JP2020151785A - Cutting insert and edge replacement type cutter - Google Patents

Abstract

To control a curl diameter of a chip while preventing an increase of cutting resistance.SOLUTION: In a cutting insert installed on an edge replacement type cutter, a rake face 2, a seating surface and a flank surface 4 are formed on an insert body 1, and an installation hole is opened in a central part of the rake face 2 and the seating surface, and a cutting edge 5 is formed in a crossing ridge line part of the rake face 2 and the flank surface 4, and the rake face 2 has a first inclination plane 2a inclining in a linear shape to the seating surface side according to separation from the cutting edge 5 to the cutting edge 5 side and a second inclination plane 2b inclining in a linear shape to the opposite side of the seating surface according to separation from the cutting edge 5 on the inside of the rake face 2 of the first inclination plane 2a in a cross section orthogonal to the cutting edge 5, and a height up to an upper end of the second inclination plane 2b from the seating surface is higher than a height up to the cutting edge 5 from the seating surface in the vertical direction to the seating surface.SELECTED DRAWING: Figure 6

Description

The present invention relates to a cutting insert that can be detachably attached to an insert mounting seat formed on the outer periphery of the tip of a cutter body of a cutter body that rotates around an axis, and such a cutting insert is an insert mounting seat of the cutter body. It relates to a cutter with a replaceable cutting edge that is detachably attached to.

As such a cutting insert, Patent Document 1 has a chamfer surface in a portion closest to the flank surface of the rake face, and this chamfer surface shifts to a second chamfer surface forming an obtuse angle to further rake face. A milling insert with a cross-sectional rake face that transitions to an inwardly or downwardly sloping slope surface with respect to a flat bottom surface is described. Here, the cutting insert described in Patent Document 1 is a positive type cutting insert in which the flank forms an acute angle.

Further, in FIGS. 6 and 7 of Patent Document 1, chips are formed at the transition portion between the bottom surface and the land by shifting the top surface of the rake face at a position higher than the lowest portion of the bottom surface to the land. Those with a stop surface formed are also described. Further, it is also described in Patent Document 1 that the possibility of having a shape in which the chamfer surface, the slope surface, and the bottom surface are concavely curved is not excluded.

Japanese Unexamined Patent Publication No. 2006-255882

By the way, the positive type cutting insert (rolling insert) as described in Patent Document 1 is often used for cutting with low cutting and low feed, and the thickness of chips becomes thin, so that curl It becomes difficult to control the diameter, and there is a concern that chips may be caught or the conveyor may be clogged when the chips are discharged.

In particular, in the case of a downcut in which the rotation direction of the cutter and the feed direction of the work material are the same (the rotation direction of the cutter and the feed direction are opposite directions), after the cutting edge bites the work material. In the first half of the cut, thick chips are generated, so the chips are curled to a small curl diameter near the cutting edge, but the second half of the cut before the cutter rotates and the cutting edge separates from the work material. Then, the thickness of the chips becomes thin, and the chips extend without being curled in the vicinity of the cutting edge, which causes the above-mentioned biting and clogging of the conveyor.

Here, in the cutting inserts shown in FIGS. 6 and 7 of Patent Document 1, a chip stop surface is formed at the transition portion between the bottom surface and the land, and a cutting edge having a thick chip bites. In the first half of the cut, the chips can be curled by the chip stop surface, but since the height of the upper end of the chip stop surface is lower than that of the cutting edge, the cutting edge is separated from the work material. In the latter half of the above, thin chips cannot be applied to the chip stop surface to curl, and the chips grow.

Further, as described in Patent Document 1, when the slope surface, the bottom surface, or the chip stop surface has a concavely curved shape, the thick chips generated in the first half of the cut are these slopes. There is a risk that the cutting resistance will increase due to surface contact with the surface, bottom surface, and chip stop surface.

The present invention has been made under such a background, and the thickness generated in the latter half of the incision is prevented from increasing the cutting resistance due to the surface contact of the thick chips generated in the first half of the incision. It provides cutting inserts that reliably curl thin chips to control the curl diameter and prevent chip biting and conveyor clogging, while such cutting inserts are detachably mounted on the insert mounting seat. The purpose is to provide a cutter with a replaceable cutting edge.

In order to solve the above problems and achieve such an object, the cutting insert of the present invention is attached to and detached from the insert mounting seat formed on the outer periphery of the tip of the cutter body of the blade tip exchange type cutter rotated around the axis. A cutting insert that can be mounted so that it faces the polygonal rake face that faces the cutter rotation direction of the cutter body and the bottom surface that faces the opposite side of the rake face and faces the cutter rotation direction of the insert mounting seat. It is provided with an insert body in which a polygonal seating surface to be seated and a flank surface arranged around the rake surface and the seating surface are formed, and the insert body is located at the center of the rake surface and the seating surface. A mounting hole through which a clamp screw for mounting the insert body is inserted into the insert mounting seat is opened, and a cutting edge is formed at the intersecting ridgeline portion between the rake face and the flank surface. The flank surface is inclined toward the inside of the insert body from the cutting edge toward the seating surface side, and the rake surface is on the cutting edge side in a cross section perpendicular to the cutting edge. A first inclined surface that inclines linearly toward the seating surface as it moves away from the cutting edge, and a side that is inside the rake surface of the first inclined surface and that is opposite to the seating surface as it moves away from the cutting edge. A second inclined surface that inclines linearly is provided, and in a direction perpendicular to the seating surface, from the seating surface to the upper end of the second inclined surface rather than the height from the seating surface to the cutting edge. It is characterized by a high height.

Further, the blade tip exchange type cutter of the present invention is characterized in that such a cutting insert is detachably attached to an insert mounting seat formed on the outer periphery of the tip portion of a cutter body that is rotated around an axis. ..

In the cutting insert and the cutting edge replaceable cutter configured in this way, the rake face of the cutting insert in a cross section orthogonal to the cutting edge is linearly inclined toward the seating surface side as the cutting edge is separated from the cutting edge. It is provided with a first inclined surface and a second inclined surface inside the rake face of the first inclined surface and inclining linearly to the side opposite to the seating surface as the distance from the cutting edge increases. Since the first and second inclined surfaces have a straight cross section, the thick chips generated in the first half of the cut come into line contact without surface contact, and an increase in cutting resistance can be prevented. ..

In the cutting insert having the above configuration, the height from the seating surface to the upper end of the second inclined surface is higher than the height from the seating surface to the cutting edge in the direction perpendicular to the seating surface. Chips that are thin and tend to stretch can be curled by applying resistance to the upper end of the second inclined surface and sliding them, so that the chips are curled from the first half to the second half of the cut. The curl diameter can be controlled to be substantially constant. Therefore, according to the cutting insert and the cutting edge replaceable cutter configured in this way, the extended chips may be caught between the cutting edge and the work material, or may be clogged on the conveyor when the chips are discharged. You can prevent it from happening.

Here, the rake face includes a flat surface extending linearly parallel to the seating surface in a cross section orthogonal to the cutting edge between the first inclined surface and the second inclined surface. May be good. Since this flat surface also has a straight cross section, it comes into line contact with the chips in the first half of the cut, and does not cause an increase in cutting resistance.

The difference between the height from the seating surface to the cutting edge and the height from the seating surface to the upper end of the second inclined surface in the direction perpendicular to the seating surface is 1.0 mm or less. desirable. If the difference between the height from the seating surface to the cutting edge and the height from the seating surface to the upper end of the second inclined surface is larger as this difference exceeds 1.0 mm, it hits the upper end of the second inclined surface and slides. There is a risk that the chips that come in contact will lose their place and become clogged.

Further, in the cross section orthogonal to the cutting edge, it is desirable that the distance between the cutting edge and the upper end of the second inclined surface in the direction parallel to the seating surface is within the range of 0.5 mm to 5.0 mm. .. If this distance is less than 0.5 mm, chips may still be clogged, while if it is larger than 5.0 mm, the chips generated in the latter half of the cut may hit the second inclined surface and be in sliding contact with each other. There is a risk that the curl diameter cannot be controlled because it will be separated from the rake face.

As described above, according to the present invention, it is possible to prevent the cutting resistance from increasing due to the thick chips generated in the first half of the cut coming into surface contact with the rake face, and it is generated in the second half of the cut. By applying a thin chip to the upper end of the second inclined surface and sliding it, the curl diameter can be controlled to be substantially constant over the entire length of the chip, so that the cutting edge and the work material It is possible to prevent chips from getting caught between the two and the conveyor from clogging.

It is a perspective view which shows one Embodiment of the cutting insert of this invention. It is a top view seen from the direction facing the rake face of the embodiment shown in FIG. It is a side view in the direction of arrow A in FIG. It is a side view in the direction of arrow B in FIG. It is a ZZ cross-sectional view in FIG. It is an enlarged view around the cutting edge of the cross-sectional view shown in FIG. A bottom view showing one embodiment of the cutting edge replaceable cutter of the present invention in which the cutting insert of the embodiment shown in FIGS. 1 to 6 is detachably attached to the insert mounting seat, as viewed from the tip side in the axial direction of the cutter body. is there. It is a side view in the direction of arrow A in FIG. It is a side view in the direction of arrow B in FIG. It is a figure which shows the chip generated by the Example of this invention. It is a figure which shows the chip generated by the comparative example with respect to the Example shown in FIG.

1 to 6 show one embodiment of the cutting insert of the present invention, and FIGS. 7 to 9 show the cutting edge exchange type of the present invention in which the cutting insert of the embodiment is detachably attached to the insert mounting seat. It shows one embodiment of a cutter, and FIGS. 10 and 11 show an embodiment of the present invention based on this embodiment and chips generated by a comparative example with respect to this embodiment.

The cutting insert of the present embodiment includes a polygonal plate-shaped insert body 1 formed of a hard material such as cemented carbide. The insert body 1 has a substantially square plate shape, and more specifically, a square octagon cut out by a straight line perpendicular to the bisector of the two sides of the square where each corner of the square intersects the corner. It is formed in a plate shape.

Further, the insert body 1 is formed in a rotationally symmetric shape by 90 ° around the insert center line C passing through the center of the square, and has a plane orthogonal to each side of the square along the insert center line C. It is formed in a plane-symmetrical shape with respect to a plane including the insert center line C and the above-mentioned bisector.

Of the two polygonal surfaces of the insert body 1, one polygonal surface is a rake face 2, and the other polygonal surface facing the opposite side of the rake face 2 is a seating surface 3, which is a rake. The side surfaces arranged around the surface 2 and the seating surface 3 are referred to as escape surfaces 4. A cutting edge 5 is formed at the intersecting ridgeline portion between the rake face 2 and the flank surface 4, and the flank surface 4 is inclined toward the inside of the insert body 1 from the cutting edge 5 toward the seating surface 3. Therefore, the cutting insert of this embodiment is a positive type cutting insert.

Further, in the central portion of the rake face 2 and the seating surface 3, a mounting hole 6 through which the insert body 1 is inserted and a clamp screw for mounting the insert body 1 to the insert mounting seat is inserted is opened. The mounting hole 6 has a circular cross section centered on the insert center line C, and the inner diameter thereof is gradually reduced from the rake surface 2 toward the seating surface 3 as shown in FIG. 5, and then the seating surface 3 It is formed so as to expand the diameter on the side.

The cutting blade 5 includes a main cutting blade 5a formed on a side portion of the square and a sub cutting blade 5b formed on a portion cut out at a corner portion of the square. The main cutting blade 5a and the secondary cutting blade 5b are located on one plane parallel to the seating surface 3, and the corner portion where the main cutting blade 5a and the secondary cutting blade 5b intersect is rounded by an arc having a small radius. Has been done. The sub cutting edge 5b may be linear or arcuate with a large radius of curvature. Further, the cutting blade 5 may be provided with a honing or a land.

As shown in FIG. 6, the rake face 2 connected to the cutting blade 5 is a first first that is linearly inclined toward the seating surface 3 side toward the cutting blade 5 as the distance from the cutting blade 5 increases. It is provided with an inclined surface 2a and a second inclined surface 2b inside the rake surface 2 of the first inclined surface 2a and inclined linearly to the side opposite to the seating surface 3 as the distance from the cutting edge 5 increases. There is. Further, in the present embodiment, the rake face 2 is flat extending linearly parallel to the seating surface 3 in a cross section orthogonal to the cutting edge 5 between the first inclined surface 2a and the second inclined surface 2b. It has a surface 2c.

Then, as shown in FIG. 6, in the direction perpendicular to the seating surface 3, the height from the seating surface 3 to the upper end of the second inclined surface 2b is higher than the height from the seating surface 3 to the cutting edge 5. Therefore, in the central portion of the rake face 2, a convex portion 2d most protruding in the insert center line C direction is formed inside the second inclined surface 2b, and the upper surface of the convex portion 2d is a seating surface. It is a flat surface parallel to No. 3, and the mounting hole 6 opens at the center of the upper surface of the convex portion 2d. As shown in FIG. 2 in a plan view facing the rake face 2, the upper surface of the convex portion 2d has an outer line having a similar shape that is one size smaller than the outer line (cutting edge 5) of the rake surface 2. There is. The upper surface of the convex portion 2d and the second inclined surface 2b may be connected to each other via a convex curved surface as shown in FIG. 6, or may intersect at an angle.

Here, in the direction perpendicular to the seating surface 3, the difference H between the height from the seating surface 3 to the cutting edge 5 and the height from the seating surface 3 to the upper end of the second inclined surface 2b is 1.0 mm or less. The range is constant over the entire circumference of the cutting blade 5, and in the present embodiment, this difference H is 0.1 mm. Further, in the cross section orthogonal to the cutting blade 5, the distance L between the cutting blade 5 and the upper end of the second inclined surface 2b in the direction parallel to the seating surface 3 is within the range of 0.5 mm to 5.0 mm. It is constant over the entire circumference of the blade 5, and in the present embodiment, this interval L is 2.0 mm.

Further, in the cross section orthogonal to the cutting edge 5, the first inclination angle θ1 formed by the first inclined surface 2a with respect to the plane P parallel to the seating surface 3 is cut in the range of 10.0 ° to 30.0 °. It is constant over the entire circumference of the blade 5, and in the present embodiment, the first inclination angle θ1 is 16.0 °. Further, in the cross section orthogonal to the cutting edge 5, the second inclination angle θ2 formed by the second inclined surface 2b with respect to the plane parallel to the seating surface 3 (for example, the upper surface of the convex portion 2d) is 10.0 ° to It is constant over the entire circumference of the cutting edge 5 within the range of 90.0 °, and in the present embodiment, the second inclination angle θ2 is 40.0 °.

Further, as in the present embodiment, when the flat surface 2c is formed between the first inclined surface 2a and the second inclined surface 2b of the rake face 2, in the cross section orthogonal to the cutting edge 5. The depth D in the direction perpendicular to the seating surface 3 from the cutting edge 5 to the flat surface 2c is preferably within the range of 0.10 mm or more, and is 0.25 mm in the present embodiment.

The replaceable cutting edge cutter to which such a cutting insert is detachably attached includes a disk-shaped cutter body 11 centered on the axis O as shown in FIGS. 7 to 9 by using a metal material such as a steel material. The tip portion (lower portion in FIGS. 8 and 9) of the cutter body 11 has a larger diameter than the rear end portion (lower portion in FIGS. 8 and 9), and an insert mounting seat is formed on the outer periphery of the tip portion. A plurality of 12s are formed at intervals in the circumferential direction, and the cutting inserts of the above embodiment are attached to these insert mounting seats 12.

In the blade tip exchange type cutter configured in this way, the rear end portion of the cutter body 11 is attached to the spindle of the machine tool, and the cutter body 11 is rotated in the cutter rotation direction T around the axis O in the direction perpendicular to the axis O. By being sent out, the work material is subjected to cutting processing such as face milling by the cutting edge 5 of the cutting insert of the above embodiment attached to the insert mounting seat 12.

The same number of concave groove-shaped tip pockets 13 as the insert mounting seats 12 are formed on the outer periphery of the tip of the cutter main body 11 at intervals in the circumferential direction, and the insert mounting seats 12 are formed in the cutter rotation direction of these tip pockets 13. It is formed on the wall surface facing T. In this embodiment, eight chip pockets 13 and insert mounting seats 12 are formed at equal intervals in the circumferential direction.

The insert mounting seat 12 includes a bottom surface facing the cutter rotation direction T, a wall surface extending from the bottom surface toward the cutter rotation direction T side and facing the outer peripheral side of the tip of the cutter main body 11, and a wall surface facing the inner peripheral side of the tip. The bottom surface of the insert mounting seat 12 is inclined so as to face the side opposite to the cutter rotation direction T toward the rear end side of the cutter body 11, and the bottom surface is inserted into the mounting hole 6 of the insert body 1. A screw hole is formed in which the clamp screw 14 is screwed.

On such an insert mounting seat 12, the insert body 1 of the cutting insert has a seating surface 3 facing the bottom surface and two flanks 4 connected to two main cutting blades 5a intersecting one auxiliary cutting blade 5b. The clamp screw 14 is seated in contact with the two wall surfaces and inserted into the mounting hole 6 as described above, and is screwed into the screw hole to be detachably attached. A sheet 15 with a through hole made of an octagonal thin plate-shaped steel material, which is one size smaller than the insert body 1, is interposed between the bottom surface of the insert mounting seat 12 and the seating surface 3 of the insert body 1. Will be done.

In the cutting insert mounted on the insert mounting seat 12 in this way, one auxiliary cutting edge 5b is substantially positioned on a plane perpendicular to the axis O of the cutter body 11, and extends from the auxiliary cutting edge 5b to the outer peripheral side. One main cutting edge 5a is arranged so as to extend toward the rear end side of the cutter body 11, and the cutting edge 5 composed of the main cutting edge 5a and the sub cutting edge 5b performs the above-mentioned cutting process on the work material. Give.

At this time, in the cutting insert and the blade tip exchange type cutter having the above configuration, the rake face 2 of the cutting insert is a straight line toward the seating surface 3 side as the cutting edge 5 side is separated from the cutting blade 5 in the cross section orthogonal to the cutting blade 5. A second inclined surface 2a that inclines in a shape and a second inclined surface that is inside the rake surface 2 of the first inclined surface 2a and inclines linearly to the side opposite to the seating surface 3 as the distance from the cutting edge 5 increases. Since it is provided with an inclined surface 2b and these first and second inclined surfaces have a linear cross section, thick chips generated in the first half of the cut are in line contact without surface contact. Therefore, it is possible to prevent an increase in cutting resistance.

Further, in the cutting insert of the present embodiment, the rake face 2 is linearly parallel to the seating surface 3 in a cross section orthogonal to the cutting edge 5 between the first inclined surface 2a and the second inclined surface 2b. It has an extending flat surface 2c. Therefore, the chips flowing from the first inclined surface 2a also come into contact with the flat surface 2c, but since the flat surface 2c also has a straight cross section, it comes into line contact with the chips and is cut. Even if thick chips come into contact with each other in the first half of the above, the cutting resistance does not increase.

Then, in the cutting insert having the above configuration and the cutting edge replaceable cutter to which the cutting insert is attached, the seating surface 3 is located in the direction perpendicular to the seating surface 3 of the insert body 1 rather than the height from the seating surface 3 to the cutting edge 5. Since the height from to the upper end of the second inclined surface 2b is high, a thin chip generated in the latter half of the cut during the downcut is applied to the upper end of the second inclined surface 2b and slid. It can be brought into contact and given resistance to curl to a small curl diameter.

Therefore, according to the cutting insert and the cutting edge replaceable cutter having the above configuration, the chips in the latter half of the cut, which are thin and tend to extend, are curled to a curl diameter substantially equal to the chips in the first half of the cut to curl the chips. The diameter can be controlled to be substantially constant. Therefore, it is possible to prevent the extended chips from being bitten or being clogged on the conveyor when the chips are discharged.

Here, the difference H between the height from the seating surface 3 to the cutting edge 5 and the height from the seating surface 3 to the upper end of the second inclined surface 2b in the direction perpendicular to the seating surface 3 is as in the present embodiment. It is desirable that it is 1.0 mm or less. If this difference H exceeds 1.0 mm, the chips that come into contact with the upper end of the second inclined surface 2b from the first half to the second half of the cut may lose their place and become clogged.

Further, in the cross section orthogonal to the cutting edge 5, the distance L between the cutting edge 5 and the upper end of the second inclined surface 2b in the direction parallel to the seating surface 3 is 0.5 mm to 5. as in the present embodiment. It is desirable that it is within the range of 0 mm. If the distance L is less than 0.5 mm, chips may be clogged, and conversely, if the distance L is larger than 5.0 mm, the chips generated in the latter half of the cut will be the second inclined surface 2b. There is a risk that the curl diameter cannot be controlled because the rake face 2 is separated from the rake face 2 before it hits the surface and slides into contact with the surface 2.

Now, when the rake face 2 has a flat surface 2c as in the present embodiment, it is desirable that the depth D from the cutting edge 5 is 0.10 mm or more as described above. If the depth D is shallower than 0.10 mm, the chips line-contacting the first inclined surface 2a will come into contact with the flat surface 2c before the curl is sufficiently formed, and the second inclined surface 2b May not be able to come into contact with.

However, in the present embodiment, the rake face 2 thus includes the flat surface 2c between the first inclined surface 2a and the second inclined surface 2b, but the flat surface 2c is not formed and the first The inclined surface 2a and the second inclined surface 2b may intersect in a V-shaped cross section, or may be connected by a concave curved surface having a small radius of curvature.

Next, examples of the present invention will be given to demonstrate the effects of the present invention. In this embodiment, face milling was performed with a cutting edge replaceable cutter to which a cutting insert based on the above embodiment was attached, and chips generated at that time were photographed. The result is shown in FIG. In addition, in FIG. 10 and FIG. 11 described below, the right side of the chip in the figure is the first half side of the cut in which the cutting edge 5 bites the work material, and the left side of the chip in the figure is the work piece by the cutting blade 5. It is the latter half of the notch that comes out of the material.

Here, the material of the work material is SCM440, and the cutting conditions are cutting speed vc: 200 m / min, axial cutting depth ap: 0.2 mm, feed amount per blade fz: 0.2 mm / t, The cutting depth in the radial direction was 100 mm (center cut), and the cutting was dry. Further, only one cutting insert was attached to the cutter body 11 to perform cutting.

Further, as a comparative example with respect to this embodiment, the same cutting conditions as in the embodiment are provided by a cutting edge replaceable cutter equipped with a cutting insert in which the height from the seating surface to the upper end of the second inclined surface is lower than the height of the cutting edge. The front milling was performed with, and the chips generated at that time were photographed. The result is shown in FIG. In this comparative example, the difference between the height from the seating surface to the cutting edge and the height from the seating surface to the upper end of the second inclined surface is 0.258 mm in the direction perpendicular to the seating surface. Was expensive.

Further, in this comparative example, in the cross section orthogonal to the cutting edge, the distance between the cutting edge and the upper end of the second inclined surface in the direction parallel to the seating surface is 2.127 mm, which is parallel to the seating surface of the first inclined surface. The first tilt angle formed with respect to a flat surface is 14.299 °, and the first tilt surface is linear from the cutting edge to 0.873 mm parallel to the seating surface, but inside the rake face. Then, it formed a concave curved surface with a radius of 1.895 mm and reached the upper end of the second inclined surface.

From the results shown in FIGS. 10 and 11, first, in the chips of the comparative example, the curl diameter (diameter) of the chips gradually increased from the first half to the second half of the incision, and at the end of the largest incision, the diameter was 7.6 mm. The diameter at the beginning of the cut reached nearly three times the diameter of 2.6 mm. On the other hand, the chips of the example have a small diameter of 2.1 mm even at the beginning of cutting, and have a diameter of 3.1 mm even at the end of cutting, and the curl diameter is large at about 1.4 times, which is less than half the diameter of the comparative example. It was suppressed.

1 Insert body 2 Scoop surface 2a First inclined surface 2b Second inclined surface 2c Flat surface 2d Convex part 3 Seating surface 4 Escape surface 5 Cutting blade 5a Main cutting blade 5b Secondary cutting blade 6 Mounting hole 11 Cutter body 12 Insert mounting Seat 13 Chip pocket 14 Clamp screw 15 Seat C Insert centerline H Height from seating surface 3 to cutting edge 5 in the direction perpendicular to seating surface 3 and height from seating surface 3 to the upper end of the second inclined surface 2b Difference L Spacing between the cutting edge 5 and the upper end of the second inclined surface 2b in the cross section orthogonal to the cutting edge 5 in the direction parallel to the seating surface θ1 First inclination angle θ2 Second inclination angle O Cutter body 11 Axis T Cutter rotation direction

Claims (5)

A cutting insert that can be detachably attached to the insert mounting seat formed on the outer circumference of the tip of the cutter body of a cutter body with a replaceable cutting edge that rotates around the axis.
A polygonal rake face facing the cutter rotation direction of the cutter body and a polygonal seating surface facing the opposite side of the rake face and facing the bottom surface of the insert mounting seat facing the cutter rotation direction. , With an insert body formed with these rake faces and flanks arranged around the seating surface.
At the center of the rake face and the seating surface, a mounting hole is opened through which the insert body is inserted and a clamp screw for mounting the insert body to the insert mounting seat is inserted.
A cutting edge is formed at the intersecting ridge line portion between the rake face and the flank surface, and the flank surface is inclined toward the inside of the insert body from the cutting edge toward the seating surface side.
The rake face has a first inclined surface that is linearly inclined toward the seating surface side as the cutting surface is separated from the cutting edge in a cross section orthogonal to the cutting blade, and the first inclined surface. It is provided with a second inclined surface that is inside the rake surface and inclines linearly to the side opposite to the seating surface as the distance from the cutting edge increases.
A cutting insert characterized in that, in a direction perpendicular to the seating surface, the height from the seating surface to the upper end of the second inclined surface is higher than the height from the seating surface to the cutting edge. The rake face is characterized by having a flat surface extending linearly in parallel with the seating surface in a cross section orthogonal to the cutting edge between the first inclined surface and the second inclined surface. The cutting insert according to claim 1. In the direction perpendicular to the seating surface, the difference between the height from the seating surface to the cutting edge and the height from the seating surface to the upper end of the second inclined surface is 1.0 mm or less. The cutting insert according to claim 1 or 2. In the cross section orthogonal to the cutting edge, the distance between the cutting edge and the upper end of the second inclined surface in the direction parallel to the seating surface is within the range of 0.5 mm to 5.0 mm. The cutting insert according to any one of claims 1 to 3. The cutting insert according to any one of claims 1 to 4 is detachably attached to an insert mounting seat formed on the outer periphery of the tip of a cutter body that is rotated around an axis. Blade tip exchange type cutter.