JPH02250706A - End mill and manufacture thereof - Google Patents

Abstract

PURPOSE:To perform a highspeed processing on a high hardness material without causing defect using a CBN sintered body tip by performing chamfering on the corner of a peripheral cutting edge and an end cutting edge, and providing the end cutting edge whose entering angle on the tangent line of chamfering radius is 30 deg. or more on the side of periphery of the end cutting edge. CONSTITUTION:A chamfering part 72 and a first end cutting edge 68 are smoothly connected in the main body of an end mill, and a peaked part formed in the boundary part of the chamfering part 72 and a peripheral cutting edge 66 is quite small. In addition, although a peaked part is formed in the boundary part of the first end cutting edge 68 and a second end cutting edge 70 based on the difference between the entering angles k2 and k3, since the entering angle of the first end cutting edge 68 is 0 deg. or more and its length dimension L is about 0.5mm or more, the peaked part does not protrude in the shaft center direction of the main body of the end mill also from the side of corner of the first end cutting edge 68, and almost no substantially cutting action excepting penetrating processing is performed. Therefore, generation of defect such as chipping and broken edge, etc., is reduced even in a tip 56 made of CBN 64 having relatively low toughness wherewith highspeed, highly precise processing is possible even for high hardness material.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an end mill having a fixed cubic boron nitride chip and a method for manufacturing the same, and particularly relates to the shape of the cutting edge of the chip.

Conventional technology The tip of the tool body, which is driven to rotate around the axis, is coated with cubic boron nitride (hereinafter referred to as CB N (cu) at least on the surface).
There is known an end mill in which a tip provided with a sintered body (abbreviation of BIC BORON NTRIDE) is fixed by brazing or the like. The above-mentioned CBN sintered body is extremely hard, does not lose its hardness even at high temperatures, and has the property of not easily reacting with iron. It has various excellent features such as being able to perform high-precision machining by high-speed cutting even on high-hardness materials of H, C45 or higher, and having a long tool life.

On the other hand, since such a CBN sintered body has relatively low toughness, it is likely to cause defects such as chipping and edge chipping in milling, which is a series of interrupted cuts, and the outer peripheral edge and bottom edge of the chip that are likely to cause such defects. It is common to have square chamfers or eight chamfers on the corners. If the size of these corner chamfers or 8-chamfers is too small, sufficient damage prevention effect cannot be obtained, and if it is too large, the processed shape will be damaged. 0.3
~0.6 wm width, and in the case of 8 chamfers, the radius of curvature is set to about 0.3~0.6 wm.

The above-mentioned 8-chamfering process is performed by fixing an end mill (12) on a rotary table 10 and attaching a rotary grinding wheel 16 such as a diamond whetstone held on a whetstone head 14 to the end mill as shown in FIG. 8, for example. (12), and in this state rotate the rotary table 10 by a predetermined constant rotation angle P around the rotation center O3. That is, when forming eight chamfers 24 with a radius of curvature r at the corners of the outer peripheral edge 20 and the bottom edge 22, as in the tip 18 shown in FIG.
By rotating the adjustment knobs 30 and 32 of the X-axis table 26 and the Y-axis table 28, which are disposed on the rotary table 10 so as to be movable in directions perpendicular to each other, the cutter fixedly mounted on the X-axis table 26 is rotated. By moving the end mill (12) attached to the stand 34 via the holder 36, the center of curvature 02 at a position spaced apart from the outer circumferential cutter 20 and the bottom cutter 22 of the tip 18 by the same dimension as the radius of curvature r, respectively. While aligning the rotation center 01 with the rotation center 01, and in this state, rotating the rotary grinding wheel 16 around the axis, the grinding plane 38 is aligned with the rotation center 0. radius of curvature r
The rotary table IO is then rotated by a rotation angle P around the rotation center OI. The end mill (12) is mounted in such a manner that its axial center is perpendicular to the moving direction of the X-axis table 26, and is oriented in the direction away from the peripheral cutter 20, that is, approximately parallel to the axial center of the end mill (12). The alignment between the center of curvature Ot and the center of rotation 01 in the orthogonal direction is mainly performed by the adjustment knob 30 of the The alignment between the center of curvature 02 and the center of rotation O6 in the direction is mainly performed by the adjustment knob 32 of the Y-axis table 28.

Note that the grinding machine and the grinding procedure described above are just an example, and for example, instead of rotating the rotary chi-pull 10, the grinding wheel head 14 is set at the rotation center 0. The end mill (12) may be moved in the same direction as the rotary grinding wheel 16, or the end mill (12) may be moved after the rotary grinding wheel 16 is moved forward. It is also possible to do so.

Problems to be Solved by the Invention However, even in end mills in which the corners of the outer peripheral cutter and the bottom cutter are chamfered with squares or eight chamfers, cutting speeds of 1.
When cutting is performed under harsh conditions of 00 ml1/min or more, chipping and other defects tend to occur at the boundary between the outer edge, bottom edge, and corner, making it impossible to obtain a tool life that is sufficient for practical use. was there.

The present invention was made against the background of the above circumstances, and its purpose is to reduce chipping of the cutting edge even when high-speed cutting is performed on high-hardness materials using CBN sintered tips. An object of the present invention is to provide an end mill that has a practically sufficient life.

Means for Solving the Problems In order to achieve this object, the inventors of the present application have made various studies, and for example, in the 8-chamfering process described above, the 8-chamfered portion 24 of the corner, the peripheral cutter 20, and the bottom cutter 22 are Center of curvature is 0 for smooth connection! It is necessary to accurately align the rotation center 01 and the rotation center 01, but the alignment work is extremely troublesome and difficult. , the rotation angle P is (180'-C) (C is the outer peripheral blade 20 and the bottom blade 2
Intersection angle with 2: see Figure 11],
A margin angle range Q, , Q in which 8 chamfers are not performed on the outer peripheral blade 20 side and the bottom blade 22 side, respectively.

It is normal to set the center of curvature at 0.
! From outer peripheral blade 20. 11.1 respectively from the position where the perpendicular line is drawn down to the bottom blade 22. It was discovered that a sharp portion is formed at a position that is a distance t toward the corner, and that this sharp portion is a major cause of chipping of the cutting edge.

In addition, when a corner is chamfered, a larger sharp part will be created at the boundary between the corner and the outer edge and the bottom edge than in the case of the 8-chamfer described above, so the chipping of the cutting edge will be more noticeable. be.

The present invention was made based on this knowledge, and its gist is that a sintered body of cubic boron nitride is provided on at least the surface of the tip of a tool body that is driven to rotate around its axis. An end mill is provided with a chip having a peripheral edge and a bottom edge formed thereon, the tip having a peripheral edge and a bottom edge formed therein, and having eight chamfers on the corners of the outer edge and the bottom edge, and at least the outer edge of the bottom edge. In this case, a first bottom blade having a cutting angle of 0° or more is provided on a tangent to the R of the eight chamfers.

In addition, when machining cutting edges on the outer periphery and the bottom of the tip, such an end mill (a) forms linear outer periphery and bottom edges at predetermined cutting angles on the outer periphery and the bottom, respectively; (b) centering around a rotation center set at a position spaced apart from the bottom blade by a dimension larger than the radius of curvature of the eight chamfered portions to be formed at the corners of the outer peripheral blade and the bottom blade; While pressing the grinding plane of the rotary grinding wheel against the corner, the end mill and its rotary grinding wheel are rotated relative to each other, and at the same time, the corner is chamfered with 8 chamfers, and at the same time, the cutting angle becomes 0゛ or more at least on the outer peripheral side of the bottom force. It can be suitably manufactured by a manufacturing method including a step of forming a first bottom blade.

Function and Effect of the Invention In such an end mill, since the first bottom cutter is provided on the tangent to the radius of the 8-chamfered corner, the first bottom cutter and the corner are smoothly connected, and the boundary There will be no sharp edges. In addition, if this first bottom blade is formed only on the outer peripheral side of the bottom blade, in other words, if the cutting angle of the first bottom blade is smaller than the cutting angle of the bottom blade, the bottom blade and the first bottom blade A sharp part is produced at the boundary with the blade, but since the cutting angle of the first bottom blade is 0° or more, the sharp part does not protrude beyond the corner side of the first bottom blade in the axial direction of the end mill. , Substantive cutting operations are hardly performed except for the plunge processing in which cutting is performed by advancing the end mill in the axial direction.

Therefore, even if the CBN sintered chip has relatively low toughness, the occurrence of defects such as chipping and edge chipping is reduced, and for example, compared to hard materials with HIC of 60 or higher,
Even when cutting at high speeds of 0 am/s+in or higher, a practically sufficient tool life can be obtained. Note that if the length of the first bottom blade is too short, sufficient chipping prevention effect cannot be obtained, so the length is set to 0.5.
It is desirable to set it to m or more.

On the other hand, in the above-described manufacturing method, in order to simultaneously form the first bottom blade with eight chamfers, the center of rotation is set at a position separated from the bottom blade by a dimension larger than the radius of curvature of the eight chamfers, and An end mill and a rotary grinding wheel,
It is only necessary to relatively rotate the rotary grinding wheel to a position where the grinding plane thereof is inclined by the same angle as the cutting angle of the first bottom blade with respect to a plane perpendicular to the axis of the end mill. In this case, as the rotary grinding wheel rotates relative to the end mill, the grinding process gradually progresses from the outer circumference of the bottom blade toward the inner circumference.
Even if the center of rotation is slightly shifted in the direction away from the bottom blade, if the relative rotation range between the rotary grinding wheel and the end mill is constant, the length of the first bottom blade will only change, and the rotary grinding There is no problem such as interference between the grindstone and the bottom blade. Therefore, the rotation center position in the direction away from the bottom blade is at least larger than the radius of curvature of the eight chamfers from the bottom blade, preferably the length of the first bottom blade is 0.5
It is sufficient to set the dimension to be equal to or larger than m, and high accuracy is not necessarily required when aligning the center of rotation in the direction away from the bottom cutter, in other words, in the direction substantially parallel to the axis of the end mill.

As mentioned above, since it is relatively easy to align the center of rotation in the direction away from the bottom blade, it is now possible to focus on aligning the center of rotation in the direction away from the peripheral blade. , the alignment accuracy is improved accordingly, and it becomes possible to reduce the margin angle range in which 8-chamfering is not performed in order to prevent interference between the rotary grinding wheel and the peripheral blade. In this way, the sharp portion that occurs at the boundary between the eight chamfers and the peripheral blade can be reduced, and chipping, chipping, and other defects on the peripheral blade side can be more effectively prevented. Also, on this outer peripheral edge side,
Eight chamfers are performed by rotating the rotating grinding wheel relative to a position spaced from the pre-formed peripheral blade by a dimension larger than the radius of curvature of the eight chamfers, and the peripheral blade is ground until the desired cutting angle is achieved. By machining it, it can be smoothly connected to the eight chamfered parts.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a plan view of an end mill that is an embodiment of the present invention. Such an end mill 50 includes a tool body 5 made of a carbide material that is rotated around an axis via a shank 52.
4, and a triangular tip 56 fixed to the tip of the tool body 54. As is clear from FIGS. 2 to 4, approximately half of the tip of the tool body 54 is cut out by a notch 58, and a chip room is formed in that part. A triangular tip seat 60 corresponding to the tip is provided. The chip 56 is made by sintering CBN 64 on a plate-shaped carbide material 62 at high temperature and pressure using metal or ceramic as a binder, and is brazed to the chip seat 60 on the carbide material 62 side. . The thickness of the CBN 64 is about 0.5 to 0.71.

As is clear from FIGS. 3, 4, and 5, the tip 56 has an outer peripheral portion, that is, an end mill 50
A straight peripheral blade 66 is provided on a side substantially parallel to the axis of the end mill 50 located on the outer peripheral side thereof, and a straight peripheral blade 66 is provided on a side substantially perpendicular to the axis located at the bottom of the end mill 50, that is, on the tip side of the end mill 50. A first bottom blade 68 and a second bottom blade 70 are provided. The peripheral blade 66 has a cutting angle of 1. It is formed with a second angle α1, and a honing angle θ1. Honing width W,
It has been honed. In addition, the first bottom blade 68
is the entering angle of 2. The second bottom edge 70 is formed with a second angle α2.
is 1 for the cutting angle. Second angle α.

The first bottom cutter 68 and the second bottom cutter 70 have a honing angle θ2. Honing width W! It has been honed. The corner of the outer circumferential cutter 66 and the first bottom cutter 68 has a radius of curvature r in order to prevent defects such as cutouts.

Eight chamfered portions 72 having a second angle α2 equal to that of the first bottom blade 68 are provided, and are smoothly connected to the first bottom blade 68. Specifically, the first bottom blade 68 is provided on a tangent to the R of the eight-chamfered portion 72 at the connection portion between the eight-chamfered portion 72 and the first bottom blade 68 .

The radius of curvature r is set at 0°3 to 0.6 in order to obtain sufficient chipping prevention effect and not to damage the processed shape.
It is set within a range of about M. Note that the honing shapes of the outer circumferential cutter 66, bottom cutter 68, and 70 are shown only in FIGS. 3 and 4, respectively, and are omitted in other drawings. Although not shown, the eight chamfered portions 7
2 is also subjected to a honing process that smoothly connects to the honing of the outer circumferential cutter 66 and the first bottom cutter 68.

The first bottom blade 68 has 0.51 TII on the outer circumferential side of the bottom! The second bottom blade 70 is provided over a length dimension of
is provided continuously to the first bottom blade 68 on the inner peripheral side of the first bottom blade 68. Further, the cutting angle 2 is smaller than the cutting angle, and the first bottom blade 68 is perpendicular to the axis of the end mill 50 or protrudes toward the tip side as it goes toward the outer circumference. has been done. Further, the second angles α2 and α can be set as appropriate, but depending on their size, there may be a sixth angle between the second face 74 of the first bottom blade 68 and the second face 76 of the second bottom blade 70. (a), (b), (
C) A ridgeline of the shape shown is created. Figure 6 (a
), (b).

(C) are α2>α1. α2=α8. α,〈α
, is the case.

Next, a method for manufacturing such an end mill 50 will be explained.

First, a carbide round bar is cut to a predetermined length to form a shank 52.
Notch 58. While manufacturing the tool body 54 by forming the chip seat 60 and the like, a chip material made by sintering CBN 64 on a carbide material 62 is cut into an appropriate size by wire-cut electrical discharge machining or the like, and the cut-out chip 56 ( At this stage, the cutting edge has not yet been formed).
Braze to 0. Thereafter, the outer peripheral edge 66 and the second bottom edge 70 are cut at predetermined cutting angles by using a diamond grindstone or the like on the outer periphery and bottom of the tip 56, respectively.5. 3, second angle α1. α, and a honing angle θ6. Honing is performed at θ2, honing width W+, and Wt. The solid line in FIG. 7 is a plan view showing the corner portion of the chip 56 in this state. Note that the second bottom blade 70 corresponds to a bottom blade formed at the bottom of the chip 56 prior to the first bottom blade 68.

Next, the end mill 50 is attached to the grinding machine shown in FIG. 8, and the center of curvature is set to 0. The positioning is performed so that it coincides with the rotation center 01 of the rotary table IO. As is clear from FIG. 7, the center of curvature O8 is
The distance d1 from the outer peripheral cutter 66 is set to be the same as the radius of curvature r of the eight chamfered portions 72 to be formed, and the alignment is mainly performed using the X-axis table 26 that moves the end mill 50 in a direction perpendicular to the axis. This is done by the adjustment knob 30. Also, the center of curvature is 0. The distance d2 from the second bottom blade 70 is set to be larger than the radius of curvature r, and the alignment is mainly performed by the adjustment knob 32 of the Y-axis table 28 that moves the end mill 50 in a direction parallel to the axis. It will be done.

On the other hand, the rotary grinding wheel 16 has its axis at the second angle α2.
Only the plane of the rotary table 10, that is, the end mill 50
It is adjusted so as to be inclined with respect to the movement plane of , and in that state, it is rotated and moved downward in FIG. As a result, the 0-rotation grinding paper stone 16 on which the corner of the chip 56 is ground is tilted by the same angle as the second angle α2 as described above, so that the rotation center 0. The separation distance from the tip 56 is determined based on the position of contact with the upper surface of the tip 56, that is, the portion where the outer peripheral blade 66 and the second bottom blade 68 are formed.

Then, in this state, rotate the rotary table 10 to the rotation center 0. By rotating it around, the grinding position of the chip 56 by the rotary grinding wheel 16 is changed, and eight chamfers are chamfered on the entire corner. The rotational angle P of the end mill 50 in the angular range to be ground by the rotary grinding wheel 16, that is, around the center of curvature O3, is set as shown in FIG. As shown in FIG.
is set between an angular position that is inclined by the same angle as the cutting angle 2 in plan view with respect to a plane S perpendicular to the axis m of the end mill 50. As a result, eight chamfers with a radius of curvature r and a second angle αZ are performed around the center of curvature 03 within the range of the rotation angle P shown in FIG. 7, and an eight-chamfered portion 72 is formed. Above curvature center 0. corresponds to the center of rotation when performing 8-chamfering.

Further, the above-mentioned 8-chamfering process is performed from the middle position of the corner toward the outer peripheral blade 66 side and the second bottom blade 70 side, but the curvature center 0. Since the distance d2 from the second bottom blade 70 is set to be larger than the radius of curvature r, when grinding is performed toward the second bottom blade 70, the second bottom blade 70 The outer circumferential side portion of is gradually ground from the outer circumferential side toward the inner circumferential side. As a result, the outer circumferential portion of the second bottom blade 70 has a cutting angle of .2 and a second angle of α.
Two first bottom blades 68 are formed. The length of the first bottom blade 68 is defined by the distance d2 from the second bottom blade 70 of the center of curvature O1, and the distance d2 is set such that the length is 0.5 an or more. predetermined. A point M line in FIG. 7 indicates the eight-chamfered portion 72 and the first bottom blade 68 formed by the eight-chamfering process described above.

Here, the alignment of the above-mentioned separation dimension dt is mainly performed by the adjustment knob 32 of the Y-axis table 28, but even if the alignment is slightly out of order, it will only change the length of the first bottom blade 68. , the rotary grinding wheel 16 and the second bottom blade 70
There is no problem such as interference between the two. Therefore, when aligning the distance d2, it is only necessary to adjust the length of the first bottom blade 68 to be at least 0.5 m, and high alignment accuracy is not necessarily required. It's not a thing.

Moreover, in this way, the center of curvature in the direction away from the second bottom blade 70 is 0. Because alignment is relatively easy,
It becomes possible to concentrate attention on the work of positioning the center of curvature O1 in the direction away from the peripheral blade 66, that is, the work of adjusting the separation dimension d, and the positioning accuracy is improved.

Therefore, in order to prevent interference between the rotary grinding wheel 16 and the outer peripheral blade 66, it is possible to reduce the allowance angle range Q in which the 8-chamfer is not performed, and the 8-chamfer part 72 and the peripheral blade 6
6 can be made smaller.

Through the above process, the end mill 50 with the above-mentioned cutting edge shape is
is manufactured, but in such an end mill 50, 8
The chamfered portion 72 and the first bottom blade 68 are smoothly connected, and the sharp portion that occurs at the boundary between the eight chamfered portions 72 and the outer circumferential blade 66 is also very small.
A sharp portion is formed at the boundary with the bottom blade 70 based on the difference in cutting angle 2 and 2, but the cutting angle 2 of the first bottom blade 68 is 0゛ or more and its length dimension is is set to be 0.5 mm or more, so the sharp portion does not protrude in the axial direction of the end mill 50 beyond the corner side of the first bottom blade 68, and there is almost no substantial cutting action except for plunge machining. Not done. Therefore, even with the insert 56 made of CBN64, which has excellent features such as being able to perform high-speed and high-precision machining of high-hardness materials, but has a problem of relatively low toughness, chipping and edge chipping are common. The occurrence of chipping is greatly reduced, and a practically sufficient tool life can be obtained.

Incidentally, the end mill of the present invention (invention product 1. II,
III) and a conventional end mill without a first bottom cutter (
When milling was performed using a conventional product) under the following cutting conditions, the results shown in Table 2 were obtained. The shape of the end mill is 10 m in diameter and 55 nn in total length for both the inventive product and the conventional product.

The length of the shank is 45 meters, the length of the outer edge of the tip and the length of the bottom edge are each 5 meters, and the specifications of the shape of the edge are as shown in Table 1. In Table 1, the units of the honing width W, , W, and the length and radius of curvature r are all -, and the second angle of the eight chamfers is equal to the second angle of the bottom blade. In addition, the durable length in Table 2 is the length that can be processed until the wear width (3) of the second surface reaches 0.15 m or the blade breaks, taking into consideration re-grinding.

Concave 11E cutting speed: 100 aui/s+in feed jo, 03
mm/blade Cutting length: 350IIIll Cutting method:
Groove cutting Depth of cut: 0.5mm Cutting oil Nidry Work material: Die steel 5KDI 1 (HIC60) Machine:
Machining center main shaft movable crab 18.5kW As is clear from these results, the tool life of the conventional product is relatively short due to chipping of the blade near the boundary between the 8-chamfer section and the bottom blade, whereas the tool life of the present product is relatively short. Since the part and the first bottom edge are smoothly connected, the tool life is relatively long, especially in the products (■) and (■) of the present invention where the length dimension of the first bottom edge is 0.5 ms or more. It can be seen that the cause of tool life is the second wear at the corner boundary, and the tool life is significantly improved. In addition, the finished surface had a good specularity and a surface roughness of ln or less.

Although one embodiment of the present invention has been described above in detail based on the drawings, the present invention can also be implemented in other embodiments.

For example, the tip 56 is made of CBN64 on a carbide material 62.
Although the chip 56 is sintered, it is also possible to use a chip made of only a sintered body of CBN, and the shape of the chip 56 can be changed as appropriate, such as a square shape.

Further, in the embodiment described above, the first
Although the bottom blade 68 is formed, it is also possible to grind all the second bottom blades 70 to leave only the first bottom blade 68.

Furthermore, in the embodiment described above, a grinding machine is used that performs eight chamfers by rotating the end mill 50 around the rotation center O1, but it is also possible to perform eight chamfers by rotating the rotary grinding wheel 16 around the rotation center O3. is also possible.

Although the 8-chamfering method in the above embodiment is one means for suitably manufacturing the end mill of the present invention, the end mill of the present invention can be manufactured by performing 8-chamfering by other methods and forming the first bottom blade. There is no harm in doing so.

Although other examples are not provided, the present invention can be implemented with various modifications and improvements based on the knowledge of those skilled in the art.

[Brief explanation of drawings]

FIG. 1 is a plan view of an end mill that is an embodiment of the present invention. 2 is a plan view showing the tip of the end mill shown in FIG. 1. FIG. 3 is an end view of the tip of the end mill of FIG. 1. FIG. FIG. 4 is a side view of FIG. 3. Figure 5 is the first
It is a figure explaining the cutting edge shape of the end mill of a figure. FIG. 6 is a view showing the second surface of the bottom blade of the end mill shown in FIG. 1. FIG. 7 is a plan view showing a portion of the corner in which the outer peripheral cutter and the bottom cutter are formed in the end mill of FIG. 1. FIG. 8 is a plan view showing an example of a grinding machine for chamfering eight corners in FIG. 7. FIG. 9 is a plan view showing the rotational position of the outer peripheral blade when performing eight-chamfering with the grinding machine of FIG. 8. FIG. FIG. 10 is a plan view showing the rotational position of the bottom blade when chamfering 8 chamfers by the grinding machine shown in FIG. 8. FIG. 11 is a plan view showing a portion of a corner of a cutting blade of a conventional end mill. 16: Rotary grinding wheel 38: Grinding plane 50: End mill 54: Tool body 56: Tip 64:
Cubic boron nitride 66: Peripheral edge 68: First bottom edge 70: Second bottom edge (bottom edge) 12: 8 Chamfered part 0, : Center of curvature (center of rotation) ``: To radius of curvature - To: To 3: Depth angle

Claims (2)

[Claims] (1) A tip having a sintered body of cubic boron nitride on at least the surface and having a peripheral edge and a bottom edge is fixed to the tip of the tool body which is driven to rotate around the axis. The end mill has an R chamfer on the corner of the outer peripheral cutter and the bottom cutter, and at least on the outer peripheral side of the bottom cutter, a cutting angle of 0° or more is on the tangent to the R of the R chamfer. An end mill characterized by being provided with a first bottom blade. (2) A method for manufacturing an end mill in which a tip having a sintered body of cubic boron nitride on at least the surface is fixed to the tip of a tool body that is driven to rotate around an axis, the tip When machining cutting edges on the outer periphery and bottom of the blade, forming linear outer periphery and bottom edges at predetermined cutting angles on the outer periphery and the bottom edge, respectively; While pressing the grinding plane of the rotary grinding wheel against the corner, the end mill and the grinding wheel are pressed around a rotation center set at a position spaced apart from the bottom by a dimension larger than the radius of curvature of the R-chamfered portion to be formed at the corner. It is characterized by including the step of relatively rotating the rotary grinding wheel and performing R-chamfering on the corner, and at the same time forming a first bottom cutter having a cutting angle of 0° or more on at least the outer peripheral side of the bottom cutter. A method of manufacturing an end mill.