result, the metallic
fastening member that was secured by sandwiching the object of fixation
from both the top and bottom faces with the flange portion and the caulk
portion can easily be detached from the object of fixation.
Since the metallic fastening member can easily be disengaged from
the object of fixation, the separation and recovery of the object of fixation
constituting the product having the metallic fastening member of the
present invention caulked can be facilitated, subsequent to the peliod of
usage of the product to promote recycling.
CA 022~4634 1998-11-27
When the metallic fastening member of the present invention is
secured to be object of fixation in a caulked manner, the pawl at the flange
portion digs into the object of fixation for a more secure fixation. Also, the
tightening force of a male screw, when in a screwed and tightened state
during usage of the product in which the object of f~xation is a constituent
element, mainly acts as compressive stress to the shaft main portion.
Therefore, generally no great tensile stress will be generated at the shaft
portion of the tee nut. There is substantially no degradation in the
fixation strength caused by a lower strength due to provision of an annular
groove in the shaft portion.
As means for providing a thin-walled portion, at least one of the
outer peripheral surface and the inner peripheral surface of the
substantially annular region of the shaft portion has a groove formed
extending in the direction of the circumference so that the wall of the shaft
portion is partially reduced. Such a groove can be provided continuous
over the entirelcircumference, or having at least one discontinuous area.
As another means for providing a thin-walled portion, a dent that is
intermittently present in the direction of the circumference can be provided
in at least one of the outer peripheral surface and the inner pelipheral
surface of the substantially annular region of the shaft portion.
The groove is preferably provided in at least the inner perimeter or
the outer pelimeter of the shaft portion in proximity to the interface
between the portion to be caulked and the shaft main portion. Also, the
groove can be provided at both the inner perimeter and the outer perimeter
of the shaft portion in proximity to the interface between the portion to be
caulked and the shaft main portion, substantially opposite to each other.
Thus, the thin-walled portion is provided at the outer circumference
of the shaft portion in the neighborhood of the interface between the portion
to be caulked and the female thread formation portion. By such a
structure, the entire length of the portion to be caulked can be subject to
bending for caulking. Since the thinnest wall portion is formed at the
stepped portion of the interface between the portion to be caulked and the
female thread formation portion, fracture can occur relatively easier in the
CA 022~4634 1998-11-27
stage of detachment from the object of fixation. This is convenient for
facilitating the separation work of recovery for recycle purposes.
The provision of the thin-walled portion at such a position allows the
metallic fastening member to be detached from the object of fixation by the
method set forth in the following in the state fixed by cauL~ing with respect
to the object of fixation. A columnar jig is driven from the second end side
that is caulked. The upper end of the jig is hit by a hammer or the like,
whereby the lower end of the jig is urged against the upper edge of the
female thread formation portion. In response to the tensile acting on the
shaft portion caused by the urge, great tensile stress is exerted on the
thinnest wall portion where the thin-walled portion is formed. Fracture
occurs at this area to divide the metallic fastening member into two parts.
As a result, the separated first end half portion, i.e., the portion including
the female thread formation portion and the flange portion, is pushed
downwards by the lower end of the jig to be detached from the object of
fixation. Then, the jig is pulled up outwards, whereby the second end half
portion that is in a close fit state with respect to the jig is detached from the
object of fixation together with the jig.
The thin-walled portion of the metallic fastening member of the
present invention can be provided at one or both of the outer circumference
and the inner circumference of the portion to be cauLked at a position closer
to the female thread formation portion side than the portion where bending
deformation occurs in a cauLked state. By providing a thin-walled portion
at such a position, the metallic fastening member can be detached from the
object of fixation using a columnar jig in a manner simil~r to that of the
above-desclibed structure.
Furthermore, the thin-walled portion of the metallic fastening
member of the present invention can be provided at the outer circumference
of the shaft portion in the female thread formation portion. In this case, a
wedge-like jig is inserted into the abutment between the caulk portion or
the flange portion and the face of the object of fixation in the state secured
to the object of fixation by caulking. Tensile stress is exerted on the shaft
portion to cause fracture at the concave portion. The metallic fastening
CA 022~4634 1998-11-27
member is separated into two pieces, and can be detached from the object of
fixation.
In this case, a structure can be provided wherein a relatively thin-
walled region recessed with a predetermined width in the extending
direction of the shaft portion and where a female thread is not provided is
formed in a region at the inner peripheral face of the female thread
formation portion. A thin-walled portion can be formed at the outer
pelipheral surface of this relatively thin-walled region. In this case, the
thin-walled portion has the minimum thickness made small enough even if
it is relatively shallow and thin. Therefore, the object of facilitating
removal of the metallic fastening member for recovery directed to recycling
purposes can be accomplished.
As an alternative to the above-described thin-walled portion, a
structure can be provided that includes an annular thin-walled portion over
the entire perimeter at the interface between the portion to be caulked and
the female thr~ad formation portion. This annular thin-walled portion is
formed by being drawn in the radial direction of the shaft portion by
shaping the portion to be caulked so that the inner and outer diameter
thereof is reduced or increased relative to the female thread formation
portion. By inserting a wedge-like jig into the abutment between the
portion to be caulked or the flange portion and the face of the object of
fixation while the object of fixation is secured in a caulk manner, tensile
stress is exerted on the shaft portion to cause fracture at the annular thin-
walled portion. As a result, the metallic fastening member can be easily
separated into two pieces to be removed from the object of fixation.
In a preferable embodiment of the metallic fastening member of the
present invention, the groove has a substantially planer bottom of a
predetermined width. By such a substantially flat bottom of a
predetermined width of the groove, valiation in the width of the bottom of
the groove caused by any slight variation in the process operation in press
shaping is so small so that there is hardly no variation in the depth. As a
result, the thinnest wall of the shaft portion of desired level can be obtained
stably. In the state where the portion to be caulked is caulked, the end of
CA 022~4634 1998-11-27
the portion bent by caulking at the flange side can easily be set to overlap
the position of the bottom of the annular groove. There is also the
advantage that the detachment in the separation work in recovery can be
carried out relatively easily since the position of the end of the portion bent
by cauL~ing at the flange side is ovellapped with the position of the bottom
of the groove.
The present invention is suitably applied to the so-called tee nut
where a female thread is formed in at least a part of the region of the inner
circumference of the shaft main portion. In the case of such a tee nut, a
structure can be provided having a relatively thin-walled region recessed
over a predetermined width in the direction where the shaft portion extends
at an area of the inner circumference of the shaft main portion, and in
which a female thread is not formed. The groove can be provided at the
outer circumference or the inner circumference of the shaft portion at that
relatively thin-walled region.
As still ~nother means for forming a thin-walled portion at the shaft
portion, a thin-walled portion provided extending in the circumference
direction at the interface between the portion to be caulked and the shaft
main portion can be provided. The thin-walled portion is formed by being
extended in the radial direction of the shaft portion by shaping the portion
to be caulked so that the inner and outer diameter is reduced or increased
at least partially relative to the shaft main portion.
The fabrication method of a metallic fastening member of the present
invention of a one piece construction formed of a metal material, and
including a cylindrical shaft portion and a flange portion extruding
outwards from the first end of the shaft portion, said shaft portion including
a portion to be cauLked at the second end opposite to said first end, and a
shaft main portion continuous to the portion to be caulked and extending
towards the second end, includes the following steps.
First, the center area of the portion of a metal sheet that will become
the flange portion is expanded towards one main surface of the metal plate
to form an expansion portion that becomes the shaft portion. A through
hole is formed at the leading end face of the expansion portion. The wall
- 8 -
CA 022~4634 1998-11-27
thickness of the leading end portion corresponding to the portion in the
expansion portion where the portion to be caulked is to be formed is made
thinner than the wall of the base portion corresponding to the region where
the shaft main portion is to be formed. Also, the inner diameter of the
leading end portion is made smaller than the inner diameter of the base
portion (termed "step (A)" hereinafter). Then, at least either the leading
end portion or the base portion is deformed in the radial direction so that
the outer diameter of the leading end portion and the outer diameter of the
base portion come closer while maintaining the wall thickness of the base
portion (termed "step (B)" hereinafter).
In a preferable embodiment of the present invention, step (B) is
carried out so that a groove extending in the direction of the circumference
is formed in at least the inner circumference of the substantially annular
region in the proximity of the interface between the leading end portion and
the base portion. In another preferable embodiment of the present
invention, step (B) is carlied out so that a groove extending in the
circumference direction is formed at both the inner circumference and the
outer circumference of the substantially annular region in the proximity of
the interface between the leading end portion and the base portion.
Step (A) preferably includes the step of reducing the outer diameter
and the inner diameter of the leading end while restricting deformation of
the base portion. Step (B) preferably includes the step of reducing the
outer diameter and the inner diameter of the base portion while restlicting
deformation of the leading end portion. Further preferably included is the
step of exerting urging force in the direction of the center axis of the shaft
portion with respect to the leading end portion after the step of (B).
According to the method of fabricating a metallic fastening member
of the present invention with the above-desclibed steps, a metallic fastening
member with a thin-walled portion directed to facilitate detachment for
recycle purposes can be fabricated efficiently without increasing the
fabrication cost and without degrading the mass production.
The foregoing and other objects, features, aspects and advantages of
the present invention will become more apparent from the following
CA 022~4634 1998-11-27
detailed description of the present invention when taken in conjunction
with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figs. lA and lB are a central vertical cross sectional view and a
perspective view, respectively, of a tee nut 51 according to a first
embodiment of the present invention.
Figs. 2A and 2B are a central vertical cross sectional view and a
perspective view, respectively, of a tee nut 61 according to a second
embodiment of the present inventian.
Figs. 3A, 3B and 3C are enlarged cross sectional views of the
neighborhood of groove 20 (50) in respective embodiments of the present
invention, showing a round U-shape, a V-shape and a squared U-shape
cross section, respectively, of the grooves.
Figs. 4A and 4B are sectional views of tee nut 51 of the first
embodiment and tee nut 61 of the second embodiment, respectively, in the
state where th,e tee nut is fitted in a through hole 18 in an object 19 of
fixation in a cauL~ed state.
Figs. 5A and 5B are sectional views of tee nut 51 of the first
embodiment fastened to an object 19 of fixation in a caulked manner,
wherein the former shows the state of a jig 70 driven in from the side of a
caulked portion 14 and the latter shows the state of tee nut 51 divided into
upper and lower pieces by the fracture at a groove 20 caused by urging force
F of jig 70, according to a method of removing tee nut from object 19 of
fixation.
Fig. 6A is a partial sectional view of a tee nut according to a third
embodiment of the present invention showing the manner of formation of
groove 20 (50), and Figs. 6B and 6C show two modifications of the tee nut of
the third embodiment.
Fig. 7A is a partial sectional view of a tee nut according to a fourth
embodiment of the present invention showing the manner of formation of
groove 20 (50), and Fig. 7B is a sectional view of a modification of the tee
nut of the fourth embodiment.
Fig. 8A is a partial sectional view showing the manner of formation
- 10 -
CA 022~4634 1998-11-27
of an annular thin-walled portion 70 of a tee nut according to a fifth
embodiment of the present invention, and Fig. 8B is an enlarged sectional
view of the neighborhood of annular thin-walled portion 70 in the tee nut of
Fig. 8A.
Fig. 9A is a central sectional view of a tee nut 81 according to a sixth
embodiment of the present invention, and Fig. 9B is a central sectional view
of a tee nut 91 which is a modification of the sixth embodiment.
Fig. lOA is a central sectional view of a tee nut 101 according to a
seventh embodiment of the present invention, and Fig. lOB is a central
sectional view of a livet 111 having a structure simil~r to that of tee nut
101 except for the absence of a female thread at the inner peIipheral face of
the shaft main portion.
Fig. 11 is a sectional view showing the sequential forward press work
sequentially applied to a metal plate 201 for the formation of tee nut 101 of
Fig. 10A or rivet 111 of Fig. 10B.
Fig. 12 i~s an enlarged sectional view showing the details of the
process applied at working stations [a]-[c] out of the working states of Fig.
11.
Fig. 13 is an enlarged sectional view showing the details of the
process applied at working stations [d]-[g] out of the working states of Fig.
11.
Figs. 14A, 14B and 14C are enlarged sectional views of the member
to be processed at working stations [d], [f~ and [g], respectively, of Fig. 13 in
the proximity of the portion to be caulked.
Fig. 15A is a central sectional view of a tee nut 121 according to a
modification of the seventh embodiment of the present invention, and Fig.
15B is a central sectional view of a rivet 131 having a structure .~imil~r to
that of tee nut 121 except for the absence of a female thread at the inner
peripheral face of the shaft main portion.
Fig. 16 shows in detail the process carried out at working stations
[d]-[g] of the process of Fig. 11 for the formation of a tee nut 121 or rivet 131
of the seventh embodiment of Figs. 15A and 15B, and is an enlarged
sectional view corresponding to Fig. 13.
- 11 -
CA 022~4634 1998-11-27
Figs. 17A, 17B and 17C are enlarged sectional views of the member
to be processed at working stations [d], [fl and [g], respectively, of Fig. 16 in
the proximity of the portion to be caulked.
Fig. 18A is a central sectional view of a tee nut 141 which is another
modification of the seventh embodiment of the present invention, and Fig.
18B is a central sectional view of a livet 151 having a structure .~imil~r to
that of tee nut 141 except for the absence of a female thread at the inner
peripheral face of the shaft main portion.
Fig. l9A is a central sectional view of a tee nut 161 which is a further
modification of the seventh embodiment of the present invention, and Fig.
l9B is a central sectional view of a livet 171 having a structure simil~r to
that of tee nut lG 1 except for the absence of a female thread at the inner
peripheral face of the shaft main portion.
Fig.20A is a central vertical sectional view of a tee nut 181 according
to an eighth embodiment of the present invention, and Fig. 20B is a central
vertical sectio~al view of a tee nut 191 which is a modification of the eighth
embodiment of the present invention.
Fig. 21A is a perspective view of tee nut 181 (or 191) of the eighth
embodiment of the present invention shown in Fig.20A, and Fig.21B is a
perspective view of a tee nut 201 which is another modification of the
eighth embodiment of the present invention.
Fig. 22A is a central vertical sectional view of a tee nut 211 according
to a ninth embodiment of the present invention, and Fig. 22B is a central
vertical sectional view of a tee nut 211 which is a modification of the ninth
embodiment of the present invention.
Fig. 23A is a partial sectional view showing an enlargement of the
structure having a partial irregular portion at the female thread formation
portion of a tee nut, and Fig. 23B is a sectional view taken along line X-X of
Fig. 23A.
Figs. 24A and 24B are central vertical sectional views of a tee nut
231 and a livet 241, respectively, according to an eleventh embodiment of
the present invention.
Figs. 25A and 25B are a front sectional view and a partial vertical
- 12 -
CA 022~4634 1998-11-27
back view, respectively, of a tee nut 251 according to a twelfth embodiment
of the present invention.
Fig. 26Ais a sectional view taken along line X-X of Fig. 25A, and Fig.
26Bis a perspective view, respectively, of tee nut 251 of the twelfth
embodiment of the present invention.
Fig. 27Ais a front sectional view and Fig. 27Bis a partial sectional
back view, respectively, of a rivet 261 which is a modification of the twelfth
embodiment of the present invention.
Fig. 28Ais a front sectional view and Fig. 28Bis a partial sectional
back view, respectively, of a tee nut 271 which is another modification of
the twelfth embodiment of the present invention.
Fig. 29Ais a front sectional view and Fig. 29Bis a partial sectional
back view, respectively, of a livet 281 which is a further modification of the
twelfth embodiment of the present invention.
Fig. 30Ais a front sectional view and Fig. 30Bis a partial sectional
back view, respectively, of a livet291 which is still another modification of
the twelfth embodiment of the present invention.
Fig. 31is a perspective view of livet 291 shown in Figs. 30A and 30B.
Fig. 32Ais a front sectional view and Fig. 32Bis a partial vertical
back view, respectively, of a rivet 301 which is yet a further modification of
the twelfth embodiment of the present invention.
Fig. 33Ais a central vertical partial sectional view and Fig. 33Bis a
perspective view, respectively, of a tee nut 311 according to a thirteenth
embodiment of the present invention.
Fig. 34Ais a central vertical sectional view of a tee nut 321 according
to a fourteenth embodiment of the present invention, and Fig. 34Bis a
central vertical sectional view of a tee nut 331 which is a modification of the
fourteenth embodiment of the present invention.
Fig. 35Ais a central vertical sectional view of a livet 341 according to
the fourteenth embodiment of the present invention, and Fig. 35Bis a
central vertical sectional view of a rivet 351 which is a modification of the
fourteenth embodiment of the present invention.
Fig. 36is an enlarged sectional view of the state in which a working
CA 022~4634 1998-11-27
station [h] is provided adjacent working station [g] in the case of forming
the tee or the rivet according to the fourteenth embodiment shown in Figs.
34A, 34B or Figs. 35A and 35B.
Fig. 37 is a partial enlarged sectional view showing the neighborhood
of a leading end portion corresponding to the portion to be caulked 34 in
working station [h] shown in Fig. 36.
Fig. 38A is a central vertical sectional view of a livet 361 according to
the fourteenth embodiment of the present invention, and Fig. 38B is a
central vertical sectional view of a livet 371 which is a modification of the
fourteenth embodiment of the present invention.
Figs. 39A and 39B are central vertical sectional views of rivets 381
and 391, respectively, which are other embodiments of the fourteenth
embodiment of the present invention.
Fig. 40A is a central vertical sectional view of a conventional tee nut
11 having a round flange and a shaft portion with a thin wall at the portion
to be caulked, ~isclosed in U.S. Patent No. 5,238,344, and Fig. 40B is a
perspective view of tee nut 11 of Fig. 40A.
Fig. 41A is a perspective view of a conventional tee nut 31 having an
octagonal flange and a shaft portion with a thin wall at the portion to be
caulked, disclosed in U.S. Patent No. 5,348,432, and Fig. 41B is a central
vertical cross section view of tee nut 31 of Fig. 41A.
Fig. 42A is a sectional view of conventional tee nut 11 of Figs. 40A
and 40B inserted and fastened to object 19 of fixation in a caulked state,
and Fig. 42B is a sectional view of conventional tee nut 31 of Figs. 41A and
41B inserted and fastened to object 19 of fixation in a caulked stated.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiments of the present invention will be desclibed hereinafter
with reference to the drawings.
[First Embodiment]
A tee nut 51 according to a first embodiment of the present invention
is shown in Figs. lA and lB. The configuration of shaft portion 12 and
flange portion 13 is basically similar to that of the conventional tee nut 11
described in U.S. Patent No. 5,238,344 with reference to Figs. 7A and 7B.
- 14-
CA 022~4634 1998-11-27
Therefore, common elements have the same reference characters allotted,and detailed description thereof will not be repeated.
Tee nut 51 of the first embodiment differs from the conventional tee
nut 11 in that an annular groove 20 is provided at the outside pelimeter of
shaft portion 12 at the interface between portion 14 to be cauL~ed and
female thread formation portion 15. Groove 20 has a cross section such as
a round U shape, a V shape, or a squared U shape as shown in Figs. 3A, 3B
and 3C, respectively. The cross sectional shape of groove 20 is selected
appropriately according to the material of the tee nut, the working property
thereof, or mechanical property such as the tensile strength.
Tee nut 51 of the above structure is used as will be described with
reference to Fig. 4A. Shaft portion 12 of tee nut 51 is inserted into a
through hole 18 formed in an object of fixation 19 such as of resin or wood.
In this state, portion 14 is subjected to a cauLking process by a caulking
device, whereby a caulked portion 14a is formed at one side surface of object
19. At the same time, pawl 16 digs into the other side surface of object 19,
so that tee nut 51 is fixed securely to object 19.
In the product where object 19 of fixation becomes the constituent
element, another member is connected to object 19 by threading in a male
screw into the female thread formation portion 15 to attain a fastened state
with tee nut 51 in a caulked manner. The tightening force of the male
screw mainly acts on female thread formation portion 15 as compressive
stress when screwed into engagement with the female thread of female
thread formation portion 15. Therefore, no great tensile stress will be
generally generated at the shaft portion of the tee nut. Therefore,
degradation in the fixation strength caused by reduction in the strength
due to provision of a groove at the shaft portion will not occur.
The method of unfastening tee nut 51 from object 19 of fixation in
recovering the object of fixation forming the product having tee nut 51
caulked, subsequent to its period of usage or at the elapse of the lifetime,
for recycling purposes will be described hereinafter with reference to Figs.
5A and 5B.
As shown in Fig. 5A, the lower end side of a columnar jig 70 having a
- 15-
CA 022~4634 1998-11-27
size slightly greater than the inner diameter of portion 14 of tee nut 51
prior to caulking is press fitted from the caulked portion 14a side of tee nut
51. The upper end of jig 70 is hit with a hammer or a like in a state where
the lower end of jig 70 abuts against the stepped portion at the interface
between portion 14 and female thread formation portion 15. As a result,
force F shown in Fig. 5A is exerted. By this force F, stress concentration is
developed at the most thin-walled region at the outer pelimeter of the shaft
portion where groove 20 is formed at the interface between portion 14 and
female thread formation portion 15. The generated tensile stress of high
intensity causes fracture at annular groove 20. As a result, tee nut 51 is
separated into two parts as shown in Fig. 5B. The lower end of jig 70
pushes down the lower half part of tee nut 51 including female thread
formation portion 15 and flange portion 13, whereby the lower part is
detached from object 19 of fixation. The upper half part of tee nut 51
including cauL~ed portion 14a is removed from through hole 18 of object 19
in a state fitte~ to jig 70 as jig 70 is pulled out upwards.
According to tee nut 51 of the present embodiment, tee nut 51 can
easily be disengaged from object 19 of fixation. At the elapse of the period
of usage of the product having tee nut 51 caulked, separation and recovery
of the object of fixation forming the product can be facilitated to promote
recycling of object 19 of fixation.
Since annular groove 20 is provided at the interface between portion
14 to be caulked and female thread formation portion 15 in tee nut 51 of the
present embodiment, the above-described method of detachment using jig
70 can be employed even when substantially the entire portion 14 to be
caulked is bent. Since the most thin-walled portion is formed at thé
stepped portion at the interface between the poltion to be caulked and the
female thread formation portion, stress concentration at that area becomes
more .~ignific~nt in detaching the tee nut from the object of fixation.
Therefore, fracture is more readily generated to facilitate the separation
operation for recovery in the recycling stage. The need of recovery for
recycling purposes is greater when object 19 of fixation is formed of plastic.
[Second Embodiment]
- lG-
CA 022~4634 1998-11-27
A tee nut 61 according to a second embodiment of the present
invention is shown in Figs. 2A and 2B. The configuration of shaft portion
32 and flange portion 33 are basically .~imil~r to that of conventional tee nut
31 of Fig. lOA and lOB corresponding to U.S. Patent No. 5,348,432.
Therefore, .simil~r elements have the same reference characters allotted,
and detailed description thereof will not be repeated.
Tee nut 61 of the second embodiment differs from conventional tee
nut 31 in that an annular groove 50 is formed around the entire outer
perimeter of a shaft portion 32 at the interface between a portion 34 to be
caulked and a female thread formation portion 35. Tee nut 61 is .qimil~r in
structure to tee nut 51 of the first embodiment for the exception that a
flange portion 33 has substantially an octagonal shape, and that a first pair
of pawls 37 and 38 and a second pair of pawls 39 and 40 extending from the
first end towards the second end at the outer peripheral portion of flange
portion 33 and arranged radially opposite to each other (the so-called
"hopper feed t~e nut") are provided. Groove 50 has a transverse cross
section similar to that of groove 20, as shown in Figs. 3A-3C. The cross
sectional shape of a round U shape, a V shape, or a squared U shape is
appropliately selected according to the matelial and working property of
the tee nut, or the mechanical property such as tensile strength 6.
The fixation by caulking relative to through hole 18 of object 19 of
fixation is similar to that of tee nut 11 of the first embodiment as shown in
Fig. 4B, provided that the anti-disengage effect is more secure by virtue of
the two pair of pawls 37, 38 and 39, 40 digging further deeper into the
bottom surface of object 19 of fixation. Therefore, the method using jig 70
can be employed in removing tee nut 61 from object 19 for recycling
purposes, as in the first embodiment corresponding to Figs. 5A and 5B.
[Third Embodiment]
The location of grooves 20 and 50 is not limited to the site at the
outer pelimeter of shaft portions 12 and 32 in the proximity of the interface
between portions 14 and 34 to be caulked and female thread formation
portions 15 and 35 as in tee nuts 51 and 61 of the previous embodiments.
More specifically, when only a local area of portions 14, 34 at the open end
CA 022~4634 1998-11-27
side is bent by cauL~ing as shown in the chain line with two dots in Fig. 6A,
annular grooves 20, 50 can be provided a little to the caulked portions 14,
34 side than the interface between portions 14, 34 to be caulked and female
thread formation portions 15 and 35. The method desclibed with reference
to Figs. 5A and 5B can be employed to remove the tee nut from object 19 of
fixation even in the case where the groove is formed at such a location.
In the case where the groove is provided at portion 14 to be caulked,
a .simil~r effect can be exhibited by providing the groove at the inner
peIimeter of shaft portions 12 and 32 as shown in Fig. 6B, or at both the
inner and outer perimeters of shaft portions 12 and 32 as shown in Fig. 6C.
lFourth Embodiment]
In the above embodiments, annular grooves 20 and 50 are provided
in the proximity of the interface between potions 14, 34 to be caulked and
female thread formation portions 15, 35, or at the outer perimeter of shaft
portions 12 and 32 corresponding to the region of portions 14, 34 to be
caulked. The ~resent invention is not limited to this location, and annular
grooves 20, 50 can be provided at the outer perimeter of female thread
formation portions 15 and 35 as shown in Fig. 7A.
When grooves 20, 50 are provided at the outer peIimeter of female
thread formation portions 15, 35, the det~ching method shown in Figs. 5A
and 5B cannot be employed. In this case, a wedge-like jig is inserted at the
abutment between caulked portions 14a, 34a or flange portions 13, 33 and
the face of object of fixation 19 with the tee nut inserted and caulked
relative to object 19. Tensile stress is exerted at the shaft portion to cause
fracture at the groove. As a result, the tee nut is broken into two parts to
allow detachment from object 19 of fixation.
As a modification of the present embodiment where grooves 20, 50
are provided at the outer perimeter of female thread formation portions 15,
35, a structure can be provided having relatively thin-walled regions 15b,
3Gb formed locally at the inner peripheral face of female thread formation
portions 15, 35. Thin-walled regions 15b, 36b are recessed with a
predetermined width in the extending direction of the shaft portion and do
not have an internally threaded surface. Annular grooves 20, 50 can be
- 18-
CA 022~4634 1998-11-27
formed at the outer peripheral surface of female thread formation portions
15, 35 corresponding to the area of thin-walled regions 15b, 36b. In this
case, the tee nut can easily be detached at the time of recovery for recycling
purposes since the waJl corresponding to the portion where relatively
shallow and thin grooves 20, 50 are provided can be made thin enough.
In the cases of the third and fourth embodiments, the shape of the
transverse cross section of the groove can be selected appropriately as
shown in Figs. 3A, 3B and 3C. Also, the configuration of flanges 13 and 33
are not limited to the circular or octagonal shape as in the above
embodiments. The terhnic~l concept of the present invention of
facilitating separation and detachment for recycling purposes by forming
grooves 20, 50 in shaft portions 12, 32 is .~imil~rly applicable even when the
flange takes another shape.
[Fifth Embodiment]
In the above described embodiments, annular thin-walled portions
are locally provided by forming annular grooves 20, 50 in shaft portions 12,
32. An annular thin-walled portion can be also formed by narrowing down
portion 34 to be caulked to be reduced in diameter so that shaft portion 32
is drawn radially. As a result, an annular thin-walled portion 70 around
the complete perimeter at the interface between portion 34 to be caulked
and female thread formation portion 35 is provided.
By inserting a wedge-like jig to the abutment between the portion to
be caulked or the flange portion and the face of the object of fixation in a
caulked state, tensile stress is exerted at the shaft portion to cause fracture
at the annular thin-walled portion. The tee nut is separated into two parts
and can be removed from the object of fixation.
In the structure of Figs. 8A and 8B, shaft portion 32 is drawn
radially by narrowing down the diameter of portion 34 to be caulked. In
an opposite manner, shaft portion 32 can be drawn radially by forming
portion 34 to be caulked so as to be increased in diameter. By forming
portion 34 to be caulked so as to have a smaller or larger diameter relative
to female thread formation portion 35, an annular thin-walled portion of
shaft portion 32 drawn radially can be formed completely around the
- 19-
CA 022~4634 1998-11-27
pelimeter at the interface between portion 34 to be caulked and female
thread formation portion 35.
[Sixth Embodiment]
The structure of a tee nut 81 according to a sixth embodiment of the
present invention will be desclibed hereinafter with reference to Fig. 9A.
In Fig. 9A, elements identical to or corresponding to tee nut 61 of the
second embodiment of Fig.2A have the same reference characters allotted,
and their descliption will not be repeated.
The present embodiment is an application of the present invention to
the tee nut disclosed in U.S. Patent No. 5,618,144. Tee nut 81 of the
present embodiment is common to the tee nut of the above-desclibed
embodiments in that it is the so-called rivet type tee nut. The difference
lies in the configuration of the portion to be caulked. More specifically, tee
nut 81 of the present embodiment has a portion 134 to be caulked of shaft
portion 32, as shown in Fig. 9A. Portion 134 has an inner diameter and an
outer diameter~greater than the inner diameter and the outer diameter,
respectively, of female screw formation portion 35.
At the circumference of shaft portion 32 in the proximity of the
interface between portion 134 to be caulked and female thread formation
portion 35, an annular groove 50 .~imil~t to that of the second embodiment
is formed around the entire perimeter. The object, specific configuration,
and detachment for recycle usage are simil~r to those desclibed in
association with annular groove 50 of the second embodiment.
Fig. 9B shows a modification of the present embodiment. This tee
nut 91 is .~imil~r to tee nut 81 of Fig. 9A in that portion 134 to be caulked ofshaft portion 32 has an inner diameter and an outer diameter greatér than
the inner diameter and the outer diameter, respectively, of female thread
formation portion 35. Tee nut 91 differs from tee nut 81 in that an
annular thin-walled portion 70 simil~r to that of the fifth embodiment is
provided instead of annular groove 50 at the outer circumference of shaft
portion 32 in the proximity of the interface between portion 134 to be
caulked and female thread formation portion 35.
Annular thin-walled portion 70 of tee nut 91 can be formed by
- 20 -
CA 022~4634 1998-11-27
increasing the inner and outer diameter of portion 34 to be caulked and
drawing shaft portion 32 in the direction of the radius. The advantage of
including annular thin-walled portion 70 is similar to that of annular thin-
walled portion 70 of tee nut 81 described in the fifth embodiment.
The above first to sixth embodiments show a structure in which the
present invention is applied to a tee nut having a female thread formed at
the inner peripheral face of the shaft portion. The present invention can
be applied in any of these embodiments with a rivet, absent of the
formation of a female thread at the inner pelipheral surface of the shaft
portion excluding the portion to be caulked.
[Seventh Embodiment]
A structure of a tee nut 101 according to a seventh embodiment of
the present invention will be described with reference to Fig. lOA. In tee
nut 101 of the present embodiment shown in Fig. lOA, the configuration of
shaft portion 32 and flange portion 33 is basically .~imil~r to those of tee nut61 of the seco~d embodiment. Therefore, in Fig. lOA, components simil~r
or corresponding to those of tee nut 61 of the second embodiment have the
same reference characters of Fig. 2A allotted, and their description will not
be repeated.
Tee nut 101 of the present embodiment differs from tee nut 61 of the
second embodiment in that an annular groove 150b of substantially a V
shape with a transverse cross section greater than that of annular groove
150a is also provided at the inner pelimeter of shaft portion 32 at a site
substantially opposite to annular groove 150a, in addition to annular groove
150a provided at the outer perimeter of shaft portion 32. Annular groove
150 is formed at the interface between portion 34 to be caulked and female
thread formation portion 35. The wall of shaft portion 32 is thinnest at the
region where annular groove 150a is located opposite to annular groove
150b. In detaching the tee nut from the panel material to which the tee
nut is secured in a caulked manner by a method simil~r to that shown in
Figs. 5A and 5B, shaft portion 32 is broken at this region where the wall is
thinnest to be separated. Thus, recovery is facilitated.
Fig. lOB shows a vertical sectional view of a rivet 111 having a
CA 022~4634 1998-11-27
structure .qimil~r to that of tee nut 101, provided that a female thread is not
formed at the inner pelipheral face of the main body 135 of the shaft
portion corresponding to the female thread formation portion 35 of tee nut
101. This rivet 111 can be used as a reinforced bore through which a bolt
is passed in fastening a plurality of metal layered sheets with a bolt. Rivet
111 of this structure is used in a manner fixed in a hole of the plate in a
caulked manner, .simil~r to tee nut 101. Detachment is effected by
fracture .qimil~r to the method shown in Figs. 5A and 5B to facilitate
recovery.
The method of forming portion 34 to be caulked and annular grooves
150a and 150b in a metallic fastening member having a structure such as
tee nut 101 or rivet 111 will be described hereinafter with reference to Figs.
11-14C.
Fabrication of tee nut 101 or rivet 111 is set forth in the following.
Referring to Fig. 11, a longitudinal strip of metal plate 201 formed of, for
example, iron ~aterial, is prepared. Metal plate 201 is sequentially
forwarded in an intermediate manner at a predetermined pitch in the
longitudinal direction indicated by arrow 202 to be subjected to a
predetermined work at respective stations.
First, a cut 204 is formed around a portion 203 to determine the
position of the region corresponding to flange portion 33 on metal plate 201.
In order to maintain the state in which portion 203 is held by the other
portion of metal plate 201 during the subsequent various processes applied
on portion 203, cut 204 is not formed around the entire circumference of
portion 203. Cut 204 is provided so that a deformable joining portion is
formed between a plurality of positions at the circumference of portion 203
and the r~m~ining portion of metal panel 201.
A deep drawing process is applied on metal plate 201 to expand the
central area of portion 203 that will become a flange portion 33 towards the
lower main surface of metal plate 201. This deep drawing work is carlied
out over a plurality of stages. At working station [a] shown in Fig. 11
which is the final stage, an expansion 205 which becomes shaft portion 32 is
formed. Since this expansion 205 is formed of a partial portion 203
CA 022~4634 1998-11-27
surrounded by cut 204, the width of cut 204 is expanded.
Following the provision of a through hole 206 at the leading end of
expansion 205 at working station [b], a relatively thin-wall leading end
portion 221 is formed corresponding to portion 34 to be caulked at working
stations [c]-[g] of Fig. 11. The details of the process applied at working
stations [a]-[c] and working stations [d]-[g] are shown in Figs. 12 and 13,
respectively, in an enlarged manner.
As shown in Figs. 12 and 13, a mold die 207 is arranged below metal
plate 201. A clamp die 208 is arranged above metal plate 201. Mold die
207 and clamp die 208 are set to come closer/farther away to/from metal
plate 201 in synchronization. Knock outs 211a-221g are maintained at the
mold die 207 side in association with each working station. Punches 212a-
212g are maintained at the clamp die 208 side.
In the operation of each working station, each of punches 212a-212g
is urged towards the inner peripheral side of expansion 201 with each of
knock outs 21 ~a-21 lg abutting against the lower end of expansion 205
while metal plate 201 is clamped between mold die 207 and clamp die 208.
Metal plate 201 is advanced intermittently as indicated by arrow 202 (Fig.
11) at every completion of the operation of mold die 207, clamp die 208,
knock outs 211a-221g and punches 212a-212g. A predetermined work is
applied on each expansion 205 in a sequentially manner.
At working station [c] that is leftmost of Fig. 12, the wall of leading
end portion 221 can be made thinner than the wall of base portion 222 by
setting the outer diameter of leading end portion 221 corresponding to
portion 34 to be caulked of expansion 205 smaller than the outer diameter
of base portion 222 corresponding to female thread formation portion 32 or
shaft main portion 132. More specifically, a forge plane 226 including a
large diameter portion 223, a slanting portion 224 and a small diameter
portion 225 is provided at mold die 207. Expansion of base portion 222 is
regulated by large diameter portion 223 of forge plane 22~, whereas
reduction in the inner diameter of leading end portion 221 is regulated by
punch 212c. The wall of leading end portion 221 is drawn thinner by the
outer diameter of leading end portion 221 being reduced by slanting portion
- 23 -
CA 022~4634 1998-11-27
/
224 and small diameter portion 225 of forge plane 226.
Here, the outer diameter of punch 212c is set slightly greater than
the inner diameter of base portion 222. As a result, a stepped portion is
formed at the inner pelipheral face at the position substantially facing the
stepped portion at the outer peripheral face of shaft portion 32 formed by
slanting portion 224 of forge plane 226.
The leading end of punch 212c used at working station [c] has a
hemispherical shape so that the punch is smoothly dliven without
damaging the surface of metal plate 201 in the deep drawing process of
leading end portion 221. Therefore, a crimp is formed at the end face of
leading end portion 72 at the deep drawing process of working station [c].
At the next working station [d], leading end portion 221 is formed to be
substantially cylindrical by punch 212d having a leading end of a
substantially a cylindrical shape while maintaining the wall thickness and
diameter of base portion 221.
At this vvorking station [d], punch 212d has a step portion at the
outer perimeter so that the inner diameter Djl of leading end portion 221 is
slightly smaller than the inner diameter Di2 of base portion 222, so that the
inner diameter is limited over the entire length of shaft portion 32. As a
result of the outer diameter and inner diameter settings of leading end
portion 221 and base portion 222 as described above, a step portion 223 is
provided at the outer perimeter at the interface between leading end
portion 221 and base portion 222, and a step portion 224 is provided at the
inner periphery of substantially a corresponding position.
At working stations [c] and [d] of the present embodiment, the
process of rendering the wall of leading end portion 221 of expansion 205
thinner than the wall of base portion 222 is effected by setting the outer
diameter of leading end portion 221 of expansion 205 slightly smaller than
the outer diameter of base portion 222 while limiting the inner diameter of
leading end 221 or the reduction of the inner diameter over the entire
length of shaft portion 32. This process can be carlied out in an opposite
manner by increasing the inner diameter of expansion 205 while forming
step portion 224 with the limitation of increase in the outer diameter of
- 24 -
CA 022~4634 1998-11-27
leading end portion 221 of expansion 205.
At working stations [e]-[g], the inner diameter and the outer
diameter of base portion 222 are gradually reduced while maint~ining the
wall thickness without changing the inner diameter Dil and the wall
thickness of leading end portion 221. More specifically, inner diameters
Di3 and Di4 of base portion 222 in Figs. 14B and 14C corresponding to
working stations [fl and [g] show the transition of Di2 ~ Di3 ~ Di4. At
working station [g] in Fig. 14C, the outer diameter of leading end 221 and
base portion 222 is substantially identical. Inner diameter Di4 Of base
portion 222 becomes smaller than inner diameter Dil of leading end portion
221.
More specifically, at working station [e], a forge plane 234 including
larger diameter portion 231 having an inner diameter smaller than large
diameter portion 223, a slanting portion 232, and a small diameter portion
233 is provided at mold die 207. The outer peripheral face of base portion
222 is pressed~inwards by forge plane 234. Punch 212e serves to prevent
base portion 222 from being deformed into an undesired shape.
Simil~rly at working stations [fl and [g], the outer peripheral face of
base portion 222 is urged inwards by the forging plane of mold die 207
while maintaining the diameter of leading end portion 221. The outer
diameter of base portion 222 becomes substantially equal to the outer
diameter of leading end portion 221 at the passage of working station [g].
At working station [g], the straight forge plane 235 provided at mold die
207 causes the outer peripheral plane of base portion 222 to be urged
further inwards. As a result, expansion 205 has substantially a uniform
outer diameter. Punches 212f and 212g at working stations [f~ and [g]
function in a manner .~imil~r to that of punch 212e of working station [e].
According to the sequential forward press process of the present
embodiment, a relatively small annular groove 150a is formed at the outer
perimeter and an annular groove 150b having a transverse cross section
greater than that of annular groove 150a is formed at the inner perimeter
of shaft portion 32 in the proximity of the interface between leading end 221
and base portion 222 of shaft portion 32 as a result of the transition of the
- 25 -
CA 022~4634 1998-11-27
deformation to form a relatively thin-walled leading end portion 221.
Then, although not shown, portion 203 that becomes flange portion
33 is cut apart from metal plate 201. Each intermediate product of the tee
nut or livet formed as described above is barrel polished to remove any burr
generated during the process. In the event of forming tee nut 101, the
process of forming female thread 35 at the inner peripheral face of base
portion 222 corresponding to shaft portion 32 is then carlied out.
According to the above-desclibed fabrication method, portion 34 to be
caulked of tee nut 101 or rivet 111 of the present embodiment can be
formed, not by a cutting process, but by a plastic forming process. By the
series of processes including the plastic forming process to produce
expansion 205 that becomes shaft portion 32 in the fabrication of tee nut
101 or livet 111, the molding process can be carlied out together with the
formation of annular grooves 150a and 150b to facilitate separation for
recycling purposes. Since each process can be carlied out by advancing a
long ship of me~tal plate 201 using the forward die, the complication in
processing an intermediate product of different states can be elimin~ted.
Fabrication of tee nut 101 or livet 111 of the present embodiment can be
carried out efficiently.
A structure of a tee nut 121 and a livet 131 which is a modification of
the present invention will be described with reference to Figs. 15A and 15B.
The structure of tee nut 121 and rivet 131 differs from the structure of tee
nut 101 and rivet 111 shown in Figs. lOA and lOB is that an annular
groove 150c provided at an inner perimeter of shaft portion 32 in the
proximity of the interface between portion 34 to be caulked and female
thread formation portion 35 or shaft portion 135 has substantially a planar
bottom face with a predetermined width. Annular groove 150a provided at
the outer perimeter of shaft portion 32 is located opposite to the flat bottom
of annular groove 150c at the flange 33 side.
When the transverse cross section is formed to have substantially a V
shape as annular groove 150b at the inner perimeter of shaft portion 32 of
tee nut 101 and livet 111, the bottom portion will extend linearly. This
means that variation in the depth of annular groove 150b easily occurs due
- 26 -
CA 022~4634 1998-11-27
to any slight variation in the working operation during the press mold
process. In contrast, by the advantage of the configuration of annular
groove 150c having a flat bottom face of a predetermined width as in tee
nut 121 and rivet 131, there is hardly no valiation in the depth even if the
working operation duling the press mold process is slightly valied. There
is only a slight variation in the width of the substantially flat bottom of
annular groove 150c. Thus, a shaft portion 32 of the desired thinnest wall
can be obtained stably. Furthermore, in the state where portion 34 is
caulked, it will become easier for the end portion bent by caulking at the
flange side to overlap the position where the bottom of annular groove 150c
is located. By overlapping the end of the portion bent by caulking at the
flange side with the position where the bottom face of annular groove 150c
is located, there is an advantage that the detachment in the separation
process for recycling purposes can be carried out relatively easier.
Tee nut 121 or livet 131 having such an annular groove 150c can be
formed by the ~equential forwarding press process shown in Fig. 16
corresponding to Fig. 13. More specifically, the tee nut 121 or livet 131
having such an annular groove 150c can be formed by setting the position of
step portion 224 at the inner perimeter of shaft portion 32 to be located
substantially opposite to the end portion of step portion 223 at the leading
end 221 side at the outer perimeter of shaft portion 32, as shown in an
enlarged manner in Fig. 17A in working station [d] desclibed with reference
to Fig. 16. This is because the portion at the inner peripheral face of base
portion 222 adjacent to step portion 224 remains substantially planar at
working stations [e] - [g] reducing the inner diameter and the outer
diameter of base portion 222. This portion corresponds to the bottom
plane of annular groove 150c. The neighborhood of leading end portion
221 of shaft portion 32 at working stations [e] and [g] are shown in Figs.
17B and 17C, respectively.
Annular grooves 105a, 105b and 105c of the present embodiment are
also applicable to the tee nut disclosed in U.S. Patent No. 5,618,144. More
specifically, Fig. 18A shows a tee nut 141 which is the tee nut of U.S.
Patent No. 5,618,144 incorporating annular grooves 105 and 105b .simil~r to
- 27 -
CA 022~4634 1998-11-27
tee nut 101 shown in, for example, Fig. lOA. Also a livet 151 as shown in
Fig. 18B can be provided by not forming a female thread at the inner
perimeter of female thread formation portion 35 of tee nut 141. Also, Fig.
l9A shows a tee nut 161 which is the tee nut of U.S. Patent No. 5,618,144
incorporating annular grooves 105 and 105c simil~l to tee nut 121 shown in
Fig. 15A. Also, a rivet 171 as shown in Fig. l9B can be provided by not
forming a female thread at the inner pelimeter of female thread formation
portion 35 of tee nut 161.
Although each of the above-described embodiment has a structure in
which pawls 16 and 17-40 are provided at the outer pelimeter of flange
portions 13 and 33, the flange portion may have a planar configuration
without a pawl. Also the flange portion does not necessarily have to be
sized as in the above-described embodiments. A metallic tee nut or rivet
having a configuration protruding slightly outwards than the outer
perimeter of the shaft main portion so as to function as an engagement
member in being dliven into an object of fixation is read on the invention of
the present application.
[Eighth Embodiment]
The structure of a tee nut 181 according to an eighth embodiment of
the present invention will be described with reference to Fig. 20A. Tee nut
181 of the present embodiment has a configuration, as shown in Figs. 20A
and 21A, simil~r to that of tee nut 101 of the seventh embodiment described
with reference to Fig. lOA. Therefore, common components have the same
reference characters allotted, and detailed description thereof will not be
repeated.
Tee nut 181 of the present embodiment differs from tee nut 101 of
the seventh embodiment in the following points. Shaft portion 32 has a
stepped portion 103 around the entire perimeter of female thread formation
portion 34 in the proximity of the flange 33 side. A distal end hollow
cylindrical portion 104 at the portion to be caulked 34 side than stepped
portion 103, and a hollow proximal end enlarged cylindrical portion 105 at
the flange portion 33 side than stepped portion 103 are provided with
stepped portion 103 as the boundary.
- 28 -
' CA 022~4634 1998-11-27
According to the tee nut of the above structure, an advantage set
forth in the following is provided in addition to the advantage similar to
that of tee nut 101 by providing annular grooves 105a and 105b at distal
end hollow cylindlical portion 104 in shaft portion 32. By the provision of
stepped portion 103 in shaft portion 32 with proximal end enlarged
cylindrical portion 105 at the flange portion 33 side, distal end hollow
cylindrical portion 104 including portion 34 to be caulked and female thread
formation portion 35 can be made relatively shorter. A longer female
thread formation portion 35 than needed does not have to be provided even
when shaft portion 32 has a great length. The shortest required length
matching the standard such as the JIS is only required. Therefore, the
number of extra working steps in the threading process by a tap can be
reduced to improve the productivity of the tee nut.
As a modification of the present invention, the configuration of distal
end hollow cylindrical portion 104 of shaft portion 32 can be applied to the
structure simil~r to that of tee nut 121 of the seventh embodiment shown in
Fig. 15A, resulting in tee nut 191 shown in Fig.20B. By such a structure,
both the advantage of annular grooves 150A and 150C of tee nut 121, and
the advantage by virtue of provision of stepped portion 103 can be enjoyed.
The flange of the tee nut of the present embodiment is not limited to
that of tee nuts 181 and 191. A flange of a configuration .qimil~r to that of
tee nut 51 shown in Fig. lB can be provided, as shown in Fig.2 lB of a tee
nut 201.
[Ninth Embodiment]
A tee nut 211 according to a ninth embodiment of the-present
invention will be described hereinafter with reference to Fig. 22A. Tee nut
201 of the present embodiment ~liffers from tee nut 181 of the above eighth
embodiment only in that a female thread is also formed at the inner
circumference of proximal end hollow cylindlical portion 105a at the flange
portion 33 side from stepped portion 103 of shaft portion 32. By virtue of
the structure of tee nut 201, female thread formation portion 35 at the
portion to be cauL~ed 34 side than stepped portion 103 can have the
smallest required length in the range defined by the standard such as the
- 29 -
CA 022~4634 1998-11-27
JIS. By fini.~hing the female thread of female thread formation portion 35
critically according to the specification corresponding to the requirement of
the standard, a female thread of a relatively rough dimension having a
diameter greater than that of the standard can be formed at the inner
circumference of proximal end hollow cylindlical portion 105a.
Accordingly, formation of the female thread in a tee nut having a relatively
long shaft portion is easier than that of a conventional tee nut that had the
female thread finished cIitically over the entire length of the region where
the female thread is to be formed. Thus, the productivity is improved.
There is also the advantage that the strength of the screw is increased by
forming a female thread also at the inner circumference of proximal end
hollow cylindrical portion 105a.
Fig. 22B shows a tee nut 121 which is a modification of the present
embodiment. The configuration of distal end hollow cylindrical portion 104
of shaft portion 32 is applied to a structure .simil~r to that of tee nut 121
which is a mod~lcation of the seventh embodiment shown in Fig. 15A. By
such a structure, both the advantage of annular grooves 150a and 150c of
tee nut 121 and also the advantage by virtue of provision of stepped portion
103 can be enjoyed.
[Tenth Embodiment]
In the region where the female thread is formed in the tee nuts of the
above-described embodiments, a screw that is partially irregular is
preferably formed as locking means to prevent unloosening of the screwed
bolt. In order to form an irregular screw thread partially, the process of
forming a concave portion 217 can be employed by indenting inwards a
portion of the outer pelipheral face of female thread formation portion 216
at shaft portion 212 of the tee nut, as shown, for example, in Figs. 23A and
23B. Two concave portions 217 are formed with an angular interval of, for
example, 180~. These concave portions 217 can be formed by sandwiching
predetermined locations of female thread formation portion 216 with a pair
of suitable tools and strongly urging these tools towards female thread
formation portion 216. By such a provision of an irregular portion 218 of
the female thread, the bolt cannot be moved unless the screwed bolt is
- 30 -
CA 022~4634 1998-11-27
rotated relatively forcefully. As a result, the screwed state is locked to
prevent the bolt from being unloose.
[Eleventh Embodiment]
The above embodiments correspond to a structure of a tee nut or a
rivet including a relatively large flange with substantially an octagonal or
circular shape with a pawl provided at the outer circumference of the flange.
However, the flange is not necessarily of a relatively large size. Also, the
pawl may be absent. More specifically, the concept of the above
embodiments is also applicable to the structure having a relatively small
flange 133 with an outer diameter slightly greater than that of shaft
portion 32, as in a tee nut 231 shown in Fig. 24A or a rivet 241 as shown in
Fig. 24B. Figs. 24A and 24B have the same reference characters allotted
for the components common to those of tee nut 101 or rivet 111 shown in
Figs. lOA and lOB. Detailed description thereof will not be repeated.
[Twelfth Embodiment]
The strllcture of a tee nut 251 according to a twelfth embodiment of
the present invention will be described hereinafter with reference to Figs.
25A and 25B and Figs. 26A and 26B. Tee nut 251 of the present
embodiment differs from tee nut 101 of the seventh embodiment shown in
Fig. lOA in that annular grooves 150a and 150b are not formed
continuously over the entire perimeter, and that there is a discontinuous
area. By providing such a discontinuous portion at annular grooves 150a
and 150b, the separation for detachment can be effected by a relatively
small tensile force since stress acts intensively at annular grooves 150a and
150b at the area corresponding to the discontinuous portion to commence
fracture from that area.
The discontinuous area of annular grooves 150a and 150b is not
limited to one area. The intermittent portion can be provided at a
plurality of areas. By appropriately altering the number of intermittent
areas or the ratio of the length of the discontinuous area to the entire
perimeter when the intermittent portion of annular grooves 150a and 150b
are provided at a plurality of areas, the mechanical strength of that area
can be adjusted, as necessary.
- 31 -
CA 022~4634 1998-11-27
Figs. 27A and 27B show the structure of the present embodiment
applied to a rivet 2Gl lacking the female thread at the inner circumference
of shaft main portion 135 of shaft portion 32. Figs. 28A and 28B show the
structure in which the present embodiment is applied to a tee nut 271
having a configuration simil~r to that of tee nut 231 shown in Fig. 24A.
Figs. 29A and 29B show a structure of the present embodiment applied to a
rivet 281 having a configuration simil~r to that of livet 241 of Fig. 24B.
Annular grooves 150a and 150b provided at the outer perimeter of
shaft portion 32 can be formed to have a stepped portion at the
discontinuous area, as livets 291 and 301 shown in Figs. 30A, 30B, 31, 32A
and 32B.
[Thirteenth Embodiment]
A tee nut 311 according to a thirteenth embodiment of the present
invention will be desclibed hereinafter with reference to Figs. 33A and 33B.
Formation of a thin-walled portion of shaft portion 32 to facilitate
detachment fo~ recycle purposes of tee nut 311 of the present embodiment is
realized by forming a plurality of dents 150d in an intermittent manner in
the substantially annular region in the proximity of the interface between
portion 34 to be caulked and female thread formation portion 35, as shown
in Fig. 33A and 33B, absent of the annular groove. Such a dent 150d can
be formed at the inner peripheral side of shaft portion 32. Alternatively,
the dent can be formed at both the inner perimeter and the outer pelimeter
of shaft portion 32. According to tee nut 311 of the present embodiment,
the size, depth, distance from an adjacent dent 150d, and the like can be
modified appropriately to allow adjustment of the mechanical strength of
this area, as necessary.
Figs. 33A and 33B show a structure in which the present
embodiment is applied to a tee nut. The present embodiment is equally
applicable to a rivet that does not have a female thread formation portion.
Although an example of the structure having a relatively large flange
portion with a pawl is shown in Figs. 33A and 33B, .~imil~r application can
be made to a tee nut or a livet having a flange of a relatively small
diameter shown in Fig. 24.
- 32 -
CA 022~4634 1998-11-27
[Fourteenth Embodiment]
A tee nut 321 according to a fourteenth embodiment of the present
invention will be desclibed hereinafter with reference to Fig. 34A. The
structure of tee nut 321 of the present embodiment is mainly common to the
structure of tee nut 101 shown in Fig. lOA. The structure of tee nut 321 of
the present embodiment differs from the structure of tee nut 101 in that a
small climped annular groove 150e extending in the direction of the
pelimeter is formed at the inner plane of annular groove 150b provided at
the inner peripheral face of shaft portion 32 in the proximity of the
interface between portion 34 to be caulked and female thread formation
portion 35. Also, portion 34 to be caulked is formed to have an outer
diameter slightly smaller than the outer diameter of female thread
formation portion 35. The structure of the present embodiment is
applicable to livet 111 of Fig. 10. Also, the present embodiment is
applicable to a metallic fastening member such as tee nut 231 or livet 241
of Fig. 24, as a~tee nut 331 of Fig. 34B. Furthermore, the present
embodiment is applicable to the livet shown in Figs. lOB and 24B, as rivets
341 and 351 shown in Figs. 35A and 35B, respectively. A climped small
annular groove can further be provided at the inner side of the annular
groove having substantially a planar bottom such as annular groove 150c of
tee nut 121 or livet 131 of Fig. 15.
By providing a small annular groove 150e at the inner face of
annular groove 150b (or 150c), the separation by fracture can further be
improved in the detachment work for recycle purposes. Since the outer
diameter of portion 34 to be caulked is made slightly smaller than the outer
diameter of female thread formation portion 35, the portion to be caulked
that has a relatively small diameter can function as a guide even in the
case where there is a slight error in the positioning between tee nut 321
and the companion hole in the insertion of tee nut 321 to the object of
fixation. Therefore, the tee nut can be inserted reliably to the companion
hole.
The small crimped annular groove 150e of the present embodiment
can be formed by including the step of shaping portion 34 so as to be pushed
- 33 -
CA 022~4634 1998-11-27
upwards with a knock out, as a step subsequent to working station [g]
shown in Fig. 13 or 16. More specifically, at working station [h] adjacent
to working station [g] as shown in Fig. 36, the inner diameter of leading end
portion 221 is restlicted by a reduction diameter portion 211x in the
proximity of the upper end of knock out 21 lh while restricting the inner
diameter of base portion 222 with punch 212h. Also, a stepped portion
211z of knock out 21 lh at the upper end of the base portion side 21 ly
pushes upwards the leading end face of leading end portion 211 with knock
out 21 lh for shaping. By this step, a crimped small annular groove 150e is
formed at the inner surface of annular grooves 150b and 150c, as shown in
an enlarged manner in Fig. 37. The outer diameter of leading end portion
211 is made slightly smaller than the outer diameter of base portion 222.
Thus, the shape of the tee nut or the rivet shown in Figs. 34 and 35 with
respect to the neighborhood of the portion to be caulked is completed.
Although a smalI annular groove 150e at the inner face of annular
grooves 150b ~nd 150c in the embodiment shown in Figs. 34 and 35 is
formed continuously along the entire pe~imeter, a small crimped annular
groove 150e can be formed having a partial discontinuous area at the inner
face of annular grooves 150b and 150c, as tee nuts 361 and 371 shown in
Figs. 38A and 38B, and livets 381 and 391 shown in Figs. 39A and 39B.
Although the present invention has been described and illustrated in
detail, it is cleally understood that the same is by way of illustration and
example only and is not to be taken by way of limitation, the spirit and
scope of the present invention being limited only by the terms of the
appended claims.
- 34 -
