Cutting tool assembly and single-sided indexable cutting insert
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2026-01-28
- Publication Date
- 2026-08-13
Smart Images
Figure KR2026095044_13082026_PF_FP_ABST
Abstract
Description
CUTTING TOOL ASSEMBLY AND SINGLE-SIDED INDEXABLE CUTTING INSERT
[0001] The present invention is directed to a cutting tool assembly and a single-sided indexable cutting insert for milling.
[0002] A cutting tool assembly for milling is a tool that is often used for machining a workpiece. Generally, the cutting tool assembly for milling includes a cutter body and one or more cutting inserts mounted in the cutter body. The cutting inserts, which are mounted in the cutting tool assembly for milling, may be selected in accordance with the material of the workpiece, the shape of a final machined product, etc. To precisely machine the workpiece and achieve efficiency in operation and costs, when some cutting edges of the cutting insert wear out, an indexable cutting insert designed to use unworn cutting edges for the cutting operation is used.
[0003] The indexable cutting insert may be categorized into a single-sided indexable cutting insert and a double-sided indexable cutting insert. In the single-sided indexable cutting insert, since the cutting edges are only formed on one face while the opposing face is configured to be at least partially in contact with the cutter body, the cutting insert is securely supported by the cutter body. Thus, the single-sided indexable cutting insert is advantageous in terms of performing machining operations that require high stability and stiffness. In the double-sided indexable cutting insert, since the cutting edges are formed on both faces, the number of cutting edges is greater than that of the single-sided indexable cutting insert. As such, the double-sided indexable cutting insert is advantageous for performing multiple machining operations with a single insert.
[0004] In the conventional cutting tool assembly for milling, when the single-sided indexable cutting insert for high feed milling has four cutting edge portions especially, the entirety of one cutting edge portion is configured to cut a bottom wall of a workpiece, while another cutting edge portion, which is positioned radially outer relative to the one cutting edge portion, is configured to cut a side wall of the workpiece. In this case, when the indexable cutting insert is rotated and mounted for milling operations, due to the geometric constraint of the square shape, the same portion as the cutting edge portion that has been used for cutting the bottom wall, or a portion very close to the cutting edge portion (e.g., a wiper designed to improve the surface roughness of a cut surface of the workpiece) is reused for cutting the side wall, thereby resulting in the rapid wear of the cutting edge portion and the degradation of wear performance. Due to this, it is impossible to maximize the performance of the cutting edge portion as well as to precisely machine the workpiece. Accordingly, it is necessary to separately distinguish one cutting edge portion configured to cut the bottom wall of the workpiece from another cutting edge portion configured to cut the side wall of the workpiece.
[0005] Embodiments of the present disclosure improve or solve at least some problems of the conventional single-sided indexable cutting insert. To this end, multiple embodiments of the present disclosure provide a single-sided indexable cutting insert and a cutting tool assembly including the same, wherein the edge portions for cutting the bottom wall of the workpiece are distinguishable from the edge portions for cutting the side wall of the workpiece by removing a wiper function.
[0006] Embodiments according to one aspect of the present disclosure is directed to a cutting tool assembly. The cutting tool assembly according to an exemplary embodiment includes: a cutter body configured to rotate about a rotational axis and having a bottom surface perpendicular to the rotational axis and a cylindrical outer peripheral surface extending perpendicularly from the bottom surface; a plurality of insert pockets formed to be spaced apart from each other along a circumferential direction of the cutter body; and a plurality of single-sided indexable cutting inserts mounted in each of the plurality of insert pockets. Each of the plurality of cutting inserts includes: a lower face disposed to be in contact with one portion of the insert pocket; an upper face opposing the lower face and having four corner portions; four side faces disposed between the lower face and the upper face; and four cutting edge portions formed at edges where the upper face and the four side faces meet each other. When viewed from the side face, a first cutting edge portion, which is disposed at the bottom surface of the cutter body among the four cutting edge portions, includes: a first cutting edge extending along an outer radial direction from an end portion that is positioned in an inner radial direction based on the rotational axis; a second cutting edge extending along the outer radial direction from the first cutting edge such that a height from the lower face decreases; and a third cutting edge extending along the outer radial direction such that the height from the lower face increases from the second cutting edge to an end portion which positioned in the outer radial direction. The second cutting edge includes: a starting point connected to the first cutting edge; a ending point connected to the third cutting edge; an intermediate point disposed at a center between the starting point and the ending point; and a first curved line portion formed concavely between the intermediate point and the ending point. The cutting insert is mounted in the insert pocket such that the upper face has a positive rake angle with respect to the rotational axis and such that the first curved line portion is disposed at the lowest position along the rotational axis.
[0007] In one embodiment, the cutting insert may be mounted in the insert pocket such that the first curved line portion of the second cutting edge and the third cutting edge come in contact with the bottom wall of a workpiece to cut the bottom wall.
[0008] In one embodiment, a second cutting edge portion, which is disposed at the outer peripheral surface of the cutter body among the four cutting edge portions, may be 90 degree rotationally symmetrical to the first cutting edge portion about a centroidal axis that is perpendicular to the lower face and passes through a center of gravity of the lower face. The second cutting edge portion may include: a fourth cutting edge corresponding to the shape and position of the first cutting edge; a fifth cutting edge corresponding to the shape and position of the second cutting edge; and a sixth cutting edge corresponding to the shape and position of the third cutting edge. The cutting insert may be mounted in the insert pocket such that the fourth cutting edge comes in contact with a side wall of the workpiece to cut the side wall.
[0009] In one embodiment, the cutting insert may be mounted in the insert pocket such that at least one portion of the fifth cutting edge cuts the side wall together with the fourth cutting edge.
[0010] In one embodiment, the second cutting edge may further include a second curved line portion, which is convex upwardly between the starting point and the intermediate point.
[0011] In one embodiment, when viewed from above the upper face, the second cutting edge may have a straight shape or a curved shape.
[0012] In one embodiment, when viewed from above the upper face, the cutting insert may have a laterally convex shape such that the second cutting edge has a predetermined angle with respect to a virtual line parallel to the bottom surface of the cutter body.
[0013] In one embodiment, the first cutting edge may be parallel to the lower face.
[0014] In one embodiment, a planar area of the lower face may be smaller than a planar area of the upper face.
[0015] Embodiments according to another aspect of the present disclosure is directed to a single-sided indexable cutting insert, which is to be mounted in a cutter body that is configured to rotate about a rotational axis. The single-sided indexable cutting insert according to an exemplary embodiment includes: a lower face; an upper face opposing the lower face and having four corner portions; four side faces disposed between the lower face and the upper face; and four cutting edge portions formed at edges where the upper face and the four side faces meet each other. A first cutting edge portion, which is disposed at a bottom surface of the cutter body among the four cutting edge portions, includes: a first cutting edge extending along an outer radial direction from an end portion that is positioned in an inner radial direction based on the rotational axis; a second cutting edge extending along the outer radial direction from the first cutting edge such that a height from the lower face decreases; and a third cutting edge extending along the outer radial direction such that the height from the lower face increases from the second cutting edge to an end portion that is positioned in the outer radial direction. The second cutting edge includes: a starting point connected to the first cutting edge; a ending point connected to the third cutting edge; an intermediate point disposed at a center between the starting point and the ending point; and a first curved line portion formed concavely between the intermediate point and the ending point. The cutting insert is mounted in the cutter body such that the upper face has a positive rake angle and such that the first curved line portion is disposed at the lowest position along the rotational axis.
[0016] In one embodiment, the second cutting edge may further include a second curved line portion, which is convex upwardly between the starting point and the intermediate point.
[0017] In one embodiment, the first curved line portion of the second cutting edge and the third cutting edge may come in contact with a bottom wall of the workpiece to cut the bottom wall.
[0018] In one embodiment, when viewed from above the upper face, the second cutting edge may have a straight shape or a curved shape.
[0019] In one embodiment, when viewed from above the upper face, the cutting insert may have a laterally convex shape such that the second cutting edge has a predetermined angle with respect to a virtual line parallel to the bottom surface of the cutter body.
[0020] In one embodiment, the first cutting edge may be parallel to the lower face.
[0021] In one embodiment, a planar area of the lower face may be smaller than a planar area of the upper face.
[0022] According to the cutting tool assembly in accordance with one embodiment, the single-sided indexable cutting insert includes four cutting edge portions and is mounted in the insert pocket so as to have the positive rake angle with respect to the rotational axis. The first cutting edge portion, which is disposed at the bottom surface of the cutter body, includes: the first cutting edge extending along the outer radial direction from the end portion that is positioned in the inner radial direction; the second cutting edge extending along the outer radial direction from the first cutting edge such that the height from the lower face decreases; and the third cutting edge extending along the outer radial direction such that the height from the lower face increases from the second cutting edge to the end portion which positioned in the outer radial direction. With this configuration, when the single-sided indexable cutting insert is initially mounted in the insert pocket of the cutter body, the first cutting edge is configured so as not to cut the bottom wall of the workpiece, while one portion of the second cutting edge and the third cutting edge is configured to cut the bottom wall of the workpiece. When the single-sided indexable cutting insert is rotated in one direction (e.g., counterclockwise direction) from the initial mounting state to be mounted, the first cutting edge is configured to cut the side wall of the workpiece, whereas the second cutting edge and the third cutting edge are configured so as not to cut the side wall of the workpiece. As such, it is possible to distinguish the one portion of the second cutting edge and the third cutting edge configured to cut the bottom wall of the workpiece from the first cutting edge configured to cut the side wall of the workpiece. As a result, it is possible to maximize the performance of the first cutting edge and the second cutting edge as well as to machine the workpiece precisely.
[0023] FIG. 1 is a perspective view illustrating a cutting tool assembly according to one embodiment of the present disclosure.
[0024] FIG. 2 is a partially exploded perspective view illustrating the cutting tool assembly shown in FIG. 1.
[0025] FIG. 3 is a front view illustrating the cutting tool assembly shown in FIG. 1.
[0026] FIG. 4 is a front view illustrating a state that the cutting tool assembly shown in FIG. 1 cuts a workpiece.
[0027] FIG. 5 is a partially enlarged view enlarging and illustrating the A-portion shown in FIG. 4.
[0028] FIG. 6 is a perspective view illustrating a single-sided indexable cutting insert shown in FIG. 1.
[0029] FIG. 7 is a side view illustrating the single-sided indexable cutting insert shown in FIG. 6.
[0030] FIG. 8 is a partially enlarged view enlarging and illustrating the B-portion shown in FIG. 7.
[0031] FIG. 9 is a partially enlarged view enlarging and illustrating the C-portion shown in FIG. 4.
[0032] FIG. 10 is a plan view illustrating the single-sided indexable cutting insert shown in FIG. 6.
[0033] FIG. 11 is a partially enlarged view enlarging and illustrating the D-portion shown in FIG. 10.
[0034] Embodiments of the present disclosure are illustrated for the purpose of explaining the technical idea of the present disclosure. The scope of the rights according to the present disclosure is not limited to the embodiments presented below or the detailed descriptions of such embodiments.
[0035] All the technical terms and scientific terms in the present disclosure include meanings or definitions that are commonly understood by those of ordinary skill in the art unless otherwise defined. All terms in the present disclosure are selected for the purpose of describing the present disclosure more clearly, and are not selected to limit the scope of the present disclosure.
[0036] As used in the present disclosure, expressions such as "comprising," "including," "having" and the like are to be understood as open-ended terms having the possibility of encompassing other embodiments, unless otherwise mentioned in the phrase or sentence containing such expressions.
[0037] The singular expressions that are described in the present disclosure may encompass plural expressions unless otherwise stated, which will be also applied to the singular expressions recited in the claims.
[0038] The expressions, such as "first," "second," etc., which are shown in the present disclosure, are used to separate a plurality of elements from each other, and are not intended to limit an order or importance of the corresponding elements.
[0039] In the present disclosure, the term "outer radial direction ORD" may be defined to mean a direction moving away from a rotational axis RA of a cutter body of a cutting tool assembly, while the term "inner radial direction IRD" may be defined to mean a direction moving toward the rotational axis RA of the cutter body of the cutting tool assembly. The term "circumferential direction CD" may be understood to mean a direction surrounding the rotational axis RA and may be understood to include both a counterclockwise direction and a clockwise direction. In addition, the term "end portion" may be defined to mean a terminal portion or an end of the corresponding element.
[0040] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In the accompanying drawings, like or relevant components are indicated by like reference numerals. In the following description of embodiments, repeated descriptions of the identical or relevant components will be omitted. However, even if a description of a component is omitted, such a component is not intended to be excluded in an embodiment.
[0041] FIG. 1 is a perspective view illustrating a cutting tool assembly according to one embodiment of the present disclosure. FIG. 2 is a partially exploded perspective view illustrating the cutting tool assembly shown in FIG. 1. FIG. 3 is a front view illustrating the cutting tool assembly shown in FIG. 1.
[0042] As shown in FIGS. 1 to 3, the cutting tool assembly 1000 according to one embodiment of the present disclosure includes a cutter body 100, a plurality of insert pockets 200, and a plurality of single-sided indexable cutting inserts 300 (hereinafter, simply referred to as "cutting inserts"). The cutting tool assembly 1000 can be used for high feed milling cutting. As used herein, the term "high feed milling cutting" refers to a type of cutting operation in which the rotational speed of a spindle configured to rotate the cutter body is high and the feed speed is also set high to shorten the time required for the cutting operation.
[0043] The cutter body 100 is coupled to the spindle of a milling machine and configured to rotate around a rotational axis RA. The cutter body 100 includes a bottom surface 110 that is perpendicular to the rotational axis RA and a cylindrical outer peripheral surface 120 that extends perpendicularly to the bottom surface 110. The bottom surface 110 has a hole formed at the center of the bottom surface 110 and has a generally flat disk shape. The cylindrical outer peripheral surface 120 is centered around the rotational axis RA and extends along the rotational axis RA. When the cutting tool assembly 1000 cuts a workpiece WP, the bottom surface 110 is arranged substantially parallel to the bottom wall WP1 of the workpiece WP, and the outer peripheral surface 120 is arranged substantially parallel to the side wall WP2 of the workpiece WP.
[0044] The plurality of insert pockets 200 are formed to be spaced apart from each other along the circumferential direction CD of the cutter body 100 (i.e., the rotational direction of the cutter body 100 about the rotational axis RA). Since the plurality of insert pockets 200 have the same shape and size, one insert pocket will be described in the following description.
[0045] The insert pocket 200 is formed by recessing a portion of the bottom surface 110 and a portion of the outer peripheral surface 120 near the corner where the bottom surface 110 and the outer peripheral surface 120 of the cutter body 100 meet each other. As shown in FIG. 2, the insert pocket 200 includes a bottom support wall 210 that is formed to be generally flat, and a screw hole 230 is formed in the bottom support wall 210. The bottom support wall 210 is formed to have a predetermined angle with respect to the bottom surface 110 of the cutter body 100. The insert pocket 200 includes two side support walls 220 that are arranged to be inclined with respect to the bottom support wall 210. The two side support walls 220 are arranged approximately perpendicular to each other and meet each other at ends in the inner radial direction IRD and ends opposite to the bottom surface 110. The bottom support wall 210 and the side support walls 220 can be formed to match the shape of the lower surface 310 and the side surface 330 of the cutting insert 300. Although the drawings according to one embodiment shows four insert pockets 200, the present disclosure is not limited thereto and may include any appropriate number of insert pockets.
[0046] The plurality of cutting inserts 300 are mounted in the plurality of insert pockets 200, respectively. The cutting inserts 300 are mounted in the insert pockets 200 such that one portion of the cutting inserts 300 protrudes from the bottom surface 110 of the cutter body 100 along the direction of the rotational axis RA, while another portion of the cutting inserts 300 protrudes from the outer peripheral surface 120 of the cutter body 100 along the outer radial direction ORD. Since the plurality of cutting inserts 300 have the same shape and size, one cutting insert will be described in the following description.
[0047] FIG. 4 is a front view illustrating a state that the cutting tool assembly shown in FIG. 1 cuts a workpiece. FIG. 5 is a partially enlarged view enlarging and illustrating the A-portion shown in FIG. 4.
[0048] As shown in FIGS. 4 and 5, the cutting insert 300 is mounted in the insert pocket 200 such that the upper face 320 thereof has a positive rake angle α with respect to the rotational axis RA. As used herein, the term "upper face 320"refers to a virtual line VL1 that is parallel to the lower face 310 and at least partially in contact with the first cutting edge portion 341, and the rotational axis RA may be understood to refer to a virtual line VL2 that is perpendicular to the bottom wall WP1 of the workpiece WP and intersects the virtual line VL1. If the cutting insert 300 is positioned to have a positive rake angle α in this way, then the cutting resistance can be reduced when cutting the workpiece WP. As a result, it is possible to cut the workpiece WP smoothly, lower the cutting temperature, and discharge chips smoothly.
[0049] FIG. 6 is a perspective view illustrating the single-sided indexable cutting insert shown in FIG. 1. FIG. 7 is a side view illustrating the single-sided indexable cutting insert shown in FIG. 6.
[0050] As shown in FIGS. 6 and 7, the cutting insert 300 includes a lower face 310, an upper face 320, four side faces 330, and four cutting edge portions 340.
[0051] The lower face 310 is positioned to be in contact with a portion of the insert pocket 200. The lower face 310 is generally flat and is positioned to be in contact with the bottom support wall 210 of the insert pocket 200 to thereby be supported by the bottom support wall 210. For example, the lower face 310 may have a generally rectangular plan-view shape. The four corners of the lower face 310 may have a round shape with a predetermined radius of curvature. In one embodiment, the planar area of the lower face 310 may be smaller than the planar area of the upper face 320.
[0052] The upper face 320 is positioned to face the lower face 310 and has four corners. For example, the upper face 320 may have a generally rectangular plan-view shape. The four corners of the upper face 320 may have a round shape with a predetermined radius of curvature.
[0053] The four side faces 330 are arranged between the lower face 310 having four corners and the upper face 320 having four corners. The four side faces 330 form an obtuse angle with respect to the lower face 310 and an acute angle with respect to the upper face 320. As such, when viewed from one side face 331 of the cutting insert 300, the side face 331 may have a generally trapezoidal front-view shape. In describing the four side faces 330 below, the side face arranged on the bottom surface 110 of the cutter body 100 is referred to as the first side face 331, the side face arranged on the outer peripheral surface 120 of the cutter body 100 is referred to as the second side face 332. The side faces sequentially arranged along the circumferential direction from the first side face 331 toward the second side face 332 are referred to as the third side face 333 and the fourth side face 334. The first to fourth side faces 331, 332, 333 and 334 have the same shape and size and are arranged to be rotationally symmetrical by 90 degrees about a centroidal axis CA. As used herein, the term "centroidal axis CA" may refer to an axis that is perpendicular to the lower face 310 and passes through the center of gravity of the lower face 310. In addition, the centroidal axis CA may be understood to be the same as the center axis of the screw hole 230 described above or the center axis of the insert bore 350 described later.
[0054] Four cutting edge portions 340 are formed at the edges where the upper face 320 and each of the four side faces 330 meet each other. The four cutting edge portions 340 are formed continuously along the circumferential direction of the upper face 320 at a border of the upper face 320. In describing the four cutting edge portions 340 below, the cutting edge portion disposed on the bottom surface 110 of the cutter body 100 is referred to as the first cutting edge portion 341 (i.e., the cutting edge portion where the upper face 320 and the first side face 331 meet each other), and the cutting edge portion disposed on the outer peripheral surface 120 of the cutter body 100 is referred to as the second cutting edge portion 342 (i.e., the cutting edge portion where the upper face 320 and the second side face 332 meet each other). The cutting edge portions sequentially arranged along the circumferential direction from the first cutting edge portion 341 to the second cutting edge portion 342 are referred to as the third cutting edge portion 343 and the fourth cutting edge portion 344. The first to fourth cutting edge portions 341, 342, 343 and 344 have the same shape and size and are arranged to be rotationally symmetrical by 90 degrees about the centroidal axis CA.
[0055] FIG. 8 is a partially enlarged view enlarging and illustrating the B-portion shown in FIG. 7.
[0056] As shown in FIG.8, when viewed from the first side face 331, the first cutting edge portion 341 includes a first cutting edge 341a, a second cutting edge 341b, and a third cutting edge 341c. The first to third cutting edges 341a, 341b and 341c are sequentially and continuously formed along the outer radial direction ORD of the first cutting edge portion 341.
[0057] As shown in FIGS. 7 and 8, the first cutting edge 341a extends along the outer radial direction ORD from a first end E1 which is located in the inner radial direction IRD based on the rotational axis RA. The first cutting edge 341a has a straight shape. For example, the height of the first cutting edge 341a from the lower face 310 may be constant as it goes along the inner radial direction IRD or the outer radial direction ORD. In one embodiment, the first cutting edge 341a may be parallel to the lower face 310.
[0058] As shown in FIGS. 7 and 8, the second cutting edge 341b extends along the outer radial direction ORD from an end (e.g., a starting point P11 described below) which is located in the outer radial direction ORD of the first cutting edge 341a such that the height from the lower face 310 is lowered. The second cutting edge 341b connects the first cutting edge 341a and the third cutting edge 341c between the first cutting edge 341a and the third cutting edge 341c.
[0059] As shown in FIG. 7, the third cutting edge 341c extends along the outer radial direction ORD from an end (e.g., an ending point P12 described below) which is located in the outer radial direction ORD of the second cutting edge 341b to a second end E2 which is located in the outer radial direction ORD such that the height from the lower face 310 is increased. The third cutting edge 341c has a straight shape.
[0060] As shown in FIG. 8, the second cutting edge 341b includes the starting point P11 connected to the first cutting edge 341a, the ending point P12 connected to the third cutting edge 341c, an intermediate point P13 located approximately midway between the starting point P11 and the ending point P12, and a first curved line portion CL1 formed concavely downward between the intermediate point P13 and the ending point P12.
[0061] The starting point P11 may be defined as a point where the height from the lower face 310 of either the first cutting edge 341a or the second cutting edge 341b begins to decrease. Furthermore, the starting point P11 may be understood as an end along the outer radial direction ORD of the first cutting edge 341a, and may also be understood as an end along the inner radial direction IRD of the second cutting edge 341b. The ending point P12 may be defined as a point where the height from the lower face 310 of either the second cutting edge 341b or the third cutting edge 341c begins to increase. In addition, the ending point P12 may be understood as an end along the outer radial direction ORD of the second cutting edge 341b, and may also be understood as an end along the inner radial direction IRD of the third cutting edge 341c.
[0062] In the first curved line portion CL1, the slope of the tangent line of the first curved line portion CL1 with respect to the lower face 310 or the first cutting edge 341a may be set to gradually decrease as it goes in the outer radial direction ORD. As used herein, the term "downward" may be defined as the direction from the upper face 320 toward the lower face 310 in FIG. 7.
[0063] The cutting insert 300 is mounted in the insert pocket 200 such that the first curved line portion CL1 is arranged at the lowest position along the rotational axis RA (i.e., at the lowest portion of the cutting tool assembly 1000). Accordingly, the first curved line portion CL1 is arranged at the lowest portion of the cutting tool assembly 1000 to thereby be in contact with the bottom wall WP1 of the workpiece WP. In this case, the first curved line portion CL1 of the second cutting edge 341b is configured to cut the bottom wall WP1. Since the cutting insert 300 is mounted in the insert pocket 200 in this manner, the first cutting edge 341a, which has conventionally served as a wiper, is not in contact with the bottom wall WP1 of the workpiece WP but is spaced apart from the bottom wall WP1 of the workpiece WP by a predetermined gap. That is, the first cutting edge 341a is not used to cut the bottom wall WP1 of the workpiece WP. Accordingly, it is possible to prevent or suppress the first cutting edge 341a from being worn by the bottom wall WP1 of the workpiece WP. As a result, even if the cutting insert 300 is rotated by 90 degrees in counterclockwise or 270 degrees in clockwise and mounted in the insert pocket 200 about the centroidal axis CA, the first cutting edge 341a can precisely cut the side wall WP2 of the workpiece WP without any degradation in wear performance, thereby prolonging the lifespan of the cutting insert 300.
[0064] In one embodiment, the second cutting edge 341b may further include a second curved line portion CL2 formed convexly upward between the starting point P11 and the intermediate point P13. In the second curved line portion CL2, the slope of the tangent line of the second curved line portion CL2 with respect to the lower face 310 or the first cutting edge 341a may be set to gradually increase as it goes in the outer radial direction ORD. As used herein, the term "upward" may be defined as the direction from the lower face 310 toward the upper face 320 in FIG. 7.
[0065] As one example, the intermediate point P13 may be an inflection point where the first curved line portion CL1 and the second curved line portion CL2 meet each other. As used herein, the term "inflection point" may be defined as a point where the slope of the tangent line of the second curved line portion CL2 with respect to the lower face 310 or the first cutting edge 341a gradually increases and then the slope of the tangent line of the first curved line portion CL1 begins to gradually decreases as it goes in the outer radial direction ORD. In this case, the tangent line TL1 passing through the intermediate point P13 may have a predetermined angle β with respect to a normal line NL that is perpendicular to the lower face 310 or the first cutting edge 341a. As another example, the intermediate point P13 may be a straight line connecting the first curved line portion CL1 and the second curved line portion CL2. In this case, the intermediate point P13 may be understood as an intermediate region. In addition, the straight line of the intermediate region may have a predetermined angle β with respect to the normal line NL that is perpendicular to the lower face 310 or the first cutting edge 341a.
[0066] FIG. 9 is a partially enlarged view enlarging and illustrating the C-portion shown in FIG. 4.
[0067] As shown in FIG. 9, in one embodiment, the cutting insert 300 may be mounted in the insert pocket 200 such that the first curved line portion CL1 of the second cutting edge 341b and the third cutting edge 341c come in contact with the bottom wall WP1 of the workpiece WP to cut the bottom wall WP1. That is, the first curved line portion CL1 of the second cutting edge 341b and the third cutting edge 341c may be configured to cut the bottom wall WP1. In this case, the first cutting edge 341a and the second curved line portion CL2 of the second cutting edge 341b are not in contact with the bottom wall WP1 of the workpiece WP but are spaced apart from the bottom wall WP1 of the workpiece WP by a predetermined gap. That is, the first cutting edge 341a and the second curved line portion CL2 of the second cutting edge 341b are not used to cut the bottom wall WP1 of the workpiece WP. As such, it is possible to prevent and suppress the first cutting edge 341a and the second curved line portion CL2 of and the second cutting edge 341b from being worn by the bottom wall WP1 of the workpiece WP. As a result, even if the cutting insert 300 is rotated by 90 degrees in counterclockwise or 270 degrees in clockwise and mounted in the insert pocket 200 about the centroidal axis CA, the first cutting edge 341a and the second curved line portion CL2 of the second cutting edge 341b can precisely cut the side wall WP2 of the workpiece WP without any degradation in wear performance, thereby prolonging the lifespan of the cutting insert 300. Moreover, when the cutting insert 300 is mounted in the insert pocket 200 as shown in FIG. 9, it is possible to prevent or suppress chips cut from the workpiece WP from being discharged toward the outer radial direction ORD.
[0068] In one embodiment, the second cutting edge portion 342 may be 90 degree rotationally symmetrical to the first cutting edge portion 341 about the centroidal axis CA. The second cutting edge portion 342 may include a fourth cutting edge 342a corresponding to the shape and position of the first cutting edge 341a and arranged at a position rotated by 90 degrees in counterclockwise from the first cutting edge 341a, a fifth cutting edge 342b corresponding to the shape and position of the second cutting edge 341b and arranged at a position rotated by 90 degrees in counterclockwise from the second cutting edge 341b, and a sixth cutting edge 342c corresponding to the shape and position of the third cutting edge 341c and arranged at a position rotated by 90 degrees in counterclockwise from the third cutting edge 341c. Here, the fourth to sixth cutting edges 342a, 342b and 342c are defined to distinguish them from the first to third cutting edges 341a, 341b and 341c, and have the same shape and size as the first to third cutting edges 341a, 341b and 341c rotated by 90 degrees about the centroidal axis CA. The cutting insert 300 may be mounted in the insert pocket 200 such that the fourth cutting edge 342a comes in contact with the side wall WP2 of the workpiece WP to cut the side wall WP2.
[0069] In this embodiment, the fifth cutting edge 342b of the second cutting edge portion 342 is not in contact with the side wall WP2 of the workpiece WP, but is rather spaced apart from the side wall WP2 of the workpiece WP by a predetermined gap. That is, the fifth cutting edge 342b of the second cutting edge portion 342 is not used to cut the side wall WP2 of the workpiece WP. As such, it is possible to prevent or suppress the fifth cutting edge 342b of the second cutting edge portion 342 from being worn by the side wall WP2 of the workpiece WP. As a result, even if the cutting insert 300 is rotated by 90 degrees in counterclockwise or 270 degrees in clockwise and mounted in insert pocket 200 about the centroidal axis CA, the fifth cutting edge 342b can precisely cut the bottom wall WP1 of the workpiece WP without any degradation in wear performance, thereby prolonging the lifespan of the cutting insert 300.
[0070] In one embodiment, the cutting insert 300 may be mounted in the insert pocket 200 such that at least a portion of the fifth cutting edge 342b cuts the side wall WP2 together with the fourth cutting edge 342a. Here, at least a portion of the fifth cutting edge 342b may be understood as a portion corresponding to the second curved line portion CL2 of the second cutting edge 341b. Whether at least a portion of the fifth cutting edge 342b cuts the side wall WP2 may be determined depending on the required cutting depth of the side wall WP2.
[0071] In one embodiment, the first to fourth cutting edge portions 341, 342, 343 and 344 may be sequentially and continuously arranged along the circumferential direction of the cutting insert 300. The first to third cutting edges 341a, 341b and 341c may be sequentially and continuously formed on the first cutting edge portion 341, and the fourth to sixth cutting edges 342a, 342b and 342c may be sequentially and continuously formed on the second cutting edge portion 342. Accordingly, the first end E1 of the first cutting edge 341a may be connected to the second end of the cutting edge which corresponds to the third cutting edge 341c formed in the fourth cutting edge portion 344, and the second end E2 of the third cutting edge 341c may be connected to the first end of the fourth cutting edge 342a.
[0072] FIG. 10 is a plan view illustrating the single-sided indexable cutting insert shown in FIG. 6. FIG. 11 is a partially enlarged view enlarging and illustrating the D-portion shown in FIG. 10.
[0073] As shown in FIGS. 10 and 11, in one embodiment, when viewed from above the upper face 320 (i.e., in a plan view of the cutting insert 300), the second cutting edge 341b may have a straight shape or a curved shape. In this embodiment, when the second cutting edge 341b has a curved shape, the second cutting edge 341b may be formed to be concave downward in FIGS. 10 and 11.
[0074] As shown in FIG. 10, in one embodiment, when viewed from above the upper face 320, the cutting insert 300 may have a laterally convex shape such that the second cutting edge 341b has a predetermined angle γ with respect to a virtual line VL parallel to the bottom surface 110 of the cutter body 100. When the second cutting edge 341b is a straight line, the straight line may have the angle γ with respect to the virtual line VL. When the second cutting edge 341b is a curved line, the tangent line TL2 at the most laterally convex portion of the second cutting edge 341b may have the angle γ with respect to the virtual line VL. When the cutting insert 300 arranged as shown in FIG. 9 cuts the workpiece WP, the first curved line portion CL1 of the second cutting edge 341b can come in contact with the bottom wall WP1 of the workpiece WP to cut the bottom wall WP1.
[0075] As shown in FIG. 6, in one embodiment, the cutting insert 300 may further include an insert bore 350. The insert bore 350 is formed to pass through the center of gravity of the lower face 310 and penetrate the lower face 310 and the upper face 320 in a direction perpendicular to the lower face 310.
[0076] As shown in FIGS. 1 to 3, in one embodiment, the cutting tool assembly 1000 may further include a clamping screw 400 for securing the cutting insert 300 to the insert pocket 200. The clamping screw 400 is threadedly coupled into the screw hole 230 formed in the insert pocket 200 through the insert bore 350 of the cutting insert 300 while the cutting insert 300 is arranged in the insert pocket 200.
[0077] While the technical concept of the present disclosure has been described above with reference to certain embodiments and examples illustrated in the accompanying drawings, it should be understood that various substitutions, modifications, and variations may be made without departing from the technical concept and scope of the present disclosure, which would be understood by those skilled in the art to which the present disclosure pertains. Furthermore, such substitutions, modifications, and variations should be considered to fall within the scope of the appended claims.
Claims
1.A cutting tool assembly, comprising:a cutter body configured to rotate about a rotational axis and having a bottom surface perpendicular to the rotational axis and a cylindrical outer peripheral surface extending perpendicularly from the bottom surface;a plurality of insert pockets formed to be spaced apart from each other along a circumferential direction of the cutter body; anda plurality of single-sided indexable cutting inserts mounted in each of the plurality of insert pockets,wherein each of the plurality of cutting inserts includes:a lower face disposed to be in contact with one portion of the insert pocket;an upper face opposing the lower face and having four corner portions;four side faces disposed between the lower face and the upper face; andfour cutting edge portions formed at edges where the upper face and the four side faces meet each other,wherein, when viewed from the side face, a first cutting edge portion, which is disposed at the bottom surface of the cutter body among the four cutting edge portions, includes:a first cutting edge extending along an outer radial direction from an end portion that is positioned in an inner radial direction based on the rotational axis;a second cutting edge extending along the outer radial direction from the first cutting edge such that a height from the lower face decreases; anda third cutting edge extending along the outer radial direction such that the height from the lower face increases from the second cutting edge to an end portion which positioned in the outer radial direction,wherein the second cutting edge includes:a starting point connected to the first cutting edge;a ending point connected to the third cutting edge;an intermediate point disposed at a center between the starting point and the ending point; anda first curved line portion formed concavely between the intermediate point and the ending point, andwherein the cutting insert is mounted in the insert pocket such that the upper face has a positive rake angle with respect to the rotational axis and such that the first curved line portion is disposed at the lowest position along the rotational axis.2.The cutting tool assembly of Claim 1, wherein the cutting insert is mounted in the insert pocket such that the first curved line portion of the second cutting edge and the third cutting edge come in contact with a bottom wall of a workpiece to cut the bottom wall.3.The cutting tool assembly of Claim 2, wherein a second cutting edge portion, which is disposed at the outer peripheral surface of the cutter body among the four cutting edge portions, is 90 degree rotationally symmetrical to the first cutting edge portion about a centroidal axis that is perpendicular to the lower face and passes through a center of gravity of the lower face,wherein the second cutting edge portion includes:a fourth cutting edge corresponding to a shape and a position of the first cutting edge;a fifth cutting edge corresponding to a shape and a position of the second cutting edge; anda sixth cutting edge corresponding to a shape and a position of the third cutting edge, andwherein the cutting insert is mounted in the insert pocket such that the fourth cutting edge comes in contact with a side wall of the workpiece to cut the side wall.4.The cutting tool assembly of Claim 3, wherein the cutting insert is mounted in the insert pocket such that at least one portion of the fifth cutting edge cuts the side wall together with the fourth cutting edge.5.The cutting tool assembly of Claim 1, wherein the second cutting edge further includes a second curved line portion that is convex upwardly between the starting point and the intermediate point.6.The cutting tool assembly of Claim 1, wherein, when viewed from above the upper face, the second cutting edge has a straight shape or a curved shape.7.The cutting tool assembly of Claim 1, wherein, when viewed from above the upper face, the cutting insert has a laterally convex shape such that the second cutting edge has a predetermined angle with respect to a virtual line parallel to the bottom surface of the cutter body.8.The cutting tool assembly of Claim 1, wherein the first cutting edge is parallel to the lower face.9.The cutting tool assembly of Claim 1, wherein a planar area of the lower face is smaller than a planar area of the upper face.10.A single-sided indexable cutting insert to be mounted in a cutter body that is configured to rotate about a rotational axis, the single-sided indexable cutting insert comprising:a lower face;an upper face opposing the lower face and having four corner portions;four side faces disposed between the lower face and the upper face; andfour cutting edge portions formed at edges where the upper face and the four side faces meet each other,wherein a first cutting edge portion, which is disposed at a bottom surface of the cutter body among the four cutting edge portions, includes:a first cutting edge extending along an outer radial direction from an end portion that is positioned in an inner radial direction based on the rotational axis;a second cutting edge extending along the outer radial direction from the first cutting edge such that a height from the lower face decreases; anda third cutting edge extending along the outer radial direction such that the height from the lower face increases from the second cutting edge to an end portion which positioned in the outer radial direction,wherein the second cutting edge includes:a starting point connected to the first cutting edge;a ending point connected to the third cutting edge;an intermediate point disposed at a center between the starting point and the ending point; anda first curved line portion formed concavely between the intermediate point and the ending point, andwherein the cutting insert is mounted in the cutter body such that the upper face has a positive rake angle and such that the first curved line portion is disposed at the lowest position along the rotational axis.11.The single-sided indexable cutting insert Claim 10, wherein the second cutting edge further includes a second curved line portion that is convex upwardly between the starting point and the intermediate point.12.The single-sided indexable cutting insert Claim 10, wherein the first curved line portion of the second cutting edge and the third cutting edge come in contact with a bottom wall of a workpiece to cut the bottom wall.13.The single-sided indexable cutting insert Claim 10, wherein when viewed from above the upper face, the second cutting edge has a straight shape or a curved shape.14.The single-sided indexable cutting insert Claim 10, wherein, when viewed from above the upper face, the cutting insert has a laterally convex shape such that the second cutting edge has a predetermined angle with respect to a virtual line parallel to the bottom surface of the cutter body.15.The single-sided indexable cutting insert Claim 10, wherein the first cutting edge is parallel to the lower face.16.The single-sided indexable cutting insert Claim 10, wherein a planar area of the lower face is smaller than a planar area of the upper face.