JP2005169511A - Cutting edge replaceable type rotating tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting tool enabling stable high efficiency machining in contour line machining or the like by suppressing trembling vibration in cutting a corner or a groove. <P>SOLUTION: An insert mounted to this cutting edge replaceable type rotating tool is formed in an approximately square shape from the rake face side view and has a pinhole. Four sides forming cutting edge ridgelines are formed in outward projecting shapes, and a connection part of two adjacent sides is formed of a corner cutting edge comprising a curve of an approximately round shape and/or a straight line. A radius r(mm) of the corner cutting edge is 1≤r≤5, and a flat part is formed at nearly the center of a flank. An insert is mounted to the cutting edge replaceable type rotating tool so that the corner cutting edge projects to the outer peripheral side of the tip of the cutting edge replaceable type rotating tool, that the cutting edge ridgeline of a projecting shape continuous with one end of the corner cutting edge forms a peripheral cutting edge, while the cutting edge ridgeline of a projecting shape continuous with the other end forms a main cutting edge and that an outermost peripheral point and/or a lowest point of the tool cutting edge is on the corner cutting edge. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a cutting edge exchange type rotary tool (hereinafter simply referred to as a cutting tool) to which an insert is detachably attached, and particularly relates to a tool particularly suitable for high feed.

Regarding a cutting tool suitable for high-feed machining and an insert used therefor, Patent Document 1 discloses that the shape of the insert in the cutting tool is a substantially quadrangular shape, and the four sides forming the cutting edge ridge line are convex outward in the arc, A flat portion is provided at substantially the center. However, the method of attaching the insert of Patent Document 1 is a method of attaching by tightening with a wedge or fixing only by providing a screw hole in the insert, and no consideration is given to clamp rigidity that becomes a problem during engraving. Furthermore, when the standing wall portion of the work material is formed, the length of the cutting edge that comes into contact with the work material becomes large, and no consideration is given to reducing the cutting resistance.
In Patent Document 2, in a throw-away rotary tool, the throw-away tip has a substantially quadrangular shape, and of the four sides forming the throw-away tip, two sides at symmetrical positions are linear, and other symmetrical The two sides at the position consist of a circular arc part and a straight line part connected to the circular arc part, and the tool has an outer peripheral cutting edge at the side, a main cutting edge at the arc part at the other side, and an inner peripheral cutting edge at the linear part. And a technique in which the cutting angle of the main cutting edge is 3 degrees or more and 35 degrees or less is disclosed. When the standing wall portion of the work material is formed using the rotary tool of Patent Document 2, the cutting resistance is devised so as to avoid an increase in the cutting edge length contacting the work material and to be substantially constant. Consideration has been given to the reduction of

Japanese Patent Laid-Open No. 2003-275917 Japanese Patent No. 3317490

  In recent high-efficiency processing such as contour processing, chatter vibration occurs in corners and groove cutting, which may lead to a problem of chipping of the cutting edge. An object of the present invention is to provide a cutting tool that suppresses chatter vibrations in corner and groove cutting, and realizes stable high-efficiency machining in contour line machining and the like.

  In the cutting tool of the present invention, the insert attached to the cutting tool has a substantially square shape when viewed from the rake face side and has a pin hole, the four sides forming the cutting edge ridge line are convex outward, and two adjacent sides The corner blade is formed of a substantially R-shaped curve and / or straight line, and the radius r (mm) of the corner blade is 1 ≦ r ≦ 5, and a flat portion is provided at the substantially central portion of the flank. When the insert is attached to the blade-tip-exchangeable rotary tool, the corner blade is mounted so as to protrude to the outer peripheral side of the tip portion of the blade-tip-exchangeable rotary tool, and the convex shape is continuous with one end of the corner blade The cutting edge ridge line forms an outer peripheral cutting edge, and the convex cutting edge ridge line connected to the other end of the corner blade is the main cutting edge forming the bottom edge, and is the outermost peripheral point of the cutting edge of the cutting edge exchangeable rotary tool. And / or mounted so that the lowest point is on the corner blade It is indexable rotary tool, wherein the door. By adopting the above configuration, the strength of the cutting edge is improved, and the cutting resistance can be reduced by adjusting the cutting edge length, so chatter vibrations in corner and groove cutting are suppressed, and stable in contour processing, etc. It is possible to provide a cutting tool that realizes high-efficiency machining.

  The cutting tool of the present invention makes it possible to provide a cutting tool that suppresses chatter vibrations in corner and groove cutting and realizes stable and highly efficient machining in contour line machining and the like.

  1 and 2, the insert 7 attached to the cutting tool body 5 has a substantially square shape when viewed from the rake face side and has a pin hole, and the four sides forming the cutting edge ridge are convex outward. In addition, a corner blade 12 formed of a substantially R-shaped curve and / or straight line is formed at the connection between two adjacent sides. The method of fixing the insert to the tool body is a first method in which the screw hole provided in the insert seat of the tool is aligned with the pin hole provided in the insert, the fixing screw is inserted and tightened, and the clamp piece 4 Is used together with the second method by pressing the rake face of the insert. In this way, by using two independent fixing methods in combination, it becomes possible to improve the rigidity of the insert cutting edge. In particular, it is an effective method for suppressing chatter vibration of the cutting edge in high feed machining. is there. Furthermore, when the insert seats are formed at unequal intervals in the circumferential direction, it is advantageous to avoid resonance due to chatter vibration during machining of the workpiece corner portion. FIG. 3 shows an enlarged view of the insert of FIG. As shown in FIG. 3, the outermost peripheral point G and / or the lowest point J of the cutting edge is mounted on the corner edge 12. In particular, when the outermost peripheral point G is mounted so as to be closer to the inner peripheral side of the tool than the connecting portion between the corner blade 12 and the outer peripheral blade 6, the cutting edge length involved in cutting can be adjusted. When the cutting edge length is set to be large, it is possible to avoid that the cutting blade center portion having the weakest blade strength first comes into contact with the work material and receives an impact. When the insert is attached to the cutting tool, the corner blade is set so as to protrude to the outer peripheral side of the tip portion of the blade-tip-exchange-type rotary tool, and the convex cutting edge ridge line connected to one end of the corner blade 12 forms the outer peripheral blade 6. The convex cutting edge ridge line connected to the other end of the corner edge 12 is the main cutting edge 3 forming the bottom edge. FIG. 4 shows a front view of the insert. The insert includes four cutting edge ridge lines 1 that are convex outward from the center, and the cutting edge ridge line 1 is formed of a curved line and / or a straight line and has a substantially arc shape. The radius r (mm) of the corner blade 12 that is a connecting portion between the cutting edge ridge line and the cutting edge ridge line is 1 ≦ r ≦ 5. By setting r to 1 ≦ r ≦ 5, the cutting edge strength can be improved and a defect can be avoided. Furthermore, by setting the cutting edge length to an appropriate range, it is possible to avoid chatter vibration due to an increase in cutting resistance and damage to the insert due to this. When r is less than 1, chipping of the corner blade 12 tends to occur. On the other hand, when r is greater than 5, chatter vibration during cutting becomes significant and the insert itself is damaged. It tends to be easier. Therefore, r is limited to 1 ≦ r ≦ 5. 5 is a side view in the direction of arrow A in FIG. 4, and FIG. 6 is a projection view of FIG. As shown in FIG. 5, the flat portion 2 is provided from the position retreated from the cutting edge ridge line to the bottom surface of the insert at substantially the center of the flank. The flat portion 2 serves as a contact surface when attached to the tool body, but accurate positioning is possible due to the flatness. The ratio M / K of the area M of the flat part 2 to the projected area K of the flank including the flat part shown in FIG. 6 is 0.3 ≦ M / K ≦ 0.4. By setting M / K to 0.3 ≦ M / K ≦ 0.4, it is possible to perform more accurate positioning and secure fixing of the insert. When M / K is less than 0.3, a sufficient contact area cannot be ensured, and the effect of providing a flat portion cannot be obtained. On the other hand, if it exceeds 0.4, it is not appropriate because it causes a reduction in the strength of the blade edge. 7 shows a side view in the direction of arrow B in FIG. The difference β-α between the angle β formed by the rake face and the flank shown in FIG. 7 and the angle α formed by the flat portion 2 and the rake face shown in FIG. 5 is set to satisfy 2 ≦ β−α ≦ 6. To do. When this difference β−α is less than 2, a sufficient contact area cannot be obtained, and when it exceeds 6, the cutting edge strength is lowered. As shown in FIG. 4, the cutting edge ridge line 1 having a convex shape is formed of a curve and / or a straight line, and the curvature radius R when the cutting edge ridge line is regarded as a substantially arc shape is the inscribed circle diameter D of the insert. The ratio R / D of R and D is taken as 0.7 ≦ R / D ≦ 1.6. When it is less than 0.7, it becomes substantially the same shape as the round insert, and the cutting angle increases in applications where the cutting depth becomes large. Therefore, the contact length between the work material and the cutting edge in the outer peripheral blade portion is increased, and the cutting resistance is increased, so that it is not suitable for high feed processing. On the other hand, if it is larger than 1.6, it becomes substantially the same shape as the straight cutting edge, and the characteristics of the substantially convex arcuate cutting edge cannot be found. In the present invention, D (mm) is not less than φ10 and not more than φ16, preferably not less than φ12 and not more than φ14. When D is larger than φ16, the main cutting edge becomes longer, leading to an increase in cutting resistance, which is inconvenient for high-feed machining. On the other hand, if it is less than φ10, the insert having a screw hole is insufficient in strength and tends to be damaged. Therefore, in the present invention, D is preferably φ10 or more and φ16 or less. Here, the characteristics of the substantially convex arcuate cutting edge are that the contact cutting edge length at the time of cutting is appropriately increased to make it stronger against interrupted cutting, and heat cracks occur due to the compression force acting. However, it has a long life until destruction. As shown in FIG. 7, the angle κ formed by the line perpendicular to the bottom surface of the insert and the flank is preferably 5 degrees to 20 degrees. However, the value of κ needs to be determined in consideration of the balance between the hardness of the work material and the strength of the cutting edge. That is, in high-feed machining with a high-hardness work material, for example, SKD61 such as HRC40 or higher, an excessive stress acts on the cutting edge portion due to a large cutting resistance, so κ is preferably 6 to 11 degrees. . Thereby, there exists an effect which maintains the blade-tip intensity | strength and avoids the defect | deletion of a cutting blade. On the other hand, when the hardness of the work material is less than HRC40, the cutting resistance can be reduced without much concern about the strength of the cutting edge. From FIG. 8, it is preferable that the cutting angle γ of the straight portion length F from the lowest point J of the cutting edge to the outer peripheral side is 9 degrees or more and 12 degrees or less. When γ is less than 9 degrees, a highly hard work material, for example, HRC 40 or more, is liable to cause welding of the work material to the cutting edge portion, and the tool has a short life, which is not preferable. If γ is greater than 12 degrees, it is not preferable because the cutting edge tends to be damaged. Further, by making the length F (mm) of the straight portion from the lowest point of the main cutting edge toward the outer peripheral side in a range of 4 ≦ F ≦ 7, when machining a particularly hard work material, This has the effect of improving chip discharge. This is because the chips are given an appropriate thickness to generate chips without mussels. The radial rake angle Rr and the rotational axis rake angle Ar (not shown) of the cutting tool shown in FIGS. 1 and 9 may be selected according to the type of work material. That is, when the hardness of the work material is less than HRC40, it is preferable to select −45 ≦ Rr ≦ −5 and 5 ≦ Ar ≦ 10. On the other hand, when the hardness of the work material is HRC40 or more, it is preferable to select −3 ≦ Rr ≦ 3 and −4 ≦ Ar ≦ 4. When the hardness of the work material is less than HRC40, by setting the value of Rr to a negative value, as shown in FIG. 3, the chips generated in the cutting start region 8 in contact with the work material Is thin, and gradually increases with the rotation of the tool. Since a thick chip is generated in the cutting end region 9, the impact force applied to the tool can be reduced and high feed can be achieved. More preferably, Rr is set to a negative value from -15 degrees to -10 degrees. On the other hand, when the hardness of the work material is HRC40 or more, it is preferable to set the value of Rr to a value of −3 ≦ Rr ≦ 3, and a longer life can be obtained.

  In the present invention, the impact generation mechanism at the time of cutting, which has been considered impossible in the past, is defined as the first stage, when biting the work material at the beginning of cutting, as the second stage, Focusing on the impact mitigation divided into two stages until the workpiece is separated, the former is the lowest point of the tip of the main cutting edge by the main cutting edge of a substantially convex arc shape consisting of a curve and / or a straight line Let J be a cutting start region 8 and let the work material bite thinly. The latter uses a negative rake angle in the radial direction to generate chips that gradually increase with the rotation of the tool, thickest in the cutting end region 9, finds the optimum value for the phase difference of the chip generation form, and reduces the impact. Resistant to intermittent cutting and long life.

  FIG. 10 is a perspective view of another insert according to the present invention, and is an example in which a breaker-shaped rake groove is provided along the cutting edge ridge line of the insert. FIG. 11 shows a perspective view of another insert according to the present invention, which is an example in which the rake face of the insert is raised and raised. FIG. 12 shows an example in which, when the insert shown in FIG. 11 is set on a cutting tool, Rr of the main cutting edge changes continuously or intermittently from Rr1 toward Rr2. The number of inserts attached to the cutting tool of the present invention is 2 or more and 7 or less, and the tool diameter H (mm) at this time is preferably in the range of 25 ≦ H ≦ 125. This is effective in that the number of cutting edges capable of high-efficiency machining can be set even with versatile cutting machine horsepower. Furthermore, it is the range which can provide sufficient pocket space also from the surface of chip discharge. Hereinafter, although this invention is demonstrated based on an Example, the cutting tool and insert of this invention are not limited to the following, It is also contained in this technical scope to change suitably.

(Example 1)
A tool body was prepared such that H had a φ63 mm tool body with four insert seats, Rr was −6 degrees, and Ar was 9 degrees. 4 to 7 as inserts to be mounted on the cutting tool, D is 12.7 mm, R is 15 mm, α is 70 degrees, β is 75 degrees, insert thickness is 5.56 mm, flat part No. 2 produced an insert provided from a position retreated 0.7 mm along the flank from the cutting edge ridge line to the bottom of the insert, and mounted on the tool body. For the insertion of the insert, a cutting tool was prepared by using both a fixing method using a fixing screw and a fixing method using a clamp piece. Table 1 shows the tool shape and insert shape used in the present invention and the comparative example. Using these cutting tools, a cutting test was performed under the following cutting conditions. The evaluation method evaluated the cutting state using chatter vibration as a guide.

(Cutting conditions)
Cutting method: Side roughing, (shoulder cutting → groove cutting → shoulder cutting)
Work material: S50C (Hardness HB200)
Tool blade diameter: φ63 (4 blades)
Tool protrusion L: 200mm
Cutting speed Vc: 160 m / min
Table feed rate Vf: 1000, 2000, 3000, 4000 mm / min
Feed per tooth fz: 0.31, 0.62, 0.93, 1.24 mm / tooth rotation speed n: 808 min-1
Cutting depth ap: 1.5 mm
Cutting width ae: 35 (shoulder cutting) to 63 (grooving) mm
Cutting oil: None, (Dry cutting by air blow)
Regarding the cutting tools of Invention Examples 3 to 13 shown in Table 1, the inserts whose corner blade r values are 1, 3, and 5 are changed in M / K value, β-α value, and R / D value, respectively. I put on what I did. Inserts with an r value of 0.5 were prepared for Comparative Examples 1 and 2, and inserts with an r value of 5.5 were prepared for Comparative Examples 14 and 15. Using these tools, as shown in FIG. 13, a cutting test was performed assuming engraving of contour lines. The tool protrusion amount L from the gauge line was set as long as 200 mm so that chatter vibrations were likely to occur, and was attached to the arbor. The machining shape was also set to shoulder shaving → grooving → shoulder shaving so that chatter vibration was likely to occur. FIG. 14 shows the results of the cutting test. However, the mark ◯ in the figure indicates good cutting performance without chatter vibration, △ indicates that a minute chatter vibration or minute defect occurs but can be used, and × indicates that a large chatter vibration or large defect occurs and cannot be used .

  From FIG. 14, Examples 3 to 13 of the present invention can be processed in the entire region of Vf = 1000, 2000, 3000, and 4000 mm / min from the first stage, and are engraved with the second stage, the third stage, and the fourth stage. However, it was possible to carve without large chatter vibrations or heavy defects. Comparative Example 1 was disabled due to the occurrence of a heavy defect in which the corner edge part was lost at Vf = 4000 mm / min. This is because the corner blade portion has insufficient strength. In Comparative Example 2, since Vf = 1000 mm / min, chatter vibration due to the outer peripheral blade coming into contact with the standing wall portion occurred, and since large chatter vibration occurred at Vf = 3000 mm / min, it was not usable. In Comparative Examples 14 and 15, large chatter vibration occurred at Vf = 3000 mm / min, and cutting was impossible. This is because the cutting resistance of the corner blade portion is large. The cutting states of Invention Examples 4 and 5 were good, but Invention Example 4 showed a tendency for the insert to fluctuate because the area of the flat portion serving as the constraining surface was small. In Invention Example 5, since the angle of the flat portion serving as the constraining surface is large, the insert tends to fluctuate. This is because a trace that seems to have moved a little during the cutting was observed on the insert seating surface of the tool body. Further, Example 6 of the present invention was in a state where it could be used continuously, but fine defects were observed on the cutting edge. This is because the R value is small and the strength is slightly insufficient. Invention Example 7 was also in a state where it could be used continuously, but small chatter vibration was generated. This is because the cutting resistance was slightly large because the R value was large. The conventional example 16 cannot be used because r is small and a heavy defect in which the corner blade part is lost occurs. This is because the corner blade portion has insufficient strength. Furthermore, generation of large chatter vibration due to the outer peripheral blade contacting the standing wall portion was also observed.

(Example 2)
Using a tool body similar to that in Example 1, an insert was mounted on one insert seat, and a cutting test was performed under the following cutting conditions. Table 1 also shows the tool shape, insert shape, and evaluation results used. In the evaluation method, the shape of the initial chip and the damaged state of the initial insert cutting edge when shouldering to a cutting length of 200 mm were observed and evaluated for each insert.
(Cutting conditions)
Cutting method: flat shoulder machining Work material: SKD61 (HRC45)
Tool blade diameter: φ63 (single blade)
Cutting depth ap: 1.0 mm
Cutting width ae: 40 mm
Cutting speed Vc: 60 m / min
Rotational speed n: 303 min-1
Table feed rate Vf: 242 mm / min
Feed per tooth fz: 0.8 mm / tooth
Cutting oil: None (dry cutting by air blow)

  From Table 2, Examples 3 to 9 and 13 of the present invention, Comparative Examples 1, 2, 14, 15 and Conventional Example 16 use an insert having a substantially convex arc-shaped cutting edge, and the chipping-like mussels are formed. Many occurred, and a defect occurred at the boundary of the insert. These defects are caused by the chip flow being unstable because the chip is thin and has a shape that tends to cause mess. On the other hand, Example 10 of the present invention uses an insert having a cutting edge in which the γ value is set to 8 degrees, and the chip is reduced to such a degree that a fine whisker-like mussel is generated on a chip, and a defect generated at a boundary portion of the insert Was also very small. Inventive Example 10 had a larger chip thickness than the substantially convex arcuate cutting edge of Inventive Example 8, but the γ value was as weak as 8 degrees, so a slight musiness was observed. However, there were no defects as in the case of Invention Examples 3 to 9 and 13, and the apparatus could be used continuously. Invention Example 11 uses an insert having a cutting edge with a γ value set to 10 degrees, and there is no occurrence of scissors-like lashes on the chips, showing a good shape, and the insert shows normal wear. In Example 11 of the present invention, by giving an appropriate chip thickness, there was no occurrence of stuffiness on the chips, and the flow of the chips was smooth. Example 12 of the present invention uses an insert having a cutting edge with a γ value set to 13 degrees, and there is no occurrence of scissors-like lashes on the chips, and a good shape is observed, and a minute defect is generated at the boundary portion of the insert. . Invention Example 12 had a cutting edge shape in which the chip thickness was the largest in the present Example 2. For this reason, it showed a good chip form in which chipping was difficult to occur. However, since the chip thickness was increased, a load was applied to the cutting edge and a fine defect was generated. From this, a substantially convex arcuate cutting edge is suitable for high feed processing for steel materials such as S50C that can be processed relatively easily. However, in high-hardness material processing exceeding HRC40, the γ value is 8-13. By providing a straight cutting edge with a certain degree, it is possible to increase the life by giving the chip a certain amount of thickness and generating crumb-free chips, and smoothing the flow of chips. is there.

FIG. 1 shows a bottom view of a cutting tool of an example of the present invention. FIG. 2 is a sectional view taken along the line CC of FIG. FIG. 3 shows details of the main cutting edge portion of FIG. FIG. 4 shows a front view of an insert to be mounted on the tool of the present invention. FIG. 5 shows a side view in the direction of arrow A in FIG. FIG. 6 shows a projection of the side view of FIG. 7 shows a side view in the direction of arrow B in FIG. FIG. 8 shows a diagram of another cutting tool of the example of the present invention. FIG. 9 shows the rake angle in the radial direction for the cutting tool of the example of the present invention. FIG. 10 shows a perspective view of another insert attached to the tool of the present invention. FIG. 11 shows a perspective view of another insert attached to the tool of the present invention. FIG. 12 shows another radial rake angle for the cutting tool of the example of the present invention. FIG. 13 is a diagram for explaining contour line engraving. FIG. 14 shows the results of the cutting test.

Explanation of symbols

1: Convex cutting edge ridge line 2: Flat part 3: Main cutting edge 4: Clamping piece 5: Tool body 6: Peripheral cutting edge 7: Insert 8: Cutting start area 9: Cutting end area 12: Corner edge ap: Depth of cut D: Diameter of the inscribed circle fz: Feed amount per blade F: Length of the straight part of the main cutting edge G: Outermost peripheral point of the cutting edge H: Tool diameter J: Bottom point of the cutting edge K: Flat part M: Area of flat part 2 r: Radius of corner edge R: Radius of curvature of substantially convex arcuate cutting edge Rr: Radial rake angle Rr1: Radial rake angle Rr2: Radial rake angle W : Work material α: Angle between flat part 2 and rake face β: Angle between rake face and flank face γ: Cut angle κ: Angle between line perpendicular to bottom face of insert and flank face

Claims (11)

In the blade-tip-replaceable rotary tool in which the insert can be attached and detached, the insert attached to the blade-tip replaceable rotary tool has a substantially square shape when viewed from the rake face side and has a pin hole, and the four sides forming the cutting edge ridge line are A corner blade that is convex outward and has a substantially R-shaped curve and / or straight line between two adjacent sides is formed, and the radius r (mm) of the corner blade is 1 ≦ r ≦ 5. A flat portion is provided in the approximate center of the flank face, and when the insert is attached to the blade-tip replaceable rotary tool, the corner blade is mounted so as to protrude to the outer peripheral side of the tip portion of the blade-tip replaceable rotary tool, The convex cutting edge ridge line connected to one end of the corner blade forms an outer peripheral cutting edge, and the convex cutting edge ridge line connected to the other end of the corner blade is a main cutting edge that forms a bottom blade, and the blade tip is replaced. Outermost point and / or lowest point of the cutting edge of a rotary tool Indexable rotary tool, characterized in that it is fitted to be on the corner edge. 2. The blade tip replaceable rotary tool according to claim 1, wherein a method of fixing the insert attached to the blade tip replaceable rotary tool is a first method by inserting a fixing screw into the pin hole provided in the insert, and a clamp piece The blade-tip-replaceable rotary tool characterized by using the second method by pressing the rake face of the insert using The blade tip replaceable rotary tool according to claim 1 or 2, wherein the flat portion of the insert attached to the blade tip replaceable rotary tool is provided from the position retracted from the cutting edge ridge line to the insert bottom surface, and the area M of the flat portion. Is a blade-tip-replaceable rotary tool characterized in that the ratio M / K to the projected area K of the flank including the flat portion is 0.3 ≦ M / K ≦ 0.4. The blade tip replaceable rotary tool according to any one of claims 1 to 3, wherein the flat portion of the insert attached to the blade tip replaceable rotary tool is provided from the position retracted from the cutting edge ridge line to the insert bottom surface side. The angle between the rake face and the rake face is α (degrees), and the angle between the rake face and the flank face is β (degrees), and the difference between α and β is 2 ≦ β−α ≦ 6. Cutting edge exchangeable rotary tool. 5. The cutting edge exchange type rotating tool according to claim 1, wherein the convex cutting edge ridge line of the insert attached to the cutting edge exchange type rotating tool is formed of a curve and / or a straight line. Rotary tool. 6. The cutting edge replacement type rotary tool according to claim 1, wherein a radius of curvature when the convex cutting edge ridge line of the insert attached to the tool is regarded as an arc is R, and an inscribed circle diameter of the insert is D. The ratio R / D of R and D is 0.7 ≦ R / D ≦ 1.6. The cutting edge exchange type rotary tool according to any one of claims 1 to 6, wherein an angle formed by a straight line portion extending from the lowest point of the main cutting edge toward the outer peripheral side to a straight line perpendicular to the rotation axis is defined as a cutting angle γ (degrees). The blade edge replaceable rotary tool, wherein 9 ≦ γ ≦ 12. The blade tip replaceable rotary tool according to any one of claims 1 to 7, wherein a length F (mm) of a straight portion from the lowest point of the main cutting edge toward the outer peripheral side is set to 4≤F≤7. The blade tip changeable rotary tool. The cutting edge exchange type rotary tool according to any one of claims 1 to 8, wherein a rake face of the insert attached to the cutting edge exchange type rotary tool has a convex shape from the bottom surface side of the insert toward the top surface, A blade-tip-exchange-type rotary tool characterized in that the rake angle in the radial direction changes continuously or intermittently toward the outer peripheral side. The cutting edge replaceable rotary tool according to any one of claims 1 to 9, wherein the number of inserts attached to the blade replaceable rotary tool is 2 or more and 7 or less, and the tool diameter H ( mm) is 25 ≦ H ≦ 125. 2. The blade tip replaceable rotary tool according to claim 1, wherein the insert attached to the blade tip replaceable rotary tool is provided with a breaker-shaped rake groove along the cutting edge ridge line.

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