U.S. patent application number 11/717858 was filed with the patent office on 2007-07-05 for multi-grip blind rivet.
This patent application is currently assigned to NEWFREY LLC. Invention is credited to Frank Piacenti, Jerry W. Robertson.
Application Number | 20070154289 11/717858 |
Document ID | / |
Family ID | 29406296 |
Filed Date | 2007-07-05 |
United States Patent
Application |
20070154289 |
Kind Code |
A1 |
Piacenti; Frank ; et
al. |
July 5, 2007 |
Multi-grip blind rivet
Abstract
A multi-grip blind rivet 74 includes a rivet body 82, adapted to
receive a portion of a mandrel 76. A plurality of indentations 88
are formed in an outer surface 86 of the rivet body 82 in each of
three axially spaced transaxial planes. Each indentation 88 is
formed with a work hardened base surface 90 having a convex
portion, which is formed with axially spaced first and second
transaxial edges 106 and 108 having nonlinear portions. Adjacent
indentations 88 are separated by ribs 89. A flared intermediate
surface 122 extends between the base surface 90 and the outer
surface 86. The rivet 74 is assembled within aligned holes 128 and
130 of workpieces 124 and 126, respectively, where, upon setting of
the rivet, the indentations 88 collapse and the outer surface 86
bulges against walls of the holes to retain the workpieces
together.
Inventors: |
Piacenti; Frank;
(Campbellsville, KY) ; Robertson; Jerry W.;
(Columbia, KY) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Assignee: |
NEWFREY LLC
1423 KIRKWOOD HIGHWAY DRUMMOND PLAZA OFFICE PARK
NEWARK
DE
19711
|
Family ID: |
29406296 |
Appl. No.: |
11/717858 |
Filed: |
March 14, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10266418 |
Oct 8, 2002 |
7198444 |
|
|
11717858 |
Mar 14, 2007 |
|
|
|
10153761 |
May 22, 2002 |
|
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|
10266418 |
Oct 8, 2002 |
|
|
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Current U.S.
Class: |
411/501 ;
411/60.1 |
Current CPC
Class: |
F16B 19/1054
20130101 |
Class at
Publication: |
411/501 ;
411/060.1 |
International
Class: |
F16B 13/06 20060101
F16B013/06; F16B 19/08 20060101 F16B019/08 |
Claims
1.-29. (canceled)
30. A multi-grip blind rivet comprising: a mandrel having a stem
and a pulling head at one end of the stem; a hollow cylindrical
body having an outer surface and formed about an axis thereof and
adapted to receive the stem of the mandrel therethrough; and a
plurality of indentations formed in the outer surface of the
cylindrical body, at least one of the plurality of indentations
formed with a base surface having a first arcuate transaxial edge
extending along a length thereof and concavely facing a second
substantially linear transaxial edge spaced axially from the first
arcuate transaxial edge.
31. The multi-grip blind rivet of claim 30 wherein the at least one
indentation is positioned at an end of the hollow cylindrical body
adjacent the pulling head and wherein the second linear transaxial
edge is positioned closer to the end than the first arcuate
transaxial edge.
Description
[0001] This application is a continuation-in-part of applicant's
co-pending application U.S. application Ser. No. 10/153,761, filed
May 22, 2002, and titled MULTI-GRIP BLIND RIVET, which is pending.
The disclosure of applicant's above-noted co-pending application is
incorporated herein by reference thereto.
BACKGROUND OF THE INVENTION
[0002] This invention relates to a multi-grip blind rivet, and
particularly relates to a multi-grip blind rivet having one or more
radial indentations formed in one or more transaxial planes of a
rivet body of the rivet.
[0003] Typically, multi-grip blind rivets include a mandrel, or
stem, formed with a head at one axial end thereof, and a rivet
body, formed as a sleeve or shank having a passage therethrough and
a flange at one axial end thereof. A mandrel-body assembly is
formed by inserting a non-head end of the mandrel into the passage
at a non-flange end of the rivet body and through the passage. With
this assembly, the head of the mandrel is eventually resting
against the non-flange end of the rivet body and the non-head end
of the mandrel is extending outward from the flange end of the
body. The assembly is then processed through a forming operation
where a groove is, or plural indentations are, formed in the outer
periphery of the rivet body in a given transaxial plane. A
plurality of grooves could be formed in the outer periphery of the
rivet body, in spaced transaxial planes, along the axial length of
the body in lieu of the indentations.
[0004] In known multi-grip rivets of the type described above, the
grooves are continuous, and concave with respect to outer surface
of the shank, with a concave work hardened surface formed at the
base of the groove. With respect to the known multi-grip rivets
which are formed with indentations, each such indentation, and the
base thereof, could be concave with a concave work hardened base.
Or, the indentations could be formed with flared upper and lower
walls extending from a flat work hardened surface, which is in the
form of a secant to the circumference of the shank of the rivet
body.
[0005] Subsequent to the formation of the grooves in the rivet
body, the mandrel-body assembly is placed within aligned openings
of two or more workpieces to be secured together by the rivet. The
diameter of the aligned openings is greater than the diameter of
the external surface of the shank of the rivet body. In this
position, an outer surface of one of the workpieces is in
interfacing engagement with an underside surface of the flange of
the rivet body. Thereafter, while supporting the flange of the
rivet by the nosepiece of the setting tool, the setting of the
rivet begins by applying a pulling load, in an axial direction away
from the flange, on the portion of the mandrel which extends
outward from the shank of the rivet body. The pulling load on the
mandrel is transferred to the rivet body shank under a compressive
load.
[0006] Continued application of the pulling load results initially
in the outward radial bulging of the rivet body located axially
between the spaced planar grooves followed by near axial closing of
each of the grooves and a corresponding axial shortening of the
rivet body. As the outwardly bulging section of the rivet body
contacts the outer surface of the workpiece, and with the
shortening of the axial length of the rivet body, the workpiece
parts are clamped together.
[0007] Eventually, the multi-grip blind rivet has been set whereby
the bulging sections of the rivet body are in firm, distorting
engagement with the inner walls of the aligned holes of the
workpieces, which creates a gripping action between the bulging
sections and the inner walls to retain the workpieces together.
[0008] The setting performance of the above-described multi-grip
blind rivet, commonly configured either with grooves or swaged
indentations along the rivet body, does not perform well where the
materials of the workpieces are soft and/or friable, especially
where the holes are oversize and there are extremes of grip
thickness.
[0009] A common form of multi-grip blind rivet, as illustrated and
described in U.S. Pat. Nos. 4,958,971 and 6,004,086, has
circumferential grooves, usually hemispherical in shape, spaced at
intervals along the axial length of the shank of the rivet body.
The grooves are concave with respect to the outer surface of the
shank of the rivet body. As this type of blind rivet is being set,
the plain cylindrical rivet body portions between the grooves
expand radially to form a characteristic "cottage loaf" setting and
the grooves collapse in an axial direction giving the capability
for wider workpiece thicknesses.
[0010] As further illustrated and described in U.S. Pat. No.
6,254,324, one or more reinforcing ribs may be formed within the
circumferential concave groove, or between
circumferential-groove-like indentations, and extend radially from
the base of the groove to the outer periphery of the shank of the
rivet body.
[0011] The control of the depth of the grooves is critical to
accommodate the extreme conditions mentioned. For example, if the
groove is too deep, cracking of the base of the groove will occur
upon setting of the rivet. If the groove is too shallow, there will
not be sufficient resistance to prevent the mandrel head from
pulling into, or even through, the rivet body.
[0012] With respect to the above-noted U.S. patents, a work
hardened area may be formed at the base, or bottom, of the groove
and will contribute to the development of a resistance to the
pulling of the mandrel head into the rivet body. Also, the load
being exerted by the mandrel head is transposed to the rivet body
and to the groove profile. This load increases under the action of
the setting tool causing the rivet body to expand radially between
the grooves as the body shortens. The setting process reaches a
point where groove closes or collapse, thereby indicating the
completion of the setting of the rivet.
[0013] Small differences in the groove depth of the grooves, as
illustrated and described in the above-noted U.S. patents, can give
significant differences in the collapse load. This condition,
together with normal manufacturing variations in mandrel crimp
breakload, could lead to either premature rivet body failure or the
pulling of the mandrel head into the rivet body.
[0014] In another type of multi-grip rivet, as illustrated and
described in U.S. Pat. No. 5,496,140, indentations are formed at
predetermined distances along the shank of the rivet body, with
flared upper and lower walls extending outward from a flat work
hardened base, which is in the form of a secant to the
circumference of the shank. During the setting operation of this
type of rivet, the indented portions retain their integrity and
allow the intermediate portions between the indentations to
collapse.
[0015] With respect to the rivet illustrated and described in U.S.
Pat. No. 5,496,140, after the mandrel-body assembly has been formed
as described above, the rivet body is indented with a series of
flat-bottom indentations, such as four equispaced identical
indentations in a common transaxial plane around the rivet body.
The formation of the indentations provide four thickened portions
with work hardened zones therebetween. This structure avoids fully
circumferential work hardening and the subsequent risk of rivet
body cracking during the application of the mandrel setting
load.
[0016] As the rivet-setting load is being applied in the setting of
the rivet of U.S. Pat. No. 5,495,140, the rivet section, which
includes the four thickened portions and the indentations, is
supporting the setting load. Again, there is a point in the setting
profile where the setting load overcomes the resistance of the work
hardened zones and the indentations collapse to complete the
setting of the rivet. With this type of rivet, body rupturing is
avoided, but only small variations in indentation depth and mandrel
crimp break load could result in an incomplete setting or the
mandrel head being pulled through the rivet body.
[0017] When setting rivets of the types described above, there are
two basic concerns which must be addressed: [0018] a. During
setting in softer workpiece materials, the grooves or indentations
are required to be deeper than normal to prevent the mandrel head
from pulling through the rivet body. However, this structure can
cause fracture of the rivet body, due partly to the thinness of the
material of the body and partly to the degree of material work
hardening. If the grooves or indentations are not at an optimum
depth, the mandrel can be pulled into the rivet body; and [0019] b.
If the grooves or indentations are less than optimum during the
setting operation, the mandrel head can be pulled through the rivet
body due to insufficient resistance being provided by the rivet
body, and little or no resistance being provided by the soft
workpiece materials. In extreme cases, the result is that the
portion of the mandrel shaft extending from the mandrel head can
protrude beyond the flange, thereby creating a potentially
hazardous condition. Such a condition could cause excessive radial
expansion of the rivet body resulting in splitting of the workpiece
material as the radial expansion takes place within the hole of the
workpiece.
SUMMARY OF THE INVENTION
[0020] Therefore, it is an object of this invention to provide a
multi-grip blind rivet which will provide excellent performance
when used with a variety of workpiece materials, and including
workpieces having wide variations of plate thickness and oversize
holes and/or slots.
[0021] Another object of this invention is to provide a multi-grip
blind rivet that provides a relatively wider band of resistance to
the setting load.
[0022] A further object of this invention is to provide a
multi-grip blind rivet which is relatively inexpensive to
manufacture.
[0023] With these and other objects in mind, this invention
contemplates a multi-grip blind rivet which includes a mandrel and
a hollow cylindrical body having an outer surface and formed about
an axis thereof and adapted to receive at least a portion of the
mandrel therethrough. A plurality of indentations are formed in the
outer surface of the cylindrical body, with at least one
indentation of the plurality of indentations formed with a base
surface having a convex portion.
[0024] In addition, this invention contemplates a multi-grip blind
rivet which includes a mandrel and a hollow cylindrical body having
an outer surface and formed about an axis thereof and adapted to
receive at least a portion of the mandrel therethrough. A plurality
of indentations are formed in the outer surface of the cylindrical
body, with each indentation formed with a base surface having a
first transaxial edge, and a second transaxial edge spaced axially
from the first transaxial edge. The first transaxial edge is
nonlinear such that axial distances between a plurality of pairs of
axially spaced points of the first and second transaxial edges
varies between the opposite ends of the first transaxial edge.
[0025] Further, this invention contemplates a multi-grip blind
rivet which includes a mandrel and a hollow cylindrical body having
an outer surface and formed about an axis thereof and adapted to
receive at least a portion of the mandrel therethrough. A plurality
of indentations are formed in the outer surface of the hollow
cylindrical body, with at least one indentation of the plurality of
indentations formed with a base surface having an endless outboard
edge around the base surface. The at least one indentation is
formed with an intermediate surface which extends between, and is
contiguous with, the outer surface of the hollow cylindrical body
and the entirety of the endless outboard edge of the base
surface.
[0026] Additionally, this invention contemplates a plurality of
ribs formed in the transaxial plane with each rib separating an
adjacent pair of the plurality of indentations.
[0027] Other objects, features and advantages of the present
invention will become more fully apparent from the following
detailed description of the preferred embodiment, the appended
claims and the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] In the accompanying drawings:
[0029] FIG. 1 is a side view showing a portion of a first prior art
multi-grip blind rivet;
[0030] FIG. 2 is a side view of the rivet of FIG. 1 with arrows
showing the directions of setting loads resulting from a pulling or
setting load applied to a mandrel of the first prior art rivet;
[0031] FIG. 3 is a sectional view taken along line 3-3 of FIG. 1
showing certain structural features of the first prior art
rivet;
[0032] FIG. 4 is a side view showing a portion of a second prior
art multi-grip blind rivet;
[0033] FIG. 5 is a side view of the rivet of FIG. 4 with arrows
showing the directions of setting loads resulting from a pull load
applied to a mandrel of the second prior art rivet;
[0034] FIG. 6 is a sectional view taken along line 6-6 of FIG. 1
showing certain structural features of the second prior art
rivet;
[0035] FIG. 7 is a partial-sectional side view showing a multi-grip
blind rivet, including a mandrel in assembly with a rivet body
having indentations formed in an outer surface thereof, in
accordance with certain principles of the invention;
[0036] FIG. 8 is a partial side view showing the indentations
formed in the rivet body of FIG. 7 in accordance with certain
principles of the invention;
[0037] FIG. 9 is a side view of the rivet of FIG. 7 with arrows
showing the directions of setting loads resulting from a pull load
applied to the mandrel in accordance with certain principles of the
invention;
[0038] FIG. 10 is a sectional view taken along line 10-10 of FIG. 8
showing structural features of portions of the indentations of the
rivet body of FIG. 7 in accordance with certain principles of the
invention;
[0039] FIG. 11 is a side view showing the multi-grip blind rivet of
FIG. 7 in assembly with two workpieces, of generally equal
thickness, which are to be retained together by the eventual
setting of the rivet in accordance with certain principles of the
invention;
[0040] FIG. 12 is a side view showing early-stage radial bulging of
the rivet body of FIG. 11 and an early phase of the collapsing or
closing of the indentations of FIG. 7 in accordance with certain
principles of the invention, with the workpieces of FIG. 11 not
shown for the purpose of clarity;
[0041] FIG. 13 is a side view showing later-stage radial bulging of
the rivet body of FIG. 11 and a later phase of the continuation of
the collapsing of the indentations of FIG. 7 formed in the body in
accordance with certain principles of the invention, with the
workpieces not shown for the purpose of clarity;
[0042] FIG. 14 is a side view showing a set rivet after final-stage
radial bulging of the rivet body of FIG. 11 and completion of the
collapsing of the indentations of FIG. 7 formed in the body in
accordance with certain principles of the invention, with the
workpieces of FIG. 11 being shown;
[0043] FIG. 15 is a side view showing a set rivet in assembly with
the two workpieces of FIG. 11, and a third workpiece of greater
thickness, to retain the three workpieces together, in accordance
with certain principles of the invention;
[0044] FIG. 16 is a side view showing a set rivet in assembly with
a first workpiece of a prescribed thickness, and a second workpiece
of a thickness greater than the prescribed thickness, to retain the
two workpieces together, in accordance with certain principles of
the invention, and
[0045] FIG. 17 is a perspective view showing a portion of the rivet
body of FIG. 7, with the indentations formed therein in accordance
with certain principles of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0046] Referring to FIGS. 1, 2 and 3, a prior art multi-grip blind
rivet 30 includes a mandrel 32 formed with a stem 34 and a pulling
head 36, and a rivet body 38 having an axial passage 40. An outer
surface 42 of the rivet body 38 is formed, in a transaxial plane,
with a plurality of indentations 44, each of which is concave, as
viewed from the exterior of the rivet body, and generally
hemispherical in shape. A plurality of ribs 46 are formed in the
outer surface 42 of the rivet body 38, formed as a result of the
indentations 44, with each rib separating adjacent indentations. An
inward-most portion 48 of each indentation 44 is work hardened as
represented by cross hatching in FIG. 1. A multi-grip blind rivet
of this type is illustrated and described in U.S. Pat. No.
6,254,324.
[0047] Referring to FIGS. 4, 5 and 6, another prior art multi-grip
blind rivet 50 includes a mandrel 52 formed with a stem 54 and a
pulling head 56, and a rivet body 58 having an axial passage 60. An
outer surface 62 of the rivet body 58 is formed, in a transaxial
plane, with a plurality of indentations 64, each of which is formed
with a flat inner surface 66, as viewed from the exterior of the
rivet body, and a pair of flared transition surfaces 68 and 70
spatially located on axially opposite sides of the surface 66.
Referring to FIG. 4, each of the flat inner surfaces 66 are work
hardened as represented by the cross hatching and, referring to
FIG. 6, form a secant to the circular configuration of the outer
surface 62 of the rivet body 58. The indentations 64 are structured
such that a large portion 72 of the rivet body remains between, and
separates, adjacent indentations. A multi-grip blind rivet of this
type is illustrated and described in U.S. Pat. No. 5,496,140.
[0048] In use of each of the rivets 30 and 50, workpieces (not
shown) are assembled, in a conventional manner, where the unset
rivet components rest on a flange (not shown), which is formed on
an end of the rivet body. Thereafter, a free end portion of the
mandrel stem, which extends from the flange end of the rivet body,
is grasped and pulled away from the rivet body. As a result of the
stem-pulling action, a rivet-setting load is applied through the
mandrel head to the adjacent end of the rivet body, as shown by an
upper row of arrows in FIGS. 2 and 5. Also, load forces are exerted
on axially opposite sides of the indentations, as shown in FIGS. 2
and 5, whereby the indentations begin to, and eventually, collapse
and close. Also, the outer surface of the rivet body bulges
outward, or expands radially, to provide for securance engagement
between the rivet and the workpieces, thereby retaining the
workpieces together.
[0049] As noted above, multi-grip blind rivets of the type
illustrated in FIGS. 1 through 6 perform well when securing
workpieces composed of relatively hard materials. However, problems
could be encountered when the workpieces are composed of materials
that are soft and/or friable, particularly when the holes of the
workpieces are oversized and there are extremes of grip thickness.
Also, with the softer and/or friable workpieces, there could be
concern for the undesirable pulling of the mandrel head through the
rivet body during the application of the setting load. Further, as
noted above, possible problems could be related to the depth of the
indentations, such as when the depth of the indentation is too
deep, or too shallow.
[0050] Referring now to FIGS. 7 and 15, in the preferred embodiment
of the invention, a multi-grip blind rivet 74 includes a mandrel 76
formed with a stem 78 and a pulling head 80 at one end of the stem.
The pulling head 80 is formed with an underside surface 102.
[0051] The rivet 74 further includes a rivet body, or a hollow
cylindrical body, having an axial passage 84 formed about an axis
85 (FIG. 8) of the rivet body. The rivet body 82 is formed with an
outer surface 86 at a prescribed radius about the axis 85. The
rivet body 82 is also formed with a flange 92, at a flange end
thereof, which has a flat surface 94 facing a sleeve-like portion
of the rivet body and has a dome-like surface 96 facing away from
the sleeve-like portion. A breakneck 98 is formed in the stem 78 of
the mandrel 76, near the flange 92, and is considerably spaced from
the mandrel head 80. A flangeless end 100 is formed at an end of
the rivet body 82, opposite the flange end thereof.
[0052] During assembly of the components of the rivet 74, the stem
78 of the mandrel 76 is inserted into the passage 84 at the
flangeless end 100 of the rivet body 82 until the underside surface
102 of the mandrel head 80 engages the flangeless end. The axial
length of the mandrel stem 78 is such that a free end portion 103
of the stem extends outward from the passage 84 at the flange end
of the rivet body 82.
[0053] Thereafter, the outer surface 86 of the rivet body 82 is
formed with a first plurality of indentations 88a, a second
plurality of indentations 88b, and a third plurality of
indentations 88c, which are located in three axially spaced first,
second and third transaxial planes, respectively, as illustrated in
FIG. 7. It is noted that, in the preferred embodiment, the
plurality of indentations 88b in the second transaxial plane, which
is the middle plane of the three planes, is closer to the plurality
of indentations 88c in the third transaxial plane than to the
plurality of indentations 88a in the first transaxial plane.
[0054] The three transaxial planes define four segments 87a, 87b,
87c and 87d of the rivet body 82 between opposite ends of the rivet
body, as shown in FIGS. 7 and 11, which are also shown as deformed
segments in FIGS. 12, 13, 14 and 16. Of the four segments, the
segments 87a and 87d are of the shortest axial length, which could
be of equal, or unequal, lengths, without departing from the spirit
and scope of the invention. The segment 87b is of the longest axial
length, and the segment 87c is of an intermediate axial length, as
compared to the shortest and the longest axial lengths.
[0055] In the preferred embodiment, the rivet 74 is formed with the
four segments 87a, 87b, 87c and 87d. The rivet could be formed with
two segments, three segments, or more than four segments, without
departing from the spirit and scope of the invention.
[0056] Hereinafter, the numeral "88" will be used to refer to the
indentations generally, and the numerals "88a," "88b" and "88c"
will be used to refer to the specific indentations in the first,
second and third transaxial planes, respectively.
[0057] In the preferred embodiment, there are four indentations 88
in each of the first, second and third transaxial planes. As few as
two indentations 88, and as many as practical, for example, at
least eight indentations 88, could be formed in any one or more of
the first, second and third transaxial planes without departing
from the spirit and scope of the invention.
[0058] In addition, a plurality of indentations could be formed in
the outer surface 86 of the rivet body 82 in a single transaxial
plane, instead of in three transaxial planes of the preferred
embodiment, with at least one indentation of the plurality of
indentations in the single plane conforming to the structure of the
indentation 88, without departing from the spirit and scope of the
invention.
[0059] The rivet body 82 is formed with a plurality of ribs 89 in
the first, second and third transaxial planes, with each rib
separating adjacent indentations 88 in a respective one of the
three planes. Each indentation 88 is formed with an inward-most
base surface 90, which is work hardened as represented by cross
hatching in FIG. 8.
[0060] Referring to FIG. 8, the base surface 90 of each indentation
88 is formed with an endless outboard edge 104 around the base
surface. The endless outboard edge 104 includes a first transaxial
edge 106 and a second transaxial edge 108, which is spaced axially
from the first transaxial edge. The endless outboard edge 104
further includes a first side edge 110 and a second side edge 112,
which are axially aligned and circumferentially spaced from each
other. The first side edge 110 and the second side edge 112 are
integrally joined with respective opposite ends of the first and
second transaxial edges 106 and 108 to thereby form the endless
outboard edge 104 of the base surface 90.
[0061] It is noted that the shape of the indentation 88, as viewed
from the exterior of the rivet 74, is generally similar to the
shape of a human "eye."
[0062] The first transaxial edge 106 of the base surface 90 is
nonlinear between opposite ends thereof, such that axial distances
between a plurality of pairs of axially spaced points of the first
and second transaxial edges 106 and 108, respectively, varies
between opposite ends of the first transaxial edge. For example,
assume that the first transaxial edge 106 is shaped as an arc, as
shown in FIG. 8, which extends in an axial direction away from the
second transaxial edge 108, and that, for purposes of this example,
the second transaxial edge 108 is linear between opposite ends
thereof. Then select a first pair of spaced points on the first and
second transaxial edges 106 and 108, respectively, with the pair of
points being axially aligned, and adjacent the second side edge
112. In this instance, the distance between the first pair of
points is slightly greater than the length of the second side edge
112, due to the slight rise of the arc of the nonlinear first
transaxial edge 106 at that point.
[0063] Then select a second pair of axially aligned points on the
first and second transaxial edges 106 and 108, respectively, at a
location equally circumferentially spaced, for example, from the
first and second side edges 110 and 112, respectively. At this
location, the arc of the nonlinear first transaxial edge 106 is at
its farthest axial distance from the second transaxial edge 108,
which represents the distance between the second pair of points.
Comparatively, the distance between the second pair of points is
greater than the distance between the first pair of points. This
example represents the manner in which the respective axial
distances between a plurality of axially spaced points on the first
and second transaxial edges 106 and 108, respectively, varies
between opposite ends of the first transaxial edge.
[0064] It is noted that, in the preferred embodiment, both the
first and second transaxial edges 106 and 108, respectively, are
each nonlinear between opposite ends thereof. However, either, but
not both, the first transaxial edge 106 or the second transaxial
edge 108 could be linear, as in the example above, and the other
edge be nonlinear without departing from the spirit and scope of
the invention. Further, either the first transaxial edge 106 or the
second transaxial edge 108, or both, could be formed with a
nonlinear portion, rather than the entirety of the edges being
nonlinear, without departing from the spirit and scope of the
invention.
[0065] In addition, the second transaxial edge 108 can be formed in
the shape of an arc, as illustrated in FIG. 8, extending in an
axial direction away from the first transaxial edge 106. In the
preferred embodiment, the arcs of the first and second transaxial
edges 106 and 108, respectively, of each base surface 90 are of the
same shape and are in an orientation in which the first and second
transaxial edges are concave toward each other.
[0066] Referring to FIG. 8, the inward extent of the base surface
90 is shown as vertical lines within two indentations 88 on
radially opposite sides of the rivet 74. Referring to FIG. 10, the
base surface 90 of each indentation 88 extends outward and is
formed with a convex portion between the first and second side
edges 110 and 112, respectively, as viewed from the exterior of the
rivet body 82. Further, as shown in FIG. 10, the base surface 90 of
each indentation 88 forms an arc surface facing in a direction away
from the axis 85 (FIG. 8) of the rivet body 82, and is formed at a
radius about the axis of the rivet body which is less than the
prescribed radius of the outer surface 86 of the rivet body.
[0067] Consequently, the arc surfaces, formed by the base surfaces
90 in any one of the first, second or third transaxial planes, are
each located on spaced portions of an imaginary circle which is
concentric with, and within, a circle which is coincidental with
the circumference of the outer surface 86 of the rivet body 82.
[0068] Referring again to FIG. 8, each of the indentations 88 is
formed with a first border surface 114, which is contiguous with
the first transaxial edge 106 of the base surface 90, and which
flares away from the base surface, toward the flangeless end 100 of
the rivet body 82 and toward the outer surface 86 of the body. Each
of the indentations 88 is also formed with a second border surface
116, which is contiguous with the second transaxial edge 108 of the
base surface 90, and which flares away from the base surface toward
the flange 92 (FIG. 7) of the rivet body 82 and toward the outer
surface 86 of the body.
[0069] The preferred embodiment of the rivet 74 is formed with the
flared first border surface 114 and the flared second border
surface 116, which are contiguous with first transaxial edge 106
and the second transaxial edge 108, respectively, to provide a
transition between the base surface 90 and the outer surface 86 of
the rivet body 82. The transition surfaces, between the base
surface and the outer surface 86, need not be flared, but could be,
for example, surfaces which are at right angles to the base surface
90 without departing from the spirit and scope of the
invention.
[0070] Referring to FIGS. 8 and 10, each of the indentations 88 is
further formed with a third border surface 118, which is contiguous
with the first side edge 110 of the base surface 90, and which
flares away from the base surface in a circumferential direction
and toward the outer surface 86 of the rivet body 82. Each of the
indentations 88 is further formed with a fourth border surface 120,
which is contiguous with the second side edge 112 of the base
surface 90, and which flares away from the base surface in a
circumferential direction and toward the outer surface 86 of the
rivet body 82.
[0071] The first, second, third and fourth border surfaces 114,
116, 118 and 120, respectively, are in the form of a plurality of
differently oriented surfaces which are integrally and continuously
joined about the endless outboard edge 104 of the base surface 90
to form an intermediate surface 122. The intermediate surface 122
is flared outward in different directions away from the endless
outboard edge 104 of the base surface 90, and extends between, and
is contiguous with, the outer surface 86 of the rivet body 82 and
the endless outboard edge.
[0072] Referring to FIG. 11, a first workpiece 124 and a second
workpiece 126 are to be retained together by a set rivet. the
workpieces 124 and 126 are generally of equal thickness, and are
formed with respective oversize holes 128 and 130. The diameter of
the holes 128 and 130 is larger than the diameter of the outer
surface 86 of the rivet body 82, and are thereby oversize in
comparison with the rivet body. Initially, the workpieces 124 and
126 are assembled with the rivet 74 as shown in FIG. 11. The free
end 103 of the mandrel stem 78 is grasped and pulled away from the
flange 92 so that pull or setting loads are developed in the
direction of the arrows shown in FIG. 9.
[0073] The workpieces 124 and 126 are not shown in FIGS. 12 and 13
in order that the bulging of the segments 87a, 87b, 87c and 87d may
be visualized. As shown in FIG. 12, with the application of the
setting load, the indentations 88 begin to collapse, and the
segments 87a, 87b, 87c and 87d of the rivet body 82 begin to bulge
radially outward. In this mode, the segment 87d is bulging toward
engagement with the walls of the holes 124 and 126 (FIG. 11), and
the segments 87a, 87b and 87c are also bulging.
[0074] Referring to FIG. 13, upon continued pulling of the free end
103 of the mandrel stem 78, the indentations 88 are nearly closed,
and the segments 87a, 87b, 87c and 87d continue to bulge radially
outward. Also, the mandrel head 80 is being pulled into the segment
87a at the flangeless end 100 (FIG. 7) of the rivet body 82.
[0075] Eventually, as shown in FIG. 14, the rivet 74 is set whereby
the indentations 88 are completely collapsed and closed, and the
segments 87a, 87b, 87c and 87d of the rivet body 82 have reached
their maximum bulge. The segment 87d has expanded radially outward
to fully engage the walls of the openings 128 and 130 of the
workpieces 124 and 126, respectively, to facilitate retaining the
workpieces together. Also, the segment 87c has expanded radially
outward to overlap a portion of the outer surface of the workpiece
124, adjacent the opening 128 thereof, to capture the workpieces
124 and 126 between the flange 92 and the segment 87c. In this
manner, the workpieces 124 and 126 are retained together.
[0076] Additionally, the mandrel head 80 has been pulled farther
into the segment 87a of the rivet body 82, with the segment having
portions 134 which wrap partially and slightly about a portion of
the head to assist in retaining the mandrel 76 with the rivet body
82 after the rivet has been set. Also, at this time, the portion of
the mandrel stem 78, which includes the free end 103, separates at
the breakneck 98 (FIG. 7) from the remaining portion of the
breakneck, and is removed.
[0077] As shown in FIG. 15, another example of an assembly of
workpieces includes a third workpiece 132, which has been assembled
with the first and second workpieces 124 and 126, as in the process
step illustrated in FIG. 11. The third workpiece 132 is of a
thickness which is greater than the thickness of either of the
first and second workpieces. When the rivet 74 is set, the expanded
segment 87d facilitates the retaining together of the first and
second workpieces 124 and 126, as described above. The radially
outward expansion of the segments 87b and 87c, which are located
within an axial hole 133 of the third workpiece, facilitate the
retention of the third workpiece with the first and second
workpieces.
[0078] In addition, the mandrel head 80 has been pulled downward to
the extent that the segment 87a expands radially outward, and
overlaps a portion of an outward surface 135 of the third workpiece
132, which is adjacent the hole 133, to capture the first, second
and third workpieces 124, 126 and 132 between the flange 92 and the
expanded segment 87a, to further facilitate the retaining together
of the three workpieces. Also, the portion 134 of the segment 87a
partially surrounds the head 80 to retain the mandrel 76 with the
rivet body 82 after the rivet 74 has been set.
[0079] As shown in FIG. 16, the workpiece 126, of a small
thickness, and a workpiece 136 of greater thickness, have been
assembled with the unset rivet 74, in accordance with the process
step illustrated in FIG. 11. When the rivet 74 is set, the expanded
segments 87c and 87d facilitate the retaining together of the
workpiece 126 and the workpiece 136. It is noted that a portion of
the segment 87d expands into engagement with the hole 130 of the
workpiece 126, and the remaining portion of the segment 87d expands
into engagement with a portion of a hole 138 of the workpiece 136.
The segment 87c expands into engagement with the remaining portion
of the hole 138. In addition, the mandrel head 80 has been pulled
downward to the extent that the segment 87b expands radially
outward, and overlaps a portion of an outward surface of the
workpiece 136, which is adjacent the hole 138, to capture the
workpieces 126 and 136 between the flange 92 and the segment 87b,
to further facilitate the retaining together of the workpieces.
Also, the portion 134 of the segment 87a partially surrounds the
head 80 to retain the mandrel 76 with the rivet body 82 after the
rivet 74 has been set.
[0080] The multi-grip blind rivet 74 provides excellent performance
in a wide variation of workpiece thickness, oversize holes and/or
slots in a variety of workpiece materials. This excellent
performance is achieved by building the above-noted features into
the rivet body 82 that give a wider band of resistance to the
setting load and, therefore, control the radial expansion, or
bulging, of the rivet body 82. This will limit the extent to which
the mandrel head 80 enters the rivet body 82.
[0081] As noted above, after assembly of the mandrel 76 with the
rivet body 82, the plurality of indentations 88 are formed into the
rivet body at the selected transaxial planes along the rivet body.
It is the shape of the indentations 88 that give the multi-grip
blind rivet 74 its ability for delivering an improved control of
collapse of the indentations, as established by the nonlinearity of
the first and second transaxial edges 106 and 108, respectively, to
provide variable distances or widths therebetween. In addition, the
convex form of the base surface 90 of the indentations 88 provides
an enhanced capability of the multi-grip blind rivet 74 for further
control of the collapse of the indentations.
[0082] The depth of the variable distances, or width, between the
first and second tranaxial edges 106 and 108, respectively, of the
indentations 88 can be more accurately controlled due to its
relatively greater area of contact of the tooling. This will lead
to a better and more predictable product performance. Additionally,
since the mandrel breakneck 98 is remote from the mandrel head 80,
a relatively greater stability during the setting of the rivet 74,
and an improved resistance to shear after setting, can be
obtained.
[0083] The segments 87a, 87b, 87c and 87d of the rivet body 82
bulge, or expand, sequentially as the rivet body shortens under the
action of the setting tool. The work hardened base surface 90 in
the indentations 88 control the rate of collapse within the profile
of the indentations.
[0084] The base surface 90 of the indentations 88, as well as the
variable distance, or width, follow the diametric shape of the
rivet body 82, but are interrupted to form the four ribs 89. The
material of the indentations 88 has a greater hardness compared
with the material which forms the ribs 89 between the indentations.
The ribs 89 add resistance to the collapse of the indentations
88.
[0085] The shape of the indentations 88 is not linear, as described
above, and varies in axial distance, or width, to provide an "eye"
shaped profile as shown in FIG. 8. The arrangement of this shape
provides greater setting stability over a band of setting loads due
to the variable distance, or width, of the indentation 88. Thus,
the variable geometry of the "eye" shape of the indentations 88
provides accrued benefits in the form of a much better control and
stable collapse of the indentations, and an indentation collapse
that is progressive over a broad spread of setting load.
[0086] The attainment of better control of the setting of the rivet
74 is due to the broad, work hardened area which will accommodate a
greater variation in the depth of the indentation 88 and in the
break load of the mandrel breakneck 89. At the same time, since the
variable distance, or width, portions may be progressively
different in their maximum width, this will insure that the rivet
body 82 will bulge progressively from the end of the rivet.
[0087] In general, the above-identified embodiments are not to be
construed as limiting the breadth of the present invention.
Modifications, and other alternative constructions, will be
apparent which are within the spirit and scope of the invention as
defined in the appended claims.
* * * * *