JP2017019083A - End mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an end mill being small in a torsion angle, and also easily discharging chips.SOLUTION: This end mill comprises a blade part 10 having a plurality of (cutting edges 10a composed of a tip blade 12a formed in a tip part 12 and a side surface blade 11a formed in a side surface part 11 and continuously extending from the tip blade) in the circumferential direction. When viewing the end mill from the tip side, on the respective side surface blades, a torsion angle θ is set so that an angle corresponding to dislocation in the circumferential direction between the root side end and the tip side end of the side surface blade becomes 90° or less. A groove (g) is respectively formed in a plurality of different positions in the extension direction of the cutting edge on an outer surface of the respective cutting edges. A curve of connecting mutual adjacent grooves in the circumferential direction on the outer surface of a blade part is connected in order in the rotational direction of the end mill in the circumferential direction, and thereby, a position in the plurality of grooves is set in the extension direction of the respective cutting edges so as do draw a spiral curve of moving to the root side from the tip side.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an end mill. The end mill is a cutting having a cylindrical blade portion provided with “a cutting edge formed by a tip blade formed at the tip portion and a side blade formed on the side surface portion and continuously extending from the tip blade”. Refers to the tool (milling).

  The end mill has a side blade and a tip blade. Accordingly, for example, the side surface of the hole formed in the workpiece can be sharpened by using the side blade of the end mill, and the bottom surface of the hole can be cut by using the end blade of the end mill. . Conventionally, various end mills have been developed according to cutting conditions such as the shape of the cutting surface of the workpiece and the material of the workpiece (for example, see Patent Document 1).

JP 2014-231115 A

  One of the important specifications when designing an end mill is “an angle formed between the axis of the end mill and the extending direction of the side blade” (hereinafter referred to as “twist angle”). When a twist angle (> 0) is given, a circumferential force (torsion torque) and an axial force (thrust force) act on the end mill during cutting.

  As the helix angle increases, the circumferential force decreases, while the axial force increases. This axial force acts as a force for pulling the end mill downward from a member (chuck or the like) that fixes the end mill, and at the same time, acts as a force for lifting the workpiece. Therefore, when the torsion angle is large, particularly when the vertical rigidity of the workpiece is relatively small, vibration / resonance (so-called “chatter”) is likely to occur in the workpiece.

  The present inventor considers using an end mill having a plurality of cutting edges when cutting a recess having a desired shape on the upper surface of a resin member having a relatively thin shape. The rigidity of the resin member in the vertical direction is very small. Actually, when an end mill having a plurality of cutting edges having a relatively large twist angle (for example, 30 ° or more) is used to process the resin member, it is easy for the resin member to be “chattered”. .

  Therefore, the present inventor considers using an end mill having a plurality of cutting edges having a relatively small twist angle. Specifically, the present inventor has determined the twist angle as follows: “When the end mill is viewed from the tip end side in the axial direction of the end mill, an angle corresponding to a circumferential shift between the root side end and the tip end of the side blade is set. It was set to a small value within a range where the condition of “90 ° or less” was satisfied. This point will be described later in detail (see FIGS. 2 and 3).

  When the resin member was actually processed using an end mill having a small helix angle within a range where the above conditions were satisfied, “chatter” hardly occurred. However, in this case, a new problem has arisen that chips generated by cutting are difficult to be discharged. This is considered to be due to the fact that when the twist angle is small, the force for lifting the chips upward (the chip lifting action) becomes small.

  From the above, an end mill with a small twist angle, which is easy to discharge chips, has been desired. That is, an object of the present invention is to provide an “end mill with a small twist angle, in which chips are easily discharged”.

  The end mill according to the present invention includes a plurality of “cutting blades formed of a tip blade formed at the tip portion and a side blade formed on the side surface portion and continuously extending from the tip blade” in the circumferential direction. A blade part, and a shank part disposed coaxially with the blade part on a base side opposite to the tip part of the blade part.

  The twist angle of this end mill is “when the end mill is viewed from the tip end side in the axial direction of the end mill, the angle corresponding to the circumferential shift between the root side end and the tip end of the side blade is 90 ° for each side blade. It is set to a small value within a range where the condition “below” is satisfied.

  The feature of the end mill according to the present invention resides in that grooves are formed on the outer surface of each cutting edge at a plurality of different positions in the extending direction of the cutting edge. According to this, compared with the case where such a groove | channel is not formed, chips can be finely divided. Accordingly, chips are easily discharged.

  In this end mill, the extending direction of each side blade is such that when the end mill is viewed from the axial base side of the end mill, the circumferential position of the side blade is directed from the axial base side to the axial tip side. It is preferable that the end mill is inclined with respect to the axis of the end mill in the direction of movement in the rotation direction of the end mill. Thereby, at the time of cutting, a force (a chip lifting action) for lifting the chips to the axial base side (that is, upward) works. That is, the chips move in the respective recesses formed between the side blades adjacent in the circumferential direction from the axial front end side toward the axial base side.

  In addition, a spiral shape that moves from the axial base side to the axial tip side by sequentially connecting a curve connecting the grooves adjacent in the circumferential direction on the outer surface of the blade portion in the circumferential direction in the rotational direction of the end mill. It is preferable that the positions of the plurality of grooves in the extending direction of the respective cutting edges are set so that the curved line is drawn.

  According to this, at the time of cutting, with the rotation of the end mill, the first cutting edge after a part of the first cutting edge (a part between adjacent grooves) contacts a certain part of the workpiece. When a part of the second cutting edge next to (the part between the adjacent grooves) is next in contact with the same part of the workpiece, the axial position of the part of the second cutting edge is the first position. It is located on the tip side in the axial direction with respect to a part of the cutting edge. Therefore, during cutting, when the respective recesses formed between the side blades adjacent to each other are moved from the axial tip side toward the axial base side, the chips are moved to the axial base side (that is, upward). E) Easy to move. As a result, chips generated due to the cutting of the side blades are more easily discharged.

  In addition, in this end mill, when the tip portion of the blade portion is viewed from the tip end side in the axial direction of the end mill, each tip blade is operated in the circumferential direction from the radially inner side toward the radially outer side. It preferably extends while bending in a direction opposite to the rotational direction of the hour.

  According to this, each recessed part formed between the front-end blades adjacent in the circumferential direction also extends while bending in the opposite direction in the circumferential direction from the radially inner side toward the radially outer side. These recesses can be paths when chips move from the radially inner side to the radially outer side. That is, the path when the chips move extends from the radially inner side to the radially outer side while bending in the opposite direction in the circumferential direction. Accordingly, during cutting, when the respective concave portions formed between the adjacent cutting edges are moved from the radially inner side toward the radially outer side, the chips are likely to move radially outward. As a result, chips generated due to the cutting of the leading edge are more easily discharged.

  In the end mill, each groove is preferably a V-shaped groove. If the width of each groove in the extending direction of the cutting edge is too large, the total length in the extending direction of the cutting edge that can contribute to the cutting becomes too small, so that the efficiency of cutting can be greatly reduced. On the contrary, if the width of each groove in the extending direction of the cutting edge is too small, the above-mentioned “action of finely dividing the chip” is difficult to be exhibited, and therefore the chip dischargeability can be greatly reduced. . In this regard, if the groove shape is V-shaped as in the above configuration, the groove width in the extending direction of the cutting edge can be easily set within an appropriate range. That is, it becomes easy to maintain both the cutting efficiency and the chip dischargeability satisfactorily.

  Specifically, in this end mill, the ratio of the length of the side blades in the axial direction to the outer diameter of the blade portion (elongation ratio) is greater than 2.0, and the twist angle of each side blade is 15. It can be designed to be less than 0 ° and the number of cutting edges to be greater than 15.

  In this specification, since the slenderness ratio is considerably large, the end mill becomes considerably slender. Generally, as the slenderness ratio increases, the rigidity of the end mill as a whole decreases. As the rigidity of the end mill decreases, the roughness of the cut surface of the workpiece also deteriorates. In this regard, as described above, when the resin member is processed, the cutting resistance acting on the end mill is significantly smaller than when a material having high hardness such as metal is processed. Therefore, when the resin member is processed, even if the slenderness ratio is larger than 2.0 (thus, the rigidity of the end mill is low), the roughness of the cutting surface of the resin member can be maintained well.

  In addition, the twist angle is very small. Therefore, as described above, even if the resin member is processed, “chatter” hardly occurs. Furthermore, the number of cutting edges is very large. In general, as the number of cutting edges increases, the cutting surface roughness of the workpiece improves, while the chip discharge performance decreases. In this regard, the reduction in chip discharge is compensated by the formation of the groove. Therefore, when processing a resin member, even if the number of cutting edges is more than 15, the roughness of the cutting surface of the resin member can be satisfactorily maintained without deteriorating chip discharge.

  In addition, the end mill can be designed such that the ratio of the outer diameter of the shank portion to the outer diameter of the blade portion is less than 0.7. The shank portion is a portion that is actually held (gripped) by the holding member when holding the end mill using a holding member such as a chuck.

  In these specifications, the outer diameter of the shank portion is considerably reduced, so that the rigidity of the end mill as a whole is lowered, and the roughness of the cut surface of the workpiece tends to deteriorate. In this regard, as described above, when processing a resin member having a low cutting resistance, the roughness of the cutting surface of the resin member is good even if the outer diameter of the shank portion is small (thus, the rigidity of the end mill is low). Can be maintained.

  In addition, when the outer diameter of the shank portion is small, a holding member such as a chuck can be downsized. Therefore, when a relatively deep recess is cut on the upper surface of the workpiece, the holding member is less likely to contact the side surface of the recess. Therefore, the freedom degree of the shape of the recessed part processed with an end mill can be raised.

It is the front view and end surface figure of the end mill which concern on embodiment of this invention. It is an enlarged view of the blade part in the front view of FIG. It is an enlarged view of the front-end | tip part in the end elevation of FIG.

  Hereinafter, an end mill 100 according to an embodiment of the present invention will be described with reference to the drawings.

(shape)
As shown in FIG. 1, the end mill 100 generally has a stepped columnar shape in which a large-diameter blade portion 10 and a small-diameter shank portion 20 are disposed coaxially and integrally with an axis CL. Presents. The shank portion 20 is a portion that is actually held (gripped) by the holding member when the end mill 100 is held using a holding member such as a chuck. Hereinafter, for convenience of explanation, the z-axis positive direction side and the z-axis negative direction side in the axial center CL direction are referred to as “tip side” and “root side”, respectively.

  The blade portion 10 includes a cylindrical side surface portion 11 and a front end portion 12 that protrudes toward the front end side of the side surface portion 11. As shown in FIG. 1 and FIGS. 2 and 3 which are enlarged views of FIG. 1, a plurality of cutting blades 10 a extending from the side surface portion 11 to the tip portion 12 are formed on the surface of the blade portion 10. Yes. In the end mill 100, 24 cutting edges 10a are formed. Exactly speaking, of the 24 cutting edges 10a, there are eight that extend to the tip of the tip 12 and extend to the middle of the tip 12 but extend to the tip of the tip 12. There are 16 that are not. The number of cutting edges 10a may be 15 or less, but is preferably larger than 15. Furthermore, it is preferably larger than 20.

  Specifically, each of the cutting blades 10a includes “a tip blade 12a formed on the tip portion 12 and extending in the radial direction” and “a tip blade 12a formed on the side surface portion 11 and continuously extending from the tip blade 12a in the direction of the axis CL. Side blades 11a ". Here, each tip edge 12a can also be defined as a “part visible when the end mill 100 is viewed from the tip side” in the corresponding cutting edge 10a.

  The extending direction of each side blade 11a is such that when the end mill 100 is viewed from the base side, the circumferential position of the side blade 11a moves in the rotational direction (during cutting) of the end mill 100 from the root side toward the tip side. Further, it is inclined with respect to the axial center CL direction. Thereby, at the time of cutting, the force which lifts up a chip | tip (chip lift action) acts. Hereinafter, as shown in FIG. 2, an angle formed by the axis CL direction and the extending direction of the side blade 11 a is defined as “twist angle θ”.

  When the end mill 100 is viewed from the front end side, the torsion angle θ is “the angle α corresponding to the circumferential shift between the root side end of the side blade 11a and the front end is 90 ° or less” for each side blade 11a. It is designed to be.

  Specifically, for example, when focusing on one side blade 11a shown with fine dots on the outer surface in FIG. 2, the root side end and the tip side end of the side blade 11a are “a "And" b ". As can be understood from FIG. 3, the angle α corresponding to the deviation in the circumferential direction between the root end “a” and the tip end “b” of the side blade 11 a is 90 ° or less. The same applies to the side blades 11a other than the side blade 11a. For each side blade 11a, the twist angle θ may or may not change depending on the position in the axial center CL direction. The transition of the twist angle θ with respect to the position of the side blade 11a in the axial center CL direction is the same for any side blade 11a.

  As shown in FIG. 3, when the tip portion 12 of the blade portion 10 is viewed from the tip side, each tip blade 12 a is rotated in the circumferential direction from the radially inner side to the radially outer side when the end mill 100 is operated in the circumferential direction ( It extends while turning in the opposite direction to the thick arrow in FIG. The radially outer end of each tip blade 12a is continuous with the tip end of the corresponding side blade 11a.

  As shown in FIG. 2, each tip blade 12 a includes “a flat portion 12 aa corresponding to a flat tip surface” and “an arcuate corner portion 12 ab connecting the flat portion 12 aa and the tip end of the side blade 11 a”. It consists of. That is, the end mill 100 is a radius end mill having a flat tip and a rounded corner.

  As shown in FIGS. 2 and 3, grooves g are formed on the outer surface of each cutting edge 10a (= side edge 11a + tip edge 12a) at a plurality of different positions in the extending direction of the cutting edge 10a. Yes. In addition, as can be understood from FIG. 2, a curve connecting the circumferentially adjacent grooves g on the outer surface of the blade portion 10 (particularly, the side surface portion 11) is sequentially connected in the rotational direction of the end mill 100 in the circumferential direction. A spiral curve moving from the tip side to the root side is drawn. That is, the amount of deviation of the position of the groove g adjacent in the circumferential direction in the axis line CL direction is constant over the entire outer surface of the side surface portion 11.

  With reference to FIG. 1, the length of the blade portion 10 in the axial center CL direction is L1, the length of the shank portion 20 in the axial center CL direction is L2, and the side surface portion 11 of the blade portion 10 is in the axial center CL direction. The length is L3, the outer diameter of the blade part 10 is D1, and the outer diameter of the shank part 20 is D2.

  When the slenderness ratio is defined as “L3 / D1”, in the end mill 100, the slenderness ratio may be 2.0 or less, but is preferably larger than 2.0. When the outer diameter ratio is defined as “D2 / D1,” the outer diameter ratio may be 0.7 or more, but is preferably less than 0.7. Furthermore, the twist angle θ may be 15 ° or more as long as the above-described condition “α ≦ 90 °” is satisfied, but is preferably less than 15 °.

  As described above, the end mill 100 is a radius end mill having a so-called “right blade / right helix angle”. “Right blade (left blade)” refers to an end mill that rotates clockwise (counterclockwise) when the end mill is viewed from the base side. “Right helix angle (left helix angle)” refers to the end mill. When viewed from the root side, each side blade is tilted with respect to the axial direction so that the circumferential position of each side blade moves in the clockwise direction (counterclockwise direction) from the root side toward the tip side. Refers to the state of being. The end mill 100 may be an end mill having a “left blade / left helix angle”.

(Material)
In the case of machining a workpiece having a relatively high hardness such as a steel material, the end mill 100 is preferably made of high-speed steel, superhard material, or the like, although it is expensive. Moreover, you may be comprised with structural carbon steel, alloy tool steel, etc. On the other hand, in the case of processing a workpiece made of a synthetic resin having a relatively small hardness such as EVA resin (ethylene / vinyl acetate copolymer resin), the end mill 100 is made of a high-speed steel, superhard material, or the like. It can be made of cheaper maraging steel or the like.

(End mill manufacturing method)
The end mill 100 can be manufactured by so-called “shaving” in which a constituent material of an end mill is shaved and shaped using a grindstone or the like. The end mill 100 can be shaped and manufactured using a 3D printer based on the three-dimensional shape data (3D CAD data) of the end mill 100.

(Action / Effect)
Hereinafter, the operation and effect of the end mill 100 according to the embodiment of the present invention will be described.

(1) In the end mill 100, grooves g are formed on the outer surface of each cutting edge 10a (= side edge 11a + tip edge 12a) at a plurality of different positions in the extending direction of the cutting edge 10a (FIG. 2 and FIG. 2). 3). Thereby, compared with the case where such a groove | channel is not formed, chips can be finely divided. Accordingly, chips are easily discharged.

(2) In the end mill 100, the extending direction of each side blade 11a moves in the rotational direction of the end mill 100 from the root side toward the tip side when the end mill 100 is viewed from the root side. It is inclined with respect to the axis CL (see FIG. 2). Thereby, at the time of cutting, a force (chip lifting action) for lifting the chips to the root side (that is, upward) works. That is, the chips move from the tip side toward the root side through the respective recesses formed between the side blades 11a adjacent in the circumferential direction.

  In addition, a spiral curve that moves from the root side to the tip side is drawn by sequentially connecting the curves connecting the circumferentially adjacent grooves g on the outer surface of the blade portion 10 in the rotational direction of the end mill 100 in the circumferential direction. In addition, the positions of the plurality of grooves g in the extending direction of each cutting edge 10a are set. As a result, during cutting, as the end mill 100 rotates, a portion of the first cutting edge 10a (a portion between adjacent grooves g) comes into contact with a certain portion of the workpiece to be cut. When a part of the second cutting edge 10a adjacent to the blade 10a (the part between the adjacent grooves g) is next in contact with the same part of the workpiece, the axial position of a part of the second cutting edge 10a Is located on the tip side with respect to a part of the first cutting edge 10a. Accordingly, during cutting, when the respective recesses formed between the side blades 11a adjacent to each other are moved from the tip side toward the root side, the chips are easily moved toward the root side (that is, upward). Become. As a result, chips generated due to the cutting of the side blade 11a are more easily discharged.

(3) In the end mill 100, when the tip portion 12 of the blade portion 10 is viewed from the tip side, each tip blade 12a has a rotational direction when the end mill 100 is operated in the circumferential direction from the radially inner side to the radially outer side. It extends while bending in the opposite direction (see FIG. 3). As a result, each recess formed between the tip blades 12a adjacent in the circumferential direction also extends while bending in the opposite direction in the circumferential direction from the radially inner side to the radially outer side. These recesses can be paths when chips move from the radially inner side to the radially outer side. That is, the path when the chips move extends from the radially inner side to the radially outer side while bending in the opposite direction in the circumferential direction. Accordingly, during cutting, when the chips move from the radially inner side to the radially outer side, the chips are likely to move radially outward. As a result, chips generated due to the cutting of the leading edge are more easily discharged.

(4) In the end mill 100, each groove g is a V-shaped groove (see FIGS. 2 and 3). Thus, by setting the width of the groove g in the extending direction of the cutting edge 10a within an appropriate range, the total length in the extending direction of the cutting edge 10a that can contribute to cutting is adjusted to an appropriate range. In addition, the “action of finely dividing the chips” is easily exhibited appropriately. That is, it becomes easy to maintain both the cutting efficiency and the chip dischargeability satisfactorily.

(5) In the end mill 100, the slenderness ratio (L3 / D1, see FIG. 1) is larger than 2.0, the twist angle θ (see FIG. 2) of each side blade 11a is less than 15 °, and The number of cutting edges 10a is greater than 15 (specifically, 16). If the slenderness ratio is greater than 2.0, the blade portion 10 becomes considerably elongated. Generally, as the slenderness ratio increases, the rigidity of the end mill as a whole decreases, and the roughness of the cut surface of the workpiece decreases. In this regard, when processing the resin member (EVA material or the like), the cutting resistance acting on the end mill is significantly smaller than when processing a material having high hardness such as metal. Therefore, when the resin member is processed, the roughness of the cutting surface of the resin member can be maintained satisfactorily even if the slenderness ratio is larger than 2.0 (thus, the rigidity of the end mill 100 is low).

  In addition, the twist angle θ is very small. The present inventor considers using the end mill 100 when cutting a recess having a desired shape on the upper surface of a resin member (such as EVA resin) having a relatively thin shape. The rigidity of the resin member in the vertical direction is very small. Therefore, when the resin member is processed using an end mill having a relatively large twist angle (for example, 30 ° or more), “battery” is likely to occur in the resin member. On the other hand, when the end mill 100 having a small twist angle θ as described above is used and the resin member is actually processed, “chatter” hardly occurs.

  Furthermore, the number of cutting edges 10a is very large. In general, as the number of cutting edges increases, the cutting surface roughness of the workpiece improves, while the chip discharge performance decreases. In this regard, in the end mill 100, the reduction in chip dischargeability is compensated by forming a large number of the grooves g. Therefore, when the resin member is processed, even if the number of cutting edges is more than 15, the cutting surface roughness of the resin member can be satisfactorily maintained without deteriorating chip discharge.

(6) In the end mill 100, the outer diameter ratio (D2 / D1, see FIG. 1) is less than 0.7. . If the outer diameter ratio is smaller than 0.7, the outer diameter D2 of the shank portion 20 is considerably reduced, so that the rigidity of the end mill 100 as a whole is lowered and the cutting surface roughness of the workpiece tends to deteriorate. In this regard, as described above, when processing the resin member having a low cutting resistance, the cutting surface of the resin member is used even if the outer diameter D2 of the shank portion 20 is small (thus, the rigidity of the end mill 100 is low). The roughness of can be maintained well.

  In addition, when the outer diameter D2 of the shank portion 20 is small, a holding member such as a chuck can be downsized. Therefore, when a relatively deep recess is cut on the upper surface of the workpiece, the holding member is less likely to contact the side surface of the recess. Therefore, the freedom degree of the shape of the recessed part processed by the end mill 100 can be raised.

  The present invention is not limited to the above embodiment, and various modifications can be employed within the scope of the present invention. For example, in the said embodiment, although the blade part 10 and the shank part 20 are integrally formed by the same material continuously (seamlessly), the blade part 10 and the shank part 20 which consist of the same material or a different material are included. Alternatively, they may be integrally formed by brazing or the like.

  The above embodiment is a radius end mill with a flat tip and an R shape at the corner of the tip, but is a flat end mill with a flat tip and no R shape at the corner of the tip. Alternatively, a ball end mill having a spherical tip may be used.

  Moreover, in the said embodiment, although each groove | channel g is a V-shaped groove | channel (refer FIG.2 and FIG.3), each groove | channel g is a semicircle shape even if it is a U-shaped groove | channel. It may be a groove.

  DESCRIPTION OF SYMBOLS 10 ... Blade part, 10a ... Cutting blade, 11 ... Side part, 11a ... Side blade, 12 ... Tip part, 12a ... Tip blade, 12aa ... Flat part, 12ab ... Corner part, 20 ... Shank part

Claims (7)

A blade portion provided with a plurality of cutting blades in the circumferential direction, the tip blade formed on the tip portion, and a side blade formed on the side surface portion and continuously extending from the tip blade;
A shank portion disposed coaxially with the blade portion on a base side opposite to the tip portion of the blade portion;
An end mill comprising:
When the end mill is viewed from the tip end side in the axial direction of the end mill, the angle corresponding to the circumferential shift between the root side end and the tip end of the side blade is 90 ° or less for each side blade. A twist angle that is an angle formed by the axis of the end mill and the extending direction of the side blades is set,
An end mill in which grooves are formed on the outer surface of each cutting edge at a plurality of different positions in the extending direction of the cutting edge. The end mill according to claim 1,
The extending direction of each side blade is such that when the end mill is viewed from the axial base side of the end mill, the circumferential position of the side blade is from the axial base side toward the axial tip side of the end mill. Inclined with respect to the axis of the end mill in the direction of movement in the rotational direction,
A spiral curve that moves from the tip end side in the axial direction to the base side in the axial direction by sequentially connecting the curves that connect the grooves adjacent in the circumferential direction on the outer surface of the blade portion in the circumferential direction in the rotational direction of the end mill. As depicted, an end mill in which positions of the plurality of grooves in the extending direction of the cutting edges are set. The end mill according to claim 2, wherein
When the tip portion of the blade portion is viewed from the tip end side in the axial direction of the end mill, each tip blade is opposite from the rotational direction when the end mill is operated in the circumferential direction from the radially inner side to the radially outer side. An end mill that extends while turning in the direction. In the end mill according to any one of claims 1 to 3,
Each groove is an end mill, which is a V-shaped groove. In the end mill according to any one of claims 1 to 4,
The ratio of the axial length of the side blades to the outer diameter of the blade portion is greater than 2.0, the twist angle of each side blade is less than 15 °, and the number of cutting blades is from 15 Big end mill. In the end mill according to any one of claims 1 to 5,
The end mill wherein the ratio of the outer diameter of the shank portion to the outer diameter of the blade portion is less than 0.7. In the end mill according to any one of claims 1 to 6,
When the blade portion is viewed from a lateral direction perpendicular to the axial direction of the end mill, the tip blade has an arc shape connecting the flat portion corresponding to the flat tip surface and the tip surface and the outer peripheral surface of the side surface portion. An end mill which is a radius end mill having a corner portion.

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