Patent Description:
<CIT> (PTL <NUM>) and <CIT> (PTL <NUM>) disclose a cutting tool having a shim disposed between a cutting insert and a holder. The shim has a jetting port for supplying coolant to the cutting edge of the cutting insert.

If a cutting tool shim has a coolant jetting port, the coolant jetting direction can be adjusted by replacing the shim. For each of a plurality of cutting inserts having differently shaped cutting edges, its corresponding shim can be used, with the holder being common. Further, if a shim has a coolant jetting port, the jetting port can be brought closer to the cutting edge. This allows accurate supply of coolant to the cutting edge. <CIT> relates to a metal cutting system for effective coolant delivery.

A cutting tool according to one aspect of the present invention is according to claim <NUM>. A cutting tool according to another aspect of the present invention is according to claim <NUM>.

When a jetting port provided in a shim is bought close to a cutting edge, coolant is accurately supplied to the cutting edge but cannot diffuse so widely. Accordingly, the coolant is locally jetted to the cutting edge. In other words, some parts of the cutting edge are not supplied with sufficient coolant. Local wear progresses at the parts of the cutting edge that are not supplied with sufficient coolant. In particular, at a portion around the boundary between an arc-shaped portion of the cutting edge and a linear portion continuous with the arc-shaped portion, flank face wear called boundary wear occurs. In the cutting tools disclosed in <CIT> and <CIT>, the portion around the boundary cannot be supplied with sufficient coolant. Therefore, it is difficult to reduce boundary wear.

An object of one aspect of the present invention, which has been made in view of the above problem, is to provide a cutting tool shim and a cutting tool that can reduce boundary wear.

One aspect of the present invention can provide a cutting tool shim and a cutting tool that can reduce boundary wear.

First, the summary of embodiments of the present invention is described.

The details of embodiments of the present invention are hereinafter described with reference to the drawings. In the drawings, identical or corresponding parts are identically denoted, and the description thereof is not repeated.

First, the configuration of a cutting tool including a cutting tool shim in the first embodiment is described.

As shown in <FIG> and <FIG>, a cutting tool <NUM> mainly includes a cutting tool shim <NUM> (hereinafter also referred to as a shim), a cutting insert <NUM>, a holder <NUM>, a fixation portion <NUM>, a first fastening portion <NUM>, and a second fastening portion <NUM>. Holder <NUM> includes a seating surface <NUM>, a side surface <NUM>, and an upper surface <NUM>. Seating surface <NUM> has a first fastening hole <NUM> and a coolant supply hole <NUM>. Upper surface <NUM> has a second fastening hole <NUM>. Side surface <NUM> extends in a direction that intersects both seating surface <NUM> and upper surface <NUM>. Side surface <NUM> is continuous with both seating surface <NUM> and upper surface <NUM>.

Shim <NUM> is disposed between cutting insert <NUM> and holder <NUM>. Shim <NUM> has a first through-hole <NUM>. First fastening portion <NUM> is inserted in first through-hole <NUM>. First fastening portion <NUM> is screwed into first fastening hole <NUM>, thus fixing shim <NUM> to holder <NUM>. Fixation portion <NUM> is disposed on upper surface <NUM> of holder <NUM>. The tip of fixation portion <NUM> is disposed in a second through-hole <NUM> provided in cutting insert <NUM>. Fixation portion <NUM> partially covers the upper surface of cutting insert <NUM>. Fixation portion <NUM> has a third through-hole <NUM>. Second fastening portion <NUM> is disposed in third through-hole <NUM> and screwed into second fastening hole <NUM> provided in upper surface <NUM>, thus fixing fixation portion <NUM> to holder <NUM>. Fixation portion <NUM> fixes cutting insert <NUM>.

As shown in <FIG>, cutting insert <NUM> includes a flank face <NUM>, and a rake face <NUM> continuous with flank face <NUM>. The ridgeline between flank face <NUM> and rake face <NUM> forms a cutting edge <NUM>. Flank face <NUM> extends from cutting edge <NUM> toward shim <NUM>. Rake face <NUM> is a face opposite to the face of cutting insert <NUM> in contact with shim <NUM>. Cutting edge <NUM> includes an arc-shaped portion 2a, a first linear portion 2b, and a second linear portion 2c. First linear portion 2b and second linear portion 2c are each continuous with arc-shaped portion 2a. Arc-shaped portion 2a connects first linear portion 2b and second linear portion 2c. The arc-shaped portion mainly corresponds to the main cutting edge (the cutting edge that plays a major role for generating chips in cutting). In a portion around the boundaries between the arc-shaped portion and the linear portions, the tool advancing side mainly corresponds to the front cutting edge (generally, the cutting edge remote from the finished surface). In a portion around the boundaries between the arc-shaped portion and the linear portions, the side opposite to the tool advancing side mainly corresponds to the side cutting edge (generally, the cutting edge that forms the finished surface).

Flank face <NUM> has a first curved portion 21a, a first plane portion 21b, and a second plane portion 21c. First plane portion 21b and second plane portion 21c are each continuous with first curved portion 21a. First curved portion 21a connects first plane portion 21b and second plane portion 21c. Arc-shaped portion 2a is the ridgeline between first curved portion 21a and rake face <NUM>. First linear portion 2b is the ridgeline between first plane portion 21b and rake face <NUM>. Second linear portion 2c is the ridgeline between second plane portion 21c and rake face <NUM>. The angle between the straight line along first linear portion 2b and the straight line along second linear portion 2c may be smaller than <NUM>°. The angle between first plane portion 21b and rake face <NUM> may be smaller than <NUM>°. Similarly, the angle between second plane portion 21c and rake face <NUM> may be smaller than <NUM>°.

With reference to <FIG>, <FIG>, shim <NUM> has a top surface <NUM>, a bottom surface <NUM>, and a side surface <NUM>. Bottom surface <NUM> is on the side opposite to top surface <NUM>. Side surface <NUM> is continuous with both top surface <NUM> and bottom surface <NUM>. Side surface <NUM> connects top surface <NUM> and bottom surface <NUM>. Side surface <NUM> has a second curved portion 13a, a third plane portion 13b, and a fourth plane portion 13c. On top surface <NUM>, cutting insert <NUM> is to be mounted. In other words, top surface <NUM> comes into contact with the bottom surface of cutting insert <NUM>. As shown in <FIG>, top surface <NUM> has a contact portion 11a to come into contact with cutting insert <NUM>, and a protruding portion 11b continuous with contact portion 11a and separated from cutting insert <NUM>. First through-hole <NUM> is open at both top surface <NUM> and bottom surface <NUM>.

The material that constitutes shim <NUM> is, for example, a ferrous alloy and a cobalt-chromium alloy. The ferrous alloy is, for example, maraging steel, stainless steel (SUS316), or the like. The material that constitutes shim <NUM> is a formed body obtained by, for example, powder metallurgy, 3D printer, or cutting from a metal body. The material that constitutes shim <NUM> may be a single crystal or a polycrystal. The polycrystal is, for example, a metallic formed body obtained by powder metallurgy. The particle diameter of the polycrystal is, for example, not less than <NUM> and not more than <NUM>. The upper limit of the particle diameter may be <NUM> or may be <NUM>. The lower limit of the particle diameter may be <NUM> or may be <NUM>. The material that constitutes shim <NUM> is not limited to metal but may be any other material that can serve as a shim. In terms of workability and durability, the material that constitutes shim <NUM> is preferably a ferrous alloy and a cobalt-chromium alloy.

Next, a method of measuring the particle diameter is described. First, ion milling is performed using a cross section polisher (CP) to form a CP work surface of a shim. Then, the CP work surface is photographed using a scanning electron microscope (SEM), and the structure of the shim is observed. The analytical method is electron back-scatter diffraction (EBSD) analysis. The accelerating voltage is <NUM> kV. A photograph is taken with a magnification of <NUM> times. Based on the difference in crystal orientation of each crystal in the polycrystal, the grain boundary is observed and the particle diameter is measured.

For example, a metal 3D printer can be used to produce shim <NUM>. Specifically, shim <NUM> is produced by heating metallic powder by laser. Thus, pores can be formed in shim <NUM>. The density of shim <NUM> is less than <NUM>%. Specifically, the density of shim <NUM> is, for example, not less than <NUM>% and not more than <NUM>%. The upper limit of the density may be <NUM>% or may be <NUM>%. The lower limit of the density may be <NUM>% or may be <NUM>%. The density of shim <NUM> being less than <NUM>% (that is, pores being present in the shim) enhances the vibration damping properties.

Next, a method of measuring the shim density is described. First, ion milling is performed using a cross section polisher to form a CP work surface of a shim. Then, the CP work surface is photographed using a scanning electron microscope (SEM) to provide a two-dimensional structure photograph of the shim with a magnification of <NUM> times. Pores in the structure are identified using image processing software (WinROOF Ver. <NUM>) manufactured by Mitani Corporation. Specifically, the region with pores and the region without pores are determined by performing conversion to binary on the structure photograph. The shim density is determined as ([the total area of the measurement field] - [the area of pores]) / (the total area of the measurement field). If no pores are present in the shim, the shim density is <NUM>%.

The Rockwell hardness of the material that constitutes shim <NUM> may be, for example, not less than <NUM> and not more than <NUM>. The upper limit of the Rockwell hardness may be <NUM> or may be <NUM>. The lower limit of the Rockwell hardness may be <NUM> or may be <NUM>. The Rockwell hardness is determined by, for example, measuring Rockwell hardness C scale (HRC) in accordance with the method provided in Japan Industrial Standard (JIS Z <NUM>). Specifically, a sample is indented with a conical diamond indenter, and the permanent indentation depth h (mm) is measured. The test force is <NUM> kgf. The additional test force is <NUM> kgf. The total test force is <NUM> kgf. The HRC is calculated in accordance with the following numerical formula <NUM>. Note that the international standard equivalent to Japan Industrial Standard (JIS Z <NUM>) is ISO <NUM>-<NUM>.

As shown in <FIG>, a coolant supply path <NUM> is provided in shim <NUM>. Coolant supply path <NUM> is for jetting coolant, which is supplied from holder <NUM>, to cutting edge <NUM>. Coolant supply path <NUM> includes a lead-in port <NUM>, a jetting port <NUM> for arc-shaped portion, a jetting port 4b for first linear portion, and a jetting port 4c for second linear portion. Lead-in port <NUM> is for leading coolant from holder <NUM> into coolant supply path <NUM>. Lead-in port <NUM> communicates with coolant supply hole <NUM> provided in seating surface <NUM> of holder <NUM>. Jetting port <NUM> for arc-shaped portion is for jetting coolant to arc-shaped portion 2a. The distance between jetting port <NUM> for arc-shaped portion and arc-shaped portion 2a is, for example, about not less than <NUM> and not more than <NUM>. The distance between jetting port <NUM> for arc-shaped portion and arc-shaped portion 2a is the distance between jetting port <NUM> for arc-shaped portion and arc-shaped portion 2a in the direction perpendicular to top surface <NUM>. The distance between jetting port <NUM> for arc-shaped portion and arc-shaped portion 2a may be not less than <NUM> and not more than <NUM>, or may be not less than <NUM> and not more than <NUM>. Jetting port 4b for first linear portion is for jetting coolant to first linear portion 2b. Similarly, jetting port 4c for second linear portion is for jetting coolant to second linear portion 2c.

As shown in <FIG>, jetting port <NUM> for arc-shaped portion, jetting port 4b for first linear portion, and jetting port 4c for second linear portion are open at protruding portion 11b of top surface <NUM>. First through-hole <NUM> is open at contact portion 11a. As shown in <FIG>, lead-in port <NUM> is open at, for example, bottom surface <NUM>. However, lead-in port <NUM> may be open at a surface other than bottom surface <NUM>. Lead-in port <NUM> may be open at, for example, side surface <NUM>.

As shown in <FIG>, <FIG>, coolant supply path <NUM> further includes a vertical pathway <NUM>, a first lateral pathway 6b, a second lateral pathway 6c, a first oblique pathway 7b, a second oblique pathway 7c, and a central pathway <NUM>. As shown in <FIG>, vertical pathway <NUM> is continuous with jetting port <NUM> for arc-shaped portion. As shown in <FIG>, vertical pathway <NUM> is continuous with first lateral pathway 6b and second lateral pathway 6c. As shown in <FIG>, first oblique pathway 7b is continuous with jetting port 4b for first linear portion and central pathway <NUM>. Similarly, second oblique pathway 7c is continuous with jetting port 4c for second linear portion and central pathway <NUM>. As shown in <FIG> and <FIG>, vertical pathway <NUM> extends in the direction perpendicular to top surface <NUM>. Each of first lateral pathway 6b and second lateral pathway 6c extends in the direction parallel to top surface <NUM>. As shown in <FIG>, each of first oblique pathway 7b and second oblique pathway 7c extends obliquely with respect to top surface <NUM>. As shown in <FIG>, central pathway <NUM> is continuous with both first oblique pathway 7b and second oblique pathway 7c.

The arrows in <FIG> represent the flow of coolant. Coolant supplied from holder <NUM> passes through lead-in port <NUM> to be led into central pathway <NUM>. Part of the coolant branches from central pathway <NUM> into first lateral pathway 6b and second lateral pathway 6c, and they join together at vertical pathway <NUM>. Part of the coolant passes through vertical pathway <NUM> and jets from jetting port <NUM> for arc-shaped portion to arc-shaped portion 2a in the shape of curtain (in the shape of layer). The other part of the coolant branches from central pathway <NUM> into first oblique pathway 7b and second oblique pathway 7c. The coolant that has passed through first oblique pathway 7b jets from jetting port 4b for first linear portion to first linear portion 2b in the shape of curtain (in the shape of layer). Similarly, the coolant that has passed through second oblique pathway 7c jets from jetting port 4c for second linear portion to second linear portion 2c in the shape of curtain (in the shape of layer).

Next, the shape of the jetting port for arc-shaped portion is described in detail.

As shown in <FIG>, jetting port <NUM> for arc-shaped portion has a curved shape along arc-shaped portion 2a. Broken line 2d shows the same shape as arc-shaped portion 2a of cutting edge <NUM> of cutting insert <NUM>. The curved shape along arc-shaped portion 2a includes an opening curved along broken line 2a. Specifically, as shown in <FIG>, as seen in the direction perpendicular to top surface <NUM>, the region surrounded by jetting port <NUM> for arc-shaped portion coincides with broken line 2d. Jetting port <NUM> for arc-shaped portion may surround broken line 2d. Arc-shaped portion 2a may have a curved shape formed by arcs having different curvatures continuous with each other.

Jetting port <NUM> for arc-shaped portion may be a single hole having an outer circumference arc 3a, an inner circumference arc 3b, and a connection portion 3c. Outer circumference arc 3a is provided along arc-shaped portion 2a. Inner circumference arc 3b is separated from outer circumference arc 3a and provided along arc-shaped portion 2a. Connection portion 3c connects outer circumference arc 3a and inner circumference arc 3b. Inner circumference arc 3b may be smaller than outer circumference arc 3a in radius of curvature. Outer circumference arc 3a is located between inner circumference arc 3b and second curved portion 13a. Jetting port <NUM> for arc-shaped portion is smaller than lead-in port <NUM> in area. This allows coolant to jet from jetting port <NUM> for arc-shaped portion at a high pressure.

Next, the shapes of the jetting port for first linear portion and the jetting port for second linear portion are described in detail.

Jetting port 4b for first linear portion extends, for example, along a straight line parallel to first linear portion 2b. Jetting port 4b for first linear portion may be a single hole, or may be a plurality of slits disposed at intervals along a straight line. Similarly, jetting port 4c for second linear portion extends, for example, along a straight line parallel to second linear portion 2c. Jetting port 4c for second linear portion may be a single hole, or may be a plurality of slits disposed at intervals along a straight line.

Next, the advantageous effects of the cutting tool shim and the cutting tool in the first embodiment are described.

Cutting tool shim <NUM> for the cutting tool in the first embodiment includes jetting port <NUM> for arc-shaped portion for jetting coolant to arc-shaped portion 2a of cutting edge <NUM>. Jetting port <NUM> for arc-shaped portion has a curved shape along arc-shaped portion 2a. This allows coolant to jet to arc-shaped portion 2a in the shape of layer (in the shape of curtain). Thus, coolant can be supplied over a wide region of arc-shaped portion 2a. As a result, occurrence of local wear of the cutting edge can be reduced. In particular, coolant is supplied to a portion around the boundary between arc-shaped portion 2a and linear portion 2b continuous with arc-shaped portion 2a. Accordingly, boundary wear around the boundary in the flank face can be reduced. Further, since the jetting port is provided in the shim, the jetting port can be brought closer to the edge of the cutting tool than when a jetting port is provided in the holder. This can shorten the distance between jetting port <NUM> for arc-shaped portion and arc-shaped portion 2a of cutting edge <NUM>. As a result, coolant can accurately jet to arc-shaped portion 2a. Further, the mechanism which jets coolant from the shim, not from the holder body, allows easy replacement.

Further, in shim <NUM> in an embodiment not according to the present invention, jetting port <NUM> for arc-shaped portion includes outer circumference arc 3a provided along arc-shaped portion 2a, and inner circumference arc 3b separated from outer circumference arc 3a and provided along arc-shaped portion 2a. Thus, coolant can be supplied over a wide region of arc-shaped portion 2a.

Further, shim <NUM> in the first embodiment includes top surface <NUM> on which cutting insert <NUM> is to be mounted. Top surface <NUM> has contact portion 11a to come into contact with cutting insert <NUM>, and protruding portion 11b continuous with contact portion 11a and separated from cutting insert <NUM>. Jetting port <NUM> for arc-shaped portion is open at protruding portion 11b. Thus, coolant can be effectively supplied to arc-shaped portion 2a.

Further, according to shim <NUM> in the first embodiment, cutting edge <NUM> further includes linear portion 2b continuous with arc-shaped portion 2a. Coolant supply path <NUM> further includes jetting port 4b for linear portion for jetting coolant to linear portion 2b. Thus, coolant can be supplied to linear portion 2b, and also to a portion around the boundary between arc-shaped portion 2a and linear portion 2b. This can reduce wear in linear portion 2b and can also reduce boundary wear.

Further, according to shim <NUM> in the first embodiment, the density of shim <NUM> is not less than <NUM>% and not more than <NUM>%. Pores provided in shim <NUM> can reduce vibrations during cutting.

Further, according to shim <NUM> in the first embodiment, the material that constitutes shim <NUM> is any one of a ferrous alloy and a cobalt-chromium alloy. These materials are usable as materials for a metal 3D printer. A metal 3D printer can accurately produce coolant supply path <NUM> that has a complex shape.

Next, the configurations of a cutting tool and a shim therefor in the second embodiment are described. The following mainly describes the differences from the cutting tool and the shim therefor in the first embodiment, and redundant description is not repeated.

Jetting port <NUM> for arc-shaped portion has a curved shape along arc-shaped portion 2a. As shown in <FIG>, the curved shape along arc-shaped portion 2a includes an opening formed by a plurality of slits 3d provided along broken line 2d, which is in the same shape as that of arc-shaped portion 2a. In this configuration, jetting port <NUM> for arc-shaped portion is formed by a plurality of slits 3d. The plurality of slits 3d are separated from one another. Each of the plurality of slits 3d is, for example, circular in shape. As shown in <FIG>, each of the plurality of slits 3d may be rectangular in shape. Each slit 3d may have any other shape, such as an ellipse, a regular square, or a polygon. The total area of slits 3d which form jetting port <NUM> for arc-shaped portion is preferably smaller than the area of lead-in port <NUM>. If lead-in port <NUM> includes a plurality of lead-in slits corresponding the plurality of jetting slits, each of the plurality of jetting slits is preferably smaller in area than a corresponding one of the plurality of lead-in slits. This allows coolant to jet from each slit 3d at a high pressure. The cutting tool in the second embodiment provides the same advantageous effects as those of the cutting tool in the first embodiment.

Next, the configurations of a cutting tool and a shim therefor in the third embodiment are described. The following mainly describes the differences from the cutting tool and the shim therefor in the first embodiment, and redundant description is not repeated.

As shown in <FIG> and <FIG>, jetting port <NUM> for arc-shaped portion may be formed by a plurality of slits 3d provided along a shape similar to the shape of arc-shaped portion 2a. A shape similar to the shape of arc-shaped portion 2a refers to the same, geometrically similar shape to the shape of arc-shaped portion 2a. In <FIG>, broken line 2f shows the same shape as, but scaled down from arc-shaped portion 2a. The center of the circle along broken line 2f coincides with the center of the circle along broken line 2d. As shown in <FIG>, a plurality of slits 3d may be provided along broken line 2f. In <FIG>, broken line 2e shows the same shape as, but scaled up from arc-shaped portion 2a. The center of the circle along broken line 2e coincides with the center of the circle along broken line 2d. As shown in <FIG>, a plurality of slits 3d may be provided along broken line 2e. Alternatively, in an embodiment not according to the present invention a single, curved jetting port <NUM> for arc-shaped portion may be provided along broken line 2f or broken line 2e. The cutting tool in the third embodiment provides the same advantageous effects as those of the cutting tool in the first embodiment.

Next, the configurations of a cutting tool and a shim therefor in the fourth embodiment are described. The following mainly describes the differences from the cutting tool and the shim therefor in the first embodiment, and redundant description is not repeated.

As shown in <FIG>, shim <NUM> may include a stand portion <NUM>. Stand portion <NUM> forms a part of second curved portion 13a and protrudes in the direction perpendicular to top surface <NUM>. The upper surface 11c of stand portion <NUM> is a part of top surface <NUM>. Upper surface 11c is closer to rake face <NUM> of cutting insert <NUM> than protruding portion 11b is. Jetting port <NUM> for arc-shaped portion may be provided in upper surface 11c of stand portion <NUM>. This allows jetting port <NUM> for arc-shaped portion to be brought closer to arc-shaped portion 2a of cutting insert <NUM>. The cutting tool in the fourth embodiment provides the same advantageous effects as those of the cutting tool in the first embodiment.

First, shims of samples <NUM>-<NUM> to <NUM>-<NUM> were prepared. The shims of samples <NUM>-<NUM> to <NUM>-<NUM> are the present examples. The shims of samples <NUM>-<NUM> to <NUM>-<NUM> are comparative examples. The material of the shims of samples <NUM>-<NUM>, <NUM>-<NUM> and <NUM>-<NUM> was maraging steel. The material of the shims of samples <NUM>-<NUM> and <NUM>-<NUM> was SUS316. The material of the shims of samples <NUM>-<NUM> and <NUM>-<NUM> was Co-Cr alloy. The material of the shim of sample <NUM>-<NUM> was cemented carbide. The material of the shim of sample <NUM>-<NUM> was SUS304. The shim density of samples <NUM>-<NUM> to <NUM>-<NUM> was not less than <NUM>% and less than <NUM>%. The shim density of samples <NUM>-<NUM> to <NUM>-<NUM> was not less than <NUM>% and not more than <NUM>%.

A cutting holder having an acceleration sensor attached to its bottom surface was fixed to a turret of a machine tool. A shim and a cutting insert were attached to the cutting holder. The edge of the cutting insert was vibrated with a force of <NUM> N using an impulse hammer. The change of the vibration acceleration (mm/s<NUM>) with respect to time was measured by the acceleration sensor. The time (t<NUM> - t<NUM>) from the point of time (t<NUM>), at which the vibration acceleration had the maximum amplitude, to the point of time (t<NUM>), at which the amplitude of the vibration acceleration became equal to or less than <NUM> times the maximum amplitude for the first time, was calculated as the vibration damping time.

As shown in Table <NUM>, the vibration damping time in the case of the shims of samples <NUM>-<NUM> to <NUM>-<NUM> was not less than <NUM> and not more than <NUM>, whereas the vibration damping time in the case of the shims of samples <NUM>-<NUM> to <NUM>-<NUM> was not less than <NUM> and not more than <NUM>. In the case of the shims of samples <NUM>-<NUM> to <NUM>-<NUM>, the vibration damping time was shorter than in the case of the shims of samples <NUM>-<NUM> to <NUM>-<NUM>. Thus, it is shown that a shim density of less than <NUM>% remarkably enhances the vibration damping properties regardless of the material of the shim. It is also shown that, with the same material, a lower shim density makes the vibration damping time shorter.

First, cutting tools of samples <NUM>-<NUM> to <NUM>-<NUM> were prepared. The cutting tool of samples <NUM>-<NUM> to <NUM>-<NUM> are the present examples. The cutting tools of samples <NUM>-<NUM> and <NUM>-<NUM> are comparative examples. For the cutting tools of samples <NUM>-<NUM> to <NUM>-<NUM>, cutting oil was jetted from a shim through a holder. For the cutting tool of sample <NUM>-<NUM>, cutting oil was jetted from the bottom surface of a holder through the holder. For the cutting tool of sample <NUM>-<NUM>, cutting oil was jetted from outside.

For the cutting tools of samples <NUM>-<NUM> and <NUM>-<NUM>, the jetting port was in the shape of an arc. For the cutting tool of sample <NUM>-<NUM>, the jetting port was in the shape of a plurality of circular holes arranged in an arc. For the cutting tools of samples <NUM>-<NUM> and <NUM>-<NUM>, the jetting port was in the shape of a single circular hole. For the cutting tool of sample <NUM>-<NUM>, the oiling pressure was <NUM> MPa. For the cutting tools of samples <NUM>-<NUM> to <NUM>-<NUM>, the oiling pressure was <NUM> MPa. For the cutting tool of sample <NUM>-<NUM>, the oiling pressure was <NUM> MPa.

A work material made of inconel <NUM> was cut <NUM> using the cutting tools of samples <NUM>-<NUM> to <NUM>-<NUM>. Then, the flank face wear volume and the boundary wear volume of cutting insert were measured. The cutting speed (Vc) was <NUM>/min. The feed rate (f) was <NUM>/rotation. The depth of cut (ap) was <NUM>. Each cutting insert was a CBN sintered body, BN7000 manufactured by Sumitomo Electric Hardmetal Corporation. The CBN content in the CBN sintered body was <NUM>% by volume, with a WC-Co binder being added.

As shown in Table <NUM>, in the case of the cutting tools of samples <NUM>-<NUM> to <NUM>-<NUM>, the flank face wear volume and the boundary wear volume of cutting insert were respectively not less than <NUM> and not more than <NUM>, and not less than <NUM> and not more than <NUM>; whereas in the case of the cutting tools of samples <NUM>-<NUM> and <NUM>-<NUM>, the flank face wear volume and the boundary wear volume of cutting insert were respectively not less than <NUM> and not more than <NUM>, and not less than <NUM> and not more than <NUM>. This result shows that cutting fluid jetted from a shim can remarkably reduce the flank face wear volume and the boundary wear volume of cutting insert.

In the case of the cutting tool of sample <NUM>-<NUM>, the flank face wear volume and the boundary wear volume of cutting insert were smaller than in the case of the cutting tool of sample <NUM>-<NUM>. This result shows that a higher oiling pressure can reduce the flank face wear volume and the boundary wear volume of cutting insert. Further, the flank face wear volume and the boundary wear volume of cutting insert in the case of the cutting tool of sample <NUM>-<NUM> were substantially the same as the flank face wear volume and the boundary wear volume of cutting insert in the case of the cutting tool of sample <NUM>-<NUM>. This result shows that a jetting port formed by a plurality of circular holes arranged in an arc shape has the same advantageous effects as those of an arc-shaped jetting port.

A work material made of titanium alloy (Ti-6Al-4V) was cut <NUM> using the cutting tools of samples <NUM>-<NUM> to <NUM>-<NUM>. Then, the flank face wear volume and the boundary wear volume of cutting insert were measured. The cutting speed (Vc) was <NUM>/min. The feed rate (f) was <NUM>/rotation. The depth of cut (ap) was <NUM>. Each cutting insert was a CBN sintered body, BN7000 manufactured by Sumitomo Electric Hardmetal Corporation. The CBN content in the CBN sintered body was <NUM>% by volume, with a WC-Co binder being added.

As shown in Table <NUM>, in the case of the cutting tools of samples <NUM>-<NUM> to <NUM>-<NUM>, the flank face wear volume of cutting insert was not less than <NUM> and not more than <NUM>; whereas in the case of the cutting tools of samples <NUM>-<NUM> and <NUM>-<NUM>, the flank face wear volume of cutting insert was not less than <NUM> and not more than <NUM>. Further, in the case of the cutting tools of samples <NUM>-<NUM> to <NUM>-<NUM>, the boundary wear did not occur in the cutting insert; whereas in the case of the cutting tools of samples <NUM>-<NUM> and <NUM>-<NUM>, the boundary wear of not less than <NUM> and not more than <NUM> occurred in the cutting insert. These results show that cutting fluid jetted from a shim can remarkably reduce the flank face wear volume of cutting insert and reduce occurrence of the boundary wear.

Further, in the case of the cutting tool of sample <NUM>-<NUM>, the flank face wear volume of cutting insert was smaller than in the case of the cutting tool of sample <NUM>-<NUM>. This result shows that a higher oiling pressure can reduce the flank face wear volume of cutting insert. Further, the flank face wear volume of cutting insert in the case of the cutting tool of sample <NUM>-<NUM> was substantially the same as the flank face wear volume of cutting insert in the case of the cutting tool of sample <NUM>-<NUM>. This result shows that a jetting port formed by a plurality of circular holes arranged in an arc shape has the same advantageous effects as those of an arc-shaped jetting port.

First, cutting tools of samples <NUM>-<NUM> to <NUM>-<NUM> were prepared. The cutting tools of samples <NUM>-<NUM> to <NUM>-<NUM> are the present examples. The cutting tools of samples <NUM>-<NUM> to <NUM>-<NUM> are comparative examples. For the cutting tools of samples <NUM>-<NUM> to <NUM>-<NUM>, cutting oil was jetted from a shim through a holder. For the cutting tools of samples <NUM>-<NUM> and <NUM>-<NUM>, cutting oil was jetted from the bottom surface of a holder through the holder. The distances between the jetting ports and the edges for the cutting tools of samples <NUM>-<NUM> to <NUM>-<NUM> were respectively <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. For the cutting tools for all the samples, the oiling pressure was <NUM> MPa.

A work material made of inconel <NUM> was cut <NUM> using the cutting tools of samples <NUM>-<NUM> to <NUM>-<NUM>. Then, the flank face wear volume and the boundary wear volume of cutting insert were measured. The cutting speed (Vc) was <NUM>/min. The feed rate (f) was <NUM>/rotation. The depth of cut (ap) was <NUM>. Each cutting insert was a CBN sintered body, BN7000 manufactured by Sumitomo Electric Hardmetal Corporation.

As shown in Table <NUM>, in the case of the cutting tools of samples <NUM>-<NUM> to <NUM>-<NUM>, the boundary wear volume of cutting insert was not less than <NUM> and not more than <NUM>; whereas in the case of the cutting tools of samples <NUM>-<NUM> to <NUM>-<NUM>, the boundary wear volume of cutting insert was not less than <NUM> and not more than <NUM>. This result shows that the boundary wear volume of cutting insert can be remarkably reduced by setting the distance between the jetting port and the edge to not less than <NUM> and not more than <NUM>. It is also shown that the boundary wear volume of cutting insert can further be reduced by setting the distance between the jetting port and the edge to not less than <NUM> and not more than <NUM>.

In the case of the cutting tools of samples <NUM>-<NUM> to <NUM>-<NUM>, the flank face wear volume of cutting insert was not less than <NUM> and not more than <NUM>; whereas in the case of the cutting tools of samples <NUM>-<NUM> and <NUM>-<NUM>, the boundary wear volume of cutting insert was not less than <NUM> and not more than <NUM>. This result shows that cutting oil jetted from a shim can reduce the flank face wear volume of cutting insert more effectively than cutting oil jetted from the bottom surface of a holder.

It should be construed that the embodiments and the examples disclosed herein are given by way of example in every respect, not by way of limitation.

Claim 1:
A cutting tool (<NUM>) comprising: a cutting tool shim (<NUM>), a cutting insert (<NUM>) and a holder (<NUM>), the cutting tool shim (<NUM>) being disposed between the cutting insert (<NUM>) and the holder (<NUM>) and being fixed to the holder (<NUM>),
the cutting insert (<NUM>) including a flank face (<NUM>) and a rake face (<NUM>) continuous with the flank face (<NUM>),
a ridgeline between the flank face (<NUM>) and the rake face (<NUM>) forming a cutting edge (<NUM>),
the cutting edge (<NUM>) including an arc-shaped portion (2a),
a coolant supply path (<NUM>) for jetting coolant to the arc-shaped portion (2a) being provided in the cutting tool shim (<NUM>), the coolant being supplied from the holder (<NUM>),
the coolant supply path (<NUM>) including
a lead-in port (<NUM>) for leading the coolant from the holder (<NUM>) to the coolant supply path (<NUM>), and
a jetting port (<NUM>) for arc-shaped portion (2a) for jetting the coolant to the arc-shaped portion (2a),
the jetting port (<NUM>) for arc-shaped portion (2a) having a curved shape along the arc-shaped portion (2a),
a distance between the jetting port (<NUM>) for arc-shaped portion (2a) and the arc-shaped portion (2a) being not less than <NUM> and not more than <NUM>, characterised in that:
the cutting edge (<NUM>) further includes a linear portion (2b) continuous with the arc-shaped portion (2a),
the coolant supply path (<NUM>) further includes a first jetting port (4b) for a first linear portion (2b) for jetting the coolant to the first linear portion (2b), and a second jetting port (4c) for a second linear portion (2c) for jetting the coolant to the second linear portion (2c), and
the jetting port (<NUM>) for arc-shaped portion (2a) is smaller than the lead-in port (<NUM>) in area.