Note: Descriptions are shown in the official language in which they were submitted.
\
~ 33L7
1 Large Secondary Head Rivet
Background of the Invention
Field of the Invention
This invention relates to blind rivets and particularly blind
rivets having a large secondary head.
Statement as to Prior Art
There are a number of different types of blind rivets on the
market which have a hollow rivet body with a flanged head on one end
and open on the opposite end. A mandrel stem is adapted to pass
through the opening in the body of the rivet with the mandrel stem
having an head positioned adjacent the open end of the rivet body.
The rivet body can then be inserted into the openîng in a workpiece
with the flange of the rivet lying flat against the surface of the
workpiece. The nosepiece of a rivet setting tool is placed against
the flange of the rivet body and by pulling the mandrel, the rivet
body opposite the flange is upset by the head of the mandrel on the
opposite side of the workpiece to form a secondary head on the rivet
body thus, securing the rivet to the workDiece. This process is
generally known in the art as "setting" the rivet. A continued
pulling force on the mandrel stem will break off the mandrel stem
from the mandrel head permitting removal of the mandrel stem from
the rivet. In this manner, the rivet is secured in the opening in
the workpiece with the flange of the rivet against one surface of
the workpiece and the formed secondary head against the opposite
surface of the workpiece.
Examples of rivets of this type and tools for setting the
rivets are illustrated in U.S. Patent Nos. 3,254,522; 3,302,444 and
3,324,700.
2~2~
1 Summary of the Invention
In the aforementioned types of blind rivets, the rivet body is
generally slightly smaller than the opening of the workpiece.
Further, the length of rivet body is slightly longer than the
thickness of the workpiece. Thus, in the "setting" of the rivet, the
secondary head is smaller than the flanged end of the rivet.
Further, in this type of rivet, as the mandrel head is forced
against the rivet body to form the secondary head, resulting lateral
forces from the rivet body act against the opening in the workpiece.
If the workpiece is a soft material, these lateral forces will
enlarge or otherwise deform the opening in the workpiece leaving a
poor connection.
It is therefore an object of this invention to provide a blind
rivet which has a rivet body configuration which can form the
secondary head permitting the rivet to be used in soft material.
It is another object of this invention to provide a rivet with
an enlarged secondary head to provide a larger bearing area on the
workpiece to reduce the likelihood of failure of the bearing area
between the secondary head and a workpiece of soft material or
workpieces that have holes slightly larger than the body of the
rivet.
It is further object of this invention to provide a blind rivet
that is capable of fastening a wide range of thickness of workpieces
together.
It is also an object of this invention to provide a blind rivet
having a rivet body with longitudinally disposed preformed areas of
weakness along the body to form the secondary head. The rivet body
is of a length such that a wide range of thickness of workpieces can
be secured together. During the setting operation, the rivet body is
~ i3017
-- 3
adapted to separate along the longitudinal areas of
weakeness to form a plurality of spaced petals that
form the secondary head.
It is an additional object of this invention
to provide longitudinally extending weakened areas
along the body of a rivet forming abutting solid body
portions which separate when the rivet is set to form
an enlarged secondary head on the rivet.
According to the above objects, from a broad
aspect, the present invention provides a blind rivet
of the type adapted to be inserted into the opening in a
workpiece and having a flange at one end and adapted to
be deformed by the head of a mandrel at the opposite end
when the mandrel is pulled. The blind rivet has an
elongated rivet body carrying a flange at one end with a
plurality of longitudinally extending weakened areas being
provided on the body between the flange and the opposite
end. The weakened areas form slits which are spaced from
the flange and the opposite end so that a continuous solid
annular section is formed on the rivet body adjacent the
flange and the opposite end. Longitudinally extending
solid portions are formed between the weakened areas that
have abutting line contact throughout their longitudinally
extent at the weakened areas. These weakened areas are
adapted to separate when the rivet body is deformed to
form from the solid portions a plurality of outwardly
extending petals that form an enlarged secondary head
on the rivet. The weakened areas only of the rivet body
are adapted to be deformed when a mandrel, extending
through the body is pulled so that minimal lateral forces
would be exerted on an opening in a workpiece and the
deformation of the rivet body would be localized. When
the rivet is deformed, the solid annular section adjacent
the opposite end is adapted to retain the mandrel head
to seal the rivet within the workpiece opening.
These and other objects will become apparent from
the accompanying description along with the drawings.
2~ 3q~L~7
1 Brief Description o _the Drawings
Figure l is an illustration of the blind rivet assembled on a
mandrel;
Figure 2 is an illustration of the blind rivet in a workpiece
and illustrating the forming of the rivet body at the beginning of
setting operation;
Figure 3 is an illustration of the rivet at the completion of
the setting operation;
Figure 4 is an illustration of the set rivet with the mandrel
removed,
Figure 5 is an illustration of the rivet positioned through a
considerable thickness of material;
Figure 6 is an illustration of the rivet positioned through a
thin workpiece; and
Figure 7 is an enlarged sectional view taken along the line 7-7
of Figure 1.
1 Description of the Preferred Embodiment
-
Attention is now directed to Figure l which illustrates the
rivet 10 having a cylindrical open body 12 with a flange 14 disposed
on one end normal to the longitudinal extent of the body 12. The
rivet body 12 is open at 16 on the end 18 opposite the flange 14.
A mandrel 20 has a stem 22 adapted to pass through the rivet
body 12 and head 24 adapted to seat against the end 18 of the rivet
body 12. There is a shoulder (not shown) adjacent the mandrel head
that has an interference fit into the opening 16 to retain the
mandrel and rivet in assembled condition, as is well known in the
art.The rivet body is adapted to be inserted through the opening in
a workpiece and by holding the flange against the workpiece and
pulling on the mandrel stem, the mandrel head is forced against the
open end of the rivet body to upset the rivet body to form a
secondary head on the rivet. This is a well known procedure in the
art of setting blind rivets.
In the conventional rivet, the rivet is supplied in many
diameters and lengths so that the rivet body is sized to the opening
in the workpiece and the thickness of the workpiece. That is, in
the conventional rivet, a rivet size and length is selected so that
the rivet body is slightly smaller than the size of the opening in
the workpiece and the rivet length is slightly longer than the
thickness of the work piece, so that, upon forming the rivet, the
rivet body has a tight fit in the opening in the workpiece and the
secondary head is forced against the surface of the workpiece in a
small area.
The rivet of this invention overcomes the necessity of having a
plurality of different sized rivets and is able to not only be
utilized in a workpiece material that is soft, but will also secure
workpieces together that have a wide range of thickness.
~ 3~L7
1 As illustrated in Figure 1, the rivet body 12 has a plurality
of elongated weakened areas 26 extending longitudinally of the body
12 and spaced at 28 and 30 from the flange 14 and end 18 of the
rivet body. The weakened areas 26 are substantially through the
material thickness of the body itself to localize the area in which
the rivet body will deform during the forming of the rivet. The
weakened areas 26 also are formed in the rivet body without changing
the circular crossectional contour of the rivet body. Further, with
the weakened areas terminating spaced from the flange and end of the
rivet body, the flange will not tear loose from the rivet body and
the mandrel head will bury into the rivet body and be held thereby
after the rivet is set, as will become more apparent hereinafter.
Further, the forces normal to the rivet body are less so that the
rivet can be utilized with softer material without effecting the
shape of the opening in the workpiece. Additionally, since there is
less force normal to the rivet body, it is not necessary that the
rivet body fit snugly in the opening in the workpiece, as is the
case of the conventional rivet, to enable the rivet secondary head
to be formed. Therefore, the rivet can be used in oversized holes,
that is, holes larger in diameter than the diameter of the rivet
body (see Fig.2).
As illustrated in Figure 2, as the mandrel 20 is pulled (while
the flange 14 is being held in the conventional manner by the
nosepiece of a tool, not shown), the rivet body 12 separates along
the lines of the weakened areas 26 to form a plurality of wings or
petals 32, 34, 36. The weakened areas 26 are circumferentially
equally spaced about the rivet body 12 so that the axial pulling
force of the mandrel head 24 will remain axial, and force each of
the petals 32 to 36 out equally from the rivet body 12. Further,
each of the petals 32 to 36 will deform at their medial area 38 so
1 that the upper and lower deformed portions 40 and 42 will be equal
in length.
As the mandrel is further pulled, the secondary head is formed.
Because of the length of the rivet body in comparison to the
thickness of the workpieces 44 and 46, the deformed portions 40,42
will extend outwardly beyond the opening 48 in the workpieces even
though the opening 48 is larger than the diameter of the rivet body
(See Figures 2 and 3). Since the deformed portion 42 overlaps the
deformed portion 40, additional rigidity is obtained in the contact
of portion 40 with the workpiece. Further, since the weakened areas
are circumferentially equally spaced about the rivet body, the axial
force of the mandrel head will equally deform the petals 32 to 36.
This arrangement enables the rivet of this invention to be used in
soft materials without affecting the opening in the workpiece.
Attention is now directed to Figure 3 which illustrates the
rivet with the secondary head 50 completely formed. As in a
conventional rivet, as the secondary head becomes completely formed,
the mandrel stem 22 will break from the head 24 leaving the head
formed into the end 18 of the rivet body as illustrated in Figure 3.
With the rivet body having a uniform crossection throughout its
length and the head 24 becoming surrounded by the deformed open end
16, the head 24 becomes partially encapsolated by the rivet body to
retain the head 24 in the rivet.
It should also be noted that the weakened areas leave the solid
portions of the rivet body that form petals 32-36 in abutting
relation when the rivet is in the free state. This lends structural
integrity to the rivet body for handling and insertion of tne
mandrel during the assembly of the rivet and mandrel. Further, the
petals 32-36 that form the secondary head have a maximum
~2.~3~1~
cross-sectional dimension giving maximum surface area
contact of the secondary head to the workpiece (see
Figure 7).
Another novel feature of the large secondary
S head rivet of this invention is that the rivet is
capable of fastening a wide range of thicknesses of
workpieces together. As illustrated in Figure 6,
the rivet can be secured to a thin workpiece 52 in
the same manner as described in connection with secur-
ing the workpieces 40 and 42. Because of the weakened
areas 26 and their equal longitudinal spacing about
the rivet body, the petals 32-36 will be equally formed
against the workpiece as previously described.
Figure 5 illustrates a substantially thicker
group 54 of workpieces being secured together by the
novel rivet of this invention. The thickness of work-
pieces which can be secured together is the depth
from the flange to a location longitudinally spaced
from the ends of weakened areas 26 adjacent the end
18 of the rivet body 12. As illustrated in Figure
5, the head 24 of the mandrel will deform the end
18 of the rivet body and the weakened area 56 is
exposed beyond the workpiece. In this fashion, the
rivet can secure together workpieces of greater thick-
ness lending additional flexibility to the adaptations
to which the rivet can be put to use.
It should also be noted that in the applica-
tion illustrated in Figures 4 and 6, the mandrel head
24 is retained in the solid body portion of the rivet
body 12 at rivet end 18 and that the solid area 28
I of the rivet body 12 extends into the solid area 30
t of the rivet body 12 to seal the rivet body 12 in
the workpiece opening. Thus, the opposed sides of
; the workpieces are moisture and air sealed from one
~ 35 another. Therefore, in the application, workpiece
~9,
3~
- 8a -
44 could be secured to the blind side of the work-
piece 46 wherein it is desirable that moisture and
air not be permitted in the area of the backside of
workpiece 46.
It can thus be seen that with a blind rivet
having a rivet body with longitudinally equally spaced
weakened areas on the rivet body, a larger bearing
area of the secondary head can be obtained. Further,
the rivet is particularly adaptable for use in soft
workpieces and where oversized openings are present
in the workpieces. Additionally, the novel rivet
of this invention is capable of fastening a wide range
of thicknesses of material.
