KR20090021726A - Cutting tool having a structure for easy rotation of insert - Google Patents

Abstract

A cutting tool having a structure for easy rotation of an insert is provided to prevent the loss of a clamping screw in replacing the cutting part of an insert by conforming a new cutting part to a work piece although the clamping screw is not separated from a holder. A cutting tool having a structure for easy rotation of an insert comprises a holder(120) equipped with a pocket part(122) having sides and bottom and a clamping hole(121) formed on the lower part of the pocket part; an insert(110) mounted to the pocket part of a holder having a center penetration hole(111) and a plurality of cutting edge parts; and a clamping screw(130) fastening the insert to the holder, consisting of a head part(131) contacting with the inner lining of the penetrating hole and a fastener(132) joined to the clamping hole of the holder.

Description

Cutting tool having a structure for easy rotation of insert}

The present invention relates to a cutting tool, and more particularly to a cutting tool capable of replacing the cutting edge (or cutting corner) by rotating the insert without removing the clamping screw.

In general, the machining tool comprises a cutting insert which is fixed to the pocket of the holder via the holder and the clamping means in contact with the workpiece.

1 is a partial plan view of a typical cutting tool including a holder and an insert mounted to the holder.

The insert 1 is fixed and mounted to the pocket portion 2A formed on the upper part of the holder 2 by the clamping screw 3, and the cutting edge or the cutting corner of the insert 1 exposed to the outside of the holder 2 ( A cutting portion contacts the workpiece (not shown) to process the workpiece.

As the machining process proceeds, the cutting portion of the insert 1 wears out and the workpiece is not cut accurately. Therefore, the insert 1 must be rotated by an angle with respect to the holder 2 to correspond to the new cutting part.

To this end, the operator removes the insert 1 from the pocket portion 2A of the holder 2 by completely removing the clamping screw 2 holding the insert 1 from the holder 2. Then, the worker fixes the insert 1 to the holder 2 via the clamping screw 3 so that a new cutting portion projects out of the holder 2.

The process of detaching the insert 1 from the holder 2 and remounting the holder 2 is not only complicated, but also time consuming, and also the clamping screw 3 separated from the holder 2. Problem occurs that may be lost.

The present invention is to solve the above problems that may occur when replacing the cut portion of the worn cutting insert, it is possible to correspond to the new cutting portion by rotating the insert without completely removing the clamping screw from the holder It is an object of the present invention to provide a cutting tool having a structure.

The cutting tool according to the present invention comprises: a holder having a pocket having side and bottom surfaces and a clamping hole formed under the pocket; An insert mounted on the pocket of the holder, the insert having a central through hole and a plurality of cutting edges; And a clamping screw for fastening the insert to the holder, including a head portion in contact with the inner circumferential surface of the insert's through hole and a fastening portion coupled to the holder's clamping hole through the insert's through hole, wherein the clamping screw secures the insert to the holder. One of the fastening portions of the screw is formed with an upper spiral portion and a lower spiral portion spaced apart by a region where no spiral portion is formed, and the other one has a spiral portion that can be fastened to the upper spiral portion and the lower spiral portion.

Here, the upper spiral portion and the lower spiral portion is formed spaced apart from the inner circumferential surface of the clamping hole of the holder, one spiral portion is formed in the lower portion of the clamping screw.

The length of the spiral portion of the clamping screw is preferably shorter than the distance between the upper and lower spiral portions in the clamping hole of the holder. Further, the length of the upper helix is shorter than the length of the lower helix and the length of the lower helix is preferably greater than the height of the pocket.

Meanwhile, the upper spiral portion and the lower spiral portion may be spaced apart from the clamping screw, and one spiral portion may be formed on the inner circumferential surface of the clamping hole of the holder.

At this time, the length of the spiral portion formed in the clamping hole of the holder is shorter than the distance between the upper spiral portion and the lower spiral portion of the clamping screw, the length of the upper spiral portion is longer than the length of the lower spiral portion and the length of the upper spiral portion is larger than the height of the pocket portion. Do.

The cutting tool according to the present invention having the above structure and function can correspond to the new cutting part by rotating the insert even when the clamping screw is not completely removed from the holder, and thus the clamping screw when replacing the cutting part of the insert Can prevent the loss.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First Example

FIG. 2 is a cross-sectional view of the cutting tool according to the first embodiment of the present invention, which corresponds to a cross-sectional view taken along the line A-A of FIG. 1.

The cutting tool according to the first embodiment of the present invention includes a holder 20 having a pocket portion 22 formed at an upper portion and a clamping hole 21 formed at a lower portion of a bottom surface of the pocket portion 22; An insert 10 having a cutting portion (cut edge or cutting corner) and positioned on the pocket portion 22 of the holder 20; And a clamping screw 30 for fixing the insert 10 to the holder 20.

The clamping screw 30 passes through the head portion 31 which contacts the circumferential surface of the through hole 11 of the insert 10 and the through hole 11 of the insert 10, thereby clamping the hole 21 of the holder 20. It includes a fastening portion 32 coupled to).

Two spiral parts spaced apart are formed on the inner circumferential surface of the clamping hole 21 of the holder 20. That is, the clamping hole 21 includes a first spiral portion 21-1 (upper spiral portion) formed in the upper region of the inner circumferential surface and a second spiral portion 21-2 (lower spiral portion) formed in the lower region.

In addition, a spiral portion 32-1 is formed under the fastening portion 32 of the clamping screw 30.

In the cutting tool having such a structure, a process of fixing the insert 10 to the holder 20 will be described.

After the fastening portion 32 of the clamping screw 30 passes through the through hole 11 formed in the insert 10, the spiral portion 32-1 formed under the fastening portion 32 of the clamping screw 30. Is screwed with the first helix 21-1 formed in the upper region of the clamping hole 21 of the holder 20. With the continuous rotation of the clamping screw 30, the spiral portion 32-1 of the fastening portion 32 of the clamping screw 30 and the first spiral portion 21-1 of the clamping hole 21 of the holder 20. ) Is released, and then the spiral portion 32-1 of the clamping screw 30 is screwed with the second spiral portion 21-2 formed in the lower region of the clamping hole 21 of the holder 20. (State of FIG. 2).

In the state of FIG. 2, the head part 31 of the clamping screw 30 is in contact with the circumferential surface of the through hole 11 of the insert 10, so that the insert 10 is clamped by the clamping screw 30. 20) is firmly fixed. In this state, the cutting portion of the insert 10 exposed to the outside of the holder 20 comes into contact with the workpiece (not shown) to process the workpiece.

Referring to the process of rotating the insert 10 on the holder 20 to replace the worn cut as follows.

When the user rotates the clamping screw 30 in reverse, the spiral portion 32-1 formed under the fastening portion 32 of the clamping screw 30 and the lower region of the clamping hole 21 of the holder 20 are formed. The screw engagement between the second spiral portions 21-2 is released. At this time, since the clamping hole 21 of the clamping screw 30 and the holder 20 is not screwed, the clamping screw 30 is limited in movement.

In this state, the clamping screw 30 can freely rotate in the clamping hole 21 of the holder 20, and the insert 10 can also be out of the pocket 22. Thus, the operator can rotate the insert 10 about the clamping screw 30 so that the new cutting portion of the insert 10 can correspond to the workpiece.

After setting a new cut of the insert 10 for the machining of the workpiece, the operator rotates the clamping screw 30 to move the helix 32-1 of the clamping screw 30 into the clamping hole 21 of the holder 20. The insert 10 is completely remounted on the holder 20 by screwing with the second spiral portion 21-2 formed in the lower region of the bottom surface).

As such, it is not necessary to completely remove the clamping screw 30 from the holder 20 in order to correspond with the new cut of the insert 10 to the workpiece. In particular, if the spiral portion 32-1 of the clamping screw 30 is not screwed with the first spiral portion 21-1 of the upper portion of the clamping hole 21 of the holder 20, the clamping screw 30 is It does not rise excessively, and thus the clamping screw 30 can be prevented from being separated from the holder 20 or lost.

Here, the length (height) of the first spiral portion 21-1 formed in the clamping hole 21 of the holder 20 is preferably shorter than the length (height) of the second spiral portion 21-2, In addition, the length of the spiral portion 32-1 of the clamping screw 30 is greater than the distance between the first spiral portion 21-1 and the second spiral portion 21-2 in the clamping hole 21 of the holder 20. It should be short.

In addition, when the clamping screw 30 moves freely (or rotates) in the clamping hole 21 of the holder 20, the head portion 31 of the clamping screw 30 passes through the through hole 11 of the insert 10. In order to completely deviate from the above, it is preferable that the length of the second helix 21-2 in the clamping hole 21 of the holder 20 is greater than the thickness (height) of the insert 10 or the height of the pocket 22. Do.

2nd Example

3 is a cross-sectional view of the cutting tool according to the second embodiment of the present invention, taken along a line A-A of FIG. 1.

Similar to the cutting tool according to the first embodiment, the cutting tool according to the second embodiment includes a holder 120 having a pocket portion 122 formed at an upper portion thereof and a clamping hole 121 formed at a lower portion of the pocket portion 122; An insert 110 having a cutting portion (cut edge or cutting corner) and located on the pocket portion 122 of the holder 120; And a clamping screw 130 that fixes the insert 110 to the holder 120.

The clamping screw 130 passes through the head portion 131 contacting the circumferential surface of the through hole 111 of the insert 110 and the through hole 111 of the insert 110, and clamping hole 121 of the holder 120. It includes a fastening portion 132 coupled to).

The fastening part 132 of the clamping screw 130 is formed with two spiral parts spaced a predetermined distance apart. That is, the fastening part 132 of the clamping screw 130 may include a first helix 132-1 (upper helix) formed in the upper region and a second helix 132-2 (lower spiral portion) formed in the lower region. Include.

On the other hand, a single spiral portion 121-1 is formed on the inner circumferential surface of the clamping hole 121 of the holder 120.

In the cutting tool having such a structure, a process of fixing the insert 110 to the holder 120 will be described.

After the fastening portion 132 of the clamping screw 130 passes through the through hole 111 formed in the insert 110, the second spiral portion 132 formed in the lower region of the fastening portion 132 of the clamping screw 130. -2) is screwed with the spiral portion 121-1 formed on the clamping hole 121 of the holder 120. By the continuous rotation of the clamping screw 130, the screw coupling of the second spiral portion 132-2 of the clamping screw 130 and the spiral portion 121-1 of the clamping hole 121 is released, and then the clamping screw The first spiral portion 132-1 formed in the upper region of the fastening portion 132 of 130 is screwed with the spiral portion 121-1 of the clamping hole 121 (state of FIG. 3).

In the state of FIG. 3, the head portion 131 of the clamping screw 130 is in contact with the circumferential surface of the through hole 111 of the insert 110, so that the insert 110 is clamped by the clamping screw 130. 120) is firmly fixed. In this state, the cutting portion of the insert 110 exposed to the outside of the holder 120 contacts the workpiece (not shown) to process the workpiece.

Referring to the process of rotating the insert 110 in the holder 120 to replace the worn cut as follows.

When the user rotates the clamping screw 130 in reverse, the first region 132-1 formed on the fastening portion 132 of the clamping screw 130 and the upper region of the clamping hole 121 of the holder 120 The screw coupling between the spiral portion 121-1 formed in the is released. At this time, since the clamping hole 121 of the clamping screw 130 and the holder 120 is not screwed, the user can perform a limited movement of the clamping screw 130.

In this state, the clamping screw 130 can freely rotate in the clamping hole 121 of the holder 120, the insert 110 can also be out of the pocket portion 122. Therefore, the operator can rotate the insert 110 about the clamping screw 130 so that the new cutting portion of the insert 110 can correspond to the workpiece.

After setting the new cutting part of the insert 110 for the workpiece machining, the operator rotates the clamping screw 130 to move the first helix 132-1 of the clamping screw 130 into the clamping hole ( The insert 10 is completely remounted on the holder 120 by screwing with the spiral portion 121-1 formed in the upper region of 121.

As such, it is not necessary to completely remove the clamping screw 130 from the holder 120 in order to correspond with the new cut of the insert 110 to the workpiece. In particular, if the second spiral portion 132-2 of the clamping screw 130 does not screw with the spiral portion 121-1 of the upper portion of the clamping hole 121 of the holder 120, the clamping screw 130 is It does not rise excessively, thus preventing the clamping screw 130 from being separated from the holder 120 or being lost.

Here, it is preferable that the length (height) of the second spiral portion 132-2 formed in the fastening portion 132 of the clamping screw 130 is shorter than the length (height) of the first spiral portion 132-1. .

In addition, when the clamping screw 130 is free to move (or rotate) in the clamping hole 121 of the holder 120, the head portion 131 of the clamping screw 130 is the through-hole 111 of the insert 110 In order to deviate completely from it, it is preferable that the length of the first spiral portion 132-1 of the clamping screw 130 is greater than the thickness (height) of the insert 110 or the height of the pocket 122.

3rd Example

4A is a cross-sectional view of the cutting tool taken along the line A-A of FIG. 1, and is a cross-sectional view of the cutting tool according to the third embodiment of the present invention. .

The cutting tool according to the third embodiment includes a holder 220 having a pocket portion 222 having side and bottom surfaces and a clamping hole 221 formed under the pocket portion; A seat 250 having a central hole and positioned on the pocket portion 222 of the holder 220; a hollow cylindrical shape and clamping of the head portion and the holder 220 contacting the inner surface of the central hole of the seat 250. A fixing member 240 having an outer circumference coupled to the inner circumferential surface of the hole 221 and an inner circumferential surface formed with a fastening portion; An insert 210 having a plurality of cutting edges and positioned on the sheet 250; And a head portion 231 contacting the outer circumferential surface of the through hole 211 of the insert 210 and a through hole 211 of the insert 210 and fixed in the clamping hole 221 of the holder 220. Including a fastening portion 232 coupled to the fixing member 240, it includes a clamping screw 230 for fixing the insert 210 to the holder 220.

On the other hand, the fixing member 240 has a function of fixing the sheet 250 located on the pocket portion 222 of the holder 220, the spiral portion formed on the outer peripheral surface and the inner peripheral surface of the clamping hole 221 of the holder 220 It is fixed through the screwing of the spiral formed in the.

As shown in FIG. 4A, a plurality of spiral parts spaced apart from each other are formed on the inner circumferential surface of the fixing member 240 and the fastening portion 232 of the clamping screw 230.

FIG. 4B is a cross-sectional view illustrating the structure of the fixing member 240 illustrated in FIG. 4A. The first spiral part 240-1 (upper spiral part) and the first spiral part are formed in the upper region and the lower region of the inner circumferential surface of the fixing member 240. 2 spiral parts 240-2 (lower spiral parts) are formed, respectively, and the spiral part is formed in the outer peripheral surface.

Meanwhile, the clamping screw 230 may include a first spiral portion 232-1 (upper spiral portion) formed in the upper region of the fastening portion 232 and a second spiral portion 232-2 (lower spiral portion) formed in the lower region. Include.

In the cutting tool having such a structure, the process of fixing the insert 210 to the holder 220 is the same as the process of fixing the inserts 10 and 110 to the holders 20 and 120 in the first and second embodiments. Therefore, description thereof is omitted.

Referring to the process of rotating the insert 210 on the holder 220 to replace the worn cut as follows.

In the state of FIG. 4A, when the user rotates the clamping screw 230 reversely, the first spiral portion 232-1 of the fastening portion 232 of the clamping screw 230 and the clamping hole 221 of the holder 220 are provided. Screwing between the first helix portion 240-1 formed in the upper region of the fixing member 240 fixed in the) and the second helix portion 232-2 of the clamping screw 230 and the fixing member in the holder 220. The screwing of the second spiral portion 240-2 of 240 is released.

At this time, since the inner circumferential surfaces of the clamping screw 230 and the fixing member 240 are not screwed, the clamping screw 230 is limited in movement.

In this state, the clamping screw 230 may rotate freely in the fixing member 240, and the insert 210 may be out of the pocket portion 222. Therefore, the operator can rotate the insert 210 about the clamping screw 230 so that the new cutting portion of the insert 210 can correspond to the workpiece.

After setting a new cut of the insert 210 to machine the workpiece, the operator rotates the clamping screw 230 to first and second helixes 232-1 and 232-2 of the clamping screw 230. ), The insert 210 is completely remounted on the holder 220 by screwing into the first and second spiral portions 240-1 and 240-2 formed on the inner circumferential surface of the fixing member 240, respectively.

As such, there is no need to completely remove the clamping screw 230 from the holder 220 in order to correspond with the new cut of the insert 210 to the workpiece. In particular, unless the second spiral portion 232-2 of the clamping screw 230 is screwed with the first spiral portion 240-1 of the fixing member 240, the clamping screw 230 does not rise excessively. Therefore, the clamping screw 230 may be prevented from being separated from the holder 220 or lost.

The first spiral portion 232-1 of the clamping screw 230 preferably has a length shorter than the length (height) of the second spiral portion 232-2, and is formed in the upper region of the fixing member 240. It is preferable that the length of the first spiral portion 240-1 is shorter than the length of the second spiral portion 240-2.

In addition, when the screwing of the second spiral portion 232-2 of the clamping screw 230 and the second spiral portion 240-2 of the fixing member 240 is released, that is, the clamping screw 230 is fixed. When freely rotatable within the member 240, the first helix of the fixing member 240 is provided so that the head portion 231 of the clamping screw 230 is completely out of the through hole 211 of the insert 210. It is preferable that the distance between the portion 240-1 and the second spiral portion 240-2 is greater than the height of the insert 210.

4th Example

5 is a cross-sectional view of the cutting tool according to the fourth embodiment of the present invention, which corresponds to a cross-sectional view taken along the line A-A of FIG. 1.

The cutting tool according to the present embodiment includes a holder 320 having a pocket portion 322 formed on an upper surface and a clamping hole 321 formed under the pocket portion; A hollow intermediate member 340 installed in the clamping hole 321 of the holder 320; An insert 310 having a cutting portion (cut edge or cutting corner) and positioned on the pocket portion 322 of the holder 320; And a head portion 331 contacting the circumferential surface of the through hole 311 of the insert 310 and a through hole 311 of the insert 310 to be fixed in the clamping hole 321 of the holder 320. It includes a clamping screw 330 to secure the insert 310 to the holder 320, including a fastening portion 332 coupled to the intermediate member 340.

The configuration and function of the members constituting the cutting tool according to the present embodiment are similar to the configuration and function of the members constituting the cutting tool according to the third embodiment, except that the intermediate member 340 does not have a sheet fixing function. There is. In addition, the intermediate member 340 may be fixed to the clamping hole 321 by interference fit.

The cutting tool according to the present embodiment is characterized in that the intermediate member 340, which is installed in the clamping hole 321 of the holder 320 in a fixed state, is a hollow member whose upper end is opened and the lower end is closed. An elastic member 350 (eg, a spring) may be mounted between the bottom surface of the 340 and the bottom surface of the insert 310.

By the intermediate member 340 and the elastic member 350 having such a structure, the second helix portion 332-2 of the fastening portion 332 of the clamping screw 330 and the second helix of the intermediate member 340. When the screwing of the screw 330-2 and the screwing of the first screw 332-1 of the clamping screw 330 and the first screw 340-1 of the intermediate member 340 are released, the external force Even in the non-applied state, the clamping screw 330 is moved upward in the intermediate member 340 by the elastic force of the elastic member 350 so that the user can easily identify the unlocked state.

The process of mounting, rotating and remounting the insert 310 in the cutting tool according to the present embodiment is the same as the process of mounting, rotating and remounting the insert 210 in the cutting tool according to the third embodiment, and thus description thereof. Is omitted.

5th Example

6 is a cross-sectional view of the cutting tool according to the fifth embodiment of the present invention, which corresponds to a cross-sectional view taken along the line A-A of FIG. 1.

The cutting tool according to the present embodiment includes a holder 420 having a pocket portion 422 formed on an upper surface and a clamping hole 421 formed under the pocket portion 422; An insert 410 having a cutting portion (cut edge or cutting corner) and positioned on the pocket portion 422 of the holder 420; The fastening portion coupled to the clamping hole 421 of the holder 420 through the head portion 431 in contact with the circumferential surface of the through hole 411 of the insert 410 and the through hole 411 of the insert 410. A clamping screw 430 that includes a 420 and fixes an insert 410 to the holder 420; And a cylindrical stopper member 440 positioned between the inner circumferential surface of the clamping hole 421 of the holder 420 and the outer circumferential surface of the fastening portion 432 of the clamping screw 430.

As shown in FIG. 6, in the cutting tool according to the present embodiment, spiral parts 421 fastened to the lower part of the inner circumferential surface of the clamping hole 421 of the holder 420 and the lower part of the fastening part 432 of the clamping screw 430. -1, 432-1) are formed, respectively.

In addition, a hollow cylindrical stopper member 440 is located in the upper region of the clamping hole 421 of the holder 420, and the upper region of the fastening portion 432 of the clamping screw 430 (that is, the spiral portion 432-). An area where 1) is not formed) is accommodated in this stopper member 440.

On the other hand, the stopper member 440 may be fixed in the clamping hole 421 of the holder 420 in the form of interference fit.

The inner surface of the upper end of the cylindrical stopper member 440 is formed with a projection 441 extending radially toward the center, the projection 441 is a spiral portion 432 formed in the fastening portion 432 of the clamping screw 430 -1).

The extension 441 may be a protruding ring member extending from an inner surface of the upper end of the cylindrical stopper member 440. In addition, a spiral portion may be formed on an inner surface of the extension portion 441.

When the stopper member 440 is fixed in the clamping hole 421 of the holder 420, the cutting tool having such a structure is in the same state as the cutting tool according to the first embodiment. Therefore, further description of this embodiment will be omitted.

Preferred embodiments of the present invention described above are disclosed for purposes of illustration, and those skilled in the art will be able to make various modifications, changes, and additions within the spirit and scope of the present invention. Modifications and additions should be considered to be within the scope of the following claims.

For example, in the above description, the cutting tool according to the fourth embodiment shown in FIG. 5 is closed between the bottom surface of the fixing member 340 and the bottom surface of the clamping screw 330. Although it has been described that the structure in which the elastic member 350 is positioned in the above, the structure can also be applied to the cutting tool according to the first and second embodiments.

That is, the holders 20 and 120 with the lower ends of the clamping holes 21 and 121 are mounted on the cutting tools according to the first and second embodiments, and the bottom surfaces of the clamping holes 21 and 1221 and the clamping screw 30 are mounted. , An elastic member may be positioned between the bottom of the 130.

1 is a plan view of a typical cutting tool comprising a holder and an insert mounted to the holder.

FIG. 2 is a view corresponding to a cross-sectional view taken along the line A-A of FIG. 1, showing a cutting tool according to the first embodiment of the present invention. FIG.

3 is a view corresponding to a cross-sectional view taken along the line A-A of FIG. 1, showing a cutting tool according to a second embodiment of the present invention having another structure;

4A is a view corresponding to a cross-sectional view taken along the line A-A of FIG. 1, showing a cutting tool according to a third embodiment of the present invention.

4B is a cross-sectional perspective view showing the structure of the fixing member shown in FIG. 4A.

5 is a view corresponding to a cross-sectional view taken along the line A-A of FIG. 1, and is a cross-sectional view of a cutting tool according to a fourth embodiment of the present invention.

FIG. 6 is a cross-sectional view of a cutting tool according to a fifth embodiment of the present invention, taken along a line A-A of FIG. 1; FIG.

Claims (10)

A holder having a pocket having side and bottom surfaces and a clamping hole formed under the pocket; An insert mounted on the pocket of the holder, the insert having a central through hole and a plurality of cutting edges; And And a clamping screw to fix the insert to the holder, including a head part in contact with an inner circumferential surface of the through hole of the insert and a fastening part passing through the insert through hole of the insert to be coupled to the clamping hole of the holder. One of the inner circumferential surface of the clamping hole of the holder and the fastening portion of the clamping screw is formed with an upper spiral portion and a lower spiral portion spaced apart by a region in which no spiral portion is formed, and the other has an upper spiral portion and a lower spiral portion. A cutting tool, characterized in that one fastening spiral portion is formed. The cutting tool according to claim 1, wherein the upper spiral portion and the lower spiral portion are formed to be spaced apart from the inner circumferential surface of the clamping hole of the holder, and the one spiral portion is formed under the clamping screw. The cutting tool according to claim 2, wherein the length of the spiral portion of the clamping screw is shorter than the distance between the upper spiral portion and the lower spiral portion in the clamping hole of the holder. 4. The cutting tool according to claim 3, wherein the length of the upper helix is shorter than the length of the lower helix and the length of the lower helix is greater than the height of the pocket. The cutting tool according to claim 1, wherein the upper spiral portion and the lower spiral portion are formed to be spaced apart from the clamping screw, and one spiral portion is formed on an inner circumferential surface of the clamping hole of the holder. 6. The cutting tool according to claim 5, wherein the length of the spiral portion formed in the clamping hole of the holder is shorter than the distance between the upper spiral portion and the lower spiral portion of the clamping screw. 7. The cutting tool according to claim 6, wherein the length of the upper helix is longer than the length of the lower helix and the length of the upper helix is greater than the height of the pocket. The cutting tool according to any one of claims 1 to 7, wherein the lower end of the clamping hole of the holder is closed and an elastic member is positioned between the bottom surface of the clamping hole and the bottom surface of the clamping screw. A holder having a pocket having side and bottom surfaces and a clamping hole formed under the pocket; A seat having a central through hole and located on a pocket of the holder; A fixing member having a hollow cylindrical shape and having a head portion in contact with an inner surface of the through hole of the sheet and an inner circumferential surface formed with an outer circumference portion coupled to an inner circumferential surface of the clamping hole of the holder; An insert mounted on said sheet having a through hole and a plurality of cutting edges; And A clamping screw for fastening the insert to the holder, including a head portion in contact with an inner circumferential surface of the through hole of the insert and a fastening portion passing through the insert through hole and engaged with a fixing member fixed in the clamping hole of the holder. Including, Cutting tools, characterized in that the inner peripheral surface of the fixing member and the fastening portion of the clamping screw are formed with a plurality of spaced apart spirals can be screwed together. 10. The cutting tool according to claim 9, wherein the fixing member is a closed end of the fixing member, and an elastic member is positioned between the bottom surface of the fixing member and the bottom surface of the clamping screw.

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