U.S. patent application number 10/690633 was filed with the patent office on 2004-07-08 for method of securing workpieces.
Invention is credited to Stoewer, Udo-Henning, Turlach, Gerhard.
Application Number | 20040128820 10/690633 |
Document ID | / |
Family ID | 7674736 |
Filed Date | 2004-07-08 |
United States Patent
Application |
20040128820 |
Kind Code |
A1 |
Stoewer, Udo-Henning ; et
al. |
July 8, 2004 |
Method of securing workpieces
Abstract
A method of securing at least two workpieces, which includes
inserting a bolt shaft through a bore hole formed in each of the
workpieces, and applying a sealant to the workpieces. Further, the
method includes engaging a locking collar with the bolt shaft such
that the locking collar is securely deformed in a locking manner
thereby forcing the sealant to uniformly distribute and form a thin
surface sealant layer on the bolt shaft.
Inventors: |
Stoewer, Udo-Henning;
(Bremen, DE) ; Turlach, Gerhard; (Osterode,
DE) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Family ID: |
7674736 |
Appl. No.: |
10/690633 |
Filed: |
October 23, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10690633 |
Oct 23, 2003 |
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10081878 |
Feb 20, 2002 |
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6659699 |
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Current U.S.
Class: |
29/517 |
Current CPC
Class: |
Y10T 29/49929 20150115;
F16B 19/05 20130101 |
Class at
Publication: |
029/517 |
International
Class: |
B23P 011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 20, 2001 |
DE |
101 07 952.4 |
Claims
What is claimed is:
1. A method of securing at least two workpieces, comprising:
inserting a bolt shaft through a bore hole formed in each of the at
least two workpieces; applying a sealant to the at least two
workpieces; and engaging a locking collar with the bolt shaft such
that the locking collar is securely deformed in a locking manner
thereby forcing the sealant to uniformly distribute and form a thin
surface sealant layer on the bolt shaft.
2. The method according to claim 1, wherein the applying step
applies the sealant to the two workpieces before the inserting step
inserts the bolt shaft into the bore hole of each of the at least
two workpieces.
3. The method according to claim 1, wherein the applying step
applies the sealant directly to the bolt shaft before the inserting
step inserts the bolt shaft into the bore hole of each of the at
least two workpieces.
4. The method according to claim 1, wherein the bolt shaft has a
locking portion including a plurality of grooves around a surface
of the bolt shaft and a plurality of peaks at least some having a
parallelogram shape and being disposed between the plurality of
grooves, and wherein the sealant is uniformly distributed via the
plurality of grooves around the surface of the bolt shaft when the
engaging step engages the locking collar with the bolt shaft.
5. The method according to claim 4, wherein the plurality of
grooves extend in spiral directions helically around the surface of
the bolt shaft.
6. The method according to claim 4, wherein the plurality of
grooves include a first group of spiral grooves that respectively
extend in a clockwise spiral direction and a second group of spiral
grooves that respectively extend in a counterclockwise spiral
direction and intersect with said first group of spiral
grooves.
7. The method according to claim 4, wherein the plurality of
grooves include a plurality of first grooves extending in a
circumferential direction of the bolt shaft and a plurality of
second grooves extending in a direction parallel to the
circumferential direction such that the first and second grooves
intersect with each other
8. The method according to claim 4, wherein the parallelogram shape
is a diamond parallelogram shape.
9. The method according to claim 4, wherein the parallelogram shape
is a pyramid shape with a four-sided base.
10. The method according to claim 4, wherein the parallelogram
shape is a square or rectangular shape.
11. The method according to claim 1, wherein when the engaging step
engages the locking collar with the bolt shaft, excess sealant is
squeezed out a second end of the bolt shaft via at least one groove
on a surface of the bolt shaft that opens to an outside at an axial
end of the locking portion.
12. The method according to claim 4, wherein respective ones of
said plurality of grooves intersect with one another so that all of
said plurality of grooves are interconnected and intercommunicated
with each other, and wherein at least one of said plurality of
grooves extends to and opens at an open groove end at an axial end
of said locking portion along an axial direction of the bolt shaft
such that excess sealant is squeezed out the open groove.
13. The method according to claim 4, wherein said locking portion
excludes all annular circumferential grooves.
14. The method according to claim 4, wherein each of the plurality
of peaks includes a parallelogram shape.
15. The method according to claim 4, further comprising: breaking
off a break-away portion of the bolt shaft that is connected to
said locking portion.
16. The method according to claim 15, wherein the breaking step
breaks off the break-away portion by breaking a constricted neck
encircled by a circumferential groove.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation application of published
U.S. application Ser. No. 10/081,878, filed on Feb. 20, 2002, which
claims priority under 35 U.S.C. .sctn. 119 to German Patent
Application 101 07 952.4, filed on Feb. 20, 2001, the entire
disclosure of both which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to a method of securing two or more
components, i.e. workpieces, with a locking collar, a bolt shaft
through a hole in the workpieces and a sealant.
[0004] 2. Background Information
[0005] It is generally known to use lockbolts for forming
high-strength mechanical joints of two or more workpieces, for
example in the field of aircraft manufacturing. The lockbolt is
secured in aligned holes through the workpieces, which have been
sealed or provided with a sealant. The lockbolt includes a shaft
that extends through the holes in the workpieces, and a bolt head
at one end of the shaft, whereby the head lies against the outer
surface of one of the workpieces. The other end of the shaft that
protrudes out of the opposite side of the other workpiece includes
a profiled locking portion, onto which is secured a lock ring or
collar, such as a swageable collar for establishing a secure
force-locking and force-transmitting connection. The lockbolt
further includes a break-away portion or pintail portion that is
connected to the locking portion by a predetermined breaking point
or so-called break-pin area, for example in the manner of a
frangible neck. This break-away portion can be gripped with an
appropriate tool, such as a tension-applying tool for forming the
mechanically secure connection and then breaking off the break-away
portion.
[0006] A lockbolt of the above described general type is disclosed,
for example, in published European Patent Application EP 0,955,477.
The lockbolt according to this publication has the following
structure with the following components. The lockbolt includes a
shaft comprising a shank for penetrating through and closely
fitting into the bored holes in the components or workpieces that
are to be connected. The bolt further includes a bolt head for
preventing axial movement of the lockbolt within the bored holes in
the workpieces. A locking portion or region of the shaft includes
plural circumferentially extending annular grooves, which are
engaged by a swageable locking collar for establishing a mechanical
connection of the lockbolt with the workpieces. A pintail or
break-away portion is connected to the end of the locking portion
by a break-pin area or frangible neck, which is particularly
located between the above-mentioned circumferential annular grooves
of the locking portion and the pintail. When the locking collar is
swaged and coupled onto the grooves of the locking portion, the
pintail is released from the shank by breaking the break-pin
area.
[0007] Especially according to the above mentioned EP 0,955,477, an
O-ring is arranged on the break-pin area or on the pintail, i.e.
generally between the locking collar and the free end of the bolt
opposite the bolt head. The outer diameter of the O-ring is larger
than the diameter of the shank, so that as the lockbolt, with the
0-ring thereon, is inserted into the bored hole in the workpieces,
the O-ring will wipe any excess undesired sealant within the bored
hole and prevent this sealant from reaching and filling into the
annular circumferential locking grooves. The sealant is supposed to
stay on the portion of the lockbolt between the O-ring and the free
end of the bolt, i.e. on the break-away pintail, without
contaminating the grooves of the locking portion of the bolt.
[0008] The known arrangement of a lockbolt with a sealant-wiping
O-ring is intended to prevent the undesired accumulation of sealant
from the bore hole of the workpieces into the locking grooves of
the bolt. Such sealant would otherwise have to be manually removed
from the grooves before the locking collar can be swaged and
engaged thereon. If sealant remains in the grooves when the locking
collar is to be swaged thereon, then the sealant becomes trapped
and encapsulated by the locking collar within these closed and
continuous circumferential grooves, and therefore forms a
pressurized hydraulic buffer, which prevents the proper complete
swaging engagement of the locking collar into the locking grooves
of the bolt.
[0009] In actual practice, while the O-ring wipes some sealant out
of the bored hole of the workpieces and thus ahead of and away from
the locking grooves of the bolt, some sealant nevertheless still
reaches and contaminates the annular circumferential grooves. Thus,
the proper functionality of the mechanical swaged connection cannot
be reliably and completely ensured in the event of a remaining
contamination of the parts of the bolts. This is especially
problematic due to the annular circumferential configuration of the
locking grooves of the locking portion of the known bolts. Whenever
sealant or other contaminant is present in such circumferential
annular grooves, the sealant or contaminant becomes sealed and
encapsulated in this closed groove by the locking collar being
swaged onto the locking portion of the bolt. The sealant or
contaminant thus forms a pressurized hydraulic buffer between the
locking portion of the bolt and the locking collar. As a result,
the locking collar cannot be properly and completely swaged onto
the locking portion of the bolt shank, so that an adequate
mechanical holding power cannot be achieved. Moreover, a further
disadvantage is that the O-rings must be individually installed on
the individual lockbolts, and after the bolt-securing process, the
O-rings must be tediously removed, if they have not fallen away by
themselves.
SUMMARY OF THE INVENTION
[0010] In view of the above, it is an object of the invention to
provide a lockbolt of the above described general type, which is
improved in such a manner so as to achieve a sufficient functional
security even when the functional area between the locking portion
of the bolt and the locking collar is contaminated with sealant.
Another object of the invention is to simplify the work necessary
for securely installing and fastening such a lockbolt. The
invention further aims to avoid or overcome the disadvantages of
the prior art, and to achieve additional advantages, as apparent
from the present specification.
[0011] The above objects have been achieved according to the
invention in a lockbolt having a bolt shaft and a bolt head at one
end of the bolt shaft. The bolt shaft includes a locking portion,
and a break-away portion connected to the locking portion through a
predetermined breaking point. The bolt itself is arranged further
in combination with a locking collar that is mechanically secured,
e.g. crimped or swaged, onto the locking portion of the bolt shaft.
The circumferential or generally cylindrical surface of the locking
portion of the bolt shaft is provided with a knurling thereon,
especially in the manner of a so-called brilliant or
diamond-patterned functional area. The knurling may, for example,
include an intersecting or criss-crossing pattern of spiral grooves
that respectively spiral in two opposite directions around the
locking portion of the bolt shaft, and form therebetween a
plurality of diamond-shaped knurling peaks bounded by sloping,
knurling flanks. This knurling pattern or surface configuration can
be cut, pressed, molded, cast, embossed, or otherwise formed on the
surface of the locking portion of the bolt shaft. Preferably, the
knurling grooves extend at an angle, i.e. in a spiral
configuration, from one axial end to the other of the locking
portion. A sealant is provided between the knurled surface of the
locking portion and the locking collar.
[0012] The knurling of the locking portion of the bolt shaft
provides the necessary mechanical gripping and locking structures
onto which the locking collar is deformed, i.e. crimped or swaged,
in order to establish a secure mechanical connection of the locking
collar onto the locking portion of the bolt shaft, and thereby to
securely mechanically join the workpieces between the bolt head and
the locking collar, with the bolt shaft extending through aligning
holes provided in the workpieces.
[0013] Moreover, the knurling allows the sealant between the
locking collar and the knurled surface of the locking portion of
the bolt shaft to be distributed, and any excessive sealant to be
squeezed-out, as follows. When the shaft of the locking bolt is
inserted through the aligned holes of the workpieces, which have
been sealed with a sealant, the sealant becomes smeared or wiped
onto the shaft of the bolt, including the locking portion thereof.
When the locking collar is deformed and locked onto the knurled
surface of the locking portion of the bolt shaft, the knurling
grooves allow the sealant to become uniformly spread out to form a
thin surfacial sealant layer or film over the knurled surface, i.e.
between the knurling and the inner surface of the locking collar
being deformed onto the knurling. Thereby, this thin sealant layer
provides an additional sealing and adhesive function without
hindering the mechanical swaging or deforming interconnection of
the locking collar onto the knurled surface of the locking portion
of the bolt shaft.
[0014] According to further details of embodiments of the
invention, the predetermined breaking point or frangible neck is
formed by a circumferentially extending annular groove between the
locking portion and the break-away portion of the shaft. Also, the
break-away portion preferably comprises a plurality of parallel
circumferentially extending grooves thereon, which allow a tool
such as a tensioning tool or clamping, squeezing and upsetting tool
to be mechanically secured thereon.
[0015] A significant advantage of the invention is that the
knurling provided on the surface of the locking portion of the bolt
shaft effectively prevents the formation of encapsulated chambers,
and instead provides venting and sealant-escape-paths between the
locking portion and the locking collar, as the locking collar is
deformed or swaged onto the locking portion of the bolt shaft.
Particularly, the knurling grooves provide an outlet for the excess
sealant to escape or be squeezed-out from between the locking
collar and the locking portion of the bolt shaft along these
knurling grooves, and also achieves a targeted distribution of a
small remaining amount of sealant to form a thin sealant layer or
film between the locking collar and the locking portion of the bolt
shaft, as follows. During the joining or securing process, the
locking collar is securely deformed in a force-locking manner onto
the knurling peaks, but the locking collar preferably and
advantageously does not completely penetrate into and fill the
bottom of the knurling grooves or the shaft base surface between
the knurling peaks. This leaves gap channels at the bottom of the
knurling grooves, i.e. free gap channels between the knurling base
surface and the locking collar, in which the sealant can uniformly
distribute itself. In this manner, the formation of an enclosed or
encapsulated, pressurized hydraulic buffer (which would be the case
in a continuous circumferential extending annular groove) is
avoided during the swaging deformation of the locking collar,
because the knurling includes spiral grooves that extend helically
in the axial direction so as to interrupt and open-up any isolated
grooves such as circumferentially extending grooves.
[0016] Instead of a knurling pattern including spiral knurling
grooves, it is alternatively possible to provide a knurling pattern
formed by the intersection of circumferentially extending grooves
and axially extending grooves. With such a knurling pattern, the
axially extending grooves provide the venting or
sealant-distributing function to prevent the formation of a sealed,
encapsulated hydraulic buffer of sealant material enclosed in a
continuous circumferentially extending groove. A generalized
feature of an embodiment of the invention is thus that the knurling
pattern includes grooves that extend in a direction having an axial
component, so as to prevent the formation of enclosed cells or
hydraulic buffers in which the sealant becomes trapped between the
bolt shaft surface and the locking collar.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In order that the invention may be clearly understood, it
will now be described in connection with example embodiments, with
reference to the accompanying drawings, wherein:
[0018] FIG. 1 is a side view of a first embodiment of a lockbolt
according to the invention;
[0019] FIG. 2 is a side view of the lockbolt of FIG. 1, installed
in two sectionally illustrated plate-shaped workpieces that are to
be joined, and a sectionally illustrated locking collar arranged on
the bolt, at a stage before the locking or joining process;
[0020] FIG. 3 is a view similar to that of FIG. 2, at a stage after
completion of the joining process and separation of the break-away
portion of the lockbolt; and
[0021] FIG. 4 is a side view of a second embodiment of a lockbolt
according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] As shown in FIG. 1, a lockbolt 1 includes a flat countersunk
head 3 mechanically rigidly connected to one end of a generally
cylindrical shaft 20. Instead of the countersunk head 3, the
lockbolt may have any other conventionally known head
configuration, such as a cylindrical head, a pan head, a round
head, or the like. Adjoining the bolt head 3, the shaft 20 includes
a cylindrical shank 2, which transitions through a preferably
conically tapering portion 4 into a profiled or surface-patterned
locking portion 5. The surface profiling of this locking portion 5
comprises a knurling 6 therearound, made up of knurling peaks 7B
bounded by knurling flanks 7, between respective adjacent knurling
grooves 7A. In this embodiment, the knurling peaks 7B are
essentially diamond-shaped, i.e. having a pyramid shape with a
four-sided diamond-shaped base, and the knurling grooves 7A include
two sets of grooves respectively extending in opposite spiral
directions helically around the surface of the bolt shaft and
intersecting one another.
[0023] The locking portion 5 of the bolt shaft 20 is connected
through a predetermined breaking point or frangible neck 8 to a
break-away portion 10 of the bolt shaft 20 that is adapted to have
an installation tool (not shown) engaged thereon. In this
embodiment, the predetermined breaking point or frangible neck 8 is
formed by a circumferentially extending groove 9. For securely
engaging the installation tool onto the break-away portion 10 of
the lockbolt 1, at least a part of the break-away portion 10 is
provided with grooves 11, particularly such as the illustrated
parallel circumferentially extending grooves 11.
[0024] FIG. 2 shows the arrangement of the lockbolt 1 during the
installation process. The lockbolt 1 will cooperate with a
cylindrical sleeve-shaped locking collar 16 (which may
alternatively have an axially shorter ring configuration) to form a
mechanically secure connection of two workpieces 12 and 13 with
each other. The joint and the lockbolt will additionally be sealed
by a sealant 18. In this example, the workpieces 12 and 13 are
substantially plate-shaped workpieces. These two workpieces 12 and
13 are arranged overlapping and surfacially contacting each other
with respective individual facing surfaces thereof, and are
respectively provided with mutually aligned fitting bore holes 14
and 15, through which the shank 2 of the lockbolt 1 extends.
[0025] The hole 14 in the workpiece 12 includes a conically tapered
countersink recess, in which the countersunk head 3 of the lockbolt
1 is received with the flat surface of the head 3 flush with the
outer surface of the workpiece 12. The conically tapering
transition portion 4, the locking portion 5, the predetermined
breaking point 8, and the break-away portion 10 of the lockbolt 1
protrude outwardly from the opposite side, i.e. the opposite outer
surface of the second workpiece 13. The cylindrical sleeve-shaped
locking collar 16 is arranged on the bolt shaft 20 so that the
conical tapering transition portion 4 as well as the portion 5 of
the bolt shaft 20 are received and surrounded in the bore 17 of the
locking collar 16.
[0026] In order to form a tight seal at the location of this joint,
i.e. through the holes 14 and 15 and the arrangement of the locking
bolt 1, a sealant 18 is applied between the workpieces 12 and 13,
and/or in the holes 14 and 15 of the workpieces 12 and 13, before
or together with the insertion of the shaft 20 of the lockbolt 1
into the holes 14 and 15. The sealant 18 may even be applied
directly to the locking bolt 1 when it is inserted into the holes
14 and 15. In any event, during this so-called "wet assembly" of
the lockbolt 1 into the holes 14 and 15 of the workpieces 12 and
13, contamination in the form of deposits or excess amounts of the
sealant 18 will be accumulated on the knurling 6, and particularly
in the knurling grooves 7A between the knurling flanks 7. According
to the invention, it is not necessary to remove the sealant 18 from
this area before arranging the locking collar 16 thereon, but
rather the sealant 18 at this location will purposely serve an
additional sealing and adhesive function between the lockbolt 1 and
the locking collar 16.
[0027] FIG. 3 shows the completed, mechanically secured and sealed
connection of the two workpieces 12 and 13 after completion of the
bolt setting and joining process. An installation tool (which is
not shown) has been set and engaged onto the break-away portion 10
and exerted a compression load onto the locking collar 16, such
that the locking collar 16 has been swaged into a deformed
condition 19 in such a manner so that it is engaged and locked in a
force-locking manner onto the locking portion 5 of the lockbolt 1.
While the locking collar 16 is being deformed into the deformed
condition 19, simultaneously, the sealant 18 present within the
bore 17 of the locking collar 16, 19 is being squeezed and
spread-out along the knurling 6, and especially so as to form a
thin surfacially extending sealant layer or film along the knurling
flanks 7. The sealant 18 does not become trapped or encapsulated
between the locking collar 16, 19 and the locking portion 5,
because the knurling 6 (and especially the 30 knurling grooves 7A)
allow the sealant 18 to be spread out in the axial direction. Any
excess amount of sealant 18 is squeezed-out or exuded as shown by
reference number 18' at the open axial end of the locking collar
16, 19, which communicates with the atmosphere around the lockbolt.
In this manner, the resulting thin uniform layer of sealant 18 does
not hinder the mechanical swaging of the locking collar 16, 19 onto
the knurling 6, but instead actually provides an additional
adhesive bonding and sealing function therebetween.
[0028] As further indicated in FIG. 3, at the end of the joining
process, the assembly tool is used to separate the break-away
portion 10 from the locking portion 5 of the lockbolt 1 at the
frangible neck or breaking point 8. For example, the tool engages
the grooves 11, and is then used to deflect and/or twist and/or
pull the break-away portion 10 until it is simply broken off at the
breaking point 8.
[0029] FIG. 4 shows a second example embodiment of a lockbolt 1
that is generally similar to that of FIG. 1, except that the
knurling 6 has a different configuration. In this embodiment of
FIG. 4, the knurling 6 includes square or rectangular knurling
peaks 7B formed between a first set of circumferential knurling
grooves 7A and a second set of axial knurling grooves 7A. The two
sets of grooves intersect each other. Thereby, the axially
extending grooves 7A provide for the escape or squeezing-out and
distributing of the sealant 18 in the manner as described above in
connection with FIG. 3. Thus, once again in the embodiment of FIG.
4, the sealant 18 will form a distributed thin sealant layer
between the deformed locking collar and the knurling, which does
not hinder the swaging engagement therebetween, but rather provides
an additional adhesive bonding and sealing function therebetween.
In this context, a "thin" layer is one that is sufficiently thin so
that it does not hinder the mechanical swaging engagement of the
collar onto the locking portion.
[0030] Although the invention has been described with reference to
specific example embodiments, it will be appreciated that it is
intended to cover all modifications and equivalents within the
scope of the appended claims. It should also be understood that the
present disclosure includes all possible combinations of any
individual features recited in any of the appended claims.
* * * * *