JP7486459B2 - Rotary tool and method for manufacturing machined product - Google Patents

Description

This disclosure relates to a rotary tool used in cutting (milling) a workpiece, and a method for manufacturing a cut product.

For example, the end mill described in Patent Document 1 is known as a rotary tool used when milling a workpiece made of a metal material or the like. The end mill described in Patent Document 1 has multiple bottom blades located at the tip side of the body. The multiple bottom blades have one bottom blade (parent blade) that extends from the outer periphery to the chisel edge, and another bottom blade (child blade) that extends from the outer periphery to a position away from the chisel edge. These bottom blades are inclined radially (in a direction perpendicular to the rotation axis) so as to approach the rear end of the body as they approach the rotation axis. At this time, the inclination angle of the child blade relative to the radial direction is larger than the inclination angle of the parent blade relative to the radial direction.

JP 2010-201565 A

In a rotary tool having a main cutting edge and a bottom cutting edge, it is preferable to prevent the main cutting edge from wearing out or becoming chipped prematurely.

A rotary tool according to one aspect of the present disclosure includes a cylindrical body extending along a rotation axis from a first end to a second end and having a cutting portion on the first end side. The cutting portion has a plurality of cutting edges located on the first end side of the body and a plurality of discharge grooves each extending from the plurality of cutting edges toward the second end of the body. The plurality of cutting edges include a first cutting edge extending from the outer periphery toward the rotation axis, a second cutting edge located forward of the first cutting edge in the rotation direction of the rotation axis and extending from the outer periphery toward the rotation axis, and a third cutting edge located forward of the second cutting edge in the rotation direction of the rotation axis and extending from the outer periphery toward the rotation axis. When the division angle between the first cutting edge and the second cutting edge when viewed from the front toward the first end of the body is defined as a first division angle, and the division angle between the second cutting edge and the third cutting edge is defined as a second division angle, the second division angle is set to be larger than the first division angle. The first cutting edge is inclined relative to the radial direction (the direction perpendicular to the rotation axis) so as to approach the second end of the main body as it approaches the rotation axis. The second cutting edge is inclined relative to the radial direction so as to approach the second end of the main body as it approaches the rotation axis. When the inclination angle of the first cutting edge relative to the rotation axis when viewed from the side of the first cutting edge is defined as a first concave angle, and the inclination angle of the second cutting edge relative to the rotation axis when viewed from the side of the second cutting edge is defined as a second concave angle, the first concave angle is set to be smaller than the second concave angle.

According to one aspect of the present disclosure, it is possible to reduce the variation in the cutting load applied to the first blade and the second blade during cutting of the workpiece, thereby improving the durability of the rotary tool.

FIG. 2 is a perspective view of an end mill according to an embodiment. FIG. 2 is an enlarged perspective view of a portion II in FIG. 1 . FIG. 2 is a front view of the end mill shown in FIG. 1 . FIG. 4 is a side view seen from a direction IV in FIG. 3 . FIG. 4 is a side view seen from a direction V in FIG. 3 . FIG. 4 is an enlarged cross-sectional view taken along the line VI-VI in FIG. FIG. 7 is an enlarged cross-sectional view of the VII-VII section in FIG. FIG. 11 is a partial side view of an end mill according to a first modified example of the embodiment. FIG. 11 is a partial side view of an end mill according to a second modified example of the embodiment. FIG. 11 is a partial side view of an end mill according to a third modified example of the embodiment. 1A to 1C are schematic diagrams illustrating a manufacturing method of a machined product according to an embodiment. 1A to 1C are schematic diagrams illustrating a manufacturing method of a machined product according to an embodiment. 1A to 1C are schematic diagrams illustrating a manufacturing method of a machined product according to an embodiment. 1A to 1C are schematic diagrams illustrating a manufacturing method of a machined product according to an embodiment.

The following describes in detail an end mill as an example of a rotary tool according to an embodiment of the present disclosure, and a method for manufacturing a machined product, with reference to the drawings. However, for the sake of convenience, each of the drawings referred to below shows a simplified version of only the components necessary to explain the embodiment. Therefore, an end mill as an example of a rotary tool may include any components not shown in each of the drawings referred to. Furthermore, the dimensions of the components in each drawing do not faithfully represent the actual dimensions of the components or the dimensional ratios of each component.

In this disclosure, the rotation axis refers to the rotation axis (rotation axis center) of the rotating tool, and the circumferential direction refers to the direction around the rotation axis. The radial direction refers to the direction perpendicular to the rotation axis and the circumferential direction, the radially inner direction refers to the direction or side approaching the rotation axis in the radial direction, and the radially outer direction refers to the direction or side away from the rotation axis in the radial direction.

<End mill according to an embodiment of the present disclosure>
The configuration of an end mill 10, which is an example of a rotary tool according to an embodiment, will be described with reference to Figures 1 to 7. Figure 1 is a perspective view of the end mill according to the embodiment. Figure 2 is an enlarged perspective view of part II in Figure 1. Figure 3 is a front view of the end mill shown in Figure 1. Figure 4 is a side view seen from direction IV in Figure 3. Figure 5 is a side view seen from direction V in Figure 3. Figure 6 is an enlarged cross-sectional view of section VI-VI in Figure 3. Figure 7 is an enlarged cross-sectional view of section VII-VII in Figure 3.

1 and 2, an end mill 10, which is an example of a rotary tool of this embodiment, is an end mill used for cutting (turning) a workpiece W (see FIG. 8) made of a metal material or the like. Examples of cutting the workpiece W include shoulder cutting, groove cutting, R cutting, and copying. The end mill 10 is a solid-type end mill made of a hard material such as cemented carbide, cermet, and cBN. The end mill 10 has a cylindrical body 12, which extends from a tip (first end) 12a to a rear end (second end) 12b along a rotation axis S. The body 12 has a cutting portion 14 on the tip 12a side that contacts the workpiece W (see FIG. 11) and turns the workpiece W. The body 12 has a shank portion 16 on the rear end 12b side that is attached to the spindle of a machine tool via an arbor. As long as at least the cutting portion 14 is made of a hard material such as cemented carbide, cermet, or cBN, the end mill 10 does not have to be a solid type end mill.

As shown in Figures 1 to 5, the cutting portion 14 has a plurality of bottom edges 18 as an example of a plurality of cutting edges, and the plurality of bottom edges 18 are located at intervals in the circumferential direction on the tip 12a side of the body 12. The cutting portion 14 has a chisel edge 20 that passes through the rotation axis S, and the chisel edge 20 is located on the tip 12a side of the body 12. The chisel edge 20 has the effect of crushing a portion of the workpiece W.

The cutting section 14 has a number of discharge grooves 22 for discharging chips generated by cutting to the outside. The multiple discharge grooves 22 are formed at intervals in the circumferential direction on the outer peripheral surface of the main body 12, and each extends in a spiral shape from the multiple bottom blades 18 toward the rear end 12b of the main body 12. An outer peripheral blade 24, which is an example of a cutting blade, is located at the outer peripheral end of the wall surface facing the rotation direction T of the rotation axis S of each discharge groove 22. The number of outer peripheral blades 24 is the same as the number of discharge grooves 22. A rake face 26 is located on the discharge groove 22 side of each outer peripheral blade 24, and a clearance face 28 is located behind the rotation direction T of the rotation axis S of each outer peripheral blade 24 (opposite the rotation direction T). The outer peripheral blade 24 is located at the intersection ridge of the rake face 26 and the clearance face 28.

The multiple bottom blades 18 include a first bottom blade 30 as a first cutting blade, which is a sub-blade that extends from the outer periphery toward the rotation axis S to a position away from the chisel edge 20. A planar scooping surface 32 is located on the discharge groove 22 side of the first bottom blade 30, and a clearance surface 34 is located behind the first bottom blade 30 in the rotation direction T of the rotation axis S. The first bottom blade 30 is located on the intersection ridge between the scooping surface 32 and the clearance surface 34. The radially outer end of the first bottom blade 30 is smoothly connected to the tip of the outer peripheral blade 24 via a corner portion 36. The corner portion 36 functions as a cutting blade.

The multiple bottom blades 18 include a second bottom blade 38 as a second cutting blade, which is a parent blade extending from the outer periphery toward the rotation axis S to the chisel edge 20. The second bottom blade 38 is located forward of the first bottom blade 30 in the rotation direction T of the rotation axis S. A planar scooping surface 40 is located on the discharge groove 22 side of the second bottom blade 38, and a clearance surface 42 is located behind the second bottom blade 38 in the rotation direction T of the rotation axis S. The second bottom blade 38 is located on the intersection ridge between the scooping surface 40 and the clearance surface 42. The radially outer end of the second bottom blade 38 is smoothly connected to the tip of the outer peripheral blade 24 via a corner portion 44. The corner portion 44 functions as a cutting blade.

The bottom blades 18 include a third bottom blade 46 as a third cutting blade, which is a sub-blade that extends from the outer periphery toward the rotation axis S to a position away from the chisel edge 20. The third bottom blade 46 is located forward of the second bottom blade 38 in the rotation direction T of the rotation axis S. The third bottom blade 46 is rotationally symmetrical with respect to the first bottom blade 30 about the rotation axis S. A planar scooping surface 48 is located on the discharge groove 22 side of the third bottom blade 46, and a relief surface 50 is located behind the third bottom blade 46 in the rotation direction T of the rotation axis S. The third bottom blade 46 is located on the intersection ridge between the scooping surface 48 and the relief surface 50. The radially outer end of the third bottom blade 46 is smoothly connected to the tip of the outer peripheral blade 24 via a corner portion 52. The corner portion 52 functions as a cutting blade.

The plurality of bottom blades 18 includes a fourth bottom blade 54 as a fourth cutting blade, which is a parent blade extending from the outer periphery toward the rotation axis S to the chisel edge 20. The fourth bottom blade 54 is located forward of the third bottom blade 46 in the rotation direction T of the rotation axis S. The fourth bottom blade 54 is rotationally symmetrical with respect to the second bottom blade 38 about the rotation axis S. A planar scooping surface 56 is located on the discharge groove 22 side of the fourth bottom blade 54, and a relief surface 58 is located behind the fourth bottom blade 54 in the rotation direction T of the rotation axis S. The fourth bottom blade 54 is located on the intersection ridge between the scooping surface 56 and the relief surface 58. The radially outer end of the fourth bottom blade 54 is smoothly connected to the tip of the outer peripheral blade 24 via a corner portion 60. The corner portion 60 functions as a cutting blade. The flank 58 of the fourth bottom cutting edge 54 is connected to the flank 42 of the second bottom cutting edge 38 via the chisel edge 20.

As an example, the end mill 10 has four bottom blades 18 (first bottom blade 30, second bottom blade 38, third bottom blade 46, and fourth bottom blade 54), but the number of bottom blades 18 may be three or five or more.

As shown in Figures 3, 6, and 7, the rake angle of the first bottom blade 30 is the first rake angle α1, and the rake angle of the second bottom blade 38 is the second rake angle α2. The first rake angle α1 may be set larger than the second rake angle α2. Compared to the second bottom blade 38, which is the parent blade connected to the chisel edge 20, the first bottom blade 30, which is the child blade located away from the chisel edge 20, may have a risk of cutting load being concentrated, for example, on the end portion close to the rotation axis S. However, when the first rake angle α1 is larger than the second rake angle α2, the cutting load applied to the first bottom blade 30 can be reduced. Therefore, the durability of the multiple bottom blades 18 as a whole is high.

The rake angle of the third bottom blade 46 is the third rake angle, and the rake angle of the fourth bottom blade 54 is the fourth rake angle. The third rake angle may be set to be larger than the fourth rake angle. In this case, for the same reason as described above, the cutting load applied to the third bottom blade 46, which is the child blade, can be reduced. Therefore, the durability of the multiple bottom blades 18 as a whole is high.

The third rake angle may be set to the same as the first rake angle α1, and the fourth rake angle may be set to the same as the second rake angle α2. Making the two rake angles the same means making the difference between the two rake angles within 1 degree. When the third rake angle is the same as the first rake angle α1, the variation in the cutting load applied to the first bottom cutting edge 30 and the third bottom cutting edge 46 can be suppressed. Therefore, chatter vibrations can be suppressed. Also, when the fourth rake angle is the same as the second rake angle α2, the variation in the cutting load applied to the second bottom cutting edge 38 and the fourth bottom cutting edge 54 can be suppressed. Therefore, chatter vibrations can be suppressed.

As shown in FIG. 3, when viewed from the front toward the tip 12a of the main body 12, the division angle between the first bottom blade 30 and the second bottom blade 38 is the first division angle θ1, the division angle between the second bottom blade 38 and the third bottom blade 46 is the second division angle θ2, and the division angle between the third bottom blade 46 and the fourth bottom blade 54 is the third division angle θ3. In this case, the second division angle θ2 may be set larger than the first division angle θ1. When the second division angle θ2 is larger than the first division angle θ1, the cutting load applied to the first bottom blade 30 can be reduced. Therefore, the durability of the multiple bottom blades 18 as a whole is high.

The third division angle θ3 may be set to be the same as the first division angle θ1. Making the two division angles the same means making the difference between the two division angles within 1 degree. When the division angles are set in this manner, it is possible to suppress the variation in the cutting load applied to the first bottom cutting edge 30 and the third bottom cutting edge 46.

As shown in Figures 4 and 5, the first bottom blade 30 may be inclined in the radial direction (direction perpendicular to the rotation axis S) so as to approach the rear end 12b of the body 12 as it approaches the rotation axis S. The first bottom blade 30 may also be perpendicular to the rotation axis S. The second bottom blade 38 is inclined in the radial direction so as to approach the rear end 12b of the body 12 as it approaches the rotation axis S. Here, the radially outer end of the second bottom blade 38 may be farther away from the rear end 12b of the body 12 than the radially outer end of the first bottom blade 30. In such a case, the second bottom blade 38, which is the parent blade, is likely to come into stable contact with the workpiece. In addition, the cutting load applied to the first bottom blade 30, which is the child blade, is suppressed, so that the durability of the first bottom blade 30 can be improved.

As described above, when the first rake angle α1 is greater than the second rake angle α2, the durability of the first bottom blade 30 is likely to decrease compared to the second bottom blade 38. However, since the cutting load applied to the first bottom blade 30, which is the child blade, is suppressed, the first bottom blade 30 is less likely to be damaged.

The third bottom blade 46 may be inclined radially so as to approach the rear end 12b of the body 12 as it approaches the rotation axis S. The third bottom blade 46 may also be perpendicular to the rotation axis S. The fourth bottom blade 54 is inclined radially so as to approach the rear end 12b of the body 12 as it approaches the rotation axis S. Here, the radially outer end of the fourth bottom blade 54 may be farther away from the rear end 12b of the body 12 than the radially outer end of the third bottom blade 46. In such a case, the fourth bottom blade 54, which is the parent blade, is likely to come into stable contact with the workpiece. In addition, the cutting load applied to the third bottom blade 46, which is the child blade, is suppressed, so that the durability of the third bottom blade 46 can be increased.

The radially outer end of the third bottom blade 46 may be located at the same position as the radially outer end of the first bottom blade 30 in the direction along the rotation axis S. In this case, the variation between the cutting load applied to the first bottom blade 30 and the cutting load applied to the cutting load applied to the third bottom blade 46 can be kept small. Therefore, the durability of the multiple bottom blades 18 as a whole is high. In addition, the radially outer end of the fourth bottom blade 54 may be located at the same position as the radially outer end of the second bottom blade 38 in the direction along the rotation axis S. In this case, the variation between the cutting load applied to the second bottom blade 38 and the cutting load applied to the cutting load applied to the fourth bottom blade 54 can be kept small. Therefore, the durability of the multiple bottom blades 18 as a whole is high.

The inclination angle of the first bottom blade 30 relative to the rotation axis S when viewed from the side is defined as the first concave angle β1, and the inclination angle of the second bottom blade 38 relative to the rotation axis S when viewed from the side is defined as the second concave angle β2. The inclination angle of the third bottom blade 46 relative to the rotation axis S when viewed from the side is defined as the third concave angle β3, and the inclination angle of the fourth bottom blade 54 relative to the rotation axis S when viewed from the side is defined as the fourth concave angle β4.

At this time, the first concave angle β1 may be set smaller than the second concave angle β2. In this case, the second bottom blade 38 can be used as a so-called main cutting edge, and the first bottom blade 30 can be used as a so-called wiper edge. When the first concave angle β1 of the first bottom blade 30 is relatively small, the inclination angle of the first bottom blade 30 with respect to the machining surface of the cut workpiece is small. Therefore, the first bottom blade 30 can be used as a wiper edge.

For example, as described above, when the first rake angle α1 is larger than the second rake angle α2, the function of the first bottom blade 30 as a sweeping blade is improved. Also, as described above, when the radially outer end of the second bottom blade 38 is farther away from the rear end 12b of the body 12 than the radially outer end of the first bottom blade 30, the cutting load applied to the first bottom blade 30 is suppressed compared to the second bottom blade 38, so that the first bottom blade 30 is less likely to be damaged. Therefore, even when the first bottom blade 30 is used as a sweeping blade, the first bottom blade 30 is less likely to be damaged .

The third concave angle β3 may be set to the same as the first concave angle β1, and the fourth concave angle β4 may be set to the same as the second concave angle β2. Making the two concave angles the same means making the difference between the two concave angles within 1 degree. When the concave angles are set in this way, the third bottom blade 46 can be used as a so-called main cutting blade, and the fourth bottom blade 54 can be used as a so-called wiper blade. Furthermore, there is little variation in the cutting load applied to the first bottom blade 30 and the third bottom blade 46, which are used as wipers. There is also little variation in the cutting load applied to the second bottom blade 38 and the fourth bottom blade 54, which are used as main cutting blades. Therefore, the durability of the multiple bottom blades 18 as a whole is high.

As shown in FIG. 3, a thinning surface 62 is located on the rake face 40 side of the second bottom cutting edge 38, and the thinning surface 62 is inclined in the radial direction so as to approach the rear end 12b of the body 12 as it approaches the outer periphery. A thinning surface 64 is located on the rake face 56 side of the fourth bottom cutting edge 54, and the thinning surface 64 is inclined in the radial direction so as to approach the rear end 12b of the body 12 as it approaches the outer periphery. This allows the core thickness of the end mill 10 to be increased while ensuring space for the flow of chips generated by the second bottom cutting edge 38 and the fourth bottom cutting edge 54.

As described above, the second division angle θ2 may be set larger than the first division angle θ1, and the third division angle θ3 may be set equal to the first division angle θ1. The first concave angle β1 may be set smaller than the second concave angle β2, and the third concave angle β3 may be set equal to the first concave angle β1. The first rake angle α1 may be set larger than the second rake angle α2, and the third rake angle may be set larger than the fourth rake angle. When the division angle and concave angle are set in this manner, the variation in the cutting load applied to the first bottom cutting edge 30 and the third bottom cutting edge 46 and the cutting load applied to the second bottom cutting edge 38 and the fourth bottom cutting edge 54 during cutting of the workpiece W can be suppressed, thereby improving the durability of the end mill 10. In particular, the first rake angle α1 may be set larger than the second rake angle α2, and when the third rake angle is set larger than the fourth rake angle, the above-mentioned effect can be further enhanced.

<First Modification of the Present Disclosure>
The configuration of the first modified example of this embodiment will be described with reference to Fig. 8. Fig. 8 is a partial side view of the end mill according to the first modified example of the embodiment.

As shown in FIG. 8, in the first modified example of this embodiment, the second bottom cutting edge 38 has an outer portion (first portion) 38e located radially outward and an inner portion (second portion) 38i located radially inward. When the second bottom cutting edge 38 is viewed from the side, the inclination angle of the outer portion 38e relative to the rotation axis S is the outer second concave angle β2e, and the inclination angle of the inner portion 38i relative to the rotation axis S is the inner second concave angle β2i.

In this case, the inner second concave angle β2i may be set larger than the outer second concave angle β2e. A larger cutting load is likely to be applied to the outer portion 38e compared to the inner portion 38i. However, if the outer second concave angle β2e is set larger than the inner second concave angle β2i, the durability of the outer portion 38e can be increased. Furthermore, since the inner second concave angle β2i is larger than the outer second concave angle β2e, it is easy to avoid the overall cutting load applied to the second bottom cutting edge 38 becoming excessively large.

At least a portion of the outer portion 38e of the second bottom blade 38 may be farther from the rear end 12b of the body 12 than the radially outer end of the first bottom blade 30. In this case, the cutting load applied to the first bottom blade 30, which is the child blade, is suppressed, thereby increasing the durability of the first bottom blade 30. Here, at least a portion of the inner portion 38i of the second bottom blade 38 may be closer to the rear end 12b of the body than the radially inner end of the first bottom blade 30. In this case, excessive variation in the cutting load applied to the first bottom blade 30 and the cutting load applied to the second bottom blade 38 is avoided.

The fourth bottom blade 54 has an outer portion 54e located radially outward and an inner portion 54i located radially inward. At least a portion of the outer portion 54e of the fourth bottom blade 54 may be farther away from the rear end 12b of the body 12 than the radially outer end of the first bottom blade 30 as the first cutting edge. When the fourth bottom blade 54 is viewed from the side, the inclination angle of the outer portion 54e relative to the rotation axis S is the outer fourth concave angle β4e, and the inclination angle of the inner portion 54i relative to the rotation axis S is the inner fourth concave angle β4i.

In this case, the inner fourth concave angle β4i may be set larger than the outer fourth concave angle β4e. A larger cutting load is likely to be applied to the outer portion 54e compared to the inner portion 54i. However, if the outer fourth concave angle β4e is set larger than the inner fourth concave angle β4i, the durability of the outer portion 54e can be increased. Furthermore, since the inner fourth concave angle β4i is larger than the outer second concave angle β4e, it is easy to avoid the overall cutting load applied to the fourth bottom cutting edge 54 becoming excessively large.

At least a portion of the inner portion 54i of the fourth bottom blade 54 may be closer to the rear end 12b of the body than the radially inner end of the first bottom blade 30. In this case, excessive variation in the cutting load applied to the first bottom blade 30 and the cutting load applied to the fourth bottom blade 54 is avoided.

<Modification 2 of the embodiment of the present disclosure>
A second modification of the embodiment of the present disclosure will be described with reference to Fig. 9. Fig. 9 is a partial side view of an end mill according to the second modification of the embodiment.

As shown in FIG. 9, in the second modification of this embodiment, the radially outer end of the second bottom blade 38 as the second cutting blade may be closer to the rear end 12b of the body 12 than the radially outer end of the first bottom blade 30. The radially outer end of the fourth bottom blade 54 may be closer to the rear end 12b of the body 12 than the radially outer end of the first bottom blade 30. In this case, the machined surface of the machined product is more likely to be formed by the second bottom blade 38 and/or the fourth bottom blade 54. Therefore, the surface quality of the machined surface can be improved. This modification is effective when it is required to produce a machined product with good surface quality.

<Modification 3 of the embodiment of the present disclosure>
A third modification of the embodiment of the present disclosure will be described with reference to Fig. 10. Fig. 10 is a partial side view of an end mill according to the third modification of the embodiment.

As shown in FIG. 10, in Modification 3 of this embodiment, the third division angle θ3 may be set smaller than the first division angle θ1. When the third division angle θ3 is a value different from the first division angle θ1 in this way, chatter vibration can be suppressed. The third bottom cutting edge 46 is inclined relative to the radial direction so as to approach the rear end 12b of the body 12 as it approaches the rotation axis. The first concave angle β1 may be set smaller than the third concave angle β3. When the concave angles are set in this way, the surface quality of the machined surface can be improved.

<Method of manufacturing machined product according to embodiment of the present disclosure>
A method for manufacturing a machined product according to an embodiment of the present disclosure will be described with reference to Figures 11 to 14. Figures 11 to 14 are schematic diagrams for explaining a method for manufacturing a machined product according to an embodiment.

As shown in Figures 11 to 14, the manufacturing method of the machined product according to this embodiment is a method for manufacturing a machined product M, which is a workpiece W that has already been machined, and includes a first step, a second step, and a third step. The first step is a step of rotating an end mill 10 as a rotating tool. The second step is a step of bringing the rotating end mill 10 into contact with the workpiece W. The third step is a step of removing the end mill 10 from the workpiece W. The specific contents of the manufacturing method of the machined product according to this embodiment are as follows.

As shown in Figures 11 and 12, the end mill 10 is rotated in the rotation direction T of the rotation axis S while being moved in the direction of the arrow D1 to approach the workpiece W. Next, as shown in Figure 13, the rotating end mill 10 is moved in the direction of the arrow D2 while being in contact with the workpiece W. This causes the cutting process (turning process) of the workpiece W to be performed, and the multiple peripheral cutting edges 24 form a side cutting surface Ws on the workpiece W, while the multiple bottom cutting edges 18 form a bottom cutting surface Wf on the workpiece W.

Then, as shown in FIG. 14, the end mill 10 is moved in the direction of the arrow D3 to move it away from the workpiece W. This completes the cutting of the workpiece W, and a machined product M, which is the workpiece W that has been machined, can be produced. Because the end mill 10 has excellent cutting capabilities for the reasons described above, a machined product M with excellent machining accuracy can be produced.

To continue the cutting process, the end mill 10 can be repeatedly brought into contact with different locations of the workpiece W while rotating. In this embodiment, the end mill 10 is brought close to the workpiece W, but since it is sufficient that the end mill 10 and the workpiece W are relatively close to each other, for example, the workpiece W may be brought close to the end mill 10. This also applies when the end mill 10 is moved away from the workpiece W.

The invention according to this disclosure has been described above based on the drawings and examples. However, the invention according to this disclosure is not limited to the above-mentioned embodiments. In other words, the invention according to this disclosure can be modified in various ways within the scope of this disclosure, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the invention according to this disclosure. In other words, it should be noted that a person skilled in the art can easily make various modifications or corrections based on this disclosure. It should also be noted that these modifications or corrections are included in the scope of this disclosure.

10 End mill (rotary tool)
12 Main body 12a Tip (first end)
12b Rear end (second end)
14 Cutting portion 16 Shank portion 18 Bottom edge (cutting edge)
20 Chisel edge 22 Discharge groove 24 Outer peripheral blade (cutting blade)
30 First bottom blade (first cutting blade, child blade)
38 Second end blade (second cutting blade, parent blade)
38e Outer part (first part)
38i Inner part (second part)
46 Third bottom blade (third cutting blade, child blade)
54 Fourth bottom blade (fourth cutting blade, parent blade)
54e Outer part (first part)
54i Inner part (second part)
S Rotation axis T Rotation direction θ1 First division angle θ2 Second division angle θ3 Third division angle α1 First rake angle α2 Second rake angle β1 First concave angle β2 Second concave angle β2e Outer second concave angle β2i Inner second concave angle β3 Third concave angle β4 Fourth concave angle β4e Outer fourth concave angle β4i Inner fourth concave angle W Workpiece Wf Bottom machining surface Ws Side machining surface M Cutting workpiece

Claims (6)

A cylindrical body extends along a rotation axis from a first end to a second end and has a cutting portion on the first end side.
The cutting portion is
A plurality of cutting edges located on a first end side of the main body;
a chisel edge located on a first end side of the body and passing through the rotation axis;
a plurality of discharge grooves each extending from the plurality of cutting edges toward the second end of the body;
The plurality of cutting edges include
A first cutting edge extending from an outer periphery side toward the rotation shaft;
a second cutting edge located forward of the first cutting edge in a rotation direction of the rotation shaft and extending from an outer circumferential side toward the rotation shaft;
a third cutting edge located forward of the second cutting edge in a rotation direction of the rotation shaft and extending from an outer circumferential side toward the rotation shaft,
The second cutting edge is a main edge that extends to the chisel edge,
The first cutting edge and the third cutting edge are each a sub-edge extending to a position away from the chisel edge,
When viewed from the front toward the first end of the main body, a division angle between the first cutting edge and the second cutting edge is defined as a first division angle, and a division angle between the second cutting edge and the third cutting edge is defined as a second division angle, the second division angle is set to be larger than the first division angle,
The first cutting edge is perpendicular to the rotation axis or inclined relative to a radial direction so as to approach the second end of the body as it approaches the rotation axis,
the second cutting edge is inclined with respect to the radial direction so as to approach the second end of the body as it approaches the rotation axis,
When an inclination angle of the first cutting edge with respect to the rotation axis when the first cutting edge is viewed from the side is defined as a first concave angle, and an inclination angle of the second cutting edge with respect to the rotation axis when the second cutting edge is viewed from the side is defined as a second concave angle, the first concave angle is set to be smaller than the second concave angle ,
a radially outer end of the second cutting edge is farther from the second end of the body than a radially outer end of the first cutting edge;
The second cutting edge is
A first portion located radially outward;
a second portion located radially inward,
a rotating tool, in which when the second cutting edge is viewed from the side, an inclination angle of the first portion with respect to the rotation axis is defined as an outer second concave angle, and an inclination angle of the second portion with respect to the rotation axis is defined as an inner second concave angle, the inner second concave angle being set to be larger than the outer second concave angle . At least a portion of the first portion is farther from the second end of the body than a radially outer end of the first cutting edge,
The rotary tool according to claim 1 , wherein at least a portion of the second portion is closer to the second end of the body than a radially inner end of the first cutting edge. 3. The rotary tool according to claim 1, wherein when a rake angle of the first cutting edge is a first rake angle and a rake angle of the second cutting edge is a second rake angle, the first rake angle is set to be larger than the second rake angle. The plurality of cutting edges include
The fourth cutting edge is located forward of the third cutting edge in the rotation direction of the rotation shaft and extends from an outer circumferential side toward the rotation shaft,
When a division angle between the third cutting edge and the fourth cutting edge when viewed from the front toward the first end of the main body is defined as a third division angle, the third division angle is set to be smaller than the first division angle,
the third cutting edge is inclined with respect to the radial direction so as to approach the second end of the body as it approaches the rotation axis,
4. The rotating tool according to claim 1, wherein when an inclination angle of the third cutting edge with respect to the rotation axis when the third cutting edge is viewed from the side is defined as a third concave angle, the first concave angle is set to be smaller than the third concave angle. The plurality of cutting edges include
The fourth cutting edge is located forward of the third cutting edge in the rotation direction of the rotation shaft and extends from an outer circumferential side toward the rotation shaft,
When a division angle between the third cutting edge and the fourth cutting edge when viewed from the front toward the first end of the main body is defined as a third division angle, the third division angle is set to be the same as the first division angle,
The third cutting edge is perpendicular to the rotation axis or inclined with respect to the radial direction so as to approach the second end of the body as it approaches the rotation axis,
4. The rotating tool according to claim 1, wherein when an inclination angle of the third cutting edge with respect to the rotation axis when viewed from the side is defined as a third concave angle, the third concave angle is set to be the same as the first concave angle. A step of rotating the rotary tool according to any one of claims 1 to 5 ;
contacting the rotating rotary tool with a workpiece;
and removing the rotating tool from the workpiece.

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