Cutting insert

Details Cutting insert Cutting insert

2000-07-10

2003-12-30

Tsai, Henry W. H. (Department: 2183)

Cutters, for shaping

Including tool having plural alternatively usable cutting edges

C407S114000, C407S116000

Reexamination Certificate

active

06669412

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. H11-196794, filed Jul. 9, 1999. The contents of that application are incorporated herein by reference in their entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the cutting insert for intermittent cutting which is used in milling tools such as face milling cutters, end-mills and others.
2. Description of the Background
FIG. 4
is the front view of a cutting insert as one example of the conventional technology.
FIG. 5
is the cross sectional view along the X—X line of the cutting insert shown in FIG.
4
.
FIG. 6
is the central sectional view of a face milling cutter equipped with the cutting insert shown in FIG.
4
. As shown in
FIG. 4
, this cutting insert is formed in the shape of an approximately square shape (
FIG. 4
is approximately square shape) board type and has an under surface
11
which makes a taking a seat side, and an upper face
12
which counters the under surface
11
. A main cutting tooth
13
is formed in a ridge line portion which extends approximately to the neighborhood of the upper surface
12
, an approximately straight line sub cutting tooth
14
is formed between two main cutting teeth
13
,
13
by which it is formed, respectively, and the circular corner tooth
15
is formed between the main cutting tooth
13
and the sub cutting tooth
14
, and a circular corner tooth connects both of the cutting teeth
13
,
14
smoothly. A side face
16
which is formed between the under surface
11
and the upper surface
12
inclines outside towards a field
12
and forms a positive insert as shown in FIG.
5
.
The upper surface
12
is made into a rake face, and the side face
16
is made into a flank face.
Moreover, a central portion of the upper surface
12
and the under surface
11
is penetrated, and the penetrations for screw penetration is formed.
A ridge line portion which makes approximately four rounds of the upper surface
12
is given a honing (honing surface)
18
as shown in FIG.
4
and FIG.
5
. That is, an intersection ridge line portion of the honing
18
and the side face
16
make up the main cutting tooth
13
, the sub cutting tooth
14
and the corner tooth
15
. The section of this honing
18
which intersects perpendicularly with a ridge line portion may be made into a straight line, and it may extend from this honing
18
toward the outside of the cutting insert
10
to a level surface. The inclination angle (honing angle) &thgr; may be set constant.
The upper surface
12
of the cutting insert
10
consists of an upper surface inclination portion
12
A which inclined so that a honing
18
may be intersected, it may extend to the level surface towards the central portion of the cutting insert
10
and become a slope, and an upper surface level part
12
B which is connected to this upper surface inclination part
12
A, and is leveled in near the central portion of the cutting insert
10
. In addition, the connection between upper surface inclination part
12
A and the upper surface level part
12
B is smoothed.
As shown in
FIG. 6
, This cutting insert
10
is provided in a tip perimeter of a main cutter body
21
in a milling cutter
20
, for instance , and a part of work material is intermittently cut off by carrying out rotation cutting of the main cutter body
21
to the work material.
The cutting insert
10
is disposed so that the main cutting tooth
13
may project toward the perimeter side of the main cutter body
21
, and also that sub cutting tooth
14
may turn onto a down tooth of the main cutter body
21
. In case of rotation cutting of the work material by the face milling cutter
20
, main cutting is performed by the main cutting tooth
13
, and finish cutting is performed by the sub cutting tooth
14
.
Although the main cutting tooth
13
and the sub cutting tooth
14
is connected smoothly by circular corner tooth
15
in above mentioned cutting insert
10
, the problem of being easy to break out in corner tooth
15
by the shocks at the time of the instruction to which each cutting tooth
13
,
14
,
15
begin to hit to the work material at the time of cutting.
Moreover, the corner tooth
15
in a center side of rotation such as face milling cutter and end mill etc., bites the chips generated by cutting of the sub cutting tooth
14
, as the results, the finished surface is damaged, moreover, as the results of the crush the chip into above mentioned corner tooth
15
, the corner tooth
15
will be broken.
Furthermore, when the vibration of the work material propagate to the corner tooth
15
at the time of cutting, there was also a problem that the corner tooth
15
will be broken.
Also, the corner tooth
15
located toward the center of rotation in face milling cutters, end mills and others bites the chips generated by the sub cutting tooth
14
during cutting. As a result, a finished surface is damaged and the corner tooth
15
is damaged as well because of the chips crushing into it.
Furthermore, when the vibration of a work material during cutting is transmitted to the corner tooth
15
, the corner tooth
15
can break.
SUMMARY OF THE INVENTION
In view of the above, this invention aims to offer the cutting insert which is possible to increase the break resistant property of the corner portion near the intersection part of the main cutting tooth and the sub cutting tooth for cutting.
To attain the above mentioned object, a cutting insert according to this invention includes a main cutting tooth having a honing angle &agr;; a sub cutting tooth having a honing angle &bgr;; and a corner tooth connecting said main cutting tooth and said sub cutting tooth and having a honing angle &ggr;, wherein said honing angle &agr; is larger than said honing angle &bgr; and said honing angle &ggr;.
In the cutting insert mentioned above, since the honing angle over a corner edge is enlarged compared with the honing angle over the main cutting tooth and sub cutting tooth, the break resistance of the corner tooth is increased from easily breaking, therefore, the corner tooth is prevented from easily breaking from the shock exerted on when cutting begins. Since a honing angle is enlarged only against the corner tooth, the sharpness of the main cutting tooth and the sub cutting tooth is not reduced.
Furthermore, another cutting insert according to the present invention includes a corner tooth having a height from an under face which makes the seat face of the corner tooth being lower than a height of a sub cutting tooth.
Since the height from the under face of the corner tooth is lower than the height of a sub cutting tooth in the cutting insert mentioned above, a corner tooth is in a lower position than a sub cutting tooth with respect to a rotational direction of a face milling cutter, an end mill or others. Hence, when the chips generated by a sub cutting tooth during cutting drift toward the center of their rotation, the corner tooth is prevented from biting the chips by the side of a rotation center or breaking by the crash of the chips into the corner tooth.
Moreover, because there is a very small clearance between the corner tooth used for cutting and a work material, when the vibration of the work material is transmitted to the corner tooth during cutting, the corner tooth is prevented from breaking.
Furthermore, still another cutting insert according to the present invention includes the honing angle &agr; in a range of 0°<&agr;<60°, the honing angle &bgr; in a range of 0°<&bgr;<60°, and the honing angle &ggr; in a range of 5°<&ggr;<80°.
In the above mentioned cutting insert, if the honing angle &agr; of the main cutting tooth is less than 0°, the effect of forming the honing face i.e., the break resistant property of the main cutting tooth cannot be increased, and if it is 60° or more, the sharpness of the main cutting tooth is reduced.
Similarly, if the honing angle &bgr; of the sub cutting tooth is less than 0°, the break resistant

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