WO2014073480A1

WO2014073480A1 - Cutting tool edge structure and cutting insert and cutting tool using said structure

Info

Publication number: WO2014073480A1
Application number: PCT/JP2013/079713
Authority: WO
Inventors: 竜也喜多
Original assignee: 株式会社タンガロイ
Priority date: 2012-11-07
Filing date: 2013-11-01
Publication date: 2014-05-15
Also published as: JPWO2014073480A1; JP5936175B2

Abstract

Provided is a cutting tool edge structure capable of controlling the direction of chip outflow to prevent severe collisions between chips flowing out from cutting edges extending in different directions from a cutting corner. At a region of one cutting edge (53) near a corner (51), a recessed section (60) having a first inner wall surface (61) and a second inner wall surface (62) is formed. Here, the length of the ridge line (62a) of the second inner wall surface (62) when viewed from the direction facing the upper surface (20) is longer than the ridge line (61a) of the first inner wall surface (61) when viewed from the same direction and the angle (β) formed by the cutting edge (53) and the ridge line (62a) of the second inner wall surface (62) is appropriately set.

Description

Cutting edge structure of cutting tool and cutting insert and cutting tool using the structure

The present invention relates to a cutting edge structure of a tool for cutting and a cutting insert and a cutting tool using the structure, and more particularly to a structure for smoothing outflow of chips.

Conventionally, cutting inserts of various shapes have been used in the field of rotary cutting tools. For example, Patent Document 1 discloses a cutting insert used for a milling tool, and Patent Document 2 discloses a cutting tool used for a blade-exchangeable drill. An insert is disclosed. And in these patent documents, the structure which the cutting edge provided in both sides across the corner part of the cutting insert cuts simultaneously, and the structure which intends discharging | emitting a chip smoothly are described. .

JP 2011-93043 A US Pat. No. 7,575,400

However, these patent documents do not take into consideration any chip flow that occurs when the cutting edges on both sides of the corner portion cut simultaneously. Chips tend to flow out in a direction substantially perpendicular to the cutting edges, so the greater the angle formed by the cutting edges, the greater the angle at which the flow of chips flowing out from each cutting edge intersects, and the chips flowing out from each other Collide violently. When the chips collide violently in this way, the direction of flow of the respective chips changes greatly, so that the chips are often not discharged smoothly, or the cutting insert and the tool body are often damaged and damaged. . As a result of intensive studies by the inventor, this chip-to-chip collision is caused by chips flowing out of the cutting edge near the corner rather than chips flowing out of the cutting edge relatively far from the corner. And obtained the knowledge that it occupies a major part of the above problem.

In view of the above problems, an object of the present invention is to provide a structure that suppresses a collision between chips flowing out in two different directions from the vicinity of a corner portion.

For this purpose, the present invention includes a polygonal end face (20) and a side face (40) connected to the end face (20), and an intersecting ridge line part () between the end face (20) and the side face (40) ( 50), at least the first and second ridgelines sandwiching the bent portion (51) formed by one vertex of the polygon act as the first and second cutting edges (53, 54), respectively. A cutting edge structure of a cutting tool including a part,
A first portion (53a1) formed on at least a first flank (41) connected to the first cutting edge (53), and the first cutting edge (53) close to the bent portion (51); A recess (60) that divides into a second part (53a2) far from the bent part (51);
The recess (60) includes a first inner wall surface (61) including a ridge line (61a) connected to the first part (53a1) and a ridge line (62a) connected to the second part (53a2). A second inner wall surface (62),
When viewed from the direction facing the end surface (20), the ridge line (62a) included in the second inner wall surface (62) is longer than the ridge line (61a) included in the first inner wall surface (61). Provide a cutting edge structure.

The present invention also resides in a cutting insert and a cutting tool provided with the above-mentioned cutting edge structure.

According to the present invention, the concave portion (60) having a triangular shape as viewed in plan is formed in the portion of the first cutting edge (53) in the vicinity of the bent portion (51), and the first cutting edge (53 ) Is divided into a first part (53a1) close to the bent part (51) and a second part (53a2) far from the bent part (51). As a result, the chips flowing out from the cutting edge (53) are subdivided and the flow of chips from the first part (53a1) is weakened, so the chips flowing out from the second cutting edge (52) No longer obstruct the flow of Further, the cross ridge line (62a) between the inner wall surface (62) of the recess (60) and the rake face of the end face (20) and connected to the second portion (53a2) also acts as a cutting edge. The strength of the flow of chips flowing out from the second portion (53a2) is greater than the strength of the flow of chips flowing out from the second portion (53a2). Therefore, the chip flow generated from the second portion (53a2) is forcibly bent by the chip flow generated from the intersecting ridge line (62a) and integrated therewith, and flows in the same direction. As described above, the collision state of the chip flow generated from the pair of cutting edges (53, 54) sandwiching the bent portion is suppressed.

FIG. 1 is a perspective view of a cutting insert according to a first embodiment of the present invention. FIG. 2 is a plan view of the cutting insert according to the first embodiment of the present invention. FIG. 3 is a side view of the cutting insert according to the first embodiment of the present invention as seen from the side surface where the recess is formed. FIG. 4A is a schematic plan view of the cutting insert of the first embodiment, and FIG. 4B is a portion IV (b) in FIG. 4A for explaining the recess according to the first embodiment. FIG. FIG. 5A is a schematic plan view of the cutting insert of the first embodiment, and FIG. 5B is a portion V (b) in FIG. 5A for explaining the chip discharge direction in the vicinity of the corner portion. ) Is an enlarged schematic diagram. FIG. 6A is a schematic plan view of the cutting insert of the first embodiment, and FIG. 6B is a portion VI (b) in FIG. 6A for explaining the outflow direction of chips in the vicinity of the recess. It is a schematic diagram which expands and shows. FIG. 7 is a schematic diagram for explaining a chip discharge direction as the entire cutting insert according to the first embodiment. FIG. 8 is an explanatory diagram for explaining the honing width and the imaginary line length of the cutting insert according to the first embodiment. FIG. 9 is a perspective view of a cutting insert according to the second embodiment of the present invention. FIG. 10 is a plan view of a cutting insert according to the second embodiment of the present invention. FIG. 11 is a side view of a cutting insert according to the second embodiment of the present invention. FIG. 12 is a perspective view of a drill using the cutting insert of the second embodiment. FIG. 13 is a front view of a drill using the cutting insert of the second embodiment. FIG. 14 is a tip view of a drill using the cutting insert of the second embodiment.

Hereinafter, some embodiments of the present invention will be described with reference to the drawings. The gist of the present invention is to provide a recess having a special shape in the vicinity of the corner portion of the bending edge, so that chips flowing out from the cutting edge on the side where the recess is provided are subdivided, and the outflow direction is a preferred direction. It is to adopt a structure that can be changed to.

(First embodiment)
1 to 3 are views of the cutting insert according to the first embodiment of the present invention as seen from each direction. The outer shape of the upper surface 20 that is the first end surface and the lower surface 30 that is the second end surface of the cutting insert 10 of the present embodiment is a substantially parallelogram having two long sides and two short sides, Cutting edges are formed at the intersection ridges 50 between the respective surfaces and the side surfaces 40. The side surface 40 intersects the upper surface 20 and the lower surface 30 at 90 °, and the cutting insert 10 is configured as a so-called negative type having a clearance angle of 0 °. A screw hole 70 penetrating from the upper surface 20 to the lower surface 30 is formed, and the cutting insert 10 is fixed to a tool body (not shown) by a screw inserted through the screw hole 70.

In the following description, the phrase “viewed from the direction facing the upper surface” means observing the upper surface 20 from a direction perpendicular to the seating surface that is a contact surface with the tool body. When the lower surface 30 is a flat surface as in the present embodiment, the above wording means a so-called planar view. On the other hand, the phrase “viewed from the direction facing the lower surface” means that the lower surface 30 is observed from a direction perpendicular to the seating surface that is a contact surface with the tool body. When the upper surface 20 is a flat surface as in this embodiment, the above wording means a so-called bottom view. Furthermore, the phrase “viewed from the direction facing the side surface” means to observe from a direction perpendicular to the side surface. However, in the case of a side surface having a clearance angle, it means viewing from a direction in which the area of the surface to be observed is parallel to the seating surface and maximizes.

The crossed ridge line portion 50 having a parallelogram shape includes two

obtuse corner portions

51 and 51 ′, two acute

angle corner portions

52 and 52 ′, two ridge lines that are long sides of the parallelogram, and a short side. And two ridgelines. Each of the two ridge lines that are long sides includes a portion that becomes a first cutting edge (hereinafter referred to as

long cutting edges

53 and 53 ′ in the present embodiment), and each of the two ridge lines that are short sides is a second cutting edge. This includes a portion (hereinafter referred to as a short cutting edge 54, 54 'in the present embodiment). Note that the corner portion conforms to the definition of JIS B 0170 “a relatively small range of cutting edge portions that connect one cutting edge to another cutting edge”. Speaking in line with this, it means “a curved cutting edge part connecting cutting edges, and its extremely small part”. Further, the terms “obtuse angle” and “acute angle” for specifying the shape of the corner portion are defined with respect to an angle formed by ridge lines extending at both ends of the corner portion when viewed in plan. Further, the “cutting edge” means a ridge line portion in a cutting edge structure that participates in (or can participate in) the cutting of the workpiece.

On one long cutting edge 53 and the

upper surfaces

20 and 40 connected thereto, a recess 60 is formed in the vicinity of the obtuse corner part 51, and the long cutting edge 53 is close to the obtuse corner part 51 across the recess 60. It is divided into a portion 53a1 and a cutting edge portion 53a2 far from the obtuse corner portion 51. The concave portion 60 has a substantially triangular shape when viewed from the direction facing the upper surface 20. As will be described later, the fragmentation of the chips flowing out from the long cutting edge 53 and the control of the direction in which the chips flow out. I do.

The recess 60 includes a first inner wall surface 61 that is an inner wall surface located on the side closer to the obtuse corner portion 51, a second inner wall surface 62 that is an inner wall surface located farther from the obtuse corner portion 51, and a first inner wall surface. 61 and a connecting surface 63 that connects the second inner wall surface 62 to each other. The connecting surface 63 is not limited in shape, and may be formed by a single curved surface as shown in FIGS. 2, 4A and 4B, or may be formed by a single plane. It may be a thing. Alternatively, a plurality of curved surfaces, a plurality of planes, or a combination of a plurality of curved surfaces and a plane may be used.

As shown in FIG. 4B in which a broken line portion in the top view (FIG. 4A) of the cutting insert 10 of the present embodiment is enlarged, the top surface 20 and the first inner portion are viewed from the direction facing the top surface 20. The ridge line 61a with the wall surface 61 intersects the cutting edge portion 53a1 of the long cutting edge 53 at an angle α of about 100 °. This angle is appropriately set within a range in which the chips are sufficiently subdivided and sufficient fracture resistance is secured at the intersection between the recess 60 and the cutting edge portion 53a1. A standard for this angle α is about 100 ° ± 15 °.

The ridge line 62 a between the upper surface 20 and the second inner wall surface 62 is significantly longer than the ridge line 61 a of the first inner wall surface 61 and is set to be three times or more. Therefore, a virtual line P formed by connecting the connection portion Q1 between the first inner wall surface 61 and the cutting edge portion 53a1 and the connection portion Q2 between the second inner wall surface 62 and the cutting edge portion 53a2 (FIG. 4B). ), The angle β formed by the ridge line 62a between the upper surface 20 and the second inner wall surface 62 with respect to the virtual line P is a relatively small value. Further, the position of the connecting surface 63 is also largely shifted to the connection portion Q1 side. The angle β is preferably as small as possible within a range in which chip fragmentation is achieved. Therefore, the length of the ridge line 62a of the second inner wall surface 62 is not less than five times the length of the ridge line 61a of the first inner wall surface 61. It is preferable. On the other hand, the crossing angle between the ridgeline 62a of the second inner wall surface 62, which is the angle β or the outer angle thereof, and the long cutting edge 53 is by appropriately regulating the flow direction of chips generated by the long cutting edge 53, It is preferable that the value be set to a value that can prevent a severe collision of chips generated in the vicinity of the corner portion (the obtuse corner portion 51 in this embodiment), which is the subject of the present invention.

In the upper surface 20, the direction perpendicular to the ridge line 62 a of the second inner wall surface 62 is a direction away from the obtuse corner portion 51 when the direction perpendicular to the long cutting edge 53 is taken as a reference. This direction coincides with the flow direction of chips generated at the ridge line 62a. By turning this outflow direction away from the obtuse corner portion 51, as will be described later, the outflow direction of chips generated by the cutting edge portion 53a2 on the opposite side of the concave portion 60 across the connecting portion Q2 is changed. It contributes to that.

The length of the ridge line 62a is determined in relation to the cutting depth assumed when the cutting insert 10 is used. That is, the length of the cutting edge portion 53a2 that is a cutting edge portion that is connected to the recess 60 at a position far from the obtuse corner portion 51 and that is involved in cutting when the maximum possible rightward cutting in the drawing is performed. The ridgeline 62a is set to be longer than that. The ridge line 62 a is formed so as to act as a cutting edge when cutting is performed with a cutting amount exceeding the recess 60. And the length is set so that the width of the chip generated at the ridgeline 62a is larger than the width of the chip generated at the adjacent cutting edge portion 53a2. If another expression is used, when the cutting insert 10 of the present embodiment is used within a range where the length of the cutting edge portion 53a2 is smaller than the length of the ridgeline 62a, the effect is maximized. The

As shown in FIG. 3, when viewed from a direction facing one side surface (hereinafter also referred to as the first flank 41) connected to the long cutting edge 53, the side surface and the first inner wall surface 61 The ridge line 61b is inclined, and the end portion 61b2 of the ridge line 61b on the lower surface 30 side is located closer to the obtuse corner portion 51 than the end portion 61b1 of the ridge line 61b on the upper surface 20 side. This will be explained using an expression according to FIG. 3. When the ridge line 61b is observed in a side view with the upper surface 20 facing upward, the ridge line 61b becomes closer to the obtuse corner portion 51 as the distance from the end portion 61b1 increases. So it extends to the right. With such a configuration, when the cutting insert 10 is used so that the upper surface 20 becomes a rake face, a sufficient gap can be secured between the first flank 41 and the work material. Excessive contact can be prevented.

Hereinafter, the operation of the cutting insert 10 of the present embodiment will be described. By forming the recess 60 in the vicinity of the obtuse corner portion 51a, the long cutting edge 53 is divided, and a cutting edge portion 53a1 and a cutting edge portion 53a2 sandwiching the recess 60 are formed. Note that the cutting edge portion 53a2 refers not only to the entire ridge line from the connection portion to the concave portion 60 to the acute corner portion 52, but only to a cutting participating portion that acts as a cutting edge during cutting as described above.

When the cutting insert 10 starts cutting with the obtuse corner portion 51 as the distal end side, as shown in FIG. 5 (b) in which a broken line portion in the top view (FIG. 5 (a)) of the cutting insert 10 is enlarged, Chips flow out from the cutting edge portion 53a1 and the short cutting edge 54a of the blade 53 in directions orthogonal to each other. The arrow A in FIG. 5 (b) indicates the flow direction of chips generated from the cutting edge portion 53a1 (corresponding to the flow direction of chips generated from the long cutting edge 53 when there is no recess 60), and the arrow B is short. An outflow direction of chips generated from the cutting edge 54 is shown.

At this time, since the width of the chip flowing out from the cutting edge portion 53a1 is extremely smaller than the width of the chip flowing out from the short cutting edge 54, the weight per unit length of the chip is also from the cutting edge portion 53a1. The one that flows out is lighter. Therefore, although the outflow direction of the two chips intersects at a deep angle, the outflow direction of the chip flowing out from the cutting edge portion 53a1 is forcibly bent by the outflow from the short cutting edge 54a, resulting in a short cut. It flows in the direction of arrow B which is the same as the flow direction of chips flowing out from the blade 54a. As described above, according to the cutting insert of the present embodiment, the flow of one chip (here, the flow from the short cutting edge 54a) is obtained by intentionally changing the strength of the chip flow. Can be prevented from obstructing the flow of the other chip (here, the flow from the cutting edge portion 53a1), and as a result, the chip flows smoothly as a whole.

When the depth of cut is large to some extent, the ridgeline 62a and the cutting edge portion 53a2 also act as cutting edges, and as shown in FIG. 6 (b) in which the broken line portion in the top view (FIG. 6 (a)) of the cutting insert 10 is enlarged, Chips are generated from each. Also at this time, since the ridge line 62a is longer than the cutting edge portion 53a2, the same phenomenon as described above occurs, and the outflow direction of the chips flowing out from the cutting edge portion 53a2 (arrow D) flows out from the ridge line 62a. It will be forced to bend in the direction of chip flow (arrow C).

Furthermore, the ridgeline 62a is inclined by an angle β with respect to the virtual line P as described above with reference to FIG. Therefore, as shown in FIG. 7, the angle of intersection between the arrow B (the chip outflow direction from the short cutting edge 54) and the arrow C (the chip outflow direction from the ridge line 62a) is an arrow B and an arrow A ( As indicated by the phantom line, the crossing angle is smaller than the crossing angle of the outflow direction from the long cutting edge 53a when the recess 60 is not present. Thereby, according to this embodiment, the collision state of chips is relieved greatly, and the effect that chips will flow more smoothly than before is obtained.

As described above, the recess 60 provided in the cutting insert according to the present embodiment is different from the nick that is conventionally employed to simply divide the cutting edge to generate fine chips. (1) Smoothing outflow of chips near the corner by subdivision, (2) Forcibly changing the outflow direction of chips by causing a part of the ridge line of the recess 60 to act as a cutting edge, (3) Main The three effects of crossing the flow direction of chips from the two locations at a shallow angle are exhibited.

As a more preferable shape, as shown in FIG. 8, when the length of the phantom line P is L and the width of honing when viewed from the direction facing the upper surface 20 is H, the angle β is expressed by the following formula tan β> H / L (Formula 1)
It will be of a size that meets the requirements. Note that the honing width H is the length from the position of the honing start to the position of the honing end when viewed from the direction facing the upper surface 20. By setting the angle β in such a size range, the sharpness when the ridgeline 62a acts as a cutting edge is improved. By improving the sharpness, the chips smoothly flow out, and the action of effectively entraining the chips flowing out from the cutting edge portion 53a2 and forcibly bending the flow in a preferable direction is enhanced.

As shown in FIG. 3, when viewed from the first flank 41 side and in a direction parallel to the first inner wall surface 61, the angle ε formed by the cutting edge portion 53a1 and the ridge line 61b is 60 ° or more and 80 °. When it is below, the gap between the work material and the cutting insert 10 when the cutting insert 10 is attached to the tool body can be sufficiently secured, and at the same time, the intersection of the cutting edge portion 53a1 and the first inner wall surface 61. Improves fracture resistance. In other words, in terms of such a view, a position where only the ridge line 61b of the first inner wall surface 61 can be seen and other parts of the first inner wall surface 61 cannot be seen among various views of viewing the side surface. And view from an angle.

As another preferred embodiment, as shown in FIG. 8, the angle γ formed by the ridge line 61a of the first inner wall surface 61 and the ridge line 62a of the second inner wall surface 62 when viewed from the direction facing the upper surface 20 is used. Is from 50 ° to 120 °, more preferably from 80 ° to 100 °. When the angle γ is within this range, the intersection between the concave portion 60 and the long cutting edge 53 is not too sharp and it is difficult for a sudden defect to occur.

As the recess 60 is formed closer to the corner portion (in the present embodiment, the obtuse corner portion 51), the chips are preferable. In particular, although different from the illustrated configuration, if the length of the cutting edge portion 53a1 is shorter than the ridge line 61a of the first inner wall surface 61, chips are more easily subdivided.

In addition, although the structure which provided the recessed part 60 only in the long cutting edge 53 above was demonstrated, the same recessed part can also be provided in the long cutting edge 53 ', for example. That is, when viewed from the direction facing the upper surface, the cutting insert 10 is rotated 180 degrees with respect to the axis of the screw hole 70 by providing a recess at a rotationally symmetrical position with respect to the diagonal line connecting the

acute corner portions

52 and 52 ′. It is also possible to make it usable.

(Second Embodiment)
9 to 11 are views of the cutting insert according to the second embodiment of the present invention as seen from each direction. 12 to 14 are views showing a state when the cutting insert of the second embodiment is attached to the tool body of the drill. In these drawings, parts having the same functions as those in the first embodiment are denoted by the same reference numerals as those used in FIGS.

The cutting insert 100 of this embodiment is a cutting insert for a drill, and particularly a cutting insert for a two-blade drill as shown in FIGS.

The cutting insert 100 is configured such that the same shape as those figures appears even if the front and back are reversed so that the lower surface on the back side of the upper surface 20 shown in FIGS. 9 and 10 becomes the upper surface. That is, the cutting insert 100 of this embodiment is 180 ° rotationally symmetric with respect to a line R of a rotation axis (FIG. 10) that is parallel to the seating surface 21 formed on the upper surface 20 and passes through the center of the cutting insert 100. It has a (two-fold symmetry) shape. To explain this in another intuitive expression, the cutting insert 100 has a two-fold symmetrical shape around an axis of rotation parallel to the seating surface 21 and passing through the center of the cutting insert 100.

Thus, since the cutting insert 100 of the present embodiment has a rotationally symmetric shape, in the following description, the shape on the upper surface 20 side will be mainly described, and the description on the lower surface 30 side which is a similar shape will be described. Omitted.

The cutting edges are a long cutting edge 53 and a short cutting edge 54 extending on both sides across one obtuse corner portion 51 formed on the upper surface 20, and the other crossing ridge line portion between the upper surface 20 and the side surface 40 is cut. Does not act as a blade. When the cutting insert 100 is attached to the tool body 200 as shown in FIGS. 12 (a) and 13 (a), FIGS. 12 (a) and 13 (b), which are enlarged views of broken lines in the respective drawings. As shown in FIG. 14, the long cutting edge 53 acts as an outer peripheral edge, and the short cutting edge 54 acts as a central edge.

In this embodiment, the recess 60 is formed on the side surface to which the short cutting edge 54 is connected (that is, in this embodiment, the short cutting edge 54 is the first cutting edge). A recess 80 is formed on the upper surface 20, and the recess 80 is formed in a position and shape that includes the first inner wall surface 61 of the recess 60 inside when viewed from the direction facing the upper surface 20. That is, the depression 80 is formed at a position where the ridge line of the depression 60 passes through the inside of the depression 80. As shown in FIG. 11, by forming the recess 80 on the upper surface 20, the angle ε formed by the above-described cutting edge 53 a 1 and the ridge line 61 a becomes larger than the case where there is no recess 80. By increasing the angle ε, a sufficient gap can be secured between the work material and the cutting insert 100 when the cutting insert 100 is attached to the tool body, and the cutting edge 53a1 and the first inner wall surface 61 intersect. The fracture resistance of the part is improved.

As shown in FIG. 11, when viewed from the direction facing the second inner wall surface 62, the intersecting ridge line portion 62a between the second inner wall surface 62 and the upper surface 20 is formed in a curved shape that is convex toward the upper surface side. Yes. When the cutting insert 100 is attached to the tool body, the intersecting ridge line portion 62a also acts as a center blade. By forming the intersecting ridge line portion 62a in such a curved manner, as shown in FIG. 14, when the cutting insert 100 is attached to the tool main body, the end-expanding space (encircled by a dotted line) is attached to the tip of the tool. ) To improve chip discharge. By improving the chip discharge performance, clogging of the chip at the tip of the tool is suppressed.

Also in the second embodiment, the angle β, the angle γ (shown in FIG. 10), and the angle ε (shown in FIG. 11) are set in the same manner as the preferred form in the first embodiment. preferable.

(Other)
The present invention is not limited only to the above-described embodiment, and the form can be changed as appropriate without departing from the technical idea thereof. That is, the cutting insert can take various shapes, and in accordance with the shape, a concave portion capable of obtaining the effects of the present invention can be formed on an appropriate ridge line or cutting edge. That is, even when the cutting insert 10 having a shape that is twice symmetrical with respect to the axis of the screw hole 70 that penetrates the upper surface and the lower surface that are the end surfaces in the first embodiment, and the front and back sides in the second embodiment are reversed. The cutting insert 100 in which the same shape appears (the rotational axis passing through the opposite part of the side surface is symmetric twice with respect to R) is illustrated as an example, and it has been described that a recess can be provided at each rotationally symmetric position. However, instead of or together with these rotation axes as illustrated, each of the two ridge lines sandwiching the corner portion (bending portion) has a shape that is n times rotationally symmetric with respect to the other rotation axes. If the cutting insert includes a portion that acts as a cutting edge, the concave portion can be provided at an appropriate position in accordance with the cutting insert. Furthermore, it is possible to form a plurality of recesses on one cutting edge. When the size of the cutting insert is large, the formation of a plurality of recesses is the ability to subdivide and discharge chips. This is preferable because of increased properties.

As described above, the shape of the connecting surface of the recess may be a plane, a combination of a plurality of curved surfaces, a combination of a plurality of planes, or a combination of a curved surface and a plane. Since the gist of the present invention is that the ridge line of the second inner wall surface is significantly longer than the ridge line of the first inner wall surface when viewed from the direction facing the upper surface and the angle β described above is small, the shape of the connecting surface A certain effect is exhibited no matter what. However, it is not preferable that the connecting surface is extremely large among the inner wall surfaces constituting the recess, the area of the second inner wall surface is larger than any other inner wall surface, and the connecting surface is formed with a minimum size. Most preferably. When the connecting surface is smoothly connected to the first inner wall surface and the second inner wall surface, it becomes difficult to determine the boundary between the connecting surface and each inner wall surface, and the end position of the ridge line of each inner wall surface is difficult to understand. In this case, the center of the connecting surface may be handled as the end portion of each inner wall surface.

Furthermore, in both of the above-described embodiments, the example in which the cutting edge structure of the present invention is embodied in a cutting insert has been described. However, the present invention can also be applied to a cutting tool having the tip structure integrally, such as a solid drill. Of course.

Claims

A polygonal end face (20) and a side face (40) connected to the end face (20), and at least of the intersecting ridge line part (50) between the end face (20) and the side face (40), A cutting tool in which the first and second ridgelines sandwiching the bent portion (51) formed by one vertex of the polygon include portions that act as first and second cutting edges (53, 54), respectively. The cutting edge structure of
A first portion (53a1) formed on at least a first flank (41) connected to the first cutting edge (53), and the first cutting edge (53) close to the bent portion (51); A recess (60) that divides into a second part (53a2) far from the bent part (51);
The recess (60) includes a first inner wall surface (61) including a ridge line (61a) connected to the first part (53a1) and a ridge line (62a) connected to the second part (53a2). A second inner wall surface (62),
When viewed from the direction facing the end surface (20), the ridge line (62a) included in the second inner wall surface (62) is longer than the ridge line (61a) included in the first inner wall surface (61). The cutting edge structure of a cutting tool.
When viewed from the direction facing the end surface (20), the ridge line (62a) included in the second inner wall surface has a length three times or more than the ridge line (61a) included in the first inner wall surface. The cutting edge structure of a cutting tool according to claim 1, wherein:
When viewed from the direction facing the first flank (41), the ridge line (61b) where the first inner wall surface (61) and the side surface (40) intersect is the end on the end surface (20) side. 3. The cutting edge structure of a cutting tool according to claim 1, wherein the blade edge structure is inclined so as to be closer to the bent portion as the distance from (61 b 1) increases.
When the honing applied to the cutting edge (53) in which the recess (60) is formed is viewed from the direction facing the end surface (20), the width of the honing is H, and the end surface (20) The length of the straight line connecting the connection portions (Q1, Q2) between the recess (60) and each of the first and second portions (53a1, 53a2) when viewed from the opposite direction is L. Sometimes, the angle β formed by the ridgeline (62a) included in the second inner wall surface (62) and the straight line is expressed by the following formula tanβ> H / L
The cutting edge structure of a cutting tool according to any one of claims 1 to 3, wherein:
When the first inner wall surface (61) is viewed from the first flank (41) side and parallel to the first inner wall surface (61), the first inner wall surface (61) is the side surface. The cutting tool according to claim 3 or 4, wherein an angle ε formed by the ridge line (61b) intersecting (40) and the first portion (53a1) is 50 ° or more and 120 ° or less. Cutting edge structure.
When viewed from the direction facing the end surface, the connection portion (Q1) between the second inner wall surface (62) and the first portion (53a1), the second inner wall surface and the second portion (53a2). The angle γ formed by the ridge line (61a) included in the first inner wall surface (61) with respect to the imaginary line (P) defined by connecting the connection portion (Q2) to the first connection surface (Q2) is approximately 80 ° or more and 110 The cutting edge structure of a cutting tool according to any one of claims 1 to 5, wherein the cutting edge structure is at most °.
A recess (80) is formed on the end surface (20), and the recess (80) includes the first inner wall surface (61) on the inner side when viewed from a direction facing the end surface. The cutting edge structure of a cutting tool according to any one of claims 1 to 6, wherein the cutting edge structure is formed at a position.
The length of the first portion (53a1) is shorter than the length of the ridge line (61a) included in the one inner wall surface when viewed from a direction facing the end surface. The cutting edge structure of the cutting tool according to any one of the above.
The recess (60) includes a connecting surface (63) connected to the first inner wall surface (61) and the second inner wall surface (62), and the area of the second inner wall surface is the first inner wall surface and the second inner wall surface (62). The cutting edge structure of a cutting tool according to any one of claims 1 to 8, wherein the cutting edge structure is larger than the connecting surface.
A cutting insert comprising the cutting edge structure according to any one of claims 1 to 9.
The second end face (30) facing the end face (20) is provided, and has a two-fold symmetrical shape with respect to at least one axis passing through the cutting insert (10, 100), and the recess (60) is in the symmetry. The cutting insert according to claim 10, wherein the cutting insert is formed at a position where
12. The cutting insert according to claim 11, wherein the shaft includes at least one of a shaft penetrating the end surface and the second end surface and a shaft penetrating opposite portions of the side surface.
A cutting tool comprising the cutting edge structure according to any one of claims 1 to 9.