JP2007283466A - Cutting insert and cutting tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting insert, reducing cutting resistance to favorably perform cutting for extended life, and a cutting tool where the cutting insert is mounted. <P>SOLUTION: This cutting insert 10 is mounted on the cutting tool adapted to cut the inner wall surface of a prepared hole to form a machined hole. The cutting insert, the outline of which is like a polygonal plate, has two polygonal surfaces 11 and a side surface 12 intersecting the polygonal surfaces 11, and a cutting blade 15 extending from the corner part of the polygonal surface 11 the ridge part and a breaker groove 13 extending along the inside of the cutting blade 15 and recessed from the polygonal surface 11 are formed on the polygonal surface 11. The breaker groove 13 is provided with an inclined surface 13A, which is inclined to gradually retreat from the polygonal surface 11 where the breaker groove 13 is formed as it separates from the corner part, seen from the opposite side to the side surface 12, and the cutting blade 15 is formed on the intersecting ridge part between the inclined surface 13A and the side surface 12. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cutting insert that is detachably attached to a cutting tool that is used when a machining hole is formed by cutting an inner wall surface of a prepared hole that is provided in advance in a workpiece, and the cutting insert is attached. Related to cutting tools.

  2. Description of the Related Art In recent years, a boring cutter or the like in which a cutting insert having a cutting blade is detachably attached to the outer periphery of a tip end of a tool body is known as a cutting tool used for machining a cylinder bore of an engine. Here, in the case of a boring cutter for roughing the inner wall surface of the prepared hole of the workpiece, the cutting resistance tends to increase in order to obtain a relatively large cutting allowance. Therefore, negative cutting inserts having high rigidity are widely used for such boring cutters.

The negative type cutting insert attached to the boring cutter has an outer shape of, for example, a substantially rectangular flat plate shape, and a cutting edge is formed on a side ridge portion of the rectangular surface, and a rectangular surface which is a rake face and a relief surface. The side surfaces are arranged so as to be orthogonal to each other, and the clearance angle is not attached to the clearance surface.
This cutting insert is mounted on the tool body so that its thickness direction is substantially along the tool rotation direction, that is, one square surface faces forward in the tool rotation direction.

  By the way, since the negative type cutting insert does not have a clearance angle on the side that is the flank, both the radial rake angle and the axial rake angle of the main cutting edge directed to the tool body tip side of the cutting insert are both It is necessary to set the negative side and give relief to the side that is regarded as the flank. However, when the radial rake angle and axial rake angle of the main cutting edge are both set to the negative side in this way, the cutting edge of the main cutting edge tends to become dull and the cutting resistance tends to increase. In some cases, vibration could occur and machining could not be performed with high accuracy. Further, not only the cutting insert but also the tool body may be damaged due to excessive cutting resistance. Furthermore, since the sharpness is inferior, there is also a problem that the finished surface that has been machined becomes rough.

Therefore, in the boring cutters described in Patent Document 1 and Patent Document 2, one in which a breaker groove is formed so as to be continuous with the cutting edge of the cutting insert has been proposed. 6 to 8 show an example of a conventional cutting insert.
This cutting insert has a quadrangular flat plate shape and includes two quadrangular surfaces 1 and four side surfaces 2, and the side surface 2 and the quadrangular surface 1 are arranged so as to be orthogonal to each other. A cutting blade 3 is formed at the crossing ridge line. Note that the height of the cutting edge 3 is constant in the circumferential direction of the rectangular surface 1.

  A breaker groove 4 that is recessed from the rectangular surface 1 in the thickness direction of the cutting insert is formed inside the cutting edge 3. Further, a rib portion 5 extending from the central portion of the quadrangular surface 1 toward the central portion of the four side ridge portions of the quadrangular surface 1 is formed, and the breaker groove 4 is divided by the rib portion 5. As shown in FIG. 8, the breaker groove 4 has a slope portion 6 that gradually slopes from the rectangular surface 1 as it approaches the center of the square surface 1 from the cutting edge 3 and the slope portion in the cross section perpendicular to the cutting edge 3. 6, and the depth of the bottom surface of the breaker groove 4 (the connecting portion between the slope portion 6 and the concave curved surface portion 7) is constant in the circumferential direction of the rectangular surface 1. Yes. Therefore, as shown in FIG. 7 when the cutting insert is viewed from the side, the cutting blade 3 and the bottom surface of the breaker groove 4 are arranged in parallel to each other.

  The cutting insert having such a configuration has a side surface 2 in which one rectangular surface 1 which is a rake face faces the front side in the tool rotation direction and is directed to the front end side of the tool body to be a front flank. And it mounts | wears so that relief may be given to the side 2 turned to the tool body radial direction outer side and made into the outer periphery flank. One cutting blade 3 is directed to the tip side of the tool body to be a main cutting blade. The boring cutter constructed in this way is attached to the spindle end of the machine tool via an adapter or the like, rotated at a high speed around the axis of the tool body, and fed in the axial direction of the tool body. The inner wall surface of the prepared hole is cut by the main cutting edge (cutting edge 3) of the cutting insert that is inserted into the prepared hole provided in advance in the workpiece and attached to the outer peripheral portion on the distal end side of the tool body. The processing hole of the inner diameter is formed.

The cutting insert having this configuration adjusts the crossing angle between the inclined surface portion 6 of the breaker groove 4 and the rectangular surface 1, and gives relief to the side surface 2 that is directed to the front end side of the tool body and serves as a front flank surface, The axial rake angle of the main cutting edge (cutting edge 3) is set to the positive side, the sharpness of the main cutting edge is improved, and cutting resistance is reduced.
Japanese Patent Laid-Open No. 10-146712 JP 2003-160488 A

  However, as shown in FIGS. 6 to 8, in the cutting insert in which the breaker groove 4 is formed, the axial rake angle of the main cutting edge is set to the positive side, but the radial rake angle is set to the negative side. In addition, the cutting force could not be reduced sufficiently. For this reason, there existed a problem that the vibration of a tool main body generate | occur | produced by cutting resistance, processing accuracy deteriorated, or the surface roughness after a process with a dullness was dull. In addition, there is a problem in that the cutting insert is damaged due to excessive cutting resistance, the life of the cutting insert is shortened, and the usage cost of the cutting insert is increased.

  The present invention has been made in view of the above-described circumstances, and is provided with a cutting insert capable of reducing cutting resistance and performing cutting work satisfactorily and extending the life of the cutting insert. An object is to provide a cutting tool.

  In order to achieve this object, a cutting insert according to the present invention is a cutting insert that is attached to a cutting tool that forms a processed hole by cutting an inner wall surface of a prepared hole provided in a workpiece. Has a polygonal flat plate shape and has two polygonal surfaces and side surfaces orthogonal to the two polygonal surfaces, and the polygonal surface includes a corner from the corner of the polygonal surface to a side ridge. And a breaker groove that extends along the inside of the cutting blade and is recessed from the polygonal surface, the breaker groove being formed on the corner portion when viewed from the side facing the side surface. The breaker groove has an inclined surface that inclines so as to gradually recede from the polygonal surface, and the cutting edge is formed at the intersecting ridge line portion between the inclined surface and the side surface. It is characterized by being.

  In the cutting tool of the present invention, the above-mentioned cutting insert is detachably mounted, and an inner wall surface of a prepared hole provided in a workpiece is cut by the cutting blade of the cutting insert to form a processed hole. A cutting tool having a tool body that is rotated about an axis, recessed portions are formed on an outer periphery of a tip portion of the tool body, and a mounting seat is formed on a rear side in the tool rotation direction of the recessed portions; One of the polygonal surfaces is mounted so as to face the front side in the tool rotation direction, and one of the corner portions protrudes outward in the tool main body radial direction and the tip end side of the tool main body.

  According to the cutting insert and the cutting tool of this configuration, the breaker groove formed in the cutting insert is provided with the inclined surface inclined with respect to the polygonal surface that is the rake face, and the intersecting ridge line between the inclined surface and the side surface Since the cutting edge is formed in the part, the cutting edge itself is arranged so as to be inclined with respect to the polygonal surface, and the clearance is given to the side surface that is directed to the outer side in the radial direction of the tool body and is the outer peripheral flank. Even when the cutting insert is mounted as described above, the radial rake angle of the main cutting edge directed to the tip side of the tool body can be set to the positive side.

Further, even if the cutting insert is mounted so that the breaker groove faces the side of the tool body toward the tip side of the tool body and the tip is flank, the axial rake angle of the main cutting edge is set to the positive side. be able to. Therefore, by setting both the radial rake angle and the axial rake angle of the main cutting edge to the positive side, the sharpness of the main cutting edge can be improved and the cutting resistance can be greatly reduced.
By reducing the cutting resistance in this way, vibration of the tool body can be prevented and cutting can be performed with high accuracy, and the cutting insert can be prevented from being damaged and broken, thereby extending the life of the cutting insert. . Moreover, the surface roughness of the processed surface after cutting can be improved by improving the sharpness of the main cutting edge.

  Here, when viewed from the side facing the side surface, an angle θ formed by the inclined surface and the polygonal surface is set within a range of 5 ° ≦ θ ≦ 15 °, whereby the outer peripheral flank surface is obtained. The cutting insert can be attached to the side face with an angle θ or less to prevent sliding contact between the outer flank face and the work material, and the radial rake angle of the main cutting edge is reliably set to the positive side. can do.

  Furthermore, the cutting insert is mounted on the mounting seat by forming rib portions on the polygonal surface that extend from the center of the polygonal surface toward the side ridges and divide the breaker groove into corners. When placing, the rib portion can be mounted in close contact with the mounting seat, and the amount of protrusion of the cutting blade from the mounting seat can be reduced. Therefore, the cutting force acting on the cutting edge can be received by the mounting seat, and the cutting insert can be prevented from being broken to extend the life of the cutting insert. Further, it is possible to prevent chips generated by the cutting blade from rubbing other breaker grooves, and it is possible to prevent the cutting blade formed at the other corner from being worn before use.

  Further, the axial rake is set so that the radial rake angle α is in the range of −15 ° ≦ α ≦ −3 ° with respect to the polygonal surface directed forward in the tool rotation direction. By mounting so that the angle β falls within the range of −15 ° ≦ β ≦ −3 °, the radial rake angle of the main cutting edge can be set to the positive side more reliably, and the cutting resistance can be reduced. .

  ADVANTAGE OF THE INVENTION According to this invention, cutting resistance which reduces cutting resistance and can perform favorable cutting work, and can aim at extension of a lifetime can be provided, and the cutting tool equipped with this cutting insert can be provided.

Embodiments of the present invention will be described with reference to the accompanying drawings. The cutting insert which is this embodiment is shown in FIG.1 and FIG.2. FIGS. 3 to 5 show a boring cutter (cutting tool) configured by mounting this cutting insert.
The cutting insert 10 is made of a hard material such as cemented carbide, and as shown in FIGS. 1 and 2, the outer shape is a substantially rectangular flat plate shape, more specifically, a square flat plate shape. A so-called negative type cutting insert 10 having four side surfaces 12 arranged so as to be orthogonal to these two rectangular surfaces 11.

  The quadrangular surface 11 includes a breaker groove 13 extending along the side ridge portion of the quadrangular surface 11 and recessed from the quadrangular surface 11, and a quadrangular surface from the central portion of the quadrangular surface 11 toward each side ridge portion of the quadrangular surface 11. 11 and a rib portion 14 extending on the same plane. In the present embodiment, the rib portion 14 is formed so as to divide the side ridge portion into two equal parts, and the rib portion 14 divides the breaker groove 13 so as to be positioned at the four corner portions 11 </ b> A of the rectangular surface 11. ing. Thereby, the breaker groove | channel 13 is arrange | positioned so that it may make a substantially L shape seeing from the side facing the square surface 11, as shown in FIG.

Further, as shown in FIG. 2, the breaker groove 13 gradually retreats from the rectangular surface 11 on which the breaker groove 13 is formed as it is away from the corner portion 11 </ b> A as seen from the side facing the side surface 12 of the cutting insert 10. An inclined surface 13A that extends in this manner, and a concave curved surface 13B that connects the inclined surface 13A and the rib portion 14 are provided.
In the present embodiment, since the rib portion 14 is formed so as to bisect the side ridge portion of the quadrangular surface 11, the breaker groove 13 has two rib portions 14 as viewed from the side facing the quadrangular surface 11. The ribs 14 and the breaker grooves 13 are formed on the two quadrangular surfaces 11 so that they are symmetrical with respect to the equally dividing reference line. The cutting inserts 10 are also arranged so as to be line symmetric with respect to a reference line that bisects the thickness direction of the cutting insert 10.

And the cutting edge 15 is formed in the intersection ridgeline part of this inclined surface 13A and the side surface 12. As shown in FIG. That is, the cutting insert 10 is formed with a pair of cutting edges 15 intersecting at the corners 11 </ b> A, and a breaker groove 13 having an approximately L shape is disposed along the inside of the pair of cutting edges 15. It has been done.
The angle θ formed by the inclined surface 13A and the rectangular surface 11 is set within a range of 5 ° ≦ θ ≦ 15 °, and in this embodiment, θ = 10 °. The rectangular surface 11 is arranged so as to intersect at an intersection angle of 10 °.

  Further, an insertion hole 16 penetrating in the thickness direction perpendicular to the quadrangular surface 11 is formed in the central portion of the quadrangular surface 11. As shown in FIG. 1, the cutting insert 10 is formed so as to be 90 ° rotationally symmetric with respect to the center portion of the cutting insert 10 (the center of the insertion hole 16) as viewed from the side facing the rectangular surface 11. Yes.

  Next, the boring cutter 20 configured by mounting the cutting insert 10 will be described. As shown in FIGS. 3 and 4, the boring cutter 20 has a tool body 21 having a substantially multi-stage columnar shape with the axis O as the center. An attachment hole 22 for attaching the tool body 21 to a spindle end or the like of a machine tool (not shown) is formed on the rear end side (upper side in FIG. 3) of the tool body 21. Further, the tool body 21 is formed with a coolant hole 23 communicating with the mounting hole 22 and extending along the axis O, and a coolant reservoir 24 having a larger diameter than the coolant hole 23. A set screw 25 is screwed to the front end side portion of the storage portion 24 along the axis O.

  A plurality of recesses 26 are formed in the circumferential direction on the outer periphery on the tip end side of the tool body 21 so that the tool body 21 is notched and opened toward the tip end side of the tool body 21 and the tool body 21 radially outward. A mounting seat 27 for mounting the cutting insert 10 is provided on the rear side of the tool rotation direction T of 26. In the present embodiment, as shown in FIG. 4, five concave portions 26 and five attachment seats 27 are arranged. These five mounting seats 27 are arranged at unequal intervals in the circumferential direction.

As shown in FIG. 5, the wall surface 27 </ b> A facing the tool rotation direction T front side of the mounting seat 27 is inclined with respect to the axis O so as to gradually retreat toward the tool rotation direction T rear side as it goes toward the tip end side of the tool body 21. It has been made. Further, a screw hole (not shown) is formed in the wall surface 27A of the mounting seat 27 facing the front side in the tool rotation direction T.
Further, the wall surface 27B of the mounting seat 27 facing the front end side of the tool body 21 is inclined so as to gradually recede toward the rear end side of the tool body 21 as it goes outward in the radial direction of the tool body 21 as shown in FIG. .

Further, a coolant discharge hole 28 communicating with the coolant reservoir 24 is opened on the bottom surface of the recess 26 facing the tool body 21 radially outward, and the coolant discharge hole 28 faces radially outward of the tool body 21. Therefore, it is arranged so as to be directed toward the rear side of the tool rotation direction T.
Further, on the front side of the recess 26 in the tool rotation direction T, a notch 29 is formed by notching the outer peripheral end portion of the recess 26.

The cutting insert 10 is mounted on the mounting seat 27 having such a configuration to form the boring cutter 20.
The cutting insert 10 is arranged such that one rectangular surface 11A of the cutting insert 10 faces the front side in the tool rotation direction T and the other rectangular surface 11 closely contacts the wall surface 27A facing the front side in the tool rotation direction T of the mounting seat 27. The cutting insert 10 is arranged on the mounting seat 27 so that the side surface 12 facing the rear end side of the tool body 21 of the 10 contacts the wall surface 27B facing the front end side of the tool body 21 of the mounting seat 27. In this state, the cutting insert 10 is firmly fixed to the mounting seat 27 by inserting the clamp screw 30 into the insertion hole 16 of the cutting insert 10 and screwing it into the screw hole formed in the mounting seat 27. When the clamp screw 30 is screwed, a work tool such as a screwdriver is inserted through a notch 29 formed on the front side of the recess 26 in the tool rotation direction T.

  By mounting the cutting insert 10 on the mounting seat 27 in this way, the cutting insert 10 has one corner 11A toward the distal end side of the tool body 21 and the outer side in the radial direction of the tool body 21 as shown in FIG. Of the pair of cutting blades 15 that are protruded and formed at the corner portion 11A, the cutting blade 15 that is directed toward the distal end side of the tool body 21 is a main cutting blade 15A, and the main cutting blade 15A and the axis O are orthogonal to each other. The angle formed by the plane, the so-called lead angle γ, is set within a range of 3 ° ≦ γ ≦ 45 °, and in this embodiment, γ = 5 °.

  Further, the radial rake angle α with respect to the rectangular surface 11A directed to the front side of the tool rotation direction T of the cutting insert 10 as a reference, as shown in FIG. It is set to the negative side so as to recede to the side, specifically, it is set within the range of −15 ° ≦ α ≦ −3 °, and in this embodiment, α = −5 °. Thereby, relief is given to side 12B turned to the tool body 21 diameter direction outside and made into the peripheral flank.

  Furthermore, the axial rake angle β with respect to the rectangular surface 11A directed to the front side of the tool rotation direction T of the cutting insert 10 is the rear side of the tool rotation direction T as shown in FIG. In this embodiment, β is set to −5 °, and is set to be in a range of −15 ° ≦ β ≦ −3 °. As a result, a relief is given to the side surface 12 </ b> A that is directed to the tip side of the tool body 21 and serves as a tip flank.

The boring cutter 20 configured in this way is attached to the spindle end of the machine tool through the attachment hole 22 of the tool body 21, and rotates the tool body 21 around the axis at a high speed and feeds it in the direction of the axis O. The inner wall surface of the prepared hole is made to have a predetermined inner diameter by the main cutting edge 15A of the cutting insert 10 directed to the distal end side of the tool body 21 by being inserted into the prepared hole formed in the workpiece. It forms a machined hole.
In this cutting process, cutting oil is supplied from the machine tool side to the coolant hole 23, and this cutting oil is discharged toward the main cutting edge 15 </ b> A through the coolant reservoir 24 and the coolant discharge hole 28.

  In the cutting insert 10 according to the present embodiment, a breaker groove 13 is formed along the side ridge portion of the square surface 11, and the breaker groove 13 includes an inclined surface 13A that intersects the square surface 11 at an angle θ = 10 °. Since the cutting edge 15 is formed at the intersecting ridge line portion between the inclined surface 13A and the side surface 12, as shown in FIG. 4, the radial rake angle α is set to the negative side with respect to the rectangular surface 11, More specifically, even if the cutting insert 10 is attached so that α = −5 °, the radial rake angle of the main cutting edge 15A itself is set to the positive side.

  Further, since the breaker groove 13 that is recessed from the rectangular surface 11 is formed, as shown in FIG. 5, more specifically, the axial rake angle β is set to be on the negative side with respect to the rectangular surface 11. Even if the cutting insert 10 is attached so as to be = −5 °, the axial rake angle of the main cutting edge 15A itself can be set to the positive side.

  Therefore, according to the present embodiment, even if the cutting insert 10 is mounted so that the radial rake angle and the axial rake angle are negative with respect to the quadrangular surface 11, the axial rake angle and the radial rake angle of the main cutting edge 15A itself. Can be set to the positive side, the sharpness of the main cutting edge 15A can be improved, and the cutting resistance can be reliably reduced. Therefore, vibration of the tool body 21 due to cutting resistance can be prevented and cutting can be performed with high accuracy, and damage to the cutting insert 10 can be prevented. Moreover, the surface roughness of the processed surface after cutting can be improved by improving the sharpness of the main cutting edge 15A.

  Further, since the cutting insert 10 is mounted so that the radial rake angle and the axial rake angle are negative with respect to the quadrangular surface 11, the side surface 12 </ b> A that is directed toward the distal end side of the tool body 21 and serves as the distal end flank and the tool The side surface 12B, which is directed outward in the radial direction of the main body 21 and formed as an outer peripheral flank, can be provided with a flank so as to recede toward the rear side in the tool rotation direction T. It is possible to prevent sliding contact with the material and to perform cutting work well.

  Further, since the rib portion 14 extending from the central portion of the quadrangular surface 11 toward the side ridge portion is formed, the rib portion 14 with respect to the wall surface 27A facing the cutting insert 10 toward the front side in the tool rotation direction T of the mounting seat 27. Can be mounted so that the amount of protrusion of the main cutting edge 15A from the mounting seat 27 can be kept small. Therefore, the cutting force acting on the main cutting edge 15A during cutting can be received by the mounting seat 27, and the cutting edge 15 can be prevented from being lost.

  Further, the cutting insert 10 is formed to be 90 ° rotationally symmetric with respect to the center of the quadrangular surface 11 when viewed from the side facing the quadrangular surface 11, and the cutting insert 10 of the quadrangular surface 11 is viewed from the side facing the side surface 12. 8 corners formed in the cutting insert 10 because it is line-symmetric with respect to a reference line that bisects the side ridge part and line-symmetrically with respect to a reference line that bisects in the thickness direction. The part 11A can be mounted and used so as to sequentially protrude from the tool body 21, and the usage cost of the cutting insert 10 can be greatly reduced. Furthermore, even when this cutting insert 10 is applied not only to a right-turning cutting tool but also to a left-turning cutting tool, the radial rake angle of the main cutting edge 15A can be set to the positive side as described above. Further, cutting can be performed satisfactorily while cutting resistance is reduced.

In addition, since the breaker groove 13 is divided for each corner portion 11A by the rib portion 14, chips generated by the main cutting edge 15A directed toward the distal end side of the tool body 21 are arranged in the other corner portion 11A. Scraping of the breaker groove 13 is prevented, and the cutting edges 15 formed on the other corner portions 11A can be used sequentially.
Moreover, since it is set as the negative type cutting insert 10, even if a cutting allowance is enlarged, the cutting insert 10 will not be damaged, and cutting can be performed efficiently.

  Further, in the boring cutter 20 having this configuration, since the mounting seats 27 are arranged at unequal intervals in the circumferential direction, the cutting resistance acting on the main cutting edge 15A of the cutting insert 10 mounted on the mounting seat 27 is large. It is possible to prevent occurrence of periodic vibration (resonance) corresponding to the natural frequency of the tool body 21 due to the different sheath operating times. In addition, since the five mounting seats 27 are provided to form the so-called odd-blade boring cutter 20, resonance of the tool body 21 can be prevented more reliably.

  Further, the angle formed by the main cutting edge 15A and the plane orthogonal to the axis O, the so-called lead angle γ is in the range of 3 ° ≦ γ ≦ 45 °, more specifically, γ = 5 °. Further, the vibration of the tool body 21 can be suppressed by reducing the back component force of the cutting resistance, and the cutting insert 10 can be prevented from being damaged by preventing the impact during cutting from becoming unnecessarily large.

As mentioned above, although embodiment of this invention was described, this invention is not limited to this, It can change suitably in the range which does not deviate from the technical idea of the invention.
For example, in a side view of the cutting insert, the angle θ formed by the inclined surface formed in the breaker groove and the square surface is set within a range of 5 ° ≦ θ ≦ 15 °, more specifically, θ = 10 °. However, the present invention is not limited to this value, and the angle θ may be set arbitrarily.

  Further, the rib portion is formed so as to extend toward the portion that bisects the side ridge portion, and the cutting insert is further 90 ° rotationally symmetric with respect to the center of the quadrangular surface. Although it demonstrated as what was comprised symmetrically with respect to the bisector of a side ridge part, and symmetrical with respect to the bisector of a thickness direction, it is not limited to this, A rib part May be formed so as to be biased toward one corner, or the rib may not be formed. However, by adopting the shape as in this embodiment, the corners of the cutting insert can be used sequentially, and can be applied to both a right-turning cutting tool and a left-turning cutting tool.

  Furthermore, although it demonstrated as a boring cutter which provided the recessed part and the attachment seat 5 each (odd number) and arrange | positioned these recessed parts and the attachment seat in the circumferential direction at unequal intervals, it is not limited to this, A recessed part and The number and arrangement of the mounting seats can be arbitrarily set, and are preferably set appropriately in consideration of the material of the workpiece, cutting conditions, and the like. However, the resonance of the tool body can be prevented by using odd-numbered blades as in the present embodiment or by arranging the mounting seats at unequal intervals.

  In addition, the lead angle γ of the main cutting edge has been described as a boring cutter attached to the tool body within the range of 3 ° ≦ γ ≦ 45 °, more specifically, γ = 5 °. It is not limited and can be set arbitrarily. However, by setting the lead angle γ within the range of this embodiment, the back force of the cutting resistance can be reduced to prevent vibration of the tool body, and the impact during cutting can be suppressed to prevent damage to the cutting insert. it can.

It is a front view of the cutting insert which is this embodiment. It is a side view of the cutting insert shown in FIG. It is a side surface fragmentary sectional view of the cutting tool with which the cutting insert shown in FIG. 1 was mounted | worn. It is a bottom view of the cutting tool shown in FIG. It is a side view of the mounting seat of the cutting tool shown in FIG. It is a front view of the conventional cutting insert. It is a side view of the cutting insert shown in FIG. It is XX sectional drawing in FIG.

Explanation of symbols

10 Cutting insert 11 Square surface (polygonal surface)
11A Corner portion 12 Side surface 13 Breaker groove 13A Inclined surface 14 Rib portion 15 Cutting edge 20 Boring cutter (cutting tool)
21 Tool body 26 Recessed part 27 Mounting seat

Claims (5)

A cutting insert attached to a cutting tool that forms a processed hole by cutting an inner wall surface of a prepared hole provided in a workpiece,
The outer shape is a polygonal flat plate shape and has two polygonal surfaces and side surfaces orthogonal to these two polygonal surfaces,
The polygonal surface is formed with a cutting edge extending from the corner of the polygonal surface along the side ridge, and a breaker groove extending along the inside of the cutting edge and recessed from the polygonal surface. ,
The breaker groove has an inclined surface that is inclined so as to gradually recede from the polygonal surface on which the breaker groove is formed as viewed from the side facing the side surface as the distance from the corner portion increases. The cutting insert, wherein the cutting edge is formed at a crossing ridge line portion between the inclined surface and the side surface.   The angle θ formed by the inclined surface and the polygonal surface when viewed from the side facing the side surface is set within a range of 5 ° ≦ θ ≦ 15 °. Cutting inserts.   The rib portion that extends from the central portion of the polygonal surface toward each side ridge portion and divides the breaker groove into corner portions is formed on the polygonal surface. The cutting insert according to claim 2. The cutting insert according to any one of claims 1 to 3 is detachably mounted, and an inner wall surface of a prepared hole provided in a workpiece is cut by the cutting blade of the cutting insert to form a processing hole. A cutting tool to be formed,
Having a tool body rotated around an axis, a recess is formed on the outer periphery of the tip of the tool body, and a mounting seat is formed on the rear side in the tool rotation direction of the recess,
One of the polygonal surfaces of the cutting insert faces the front side in the tool rotation direction, and one of the corners is mounted so as to protrude outward in the tool body radial direction and the tool body tip side. Cutting tool that features.   The cutting insert has an axial rake so that the radial rake angle α is within a range of −15 ° ≦ α ≦ −3 ° with respect to the polygonal surface facing the front side in the tool rotation direction. The cutting tool according to claim 4, wherein the angle β is mounted so as to be in a range of −15 ° ≦ β ≦ −3 °.

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