Cutting insert

Abstract

The present application provides a cutting insert which can use a plurality of intervals of cutting edges, and can prevent unused cutting edges of adjacent intervals from being damaged by swarf discharged from cutting edges of intervals in use. An edge line 10 at which an upper surface 4 and a peripheral surface 6 intersect is divided into a plurality of intervals AB, BC, CD,... Each of the plurality of intervals AB, BC, CD,..., for example, interval AB, includes one sub cutting edge 11 and one main cutting edge 13 longer than the sub cutting edge 11. The main cutting edge 13 is inclined at an angle α and moves away from a lower surface 5 as it moves away from the sub cutting edge 11. In a direction from the main cutting edge 13 toward a mounting hole 9, a relief of the upper surface 4 does not change in an up-down direction opposite the upper surface 4 and the lower surface 5, or sinks from the upper surface 4 toward a lower side z2 where the lower surface 5 is located.

Description

Technical Field

[0001] This invention relates to cutting blades. Background Technology

[0002] In milling tools such as face milling cutters, when the main cutting edge is mounted on the tool body, the sharpness is improved by increasing the tilt angle of the main cutting edge when viewed from the side (hereinafter referred to as "axial tilt angle"). To increase the axial tilt angle, the main cutting edge of the cutting insert used on milling tools is generally set to a shape that is lower right as it moves away from the secondary cutting edge, or a shape parallel to the lower surface (for example, Patent Document 1).

[0003] In single-sided cutting inserts, if the insert has a side that is inclined relative to the central axis of the mounting hole, the upper surface can be tilted when the insert is mounted on the tool body, thereby increasing the axial apparent tilt angle within the clearance angle range of the side. In such cutting inserts, the main cutting edge is often seen to be inclined to the upper right (e.g., Patent Documents 2 and 3).

[0004] On the other hand, for double-sided cutting inserts, since the side face is parallel to the central axis of the mounting hole, if the upper surface is tilted relative to the axial direction of the milling tool to increase the axial tilt angle, the clearance surface of the secondary cutting edge will affect the cutting material. When it is desirable to increase the axial tilt angle, the primary cutting edge of a double-sided cutting insert will almost never adopt a shape that tilts upwards to the right.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2015-128816

[0008] Patent Document 2: Japanese Patent Application Publication No. 2009-202324

[0009] Patent Document 3: Japanese Patent Application Publication No. 2011-121131

[0010] Technical issues

[0011] If the main cutting edge is sloping downwards to the right, the waste material discharged from the cutting edge of the section in use can easily come into contact with the cutting edges of other adjacent sections on the right (see reference). Figure 10 If the cutting edge in the adjacent section to the right is an unused cutting edge rather than a used cutting edge, the unused cutting edge will be damaged due to scrap. If the cutting edge is damaged before use, it will be unusable, resulting in economic loss.

[0012] Therefore, the present invention aims to provide a cutting blade that can use multiple sections of cutting edges, and can prevent unused cutting edges in adjacent sections from being damaged by waste material discharged from the cutting edges of the sections in use. Summary of the Invention

[0013] One aspect of the invention provides a cutting insert having an upper surface, a lower surface opposite to the upper surface, a circumferential side surface connecting the upper and lower surfaces, and a mounting hole penetrating the upper and lower surfaces. The upper surface is rotationally symmetrical about a central axis passing through the center of the upper surface and the center of the lower surface, and the lower surface is formed with a shape substantially the same as the upper surface. The edges where the upper surface and the circumferential side surface intersect are divided into a plurality of intervals, each of the plurality of intervals including a secondary cutting edge and a primary cutting edge longer than the secondary cutting edge. The primary cutting edge is inclined in a manner that moves away from the secondary cutting edge and away from the lower surface. In the direction from the primary cutting edge toward the mounting hole, the undulation of the upper surface does not change in the vertical direction opposite to the upper and lower surfaces, or sinks from the upper surface to the lower surface.

[0014] Another aspect of the invention provides a cutting insert having an upper surface, a lower surface opposite to the upper surface, a peripheral surface connecting the upper and lower surfaces, and a mounting hole penetrating the upper and lower surfaces. The upper surface is rotationally symmetrical about a central axis passing through the center of the upper surface and the center of the lower surface, and the lower surface is formed with a shape substantially the same as the upper surface. The ridge line where the upper surface and the peripheral surface intersect is divided into multiple intervals, each of the multiple intervals including a secondary cutting edge and a primary cutting edge longer than the secondary cutting edge. The primary cutting edge is inclined away from the lower surface as it moves away from the secondary cutting edge. The upper surface includes a flat surface parallel to an imaginary plane orthogonal to the central axis passing through the center of the upper surface and the center of the lower surface, a chip-ejection surface located on the outer periphery of the flat surface and inclined at a first angle relative to the imaginary plane, and a ridge surface located between the chip-ejection surface and the primary cutting edge and inclined at a second angle less than the first angle relative to the imaginary plane. In a top view viewed along the central axis, the length of the shortest distance from the primary cutting edge, which is formed as a straight line, to the outer edge of the mounting hole is used as a reference value. In any cross-section cut orthogonal to the main cutting edge at any position, measure the distance from the imaginary intersection point of the imaginary straight line obtained by extending the contour of the edge into a straight line and the flat surface along a direction orthogonal to the central axis to the main cutting edge. Set the measured length as a variable value that varies according to the cut position of the arbitrary cross-section. All variable values ​​are greater than half of the reference value.

[0015] The axial tilt angle is determined by three factors: the tilt angle of the primary cutting edge, the radial tilt angle, and the entry angle, as observed from the side of the milling tool. In cutting inserts, even if the primary cutting edge tilts upwards to the right, the axial tilt angle can be balanced by increasing the negative radial tilt angle in the negative direction. These aspects share a common feature: in double-sided cutting inserts with roughly the same upper and lower surface shapes, the primary cutting edge tilts upwards to the right, moving away from the lower surface as it moves away from the secondary cutting edge, and the shape formed by the upper surface easily maintains clearance with the cutting material. For the former, since the undulations of the upper surface closer to the center have no rising portion even if there is a downward portion, the height towards the center of the upper surface is lower. Because the upper surface has no bulge, it easily maintains clearance with the cutting material. For the latter, if the upper surface has a bulge, the variable value will decrease, but whether on the low depth of cut side or the high depth of cut side of the primary cutting edge, the variable value exceeds half of the reference value. Because the bulge of the upper surface is small, it easily maintains clearance with the cutting material. In these ways, even if the radial tilt angle is increased in the negative direction, it is difficult for chips to get stuck between the upper surface and the cutting material. Therefore, it is possible to avoid damage to the unused cutting edges in the adjacent section after using the main cutting edge tilted to the upper right due to the waste material discharged from the cutting edge in the section in use.

[0016] In the aforementioned respect, in a top view viewed from the upper surface, the angle between the secondary cutting edge and the primary cutting edge can be greater than or equal to 140° and less than or equal to 155°.

[0017] Based on this, the approach angle is greater than or equal to 25° and less than or equal to 40°, which is less than the usual 45°. Even if the main cutting edge is tilted to the upper right, the axial apparent tilt angle can be made positive by reducing the approach angle to achieve balance.

[0018] In the aforementioned respect, in the vertical direction relative to the upper and lower surfaces, with the position closest to the lower surface in the main cutting edge as the lowest point and the position farthest from the lower surface as the highest point, the second imaginary straight line passing through the lowest and highest points can be inclined at an angle greater than or equal to 1° and less than or equal to 10° relative to the imaginary plane orthogonal to the central axis passing through the center of the upper and lower surfaces.

[0019] In this respect, since the inclination of the main cutting edge is greater than or equal to 1°, the scrap discharged from the main cutting edge can deviate from the cutting edge of the adjacent section on the right at a sufficient angle. The greater the inclination of the main cutting edge, the more the cutting starts from the side with a higher depth of cut relative to the material being cut. In this respect, since the inclination of the main cutting edge is less than or equal to 10°, excessive load on the main cutting edge can be avoided on the side with a higher depth of cut.

[0020] In the aforementioned respects, the upper surface exhibits hexafold or quintufold symmetry about the central axis.

[0021] Accordingly, the excellent effects of the present invention can be achieved in cutting inserts with multiple cutting edges on both sides, which offer superior economic efficiency.

[0022] The present invention provides a cutting insert that can use multiple sections of cutting edges and can prevent unused cutting edges in adjacent sections from being damaged by waste material discharged from the cutting edges in the sections in use. Attached Figure Description

[0023] Figure 1 This is a side view of a milling tool with a cutting insert provided in an embodiment of the present invention mounted.

[0024] Figure 2 When viewed from a direction that approximates a straight line on the upper surface... Figure 1 The side view of the milling tool shown.

[0025] Figure 3 Viewed from the side of the secondary cutting edge Figure 1 The front view of the milling tool shown.

[0026] Figure 4 This is a perspective view of a cutting blade provided in an embodiment of the present invention.

[0027] Figure 5 Viewed from the first side Figure 4 The side view of the cutting blade is shown.

[0028] Figure 6 Viewed from the top surface side Figure 4 The top view of the cutting blade shown.

[0029] Figure 7 It is along Figure 6 A cross-sectional view of the low depth of cut side of line VII-VII.

[0030] Figure 8 It is along Figure 6 A cross-sectional view of the center of the main cutting edge along line VIII-VIII.

[0031] Figure 9 It is along Figure 6 A cross-sectional view of the high depth of cut side of the IX-IX line.

[0032] Figure 10 This is a side view of the cutting blade of the present invention and a side view of a conventional cutting blade, showing the waste material discharged from the main cutting edge in comparison.

[0033] Explanation of main component symbols Milling tool 1

[0034] Tool Body 2

[0035] Cutting insert 3

[0036] upper surface 4

[0037] lower surface 5

[0038] 6 sides

[0039] Mounting hole 9

[0040] Edge 10

[0041] Secondary cutting edge 11

[0042] Angular cutting edge (second angle) 12

[0043] Main cutting edge 13

[0044] Connecting part 14

[0045] Edge surface (1st chip surface) 41

[0046] Chip-exiting surface (second chip-exiting surface) 42

[0047] Flat surface 43

[0048] Side view 61, 61, 63

[0049] Lowest point 131

[0050] Highest point 132

[0051] Clearance surface 611 of the secondary cutting edge

[0052] Clearance surface 612 of the main cutting edge

[0053] First angle A to F

[0054] Interval AB to FA

[0055] The rotary axis AX of the milling tool

[0056] Inclination i as observed from the side of the milling tool

[0057] Angular axis tilt angle j

[0058] Radial tilt angle k

[0059] Baseline value L0

[0060] Variable values ​​L1, L2, L3

[0061] Central axis O

[0062] Intersection points P1, P2, P3

[0063] radial r

[0064] Imaginary plane s intersecting with the secondary cutting edge

[0065] The imaginary lines v1, v2, v3 are obtained by extending the contour of the facets through the imaginary line passing through the imaginary intersection point of the extension of the secondary cutting edge and the extension of the primary cutting edge t.

[0066] (First imaginary line)

[0067] The imaginary straight line passing through the lowest and highest points...

[0068] Line (Second Imaginary Line)

[0069] Imaginary plane xy

[0070] Up and down direction (axial direction of the cutting tool) z

[0071] upper z1

[0072] lower z2

[0073] Inclination angle α of the main cutting edge

[0074] The inner β between the secondary cutting edge and the primary cutting edge

[0075] angle 1st angle γ

[0076] second angle δ

[0077] Circumferential direction θ Detailed Implementation

[0078] The preferred embodiments of the present invention will now be described with reference to the accompanying drawings. It should be noted that items labeled with the same reference numerals in the figures have the same or identical structure. For example... Figure 5 As shown, one feature of the cutting insert 3 provided in one embodiment of the present invention is that the cutting insert 3 has a double-sided specification with the same shape for its upper surface 4 and lower surface 5, and the main cutting edge 13 tilts to the upper right as it moves away from the lower surface 5 from the lower cutting depth side to the higher cutting depth side. Since the waste is discharged to the upper right rather than the lower right, therefore... Figure 10 As shown, this can prevent damage to the cutting edge in the adjacent section on the right.

[0079] With the upper surface 4 and lower surface 5 being approximately flat, the axial apparent tilt angle j is determined based on the tilt angle i of the main cutting edge 13. Figure 2 As shown), radial tilt angle k ( Figure 3 (as shown) and the angle of entry (180°-β) ( Figure 6The inclination angle i of the main cutting edge 13 is determined by three factors (as shown). It is observed from the upper surface 4 of the cutting insert 3 in an approximately straight direction when the cutting insert 3 is mounted on the tool body 2. If the main cutting edge 13 of the cutting insert 3 is tilted to the upper right, the inclination angle i of the main cutting edge 13 becomes smaller. For a milling tool 1 with the cutting insert 3 mounted, in order to make the axial apparent inclination angle j a positive angle, the radial inclination angle k is increased in the negative direction, and the approach angle (180°-β) is reduced to achieve balance.

[0080] If the radial tilt angle k is further increased in the negative direction, scrap material can easily get stuck between the upper surface 4 of the cutting insert 3 and the cutting material. Figure 4 , Figures 7 to 9 As shown, in one embodiment of the present invention, the cutting blade 3 does not have a convex surface or the like forming a protrusion on the upper surface 4, thus ensuring a sufficient clearance between the upper surface 4 and the cutting material. Therefore, even if the radial tilt angle k is increased in the negative direction, waste material is easily discharged. The structures will now be described in detail with reference to the accompanying drawings.

[0081] Figure 1 and Figure 2 This is a side view of a milling tool 1 with a cutting blade 3 provided in an embodiment of the present invention mounted. Figure 3 Viewed from the side of secondary cutting edge 11 Figure 1 The front view of the milling tool 1 shown. Figures 1 to 3 As shown, for example, the milling tool 1 is a front milling cutter tool, having a tool body 2 formed in the shape of a disc and a plurality of replaceable cutting inserts 3 mounted on the outer periphery of the tool body 2.

[0082] The following is about Figure 1 The definition of the axial tilt angle j shown is explained. An imaginary plane parallel to the upper surface 4 and intersecting all secondary cutting edges 11 is defined as s( Figure 5 As shown). Let t be the imaginary intersection point of the imaginary line obtained by extending the secondary cutting edge 11 projected onto the imaginary plane s and the imaginary line obtained by extending the primary cutting edge 13 projected onto the imaginary plane s. Figure 6 As shown). Let the imaginary straight line passing through the imaginary intersection point t and orthogonal to the rotation axis AX of the milling tool 1 be u ( Figure 2 As shown). The axial tilt angle j is the angle j between the main cutting edge 13 and the rotation axis AX of the milling tool, as observed along the imaginary straight line u (where the rotation axis AX overlaps with the imaginary intersection point t). Figure 1 (As shown).

[0083] The tilt angle i of the main cutting edge 13, observed from the upper surface 4 of the cutting edge 3 in an approximately straight direction with the cutting insert 3 mounted on the tool body 2. Figure 2(As shown) represents a negative angle greater than or equal to -14° and less than or equal to -6°. The example shown is -10°. For milling tool 1, even if the tilt angle i is small, in order to make the axial apparent tilt angle j a positive angle, the radial tilt angle k, which is a negative angle, is increased in the negative direction, and the approach angle (180° - β) is decreased. Figure 6 (As shown) to achieve balance. The radial tilt angle k is preferably a negative angle greater than or equal to -30° and less than or equal to -10°. In the illustrated example, the radial tilt angle k is -15°. The angle of entry (180°-β) is preferably greater than or equal to 25° and less than or equal to 40°. In the illustrated example, the angle of entry (180°-β) is 30°.

[0084] Figure 4 This is a perspective view of a cutting blade 3 provided in an embodiment of the present invention. Figure 4 As shown, the cutting insert 3 has an upper surface 4, a lower surface 5 opposite to the upper surface 4, a peripheral surface 6 connecting the upper surface 4 and the lower surface 5, and a mounting hole 9 penetrating the upper surface 4 and the lower surface 5. The central axis of the mounting hole 9 coincides with the central axis O of the cutting insert 3, which passes through the center of the upper surface 4 and the center of the lower surface 5.

[0085] In the following description, the direction parallel to the axial direction of the central axis O is referred to as the vertical direction z. The upper surface 4 and the lower surface 5 are opposite each other in the vertical direction z. The side of the upper surface 4 viewed from the lower surface 5 is called the upper side z1, and the side of the lower surface 5 viewed from the upper surface 4 is called the lower side z2. Furthermore, the direction orthogonal to the central axis O is called the radial direction r of the cutting tool 3, and the direction along the circumference centered on the central axis O is called the circumferential direction θ of the cutting tool 3.

[0086] The cutting insert 3 is a double-sided cutting insert capable of flipping the upper surface 4 and the lower surface 5 for use, with the lower surface 5 having a shape substantially the same as the upper surface 4. In the milling tool 1, the cutting insert 3 can be mounted on the tool body 2 with the lower surface 5 fixed or with the upper surface 4 fixed. Therefore, the upper surface 4 will be described in detail, and the description of the lower surface 5 will be omitted.

[0087] The upper surface 4 is rotationally symmetric about the central axis O. Preferably, it forms a six-fold or five-fold symmetry. The outline of the upper surface 4 is an approximate polygon with multiple first angles A, B, C… In the illustrated example, the upper surface 4 forms a six-fold symmetry (60° symmetry) about the central axis O, forming an approximate regular hexagon (see reference). Figure 6 The cutting insert 3 has multiple cutting edges 11-13 on both sides, so it is economical.

[0088] The edge 10 where the upper surface 4 intersects the peripheral surface 6 is divided into multiple intervals (sides of the polygon) AB, BC, CD... corresponding one-to-one with multiple first angles A, B, C... In each of the multiple intervals AB, BC, CD..., a secondary cutting edge 11, an angular cutting edge 12, and a primary cutting edge 13 are formed. In other words, each of the multiple intervals AB, BC, CD... includes a set of cutting edges 11 to 13, and a set of cutting edges 11 to 13 includes one secondary cutting edge 11, one angular cutting edge 12, and one primary cutting edge 13.

[0089] Specifically, the interval AB includes a secondary cutting edge 11, a corner cutting edge 12, and a primary cutting edge 13. The secondary cutting edge 11 is adjacent to the first corner A corresponding to the interval AB. The corner cutting edge 12 is adjacent to the secondary cutting edge 11 from the opposite side of the corresponding first corner A. The primary cutting edge 13 is adjacent to the corner cutting edge 12 and extends toward another first corner B adjacent to the first corner A. The interval AB may also include a connecting portion 14, which is adjacent to the primary cutting edge 13 from the opposite side of the secondary cutting edge 11, i.e., the side with the highest cutting depth, and connects the adjacent first corner B on the right side with the primary cutting edge 13.

[0090] The primary cutting edge 13 is the longest among cutting edges 11, 12, and 13, and is longer than the secondary cutting edge 11 and the corner cutting edge 12. The corner cutting edge 12 is curved in an arc shape when viewed from the upper surface 4. The secondary cutting edge 11 is located on the opposite side of the primary cutting edge 13, separated from the corner cutting edge 12. The secondary cutting edge 11 has the function of reducing the roughness of the machined bottom surface and is also called a finishing edge. With the cutting insert 3 mounted on the tool body 2, the secondary cutting edge 11 is positioned in a direction approximately orthogonal to the rotation axis AX of the milling tool 1. With the cutting insert 3 mounted on the tool body 2, the primary cutting edge 13 is positioned further away from the rotation axis AX of the cutting tool 1 than the secondary cutting edge 11.

[0091] In the following description, sometimes “angle A, B, C…” is simply referred to as “angle A, B, C…”, sometimes “angle cutting edge 12” is referred to as “angle 2 12”, sometimes “another angle 1” adjacent to “the angle 1 corresponding to the interval” is referred to as “the angle 1 adjacent to the right”, sometimes “the angle 1 corresponding to the interval” is referred to as the “starting point” of the interval, and sometimes “another angle 1” adjacent to “the corresponding angle 1” is referred to as the “ending point” of the interval.

[0092] Similar to interval AB, each of intervals BC, CD, DE… includes a secondary cutting edge 11 adjacent to the first angle B, C, D… corresponding to that interval BC, CD, DE…, an angular cutting edge 12 adjacent to the secondary cutting edge 11 from the opposite side of the corresponding first angle B, C, D…, a main cutting edge 13 adjacent to the angular cutting edge 12 and extending toward the adjacent first angle C, D, F… on the right, and a connecting portion 14 connecting the right end of the main cutting edge 13 and the adjacent first angle C, D, F… on the right. The secondary cutting edges 11, angular cutting edges 12, main cutting edges 13, and connecting portions 14 formed in intervals AB, BC, CD… are arranged counterclockwise along the circumferential direction θ of the cutting insert 3 in this order.

[0093] The upper surface 4 includes an imaginary plane xy (parallel to the central axis O of the cutting blade 3). Figure 5 The planar surface 43 (as shown), the chip-ejecting surface 42 on the outer periphery of the planar surface 43, and the edge surface 41 between the chip-ejecting surface 42 and the main cutting edge 13. The edge surface 41 can also be called the first chip-ejecting surface, the chip-ejecting surface 42 can be called the second chip-ejecting surface, and the imaginary plane xy can be called the imaginary horizontal plane.

[0094] The circumferential surface 6 connecting the upper surface 4 and the lower surface 5 is parallel to the central axis O of the cutting insert 3. That is, the cutting insert 3 is a negative-type cutting insert, with the clearance angle of its secondary cutting edge 11 and primary cutting edge 13 forming 0°. The circumferential surface 6 is divided into multiple sides 61, 62, 63… corresponding one-to-one with multiple intervals AB, BC, CD… In the illustrated example, the circumferential surface 6 is divided into sides 61 to 66, numbered 1 to 6.

[0095] Each side (e.g., the first side 61) includes a clearance surface 611 of the secondary cutting edge 11 adjacent to the secondary cutting edge 11 and a clearance surface 612 of the main cutting edge 13 adjacent to the main cutting edge 13. In the circumferential direction θ of the cutting insert 3, the clearance surfaces 611 of the secondary cutting edge 11 and 612 of the main cutting edge 13 are arranged alternately. In the illustrated example, the clearance surfaces 611 and 612 are respectively formed as planes rather than curved surfaces. The connecting portion 14 may be located on the same plane as the clearance surface 612 of the main cutting edge 13, or it may be located on a different plane.

[0096] Figure 5 Viewed from the first side 61 Figure 4 A side view of the cutting blade shown. (As shown) Figure 5 As shown, in each interval (e.g., interval AB), the main cutting edge 13 formed in that interval tilts upwards and to the right, moving away from the lower surface 5 as it moves away from the secondary cutting edge 11 formed in that interval. In the vertical direction z, the position of the main cutting edge 13 closest to the lower surface 5 is taken as the lowest point 131, and the position farthest from the lower surface 5 is taken as the highest point 132.

[0097] Let α represent the angle of inclination of the imaginary straight line w passing through the lowest point 131 and the highest point 132 relative to the imaginary plane xy orthogonal to the central axis O. The angle α is preferably greater than or equal to 1° and less than or equal to 10°. If the angle α is greater than or equal to 1°, the scrap discharged from the main cutting edge 13 is sufficiently distanced from the adjacent first angle on the right (first angle B in the illustrated example). If the angle α is less than or equal to 10°, excessive load is prevented on the main cutting edge 13 on the high depth of cut side away from the secondary cutting edge 11.

[0098] Figure 6 It is observed from one side of the upper surface 4 along the central axis O. Figure 4 The diagram shows a top view of the cutting insert 3. In the illustrated example, the secondary cutting edge 11 and the primary cutting edge 13 are both formed as straight lines in the top view. In the top view, the angle (interior angle) β formed by the secondary cutting edge 11 and the primary cutting edge 13 is preferably greater than or equal to 140° and less than or equal to 155°. Since the approach angle (180° - β) is greater than or equal to 25° and less than or equal to 40°, which is less than the usual 45°, even if the primary cutting edge 13 is tilted to the upper right in the side view, the axial apparent tilt angle j can be made positive to achieve balance.

[0099] Figures 7 to 9 They are along Figure 6 The cross-sectional views of lines VII-VII, VIII-VIII, and IX-IX. Specifically, Figure 8 This is a cross-sectional view obtained by cutting the cutting insert 3 at the center of the main cutting edge 13, which is equidistant from the secondary cutting edge 11 and the connecting part 14, in a manner orthogonal to the main cutting edge 13. Figure 7 This is a cross-sectional view obtained by cutting the cutting insert 3 at a position closer to the secondary cutting edge 11 than the center, in a manner orthogonal to the main cutting edge 13. Figure 9 This is a cross-sectional view obtained by cutting the cutting insert 3 at a position further away from the secondary cutting edge 11 at the high depth of cut, in a manner orthogonal to the main cutting edge 13.

[0100] like Figures 7 to 9 As shown, the cross-sectional profile of facet 41 is a straight line. Similarly, the cross-sectional profile of chip-ejecting facet 42 is a straight line. Figure 7 As shown, the chip-exit surface 42 is inclined at a first angle θ1 relative to the imaginary plane xy orthogonal to the central axis O. The edge surface 41 is inclined at a second angle θ2 relative to the virtual plane xy, which is less than the first angle θ1.

[0101] like Figure 5 and Figure 8As shown, in the direction of the main cutting edge 13 toward the mounting hole 9, regarding the undulation of the upper surface 4, the edge face 41 and the chip-ejecting face 42 continuously sink from the upper surface 4 to the lower surface 5, while the flat surface 43 does not change along the vertical direction z. That is, when approaching the central axis O along the radial direction r of the cutting insert 3, the undulation of the upper surface 4 will not rise even if it sinks. The closer to the center, the lower the height of the upper surface 4.

[0102] It should be noted that in this invention, the flat surface 43 is not limited to a strictly flat surface; it can also have slight irregularities without affecting waste discharge performance. Figure 6 In the example shown, Arabic numerals from "1" to "6" and circular markings separating the numerals are engraved on the flat surface 43. For example, the height of the upper surface 4 may decrease slightly in the vertical direction z as it enters the engraving formed by the fine recesses, and increase slightly in the vertical direction z as it exits the engraving. Such a method does not affect the spirit of the invention and is, of course, included within the scope of this invention.

[0103] The undulations of the upper surface 4 will be explained in more detail below. For example... Figures 7 to 9 As shown, the imaginary lines v1, v2, v3... obtained by extending the contour of the edge 41 intersect the flat surface 43 at the imaginary intersection points P1, P2, P3... In each sectional view, along the direction orthogonal to the central axis O (i.e., along... Figure 6 Along lines VII-VII, VIII-VIII, and IX-IX, measure the distances from imaginary intersection points P1, P2, P3… to the main cutting edge 13, and denote the lengths as L1, L2, L3…

[0104] The position of the main cutting edge 13 is determined according to the low depth of cut side (refer to...). Figure 7 ), Central Department (refer to) Figure 8 ), high depth of cut side (refer to) Figure 9 The sequence gradually rises and moves away from the flat surface 43. Therefore, in Figures 7 to 9 In this context, L1 < L2 < L3. The lengths L1, L2, L3... are variable values ​​that vary depending on the cut-off position of any cross-section.

[0105] The variable values ​​L1, L2, L3… have the property of decreasing when there is a bulge on the upper surface 4. When… Figure 6 When the shortest distance L0 from the main cutting edge 13 to the outer edge of the mounting hole 9 in the top view is used as the reference value, since the bulge on the upper surface 4 of the cutting insert 3 is small, all the variable values ​​L1, L2, L3... are greater than half of the reference value L0. In the example shown, (L1>L0×0.5) and (L2>L0×0.5) and (L3>L0×0.5).

[0106] The cutting blade 3, configured as described above in one embodiment of the present invention, is as shown in the reference. Figure 5 The main cutting edge 13 tilts upwards and to the right as it moves away from the lower surface 5 from the low depth of cut side to the high depth of cut side. Figure 10 As shown, in existing cutting inserts, because the main cutting edge is tilted to the lower right, waste is discharged to the lower right, which may damage the cutting edges of adjacent sections. In contrast, the cutting insert 3 of the present invention discharges waste to the upper right, so it can prevent damage to the cutting edges of adjacent sections even if the cutting edges of adjacent sections are not used.

[0107] Furthermore, as referenced Figure 5 and Figures 7 to 9 The cutting insert 3 has a smaller bulge on its upper surface 4, making it easier to ensure a clearance between the upper surface 4 and the cutting material. Since scrap is less likely to get stuck between the upper surface 4 and the cutting material, the radial tilt angle k can be increased in the negative direction. The angle β between the secondary cutting edge 11 and the primary cutting edge 13 is greater than or equal to 140° and less than or equal to 155°. Therefore, in the milling tool 1 equipped with the cutting insert 3, the approach angle (180°﹣β) is greater than or equal to 25° and less than or equal to 40°, which is less than the usual 45°.

[0108] For reference Figure 2 and Figure 5 As stated above, if the main cutting edge 13 tilts to the upper right, the tilt angle i of the main cutting edge 13 as observed from the side of the milling tool 1 becomes smaller, but the cutting insert 3 is designed to make... Figure 1 The axial tilt angle j shown is a positive angle. The radial tilt angle k, which is a negative angle, is increased in the negative direction, and the infeed angle (180°﹣β) is reduced to achieve balance. In the cutting insert 3, which has multiple cutting edges on both sides and is economical, since the main cutting edge 13 tilted to the upper right can be used, it is possible to prevent the cutting edges 11 to 13 of adjacent unused sections (e.g., section BC) from being damaged by waste material discharged from the main cutting edge 13 of the used section (e.g., section AB).

[0109] The embodiments described above are for the purpose of facilitating understanding of the present invention and are not intended to limit the scope of the invention. The elements, configurations, materials, conditions, shapes, and dimensions of the embodiments are not limited to those illustrated and can be appropriately modified. Furthermore, the various structures shown in different embodiments can be partially substituted or combined. For example, the cutting insert of the present invention can be applied to a milling tool 1 with reverse rotation direction. In this case, the other first angle adjacent to the corresponding first angle is not adjacent to the right side of the corresponding first angle but to the left side.

Claims

1. A cutting blade having an upper surface, a lower surface opposite to the upper surface, a peripheral surface connecting the upper surface and the lower surface, and a mounting hole penetrating the upper surface and the lower surface; The upper surface is rotationally symmetrical about a central axis passing through the center of the upper surface and the center of the lower surface, and the lower surface is formed to have approximately the same shape as the upper surface; The edge line where the upper surface and the peripheral side intersect is divided into multiple adjacent intervals, each of the multiple adjacent intervals including a secondary cutting edge and a main cutting edge that is longer than the secondary cutting edge; In each of the intervals, the secondary cutting edge and the primary cutting edge are arranged in the same order along a circumference centered on the central axis, in a counterclockwise direction from one interval to its adjacent interval. The main cutting edge is inclined to the upper right and is inclined in a manner that moves away from the lower surface as it moves away from the secondary cutting edge; In the direction of the main cutting edge toward the mounting hole, the undulation of the upper surface does not change in the vertical direction relative to the upper and lower surfaces, or sinks from the upper surface to the lower surface.

2. A cutting blade having an upper surface, a lower surface opposite to the upper surface, a peripheral surface connecting the upper surface and the lower surface, and a mounting hole penetrating the upper surface and the lower surface; The upper surface is rotationally symmetrical about a central axis passing through the center of the upper surface and the center of the lower surface, and the lower surface is formed to have approximately the same shape as the upper surface; The edge line where the upper surface and the peripheral side intersect is divided into multiple adjacent intervals, each of the multiple adjacent intervals including a secondary cutting edge and a main cutting edge that is longer than the secondary cutting edge; In each of the intervals, the secondary cutting edge and the primary cutting edge are arranged in the same order along a circumference centered on the central axis, in a counterclockwise direction from one interval to its adjacent interval. The main cutting edge is inclined to the upper right and is inclined in a manner that moves away from the lower surface as it moves away from the secondary cutting edge; The upper surface includes a flat surface parallel to an imaginary plane orthogonal to the central axis passing through the center of the upper surface and the center of the lower surface, a chip-ejecting surface disposed on the outer periphery of the flat surface and inclined at a first angle relative to the imaginary plane, and a ridge surface disposed between the chip-ejecting surface and the main cutting edge and inclined at a second angle relative to the imaginary plane at an angle less than the first angle. In a top view taken along the central axis, the shortest distance from the main cutting edge, which is formed as a straight line, to the outer edge of the mounting hole is used as a reference value. In any cross-section cut at any position of the main cutting edge in a manner orthogonal to the main cutting edge, the distance from the imaginary intersection point of the imaginary straight line obtained by extending the contour of the edge formed as a straight line and the flat surface to the main cutting edge is measured along a direction orthogonal to the central axis. The measured length is set as a variable value that varies according to the cut position of the arbitrary cross-section, and at this time, all of the variable values ​​are greater than half of the reference value.

3. The cutting insert according to claim 1 or 2, wherein, In a top view viewed from the upper surface, the angle between the secondary cutting edge and the primary cutting edge is greater than or equal to 140° and less than or equal to 155°.

4. The cutting insert according to claim 3, wherein, In the vertical direction relative to the upper and lower surfaces, with the position closest to the lower surface of the main cutting edge as the lowest point and the position farthest from the lower surface as the highest point, the imaginary straight line passing through the lowest and highest points is inclined at an angle greater than or equal to 1° and less than or equal to 10° relative to the imaginary plane orthogonal to the central axis.

5. The cutting insert according to claim 4, wherein, The upper surface forms a six-fold or five-fold symmetry about the central axis.

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