Note: Descriptions are shown in the official language in which they were submitted.
4;3;~
BACKGROUND OF l~lE INVENTION
The present invention concerns clamping mechanisms for
holding cutting inserts on toolholders during material removal
operations.
A toolholder usually is comprised of a shank for attachment
to a machine and a pocket on one end for seating of a cutting
insert~ usually an indexable cutting insert. The insert on the
toolholder must always be firmly and positively located in order
to provide as consistent a cut in the work material as possible.
In some cases, the clamping mechanism can take the form of
an external clamp that is located on top of the toolholder and
extends over the top of the insert ~ provide sufficient clamping
force to hold the insert in the pocket.
Sometimes, however, external clamping mechanisms are not
satisfactory because of the smallness in size of the insert or
because of the amount of work space allowed for specific cuts.
When the external top clamps are not satisfactory, usually
the cutting insert can be made with an axial hole through its
center and placed over a rotatable pin element that is held by
the toolholder. When using a pin, the insert is usually held
firmly between the head of the pin and a side wall of the pocket
of a toolholder.
Various mechanisms for providing the pin with enough
force to hold the insert in the toolholder have been devised, a
representative sampling of which may be had by reviewing United
States Patent No. 3,525,136 to Crosby; United States Patent No.
3,787,941 to Novkov; United States Patent No. 3,491,421 to
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Holloway; United States Patent No. 3,488,422 to Jones; an~
United States Patent Nos. 3,341,920 and 3,341,923 ta Kelm~ In
addition, attention should be directed to United States Patent
Nos. 3,946,473; 3,6237201 and 3,310,859 for similar types of
pin holding mechanisms.
While some of the above-mentioned clamping mechanisms have
worked adequately, there is always a need to improve upon the
efficiency and reliability of the clamping mechanism.
It is an object of the present invention to provide a
stronger pin clamping mechanism.
It is a further object of the present invention to provide
a more positive and faster acting pin clamping element.
BRIEF SUMMARY OF THE INVENTION
According to the present invention, a cutting tool is
furnished for holding a cutting insert in an insert pocket during
working operations. The cutting insert typically has an axial
hole therethrough that is adapted for engagement with the head of
a pin member.
The cutting tool is comprised of a cutter body having a
portion adapted for attachment to a support member that may be
either stationary or rotational in nature. On another part of
the cutter body, an insert seat is provided having at least a
bottom wall and side wall so that the cutting insert may rest on
the bottom wall and be clamped between the head of the pin and
the side wall of the insert seat.
A transverse pin receiving hole is formed through the
bottom wall of the insert seat and is located so that it has
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; at least partial registration with the central axial hole in
the cutting insert.
The transverse pin receiving hole has an enlarged section
immediately below the bottom wall of the insert seat such that
an upward facing abutment shoulder is formed along the pin
receiving hole. The pin, preferably, has another end opposite
the insert engaging head that is adapted for moving engagement
with the cutter body. Preferably, the end of the pin is
; threadedly connected in the cutter body such that rotational
movement of the pin causes movement in a first and second
direction, depending upon the direction of rotation of the pin.
Attached to the pin member, and intermediate of the ends
of the pin, is an abutment shoe that may pivot upon the mid-
section of the pin. When the abutment shoe, the pin, and the
insert are all placed in the cutter body, rotation of the pin
causes the pin to move in a first direction in the hole, abutting
the shoe member against the upward face and the abutment
shoulder.
As the pin is moved further in the first direction, the
abutment shoe tilts the head of the pin toward the side wall of
the insert seat and thus firmly and positively clamps the insert
between the head of the pin and the side wall of the insert seat.
Rotation of the pin in an opposite direction causes the pin
to move in a second direction which allows the abutment shoe some
freedom of movement in the hole such that the resilient pin
straightens and the insert is then not clamped against the side
wall of the insert seat. Preferably, the pin has opposing ends
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with a reduced diameter portion between said ends adapted for
engagement with the pivotal shoe member. The pin may also have
a flanged portion intermediate of the ends for engaging a shim
member placed beneath the insert in the insert seat.
The shoe member, preferably, is formed having a somewhat
C-shaped cross section when viewed in plan such that the arms
of the C-shaped shoe fit substantially around the diameter of
the pin and is resiliently held on the pin by the arms.
The exact nature of the present invention will become more
clearly apparent upon reference to the following detailed
specification taken in connection with the accompanying drawings
~ in which:
;~ BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view of a toolholder with an
assembly view of the insert, pin and shoe member.
-~ .
Figure 2 is a cut-away side view of the clamping mechanism
according to the present invention in a clamped position.
Figure 3 is a cut-away side view of the clamping mechanism
according to the present invention in an unclamped position.
Figure 4 is a cross section in plan of the pivot shoe
member and the pin.
; Figure 5 is a side view of the pivot shoe element according
to the present invention.
-~ DETAILED DESCRIPTION OF THE INVENTION
,
Referring to the drawings somewhat more in detail, what is
shown in Figure 1 is a toolholder 10 having an insert pocket 12
in which is seated insert 14. The toolholder 10, as shown in
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Figure 1, is a stationary tool holder; however, 10 could
represent a section of a milling cutter or other type of tool
upon which indexable, replaceable inserts are supported.
As shown in Figure 1, there is a pin member 16 having an
end thereon 18 for eng~ging central hole 20 of insert 14. A
transverse hole 22 is shown formed through the bottom of the
insert pocket 12 and lower end 24 of the pin 16 is threaded so
as to engage a threaded portion of hole 22. Hole 22 has an
enlarged portion near its interséction with the insert pocket
12 into which fits pivotal shoe member 26. Pivotal shoe member
26 engages a reduced diameter portion intermediate the ends of
pin 16 and rests in the enlarged section of hole 22.
In the particular assembly shown in all of the figures, a
shim member 28 is shown fitting into the pocket 12 of the tool-
holder. Shim members may or may not be used when seating an
insert in the pocket of a toolholder; however, when so used, they
help to form a bottom wall upon which to seat insert 14.
Insert 14, typically, in most toolholders 10, will have an
insert seat comprised of at least a bottom wall and a side wall.
When shim 28 is used, the top of shim 28 will form the bottom
wall of the insert seat. If a shim is not used, then the insert
will rest upon the bottom wall of the insert pocket.
Referring now to Figure 2, what is shown therein is the
insert 14 seated upon the shim 28 and the abutting side wall 31 of
a toolholder 10 The head of the pin 18 is engaged with the
central axial hole 20. The pivot shoe member 26 is engaged on
an intermediate portion of the pin 16 and is located in an
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enlarged section 30 of the transverse hole 22 in the tool-
holder 10.
The lower end 24 of pin 16 is threadedly engaged with the
hole 22 such that rotation in one direction of pin 16 causes the
pin to move downwardly in hole 22 while rotational motion in an
opposite direction will cause the pin member 16 to move upwardly
in hole 22.
The enlarged section 30 that was formed in hole 22 has
formed an upwardly facing abutment shoulder 32 which engages the
lowermost portion of the pivot shoe 26. As shown in Figure 2,
the pin member 16 has been rotated such that the pin has advanced
downwardly in hole 22 forcing the nose of the pivot shoe 26 to
engage the upwardly facing shoulder 32 and vertical shoulder 33.
Continued downward movement of pin 16 causes the shoe
member 26 to bend the resilient pin 16 toward the side wall 31
of ~he insert seat and has thus firmly clamped the cutting
insert 14 between the head 18 of pin 16 and the side wall 31.
As shown in Figure 3, again, cutting insert 14 on toolholder
10 and pin 16 have a head portion 18 and a shim 28 forming a part
of the insert seat. The pivot shoe member 26 is still located in
: enlarged portion 30 of the hole 22; however, pin 16 has been
: rotated in one direction and has caused movement upwardly in the
; hole 22.
. Upward movement of pin 16 has relieved the abutment forces
between the upwardly facing shoulder 32 and pivot shoe 26 and the
resilient pin 16 has strengthened such that the head 18 is not in
engagement with the boundary wall of axial hole 20 on the insert.
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In this condition, the insert 14 may be freely removed and
replaced or merely indexed so as to achieve a better cutting edge.
Referring now to Figure 4, the pivot shoe is preferably
C-shaped in cross sectional plan view and engages a reduced
diameter portion intermediate the ends of 18 and 24 of pin 16.
The engagement of the shoe with the reduced diameter portion may
be seen in Figures 1 through 3.
It can be seen in these figures that the reduced diameter
intermediate section of pin 16 is of a length and a diameter
that allows itself to be loosely engageable in bore 11 of shoe
26, as shown in Figure 4. As shown in Figures 2 and 3, pin 16
is loosely engaged in bore 11 of shoe 26 such that the bottom
surface 25 of shoe 26 faces threaded end 24 of pin 16.
In Figure 4, the pivot shoe member is shown having a
C-shaped cross section in plan having arms 34 that extend around
the periphery of the reduced diameter portion of pin member 16.
By advantageously sizing the dîameter between the arms 34, one
may snap pivot member 26 on and off the reduced diameter portion
16. Both the pivot shoe member 26 and the pin member 16 are
preferably made of a tough, resilient material.
Shown in Figure 5 is the pivot shoe member 26 having a bore
formed longitudinally through one side so as to fit around the
reduced diameter of pin 16. Pivot shoe member 26 has the bore
formed so that its central axis can be in alignment with the
lo~gitudinal axis of the pin member when the pin member is mounted
in hole 22, but will not be in alignment with the longitudinal
axis as the pivot shoe member is forced to pivot in the enlarged
secton 30 of hole 22.
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As shown in Figures 4 and 5, shoe 26 has a top surface
27 having a slan~ed portion 29. A peripheral surface 23 connects
the top surface 27 to the bottom surface 25. Bore 11 communicates
between top surface 27 and bottom surface 25 and intersects
peripheral surface 23 continuously from top to bottom so as
to provide the shoe body 26 with the C-shaped configuration
observed when it is viewed in plan. Bore 11 is obliquely aligned
with planes defined by top slanted portion 29 ànd bottom surface
25. Shoe 25 further has a convex surface 17 forming the juncture
of peripheral surface 23 and bottom surface 25 in a location on
the shoe body 26 generally opposite to where bore 11 intersects
peripheral surface 23.
Modifications may be made within the scope of the appended
claims.
