Tool body and rotary cutting tool

Abstract

To provide a tool body and a rotary cutting tool that can achieve multiple blades while maintaining high rigidity.SOLUTION: A tool body 10 has a central section 40 which is assembled to an arbor 30 and is rotated around a center axis Ax. The tool body has a plurality of recesses 60 provided along a circumferential direction between the central portion 40 and an outer peripheral section 50 in a front view from an opposite side of the assembling side to the arbor 30. The recess 60 has a cross-sectional shape which is gradually narrowed in a depth direction.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a tool body and a rotary cutting tool.

Background Art

[0002] Patent Document 1 discloses a technique for reducing the weight by forming a plurality of through holes in a rotary cutting tool such as a milling cutter. Patent Document 2 discloses a face milling cutter having a tool body with a plurality of recesses and a concave pocket formed in the outer peripheral portion of the tip.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a rotary cutting tool having a plurality of through holes as in the technique described in Patent Document 1, the weight cannot be sufficiently reduced, and the overall rigidity is lowered.

[0005] On the other hand, in the technique described in Patent Document 2, by forming a concave pocket also in the outer peripheral portion of the tip together with a plurality of recesses, sufficient weight reduction can be achieved while ensuring the overall rigidity. However, the strength of the outer peripheral portion where the cutting edge is provided is lowered, and the number of cutting edges provided on the outer peripheral portion is limited.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a tool body and a rotary cutting tool capable of increasing the number of blades while maintaining high rigidity.

Means for Solving the Problems

[0007] A tool body according to an aspect of the present invention is a tool body whose central portion is assembled to a spindle and rotated about a central axis. In a front view from the side opposite to the assembly side to the spindle, a plurality of recesses provided along the circumferential direction are formed between the central portion and the outer peripheral portion, and the recesses have a cross-sectional shape that gradually narrows in the depth direction.

[0008] In the tool body having the above structure, a plurality of recesses are provided along the circumferential direction between the central portion and the outer peripheral portion in a front view. Moreover, the recesses have a cross-sectional shape that gradually narrows in the depth direction. Thereby, it is possible to achieve weight reduction while suppressing a decrease in rigidity due to the provision of the recesses. Further, since a plurality of recesses are provided between the central portion and the outer peripheral portion, it is possible to suppress a decrease in rigidity in the outer peripheral portion where the cutting edge is provided and a reduction in the number of cutting edges of the cutting edge provided on the outer peripheral portion as compared with a structure in which the outer peripheral portion is hollowed out.

[0009] In the axial direction, the bottom of the recess, the front end of the central portion, and the front end of the outer peripheral portion may be arranged in this order from the assembly side to the spindle.

[0010] The recess may have an outer peripheral side inclined surface that gradually inclines toward the front side in the radially outward direction.

[0011] The recess may have an inner peripheral side inclined surface that gradually inclines toward the assembly side in the radially outward direction on the central portion side rather than the outer peripheral side inclined surface, and the inclination angle of the outer peripheral side inclined surface with respect to a plane orthogonal to the central axis may be larger than that of the inner peripheral side inclined surface.

[0012] In a cross section taken along a virtual straight line connecting the deepest point of the bottom of the recess and the central axis in a front view, the inclination angle of the outer peripheral side inclined surface may be larger than the inclination angle of the inner peripheral side inclined surface.

[0013] In a cross-sectional view, the recess may have a portion formed in a V shape.

[0014] The V-shaped portion in the concave portion has a front inclined surface on the front side in the rotation direction and a rear inclined surface on the rear side in the rotation direction, and the front inclined surface may have an inclination angle with respect to a plane orthogonal to the central axis that is larger than that of the rear inclined surface.

[0015] In a front view, the concave portion may have a tapered portion that gradually becomes thinner toward the outer peripheral portion.

[0016] The rotary cutting tool according to one aspect of the present invention includes the above-described tool body and a cutting edge provided on the outer peripheral portion of the tool body.

Advantages of the Invention

[0017] According to the present invention, there are provided a tool body and a rotary cutting tool that can be multi-edged while maintaining high rigidity.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0019] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. As shown in FIGS. 1 to 3, the tool body 10 according to this embodiment is formed in a disk shape. This tool body 10 is, for example, the body of a rotary cutting tool 100 such as a face mill used for performing cutting on a workpiece. The tool body 10 is fixed to and assembled with an arbor 30 by a fastening component 20.

[0020] The arbor 30 is, for example, attached to a machine tool such as a machining center and has a boss portion 31. A cylindrical mounting shaft 32 having a hole portion 33 with an internal thread formed on its inner peripheral surface is provided in the boss portion 31.

[0021] The fastening component 20 is a bolt for fixing the tool body 10 to the arbor 30 and is fastened to the mounting shaft 32 formed in the boss portion 31 of the arbor 30. The fastening component 20 has a shaft portion 21 and a head portion 22. An external thread is formed on the outer peripheral surface of the shaft portion 21. The head portion 22 is formed in a disk shape with a larger diameter than the shaft portion 21. An engagement hole 23 is formed at the center of the head portion 22. The engagement hole 23 is, for example, a tool hole such as a hexagonal hole or a Torx (registered trademark) hole into which a tool such as a wrench can be inserted.

[0022] The tool body 10 has a front surface 10a and a back surface 10b, and the back surface 10b side is assembled to the arbor 30. The arbor 30 has an annular recess extending in the circumferential direction between a central portion 40 and an outer peripheral portion 50 in a front view, and this recess portion is an annular depression 55.

[0023] The tool body 10 has a mounting hole 41 at its central portion 40. The mounting shaft 32 provided in the boss portion 31 of the arbor 30 is inserted into this mounting hole 41. Then, the shaft portion 21 of the fastening component 20 is screwed into the hole portion 33 of the mounting shaft 32 inserted into this mounting hole 41 and fastened. Thereby, the central portion 40 of the tool body 10 is fixed to and assembled with the arbor 30 by the fastening component 20. Note that between the tool body 10 and the mounting shaft 32 of the boss portion 31, keys and key grooves (not shown) that engage with each other are provided to transmit the rotational force of the arbor 30 to the tool body 10.

[0024] On the tool body 10, a plurality of cutting edges 51 are provided on the front surface 10a side of the outer peripheral portion 50 thereof. A plurality of chip seats 52 are formed on the outer peripheral portion 50 of the tool body 10. These chip seats 52 are arranged at intervals in the circumferential direction, and a cutting chip 53 is mounted on each chip seat 52. Then, by mounting the cutting chips 53 on these chip seats 52, a rotary cutting tool 100 having a plurality of cutting edges 51 provided on the outer peripheral portion 50 of the tool body 10 is formed. Note that the rotary cutting tool 100 may have a configuration in which the cutting edges 51 are directly provided on the outer peripheral portion 50 of the tool body 10.

[0025] As described above, the rotary cutting tool 100 is assembled to the arbor 30 with the back surface 10b side, which is the side for assembling the tool body 10 to the arbor 30, facing the arbor 30. Then, the rotary cutting tool 100 is rotated together with the arbor 30 in the rotational direction R around the central axis Ax (see FIG. 3), and cutting is performed on the workpiece by the cutting edges 51 provided on the front surface 10a side of the outer peripheral portion 50 of the tool body 10.

[0026] As shown in FIGS. 4 to 6, the tool body 10 has a plurality of recesses 60 in a front view. These recesses 60 are provided along the circumferential direction between the central portion 40 and the outer peripheral portion 50 of the tool body 10. These recesses 60 are shaped to be further recessed from the bottom of the annular recessed portion 55 between the central portion 40 and the outer peripheral portion 50. In this way, the tool body 10 is lightened by providing a plurality of recesses 60 between its central portion 40 and outer peripheral portion 50. Note that although a part of the recesses 60 adjacent to each other in the circumferential direction communicate with each other on the central portion 40 side, these recesses 60 adjacent to each other in the circumferential direction may be provided at intervals from each other.

[0027] FIG. 5 shows a cross section taken along a virtual straight line orthogonal to the extending direction of the recess 60 on the central portion 40 side of the tool body 10 (section V-V in FIG. 3). As shown in FIG. 5, the recess 60 formed in the tool body 10 has a cross-sectional shape that gradually narrows in the depth direction.

[0028] Here, as the recess formed in the tool body 10, even if the cross-sectional shape does not gradually narrow in the depth direction, the weight reduction of the tool body 10 can be achieved. That is, for the weight reduction of the tool body 10, the removed volume due to forming the recess contributes. Therefore, if the removed volumes are the same, as the cross-sectional shape of the recess, a rectangular shape having a constant width in the depth direction can achieve a similar weight reduction. And when forming a recess with a rectangular cross-section, between the recesses, a portion with a rectangular cross-section having the same width dimension is formed along the axial direction of the tool body 10.

[0029] On the other hand, if a recess 60 having a cross-sectional shape that gradually narrows in the depth direction is formed as in this embodiment, in the tool body 10, a triangular cross-section portion Pt is formed between the recesses 60 (see FIG. 5). This triangular cross-section portion Pt, compared with the rectangular cross-section portion formed when providing a recess with a rectangular shape having a constant width in the depth direction, even if the removed volume due to forming the recess is the same, the width of the root portion becomes larger and high strength is maintained. Therefore, according to the tool body 10 of this embodiment in which the recess 60 having a cross-sectional shape that gradually narrows in the depth direction is formed, while suppressing a decrease in the rigidity of the tool body 10 and ensuring high strength against deflection, weight reduction is achieved.

[0030] FIG. 6 shows a cross-section (section VI-VI in FIG. 3) taken along a virtual straight line connecting a point at the deepest part of the bottom 60a of the recess 60 and the central axis Ax. Note that the point at the deepest part of the bottom 60a of the recess 60 is the point closest to the back surface 10b in the recess 60, and includes the vicinity of that point. In the cross-sectional view of FIG. 6, the tool body 10, in the axial direction, is arranged in the order of the back surface 10b on the assembly side to the arbor 30, the bottom 60a of the recess 60, the end surface on the front surface 10a side in the central part 40 having the contact part 40a where the fastening part 20 contacts, and the end surface on the front surface 10a side in the outer peripheral part 50 where the cutting edge 51 is provided. That is, in the tool body 10, the relationship among the dimension H1 from the back surface 10b of the arbor 30 to the bottom 60a of the recess 60, the dimension H2 from the back surface 10b of the arbor 30 to the end surface on the front surface 10a side in the central part 40, and the dimension H3 from the back surface 10b of the arbor 30 to the end surface on the front surface 10a side in the outer peripheral part 50 is H1 < H2 < H3.

[0031] By setting such dimensions, the tool body 10 can sufficiently secure the wall thickness of the outer peripheral part 50 that requires the highest rigidity due to a large force being applied during cutting and maintain high strength. Further, the tool body 10 can also sufficiently secure the wall thickness and maintain high strength in the central part 40 that requires high rigidity because it is assembled to the arbor 30 by the fastening part 20. And the tool body 10 can achieve weight reduction by providing the recess 60 while maintaining the outer peripheral part 50 and the central part 40 at high strength.

[0032] Also, as shown in FIG. 6, the recess 60 has an outer peripheral side inclined surface 61 that gradually inclines toward the front surface 10a side of the tool body 10 in the radially outward direction. Further, the recess 60 has an inner peripheral side inclined surface 62 that gradually inclines toward the back surface 10b side of the tool body 10 in the radially outward direction on the central part 40 side rather than the outer peripheral side inclined surface 61. And the inclination angle θ1 of the outer peripheral side inclined surface 61 with respect to the plane S orthogonal to the central axis Ax is made larger than the inclination angle θ2 of the inner peripheral side inclined surface 62 with respect to the plane S orthogonal to the central axis Ax.

[0033] Here, when machining a workpiece with the rotary cutting tool 100, in some cases, a fluid such as coolant supplied through the arbor 30 is discharged radially outward from the center portion 40 side of the tool body 10 toward the cutting location by the cutting edge 51. In such a case, in the tool body 10 having the recess 60 with the outer peripheral side inclined surface 61, the fluid discharged from the center portion 40 side can be smoothly guided along the outer peripheral side inclined surface 61 of the recess 60 to the outer peripheral portion 50 side where the cutting edge 51 is provided. Thereby, the fluid can be smoothly supplied to the cutting edge 51 of the outer peripheral portion 50 for cooling and lubrication.

[0034] In particular, the recess 60 has an inner peripheral side inclined surface 62 that is inclined radially outward and gradually toward the back surface 10b side of the tool body 10 on the center portion 40 side rather than the outer peripheral side inclined surface 61. By inclining the center portion 40 side rather than the outer peripheral side inclined surface 61 toward the back surface 10b side in this way, the fluid discharged radially outward from the center portion 40 of the tool body 10 can be guided to the outer peripheral side inclined surface 61 without disturbing the injection of the fluid. Then, the fluid guided to the outer peripheral side inclined surface 61 is then guided to the outer peripheral portion 50 side of the tool body 10 where the cutting edge 51 is provided along the outer peripheral side inclined surface 61 having an inclination angle θ1 larger than the inclination angle θ2 of the inner peripheral side inclined surface 62. Thereby, the fluid can be more smoothly supplied to the cutting edge 51 of the outer peripheral portion 50 for cooling and lubrication. Note that the outer peripheral side inclined surface 61 that directly guides the fluid to the cutting edge 51 can better guide the fluid to the cutting edge 51 by changing the direction as the inclination angle θ1 is larger. For this reason, the inclination angle θ1 of the outer peripheral side inclined surface 61 is made larger than the inclination angle θ2 of the inner peripheral side inclined surface 62 provided so as not to disturb the injection of the fluid.

[0035] Also, as shown in FIG. 5, the recess 60 is formed in a V shape on the center portion 40 side of the tool body 10, so that the fluid discharged radially outward from the center portion 40 side can be more smoothly guided to the outer peripheral portion 50 side where the cutting edge 51 is provided, and further, the chip discharge property during cutting by the cutting edge 51 of the outer peripheral portion 50 can be improved.

[0036] Here, on the center portion 40 side of the tool body 10, the recess 60 formed in a V shape has a front inclined surface 65 on the front side in the rotation direction R and a rear inclined surface 66 on the rear side in the rotation direction R. And, the inclination angle θ3 of the front inclined surface 65 with respect to the plane S orthogonal to the central axis Ax is made larger than the inclination angle θ4 of the rear inclined surface 66 with respect to the plane S orthogonal to the central axis Ax. By forming the recess 60 in a V shape with such a front inclined surface 65 and rear inclined surface 66, the fluid can be more smoothly guided to the cutting edge 51 of the outer peripheral portion 50, and the discharge property of the chips generated during cutting can be further improved.

[0037] Also, as shown in FIG. 3, the recess 60 has a tapered portion 64 that gradually becomes narrower toward the outer peripheral portion 50 of the tool body 10 in a front view of the tool body 10. By providing the tapered portion 64 in the recess 60 in this way, the flow velocity of the fluid discharged from the center portion 40 side of the tool body 10 toward the radially outer side and entering the recess 60 can be increased at the tapered portion 64. Further, by providing the tapered portion 64 in the recess 60, the wall thickness at the outer peripheral portion 50 can be maintained. Thereby, while securing the wall thickness on the outer peripheral portion 50 side between the recesses 60 and maintaining the rigidity, the fluid can be guided better to the outer peripheral portion 50 provided with the cutting edge 51 of the tool body 10.

[0038] As described above, according to the tool body 10 according to the present embodiment and the rotary cutting tool 100 including the same, a plurality of recesses 60 are provided along the circumferential direction between the center portion 40 and the outer peripheral portion 50 in a front view. Moreover, the recess 60 has a cross-sectional shape that gradually narrows in the depth direction. Thereby, it is possible to achieve weight reduction while suppressing a decrease in the rigidity of the tool body 10 due to the provision of the recess 60. Further, since a plurality of recesses 60 are provided between the center portion 40 and the outer peripheral portion 50 of the tool body 10, compared with a structure in which the outer peripheral portion 50 is hollowed out, a decrease in the rigidity of the outer peripheral portion 50 provided with the cutting edge 51 and a reduction in the number of cutting edges of the cutting edge 51 provided on the outer peripheral portion 50 can be suppressed.

Explanation of reference numerals

[0039] 10 Tool body 10a Front surface 30 Arbor 40 Central part 51 Cutting edge 60 Recess 60a Bottom 61 Outer peripheral inclined surface 62 Inner peripheral inclined surface 64 Tapered part 65 Front side inclined surface 66 Rear side inclined surface 100 Rotary cutting tool Ax Central axis R Rotation direction θ1, θ2 Inclination angles θ3, θ4 Inclination angles

Claims

1. A tool body having a central portion assembled to an arbor and rotated about a central axis, In a front view from the side opposite to the assembly side to the arbor, between the central portion and the outer peripheral portion, having a plurality of recesses provided along the circumferential direction, The recess has a cross-sectional shape that gradually narrows in the depth direction, Tool body.

2. In the axial direction, the bottom of the recess, the front end portion on the front side in the central portion, and the front end portion on the front side in the outer peripheral portion are arranged in order from the assembly side to the arbor, The tool body according to claim 1.

3. The recess has an outer peripheral side inclined surface that gradually inclines toward the front side in the radial outward direction, The tool body according to claim 1.

4. The recess has an inner peripheral side inclined surface that gradually inclines toward the assembly side in the radial outward direction on the central portion side rather than the outer peripheral side inclined surface, The inclination angle of the outer peripheral side inclined surface with respect to a plane orthogonal to the central axis is made larger than that of the inner peripheral side inclined surface, The tool body according to claim 3.

5. In a cross-section along a virtual straight line connecting the deepest point of the bottom of the recess in a front view and the central axis, the inclination angle of the outer peripheral side inclined surface is made larger than the inclined surface of the inner peripheral side inclined surface, The tool body according to claim 4.

6. In a cross-sectional view, the recess has a portion formed in a V shape, The tool body according to claim 1.

7. The V-shaped portion in the recess has a front side inclined surface on the front side in the rotation direction and a rear side inclined surface on the rear side in the rotation direction, The inclination angle of the front side inclined surface with respect to a plane orthogonal to the central axis is made larger than that of the rear side inclined surface, The tool body according to claim 6.

8. In a front view, the recess has a tapered portion that gradually becomes thinner toward the outer peripheral portion, The tool body according to claim 1.

9. The tool body according to any one of claims 1 to 8, A cutting edge provided on the outer peripheral portion of the tool body, Having, Rotary cutting tool.

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