U.S. patent application number 11/704780 was filed with the patent office on 2007-07-05 for nut feed system and method of feeding nuts.
Invention is credited to John J. Vrana.
Application Number | 20070155516 11/704780 |
Document ID | / |
Family ID | 35374218 |
Filed Date | 2007-07-05 |
United States Patent
Application |
20070155516 |
Kind Code |
A1 |
Vrana; John J. |
July 5, 2007 |
Nut feed system and method of feeding nuts
Abstract
A nut feed system and method of feeding nuts through a nut feed
passage which avoids contact between the feed pawl and the nut
bore. The end face of the nut includes a nut feed groove extending
perpendicular to the nut bore and the free end of the feed pawl is
received in the groove to drive the nuts through a nut feed passage
without contacting the bore. The disclosed embodiment of the nut
includes a counterbore through the end face and radial
channel-shaped feed grooves and the feed pawl includes a
cylindrical center portion and radial portions received in the
counterbore and feed grooves.
Inventors: |
Vrana; John J.; (Rochester
Hills, MI) |
Correspondence
Address: |
HOWARD & HOWARD ATTORNEYS, P.C.
THE PINEHURST OFFICE CENTER, SUITE #101
39400 WOODWARD AVENUE
BLOOMFIELD HILLS
MI
48304-5151
US
|
Family ID: |
35374218 |
Appl. No.: |
11/704780 |
Filed: |
February 9, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10847795 |
May 18, 2004 |
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11704780 |
Feb 9, 2007 |
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Current U.S.
Class: |
470/18 |
Current CPC
Class: |
B23P 19/062
20130101 |
Class at
Publication: |
470/018 |
International
Class: |
B21D 53/24 20060101
B21D053/24 |
Claims
1. A method of feeding nuts through a nut feed passage, each of
said nuts including a body portion having an end face and a bore
extending through said body portion through said end face, said
method comprising the following steps: forming a nut feed groove in
said end face of said nut on opposed sides of said bore extending
generally perpendicular to an axis of said bore; locating an end
portion of a reciprocable nut feed pawl located in said feed
passage in said nut feed groove; and reciprocating said nut feed
pawl to feed said nut through said nut feed passage.
2. The method of feeding nuts as defined in claim 1, wherein said
method includes forming said nut feed groove in said end face
through an axis of said bore, thereby forming separate nut feed
grooves on opposed sides of said bore, each having an open inner
end opening into said bore.
3. The method of feeding nuts as defined in claim 1, wherein said
method includes forming a channel-shaped nut feed groove in said
end face having a bottom wall and opposed side walls.
4. The method of feeding nuts as defined in claim 1, wherein said
method includes forming a counterbore in said end face coaxially
aligned with said bore and said groove extending through said axis
of said bore, thereby forming nut feed grooves on opposed sides of
said bore, and locating said end portion of said reciprocable feed
pawl having a semicircular portion in said counterbore and radial
portions in said nut feed grooves.
5. The method of feeding nuts as defined in claim 4, wherein said
method includes forming channel-shaped nut feed grooves on opposed
sides of said bore, each having a bottom wall and opposed side
walls extending generally perpendicular to said end face and
engaging an end portion of said nut feed pawl against one of said
side walls.
6. The method of feeding nuts as defined in claim 5, wherein said
method includes locating radial portions of said reciprocable feed
pawl in said grooves having a width less than a width of said
grooves measured between said side walls and engaging one of said
side walls.
7. The method of feeding nuts as defined in claim 1, wherein said
method includes forming linear wire grooves in said end face of
said nut on opposed sides of said nut feed groove extending
generally perpendicular to said nut feed groove and locating
frangible wires in said linear wire grooves interconnecting said
nut to adjacent nuts in a continuous strip.
8. A method of feeding nuts through a nut feed passage, each of
said nuts including a body portion having an end face and a bore
extending through said body portion through said end face, said
method comprising the following steps: forming channel-shaped nut
feed grooves in said end face of said nuts on opposed sides of said
bore having an axis intersecting said bore; locating end portions
of a reciprocable feed pawl in said channel-shaped feed grooves;
and reciprocating said feed pawl to feed said nuts through said
feed passage.
9. The method of feeding nuts as defined in claim 8, wherein said
method includes forming said channel-shaped nut feed grooves in
said end face of said nuts each having a bottom wall and opposed
side walls extending generally perpendicular to said end face of
said nut.
10. The method of feeding nuts as defined in claim 8, wherein said
method includes forming linear wire grooves in said end face of
said nuts on opposed sides of said channel-shaped nut feed grooves
extending perpendicular to said nut feed grooves and locating
frangible wires in said linear wire grooves interconnecting said
nuts in a continuous strip.
11. The method of feeding nuts as defined in claim 8, wherein said
method includes forming a counterbore in said end face of said nut
coaxially aligned with said bore having a diameter greater than
said bore, and locating said end portion of said feed pawl having a
central semicircular portion received in said counterbore and
radial portions received in said channel-shaped nut feed
grooves.
12. The method of feeding nuts as defined in claim 11, wherein said
method includes forming said channel-shaped nut feed grooves in
said end face of said nuts having a width measured between said
side walls less than a width of said radial portions of said end
portion of said feed pawl.
13. The method of feeding nuts as defined in claim 1 1, wherein
said method includes forming said counterbore in said end face
having a cylindrical outer surface.
14. The method of feeding nuts as defined in claim 11, wherein said
method includes forming said channel-shaped nut feed grooves with
each groove extending perpendicular to said bore, each having an
inner portion communicating with said counterbore.
15. A method of feeding nuts through a nut feed passage, each of
said nuts including a body portion having an end face and a bore
extending through said body portion through said end face, said
method comprising the following steps: forming a counterbore
through said end face of said nuts coaxially aligned with said bore
having a diameter greater than said bore and radial nut feed
grooves having an inner portion communicating with said
counterbore; forming a reciprocable nut feed pawl having an end
portion including an arcuate central portion configured to be
received in said counterbore and radial portions configured to be
received in said radial nut feed grooves; receiving said nuts in
said nut feed passage with said end face opposite said end portion
of said reciprocable nut feed pawl; receiving said arcuate portion
in said counterbore and said radial portions in said radial nut
feed grooves of one of said nuts; and reciprocating said
reciprocable nut feed pawl to feed said one of said nuts through
said nut feed passage.
16. The method of feeding nuts as defined in claim 15, wherein said
method includes forming channel-shaped radial nut feed grooves in
said end face of said nuts each having a bottom wall and opposed
planar side faces and forming said radial portions of said end
portion of said reciprocable nut feed pawl having planar end faces
adapted to engage one of said planar side faces of said radial nut
feed grooves.
17. The method of feeding nuts as defined in claim 15, wherein said
method includes forming said counterbore having a cylindrical outer
surface coaxially aligned with said bore and forming said arcuate
central portion of said end portion of said reciprocable nut feed
pawl having a cylindrical surface adapted to be received in said
cylindrical outer surface of said counterbore.
18. The method of feeding nuts as defined in claim 17, wherein said
method includes forming a chamfered arcuate end surface on said
cylindrical surface of said end portion of said reciprocable nut
feed pawl.
19. The method of feeding nuts as defined in claim 15, wherein said
method includes forming linear wire grooves in said end face of
said nuts on opposed sides of said radial nut feed grooves
extending generally perpendicular to said nut feed grooves and
locating frangible wires in said linear wire grooves
interconnecting said nuts in a continuous strip, whereby said
method includes reciprocating said reciprocable nut feed pawl to
feed a plurality of said nuts through said nut feed passage.
20. A reciprocable nut feed pawl for feeding nuts through a nut
feed passage, said nut feed pawl having an end portion including a
generally semicircular central portion and radial portions
extending from a midportion of said generally semicircular portion
each having a planar drive face intersecting said generally
semicircular central portion.
21. The reciprocable nut feed pawl as defined in claim 20, wherein
said generally semicircular central portion has a cylindrical outer
surface.
22. The reciprocable nut feed pawl as defined in claim 20, wherein
said generally cylindrical outer surface defines an arc of less
than 150 degrees.
23. The reciprocable nut feed pawl as defined in claim 20, wherein
said end portion of said reciprocable nut feed pawl includes a
planar back face.
24. The reciprocable nut feed pawl as defined in claim 23, wherein
said planar back face is inclined relative to an axis of said
generally semicircular portion from an end of said end portion.
25. The reciprocable nut feed pawl as defined in claim 24, wherein
said back face is inclined relative to a tangent of said generally
semicircular surface at an angle of between 20 and 60 degrees.
26. The reciprocable nut feed pawl as defined in claim 20, wherein
said end portion of said reciprocable nut feed pawl includes an
inclined back face inclined relative to an axis of said generally
semicircular central portion and an arcuate end surface blending
into said inclined back face.
27. The reciprocable nut feed pawl as defined in claim 20, wherein
said generally semicircular central portion of said end portion of
said reciprocable nut feed pawl includes an arcuate chamfered end
surface.
28. A reciprocable nut feed pawl for feeding nuts through a nut
feed passage, said reciprocable nut feed pawl having an end portion
including a nut engaging face having a generally cylindrical
surface defining an arc of less than 180 degrees and radial
portions extending radially from said generally cylindrical surface
each having a planar drive face intersecting said generally
cylindrical surface.
29. The reciprocable nut feed pawl as defined in claim 28, wherein
said cylindrical surface defines an arc of less than 150
degrees.
30. The reciprocable nut feed pawl as defined in claim 28, wherein
said end portion of said reciprocable nut feed pawl includes an
inclined planar back face.
31. The reciprocable nut feed pawl as defined in claim 28, wherein
said end portion of said reciprocable nut feed pawl includes an
inclined back face inclined relative to an axis of said generally
cylindrical surface at an angle of between 20 and 60 degrees.
32. The reciprocable nut feed pawl as defined in claim 31, wherein
said end portion of said reciprocable nut feed pawl includes an
arcuate end face blending into said inclined back face.
33-50. (canceled)
Description
FIELD OF THE INVENTION
[0001] This invention relates to a nut feed system, including a
method of feeding nuts, a nut feed pawl and a nut configured to
receive a nut feed pawl for feeding nuts through a nut feed passage
without contacting the nut bore, thereby avoiding damage of the nut
bore during feeding.
BACKGROUND OF THE INVENTION
[0002] Nuts are typically fed through a nut feed passage by
reciprocating a nut feed pawl having a finger received in the nut
bore. The nut feed pawl is typically pivotally mounted on a feed
mechanism, wherein the nut feed pawl is biased by a spring,
pneumatic or hydraulic pressure or a positive linkage to
reciprocate through the nut feed passage. The nut bore may be
threaded or unthreaded to receive a thread forming or thread
rolling male fastener, such as a bolt or screw. Nuts are fed
through a nut feed passage for various purposes including, but not
limited to, secondary operations, such as interconnecting the nuts
in a strip, and installation. However, the nut feed pawl may deform
or damage the nut bore during feeding of the nuts through a nut
feed passage making it difficult or impossible to thread a male
fastener into the nut bore. For example, the nuts may be jammed or
cocked in the nut feed passage and the force of the finger of the
nut feed pawl in the thread cylinder may be sufficient to damage a
threaded nut bore or an unthreaded nut bore.
[0003] This is a particular problem with self-attaching nuts,
including pierce, clinch and weld nuts, wherein the nut is
permanently attached to a metal panel because the entire nut and
panel assembly may have to be scrapped if the nut bore cylinder is
damaged. In many applications, such as automotive applications,
several self-attaching nuts are simultaneously attached to a panel,
such as a bracket, frame or vehicle body component and the male
fasteners are typically threaded into the nuts with a torque
wrench. Thus, if the thread cylinder (threaded or unthreaded) of
one of the nuts is damaged or distorted, a male fastener may
crossthread in the nut bore or it may not be possible to thread the
male fastener into the nut bore, requiring scrapping or
retrofitting the entire assembly. As used herein, the term "nut"
includes any female fastener having a threaded or unthreaded bore.
Thus, there has been a long felt need for a method of feeding nuts
through a feed passage using a feed pawl which does not engage the
nut bore, eliminating damage or distortion of the nut bore.
[0004] Various attempts have been made by the Applicant and others
to eliminate damage to the nut bore or thread cylinder through
feeding of nuts through a nut feed passage, including providing
notches in the side faces of the nut and feeding the nuts with two
feed pawls or ratchets on opposed sides of the nuts which feed the
nuts to a fastener installation head or for secondary operations,
such as interconnecting the nuts in a strip, as disclosed for
example in PCT Application WO 03/016727 A2 filed Jul. 31, 2002 and
assigned to the assignee of this application. However, such methods
of feeding nuts require additional space, particularly for fastener
installation heads where additional space is not available and such
methods are not always reliable because the use of two feed pawls
or ratchets must be balanced to avoid cocking of the nuts during
feeding. Further, such methods require complex feed mechanisms and
substantial modification of the fastener and the feed mechanism. It
would thus be desirable to feed nuts through a feed passage without
contacting the nut bore, but with minimal modification of the feed
pawl and the nut. The method of feeding nuts, nut feed pawl and nut
configuration of this invention solves the problem of nut bore
distortion or damage during feeding with minimal modification of
the feed pawl and nut.
SUMMARY OF THE INVENTION
[0005] As set forth above, nuts or female fasteners are typically
fed through a nut feed passage for various applications including,
for example, installation of a self-attaching fastener in a panel
as disclosed herein and in U.S. Pat. No. 6,631,827 assigned to the
assignee of this application and U.S. Pat. Nos. 3,942,235 and
3,108,368, both assigned to the assignee of the predecessor in
interest of the assignee of this application. This application and
the above-referenced U.S. patents disclose a method of feeding
pierce and clinch nuts in bulk or strip form through a nut feed
passage of a pierce or clinch nut installation head. Although the
method of feeding nuts through a nut feed passage, nut feed pawl
and nut of this invention is particularly suitable for feeding
self-attaching fasteners, including weld, clinch and pierce nuts,
this invention is not limited to self-attaching fasteners and may
be utilized to feed nuts through a nut feed passage for other
applications, including secondary operations, such as tapping the
nut bore and interconnecting the nuts in a continuous strip as
disclosed, for example, in U.S. Pat. No. 3,711,931, assigned to the
predecessor in interest of the assignee of this application. As set
forth above, nuts are presently fed through a nut feed passage by a
reciprocating nut feed pawl which is pivotally supported in the nut
feed passage having a distal end portion including a finger which
is received in the nut bore and the feed pawl is reciprocated
through the nut feed passage to drive the nuts through the nut feed
passage. The nut feed pawl may be spring biased as disclosed in the
above-referenced U.S. Pat. Nos. 6,631,827 and 3,108,368, the feed
pawl may be interconnected to a linkage as disclosed in the
above-referenced U.S. Pat. No. 3,942,235, or the feed pawl may be
biased by other means including pneumatic or hydraulic pressure.
However, the nuts may encounter resistance to feeding the nuts
through the nut feed passage, resulting in sufficient force applied
to the nut bore or thread cylinder by the finger of the nut feed
pawl to cause distortion or damage to the nut bore or thread
cylinder, such that a male fastener will not thread into the nut
bore. Further, the distortion or damage to the nut bore may not be
discovered until after the nut is delivered to the customer. This
is a particular problem where the nut is a self-attaching nut, such
as a weld, clinch or pierce nut, where the nut is permanently
installed to a panel and the defect in the nut bore or thread
cylinder may not be discovered until after installation. The method
of feeding nuts, feed pawl and nut configuration of this invention
eliminates this problem by avoiding contact between the nut feed
pawl and the nut bore, but requires no modification of the nut feed
pawl, except for the distal end of the feed pawl and the end face
of the nut as now described.
[0006] The nut of this invention includes a body portion having an
end face and a bore through the body portion through the end face
which may be threaded or unthreaded as described above. That is,
the general configuration of the nut may be conventional including
conventional polygonal nuts and particularly including
self-attaching nuts, such as pierce, clinch and weld nuts as
described above. Where the nut is a weld nut, the end face referred
to herein is preferably the back face opposite the weld face, which
typically includes weld projections or tips. Where the nut is a
pierce or clinch nut, the end face is preferably the back face of
the nut opposite the pilot portion as described further below.
[0007] The end face of the nut of this invention further includes a
nut feed groove extending perpendicular to the nut bore, preferably
on opposed sides of the bore adapted to receive a nut feed pawl for
feeding the nuts through a feed passage without engaging the bore.
In a preferred embodiment, the nut feed groove extends through the
axis of the nut bore, thereby defining feed grooves on opposed
sides of the nut bore, each having an open inner end opening into
the nut bore. In one preferred embodiment, the nut feed grooves are
channel-shaped, each having a bottom wall and opposed side walls
which receive the distal end of the nut feed pawl as described
below. In a preferred embodiment, the side walls of the
channel-shaped nut feed grooves extend generally perpendicular to
the end face of the nut. In one preferred embodiment of the nut of
this invention, the nut bore further includes a counterbore through
the end face coaxially aligned with the nut bore having a diameter
greater than the nut bore which receives a central distal free end
of the nut feed pawl as described below, although the nut feed
groove may be utilized to feed the nuts through a nut feed passage
without the counterbore. In one preferred embodiment, the
counterbore is cylindrical to receive a generally cylindrical
central end portion of the nut feed pawl as now described.
[0008] As will be understood from the above description, the nut
feed pawl of this invention may be generally conventional except
for the shape of the free distal end. As described above, the nut
feed pawl may be pivotally supported in the nut feed passage and
biased to feed nuts through the nut feed passage by a spring,
pneumatic or hydraulic pressure or interconnected to the feed
mechanism by a linkage. In a preferred embodiment, wherein the end
face of the nut includes channel-shaped nut feed grooves on opposed
sides of the bore, as described above, the end portion of the feed
pawl includes generally rectangular end portion or portions,
preferably having a width less than the width of the channel-shaped
grooves measured between the opposed side walls. Where the bore of
the nut includes a counterbore as described above, the free distal
end of the feed pawl further includes a central semicircular
portion having an outer diameter generally equal to the inner
diameter of the counterbore which is received in the counterbore.
In a preferred embodiment, the central portion of the free end of
the feed pawl is cylindrical having an arcuate end chamfer to
assure proper seating of the free end of the feed pawl in the
counterbore in the end face of the nut during each reciprocal
movement of the feed pawl.
[0009] Thus, a preferred embodiment of the nut feed pawl includes a
central cylindrical end portion configured to be received in the
counterbore and radial portions extending radially from a
circumference of the central cylindrical portion, wherein the
radial portions preferably have a width less than a width of the
channel-shaped nut feed grooves which engage the opposed side wall
of the nut feed grooves. In a preferred embodiment of the nut feed
pawl, the generally cylindrical surface defines an arc of less than
180 degrees, preferably less than 150 degrees, to facilitate
receipt of the cylindrical end of the nut feed pawl in the
cylindrical counterbore and the nut feed grooves and prevent
binding during repeated reciprocal movement of the nut feed pawl
through the nut feed passage. As will be understood, the design of
the nut and the nut feed pawl of this invention provides a balanced
force against the nut during feeding of the nut through the nut
feed passage, preventing cocking and assuring accurate feeding of
the nuts through the nut feed passage without contacting the nut
bore, thereby preventing distortion or damage to the nut bore while
assuring feeding of the nuts through the nut passage. Further, if a
nut becomes jammed in the nut passage, no damage is done to the nut
bore.
[0010] As set forth above, this invention may also be utilized for
feeding nuts for secondary operations, such as tapping the bore or
interconnecting the nuts in a continuous strip as disclosed in the
above-referenced U.S. Pat. No. 3,711,931. In one preferred
embodiment, the nut feed grooves are coaxially aligned with the nut
bore and extend from the nut bore a distance less than the width of
the end face of the nut. The method of this invention may then
include forming linear wire grooves in the end face of the nuts on
opposed sides of the radial nut feed grooves, preferably extending
perpendicular to the nut feed grooves and locating frangible wires
in the linear wire grooves interconnecting the nuts in a continuous
strip. As will be understood, the method of feeding nuts through a
nut passage of this invention will then include receiving the free
distal end of the nut feed pawl in the nut feed grooves of one of
the nuts and feeding a plurality of interconnected nuts through the
nut passage.
[0011] The method of feeding nuts through a nut feed passage thus
includes forming a nut feed groove in the end face of the nut
extending generally perpendicular to an axis of the nut bore,
preferably on opposed sides of the bore, forming a nut feed pawl
located in the nut feed passage having an end portion configured to
be received in the nut feed groove and reciprocating the nut feed
pawl to feed a nut through the nut feed passage. Where the nut bore
further includes a counterbore, as described above, the method of
this invention includes forming and receiving a semicircular
central portion at the free end of the reciprocable nut feed pawl
in the counterbore and reciprocating the nut feed pawl through the
nut feed passage as described above. As will now be understood, the
nut feed system of this invention including the method, feed pawl
and nut of this invention assures accurate feeding of nuts through
the nut feed passage, avoiding jamming of the nuts in the feed
passage and contact between the feed pawl and the nut bore, thereby
avoiding distortion or damage of the nut bore by avoiding contact
of the nut bore with the feed pawl. The nut feed grooves and
counterbore in the end face of the nut may be formed during
manufacture of the nut without any substantial increase in cost and
the-nut feed pawl may replace a conventional feed pawl without
substantial modification of the feed mechanism or installation
head. The method of feeding nuts through a nut feed passage of this
invention further balances the force of the reciprocating nut feed
pawl against the nut, particularly where the nut feed grooves are
located on opposed sides of the nut bore in the end face of the nut
and thus avoids cocking of the nuts in the nut passage.
[0012] Other advantages and meritorious features of this invention
will be more fully understood from the following description of the
preferred embodiments, the appended claims and the drawings, a
brief description of which follows. As will be understood, however,
the embodiment of the nut feed system and method of this invention
described below and shown in the drawings is exemplary only and
does not limit the invention except as set forth in the appended
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a side partially cross-sectioned view of a
conventional pierce or clinch nut head having the improved nut feed
pawl and nut configuration of this invention;
[0014] FIG. 2 is a top perspective view of one embodiment of the
nut feed pawl and nut configuration of this invention;
[0015] FIG. 3 is a top view of the nut configuration shown in FIG.
1 prior to receipt of frangible wires in the linear wire grooves
with a cross-sectional view of the end portion of the nut feed
pawl;
[0016] FIG. 4 is a partial cross-sectional view of FIG. 3 in the
direction of view arrows 4-4;
[0017] FIG. 5 is a partial end cross-sectional view of FIG. 3 in
the direction of view arrows 5-5;
[0018] FIG. 6 is an end perspective view of a nut of this invention
which includes frangible wires for interconnecting the nuts in a
strip as shown in FIG. 2;
[0019] FIG. 7 is an end view of the nut shown in FIG. 7;
[0020] FIG. 8 is a side cross-sectional view of the nut shown in
FIG. 7 in the direction of view arrows 8-8;
[0021] FIG. 9 is a side perspective view of the nut feed pawl shown
in FIG. 2;
[0022] FIG. 10 is a partial side view of the nut feed pawl shown in
FIGS. 2 and 9; and
[0023] FIG. 11 is a partial end view of the nut feed pawl shown in
FIGS. 2, 9 and 10.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] FIG. 1 illustrates a generally conventional pierce or clinch
nut installation head 20. As will be understood by those skilled in
this art and described further in the above-referenced U.S.
patents, a pierce or clinch nut installation head is typically
installed in the upper die shoe or platen of a die press (not
shown), such that a pierce or clinch nut is installed in a panel
with each stroke of the die press. The disclosed embodiment of the
pierce or clinch nut installation head 20 includes a base member
22, which is conventionally attached to the upper die shoe or
platen of a die press (not shown) having a mounting block 24 and a
plunger 26 fixed relative to the base member 22. The installation
head 20 further includes a nose member assembly 28 having a nut
feed passage 30 receiving pierce or clinch nuts 32 and a plunger
passage 34 which receives the free end 36 of the plunger 26. The
installation head 20 further includes a large coil spring 38 which
normally biases the nose member 28 away from the base member 22
when the die press (not shown) is opened. The base member 22
further includes an inclined cam surface 40 which receives a roller
(not shown) rotatably supported on the nose member assembly 28
which forms part of the feed mechanism described below. The feed
mechanism includes a nut feed pawl 42 having an aperture 46 (see
FIG. 2) which receives a pivot pin 44 pivotally supporting the nut
feed pawl 42 on the feed mechanism in the nut feed passage 30. The
nut feed pawl 42 includes a free distal end 46 which engages and
feeds the pierce or clinch nuts 32 through the nut feed passage 30
with each stroke of the die press (not shown) as described below.
The disclosed embodiment of the nut feed pawl 42 further includes a
proximal finger 50 which is biased upwardly by a small return coil
spring 52 rotating the nut feed pawl 42 in a counterclockwise
direction. The feed mechanism 54 further includes a coil spring 56
surrounding an adjustment rod 58 having an adjustment knob 60.
[0025] Thus, upon closing of the die press (not shown), the nose
member 28 engages a panel (not shown) located in the die press,
driving the nose member 28 upwardly in FIG. 1 to drive the free end
36 of the plunger 26 through the plunger passage 34, thereby
installing a pierce or clinch nut 32 in a panel opposite the
plunger passage 34 (not shown). As the nose member 28 is driven
upwardly, the roller (not shown) engages the inclined cam surface
40, driving the feed mechanism 54 to the right in FIG. 1. Upon
opening of the die press (not shown), the coil spring 38 drives the
nose member 28 away from the base member 22 and the coil spring 56
of the feed mechanism 54 then drives the nut feed pawl 42 to the
left in FIG. 1, driving a pierce or clinch nut 32 in the feed
passage 30 into the plunger passage 34 and the installation head 20
is then ready for repeating the cycle, such that a pierce or clinch
nut 32 is installed in a panel (not shown) opposite the plunger
passage 34 with each stroke of the die press.
[0026] As described above, the free distal end 48 of a conventional
pierce or clinch nut installation head normally includes a finger
(not shown) which is received in the nut bore 64 as disclosed in
the above-referenced patents. Thus, the finger at the free end 48
of the nut feed pawl 42 is driven against the nut bore 64 by the
coil spring 56 with each stroke of the die press. However, the nuts
32 may become cocked or jammed in the nut feed passage 30 and the
force of the finger in the nut bore may be sufficient to damage the
thread cylinder making it difficult or impossible to thread a male
fastener (not shown) into the bore 64. As used herein, the term
"thread cylinder" refers to the cylindrical configuration of the
nut bore 64, whether or not the bore is threaded or unthreaded.
Thus, a primary object of this invention is to feed the nuts 32
through the nut feed passage 30 without contacting the thread
cylinder 64.
[0027] The disclosed embodiment of the nut 32 is a generally
conventional pierce or clinch nut including a pilot portion 66
having a planar face 68, flange portions 70 on opposed sides of the
pilot portion 66, each having a panel support face 72 and
re-entrant grooves 74 in the panel support faces 72. The re-entrant
grooves 74 each include a bottom wall 76, an inner side wall 78
inclined from the bottom wall 76 outwardly and an outer side wall
80 inclined inwardly toward the pilot portion 66 as best shown in
FIGS. 6 and 8. As will be understood by those skilled in this art,
the plunger 26 shown in FIG. 1 drives the planar end face 68 of the
pilot portion 66 against a panel (not shown) opposite the plunger
passage 34 to pierce an opening in the panel and a die button (not
shown) then clinches the panel adjacent the pierced panel opening
into the re-entrant grooves 74 permanently attaching the nut 32 to
a panel. Alternatively, the panel may be pre-pierced and clinched
to the panel by the die button. Thus, the nut 32 may be utilized as
either a pierce or clinch nut. However, the configuration of the
nut 32 as thus far described is conventional.
[0028] The nut 32 further includes a back or end face 82 which is
typically planar and the nut bore 64 extends through the end face
82 and the piercing face 68 of the pilot portion 66 as best shown
in FIG. 8. As disclosed in the above-referenced U.S. Pat. No.
3,711,931, the nuts 32 may be interconnected in a continuous strip
by frangible wires 84. Linear wire grooves 86 may be rolled into
the end face 82 of the nut during the roll forming process and the
wires 84 are then received in the wire grooves 86 and the end face
84 is then either clinched or knurled to permanently retain the
frangible wires 84 in the grooves 86. The frangible wires 84 may be
formed of any suitable material including annealed carbon steel
wire, which is preferably not heat treated, monofilament nylon
strand, cord, cable or the like. As disclosed in U.S. Pat. No.
3,711,931, the continuous strip of pierce or clinch nuts may be fed
from a coil to the installation head 20. Alternatively, as
disclosed in the above-referenced U.S. Pat. No. 3,108,368 and U.S.
Pat. No. 3,140,010 assigned to the predecessor in interest of the
assignee of this application, the nuts may be fed in bulk form to
the installation head 20 through plastic chuting. The back or end
face of the disclosed embodiment of the pierce nut 32 further
includes inclined faces 88 on opposed sides of the end face 82 and
faces 90 perpendicular to the end face 82. The linear wire grooves
86 are preferably located in the planar end face 82 adjacent to but
spaced from the inclined faces 88. As disclosed in the
above-referenced U.S. Pat. No. 3,711,931, the pierce or clinch nut
32 may also be T-shaped, wherein the linear wire grooves 86 are
formed in the planar end face. However, as set forth above, the
configuration of the nut 32 may also be a weld nut or any
conventional nut.
[0029] The nuts 32 of the nut feed system of this invention
includes a nut feed groove 92 in the end face 82 which receives the
free distal end 48 of the reciprocating nut feed pawl 42 without
contacting the nut bore 64. In a preferred embodiment, the nut feed
groove 92 extends through an axis of the nut bore 64 to define nut
feed grooves 92 on opposed sides of the nut bore 64, each having an
open end opening into the nut bore 64 as best shown in FIGS. 6 and
7. In a preferred embodiment, the nut feed groove or grooves 92 are
channel-shaped, each having a bottom wall 94 and opposed side walls
96 which, in a preferred embodiment, extend generally perpendicular
to the end face 82. In a preferred embodiment, the bottom wall 94
of the channel-shaped groove 92 is planar and parallel to the end
face 82, such that the opposed side walls 96 are also perpendicular
to the bottom wall 94. The channel-shaped groove 92 also includes
end walls 98 which are preferably located within the end face 82 or
spaced from the inclined surface 88 at the end face. In the
disclosed embodiment, wherein the end face 82 of the pierce or
clinch nuts 32 include linear wire grooves 86 for interconnecting
the nuts in a continuous strip as described above, the end walls 98
are also preferably spaced from the linear wire grooves 86 and thus
the linear wire grooves 86 are spaced on opposed sides of the nut
feed groove 92 and extend perpendicular to the nut feed groove 92
and the side walls 96. As described below, the free distal end 48
of the nut feed pawl 42 is specifically configured to be received
within the nut feed groove or grooves 92.
[0030] In a preferred embodiment of the nut feed system of this
invention, the end face 82 of the nut 32 also includes a
counterbore 100 coaxially aligned with the bore 64 having a
diameter greater than the nut bore 64 to receive a central
generally semicircular portion at the free distal end 48 of the nut
feed pawl 42 as described below. In a preferred embodiment, the
counterbore 100 is cylindrical having a smooth cylindrical surface.
Where the nut bore 64 is internally threaded as shown in the
drawings, the diameter of the cylindrical counterbore 100 is
greater than the root or major diameter of the internal threads 102
as best shown in FIG. 5. As will be understood by those skilled in
this art, the nut feed groove or grooves 92 and the counterbore 100
may be formed during piercing of the bore 64 without any
substantial increase in cost. As now described, the distal free end
48 of the nut feed pawl 42 is configured to be received in the nut
feed groove 92 without contacting the nut bore 64, thereby avoiding
damage to the nut bore 64 during feeding of the nuts 32 through the
nut feed passage 30.
[0031] FIGS. 9 to 11 illustrate one preferred embodiment of the nut
feed pawl 42. As described above, the nut feed pawl 42 is generally
conventional except for the configuration of the distal free end
48. As described above, the disclosed embodiment of the nut feed
pawl 42 includes an aperture 46 adapted to receive a pivot pin 44
(see FIG. 1) to pivotally support the nut feed pawl 42 in a nut
feed passage 30 having a proximal finger 50 which is biased by a
return spring 52, urging the nut feed pawl to rotate in a
counterclockwise direction to receive the distal free end 48 in the
nut feed groove 92 and the counterbore 100 upon opening of the die
press (not shown). Thus, a conventional nut feed pawl may be easily
replaced by the nut feed pawl 42 of this invention by removing the
pivot pin 44 and replacing the conventional nut feed pawl with the
nut feed pawl 42 of this invention with minor modifications to
account for the preferred angle of inclination of the feed pawl 42
of this embodiment. Further, the nut feed pawl 42 of this invention
does not have a significantly greater cost.
[0032] As best shown in FIG. 11, the distal free end of the end
portion 48 of the nut feed pawl 42 includes a generally
semicircular central end portion 104 and radial portions 106. The
driving face of the distal free end 48 of the feed pawl 42 includes
a cylindrical surface 108 which blends into the generally
semicircular end portion 104 in an arcuate chamfer 110, as shown in
FIGS. 10 and 11, and the radial portions 106 include planar driving
surfaces 112 as best shown in FIGS. 9 and 11. As best shown in FIG.
11, the cylindrical surface 110 defines an arc of less than 180
degrees, preferably less than 150 degrees, or about 120 degrees,
and the radial portions 106 extend from the cylindrical surface
108. The back face 114 is preferably inclined from the end face 116
at an angle of between 20 and 60 degrees and may include an arcuate
surface 118 as shown in FIG. 10 which blends the inclined back face
114 into the end face 116. The reciprocable nut feed pawl 42 is
preferably formed of tool steel to reduce wear and the upper
portion 120 may have a smaller width to reduce cost. As set forth
above, the distal free end 48 of the nut feed pawl 42 is configured
to be received in the nut feed grooves 92 and the counterbore 100
in the end face 82 of the nut 32 without contacting the nut bore 64
as now described.
[0033] As best shown in FIGS. 3 to 5, the central cylindrical
portion 108 of the distal free end 48 of the nut feed pawl 42 is
received in the cylindrical counterbore 100 and the radial portions
106 are received in the nut feed grooves 92, such that the planer
end faces 112 engage the leading side wall 96 as the distal end 48
of the feed pawl is biased in a counterclockwise direction by the
return spring 32 (FIG. 1) upon opening of the die press. The
diameter of the cylindrical surface 108 is generally equal to the
internal diameter of the cylindrical counterbore 100 or slightly
less to prevent binding. The radial portions 106 are generally
rectangular as shown in FIG. 3 having a width substantially less
than the width of the nut feed grooves 92 measured between the side
walls 96 as best shown in FIGS. 3 and 4. The arcuate chamfered
surface 110 prevents binding of the cylindrical surface 108 in the
cylindrical counterbore 100 as the distal free end 48 of the nut
feed pawl is received and retracted from the nut feed groove 92 and
the counterbore 100 during each stroke of the die press (not
shown). The feeding force is thus balanced between the planar drive
faces 112 of the radial portions 106 of the nut feed pawl 42 and
the cylindrical portion 108 while avoiding any contact with the nut
bore 64. As will now be understood, the counterbore 96 in the end
face 82 is thus preferably cylindrical to receive the cylindrical
surface 108 adjacent the free end 116 of the nut feed pawl and the
side walls 96 preferably extend perpendicular to the end face 82 in
this embodiment to provide balanced feeding of the nuts 32 through
the nut feed passage 30.
[0034] The method of feeding nuts through a nut feed passage will
now be understood from the above description of one preferred
embodiment of the distal free end 48 of the nut feed pawl 42 and
the preferred configuration of the nut feed groove 92 and
counterbore 100. The method of feeding nuts through a feed passage
of this invention includes forming a nut feed groove 92 in the end
face 82 of the nut, locating a free distal end portion 48 of a
reciprocable nut feed pawl 42 in the nut feed groove 92 and
reciprocating the nut feed pawl 42 to feed a nut through the nut
feed passage 30 as shown in FIGS. 1 and 2. A preferred embodiment
of the method of this invention includes forming the nut feed
groove 92 through the axis of the nut bore 64, forming separate nut
feed grooves on opposed sides of the nut bore 64, wherein each nut
feed groove has an open inner end opening into the nut bore 64. In
a most preferred embodiment, the method of this invention includes
forming channel-shaped grooves 92 in the end face 82 of the nut 32,
each having a bottom wall 94 and opposed side walls 96 which
preferably extend perpendicular to the end face 82 of the nut 32
and the nut feed pawl 42 includes radial portions 106, each having
a planar drive face 112 engaging the planar side walls 96 of the
channel-shaped grooves 92. Where the end face 82 of the nut
includes a counterbore 100, the method of this invention preferably
includes forming a cylindrical counterbore in the end face 82 of
the nut coaxially aligned with the bore 64 having a diameter
greater than the bore 64 and the method of this invention
preferably includes forming a cylindrical surface 108 on the distal
free end 48 of the nut feed pawl 42 and receiving the central
cylindrical surface 108 into the cylindrical bore 100 in the end
face 82 of the nut 32. The method of this invention then includes
reciprocating the nut feed pawl 42 through the nut feed passage 30
to feed a nut 32 through the nut feed passage 30.
[0035] As will now be understood from the description of a
preferred embodiment of the nut feed system of this invention, the
nut feed system of this invention, including the nut feed pawl 42
and the nuts 32, may be utilized to feed any configuration of nuts
through a feed passage for any purpose, including but not limited
to secondary operations, such as tapping and threading of the nut
bore or interconnecting the nuts in a continuous strip, and feeding
the nuts through a nut feed passage into an installation head, such
as the pierce or clinch nut head 20, disclosed in FIG. 1 and
described above and weld nuts into a nut welding apparatus. Thus,
the nut feed system and method of this invention is not limited to
self-attaching nuts, such as pierce, clinch or weld nuts, but may
be utilized in any application requiring feeding of the nuts
through a nut feed passage where a reciprocable nut feed pawl
drives the nuts through the nut feed passage. Although it has been
found that the combination of a nut feed pawl having a semicircular
or cylindrical end portion received in a counterbore and radial
portions received in nut feed grooves extending through the axis of
the bore provides advantages over a nut feed groove alone,
including a balanced force, as described above, a nut feed groove
extending generally perpendicular to the axis of the bore, but not
extending through the axis of the bore may also be utilized,
wherein the distal free end of the nut feed pawl includes a drive
face received in the nut feed groove may also be utilized, provided
the free end of the nut feed pawl does not engage and drive against
the nut bore. The nut feed system and method of this invention thus
provides an important advantage over the prior art, eliminating
damage or distortion of the nut bore cylinder and fulfills a long
felt need in this art.
* * * * *