Note: Descriptions are shown in the official language in which they were submitted.
2138S23
Self-Drilllna Hollow Rivet
The invention concerns a self-drilling hollow rivet
comprising a rivet bushing and exhibiting a set-head on one
end and a closing head capable of formation on the other
end, with a drill shaft axially penetrating through the
rivet bushing and exhibiting rotation carriers on either
side of an intended breaking location and provided on one
end with a drill head and on the other end of the drill
shaft and with tensioning carriers for a setting apparatus,
whereby the drill head tapers towards the rivet bushing or
towards the rivet bushing section. ;i
A self-drilling hollow rivet of this type has become known
in the art through DE-OS 2554577.
With this type of rivet, construction components comprising
the same or different materials can be permanently connected
to each other. Rivets have the advantage, compared to other
types of connecting means, that the construction components
to be joined do not distort and do not undergo a structural
change as can occur in welding. Construction components from
differing materials can be easily, permanently and securely
connected to each other. With modern riveting systems,
economical connections of highest quality can be effected.
2138523
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The self-drilling hollow rivet which is known in the art
exhibits rotation carriers on both sides of an intended
breaking location which comprise parallel opposing flat
surfaces on the drill shaft which run in a longitudinal
direction. The smooth surfaces of the drill shafts lie
closely adjacent to corresponding opposing surfaces of the
rivet bushing. When the drill shaft is rotated, the rivet
bushing rotates therewith.
Tension carriers are formed on the other end of the drill
shaft opposite to the drill head in order to pull the drill
shaft, under exercise of substantial tensioning force
through the rivet bushing and in opposition to a resistant
force produced by the drill head, through the rivet bushing.
In the course of this tensioning process the rivet bushing
is deformed and a closing head forms. The drill shaft
simultaneously shears at the predetermined breaking location
and the drill head falls out of the closing head. The
rotational carriers on both sides of the intended breaking
location are provided in order to transmit a torque which is
produced by the drilling procedure to the drill head without
breaking the drill shaft.
.
In order to successfully transfer the torque to the drill
head and to relieve the intended breaking location it is
necessary for the parallel surfaces of the drill shaft to
precisely seat on the opposing surfaces of the rivet bushing
without play. This is in particular necessary for
applications with which the rotation direction of the drill
must be changed. For this reàson the self-drilling hollow
rivet known in the art is difficult and expensive to -.
produce.
2138523
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Since the outer wall of the rivet should be seated as
closely as possible on the inner wall of an object into
which the rivet is to be set, the overcoming of a certain
amount of frictional force is necessary. In consequence of
the rotation of the drill shaft, it is necessary for the
rotation carriers of the self-drilling hollow rivet known in
the art to already carry a substantial load during rotation,
since the bore resistance as well as the frictional
resistance between the rivet bushing and the adjacent wall
must be overcome. For this reason the intended breaking
location is not sufficiently relieved.
Furthermore, by means of the shoulder formed between the end
of the rivet bushing and the drill head, one guarantees that
the drill head does not sink into the rivet bushing during
the setting procedure. For this reason the drill head either
continues to hang loosely in the rivet bushing after the
setting procedure or it falls out of the closing head.
The formed shoulder has, however, the disadvantage that a
pulling back leads to the formation of cracks in the rivet
bushing when setting the rivet and when forming the closing
head.
Furthermore the self drilling hollow rivet known in the art
has the additional disadvantage that the rotation carriers
must already be formed during production and fabrication.
The rotational carriers of the drill shaft and their
corresponding recesses in the rivet bushing require a
difficult preorientation prior to each boring procedure.
An additional self-drilling hollow rivet is known in the art
2138~2~
from US-A 3,935,786 with which the rotational carriers
comprise longitudinal ribs, which are difficult to
fabricate, (on the drill shaft) and corresponding recesses
in the rivet bushing.
The self-drilling hollow rivet can also be driven via the
drill shaft.
A self-drilling hollow rivet which can be driven via the
set-head is known in the art from DE-OS 2554577, whereby the
rotation carriers are not configured on both sides of the
intended breaking location.
It is therefore the purpose of the presently filed
application to further improve a rivet of the above
mentioned kind in such a fashion that the drilling and
setting procedure can be securely enacted without waste to
produce a tight rivet connection.
This purpose is achieved in accordance with the invention in
that the rotation carrier penetrates into the material of
the rivet housing, the rotation carriers border, without
exhibiting a shoulder, on the taper of the drill head, and
the set-head exhibits at least two flattened surfaces on the
outer periphery which run parallel to the plane of a drill
axis .
It is possible, using the self-drilling hollow rivet in
accordance with the invention, for the drilling procedure to
be securely carried out since the setting apparatus can
tightly frictionally engage the set-head on its outer
periphery. The torque occurring during the drilling
procedure is securely transferred via the rotation carriers
2138~23
-- 3D --
formed on both sides of the intended breaking location
without having an undesirable shearing on the drill shaft
during the drilling procedure in the vicinity of the
intended breaking location. Since the rotation carriers
penetrate into the material of the rivet bushing, the
fabrication of recesses in the rivet bushing is not
necessary. Neither is it necessary to preorient the rivet
bushing and the drill shaft prior to the setting procedure.
When the drilling procedure is ended it is possible for the
self-drilling hollow-rivet to be securely set and the
shoulder-free conical taper of the drill head guarantees
that the rivet bushing is securely widened to an extent
which depends on the conical shape without the formation of
cracks to form a closing head. Thereby the drill head is
pulled into the rivet bushing so that the rivet bushing
nearly completely surrounds the drill head. The closing head
is thereby stabilized and tightly closed.
2I38523
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The drill shart does not break at the provided intended
breaking location until the drill head is pulled into the
rivet bushing to undergo a secure connection therewith.
Even prior to the setting procedure the rotation carrie-s
assure that the rivet bushing and the drill, comprising the
drill head and the drill shaft, constitute a firmly joined
unit.
The setting apparatus can engage the self-drilling hollow-
rivet in an optimum rotation-transferring fashion by means
of the surfaces on the set-head running parallel to the
rivet bushing.
In further configurations of the invention, the drill shaft
and the drill head are manufactured as integral parts and
both the drill head as well as the drill shaft are made from
a hardened material.
This has the advantage that no additional weak locations on
the drill can be formed during the drilling procedure it-
self. The drill can break only at the intended breaking
location when the tensioning forces exceed a predetermined
amount. In the event that the drill shaft, along with the
drill head, is uniformly hardened, it is possible for it to
withstand even larger loads during the drilling procedure
without damage.
In a further manifestation of the invention a sealing film
is provided for on an inner wall of the rivet bushing or the
rivet bushing section and a seal is arranged below the set-
head. This has the advantage that the rivet connection can
be sealed to a further extent in the event that same is
213852~
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needed.
In a further manifestaticn of the invention, the rotation
carriers are configured as ribs exhibiting a triangular
shaped cross section which are evenly separated from the
surface of the drill shaft in the longitudinal direction
over nearly the entire le~gth. The drill shaft is securely
held in the rivet bushing.
This has the advantage that on the one hand the drill cannot
unintentionally fall out of the rivet bushing, and, on the
other hand, the rotational forces occurring during the
drilling procedure can be uniformly transferred from the
rivet bushing onto the drill shaft. Should the self-drilling
hollow rivet in accordance with the invention be configured
with rotation carriers on both sides of the intended break-
ing location as well as on the outer periphery of the set-
head, it is not necessary to directly drive~the drill shaft
during the drilling procedure. It is sufficient to cause
rotation of the rivet housing via the set head, that is to
say, via the at least two flattened surfaces provided
therein.
The conically formed drill head allows for the possibility
of not only setting the self-drilling hollow rivet in one
working step, rather also to permanently and securely spread
out same. The hollow-rivet in accordance with the invention
is, due to a relative motion between the drill shaft and the
rivet bushing, sufficiently strongly spread in the vicinity
of the closing head that the rivet bushing not only tightly
fills the rivet hole over the entire length but the rivet
bushing is also sufficiently widened on the end having the
closing head that the drill head section with the conically
213852~
-- 6
running cross-section permanently seals the rivet hole.
In this fashion the self-drilling hollow rivet in accordance
with the invention fulfills all extended requirements posed
in high rise steel construction, crane construction, bridge
construction with support carrier connections, supports,
joints in steel frame work of trusswork and crane girdering,
plate girders, in the construction of containers and in
binding connections associated with automotive body, automo-
tive and airplane construction. The self-drilling hollow
rivet in accordance with the invention is particularly ad-
vantageous in the construction of facades and in the area of
roof construction. Sheet metal overlaps of all kinds can be
joined in a secure and rapid fashion. The self-drilling
hollow rivet is not only easily handled but can also be
worked in a rapid and secure fashion and can be equipped
with all conventional set-head shapes. A leak proof rivet
connection can be effected with the self-drilling hollow
rivet. Furthermore, it is possible to also form holding
grooves on the drill shaft or in the vicinity of the rota-
tion carrier which are arranged neighbouring the drill head
into which the plastic-deformed rivet bushing material flows
during the setting procedure to effect an even stronger
connection between the drill head and the closing head.
Should the drill shaft itself exhibit a triangular shaped
cross-section this has the advantage that the drill shaft
cannot slip in the setting apparatus during the drilling
procedure, e.g. cannot twist or rotationally slip in an un-
desired fashion and the triangular shaped cross sectional
form also guarantees that the conformed rivet bushing
securely drives the drill shaft during the drilling proce-
dure.
2138523
-- 7
Further advantages can be derived from the description of
the accompanying drawing. Likewise the above mentioned fea-
tures and those which are to be explained further below in
accordance with the invention can be utilized individually
or collectively in arbitrary combination. The embodiments
mentioned are not to be considered as exhaustive enumera-
tions rather have exemplary character only.
The invention is represented in the drawing and will be
further described with reference to embodiments.
Fig. 1 shows a cut through a self-drilling hollow rivet in
accordance with the invention having a rivet bush-
ing between a first and a second construction
component;
Fig. 2 shows a set and closed self-drilling hollow rivet
in accordance with Fig. l;
Fig. 3 shows a cut through a section of a rivet bushing of
a self-drilling hollow rivet with a drill shaft ex-
hibiting holding and rotation carriers on both
sides of a intended breaking location;
Fig. 4 shows a further embodiment o~ a self-drilling rivet
in accordance with the invention having a sidewards
flattened set-head and a drill shaft exhibiting
carriers-which engage into the rivet bushing;
Fig. 4a is a view in accordance with IVa - IVa of Fig. 4;
Fig. S shows an additional embodiment of a self-drilling
2138523
-
-- 8
hollow rivet in accordance with the invention
having a shaft with an oval cross-section;
Fig. 5a shows a view Va - Va of Fig. 5;
Fig. 6 shows a further schematic representation of a set-
head in accordance with the invention.
The individual figures of the drawings show the object in
accordance with the invention in a strongly schematized
fashion and are not to be taken to scale. The objects of the
individual figures are represented partially in a greatly
enlarged fashion so that their construction can be better
shown. The cut surfaces of the drill head are represented in
an oversimplified fashion.
Fig. 1 shows a self-drilling hollow rivet lO, represented in
cross section, holding a drill 11 in a guided fashion. A
rivet bushing 12 exhibits a shaft end 13 which is directed
towards a drill head 14. The shaft end 13 borders on the
drill head 14. The drill head 14 drills a rivet hole 15 in a
first construction component 16 and a second construction
component 17 which are to be permanently connected to each
other. The drill head 14 exhibits, in the embodiment of
Fig. 1, a diameter which is slightly larger than the outer
diameter of the rivet bushing 12. When closing the set self-
drilling hollow rivet 10, the rivet bushing 12 is plasti-
cally deformed in the direction of the active sealing forces
and the material-of the rivet bushing can flow into the free
space between the rivet bushing outer diameter and the rivet
hole diameter. In the embodiment of Fig. 1, the drill 11 ex- ---
hibits a drill shaft 18 which is equipped with an intended
breaking location 19 which is more or less distant from the
~ 2138S23
g
drill head 14. Rotation carriers are formed for the drilling
process on both sides of the intended breaking location 19
as longitudinal ribs 19', 19'' having rectangular shape
which tightly and securely press into the inner wall of the
rivet bushing 12 when the drill 11 is pulled into the rivet
bushing 12 during the manufacture of the self-drilling
hollow rivet. The drill 11 is securely connected to the
rivet bushing 12 by means of the longitudinal ribs 19',
19''. Should an auxiliary tool (not shown), for example, a
setting apparatus be applied to the set-head 20 in such a
fashion that the set-head 20 is pushed in a direction of a
first construction component 16 and the drill shaft 18 is
pulled in the direction of the arrow 20', whereby the clos-
ing forces act in a direction of arrow 20', it is possible
for the drill head 14 to be pulled into the rivet
bushing 12. The drill head 14 slides into the shaft end 13
via a ring-shaped conical surface 21 configured on the drill
head 14 and rivet bushing material 12 surrounds the drill
head 14. The shaft end 13 is carefully and evenly widened
via the conically shaped surface 21 so that the material of
the shaft end 13 can jacket the drill head 14 without
cracking. The conically formed surface 21 and the surfaces
of all longitudinal ribs 19' can be coated with a sealing
film. Likewise a seal 22 is brought onto the surface of the
set-head 20 which faces the first construction component 16.
The inner wall of the rivet bushing 12 can likewise be pro-
vided with a sealing film coating.
A section 26 of the drill shaft 18, also shown in Fig. 1, is
provided with ring-shaped grooves 27 which have exemplary
character only. Gripping claws of a setting apparatus can
engage into the ring-shaped grooves 27 so that a defined
force component can be generated in a direction of arrow
2138523
-- 10 --
20'. The drill 11, consisting of a drill shaft 18 and a
drill head 14, is manufactured as one piece and the material
from which the drill 11 is made is uniformly hardened.
Surfaces are provided, preferentially over the entire
material thickness of the set-head 20, on the outer peri-
phery of the set-head 20 which are longitudinally and
axially parallel to the rivet bushing 12 and which likewise
serve as rotation carriers for the self-drilling hollow
rivet 10. These surfaces, which are not shown in Fig. 1, are
surrounded by the setting apparatus in close frictional
engagement and the self-drilling hollow rivet 10 rotates
during the drilling procedure. The rotating rivet bushing 12
can also drive the drill shaft 18 so that it is not ab-
solutely necessary for the drill shaft 18 itself to be
driven.
It is also possible for holding grooves to be fashioned in
the vicinity of the drill head 14 or in the vicinity of the
longitudinal ribs 19' to additionally fix the drill head 14
in the rivet bushing 12 in a secure fashion. These holding
grooves provide extra security for a set rivet.
The drill axis is indicated in Fig. 1 as 24.
Fig. 2 shows a self-drilling hollow rivet 10 in the set and
closed state after the drill shaft 18, as represented in
Fig. 1, has been strongly pulled in the direction of arrow
20' to tear off the drill shaft 18 at the intended.breaking
location 19. The end of the rivet bushing 12 facing away
from the set-head 20 has been made into an enlargement 23 to ~-
form the closing head. The closing head overlaps the second ~:
construction component 17 and tightly surrounds the drill
2138523
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head 14. The drill head 14 remains in the hollow region of
the self-drilling hollow rivet 10 to stabilize the closing
head. In this fashion, the first construction component 16
is permanently attached to the second construction component
17. The rivet bushing 12 has been enlarged via the conically
running surface 21 and the longitudinal ribs 19' have
pressed more firmly into the inner wall of the rivet bushing
12.
Fig. 3 shows a cross section of a rivet bushing section 30,
for example, the rivet bushing section 30 of a self-drilling
hollow rivet. The drill shaft 30 is held in the rivet
bushing section 30 and a drill head 32 is adjacent thereto.
The drill head 32 is arranged outside of an end 33 of the
rivet bushing section 30. A conical expanded portion 34 is
adjacent to the drill shaft 31 and points outwardly away
from end 33. Longitudinal ribs 35,36 are formed as rotation
carriers within the rivet bushing section 30 on the drill
shaft 31 which additionally hold the rivet bushing section
30 and the drill shaft 31 together. An additional contour 37
is formed on drill shaft 31. The contour 37 is dimensioned
as an intended breaking location.
A surface section 39 is provided on the drill head 32 itself
which works together with the end 33 of the rivet bushing
section 30 when the drill shaft 31 is pulled back in the
direction of arrow 40. The end 33 flows under plastic
deformation about the drill head 32 and the two parts, the
drill head 32 and the rivet bushing section 30, form a per-
manent connection. The hollow region of the rivet bushing
section 30 iS sealed by the drill head 32 and the longitu-
dinal ribs 35.
2138523
- 12 -
The conical expanced portions on the drill head 32 shown in
Fig. 3 can exhibit differing angles for the dimensioning of
the expanded portion. It is possible for the drill shaft 31
to exhibit, which is not shown in the figure, means on the
end opposite to the drill head 32 to allow a setting
apparatus, also not described, to grasp the drill shaft 31
in tight frictional engagement. The drill shaft 31 is
manufactured from a hardened material. The drill shaft 31
and the drill head 32 are produced from a single material
(mono-metal).
Fig. 4 shows an additional embodiment of a self-drilling
hollow rivet in accordance with the invention having a drill
shaft 41 with ribs 42 formed as rotation carriers in the
vicinity of the drill tip which engage into the inner walls
43 of a rivet bushing 44. The rivet bushing 44 is securely
connected to the arill shart 41 by means of the engagement
of the ribs 42 which can be configured as guiding ribs. When
the rivet bushing 44 is set into rotation, the drill shaft
41 and the drill tip rotate along therewith. In addition a
first surface 46 and a second surface 47 are formed on the
set-head 45 which are adapted to receive an auxiliary tool
for the rotational motion. A contour 48 is provided for as
an intended breaking location between, as viewed in the
longitudinal direction, the ribs 42. Carriers 49 are pro-
vided for on the drill shaft 41 so that tensioning forces
can be transferred in a defined fashion in the direction of
arrow 49'. Setting apparatus claws securely engage the
carrier 49'.
Fig. 4a shows a cut IVa - IVa of Fig. 4. A plan view of the
configuration of the set-head 45 is shown and the drill --
shaft 41 is cut. The surfaces 46,47 are visible.
2I38523
- 13 -
The surfaces 46,47 can also form the peripheral surfaces of
the set-head 45 configured in a four-, six- or eight-edged
fashion.
Fig. 5 shows an additional manifestation of a self-drilling
hollow rivet in accordance with the invention with an oval
or triangular-shaped sha,t cross section of a drill shaft 51
which engages into an opening of a rivet bushing 52 and
penetrates from one end to the other end therethrough. The
opening of the rivet bushing 52 has a cross section which is
adapted to the cross sectional shape of the drill shaft 51
with necessary play. Should the cross sectional shape of the
drill shaft 51 be adapted to the cross sectional shape of
the rivet bushing 52, a frictional connection with regard to
rotational motion in the direction of arrow 5~ is guaranteed
by this configuration. Likewise, a drill shaft 51 configured
in this fashion cannot twist or slip in an undefined fashion
in the setting apparatus. Ring-shaped grooves, which are not
described further, are provided on the drill shaft 51 in
order to pull the drill shaft 51 in the direction of arrow
55 after completion of the drilling process to effect the
formation of the closing head. Ribs or nubs 56l which also
function as rotation carriers, serve to hold the drill shaft
51 securely within the rivet bushing 52. An intended break-
ing location 57 is furthermore formed on the drill shaft 51.
Fig. 5a shows a cut Va - Va of Fig. 5 wherein it is clearly
shown how the cross sectional form of the drill shaft 51 and
the opening of the rivet bushing 52 or the opening through
the set-head 53 are adapted to each other. Surfaces 58,59, -
which are additionally formed on set-head 53, serve as rota-
tion carriers.
2138523
- 14 -
Fig. 6 shows an additional configuration of a set-head 63
having a rivet bushing 62. Surfaces 64,65 are configured on
the outer periphery of the set-head 63 axis-parallel to
rivet bushing 62 and function as rotation carriers. A
shoulder 66 borders on the surfaces 64,65 to serve as a flat
seating surface for the ends of the setting apparatus.
A self-drilling hollow rivet 10 exhibits a drill 11 and a
rivet bushing 12 which are intended to hold together a first
and a second construction component 16,17. In a first
working step a rivet hole 15 is bored with the drill 11 in
order to permanently connect the construction components 16
and 17 to each other. The drill 11 is held via ribs 19',19''
in a tight and secure fashion in the rivet bushing 12.
Flattened surfaces are proviaed for on the set-head 20 at
its outer periphery into which a setting apparatus engages.
The setting apparatus sets the self-drilling hollow rivet
into rotation. The rotational forces are evenly transmitted
from the self-drilling hollow rivet 12 to the drill 11 via
the rotation carriers 19',19'' without having the drill
shaft 18 tear at the intended breaking location 19 during
the drilling procedure. After completion of the drilling
procedure, the self-drilling hollow rivet 10 is set in a
second working step in which the drill shaft 18 is pulled in
the direction of arrow 20'. In this fashion setting
apparatus gripping means engage into the ring-shaped grooves
27. In this setting procedure the drill head 14 is pulled
into the rivet housing 12 and the rivet housing 12 nearly
completely encloses the drill head 14. The closing head is
formed and the hollow-rivet is tightly sealed.
