JP5581552B2 - Tool holder - Google Patents

Description

  The present invention relates to a tool holder capable of performing a cutting operation while ejecting a cutting fluid mist in which the cutting fluid is atomized from a tip portion.

  For tool holders that can perform cutting operations while jetting the cutting fluid mist, the cutting fluid mist is caused by centrifugal force, gravity, etc. if it is a rotary type, and by gravity etc. even if it is not a rotary type. In some cases, the cutting fluid mist cannot be stably supplied due to adhesion and accumulation on the outer periphery of the supply flow path. In addition, when the cutting operation is stopped, the accumulated cutting fluid is released from centrifugal force and gravity, and may droop unexpectedly.

  As a technique for solving this problem, for example, there is a technique described in Patent Document 1 for a rotary tool holder. The technique described in Patent Document 1 includes an inner hole in which a downstream opening is smaller in diameter than an upstream opening in a supply flow path (in the literature, “mist passage”) in front of a tool holder, and the inner hole. A nozzle having an outer hole formed radially outward is provided.

  The cutting fluid mist is centrifuged by rotation, and the concentration of the cutting fluid mist is different between the radially outer side and the center side of the supply flow path. The cutting fluid mist flows through the inner hole, the air velocity is accelerated, and the high-concentration outer cutting fluid mist flows through the outer hole. Then, in the space where the inner hole and the outer hole merge, the cutting fluid mist flowing through the outer hole is mixed with the cutting fluid mist accelerated through the inner hole, and can be re-misted.

JP 2000-158285 A

  However, the cutting fluid mist is highly likely to be reliquefied when flowing through the outer hole. For this reason, when the re-liquefied cutting fluid having a large specific gravity is discharged from the outer hole to the merged space, the cutting fluid mist that has circulated through the inner hole is simply pressed against the outer periphery of the merged space by centrifugal force and accumulated. There is a possibility that it is not mixed well and re-misting cannot be achieved efficiently.

  In view of the above circumstances, an object of the present invention is to provide a tool holder capable of reliably re-misting and stably supplying a cutting fluid mist.

  The first characteristic configuration of the tool holder according to the present invention includes a holder main body to which a cutting tool can be attached at a front end portion, and provided inside the holder main body along a central axis of the holder main body, and a rear end of the holder main body A supply channel that supplies cutting fluid mist from the side toward the tip, and the flow channel cross-sectional area of the supply channel is reduced in order from the upstream side to the downstream side of the supply channel. A diameter-reduced part, a diameter-enlarged part that expands the flow-path cross-sectional area narrowed by the first diameter-reduced part at least more than the flow-path cross-sectional area upstream of the first diameter-reduced part, and the diameter-expanded part An enlarged space having the cross-sectional area of the flow path expanded by the above, and a second reduced diameter portion for reducing the cross-sectional area of the flow path of the enlarged diameter space, and the central axis on the outer peripheral portion of the expanded diameter space And a plurality of recesses along the direction intersecting with the central axis.

  With this configuration, for example, a part of the cutting fluid mist is supplied by a centrifugal force or gravity in the case of a rotary tool holder or by gravity in a non-rotary tool holder. The cutting fluid adhering to, depositing, and liquefying on the outer peripheral portion is sent to the downstream side by the air current of the cutting fluid mist, and is particularly deposited on the outer peripheral portion of the enlarged diameter portion. On the other hand, the air velocity of the cutting fluid mist is accelerated when passing through the first reduced diameter portion, and the cutting fluid mist is ejected from the first reduced diameter portion into the enlarged space. In other words, since the accelerated air flow is released from a small channel cross-sectional area (atmospheric pressure) to a large channel cross-sectional area (at low air pressure), the cutting fluid mist diffuses somewhat radially. To do. Therefore, although the cutting fluid mist near the central axis flows straight down as it is, a portion of the cutting fluid mist collides with the second reduced diameter portion and convects or diffuses in the radially outward direction to expand the diameter. It is sprayed directly on the outer peripheral part.

  In addition, a plurality of recesses are formed along the central axis on the outer peripheral surface of the expanded space, and the above-described liquefied cutting fluid accumulates in the recesses. The concave portion is along the direction intersecting the central axis, that is, intersecting the direction of the airflow blown to the outer peripheral portion of the enlarged diameter space and the direction of convection. Therefore, the cutting fluid accumulated in the recesses splashes in the radial direction so as to be splashed from the corners of the recesses by a convective airflow or an airflow directly blown, and re-mists. Even if it drops in the form of droplets, it will splash in the radial direction, so it will be repelled and diffused by the air current of the cutting fluid mist that flows into the second reduced diameter portion and has no turbulence. It is re-misted.

  Since the second reduced diameter part is provided downstream of the enlarged diameter part, the air velocity of the cutting fluid mist including the remisted cutting fluid mist is accelerated, the mists are less likely to aggregate, and reliquefaction is prevented. Is done.

  Thus, with the tool holder of this configuration, re-misting can be reliably achieved, and stable cutting fluid mist can be supplied.

  The second characteristic configuration of the tool holder according to the present invention is such that the first reduced diameter portion and the second reduced diameter portion are set so as to gradually reduce the flow path cross-sectional area, and the first reduced diameter portion and In the point which provided the 1st step part in the boundary part with the said enlarged diameter part.

  According to this configuration, since the first reduced diameter portion and the second reduced diameter portion gradually reduce the cross-sectional area of the flow path, the air current of the cutting fluid mist is less likely to be disturbed and smoothly flows, and the air velocity is efficiently accelerated. The In addition, since the first step portion is provided at the boundary portion between the first reduced diameter portion and the enlarged diameter portion, the flow passage cross-sectional area of the supply flow path is suddenly widened by the first step portion, and the air flow and the supply flow The edge with the road is cut, and the airflow is difficult to follow along the surface of the enlarged diameter portion. As a result, the air velocity of the cutting fluid mist does not decrease, convection and the like are likely to occur, and the re-misting of the cutting fluid accumulated in the recess is promoted.

  A third characteristic configuration of the tool holder according to the present invention is that a second step portion is provided at a boundary portion between the diameter-expanded space and the second reduced-diameter portion.

  If it is this structure, the cutting fluid collected in the diameter expansion space will be collided by the 2nd step part by the airflow which distribute | circulates the surface vicinity, will be splashed toward the radial inside direction, and will be re-misted. Even if the liquid drops in the form of droplets, they will splash toward the inner radial direction, so that they will be bounced and diffused by the airflow of the cutting fluid mist flowing into the second reduced diameter portion with a high airflow velocity, and the cutting fluid will surely be re-misted. It becomes.

  A fourth characteristic configuration of the tool holder according to the present invention is that the flow passage cross-sectional area in the second step portion is at least larger than the flow passage cross-sectional area in the first step portion.

  According to this configuration, since the flow passage cross-sectional area in the second step portion is larger than the flow passage cross-sectional area in the first step portion, the air current of the cutting fluid mist diffused from the first step portion can be received in a wide area, The cutting fluid mist flows smoothly from upstream to downstream.

  A fifth characteristic configuration of the tool holder according to the present invention is that the position of the second step portion can be changed in the direction of the central axis.

  With this configuration, it is possible to optimize the re-misting in each condition by changing the position of the second step portion in the direction of the central axis in accordance with the amount of cutting fluid mist ejected.

  A sixth feature configuration of the tool holder according to the present invention includes a cylindrical throttle member that can be inserted and fixed to the supply flow path, and includes the second step portion at an insertion side end of the throttle member, And it exists in the point which formed the said 2nd diameter reduction part in the inner peripheral part of the said aperture_diaphragm | restriction member.

  With this configuration, the supply channel can be provided with the second step portion and the second reduced diameter portion only by inserting and fixing the throttle member in the supply channel without performing complicated processing inside the holder body. it can.

  A seventh feature of the tool holder according to the present invention is that the throttle member can be inserted and fixed to the supply flow path by screwing, and is a screw groove for screwing formed in the inner periphery of the holder body. Is the recess.

  Although it is difficult to give a complicated shape to the inside of the passage-shaped hole, in this configuration, the screw channel for screwing and fixing also serves as the concave portion, so that the processing of the supply channel is easy.

It is a side view of the tool holder concerning the present invention. It is a sectional side view of a tool holder. It is sectional drawing of diameter expansion space vicinity. It is an expanded sectional view of the perimeter part of diameter expansion space. It is sectional drawing of diameter-expansion space vicinity in another embodiment. It is an expanded sectional view of the middle vicinity in the outer peripheral part of diameter expansion space concerning another embodiment. It is an expanded sectional view of the upstream vicinity in the outer peripheral part of the diameter expansion space which concerns on another embodiment. It is an expanded sectional view of the downstream vicinity in the outer peripheral part of the diameter expansion space which concerns on another embodiment.

  An example in which the present invention is applied to a rotary tool holder will be described with reference to the drawings.

〔Overview〕
As shown in FIG. 1, the tool holder can be attached with a cutting tool P at the tip, and is attached to the holder body 1 inserted and supported by the machine tool spindle B and the rear end on the insertion side of the holder body 1. And a pull bolt 5. The holder main body 1 can be driven to rotate about a rotation axis X as a “center axis” by a motor (not shown) provided on the machine tool spindle B. The holding portion 51 is formed by recessing the outer peripheral surface of the pull bolt 5. The holder main body 1 is held on the machine tool spindle B by being pulled inward while holding the holding part 51 in the insertion direction by the clamp C on the machine tool spindle B side. A chuck 2 is provided at the tip of the holder body 1, and the cutting tool P can be detached from the holder body 1 by the chuck 2. The cutting fluid mist M can be supplied from the mist supply port 53 of the pull bolt 5 which is the rear end side of the tool holder, and can be ejected from the tip of the cutting tool P to the workpiece during the cutting operation.

  Hereinafter, the pull bolt 5 side is referred to as “upstream side” and “rear end side”, and the cutting tool P side is referred to as “downstream side” and “front end side”.

〔Chuck〕
As shown in FIG. 2, the chuck 2 has a general configuration, and roughly includes a cylindrical tightening nut 21 and a cylindrical collet 22. The tightening nut 21 is externally inserted into the holder body 1 so as to be able to be screwed. When the tightening nut 21 is tightened, the tightening nut 21 moves along the direction of the rotation axis X. The collet 22 is inserted into the holder main body 1 so as to be slidable along the rotation axis X while being locked so as to be rotatable relative to the tightening nut 21. A plurality of slits are formed in the collet 22 along the direction of the rotation axis X. By tightening the tightening nut 21, the collet 22 is inserted without rotating relative to the holder main body 1, and is bent and reduced in diameter by a wedge action by a tapered surface inside the holder main body 1. . With this reduced diameter, the entire circumference of the cutting tool P inserted into the collet 22 can be clamped uniformly.

[Supply channel]
As shown in FIG. 2, the cutting fluid mist M is supplied from a mist supply port 53 on the rear end side of the pull bolt 5, and is provided in a supply flow path 10 provided in the holder body 1 and in a cutting tool P (not shown). It circulates through the hole and is ejected from the tip of the blade P. The cutting fluid mist M is generated by mixing the cutting fluid L and compressed air in a mist generating section (not shown), and is fed by pressure to the mist supply port 53 with a certain air velocity. The supply flow path 10 includes a hole 52 drilled in the pull bolt 5, a hole 61 drilled in the third nozzle 6, a pipe 7, a hole 31 drilled in the first nozzle 3, and a diameter expansion space 12. The hole 41 is formed in the second nozzle 4 as a “throttle member”.

  As a method for assembling each member, a hole 11 along the rotation axis X is drilled in the holder body 1, and the first nozzle 3 and the second nozzle 4 are connected to the hole 11 from the tip side. The pipe 7, the third nozzle 6, and the pull bolt 5 are inserted and fixed in order from the rear end side.

  A screw groove 13 is formed from the center portion to the vicinity of the tip portion of the hole portion 11. The first nozzle 3 and the second nozzle 4 can be inserted and fixed by being screwed into the hole 11 of the holder body 1 and can be freely adjusted in position in the rotation axis X direction. There is almost no gap between the first nozzle 3 and the second nozzle 4 and the hole 11 of the holder body 1. A plurality of screw grooves 13 are formed along the rotation axis X in a shape along the direction substantially orthogonal (crossing) with the rotation axis X at the outer peripheral portion of the diameter-enlarged space 12. Corresponds to “concave”.

  The hole 31 of the first nozzle 3 is along the rotation axis X, has the largest flow path cross-sectional area at the upstream end, and is gradually reduced in diameter in a tapered shape toward the downstream. Of the hole 31, a portion that is reduced in a taper shape corresponds to the “first reduced diameter portion 32” according to the present invention, and an end portion on the downstream side of the first nozzle 3 is an “expanded diameter portion” according to the present invention. 33 ". Further, the enlarged diameter portion 33 is a surface substantially orthogonal to the rotation axis X, and the downstream edge of the hole 31 is angular. This angular portion corresponds to the “first step portion 34” according to the present invention.

  The hole 41 of the second nozzle 4 is along the rotational axis X, has the largest flow path cross-sectional area at the upstream end, and is gradually reduced in a taper shape toward the downstream side. From the vicinity of the portion, the diameter is increased again in a tapered shape. The second nozzle 4 is positioned so as to be separated from the first nozzle 3, thereby forming an enlarged diameter space 12. A portion of the hole 41 that is reduced in a taper shape corresponds to the “second reduced diameter portion 42” according to the present invention. Further, the upstream end portion of the second nozzle 4 is a surface substantially orthogonal to the rotation axis X, and the upstream end edge of the hole portion 41 is angular. This angular portion corresponds to the “second step portion 43” according to the present invention.

  The elastic member 44 is fixed to the entire diameter-enlarged portion of the hole 41 of the second nozzle 4. When the cutting tool P is fixed by the chuck 2, the cutting tool P is inserted until it comes into contact with the elastic member 44. Accordingly, the elastic member 44 serves as a buffer material and the second nozzle 4 and the cutting tool P do not rattle each other while the diameter-enlarged portion of the hole is used as a positioning member for the cutting tool P. Mist leakage can be prevented.

  The hole 61 of the third nozzle 6 is along the rotation axis X, and is tapered toward the downstream side in the vicinity of the upstream end, and thereafter has a constant channel cross-sectional area. Yes. The pipe 7 has a constant flow path cross-sectional area over its entire length. The pipe 7 is press-fitted into the hole 61, and the third nozzle 6 and the pipe 7 are integrated. A step is formed near the middle of the hole 11 of the holder main body 1, and an annular end member 8 inserted from the rear end side is locked to the step.

  The outer diameter of the third nozzle 6 is set slightly smaller than the inner diameter of the hole 11 of the holder body 1. The third nozzle 6 and the pipe 7 are inserted into the hole 11 of the holder main body 1 in a state where the spring 7 is sheathed on the pipe 7. Finally, the pull bolt 5 is screwed into the hole 11 of the holder body 1 and fixed, and the third nozzle 6 and the pipe 7 are prevented from coming out of the hole of the holder body 1. Since the spring 9 is disposed across the third nozzle 6 and the end member 8, the third nozzle 6 is constantly urged toward the rear end side so as to contact the pull bolt 5 by the urging force of the spring 9, and the pull bolt There is no gap between 5 and the third nozzle 6. Further, since the seal member 62 is disposed at the rear end side of the third nozzle 6, the cutting fluid mist M does not leak from between the pull bolt 5 and the third nozzle 6.

  The outer diameter of the pipe 7 is smaller than the outer diameter on the upstream side of the first reduced diameter portion 32 and larger than the outer diameter on the downstream side of the first reduced diameter portion 32. Therefore, the downstream end of the pipe 7 is fitted into the inner peripheral surface of the first reduced diameter portion 32, and the supply flow path 10 is smoothly connected. Depending on the specifications of the machine tool spindle B, the length of the pull bolt 5 in the direction of the rotational axis X may be changed. In particular, when the length of the pull bolt 5 is shortened, there is no gap between the pull bolt 5 and the third nozzle 6 due to the action of the spring 9, but the total length of the third nozzle 6 and the pipe 7 is constant. Therefore, a gap may be generated between the pipe 7 and the first reduced diameter portion 32. However, since the airflow speed of the cutting fluid mist M is fast, the cutting fluid mist M hardly leaks from the gap.

  The supply flow path 10 is configured as described above, and the flow path cross-sectional area of the supply flow path 10 is constant from the mist supply port 53 to the middle of the third nozzle 6 and is tapered in the middle of the third nozzle 6. After that, it is constant up to the downstream end of the pipe 7. Further, the flow passage cross-sectional area is narrowed in a tapered shape by the first reduced diameter portion 32 and is expanded at once by the enlarged diameter portion 33. Further, the flow passage cross-sectional area of the supply flow passage 10 is constant in the diameter-expanded space 12, but after being narrowed again at the second step portion 43 and tapered at the second diameter-reduced portion 42, It is expanded again so as to correspond to the end surface on the rear end side of the cutting tool P.

  As is clear from FIG. 2, the flow passage cross-sectional area in the enlarged diameter space 12 is the largest, and the flow passage cross-sectional area in the second step portion 43 is the upstream side of the first step portion 34 and the first step portion 34. It is larger than the flow path cross-sectional area.

[Distribution of cutting fluid mist]
As shown in FIG. 2, the cutting fluid mist M supplied from the mist supply port 53 flows toward the downstream side, and is first accelerated smoothly at the reduced diameter portion of the third nozzle 6. And it distribute | circulates, maintaining the airflow speed, and is accelerated more smoothly by the 1st reduced diameter part 32. FIG.

  Since the tool holder is rotating during the operation, a centrifugal force is applied to the cutting fluid mist M somewhat, and the cutting fluid mist M flows from the upstream side to the downstream side along the rotation axis X while swirling. To do. A part of the cutting fluid mist M adheres to and accumulates on the outer peripheral surface of the supply passage in the middle of circulation. The liquefied cutting fluid L is pushed downstream by the air current of the cutting fluid mist M while adhering to the outer peripheral surface of the supply passage by centrifugal force, and accumulates in the outer peripheral portion of the expanded space 12 as shown in FIG. That is, the cutting fluid L accumulates in the screw groove 13 exposed to the enlarged space 12. The cutting fluid L has a surface shape as shown in FIGS. 3 and 4 due to centrifugal force, the air current of the cutting fluid mist M, its own surface tension, etc. Accumulate at 13.

  Since the expanded diameter space 12 is considerably wider than the hole 31, the pressure of the hole 31 is higher than the pressure of the expanded diameter 33. Therefore, the cutting fluid mist M accelerated by the first reduced diameter portion 32 is ejected vigorously while being diffused somewhat radially from the hole portion into the enlarged diameter space 12, as shown in FIG. As a result, the air flow around the rotation axis X flows straight down along the rotation axis X toward the hole 41, but the gradient of the second staying portion is tight, so that part of the cutting fluid mist M Hits the second reduced diameter portion 42 and convects in the radially outward direction. Moreover, since the square stepped first portion 34 is provided, the edge between the air flow and the supply flow path 10 is cut, and the cutting fluid mist M is unlikely to follow the enlarged diameter portion 33, so that the above-described air flow is likely to occur.

  As shown in FIG. 4, the air current of the convected cutting fluid mist M passes through the surface of the cutting fluid L accumulated in the thread groove 13 at a high speed. As a result, the cutting fluid L is wound up at the tooth tip of the screw groove 13 and splashes in the radially inward direction so as to increase the splash, thereby re-misting. Even if it is splashed in the form of droplets, it will splash toward the inner radial direction, so there will be no turbulence that goes straight in the vicinity of the rotation axis X, and it will be bounced and diffused by the air current of the cutting fluid mist M that has a high air velocity, The cutting fluid L is reliably re-misted.

  In addition, since the supply flow path 10 is reduced in diameter by the second reduced diameter portion 42, the air flow velocity of the cutting fluid mist M including the remisted cutting fluid mist M is accelerated, and the mists are less likely to agglomerate. Liquefaction is prevented.

  In addition, since the second nozzle 4 portion is movable in the direction of the rotation axis X, for example, if the amount of ejection of the cutting fluid mist M (ejection pressure) is increased, the flow of the airflow may be slightly changed. By changing the position of the two nozzles 4, it is possible to adjust to a state where optimum re-misting can be realized.

[Another embodiment]
An example in which the gradient of the second reduced diameter portion 42 in the second nozzle 4 is set to be gentler than that in the above-described embodiment will be described with reference to FIGS. Since other configurations are the same as those in the above-described embodiment, they will not be described. In addition, the same code | symbol shall be attached | subjected about the same structure as the structure of the above-mentioned embodiment.

  As shown in FIG. 5, the cutting fluid mist M accelerated by the first reduced diameter portion 32 is ejected vigorously while diffusing radially from the hole portion into the enlarged diameter space 12. As a result, an airflow state as shown in the above-described embodiment may occur, but the airflow in the vicinity of the rotation axis X flows straight down toward the hole 41 along the rotation axis X, and In some cases, a part of the cutting fluid mist M is blown against the screw groove 13 and another part of the cutting fluid mist M is blown back against the enlarged diameter portion 33 to be convected. The flow of the airflow in this case will be described in detail below.

  As shown in FIG. 6, in the vicinity of the middle of the enlarged diameter portion 33 in the rotation axis X direction, the diffused air flow of the cutting fluid mist M collides with the surface of the cutting fluid L accumulated in the screw groove 13. In addition, it passes at high speed. As a result, the cutting fluid L is wound up at the tooth tip of the screw groove 13 and splashes in the radially inward direction so as to increase the splash, thereby re-misting. Even if splashed in the form of droplets, it splashes in the radial direction, so it is bounced and diffused by the air current of the cutting fluid mist M that travels straight toward the second diameter-reduced portion 42 and has no turbulence and has a high air velocity. The cutting fluid L is reliably re-misted.

  As shown in FIG. 7, similarly, the air current of the convective cutting fluid mist M is rewound upstream of the cutting fluid L accumulated in the screw groove 13 in the vicinity of the upstream side of the enlarged diameter portion 33 in the rotation axis X direction. Passes fast at high speed. Thereby, at the tooth tip of the screw groove 13, the cutting fluid L is wound up and splashes in the radial inner direction so as to raise the splash, and is re-misted.

  As shown in FIG. 8, in the vicinity of the downstream side of the diameter-expanded portion 33 in the direction of the rotation axis X, the diameter of the radially dispersed air current of the cutting fluid mist M merges with the airflow flowing in the vicinity of the rotation axis X. While correcting the trajectory in the inward direction, the surface of the cutting fluid L accumulated in the thread groove 13 is pushed downstream. Then, in the second step portion, the cutting fluid L is wound up and splashes in the radial direction so as to raise the splash, and re-misted.

  As can be understood from the description of the above-described embodiment and the present embodiment, not only the change in the air flow velocity of the cutting fluid mist M, but also the gradient of the second reduced diameter portion 42, the first nozzle 3 and the second nozzle 4, The flow of the air current of the cutting fluid mist M may also be changed by changing various conditions such as the separation distance (the length of the diameter expansion space 12 in the direction of the rotation axis). However, according to the present invention, the optimum re-misting of the cutting fluid mist M can be realized regardless of the flow of airflow.

[Other alternative embodiments]
(1) In the above-described embodiment, an example in which the present invention is applied to a rotary tool holder has been described. However, the present invention is not limited to this. The present invention may be applied to a non-rotating tool holder.

(2) In the above-described embodiment, the cutting fluid mist M is ejected from the distal end portion of the cutting tool P. However, the cutting fluid mist M is ejected from the distal end portion of the collet 22 without attaching the cutting tool P. May be.

(3) In the above-described embodiment, the thread groove 13 for screwing the second nozzle 4 as the “concave portion” is described as an example, but the present invention is not limited to this. In the outer peripheral portion of the diameter expansion space 12, if a plurality of concave portions are formed along the rotation axis X along the direction substantially orthogonal to the rotation axis X, for example, provided in pieces along the circumferential direction. It may be a concave portion. Further, the concave portion and the convex portion are in an integrated relationship, and a convex portion may be formed instead of the concave portion.

  The present invention provides a holder main body capable of attaching a cutting tool to a tip end portion, and is provided inside the holder main body along the central axis of the holder main body, and supplies cutting fluid mist from the rear end side of the holder main body toward the tip end portion. The present invention can be applied to various tool holders including a supply flow path.

1 Holder body 4 Second nozzle (aperture member)
10 Supply passage 12 Expanded space 13 Thread groove (recess)
32 1st diameter-reduced part 33 diameter-expanded part 34 1st step part 42 2nd diameter-reduced part 43 2nd step part X Rotation axis (center axis)
P Cutting tool M Cutting fluid mist

Claims (7)

A holder body capable of attaching a cutting tool to the tip,
A supply flow path that is provided inside the holder main body along the central axis of the holder main body and supplies a cutting fluid mist from the rear end side of the holder main body toward the front end portion,
In order from the upstream side to the downstream side of the supply channel, a first reduced diameter portion for reducing the flow path cross-sectional area of the supply flow channel, and at least the flow path cross-sectional area reduced by the first reduced diameter portion A diameter-enlarging portion that expands more than the channel cross-sectional area upstream of the first diameter-reducing portion, a diameter-enlarging space that has the channel cross-sectional area expanded by the diameter-enlarging portion, and the diameter-enlarging space A second reduced diameter portion for reducing the cross-sectional area of the flow path,
A tool holder in which a plurality of recesses along the direction intersecting the central axis are formed along the central axis in an outer peripheral portion of the diameter expansion space.   The first reduced diameter portion and the second reduced diameter portion are set so as to gradually reduce the flow path cross-sectional area, and a first step portion is formed at a boundary portion between the first reduced diameter portion and the enlarged diameter portion. The tool holder according to claim 1, comprising:   The tool holder according to claim 2, further comprising a second step portion at a boundary portion between the diameter-expanded space and the second reduced-diameter portion.   The tool holder according to claim 3, wherein the flow path cross-sectional area in the second step portion is at least larger than the flow path cross-sectional area in the first step portion.   The tool holder according to claim 3 or 4, wherein the position of the second step portion can be changed in the direction of the central axis. A cylindrical throttle member that can be inserted and fixed to the supply flow path,
6. The device according to claim 3, wherein the second stepped portion is provided at an end portion on the insertion side of the throttle member, and the second reduced diameter portion is formed on an inner peripheral portion of the throttle member. Tool holder as described.   The tool holder according to claim 6, wherein the throttle member can be inserted and fixed to the supply flow path by screwing, and a screw groove for screwing formed in an inner peripheral portion of the holder body is the concave portion. .

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