Fastening component

Abstract

To provide a fastening component which can effectively inhibit deformation caused when a hexagonal wrench is inserted into a hexagonal socket and the hexagonal wrench inserted into the hexagonal socket is rotated.SOLUTION: A fastening component 100 is fastened to an arbor 10, fixes a cutter 20 serving as a rotary cutting tool to the arbor 10, and includes: a shaft part 30 to be screwed into a female screw 13c of the arbor 10; and a hexagonal socket 40 which is formed at a shaft center AX on an end surface opposite to the fastening side to the arbor 10 and into which a hexagonal wrench 60 may be inserted. The hexagonal socket 40 has an upper surface protruding arc part 51, having a protruding arc shape, at a contact part with the hexagonal wrench 60 in a top view and has a side surface protruding arc part 52, having a protruding arc shape, in a side view.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to fastening parts.

Background Art

[0002] As a fastening part for fixing a rotary cutting tool such as a face mill, shell end mill, boring cutter, side cutter, etc. to an arbor, it is known to use a bolt with a hexagonal hole. This fastening part is fastened to and released from the arbor by inserting a hexagonal wrench into the hexagonal hole and turning it. The shape of the hexagonal hole of this bolt with a hexagonal hole includes, for example, those disclosed in Patent Documents 1 and 2.

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 the above-mentioned fastening part, when a hexagonal wrench is inserted into the hexagonal hole, if the hexagonal wrench is tilted, the tip of the hexagonal wrench contacts the inner wall surface of the hexagonal hole. As a result, the inner wall surface of the hexagonal hole or the hexagonal wrench may be deformed. Therefore, as a fastening part, further improvement in the shape of the hexagonal hole is desired to suppress deformation of the inner wall surface of the hexagonal hole and the hexagonal wrench.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a fastening part capable of effectively suppressing deformation when inserting a hexagonal wrench into a hexagonal hole and when turning the hexagonal wrench inserted into the hexagonal hole.

Means for Solving the Problems

[0006] The fastening component according to one aspect of the present invention is a fastening component that is fastened to an arbor to fix a rotary cutting tool to the arbor, and includes a shaft portion screwed into the female thread of the arbor, and a hexagonal hole formed at the shaft center on the end face opposite to the fastening side to the arbor and into which a hexagonal wrench can be inserted. The hexagonal hole has a convex arc-shaped upper surface convex arc portion at the contact portion with the hexagonal wrench in a top view, and has a convex arc-shaped side surface convex arc portion in a side view.

[0007] In the fastening component having the above structure, the hexagonal hole has a convex arc-shaped upper surface convex arc portion at the contact portion with the hexagonal wrench in a top view. For example, if the hexagonal hole is straight in a top view, when tightening with a hexagonal wrench, the edge portion of the hexagonal wrench may contact the inner wall surface of the hexagonal hole, and the edge portion or the hexagonal hole may be recessed. By having a convex arc-shaped upper surface convex arc portion at the contact portion with the hexagonal wrench in a top view, the contact area between the inner wall surface and the hexagonal wrench is increased, the stress at the contact portion is relaxed, and the occurrence of deformation such as dents in the edge portion and the inner wall surface can be suppressed. Further, in the fastening component having the above structure, the hexagonal hole has a convex arc-shaped side surface convex arc portion in a side view. For example, if the hexagonal hole is straight in a side view, when the hexagonal wrench is inserted obliquely, the tip portion of the hexagonal wrench may interfere with the inner wall surface, and the tip portion of the hexagonal wrench or the hexagonal hole may be recessed. By having a convex arc-shaped side surface convex arc portion in a side view, the hexagonal wrench can be smoothly guided into the depth of the hexagonal hole, and the occurrence of deformation such as dents in the hexagonal wrench or the hexagonal hole due to the contact of the tip portion of the hexagonal wrench with the inner wall surface of the hexagonal hole can be suppressed.

[0008] The upper surface convex arc portion may have an arc larger than the diameter of the inscribed circle of the hexagonal hole.

[0009] The side surface convex arc portion may have an arc larger than the upper surface convex arc portion.

[0010] The point closest to the shaft center of the hexagonal hole in the side surface convex arc portion may be arranged at a position not more than half of the depth of the hexagonal hole.

[0011] The side convex arc portion may be composed of at least two convex arc portions.

[0012] The side convex arc portion is composed of at least two convex arc portions, and the convex arc portion closest to the axial center of the hexagonal hole may have a larger arc than the other convex arc portions.

Advantages of the Invention

[0013] According to the present invention, there is provided a fastening component capable of effectively suppressing deformation when inserting a hexagonal wrench into a hexagonal hole and when rotating the hexagonal wrench inserted into the hexagonal hole.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

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Figure 10

Figure 11

Modes for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. As shown in FIGS. 1 and 2, the fastening component 100 according to the present embodiment is a bolt for fixing the cutter (rotary cutting tool) 20 to the arbor 10 and is fastened to the arbor 10. In this example, the case of fixing the cutter 20 to the arbor 10 is illustrated. However, the rotary cutting tool is not limited to a face mill, and may be a rotary cutting tool such as a shell end mill, a boring cutter, or a side cutter.

[0016] The arbor 10 is, for example, attached to a machine tool such as a machining center, and mainly has a shank portion 11, a flange portion 12, and a boss portion 13.

[0017] The shank portion 11 has a tapered shape and is inserted into a tapered hole (not shown) of the spindle of the machine tool. Thereby, the arbor 10 is fixed to the spindle of the machine tool.

[0018] The flange portion 12 is provided on the side opposite to the mounting side to the spindle of the machine tool with respect to the shank portion 11. The flange portion 12 has a V-groove 12a and a key groove 12b. The V-groove 12a is a groove portion that is gripped when being stored in the magazine of the automatic tool changer of the machine tool or when exchanging tools by a tool changing arm, and is formed over the circumferential direction of the flange portion 12. The key groove 12b is a groove portion into which a key (not shown) of the machine tool is locked. By being locked to the key, the arbor 10 is fixed in the circumferential direction with respect to the spindle of the machine tool.

[0019] The boss portion 13 is provided on the side opposite to the shank portion 11 with respect to the flange portion 12. The boss portion 13 has a mounting shaft 13a and a key 13b at its tip. The mounting shaft 13a is formed in a cylindrical shape having a female thread 13c on its inner peripheral surface. The key 13b is formed at two locations around the mounting shaft 13a.

[0020] The cutter 20 is a rotary cutting tool mainly used for face machining of a workpiece, and is mounted on the boss portion 13 of the arbor 10. The cutter 20 has a plurality (six in this example) of tip seats 21 and a mounting hole 22. The tip seats 21 project outward in the circumferential direction, and cutting tips 23 are respectively mounted on these tip seats 21. The mounting hole 22 is formed at the center of the cutter 20, and a mounting shaft 13a provided on the boss portion 13 of the arbor 10 is inserted into this mounting hole 22. Further, the cutter 20 has two key holes (not shown) on the mounting side to the boss portion 13 of the arbor 10, into which a key 13b provided on the boss portion 13 is engaged.

[0021] The fastening component 100 is screwed and fastened to the male thread 13c of the mounting shaft 13a of the boss portion 13 of the arbor 10 with the cutter 20 mounted on the boss portion 13 of the arbor 10. Thereby, the cutter 20 is fixed to the boss portion 13 of the arbor 10.

[0022] Next, the fastening component 100 will be described. As shown in FIGS. 3 to 5, the fastening component 100 has a shaft portion 30 and a hexagonal hole 40. The shaft portion 30 has a head portion 31 at one end. The head portion 31 is formed in a disc shape with a larger diameter than the shaft portion 30.

[0023] The fastening component 100 is formed, for example, by a metal powder sintering 3D printer that three-dimensionally forms a shaped object using metal powder. Examples of the forming method by a metal powder sintering 3D printer include powder bed fusion, electron beam melting (EBM) that melts powder using an electron beam, or selective laser melting (SLM) that melts powder using a laser beam.

[0024] The shaft portion 30 is a portion that is screwed to the mounting shaft 13a of the boss portion 13 of the arbor 10, and an external thread is formed on the outer circumference. The hexagonal hole 40 is formed at the axis center on the end face of the fastening component 100 on the side opposite to the fastening side to the arbor 10.

[0025] As shown in FIG. 6, the hexagonal hole 40 of the fastening component 100 is a hole into which a hexagonal wrench 60 can be inserted. When fastening and unfastening the fastening component 100 to the arbor 10, the operating rod portion 61 side of the hexagonal wrench 60 is inserted into this hexagonal hole 40. Then, by gripping the operating rod portion 62 of the hexagonal wrench 60 and rotating it in either direction, the fastening and unfastening of the fastening component 100 are performed.

[0026] As shown in FIG. 7, the hexagonal hole 40 has six inner wall surfaces 41. Further, between adjacent inner wall surfaces 41, relief recesses 42 are provided so that the insertion and extraction can be smoothly performed while suppressing interference with the edge portion 60a of the hexagonal wrench 60. The hexagonal hole 40 has an upper convex arc portion 51 with a convex arc shape at the contact portion with the inner wall surface 41 that the hexagonal wrench 60 contacts in a top view. This upper convex arc portion 51 bulges toward the axis center AX of the hexagonal hole 40. This upper convex arc portion 51 has an arc larger than the diameter of the inscribed circle C of the hexagonal hole 40.

[0027] As shown in FIGS. 8 and 9, in a side view, the hexagonal hole 40 has side convex arc portions 52 with a convex arc shape on each inner wall surface 41. This side convex arc portion 52 bulges toward the axis center AX of the hexagonal hole 40. This side convex arc portion 52 has an arc larger than that of the upper convex arc portion 51.

[0028] The closest contact point P closest to the axis center AX of the hexagonal hole 40 in the side convex arc portion 52 is arranged at a position where its depth Dp is less than or equal to half (1 / 2D) of the depth D of the hexagonal hole 40. Note that the shape of the end portion of the head 31 of the fastening component 30 is not limited to a flat surface and may also be a curved surface or the like. Here, in this example, the depth D of the hexagonal hole 40 is the dimension from the edge portion on the head 31 side in the hexagonal hole 40 to the edge portion on the side opposite to the head 31 on the inner wall surface 41 of the hexagonal hole 40, regardless of the shape of the end portion of the head 31.

[0029] Further, the side convex arc portion 52 is composed of two convex arc portions 52a and 52b. One of the convex arc portions 52a has a larger arc than the other convex arc portion 52b on the entrance side of the hexagonal hole 40. The closest contact point P in the side convex arc portion 52 is arranged on one of the convex arc portions 52a.

[0030] As described above, when the fastening component 100 is fastened or unfastened, the operating rod portion 61 of the hexagonal wrench 60 is inserted into the hexagonal hole 40 and rotated.

[0031] Here, if the inner wall surface 41 of the hexagonal hole 40 is a straight line in a top view, when tightening with the hexagonal wrench 60, the edge portion 60a of the hexagonal wrench 60 may contact the inner wall surface 41 of the hexagonal hole 40, and the edge portion 60a of the hexagonal wrench 60 or the inner wall surface 41 of the hexagonal hole 40 may be recessed.

[0032] On the contrary, as shown in FIG. 10, in a top view, if a top convex arc portion 51 having a convex arc shape is provided on the inner wall surface 41 of the hexagonal hole 40, which is the contact portion with the hexagonal wrench 60, the contact angle θ between the hexagonal wrench 60 and the inner wall surface 41 can be reduced. Thereby, in the contact portion with the hexagonal wrench 60, the contact area between the inner wall surface 41 and the hexagonal wrench 60 becomes larger, so that the stress is relaxed, and the occurrence of deformation such as the recess of the edge portion 60a or the inner wall surface 41 can be suppressed.

[0033] Also, if the inner wall surface 41 of the hexagonal hole 40 is a straight line in a side view, when the hexagonal wrench 60 is inserted obliquely, the tip of the hexagonal wrench 60 may interfere with the inner wall surface 41, and the hexagonal wrench 60 or the hexagonal hole 40 may be deformed.

[0034] On the contrary, as shown in FIG. 11, in a side view, by providing a side convex arc portion 52 having a convex arc shape on the inner wall surface 41 of the hexagonal hole 40, the hexagonal wrench 60 is smoothly guided into the depth of the hexagonal hole 40 by the side convex arc portion 52 in a side view. Therefore, the occurrence of deformation such as the recess of the hexagonal wrench 60 or the hexagonal hole 40 due to the contact of the tip of the hexagonal wrench 60 with the inner wall surface 41 of the hexagonal hole 40 can be suppressed.

[0035] As described above, according to the fastening component 100 according to the present embodiment, when the hexagonal wrench 60 is inserted into the hexagonal hole 40 and when fastening and unfastening are performed with the hexagonal wrench 60, generation of deformation such as deformation of the hexagonal wrench or the recess of the hexagonal hole 40 can be effectively suppressed.

[0036] In particular, since the upper surface convex arc portion 51 has an arc larger than the diameter of the inscribed circle C of the hexagonal hole 40, the contact angle C between the inner wall surface 41 of the hexagonal hole 40 and the hexagonal wrench 60 when turning the hexagonal wrench 60 inserted into the hexagonal hole 40 can be reduced. Thereby, the contact portion between the inner wall surface 41 of the hexagonal hole 40 and the hexagonal wrench 60 can be made closer to surface contact.

[0037] Also, since the side surface convex arc portion 52 has an arc larger than that of the upper surface convex arc portion 51, when the hexagonal wrench 60 is inserted into the hexagonal hole 40, it can be smoothly guided into the hexagonal hole 40 while suppressing the contact of the hexagonal wrench 60 with the inner wall surface 41 of the hexagonal hole 40.

[0038] Furthermore, since the closest contact point P closest to the axial center AX of the hexagonal hole 40 in the side surface convex arc portion 52 is arranged at a position not more than half of the depth D of the hexagonal hole 60, when the hexagonal wrench 60 is inserted obliquely, the direction of the hexagonal wrench 60 can be corrected by the side surface convex arc portion 52 toward the inside of the hexagonal hole 40 and can be guided more smoothly.

[0039] Also, the side surface convex arc portion 52 is composed of two convex arc portions 52a and 52b. Thereby, when the hexagonal wrench 60 is inserted into the hexagonal hole 40, the hexagonal wrench 60 can be guided toward the inside of the hexagonal hole 40 while suppressing deformation of the hexagonal wrench 60 or the hexagonal hole 40 due to contact by the two convex arc portions 52a and 52b of different arcs. In particular, the convex arc portion 52a closest to the axial center AX of the hexagonal hole 40 can smoothly guide the hexagonal wrench 60 toward the inside of the hexagonal hole 40.

Explanation of reference numerals

[0040] 10 Arbor 13c Fine thread 20 Cutter (rotary cutting tool) 30 Shaft portion 60 hexagon wrench 40 hexagon socket 51 upper convex arc part 52 side convex arc part 52a, 52b convex arc parts 100 fastening part AX axis center C inscribed circle D depth of hexagon socket P closest contact point

Claims

1. A fastening component that is fastened to a spindle and fixes a rotary cutting tool to the spindle, having a shaft portion screwed into the female thread of the spindle, and a hexagonal hole formed at the axis center of the end face on the side opposite to the fastening side to the spindle and into which a hexagonal wrench can be inserted, and comprising: The hexagonal hole has a convex arc-shaped upper surface convex arc portion at the contact portion with the hexagonal wrench in a top view, and a convex arc-shaped side surface convex arc portion in a side view, Fastening component.

2. The upper surface convex arc portion has an arc larger than the diameter of the inscribed circle of the hexagonal hole, The fastening component according to claim 1.

3. The side surface convex arc portion has an arc larger than the upper surface convex arc portion, The fastening component according to claim 1.

4. The point closest to the axis center of the hexagonal hole in the side surface convex arc portion is arranged at a position not more than half of the depth of the hexagonal hole, The fastening component according to claim 1.

5. The side surface convex arc portion consists of at least two convex arc portions, The fastening component according to claim 1.

6. The side surface convex arc portion consists of at least two convex arc portions, and the convex arc portion closest to the axis center of the hexagonal hole has an arc larger than the other convex arc portions, The fastening component according to claim 1.

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