Cutting insert and indexable drill
The present disclosure relates to a cutting insert and an indexable drill. The cutting insert and the indexable drill according to the present disclosure are configured such that when the cutting insert is mounted on the indexable drill, the cutting insert is easily inserted into the indexable drill at the initial time, and strong coupling force is implemented between the indexable drill and the cutting insert at a point of time at which the cutting insert is completely mounted. In addition, the cutting insert, according to the present disclosure, has excellent rigidity, when compared to cutting inserts in the related art that perform identical/similar cutting processing, since a portion, which is weak in rigidity, is provided as a thick portion.
1. A cutting insert comprising:
an insert body;
a post which is convexly formed at a lower side of the insert body and has a first central axis;
a fastening surface which is formed at a lateral side of the insert body;
a pressure receiving surface which is formed on the insert body in a direction orthogonal to the fastening surface;
a tip cutting edge which is formed at a tip portion of the insert body and subjected to cutting processing;
a lateral cutting edge which is formed at a lateral side of the insert body and subjected to cutting processing; and
an insert flute which is formed at one side of the lateral cutting edge of the insert body and guides a discharge of cutting chips,
wherein the fastening surface is provided as a surface of a cylindrical shape in which an upper radius and a lower radius are equal to each other, and a second central axis of the cylinder has a gradient with respect to the first central axis when viewed from a lateral side, and the second central axis is eccentric and has a gradient when viewed from a top side, and
wherein the pressure receiving surface is formed to be inclined so that a portion, which is directed toward the tip cutting edge, is wider with respect to the first central axis when viewed from a lateral side of the cutting insert in a direction orthogonal to the pressure receiving surface.
2. The cutting insert of claim 1 , wherein in the fastening surface, when a first angle which is formed between the first central axis and a surface of the fastening surface is defined in a cross section that runs through the first central axis and an initial portion of the fastening surface, and a second angle which is formed between the first central axis and a surface of the fastening surface is defined in a cross section that runs through the first central axis and a final portion of the fastening surface, the first angle is greater than the second angle.
3. The cutting insert of claim 2 , wherein in the fastening surface, when a third angle which is formed between the first central axis and a surface of the fastening surface is defined in a first cross section that runs through the first central axis and an initial portion of the fastening surface and a fourth angle which is formed between the first central axis and a surface of the fastening surface is defined in a cross section that is in parallel with the first cross section and runs through a final portion of the fastening surface, the third angle and the fourth angle are equal to each other.
4. An indexable drill comprising:
a holder body;
a body flute which is formed in an outer circumferential surface of the holder body and guides a discharge of cutting chips;
a seat which is formed at a tip portion of the holder body and on which a cutting insert is placed;
a center boss which is formed on the seat and guides the rotation of the cutting insert when the cutting insert is mounted; and
twin fingers which are formed on the seats in the form of two branches, have a holder fastening surface that is formed on an inner circumferential surface thereof so as to be concentric with a third central axis of the center boss, and have a pressing surface that is formed at a lateral side so as to press the cutting insert, and
the cutting insert is the cutting insert according to claim 3 .
5. An indexable drill comprising:
a holder body;
a body flute which is formed in an outer circumferential surface of the holder body and guides a discharge of cutting chips;
a seat which is formed at a tip portion of the holder body and on which a cutting insert is placed;
a center boss which is formed on the seat and guides the rotation of the cutting insert when the cutting insert is mounted; and
twin fingers which are formed on the seats in the form of two branches, have a holder fastening surface that is formed on an inner circumferential surface thereof so as to be concentric with a third central axis of the center boss, and have a pressing surface that is formed at a lateral side so as to press the cutting insert, and
the cutting insert is the cutting insert according to claim 2 .
6. The cutting insert of claim 1 , wherein in the fastening surface, when a reference line is presented at a particular height, and a first distance along the reference line from a surface of an initial portion of the fastening surface to the first central axis, and a second distance along the reference line from a surface of a final portion of the fastening surface to the first central axis are defined, the first distance is smaller than the second distance.
7. The cutting insert of claim 6 , wherein in the fastening surface, third and fifth distances from the first central axis to an initial portion of the fastening surface are smaller than fourth and sixth distances from the first central axis to a final portion of the fastening surface when viewed from a plan cross section that runs through the fastening surface,
wherein the third distance represents a shortest distance from the first central axis to a surface of the initial portion in a plan cross section of a portion adjacent to the tip portion,
the fourth distance represents a shortest distance from the first central axis to the surface of the initial portion in a plan cross section of a portion adjacent to a seating surface of the cutting insert,
fifth distance represents a shortest distance from the first central axis to the surface of the final portion in the plan cross section of a portion adjacent to the tip portion, and
the sixth distance represents a shortest distance from the first central axis to the surface of the final portion in the plan cross-section of a portion adjacent to the seating surface.
8. An indexable drill comprising:
a holder body;
a body flute which is formed in an outer circumferential surface of the holder body and guides a discharge of cutting chips;
a seat which is formed at a tip portion of the holder body and on which a cutting insert is placed;
a center boss which is formed on the seat and guides the rotation of the cutting insert when the cutting insert is mounted; and
twin fingers which are formed on the seats in the form of two branches, have a holder fastening surface that is formed on an inner circumferential surface thereof so as to be concentric with a third central axis of the center boss, and have a pressing surface that is formed at a lateral side so as to press the cutting insert, and
the cutting insert is the cutting insert according to claim 7 .
9. An indexable drill comprising:
a holder body;
a body flute which is formed in an outer circumferential surface of the holder body and guides a discharge of cutting chips;
a seat which is formed at a tip portion of the holder body and on which a cutting insert is placed;
a center boss which is formed on the seat and guides the rotation of the cutting insert when the cutting insert is mounted; and
twin fingers which are formed on the seats in the form of two branches, have a holder fastening surface that is formed on an inner circumferential surface thereof so as to be concentric with a third central axis of the center boss, and have a pressing surface that is formed at a lateral side so as to press the cutting insert, and
the cutting insert is the cutting insert according to claim 6 .
10. The cutting insert of claim 1 , wherein a wrench groove into which a wrench tool is mounted is further formed at a lateral side of the insert body, and the wrench groove is formed to be inclined in a direction identical to a direction of a gradient of the lateral cutting edge when viewed from a lateral side of the insert body.
11. An indexable drill comprising:
a holder body;
a body flute which is formed in an outer circumferential surface of the holder body and guides a discharge of cutting chips;
a seat which is formed at a tip portion of the holder body and on which a cutting insert is placed;
a center boss which is formed on the seat and guides the rotation of the cutting insert when the cutting insert is mounted; and
twin fingers which are formed on the seats in the form of two branches, have a holder fastening surface that is formed on an inner circumferential surface thereof so as to be concentric with a third central axis of the center boss, and have a pressing surface that is formed at a lateral side so as to press the cutting insert, and
the cutting insert is the cutting insert according to claim 10 .
12. The cutting insert of claim 1 , wherein a curved surface grinding reference surface, which has a radius smaller than an outer diameter of the insert body and is concentric with the first central axis, is formed at a lower side of the insert body, and the curved surface grinding reference surface is clamped by a grinding machine when the cutting insert is mounted on the grinding machine and subjected to grinding processing.
13. The cutting insert of claim 12 , wherein a flat surface grinding reference surface having a flat shape is further formed on the curved surface grinding reference surface, and the flat surface grinding reference surface is used to manage a dimension of the cutting insert.
14. An indexable drill comprising:
a holder body;
a body flute which is formed in an outer circumferential surface of the holder body and guides a discharge of cutting chips;
a seat which is formed at a tip portion of the holder body and on which a cutting insert is placed;
a center boss which is formed on the seat and guides the rotation of the cutting insert when the cutting insert is mounted; and
twin fingers which are formed on the seats in the form of two branches, have a holder fastening surface that is formed on an inner circumferential surface thereof so as to be concentric with a third central axis of the center boss, and have a pressing surface that is formed at a lateral side so as to press the cutting insert, and
the cutting insert is the cutting insert according to claim 12 .
15. An indexable drill comprising:
a holder body;
a body flute which is formed in an outer circumferential surface of the holder body and guides a discharge of cutting chips;
a seat which is formed at a tip portion of the holder body and on which a cutting insert is placed;
a center boss which is formed on the seat and guides the rotation of the cutting insert when the cutting insert is mounted; and
twin fingers which are formed on the seats in the form of two branches, have a holder fastening surface that is formed on an inner circumferential surface thereof so as to be concentric with a third central axis of the center boss, and have a pressing surface that is formed at a lateral side so as to press the cutting insert, and
the cutting insert is the cutting insert according to claim 1 .
16. The cutting insert of claim 15 , further comprising:
an oil hole which is formed in the holder body, and allows cutting oil to be discharged to the cutting insert and a portion which is subjected to the cutting processing.
17. The cutting insert of claim 15 , wherein the pressing surface is formed to be inclined when viewed from a lateral side of the holder body in a direction orthogonal to the pressing surface so that a portion of the pressing surface, which is directed toward a tip portion of the twin finger, is wider with respect to the third central axis.
18. The cutting insert of claim 15 , wherein a post of the cutting insert is loosely assembled to the center boss.
19. The cutting insert of claim 15 , wherein a guide protrusion is further formed on the seat so as to guide the rotation of the cutting insert when the cutting insert is mounted on or separated from the holder body.