Description
INTERNAL GROOVE INSERT AND TOOL HOLDER
THEREFOR
Technical Field
[1] The present invention relates to an internal groove insert for forming a groove inside
a bore of a workpiece and a tool holder for mounting the same.
Background Art
[2] As shown in Fig. 8, a conventional internal groove insert, which is mounted to a tool
holder, is used to form a groove inside a bore of a workpiece. As further shown in Fig.
8, the conventional internal groove insert 100 includes a main body 110 and two pro
jections 121, 122 that project from two adjacent lateral surfaces of the main body 110.
Thus, the insert 100 generally has an L-shape. Cutting edges 124, 126 for performing a
cutting operation are formed at the end portions of the two projections 121, 122. The
insert 100 having such a shape is mounted within a pocket formed at the end portion of
a tool holder 130, wherein the pocket has a shape corresponding to the insert 100 so
that it can accommodate the insert 100 therein. That is, the pocket is provided with a
recess 132, which corresponds to and receives one of the projections of the insert 100.
As the tool holder 130 in which the insert 100 is mounted rotates about a rotation axis
134, the cutting edge 124 projecting outwardly from the peripheral surface of the tool
holder 130 cuts the interior surface of the bore of the workpiece 136 such that a groove
can be formed.
[3] Fig. 9 shows a conventional indexable cutting insert 200, which is capable of both
turning and drilling. As shown in Fig. 9, the cutting insert 200 includes a top surface
210, a lower surface 202 and four lateral surfaces 203 extending between the top
surface 201 and the lower surface 202 so that the insert 200 has a generally rectangular
shape. The lateral surface 203 of the cutting insert 200 is configured to be inclined by
an obtuse angle with respect to the lower surface 202 so as to define a positive
clearance angle. As such, when performing turning and drilling operations, it can avoid
an interference with a workpiece. Fig. 10 is a side view of the end portion of a tool
holder having the cutting insert of Fig. 9. As shown in Fig. 10, a lateral wall 212 of a
pocket of the tool holder 210, in which the insert 200 is mounted, is inclined by an
obtuse angle with respect to the bottom surface 214 of the pocket. The obtuse angle
between the lateral wall 212 and the bottom surface 214 is same as the angle a
between the lateral surface 203 and the lower surface 202 of the cutting insert 200.
[4] As such, the internal groove insert and the indexable cutting insert for turning and
drilling have different shapes since their operating conditions differ. Further, a pocket
of a tool holder is configured to have a shape, which may receive its corresponding
insert. Thus, the conventional technique has a problem in that the tool holder for the
conventional indexable cutting insert for turning and drilling cannot be used for an
internal groove insert. Moreover, a separate tool holder, which is different from the
tool holder of the conventional indexable insert for turning and drilling, is required for
the internal groove insert.
Disclosure of Invention
Technical Problem
[5] The present invention is directed to solving such a problem of the conventional
technique. The object of the present invention is to provide an internal groove insert
that can be used in a tool holder, which is also compatible with a cutting insert for
turning and drilling. Another object of the present invention is to provide a tool holder,
which can be used for both the internal groove insert of the present invention and the
conventional cutting insert for turning and drilling.
[6] Further, another object of the present invention is to provide an internal groove
insert, which can minimize a stress imparted to the clamping screw for mounting the
insert, and which can be easily manufactured without using any difficult manufacturing
technique.
Technical Solution
[7] To achieve these objects, an internal groove insert according to one embodiment of
the present invention comprises: a rectangular main body comprising a top surface, a
lower surface, first to fourth lateral surfaces which are orderly formed in the counter
clockwise from the top view and a clamping hole passing from the center of the top
surface to the center of the lower surface; and first and second projections each
projecting from the adjacent first and second lateral surfaces. The first projection has a
first cutting edge thereon at the side of the top surface of the main body and the second
projection has a second cutting edge thereon at the side of the lower surface of the
main body. The first and fourth lateral surfaces are inclined by an obtuse angle with
respect to the top surface of the main body, while the second and third lateral surfaces
are inclined by an acute angle with respect to the top surface of the main body. The
central axis of the clamping hole is inclined so that the axis is parallel to the edge
where the first and fourth lateral surfaces meet. The first projection has chip breakers
thereon at the side of the top surface of the main body, while the second projection has
chip breakers on its surface at the side of the lower surface of the main body. This
insert is formed by an inclined pressing molding.
[8] A tool holder according to one embodiment of the present invention comprises a
pocket, which can receive the internal groove insert of the present invention. The
pocket comprises a bottom surface, as well as first and second lateral walls that are
adjacent to each other and inclined by an obtuse angle with respect to the bottom
surface. The obtuse angle, which the first and second lateral walls of the pocket form
with respect to the bottom surface of the pocket, is the same as the obtuse angle that
the first and fourth lateral surfaces of the insert form with respect to the top surface of
the insert. A recess for receiving one of the projections of the internal groove insert is
formed on the first lateral wall. A screw hole, into which a clamping screw for
mounting the insert is fastened, is formed on the bottom surface of the pocket. The
central axis of the screw hole is formed to be parallel to the edge where the first and
second lateral walls of the pocket meet.
Advantageous Effects
[9] According to the present invention, the internal groove insert can be used in a tool
holder, which is also compatible with a cutting insert for turning and drilling. The tool
holder of the present invention, which has the pocket for receiving the internal groove
insert of the present invention, can also receive the cutting insert for turning and
drilling. Thus, it is not necessary to separately use two types of tool holders for the
internal groove insert and the cutting insert for turning and drilling.
[10] Further, the internal groove insert of the present invention can minimize the stress
imparted to the clamping screw for mounting the insert. The internal groove insert can
be easily manufactured without using any difficult manufacturing technique.
Brief Description of Drawings
[11] Fig. 1 is a perspective view of the internal groove insert according to the present
invention.
[12] Fig. 2 is a top view and a side view of the insert shown in Fig. 1.
[13] Fig. 3 shows that the insert of Fig. 1 is mounted on the tool holder.
[14] Fig. 4 is a sectional view of the insert taken along the line A-A shown in Fig. 2.
[15] Fig. 5 shows that the cutting insert for turning and drilling and the internal groove
insert shown Fig. 1 are mounted in identical tool holders.
[16] Fig. 6 is a sectional view of an apparatus for manufacturing the insert shown in Fig.
1.
[17] Fig. 7 is a top view of the apparatus shown in Fig. 6.
[18] Fig. 8 shows a conventional internal groove insert.
[19] Fig. 9 shows a cutting insert, which is capable of both turning and drilling.
[20] Fig. 10 shows that the cutting insert of Fig. 9 is mounted in a tool holder.
Mode for the Invention
[21] Referring to the embodiments illustrated in drawings, an internal groove insert
according to the present invention and a tool holder in which such an insert is mounted
are described below.
[22] Fig. 1 is a perspective view of an internal groove insert according to the present
invention. Fig. 2 shows a top view (left side) and a side view (right side) of the internal
groove insert shown in Fig. 1. As illustrated in Figs. 1 and 2, the insert comprises a
rectangular main body 10. The main body 10 includes a top surface 11, a lower surface
12, first to fourth lateral surfaces 13-16 extending between the top surface 11 and the
lower surface 12 and a clamping hole 17 which passes through from a center of the top
surface 11 to a center of the lower surface 12. The first to fourth lateral surfaces 13-16
are orderly formed in the counter-clockwise direction when seen from the top surface
11 of the main body 10. A first projection 2 1 and a second projection 22 project from
the adjacent first and second lateral surfaces 13, 14, respectively.
[23] The first projection 2 1 has a first cutting edge 24 on its end portion at the side of the
top surface 11 of the main body 10. The second projection 22 has a second cutting
edge 25 on its end portion at the side of the lower surface 12 of the main body 10. As
illustrated in Fig. 3, when the lower surface 12 of the insert is mounted in contact with
a bottom surface 33 of a pocket of a tool holder 3, the first cutting edge 24 is used for
internal grooving operation. On the contrary, when the top surface 11 of the insert is
mounted in contact with the bottom surface 33 of the pocket of the tool holder 3, the
second cutting edge 25 is used for internal grooving operation. As such, two cutting
edges 24, 25 are formed in opposite directions to each other. Thus, a cutting edge,
which is not involved in the cutting operation, is prevented from being damaged by
cutting chips generated during the cutting operation. In particular, when the first
cutting edge 24 is in use for the cutting operation, the second cutting edge 25 is
prevented from being damaged by the cutting chips generated during the cutting
operation. Further, when the second cutting edge 25 is in use for the cutting operation,
the first cutting edge 24 is prevented from being damaged by the cutting chips.
[24] As illustrated in Fig. 2, the first projection 2 1 has chip breakers 26 at the side of the
top surface 11 of the main body 10 in order to facilitate the discharge of chips
generated from the cutting edge 24 during the cutting operation. Although it is not i l
lustrated, the second projection 22 also has chip breakers at the side of the lower
surface 12 of the main body 10. The first to fourth lateral surfaces 13-16 of the insert 1
are inclined with respect to the top and lower surfaces 11, 12. As illustrated in Fig. 2,
the first lateral surface 13 is inclined by an obtuse angle with respect to the top surface
11 of the main body 10, while the third lateral surface 15 is inclined by an acute angle
with respect to the top surface 11 of the main body. The fourth lateral surface 16 is
inclined by an obtuse angle with respect to the top surface 11 of the main body 10,
while the second lateral surface 14 is inclined by an acute angle with respect to the top
surface 11 of the main body.
[25] Fig. 3 shows that the internal groove insert of Fig. 1 is mounted in a tool holder. The
insert 1 is mounted within the pocket of the tool holder 3. An inner side of the pocket
has a shape corresponding to an outer shape of the insert 1. The pocket of the tool
holder 3 comprises a bottom surface 33 and first and second lateral walls 31, 32, which
are adjacent to each other and inclined by an obtuse angle with respect to the bottom
surface 33. The obtuse angle defined between the first and second lateral walls 31, 32
and the bottom surface 33 is the same as the obtuse angle defined between the first and
fourth lateral surfaces 13, 16 and the top surface 11 of the insert 1. A recess 34 is
formed in the first lateral wall 3 1 for receiving the projection of the insert 1. In Fig. 3,
the lower surface 12 of the insert 1 is in contact with the bottom surface 33 of the
pocket, while the second and third lateral surfaces 14, 15 abut the first and second
lateral walls 31, 32, respectively. The second projection 22 of the insert 1 is received
within the recess 34 of the pocket. As such, since the first and fourth lateral surfaces
13, 16 of the insert 1 are inclined to define an obtuse angle with respect to the top
surface 11 of the main body 10 while the second and third lateral surfaces 14, 15 are
inclined to define an acute angle with respect to the top surface 11 of the main body
10, the first and second lateral walls 31, 32 of the pocket of the tool holder 3 are
inclined to define an obtuse angle with respect to the bottom surface 33, thereby corre
sponding to the shape of the insert 1. Thus, as illustrated in Fig. 5, the pocket of the
tool holder in which the insert 1 is received can also receive the indexable insert 200
for the turning and drilling operations whose lateral surfaces 202 are inclined by an
obtuse angle with respect to the lower surface 201.
[26] Fig. 4 is a sectional view taken along line A-A of Fig. 2. As illustrated in Fig. 4, a
central axis 18 of the clamping hole 17 is inclined with respect to the lower surface 12
of the main body 10. The inclined angle of the central axis 18 is same as the inclined of
the edge with respect to the lower surface 12, the edge being defined by an intersection
of the first lateral surface 13 and the fourth lateral surface 16. That is, the central axis
18 is parallel to the edge where the first and fourth lateral surfaces 13, 16 intersect.
Corresponding to this, a screw hole (not illustrated), in which a clamping screw is
fastened, is defined on the bottom surface 33 of the tool holder 3. The central axis of
the screw hole is inclined with respect to the bottom surface 33 by the same angle as
the central axis 18 of the clamping hole 17. That is, the central axis of the screw hole is
parallel to an edge where the first and second lateral walls 31, 32 of the pocket meet.
[27] As such, since the clamping hole 17, into which the clamping screw is inserted, is
inclined with respect to the top and lower surfaces 11, 12 of the insert 1, the clamping
screw is fastened to be inclined with respect to the bottom surface 33 of the pocket of
the tool holder 3. Thus, a cross-sectional area (S in Fig. 4) of the clamping screw in the
abutting surface is larger compared to the case where a clamping screw is perpendicularly
fastened into a bottom surface. Thus, stress imparted to the clamping screw is
reduced and the insert can be fastened more securely.
[28] Further, since the clamping hole 17 is inclined with respect to the edge where the
first and fourth lateral surfaces 13, 16 meet, the insert 1 can be easily manufactured by
an inclined pressing molding method without using any difficult manufacturing
technique. A method of manufacturing the insert according to the present invention by
the inclined pressing molding method is explained below.
[29] The insert 1 according to the present invention includes the first to fourth lateral
surfaces 13-16, which are inclined with respect to the top and lower surfaces 11, 12.
When the top and lower surfaces of the insert art not perpendicular to the lateral
surfaces of the insert, a die whose bottom surface and lateral surfaces are not per
pendicular to each other (so-called positive die) is used. However, such a positive die
requires a difficult pressing technique since the bottom surface and the lateral surfaces
of the die are inclined with respect to each other.
[30] Fig. 6 is a sectional view of an inclined die used for an inclined pressing molding
method. As illustrated in Fig. 6, the inclined die 40 includes a bottom surface 41,
lateral surfaces 42 which are perpendicular to the bottom surface 41, a top surface 43
which is inclined with respect to the lateral surfaces 42 and a through hole 44 which
passes through from the top surface 43 of the inclined die 40 to the bottom surface 4 1
of the inclined die 40 and is perpendicular to the bottom surface 41. As illustrated in
Fig. 7, the through hole 44 has an L-shaped section as the shape of the insert 1 when
seen, from the top view. A process of manufacturing the insert by the inclined pressing
molding method is as follows: a lower punch 54 and a core rod 58 rise from the space
under the through hole 44 of the inclined die 40; metal powder for forming the insert is
poured; and an upper punch 50 is inserted from the space over the through hole 44 of
the inclined die 40. An outer shape of the insert 1 is formed by the space defined by the
inner surfaces of the through hole 44 of the inclined die 40, a pressing surface 52 of the
upper punch 50 and a pressing surface 56 of the lower punch 54. The clamping hole 17
is formed by the core rod 58. After the metal powder is compressed and sintered, it is
ground to form the complete insert. According to the present invention, since the
clamping hole 17 is inclined to be parallel to an edge where the first and fourth lateral
surfaces 13, 16 meet, it can be formed by the core rod 58 which is perpendicular to the
bottom surface 4 1 of the inclined die 40. Thus, it is not necessary to use a positive die,
which requires a difficult pressing technique. As such, productivity can be greatly
improved through manufacturing the insert by the inclined pressing molding.
WO 2011/083887 PCT/KR2010/000787
Claims
[1] An internal groove insert, comprising:
a rectangular main body having a top surface, a lower surface, first to fourth
lateral surfaces formed in a counter-clockwise direction when seen from the top
view;
a clamping hole passing from said top surface to said lower surface; and
first and second projections each projecting from the adjacent first and second
lateral surfaces;
wherein said first projection has a first cutting edge on its end portion at a side of
the top surface of the main body, and said second projection has a second cutting
edge on its end portion at a side of the lower surface of the main body;
wherein said first and fourth lateral surfaces are inclined by an obtuse angle with
respect to the top surface of the main body, said second and third lateral surfaces
being inclined by an acute angle with respect to the top surface of the main body;
and
wherein the central axis of said clamping hole is formed to be parallel to an edge
where the first and fourth lateral surfaces meet.
[2] The internal groove insert of Claim 1, wherein said first projection has chip
breakers on its surface at the side of the top surface of said main body, and
wherein said second projection has chip breakers on its surface at the side of the
lower surface of said main body.
[3] The internal groove insert of Claim 1 or 2, wherein said insert is formed by an
inclined pressing molding.
[4] A tool holder comprising a pocket in which the internal groove insert of Claim 1
or 2 is mounted, wherein:
said pocket comprises a bottom surface and first and second lateral walls
adjacent to each other and being inclined by an obtuse angle with respect to said
bottom surface;
the obtuse angle formed by said first and second lateral walls with respect to said
bottom surface is identical to the obtuse angle formed by said first and fourth
lateral surfaces of said insert with respect to the top surface of the main body;
and
a recess for receiving the projection of said insert is formed on said first lateral
wall.
[5] The tool holder of Claim 4, wherein:
a screw hole into which a clamping screw for mounting said insert is fastened is
formed on said bottom surface; and
the central axis of said screw hole is formed to be parallel to the edge where the
first and second lateral walls of said pocket meet.