Note: Descriptions are shown in the official language in which they were submitted.
2~71~
-1- GECAN 3064
SOCKET DRIVER TOOL
Field of the Invention
The present inventlon relates to a socket for cap
screws and more specifically a socket which prevents
stripping and deformation of the heads of cap screws in
situations where the threaded portion of the bolt is
seized in the work from which the removal is desired.
Background of the Invention
Cap screws are commonly used structural fasteners
characterized by head portions having central hexagonally
shaped recesses therein. Cap screws are removed by use
of a commonly known hexagonal key socket also called an
allen key which is inserted into the hexagonal recess in
the head of the cap screw and twisted in the proper
direction to remove the screw from the structure.
Because of contamination and exposure to heat,
sometimes the cap screw will become seized in its place
in the bore of a workpiece. The use of hexagonal key
sockets for the removal of seized cap screws requires a
great deal of care to maintain a square alignment of the
key to the hexagonal recess in the screw head. When
torque is applied to the key, any misalignment may result
in the undesirable stripping of the recess in the cap
screw head (i.e. the rounding out of the "flats" of the
hexagonal recess) or further, the deformation of the wall
around the recess. Stripping and head deformation is
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GECAN 3064
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common with cap screws whose heads have been modified to
be fitted with lock wires.
When the recess in the cap screw is stripped the
screw may only be removed by complex and tedious, time
consuming methods. To aid in the removal of seized cap
screws hexagonal key sockets have been used in
combination with the application of wrench-type jaws on
the outer portions of the head. However, this arrangement
is extremely bulky and the high pressure, point-contact
of the jaws often crushes the head of the screw.
The problems associated with the removal of cap
screws in dangerous environments, such as areas having
high radioactivity levels are only amplified by the
hostile environment. In nuclear reactors, the removal of
feeder pipes from fuel channel end fittings requires that
a flange be disconnected from the end fitting by the
removal of four cap screws. This must be completed as
quickly as possible to reduce the worker's exposure to
radiation. The cap screws are often seized into the end
fitting feeder port flange and the stripping and
deformation of cap screw heads using the hexagonal key
socket is common. When the heads of the cap screws are
damaged the worker must spend an extended amount of time
exposed to the radioactivity.
An improved cap screw removal socket is taught by
German Democratic Republic Patent 144,731, issued
November 5, 1980 to Gerlach et al. In this socket the
hexagonal key is surrounded by a saw toothed flange for
engaging the top surface of the cap screw. The flange
provides beneficial frictional engagement to aid in the
removal of the cap screw, while preventing the problem of
point contact. However, misalignment of the hexagonal
key with the recess in the cap screw head can still take
place leading to stripping of the head. Further the
socket of the German patent gives no support to the wall
around the recess and does not prevent wall deformation.
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GECAN 3064
-3
Driver tools have been taught which encapsulate the
head of the screw on which they act. For example United
States Patents 4,800,788, issued January 31, 1989 to
Goldstein and 4,285,255, issued August 25, 1981 to
Winfrey, are useful especially in locating the screw head
and preventing lateral slipping of the driver tool, but
do not appear to teach much more than that.
The cap screw removal socket which has been
developed and is described herein, fully encapsulates the
head of the cap screw, preventing the subsequent
misalignment of the hexagonal key portion of the socket
with the recess in the head of the screw while adding
beneficial frictional energy to the head, thereby
providing a socket which can be used at high torques to
remove cap screws efficiently, including those cap screws
which are highly seized in the workpiece.
Object of the Invention
An object of the present invention is to provide a
socket driver tool for cap screws which prevents
stripping and deformation of the screw head during
removal.
It is another object of the present invention to
provide a socket driver tool with a replaceable hexagonal
key insert for removing cap screws without stripping and
deformation.
It is a further object of the present invention to
provide a socket driver tool with enhanced engagement of
the cap screw during removal to prevent stripping and
substantial deformation.
Summary of the Invention
According to the invention there is provided a
socket driver tool for cap screws. The socket has a
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GECAN 3064
--4--
hexagonal key portion and a cylindrical socket which act
together to remove cap screws.
According to a broad aspect of the invention there
is provided a socket driver tool for cap screws. A cap
screw is characterized as having a head with a central
hexagonally shaped recess. The socket driver tool
comprises a hollow cylindrical socket which has an end
wall to which torque may be applied, such as would be
with a torque socket wrench, and an open end opposite the
end wall. The cylindrical socket is adapted to snugly
fit over and encapsulate the head of the cap screw and
the inner surfaces of the cylindrical socket are able to
contact the head of the screw. In addition, the socket
driver tool comprises a hexagonal key portion,
corresponding to the hexagonal recess in the screw, which
is concentric with and extends from the end wall within
and in coaxial relationship with the cylindrical socket
so that it fits within and cooperates with the central
hexagonal recess in the screw head when the cylindrical
socket is placed over the head of the screw.
In accordance with another embodiment of the
invention there is provided a socket driver tool for cap
screws similar to that above except that the socket will
receive and drive a replaceable hexagonal key insert.
In accordance with a further embodiment of the
invention there is provided a socket driver tool for cap
screws similar to that above except that the socket will
provide additional engagement to the head of the screw by
scoring the outer surfaces thereof.
Brief Description of the Drawings
For a better understanding of the nature and objects
of the present invention reference may be had by way of
example to the accompanying diagrammatic drawings, in
which:
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GECAN 3064
Figure 1, is a view of a cap screw with a hexagonal
key aligned with the hexagonal recess thereof;
Figure 2, is a view of the socket driver tool of the
present invention;
Figure 3, is a cutaway view of the socket of Figure
2 showing the placement of the cap screw within the
socket;
Figure 4, is a view of an alternate embodiment of
the present invention, including a cylindrical socket and
a replaceable hexagonal key insert; and
Figure 5, is a view of an modification of the socket
of Figure 4 wherein the hexagonal key is separated from
the base of the insert;
Figure 6, is a view of an alternate embodiment of
the present invention including a cylindrical socket with
splines with cutting edges for scoring the surface of the
cap screw head and a replaceable hexagonal key insert.
Des¢ription of the Preferred Embodiment
In Figure 1, a cap screw 1, such as would be
commonly used as a structural fastener characterized by a
head 2 having a central hexagonally shaped recess 3
therein, is illustrated. Cap screws are normally removed
by the action of a hexagonal key 18. To remove the cap
screw 1, the hexagonal key 18 is inserted into the recess
3 of the screw 1 and twisted in the proper direction.
Referring to Figure 2, there is shown a socket
driver tool 10 for cap screws. The socket driver tool 10
comprises a hollow cylindrical socket 12 which has an end
wall 14 and an open end 13, opposite the end wall 14.
The open end 13 allows for the socket to be placed over
the head of the screw. The end wall 14 is adapted for
connection to a standard socket driver (not shown). The
connection is of the kind commonly known in the art for
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GECAN 3064
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torque sources such as ratchet handles or pneumatic
wrenches. Extending from the end wall 14 and concentric
with the cylindrical socket 12 is a hexagonal key portion
18, corresponding to the hexagonal recess in the cap
screw. In Figure 3 it can be seen that the hexagonal key
portion 18 extends from the end wall 14 so as to fit into
the recess 3 in the screw when the cylindrical socket 12
is placed over the head of the cap screw 2. When the
socket is placed over the head of the cap screw 2 the
cylindrical socket 12 fits snugly over and encapsulates
the head 2.
As will be understood by those knowledgeable in the
art, when sockets are rotated, there will often be a
degree of misalignment of the socket to the head of the
screw. Oftentimes,, when using traditional hexagonal key
sockets misalignment of the key with the cap screw head
leads to stripping of the head. However, referring again
to Figure 3, the socket of the present invention fits
snugly over the head of the screw 2 so that misalignment
is next to impossible. However, when there is any
misalignment the inner portions 16 of the cylindrical
socket 12 make contact with the head 2. When torque is
applied, this contact translates into frictional
engagement of the socket which acts positively to remove
the screw. The contact which occurs is not
point-contact, rather substantial surface contact.
Removal of the screw becomes a combination of the action
of the hexagonal key 18 on the recess 3 in the head 2 and
the action of the cylindrical socket 12 on the head 2 of
the screw.
The problems associated with misalignment also often
lead to a deformation of the wall 4 surrounding the
recess 3. In some cases, the wall 4 will break away from
the head 2. This problem is prevented using the socket
of the present invention. The cylindrical socket 12 of
the socket acts to support the walls 4 of the head
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GECAN 3064
--7--
surrounding the recess 3 when the hexagonal key 18 is
acting inside the recess 3. In fact any elastic
deformation of the cap screw head occurring during the
application of torque acts to briny the head and
cylindrical socket into greater frictional engagement.
This also acts in the removal of the screw.
This socket has been found to remove cap screws very
efficiently, including those screws which are seized in
the work. Where the weak part of the screw, using
traditional removal means, would be the head, the weakest
part of the screw, using the socket of the present
invention, has been found to be the threaded portion of
the screw just below the head.
Referring back to Figure 2, to enhance the
frictional action of the socket 12 during removal of cap
screws, the inner surfaces 16 of the cylindrical socket
12 can be modified to have a rough finish. The rough
finish will act to further engage the head of the screw,
when the head of the screw makes contact with the inner
surfaces 16 of the cylindrical socket 12. Preferably the
rough finish is in the form of striations 17 running from
the open end 13 to the end wall 14 that will immediately
engage the head of the screw as it is inserted into the
socket 10.
Referring to Figure 4, an alternate embodiment of
the socket driver tool 19 for cap screws is shown. The
socket driver tool comprises two separate parts: a hollow
cylindrical socket 12 similar to that described herein
before, additionally having a recess 22 of predetermined
shape in the end wall 14 of the cylindrical socket to
receive and drive a replaceable insert 25, which is
inserted into the recess 22 of the cylindrical socket 12.
The insert 25 itself comprises a base 26, which snugly
fits into the recess 22 and a hexagonal key portion 27
extending from the base 26, which corresponds to the
hexagonal recess of the screw. The shape of the recess
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GECAN 3064
--8--
22 of the cylindrical socket 12 is selected to ensure
that the insert 25 will not move or rotate within the
recess 22 and therefor will remain in a single
orientation when the insert is driven by the socket 19.
Preferably the recess 22 of the cylindrical socket will
be selected to be a shape which will accept a hexagonal
insert (as shown). This shape is known by those skilled
in the art. The hexagonal key portion 27 extends from
the base 26 in coaxial relationship with the socket to
allow it to fit within and cooperate with the central
hexagonally shaped recess in the head of the screw when
the socket is assembled and used. That is when the
insert is placed within the recess of the cylindrical
socket and the cylindrical socket is placed over the head
of the screw. This is substantially the same as the
socket of Figure 3.
To enhance the use of the present socket 19 the
insert 25 is held within the recess 22 by means of a pin
29 which is inserted through a bore 28 in a side wall 23
of the recess 22 into a indentation 30 in the base 26 of
the insert 25. The bore 28 corresponds to the size of
the pin 29 while the indentation 30 is a small cavity in
the base 26 of the insert 25. The pin 29 is inserted
when the bore 28 and indentation 30 are lined up. To
remove the insert 25, the pin 29 is simply withdrawn from
the bore 28.
Alternatively, the insert could be held within the
recess by means of a D-dent pin on the base of the insert
(not shown), which cooperates with a bore through a side
wall of the recess. The bore is much the same as that
bore 28 shown in Figure 4. The insert is placed into the
recess by aligning the pin with the bore in the recess
and forcing the insert into the recess. When the insert
is in place, the pin extends into the bore holding the
insert securely in the recess. The insert is removed by
inserting a suitable object into the bore to force the
2~710~
GECAN 3064
_g_
pin into a retracted position, whil~e at the same time
pulling the insert out of the recess. The action of a
D-dent pin is known to those skilled in the art.
To enhance the frictional action provided by the
cylindrical socket 12 of the socket of the present
embodiment 19, the inner surfaces 16 of the cylindrical
socket 12 can be modified to define a roughened finish,
as shown in Figure 4. The roughened finish is as
described herein before and is preferably in the form of
striations (as shown) running from the open end 13 to the
recess 22 that will engage the head of the screw as it is
inserted into the socket.
It is known that, under continuous use, the
hexagonal key sockets will wear down and replacement will
be required. The hexagonal key portion of the present
invention will also wear down over time and need
replacing. The embodiment of the present invention
having a separate hexagonal key insert allows the simple
replacement of the insert rather than the replacement of
the entire socket. This results in a reduction in
replacement costs.
Cap screws are commonly available having a common
sized central hexagonal recess but in a wide variety of
external head diameters. The cylindrical socket of the
driver tool of the present invention can be produced in a
range of diameters corresponding to the external head
diameters. These sockets could then be marketed as a
set. To reduce the weight of the set, the two part
sockets could be produced with a common shared hexagonal
key insert. In this way a set of sockets could be
produced which can be used on a variety of cap screws to
control costs.
With reference to Figure 5, a modification of the
insert of the socket of Figure 4 is shown where the
hexagonal key 50 is separated from base 42. During use
the replaceable hexagonal key 50 is securely held within
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GECAN 3064
--10--
the base 42. The base 42, as herein before described,
fits snugly into and is driven by the recess 22 in the
end wall 14 of the cylindrical socket 12 and remains in a
single orientation therein. A central portion of the
base 42 has been modified to define a recess 44 for
accepting the replaceable hexagonal key 50. The
replaceable hexagonal key portion 50 is comprised of a
first end 52, adapted to conform to, be held within and
be driven by the recess 44 in the base 42 and a second
end 54, opposite the first end 52, which conforms to the
central hexagonal recess in the head of the cap screw.
The recess 44 of the base 42 is preferably made to be
square (as shown) and the end of the key 52 which fits
within this recess 44 conforms to the square shape (as
shown). When the key 50 is held within the recess 44 in
the base 42, the opposite end 54 extends out from the
base 42 in coaxial relationship with the cylindrical
socket 12. In this way the hexagonal key portion 50 fits
within and cooperates with the recess in the head of the
screw when the socket is assembled and used. That is,
when the hexagonal key is fitted into the base, the base
is placed into the cylindrical socket and the socket is
placed over the head of the screw. This is substantially
the same as the socket arrangement of Figure 3.
The use of the base 42 and replaceable hexagonal key
50 can be enhanced by a similar pin arrangement as that
described in regards to the two piece socket (Figure 4)
with obvious modifications (not shown). The pin must
pass through bores in both the recess 22 of the end wall
of the socket and the base 42 into an indentation in the
end 52 of the replaceable hexagonal key 50 that fits
within the recess 44 of the base. The use of D-dent pins
in this embodiment is also possible (shown in Figure 5).
In this case two D-dent pins offset to each other are
required. One of the pin/bore arrangements 56, 58 acts
between the base 42 and the recess 22 and the other
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GECAN 3064
--11--
pin/bore arrangement 60, 62 acts between the key 50 and
the base 42.
The benefits of using the socket with the
replaceable insert are only further enhanced by the
socket with the two piece insert.
Referring to Figure 6, an alternate embodiment of
the socket driver tool for cap screws is shown. The
socket driver tool comprises three parts: a hollow
cylindrical socket 12 having a recess 22 in the end wall
similar to that described herein before in regards to the
embodiment of Figure 4, additionally having splines 66
disposed about the inner surfaces 16 of the socket. The
splines extend from the open end 13 of the socket to the
recess 22 in coaxial relationship with the socket 12; a
replaceable insert 25 in accordance with that insert 25
described in regards to Figure 4; and a spring means 74
acting between the end wall 14 of the socket 12 and the
insert 25.
The socket of the present embodiment acts to provide
enhanced engagement of the head of the cap screw during
removal. This is accomplished by the action of the
splines 66. The splines 66 are machined to define
cutting edges 69 adjacent the open end 13 which will
score the head of the screw when the socket is placed
over the head to form grooves thereon (not shown). The
splines 66 slide into the grooves formed on the head of
the screw as the screw is forced into the socket 12. In
this way the socket firmly engages the screw to help in
the removal of the screw when torque is applied. To form
the grooves the open end of the cylindrical socket is
aligned with the head of the cap screw and forced over
the head of the cap screw using a suitable instrument.
This will preferably be carried out by tapping the
aligned socket with a hammer.
20S71 ~
GECAN 3064
-12-
The spring device 74 is located between the end wall
14 of the cylindrical socket 12 and the insert 25. The
spring device 74 acts to hold the insert 25 toward the
open end 13 of the cylindrical socket 12 when the socket
is not in use. The spring 74 also allows the insert 25
to be pushed toward the end wall 14 of the socket 12 as
the socket is placed over the head of the screw. The
insert 25 must be held toward the open end 13 so that the
hexagonal key portion 27 of the insert 25 can be aligned
with the hexagonal recess of the screw before the socket
12 is forced over the head of the screw. The spring 74
ensures that the hexagonal key portion 27 of the insert
25 remains in the recess of the screw regardless of how
far the screw is forced into the socket.
It will be appreciated that the recess 22 in the end
wall 14 of the socket 12 which accepts the insert 25 will
have to be extended up the inner surfaces 16 of the
cylindrical socket 12 so that the insert 25 can move in a
coaxial direction within the socket 12 and be driven by
the socket 12 at any point along the inner surfaces 16.
Further, the splines 66 have to be oriented within the
cylindrical socket 12 to correspond with the shape of the
recess 22 so that the insert 25 can move freely in
coaxial relationship with the socket 12 and the insert 25
can be removed from the socket 12.
To enhance the use of this socket the insert 25 is
held within the socket 12. The insert may be held by
means of a D-dent pin 76 on the base 26 of the insert 25,
which cooperates with a slot 78 through a wall 23 of the
recess 22. The slot 78 is of adequate length to allow
the pin 76 to move up and down as the insert 25 moves
coaxially in the socket 12. The insert 25 is placed into
the recess 22 by aligning the pin 76 with the slot 78 and
forcing the insert 25 into the recess 22 against the
spring means 74. When the insert 25 is in place the pin
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G~CAN 3064
-13-
76 extends into the slot 78 holding the insert 25
securely in the recess 22.
The socket of the present embodiment has been found
to remove seized cap screws very efficiently. The action
of the splines alone, without the use of the insert, can
also used to remove cap screws.
