Metal working – Method of mechanical manufacture – Assembling or joining
Reexamination Certificate
2001-08-29
2003-04-15
Vidovich, Gregory (Department: 3726)
Metal working
Method of mechanical manufacture
Assembling or joining
C029S243530, C029S243540, C029S525060, C072S414000, C072S466500
Reexamination Certificate
active
06546613
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to anvil designs used in association with rivet setting machines, and more specifically relates to an anvil design which provides that less force is needed to install a self-piercing rivet.
Self-piercing rivets are used in a variety of applications in order to attach a component to a workpiece or two workpieces together. When a self-piercing rivet is installed to join two workpieces together, the rivet pierces a first workpiece and an anvil deforms the rivet and accommodates deformation of a second workpiece so that while the rivet head is spread to hold the workpieces together in clamped engagement, the rivet does not pierce the second workpiece and, in effect, becomes encapsulated. As a result, the two workpieces become secured together.
This process is generally performed using a rivet setting machine
20
, like the one illustrated in
FIGS. 1 and 2
. The rivet setting machine
20
is typically hydraulically powered and has a generally C-shaped frame
22
. One end of the C-shaped frame
22
has a carrier head
24
which holds the rivets
26
therein prior to their being attached to the workpieces
28
,
30
. Above the carrier head
24
is a driver
32
which drives the rivets
26
from the carrier head
24
into the workpieces
28
,
30
along an axis
34
. At the opposite end of the C-shaped frame
22
, an anvil
136
is attached thereto in alignment with the carrier head.
24
. The anvil
136
is used to support the workpieces
28
,
30
during the riveting process and has a cavity (not shown in
FIGS. 1
or
2
, but see
FIGS. 3 and 4
) therein which allows for the accommodation of the deformation of the rivet
26
and the workpieces
28
,
30
during the riveting process.
The cavity
138
in the anvil
136
illustrated in
FIGS. 3-9
is representative of the configuration of a cavity that has typically been provided in anvils used in such rivet setting machines
20
for the accommodation of the deformation of the rivets
26
and the workpieces
28
,
30
during a riveting process. As best illustrated in
FIG. 3
, the anvil
136
generally has a first portion
140
and a second portion
142
. The second portion
142
is dimensioned to fit within the C-shaped frame
22
of the rivet setting machine
20
while the first portion
140
is dimensioned to rest on top of the C-shaped frame
22
. At an end
144
of the first portion
140
opposite where the first portion
140
and the second portion
142
of the anvil
136
are joined together, the cavity
138
is formed therein. The end
144
of the first portion
140
also supports the workpieces
28
,
30
during the riveting process.
At the end
144
of the first portion
140
, the cavity
138
has a diameter that is smaller than a diameter of the first portion
140
of the anvil
136
. The cavity
138
typically defines a side wall
146
that extends from the end
144
of the first portion
140
into the first portion
140
toward the second portion
142
. The side wall
146
initially extends from the end
144
toward the second portion
142
at a straight, inward angle such that the diameter of the cavity
138
proximate to the end
142
is larger than the diameter of the cavity
138
proximate to the second portion
142
. The side wall
146
then extends further into the first portion
140
toward the second portion
142
at an arc, such that the arced portion
148
of the side wall
146
more dramatically extends toward a center
152
of the first portion
140
than does the straight, angled portion
150
of the side wall
146
.
The cavity
138
further defines a main portion
154
. The main portion
154
extends from the end of the arced portion
148
of the side wall
146
toward the center
152
of the first portion
140
. The main portion
154
extends from the end of the arced portion
148
toward the center
152
at a straight angle toward the end
144
of the anvil
136
. Thus, the arced portion
148
of the side wall
146
is the furthest portion of the cavity
138
from the end
144
of the anvil
136
.
Disadvantages have arisen with such an anvil design, which will be discussed in regard to the riveting process with such an anvil
136
being used, as illustrated in
FIGS. 5-9
. As illustrated in
FIG. 5
, the end
144
of the anvil
136
supports the workpieces
28
,
30
and the rivet
26
is forced into contact with the workpiece
28
by the rivet setting machine
20
, such that it begins to pierce through the workpiece
28
. As the rivet
26
continues to pierce through the workpiece
28
, as illustrated in
FIGS. 6 and 7
, the workpiece
30
deforms into the cavity
138
of the anvil
136
such that the main portion
154
of the cavity
138
supports the workpiece
30
.
As illustrated in
FIGS. 8 and 9
, the continued forcing of the rivet
26
into the workpieces
28
,
30
, which is necessary for the attachment of the rivet
26
to the workpieces
28
,
30
, causes the workpiece
30
and the rivet
26
to deform in accordance with the configuration of the cavity
138
such that the rivet
26
is forced toward the arced portion
148
of the cavity
138
, thus forcing the deformation of the workpiece
30
to abut against the main portion
154
, the arced portion
148
and the side wall
146
.
This forcing of the deforming of the workpiece
30
into the main portion
154
, the arced portion
148
and the side wall
146
has many disadvantages. One such disadvantage is that during the riveting process, the stress is elevated as there is no place for the material of the workpiece
30
to flow to during the latter stages of the riveting process. The prior art anvil configuration also causes an extreme amount of wear and tear on the anvil
136
because of the material of the workpiece
30
being forced against the main portion
154
, the arced portion
148
and the side wall
146
. The prior art anvil configuration further does not allow for a wide variance in the range of material thickness of the workpieces
28
,
30
that can be handled, such that it can not be ensured that the riveting process will be completed when a variety of thicknesses of workpieces are used, as a thicker workpiece may not be able to be fully deformed within the cavity
138
.
Such disadvantages with the prior art anvil configuration have necessitated the need for an improved anvil configuration which overcomes these disadvantages.
OBJECTS AND SUMMARY OF THE INVENTION
A general object of an embodiment of the invention is to provide an anvil configuration for a rivet setting machine that provides a cavity with a relief pocket such that material from a workpiece can flow without encountering resistance from the sidewalls of the anvil during a riveting process.
Another object of an embodiment of the invention is to provide an anvil configuration for a rivet setting machine that allows for the reduction in power or load required for the riveting process.
Yet another object of an embodiment of the invention is to provide an anvil configuration for a rivet setting machine that allows for the downsizing of the C-frame of the rivet setting machine.
Another object of an embodiment of the invention is to provide an anvil configuration for a rivet setting machine that allows for the rivet setting machine to be a pneumatic unit as opposed to a hydraulic unit.
Still another object of an embodiment of the invention is to provide an anvil configuration that reduces the wear on the anvil during the riveting process.
Yet another object of an embodiment of the invention is to provide an anvil configuration that allows the rivet setting machine to handle a wider variance in the range of material thickness of the workpieces to be joined together.
Briefly, and in accordance with at least one of the foregoing objects, an embodiment of the present invention provides an anvil for a rivet setting machine configured to drive a rivet into a workpiece within a riveting process. The anvil has a cavity therein configured to accommodate a deformation of the rivet and the workpiece during the riveting
Omgba Essama
Textron Inc.
Trexler, Bushnell Giangiorgi, Blackstone & Marr, Ltd.
Vidovich Gregory
LandOfFree
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