JP7746403B2 - Holder, cutting tool, and method for manufacturing machined product - Google Patents

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No. 2021-187861, filed November 18, 2021, the entire disclosure of which is incorporated herein by reference.

This disclosure relates to a holder for a cutting tool. The cutting tool can be used when cutting a workpiece such as a metal.

Cutting tools used when cutting workpieces such as metals include those described in International Publication No. 2019/220528 (Patent Document 1) and JP-A-2020-518477 (Patent Document 2).

The cutting tool described in Patent Document 1 has a coolant supply passage that has a discharge passage and a coolant reservoir. The discharge passage is a hole that opens to the chip pocket and includes a coolant outlet. The coolant reservoir is a hole that is located further inside than the discharge passage and has a larger inner diameter than the discharge passage.

The cutting tool described in Patent Document 2 has a supply hole and a longitudinal opening. The supply hole is a hole formed by the tool head and disk, and is a portion for supplying coolant to the cutting element. The longitudinal opening, like the supply hole, is a hole formed by the tool head and disk, and extends from the supply hole to the groove (chip pocket).

The cutting tools described in Patent Documents 1 and 2 both have flow channels for supplying coolant toward chip pockets, but these flow channels are composed only of hole-shaped portions. As a result, there is a risk that the outlet of the flow channel may be temporarily blocked by chips generated during cutting of the workpiece. Furthermore, because coolant is generally subjected to high flow pressure, there is a risk that the flow channel may be damaged if the outlet of the flow channel is temporarily blocked.

The non-limiting one-sided holder disclosed herein comprises a cylindrical body extending along a rotation axis from a first end to a second end, an insert pocket located on the first end side of the body and capable of receiving a cutting insert, a chip pocket located forward of the insert pocket in the rotation direction of the rotation axis, a linear coolant hole located inside the body and opening toward the chip pocket, and a first groove opening toward the first end and extending along the central axis of the coolant hole from the opening of the coolant hole toward the chip pocket.

FIG. 1 is a perspective view of a non-limiting one-sided holder of the present disclosure. FIG. 2 is a perspective view of the holder shown in FIG. 1 as viewed from another direction. FIG. 2 is a plan view of the holder shown in FIG. 1 as viewed from the first end side. 4 is a side view of the holder shown in FIG. 3 as viewed from the A1 direction. FIG. 4 is a side view of the holder shown in FIG. 3 as viewed from the A2 direction. FIG. 1 is a perspective view of a non-limiting one-sided cutting tool of the present disclosure. FIG. 7 is a perspective view of the cutting tool shown in FIG. 6, viewed from another direction. FIG. 8 is an enlarged view of an area B1 shown in FIG. 7. FIG. 7 is a plan view of the cutting tool shown in FIG. 6 as viewed from the first end side. FIG. 10 is a side view of the cutting tool shown in FIG. 9 as viewed from the A3 direction. FIG. 10 is a side view of the cutting tool shown in FIG. 9 as viewed from the A4 direction. FIG. 10 is the same plan view as that of FIG. 9, showing the coolant holes in a transparent view. FIG. 13 is an enlarged view of an area B2 shown in FIG. 12 . FIG. 13 is a cross-sectional view of the cutting tool shown in FIG. 12 taken along line XIV. FIG. 15 is an enlarged view of an area B3 shown in FIG. 14. FIG. 7 is an enlarged view of the cutting tool shown in FIG. 6 as viewed along the central axis of a coolant hole. 1 is a schematic diagram showing a step in a non-limiting method of manufacturing a one-sided machined product according to the present disclosure. 1 is a schematic diagram showing a step in a non-limiting method of manufacturing a one-sided machined product according to the present disclosure. 1 is a schematic diagram showing a step in a non-limiting method of manufacturing a one-sided machined product according to the present disclosure.

<Holder>
The following describes in detail a non-limiting example of a holder 1 according to the present disclosure with reference to the drawings. However, for the sake of convenience, the drawings shown below show only the main components necessary for explaining the embodiment in a simplified form. Therefore, the holder 1 may include optional components not shown in the drawings. Furthermore, the dimensions of the components in the drawings do not faithfully represent the actual dimensions of the components or the dimensional ratios of the components.

The holder 1 may have a main body 3, an insert pocket 5, a chip pocket 7, a coolant hole 9 and a first groove 11, as a non-limiting example shown in Figures 1 to 16.

The main body 3 may be cylindrical. A cylindrical shape may be roughly cylindrical, and does not necessarily have to be cylindrical in the strict sense. Furthermore, the main body 3 may extend along the rotation axis O1 from the first end 3a to the second end 3b. Generally, the first end 3a is referred to as the "front end" and the second end 3b is referred to as the "rear end." The main body 3 is rotatable around the rotation axis O1. Note that the arrow Y1 in Figure 1 and other figures may indicate the direction of rotation of the rotation axis O1, or may indicate the direction of rotation of the main body 3 around the rotation axis O1.

The main body 3 is not limited to a specific size. For example, the length of the main body 3 in the direction along the rotation axis O1 may be set to approximately 40 to 100 mm. Furthermore, the width (diameter) of the main body 3 in the direction perpendicular to the rotation axis O1 may be set to approximately 60 to 350 mm.

Materials for the main body 3 may include, for example, steel and cast iron. If the main body 3 is made of steel, the main body 3 has high toughness.

The insert pocket 5 may be located on the first end 3a side of the main body 3 and may be capable of receiving a cutting insert. The insert pocket 5 may be open on the outer peripheral surface of the main body 3 and on the end face on the first end 3a side. There may be only one insert pocket 5, or there may be multiple insert pockets 5.

When the holder 1 has multiple insert pockets 5, these insert pockets 5 may be positioned at equal intervals around the rotation axis O1, or may be positioned at uneven intervals. When there are multiple insert pockets 5, the number of insert pockets 5 may be 2 to 20.

The chip pocket 7 may be located forward of the insert pocket 5 in the rotational direction Y1 of the rotation axis O1. Similarly to the insert pocket 5, the chip pocket 7 may open on the outer peripheral surface of the main body 3 and on the end face on the side of the first end 3a. The number of chip pockets 7 may be the same as the number of insert pockets 5. The chip pocket 7 may be used as a space for the flow of chips generated during cutting of the workpiece.

The coolant hole 9 may be linear, as shown in Figures 13 and 14 as a non-limiting example. The coolant hole 9 may also be located inside the main body 3 and open toward the chip pocket 7. In other words, the coolant hole 9 may be located inside the main body 3 and have an opening 13 that opens toward the chip pocket 7.

Coolant (cooling fluid) supplied from the outside can flow inside the coolant hole 9. The opening 13 of the coolant hole 9 can also function as an outlet for discharging the coolant. Therefore, if the holder 1 has a coolant hole 9, coolant can be flowed toward the chip pocket 7 through the coolant hole 9 and then discharged from the opening 13 toward the chip pocket 7.

The coolant hole 9 may also open on the opposite side of the chip pocket 7, as shown in Figure 14 as a non-limiting example. In other words, the coolant hole 9 may further have an opening 15 that opens on the opposite side of the chip pocket 7. This opening 15 can function as an inlet for allowing coolant to flow into the interior of the coolant hole 9.

The position of the opening 15 is not particularly limited. For example, if the main body 3 has a through hole 17 that opens at the end face on the first end 3a side and the end face on the second end 3b side, the opening 15 may be located on the inner circumferential surface of the through hole 17. That is, the coolant hole 9 may open at the inner circumferential surface of the through hole 17. The axis passing through the center of the end face on the first end 3a side and the center of the end face on the second end 3b side of the main body 3 may be the central axis of the through hole 17. The central axis of the through hole 17 may coincide with the rotation axis O1. An arbor can be attached to the through hole 17. During cutting of the workpiece, the opening of the through hole 17 at the end face on the second end 3b side may be blocked to prevent coolant leakage.

If the coolant hole 9 has an opening 15 in addition to the opening 13, the opening 13 may be referred to as the first opening 13, and the opening 15 as the second opening 15. The number of coolant holes 9 may be the same as the number of chip pockets 7. The inner diameter W1 of the coolant hole 9 may be set to approximately 2 to 4 mm. The cross section of the coolant hole 9 perpendicular to the central axis O2 of the coolant hole 9 may be circular. The cross-sectional shape of the coolant hole 9 is not limited to a circular shape.

Examples of coolants include water-insoluble and water-soluble oils. Water-insoluble oils include cutting oils such as oil-based, inert extreme pressure, and active extreme pressure types. Water-soluble oils include cutting oils such as emulsions, solubles, and solutions. Coolants are not limited to liquids and may be gases such as inert gases. Coolants may be selected appropriately depending on the material of the workpiece.

The first groove 11 may open toward the first end 3a and extend along the central axis O2 of the coolant hole 9 from the opening 13 of the coolant hole 9 toward the chip pocket 7, as shown in a non-limiting example in Figure 13.

When the holder 1 has a first groove 11 extending from the opening 13 of the coolant hole 9 toward the chip pocket 7 along the central axis O2 of the coolant hole 9, the first groove 11 is located between the coolant hole 9 and the chip pocket 7, so the opening 13 of the coolant hole 9 is less likely to be blocked by chips.

Furthermore, because the first groove 11 opens not only toward the chip pocket 7 but also toward the first end 3a, the opening 19 in the first groove 11 can have a first portion 19a that opens toward the chip pocket 7 and a second portion 19b that is located closer to the opening 13 of the coolant hole 9 than the first portion 19a and opens toward the first end 3a. Therefore, even if the opening 19 (first portion 19a) on the chip pocket 7 side of the first groove 11 is blocked by chips, coolant can easily be discharged from the opening 19 (second portion 19b) on the first end 3a side of the first groove 11.

Furthermore, because the first groove 11 extends along the central axis O2 of the coolant hole 9, the flow of coolant discharged from the opening 13 of the coolant hole 9 is less likely to be obstructed by the first groove 11. Therefore, the holder 1 makes it easier for the coolant to be discharged.

The second portion 19b of the opening 19 of the first groove 11 may be connected to the first portion 19a of the opening 19. The second portion 19b may also be inclined relative to the first portion 19a.

An imaginary line extending from the central axis O2 toward the outer periphery of the main body 3 may be the first imaginary line L1. The first imaginary line L1 may intersect with the insert pocket 5 when viewed from the front in the rotational direction Y1, as in the non-limiting example shown in Figure 15, and may be located further forward in the rotational direction Y1 than the insert pocket 5 when viewed from the front from the first end 3a, as in the non-limiting example shown in Figure 13. For ease of visual understanding, in the non-limiting example shown in Figure 15, the portion where the first imaginary line L1 intersects with the insert pocket 5 is surrounded by a dashed line L1a.

When the insert pocket 5 is viewed from the front in the rotational direction Y1, if the first imaginary line L1 intersects with the insert pocket 5, the cutting insert's cutting face is likely to be cooled by the coolant. Furthermore, when the insert pocket 5 is viewed from the front from the first end 3a side, if the first imaginary line L1 is located further forward in the rotational direction Y1 than the insert pocket 5, the coolant is likely to discharge chips from the chip pocket 7.

The cross-sectional area of the first groove 11 in a cross section perpendicular to the central axis O2 may be the same as or different from the cross-sectional area of the coolant hole 9 in a cross section perpendicular to the central axis O2. For example, the cross-sectional area of the first groove 11 may be larger than the cross-sectional area of the coolant hole 9. In this case, chips are less likely to clog the first groove 11, allowing for better coolant discharge.

The cross-sectional area of the coolant hole 9 may be constant. The cross-sectional area of the first groove 11 may be evaluated as the maximum value of the cross-sectional area of the first groove 11. The cross section of the first groove 11 including the second portion 19b may have the maximum value of the cross-sectional area of the first groove 11.

If it is difficult to compare the cross-sectional area of the first groove 11 with the cross-sectional area of the coolant hole 9, the above-mentioned configuration may be evaluated by comparing their areas when viewed in a plan view instead of comparing their cross-sectional areas. For example, as shown in the non-limiting example of FIG. 8, the area of the first groove 11 when viewed in a plan view may be replaced with the cross-sectional area of the first groove 11. Similarly, the area of the opening 13 of the coolant hole 9 when viewed in a plan view may be replaced with the cross-sectional area of the coolant hole 9. Note that, for ease of visual understanding, in the non-limiting example of FIG. 8, the opening 13 of the coolant hole 9 and the first groove 11 are hatched differently to evaluate the areas of the first groove 11 and the opening 13.

The width W2 of the first groove 11 may be the same as or different from the inner diameter W1 of the coolant hole 9. For example, as shown in a non-limiting example in Figure 13, the width W2 of the first groove 11 may be larger than the inner diameter W1 of the coolant hole 9. In this case, chips are less likely to clog the first groove 11, allowing for smooth coolant discharge.

The inner diameter W1 may be constant. The width W2 may refer to the dimension of the first groove 11 in a direction perpendicular to the central axis O2 when the first groove 11 is viewed from the front from the first end 3a side. The width W2 may also be evaluated as the maximum value of the width W2. The second portion 19b of the first groove 11 may have the maximum value of the width W2.

The depth D1 of the first groove 11 may be the same as or different from the inner diameter W1 of the coolant hole 9. For example, as shown in a non-limiting example in Figure 15, the depth D1 of the first groove 11 may be greater than the inner diameter W1 of the coolant hole 9. In this case, chips are less likely to clog the first groove 11, allowing for smooth coolant discharge.

Note that depth D1 may refer to the dimension of the first groove 11 in a direction perpendicular to the central axis O2 in a cross section of the first groove 11 along the rotation axis O1. Depth D1 may also be evaluated as the maximum value of depth D1. The portion of the first groove 11 that includes the second portion 19b may have the maximum value of depth D1.

As shown in Figures 4 and 5 as a non-limiting example, the insert pocket 5 may have a flat seating surface 21 facing forward in the rotational direction Y1. The seating surface 21 is capable of abutting (contacting) the cutting insert when the cutting insert is attached to the holder 1. Note that "flat" does not necessarily mean flat in the strict sense. The seating surface 21 only needs to be roughly flat, and may be slightly curved or have slight irregularities that are not noticeable when the holder 1 is viewed as a whole. For example, the seating surface 21 may have slight irregularities of about several tens of microns.

The radial rake θ1 of the bearing surface 21 may be the same as or different from the radial rake θ2 of the central axis O2. For example, as shown in a non-limiting example in Figure 12, the radial rake θ1 of the bearing surface 21 may be smaller than the radial rake θ2 of the central axis O2. In this case, the coolant will more easily expel chips from the chip pocket 7.

Radial rake may refer to the angle of inclination relative to the radial direction of the rotation axis O1 when viewed from the front from the first end 3a side. For example, as shown in a non-limiting example in Figure 12, the radial rake θ1 of point 21A on the bearing surface 21 may refer to the angle between an imaginary line passing through the rotation axis O1 and point 21A and a tangent to the bearing surface 21 at point 21A. Furthermore, the radial rake θ2 of point O2A on the central axis O2 may refer to the angle between an imaginary line passing through the rotation axis O1 and point O2A and the central axis O2.

The radial rake θ1 of the bearing surface 21 and the radial rake θ2 of the central axis O2 are not limited to specific values. For example, the radial rake θ1 may be set to approximately -20 to 0°. The radial rake θ2 may be set to approximately -30 to 0°. The magnitude relationship between the radial rake θ1 and the radial rake θ2 may be evaluated in terms of absolute values. For example, if the radial rake θ1 is -10° and the radial rake θ2 is -20°, the absolute values can be compared to determine that the radial rake θ1 is smaller than the radial rake θ2.

The holder 1 may further have a second groove 23, as shown in a non-limiting example in Figure 13. The second groove 23 may be located between the first groove 11 and the chip pocket 7 and extend along the central axis O2. If the holder 1 does not have the second groove 23, the intersection ridge between the first groove 11 and the chip pocket 7 is likely to be sharp, and there is a risk of chips becoming caught. However, if the holder 1 has the second groove 23 configured as described above, chips can be prevented from becoming caught.

The width W3 of the second groove 23 may be the same as the width W2 of the first groove 11, or may be different. For example, as shown in a non-limiting example in Figure 13, the width W3 of the second groove 23 may be greater than the width W2 of the first groove 11. In this case, chip entrapment can be suppressed.

Note that width W3 may be defined in the same way as width W2. Width W3 may also be evaluated as the maximum value of width W3. The center of second groove 23 in the direction along central axis O2 may have the maximum value of width W3.

The second groove 23 may be separated from the insert pocket 5 or may be connected to the insert pocket 5. For example, as in the non-limiting example shown in Figure 13, when the second groove 23 is connected to the insert pocket 5, the durability of the constraint surface 25 in the insert pocket 5 is improved. The insert pocket 5 may also have a constraint surface 25. The constraint surface 25 can function as a surface that constraints the cutting insert. The constraint surface 25 may be located forward of the seat surface 21 in the rotational direction Y1.

The second groove 23 may be connected to the chip pocket 7. The second groove 23 may also be connected to the first groove 11. The opening 19 (first portion 19a) of the first groove 11 on the chip pocket 7 side may be connected to the second groove 23.

<Cutting tools>
Next, a non-limiting one-sided cutting tool 101 of the present disclosure will be described with reference to FIGS. 6 to 16. FIG.

The cutting tool 101 may have a holder 1 and a cutting insert 103, as shown in the non-limiting example in Figures 6 to 16. The cutting insert 103 may be located in the insert pocket 5 of the holder 1 and have a cutting edge 105. The cutting insert 103 can be used to cut a workpiece in a cutting process. Note that the cutting insert 103 may also be simply referred to as the insert 103.

When the cutting tool 101 has a holder 1, the coolant is easily discharged, enabling excellent cutting performance. Furthermore, the cutting tool 101 can perform cutting by bringing the cutting edge 105 of the insert 103 into contact with the workpiece.

As shown in a non-limiting example in Figure 15, the first virtual straight line L1 may intersect with the cutting edge 105 when the insert pocket 5 is viewed from the front in the rotational direction Y1. In this case, the cutting edge 105 can be effectively cooled.

In addition, if the cutting edge 105 has a main cutting edge 107 described below, the first virtual straight line L1 may intersect with the main cutting edge 107 when viewing the insert pocket 5 from the front in the rotational direction Y1.

The cutting edge 105 may have a major cutting edge 107. The major cutting edge 107 may have a linear shape that approaches the first end 3a as it approaches the rotation axis O1. The major cutting edge 107 may play a primary role in cutting the workpiece.

As shown in a non-limiting example in Figure 15, when the insert pocket 5 is viewed from the front in the rotational direction Y1, at least a portion of the first groove 11 may be located closer to the first end 3a than the region S1 formed by extending the main cutting edge 107 in a direction perpendicular to the main cutting edge 107. To facilitate visual understanding, in the non-limiting example shown in Figure 15, the region S1 is hatched. Furthermore, the portion of the first groove 11 that is located closer to the first end 3a than the region S1 is surrounded by a dashed line 11a.

When the insert pocket 5 is viewed from the front in the rotational direction Y1, if at least a portion of the first groove 11 (the portion surrounded by the dashed line 11a) is located closer to the first end 3a than the region S1, the discharge of coolant is less likely to be obstructed by chips, and coolant can be supplied closer to the cutting point.

The cutting tool 101 may be used for milling. The insert 103 may be located within the insert pocket 5. The insert 103 may be attached to the insert pocket 5 so that at least a portion of the cutting edge 105 protrudes from the holder 1. If the holder 1 has multiple insert pockets 5, the cutting tool 101 may have multiple inserts 103, and one insert 103 may be located in each insert pocket 5.

The insert 103 may be polygonal plate-shaped. The insert 103 may also have a through hole 109, as shown in a non-limiting example in Figures 10 and 11. The cutting tool 101 may have a fixing member 111. The fixing member 111 may be a member for fixing the insert 103 to the holder 1. The fixing member 111 may be a screw, as shown in a non-limiting example in Figures 10 and 11. The fixing member 111 is not limited to a screw, and may be, for example, a clamp member.

As a non-limiting example shown in Figure 15, the main cutting edge 107 may form one side of the upper surface (rake face) of the insert 103, which has a polygonal plate shape. In this case, the length of one side of the upper surface of the insert 103 may correspond to the length of the main cutting edge 107.

As a non-limiting example shown in Figures 4 and 5, the holder 1 may have a screw hole 27 at a position corresponding to the through hole 109 in the insert pocket 5. The screw hole 27 may open to the seat surface 21. The insert 103 can be fixed to the holder 1 by inserting a screw, which is a fixing member 111, into the through hole 109 of the insert 103 and fixing this screw to the screw hole 27 of the holder 1.

The insert 103 may be made of, for example, cemented carbide or cermet. The cemented carbide may have a composition such as WC-Co, WC-TiC-Co, or WC-TiC-TaC-Co. Here, WC, TiC, and TaC may be hard particles, and Co may be a binder phase.

The cermet may also be a sintered composite material in which a ceramic component is combined with a metal. An example of a cermet is a titanium compound primarily composed of titanium carbide (TiC) or titanium nitride (TiN). It goes without saying that the material of the insert 103 is not limited to the above composition.

The surface of the insert 103 may be coated with a coating using a chemical vapor deposition (CVD) method or a physical vapor deposition (PVD) method, and the coating composition may include, for example, titanium carbide (TiC), titanium nitride (TiN), titanium carbonitride (TiCN), and _alumina ( _Al2O3 ).

When the insert 103 has a polygonal plate shape, the width W2 and/or depth D1 of the first groove 11 described above in the holder 1 may be smaller than the length of the main cutting edge 107 (the length of one side of the top surface of the insert 103). In this case, chips generated by the main cutting edge 107 are less likely to enter the first groove 11. In particular, when the width W2 and/or depth D1 of the first groove 11 is less than half the length of the main cutting edge 107 (the length of one side of the top surface of the insert 103), chips can be prevented from entering the first groove 11 for a variety of cutting depths.

<Method of manufacturing machined product>
Next, a non-limiting method for manufacturing the one-surface machined product 201 according to the present disclosure will be described with reference to FIGS. 17 to 19. FIG.

The machined product 201 may be produced by cutting a workpiece 203. A manufacturing method for the machined product 201 may include the following steps:
(1) rotating the cutting tool 101, which is typified by the non-limiting embodiment described above, along the rotation axis O1 of the holder 1;
(2) bringing the cutting edge 105 of the insert 103 into contact with the workpiece 203;
(3) separating the cutting tool 101 from the workpiece 203;
may have

Specifically, as shown in a non-limiting example in Figure 17, the cutting tool 101 may first be rotated in the Y1 direction along the rotation axis O1 while being moved in the Y2 direction, bringing it relatively closer to the workpiece 203. Next, as shown in a non-limiting example in Figure 18, the cutting edge 105 of the insert 103 may be brought into contact with the workpiece 203 to cut it. Then, as shown in a non-limiting example in Figure 19, the cutting tool 101 may be moved relatively farther away from the workpiece 203.

By going through the above steps, it is possible to obtain a machined product 201 with a highly accurate finished surface. Specifically, when a cutting tool 101 with a holder 1 is used in the manufacturing method of the machined product 201, the coolant is easily discharged, enabling excellent machinability to be achieved. As a result, it is possible to obtain a machined product 201 with a highly accurate finished surface.

In the non-limiting example shown in Figures 17 to 19, the workpiece 203 is fixed and the cutting tool 101 is moved in each process, but of course this is not limited to this form.

For example, in step (1), the workpiece 203 may be brought closer to the cutting tool 101. Similarly, in step (3), the workpiece 203 may be moved away from the cutting tool 101. If the cutting process is to be continued, the cutting tool 101 may be kept rotating, and the process of bringing the cutting edge 105 of the insert 103 into contact with different locations on the workpiece 203 may be repeated.

Examples of materials for the workpiece 203 include carbon steel, alloy steel, stainless steel, cast iron, and non-ferrous metals.

REFERENCE SIGNS LIST 1: Holder 3: Main body 3a: First end 3b: Second end 5: Insert pocket 7: Chip pocket 9: Coolant hole 11: First groove 13: Opening (first opening)
15...Opening (second opening)
17...Through hole 19...Opening 19a...First portion 19b...Second portion 21...Seat surface 23...Second groove 25...Restraint surface 27...Screw hole 101...Cutting tool 103...Cutting insert (insert)
105: Cutting edge 107: Main cutting edge 109: Through hole 111: Fixing member (screw)
201... Cutting workpiece 203... Workpiece O1... Rotation axis O2... Center axis Y1... Rotation direction L1... First virtual straight line S1... Area

Claims (12)

a cylindrical body extending from a first end to a second end along a rotation axis;
an insert pocket located on the first end side of the body and capable of receiving a cutting insert;
a chip pocket located forward of the insert pocket in the rotation direction of the rotary shaft;
a linear coolant hole located inside the body and opening toward the chip pocket;
a first groove that opens toward the first end and extends from the opening of the coolant hole toward the chip pocket along a central axis of the coolant hole ,
a cross-sectional area of the first groove in a cross section perpendicular to the central axis is larger than a cross-sectional area of the coolant hole in a cross section perpendicular to the central axis,
A holder , wherein the width of the first groove is greater than the inner diameter of the coolant hole . a first imaginary line extending from the central axis toward the outer periphery of the main body;
The first virtual straight line is
When the insert pocket is viewed from the front in the rotation direction, the insert pocket intersects with the insert pocket, and
The holder according to claim 1 , wherein the holder is located forward of the insert pocket in the rotation direction when the insert pocket is viewed from the front from the first end side. A holder as described in claim 1 or 2, wherein the depth of the first groove is greater than the inner diameter of the coolant hole. The insert pocket has a flat seat surface facing forward in the rotation direction,
3. The holder according to claim 1, wherein the radial rake of the bearing surface is smaller than the radial rake of the central shaft. The holder according to claim 1 or 2, further comprising a second groove located between the first groove and the chip pocket and extending along the central axis. The holder according to claim 5 , wherein the width of the second groove is greater than the width of the first groove. The holder according to claim 5 , wherein the second groove is connected to the insert pocket. The holder according to claim 1 or 2;
a cutting insert located in the insert pocket of the holder and having a cutting edge. a first imaginary line extending from the central axis toward the outer periphery of the main body;
The cutting tool according to claim 8 , wherein the first imaginary line intersects with the cutting edge when the insert pocket is viewed from the front in the rotation direction. a cylindrical body extending from a first end to a second end along a rotation axis;
an insert pocket located on the first end side of the body and capable of receiving a cutting insert;
a chip pocket located forward of the insert pocket in the rotation direction of the rotary shaft;
a linear coolant hole located inside the body and opening toward the chip pocket;
a holder having a first groove that opens toward the first end and extends from the opening of the coolant hole toward the chip pocket along a central axis of the coolant hole;
a cutting insert located in the insert pocket of the holder and having a cutting edge,
The cutting edge has a linear main cutting edge that approaches the first end as it approaches the rotation axis,
A cutting tool wherein at least a portion of the first groove is located closer to the first end than the area where the main cutting edge is extended in a direction perpendicular to the main cutting edge when the insert pocket is viewed from the front in the rotational direction . rotating the cutting tool according to claim 8 along the rotation axis of the holder;
bringing the cutting edge of the cutting insert into contact with a workpiece;
and removing the cutting tool from the workpiece. rotating the cutting tool of claim 10 along the rotation axis of the holder;
bringing the cutting edge of the cutting insert into contact with a workpiece;
and removing the cutting tool from the workpiece.