Patent Description:
A dental handpiece rotates a cutting tool attached to the dental handpiece at a high speed. Therefore, the cutting tool generates heat when cutting a tooth. This may adversely affect a living body. Thus, the dental handpiece has a function of introducing spray water onto the cutting tool so as to cool the cutting tool.

The dental handpiece having the function of introducing spray water onto the cutting tool is described in, for example, <CIT>. In the dental handpiece described in this publication, a water spraying tube path is formed in a head portion so as to mix water from a water supply tube path with air from an air supply tube path and eject it from an ejection port toward the cutting tool. The water spraying tube path is formed to orient obliquely downward from a merged portion of the water supply tube and the air supply tube and is configured to introduce spray water from the ejection port opened at a lower surface of a base portion of the head portion.

Since the spray water mixed at the merged portion of the water supply tube path and the air supply tube path is introduced from the ejection port toward the cutting tool in the dental handpiece described in the above publication, the spray water is spread from the ejection port uniformly in the longitudinal direction and lateral direction of the cutting tool. In order to surely hit the spray water on the cutting tool, the spray water is required to be spread in the longitudinal direction (long-side direction) of the cutting tool. On the other hand, when the spray water is spread in the lateral direction (short-side direction) of the cutting tool, a portion of a tooth that is being cut is less likely to be seen at the time of cutting the tooth.

Further technological background can be found in <CIT>. <CIT> discloses a dental handpiece configured to detachably hold a cutting tool, the dental handpiece comprising: a holding portion provided with an insertion port into which the cutting tool is insertable, the holding portion being configured to hold the cutting tool inserted in the insertion port; and a main body portion configured to accommodate the holding portion, the main body portion being provided with a water introduction hole and air holes.

The present invention has been made to solve the above-described problem and has an object to provide a dental handpiece to spread spray water in a longitudinal direction of a cutting tool and suppress the spray water from being spread in a lateral direction of the cutting tool.

A dental handpiece of the present invention is a dental handpiece configured to detachably hold a cutting tool. The dental handpiece includes: a holding portion provided with an insertion port into which the cutting tool is insertable, the holding portion being configured to hold the cutting tool inserted in the insertion port; and a main body portion configured to accommodate the holding portion, the main body portion being provided with a water introduction hole and a plurality of chip air holes. The plurality of chip air holes is disposed to sandwich the water introduction hole in a second direction intersecting a first direction in which the insertion port and the water introduction hole are arranged.

Hereinafter, embodiments of the present invention will be described with reference to figures.

First, a configuration of a dental handpiece according to an embodiment of the present invention will be described.

Referring to <FIG>, a dental handpiece <NUM> is configured to detachably hold a cutting tool <NUM>. The dental handpiece <NUM> is configured to hold the cutting tool <NUM> configured to cut a tooth and rotate the cutting tool <NUM> at high speed. In the present embodiment, the dental handpiece <NUM> is a motor handpiece or motor driven handpiece configured to rotate the cutting tool <NUM> at high speed by a motor. More specifically, the dental handpiece <NUM> is a contra-angle type handpiece. It should be noted that the dental handpiece <NUM> may be an air turbine handpiece configured to rotate the cutting tool <NUM> at high speed by an air turbine.

A driving portion <NUM> is connected to one end side (proximal end side) of the dental handpiece <NUM> in the longitudinal direction thereof. The driving portion <NUM> is attachable to and detachable from the proximal end side of the dental handpiece <NUM>. The driving portion <NUM> includes a motor configured to drive for rotation or to drive a rotational motion. The cutting tool <NUM> is held on the other end side (distal end side) of the dental handpiece <NUM> in the longitudinal direction. The cutting tool <NUM> is configured to be rotated to cut a tooth.

The dental handpiece <NUM> includes a body portion <NUM>, a neck portion <NUM> and a head portion <NUM>. The body portion <NUM>, the neck portion <NUM>, and the head portion <NUM> are arranged in this order from the proximal end side to the distal end side of dental handpiece <NUM> in the longitudinal direction.

Body portion <NUM> is attachable to and detachable from driving portion <NUM>. Body portion <NUM> is disposed on the proximal end side of dental handpiece <NUM>. The diameter of body portion <NUM> is gradually decreased toward the distal end side of dental handpiece <NUM>. Body portion <NUM> includes a housing having a substantially cylindrical shape. Body portion <NUM> is a grip portion to be held by a user, such as a practitioner and a maintenance operator.

When the user holds dental handpiece <NUM> such that cutting tool <NUM> faces downward and head portion <NUM> faces upward with body portion <NUM> being horizontal, neck portion <NUM> is curved upward at the center portion in the longitudinal direction and is gradually decreased in diameter toward the distal end side. Neck portion <NUM> includes a housing having a substantially cylindrical shape.

Head portion <NUM> is connected to body portion <NUM> via neck portion <NUM>. Head portion <NUM> includes a housing having a substantially cylindrical shape and having an axial direction (upward/downward direction in <FIG>) that is substantially orthogonal to the longitudinal direction of neck portion <NUM>.

Referring to <FIG> and <FIG>, dental handpiece <NUM> is configured to rotate cutting tool <NUM> at high speed by increasing the speed of the rotation of the motor of driving portion <NUM> by a rotation transmission mechanism <NUM>. Rotation transmission mechanism <NUM> is accommodated in a housing of each of body portion <NUM>, neck portion <NUM>, and head portion <NUM>.

Rotation transmission mechanism <NUM> includes a first transmission mechanism <NUM>, a second transmission mechanism <NUM>, a third transmission mechanism <NUM>, and a tool rotation mechanism <NUM>. First transmission mechanism <NUM>, second transmission mechanism <NUM>, third transmission mechanism <NUM>, and tool rotation mechanism <NUM> are arranged in this order from the proximal end side to the distal end side of dental handpiece <NUM> in the longitudinal direction.

First transmission mechanism <NUM> is disposed inside the housings of body portion <NUM> and neck portion <NUM>. Second transmission mechanism <NUM> is disposed inside the housing of neck portion <NUM>. Third transmission mechanism <NUM> is disposed inside the housings of neck portion <NUM> and head portion <NUM>. Tool rotation mechanism <NUM> is disposed inside the housing of head portion <NUM>.

First transmission mechanism <NUM> is configured to transmit the rotation of the motor of driving portion <NUM> to the second transmission mechanism. First transmission mechanism <NUM> includes a motor-coupled portion <NUM>, a first rotation shaft <NUM>, two first bearing portions <NUM>, and a drive gear <NUM>. Motor-coupled portion <NUM> is configured to be coupled to a shaft portion of the motor of driving portion <NUM>. Motor-coupled portion <NUM> is connected to the proximal end side of first rotation shaft <NUM>. First rotation shaft <NUM> is a hollow, substantially cylindrical body. First rotation shaft <NUM> is held by two first bearing portions <NUM> so as to be rotatable around a rotation axis extending in the axial direction. Two first bearing portions <NUM> are disposed to be separated from each other in the axial direction of first rotation shaft <NUM>. Each of two first bearing portions <NUM> is a ball bearing. Drive gear <NUM> is connected to the distal end side of first rotation shaft <NUM>. Drive gear <NUM> is an internally-toothed gear or an internal gear or a hub gear.

Second transmission mechanism <NUM> is configured to transmit the rotation of first transmission mechanism <NUM> to third transmission mechanism <NUM>. Second transmission mechanism <NUM> includes a pinion gear <NUM>, a second rotation shaft <NUM>, two second bearing portions <NUM>, and a bevel gear <NUM>. Pinion gear <NUM> is configured to be engaged with drive gear <NUM>. Pinion gear <NUM> is connected to the proximal end side of second rotation shaft <NUM>. Second rotation shaft <NUM> is a solid, substantially cylindrical body. Second rotation shaft <NUM> is held by two second bearing portions <NUM> so as to be rotatable around a rotation axis extending in the axial direction. Two second bearing portions <NUM> are disposed to be separated from each other in the axial direction of second rotation shaft <NUM>. Each of two second bearing portions <NUM> is a ball bearing. Bevel gear <NUM> is connected to the distal end side of second rotation shaft <NUM>. Bevel gear <NUM> is an internally-toothed gear or an internal gear or an hub gear.

Third transmission mechanism <NUM> is configured to transmit the rotation of second transmission mechanism <NUM> to tool rotation mechanism <NUM>. Third transmission mechanism <NUM> includes a middle gear <NUM>, a third rotation shaft <NUM>, two third bearing portions <NUM>, and a front gear <NUM>. Middle gear <NUM> is configured to be engaged with bevel gear <NUM>. Middle gear <NUM> is connected to the proximal end side of third rotation shaft <NUM>. Third rotation shaft <NUM> is a solid, substantially cylindrical body. Third rotation shaft <NUM> is held by two third bearing portions <NUM> so as to be rotatable around a rotation axis extending in the axial direction. Two third bearing portions <NUM> are disposed to be separated from each other in the axial direction of third rotation shaft <NUM>. Each of two third bearing portions <NUM> is a ball bearing. Front gear <NUM> is connected to the distal end side of third rotation shaft <NUM>. Front gear <NUM> is an externally-toothed gear or an internal gear or an hub gear.

Tool rotation mechanism <NUM> is configured to rotate cutting tool <NUM> by transmitting the rotation of third transmission mechanism <NUM> to cutting tool <NUM>. Tool rotation mechanism <NUM> includes a holding portion <NUM> and two head-portion bearing portions <NUM>.

Holding portion <NUM> is held by two head-portion bearing portions <NUM> so as to be rotatable around a rotation axis extending in the axial direction of cutting tool <NUM>. Two head-portion bearing portions <NUM> are disposed to be separated from each other in the axial direction of holding portion <NUM>. Each of two head-portion bearing portions <NUM> is a ball bearing.

Cutting tool <NUM> includes a base stem 3a and a cutting edge portion 3b. Base stem 3a and cutting edge portion 3b are formed in one piece. Base stem 3a and cutting edge portion 3b form a substantially cylindrical shape. Base stem 3a is held by holding portion <NUM> inside head portion <NUM>. Cutting edge portion 3b protrudes from base stem 3a in the axial direction of base stem 3a.

Holding portion <NUM> has a mechanism configured to detachably hold cutting tool <NUM>. Holding portion <NUM> includes a rotation cylinder <NUM>, a chuck <NUM>, an elastic body <NUM>, a slide ring <NUM>, and a ring stopper <NUM>.

Chuck <NUM>, elastic body <NUM>, slide ring <NUM>, and ring stopper <NUM> are inserted in rotation cylinder <NUM>. Chuck <NUM>, elastic body <NUM>, slide ring <NUM>, and ring stopper <NUM> are accommodated in rotation cylinder <NUM> in this order from the cutting edge side toward the cutting root side of cutting tool <NUM>.

Rotation cylinder <NUM> is configured to allow cutting tool <NUM> to be inserted therein. Rotation cylinder <NUM> is a head-side gear formed to have a cylindrical shape. Rotation cylinder <NUM> is a substantially cylindrical body having: an inner diameter that allows for accommodation of chuck <NUM>, elastic body <NUM>, slide ring <NUM>, and ring stopper <NUM>; and an outer diameter that can be fitted to an inner ring of head-portion bearing portion <NUM>.

Rotation cylinder <NUM> can convert the rotation of third transmission mechanism <NUM> around the axis along the longitudinal direction of neck portion <NUM> into the rotation of tool rotation mechanism <NUM> around the axis along the longitudinal direction of cutting tool <NUM>.

Rotation cylinder <NUM> includes a stem main body 53a, which is a substantially cylindrical body, and rotor gear teeth 53b. Rotor gear teeth 53b are a bevel gear. Stem main body 53a is a substantially cylindrical body. Rotor gear teeth 53b protrude radially outward from an outer peripheral surface of stem main body 53a, and, when viewed in a cross-sectional view, a surface thereof on the cutting edge side is inclined downward in a direction toward the radially outward side. The plurality of rotor gear teeth 53b are provided at equal intervals along the outer periphery of stem main body 53a. Rotation cylinder <NUM> provided with the plurality of rotor gear teeth 53b is a bevel gear and is a driven gear engaged with front gear <NUM> of third transmission mechanism <NUM>.

Chuck <NUM> is configured to attach and detach cutting tool <NUM> inserted in rotation cylinder <NUM>. Chuck <NUM> is disposed on the cutting edge side (lower side) with respect to the substantially center of cutting tool <NUM> in the longitudinal direction inside rotation cylinder <NUM>. Chuck <NUM> is configured to hold base stem 3a of cutting tool <NUM> inserted along the longitudinal direction of cutting tool <NUM>.

Elastic body <NUM> is configured to bias chuck <NUM> to engage chuck <NUM> with cutting tool <NUM>. Elastic body <NUM> is a compressive elastic body deformable in a compression direction, and is externally fitted to an upper portion of chuck <NUM> inside rotation cylinder <NUM>.

Slide ring <NUM> is configured to be movable in the axial direction inside rotation cylinder <NUM>. Slide ring <NUM> is accommodated on the cutting root side of cutting tool <NUM> with respect to elastic body <NUM> and is configured to push elastic body <NUM>.

In holding portion <NUM>, elastic body <NUM> before being compressively deformed pushes an end portion of chuck <NUM> on the cutting root side, and chuck <NUM> having been decreased in diameter by the pushing of elastic body <NUM> can hold cutting tool <NUM>. On the other hand, when elastic body <NUM> is compressively deformed, cutting tool <NUM> held by chuck <NUM> can be released.

Ring stopper <NUM> is formed to have a substantially ring shape and is externally fitted to a portion of slide ring <NUM> on the cutting root side. Ring stopper <NUM> can regulate a position of cutting tool <NUM> when cutting tool <NUM> is attached.

Each of two head-portion bearing portions <NUM> is formed to have a substantially ring shape. Two head-portion bearing portions <NUM> rotatably support the cutting edge side end portion and cutting root side end portion of holding portion <NUM> inside head portion <NUM>.

Head portion <NUM> includes a stem portion <NUM>, a housing main body portion <NUM> and a push cap <NUM>. Stem portion <NUM> is connected to the distal end side of neck portion <NUM>. Housing main body portion <NUM> is a hollow, substantially cylindrical body extending along the longitudinal direction of cutting tool <NUM> attached thereto. Tool rotation mechanism <NUM>, which is configured to be driven to rotate cutting tool <NUM> held inside housing main body portion <NUM>, is accommodated therein. The upper and lower ends of housing main body portion <NUM> are opened, and push cap <NUM> is disposed at the upper end portion of housing main body portion <NUM>. Push cap <NUM> is provided for the sake of an operation of attaching and detaching cutting tool <NUM> to and from head portion <NUM>.

Referring to <FIG> and <FIG>, holding portion <NUM> is provided with an insertion port IP into which cutting tool <NUM> can be inserted. Holding portion <NUM> is configured to hold cutting tool <NUM> inserted in insertion port IP. Head portion <NUM> includes a spraying portion <NUM>. Dental handpiece <NUM> includes a main body portion MP. In the present embodiment, stem portion <NUM>, housing main body portion <NUM> and spraying portion <NUM> constitute main body portion MP. Holding portion <NUM> is accommodated in main body portion MP. Main body portion MP is provided with a water introduction hole WH and a plurality of chip air holes CH. In the present embodiment, spraying portion <NUM> is provided with water introduction hole WH and the plurality of chip air holes CH. One-point water introduction is employed with which only one water introduction hole WH is provided.

Spraying portion <NUM> is attached to stem portion <NUM>. Stem portion <NUM> is provided with a water introduction tube path WP and an air supply tube path AP. Water introduction tube path WP communicates with water introduction hole WH. Water introduction tube path WP is configured to supply water to water introduction hole WH. Water introduction tube path WP is connected to a water introduction tube P1. Water introduction tube P1 is connected to a water introduction portion of driving portion <NUM> shown in <FIG>. Air supply tube path AP communicates with the plurality of chip air holes CH. Air supply tube path AP is configured to supply air to the plurality of chip air holes CH. Air supply tube path AP is connected to an air supply tube P2. Air supply tube P2 is connected to an air supply portion of driving portion <NUM> shown in <FIG>.

Referring to <FIG> and <FIG>, water introduction hole WH is disposed to face cutting tool <NUM>. The opening of water introduction hole WH has a circular shape. The opening of each of the plurality of water introduction holes WH may have a perfect circular shape. The opening area of water introduction hole WH is larger than the opening area of each of the plurality of chip air holes CH.

The plurality of chip air holes CH provided in main body portion MP are disposed to sandwich water introduction hole WH in a second direction D2 intersecting a first direction D1 in which insertion port IP and water introduction hole WH are arranged. First direction D1 may be orthogonal to second direction D2. The opening of each of the plurality of chip air holes CH has a circular shape. The opening of each of the plurality of chip air holes CH may have a perfect circular shape. The plurality of chip air holes CH may be formed to have the same shape.

The plurality of chip air holes CH include a first hole CH1, a second hole CH2, a third hole CH3, and a fourth hole CH4. First hole CH1 and second hole CH2 are arranged along first direction D1. Third hole CH3 and fourth hole CH4 are arranged along first direction D1. First hole CH1 and third hole CH3 are arranged with water introduction hole WH being interposed between first hole CH1 and third hole CH3 in second direction D2, and are disposed on one side in first direction D1 with respect to center C of water introduction hole WH in first direction D1. Second hole CH2 and fourth hole CH4 are arranged with water introduction hole WH being interposed between second hole CH2 and fourth hole CH4 in second direction D2, and are disposed on the other side in first direction D1 with respect to center C of water introduction hole WH in first direction D1.

In first direction D1, first hole CH1, third hole CH3, and second hole CH2 and fourth hole CH4 are disposed on the inner side with respect to the diameter of water introduction hole WH. In second direction D2, first hole CH1 faces third hole CH3, and second hole CH2 faces fourth hole CH4.

Each of first hole CH1 and third hole CH3 is inclined toward water introduction hole WH. The inclination angle of each of first hole CH1 and third hole CH3 is, for example, <NUM>°. Each of second hole CH2 and fourth hole CH4 is inclined toward water introduction hole WH. The inclination angle of each of second hole CH2 and fourth hole CH4 is, for example, <NUM>°.

The size of the opening of water introduction hole WH in first direction D1 is larger than the size of the opening of water introduction hole WH in second direction D2. The opening of water introduction hole WH has a long-side direction in first direction D1 and a short-side direction in second direction D2. Water introduction hole WH is provided with a tapered portion having an opening area that is increased toward the opening thereof in first direction D1. The tapered portion is formed to have a crescent shape when viewed in a plan view.

Next, an operation of supplying spray water SW of dental handpiece <NUM> according to the embodiment will be described.

As shown in <FIG> and <FIG>, water supplied from water introduction tube path WP to water introduction hole WH is introduced from water introduction hole WH. Air supplied from air supply tube path AP to the plurality of chip air holes CH is ejected from the plurality of chip air holes CH so as to hit the air onto the water introduced from water introduction hole WH. Thus, spray water is formed. The spray water is ejected toward cutting tool <NUM>. Particularly, the spray water is ejected toward cutting edge portion 3b of cutting tool <NUM>.

As shown in <FIG> and <FIG>, by the air ejected from the plurality of chip air holes CH, spray water SW formed by the air and the water introduced from water introduction hole WH is suppressed from being spread in second direction D2. Specifically, with first hole CH1 and second hole CH2, spray water SW is suppressed from being spread to one side in second direction D2, whereas with third hole CH3 and fourth hole CH4, spray water SW is suppressed from being spread to the other side in second direction D2. The air is ejected from each of the plurality of chip air holes CH with substantially the same pressure.

As shown in <FIG> and <FIG>, spray water SW is spread in a longitudinal direction D3 by the air ejected from the plurality of chip air holes CH. In this way, spray water SW is spread in longitudinal direction D3 and is suppressed from being spread in second direction (lateral direction) D2.

Next, modifications of dental handpiece <NUM> according to the embodiment will be described with reference to <FIG> and <FIG>.

As shown in <FIG>, in a modification <NUM> of dental handpiece <NUM> according to the embodiment, the configuration of the plurality of chip air holes CH is different from the configuration described above. In modification <NUM> of dental handpiece <NUM> according to the embodiment, the configuration of chip air hole CH is different from the configuration described above. The plurality of chip air holes CH include a first hole CH1 and a second hole CH2. First hole CH1 is an elongated hole having a long-side direction in first direction D1. Second hole CH2 is an elongated hole having a long-side direction in first direction D1. First hole CH1 and second hole CH2 are arranged with water introduction hole WH being interposed between first hole CH1 and second hole CH2 in second direction D2.

As shown in <FIG>, in a modification <NUM> of dental handpiece <NUM> according to the embodiment, the configuration of the plurality of chip air holes CH is different from the configuration described above. The plurality of chip air holes CH include a first hole CH1, a second hole CH2, a third hole CH3, a fourth hole CH4, a fifth hole CH5, and a sixth hole CH6. First hole CH1, second hole CH2, and fifth hole CH5 are arranged along first direction D1. Third hole CH3, fourth hole CH4, and sixth hole CH6 are arranged along first direction D1. First hole CH1 and second hole CH2 are arranged with fifth hole CH5 being interposed between first hole CH1 and second hole CH2 in first direction D1. Third hole CH3 and fourth hole CH4 are arranged with sixth hole CH6 being interposed between third hole CH3 and fourth hole CH4 in first direction D1.

Next, functions and effects of dental handpiece <NUM> according to the embodiment will be described.

According to dental handpiece <NUM> of the embodiment, the plurality of chip air holes CH provided in main body portion MP are disposed to sandwich water introduction hole WH in second direction D2 intersecting first direction D1 in which insertion port IP and water introduction hole WH are arranged. Thus, spray water SW is spread in longitudinal direction D3 by the air ejected from the plurality of chip air holes CH, with the result that spray water SW can be spread in longitudinal direction D3. Further, by the air ejected from the plurality of chip air holes CH, spray water SW can be suppressed from being spread in second direction D2. Therefore, spray water SW can be spread in longitudinal direction D3, and spray water SW can be suppressed from being spread in second direction (lateral direction) D2.

In dental handpiece <NUM> according to the embodiment, so-called one-point water introduction is employed with which only one water introduction hole WH is provided. In the one-point water introduction, water introduction tube path WP and air supply tube path AP can be shorter than those in multi-point water introduction with which a plurality of water introduction holes WH are provided. Therefore, a space on the front side of head portion <NUM> can be made small. Therefore, in dental handpiece <NUM> according to the embodiment, the size of head portion <NUM> in longitudinal direction D3 can be reduced. That is, the height of head portion <NUM> can be reduced.

Further, in the case where the merged portion at which the water supply tube path and the air supply tube path are merged is provided inside head portion <NUM> as in PTL <NUM>, the height of head portion <NUM> is increased by the height of the water spray tube path from the merged portion to the ejection port of the lower surface of head portion <NUM>. In dental handpiece <NUM> according to the embodiment, water introduced from water introduction hole WH and air introduced from the plurality of chip air holes CH hit each other outside dental handpiece <NUM>, thereby forming spray water SW. Therefore, the height of head portion <NUM> can be made low.

According to dental handpiece <NUM> of the embodiment, first hole CH1 and third hole CH3 are arranged with water introduction hole WH being interposed between first hole CH1 and third hole CH3 in second direction D2, and are disposed on one side in first direction D1 with respect to center C of water introduction hole WH in first direction D1. Second hole CH2 and fourth hole CH4 are arranged with water introduction hole WH being interposed between second hole CH2 and fourth hole CH4 in second direction D2, and are disposed on the other side in first direction D1 with respect to center C of water introduction hole WH in first direction D1. Therefore, spray water SW can be suppressed from being divided in first direction D1 by the air ejected from first hole CH1, third hole CH3, second hole CH2 and fourth hole CH4. Therefore, spray water SW can be continuously ejected in first direction D1.

According to dental handpiece <NUM> of the embodiment, each of first hole CH1 and third hole CH3 is inclined toward water introduction hole WH, and each of second hole CH2 and fourth hole CH4 is inclined toward water introduction hole WH. Therefore, the air ejected from first hole CH1, third hole CH3, second hole CH2 and fourth hole CH4 can hit the water introduced from the water introduction hole WH. Thus, the spray water can be formed.

According to dental handpiece <NUM> of the embodiment, the size of the opening of water introduction hole WH in first direction D1 is larger than the size of the opening of water introduction hole WH in second direction D2. Therefore, spray water SW can be made longer in first direction D1 than in second direction D2. Therefore, spray water SW can be elongated in the longitudinal direction. Hence, spray water SW can be long in longitudinal direction D3. Thus, even when cutting tool <NUM> is long, spray water SW can be surely ejected to cutting tool <NUM>.

Claim 1:
A dental handpiece (<NUM>) configured to detachably hold a cutting tool (<NUM>), the dental handpiece (<NUM>) comprising:
a holding portion (<NUM>) provided with an insertion port (IP) into which the cutting tool (<NUM>) is insertable, the holding portion (<NUM>) being configured to hold the cutting tool (<NUM>) inserted in the insertion port (IP); and
a main body portion (MP) configured to accommodate the holding portion (<NUM>), the main body portion (MP) being provided with a water introduction hole (WH) and a plurality of chip air holes (CH), wherein
the plurality of chip air holes (CH) provided in the main body portion (MP) is disposed to sandwich the water introduction hole (WH) in a second direction (D2) intersecting a first direction (D1) in which the insertion port (IP) and the water introduction hole (WH) are arranged.