JP6354451B2 - Ball end mill and manufacturing method thereof - Google Patents

Description

  The present invention relates to a small-diameter ball end mill used for processing precision molds and the like, and a method for manufacturing the same.

  The ball end mill has a cutting edge constituted by an outer peripheral blade formed on the outer peripheral portion and a bottom blade formed spherically at the tip of the end mill, and is used for cutting a workpiece. For example, as described in Patent Document 1, a small-diameter ball end mill having a small outer diameter is formed of a cBN sintered body, a diamond sintered body (PCD), or the like in order to process a material with high hardness. A whetstone or the like is used for the formation.

  However, cBN sintered bodies, PCD, and the like have extremely high hardness and excellent wear resistance, but have a brittle side surface for impact. A ball end mill formed of such a brittle material may tend to cause chipping during processing of a workpiece as compared with a ball end mill formed of a cemented carbide or the like depending on an application. The ball end mill functions as a cutting edge with the outer peripheral edge and the bottom edge. However, since the peripheral speed is different between the center part and the outer peripheral part of the end mill, the cutting resistance during the cutting of the workpiece is axial. The central portion and the outer peripheral portion are different. For this reason, it is necessary to ensure the strength of the cutting edge in accordance with the respective peripheral speeds at the axial center portion and the outer peripheral portion of the end mill.

In this respect, for example, in the ball end mill described in Patent Document 1, the flank of the R blade (bottom blade) is configured to have a curved first flank and a substantially flat second flank, and the first flank By adjusting the radius of curvature, the chipping resistance of the cutting edge is improved.
Further, Patent Document 2 proposes a ball end mill in which a rake face and a flank face formed with a cutting edge interposed therebetween are formed smoothly and continuously without forming a ridgeline. It is described that it is easy to grind at the time of machining and that no discontinuity occurs in the arcuate cutting edge, so that the cutting edge strength can be increased. In Patent Document 2, a specific blade diameter of the end mill is not described.

JP 2013-13962 A Japanese Patent No. 4470295

  However, end mills made of brittle materials with high hardness such as cBN sintered bodies and PCD require a strong mechanical load during grinding when forming the end blades of the end mill itself. And the yield is very poor. In addition, the diameter of the end mill has been reduced, and it is difficult to machine the complicated shape of the reduced end mill. In addition, the grinding wheel wears during processing, so that sufficient processing accuracy can be obtained. There is a concern that it will not be obtained and processing errors will occur. And since the processing precision of shapes, such as a cutting blade, falls, it becomes difficult to finish the processing surface of a to-be-processed object with high precision by a small diameter end mill.

  The present invention has been made in view of such circumstances, and a small-diameter ball end mill capable of improving the fracture resistance and wear resistance of the tool itself and improving the finishing accuracy of the workpiece, It aims at providing the manufacturing method.

The ball end mill according to the present invention is composed of a cBN sintered body or a diamond sintered body, and is arranged on the outer periphery of the tool tip portion at a tool tip portion rotated about an axis and having a diameter of 0.1 mm to 6.0 mm. It has at least a pair of cutting blades consisting of an outer peripheral blade and an arcuate bottom blade arranged at the tip of the tool tip, and the cutting blade has a surface shape obtained by rotating the cutting blade around the axis. A margin that is connected to the cutting edge on the land and has no clearance angle is connected, and a clearance surface is connected to the margin, and the clearance angle of the clearance surface is continuous from the axis side to the outer peripheral side. The surface roughness Rz of the margin is set to 0.1 μm or less, and the surface roughness Rz of the flank surface is set to 1 μm or less exceeding the size of the surface roughness of the margin. It is characterized by being.

The ball end mill has different peripheral speeds at the shaft center and the outer periphery due to differences in cutting conditions such as the blade diameter, rotation speed, feed rate, etc., and the cutting resistance during machining of the workpiece is different from that of the shaft center. It differs from the outer periphery. For this reason, the cutting edge strength required differs between the shaft center portion and the outer peripheral portion.
In this respect, in the ball end mill of the present invention, the flank face adapted to the cutting conditions can be formed from the axial line side to the outer peripheral side of the cutting edge by changing the flank angle of the flank face from the axial line side to the outer peripheral side. The necessary cutting edge strength can be ensured at each position.
Moreover, by providing a margin along the cutting edge, the flank can be easily processed, and it is possible to avoid the influence on the previously formed cutting edge. Further, the margin provided along the cutting edge also works advantageously in terms of reinforcing the cutting edge.
Therefore, the fracture resistance and wear resistance of the tool itself can be improved, and as a result, the finishing accuracy of the workpiece can be improved.
In addition, the margin connected to the cutting edge affects the surface roughness of the finished surface of the workpiece. Therefore, the surface roughness Rz (maximum height) should be formed with a smooth surface of 0.1 μm or less. Is desirable. In addition, by forming a margin with a smooth surface, the cutting edge can be formed with a sharp ridgeline, and a cutting edge with high machinability can be configured.
On the other hand, the surface roughness Rz of the flank is larger than the surface roughness of the margin and has a surface roughness of 1 μm or less, so that the contact with the chips of the workpiece is reduced and the cutting oil is retained. can do. Moreover, since heat dissipation is promoted by increasing the surface area of the flank, the tool life can be improved. In addition, when the surface roughness of the flank is increased to 1 μm or more, stress concentration tends to be caused, and defects are likely to occur depending on cutting conditions.

In the ball end mill of the present invention, the clearance angle may be set to be large from the axis side to the outer peripheral side.
Looking at the relationship between the rotational speed of the ball end mill and the feed speed, when the rotational speed (angular speed) is constant, the higher the feed speed, the more the clearance of the flank face is avoided in order to avoid contact between the workpiece and the flank face. It is necessary to set a large corner. Moreover, the peripheral speed is faster on the outer peripheral side than on the axial side on the axial side and the outer peripheral side of the ball end mill. For this reason, in a general ball end mill, the clearance angle is set in accordance with the cutting depth of the workpiece on the outermost periphery.
In this regard, by setting the clearance angle on the outer peripheral side larger than the axial line side of the end mill, in other words, by setting the clearance angle on the axial side smaller than the outer peripheral side, the axis side of the tool can be formed thicker. . Therefore, the fracture resistance can be further improved.

  The present invention is a method for producing the ball end mill by irradiating a cylindrical material made of a cBN sintered body or a diamond sintered body with a laser beam, and forming a gash and a rake face on the cylindrical material. And a cutting edge processing step of forming a tip ball-shaped outer peripheral surface on the cylindrical material after the gash processing step to form a cutting blade comprising an outer peripheral blade and a bottom blade, and a gap from the cutting blade. A flank machining step for forming a flank leaving a margin, and the cutting edge machining step is configured such that the irradiation position of the laser beam and the cutting blade in a state where the cylindrical material is rotated around the axis. It is characterized by being carried out by moving in an arc along the cutting edge shape.

By processing the cutting edge after the gash processing step, it is possible to avoid chipping of the cutting edge. Further, by forming the flank with leaving a margin, the flank can be easily processed, and it is possible to avoid the influence on the previously formed cutting edge.
In this way, by performing laser processing in accordance with the above-described procedure, even a brittle material such as a cBN sintered body or a diamond sintered body can be used to process a reduced end mill with high accuracy. The finishing accuracy of the workpiece can be improved.

  According to the present invention, even with a small-diameter ball end mill, it is possible to improve the chipping resistance and wear resistance of the tool itself, so that it is possible to improve the finishing accuracy of the workpiece.

It is the schematic of the tool front-end | tip part of the ball end mill which concerns on this invention, Comprising: (a) is the front view seen from the front end direction, (b) is a side view. 2 is a cross-sectional view of a main part of the ball end mill of FIG. 1, (a) is a cross-sectional view taken along the line AA, and (b) is a cross-sectional view taken along the line BB. It is a schematic side view of the whole ball end mill. In the Example of the ball end mill which concerns on this invention, it is an enlarged image which shows a flank. It is a whole lineblock diagram showing the laser processing device of one embodiment used for the manufacturing method of the ball end mill concerning the present invention. It is a schematic diagram explaining the manufacturing method of a ball end mill. It is a schematic diagram explaining the light intensity distribution of a laser beam.

Hereinafter, an embodiment of a ball end mill and a manufacturing method thereof according to the present invention will be described with reference to the drawings.
As shown in FIG. 3, the ball end mill 1 of the present embodiment has a tool tip 2 that is rotated around an axis D, and a pair of cutting edges 11 are provided at the tool tip 2 as shown in FIG. This is a two-blade ball end mill formed on the opposite side of 180 ° across the axis D, and a small-diameter end mill in which the outer diameter φ of the tool tip 2 is 0.1 mm or more and 6.0 mm or less.
As shown in FIG. 3, the ball end mill 1 is provided with a cylindrical shank portion 3, the tip portion of the shank portion 3 is formed with a small diameter, and a substantially cylindrical tip portion 5 is formed at the tip of the small diameter neck portion 4. The structure is joined. The tip part 5 is a cemented carbide part 6 joined to the neck part 4 and a tool tip part 2 made of a cBN sintered body or a diamond sintered body connected to the cemented carbide part 6 and having a cutting edge 11 formed thereon. It consists of. And the tool front-end | tip part 2 is formed in the substantially cylindrical shape, and the front end side is formed in the shape of a substantially hemispherical tip ball.

As shown in FIG. 1, the cutting blade 11 is formed by an outer peripheral blade 12 disposed on the outer periphery of the tool distal end portion 2 and an arc-shaped bottom blade 13 disposed on the distal end of the tool distal end portion 2. The cutting blade 11 is disposed at a position 180 degrees apart in the circumferential direction. Further, the cutting blade 11 has a surface shape obtained by rotating the cutting blade 11 about the axis D, and is a portion corresponding to a first flank that is continuous with the cutting blade 11 on the land and has no clearance angle. A margin 15 is connected, and the cutting edge 11 is formed by the margin 15 and the rake face 14. The margin 15 is provided with a width that is about half the core thickness. The margin 15 is connected to a second flank 16 (referred to as flank in the present invention). The other flank of the second flank 16 is a third flank 17 and a third flank 17 is a fourth flank. The flank 18 is sequentially connected. The second flank 16, the third flank 17 and the fourth flank 18 have escaped radially inward from the cutting edge 11 in order to avoid unnecessary contact with the work surface of the workpiece. Formed by a surface.
The land here is a portion having a width from the cutting edge 11 to the intersection line of the second flank 16 and the third flank 17.

  As shown in FIGS. 2A and 2B, the second flank 16 is provided such that the flank angle θ continuously changes from the axis D side to the outer peripheral side. In this case, the clearance angle θ of the second flank 16 is set to be large from the axis D side (arc center O) to the outer peripheral side (point a or point b). Specifically, it is provided in a range from 3 ° to 20 ° from the axis D side to the outer peripheral side.

Further, in the ball end mill 1 of the present embodiment, the surface roughness Rz (maximum height) of the margin 15 is set to 0.1 μm or less, and the surface roughness Rz of the second flank 16 has the surface roughness of the margin 15. It is provided at 1 μm or less.
Further, as shown in FIG. 4, the second flank 16 is provided with a guide groove 51 in which a series of pulse marks is present in a groove shape that is generated when processing is performed with a pulse laser under a certain condition. The guide grooves 51 extend along the inclination direction of the second flank 16 (the direction indicated by the arrow in FIG. 4) and are formed substantially parallel to each other. Further, a large number of fine grooves extending in a direction intersecting with the guide grooves 51 are formed between the adjacent guide grooves 51, and the surface of the second flank 16 is formed by the guide grooves 51 and the fine grooves. Is formed with fine mesh irregularities and is provided on the surface having the surface roughness Rz.

Then, the ball end mill 1 configured as described above forms the shape of the cutting edge 11 and the like by irradiating the columnar material 20 serving as the tool tip 2 with the laser beam L.
As shown in FIG. 5, a laser processing apparatus 100 used in this manufacturing method irradiates a cylindrical material 20 made of a cBN sintered body or a diamond sintered body with a laser beam L to three-dimensionally the entire tool tip 2. It is a processing device. The laser processing apparatus 100 includes a laser beam irradiation mechanism 22 that scans the laser beam L while oscillating the laser beam L at a constant repetition frequency, and rotates, swivels, and rotates while holding the columnar material 20. A material holding mechanism 24 that can move in the xyz-axis direction and a control unit 25 that controls these are provided.

  The material holding mechanism 24 has a mechanism that can translate the workpiece in each of the xyz directions, and can perform a turning motion and a rotation motion. Specifically, an x-axis stage portion 31x that moves in the x direction parallel to the horizontal plane, and a y-axis that is provided on the x-axis stage portion 31x and is movable in the y direction perpendicular to the x direction and parallel to the horizontal plane Stage unit 31y, z-axis stage unit 31z provided on y-axis stage unit 31y and movable in the direction perpendicular to the horizontal plane, axis D of columnar material 20 provided on the z-axis stage unit and laser pulse A turning mechanism 32 for adjusting the angle formed by the irradiation of light, and a rotating mechanism 33 fixed to the turning mechanism 32 and capable of holding the columnar material 20 and rotating the columnar material 20 about the axis D. It is set as the structure provided. For example, a servo motor is used for each of the drive portions of the stage portions 31x to 31z, the turning mechanism 32, and the rotation mechanism 33, and the phase can be fed back by an encoder.

The laser beam irradiation mechanism 22 includes a laser light source 26 that pulse-oscillates a laser beam that becomes a laser beam L by a Q switch, and an optical system that scans the laser beam L to be irradiated and collects the laser beam in a spot shape on the same plane. And a galvano scanner 27 having.
As the laser light source 26, a light source capable of irradiating laser light having a short wavelength of 190 nm to 550 nm can be used. For example, in this embodiment, a UV-YAG laser (third harmonic: wavelength 355 nm, processing position output: 5 W, 60 kHz) ) Which can oscillate and emit laser light. The galvano scanner 27 is disposed directly above the material holding mechanism 24, and the laser beam L is emitted from the vertical direction (z-axis direction).

  Note that the polarization state of the laser may be controlled according to the material to be processed. For example, a cBN sintered body is a composite material of cBN (cubic boron nitride) particles and a binder, and there is a large band gap difference between cBN particles having a large band gap of about 6 eV and the binder. Similarly, PCD (diamond sintered body) is a composite of micron-sized synthetic diamond powder that is sintered and bonded under high temperature and pressure, and is a composite of diamond crystallites and sintering aids required for sintering. There is a large band gap difference between diamond and a sintering aid, which is a material mainly having a large band gap of 5.47 eV. For this reason, even in the case of processing by multiphoton absorption, when the laser beam is incident on s-polarized light, the change in the absorption rate is increased, so that cBN particles and diamond crystallites are less likely to be processed. Since surface undulations become unstable, radial polarization exhibits the effect of the present invention particularly in cBN sintered bodies and PCD.

A method for manufacturing the ball end mill 1 using the laser processing apparatus 100 configured as described above will be described.
First, a gash processing step for forming the gash and rake face 14 on the columnar material 20 is executed. As shown in FIG. 6A, the gash processing step is performed by scanning the laser beam L while moving the columnar material 20.

Next, a cutting edge processing step is performed in which a tip ball-shaped outer peripheral surface is formed on the columnar material 20 after the gash processing step and a cutting edge 11 including the outer peripheral edge 12 and the bottom edge 13 is formed. In the cutting edge processing step, as shown in FIG. 6B, the cylindrical material 20 is rotated around the axis D, and the laser beam L is processed on the rotating cylindrical material 20. The tip of the columnar material 20 is formed in a tip ball shape by moving in an arc shape along the shape.
At this time, since the laser beam L is irradiated while the cylindrical material 20 is rotated around the axis D, the outer peripheral surface of the rotating cylindrical material 20 is randomly irradiated with the laser beam L. It will be. Therefore, the surface roughness Rz (maximum height) of the outer peripheral surface of the cylindrical material 20 can be formed with a smooth surface of 0.1 μm or less, and the cutting edge 11 can be formed with a sharp ridgeline. Therefore, a cutting edge with high machinability can be configured.

Finally, a flank machining step for forming the second flank 16 is performed. In the flank machining step, as shown in FIG. 6C, the second flank 16 is formed leaving a margin 15 with a gap from the cutting edge 11. At this time, the second flank 16 is formed while the guide groove 51 and the fine groove are processed, thereby forming a mesh-like fine unevenness.
Thus, the margin 15 is formed by leaving a part of the outer peripheral surface of the columnar material 20 processed in the cutting edge processing step as it is, so that the surface roughness Rz is 0.1 μm or less. A smooth surface. On the other hand, the second flank 16 is provided with a surface roughness of 1 μm or less exceeding the size of the surface roughness Rz of the margin 15 by forming a mesh-like fine unevenness by the guide grooves 51 and the fine grooves.

The method for forming the second flank 16 will be described in further detail.
The formed second flank 16 has a flank angle θ inclined at 3 ° to 20 ° as shown in FIG. 2, and the laser beam L is shown by a two-dot chain line in FIG. 6C. Then, the surface of the cylindrical material 20 is scanned from the axis D side toward the outer peripheral side along the shape of the second flank 16 formed. However, the light intensity distribution in the radial cross section of the laser beam L, as shown by hatching in FIG. 7, larger in beam center L _0, and has a small Gaussian distribution at the peripheral portion. For this reason, the cutting surface is formed slightly inclined with respect to the irradiation direction of the laser beam L. Therefore, the laser beam L, considering the Gaussian distribution, in a state of slightly tilting the beam center L ₀ relative to the second flank 16, and is irradiated onto the cylindrical material 20. Specifically, the irradiation angle of the laser beam L is adjusted by combining the rotation angle around the axis D of the cylindrical material 20 (the rotation angle of the rotation mechanism 33) and the rotation angle of the rotation mechanism 32, By adjusting the combination of the irradiation angle and the cutting angle of the laser beam L (the light intensity of the laser beam L), the inclination angle of the second flank 16 can be arbitrarily adjusted.

  Then, the second flank 16 is scanned repeatedly in parallel along the tilt direction of the second flank 16 while irradiating the laser beam L whose irradiation angle is adjusted in this manner at a constant repetition frequency. The guide grooves 51 extending along the inclined direction are formed so as to be arranged substantially parallel to each other, and the fine grooves are formed between the adjacent guide grooves 51, and the mesh-like fine structure in which the guide grooves 51 and the fine grooves are combined. Unevenness can be formed.

The ball end mill has different peripheral speeds on the axis D side and the outer peripheral side due to differences in cutting conditions such as the blade diameter, rotation speed, feed rate, etc., and the cutting resistance during the cutting of the workpiece is the axis D. The side and the outer peripheral side are different. For this reason, the cutting edge strength required differs between the axis D side and the outer peripheral side.
In this regard, according to the ball end mill manufacturing method of the present embodiment, the clearance angle θ of the second flank 16 is changed from the axis D side by changing the direction of the cylindrical material 20 and the irradiation angle of the laser beam L. It is also possible to make a small change toward the outer peripheral side. From the axis D side of the cutting edge 11 to the outer peripheral side, the cutting conditions such as the diameter of the ball end mill (blade diameter φ), the type of workpiece, the rotational speed, and the feed speed are used. An adapted flank can be formed. Therefore, the necessary cutting edge strength can be ensured at each position.

Thus, in the manufacturing method of the ball end mill of this invention, it can avoid that the chipping etc. of the blade edge | tip 11 arise by processing the cutting blade 11 after a gash process. Furthermore, by forming the second flank 16 with the margin 15 left, the second flank 16 can be easily machined, and it is possible to avoid the influence on the previously formed cutting edge 11.
In this way, by performing laser processing in accordance with the above-described procedure, even a brittle material such as a cBN sintered body or a diamond sintered body can be used to process a reduced end mill with high accuracy. The finishing accuracy of the workpiece can be improved.
Further, in the ball end mill 1 of the present invention, the clearance angle θ of the second flank 16 is changed from the axis D side to the outer peripheral side, thereby adapting to the cutting conditions from the axis D side to the outer peripheral side of the cutting edge 11. The two flank surfaces 16 can be formed, and the necessary cutting edge strength can be ensured at each position.

For example, looking at the relationship between the rotational speed of the ball end mill and the feed speed, when the rotational speed (angular speed) is constant, the higher the feed speed, the more the flank face is avoided in order to avoid contact between the workpiece and the flank face. It is necessary to set a large clearance angle. Moreover, the peripheral speed is faster on the outer peripheral side than on the axial side on the axial side and the outer peripheral side of the ball end mill. For this reason, in a general ball end mill, the clearance angle is set in accordance with the cutting depth of the workpiece on the outermost periphery.
In this regard, in the ball end mill 1 of the above embodiment, the clearance angle θ on the outer peripheral side is set larger than the axis D side of the end mill, in other words, the clearance angle θ on the axis D side is set smaller than the outer peripheral side. Thus, the axis D side of the tool can be formed thick. Therefore, chipping resistance can be improved.

In addition, since the margin 15 is provided along the cutting edge 11, the second flank 16 can be easily processed, and it is possible to avoid the influence on the previously formed cutting edge 11. Further, the margin 15 provided along the cutting edge 11 also works advantageously in terms of reinforcing the cutting edge 11.
Therefore, the fracture resistance and wear resistance of the tool itself can be improved, and as a result, the finishing accuracy of the workpiece can be improved.

By the way, the feed direction of the ball end mill 1 and the cutting direction (up cut) in which the direction in which the bottom blade 13 advances by rotation about the axis D is the same direction, and the bottom blade 13 is about the axis D with respect to the feed direction of the ball end mill 1. It is called downward cutting (down cut) in which the advancing direction is the opposite direction, but in either case of upward cutting or downward cutting, the ball end mill 1 moves forward while coming into contact with the workpiece from the rake face 14. Processing is performed.
Thus, when considering the case where the cutting edge 11 is turned downward when the ball end mill 1 is rotated, a part of the second flank 16 can be used as the cutting edge 11 as well. It is desirable to increase the clearance angle θ of the outer periphery and decrease the clearance angle θ on the outer peripheral side. Also in this respect, according to the ball end mill manufacturing method of the present embodiment, the clearance angle θ of the second flank 16 is changed to the axis D by changing the direction of the cylindrical material 20 and the irradiation angle of the laser beam L. It can be formed small from the side to the outer peripheral side.

Further, the margin 15 connected to the cutting edge 11 is formed of a smooth surface having a surface roughness Rz of 0.1 μm or less, and avoids affecting the surface roughness of the finished surface of the workpiece. be able to. Furthermore, since the cutting edge 11 can be formed with a sharp ridgeline, the cutting edge 11 with high machinability can be configured.
On the other hand, since the surface roughness Rz of the second flank 16 is larger than the surface roughness of the margin 15 and is formed with a surface roughness of 1 μm or less, the contact with the chips of the workpiece is reduced, Cutting oil can be retained. Moreover, since heat dissipation is accelerated | stimulated by the increase in the surface area of the 2nd flank 16, the tool life can be improved. Note that when the surface roughness Rz of the second flank 16 is increased to 1 μm or more, stress concentration is likely to occur, and defects are likely to occur depending on cutting conditions.

Experiments were conducted to confirm the effect of the ball end mill according to the present invention described above.
The shape of each sample of the ball end mill was formed under the conditions shown in Table 1. Specifically, Example 1 and Comparative Example 1 were prepared with an outer diameter φ of the tool tip (outer peripheral blade) of 0.4 mm, and Examples 2 and Comparative Example 2 were prepared with an outer diameter φ of 2 mm. In the first and second embodiments, the clearance angle θ of the second flank connected to the margin is 10 ° on the axis side and 20 ° on the outer periphery side, and 10 ° to 20 ° from the axis side to the outer periphery side. In this range, it is formed by continuously changing. On the other hand, in Comparative Example 1 and Comparative Example 2, the relief angle θ of the second flank is set to the maximum angle (20 °) of the relief angle θ of Example 1 and Example 2 without changing from the axis side to the outer peripheral side. It is formed at a certain angle. In addition, the outer diameter (phi) and curvature radius R of Table 1 are the dimension values of the site | part regarding a cutting blade, as shown in FIG. Then, 10 samples (N = 10) were produced for each sample.
Moreover, Example 1 and Example 2 were produced by laser processing as described in the above embodiment, and Comparative Examples 1 and 2 were produced by grinding.

  Then, using each of the manufactured samples, cutting was performed on the surface of the work material made of SKD11 (HRC59.5), and the presence or absence of defects was evaluated. The cutting conditions were set as shown in Table 1.

In Table 1, “average number of broken paths” is an average value of the number of paths until a defect occurs in each sample. For example, in Example 1, the average number of broken paths for each of the 10 samples produced was “40”. is there. For this reason, in Example 1, it turns out that cutting of 4 m (100 mm x 40) of cutting length for 40 passes is possible.
As shown in the results of each sample in Table 1, by changing the clearance angle θ from the axial line side to the outer peripheral side, it is possible to increase the cutting length until the defect occurs, Can be improved.

  In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the meaning of this invention, a various change can be added.

DESCRIPTION OF SYMBOLS 1 Ball end mill 2 Tool tip part 3 Shank part 4 Neck part 5 Tip part 6 Cemented carbide part 11 Cutting blade 12 Outer peripheral blade 13 Bottom blade 14 Rake face 15 Margin 16 Second flank 17 Third flank 18 Fourth flank 20 Cylindrical material 22 Laser beam irradiation mechanism 24 Material holding mechanism 25 Control unit 26 Laser light source 27 Galvano scanner 31x x-axis stage unit 31y y-axis stage unit 31z z-axis stage unit 32 turning mechanism 33 rotating mechanism 51 guide groove 100 laser processing apparatus

Claims (3)

an outer peripheral blade disposed on the outer periphery of the tool tip, and a tool tip made of a cBN sintered body or a diamond sintered body and having a diameter rotated about the axis of 0.1 mm to 6.0 mm; Comprising at least a pair of cutting blades consisting of an arcuate bottom blade disposed at the tip of the part,
The cutting edge has a surface shape obtained by rotating the cutting edge about the axis, and a margin that is connected to the cutting edge on the land and has no clearance angle is connected, and the clearance face is connected to the margin. Has been
The clearance angle of the flank is provided continuously changing from the axis side to the outer peripheral side ,
The ball end mill is characterized in that a surface roughness Rz of the margin is set to 0.1 μm or less, and a surface roughness Rz of the flank surface is provided to be 1 μm or less exceeding the size of the surface roughness of the margin. .   The ball end mill according to claim 1, wherein the clearance angle is set to be large from the axis side to the outer peripheral side. A method of manufacturing the ball end mill by irradiating a cylindrical material made of a cBN sintered body or a diamond sintered body with a laser beam,
A gash processing step of forming a gash and rake face on the cylindrical material,
A cutting edge processing step of forming a tip ball-shaped outer peripheral surface on the cylindrical material after the gash processing step to form a cutting blade comprising an outer peripheral blade and a bottom blade;
A flank machining step for forming a flank leaving a margin and leaving a margin with the cutting edge,
The cutting edge processing step is performed by moving the irradiation position of the laser beam in an arc shape along the cutting edge shape serving as the cutting edge in a state where the columnar material is rotated around the axis. A method for producing a ball end mill.