Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
This invention relates generally to work piece holders,
and more particularly, to improved clamping arrangements used in
conjunction with clamping screws.
Prior art work piece holders were equipped with tiltable
work engaging elements (See for example, U.S. Patent No. 2,649,123)
The tiltable element cooperated with a clamp shoe to extend the
clamping forces to surfaces having diversified angles. The clamp
shoe was threaded and locked onto the clamp screw so that turning
the screw in a fixture, for example, tightened or loosened the clamp.
The shoe terminated in a spheroidal element. The tiltable element
had a spherical socket spun aroung the screw end of the spheroid to
lock the tiltable element in place while still enabling the desired
tilt. The tilt was naturally limited by the periphery of the spun
over portion of the element. Instead of attaching "clamp shoes" to
screw elements, work piece holders utilize screw elements that have
socket integral thereto. Truncated sphere placed in the sockets
serve as the tiltable work engaging elements. These ball clamps are
less expensive to manufacture and more efficient to use than the
prior art holders, such as are disclosed in U.S. Patent No. 2,649,123.
A problem with these ball clamps is that the ball is
totally free to rotate within the socket. Often the truncated por-
tion of the sphere, which is the work engaging surface, may rotate
leaving an arcuate surface to engage the work piece. The arcuate
surface is most likely to move the work piece than the flat surface.
Another problem caused by the freely rotating truncated
sphere is that it may enable the sphere to work loose and fall
from the so`cket. The benefit of the tool holding ball clamp is
that no impressions or marks are made on the tool shanks or other
work pieces being held. If a portion of the flat is within the
socket, then the rim of the socket will leave a mark. Thus, can-
celling the benefit of the ball clamp.
Another problem resulting from a freely rotating ball
within a socket is that when the ball or truncated sphere rotates
so that the angle between the surface being held and the longitudinal
axis of the screw is less than approximately 75 degrees, the clamp
- 2 - ~
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tends to cause transverse forces to be applied to screw body.
Accordingly, an object of the present invention is to
provide new and improved work piece clamps using a socketed screw
member with a truncated work piece engaging ball or sphere held
within the socket.
A related object of the present invention is to provide
improved ball clamps wherein the sphere is truncated to provide
parallel flat surfaces. One flat surface is used as the work
pieces engaging surface. A protrusion in the socket cooperates
with the other flat surface on the sphere within the socket to
limit the rotation of the sphere.
Yet another object of the present invention is to provide
protrusion means on the inner pole of,the truncated sphere having
a single flat surface. Depression means at the pole of the socket
receives the protrusion and limits the rotation of the truncated
sphere within the socket.
Yet another object of the present invention is to provide
improved ball clamps wherein the truncated sphere has a protrusion
and the socket has a receptacle for the protrusion to limit the
rotation of the sphere within the socket.
A preferred embodiment of the invention comprises a '~
threaded member having a socket at one end. A sphere which is
truncated past its equator so that it's larger than a hemisphere is
locked within the socket by spinning the outer periphery of the
socket. The first truncated section provides a flat surface for
engaging the work piece being clamped. A polar portion of the
sphere juxtaposed to the innermost section of the socket is also
truncated providing a second flat surface that is substantially
parallel to the bottom of the external-most portion of the truncated
sphere. A protrusion in the socket limits the rotation of the
sphere within the socket to approximately 15 in any direction.
The above mentioned an other objects and features of
the invention will become more apparent from the description of
the apparatus in the following specification, taken in conjunction
with the accompanying drawings, in which:
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Fig. 1 is a sectional view of the ball clamp wherein the
rotation of the ball used is limited;
Fig. 2 is a sectional view of the ball clamp showing the
ball claim of Fig. 1 used to clamp a work piece; and
Figs. 3, 4 and 5 are additional embodiments of the inven-
tive ball clamp.
In Fig. 1 the improved ball clamp assembly is generally
shown at 11. The sectional view shows the threaded screw member
12 having a socket 13 and threads 14. The screw member could be
a stud or a machine screw used in clamping or holding tool parts
in place. In addition set screw devices could use the ball and
socket arrangement featured herein.
The spheroid or ball 16 is shown set into the socket. It
has a portion thereof truncated from the body, however. The remain-
ing truncated sphere is larger than a hemisphere. The socket 13 has
a protrusion 17 shown at the polar portion or in this case the bottom-
most portion of the socket. At the inner pole of the ball, as shown
in Fig. 1, is a second truncated section 18. The protrusion 17
is abutted by truncated section 18, when the ball rotates in any
direction. The degree of rotation, therefore, is controlled by the
size of the protursion and angular displacement from the vertical
of the sides of the protrusion, such as side 20. Practically, the
degree of rotation is limited to approximately 15.
Fig 2 shows the application of the ball clamp in holding
an angular cutting blade having an angular incline in place within
a tool holder. The ball 16 rotates to assume a position wherein
the flat section 19 of the major truncated portion of the spheroid
abuts the tool 21 holding the tool firmly within the tool holder 22.
Tightening the clamp screw 11 depresses the relatively large surface
area 19 of the hardened ball against the shank 23 of the tool 21.
The large surface area minimizes marring of the shank surface, but
nonetheless, retains the tool in place.
The flat surface 19 also gives a more reliable setting
and is more resistant to the vibratory forces often encountered
during the cutting operation with the tools.
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Fig. 3 is another embodiment of the invention. The ball
clamp is again shown by the number ll, and the ball itself is 16.
The truncated surface is 19 and the socket is 13. Instead of a
second truncated surface, at the polar section of the sphere, a
protrusion 26 is shown at the polar section of the truncated sphere.
The protrusion, it should be understood, can be at any other
section of the sphere. The socket has an extended depressed por-
tion 27 for receiving protursion 26. There is sufficient clearance
on the depression 27 to enable to protrusion 26 to move so that the
flat surface 19 of the ball can bary in positional setting by a
desired amount, such as approximately 15 in any direction.
In Fig. 4 yet another embodiment of the invention is
shown wherein the tool clamp 11 has a screw member 12, having
threads 14 and socket 13 for receiving a truncated sphere 16. A
portion of the other surface of the truncated sphere within the
socket 13 has a circumferential cavity therein 28. A corresponding
portion of the socket has a circumferential protrusion 29 justaposed
to the cavity and inserted within the cavity. There is sufficient
clearance within the cavity 28 to enable the sphere 16 to rotate
within the socket, but to be limited in that rotation to a desired
amount, such as approximately 15 in any direction.
With this type of arrangement the sphere can be a
hemisphere or even less than a hemisphere, enabling the maximiza-
tion of surface 19. Further, no spinning is required at the
bottom of the body 12. The oppositely disposed protrusion and
cavity can both be located at specific points instead of being
circumferential.
In Fig. 5 still another embodiment of the invention is
shown wherein the tool clamp 11 has a screw member 12 having
threads 14 and socket for receiving a truncated sphere 16. The
sphere is retained in the socket 13 by any well know manner, such
as by spinning a retaining shoulder 15 below the equator of the
sphere.
Means are provided for limiting the rotation of the
sphere 16 in the socket 13. More particularly, there is shown in
Fig. 5 a pin receiving aperture 26 in the socket of screw 12 and a
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slightly larger pin receiving aperture 27 in the body of the sphere.
A pin 28 is provided which extends into each of the apertures
thereby limiting the rotational movement of the sphere in the
socket.
The ifteen degree rotation, previously alluded to herein,
is shown as angle ~ in Fig. 1. The seventy-five degree rotation,
previously alluded to, is the complementary angle ~, also shown in
Fig. 1. The truncated portion 19 abuts the surface of the workpiece.
Where necessary, the ball 16 is rotated within the socket 15 to
accomplish this.
It should be understood that while the ball and socket
arrangement have been described in conjunction with a screw clamp-
ing device; nonetheless, it is believed that this invention also
applies to other types of retaining devices, such as tubular mem-
bers, plate members and the like, used not only for clamping, but
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also for functions,such as leveling pa;ds, toggle pads, or the
like.
While the principles of the invention have been described
above in connection with specific apparatus and applications, it
is to be understood that this description is made only by way of
example, and not as a limitation on the scope of the invention.
