Cutting insert and cutting tool assembly including same

Abstract

A cutting blade capable of forward rotation and high-feed-rate backward rotation according to one embodiment includes: an upper surface; a lower surface opposite to the upper surface in a vertical direction; a side portion connecting the upper surface and the lower surface; a mounting hole extending through the upper surface and the lower surface; and a plurality of cutting edges formed at the edges where the upper surface and the side portion intersect, wherein the upper surface has one or more cutting corners, the plurality of cutting edges includes a primary cutting edge and a secondary cutting edge extending from the cutting corner, and relative to a virtual reference surface perpendicular to the vertical direction, the representative inclination of the secondary cutting edge for high-feed-rate backward rotation is greater than the representative inclination of the primary cutting edge for forward rotation.

Description

[Technical Field]

[0001] The present invention relates to a cutting blade for rotating workpieces and a cutting tool assembly including the same. [Previous Technology]

[0002] Rotation is a curved operation performed on a lathe, primarily involving cutting the surface of a circular workpiece while it is rotating. In this type of rotation, generally, if the entry angle of the cutting tool (e.g., the angle between the cutting edge of the cutting blade and the workpiece surface) is small during backward rotation, the thickness of the chips produced on the workpiece becomes thinner and drooping chips are generated, thus hindering the chip removal process. Therefore, in related technologies, the corner angle of the cutting blade is designed to be very small to ensure the entry angle of the cutting blade during backward rotation.

[0003] [Technical Issues]

[0004] However, if the corner angle of the cutting blade is small, the entry angle of the cutting blade during the forward rotation becomes large. The disadvantage is that a relatively large load is applied to the forward rotation of the cutting blade. Furthermore, if the corner angle of the cutting blade is small, the upper and lower surfaces of the cutting blade become smaller. Thus, when designing the cutting blade, there are considerable limitations in ensuring space for forming the chip-forming section and promoting chip removal. In particular, when using double-sided negative-angle cutting blades, the upper and lower surfaces of the cutting blade should also be used as tool mounting surfaces, thus creating greater space constraints when designing the cutting blade. Therefore, this is more disadvantageous in terms of ensuring space for promoting chip removal and in terms of stable blade mounting. In conventional rotating cutting blades, small-corner cutting blades are mainly used for contour cutting. During the backward rotation, only the tip portion of such cutting blades is used. Therefore, the length of the chip-forming section is very small, making it difficult to use such cutting blades for high-feed-rate backward rotation. [Summary of the Invention]

[0005] [Technical Solution]

[0006] This invention provides a double-sided cutting insert mounted on a non-rotary cutting tool, such as a turning tool. Furthermore, this invention provides a cutting insert capable of both forward and backward rotation, and further, by efficiently configuring the shape of the chip forming portion, promotes smooth chip generation and good chip removal. Furthermore, this invention provides a backward rotation cutting insert capable of achieving a chip thickness that does not cause chip sagging and enabling high feed rates. Moreover, this invention provides a cutting insert capable of ensuring a stable mounting surface and smoothly receiving large loads during forward rotation.

[0007] The present invention also provides a cutting tool assembly including the above-described cutting blade.

[0008] One aspect of the present invention pertains to a cutting blade. A cutting blade capable of forward rotation and high-feed-rate backward rotation according to an exemplary embodiment includes: an upper surface; a lower surface opposite to the upper surface in a vertical direction; a side portion configured to connect with the upper and lower surfaces; a mounting hole extending through the upper and lower surfaces; and a plurality of cutting edges formed at the edge where the upper surface and the side portion intersect, wherein the upper surface has one or more cutting corners, the plurality of cutting edges includes a primary cutting edge and a secondary cutting edge extending from the cutting corner, and, relative to a virtual reference surface perpendicular to the vertical direction, the representative inclination of the secondary cutting edge for high-feed-rate backward rotation is greater than the representative inclination of the primary cutting edge for forward rotation.

[0009] In one embodiment, the cutting blade includes a first side surface, a second side surface, a third side surface, and a fourth side surface. The first side surface and the second side surface may be opposite each other, and the third side surface and the fourth side surface may be opposite each other. A pair of cutting corners may be disposed on the upper surface. The pair of cutting corners may include a first cutting corner and a second cutting corner, wherein the adjacent first side surface and the third side surface intersect the upper surface at the first cutting corner, and the adjacent second side surface and the fourth side surface intersect the upper surface at the second cutting corner. Further, the primary cutting edge may include a first cutting edge formed by the edge extending from the first cutting corner and intersecting the first side surface and the upper surface, and a second cutting edge formed by the edge extending from the second cutting corner and intersecting the second side surface and the upper surface. The secondary cutting edge may include a third cutting edge formed by the edge extending from the first cutting corner and intersecting the third side surface and the upper surface, and a fourth cutting edge formed by the edge extending from the second cutting corner and intersecting the fourth side surface and the upper surface.

[0010] In one embodiment, the upper surface may have a rhomboid shape, and the corner angle of each of the pair of cut corners is greater than 66° and less than 75°.

[0011] In one embodiment, each of the plurality of cut edges is any one of the following: a combination of straight lines and serrated shapes, a combination of straight lines and curves, a combination of a plurality of straight lines, a straight shape, and a curved shape.

[0012] In one embodiment, the representative inclination of the primary cut edge may be the inclination of a virtual reference surface of a first imaginary line relative to a first vertical line extending from each of a pair of cut corners to a point halfway through the primary cut edge. Based on the first imaginary line, the total area defined by the first imaginary line and the primary cut edge above the first imaginary line may be equal to the total area defined by the first imaginary line and the primary cut edge below the first imaginary line. Furthermore, the representative inclination of the secondary cut edge may be the inclination of a virtual reference surface of a second imaginary line relative to a second virtual line extending from each of a pair of cut corners to a point halfway through the secondary cut edge. Based on the second imaginary line, the total area defined by the second imaginary line and the secondary cut edge above the second imaginary line may be equal to the total area defined by the second imaginary line and the secondary cut edge below the second imaginary line.

[0013] In one embodiment, the upper surface may include a seat surface and an inclined surface. The seat surface may be formed as a plane parallel to the virtual reference surface, and the inclined surface may be formed as a curved surface in which a plurality of valley surfaces and a plurality of ridge surfaces are interleaved.

[0014] In one embodiment, the inclined surface may include a forward-turning inclined surface adjacent to the primary tangent and a backward-turning inclined surface adjacent to the secondary tangent.

[0015] In one embodiment, the angle between the bisector of the corner passing through a pair of cut corners and the extension of the intersection of the valley surface and the ridge surface of the forward tilting surface may be smaller than the angle between the bisector of the corner and the extension of the intersection of the valley surface and the ridge surface of the backward tilting surface.

[0016] In one embodiment, a plurality of point portions spaced apart from each other along the extension direction of the secondary tangent edge may be formed on the back-turning inclined surface.

[0017] In one embodiment, the distance between each of the secondary cut edges and the point portions may be less than the distance between the primary cut edges and the junction of the forward-inclined surface of the seat surface.

[0018] In one embodiment, a forward-rotating chip forming portion including a first groove surface inclined downward toward the mounting hole and a second groove surface connected to the first groove surface and inclined upward toward the mounting hole can be formed on the forward-rotating inclined surface, and a rear-rotating chip forming portion including a third groove surface inclined downward toward the mounting hole and a fourth groove surface connected to the third groove surface and inclined upward toward the mounting hole can be formed on the rear-rotating inclined surface.

[0019] In one embodiment, the rear-turn chip forming portion may have at least half the length of the edge where the third side meets the upper surface.

[0020] In one embodiment, the tilt angle of the rear-turn chip forming portion relative to the virtual reference surface may be greater than the tilt angle of the front-turn chip forming portion which is symmetrical about the corner bisectors passing through a pair of cutting corners.

[0021] In one embodiment, the ramp distance of the rear-turn chip forming section can be set to be less than the ramp distance of the front-turn chip forming section which is symmetrical about the corner bisectors passing through a pair of cutting corners.

[0022] In one embodiment, the entry angle of the primary cutting edge relative to the workpiece may be greater than 90°, and the entry angle of the secondary cutting edge relative to the workpiece may be less than 30°.

[0023] In the above embodiments, the upper and lower surfaces may have mirror symmetry with respect to the virtual reference surface.

[0024] Another aspect of the present invention pertains to a cutting tool assembly. A cutting tool assembly for rotating a workpiece according to an exemplary embodiment includes: a cutting blade configured to be capable of both forward rotation and high-feed-rate backward rotation; a tool holder having an insertion pocket for mounting the cutting blade at its tip; and a fixing member configured to secure the cutting blade to the insertion pocket of the tool holder. The cutting blade includes an upper surface, a lower surface perpendicular to the upper surface in a vertical direction, a plurality of side surfaces located between the upper and lower surfaces, and a plurality of cutting edges formed by the edges where the plurality of side surfaces intersect the upper surface. The upper and lower surfaces are mirror-symmetric relative to a virtual reference surface located between the upper and lower surfaces and perpendicular to the vertical direction. The upper surface has a pair of cutting corners. The plurality of cutting edges includes a primary cutting edge for forward rotation extending from each of the pair of cutting corners and a secondary cutting edge for high-feed-rate backward rotation extending from each of the pair of corners. Relative to the virtual reference surface, the representative inclination of the secondary cutting edges is greater than that of the primary cutting edges, and the entry angle of the primary cutting edge relative to the workpiece is greater than 90° while the entry angle of the secondary cutting edges relative to the workpiece is less than 30°.

[0025] In one embodiment, the representative inclination of the primary cut edge may be the inclination of a virtual reference surface of a first imaginary line relative to a first vertical line extending from each of a pair of cut corners to a point halfway through the primary cut edge. Based on the first imaginary line, the total area defined by the first imaginary line and the primary cut edge above the first imaginary line may be equal to the total area defined by the first imaginary line and the primary cut edge below the first imaginary line. The representative inclination of the secondary cut edge may be the inclination of a virtual reference surface of a second imaginary line relative to a second virtual line extending from each of a pair of cut corners to a point halfway through the secondary cut edge. Based on the second imaginary line, the total area defined by the second imaginary line and the secondary cut edge above the second imaginary line may be equal to the total area defined by the second imaginary line and the secondary cut edge below the second imaginary line.

[0026] [Beneficial Effects]

[0027] According to an embodiment of the present invention, by means of a rearward rotation controlled by the structural features of the cutting blade, the chips can be prevented from sagging.

[0028] The cutting blade according to the invention is a double-sided blade with four corners, which can stably cut in both rearward and forward rotation. In particular, the cutting blade can perform high feed rate cutting in the rearward rotation direction, thus increasing productivity. Furthermore, it can promote smooth chip removal, thereby preventing chip sagging and surface damage to the workpiece.

Implementation Method

[0047] The embodiments of the present invention are described for the purpose of illustrating the technical concept of the present invention. The scope of the present invention is not limited to the following embodiments or their detailed descriptions.

[0048] Unless otherwise defined, the technical and scientific terms used in this invention include meanings or definitions generally understood by those skilled in the art. All terms used in this invention are chosen for the purpose of more clearly describing the invention, and not for limiting the scope of the invention.

[0049] As used in this invention, the terms "comprising", "including", "having" and the like, unless otherwise stated in a phrase or sentence containing such terms, should be understood to include open-ended terms of other embodiments.

[0050] Unless otherwise stated, the singular form mentioned in this invention may include the plural form. The same applies to the singular form used in the claims.

[0051] The terms "first", "second", etc., used in the various embodiments of the present invention are used to separate the plurality of elements from each other and do not limit the order or importance of the corresponding elements.

[0052] The directional terms "above" and "over" used herein are based on the fact that the upper surface is located in the direction opposite to the lower surface in the diagram. The directional terms "below" and "under" refer to the direction opposite to the above or upper direction. The cutting blade shown in the diagram may have other directions, and the above directional terms can be interpreted accordingly.

[0053] Embodiments of the present invention will be described below with reference to the drawings. In the drawings, similar or related elements are marked by similar element symbols. In the following description of the embodiments, repeated descriptions of the same or corresponding elements will be omitted. However, even if the description of elements is omitted, it is not intended that those elements be excluded from the embodiments.

[0054] FIG1 is a perspective view of a cutting blade 1000 according to an embodiment of the present invention. FIG2 is a perspective view of the cutting blade 1000 according to an embodiment of the present invention viewed from another direction.

[0055] Referring to Figures 1 and 2, the cutting blade 1000 can be described as a rotatable double-sided indexable cutting blade. The cutting blade 1000 includes an upper surface 1100 and a lower surface 1200 facing each other in the vertical direction (z direction in Figures 1 and 2), and includes a side portion 1300 connecting the upper surface 1100 and the lower surface 1200. According to one embodiment, the cutting blade 1000 has a mounting hole 1400 formed through the upper surface 1100 and the lower surface 1200, and can be securely mounted to a cutting tool by using a clamping screw or similar fixing tool.

[0056] The side portion 1300 of the cutting blade 1000 has four sides, such as a first side 1310, a second side 1320, a third side 1330, and a fourth side 1340. The first side 1310 and the second side 1320 face each other, and the third side 1330 and the fourth side 1340 face each other. That is, when the cutting blade 1000 is viewed from above or below, the upper surface 1100 and the lower surface 1200 have a rectangular shape. In one embodiment, the edge lengths S1 and S2 of the sides are the same, so that the upper surface 1100 and the lower surface 1200 have a rhomboid shape.

[0057] In the cutting blade 1000, the cutting edge can be formed at the edge where the upper surface 1100 meets the side surface, or at the edge where the lower surface 1200 meets the side surface.

[0058] Each of the upper surface 1100 and the lower surface 1200 has four corners where adjacent side faces meet. Two of the four corners may be referred to as cut corners 1110, and the remaining two corners may be referred to as uncut corners 1110'.

[0059] In one embodiment, a pair of cut corners 1110 includes a first cut corner 1111 where adjacent first side surfaces 1310 and 1330 intersect with the upper surface 1100 (or lower surface 1200), and a second cut corner 1112 where adjacent second side surfaces 1320 and 1340 intersect with the upper surface 1100 (or lower surface 1200). A pair of non-cut corners 1110' includes a first non-cut corner 1111' where adjacent first side surfaces 1310 and 1340 intersect with the upper surface 1100 (or lower surface 1200), and a second non-cut corner 1112' where adjacent second side surfaces 1320 and 1330 intersect with the upper surface 1100 (or lower surface 1200).

[0060] The plurality of cutting edges formed on the cutting blade 1000 includes a primary cutting edge 1500 and a secondary cutting edge 1600 extending from a pair of cutting corners 1110. That is, the primary cutting edge 1500 and the secondary cutting edge 1600 are provided on each of the upper surface 1100 and the lower surface 1200. The primary cutting edge 1500 can be rotated forward, while the secondary cutting edge 1600 can be rotated backward, particularly for high feed rates. The high feed rate that can significantly improve productivity can be 0.5 mm / rev or higher.

[0061] To make the cutting blade 1000 usable on both sides, the upper surface 1100 and the lower surface 1200 are mirror-symmetric with respect to a virtual plane (hereinafter referred to as the virtual reference plane) that is perpendicular to the central axis L0 extending in the vertical direction and passing through the center CP of the mounting hole 1400. Accordingly, in the following description, to avoid repetition, the upper surface 1100 will be mainly described in relation to the lower surface 1200.

[0062] The cutting blade 1000 according to the exemplary embodiment has a rhomboid-shaped upper surface 1100, but the shape of the cutting blade 1000 is not limited thereto. For example, the cutting blade 1000 may have a circular, elliptical, and various polygonal upper surface. One or more cutting corners may be provided on the upper surface of various shapes. When the upper surface has a rhomboid shape, the upper surface may have cutting corners with multiple angles. Even with cutting blades having upper surfaces of multiple shapes, primary and secondary cutting edges extending from the cutting corners are formed, making the cutting blade suitable for both forward and backward rotation.

[0063] Figure 3 is a plan view of the cutting blade 1000 shown in Figure 1.

[0064] Referring to Figure 3, the primary cut edge 1500 includes a first cut edge 1510 formed by the corner extending from the first cut corner 1111 and intersecting the first side surface 1310 and the upper surface 1100, and a second cut edge 1520 formed by the corner extending from the second cut corner 1112 and intersecting the second side surface 1320 and the upper surface 1100. Furthermore, the secondary cut edge 1600 includes a third cut edge 1610 formed by the corner extending from the first cut corner 1111 and intersecting the third side surface 1330 and the upper surface 1100, and a fourth cut edge 1620 formed by the corner extending from the second cut corner 1112 and intersecting the fourth side surface 1340 and the upper surface 1100. That is, each cut corner forms a primary cut edge 1500 and a secondary cut edge 1600.

[0065] The cutting corner 1110 may have a sharp corner (a) to improve machining accuracy without generating high radial pressure that may cause vibration during workpiece rotation.

[0066] The corner angle (a) of the cutting corner 1110 can be 66° or more and 75° or less. According to one embodiment, the corner angle (a) of the cutting blade 1000 is 70°. If the corner angle of the cutting corner is less than 66°, the cutting corner becomes narrower and structurally weaker. Accordingly, a cutting blade with that corner angle is not suitable for high-feed-rate rearward rotation under high loads. Furthermore, because the upper surface is narrowed, the inclined surface used for setting shaped chips and the space for chip discharge are limited, making it difficult to expect good chip discharge. If the corner angle of the cutting corner exceeds 75°, the entry angle (or cutting edge angle) of the cutting blade relative to the workpiece becomes smaller during the rearward rotation period, resulting in thinner chips produced by the workpiece. Thinner chips may fall more easily, making smooth chip discharge more difficult, potentially leading to reduced machining quality due to scratches left on the machined surface of the workpiece.

[0067] The upper surface 1100 includes a seat surface 1120 and an inclined surface 1130 disposed between the mounting hole 1400 and the cutting edges 1500 and 1600. The seat surface 1120 is a mounting surface for mounting the cutting tool on the tool and is formed as a plane parallel to the virtual reference surface F (see Figures 4 and 5). The inclined surface 1130 is a surface for sliding the chips generated during the turning process (a surface for promoting chip removal) and is formed as a curved surface with a plurality of valley surfaces and a plurality of ridge surfaces interlaced.

[0068] The inclined surface 1130 includes a forward-turning inclined surface 1131 formed adjacent to the primary cutting edge 1500 to facilitate smooth discharge of chips generated during the forward-turning phase, and includes a backward-turning inclined surface 1132 formed adjacent to the secondary cutting edge 1600 to facilitate smooth discharge of chips generated during the backward-turning phase.

[0069] The forward-turning inclined surface 1131 is formed such that a plurality of valley surfaces 1131A and a plurality of ridge surfaces 1131B are staggered and continuous along the extension direction of the primary cutting edge 1500 (the first and second primary cutting edges 1510 and 1520). Furthermore, the backward-turning inclined surface 1132 is formed such that a plurality of valley surfaces 1132A and a plurality of ridge surfaces 1132B are staggered and continuous along the extension direction of the secondary cutting edge 1600 (the first and second secondary cutting edges 1610 and 1620). In one embodiment, the forward-turning inclined surface 1131 has a twisted shape so that chips generated by the workpiece during the forward-turning period can be facilitated to be discharged in a direction away from the workpiece. That is, when the imaginary line passing through a pair of cutting corners 1110, such as the first cutting corner 1111 and the second cutting corner 1112, is defined as the corner bisector B, the angle b1 between the extension line C1 of the intersection of the valley surface 1131A and the ridge surface 1131B of the forward tilting surface 1131 and the corner bisector B is smaller than the angle b2 between the extension line C2 of the intersection of the valley surface 1132A and the ridge surface 1132B of the backward tilting surface 1132 and the corner bisector B. In this way, by forming an angle b2 on the backward tilting surface 1132 that is larger than the angle b1 on the forward tilting surface 1131, especially during the backward tilting phase, the chip discharge in the chip drooping direction is guided in the opposite direction.

[0070] A plurality of dot portions 1133 spaced apart from each other along the extension direction of the secondary cutting edge 1600 are formed on the back-turning inclined surface 1132 to make the generated chips curled and soft and to promote smoother discharge during the back-turning phase. The dot portions 1133 may be formed to stand upright from the back-turning inclined surface 1132, especially from the valley surface 1132A of the back-turning inclined surface 1132, and may be formed to include a surface parallel to the seat surface 1120. The dot portions 1133 can serve as a chip crusher for good chip control. In one embodiment, three dot portions 1133 are formed on the back-turning inclined surface 1132. However, the number of dot portions 1133 is not limited thereto. The imaginary line connecting the dot portions 1133 may be inclined relative to the secondary cutting edge 1600 to guide the chips in a direction of smooth discharge. That is, the point portion 1133 can be formed such that, based on the cutting corner 1110 (the first cutting corner 1111 and the second cutting corner 1112), as the point portion 1133 moves away from the cutting corner 1110, the distance between the point portion 1133 and the adjacent secondary cutting edge 1600 increases.

[0071] When viewed from above, the distance D1 between the secondary cutting edge 1600 and the point portion 1133 is less than the distance D2 between the primary cutting edge 1500 and the seat surface of the forward tilting surface 1131. In this respect, distance D1 can be the maximum distance from the secondary cutting edge 1600 to the point portion 1133, while distance D2 can be the maximum distance from the primary cutting edge 1500 to the seat surface of the forward tilting surface 1131.

[0072] In the cutting blade 1000 according to one embodiment, the inclined surface 1130 is formed into a wavy curved shape, and the distance D1 on the rear inclined surface 1132 is set to be smaller than the distance D2 on the front inclined surface 1131, so as to further prevent chip sagging. In this way, it is possible to ensure the formation of smooth chips with a curled shape and to guide good chip discharge.

[0073] Figure 4 is a front view of the cutting blade 1000 shown in Figure 1. Figure 5 is a right side view of the cutting blade 1000 shown in Figure 1. Figure 6 is an enlarged view of the main cutting edge 1500 shown in Figure 5. Figure 7 is an enlarged view of the secondary cutting edge 1600 shown in Figure 5. Figures 8A and 8B are schematic diagrams of representative inclinations of cutting edges with a combination of straight lines and curves, while Figures 9A and 9B are schematic diagrams of representative inclinations of cutting edges with a combination of multiple straight lines. Furthermore, Figures 10A and 10B are schematic diagrams of representative inclinations of cutting edges with a straight line shape, while Figures 11A and 11B are schematic diagrams of representative inclinations of cutting edges with a curved shape.

[0074] Referring to Figures 4 and 7, a cutting blade 1000 according to one embodiment includes cutting edges (primary cutting edge 1500 and secondary cutting edge 1600) having a combination of straight lines and serrated shapes. Straight segments may extend from the cutting corner 1110, and serrated segments (or wavy segments) may extend continuously from the straight segments. The shape of the cutting edge of the cutting blade 1000 is not limited to one embodiment, and the cutting edge of the cutting blade 1000 may be formed in various shapes. For example, as shown in Figures 8A to 11B, in another embodiment, the cutting edge of the cutting blade (primary cutting edge 1500 and secondary cutting edge 1600) may be formed in any of the following shapes: a combination of straight lines and curves (see Figures 8A and 8B), a combination of multiple straight lines (see Figures 9A and 9B), a straight shape (see Figures 10A and 10B), and a curved shape (see Figures 11A and 11B).

[0075] In the cutting blade 1000 capable of both forward rotation and high-feed-rate backward rotation, the secondary cutting edge 1600 for high-feed-rate backward rotation is formed with a larger inclination relative to the virtual reference plane F than the primary cutting edge 1500 for forward rotation. That is, the first inclination angle d1 of the primary cutting edge 1500 is smaller than the second inclination angle d2 of the secondary cutting edge 1600.

[0076] In this respect, the first tilt angle of the primary cut edge 1500 signifies a representative tilt d1 of the primary cut edge 1500. The representative tilt d1 is the tilt of the virtual reference plane F relative to the first imaginary line L1 of the first vertical line V1 extending from the cut corner 1110 to the half-length point P1 passing through the primary cut edge 1500. Furthermore, the second tilt angle of the secondary cut edge 1600 signifies a representative tilt d2 of the secondary cut edge 1600. The representative tilt d2 is the tilt of the virtual reference plane F relative to the second imaginary line L2 of the second imaginary line V2 extending from the cut corner 1110 to the half-length point P2 passing through the secondary cut edge 1600 (see Figures 6 to 11B).

[0077] In one embodiment, the first imaginary line L1 may be defined as follows: That is, the total area defined by the first imaginary line L1 and the portion defined by the main tangent 1500 (the shaded portion on the first imaginary line L1) located above the first imaginary line L1 may be equal to the total area defined by the main tangent 1500 (the shaded portion below the first imaginary line L1) located below the first imaginary line L1.

[0078] In one embodiment, the second imaginary line L2 may be defined as follows: That is, the total area defined by the second imaginary line L2 and the portion defined by the secondary tangent 1600 (the shaded portion on the second imaginary line L2) located above the second imaginary line L2 may be equal to the total area defined by the secondary tangent 1600 (the shaded portion below the second imaginary line L2) located below the second imaginary line L2.

[0079] Figure 12 is a partial cross-sectional view of the cutting blade 1000 located at point Z1 in Figure 3. Figure 13 is a partial cross-sectional view of the cutting blade 1000 located at point Z2 in Figure 3.

[0080] As shown in FIG12, the front-rotating chip forming part 1140 is formed on the front-rotating inclined surface 1131. The front-rotating chip forming part 1140 includes a first groove surface 1141 inclined downward toward the mounting hole 1400 and a second groove surface 1142 connected to the first groove surface 1141 and inclined upward toward the mounting hole 1400.

[0081] Furthermore, as shown in FIG13, the rear-rotating chip forming portion 1150 is formed on the rear-rotating inclined surface 1132. The rear-rotating chip forming portion 1150 includes a third groove surface 1151 that is inclined downward toward the mounting hole 1400 and a fourth groove surface 1152 that is connected to the third groove surface 1151 and inclined upward toward the mounting hole 1400.

[0082] As described above, the cutting blade 1000 according to one embodiment has a significantly large corner angle (a), so that the forward-turning chip forming portion 1140 and the rear-turning chip forming portion 1150 can be easily formed on the inclined surface 1130 of the upper surface 1100 without much spatial restriction. In one embodiment, the rear-turning chip forming portion 1150 is formed to have a length (M) of at least half the length of any edge of the upper surface 1100 (e.g., the length of the edge where the third side meets the upper surface (S2)) to guide stable chip discharge (see FIG3).

[0083] Referring to Figures 12 and 13, the tilt angle e2 of the rear-rotating chip forming section 1150 relative to the virtual reference plane F is greater than the tilt angle e1 of the front-rotating chip forming section 1140, which is symmetrical to the relative corner bisector B. Furthermore, the ramp distance N2 of the rear-rotating chip forming section 1150 is set to be less than the ramp distance N1 of the front-rotating chip forming section 1140, which is symmetrical to the relative corner bisector B. This guides the broken chips, thereby preventing chip sagging.

[0084] FIG14 is a perspective view of a cutting tool assembly 100 according to an embodiment of the present invention. FIG15 is an exploded perspective view of the cutting tool assembly 100 shown in FIG14.

[0085] Referring to Figures 14 and 15, the cutting tool assembly 100 can be mounted on a lathe and configured to cut a rotating workpiece. For this purpose, the cutting tool assembly 100 includes the cutting blade 1000 described above, a tool holder 2000 having an insertion pocket 2100 at its tip for mounting the cutting blade 1000, and a fixing member 3000 configured to secure the cutting blade 1000 to the insertion pocket 2100 of the tool holder 2000.

[0086] A cutting tool assembly 100 according to an embodiment of the present invention includes a pad 4000 configured to support a cutting blade 1000, so that the cutting blade 1000 can be stably mounted on a tool holder 2000. With the cutting blade 1000 supported by the pad 4000, the cutting blade 1000 can be positioned in an insertion pocket 2100 of the tool holder 2000. In another embodiment, the cutting blade 1000 can be directly positioned in the insertion pocket 2100 of the tool holder 2000 without being supported by the pad 4000. In this case, the insertion pocket 2100 may include a surface having a shape complementary to the shape of the lower surface of the cutting blade 1000.

[0087] The fixing member 3000 includes a lathe screw 3100 fixed to the cutting blade 1000 and washers 4000 arranged vertically, a clamp 3200 configured to fix the cutting blade 1000, and a clamping screw 3300 inserted into the clamp 3200 and fixed to the tool holder 2000. By tightening the clamping screw 3300, the cutting blade 1000 can be fixed to the tool holder 2000, so that the clamp 3200 can push the cutting blade 1000.

[0088] Figures 16 and 17 are schematic diagrams of the state of the cutting tool assembly 100 shown in Figure 14 cutting the workpiece W.

[0089] Referring to Figures 16 and 17, the primary cutting edge 1500 of the cutting blade 1000 has an entry angle f greater than 90° relative to the workpiece W, and the secondary cutting edge 1600 has an entry angle g less than 30° relative to the workpiece W. Since the entry angle g during backward rotation is smaller than the entry angle f during forward rotation, it is important to ensure chip removal space by efficiently arranging the cutting edges and chip forming portions. The cutting blade 1000 used in the cutting tool assembly 100 according to one embodiment promotes smooth chip formation and good chip removal through the efficient arrangement of the cutting edges and chip forming portions. The cutting blade 1000 performs cutting in the backward rotation direction and can have a small entry angle. This promotes smooth chip removal.

[0090] The cutting tool assembly 100 may have an optimized cutting edge structure. That is, in the cutting blade 1000, the representative inclination d2 of the secondary cutting edge 1600 is a positive inclination greater than the representative inclination d1 of the primary cutting edge 1500. Accordingly, the cutting blade 1000 mounted on the cutting tool assembly 100 may have a structure similar to a positive blade relative to the centerline CLW of the workpiece W. Thus, by arranging the blades similar to positive edges, it is possible to prevent chips from sagging onto the outer surface of the cut workpiece and to promote smooth chip removal.

[0091] According to the above embodiment, the cutting blade 1000 has a chip control function that enables backspin at a small lead angle (g). Thus, the cutting blade 1000 has a larger corner angle (a) at the cutting corner compared to conventional cutting blades, thereby solving the problem that may occur when the cutting corner is formed very narrow to ensure the entry angle during the backspin period.

[0092] Although the technical features of the above embodiments are described with the right cutting blade as an example, the present invention can also be applied to the left cutting blade with the cutting edges arranged in the opposite direction.

[0093] While certain embodiments have been described, these embodiments are merely examples and do not limit the scope of the invention. Furthermore, the embodiments described herein can be implemented in various different forms. Moreover, various omissions, substitutions, and variations are permitted in the embodiments described herein without departing from the scope of the invention. The claims and their equivalents cover those forms and modifications, and those forms and modifications also fall within the scope of the invention. [Simplified Explanation of the Diagram]

[0029] The drawings are incorporated in and constitute a part of the specification and illustrate embodiments of the invention.

[0030] Figure 1 is a perspective view of a cutting blade according to an embodiment of the present invention.

[0031] FIG2 is a perspective view of a cutting blade according to an embodiment of the present invention viewed from another direction.

[0032] Figure 3 is a plan view of the cutting blade shown in Figure 1.

[0033] Figure 4 is a front view of the cutting blade shown in Figure 1.

[0034] Figure 5 is a right-side view of the cutting blade shown in Figure 1.

[0035] Figure 6 is an enlarged view of the main cut edge shown in Figure 5.

[0036] Figure 7 is an enlarged view of the secondary cut edge shown in Figure 5.

[0037] Figures 8A and 8B are schematic diagrams of the representative inclination of the tangent edges of the shapes of the combined straight lines and curves shown.

[0038] Figures 9A and 9B are schematic diagrams of the representative inclination of the tangent edges of the shapes of the multiple straight lines in the combination shown.

[0039] Figures 10A and 10B are schematic diagrams of the representative inclination of the straight-line cut edge shown.

[0040] Figures 11A and 11B show representative inclinations of the cut edges with the curved shape shown.

[0041] Figure 12 is a partial cross-sectional view of the cutting blade located at point Z1 shown in Figure 3.

[0042] Figure 13 is a partial cross-sectional view of the cutting blade located at point Z2 shown in Figure 3.

[0043] FIG14 is a perspective view of a cutting tool assembly according to an embodiment of the present invention.

[0044] Figure 15 is a three-dimensional exploded view of the cutting tool assembly shown in Figure 14.

[0045] Figure 16 is a schematic diagram of the cutting tool assembly shown in Figure 14 cutting the workpiece.

[0046] Figure 17 is a schematic diagram of the cutting tool assembly shown in Figure 14 cutting a workpiece from another direction. [Biomaterial Storage]

[0095] None

Claims

1. A cutting blade capable of forward rotation and high-feed-rate backward rotation, comprising: The upper surface; A lower surface that is vertically opposite to the upper surface; a side portion configured to connect with both the upper and lower surfaces; A mounting hole extending through the upper and lower surfaces; and a plurality of cleaving edges formed at the edge where the upper surface meets the side portion, wherein the upper surface has one or more cutting corners, the plurality of cleaving edges including a primary cleaving edge and a secondary cleaving edge extending from the cutting corner, and, relative to a virtual reference surface perpendicular to the vertical direction, the representative inclination of the secondary cleaving edge for high feed rate backward rotation is greater than the representative inclination of the primary cleaving edge for forward rotation, and wherein the upper surface includes an inclined surface, and the inclined surface includes a backward tilting surface adjacent to the secondary cleaving edge, and wherein the backward tilting surface is formed as a plurality of valley surfaces and a plurality of ridge surfaces that are staggered and continuous along the extension direction of the secondary cleaving edge.

2. The cutting blade as claimed in claim 1, wherein the side portion includes a first side, a second side, a third side, and a fourth side, the first side and the second side being opposite to each other, and the third side and the fourth side being opposite to each other, a pair of cutting corners being disposed on the upper surface, the pair of cutting corners including a first cutting corner and a second cutting corner, wherein the first side and the third side being adjacent to each other intersect the upper surface at the first cutting corner, and the second side and the fourth side being adjacent to each other intersect the upper surface at the second cutting corner, the primary cutting edge including a first cutting edge formed by the edge extending from the first cutting corner and intersecting the first side and the upper surface, and a second cutting edge formed by the edge extending from the second cutting corner and intersecting the second side and the upper surface, and the secondary cutting edge including a third cutting edge formed by the edge extending from the first cutting corner and intersecting the third side and the upper surface, and a fourth cutting edge formed by the edge extending from the second cutting corner and intersecting the fourth side and the upper surface.

3. The cutting blade as claimed in claim 2, wherein the upper surface has a rhomboid shape, and the corner angle of each of the pair of cutting corners is greater than 66° and less than 75°.

4. The cutting blade as claimed in claim 2, wherein each of the plurality of cutting edges is any one of the following: a combination of straight lines and serrated shapes, a combination of straight lines and curves, a combination of a plurality of straight lines, a straight shape, and a curved shape.

5. The cutting blade as claimed in claim 2, wherein the representative inclination of the primary cutting edge is the inclination of a virtual reference surface relative to a first imaginary line extending from each of the pair of cutting corners to a first vertical line passing through half a point of the primary cutting edge, the total area defined by the first imaginary line and the portion of the primary cutting edge above the first imaginary line is equal to the total area defined by the first imaginary line and the portion of the primary cutting edge below the first imaginary line, and the representative inclination of the secondary cutting edge is the inclination of a virtual reference surface relative to a second imaginary line extending from each of the pair of cutting corners to a second vertical line passing through half a point of the secondary cutting edge, the total area defined by the second imaginary line and the portion of the secondary cutting edge above the second imaginary line is equal to the total area defined by the second imaginary line and the portion of the secondary cutting edge below the second imaginary line.

6. The cutting blade as claimed in claim 2, wherein the upper surface further includes a seat surface connected to the inclined surface, the seat surface being formed as a plane parallel to the virtual reference surface, and the inclined surface being formed as a curved surface with a plurality of valley surfaces and a plurality of ridge surfaces intersecting.

7. The cutting blade as claimed in claim 6, wherein the inclined surface includes a forward-turning inclined surface adjacent to the primary cutting edge and a backward-turning inclined surface adjacent to the secondary cutting edge.

8. The cutting blade as claimed in claim 7, wherein the angle between the bisector of the corner passing through the pair of cutting corners and the extension of the line at the intersection of the valley and ridge surfaces of the forward tilting surface is less than the angle between the bisector of the corner and the extension of the line at the intersection of the valley and ridge surfaces of the rear tilting surface.

9. The cutting blade as claimed in claim 7, wherein a plurality of points spaced apart from each other along the extension direction of the secondary cutting edge are formed on the rear-turning inclined surface.

10. The cutting blade as claimed in claim 9, wherein the distance between the secondary cutting edge and each of the point portions is less than the distance between the primary cutting edge and the junction of the forward-turning inclined surface of the seat surface.

11. The cutting blade as claimed in claim 7, comprising a front-rotating chip forming portion formed on the front-rotating inclined surface, including a first groove surface inclined downward toward the mounting hole and a second groove surface connected to the first groove surface and inclined upward toward the mounting hole, and a rear-rotating chip forming portion formed on the rear-rotating inclined surface, including a third groove surface inclined downward toward the mounting hole and a fourth groove surface connected to the third groove surface and inclined upward toward the mounting hole.

12. The cutting blade as claimed in claim 11, wherein the rear-turn chip forming portion has a length of at least half the length of the edge where the third side meets the upper surface.

13. The cutting blade as claimed in claim 11, wherein the tilt angle of the rear-rotating chip forming portion relative to the virtual reference surface is greater than the tilt angle of the front-rotating chip forming portion which is symmetrical about the corner bisector passing through the pair of cutting corners.

14. The cutting blade as claimed in claim 11, wherein the ramp distance of the rear-turning chip forming portion is set to be less than the ramp distance of the front-turning chip forming portion which is symmetrical about the bisector of one corner of the pair of cutting corners.

15. The cutting blade as claimed in claim 1, wherein the primary cutting edge system is configured with an entry angle greater than 90° relative to the workpiece, and the secondary cutting edge system is configured with an entry angle less than 30° relative to the workpiece.

16. The cutting blade as claimed in claim 1, wherein the upper surface and the lower surface are mirror-symmetric with respect to the virtual reference plane.

17. A cutting tool assembly for rotating a workpiece, comprising: A cutting blade configured to be used for both forward rotation and high-feed-rate backward rotation; A tool holder with an insertion pocket for mounting the cutting blade at its tip; and a fixing member configured to secure the cutting blade to the insertion pocket of the tool holder. The cutting blade includes an upper surface, a lower surface perpendicular to the upper surface in a vertical direction, a plurality of side surfaces located between the upper and lower surfaces, and a plurality of cutting edges formed by the edges where the side surfaces intersect the upper surface. The upper and lower surfaces are mirror-symmetric relative to a virtual reference surface located between the upper and lower surfaces and perpendicular to the vertical direction. The upper surface has a pair of cutting corners. The plurality of cutting edges includes a primary cutting edge for forward rotation extending from each of the pair of cutting corners and a secondary cutting edge for high-feed backward rotation extending from each of the pair of cutting corners. The representative inclination of the secondary cutting edge is greater than that of the primary cutting edge relative to the virtual reference surface. Furthermore, the primary cutting edge system is configured with an entry angle greater than 90° relative to the workpiece and the secondary cutting edge system is configured with an entry angle less than 30° relative to the workpiece, wherein the upper surface includes an inclined surface, and the inclined surface includes a back-turning inclined surface adjacent to the secondary cutting edge, wherein the back-turning inclined surface is formed as a plurality of valley surfaces and a plurality of ridge surfaces that are staggered and continuous along the extension direction of the secondary cutting edge.

18. The cutting tool assembly as claimed in claim 17, wherein the representative inclination of the primary cutting edge is the inclination of a virtual reference surface relative to a first imaginary line extending from each of the pair of cutting corners to a first vertical line passing through half a point of the primary cutting edge, the total area defined by the first imaginary line and the portion of the primary cutting edge above the first imaginary line is equal to the total area defined by the first imaginary line and the portion of the primary cutting edge below the first imaginary line, the representative inclination of the secondary cutting edge is the inclination of a virtual reference surface relative to a second imaginary line extending from each of the pair of cutting corners to a second vertical line passing through half a point of the secondary cutting edge, and the total area defined by the second imaginary line and the portion of the secondary cutting edge above the second imaginary line is equal to the total area defined by the second imaginary line and the portion of the secondary cutting edge below the second imaginary line.

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