Rotary cutting tool, insert and holder

Abstract

The purpose of the present invention is to improve centering accuracy in a rotary cutting tool in which a holder and an insert are separated from each other, and to suppress cost. In a rotary cutting tool, an insert is provided with: a cutting edge formed on at least one of one end and a side surface; a convex portion formed at the other end portion; and a through hole penetrating in the axial direction of the blade, the convex portion has a tapered surface such that the outer diameter becomes smaller from one end side to the other end side, the holder has a long shape, and a recessed portion is formed at one end of the fixed blade, and the recessed portion includes: a receiving portion that is a recessed receiving portion for receiving the convex portion and has a tapered seat surface formed thereon, and the receiving portion is provided with a through hole that penetrates the through hole in the axial direction of the blade; the inner diameter is increased from the other end part side to the one end part side; and a female screw portion located further toward the other end of the holder than the accommodating portion, the opening end of the female screw portion being connected to the accommodating portion.

Description

Technical Field

[0001] The present invention relates to a rotary cutting tool, a blade, and a holder. Background Art

[0002] Rotary cutting tools such as end mills are known (for example, refer to Patent Documents 1 to 3). In the end mill described in Patent Document 1, a shank and an end mill body are fixed by screwing, where the end mill body having an outer peripheral edge is screwed into an internal thread portion formed in the shank. In the blade detachable rotary tool described in Patent Document 2, a body and a blade are fixed by screwing an installation screw that penetrates the blade into an internal thread portion formed in the body. In the rotary tool described in Patent Document 3, a shank and a replacement tool are fixed by screwing an installation screw that penetrates the replacement tool into an internal thread portion formed in the shank.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: International Publication No. 2019 / 188135

[0006] Patent Document 2: Japanese Patent No. 5731643

[0007] Patent Document 3: Japanese Patent No. 4791826

[0008] If a holder such as a shank mounted on the device side and a blade having a cutting edge formed at the tip are manufactured as an integral tool, then in the case of blade breakage, the entire tool needs to be replaced, so the manufacturing cost becomes high. Therefore, as described in Patent Documents 1 to 3, by separating the holder and the blade, the manufacturing cost of the rotary cutting tool can be suppressed.

[0009] However, in the tools described in Patent Documents 1 and 2, since the alignment of the central axis of the holder and the central axis of the blade is determined by the screwed internal thread portion and the external thread portion, there is room for improvement in centering accuracy. In addition, in the end mill described in Cited Document 1, since the external thread portion is brazed to the blade, in order to improve the centering accuracy, it is also necessary to improve the accuracy during brazing. In addition, in the rotary tool described in Patent Document 3, in order to fit the holder and the blade, a fitting shape that is symmetric with respect to the central axis is formed on the holder and the blade. By forming the fitting shape on the holder and the blade, the centering accuracy is improved, but the machining cost is incurred for machining the complex fitting shape. Summary of the Invention

[0010] The present invention has been made to solve at least a part of the above problems, and an object thereof is to suppress costs while improving centering accuracy in a rotary cutting tool in which a holder and a blade are separate bodies.

[0011] The present invention is accomplished to solve at least a part of the above problems and can be implemented in the following manner.

[0012] (1) According to one aspect of the present invention, there is provided a rotary cutting tool including a holder and a blade fixed to the holder. In this rotary cutting tool, the blade includes: a cutting edge formed on at least one of an axial end portion and a side surface of the blade; a convex portion formed at the other axial end portion of the blade and protruding along the axial direction of the blade; and a through hole penetrating the blade along the axial direction of the blade. The convex portion has a tapered surface such that an outer diameter of the convex portion becomes smaller as it goes from the one end side to the other end side of the blade. The holder has a long strip shape, and a concave portion recessed along the axial direction of the holder is formed at one end portion for fixing the blade. The concave portion includes: a receiving portion which is a concave receiving portion for receiving the convex portion of the blade and has a tapered seat surface formed such that an inner diameter becomes larger as it goes from the other end side to the one end side of the holder; and an internal thread portion located on the other end side of the holder with respect to the receiving portion and formed along the axial direction of the holder. An open end portion of the internal thread portion is connected to the receiving portion.

[0013] According to this structure, a screw is inserted through the through hole of the blade, and an external thread portion of the inserted screw is screwed with the internal thread portion of the holder, thereby fixing the blade to the holder. That is, since the holder and the blade are formed separately, in the case where the cutting edge of the blade is damaged, it is only necessary to replace the blade without replacing the entire rotary cutting tool including the holder. In particular, in the case where the holder and the blade are integrated and centerless machining is performed on the holder, such centerless machining is not required when replacing the blade in this structure. In addition, the blade can be replaced in a state where the holder is mounted on a device for rotating the rotary cutting tool, and thus the time for adjusting the origin of the rotary cutting tool with respect to the device can be shortened. As a result, the cost of the rotary cutting tool and the manufacturing cost of a component cut by the tool can be suppressed. Further, when the external thread portion and the internal thread portion are tightened, the tapered seat surface formed in the receiving portion of the holder contacts the tapered surface formed in the convex portion of the blade. If it is rotated in the direction of tightening the screw after the contact, the holder and the blade approach each other in the axial direction, and the alignment of the central axes of both is performed by the contact between the tapered seat surface and the tapered surface. In this structure, since the shapes of the tapered seat surface formed on the holder and the tapered surface formed on the blade are not complicated, the machining of the concave portion of the holder and the convex portion of the blade becomes simple. Moreover, since positioning is performed by the fitting of the tapered seat surface and the tapered surface, the center offset of the blade with respect to the holder can be suppressed.

[0014] (2) In the rotary cutting tool described in the above method (1), in the longitudinal section of the holder including the axis of the holder, the angle formed by the tapered seat surface and the axis of the holder may be 30 degrees or more and 60 degrees or less.

[0015] According to this structure, since the angle formed by the tapered seat surface and the axis of the holder is 30 degrees or more, the wall thickness of the portion where the recess is formed in the holder does not become too thin, and a decrease in the rigidity of the holder can be suppressed. In addition, since the angle formed by the tapered seat surface and the axis of the holder is 60 degrees or less, it is possible to suppress the center offset of the cutting blade with respect to the holder during fastening, and it is possible to suppress the cutting blade from being inclined and fixed with respect to the holder.

[0016] (3) In the rotary cutting tool described in the above method (1) or method (2), the cutting blade is fixed to the holder by a bolt that is inserted through the through hole and screwed into the internal thread portion, and the rotary cutting tool may further include an anti-rotation mechanism that restricts relative rotation of the cutting blade with respect to the holder about the axis of the holder.

[0017] According to this structure, the anti-rotation mechanism restricts the cutting blade fixed to the holder from rotating about the axis with respect to the holder, so that the function of the rotary cutting tool can be fully exerted.

[0018] (4) In the rotary cutting tool described in any one of the above methods (1) to (3), for the through hole, the inner diameter on the one end side of the cutting blade may be larger than the inner diameter on the other end side, and an engagement surface is formed at the position where the inner diameter is switched.

[0019] According to this structure, the head of the bolt inserted through the through hole can be hooked on the engagement surface. Thereby, the position of the bolt with respect to the cutting blade in the axial direction can be restricted.

[0020] (5) In the rotary cutting tool described in any one of the above methods (1) to (4), the cutting edge may also be an end mill having at least one of an outer peripheral edge and a bottom edge.

[0021] According to this structure, an end mill with reduced cost can be provided.

[0022] (6) According to another aspect of the present invention, there is provided a cutting blade used by being fixed to a holder of a rotary cutting tool. In this cutting blade, there are provided: a cutting edge formed at one end of the cutting blade in the axial direction; a convex portion formed at the other end of the cutting blade in the axial direction, protruding along the axial direction of the cutting blade; and a through hole penetrating the cutting blade along the axial direction of the cutting blade, and the convex portion has a tapered surface such that the outer diameter of the convex portion becomes smaller as it goes from the one end side to the other end side of the cutting blade.

[0023] According to this structure, in the case where a holder having a conical seat surface that engages with the conical surface of the blade has an internal thread portion formed on the opposite side of the conical seat surface facing the blade, the blade is fixed to the holder by screwing a screw inserted through the through-hole with the internal thread portion. Therefore, in the case where the cutting edge of the blade is damaged, it is possible to replace only the blade without replacing the holder that fixes the blade. As a result, the cost of the rotary cutting tool can be suppressed. In addition, since the positioning of the blade relative to the holder is determined by a conical surface with a simple shape, the processing of the holder and the processing of the blade become simple. Moreover, since positioning is performed using the conical surface, the center offset of the blade relative to the holder can be suppressed.

[0024] (7) According to still another aspect of the present invention, there is provided a holder for a rotary cutting tool for fixing a blade. In this holder, it has a long strip shape, and at least one of an end portion and a side surface for fixing the blade is formed with a recess that is recessed along the axial direction of the holder. The recess includes: a receiving portion, which is a concave receiving portion for receiving at least a part of the blade, and is formed with a conical seat surface such that the inner diameter increases from the other end side of the holder toward the one end side; and an internal thread portion, which is located on the other end side of the holder compared to the receiving portion and is formed along the axial direction of the holder, and an open end of the internal thread portion is connected to the receiving portion.

[0025] According to this structure, in the case where a blade having a conical surface that engages with the conical seat surface of the holder is formed with a through-hole through which a screw can be inserted, the screw inserted through the through-hole is screwed with the internal thread portion, thereby fixing the blade to the holder. Therefore, in the case where the cutting edge of the blade fixed to the holder is damaged, it is only necessary to replace the blade. As a result, the cost of the rotary cutting tool can be suppressed. In addition, since the positioning of the blade relative to the holder is determined by a conical seat surface with a simple shape, the processing of the holder and the processing of the blade become simple. Moreover, since positioning is performed through the conical seat surface, the center offset of the blade fixed to the holder can be suppressed.

[0026] In addition, the present invention can be implemented in various ways. For example, it can be implemented in the form of a rotary cutting tool, a holder, a blade, an end mill, a reamer, a cutting tool, and a system including them, a method for manufacturing a rotary cutting tool, and a system including them, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic perspective view of a rotary cutting tool as an embodiment of the present invention.

[0028] Figure 2 is a schematic exploded perspective view of the rotary cutting tool.

[0029] Figure 3It is a schematic cross-sectional view of a rotary cutting tool.

[0030] Figure 4 It is a schematic exploded perspective view of a holder and a blade of a second embodiment.

[0031] Figure 5 It is a schematic cross-sectional view of a rotary cutting tool of a second embodiment.

[0032] Figure 6 It is a schematic exploded perspective view of a holder and a blade of a third embodiment.

[0033] Figure 7 It is a magnified perspective view of a recess of a holder of a third embodiment.

[0034] Figure 8 It is a schematic cross-sectional view of a rotary cutting tool of a third embodiment.

[0035] Figure 9 It is a schematic exploded perspective view of a holder and a blade of a fourth embodiment.

[0036] Figure 10 It is a schematic cross-sectional view of a rotary cutting tool of a fourth embodiment.

[0037] Explanation of reference numerals

[0038] 10, 10a, 10b... Holders

[0039] 10ca... Step portion

[0040] 10cb... Small-diameter portion

[0041] 11, 11a, 11b... Recesses

[0042] 12, 12a, 12b... Tapered seat surfaces

[0043] 13... Internal thread portion

[0044] 14, 14a... Bottom surfaces of recesses

[0045] 15, 15a... Pin holes

[0046] 16... Protruding portion

[0047] 16c... Protruding surface

[0048] 16s... Inclined surface

[0049] 17... End face

[0050] 18... Insertion hole

[0051] 20, 20a, 20b, 20c... Blades

[0052] 21, 21a, 21b, 21c... convex portions

[0053] 21A, 21Aa, 21Ab, 21Ac... conical surfaces

[0054] 21B, 21Ba, 21Bb, 21Bc... bottom surfaces of convex portions

[0055] 21C, 21Ca, 21cb... notches

[0056] 21Cc... grooves

[0057] 21Dc... stepped portions

[0058] 24... through holes

[0059] 24A... holes on the base end side

[0060] 24B... holes on the front end side

[0061] 25... cutting edges

[0062] 25b... bottom edges

[0063] 25o... outer peripheral edges

[0064] 30... bolts

[0065] 31... external thread portions

[0066] 32... heads

[0067] 40, 40a... pins

[0068] 50... anti-rotation pins

[0069] 50c... front end portions

[0070] 100, 100a, 100b... rotary cutting tools

[0071] OL1... central axis of the rotary cutting tool

[0072] OL 2, OL 2a... central axes of pin holes

[0073] ST... step (engagement surface). Detailed implementation manners

[0074] Figure 1It is a schematic perspective view of a rotary cutting tool 100 as an embodiment of the present invention. In the rotary cutting tool 100 of the present embodiment, a holder 10 that is mounted on a device and rotates about a central axis OL1 and a blade 20 that has a cutting edge 25 formed on its outer peripheral surface and is mounted on the holder 10 are configured as detachable components. Therefore, even if the cutting edge 25 is damaged due to its lifespan or the like, as long as the damaged blade 20 is removed and replaced with a new blade 20, the holder 10 does not need to be replaced. Thus, the cost of the rotary cutting tool 100 can be suppressed.

[0075] As Figure 1 shown, the rotary cutting tool 100 of the present embodiment includes: a blade 20 having a cutting edge 25 formed at one end in the axial direction of the central axis OL1, a holder 10 having a long strip shape along the central axis OL1, a bolt 30 that fixes the blade 20 to the holder 10 by bolt fastening, and a cylindrical pin 40. In Figure 1 , the holder 10, the blade 20, and the bolt 30 are fixed such that the central axis of the holder 10, the central axis of the blade 20, and the central axis of the bolt 30 respectively overlap with the central axis OL1. In addition, hereinafter, the side of the holder 10 along the central axis OL1 is also referred to as the base end side, and the side of the blade 10 is also referred to as the front end side.

[0076] Figure 2 It is a schematic exploded perspective view of the rotary cutting tool 100. As Figure 2 shown, in addition to the cutting edge 25, the blade 20 further includes a convex portion 21 that protrudes along the central axis OL1 on the base end side and a through hole 24 that penetrates the blade 20 along the central axis OL1. The cutting edge 25 has a bottom edge 25b formed on the front end side end surface of the blade 20 and an outer peripheral edge 25o formed on the outer peripheral side surface of the front end side. In addition, the rotary cutting tool 100 of the present embodiment is an end mill that rotates about the central axis OL1.

[0077] Figure 3 It is a schematic cross-sectional view of the rotary cutting tool 100. Figure 3 It shows a longitudinal section passing through the central axis OL1 and parallel to the central axis OL1. The convex portion 21 has a tapered surface 21A that is a part of a conical surface centered on the central axis OL1 formed on the front end side, a bottom surface 21B formed on the base end side and orthogonal to the central axis OL1, and a notch 21C formed on a part of the tapered surface 21A. The tapered surface 21A is a conical surface whose outer diameter of the convex portion 21 decreases along the central axis OL1 from the front end side to the base end side. The tapered surface 21A is formed by machining with reference to the central axis of the blade (the same axis as the central axis OL1 in Figures 1 to 3 ) as a reference. The notch 21C is a surface obtained by cutting off a part of the tapered surface 21A along an axis orthogonal to the radial direction of the bottom surface 21B. In addition, details of the notch 21C will be described later together with the pin 40.

[0078] As Figure 3 shown, the through-hole 24 formed in the blade 20 has a base-end-side hole 24A formed on the base-end side along the central axis OL1 and a tip-end-side hole 24B that is connected to the base-end-side hole 24A and formed on the tip-end side along the central axis OL1. The base-end-side hole 24A and the tip-end-side hole 24B are holes in which circular cross-sections with different inner diameters extend along the central axis OL1. The inner diameter of the base-end-side hole 24A is smaller than the inner diameter of the tip-end-side hole 24B. Therefore, as Figure 3 shown, a step (engagement surface) ST is formed at the position where the inner diameters of the base-end-side hole 24A and the tip-end-side hole 24B are switched. The inner diameter of the base-end-side hole 24A is larger than the cross-sectional inner diameter of the external thread portion 31 of the bolt 30 and smaller than the cross-sectional inner diameter of the head 32 of the bolt 30. The inner diameter of the tip-end-side hole 24B is larger than the cross-sectional inner diameter of the external thread portion 31 and the cross-sectional inner diameter of the head 32. Therefore, the head 32 of the bolt 30 inserted from the tip-end side of the through-hole 24 is restricted in its position along the central axis OL1 by the step ST. In addition, the length along the central axis OL1 of the tip-end-side hole 24B is formed such that, in a state where the bolt 30 fixes the blade 20 to the holding member 10, the tip-end-side end surface of the bolt 30 is located on the base-end side with respect to the tip-end-side end surface of the blade 20.

[0079] As Figure 2 shown, the holding member 10 is a member having a circular cross-section orthogonal to the central axis OL1. A recess 11 recessed along the central axis OL1 is formed on the tip-end side of the holding member 10. A cylindrical pin hole 15 that is orthogonal to the central axis OL1 and penetrates along the central axis OL2 is formed in the holding member 10. The central axis OL2 is an axis orthogonal to the radial direction of the cross-section of the holding member 10. A pin 40 is inserted into the pin hole 15. In addition, in Figure 2 , illustration of the pin 40 inserted into the pin hole 15 is omitted.

[0080] As Figure 3 shown, the recess 11 is formed by a tapered seat surface 12, a bottom surface 14, and an internal thread portion 13. The tapered seat surface 12 is a part of a conical surface with the central axis OL1 formed on the tip-end side of the recess 11 as its axis. The inner diameter of the tapered seat surface 12 increases along the central axis OL1 from the base-end side toward the tip-end side. The tapered seat surface 12 is machined with reference to the central axis of the holding member 10 (the same axis as the central axis OL1 in Figures 1 to 3 ). The bottom surface 14 is a circular plane that is connected to the base-end side of the tapered seat surface 12 and orthogonal to the central axis OL1.

[0081] As Figure 3As shown, the inner diameter of the front end side of the conical seat surface 12 is larger than the inner diameter of the bottom surface 21B of the proximal end side in the convex portion 21 of the blade 20, and is smaller than the inner diameter of the front end side in the conical surface 21A of the convex portion 21. Further, the inner diameter of the bottom surface 14 in the concave portion 11 is smaller than the inner diameter of the bottom surface 21B of the convex portion 21. Therefore, at least a part of the convex portion 21 is received in the concave receiving portion formed by the conical seat surface 12 and the bottom surface 14, and the bottom surface 21B of the convex portion 21 does not contact the bottom surface 14 of the concave portion 11. Further, as Figure 3 shown, a part of the conical seat surface 12 and the bottom surface 14 is cut to form a pin hole 15. In the present embodiment, in the longitudinal section of the holder 10 including the central axis OL1, the angle formed by the conical seat surface 12 and the central axis OL1 is 30 degrees. The angle formed by the conical surface 21A of the blade 20 and the central axis OL1 is the same as the conical seat surface of the holder 10, which is 30 degrees.

[0082] As Figure 3 shown, the internal thread portion 13 is formed at the central portion of the bottom surface 14 and extends toward the proximal end side along the central axis OL1. In other words, the internal thread portion 13 is formed on the proximal end side compared with the conical seat surface 12 and the bottom surface 14. The open end portion of the front end side of the internal thread portion 13 is connected to the proximal end side of the bottom surface 14.

[0083] The shape of the pin 40 inserted into the pin hole 15 of the holder 10 is shorter than the total length of the pin hole 15, and has a cross section with an outer diameter slightly smaller than the inner diameter of the pin hole 15. Figure 3 The shown longitudinal section is a cross section orthogonal to the central axis OL2 of the pin hole 15. As Figure 3 shown, in the state where the pin 40 is inserted into the pin hole 15 and the blade 20 is fixed to the holder 10, the portion of the cylindrical side surface of the pin 40 located at the most front end side is located on the front end side compared with the surface of the bottom surface 21B of the blade 20. In Figure 3 the shown state, the convex portion 21 of the blade 20 does not contact the pin 40 through the cutout 21C formed in the blade 20. However, from Figure 3 the shown state, when the blade 20 rotates relative to the holder 10 about the central axis OL1, the cutout 21C in the convex portion 21 contacts the pin 40. When the conical surface 21C contacts the pin 40, the relative rotation of the blade is restricted by this contact. That is, the pin 40 inserted into the pin hole 15 formed in the holder 10 functions as a rotation preventing mechanism that restricts the relative rotation of the blade 20 fixed to the holder 10 about the central axis OL1 relative to the holder 10.

[0084] From Figure 2Starting from the state where the shown blade 20 is not fixed to the holder 10, in order to fix the blade 20 to the holder 10, first, the bolt 30 is inserted through the through-hole 24 from the front end side of the blade 20 where the cutting edge 25 is formed. The external thread portion 31 of the bolt 30 inserted through the through-hole 24 and exposed from the base end side of the through-hole 24 is inserted into the internal thread portion 13 in the recess 11 of the holder 10. When the inserted bolt 30 is rotated in the tightening direction around the central axis OL1, the blade 20 moves together with the bolt 30 along the central axis OL1 toward the base end side of the holder 10. When the bolt 30 and the blade 20 move a certain amount, the tapered surface 21A in the convex portion 21 of the blade 20 starts to contact the tapered seat surface 12 in the recess 11 of the holder 10. When further rotated in the direction of tightening the bolt, through the contact between the tapered seat surface 12 of the recess 11 and the tapered surface 21A of the convex portion 21, the alignment of the central axis of the holder having the recess 11 and the central axis of the blade 20 having the convex portion 21 is performed. After fixing the blade 20 to a non-movable position relative to the holder 10, by inserting the pin 40 into the pin hole 15 of the holder 10, the rotation of the blade 20 fixed relative to the holder 10 around the central axis OL1 is restricted. In order to remove the blade 20 fixed to the holder 10, it is only necessary to rotate the bolt 30 around the central axis OL1 in the loosening direction.

[0085] As described above, in the rotary cutting tool 100 of the present embodiment, the blade 20 includes a convex portion 21 protruding along the central axis OL1 on the proximal end side and a through hole 24 penetrating the blade 20 along the central axis OL1. The tapered surface 21A formed on the convex portion 21 is a conical surface whose outer diameter decreases along the central axis OL1 from the front end side to the proximal end side. On the front end side of the holder 10 that fixes the blade 20, a concave portion 11 is formed that depresses along the central axis OL1. The tapered seat surface 12 formed in the concave portion 11 has an inner diameter that increases along the central axis OL1 from the proximal end side to the front end side. Therefore, at least a part of the convex portion 21 is accommodated in the concave accommodation portion formed by the tapered seat surface 12 and the bottom surface 14. In addition, the internal thread portion 13 is formed on the proximal end side with respect to the tapered seat surface 12 and the bottom surface 14. In the rotary cutting tool 100 of the present embodiment, a bolt 30 is inserted through the through hole 24 of the blade 20, and the external thread portion 31 of the inserted bolt 30 is screwed with the internal thread portion 13 of the holder 10, thereby fixing the blade 20 to the holder 10. That is, since the holder 10 and the blade 20 are formed separately, in the case where the cutting edge 25 of the blade 20 is damaged, it is only necessary to replace the blade 20 without replacing the entire rotary cutting tool 100 including the holder 10. In particular, the non-centering machining performed on the holder 10 in the case where the holder 10 and the blade 20 are integrated is not required when replacing the blade 20 in the present embodiment. In addition, the blade 20 can be replaced in a state where the holder 10 is mounted on a device that rotates the rotary cutting tool 100, so that the time for adjusting the origin of the rotary cutting tool 100 with respect to the device can be shortened. As a result, the cost of the rotary cutting tool 100 and the manufacturing cost of the component cut by the rotary cutting tool 100 can be suppressed. In addition, when the external thread portion 31 and the internal thread portion 13 are tightened, the tapered seat surface 12 formed in the accommodation portion of the holder 10 comes into contact with the tapered surface 21A formed in the convex portion 21 of the blade 20. If the bolt 30 is rotated in the tightening direction after the contact, the holder 10 and the blade 20 approach each other along the central axis OL1, and the alignment of their central axes is performed by the contact between the tapered seat surface 12 and the tapered surface 21A. In the present embodiment, since the shapes of the tapered seat surface 12 formed in the holder 10 and the tapered surface 21A formed in the blade 20 are not complicated, the machining of the concave portion 11 of the holder 10 and the convex portion 21 of the blade 20 becomes simple. Moreover, since positioning is performed by the fitting of the tapered seat surface 12 and the tapered surface 21A, the center offset of the blade 20 with respect to the holder 10 can be suppressed.

[0086] In addition, in the present embodiment, in the longitudinal section of the holder 10 including the central axis OL1, the angle formed by the tapered seat surface 12 and the central axis OL1 is 30 degrees. In the present embodiment, since the angle formed by the tapered seat surface 12 and the central axis OL1 of the holder 10 is 30 degrees, the wall thickness of the portion of the holder 10 where the recess 11 is formed does not become too thin, and a reduction in the rigidity of the holder 10 can be suppressed. In addition, since the angle formed by the tapered seat surface 12 and the central axis OL1 of the holder 10 is 60 degrees or less, the center offset of the blade 20 relative to the holder 10 during fastening can be suppressed, and the blade 20 can be suppressed from being fixed to the holder 10 obliquely.

[0087] In addition, in the present embodiment, the pin 40 inserted into the pin hole 15 formed in the holder 10 functions as an anti-rotation mechanism that restricts the relative rotation of the blade 20 fixed to the holder 10 about the central axis OL1 with respect to the holder 10. That is, since the fixed blade 20 is suppressed from rotating about the central axis OL1 relative to the holder 10, the rotary cutting tool 100 can fully function as a tool.

[0088] In addition, in the blade 20 of the present embodiment, a step ST is formed at the position where the inner diameters of the proximal-side hole 24A and the distal-side hole 24B in the through-hole 24 are switched. Therefore, the head 32 of the bolt 30 inserted into the through-hole 24 can be hooked on the step ST. Thereby, the position of the bolt 30 relative to the blade 20 along the central axis OL1 can be restricted.

[0089] <Second Embodiment>

[0090] Figure 4 FIG. is a schematic exploded perspective view of the holder 10a and the blade 20a of the second embodiment. Figure 5 FIG. is a schematic cross-sectional view of the rotary cutting tool 100a of the second embodiment. In the rotary cutting tool 100a of the second embodiment, the anti-rotation mechanism of the blade 20a is different from that of the rotary cutting tool 100 of the first embodiment. Therefore, in the second embodiment, the anti-rotation mechanism different from that of the first embodiment will be described, and the description of the structure identical to that of the first embodiment will be omitted.

[0091] As Figure 4 shown, in the holder 10a of the second embodiment, a pin hole 15a is formed along the radial direction of the cross-section along the central axis OL1 and along the central axis OL2a. Figure 5 FIG. shows a longitudinal section parallel to both the central axis OL1 and the central axis OL2a. As Figure 4 , Figure 5As shown, the pin hole 15a is different from the pin hole 15 of the first embodiment and does not penetrate the entire holding member 10a along the cross-section of the holding member 10a. Through the pin hole 15a, a part of the tapered seat surface 12a and the bottom surface 14a of the concave portion 11a is cut off. The pin 40a has a circular cross-section slightly smaller than the pin hole 15a, as Figure 5 shown, and has a cylindrical shape extending along the central axis OL2a.

[0092] As Figure 4 , 5 shown, a notch 21Ca is formed in the convex portion 21a. As Figure 5 shown, the notch 21Ca is formed at a position where the convex portion 21a does not contact the pin 40a in a state where the pin 40a is inserted into the pin hole 15a and the blade 20a is fixed to the holding member 10a. Similar to the first embodiment, the surface of the bottom surface 21Ba of the blade 20a is located on the front end side compared to the portion of the cylindrical side surface of the pin 40a located on the most front end side. Therefore, when the blade 20a rotates relative to the holding member 10a about the central axis OL1, the notch 21Ca in the convex portion 21a contacts the pin 40a. That is, the pin 40a inserted into the pin hole 15a formed in the holding member 10a functions as an anti-rotation mechanism.

[0093] <Third Embodiment>

[0094] Figure 6 is a schematic exploded perspective view of the holding member 10b and the blade 20b of the third embodiment. Figure 7 is an enlarged perspective view of the concave portion 11b of the holding member 10b of the third embodiment. Figure 8 is a schematic cross-sectional view of the rotary cutting tool 100b of the third embodiment. In the rotary cutting tool 100b of the third embodiment, compared with the rotary cutting tool 100 of the first embodiment and the rotary cutting tool 100a of the second embodiment, the anti-rotation mechanism of the blade 20b is different. Therefore, in the third embodiment, the anti-rotation mechanism different from those of the first and second embodiments will be described, and the description of the structures identical to those of the first and second embodiments will be omitted.

[0095] Figure 7 represents Figure 6 the schematic enlarged perspective view of the concave portion 11b shown. As Figure 7 shown, in the holding member 10b of the third embodiment, an end face 17 connecting the concave portion 11b and the outer peripheral surface of the holding member 10b is formed. The end face 17 has a shape in which the hollow portion of the concave portion 11b is hollowed out with respect to a circle orthogonal to the central axis OL1. The end face 17 is located on the most front end side in the holding member 10b.

[0096] As Figure 7As shown, a protrusion 16 that protrudes toward the radially inner side is formed on a part of the tapered seat surface 12b of the recess 11b. The protrusion 16 has a protruding surface 16c that protrudes from the end surface 17 toward the radially inner side along a cross section parallel to the end surface 17, and an inclined surface 16s that is connected to the protruding surface 16c. As Figure 8 shown, the inclined surface 16s is an inclined surface that faces the center as it goes toward the proximal end side from the connected protruding surface 16c. The inclined surface 16s is connected to the opening end surface of the internal thread portion 13.

[0097] As Figure 8 shown, a cutout 21Cb that cuts off a part of the tapered surface 21Ab is formed in a part of the convex portion 21b of the blade 20b. Figure 8 shown, the cutout 21Cb is an inclined surface formed so as to engage with the inclined surface 16s of the protrusion 16 when the blade 20b is fixed to the holder 10b. Specifically, the cutout 21Cb is an inclined surface that approaches the center as it becomes the proximal end side. In addition, the angle formed by the inclined surface of the cutout 21C with the central axis OL1 is the same as the angle formed by the inclined surface 16s of the holder 10b with the central axis OL1.

[0098] As Figure 8 shown, the protrusion 16 in the recess 11b of the holder 10b protrudes more toward the radially inner side than the tapered seat surface 12b and the tapered surface 21Ab in the convex portion 21b of the blade 20b. Therefore, when the blade 20b rotates relative to the holder 10b about the central axis OL1, the protrusion 16 comes into contact with the tapered surface 21Cb. That is, the protrusion 16 formed in the recess 11b of the holder 10b functions as an anti-rotation mechanism.

[0099] <Fourth Embodiment>

[0100] Figure 9 is a schematic exploded perspective view of the holder 10c and the blade 20c of the fourth embodiment. Figure 10 is a schematic cross-sectional view of the rotary cutting tool 100c of the fourth embodiment. In the rotary cutting tool 100c of the fourth embodiment, the anti-rotation mechanism of the blade 20c is different from that of the rotary cutting tool 100 of the first embodiment and the rotary cutting tools 100b of the second and third embodiments. Therefore, in the fourth embodiment, the anti-rotation mechanism different from that of the first to third embodiments will be described, and the description of the same structures as those of the first to third embodiments will be omitted.

[0101] As Figure 9 shown, in the holder 10c of the fourth embodiment, an end surface 17 that connects the recess 11c and the outer peripheral surface of the holder 10c is formed. The end surface 17 has a shape in which the hollow portion of the recess 11c is hollowed out with respect to a circle orthogonal to the central axis OL1. The end surface 17 is located on the foremost end side in the holder 10c.

[0102] As shown Figure 10 in part of the tapered seat surface 12c that forms the concave portion 11c, an insertion hole 18 formed from the front end side toward the base end side is formed in a direction parallel to the rotation axis OL1. The insertion hole 18 and the through hole 24 are separated by a partition wall. A rotation prevention pin 50 that protrudes from the insertion hole 18 onto the tapered seat surface 12c is inserted (pressed) into the insertion hole 18. Additionally, for the insertion hole 18 and the rotation prevention pin 50, as the best embodiment, as shown in this embodiment, their cross-sections are circular, but in the present invention, the cross-sectional shape of the insertion hole is not limited to this and also includes polygons. Further, in the present embodiment, the insertion hole 18 is formed to penetrate from the front end side toward the base end side in the holding member 10c, but this represents the best embodiment and it is not necessary to penetrate. As long as the rotation prevention pin described later can be inserted, it can also be formed by a detent hole.

[0103] As shown Figure 10 in part of the convex portion 21c of the blade 20c, a groove 21Cc is formed by cutting off a part of the tapered surface 21Ac in a square shape. As shown Figure 9 in the groove 21Cc is a engaging groove formed in such a way that when the blade 20c is fixed to the holding member 10c, it engages with the rotation prevention pin 50 inserted into the insertion hole 18. Specifically, the cutout 21Cc is formed by penetrating a part of the convex portion 21c of the blade 20c toward the through hole 24.

[0104] As shown Figure 10 the rotation prevention pin 50 inserted into the insertion hole 18 in the concave portion 11c of the holding member 10c protrudes more toward the radial center side than the tapered seat surface 12c and the tapered surface 21Ac in the convex portion 21c of the blade 20c. Therefore, when the blade 20c rotates relative to the holding member 10c around the central axis OL1, the rotation prevention pin 50 comes into contact with the groove 21Cc of the tapered surface 21c. That is, the front end portion 50c of the pin 50 formed in the concave portion 11c of the holding member 10c (the portion protruding more than the tapered seat surface 12c) functions as a rotation prevention mechanism.

[0105] According to the rotation prevention mechanism of such a present embodiment, by pressing the rotation prevention pin 50 in a direction perpendicular to the holding member 10c, that is, in a direction parallel to the rotation axis OL1, even when a load caused by the rotation of a tool is applied to the rotation prevention pin 50 during use, the rotation prevention pin 50 will not fall off and can play a role in preventing rotation when the blade 20c is in use.

[0106] In addition, by forming a groove 21Cc on the conical surface 21c in contact with the front end portion 50c of the rotation prevention pin 50, even if a force in the rotation direction, that is, a lateral force with respect to the axial direction of the rotation prevention pin 50, is applied to the front end portion 50c, the lateral sides of the front end portion 50c of the rotation prevention pin 50 can be held by both side walls of the groove 21Cc. In this regard, it may also be constituted by the cutout 21C shown in other embodiments. However, in this case, assuming that a lateral force is applied to the axial direction of the rotation prevention pin 50, when a force is applied in the rotation direction of the blade 20c, an oblique force is generated at the front end portion 50c of the rotation prevention pin 50, and a force is applied to the blade 20c in the upward floating direction, causing the blade 20c to tilt. Therefore, the groove structure shown in this embodiment is the optimal embodiment.

[0107] In addition, the holding member 10c of the present embodiment forms a stepped portion 10ca on the front end side rather than the base end side of the peripheral surface. With the stepped portion 10ca as the boundary, a reduced-diameter portion 10cb with a smaller diameter of the holding member 10c is formed on the front end side. By forming this reduced-diameter portion 10cb, the outer shape of the holding member 10c becomes relatively thinner compared to the outer diameter of the blade 20c. Therefore, it is effective in preventing the holding member 10c from contacting the workpiece during machining. However, when the outer shape of the holding members 10, 10a, or 10b shown in the first to third embodiments is directly thinned to form the reduced-diameter portion 10cb, the wall thickness at the end of the end face 17 of the holding member 10c becomes thinner, and there is a concern about a reduction in strength when supporting the blade 20c during cutting.

[0108] Therefore, in order to ensure the wall thickness, reducing the size of the conical surface was considered. However, in this embodiment, since the same-sized blades as those in the first to third embodiments are also used, the size of the conical surface becomes smaller compared to the size of the blade 20c. Therefore, there is a concern that the blade 20c will float, and the contact area between the holding member and the blade cannot be sufficiently ensured. In this case, in order to ensure the contact area between the holding member and the blade, it is necessary to reduce the conical size on the blade side. However, reducing the overall size of the blade will result in a shorter cutting edge on the side surface of the blade, which limits the cutting during machining.

[0109] Therefore, in the present embodiment, as Figure 9 and Figure 10 shown, by forming a stepped portion 21Dc between the convex portion 21c and the cutting edge of the blade 20c, as a stepped blade, it is possible to ensure the length of the cutting edge on the side surface and reduce the size of the conical surface 21Ac. Therefore, it is possible to ensure the contact area between the holding member 10c and the blade 20c while also ensuring the length of the cutting edge.

[0110] <Modification Example of the Present Embodiment>

[0111] The present invention is not limited to the above-described embodiments and can be implemented in various ways without departing from its gist. For example, the following modifications can be made.

[0112] In the above-described first embodiment, the rotary cutting tool 100 including the holder 10 having the recess 11 formed therein, the blade 20 having the convex portion 21 that houses at least a part thereof in the recess 11, and the bolt 30 that is inserted through the through-hole 24 of the blade 20 and screwed into the internal thread portion 13 of the holder 10 has been described as an example. However, the structure of the rotary cutting tool 100 can be modified. For example, the rotary cutting tool 100 can be composed only of the holder 10 and the blade 20 and does not include the bolt 30 and the pin 40. The rotary cutting tool 100 can be a tool other than an end mill, and can also be a tool such as a reamer or a cutter. It is sufficient that the cutting edge 25 has at least one of the outer peripheral edge 25o and the bottom edge 25b. In addition, only the holder 10 or the blade 20 can be circulated as a component of the rotary cutting tool 100.

[0113] In the above-described first embodiment, the angles formed by the tapered seat surface 12 of the holder 10 and the tapered surface 21A of the blade 20 with respect to the central axis of each component are 30 degrees, respectively. However, they can be less than 30 degrees or greater than 30 degrees. In order to suppress a decrease in the rigidity of the holder 10, the angle formed by the tapered seat surface 12 with respect to the central axis is preferably 30 degrees or more. In addition, in order to stabilize the yaw (tilt) of the cutting edge 25 of the blade 20 fixed to the holder 10, the angle formed by the tapered seat surface 12 with respect to the central axis is preferably 60 degrees or less. The anti-rotation mechanism in each of the above-described first to third embodiments is an example, and a known structure can be used. In addition, in each of the above-described first to third embodiments, for convenience, the central axis of the holder 10 and the central axis of the blade 20 are overlapped with the central axis OL1 and described as the same axis.

[0114] In the above-described first embodiment, the step ST at the position where the inner diameters of the proximal-side hole 24A and the distal-side hole 24B formed in the through-hole 24 are switched restricts the position of the head 32 of the bolt 30 inserted through the through-hole 24 along the central axis OL1. However, the shape of the engaging surface that engages with the head 32 of the bolt 30 to restrict the position of the bolt 30 can be a shape other than the step ST and can be modified. For example, the inner diameter of the proximal-side hole 24A can also be a tapered surface formed by a cone that gradually decreases toward the opening end surface of the distal-side hole 24B.

[0115] As described above, the present mode has been described based on the embodiments and modification examples. However, the embodiments of the above mode are for facilitating the understanding of the present mode and do not limit the present mode. The present invention can be changed and improved without departing from the scope of its gist and claims, and the present mode includes its equivalents. In addition, if the technical features are not described as necessary in this specification, they can be appropriately deleted.

Claims

1. A rotary cutting tool comprising a holder and a blade fixed to the holder, wherein: The blade has: a cutting edge formed on at least one of an end portion and a side surface of the blade in the axial direction; a convex portion formed at the other end of the blade in the axial direction and protruding along the axial direction of the blade; and a through hole, which penetrates the blade along the axial direction of the blade, The convex portion has a tapered surface so that the outer diameter of the convex portion decreases from the one end side of the blade to the other end side, The retainer has a long strip shape, and a concave portion is formed at one end portion where the blade is fixed, and is concave along the axial direction of the retainer. The recess has: an accommodating portion which is a concave accommodating portion for accommodating the convex portion of the blade, and is formed with a tapered seat surface so that the inner diameter increases as it moves from the other end side of the holder toward the one end side; and The internal thread portion is located on the other end side of the holder relative to the accommodation portion, is formed along the axial direction of the holder, and forms an open end portion in the accommodation portion.

2. The rotary cutting tool according to claim 1, characterized in that In a longitudinal section of the holder including the axis of the holder, an angle formed by the tapered seat surface and the axis of the holder is greater than or equal to 30 degrees and less than or equal to 60 degrees.

3. The rotary cutting tool according to claim 2, characterized in that: The blade is fixed to the holder by a bolt inserted through the through hole and screwed into the internal thread portion. The rotary cutting tool further includes a rotation-stopping mechanism for restricting relative rotation of the blade with respect to the holder around the axis of the holder.

4. The rotary cutting tool according to claim 3, characterized in that: The through hole has an inner diameter on the one end side of the insert larger than an inner diameter on the other end side, and an engagement surface is formed at a position where the inner diameter switches.

5. The rotary cutting tool according to any one of claims 1 to 4, characterized in that: The rotary cutting tool is an end mill having the cutting edge.

6. A blade, which is fixed to a holder of a rotary cutting tool for use, characterized in that: The blade has: a cutting edge formed on at least one of an end portion and a side surface of the blade in the axial direction; a convex portion formed at the other end of the blade in the axial direction and protruding along the axial direction of the blade; and a through hole, which penetrates the blade along the axial direction of the blade, The convex portion has a tapered surface such that an outer diameter of the convex portion decreases from the one end side toward the other end side of the insert.

7. A holder for a rotating cutting tool and a fixed blade, characterized in that: The retainer has a long strip shape, and a concave portion recessed along the axial direction of the retainer is formed at at least one of an end portion and a side surface where the blade is fixed. The recess has: an accommodation portion which is a concave accommodation portion for accommodating at least a portion of the blade, and is formed with a tapered seat surface so that the inner diameter increases as it moves from the other end side of the holder toward the one end side; and The internal thread portion is located on the other end side of the holder relative to the accommodation portion, is formed along the axial direction of the holder, and forms an open end portion in the accommodation portion.

Images