JP7020162B2 - Square end mill - Google Patents

Description

The present invention relates to a square end mill.

Conventionally, for example, the square end mill described in Patent Document 1 is known. The cutting edge of the square end mill has a bottom edge and an outer peripheral edge. The bottom blade and the outer peripheral blade are connected so as to form a substantially right angle between each other at the outer peripheral portion of the tip of the square end mill.

Japanese Unexamined Patent Publication No. 2012-171028

In this type of square end mill, the degree of progress of damage and wear of the cutting edge differs between the bottom blade and the outer peripheral blade, which affects the tool life.

In view of the above circumstances, one of the objects of the present invention is to provide a square end mill capable of equalizing the degree of progress of damage and wear of the cutting edge between the bottom blade and the outer peripheral blade and extending the tool life.

One aspect of the square end mill of the present invention is a tool blade that is rotated around the central axis, a bottom blade that is arranged at the axial tip of the tool blade, and an arrangement on the tip surface of the tool blade. The bottom blade flank extending from the bottom blade toward the rear end side in the axial direction in the direction opposite to the tool rotation direction, and the radial outer end portion of the tool blade portion are arranged in the axial direction. An outer peripheral blade extending along the line and connecting to the bottom blade, and an outer peripheral blade arranged on the outer peripheral surface of the tool blade portion and extending inward in the radial direction from the outer peripheral blade in the direction opposite to the tool rotation direction. It is formed at the intersection of the flank, the bottom blade flank and the outer peripheral blade flank, and is radially inward from the connection point between the bottom blade and the outer peripheral blade toward the rear end side in the axial direction. With a corner ridge extending toward, the bottom blade extends radially inward from the connection point toward the rear end side in the axial direction, and a reference plane including the central axis and the connection point. When viewed from the front, the medium-low gradient angle formed between the virtual straight line orthogonal to the central axis and the bottom blade is more than 0 ° and less than 3 °, and is between the bottom blade and the corner ridgeline. The first ridge angle formed in 1 and the second ridge angle formed between the outer peripheral blade and the corner ridge are 36 ° or more and 51 ° or less, respectively.

In the square end mill, it is preferable that the first ridge line angle and the second ridge line angle are 40 ° or more and 45 ° or less, respectively.

In the square end mill, it is preferable that the clearance angle of the bottom blade flank and the clearance angle of the outer peripheral blade flank are 4 ° or more and 8 ° or less, respectively.

In the square end mill, the difference between the clearance angle of the bottom blade flank surface and the clearance angle of the outer peripheral blade flank surface is preferably less than 2 °.

In the square end mill, it is preferable that the clearance angle of the bottom blade flank and the clearance angle of the outer peripheral blade flank are equal to each other.

In the square end mill, the tool blade portion is arranged at least at the tip portion in the axial direction and faces the tool rotation direction, and the gash surface connected to the tip portion of the outer peripheral blade and the bottom blade and the radial direction of the tool blade portion. It is provided with a chip discharge groove arranged at the outer end portion, facing the tool rotation direction, and connected to a portion of the outer peripheral blade located on the rear end side in the axial direction with respect to the tip portion, and the chip discharge groove is the gash. The length in the axial direction of the portion of the gash surface that is recessed from the surface in the direction opposite to the tool rotation direction and is connected to the tip of the outer peripheral blade shall be 0.3 mm or more and 0.6 mm or less. preferable.

In the square end mill, it is preferable that the axial rake angle of the gash surface exceeds 0 ° and is 3 ° or less.

In the square end mill, it is preferable that the axial length of the radial outer end portion of the gash surface is the smallest in the portion connected to the tip end portion of the outer peripheral blade.

In the square end mill, it is preferable to include a holder that extends along the central axis and to which the tool blade portion is detachably attached.

According to one aspect of the present invention, there is provided a square end mill capable of equalizing the degree of progress of damage and wear of the cutting edge between the bottom blade and the outer peripheral blade and extending the tool life.

It is a perspective view which shows the cutting edge exchange type square end mill of this embodiment. It is a top view of the cutting edge exchange type square end mill. It is a side view of the cutting edge exchange type square end mill. It is a front view of the cutting edge exchange type square end mill. It is a perspective view which shows the cutting insert (tool blade part) of this embodiment. It is a top view of the cutting insert. It is a side view of a cutting insert. It is a front view of a cutting insert. It is a rear view of a cutting insert. It is an enlarged view which shows the main part of the cutting insert, and shows the medium-low gradient angle, the 1st ridge line angle, and the 2nd ridge line angle. It is a cutting edge observation photograph of the cutting edge portion of the Example of this invention. It is a cutting edge observation photograph of the cutting edge portion of a conventional comparative example.

Hereinafter, the cutting insert 10 according to the embodiment of the present invention and the cutting edge exchangeable square end mill 1 provided with the cutting insert 10 will be described with reference to the drawings. The cutting insert 10 is an example of a tool blade portion, and the blade tip exchange type square end mill 1 is an example of a square end mill.

As shown in FIGS. 1 to 4, the blade tip exchange type square end mill 1 includes a holder 2, a cutting insert 10, a bottom blade 11, a bottom blade flank surface 12, an outer peripheral blade 13, and an outer peripheral blade flank surface 14. , A corner ridge line 15, a gash surface 16, a chip discharge groove 17, and a screw member 30. The bottom blade 11, the bottom blade flank 12, the outer peripheral blade 13, the outer peripheral blade flank 14, the corner ridge line 15, the gash surface 16, and the chip discharge groove 17 are provided in the cutting insert 10. The bottom blade 11 and the outer peripheral blade 13 are arranged at the outer edge portion of the cutting insert 10.

The holder 2 is a columnar shape centered on the central axis C. The holder 2 extends along the central axis C. The holder 2 is rotated around the central axis C. The cutting insert 10 is attached to the first end of the both ends of the holder 2 in the central axis C direction. An insert mounting seat 3 is arranged at the first end of the holder 2. The cutting insert 10 is detachably attached to the insert mounting seat 3. That is, the cutting insert 10 is detachably attached to the holder 2.

In the description of the present embodiment, the direction in which the central axis C of the holder 2 extends, that is, the direction along the central axis C is referred to as an axial direction. In the axial direction, the direction from the insert mounting seat 3 of the holder 2 toward the end of the holder 2 opposite to the insert mounting seat 3 (the second end different from the first end) is rearward. Called the end side. The rear end side is the upper side in FIGS. 2 and 3. Of the axial directions, the direction from the end of the holder 2 opposite to the insert mounting seat 3 toward the insert mounting seat 3 is referred to as the tip side. The tip side is the lower side in FIGS. 2 and 3.
The direction orthogonal to the central axis C is called the radial direction. Of the radial directions, the direction closer to the central axis C is called the inner side in the radial direction, and the direction away from the central axis C is called the outer side in the radial direction.
The direction that orbits around the central axis C is called the circumferential direction. Of the circumferential directions, the direction in which the cutting edge exchangeable square end mill 1 is rotated during cutting is called the tool rotation direction R, and the rotation direction opposite to this is the direction opposite to the tool rotation direction R or the anti-tool rotation direction. Call.

A cutting insert 10 is arranged on the insert mounting seat 3 at the tip of the holder 2 so that its central axis (insert central axis) substantially coincides with the central axis C of the holder 2. That is, the central axis C of the holder 2 and the central axis of the cutting insert 10 are arranged coaxially with each other. The cutting insert 10 is rotated around the central axis C together with the holder 2.

The above definition of direction also applies to the cutting insert 10. In FIGS. 5 to 9 and the like showing the cutting insert 10, the central axis of the cutting insert 10 is represented by using the same reference numeral C as the central axis C of the holder 2.
Specifically, in the cutting insert 10, the direction from the bottom blade 11 toward the end of the cutting insert 10 opposite to the bottom blade 11 is the rear end side. Of the axial directions, the direction from the end of the cutting insert 10 opposite to the bottom blade 11 toward the bottom blade 11 is the tip side.

In FIGS. 1 to 4, the holder 2 is made of a metal such as a steel material. The rear end portion of the holder 2 is attached to a spindle of a machine tool (not shown). When the spindle is rotationally driven, the holder 2 is rotated in the tool rotation direction R around the central axis C. The holder 2 is moved together with the main shaft in the axial direction, the radial direction, the composite direction thereof, and the like. As a result, the blade tip exchange type square end mill 1 performs milling processing (milling processing) on the work material such as metal by the bottom blade 11 and the outer peripheral blade 13 of the cutting insert 10. The blade tip exchange type square end mill 1 of the present embodiment may be used for a machine tool such as a machining center for multi-axis control of 4 to 6 axes, for example.

The insert mounting seat 3 has an insert insertion groove 4 and a screw hole 5.
The insert insertion groove 4 is arranged at the tip of the holder 2 and extends in the radial direction. The insert insertion groove 4 has a groove shape that opens on the tip side and in the radial direction at the tip portion of the holder 2. The insert insertion groove 4 has a slit shape that penetrates the tip of the holder 2 in the radial direction. The insert insertion groove 4 opens on the tip end surface of the holder 2 and also opens on the outer peripheral surface of the holder 2. The insert insertion groove 4 has a concave shape that is recessed from the front end surface of the holder 2 toward the rear end side. Although not particularly shown, the bottom surface located at the rear end of the insert insertion groove 4 and facing the front end side is V-shaped and is recessed toward the rear end side.

By providing the insert insertion groove 4 at the tip of the holder 2, the tip is divided into two, and a pair of tip halves (half pieces) are formed at the tip. At the tip portion, the screw hole 5 penetrates one tip half body portion and extends radially into the other tip half body portion. Of the screw holes 5, the inner diameter of the hole portion formed in one tip half body portion is larger than the inner diameter of the hole portion formed in the other tip half body portion. A female screw portion is provided on the inner peripheral surface of the hole portion of the screw hole 5 formed in the other tip half body portion. Of the screw holes 5, the hole portion formed in at least one of the tip half bodies is a through hole. In the example of the present embodiment, each hole portion of one tip half body portion and the other tip half body portion is a through hole, respectively.

The cutting insert 10 is made of, for example, cemented carbide. In the cutting insert 10 attached to the insert mounting seat 3, the bottom blade 11 is arranged so as to project toward the tip end side of the holder 2, and the outer peripheral blade 13 is arranged so as to project outward in the radial direction of the holder 2.

As shown in FIGS. 5 to 9, the cutting insert 10 has a plate shape. In the example of this embodiment, the cutting insert 10 has a substantially pentagonal plate shape. The cutting insert 10 has a front-back inverted symmetry shape (180 ° rotational symmetry shape) with the central axis C as the axis of symmetry.
A pair of plate surfaces facing the thickness direction of the cutting insert 10 are indicated by reference numerals 18 and 19 in the drawing. The cutting insert 10 has a screw insertion hole 20, a cutting edge portion 21, a corner ridge line 15, a gash surface 16, and a chip discharge groove 17.

The screw insertion hole 20 penetrates the cutting insert 10 in the thickness direction. The screw insertion hole 20 opens in one plate surface 18 and the other plate surface 19 of the cutting insert 10. The screw insertion hole 20 is a circular hole. The central axis of the screw insertion hole 20 is orthogonal to the central axis C of the cutting insert 10. When the cutting insert 10 is mounted on the insert mounting seat 3 and fixed, the screw member 30 is inserted into the screw insertion hole 20.

The cutting edge portion 21 is arranged at the tip portion in the axial direction and the outer end portion in the radial direction in the cutting insert 10. The cutting edge portion 21 has a rake face, a flank intersecting the rake face, and a cutting edge formed at the intersecting ridge line portion between the rake face and the flank surface. The rake face is a surface of the cutting edge portion 21 facing the tool rotation direction R. The flank includes a surface of the cutting edge portion 21 facing the tip end side and a surface facing the radial outer side.

The cutting edge has a bottom blade 11 and an outer peripheral blade 13. The cutting edge is substantially L-shaped as a whole. The cutting insert 10 of the present embodiment is a two-flute cutting tip, and has two sets of cutting edges having a bottom blade 11 and an outer peripheral blade 13 in a 180 ° rotational symmetry with the central axis C as the center.

The bottom blade 11 is arranged at the tip portion in the axial direction of the cutting insert 10. The bottom blade 11 extends along the radial direction. The bottom blade 11 is linear. The radial outer end of the bottom blade 11 is connected to the tip of the outer peripheral blade 13. The bottom blade 11 extends radially inward from the connection point A between the bottom blade 11 and the outer peripheral blade 13 toward the rear end side. The radial inner end of the bottom blade 11 is located on the central axis C.

As shown in FIG. 10, when the reference plane including the central axis C and the connection point A is viewed from the front, the medium-low gradient angle D formed between the virtual straight line VL orthogonal to the central axis C and the bottom blade 11 Is greater than 0 ° and less than 3 °. The reference plane is a virtual plane perpendicular to the main motion direction (circumferential direction) of the blade edge exchange type square end mill 1 and including the connection point A. The medium-low gradient angle D is an acute angle or an obtuse angle centered on the connection point A formed between the virtual straight line VL and the bottom blade 11. The medium-low gradient angle D may be rephrased as a sub-cutting angle, a front cutting edge angle, a shear angle, and the like.

As shown in FIG. 6, the amount of displacement in the axial direction (that is, the inclination with respect to the radial direction) per unit length along the radial direction of the bottom blade 11 is constant over the entire blade length of the bottom blade 11. The rotation locus of the bottom blade 11 when the cutting insert 10 is rotated around the central axis C is a concave conical shape that is recessed toward the rear end side with the central axis C as the center.

Of the rake face of the cutting edge portion 21, the portion adjacent to the rear end side of the bottom blade 11 is the rake face portion (bottom blade rake face) of the bottom blade 11. The rake face portion of the bottom blade 11 is flat. The rake face portion of the bottom blade 11 is arranged on the gash surface 16. The axial rake angle of the bottom blade 11 corresponds to the axial rake angle of the gash surface 16 described later.

As shown in FIGS. 5 and 8, of the flanks of the cutting edge portion 21, the portion of the bottom blade 11 adjacent to the tool rotation direction R in the direction opposite to the tool rotation direction R is the bottom blade flank surface 12. The bottom blade flank surface 12 is arranged on the tip surface of the cutting insert 10. The bottom blade flank surface 12 extends from the bottom blade 11 toward the rear end side in the direction opposite to the tool rotation direction R. As a result, the bottom blade flank surface 12 is provided with a flank angle. The clearance angle of the bottom blade flank surface 12 is 4 ° or more and 8 ° or less. The clearance angle of the bottom blade flank surface 12 corresponds to the clearance angle of the bottom blade 11.

Of the tip surface of the cutting insert 10, the portion of the bottom blade flank surface 12 located in the direction opposite to the tool rotation direction R has a larger clearance angle than the bottom blade flank surface 12. The bottom blade flank surface 12 and the portion of the bottom blade flank surface 12 located in the direction opposite to the tool rotation direction R are planar.

As shown in FIGS. 5 to 7, the outer peripheral blade 13 is arranged at the outer end portion in the radial direction of the cutting insert 10. The outer peripheral blade 13 extends along the axial direction and is connected to the bottom blade 11. The outer peripheral blade 13 extends in a direction opposite to the tool rotation direction R as it toward the rear end side in the axial direction. In FIG. 10, the angle formed between the outer peripheral blade 13 and the bottom blade 11 is approximately 90 °, and specifically, is a value obtained by subtracting the medium-low gradient angle D from 90 °. The rotation locus of the outer peripheral blade 13 when the cutting insert 10 is rotated around the central axis C is cylindrical with the central axis C as the center.

In FIGS. 5 to 7, the outer peripheral blade 13 has a tip portion 13a and a portion 13b located on the rear end side of the tip portion 13a. The tip of the tip portion 13a is connected to the radial outer end of the bottom blade 11. The tip portion 13a and the portion 13b located on the rear end side of the tip portion 13a are linear, respectively.

The amount of displacement in the circumferential direction (that is, the inclination with respect to the axial direction) per unit length along the axial direction in the portion 13b located on the rear end side of the tip portion 13a is larger than the displacement amount of the tip portion 13a. That is, the outer peripheral blade 13 has different axial rake angles (corresponding to a helix angle) between the tip portion 13a and the portion 13b located on the rear end side of the tip portion 13a. The axial rake angle of the tip portion 13a corresponds to the axial rake angle of the gash surface 16 described later. The axial rake angle of the portion 13b located on the rear end side of the tip portion 13a is, for example, 4 ° or more and 15 ° or less. The axial rake angle of the portion 13b located on the rear end side of the tip portion 13a is larger than the axial rake angle of the tip portion 13a.

Of the rake face of the cutting edge portion 21, the portion adjacent to the inner side in the radial direction of the outer peripheral blade 13 is the rake face portion (outer peripheral blade rake surface) of the outer peripheral blade 13. The rake face portion of the outer peripheral blade 13 includes a rake face portion of the tip portion 13a and a rake face portion of the portion 13b located on the rear end side of the tip portion 13a. The rake face portion of the tip portion 13a is planar. The rake face portion of the tip portion 13a is arranged on the gash surface 16. The rake face portion of the portion 13b located on the rear end side of the tip portion 13a has a concave curved surface shape. The rake face portion of the portion 13b located on the rear end side of the tip portion 13a is arranged in the chip discharge groove 17.

Of the flanks of the cutting edge portion 21, the portion of the outer peripheral blade 13 adjacent to the outer peripheral blade 13 in the direction opposite to the tool rotation direction R is the outer peripheral blade flank surface 14. The outer peripheral blade flank surface 14 is arranged on the outer peripheral surface of the cutting insert 10. The outer peripheral blade flank surface 14 extends inward in the radial direction from the outer peripheral blade 13 in the direction opposite to the tool rotation direction R. As a result, the outer peripheral blade flank surface 14 is provided with a flank angle. The clearance angle of the peripheral blade flank surface 14 is 4 ° or more and 8 ° or less. The clearance angle of the outer peripheral blade flank surface 14 corresponds to the clearance angle of the outer peripheral blade 13. The difference between the clearance angle of the bottom blade flank surface 12 and the clearance angle of the outer peripheral blade flank surface 14 is less than 2 °. In the example of the present embodiment, the clearance angle of the bottom blade flank surface 12 and the clearance angle of the outer peripheral blade flank surface 14 are equal to each other.
In the example of the present embodiment, of the outer peripheral blade flank surface 14, the flank portion of the tip portion 13a and the flank surface portion of the portion 13b located on the rear end side of the tip portion 13a are formed by a single surface. Has been done.

Of the outer peripheral surface of the cutting insert 10, the portion of the outer peripheral blade flank surface 14 located in the direction opposite to the tool rotation direction R has a larger clearance angle than the outer peripheral blade flank surface 14. The outer peripheral blade flank surface 14 and the portion of the outer peripheral blade flank surface 14 located in the direction opposite to the tool rotation direction R are both planar.

As shown in FIGS. 5 and 10, the corner ridge line 15 is formed at the intersecting ridge line portion between the bottom blade flank surface 12 and the outer peripheral blade flank surface 14. The corner ridge line 15 extends inward in the radial direction from the connection point A between the bottom blade 11 and the outer peripheral blade 13 toward the rear end side. The corner ridge line 15 is a straight line. The corner ridge line 15 is an intersecting ridge line between a portion of the bottom blade flank surface 12 located in the direction opposite to the tool rotation direction R and a portion of the outer peripheral blade flank surface 14 located in the direction opposite to the tool rotation direction R. It may be formed over parts.

As shown in FIG. 10, when the reference plane including the central axis C and the connection point A is viewed from the front, the first ridge line angle θ1 formed between the bottom blade 11 and the corner ridge line 15, and the outer peripheral blade 13 The second ridge line angle θ2 formed between the corner ridge line 15 and the corner ridge line 15 is 36 ° or more and 51 ° or less, respectively. That is, the first ridge line angle θ1 is 36 ° or more and 51 ° or less, and the second ridge line angle θ2 is 36 ° or more and 51 ° or less. Preferably, the first ridge line angle θ1 and the second ridge line angle θ2 are 40 ° or more and 45 ° or less, respectively.

When the corner ridge line 15 is projected perpendicularly to the reference surface including the central axis C and the connection point A, the reference surface is viewed from the front and between the bottom blade 11 and the corner ridge line 15. The angle formed is the first ridge angle θ1, and the angle formed between the outer peripheral blade 13 and the corner ridge 15 is the second ridge angle θ2.

As shown in FIGS. 5 to 7, the gash surface 16 is arranged at least at the tip portion of the cutting insert 10, faces the tool rotation direction R, and is connected to the tip portion 13a and the bottom blade 11 of the outer peripheral blade 13. The gosh surface 16 is planar. The axial rake angle of the gash surface 16 is more than 0 ° and 3 ° or less. That is, the axial rake angle of the gash surface 16 is a conformal angle (positive angle).

As shown in FIG. 6, the axial length (flat width) F of the portion of the gash surface 16 connected to the tip portion 13a of the outer peripheral blade 13 is 0.3 mm or more and 0.6 mm or less. The axial length of the gash surface 16 at the radial outer end is the smallest at the portion connected to the tip portion 13a of the outer peripheral blade 13 (F value above). The axial length of the gash surface 16 at the radial outer end portion increases radially inward from the portion connected to the tip portion 13a.

As shown in FIGS. 5 to 7, the chip discharge groove 17 is arranged at the outer end portion in the radial direction of the cutting insert 10 and faces the tool rotation direction R, and is on the rear end side of the outer peripheral blade 13 with respect to the tip portion 13a. It is connected to the portion 13b located at. The chip discharge groove 17 is recessed from the gash surface 16 in a direction opposite to the tool rotation direction R.

The chip discharge groove 17 extends in a direction opposite to the tool rotation direction R so as to be toward the rear end side in the axial direction. The cross-sectional shape perpendicular to the central axis C of the chip discharge groove 17 is a concave curve. The chip discharge groove 17 is connected to the gash surface 16. The intersecting ridge line portion 22 between the chip discharge groove 17 and the gash surface 16 is radially inward from the boundary point between the tip portion 13a of the outer peripheral blade 13 and the portion 13b located on the rear end side of the tip portion 13a. Therefore, it extends toward the rear end side. The crossed ridge line portion 22 has a curved shape that is convex toward the tip end side and inward in the radial direction.

As shown in FIGS. 1 to 3, the screw member 30 fixes the cutting insert 10 to the insert mounting seat 3. The screw member 30 has a screw head and a screw shaft portion. The screw head is arranged in the hole portion of the screw hole 5 of one of the tip half bodies of the pair of tip half bodies provided at the tip portion of the holder 2. The diameter of the screw shaft portion is smaller than that of the screw head. A male screw portion is provided on the outer peripheral surface of the screw shaft portion. The screw shaft portion is inserted into the hole portion of the screw hole 5 of one tip half body portion, the screw insertion hole 20 of the cutting insert 10, and the hole portion of the screw hole 5 of the other tip half body portion. The male screw portion of the screw shaft portion is screwed into the female screw portion of the hole portion of the screw hole 5 of the other tip half body portion.

According to the blade tip exchange type square end mill 1 of the present embodiment described above, the medium-low gradient angle D of the bottom blade 11 is more than 0 ° and less than 3 °. This has the effect of improving the shape maintenance life of the cutting edge of the replaceable cutting edge square end mill 1. In addition, the strength of the cutting edge of the cutting edge is ensured, chipping is prevented, and the machined surface accuracy of the work material can be maintained satisfactorily.

Specifically, since the medium-low gradient angle D exceeds 0 °, smooth movement is possible in machining in which the cutting edge exchangeable square end mill 1 is sent in the direction orthogonal to the central axis C (diameter direction), and machining of the work material is possible. The surface accuracy can be improved. On the other hand, when the medium-low gradient angle D is 0 ° or less, the cutting load on the bottom blade 11 becomes large, which hinders smooth movement and lowers the machined surface accuracy. In addition, it is not suitable for cutting to form corners perpendicular to the work material.

Further, since the medium-low gradient angle D is less than 3 °, the cutting edge strength of the cutting edge is ensured, chipping is suppressed, and the machined surface accuracy of the work material is stably ensured. On the other hand, when the medium-low gradient angle D is 3 ° or more, the cutting edge strength of the cutting edge is lowered, vibration is generated during cutting, and the cutting edge is likely to be chipped at an early stage, and the machined surface of the work material is easily damaged. Affects the surface texture of. Further, for example, when the machining width of the work material is small, a convex shape (so-called “navel”) in which the bottom blade shape is transferred to the machined surface tends to remain, and it becomes difficult to secure flatness.

In the present embodiment, when the medium-low gradient angle D is 2 ° or less, the above-mentioned effect becomes more remarkable, which is preferable.

In the present embodiment, the first ridge angle θ1 formed between the bottom blade 11 and the corner ridge line 15 is 36 ° or more and 51 ° or less, and is formed between the outer peripheral blade 13 and the corner ridge line 15. The second ridge line angle θ2 to be formed is 36 ° or more and 51 ° or less. This has the effect of improving the shape maintenance life of the cutting edge of the replaceable cutting edge square end mill 1.

Specifically, when the first ridge line angle θ1 and the second ridge line angle θ2 are 36 ° or more and 51 ° or less, respectively, the difference between the clearance angle of the bottom blade flank surface 12 and the clearance angle of the outer peripheral blade flank surface 14 can be obtained. It can be kept small. Then, the difference between the blade angle of the bottom blade 11 and the blade angle of the outer peripheral blade 13 can be suppressed to a small size. Therefore, the strength of the cutting edge of the bottom blade 11 and the strength of the cutting edge of the outer peripheral blade 13 can be equalized. Further, the amount of wear of the bottom blade 11 and the amount of wear of the outer peripheral blade 13 can be equalized. As a result, the cutting edge strength of the cutting edge of the replaceable cutting edge square end mill 1 is stably secured, chipping is suppressed, and the machined surface accuracy of the work material can be maintained satisfactorily.

Specifically, since the first ridge line angle θ1 is 36 ° or more, damage, wear, and the like of the bottom blade 11 and the outer peripheral blade 13 can be evenly dispersed, and the tool life can be extended. On the other hand, when the first ridge line angle θ1 is less than 36 °, the clearance angle of the outer peripheral blade flank angle 14 becomes larger than the clearance angle of the bottom blade flank surface 12, and the outer peripheral blade 13 is damaged as compared with the bottom blade 11. Wear and the like are likely to progress. For this reason, the bottom blade 11 and the outer peripheral blade 13 have a difference in the degree of blade edge defect and blade edge retreat, which affects the tool life.

Further, since the first ridge line angle θ1 is 51 ° or less, damage, wear, etc. of the bottom blade 11 and the outer peripheral blade 13 can be evenly dispersed, and the tool life can be extended. On the other hand, when the first ridge line angle θ1 exceeds 51 °, the clearance angle of the bottom blade flank surface 12 becomes larger than the clearance angle of the outer peripheral blade flank surface 14, and the bottom blade 11 is damaged or worn as compared with the outer peripheral blade 13. Etc. are easy to progress. For this reason, the bottom blade 11 and the outer peripheral blade 13 have a difference in the degree of blade edge defect and blade edge retreat, which affects the tool life.

Further, since the second ridge line angle θ2 is 36 ° or more, damage, wear, etc. of the bottom blade 11 and the outer peripheral blade 13 can be evenly dispersed, and the tool life can be extended. On the other hand, when the second ridge line angle θ2 is less than 36 °, the clearance angle of the bottom blade flank surface 12 becomes larger than the clearance angle of the outer peripheral blade flank surface 14, and the bottom blade 11 is damaged as compared with the outer peripheral blade 13. Wear and the like are likely to progress. For this reason, the bottom blade 11 and the outer peripheral blade 13 have a difference in the degree of blade edge defect and blade edge retreat, which affects the tool life.

Further, since the second ridge line angle θ2 is 51 ° or less, damage, wear, etc. of the bottom blade 11 and the outer peripheral blade 13 can be evenly dispersed, and the tool life can be extended. On the other hand, when the second ridge line angle θ2 exceeds 51 °, the clearance angle of the outer peripheral blade flank angle 14 becomes larger than the clearance angle of the bottom blade flank surface 12, and the outer peripheral blade 13 is damaged or worn as compared with the bottom blade 11. Etc. are easy to progress. For this reason, the bottom blade 11 and the outer peripheral blade 13 have a difference in the degree of blade edge defect and blade edge retreat, which affects the tool life.

Further, in the present embodiment, when the first ridge line angle θ1 is 40 ° or more and 45 ° or less and the second ridge line angle θ2 is 40 ° or more and 45 ° or less, the cutting edge of the blade tip exchange type square end mill 1 is cut. The shape maintenance life in the above is further improved, and high-quality machined surface accuracy is well maintained.

Further, in the present embodiment, the clearance angle of the bottom blade flank surface 12 and the clearance angle of the outer peripheral blade flank surface 14 are 4 ° or more and 8 ° or less, respectively, so that the following effects can be obtained.
That is, in this case, the cutting edge strength of the cutting edge of the replaceable cutting edge square end mill 1 is ensured, and the shape maintenance life of the cutting edge is improved. In addition, the chipping of the cutting edge is prevented, and the machined surface accuracy of the work material can be maintained satisfactorily.

Specifically, since the clearance angle (bottom blade clearance angle) of the bottom blade flank surface 12 is 4 ° or more, contact between the bottom blade flank surface 12 and the work material can be suppressed. On the other hand, when the clearance angle of the bottom blade flank 12 is less than 4 °, the flank wear of the bottom blade flank 12 progresses faster, which may affect the tool life. Further, in order to avoid contact between the bottom blade flank surface 12 and the work material, the allowable range of cutting conditions may be narrowed.

Further, since the clearance angle of the bottom blade flank surface 12 is 8 ° or less, the blade angle of the bottom blade 11 is secured, the cutting edge strength of the bottom blade 11 is secured, and the bottom blade 11 can be prevented from being damaged. On the other hand, when the clearance angle of the bottom blade flank 12 exceeds 8 °, the strength of the cutting edge of the bottom blade 11 decreases, and the bottom blade 11 tends to be chipped, which affects the machined surface accuracy.

Further, since the clearance angle (peripheral blade clearance angle) of the outer peripheral blade flank surface 14 is 4 ° or more, contact between the outer peripheral blade flank surface 14 and the work material can be suppressed. On the other hand, when the clearance angle of the outer peripheral blade flank surface 14 is less than 4 °, the flank wear of the outer peripheral blade flank surface 14 progresses faster, which may affect the tool life. Further, in order to avoid contact between the outer peripheral blade flank surface 14 and the work material, the allowable range of cutting conditions may be narrowed.

Further, since the clearance angle of the outer peripheral blade flank surface 14 is 8 ° or less, the blade angle of the outer peripheral blade 13 is secured, the cutting edge strength of the outer peripheral blade 13 is secured, and the outer peripheral blade 13 can be prevented from being damaged. On the other hand, when the clearance angle of the outer peripheral blade flank 14 exceeds 8 °, the cutting edge strength of the outer peripheral blade 13 is lowered, and the outer peripheral blade 13 is likely to be chipped, which affects the machined surface accuracy.

In order to further stabilize the above-mentioned effects, it is preferable that the clearance angle of the bottom blade flank surface 12 and the clearance angle of the outer peripheral blade flank surface 14 are 5 ° or more and 8 ° or less, respectively. In the best mode of the present embodiment, the clearance angle of the bottom blade flank surface 12 and the clearance angle of the outer peripheral blade flank surface 14 are both 6 °.

Further, in the present embodiment, since the difference between the clearance angle of the bottom blade flank surface 12 and the clearance angle of the outer peripheral blade flank surface 14 is less than 2 °, the degree of progress of damage, wear, etc. of the bottom blade 11 and the outer circumference. The degree of progress of damage, wear, etc. of the blade 13 is more equalized. Therefore, the tool life can be extended, and the quality of the machined surface of the work material can be stably improved.

Further, in the present embodiment, when the clearance angle of the bottom blade flank surface 12 and the clearance angle of the outer peripheral blade flank surface 14 are equal to each other, the degree of progress of damage, wear, etc. of the bottom blade 11 and the outer peripheral blade 13 The degree of progress of damage, wear, etc. is more stably equalized.

Further, in the present embodiment, the length (flat width) F in the axial direction of the portion of the gash surface 16 connected to the tip portion 13a of the outer peripheral blade 13 is 0.3 mm or more and 0.6 mm or less, so that the blade edge can be replaced. It has the effect of improving the shape maintenance life of the cutting edge of the square end mill 1. In addition, the strength of the cutting edge of the cutting edge is ensured, chipping is prevented, and the machined surface accuracy of the work material can be maintained satisfactorily.

Specifically, since the flat width F is 0.3 mm or more, the cutting edge strength of the cutting edge is sufficiently secured. As a result, for example, even when high-efficiency machining such as finishing is performed on a work material such as a high-hardness material or a difficult-to-cut material, the chipping of the cutting edge is suppressed. On the other hand, when the flat width F is less than 0.3 mm, the cutting edge strength of the cutting edge cannot be secured, and the cutting edge may be easily damaged due to vibration of the cutting edge in high-efficiency machining.

Further, since the flat width F is 0.6 mm or less, it is possible to maintain good chip discharge. The chips are chips generated from the vicinity of the radial outer end of the bottom blade 11 and the vicinity of the tip portion 13a of the outer peripheral blade 13. In addition, the cutting resistance of the cutting edge is reduced, the accuracy of the machined surface of the work material is improved, and the surface texture of the machined surface is maintained well. On the other hand, when the flat width F exceeds 0.6 mm, it becomes difficult to secure the chip discharge property, the cutting resistance of the cutting edge increases, the sharpness decreases, and the surface texture of the machined surface of the work material is good. It becomes difficult to maintain.

In order to further stabilize the above-mentioned effects, the flat width F is preferably 0.45 mm or more and 0.55 mm or less.

Further, in the present embodiment, since the axial rake angle (axial rake) of the gash surface 16 exceeds 0 ° and is 3 ° or less, the amount of flank wear can be suppressed and the shape maintenance life of the cutting edge is improved. Has.

Specifically, since the axial rake angle of the gash surface 16 exceeds 0 ° (that is, it is a positive value), the cutting edge sharply cuts into the work material and easily bites, the processing efficiency is improved, and the processing surface accuracy is improved. improves. On the other hand, when the axial rake angle of the gash surface 16 is 0 ° or less, it is difficult to secure the sharpness of the cutting edge, and the amount of flank wear increases.

Further, since the axial rake angle of the gash surface 16 is 3 ° or less, vibration due to an increase in thrust force during cutting can be suppressed, and the machining surface accuracy can be stably improved. On the other hand, when the axial rake angle of the gash surface 16 exceeds 3 °, the amount of flank wear increases due to the increase in thrust force, vibration is likely to occur, and the cutting edge may be damaged. Therefore, it may be difficult to maintain the shape of the cutting edge (right angle shape).

In order to make the above-mentioned action and effect more stable, it is preferable that the axial rake angle of the gash surface 16 exceeds 0 ° and is 2 ° or less.

Further, in the present embodiment, the axial length at the radial outer end portion of the gash surface 16 is the smallest at the portion connected to the tip end portion 13a of the outer peripheral blade 13, so that the following effects can be obtained.
That is, in this case, the axial length at the radial outer end of the gash surface 16 is the minimum at the radial outer end and becomes larger at the portion located inside the radial outer end than the radial outer end (diameter). Equal to or better than the outer edge). Therefore, if the cutting edge portion of the gash surface 16 connected to the tip end portion 13a of the outer peripheral blade 13 is manufactured so that the cutting edge strength of the cutting edge can be ensured, the cutting edge located radially inside from this portion. Rigidity can be stably ensured in the entire portion (bottom blade 11). Therefore, the cutting edge strength of the cutting edge can be stably increased.

Further, in the present embodiment, the tool blade portion is the cutting insert 10, and the square end mill is the cutting edge exchange type square end mill 1. The present invention exerts a particularly remarkable effect when applied to a cutting insert 10 made of cemented carbide and a cutting edge exchangeable square end mill 1 provided with the cutting insert 10.

The present invention is not limited to the above-described embodiment, and the configuration can be changed without departing from the spirit of the present invention, for example, as described below.

In the above-described embodiment, the cutting insert 10 has a pentagonal plate shape, but the cutting insert 10 is not limited to this. The cutting insert 10 may have a polygonal plate shape other than the pentagonal plate shape, for example.
Further, although the example in which the cutting insert 10 has the screw insertion hole 20 is given, the cutting insert 10 may not have the screw insertion hole 20. In this case, the cutting insert 10 is detachably attached to the holder 2 by, for example, a clamp mechanism.

Further, although it is assumed that the gash surface 16 is flat, the present invention is not limited to this. The gash surface 16 may have a curved surface (convex curved surface or concave curved surface).

Further, in the above-described embodiment, the cutting edge exchange type square end mill 1 has been described as an example, but the square end mill may be a solid type. The solid type square end mill is integrally provided with a blade portion and a shank portion. The blade is located at least at the axial tip of the square end mill. The shank portion is arranged on the rear end side in the axial direction with respect to the blade portion. In this case, the "tool blade portion" of the present invention corresponds to the above-mentioned blade portion.

In the above-described embodiment, the material of the cutting insert 10 is, for example, cermet, high-speed steel, titanium carbide, silicon carbide, silicon nitride, in addition to the cemented carbide containing tungsten carbide (WC) and cobalt (Co). , Ceramics made of aluminum nitride, aluminum oxide, and mixtures thereof, cubic boron nitride sintered body, diamond sintered body, hard phase made of polycrystalline diamond or cubic boron nitride, ceramics, iron group metals, etc. It is also possible to use an ultra-high pressure calcined body that calcins the bonded phase under ultra-high pressure.
Further, as the holder 2, for example, in addition to the case of manufacturing with an alloy tool steel such as SKD61, it is also possible to use a holder 2 formed by joining an alloy tool steel such as SKD61 and a cemented carbide.

In addition, as long as it does not deviate from the gist of the present invention, each configuration (component) described in the above-described embodiments, modifications, and notes may be combined, and additions, omissions, substitutions, and the like of the configurations may be combined. It can be changed. Further, the present invention is not limited to the above-described embodiments, but is limited only to the scope of claims.

Hereinafter, the present invention will be specifically described with reference to Examples. However, the present invention is not limited to this embodiment.

[Tool life confirmation test]
As an example of the present invention, a cutting insert 10 having the specifications of Examples 1 to 8 in Table 1 below and a cutting edge exchangeable square end mill 1 were prepared. Further, as a conventional comparative example, a cutting insert having the specifications of Comparative Examples 1 to 8 in Table 2 below and a cutting edge exchange type square end mill were prepared.

The procedure for obtaining the first ridge line angle θ1 and the second ridge line angle θ2 shown in Tables 1 and 2 is as follows.
First, as a first step, the bottom blade clearance angle and the outer peripheral blade clearance angle are measured using a contact-type contour shape measuring device, and the medium-low gradient angle D is measured using a tool presetter.
Next, as a second step, a three-dimensional shape model of the tip of the corner portion of the cutting edge portion 21 is created based on the measurement data of the above three items, and this is converted into electronic data.
Finally, as a third step, from the drawing of the above three-dimensional shape model, the corner ridge line 15 is perpendicular to the reference plane including the central axis C of the cutting insert and the connection point A between the bottom blade 11 and the outer peripheral blade 13. The angles of the first ridge line angle θ1 and the second ridge line angle θ2 are calculated by projecting to. Here, the first ridge line angle θ1 can be obtained from the intersection angle with the corner ridge line 15 with the bottom blade 11 of the cutting insert as a reference line. Further, the second ridge line angle θ2 can be obtained from the intersection angle with the corner ridge line 15 with the outer peripheral blade 13 of the cutting insert as a reference line.

Then, in the examples and comparative examples, cutting was performed under the following conditions, and the tool life was evaluated.
Work material: DAC (45HRC)
Processing method: Shoulder cutting Cutting conditions: Vc = 160m / min, fz = 0.15mm / t, ap = 1.0mm, ae = 0.2mm, OH = 90mm, air blow

The criteria for judging the evaluation results (A to C) in Tables 1 and 2 are as follows.
A: The cutting length (cutting distance) that can ensure the accuracy of the machined surface is 80 m or more, and the tool life is excellent.
B: The cutting length that can ensure the machined surface accuracy is 40 m or more and 80 m or less, and the tool life is good.
C: The cutting length that can ensure the machined surface accuracy is less than 40 m, and the tool life is inferior.
In the above A to C, the standard for "ensuring the accuracy of the machined surface" is that the maximum flank wear amount is 0.1 mm or less.

[Discussion]
In Examples 1 to 5, each numerical range of the bottom blade clearance angle and the outer peripheral blade clearance angle is 4 ° to 8 °, and the bottom blade clearance angle and the outer peripheral blade clearance angle are set to the same value. The medium-low gradient angle D was set to 1 ° or 2 °. The first ridge angle θ1 and the second ridge angle θ2 were 44 ° or 44.5 °, respectively.
The evaluation result of the cutting test showed that the tool life was 80 m or more, and was ranked A. When the cutting edge portion 21 was observed at a microscope magnification of 100 times when the cutting length was 80 m, the amount of flank wear was small and the shape of the cutting edge could be maintained. Furthermore, since no defect in the cutting edge was observed, it was judged that the blade could be used continuously. In Example 3, the longest tool life was shown, and the cutting length when the criterion for determining the maximum flank wear amount was set to 0.1 mm was 144 m. An observation photograph of the cutting edge of the cutting edge portion 21 of Example 3 is shown in FIG. 11 (observation magnification 100 times). As shown in FIG. 11, in Example 3, the amount of flank wear was small, and the cutting edge shape could be maintained.

In Example 6, the bottom blade clearance angle was set to 4 ° and the outer peripheral blade clearance angle was set to 5 °. The first ridge angle θ1 was 37.9 °, the second ridge angle θ2 was 50.1 °, and the difference between the two was 12.2 °.
The evaluation result of the cutting test showed that the tool life did not reach 80 m but was 40 m or more, and was ranked B.
When the cutting edge portion 21 was observed at a microscope magnification of 100 times when the cutting length was 40 m, the amount of flank wear was observed to progress closer to the outer peripheral blade 13 than to the vicinity of the bottom blade 11, but the cutting edge It was judged that the state of shape maintenance was satisfactory. At the time of 45 m, the maximum flank wear amount exceeded 0.1 mm.

In Example 7, the bottom blade clearance angle was set to 6 ° and the outer peripheral blade clearance angle was set to 7 °. The first ridge line angle θ1 was 40.1 °, the second ridge line angle θ2 was 48.9 °, and the difference between the two was 8.8 °.
According to the evaluation result of the cutting test, the tool life did not reach 80 m, but it showed 40 m or more and was ranked B.
When the cutting edge portion 21 was observed at a microscope magnification of 100 times when the cutting length was 40 m, the wear width of the outer peripheral blade flank surface 14 was larger than that of the bottom blade flank surface 12, but the shape of the cutting edge could be maintained. I decided that there was. At the time of 60 m, the maximum flank wear amount exceeded 0.1 mm.

In Example 8, the bottom blade clearance angle was set to 8 ° and the outer peripheral blade clearance angle was set to 7 °. The first ridge angle θ1 was 48.3 °, the second ridge angle θ2 was 40.7 °, and the difference between the two was 7.6 °.
According to the evaluation result of the cutting test, the tool life did not reach 80 m, but it showed 40 m or more and was ranked B.
When the cutting edge portion 21 was observed at a microscope magnification of 100 times when the cutting length was 40 m, the shape of the cutting edge could be maintained although the bottom blade flank surface 12 was worn more than the outer peripheral blade flank surface 14. I decided that there was. At the time of 70 m, the maximum flank wear amount exceeded 0.1 mm.

In Comparative Example 1, the bottom blade clearance angle was set to 4 ° and the outer peripheral blade clearance angle was set to 6 °, and the difference between the two was set to 2 °. The first ridge line angle θ1 was 30.7 °, the second ridge line angle θ2 was 54.3 °, and the difference between the two was 23.6 °.
The evaluation result of the cutting test showed that the tool life was less than 40 m, and it was ranked C.
When the cutting edge portion 21 was observed at a microscope magnification of 100 times when the cutting length was 5 m, the outer peripheral blade 13 was significantly worn compared to the bottom blade 11, but the cutting edge shape of the cutting edge could be maintained. I decided that there was. At the time of 31 m, the maximum flank wear amount exceeded 0.1 mm.

In Comparative Example 2, the bottom blade clearance angle was set to 4 ° and the outer peripheral blade clearance angle was set to 8 °, and the difference between the two was set to 4 °. The first ridge angle θ1 was 26.0 °, the second ridge angle θ2 was 62.0 °, and the difference between the two was 36 °.
The evaluation result of the cutting test showed that the tool life was less than 40 m, and it was ranked C.
When the cutting edge portion 21 was observed at a microscope magnification of 100 times when the cutting length was 5 m, the wear of the outer peripheral blade 13 progressed more than that of the bottom blade 11, and minute chipping was confirmed. It was judged that the shape of the cutting edge of was maintained. At 17 m, the tip of the cutting edge was damaged and the tool life was reached.

In Comparative Example 3, the bottom blade clearance angle was set to 6 ° and the outer peripheral blade clearance angle was set to 8 °, and the difference between the two was set to 2 °. The first ridge line angle θ1 was 35.7 °, the second ridge line angle θ2 was 51.3 °, and the difference between the two was 15.6 °.
The evaluation result of the cutting test showed that the tool life was less than 40 m, and it was ranked C.
When the cutting edge portion 21 was observed at a microscope magnification of 100 times when the cutting length was 5 m, the outer peripheral blade 13 was significantly worn compared to the bottom blade 11, but the cutting edge shape of the cutting edge could be maintained. I decided that there was. At 20 m, the maximum flank wear amount exceeded 0.1 mm.

In Comparative Example 4, the bottom blade clearance angle was set to 6 ° and the outer peripheral blade clearance angle was set to 8 °, and the difference between the two was set to 2 °. The first ridge angle θ1 was 36.1 °, the second ridge angle θ2 was 51.9 °, and the difference between the two was 15.8 °.
The evaluation result of the cutting test showed that the tool life was less than 40 m, and it was ranked C.
When the cutting edge portion 21 was observed at a microscope magnification of 100 times when the cutting length was 5 m, the outer peripheral blade 13 was significantly worn compared to the bottom blade 11, but the cutting edge shape of the cutting edge could be maintained. I decided that there was. At the time of 29 m, the maximum flank wear amount exceeded 0.1 mm.

In Comparative Example 5, the bottom blade clearance angle was set to 6 ° and the outer peripheral blade clearance angle was set to 8 °, and the difference between the two was set to 2 °. The first ridge angle θ1 was 36.4 °, the second ridge angle θ2 was 52.6 °, and the difference between the two was 16.2 °.
The evaluation result of the cutting test showed that the tool life was less than 40 m, and it was ranked C.
When the cutting edge portion 21 was observed at a microscope magnification of 100 times when the cutting length was 5 m, the outer peripheral blade 13 was significantly worn compared to the bottom blade 11, but the cutting edge shape of the cutting edge could be maintained. I decided that there was. At the time of 37 m, the maximum flank wear amount exceeded 0.1 mm.

In Comparative Example 6, the bottom blade clearance angle was set to 6 °, the outer peripheral blade clearance angle was set to 10 °, and the difference between the two was 4 °. The first ridge angle θ1 was 30.5 °, the second ridge angle θ2 was 58.5 °, and the difference between the two was 28 °.
The evaluation result of the cutting test showed that the tool life was less than 40 m, and it was ranked C.
When the cutting edge portion 21 was observed at a microscope magnification of 100 times when the cutting length was 5 m, the wear of the outer peripheral blade 13 progressed more than that of the bottom blade 11, and minute chipping was confirmed. It was judged that the shape of the cutting edge of was maintained. At the time of 23 m, the maximum flank wear amount exceeded 0.1 mm.

In Comparative Example 7, the bottom blade clearance angle was set to 6 ° and the outer peripheral blade clearance angle was set to 12 °, and the difference between the two was 6 °. The first ridge angle θ1 was 26.1 °, the second ridge angle θ2 was 62.9 °, and the difference between the two was 36.8 °.
The evaluation result of the cutting test showed that the tool life was less than 40 m, and it was ranked C.
When the cutting edge portion 21 was observed at a microscope magnification of 100 times when the cutting length was 5 m, the wear of the outer peripheral blade 13 progressed more than that of the bottom blade 11, and minute chipping was confirmed. It was judged that the shape of the cutting edge of was maintained. At 9 m, the tip of the cutting edge was damaged and the tool life was reached. An observation photograph of the cutting edge of the cutting edge portion 21 of Comparative Example 7 is shown in FIG. 12 (observation magnification 100 times). As shown in FIG. 12, in Comparative Example 7, the wear width of the outer peripheral blade flank surface 14 was large, and minute chipping was observed.

In Comparative Example 8, the bottom blade clearance angle was set to 8 ° and the outer peripheral blade clearance angle was set to 12 °, and the difference between the two was 4 °. The first ridge angle θ1 was 33.2 °, the second ridge angle θ2 was 55.8 °, and the difference between the two was 22.6 °.
The evaluation result of the cutting test showed that the tool life was less than 40 m, and it was ranked C.
When the cutting edge portion 21 was observed at a microscope magnification of 100 times when the cutting length was 5 m, the wear of the outer peripheral blade 13 progressed more than that of the bottom blade 11, and minute chipping was confirmed. It was judged that the shape of the cutting edge of was maintained. At 13 m, the tip of the cutting edge was damaged and the tool life was reached.

According to the present invention, there is provided a square end mill capable of equalizing the degree of progress of damage and wear of the cutting edge between the bottom blade and the outer peripheral blade and extending the tool life. Therefore, it has industrial applicability.

2 ... holder, 11 ... bottom blade, 12 ... bottom blade flank surface, 13 ... outer peripheral blade, 13a ... outer peripheral blade tip, 13b ... outer peripheral blade located on the rear end side in the axial direction from the tip, 14 ... Outer blade flank surface, 15 ... Corner ridge line, 16 ... Gash surface, 17 ... Chip discharge groove, A ... Connection point, C ... Central axis, D ... Medium and low gradient angle, R ... Tool rotation direction, VL ... Virtual straight line , Θ1 ... 1st ridge angle, θ2 ... 2nd ridge angle

Claims (9)

A tool blade that can be rotated around the central axis,
The bottom blade arranged at the tip of the tool blade in the axial direction,
A bottom blade flank that is arranged on the tip surface of the tool blade and extends from the bottom blade toward the rear end side in the axial direction in the direction opposite to the tool rotation direction.
An outer peripheral blade that is arranged at the radial outer end of the tool blade, extends along the axial direction, and is connected to the bottom blade.
An outer peripheral blade flank surface that is arranged on the outer peripheral surface of the tool blade portion and extends inward in the radial direction from the outer peripheral blade in the direction opposite to the tool rotation direction.
A corner formed at the intersection ridgeline portion between the bottom blade flank surface and the outer peripheral blade flank surface, and extending inward in the radial direction from the connection point between the bottom blade and the outer peripheral blade toward the rear end side in the axial direction. With a ridgeline,
The bottom blade extends radially inward from the connection point toward the rear end side in the axial direction.
Looking at the reference plane including the central axis and the connection point from the front,
The medium-low gradient angle formed between the virtual straight line orthogonal to the central axis and the bottom blade is more than 0 ° and less than 3 °.
The first ridge angle formed between the bottom blade and the corner ridge and the second ridge angle formed between the outer peripheral blade and the corner ridge are 36 ° or more and 51 ° or less, respectively. There is a square end mill. The square end mill according to claim 1.
A square end mill in which the first ridge angle and the second ridge angle are 40 ° or more and 45 ° or less, respectively. The square end mill according to claim 1 or 2.
A square end mill in which the clearance angle of the bottom blade flank and the clearance angle of the outer peripheral blade flank are 4 ° or more and 8 ° or less, respectively. The square end mill according to claim 3.
A square end mill in which the difference between the clearance angle of the bottom blade flank and the clearance angle of the outer peripheral blade flank is less than 2 °. The square end mill according to claim 3 or 4.
A square end mill in which the clearance angle of the bottom blade flank and the clearance angle of the outer peripheral blade flank are equal to each other. The square end mill according to any one of claims 1 to 5.
A gosh surface that is arranged at least at the tip of the tool blade in the axial direction and faces the tool rotation direction and is connected to the tip of the outer peripheral blade and the bottom blade.
It is provided with a chip discharge groove which is arranged at the outer end portion in the radial direction of the tool blade portion, faces the tool rotation direction, and is connected to a portion of the outer peripheral blade located on the rear end side in the axial direction from the tip portion.
The chip discharge groove is recessed from the gash surface in a direction opposite to the tool rotation direction.
A square end mill having an axial length of a portion of the gash surface connected to the tip of the outer peripheral blade of 0.3 mm or more and 0.6 mm or less. The square end mill according to claim 6.
A square end mill in which the axial rake angle of the gash surface is more than 0 ° and 3 ° or less. The square end mill according to claim 6 or 7.
A square end mill in which the axial length at the radial outer end of the gash surface is the smallest at the portion connected to the tip of the outer peripheral blade. The square end mill according to any one of claims 1 to 8.
A holder that extends along the central axis and to which the tool blade is detachably attached.
Square end mill.

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