Cutting insert

Abstract

A cutting blade capable of covering a relatively wide area from a low region (micro-finishing) to a middle region (medium cutting) with one blade. The cutting blade 10 includes an upper surface, a lower surface, a peripheral side surface 15, a cutting edge 20 having a main cutting edge 21 and a corner cutting edge 25, a corner portion 36, a protrusion portion 40 having a first protrusion 41 and a second protrusion 42 formed from the corner portion 36 toward the central axis AX1, a rake face portion 50, and an inclined portion S provided on the cutting edge 20. The inclined portion S has a first inclined portion S1 starting from the middle of the corner cutting edge 25, and the rake face portion 50 is shaped such that the angle of the rake angle gradually increases as it moves away from the corner portion 36.

Description

Technical Field

[0001] The present invention relates to a cutting blade. Background Art

[0002] Conventionally, as tools for turning, cutting blades with various structures have been used. As one of such cutting blades, for example, a cutting blade provided with a chip breaker projection (projection part) extending near a corner and an inclination of a cutting edge in side view has been disclosed (see Patent Document 1). The cutting blade disclosed in Patent Document 1 ensures chip disposal during finish machining by having a chip breaker projection. At the same time, in order to also cope with high cutting depths, it is formed such that the height of the chip breaker projection temporarily increases and then decreases.

[0003] Prior Art Documents

[0004] Patent Document

[0005] Patent Document 1: International Publication WO 2015 / 046558 A1

[0006] Technical Problem

[0007] However, for the conventional cutting blades as described above, in reality, it is required to be able to cover (cope with) a relatively wide range from a low region (micro finish machining) to a medium region (medium cutting) with a single blade. In view of such a reality, for example, for a cutting blade having a structure suitable for finish machining (low cutting depth and low feed machining), a so-called structure with an expanded applicable range is considered as a cutting blade that meets the above requirements in order to maintain such characteristics and be able to achieve high-quality cutting even when a high cutting depth is formed.

[0008] Therefore, an object of the present invention is to provide a cutting blade that can cover a relatively wide range from a low region (micro finish machining) to a medium region (medium cutting) with a single blade. Summary of the Invention

[0009] According to one aspect of the present invention, a cutting blade is characterized by including:

[0010] An upper surface as a first end surface;

[0011] A lower surface as a second end surface, which is a surface on the side opposite to the upper surface and has a mounting surface for mounting a cutting tool to a main body;

[0012] A peripheral side surface formed to connect the upper surface and the lower surface;

[0013] A cutting edge having a main cutting edge and a corner cutting edge formed on an intersection ridge line of the upper surface and the peripheral side surface;

[0014] The corner portion including the corner cutting edge;

[0015] A protrusion having a first protrusion with a top surface that becomes lower as it moves from the corner portion toward the central axis formed in a direction perpendicular to the lower surface through the center of the upper surface, and a second protrusion connected to the first protrusion and having a top surface that becomes higher as it moves from the first protrusion toward the central axis;

[0016] A rake face formed between the protrusion and the cutting edge; and

[0017] A slant portion provided on the cutting edge midway along the corner cutting edge such that the height of the cutting edge gradually decreases as it moves away from the corner cutting edge,

[0018] The slant portion has a first slant portion starting midway along the corner cutting edge,

[0019] The rake face is shaped such that the angle of the rake angle gradually increases as it moves away from the corner portion.

[0020] In the manner described above, a cutting insert that is particularly suitable for finish machining (low-region machining such as low cutting depth and low feed machining) and can also expand the applicable range on the high cutting depth side can be provided. In other words, an improved cutting insert that is mainly for low cutting depth conditions and can also handle medium-region machining such as high cutting depth and low feed conditions can be provided. That is, the front protrusion, i.e., the first protrusion, formed at a position near the corner portion on the upper surface contributes to the improvement of chips, especially in the low region; the slant portion (slant) provided on the cutting edge starting from near (midway) the corner cutting edge serves to make the chips flow faster; the rake face formed such that the rake angle is larger in medium-region machining than in low-region machining serves to suppress burrs / vibrations during medium-region machining; the rake face with a shape where the rake angle gradually increases as it moves away from the corner portion feeds the chips while rounding the chips and flowing along the rake face; if there are too many chip discharge channels (chip grooves), problems may occur due to this, but for this, a structure with an expanded applicable range has been achieved, that is, by setting the second protrusion into a suitable shape for guiding chips, various functions such as suppressing such problems are achieved. This structure is particularly suitable for finish machining (low cutting depth and low feed machining), and high-quality cutting can also be achieved when high cutting depth is formed.

[0021] In the cutting insert described above, the slant portion may further have a second slant portion connected to the first slant portion and having a larger slope than the first slant portion.

[0022] In the cutting insert described above, the rake face near the corner portion may also be formed into a substantially smooth surface.

[0023] In the cutting blade as described above, the rake face near the corner may also be shaped such that the rake angle is consistent with the slope of the first inclined portion.

[0024] The rake face of the cutting blade as described above may also be formed such that the angle of the rake angle gradually increases as it moves away from the corner.

[0025] In the cutting blade as described above, the peak point of the first protrusion may be higher than the tip of the corner cutting edge.

[0026] In the cutting blade as described above, the first protrusion may also gradually become lower as it moves from the peak point toward the central axis.

[0027] In the cutting blade as described above, a top surface may also be formed on the second protrusion, and the top surface has a portion that is inclined so as to become higher as it moves from the first protrusion toward the central axis.

[0028] The side portion of the second protrusion as described above may also be formed in a multi-stage shape.

[0029] A wall surface may also be formed in the portion between the top surface and the rake face of the second protrusion of the cutting blade as described above.

[0030] The wall surface as described above may also have: a first-stage wall surface standing up from the rake face and a second-stage wall surface provided between the first-stage wall surface and the top surface.

[0031] The first-stage wall surface as described above may also be formed such that the size of the space formed between the first-stage wall surface and the rake face gradually decreases as it moves away from the corner to allow chip flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a perspective view showing an example of a cutting blade according to one aspect of the present invention.

[0033] Figure 2 is an enlarged view showing Figure 1 a part (circled part) in

[0034] Figure 3 is a top view showing an example of the cutting blade.

[0035] Figure 4 is a front view of the cutting blade as viewed in the length direction.

[0036] Figure 5 is a side view of the cutting blade as viewed in the width direction.

[0037] Figure 6 is a partial top view of the cutting blade showing an enlarged view of the first protrusion and the second protrusion portions.

[0038] Figure 7Side view of a portion of a cutting insert including a first protrusion and a second protrusion.

[0039] Figure 8 Partial top view of a cutting insert that magnifies a portion of the first protrusion.

[0040] Figure 9 Side view of a portion of a cutting insert including the first protrusion.

[0041] Figure 10 Figure showing a machining image when representing a low region (low cutting depth) of a cutting insert.

[0042] Figure 11 Is a magnified representation of Figure 10 Figure of a portion of the cutting insert shown including the first protrusion.

[0043] Figure 12 Figure showing a machining image when representing a middle region (medium cutting depth) of a cutting insert.

[0044] Figure 13 Is a magnified representation of Figure 12 Figure of a portion of the cutting insert shown including the first protrusion and the second protrusion.

[0045] Figure 14 (A) is an image showing an example of a chip at a middle region cutting depth of Figure 12 , Figure 13 shown, and (B) is a reference image showing an example of a chip based on the cutting depth of an existing cutting insert.

[0046] Figure 15 Figure that magnifies a portion including the first protrusion and the second protrusion as viewed along the length direction of the cutting insert.

[0047] Figure 16 Figure that magnifies a portion including the first protrusion as viewed along the length direction of the cutting insert.

[0048] Main component symbol description

[0049] Cutting insert 10

[0050] First circumferential side face 11

[0051] Second circumferential side face 12

[0052] Third circumferential side face 13

[0053] Fourth circumferential side face 14

[0054] Circumferential side face 15

[0055] Intersection ridge line of the upper surface and the circumferential side face 16

[0056] Upper surface (first end face) 17

[0057] Threaded hole 18

[0058] Lower surface (second end face) 19

[0059] Cutting edge 20

[0060] Deepest part of the cutting edge 20d

[0061] Main cutting edge 21

[0062] Corner cutting edge 25

[0063] Tip of the corner cutting edge 25t

[0064] Corner part 36

[0065] Protrusion 40

[0066] First chip-breaking protrusion (first protrusion) 41

[0067] Peak point of the first protrusion 41p

[0068] Top surface of the first protrusion 41u

[0069] Second chip-breaking protrusion (second protrusion) 42

[0070] First-stage wall surface of the second chip-breaking protrusion (a part of the side of the second protrusion) 42a

[0071] Second-stage wall surface of the second chip-breaking protrusion (a part of the side of the second protrusion) 42b

[0072] Top surface of the second chip-breaking protrusion 42u

[0073] Rake face 50

[0074] Workpiece (material to be cut) 100

[0075] Chip 101

[0076] Central axis AX1

[0077] First direction D1

[0078] Second direction D2

[0079] Third direction D3

[0080] Fourth direction D4

[0081] Direction perpendicular to the cutting edge (one of them) D5

[0082] Cutting edge height H

[0083] Inclination (inclined portion) S

[0084] First inclination (first inclined portion) S1

[0085] Second inclination (second inclined portion) S2

[0086] Gradient θ1 of the first inclination (first inclined portion)

[0087] Gradient θ2 of the second inclination (second inclined portion) Detailed implementation mode

[0088] Hereinafter, a preferred implementation mode of the cutting blade of the present invention will be described in detail with reference to the accompanying drawings (refer to Figure 1 etc.). Hereinafter, first, an overview of the cutting blade 10 used in the cutting of the workpiece (material to be cut) 100 will be described, and then the characteristic parts of the cutting blade 10 of the present invention will be described (refer to Figure 1 etc.). In addition, in the following description, for convenience, the terms "low region" and "medium region" are used. The "low region" refers to the range of cutting in a state where the depth of cut is relatively small or the cutting edge or chip breaker used in such cutting, and the "medium region" refers to the range of cutting in a state where the depth of cut is larger than that or the cutting edge or chip breaker used in such cutting.

[0089] 《Overview of the cutting blade》

[0090] Figure 1 The cutting blade 10 shown in etc. is configured to be mounted on the main body (not shown) of the cutting tool by rotating 180° around the central axis AX1 passing through the center of the upper surface 17 and perpendicular to the lower surface 19, so that either one of the pair of cutting edges 20 can be used (refer to Figure 1 , Figure 3 etc.). In the central part of the cutting blade 10, a threaded hole 18 for passing an installation screw (not shown) is formed so as to penetrate the upper surface 17 and the lower surface 19 (refer to Figure 2 , Figure 3 etc.). When the cutting blade 10 is mounted on the main body, the lower surface 19 functions as the mounting surface in contact with the main body.

[0091] The cutting blade 10 of the present embodiment includes: an upper surface 17, which is along the central axis AX1 and faces Figure 1The first end face above in it; the second end face facing downward opposite to the first end face, i.e., the lower surface 19; and the peripheral side face 15, which is composed of a first peripheral side face portion 11, a second peripheral side face portion 12, a third peripheral side face portion 13, and a fourth peripheral side face portion 14 that connect the upper surface 17 and the lower surface 19. To make the area of the lower surface 19 smaller than that of the upper surface 17, these first peripheral side face portion 11, second peripheral side face portion 12, third peripheral side face portion 13, and fourth peripheral side face portion 14 are all inclined in a suspended state (refer to Figure 4 ), so as to form the flank face of the cutting edge 20 (refer to Figure 4 , Figure 5 , etc.). In addition, as described above, the cutting insert 10 of the present embodiment has a symmetrical shape that can be rotated 180° around the central axis AX1 and used. Therefore, unless otherwise specified, the shapes or structures of the corner portions 36 or the cutting edges 20 described below are applicable to any one of the pair of components forming the symmetrical shape.

[0092] In a top view (refer to Figure 3 ), the shape of the upper surface 17 is a rhomboid (diamond) composed of a group of substantially parallel edge portions. For convenience, one of the extension directions of the longer one of the two diagonals of the rhomboid (referred to as the "length direction" in this specification) is set as the first direction D1, and the other is set as the third direction D3. One of the extension directions of the shorter one of the diagonals (referred to as the "width direction" in this specification) is set as the second direction D2, and the other is set as the fourth direction D4 (refer to Figure 1 , Figure 3 , etc.). Corner portions 36 are respectively formed in the first direction D1 and the third direction D3 of the cutting insert 10 (refer to Figure 2 , etc.). In addition, in order to represent the shape or structure of the cutting insert 10 when viewed from the side as described in the present embodiment, it can be considered that, compared with the view when viewed along the width direction (i.e., the view when viewed from the second direction D2 or the fourth direction D4), the view when viewed from the direction perpendicular to the cutting edge 20 (in the length direction) (for convenience, an example of such a direction is represented by the reference numeral D5. See Figure 3 , etc.) is easier to understand. In this specification, for convenience, the view when viewed along the direction D5 is referred to as a side view, and such a side view is shown in a part of the drawings (refer to Figure 7 , Figure 9 ).

[0093] On the intersection ridge line (edge portion) 16 between the peripheral side face 15 and the upper surface 17, a cutting edge 20 composed of a main cutting edge 21 and a corner cutting edge 25 is formed (refer to Figure 1 , etc.). The corner cutting edge 25 is formed on the above-mentioned corner portion 36. The main cutting edge 21 is formed to be connected to the corner cutting edge 25 (refer to Figure 2 , etc.).

[0094] On the upper surface 17, a protrusion 40 having a first chip-breaking protrusion (first protrusion) 41 and a second chip-breaking protrusion (second protrusion) 42 is formed from the corner 36 toward the central axis AX1 (see Figure 15 , Figure 16 wait).

[0095] The first chip breaking protrusion 41 is formed in a shape elongated and extending in the longitudinal direction at a position close to the corner portion 36 (see Figure 6 , Figure 16 The first chip-breaking projection 41 is formed to have an upper surface 41u, the height of which gradually increases from the corner 36 toward the central axis AX1 along the longitudinal direction (see Figure 7 The portion indicated by the arrow pointing to the upper right in the figure) reaches the peak point 41p while slowly inclining, and then gradually decreases as it moves from the peak point 41p toward the central axis AX1 (refer to Figure 7 ). In addition, the first chip breaking protrusion 41 is formed so that its peak point 41p is higher than the cutting edge 25t of the corner cutting edge 25 (see Figure 7 The first chip-breaking projection 41 of this shape helps to ensure a gap between the first chip-breaking projection 41 and the cutting edge 20 for breaking the chips (in Figure 14 The space for the flow of the chip 101 (indicated by symbol 101 in the figure) (the space such as the so-called groove) helps to suppress over-constraint. Regardless of the low area or the middle area, the generation of the chip 101 starts from the first chip breaking protrusion 41, which is the closest part of the corner cutting edge 25, under any conditions.

[0096] For a more detailed explanation of the above contents (refer to Figure 7etc.). Usually, if the front angle is too large, the chip 101 will follow the front cutting surface of the front cutting portion 50 and penetrate deeper. In this specification, the situation where the chip 101 hits the first chip breaking protrusion 41 in this state is called "overconstraint". The increase in the restraining force is beneficial in cutting the chip 101 finely, but on the other hand, there are other problems, that is, relative to the natural outflow of the chip 101, the chip 101 will be forcibly deformed and peeled off from the workpiece (cut material) 100, so it is easy to cause damage or burrs on the machined surface. Since a protrusion-type chip breaker is provided for chip cutting, it can be said that there is no way to some extent, but in fact, in products with a strong front angle of the corner 36, sometimes the chip 101 is blocked, overconstrained, and the surface is rough. In this embodiment, in view of such actual conditions, in order to solve the problem, the angle difference between the slope (angle) θ1 of the first inclination S1 and the front angle of the front cutting portion 50 is suppressed, so that the part can be made flatter. In addition, it can be said that the reason why the first chip breaking protrusion 41 is lowered after the peak value (after exceeding the peak point 41p) is similarly because the higher the protrusion height is when viewed from the cutting edge cross section, the stronger the constraint on the chip 101. In addition, if the optimal rake angle is set for the portion provided with the first inclination S1, the portion can be flattened.

[0097] The second chip-breaking protrusion 42 is formed to be connected to the first chip-breaking protrusion 41. The second chip-breaking protrusion 42 of the present embodiment has a top surface 42u inclined in a manner that increases in height from the first chip-breaking protrusion 41 toward the central axis AX1, and also has a first-stage wall surface 42a and a second-stage wall surface 42b (see Figure 2 , Figure 15 The top surface 42u may include a streamlined portion that gradually increases in height, or may be composed of a multi-level wall surface. The first-level wall surface 42a is mainly used as a guide to constrain the chips 101, and the second-level wall surface 42b, although not directly contributing to the cutting performance, is formed in a manner to ensure a groove for the chips 101 to flow. In addition, the first-level wall surface 42a and the second-level wall surface 42b are basically configured to form a secondary structure that does not form a large space for guiding the chips 101 generated in a spiral shape. In the present embodiment, the main configuration is to make the first-level wall surface 42a function as a guide, and the second-level wall surface 42b is set to a structure that appropriately avoids (expands the space).

[0098] The first-stage wall surface 42a is formed as a wall surface that particularly functions during machining in the middle region. The first-stage wall surface 42a may be composed of multiple-stage wall surfaces, but it suffices to be formed in a smoothly changing streamline shape. The first-stage wall surface 42a in the present embodiment is composed of a wall surface that stands up from the rake face 50 toward the top surface 42u, and is particularly formed to function as a guide that restrains the chip 101 generated by being cut by the main cutting edge 21 during machining in the middle region (see Figure 1 etc.). The first-stage wall surface 42a of the present embodiment is formed in such a manner that, for example, as it moves away from the corner 36, the space gradually narrows to form a space (chip groove) of an appropriate size and shape between the first-stage wall surface 42a and the rake face 50 through which the chip 101 can flow smoothly rearward (in the direction away from the corner 36). Such a first-stage wall surface 42a particularly guides (assists) the smooth flow of the chip 101 during machining in the middle region, and furthermore, can also achieve effects such as suppressing chip entanglement caused by the oscillation of the chip 101 (see Figure 14 etc.).

[0099] The second-stage wall surface 42b is formed as a wall surface that functions to guide the smooth flow of the chip 101 that has passed over the first-stage wall surface 42a. Assuming that an extremely long chip groove remains on the middle region side, in the case of generating a long spiral-shaped chip 101, such a chip 101 cannot be completely processed, which may cause oscillation and entanglement. Therefore, in the present embodiment, such a situation is envisaged so that the chip 101 that has passed over the first-stage wall surface 42a can be processed by the second-stage wall surface 42b.

[0100] A rake face 50 is formed between the protrusion 40 and the cutting edge 20 (see Figure 2 , Figure 6 etc.). The rake face 50 is a part that functions as the rake face of the cutting edge 20 during machining (see Figure 10 , Figure 12 ), and is formed with a prescribed rake angle. Although not particularly illustrated, the rake angle of the rake face 50 can be defined as the corresponding rake face 50 angle relative to the horizontal plane (a plane parallel to the upper surface 17 or the lower surface 19) in a cross-section perpendicular to the cutting edge 20. In the present embodiment, the rake face 50 is formed in such a manner that as it moves away from the corner 36, the angle of the rake angle gradually (gradually and continuously) increases (in other words, in such a manner that a slight twist is applied to the rake face). In addition, the rake face 50 of the cutting insert 10 in the present embodiment is formed such that as it moves away from the corner 36, the angle of the rake angle increases and does not increase after reaching the deepest part 20d of the cutting edge 20 (see Figure 5 ).

[0101] In addition, the front cutting portion 50 is formed as a smooth surface near the corner portion 36. The smoothness mentioned here does not refer to flatness, but rather to the degree of smoothness that can make the outflow of the chip 101 during cutting smoother. Importantly, if a rake angle is specifically set or the first chip breaker projection 41 is formed near the corner portion 36, at least irregularities will be formed, so it will not be strictly flat in the strict sense. However, here, focusing on the point that the closer the surface near the corner portion 36 is to being smooth, the easier it is for the chip 101 to flow smoothly, attention should be paid to making it smooth to at least the extent that the above effects can be achieved (refer to Figure 8 etc.). In other words, the rake face constituting the front cutting portion 50 is a composite surface formed by the slopes (θ1, θ2) of the inclined S and the rake angle. In the cutting insert 10 of the present embodiment, a rake angle is provided at the corner portion 36. Even when observing only within the range of the first inclination S1, since it is a structure in which the rake angle is small but continuously changes, although it is not strictly flat, it is formed smoothly. To put it further, if the chip 101 is to be cut into finer pieces, it is desirable to impose constraints, so it is desired to make the rake angle slightly stronger. However, if this is done excessively, it will become overconstrained. Therefore, the balance from this perspective is also important.

[0102] On the cutting edge 20, an inclination (inclined portion) S is provided in such a way that as it moves away from the corner cutting edge 25, the cutting edge height (referring to the distance from the surface parallel to the lower surface 19 to the cutting edge 20, denoted by the symbol H in the figure) gradually decreases (refer to Figure 7 , Figure 9 etc.). The inclination S in the cutting insert 10 of the present embodiment is composed of a first inclination S1 starting from the middle of the corner cutting edge 25 and a second inclination S2 connected to the first inclination S1 and having a slope θ2 larger than the slope θ1 of the first inclination S1 (refer to Figure 9 etc.). The first inclination S1 starting from the middle of the corner cutting edge 25 particularly serves to introduce the chip 101 in the low region (low cutting depth) to the first chip breaker projection 41 at an earlier stage. Through such an inclination S, the cutting edge 20 is inclined, and the chip 101 flows out along the rake face extending along the cutting edge 20. At this time, on the basis that the curling (upward curling) shown by the arrow in Figure 11 is promoted, the chip 101 comes into contact with the first chip breaker projection 41 that it contacts most recently. In the cutting insert 10 of such a present embodiment, as little as possible, unnecessary elements that cause the chip 101 to bend are not given to the chip 101. Priority is given to making the chip 101 flow out in a more stable spiral state rather than cutting, to achieve smooth discharge of the chip 101.

[0103] As described above, in the cutting blade 10 provided with the inclination S, the rake face 50 near the corner 36 can also be formed such that its rake angle is the same as the slope of the first inclination S1. The specific numerical value is not particularly limited. For example, the slope θ1 of the first inclination S1 can be set to 5°, and the rake angle of the rake face 50 near the corner 36 can be set to the same 5°. For example, if an excessive rake angle is given, upward bending caused by the inclination S and lateral bending caused by the rake angle will occur, and the chip 101 will be difficult to flow smoothly. In this case, the chip 101 is likely to be clogged, and chips 101 with a forced tearing shape are likely to be generated. In this way, the quality of the machined surface may sometimes deteriorate in the form of a gouged surface or a white turbid surface. Regarding this point, according to the cutting blade 10 of the present embodiment having the above-described structure, strong bending is minimized in the rake face 50 (near the corner 36), and the chip 101 can flow smoothly in a certain direction and toward the first chip breaker protrusion 41 at an earlier stage. Importantly, it is not preferable to overly bend the chip 101. In this regard, the cutting blade 10 of the present embodiment can be said to be a structure that focuses on smoothly flowing the chip 101 on the rake face.

[0104] 《Overview of the Features of the Cutting Blade》

[0105] If the outline of the features of the cutting blade 10 of the present embodiment configured as described above is described together with the process up to when the present inventor thought of the features and the considerations, etc., it is as follows.

[0106] When cutting using the cutting blade 10, due to the requirements for improving the chip 101 in the outer diameter turning of the automatic lathe and the low region (micro cutting depth), first, based on this, the shape of making the protrusion (the first protrusion) as close as possible to the corner cutting edge was studied. However, it was found that if this is done, the width of the chip breaker becomes too narrow or the chip 101 is bent with a strong (large) rake angle, etc., which has an impact. Especially in the middle region where the rake angle is relatively large, it becomes a so-called overconstrained condition, affecting the machined surface. In other words, it can be thought that in the case of chip 101 clogging, the chip 101 generated from the workpiece (material to be cut) 100 in the machining region is forcibly bent and cut very obviously. That is, as a result of so-called forced tearing, surface roughness or surface white turbidity is likely to occur, and the quality of the machined surface deteriorates. Considering these, in the present embodiment, the design is carried out by giving priority to the chip discharge performance in the low region. Specifically, (i) an inclination S is provided on the cutting edge 20 to promote upward curling (by the inclination S provided on the cutting edge 20, as the distance from the corner 36 increases, the cutting edge height H and the rake face decrease together. Therefore, if it is Figure 10 in the middle, the chip 101 moves in the direction upward with respect to the paper surface, as Figure 14(A) shows that the chip 101 is formed into a spirally long cylindrical shape, and (ii) in order to promote curling (i.e., to pull the chip toward the first chip breaking protrusion 41), the starting position of the inclination S is located within the corner 36. In addition, from the results of various comparative tests, it can be seen that when the front angle of the front blade portion 50 is close to the inclination of the inclination S, the outflow performance of the chip 101 in the low area is smoother. Therefore, by adopting a structure in which the inclination of the inclination S is approximately equal to the front angle, an extremely curved shape is not formed, and the chip 101 flows smoothly from the front blade surface of the corner 36 to the first chip breaking protrusion 41. However, the height of the first chip breaking protrusion 41 does not become extremely high, and is formed into a shape that suppresses the chip 101 as much as possible only at the front end (the portion of the cutting insert 10 where the first chip breaking protrusion 41 is formed). The cross-section of the first chip breaking protrusion 41 is also preferably a gentle shape. The height of the first chip breaker projection 41 is gradually reduced along with the inclination S of the cutting insert 10 , and is in a shape that forms a space (chip groove) for the chips 101 to flow out.

[0107] In addition, as another requirement for the cutting insert 10, there is a requirement to deal with the problem of a large number of burrs / chatters generated in the semi-finishing of stainless steel. In this regard, as described above, while designing the discharge performance of the chips 101 in the low region with priority, the effective cutting edge is also extended in the middle region for processing (in the cutting insert 10 of the present embodiment, the effective cutting edge is formed in the side view (refer to Figure 5 ) or side view (refer to Figure 9 ) the main cutting edge 20 reaches the deepest part (at Figure 5 In this case, in order to reduce the cutting resistance during cutting in the middle area, a front blade portion 50 having a larger front angle in the middle area than in the low area is formed to suppress burrs / chatter. In addition, a second inclination S2 is formed that is deeper (increased) than the first inclination (the first level inclination in the low area) S1. Such a second inclination S2 further promotes cutting along the Figure 13 In addition, by making the inclination θ2 of the second inclination S2 larger than the rake angle (of the rake portion 50 at this location), the cutting performance can be improved, thereby forming a structure that improves anti-vibration performance, suppresses burr generation, and reduces cutting resistance.

[0108] In addition, particularly for the middle region, a second chip breaker projection 42 with a two-stage cross-section is formed. Regarding this second chip breaker projection 42, a structure in which it descends along the inclination S could be considered, similar to the first chip breaker projection 41. However, in such a case, the chip groove would be too wide, and under conditions such as high cutting depth / low feed, the chip 101 with a width would be discharged while swinging, resulting in unstable chip outflow / generation, which is the same problem as that of conventional cutting inserts. Considering this, in the present embodiment, different from the low region, in the middle region, the chip groove is considered to be formed in a relatively narrow structure, and at the same time, the second chip breaker projection 42 is formed. The second chip breaker projection 42 has multiple stages and forms a space that is not too large, so as to be a guide for the chip 101 that is spirally generated mainly by the first-stage wall surface 42a. And the second-stage wall surface 42b is formed in a shape that moderately expands the space, realizing the discharge performance of the chip 101 and ensuring the chip groove. Through these functions, the long and stable spiral chip 101 is discharged (refer to Figure 14 (A)). On the other hand, in the case of a conventional cutting insert that does not achieve such a function, even if there is no problem with the outflow of the chip 101 in the spiral part, when the chip groove is wide and has a high degree of freedom, the tendency to elongate and entangle due to swinging during machining is enhanced (refer to Figure 14 (B)). Particularly, in the case of an automatic lathe application, compared with a general lathe, the ratio of the feed to the cutting depth amount is extremely low, so it is likely to become such a phenomenon (in the case of a general lathe, the ratio of the feed amount is large and the chip 101 becomes thicker). In this case, the chip groove becomes narrow and is easily blocked, resulting in defects, etc.). Therefore, considering such problem points, in the present embodiment, in the middle region, the chip groove is restricted to a certain extent, and a structure is formed in which the first-stage wall surface 42a of the second chip breaker projection 42 serves as a guide for the flow.

[0109] The cutting blade 10 of the present embodiment having the above characteristics realizes covering a wide area from a low region (micro finishing) to a middle region (medium cutting) with one blade. In other words, a structure with an expanded applicable range is achieved, which is suitable for finishing (low cutting depth and low feed machining) while also being able to achieve high-quality cutting when forming a high cutting depth. This is because, in particular, as described above, the first chip breaker projection 41 is provided with a structure that ensures a space for the chip 101 to flow while suppressing overconstraint, and further, the second chip breaker projection 42 with a two-stage structure that emphasizes guiding the chip 101 is provided. Additionally, by adjusting the inclination (slant) of the cutting edge 20 when viewed from the side (i.e., changing the slope by the use of the first chip breaker projection 41 and the second chip breaker projection 42), the applicable range is further expanded on the high cutting depth side. Moreover, by gradually changing the rake angle of the rake face 50, the cutting resistance is reduced and the applicable range is further expanded. In this way, in combination with the action of the so-called optimized projection part 40 (the first chip breaker projection 41 and the second chip breaker projection 42), smooth chip generation / discharge without overconstraint is achieved.

[0110] In addition, the above embodiment is an example of a preferred implementation of the present invention, but is not limited thereto. Various modifications can be made without departing from the gist of the present invention.

[0111]

Industrial Applicability

[0112] The present invention is applicable to cutting blades for cutting machining (mainly for turning).

Claims

1. A cutting insert, characterized in that, Comprising: The upper surface as the first end face; The lower surface as the second end face, which is the face on the side opposite to the upper surface and has a mounting surface for mounting a cutting tool to the main body; The peripheral side face, which is formed to connect the upper surface and the lower surface; The cutting edge, which has a main cutting edge and a corner cutting edge formed on the intersecting ridge line of the upper surface and the peripheral side face; The corner part including the corner cutting edge; The protrusion part, which has a first protrusion formed by elongating slenderly from the corner part toward the central axis passing through the center of the upper surface and extending in a direction perpendicular to the lower surface, and having a top surface that becomes lower as it moves from the corner part toward the central axis, and a second protrusion connected to the first protrusion and having a top surface that becomes higher as it moves from the first protrusion toward the central axis; The rake face formed between the protrusion part and the cutting edge; and The inclined part, which is provided on the cutting edge midway from the corner cutting edge, such that the height of the cutting edge gradually decreases as it moves away from the corner cutting edge, The inclined part has a first inclined part starting midway from the corner cutting edge, and a second inclined part connected to the first inclined part and having a greater slope than the first inclined part; The rake face is shaped such that the angle of the rake angle gradually increases as it moves away from the corner part.

2. The cutting insert according to claim 1, wherein, The rake face near the corner part forms a substantially smooth surface.

3. The cutting insert according to claim 2, wherein, The rake face near the corner part is shaped such that the rake angle is formed to be consistent with the slope of the first inclined part.

4. The cutting insert according to claim 3, wherein, The rake face is formed such that the angle of the rake angle gradually increases as it moves away from the corner part.

5. The cutting blade according to any one of claims 1 to 4, wherein, The peak point of the first protrusion is higher than the tip of the corner cutting edge.

6. The cutting blade according to claim 5, wherein, The first protrusion gradually decreases as it moves from the peak point toward the central axis.

7. The cutting insert according to any one of claims 1 to 6, wherein, A top surface is formed on the second protrusion, and the top surface has a portion that is inclined so as to become higher as it moves from the first protrusion toward the central axis.

8. The cutting insert according to claim 7, wherein, The side part of the second protrusion is formed in a multi-stage shape.

9. The cutting insert according to claim 8, wherein, A wall surface is formed in the part of the second protrusion between the top surface and the rake face.

10. The cutting insert according to claim 9, wherein, The wall surface has: a first-stage wall surface standing up from the rake face; and a second-stage wall surface provided between the first-stage wall surface and the top surface.

11. The cutting insert according to claim 10, wherein, The first-stage wall surface is formed such that the size of the space formed between the first-stage wall surface and the rake face gradually decreases as it moves away from the corner part to allow the chip to flow.

Images