WO2016039347A1

WO2016039347A1 - Cutting insert and interchangeable cutting edge-type rotary cutting tool

Info

Publication number: WO2016039347A1
Application number: PCT/JP2015/075494
Authority: WO
Inventors: 哲司小宮山
Original assignee: 株式会社タンガロイ
Priority date: 2014-09-09
Filing date: 2015-09-08
Publication date: 2016-03-17
Also published as: JP6292425B2; JPWO2016039347A1

Abstract

The present invention relates to a cutting insert (1): provided with a roughly polygonal first end face (2), a second end face (3) that is opposite said first end face, a surrounding side surface (4) that connects said end faces, and at least one cutting edge (8) formed on the intersection ridge between the first end face and the surrounding side surface; and having a central axis line determined so as to pass through said end faces. The cutting edge has a cutting edge portion (9) extending between a first corner and a second corner that are adjacent to each other on the first end face. Said portion (9) is provided with a first corner-side first cutting edge section (9a) and a second corner-side second cutting edge section (9b) that are connected to each other. When a surface that passes between the first end face and the second end face and intersects at right angles with the central axis line is defined as a middle plane (M), the first cutting edge section (9a) has a sub-section (9ap) that is formed so as to approach the middle plane as distance from the first corner increases when moving toward the second corner.

Description

Cutting insert and cutting edge exchangeable rotary cutting tool

The present invention relates to a cutting insert and a cutting edge exchange type rotary cutting tool. More specifically, the present invention relates to a high-feed cutting insert and a blade-tip-exchange-type rotary cutting tool that is detachably mounted thereon.

Conventionally, as a tool used for cutting a metal or the like, a cutting edge exchange type rotary cutting tool in which a plurality of cutting inserts are attached to the tip of a substantially disk-like or substantially cylindrical tool body rotated around an axis is used. ing. In such a blade-tip-exchange-type rotary cutting tool, there is a demand for use in high-feed machining. High feed processing refers to processing that feeds a tool at a high feed rate, and can realize high-efficiency machining.

Patent Document 1 discloses an example of such a cutting insert for high feed processing. The cutting insert of patent document 1 has a substantially quadrilateral shape in a top view and is a positive type, and a cutting edge is formed at an intersecting ridge line portion between the upper surface and the peripheral side surface. The cutting edge has a main cutting edge that forms a bottom edge that is continuous with one end of the corner cutting edge, and an outer peripheral edge that is continuous with the other end of the corner cutting edge. Each of the main cutting edge and the outer peripheral edge has a curved shape protruding outward in a top view of the cutting insert. From the main cutting edge to the outer peripheral edge, the cutting edge has a linear shape parallel to the lower surface in a side view of the cutting insert. In such a cutting insert, the corner cutting edge is positioned on the outermost peripheral side at the tip end of the tool body of the rotary cutting tool, and the end region away from the corner cutting edge of the main cutting edge is positioned on the tool tip side. And is detachably mounted.

JP 2005-169511 A

However, the cutting insert for high-feed machining as described in Patent Document 1 has the following problems. In the high-feed machining, only the main cutting edge of the cutting insert is mainly used as the cutting edge, and chips generated thereby are easily discharged in the tool outer peripheral direction. In particular, since the cutting insert of Patent Document 1 has a linear shape in which the main cutting edge is parallel to the lower surface in a side view, when the cutting insert is mounted so that the radial rake is 0 ° or less with respect to the tool body, The radial rake of the main cutting edge is also 0 ° or less in the tip view of the tool body. Therefore, chips generated by the main cutting edge are more easily discharged in the tool outer peripheral direction by the cutting force (reaction force) received from the cutting insert. When chip discharge is concentrated in the outer periphery of the tool, the probability that the discharged chip is caught between the side surface of the cutting insert and the workpiece or collides with the workpiece surface of the workpiece increases. . This can cause problems such as a reduction in tool life of the cutting insert and a deterioration in surface accuracy such as scratches on the processed surface of the workpiece. In particular, in a digging process such as a pocket process, this problem becomes even greater because the space for chip removal is small.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a cutting insert and a cutting edge-exchangeable cutting tool that can more suitably promote chip discharge.

According to a first aspect of the present invention, there is provided a first end surface having a substantially polygonal shape, a second end surface facing the first end surface, a peripheral side surface connecting the first end surface and the second end surface, The present invention relates to a cutting insert that includes at least one cutting edge formed at an intersecting ridge line portion between an end surface and the peripheral side surface, and has a central axis that is defined so as to penetrate the first end surface and the second end surface. This cutting insert is preferably a cutting insert for high feed processing. The cutting edge has a cutting edge portion extending between the first corner and the second corner adjacent to each other on the first end face. The cutting edge portion includes a first cutting edge portion on the first corner side and a second cutting edge portion that is a second cutting edge portion on the second corner side and is connected to the first cutting edge portion. . And when the surface which penetrates between the 1st end surface and the 2nd end surface and intersects at right angles to the central axis is defined as an intermediate surface, the 1st cutting edge part is in the 2nd corner. And a portion that is shaped to approach the intermediate surface as it moves away from the first corner.

In this cutting insert, the first cutting edge portion on the first corner side with respect to the second cutting edge portion is shaped so as to approach the intermediate surface as it is separated from the first corner toward the second corner. Has a part. Therefore, when the cutting insert is attached to the insert mounting seat of the tool body, for example, with a 0 ° radial rake so that the first corner portion is located on the outermost peripheral side of the rotary cutting tool, the cutting edge portion of the working cutting edge The radial rake is changed to the plus side (positive) on the outer periphery side of the tool, and the chip discharge direction by the first cutting edge portion can be directed to the inner periphery side of the tool. Thereby, damage to the cutting insert caused by chips and deterioration of the surface accuracy of the processed surface of the workpiece can be suppressed.

Preferably, the cutting edge includes a corner cutting edge extending along the first corner that smoothly connects to the first cutting edge portion. More preferably, the corner cutting edge may have a portion shaped so as to be closer to the intermediate surface as it approaches the first cutting edge portion.

Preferably, in a side view of the cutting insert, the first cutting edge portion has a concave curved shape that is recessed in a direction close to the intermediate surface.

Preferably, in the side view of the cutting insert, the second cutting edge portion has a portion having the longest distance from the intermediate surface among the cutting edges. More preferably, in the side view of the cutting insert, the second cutting edge portion has a convex curved shape protruding in a direction away from the intermediate surface.

Preferably, when the cutting insert is viewed from the side facing the first end surface, the second cutting edge is curved outwardly of the cutting insert. Preferably, when the cutting insert is viewed from the side facing the first end surface, the first cutting edge portion is connected to the second cutting edge portion smoothly and linearly with the second cutting edge portion. It extends between the first corner.

Preferably, when the cutting insert is viewed from the side facing the first end surface, the second cutting edge portion forms an inner angle of 165 ° or more and less than 180 ° with the first cutting edge portion.

Preferably, the first end face has n (where n is an integer of 3 or more) corners, and the cutting insert substantially has a shape rotationally symmetrical n times around the central axis.

According to a second aspect of the present invention, there is provided a tool body having a rotation axis and having at least one insert mounting seat formed thereon, and a cutting insert is detachably mounted on the insert mounting seat. About. The cutting insert that is detachably attached to the insert mounting seat may be the aforementioned cutting insert. It is preferable that at least the first cutting edge portion of the cutting insert has a cutting edge portion with a positive radial rake as viewed from the front end surface of the blade-tip-exchange-type rotary cutting tool (13). The cutting insert itself can be mounted on the tool body with a radial rake of 0 ° or less.

With respect to the working cutting edge, the second cutting edge portion of the cutting edge portion is positioned closest to the tool tip side, and the first corner adjacent to the first cutting edge portion is positioned closest to the tool outer peripheral side. The cutting insert may be attached to the insert mounting seat. In this case, the cutting angle at the second cutting edge may be smaller than the cutting angle at the first cutting edge.

FIG. 1 shows a perspective view of a cutting insert according to an embodiment of the present invention. FIG. 2 shows a top view of the cutting insert of FIG. FIG. 3 shows a side view of the cutting insert of FIG. 4 shows a bottom view of the cutting insert of FIG. FIG. 5A is a top view of the cutting insert of FIG. 1 corresponding to FIG. 2, and is a view for explaining the cut portion and the shape of the cutting edge of FIG. 5B. FIG. 5B shows a cross-sectional view of the cutting insert of FIG. 1 along the line VB-VB of FIG. 5A. FIG. 6: shows the side view of the blade-exchange-type rotary cutting tool which concerns on one Embodiment of this invention. FIG. 7 shows a front end view of the blade edge-exchange-type rotary cutting tool of FIG. FIG. 8 shows a side view of a tool body used in the cutting edge exchange type rotary cutting tool of FIG. FIG. 9 shows a front end view of the tool body of FIG. 10A is a view of the cutting insert of FIG. 1 mounted on the tool body of FIG. 8 as viewed from a direction substantially opposite to the first end surface, and is a partial cross-sectional view taken along line XA-XA of FIG. It is. FIG. 10B is an enlarged view of the vicinity of the cutting insert shown in FIG. 10A. FIG. 11 is a diagram for explaining one working form of the cutting edge exchange type rotary cutting tool of FIG. 6, and shows a state where the workpiece is machined by the working cutting edge of the cutting insert shown in FIG. 10A. The enlarged schematic diagram of the cutting insert vicinity is shown. FIG. 12 is a view for explaining a machining form of the cutting edge exchange type rotary cutting tool of FIG. 6 different from the form of FIG. 11, and the workpiece is cut by the working cutting edge of the cutting insert shown in FIG. 10A. The enlarged schematic diagram of the cutting insert vicinity showing the place currently processed is shown. FIG. 13 shows a partially enlarged view of one cutting insert in the cutting edge exchangeable cutting tool of FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

The cutting insert 1 of the present embodiment has a substantially rectangular plate shape as shown in FIGS. The cutting insert 1 includes a first end surface 2 having a substantially square shape, a second end surface 3 disposed so as to face the first end surface 2, and a peripheral side surface 4 connecting the first end surface 2 and the second end surface 3. And basically consists of. The second end surface 3 is smaller than the first end surface 2, but has a substantially rectangular shape like the first end surface 2. Overall, the first end surface 2 and the peripheral side surface 4 are connected so that the inner angle between them is an acute angle, and the second end surface 3 and the peripheral side surface 4 are such that the inner angle between them is an obtuse angle. Connected. Therefore, the cutting insert 1 of this embodiment is what is called a positive type. Therefore, the 1st end surface 2 may be called an upper surface, and the 2nd end surface 3 may be called a lower surface. However, the present invention is not limited to this, and may be a negative type in which the first end surface 2 and the second end surface 3 intersect the peripheral side surface 4 at substantially right angles. Further, the cutting insert 1 is provided with a mounting hole 5 in which a central axis O is defined so as to pass through a substantially central portion of the first end surface 2 and a substantially central portion of the second end surface 3. Basically, the cutting insert 1 is configured to be 90 ° rotationally symmetric (4-fold rotational symmetry) around the central axis O.

The first end surface 2 is viewed from the direction facing the first end surface 2 (that is, in FIG. 2), four curved corner portions 6, and four side portions 7 formed between the corner portions 6, It has a substantially square shape composed of All the side portions 7 have the same length. Moreover, all the corner parts 6 have the same shape, and all the side parts 7 also have the same shape. Therefore, the cutting insert 1 of the present embodiment has a substantially quadrangular shape that is 90 ° rotationally symmetric with respect to the central axis O in FIG. 2, but the present invention is not limited to this, and a triangular shape or Other shapes such as a pentagonal shape may be used. That is, in the cutting insert according to the present invention, the first end face 2 has n (where n is an integer of 3 or more) corners, and substantially has a shape that is n times symmetrical around the central axis O. Further, the shapes, lengths, and numbers of the corner portions 6 and the side portions 7 are not limited to the present embodiment, and can be appropriately changed without departing from the gist of the present invention. Since the first end surface 2 has four corner portions 6 and four side portions 7, the peripheral side surface 4 has four main side surfaces 4a and four corner side surfaces 4b extending between the main side surfaces. The main side surface 4a related to the corresponding side portion 7 and the corner side surface 4b related to the corresponding corner portion 6 are alternately continuous in the circumferential direction. Both the main side surface 4 a and the corner side surface 4 b extend from the first end surface 2 to the second end surface 3.

A plurality (four in this case) of cutting edges 8 are formed at the intersecting ridge line portion between the first end surface 2 and the peripheral side surface 4. Each cutting edge 8 includes a main cutting edge (cutting edge portion) 9. In the cutting insert 1, the cutting edge 8 has the corner cutting edge 10 in addition to the main cutting edge 9, but the corner cutting edge 10 may not be provided. The main cutting edge 9 is formed at an intersecting ridge line portion between the first end surface 2 and the main side surface 4 a of the peripheral side surface 4 corresponding to the side portion 7. The main cutting edge 9 extends between two corners 6 adjacent to each other. In particular, in the cutting insert 1, the main cutting edge 9 extends over the entire area between the two corners 6. The corner cutting edge 10 is formed at an intersecting ridge line portion between the first end surface 2 and the corner side surface 4 b corresponding to the corner portion 6.

Here, since the four cutting edges 8 are formed to have a 90 ° rotationally symmetric shape around the central axis O of the mounting hole 5, one of the four cutting edges 8 will be described below. 2 will be described with particular attention to the cutting edge 8a having the main cutting edge 9 extending along the side portion 7 located on the lower side in FIG. Therefore, the following description about the cutting edge 8a is similarly applied to other cutting edges. The cutting insert 1 can be indexed, and identification marks 2a to 2d are attached to the first end surface 2 in order to discriminate the used cutting edge or the unused cutting edge.

With respect to the cutting edge 8a, the corner 6 on the right side of the main cutting edge 9 in FIG. 2 is defined as a first corner 6a, and the corner 6 on the left side of the main cutting edge 9 in FIG. 2 is defined as a second corner 6b. The corner cutting edge 10 in the cutting edge 8a extends to the first corner 6a. The main cutting edge 9 has a first cutting edge portion 9a on the first corner 6a side and a second cutting edge portion 9b on the second corner 6b side. The first cutting edge portion 9a is directly and smoothly connected to the second cutting edge portion 9b. However, the first cutting edge portion 9a is not limited to being directly connected to the second cutting edge portion 9b, and they may be connected indirectly, that is, via a further connection cutting portion. The first cutting edge portion 9a is directly connected to the first corner 6a, and the second cutting edge portion 9b is directly connected to the second corner 6b.

The first cutting edge portion 9a is longer than the second cutting edge portion 9b. The first cutting edge portion 9a preferably has a length that is at least twice the length of the second cutting edge portion 9b, more preferably a length that is at least three times longer. In the cutting insert 1 of the present embodiment, The first cutting edge portion 9a has a length of about 3.5 times the length of the second cutting edge portion 9b. This is because the second cutting edge portion is a part of the main cutting edge but is a portion that provides a wiping edge action as can be understood from the processing modes of FIGS. 11 and 12 described later.

The first cutting edge portion 9a is linear when the cutting insert 1 is viewed from the side facing the first end face 2, that is, in FIG. In FIG. 2, the second cutting edge portion 9 b has a curved shape, and particularly has a shape that gently protrudes toward the outside of the cutting insert 1.

Here, the main cutting edge 9 of the cutting edge 8a will be further described with reference to FIG. 5A corresponding to FIG. A straight line La extending along the first cutting edge portion 9a of the main cutting edge 9 of the cutting edge 8a and a straight line Lb extending through both ends of the second cutting edge portion 9b are shown in FIG. 5A. However, one end 9b ′ of the second cutting edge portion 9b of the cutting edge 8a is located at a boundary portion with the first cutting edge portion 9a (of the cutting edge 8a) which is linear in FIG. 5A, and the second cutting edge portion. The other end 9 b ″ of FIG. 5A is located at the boundary with the corner cutting edge 10 (of the adjacent cutting edge 8) having a substantially single curvature in FIG. 5A. As can be understood from the relationship between the straight line La and the straight line Lb, in FIG. 5A, the second cutting edge portion 9b forms an inner angle θ1 slightly smaller than 180 ° with the first cutting edge portion 9a as a whole. Specifically, the inner angle is about 170 °. In the present invention, θ1 may be an obtuse angle, preferably in the range of 160 ° to less than 180 °, more preferably in the range of 165 ° to less than 180 °, and even more preferably in the range of 165 ° to 175 °. It should be set. In FIG. 5A, the second cutting edge portion 9b extends so as not to protrude outward from the straight line La.

Further, FIG. 5A shows a tangent line Lc of the cutting edge 8a in the vicinity of the other end 9b ″ of the second cutting edge portion 9b of the cutting edge 8a. The line Lc forms an internal angle θ2 with the line La. The inner angle θ2 is smaller than the inner angle θ1, and here is about 164 °. That is, in FIG. 5A, the main cutting edge 9 of the cutting edge 8a is connected to the corner cutting edge 10 of the adjacent cutting edge so as to have an internal angle of about 164 °.

Here, reference is made to FIG. 3 which is a side view of the cutting insert 1 viewed from the side facing the main side surface 4a formed on the main cutting edge 9 of the cutting edge 8a. In FIG. 3, both the first cutting edge portion 9a and the second cutting edge portion 9b of the main cutting edge 9 have a curved shape. As shown in FIG. 3, a surface that penetrates the peripheral side surface 4 and intersects the central axis O at a right angle is defined between the first end surface 2 and the second end surface 3, and the surface is defined as the intermediate surface M. It is defined as In FIG. 3 from the main side surface 4a side of the peripheral side surface 4 of the cutting insert 1, the intersection ridge line portion between the first end surface 2 and the peripheral side surface 4 is a distance from the intermediate surface M as it moves along the intersection ridge line portion. Is curved to change. Specifically, the first cutting edge portion 9a is curved so as to protrude inwardly (indent) in a direction from the first end surface 2 side toward the second end surface 3 side. The second cutting edge portion 9b is curved so as to protrude outward in a direction from the second end surface 3 side toward the first end surface 2 side. The corner cutting edge 10 extending along the first corner 6a out of the cutting edges 8a located on the lower side in FIG. 2 is the first cutting edge portion 9a of the cutting edge 8a and the first cutting edge 8 of the adjacent cutting edge 8. It extends between the two cutting edges 9b, and here they are directly connected. The corner cutting edge 10 of the cutting edge 8a is shaped to be inclined from the second cutting edge 9b side of the adjacent cutting edge 8 toward the first cutting edge 9a of the same cutting edge 8a in a side view. ing. In particular, in the single cutting edge 8 a, the corner cutting edge 10 is inclined in FIG. 3 so as to approach the intermediate surface M as it approaches the main cutting edge 9. And the corner cutting edge 10 is extended so that the 2nd cutting edge part 9b of the adjacent cutting edge 8 and the 1st cutting edge part 9a in the same cutting edge 8a may be connected smoothly. Accordingly, in FIG. 3, the cutting edge 8a is curved in a substantially S shape, more precisely, a substantially inverted S shape, with respect to the entire region from the main cutting edge 9 to the corner cutting edge 10. Therefore, in the insert thickness direction (which is a direction parallel to the central axis O), a portion (most projecting portion) 9c farthest from the intermediate surface M in the cutting edge 8a is in the second cutting edge portion 9b. A portion 9d closest to the intermediate surface M in 8a (the closest portion) 9d is in the first cutting edge portion 9a. As is clear from FIG. 3, the closest portion 9d divides the first cutting edge portion 9a of the main cutting edge 9 into a region on the first corner portion 6a side and a region on the second corner portion 6b side. It is located in the region on the first corner portion 6a side.

In FIG. 3, the height difference H between the most protruding portion 9c and the closest portion 9d, that is, the distance difference between them from the intermediate surface M in the direction of the central axis O is about 0.5 mm. In the cutting insert 1 of the present embodiment, an inscribed circle (not shown) defined on the first end surface 2 in FIG. 2 has a diameter of about 16 mm, and the maximum thickness of the cutting insert is about 7 mm. Designed as such. The height difference H is preferably 0.2 mm or more, and more preferably 0.4 mm or more. The height difference H is preferably 1.5 mm or less, and more preferably 0.8 mm or less. However, the height difference H may be determined according to the overall dimensions of the cutting insert, and particularly preferably according to the total length of the main cutting edge.

Thus, in the side view of the cutting insert 1, the first cutting edge portion 9 a and the corner cutting edge 10 of the main cutting edge 9 protrude as a whole from the first end face 2 side to the second end face 3 side. It has a curved shape (substantially concave arc shape in FIG. 3). On the other hand, the second cutting edge portion 9b of the main cutting edge 9 is curved so as to protrude in the direction from the second end face 3 side toward the first end face 2 side in the side view of the cutting insert 1 (in FIG. 3). (Substantially convex arc shape). Accordingly, the first cutting edge portion 9a constitutes a concave curved cutting edge portion, and is inclined away from the intermediate surface M from the closest portion 9d toward the corner cutting edge 10. That is, the first cutting edge portion 9a is shaped so as to be closer to the intermediate surface M as it is separated from the first corner 6a side toward the second corner 6b on the first corner portion 6a side from the closest portion 9d. Part 9ap. Further, the first cutting edge portion 9a is shaped so as to be separated from the intermediate surface M as it is separated from the first corner 6a side toward the second corner 6b on the second corner portion 6a side from the closest portion 9d. Part 9aq. On the other hand, the second cutting edge portion 9b constitutes a convex curved cutting edge portion protruding outward of the cutting insert 1 in both FIG. 2 (plan view or top view) and FIG. 3 (side view). To do. Therefore, the cutting edge 8 is substantially reverse S-shaped in the region of the main cutting edge 9 from the second cutting edge portion 9b to the first cutting edge portion 9a, and is further substantially reduced up to the range including the corner cutting edge 10. Inverted S-shape.

Each cutting edge 8 extends to the intersection of the rake face equivalent portion (that is, rake face) 11a of the first end face 2 and the flank face equivalent portion (ie, flank face) 11b of the peripheral side surface 4. That is, a part of the first end face 2 functions as a rake face with respect to the corresponding cutting edge 8. A part of the peripheral side surface 4 (for example, one main side surface 4 a and one corner side surface 4 b) functions as a flank with respect to the corresponding cutting edge 8. The second end surface 3 is configured to function as a seating surface that comes into contact with the bottom wall surface 17 of the insert mounting seat 16 provided on the tool body 14. In the cutting insert 1, the second end surface 3 extends so as to be orthogonal to the central axis O and is flat. However, the second end surface 3 may have other shapes, for example, irregularities.

In the cutting insert 1 of this embodiment, the cutting edge 8 (including the cutting edge 8a) is formed only at the intersecting ridge line portion between the first end face 2 and the peripheral side face 4. However, it is also possible to form a cutting edge at the intersection ridge line portion between the second end surface 3 and the peripheral side surface 4 so that the cutting insert according to another embodiment of the present invention is used on both sides. . In this case, the first end surface 2 also functions as a seating surface, and the second end surface 3 also functions as a rake surface. That is, when the first end surface 2 functions as a rake surface, the second end surface 3 functions as a seating surface, and when the second end surface 3 functions as a rake surface, the first end surface 2 functions as a seating surface. Further, in the cutting insert 1 of the present embodiment and the cutting insert according to another embodiment of the present invention, the peripheral side surface 4 also functions as a flank, and the side of the insert mounting seat 16 provided on the tool body 14. It also functions as a constraining surface that contacts the wall surface 18.

Since each cutting edge 8 includes the first cutting edge portion 9a, the second cutting edge portion 9b, and the corner cutting edge 10 as described above, the rake face 11a associated therewith is the first rake face part r1, the second rake face part r2, A corner rake face portion r3. Two of each of these rake faces connect smoothly to each other. The rake face 11a is inclined so as to approach the intermediate face M as it moves away from the cutting edge toward the inside of the first end face 2. This contributes to setting a positive rake angle.

As particularly understood from the cross-sectional view of the cutting insert 1 in FIG. 5B along the line VB-VB in FIG. 5A, the peripheral side surface 4 is a side surface portion (cut) on the first end surface 2 side in the thickness direction of the cutting insert. A blade side portion) 4c and a side surface portion (sitting surface side portion) 4d on the second end face 3 side. The cutting edge side portion 4c corresponds to the flank 11b, and has substantially the same inclination and substantially the same width throughout. The cutting edge side portion 4c has a positive clearance angle. On the other hand, the seating surface side portion 4d has a clearance angle of approximately 0 °, and a constraining surface 12 substantially parallel to the central axis O is formed. That is, when the cutting edge side portion 4c defines a first virtual surface (not shown) parallel to the central axis O so as to pass through the cutting edge 8, the cutting edge side portion 4c increases from the first end face 2 side to the second end face 3 side. 1 Inclining and extending away from the imaginary plane. The seating surface side portion 4d extends along the second imaginary surface when a second imaginary surface (not shown) parallel to the central axis O is defined. The restraining surface 12 has a function of contacting the side wall surface 18 of the insert seat 16. The restraining portion 12 is formed over substantially the entire region of the second end surface side 3 of the main side surface 4a of the peripheral side surface 4 in the width direction (circumferential direction) of the cutting insert 1, and the central axis of the cutting insert 1 as described above. It extends so as to have a substantially parallel relationship with O. That is, the restraining portion 12 is formed as a surface having a positional relationship that intersects the second end surface 3 at a substantially right angle. In the present embodiment, the peripheral side surface 4 is configured as described above. However, the configuration is not limited to this, and the shape can be appropriately changed according to required performance and the like.

The cutting insert 1 can be made from a hard material such as cemented carbide, cermet, ceramic, or an ultra-high pressure sintered body containing diamond or cubic boron nitride, or a coating of the hard material.

Next, the blade-tip-exchange-type rotary cutting tool 13 in which the cutting insert 1 of the above embodiment is detachably mounted will be described with reference to FIGS. 6 to 10B.

The cutting edge exchange type rotary cutting tool 13 of this embodiment includes a tool body 14. In the tool body 14, a rotation axis RA extending from the front end side to the rear end side is defined. The blade-tip-exchange-type rotary cutting tool 13 is configured to be rotatable around the rotation axis RA and forward in the rotational direction K. Note that the blade-tip-exchange-type rotary cutting tool 13 may be used by being rotated relative to the workpiece around the rotation axis, and the cutting tool itself does not necessarily need to rotate.

The tool body 14 has a mounting hole 15 extending along the rotation axis RA, and has a hollow cylindrical overall shape. A plurality of insert mounting seats 16 are formed at the distal end located at the distal end of the tool body 14. In the present embodiment, four insert mounting seats 16 are formed, but the number of insert mounting seats 16 may be one or plural. Each insert mounting seat 16 is formed so as to open forward in the rotational direction K around the rotation axis RA and open to the front end side and the outer peripheral side. The four insert mounting seats 16 are arranged at substantially equal intervals in the circumferential direction around the rotation axis RA, but may be arranged at unequal intervals.

The insert mounting seat 16 includes a bottom wall surface 17 capable of contacting the second end surface 3 of the cutting insert 1 and side wall surfaces 18 (18a, 18b) capable of contacting the peripheral side surface 4 of the cutting insert 1. The bottom wall surface 17 of the insert mounting seat 16 basically has the same shape as the second end surface 3 of the cutting insert 1 and has a size corresponding to the second end surface 3. The bottom wall surface 17 faces forward in the rotation direction K. A screw hole 20 for inserting and screwing a fixing screw 19 for fixing the cutting insert 1 is formed in the approximate center of the bottom wall surface 17. The side wall surfaces 18a, 18b of the insert mounting seat 16 are determined so as to be able to contact the restraining portion 12 of the peripheral side surface 4 of the cutting insert 1, and are formed so as to intersect the bottom wall surface 17 at a certain angle. Yes. The first side wall surface 18a mainly faces the outer peripheral side of the tool body, and the second side wall surface 18b mainly faces the tip side of the tool body. In order to correspond to the shape of the cutting insert 1, the first side wall surface 18 a extends so as to form approximately 90 ° with the second side wall surface 18 b, but these intersecting angles can be changed according to the shape of the cutting insert. .

Furthermore, a chip pocket 21 for discharging chips generated by cutting is provided on the front side of each insert mounting seat 16 in the tool rotation direction K.

The cutting insert 1 is attached to the insert mounting seat 16 when the fixing screw 19 is screwed into the screw hole 20 through the mounting hole 5. In addition, the cutting insert 1 is attached to the insert mounting seat 16 at the lower right in FIG. 6 so that the cutting edge 8 different from the cutting edge 8a is a working cutting edge.

Reference is now made to FIG. 10A. In FIG. 10A, a straight line RB parallel to the rotation axis RA of the tool is parallel to the paper surface, and is a partially enlarged view of the cutting tool 13 as viewed from the side substantially facing the first end surface 2 of the attached cutting insert 1 Some are in cross-section). At this time, as shown in FIG. 10A, the second cutting edge portion 9b of the main cutting edge 9 of the working cutting edge 8u involved in cutting is the most tool tip side in the direction along the rotation axis RA (straight line RB). Located in. In particular, the region including the most protruding portion 9c is located closest to the tool tip side. Further, the corner cutting edge 10 of the working cutting edge 8u involved in the cutting is located on the tool outer peripheral side with respect to the main cutting edge 9, and the working cutting edge 8u is located on the most outer peripheral side of the tool.

However, the cutting insert 1 itself is mounted on the tool body 14 so that the axial rake is 5 ° and the radial rake is 0 °. However, the present invention is not limited to this, and the values of the axial rake and the radial rake can be appropriately changed as necessary. The mounting angle of the cutting insert 1 itself is the angle at which the insert mounting seat 16 is arranged.

Here, in FIG. 10A, which is a side view of the tool body 14, it passes through a portion of the second cutting edge portion 9 b that is perpendicular to the most cutting end side of the second cutting edge portion 9 b at a right angle to the direction along the straight line RB parallel to the rotation axis RA. The straight line drawn in this way is defined as the tangent (or tangential plane) Ld of the main working cutting edge 9u. The tangent Ld is the boundary between the second cutting edge portion 9b of the main cutting edge 9 of the working cutting edge 8u and the corner cutting edge 10 of the non-working cutting edge 8 adjacent to the second cutting edge portion 9b. (Equivalent to the boundary portion 9b ″) Nearly touches the vicinity. Moreover, in FIG. 10A, the line which extended substantially the linear 1st cutting-blade part 9a when it sees from the 1st end surface 2 side is defined as the extension line N1. In the cutting tool of the present embodiment, when the cutting insert 1 is viewed from the direction facing the first end face 2 and substantially perpendicular to the rotation axis RA, the first cutting edge portion 9a has the tangent line Ld and the extension line N1. Are arranged so that the internal angle α formed by That is, when the cutting insert 1 is mounted at the mounting angle, the inner angle θ2 in the vicinity of the boundary portion 9 ″ of the cutting insert 1 itself is about 164 °, and the inner angle α is about 166 °. At this time, as will be described in detail later, as shown in FIG. 10B, the cutting angle EH2 of the second cutting edge portion 9b is smaller than the cutting angle EH1 of the first cutting edge portion 9a (EH2 <EH1).

Next, the operation and effect of the cutting edge replacement type rotary cutting tool 13 to which the cutting insert 1 is mounted according to this embodiment will be described.

FIG. 11 is an enlarged view of the vicinity of one cutting insert in a situation where a workpiece is being processed. As schematically shown in FIG. 11, the cutting tool 13 is rotated around the axis RA and is sent to the workpiece W with a constant cut. Since it is high-feed machining, the depth of cut is very small compared to the case of right-angle shoulder cutting. In FIG. 11, the working cutting edge 8 u is located on the most distal end side of the tool in the region including the most protruding portion (corresponding to the portion 9 c) in FIGS. 2 and 3. Further, in this machining mode, the cut is within the range of the first cutting edge portion 9a of the main working cutting edge 9u in the direction parallel to the axis RA from the second cutting edge portion 9b. However, the processing form is not limited to this, and as shown in FIG. 12, when more cutting is to be made, up to the corner cutting edge 10u of the working cutting edge 8u is used for cutting.

The cutting insert 1 of the present embodiment has a configuration in which a cutting edge 8 composed of a main cutting edge 9 and a corner cutting edge 10 is provided at an intersecting ridge line portion formed by the first end face 2 and the peripheral side face 4. It is a cutting insert for high feed.

In the cutting tool of the present embodiment, when the cutting insert 1 is viewed from the direction substantially opposite to the first end surface 2, the first cutting edge portion 9a of the working cutting edge 8u has the tangent line Ld and the extension line N1 shown in FIG. 10A. Are arranged so that the internal angle α formed by Since the line N1 is an extension line of the first cutting edge portion 9a, the cutting angle EH1 at the first cutting edge portion 9a when the cutting insert 1 is mounted on the tool body 14 is about 14 ° (≈ 180 ° −α). Therefore, in the blade-tip-exchange-type rotary cutting tool 13 of the present embodiment, so-called high feed machining, in which cutting is performed with a small cut and a large feed speed, can be realized. The cutting angle EH1 is an angle formed by the first cutting edge portion 9a (that is, the line N1) and the plane perpendicular to the axis RA of the cutting tool (that is, the line Ld ′ parallel to the line Ld) as shown in FIG. 10B. The inner angle α is not limited to about 166 °, and can be changed as appropriate as long as high feed processing is possible. The inner angle α is preferably 160 ° or more. That is, the cutting angle EH1 is preferably 20 ° or less. The inner angle α is more preferably 165 ° or more. With such an angle, the machining efficiency in high-feed machining can be particularly increased.

In the side view of the cutting insert 1 (FIG. 3), the first cutting edge portion 9a of the main cutting edge 9 is opposite to the side to which the second cutting edge portion 9b is connected (the corner cutting edge 10). The region 9 ap has the portion 9 ap that is closest to the intermediate surface M. Further, in the cutting insert 1, the corner cutting edge 10 connected to the first cutting edge portion 9a has a portion that is shaped to be inclined toward the closest portion 9d. With such a configuration, the following effects can be obtained.

The cutting insert 1 of the present embodiment has a first cutting edge portion 9a of the main cutting edge 9 as viewed from the side, from the end opposite to the end connected to the second cutting edge 9b (that is, the first cutting edge 9a). A portion 9 ap that is closer to the intermediate surface M is formed as it is separated from the first corner 6 a side toward the second cutting edge portion 9 b side. Therefore, as shown in FIG. 7, even when the cutting insert 1 itself is mounted so that the radial rake is 0 °, the radial rake is positive in the front view of the tool body 14 (FIG. 7). There is a cutting edge CA. This will be described with reference to FIG.

FIG. 13 shows a line L1 extending from the tool axis RA in the tool radial direction (that is, a line with a radial rake of 0 °). That is, the line L1 passes through the tool axis RA and the outermost peripheral portion of the cutting insert. Further, in FIG. 13, in the end region of the first cutting edge portion 9a of the main working cutting edge 9u, as a tangent line at that point so as to pass through a point between the closest portion 9d and the corner cutting edge 10. A drawn line L2 is shown. The line L1 and the line L2 intersect with each other instead of being parallel to each other. In FIG. 13, the line L2 extends forward in the tool rotation direction compared to the line L1 on the tool outer peripheral side from the intersection of the line L1 and the line L2. It will be understood from the angle β of the line L2 with respect to the line L1 that the radial rake is positive in the cutting edge 8u of the working cutting edge 8u in the vicinity of the closest portion 9d, particularly in the cutting edge portion 9ap on the outer peripheral side from the portion 9d. The chip portion generated from the cutting edge portion where the radial rake is positive tends to flow out in the inner circumferential direction of the tool. If even a part of the whole chip faces in the tool inner circumferential direction, the chip can be prevented from being discharged in the tool outer circumferential direction as a whole. In particular, if the radial rake is positive in the vicinity of the corner cutting edge 10 that is the outermost peripheral side of the tool, the chip even in a situation in which the discharge of the most chip that is the working cutting edge up to the corner cutting edge 10 is a problem. Can be prevented from being discharged toward the outer periphery of the tool. As a result, the tool life is reduced and the work piece is caused by chipping between the outer surface of the cutting insert 1 and the work piece, or the chip colliding with the work surface of the work piece. It is possible to suppress deterioration in accuracy of the processed surface.

As described above, in this embodiment, the portion 9ap on the outer peripheral side from the closest portion 9d of the first cutting edge portion 9a of the main cutting edge 9 is continuous with the corner cutting edge 10, and the corner cutting edge 10 has the above shape. . That is, as with the portion 9ap, the corner cutting edge 10 is generally inclined so as to approach the intermediate surface M as it approaches the closest portion 9d. With this configuration, when the cutting insert 1 is mounted on the tool body 14, a positive radial rake is further imparted at the outermost peripheral portion of the working cutting edge 8u (that is, the region where the corner cutting edge 10 is present). It becomes easy to be done. Since the cutting speed on the outermost peripheral side of the tool is the fastest, the chip generated from the cutting edge part at that point or the part is relatively larger than the chip on the inner peripheral side of the tool or the part (kinetic energy). ) And significantly affects the behavior of the entire chip. Therefore, when cutting to the corner cutting edge 10 as shown in FIG. 12, it is generated by the cutting edge portions 9ap and 10 having a positive radial rake located on the outermost peripheral side of the tool and flows out toward the inner peripheral direction of the tool. Depending on the chip to be cut, the entire chip becomes more difficult to be discharged in the outer peripheral direction of the tool. That is, the chips are discharged to the outer peripheral side so as to go obliquely upward, and the chips are caught between the outer surface of the cutting insert 1 and the workpiece, or the chips collide with the machining surface of the workpiece. Can be prevented.

In the side view of the cutting insert 1 (that is, FIG. 3), the first cutting edge portion 9 a as a whole has a concave curved shape (substantially concave arc shape) that is recessed in the direction approaching the intermediate surface M. When the entire first cutting edge portion 9a is shaped as a positive radial rake when mounted on the tool body 14, the chips go too far toward the inner periphery of the tool, and the inside of the chip pocket Chips may become clogged. However, as in the present embodiment, since the first cutting edge portion 9a is concave, the inner peripheral side portion (second cutting edge portion 9b side portion) of the first cutting edge portion 9a located on the inner peripheral side of the tool. 9aq can be provided with an opposite inclination facing the tool outer peripheral side, so that the outflow direction of chips can be balanced in relation to the outer peripheral side portion 9ap.

In the side view of the cutting insert 1 in FIG. 3, the second cutting edge portion 9 b has a portion 9 c farthest from the intermediate surface M. By configuring in this way, in the corner portion 6 and its peripheral region, the corner portion 6 (corresponding to the corner cutting edge 10) of the first end surface 2 is configured to have the largest distance from the intermediate surface M. The average height from the boss face and the average thickness of the adjacent rake face can be increased. Since the corner portion 6 and its periphery are portions that receive cutting resistance from both the bottom surface side and the side surface side of the processed surface of the workpiece, strength is required. As described above, by providing the second cutting edge portion 9b that does not affect the chip discharge direction with the portion 9c having the longest distance from the intermediate surface M, the corner portion 6 is not deteriorated without deteriorating the chip discharge performance. And the intensity | strength of the periphery (especially area | region which contacts the side surface side of the processed surface of a to-be-processed object) can be raised.

In the side view of the cutting insert 1, the second cutting edge portion 9b has a convex curved shape (that is, a substantially convex arc shape) protruding in a direction away from the intermediate surface M. Since the second cutting edge portion 9b has the portion 9d farthest from the intermediate surface M, the second cutting edge portion 9b tends to be a portion that first bites into the workpiece in cutting. The largest impact is applied to the portion that bites first, but the second cutting edge portion 9b can bite the workpiece smoothly by adopting a convex curved shape. This makes it possible to suppress damage to the second cutting edge portion 9b.

The second cutting edge is curved in a convex shape in plan view of FIG. Thereby, when the cutting insert 1 is mounted on the tool body, the cutting angle EH2 at the second cutting edge portion 9b can be made smaller than the cutting angle EH1 at the first cutting edge portion 9a. The cut angle EH2 at the second cutting edge portion 9b is shown in FIG. 10B. The cutting angle EH2 at the second cutting edge portion 9b is determined when the straight line N2 is determined in FIG. 10B so as to connect both ends of the second cutting edge portion (corresponding to the boundary portions 9b ′ and 9b ″). And the tangent line Ld in FIG. By making the cutting angle EH2 at the second cutting edge portion 9b located on the most distal end side of the cutting tool relatively small, the chip cutting thickness by cutting at the second cutting edge portion 9b is relatively thinner. Become. Therefore, the cutting resistance applied to the second cutting edge portion 9b can be reduced, and thus the damage to the second cutting edge portion 9b can be further suppressed. The cutting angle EH2 at the second cutting edge portion 9b is preferably 5 ° to 15 ° smaller than the cutting angle EH1 at the first cutting edge portion 9a.

Also, the present invention is particularly effective when the cutting insert 1 is mounted so that the radial rake is 0 ° or less. This is because the radial rake of the main cutting edge 9 is likely to be negative only when mounted in such a manner.

The cutting insert according to the present invention and the rotary cutting tool on which the cutting insert is mounted are preferably used for high-feed machining with a cutting angle of 30 ° or less. In the said embodiment, although the cutting angle differed with the 1st cutting edge part 9a and the 2nd cutting edge part 9b, the cutting angle of the 1st cutting edge part 9a set relatively large is set to 30 degrees or less. It is good to be done. In the high feed processing, the feed may be set to 0.2 mm / blade or more, more preferably 0.3 mm / blade or more, at a feed fz per blade. The feed per tooth fz is defined by the formula “fz = vf / (z · n)”, where vf (mm / min) is the table feed speed per minute, z is the number of blades, n (min ⁻¹ ) is the spindle rotation speed (feed per rotation).

In the cutting insert, the inclination of the first, second, and corner rake face portions r1, r2, r3 with respect to the intermediate surface M may be changed. The first rake face part r1 of the first cutting edge part 9a may increase in inclination as it approaches the second rake face part r2 of the second cutting edge part 9b. That is, the second rake face portion r2 of the second cutting edge portion 9b can be inclined more greatly with respect to the intermediate surface M than the vicinity of the corner rake face portion r3 of the first corner 6a of the first rake face portion r1 of the first cutting edge portion 9a. . By changing the rake angle of the first cutting edge portion 9a so that the rake angle is larger on the inner peripheral side than on the outer peripheral side, the chips generated by the first cutting edge portion 9a are more on the inner peripheral side. It tends to flow out. For this reason, it is further prevented that chips are bitten between the outer surface of the cutting insert 1 and the workpiece or that the chips collide with the workpiece surface of the workpiece. Further, the corner rake surface portion r3 of the corner cutting edge 10 has an inclination between the vicinity of the first corner 6a of the first rake surface portion r1 and the second rake surface portion r2, and the inclination changes so as to be smoothly connected thereto. Good.

The representative embodiment of the present invention has been described above, but the present invention is not limited to that embodiment. Various changes and modifications can be made to the present invention without departing from the spirit and scope of the present invention as defined by the claims of this application.

Claims

The first end surface (2) having a substantially polygonal shape, the second end surface (3) facing the first end surface (2), the first end surface (2), and the second end surface (3) are connected. A peripheral side surface (4); and at least one cutting edge (8) formed at an intersecting ridge line portion between the first end surface (2) and the peripheral side surface (4), the first end surface (2 ) And the second end face (3), a cutting insert (1) for high feed machining having a central axis (O) defined to penetrate through the second end face (3),
The cutting edge (8) has a cutting edge portion (9) extending between the first corner (6a) and the second corner (6b) adjacent to each other of the first end face (2),
The cutting edge portion (9)
A first cutting edge (9a) on the first corner (6a) side;
A second cutting edge (9b) on the second corner (6b) side, the second cutting edge (9b) connected to the first cutting edge (9a);
With
When a surface passing through between the first end surface (2) and the second end surface (3) and intersecting at right angles to the central axis (O) is defined as an intermediate surface (M), the first surface The cutting edge portion (9a) has a portion (9ap) shaped so as to be closer to the intermediate surface (M) as it is separated from the first corner (6a) toward the second corner (6b). Have
Cutting insert (1).
The cutting edge (8) includes a corner cutting edge (10) extending along the first corner (6a) that smoothly connects to the first cutting edge portion (9a).
Cutting insert (1) according to claim 1.
The corner cutting edge (10) has a portion shaped to be closer to the intermediate surface (M) as it approaches the first cutting edge (9a).
Cutting insert (1) according to claim 2.
In the side view of the cutting insert (1), the first cutting edge (9a) has a concave curved shape that is recessed in a direction close to the intermediate surface (M).
Cutting insert (1) according to any one of claims 1 to 3.
In the side view of the cutting insert (1), the second cutting edge (9b) has a portion (9c) having the longest distance from the intermediate surface (M) in the cutting edge (8). Have
Cutting insert (1) according to any one of the preceding claims.
In the side view of the cutting insert (1), the second cutting edge (9b) has a convex curved shape protruding in a direction away from the intermediate surface (M).
Cutting insert (1) according to claim 5.
When the cutting insert (1) is viewed from the side facing the first end surface (2), the second cutting edge (9b) is curved outwardly of the cutting insert (1), and the first The one cutting edge (9a) extends linearly between the second cutting edge (9b) and the first corner (6a) while smoothly connecting to the second cutting edge (9b).
Cutting insert (1) according to any one of the preceding claims.
When the cutting insert (1) is viewed from the side facing the first end face (2), the second cutting edge (9b) is at an internal angle of 165 ° or more and less than 180 ° with the first cutting edge (9a). The cutting insert (1) according to any one of claims 1 to 7, which forms (θ1).
The first end face (2) has n corners (where n is an integer of 3 or more),
The cutting insert (1) has a shape that is rotationally symmetric about n times around the central axis (O),
The cutting insert according to any one of claims 1 to 8.
Cutting edge replacement comprising a tool body (14) having a rotational axis (RA) and having at least one insert mounting seat (16) formed thereon, wherein a cutting insert is detachably mounted on the insert mounting seat (16). Type rotary cutting tool (13),
The cutting insert is a cutting insert (1) according to any one of claims 1 to 9,
When viewed from the front end face of the blade-tip-exchange-type rotary cutting tool (13), at least the first cutting edge portion (9a) of the cutting insert (1) has a portion where the radial rake is positive. ,
Cutting edge exchange type rotary cutting tool (13).
The cutting insert (1) itself is mounted on the tool body (14) with a radial rake of 0 ° or less,
The blade-tip-exchange-type rotary cutting tool (13) according to claim 10.
Regarding the working cutting edge (8u), the second cutting edge portion (9b) of the cutting edge portion is located closest to the tool tip side, and the first corner (6a) adjacent to the first cutting edge portion (9a). The cutting insert is mounted on the insert mounting seat (16) so that is located on the outermost side of the tool,
The cutting angle (EH2) at the second cutting edge (9b) is smaller than the cutting angle (EH1) at the first cutting edge (9a),
A blade-exchangeable rotary cutting tool (13) according to claim 10 or 11.