Releasably-fastened cutting head, and holder for cutting head

Abstract

The present invention provides a releasably-fastened cutting head (100) comprising: a head cutting part (101) including a cutting edge; and a head fastening part (102) extended in the axial direction below the head cutting part (101) and fastened to a holder (200), wherein the head fastening part (102) includes: a head external thread (110) which is screw-coupled to a holder internal thread (210) formed on a holder (200) when the fastening part is fastened to the holder (200); a head shaft support surface (120) formed perpendicularly to the axial direction of the cutting head (100) on the bottom surface of the lower end of the head cutting part (101) so as to support a load in the axial direction when the fastening part is fastened to the holder (200); and a head radial support surface (130) which is the outer peripheral surface of the head fastening part (102), and which supports a load in the radial direction when the fastening part is fastened to the holder (200), the head radial support surface (130) including a head radial first support surface (131) formed above the head external thread (110), and a head radial second support surface (132) formed below the head external thread (110).

Description

A cutting head and a holder for the cutting head that can be releasedly engaged

[0001] The present invention relates to a cutting head that is removably connected for a cutting tool and a holder for the cutting head.

[0002] The cutting tool includes a cutting head having a cutting edge formed thereon and a holder in which the cutting head is received and secured.

[0003] For such cutting tools, the head and holder must have excellent axial alignment when connected.

[0004] Referring to FIG. 10, prior art patent publication No. 10-1965173 discloses a screw-fastened tool comprising a tool head (3) and a tool shank (4), wherein the tool shank has an external screw (5) and a support area located between the tool head (3) and the external screw (5), and the support area is formed by two conical bearing surfaces (6, 8) having different conical angles.

[0005] The cutting tool of the above prior art document establishes a support area by conical bearing surfaces (6, 8) formed adjacent to each other, and is supported axially by the bearing surface (6) and radially by the bearing surface (8). However, there was a problem in that the support area was limited by only the adjacent bearing surfaces (6, 8), so axial alignment could not be properly achieved when the tool head (3) and the tool shank (4) were connected.

[0006] <Prior Art Literature>

[0007] (Patent Document 1) Registered Patent Publication No. 10-1965173 (Published Apr. 3, 2019)

[0008] The present invention has been devised to solve the problems of the aforementioned prior art, and aims to provide a cutting head and a holder capable of accurately aligning the cutting head axially with respect to the holder when the cutting head and the holder are coupled.

[0009] In addition, the present invention aims to provide a cutting head and a holder capable of improving tool life by suppressing tool damage caused by contamination and foreign substances and suppressing vibration during processing.

[0010] A removably coupled cutting head according to the present invention for solving the above-mentioned problem comprises a head cutting portion including a cutting edge and a head fastening portion formed to extend axially below the head cutting portion and fastened to a holder, wherein the head fastening portion comprises: a head male screw that is screw-coupled with a holder female screw formed in the holder when fastened to the holder; a head axial support surface formed perpendicular to the axial direction of the cutting head on the lower bottom surface of the head cutting portion and supporting a load in the axial direction when fastened to the holder; and a head radial support surface formed on the outer surface of the head fastening portion and supporting a load in the radial direction when fastened to the holder; wherein the head radial support surface may include a head radial first support surface formed above the head male screw and a head radial second support surface formed below the head male screw.

[0011] In addition, a head fastening groove is formed in the circumferential direction on the radial support surface, and a ring-shaped elastic body is fitted into the head fastening groove. The elastic body fitted into the head fastening groove protrudes radially from the radial support surface, and when the head fastening part is fastened to the holder, the protruding portion of the elastic body undergoes elastic deformation, thereby allowing for fastening by an interference fit.

[0012] Additionally, the head fastening groove includes a first head fastening groove formed circumferentially on the first radial support surface of the head, and the elastic body may include a ring-shaped first elastic body fitted into the first head fastening groove.

[0013] Additionally, the head fastening groove includes a second head fastening groove formed circumferentially on the second radial support surface of the head, and the elastic body may include a ring-shaped second elastic body fitted into the second head fastening groove.

[0014] Additionally, the head fastening groove includes a first head fastening groove formed circumferentially on the first head radial support surface and a second head fastening groove formed circumferentially on the second head radial support surface, and the elastic body may include a first ring-shaped elastic body fitted into the first head fastening groove and a second ring-shaped elastic body fitted into the second head fastening groove.

[0015] In addition, the diameter of the second support surface in the radial direction of the head can be formed to be larger than the root diameter of the head male screw.

[0016] In addition, the axial length of the first radial support surface of the head can be formed to be 100 to 130% of the axial length of the second radial support surface of the head, and preferably can be formed to be the same as the axial length of the second radial support surface of the head.

[0017] In addition, the first radial support surface of the head is formed as a tapered shape that narrows downward, and the first radial support surface of the head has an axial length corresponding to 45 to 50% of the maximum diameter, and preferably has an axial length of 50% of the maximum diameter.

[0018] Additionally, the first radial support surface of the head is formed as a tapered shape that narrows downward, and the maximum diameter of the first radial support surface of the head is formed to be 60 to 80% of the maximum outer diameter of the head cutting portion (101), and preferably to be 73 to 76% of the maximum outer diameter of the head cutting portion.

[0019] In addition, the second support surface in the radial direction of the head can be formed in a cylindrical shape.

[0020] In addition, the diameter of the second support surface in the radial direction of the head can be formed to be smaller than the diameter of the first support surface in the radial direction of the head.

[0021] In addition, the first radial support surface of the head may be formed as a tapered shape that narrows downward, and the outer diameter of the male screw of the head may be formed to be smaller than the minimum diameter of the first radial support surface of the head.

[0022] A holder for a cutting head that is removably fastened according to the present invention for solving the above-mentioned problem comprises a holder fastening portion which is a space into which a cutting head is inserted and fastened, and a shank formed to extend axially below the holder fastening portion. The holder fastening portion comprises: a holder female screw that is screw-coupled with a head male screw formed on the cutting head when the cutting head is inserted and fastened; a holder axial support surface formed perpendicular to the axial direction of the holder on the upper surface of the holder fastening portion to support a load in the axial direction when fastened with the cutting head; and a holder radial support surface formed on the inner circumference of the holder fastening portion to support a load in the radial direction when fastened with the cutting head. The holder radial support surface may include a holder radial first support surface formed above the holder female screw and a holder radial second support surface formed below the holder female screw.

[0023] In addition, the diameter of the second radial support surface of the holder can be formed to be the same as the inner diameter of the female screw of the holder.

[0024] In addition, the second radial support surface of the holder can be formed in a cylindrical shape.

[0025] In addition, the first radial support surface of the holder may be formed as a tapered shape that narrows downward.

[0026] In addition, a head radial support surface is formed on the outer surface of the head fastening portion of the cutting head that is fastened to the holder, and the axial length of the holder radial support surface may be formed to be shorter than the axial length of the head radial support surface.

[0027] Additionally, the head radial support surface includes a head radial first support surface formed on the head male screw and a head radial second support surface formed below the head male screw, and the axial length of the holder radial first support surface may be formed to be shorter than the axial length of the head radial first support surface.

[0028] The detachably coupled cutting head and holder for the cutting head of the present invention, configured as described above, have the effect of improving axial alignment when the cutting head is coupled to the holder by forming radial support surfaces on the upper and lower sides.

[0029] In addition, by forming the above-mentioned radial support surfaces on the upper and lower sides, stress is distributed when bending occurs during processing, thereby improving the durability of the holder and minimizing bending between the cutting head and the holder, which has the effect of preventing tool breakage and holder damage.

[0030] In addition, by forming a head fastening groove in the circumferential direction on the radial support surface and configuring a ring-shaped elastic body to be fitted into the head fastening groove, it is possible to improve axial alignment during machining, reduce tool vibration caused by machining, and prevent damage to the fastening part caused by contamination and foreign substances.

[0031] In addition, the diameter of the second support surface in the radial direction of the head is formed to be larger than the root diameter of the male screw of the head, which has an advantageous effect for centering (axial alignment) and support.

[0032] FIG. 1 is a figure showing a cutting head and a head in a connected state and a head in a disconnected state according to an embodiment of the present invention.

[0033] FIG. 2 is a front view showing the structure of a cutting head according to one embodiment of the present invention,

[0034] FIGS. 3 to 5 are drawings showing embodiments in which a ring-shaped elastic body is fitted onto the radial support surface of the head of FIG. 2.

[0035] FIG. 6 is a longitudinal cross-sectional view showing the structure of a holder for a cutting head according to one embodiment of the present invention,

[0036] FIG. 7 is a longitudinal cross-sectional view of the head fastening portion of a cutting head according to one embodiment of the present invention,

[0037] FIG. 8 is a longitudinal cross-sectional view of a holder fastening portion of a holder for a cutting head according to one embodiment of the present invention,

[0038] FIG. 9 is a cross-sectional view showing the state in which the head fastening part of FIG. 7 and the holder fastening part of FIG. 8 are combined.

[0039] FIG. 10 is a longitudinal section showing the structure of a conventional cutting tool.

[0040] Hereinafter, embodiments of a removably coupled cutting head and a holder for a cutting head according to the present invention will be described in detail with reference to FIGS. 1 to 9.

[0041] FIG. 1 shows a cutting head and a head in a connected state and a disconnected state according to one embodiment of the present invention.

[0042] Referring to FIG. 1, a detachably coupled cutting head (100) according to one embodiment of the present invention includes a head cutting portion (101) including a cutting edge and a head fastening portion (102) formed to extend axially below the head cutting portion (101) and fastened to a holder (200).

[0043] Additionally, a holder (200) for a cutting head that is removably fastened according to one embodiment of the present invention includes a holder fastening portion (202) which is a space into which a cutting head (100) is inserted and fastened, and a shank (250) formed to extend axially below the holder fastening portion (202).

[0044] The cutting head (100) and the holder (200) are configured to be connected or disconnected by screw connection.

[0045] FIG. 2 shows the structure of a cutting head (100) according to one embodiment of the present invention, and FIG. 3 to 5 show embodiments in which a ring-shaped elastic body is fitted onto the radial support surface of the head of FIG. 2.

[0046] Referring to FIG. 2, a cutting head (100) according to one embodiment of the present invention includes a cutting portion (101) at the top and a head fastening portion (102) formed to extend axially at the bottom.

[0047] The head fastening portion (102) includes a head male screw (110), a head shaft support surface (120), and a head radial support surface (130).

[0048] The head male screw (110) is formed to be screw-coupled with the holder female screw (210) formed in the holder (200) when fastened to the holder (200).

[0049] The head shaft support surface (120) is formed on the lower bottom surface of the head cutting part (101) as a surface perpendicular to the axial direction of the cutting head (100), and supports a load in the axial direction when the cutting head (100) is fastened to the holder (200).

[0050] The head radial support surface (130) is formed on the outer surface of the head fastening part (102) and supports a load in the radial direction when the cutting head (100) is fastened to the holder (200).

[0051] As illustrated in FIGS. 2 to 5, the head radial support surface (130) includes a head radial first support surface (131) formed on the head male screw (110) and a head radial second support surface (132) formed below the head male screw (110).

[0052] By forming a first head radial support surface (131) at the top and a second head radial support surface (132) at the bottom with the head male screw (110) in between, the cutting head (100) is radially supported at the top and bottom respectively when fastened to the holder (200), thereby improving axial alignment.

[0053] Meanwhile, when the tool bends during processing, if the radial support surface is applied only to the upper part, stress is concentrated on that support surface. Since the holder is mostly made of steel, deformation is caused by stress concentration in the contact part of the holder, which becomes a fatal defect in using the indexable holder.

[0054] However, since the head radial support surface (130) is formed on the upper and lower sides respectively, stress is distributed when bending occurs during processing, thereby improving the durability of the holder. Additionally, when the cutting head (100) attempts to bend, the upper and lower radial support surfaces hold it in place, thereby minimizing the bending phenomenon between the cutting head (100) and the holder (200), thus preventing tool breakage and holder damage.

[0055] Meanwhile, the axial length of the first head radial support surface (131) can be formed to be 100 to 130% of the axial length of the second head radial support surface (132), and preferably can be formed to be the same as the axial length of the second head radial support surface (132).

[0056] The head radial first support surface (131) and the head radial second support surface (132) both serve for axial alignment and stress distribution, but the head radial first support surface (131) primarily serves for axial alignment, while the head radial second support surface (132) primarily serves for stress distribution. Therefore, if the head radial second support surface (132) becomes longer than the head radial first support surface (131), the role of axial alignment increases, which may be more disadvantageous for axial alignment during manufacturing. Thus, it is preferable that the axial length of the head radial first support surface (131) be formed to be equal to or longer than the axial length of the head radial second support surface (132).

[0057] The head radial first support surface (131) may be formed as a tapered shape that narrows downward, and the head radial first support surface (131) has an axial length corresponding to 45-50% of the maximum diameter, preferably an axial length of 50% of the maximum diameter.

[0058] In addition, the maximum diameter of the first radial support surface (131) of the head is formed to be 60 to 80% of the maximum outer diameter of the head cutting portion (101), and preferably to be 73 to 76% of the maximum outer diameter of the head cutting portion (101).

[0059] When the cutting head (100) is fastened to the holder (200), it is fastened in an interference fit manner. Therefore, when fastened, the first radial support surface (231) of the holder opens up and comes into contact with the first radial support surface (131) of the head, and the head shaft support surface (120) comes into contact with the shaft support surface (220) of the holder, thereby achieving axial alignment.

[0060] If the lengths of the radial first support surfaces of the head and holder increase, the area of ​​each support surface widens, requiring a large torque when fastening the head, which may result in the fastening part of the head being damaged.

[0061] Conversely, if the lengths of the radial first support surfaces of the head and holder are shortened, the area of ​​each support surface is reduced, so while a large torque is not required when fastening the head, the durability of the radial first support surface of the holder may be deteriorated.

[0062] Accordingly, the head radial first support surface (131) needs to have an appropriate range of axial length and maximum diameter as described above.

[0063] A head fastening groove (140) is formed in the circumferential direction on the radial support surface (130), and a ring-shaped elastic body (140a) is fitted into the head fastening groove (140), and the elastic body (140a) fitted into the head fastening groove (140) protrudes radially from the radial support surface (130).

[0064] When the head fastening part (102) is fastened to the holder (200), the protruding part of the elastic body (140a) is elastically deformed and fastened by an over-fit.

[0065] Referring to the embodiment of FIG. 3, the head fastening groove (140) includes a head fastening first groove (141) formed circumferentially on the head radial first support surface (131), and the elastic body (140a) includes a ring-shaped first elastic body (141a) fitted into the head fastening first groove (141).

[0066] Referring to the embodiment of FIG. 4, the head fastening groove (140) includes a second head fastening groove (142) formed circumferentially on the second head radial support surface (132), and the elastic body (140a) includes a ring-shaped second elastic body (142a) fitted into the second head fastening groove (142).

[0067] Referring to the embodiments of FIGS. 2 and FIGS. 5, the head fastening groove (140) includes a first head fastening groove (141) formed circumferentially on the first head radial support surface (131) and a second head fastening groove (142) formed circumferentially on the second head radial support surface (132). Additionally, the elastic body (140a) includes a ring-shaped first elastic body (141a) fitted into the first head fastening groove (141) and a ring-shaped second elastic body (142a) fitted into the second head fastening groove (142).

[0068] As described above, a head fastening groove (140) is formed in the circumferential direction on the radial support surface (130), and a ring-shaped elastic body (140a) is fitted into the head fastening groove (140). During processing, the elastic body (140a) acts as a damper to improve axial alignment, improve the shaking of the tool caused by processing, and prevent damage to the fastening part caused by contamination and foreign matter.

[0069] FIG. 7 shows a longitudinal cross-sectional view of the head fastening portion of a cutting head according to one embodiment of the present invention. Referring to FIG. 7, the diameter (d2) of the second radial support surface (132) of the head is formed to be larger than the root diameter (di) of the head male screw (110). The larger the diameter (d2) of the second radial support surface (132) of the head, the wider the support area becomes, which is advantageous for centering (axial alignment) and support.

[0070] Meanwhile, the second support surface (132) in the radial direction of the head is preferably formed in a cylindrical shape. By forming it in a cylindrical shape, centering (axial alignment) and bending during processing can be minimized, and the effect of stress distribution is increased.

[0071] The diameter (d2) of the second radial support surface (132) of the head is formed to be smaller than the diameter (d1) of the first radial support surface (131) of the head.

[0072] The first radial support surface (131) of the head is formed as a tapered shape that narrows downward, and the outer diameter (do) of the head male screw (110) is formed to be smaller than the minimum diameter of the first radial support surface (131) of the head.

[0073] FIG. 6 is a cross-sectional view showing the structure of a holder for a cutting head according to an embodiment of the present invention. Referring to FIG. 6, a holder (200) for a cutting head that is removably fastened according to an embodiment of the present invention includes a holder fastening portion (202) which is a space into which a cutting head (100) is inserted and fastened, and a shank (250) formed to extend axially below the holder fastening portion (202).

[0074] FIG. 7 is a cross-sectional view of the head fastening portion of a cutting head according to one embodiment of the present invention, and FIG. 8 is a cross-sectional view of the holder fastening portion of a holder for a cutting head according to one embodiment of the present invention.

[0075] Referring to FIGS. 6 and FIGS. 8, the holder fastening portion (202) includes a holder female screw (210), a holder shaft support surface (220), and a holder radial support surface (230).

[0076] The holder female screw (210) is screw-coupled with the head male screw (110) formed on the cutting head (100) when the cutting head (100) is inserted and fastened.

[0077] The holder shaft support surface (220) is formed perpendicular to the axial direction of the holder (200) on the upper surface of the holder fastening part (202) and supports the load in the axial direction when fastened with the cutting head (100).

[0078] The radial support surface (230) of the holder is the inner circumferential surface of the holder fastening part (202) and supports the load in the radial direction by abutting against the radial support surface (130) of the head when fastened with the cutting head (100).

[0079] The holder radial support surface (230) comprises a holder radial first support surface (231) formed on the holder female screw (210) and a holder radial second support surface (232) formed below the holder female screw (210). The holder radial first support surface (231) corresponds to the head radial first support surface (131), and the holder radial second support surface (232) corresponds to the head radial second support surface (132).

[0080] By forming a first radial support surface (231) on the upper side and a second radial support surface (232) on the lower side with the above holder female screw (210) in between, the cutting head (100) is supported radially from the upper and lower sides, respectively, when fastened to the holder (200), thereby improving axial alignment. In addition, bending phenomena during processing can be minimized, and stress can be distributed to prevent tool breakage and holder damage.

[0081] The diameter (D2) of the second radial support surface (232) of the holder is formed to be the same as the inner diameter (Di) of the female screw (210) of the holder.

[0082] In addition, the second radial support surface (232) of the holder is preferably formed in a cylindrical shape. By forming it in a cylindrical shape, bending during centering (axial alignment) and processing can be minimized, and the effect of stress distribution is increased.

[0083] The first radial support surface (231) of the holder is formed in a tapered shape that narrows downward.

[0084] It is preferable that the axial length of the holder radial support surface (230) be formed to be shorter than the axial length of the head radial support surface (130). Generally, the cutting head is made of carbide and the holder is made of steel, so bending occurs between the cutting head and the holder during machining (e.g., end mill slotting). For example, if the axial length (l1) of the head radial first support surface (131) of the cutting head becomes shorter than the length (L1) of the holder radial first support surface (231), which is the corresponding support surface of the holder (200), damage to the support surface of the holder may occur when the cutting head bends. To prevent this, the axial length (L1) of the holder radial first support surface (230) is formed to be shorter than the axial length (l1) of the head radial support surface (130).

[0085] FIG. 9 shows the state in which the head fastening part (102) of the cutting head (100) of FIG. 7 and the holder fastening part (202) of the holder (200) of FIG. 8 are fastened and combined according to one embodiment of the present invention described above.

[0086] The foregoing description is merely an illustrative explanation of the technical concept of the present invention, and those skilled in the art to which the present invention pertains will be able to make various modifications, changes, and substitutions within the scope of the essential characteristics of the present invention. Accordingly, these embodiments are intended to explain, not limit, the technical concept of the present invention, and the scope of the technical concept of the present invention is not limited by these embodiments. The scope of protection of the present invention shall be interpreted by the claims below, and all technical concepts within an equivalent scope shall be interpreted as being included within the scope of rights of the present invention.

[0087] <Explanation of Symbols>

[0088] 100: Cutting head

[0089] 101: Head cutting section

[0090] 102: Head connection part

[0091] 110: Male head screw

[0092] 120: Head shaft support surface

[0093] 130: Head radial support surface

[0094] 131: Head radial first support surface

[0095] 132: Head radial second support surface

[0096] 140: Head connection groove

[0097] 140a: Elastomer

[0098] 141: Head fastening part first groove

[0099] 141a: First elastic body

[0100] 142: Second groove of the head fastening part

[0101] 142a: Second elastic body

[0102] 200: Holder

[0103] 202: Holder fastening part

[0104] 210: Holder female screw

[0105] 220: Holder shaft support surface

[0106] 230: Holder radial support surface

[0107] 231: Holder radial first support surface

[0108] 232: Holder radial second support surface

[0109] 250: Shank

Claims

1. A detachably fastened cutting head (100) comprising a head cutting portion (101) including a cutting blade, and a head fastening portion (102) formed to extend axially below the head cutting portion (101) and fastened to a holder (200), wherein The head fastening part (102) above is, A head male screw (110) that is screw-coupled with a holder female screw (210) formed in the holder (200) when fastened to the holder (200); A head shaft support surface (120) formed perpendicularly to the axial direction of the cutting head (100) on the lower bottom surface of the head cutting part (101) and supporting a load in the axial direction when fastened to the holder (200); and It includes a head radial support surface (130) which supports a load in the radial direction when fastened to the holder (200) as an outer surface of the head fastening part (102); The above head radial support surface (130) comprises a head radial first support surface (131) formed on the head male screw (110) and a head radial second support surface (132) formed below the head male screw (110), wherein the cutting head (100) is removably fastened.

2. In Paragraph 1, A head fastening groove (140) is formed in the circumferential direction on the radial support surface (130), and a ring-shaped elastic body (140a) is fitted into the head fastening groove (140). The elastic body (140a) fitted into the head fastening groove (140) protrudes radially from the radial support surface (130), and A cutting head (100) that is detachably fastened, in which the protruding part of the elastic body (140a) is elastically deformed and fastened by an interference fit when the head fastening part (102) is fastened to the holder (200).

3. In Paragraph 2, The head fastening groove (140) includes a head fastening first groove (141) formed circumferentially on the head radial first support surface (131), and The above elastic body (140a) comprises a ring-shaped first elastic body (141a) that is fitted into the first groove (141) of the head fastening part, and is a cutting head (100) that is removably fastened.

4. In Paragraph 2, The head fastening groove (140) includes a second head fastening groove (142) formed circumferentially on the second head radial support surface (132), and The above elastic body (140a) comprises a ring-shaped second elastic body (142a) that is fitted into the second groove (142) of the head fastening part, and is a cutting head (100) that is releasedly fastened.

5. In Paragraph 2, The head fastening groove (140) includes a first head fastening groove (141) formed circumferentially on the first head radial support surface (131) and a second head fastening groove (142) formed circumferentially on the second head radial support surface (132). The above elastic body (140a) comprises a ring-shaped first elastic body (141a) fitted into the first groove (141) of the head fastening part and a ring-shaped second elastic body (142a) fitted into the second groove (142) of the head fastening part, wherein the cutting head (100) is removably fastened.

6. In Paragraph 1, A cutting head (100) that is removably fastened, wherein the diameter (d2) of the second radial support surface (132) of the head is formed to be larger than the root diameter (di) of the head male screw (110).

7. In Paragraph 1, A cutting head (100) that is removably fastened, wherein the axial length of the first radial support surface (131) of the head is formed to be 100 to 130% of the axial length of the second radial support surface (132) of the head.

8. In Paragraph 7, A cutting head (100) that is removably fastened, wherein the axial length of the first radial support surface (131) of the head is formed to be the same as the axial length of the second radial support surface (132) of the head.

9. In Paragraph 1, The first support surface (131) in the radial direction of the head is formed in a tapered shape that narrows downward, and The above head radial first support surface (131) is a detachably fastened cutting head (100) having an axial length corresponding to 45-50% of the maximum diameter.

10. In Paragraph 9, The above head radial first support surface (131) is a removably fastened cutting head (100) having an axial length of 50% of the maximum diameter.

11. In Paragraph 1, The first support surface (131) in the radial direction of the head is formed in a tapered shape that narrows downward, and A cutting head (100) that is removably fastened, wherein the maximum diameter of the first radial support surface (131) of the head is 60 to 80% of the maximum outer diameter of the head cutting portion (101).

12. In Paragraph 11, A removably fastened cutting head (100), wherein the maximum diameter of the first radial support surface (131) of the head is 73 to 76% of the maximum outer diameter of the head cutting portion (101).

13. In Paragraph 1, The above head radial second support surface (132) is formed in a cylindrical shape and is a cutting head (100) that is releasedly fastened.

14. In Paragraph 13, A cutting head (100) that is releasedly fastened, wherein the diameter (d2) of the second radial support surface (132) of the head is formed to be smaller than the diameter (d1) of the first radial support surface (131) of the head.

15. In Paragraph 14, The first support surface (131) in the radial direction of the head is formed in a tapered shape that narrows downward, and A cutting head (100) that is releasedly fastened, wherein the outer diameter (do) of the head male screw (110) is formed to be smaller than the minimum diameter of the first radial support surface (131) of the head.

16. A holder (200) for a cutting head that is removably fastened, comprising a holder fastening portion (202) which is a space into which a cutting head (100) is inserted and fastened, and a shank (250) formed to extend axially below the holder fastening portion (202). The above holder fastening part (202) is, A holder female screw (210) that is screw-coupled with a head male screw (110) formed on the cutting head (100) when the cutting head (100) is inserted and fastened; A holder shaft support surface (220) formed perpendicular to the axial direction of the holder (200) on the upper upper surface of the holder fastening part (202) and supporting a load in the axial direction when fastened with the cutting head (100); and It includes a holder radial support surface (230) that supports a load in the radial direction when fastened with the cutting head (100) as an inner circumferential surface of the holder fastening part (202). The holder radial support surface (230) comprises a holder radial first support surface (231) formed on the holder female screw (210) and a holder radial second support surface (232) formed below the holder female screw (210), forming a holder that is removably fastened, for a cutting head holder (200).

17. In Paragraph 16, A holder (200) for a cutting head that is removably fastened, wherein the diameter (D2) of the second radial support surface (232) of the holder is formed to be the same as the inner diameter (Di) of the female screw (210) of the holder.

18. In Paragraph 17, The holder radial second support surface (232) is formed in a cylindrical shape and is a holder (200) for a cutting head that is removably fastened.

19. In Paragraph 18, The first radial support surface (231) of the holder is formed as a tapered shape that narrows downward, and is a holder (200) for a cutting head that is releasedly fastened.

20. In Paragraph 19, A head radial support surface (130) is formed on the outer surface of the head fastening portion (102) of the cutting head (100) that is fastened to the holder (200), and supports a load in the radial direction when fastened to the holder (200). A holder (200) for a cutting head that is removably fastened, wherein the axial length of the radial support surface (230) of the holder is formed to be shorter than the axial length of the radial support surface (130) of the head.

21. In Paragraph 20, The head radial support surface (130) comprises a head radial first support surface (131) formed on the head male screw (110) and a head radial second support surface (132) formed below the head male screw (110). A holder (200) for a cutting head that is releasedly fastened, wherein the axial length (L1) of the first radial support surface (231) of the holder is shorter than the axial length (l1) of the first radial support surface (131) of the head.

Images