JP2513239Y2 - Rolling tool fastening device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a rolling tool fastening device.

[Prior Art] Conventionally, as a means for attaching a milling tool such as a face mill to the tip of a spindle of a machine tool via an adapter,
For example, a rolling tool fastening device having a configuration as shown in FIGS. 13 and 14 is adopted.

In this device, an adapter body 2 is fixed to a tip end of a spindle 1 of a machine tool with a bolt, a lock ring 3 is rotatably attached to an outer circumference of the adapter body 2, and an inner peripheral surface of a tip side of the lock ring 3 is attached. A flange 7 (two-dot chain line in FIG. 13) provided at the rear end of the outer peripheral surface of the rolling tool 6 is inserted into the notch portion 5 of the flange 4 protruding in the axial direction, and in this state, the adapter While attaching the hook bar 8 to the main body 2 and blocking the rotation of the adapter main body 2 with one hand, the hook spanner 9 is attached to the lock ring 3 with the other hand, and the lock ring 3 is moved to the 13th position.
The turning tool 6 is attached to the spindle 1 by rotating clockwise in the figure and locking the flange 7 with the flange 4. Note that 6a is a cutting blade attached to the tip of the rolling tool.

In the conventional device described above, the flange 7 is formed to have a thickness slightly smaller than the distance between the rear end surface of the flange 4 and the front end surface 2a of the adapter body 2.
Thus, the rolling tool 6 can be securely held with the collar 7 locked. In this device, in order to remove the rolling tool 6 from the main spindle 1, the reverse operation to the above is performed, the lock ring 3 is rotated counterclockwise in FIG. The rolling tool 6 may be removed by aligning the position with the cutout portion 7.

However, in the above-mentioned conventional device, when the rolling tool 6 is attached or detached, the adapter body 2 and the lock ring 3 are
The hooking bar 8 and the hooking wrench 9 must be supported respectively, and since both hands are blocked and the rolling tool 6 cannot be held by hand, not only the attaching / detaching work becomes difficult, but also In particular, at the time of removal, the rolling tool 6 may fall when the brim 5 and the notch 7 are aligned with each other, and in this case, the rolling tool 6 may be damaged.

A fastening device shown in FIG. 15 is also known as a device that solves these drawbacks.

In this device, an adapter body 12 is fixed to a tip end of a spindle 10 of a machine tool with a bolt, and a projection provided at a rear end of a rolling tool 16 is attached to a mounting hole 12a formed at an axial center position of the adapter body 12. Fitting the portion 16a, from the through hole 12b penetrating in the diametrical direction of the adapter body 12 and facing the mounting hole 12a, the clamp bolt 19 is passed through the through hole 16b formed in the projection 16a and tightened, Rolling tool with clamp bolt 19
16 is attached to the spindle 10.

In this device, since the clamp bolt 19 can be rotated with one hand, the clamp bolt 19 can be rotated with one hand.
You can hold the rolling tool 16 with the other hand while operating the
It has the advantage of being able to prevent 16 accidental drops.

[Problems to be solved by the invention] However, in this device, as an adapter,
As shown in the figure, a shaft S that is movably mounted in the axial direction of the adapter 2 is provided at the axial center position of the adapter 2, and the shaft S is used to mount a drill or the like. If a so-called "hollow product" is to be adopted, the clamp bolt must be inserted through the shaft to be attached, and in reality, such a hollow product cannot be used.

The present invention has been made in view of the above circumstances, and provides a fastening device for a rolling tool that can use a hollow adapter and can easily perform attachment / detachment work of the rolling tool. With the goal.

[Means for Solving the Problems] Therefore, in a fastening device for a rolling tool according to the present invention, an adapter is attached to a cylindrical adapter body attached to a tip end portion of a spindle of a machine tool, and attached to a tip end side of the adapter body. Lock ring and a clamp bolt and tweezers bolt for attaching the lock ring to the adapter body, and a clamp bolt with a female screw formed on the side surface of the adapter body facing each other. A hole and a tweezers bolt mounting hole are formed, and an elastic member for urging the lock ring in the tip direction is attached to the tip side of the adapter body, and the lock ring is a ring-shaped fitting portion externally fitted to the adapter body. A flange portion protruding from the inner peripheral surface of the fitting portion in the axial direction of the lock ring, and the flange portion provided on the flange portion. And a plurality of notches, and the fitting part has a clamp bolt insertion hole and a tweezers bolt insertion hole that are provided at positions corresponding to the clamp bolt mounting hole and the tweezers bolt mounting hole and that penetrate through in the radial direction. The clamp bolt insertion hole is formed with a bolt insertion part having an inner diameter larger than the outer diameter of the screw part of the clamp bolt, and a tapered surface continuously formed on the outer side of the bolt insertion part. The outer peripheral surface of the rolling tool is provided at a position corresponding to the cutout portion of the flange portion, and the inside of the cutout portion can be inserted and the rear portion of the flange portion is rotated along with the rotation of the rolling tool. A collar having a thickness to be sandwiched between the end surface and the tip surface of the adapter body is formed, and the clamp bolt is
It is screwed into the clamp bolt mounting hole from the clamp bolt insertion hole, and the head of the clamp bolt has a tapered surface that abuts the tapered surface formed in the clamp bolt insertion hole. The rolling tool fastening device is configured to be screwed into the tweezers bolt mounting hole from the tweezers bolt insertion hole.

[Embodiment] An embodiment of the fastening device of the present invention will be described below with reference to the drawings.

An adapter 30 is fixed to the tip of the spindle 20 of the machine tool.
Is attached.

The adapter 30 has a cylindrical adapter body 31 attached to the tip of the main shaft 20, a lock ring 32 attached to the tip of the adapter body 31, and the lock ring 32 attached to the adapter body 31. Clamp bolt 33 and tweezers bolt 34, and a coil spring that is attached to the tip side of the adapter body 31 and biases the lock ring 32 in the tip direction (left side in FIG. 1).
35 (elastic member).

On the side surface 31a of the adapter body 31, at a position opposed to each other in the diametrical direction of the adapter body 31, there are a clamp bolt mounting hole 31b and a tweezers bolt mounting hole 31c formed with a female screw and penetrating to a through hole 31d described later. It is formed (Figs. 3 and 4).

The clamp bolt mounting hole 31b is provided with a threaded portion 31b1 formed with a female screw over a length from the vicinity of the opening end to almost the middle of the entire length of the clamp bolt mounting hole 31b. A tapered surface 31b2 is formed at the outer peripheral side opening end of the clamp bolt mounting hole 31b. Further, on the side surface of the clamp bolt mounting hole 31b, the adapter body 3
A stopper screw mounting hole 36 extending in the axial direction of 1 and penetrating to the rear end surface of the adapter body 31 is formed. A stopper screw 37 and a lock screw 37a, which is arranged in the direction of the stopper screw 37 and prevents the screw from loosening, are screwed into the stopper screw mounting hole 36. This stopper screw 37
A cylindrical protrusion 37b is provided at the tip of the. The protrusion 37b is projected inside the clamp bolt mounting hole 31b, and the tapered portion 33d of the clamp bolt 33 (described later).
Is approached to the surface of. Stopper screw mounting hole
The side surface of the clamp bolt mounting hole 31b facing 36 is provided with a tip surface 31i extending in the axial direction of the adapter body 31.
A backup ball mounting hole 38 is formed which penetrates up to the inside and accommodates a spherical backup ball 39 therein.
The inner diameter of the backup ball mounting hole 38 is approximately equal to the distance between the tip surface 31i of the adapter body 31 and the narrowed portion 33d of the clamp bolt 33. In a state in which the rear end surface 45 of the tool body 40 described later is brought into contact with the tip end surface 31i (a state in which the tool body 40 is attached to the adapter 30), the side surface of the backup ball 39 has the narrowed portion 33d. And the rear end surface 45 and the inner wall of the backup ball mounting hole 38 are substantially in contact with each other.

The tweezers bolt mounting hole 31c is composed of a threaded portion 31c1 formed with an internal thread and an enlarged diameter portion 31c2 formed from the outer end of the threaded portion 31c1 to the side surface 31a. The expanded diameter portion 31c2 has a cylindrical support pin 50 (seventh outer diameter) having an outer diameter slightly smaller than the expanded diameter portion 31c2.
(Fig.) Is inserted with its axial direction arranged in the diametrical direction of the adapter body 31. The axial length of the support pin 50 is longer than the axial length of the expanded diameter portion 31c2. As shown in FIG. 1, the upper end of the support pin 50 projects into a tweezers bolt through hole 32e (described later) formed in the lock ring 32 and is housed in the through hole 32e. And the tweezers bolt 34 is
It penetrates through the inside of the support pin 50 and is screwed into the threaded portion 31c1 of the tweezers bolt mounting hole 31c. The outer diameter of the head portion 34a of the tweezers bolt 34 is formed larger than the inner diameter of the support pin 50, and the lower surface of the head portion 34a is supported by the upper end surface of the support pin 50.

A through hole 31d is formed at the axial center position of the adapter body 31 so as to penetrate in the axial direction. A tapered surface 31e is formed at the open end of the through hole 31d.

Further, on the rear end side of the side surface 31a of the adapter body 31,
A projecting portion 31f projecting in the outer peripheral direction is provided over the entire circumference of the side surface 31a. The projection 31f is provided with four recesses 31g that are open at the surface facing the tip side at equal intervals. Of these recesses 31g, one recess 31g is provided at a position corresponding to a clamp bolt insertion hole 32d of a lock ring 32 described later. In these recesses 31g,
The above-mentioned coil spring (elastic member) 35 is attached to each of them.

The adapter main body 31 is formed with four bolt through holes 31j penetrating from the front end surface 31i to the rear end surface thereof. Adapter body 31
A bolt (not shown) for fixing the shaft to the main shaft 20 is stored.

As shown in FIG. 5, a positioning bolt mounting hole 31k is formed in the tip surface 31i of the adapter body 31 along the axial direction of the adapter body 31. This bolt mounting hole 31k
Is a positioning bolt 51 shown by a chain double-dashed line in FIG.
Is attached with its head protruding from the tip surface 31i.

The lock ring 32 includes a fitting portion 32a externally fitted to the adapter body 31, a flange portion 32b protruding from the inner peripheral surface of the fitting portion 32a in the axial direction of the lock ring 32, and the flange portion. It is composed of two notches 32c provided in 32b (Figs. 6 and 8).

The fitting portion 32a is provided at positions corresponding to the clamp bolt mounting hole 31b and the tweezers bolt mounting hole 31c, respectively, and the clamp bolt insertion hole 32d and the tweezers bolt insertion hole 32e are formed through the fitting portion 32a in the radial direction. Are formed.

The clamp bolt insertion hole 32d has a bolt insertion portion 32f having an inner diameter larger than an outer diameter of a screw portion 33a (described later) of the clamp bolt 33, and a taper continuously formed on the outer side of the bolt insertion portion 32f. And a tapered surface 32g formed on the surface (Fig. 9). The shape of this tapered surface 32g is
The inner diameter is set to be pressed by a tapered surface 33c (described later) formed on the clamp bolt 33 when the clamp bolt 33 is inserted into the clamp bolt insertion hole 32d and tightened.

As described above, the screw portion 33 is provided on the clamp bolt 33.
a is formed, and the screw portion 33a penetrates the clamp bolt insertion hole 32d and the clamp bolt mounting hole 31b.
Is screwed into the screw part 31b1 of the. The clamp bolt 33
The lower surface of the head portion 33b of the head 33b has a tapered surface 3 having a shape corresponding to the tapered surface 32g formed in the clamp bolt insertion hole 32d.
3c is formed. Further, a tapered portion 33d having a diameter smaller than the root diameter of the screw portion 33 is provided at the tip of the screw portion 33a of the clamp bolt 33. An enlarged diameter portion 33e having an outer diameter substantially equal to the root diameter of the screw portion 33a is provided at the tip of the reduced portion 33d.

The rear end surface 41 of the rolling tool 40 is provided with a fitting portion 42 that projects rearward and is fitted into the lock ring 32. The outer diameter of the fitting portion 42 is slightly smaller than the inner diameter of the flange portion 32b of the lock ring 32.
Two flanges 44 are formed on the outer peripheral surface 43 of the fitting portion 42. The flange 44 is provided at a position corresponding to the cutout portion 32c of the flange portion 32b. The size of the collar 44 is such that it can be inserted into the cutout portion 32c. Further, the thickness of the collar 44 is such that it is sandwiched between the rear end surface of the flange portion 32b and the front end surface of the adapter body 31 when the clamp bolt 33 is tightened.

The rear end surface 45 of the fitting portion 42 is provided with a protrusion 46 that is fitted into the through hole 31d formed in the adapter body 31. The outer peripheral surface 47 of the projection 46 is formed on the adapter body 31.
Is formed in a tapered shape along the tapered surface 31e of the projection 4
When 6 is fitted in the through hole 31d, it comes into contact with the tapered surface 31e.

Further, on the rear end surface 45 of the fitting portion 42, two positioning holes 48 formed in a substantially elliptical shape are formed at positions corresponding to the positioning bolts 51. These locating holes 48
Is a state in which the protrusion 44 of the tool body 40 is arranged at the position of the notch 32c of the lock ring 32 and the protrusion 46 is fitted into the through hole 31d, and the head of the positioning bolt 51 is positioned in the positioning hole 48. The head of the positioning bolt 51 is moved to the other end 48b side with the rotation of the tool body 40 and abuts on the other end 48b.

Further, three throw-away tips 60 are detachably attached to the tip surface 49 of the tool body 40.

Next, a method for attaching / detaching the rolling tool 40 to / from the spindle 20 of the tool machine using the rolling tool fastening device configured as described above will be described.

First, the adapter body 31 is fixed to the spindle 20 of the machine tool with bolts. Then, fit the fitting portion 32a of the lock ring 32 to the outer circumference of the adapter body 31, align the positions of the clamp bolt insertion hole 32d and the clamp bolt mounting hole 31b, and then insert the clamp bolt 33 from the clamp bolt insertion hole 32d. Screw it into the clamp bolt mounting hole 31b. Similarly, after aligning the positions of the tweezers bolt insertion hole 32e and the tweezers bolt mounting hole 31c and inserting the support pin 50 into the expanded diameter portion 31c2, the inside of the support pin 50 is pierced and the tweezers bolt 34 is inserted. Screw it into the tweezers bolt mounting hole 31c. In the above work, the clamp bolt 33 is kept in a slightly loosened state. Then, the coil spring 35 attached to the adapter body 31 presses the lock ring 32 in the front end direction (left in FIG. 1), and the vicinity of the clamp bolt through hole 32d of the lock ring 32 has the support pin 50 and the tweezers bolt. It rotates slightly around 34 in the clockwise direction in FIG. 1 and is slightly raised with respect to the adapter body 31.

Then, the stopper screw 37 is screwed into the stopper screw mounting hole 36, and the protrusion 37b of the stopper screw 37 is fixed to the clamp bolt 33.
The locking screw 37a is screwed in behind the stopper screw 37 to prevent the stopper screw 37 from loosening. On the other hand, the backup ball 39 is housed in the backup ball mounting hole 38, and the mouth of the backup ball mounting hole 38 is held so that the backup ball 39 does not drop due to caulking.

Then, the position of the collar 44 formed in the fitting portion 42 of the rolling tool 40 is aligned with the position of the cutout portion 32c of the lock ring 32, and the protrusion 46 is fitted into the through hole 31d of the adapter body 31,
The rear end surface 45 of the fitting portion 42 is brought into contact with the front end surface 31i of the adapter body 31. Then, the positioning hole 48 accommodates the head of the positioning bolt 51 on the side of the one end 48a thereof, and the rear end surface 45
Contacts the surface of the backup ball 39 and holds the backup ball 39 in the backup ball mounting hole 38.

Then, the rolling tool 40 is rotated clockwise when viewed from the tip end surface side, and the positioning bolt 51 is moved to the other end 48 of the positioning hole 48.
Contact b and stop the rotation work. Then, the clamp bolt 33, which has been loosened as described above, is tightened. Then, the clamp bolt 33 moves toward the adapter body 31,
The tapered surface 33c formed on the head 33b of the clamp bolt 33 contacts the tapered surface 32g of the clamp bolt through hole 32d, and a force is applied to the tapered surface 32g in the rear end direction (rightward in FIG. 1). To be As a result, the lock ring 32 moves toward the adapter body 31 against the pressing force of the coil spring 35. As a result, the flange 44 formed on the rolling tool 40 is pressed toward the rear end by the flange portion 32b formed on the lock ring 32, and the flange 44b is formed between the flange portion 32b and the tip surface 31i of the adapter body 31. Pinch and insert the rolling tool 40 into the adapter 30
Can be securely mounted.

Further, when the rolling tool 40 is removed from the adapter 30, the above procedure may be reversed. That is, when the clamp bolt 33 is loosened, the tapered surface 33c of the head portion 33 of the clamp bolt 33 moves in a direction away from the clamp bolt insertion hole 32g, and the pressing of the tapered surface 33c on the tapered surface 32g is released. The elastic force of the coil spring 35 causes the lock ring 32 to slightly rotate clockwise around the head of the tweezers bolt 34 in FIG. For this reason,
The flange portion 32b of the lock ring 32 is separated from the surface of the collar 44. In this state, the rolling tool 40 is rotated counterclockwise as viewed from the tip end surface thereof, and the head of the positioning bolt 51 is brought into contact with the one end 48a of the positioning hole 48 to stop the rotation. At this time, since the position of the collar 44 faces the cutout portion 32c, the rolling tool 40 can be removed from the adapter 30 while the flange 44 is inserted through the inside of the cutout portion 32c.

In the fastening device of the present embodiment, since the protrusion 37b of the stopper screw 37 is brought close to the reduced portion 33d of the clamp bolt 33, when the clamp bolt 33 is loosened excessively, the expanded diameter portion 33e of the clamp bolt 33 is The upper end abuts on the outer peripheral surface of the protrusion 37d, so that the clamp bolt 33 can be prevented from falling off.

In addition, when removing the rolling tool 40,
Tapered surface 47 of protrusion 46 of 40 and through hole 31d of adapter body 31
Clamp bolt 33
Even if it is loosened, the rolling tool 40 cannot be rotated and it may be difficult to remove it.In this case, remove the lock screw 37a and loosen the stopper screw 37 to remove the protrusion 3
7b should be separated from the tapered portion 33d, and the stopper screw mounting hole 36
It is sufficient to loosen the clamp bolt 33 sufficiently after storing it inside. That is, the clamp bolt 33 and the expanded portion 33
Since e is provided, when the clamp bolt 33 is loosened, the expanded diameter portion 33e comes into contact with the surface of the backup ball 39 and pushes the backup ball 39 in the tip direction. For this reason, this backup ball 39
Since the rear end surface 45 of the 40 is pressed toward the front end, the work of removing the fitting between the rolling tool 40 and the adapter body 31 becomes easy.

According to the above-described fastening device of the present embodiment, the conventional means for fixing the rolling tool 40 to the adapter body 31 by using the clamp bolt penetrating the adapter body 31 is not used as a hollow adapter. The thing of goods can be used. In addition, by rotating the clamp bolt 33 without the trouble of fixing the adapter body and the lock ring with both hands and rotating the lock ring to attach and detach the rolling tool, as in the conventional case. The rolling tool 40 can be attached to and detached from the adapter 30, and the attachment and detachment work of the rolling tool 40 is easy. In addition, 40 cutting tools
Since the rolling tool 40 is not likely to fall when the locking tool is locked to the lock ring 32, even if the rolling tool 40 is not supported one by one when the clamp bolt 33 is rotated. It is possible to improve the certainty of the work without the 40 being dropped and damaged.

[Advantage of the Invention] The present invention provides an adapter including an adapter body, a lock ring, a clamp bolt, and a tweezers bolt, and a clamp bolt mounting hole and a tweezers bolt mounting hole are formed on a side surface of the adapter body. An elastic member is attached to the tip side of the main body, and the lock ring has a ring-shaped fitting portion, a flange portion, and a notch portion provided in the flange portion, and the fitting portion has a clamp bolt insertion hole. And a tweezers bolt insertion hole is formed, the clamp bolt insertion hole is provided with a bolt insertion portion and a tapered surface, a flange is formed on the outer peripheral surface of the rolling tool,
The clamp bolt is screwed into the clamp bolt attachment hole from the clamp bolt insertion hole, a tapered surface is formed on the head of the clamp bolt, and the tweezers bolt is inserted from the tweezers bolt insertion hole to the tweezers bolt attachment hole. Since the rolling tool fastening device is screwed in, a hollow adapter can be used as the adapter. Further, the turning tool can be attached to and detached from the adapter by rotating the clamp bolt, and the work of attaching and detaching the cutting tool is easy. Furthermore, when the rolling tool is locked to the lock ring, there is no risk of the rolling tool falling, so even if the rolling tool is not supported one by one when the clamp bolt is rotated. The tool will not be dropped and damaged, and the reliability of the work can be improved.

[Brief description of drawings]

1 to 12 are views showing an embodiment of a fastening device of the present invention, FIG. 1 is an exploded vertical sectional view of the fastening device, FIG. 2 shows an adapter body, and an arrow A direction in FIG. FIG. 3 is a sectional view of the adapter body taken along line BB in FIG. 2, FIG. 4 is a partially omitted sectional view taken along line CC of FIG. 2, and FIG. 5 is D of FIG.
-Partial cross-sectional view of line D, FIG. 6 is a view showing the adapter, and is a view taken in the direction of the arrow E in FIG. 1. FIG. The figure is a front view of the lock ring, FIG. 9 is a sectional view taken along the line FF of FIG. 8, FIG. 10 is an enlarged side view of the clamp bolt, and FIG. 11 is a view showing the rear end surface of the rolling tool. 1 is a view from the direction of G in FIG. 1, FIG. 12 is a view showing the tip end surface of the rolling tool, FIG. 1 is a view from the direction of H in FIG. 1, and FIGS. 13 to 15 are views showing a conventional fastening device. , FIG. 13 is a view showing the front end surface of the fastening device, FIG. 14 is a longitudinal sectional view of the fastening device,
FIG. 15 is a vertical sectional view of the fastening device. 20 …… Machine tool spindle, 30 …… Adapter, 31 …… Adapter body, 31a …… Adapter body side, 31b… Clamp bolt mounting hole, 31c… Tweezer bolt mounting hole, 31d…
… Through hole, 31i …… Tip surface of adapter body, 32… Lock ring, 32a… Fitting part, 32b… Flange part, 32c…
… Notch, 32d …… Clamp bolt insertion hole, 32e ……
Tweezers bolt insertion hole, 32f …… Bolt insertion part, 32g…
… Tapered surface, 33 …… Clamp bolt, 33b …… Clamp bolt head, 33c …… Tapered surface, 34 …… Tweezer bolt, 35 …… Coil spring (elastic member), 40 …… Rolling tool, 43… ... peripheral surface, 44 ... tsuba.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideo Moronuki 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Corporation

Claims (1)

(57) [Scope of utility model registration request] 1. An adapter is fixed to a tip end portion of a main shaft of a machine tool, and a protrusion formed on a rear end side of a rolling tool is fitted into a through hole formed at an axial center position of the adapter,
By engaging the flange formed on the outer peripheral surface of the rolling tool with the flange portion projecting in the axial direction from the tip of the adapter,
A fastening tool fastening device adapted to attach a rolling tool to a machine tool, wherein the adapter is a cylindrical adapter body attached to a tip end portion of a spindle of the machine tool, and is attached to a tip end side of the adapter body. Lock ring and a clamp bolt and a tweezers bolt for attaching the lock ring to the adapter body, and a clamp bolt having a female screw formed on a side surface of the adapter body and facing each other. An attachment hole and a tweezers bolt attachment hole are formed, and an elastic member for urging the lock ring in the tip direction is attached to the tip end side of the adapter body, and the lock ring is a ring externally fitted to the adapter body. -Shaped fitting part and a flange that is provided so as to project from the inner peripheral surface of the fitting part in the axial direction of the lock ring. And a plurality of notches provided in the flange, and the fitting portion is provided at positions corresponding to the clamp bolt mounting hole and the tweezers bolt mounting hole, respectively, and penetrates in the radial direction. Clamp bolt insertion hole and tweezers bolt insertion hole are formed, the clamp bolt insertion hole,
The bolt insertion portion having an inner diameter larger than the outer diameter of the threaded portion of the clamp bolt, and a tapered surface continuously formed on the outside of the bolt insertion portion in a tapered shape. The outer peripheral surface of the tool is provided at a position corresponding to the cutout portion of the flange portion, and can be inserted through the cutout portion and the rear end surface of the flange portion as the rolling tool rotates. A collar having a thickness is formed so as to be sandwiched between the tip of the adapter body and the clamp bolt, and the clamp bolt is screwed into the clamp bolt attachment hole from the clamp bolt insertion hole. Has a tapered surface that abuts a tapered surface formed in the clamp bolt insertion hole, and the tweezers bolt is inserted from the tweezers bolt insertion hole to the tweezers bolt. Milling tool fastening device, characterized in that it is threaded in with the hole.