Patent Description:
For example, <CIT> (PTD <NUM>) discloses a valve finisher capable of coaxially finish machining a hole in a stem guide of a cylinder head in an engine and machining an inner peripheral surface of a valve seat. The valve finisher includes a plurality of cutting inserts which are disposed on the outer periphery of a main body. <CIT> discloses a rotatable valve seat tool assembly.

A cutting tool according to the invention includes a main body and a cutter. The main body has an outer peripheral surface with one end and the other end. The cutter is fixed to the main body. The main body is provided with a hole extending in a direction from a region surrounded by the one end toward a region surrounded by the other end. When viewed from this direction, the shape of the opening of the hole is circular, and the hole is provided inner than the outer peripheral surface. The cutter has a member disposed inside the hole. The main body is provided with a recess in communication with the hole. When viewed from a radial direction, the main body has a projection member covering a part of the recess.

According to the valve finisher, a part of the outer periphery of the main body is cut off so as to form a pocket in the outer periphery, and each cutting insert is disposed in the pocket. Since the outer peripheral portion of the main body is cut off so as to form a pocket therein, the strength and the rigidity of the main body are reduced. Therefore, it is difficult to hold a large number of cutting inserts (cutter) in the main body. As a result, it is necessary to cut a workpiece with a small number of cutters, which consequently deteriorates the durability of cutting edges.

An object of one aspect of the present disclosure is to provide a cutting tool and a cutting device capable of improving the durability of cutters.

According to one aspect of the present disclosure, there is provided a cutting tool and a cutting device capable of improving the durability of cutters.

First, aspects of the present disclosure will be described briefly hereinafter.

A cutting tool <NUM> according to one aspect of the present disclosure includes a main body <NUM> and a cutter <NUM>. The main body <NUM> has an outer peripheral surface <NUM> with one end <NUM> and the other end <NUM>. The cutter <NUM> is fixed to the main body <NUM>. The main body <NUM> is provided with a hole <NUM> extending in a direction from a region <NUM> surrounded by one end <NUM> to a region <NUM> surrounded by the other end <NUM>. When viewed from the above direction, the shape of the opening <NUM> of the hole <NUM> is circular, and the hole <NUM> is provided inner than the outer peripheral surface <NUM>. The cutter <NUM> has a member disposed inside the hole <NUM>. The main body <NUM> is provided with a recess <NUM> in communication with the hole <NUM>. When viewed from a radial direction, the main body <NUM> has a projection member <NUM> covering a part of the recess <NUM>.

After extensive researches for a solution to improve the durability of cutters, the inventors of the present disclosure have achieved the following findings, and thereby established one aspect of the present disclosure. In order to improve the durability of the cutter, it is effective to use a large number of cutters so as to reduce the load of each cutter. In order to use a large number of cutters, it is required to improve the strength of the main body. After extensive studies, the inventors have conceived the idea of providing the cutters inner than the outer peripheral surface of the main body other than on the outer periphery of the main body. As a result, compared with the case where the outer periphery of the main body is cut off to form a pocket, the volume to be cut off the main body is smaller, which makes it possible to improve the strength of the main body.

When a location for disposing the cutter is provided inner than the outer peripheral surface of the main body, it is required to machine the main body in the axial direction instead of in the radial direction. Normally, the shape of a shank for holding a cutting edge is rectangular in plan view. However, in order to form a rectangular hole in the main body along the axial direction in plan view, it is required to perform, for example, electric discharge machining. Compared with machining by a combination of drill machining and subsequent reamer finishing, the electric discharge machining is lower in machining accuracy and longer in machining time, and thereby it is difficult to form a rectangular hole in plan view. Therefore, in the present disclosure, drill machining and subsequent reamer finishing, for example, are used to form a hole having a circular opening in the main body in plan view.

According to the cutting tool <NUM> according to one aspect of the present disclosure, the shape of the opening <NUM> of the hole <NUM> provided in the main body <NUM> is circular, and the hole <NUM> is provided inner than the outer peripheral surface <NUM>, which makes it possible to improve the strength of the main body <NUM>. As a result, a large number of cutters <NUM> can be attached to the main body <NUM>, which makes it possible to improve the durability of each cutter <NUM>.

With a cutting tool according to claim <NUM> it is possible to improve the durability of the cutting edge <NUM>.

With a cutting tool according to claim <NUM>, since the arc-shaped second side face <NUM> contacts the inner peripheral surface of the hole <NUM>, it is possible to improve the positioning accuracy of the shank <NUM> in the radial direction, which contributes to the improvement of the cutting accuracy.

With a cutting tool according to claim <NUM> it is possible to suppress the rotation of the shank <NUM>, which makes it possible to firmly fix the shank <NUM> to the main body <NUM>.

With a cutting tool according to claim <NUM> it is possible to adjust the position of the cutter <NUM> in the above direction with high accuracy, which contributes to the improvement of the cutting accuracy.

With a cutting tool according to claim <NUM> it is possible to suppress the inclination of the shank <NUM> with respect to the above direction.

With a cutting tool according to claim <NUM> it is possible to suppress the vibration of the cutting edge <NUM> during machining.

With a cutting tool according to claim <NUM> it is possible to machine the inner peripheral surface of the valve seat with the cutter <NUM> while performing finish machining of a hole in the stem guide with the reamer, for example.

With a cutting tool according to claim <NUM> the resistance to each cutter <NUM> is reduced, which makes it possible to further improve the durability of the cutters <NUM>.

With a cutting tool according to claim <NUM> it is possible to form an article having an inner peripheral surface whose angle changes along the above direction.

(With a cutting tool according to claim <NUM> it is possible to form an article having an inner peripheral surface with different angles.

With a cutting device <NUM> according to claim <NUM> it is possible to provide the cutting device <NUM> capable of improving the durability of the cutter <NUM>.

Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. It should be noted that in the following drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated.

First, the structure of a cutting tool <NUM> according to the present embodiment will be described.

As illustrated in <FIG>, the cutting tool <NUM> according to the present embodiment mainly includes a main body <NUM>, a cutter <NUM>, a fastening member <NUM>, and a position adjusting member <NUM>. The main body <NUM> has, for example, a hollow cylindrical shape. The main body <NUM> surrounds an axis line <NUM>. A space formed by an inner peripheral surface <NUM> of the main body <NUM> extends along the axis line <NUM>. The main body <NUM> is provided with a recess <NUM> and a hole <NUM> (see <FIG>) in communication with the recess <NUM>. The cutter <NUM> is disposed inside the hole <NUM> (see <FIG>). The cutter <NUM> includes a cutting edge <NUM> and a shank <NUM> configured to hold the cutting edge <NUM>. The shank <NUM> is disposed inside the hole <NUM>. At least a part of the cutting edge <NUM> is positioned in the recess <NUM>.

As illustrated in <FIG>, the main body <NUM> has an outer peripheral surface <NUM>. The outer peripheral surface <NUM> has one end <NUM> and the other end <NUM> (see <FIG>). The hole <NUM> (see <FIG>) extends in a first direction A from one region <NUM> surrounded by one end <NUM> to the other region <NUM> surrounded by the other end <NUM>. The first direction A is, for example, a direction parallel to the axis line <NUM>. Specifically, the hole <NUM> extends, for example, along the direction parallel to the axis line <NUM>. As illustrated in <FIG>, the recess <NUM> opens to the side of one end <NUM> and the outer peripheral surface <NUM>. A plurality of recesses <NUM> are provided along the circumferential direction of the axis line <NUM>. The number of the holes <NUM> and the recesses <NUM> is, for example, <NUM>, but it is not particularly limited thereto. Preferably, the number of the holes <NUM> and the recesses <NUM> is <NUM> or more.

As illustrated in <FIG>, when viewed from the first direction A, the shape of the opening <NUM> of the hole <NUM> is circular. Preferably, when viewed from the first direction A, the inner sectional shape of the hole <NUM> is also circular. When viewed from the first direction A, the hole <NUM> may be provided inner than one end <NUM> or may be provided inner than the other end <NUM>. The hole <NUM> is provided inner than the outer peripheral surface <NUM>. When viewed from the first direction A, the hole <NUM> is provided outer than the inner peripheral surface <NUM>. The hole <NUM> is, for example, a blind hole.

As illustrated in <FIG>, a plurality of holes <NUM> are provided in the main body <NUM> along the circumferential direction of the axis line <NUM>. When viewed from the direction parallel to the axis line <NUM>, the plurality of holes <NUM> are provided on the same circle centered on the axis line <NUM>. In other words, when viewed from the direction parallel to the axis line <NUM>, the distance from the center of each of the plurality of holes <NUM> to the axis line <NUM> is identical. The number of the holes <NUM> is for example <NUM>, but it is not limited to <NUM>. Preferably, the number of holes <NUM> is <NUM> or more. The number of the holes <NUM> is the same as the number of the recesses <NUM>. The main body <NUM> is provided with a plurality of through holes <NUM>. When viewed from the direction parallel to the axis line <NUM>, the plurality of through holes <NUM> are provided on the same circle centered on the axis line <NUM>. The through holes <NUM> extend in the direction parallel to the axis line <NUM>. The number of the through holes <NUM> is, for example, <NUM>, but it is not limited to <NUM>.

As illustrated in <FIG>, the main body <NUM> includes a first main body region <NUM>, a second main body region <NUM>, a third main body region <NUM>, and a fourth main body region <NUM>. The first main body region <NUM> has one end <NUM>. The width W1 of the first main body region <NUM> may increase gradually in the first direction A. The second main body region <NUM> is provided contiguous to the first main body region <NUM>. The width W2 of the first main body region <NUM> is constant in the first direction A. The recess <NUM> extends so as to cross the boundary between the first main body region <NUM> and the second main body region <NUM>. Holes <NUM> are provided in the second main body region <NUM>.

The third main body region <NUM> is provided contiguous to the second main body region <NUM>. The width of the third main body region <NUM> increases monotonically in the first direction A. Holes <NUM> and through holes <NUM> are provided in the third main body region <NUM>. The fourth main body region <NUM> is provided contiguous to the third main body region <NUM>. The width W3 of the fourth main body region <NUM> is constant in the first direction A. As illustrated in <FIG>, in a second direction B (that is, the radial direction B) perpendicular to the axis line <NUM>, the width W3 of the fourth main body region <NUM> is larger than the width W2 of the second main body region <NUM>. In the radial direction B, the width W1 of one region <NUM> surrounded by one end <NUM> is smaller than the width of the other region <NUM> surrounded by the other end <NUM>.

As illustrated in <FIG>, when viewed from the radial direction, the main body <NUM> has a projection member <NUM> that covers a part of the recess <NUM>. The projection member <NUM> projects from the opening end of the concave portion <NUM> along the circumferential direction of the main body <NUM>. As illustrated in <FIG>, the cutting edge <NUM> may be in contact with the projection member <NUM> of the main body <NUM>, which makes it possible to suppress the vibration of the cutting edge <NUM>.

As illustrated in <FIG>, the diameter of the hole <NUM> may be constant in the first direction A. The hole <NUM> may communicate with the hole <NUM>. The hole <NUM> may communicate with the hole <NUM>. A hole <NUM> may be provided in the recess <NUM>. The hole <NUM> may penetrate the recess <NUM> and the inner peripheral surface <NUM>. A hole <NUM> may be provided in the other region <NUM> surrounded by the other end <NUM>. The hole <NUM> is configured to align the main body <NUM> with a connection member <NUM>. As illustrated in <FIG>, the cross-sectional shape of the hole <NUM> may be circular. Each of the plurality of holes <NUM> may be provided on the same cross section. The cross-sectional shape of the inner peripheral surface <NUM> may be circular.

As illustrated in <FIG>, the cutter <NUM> may include a plurality of cutter members 20a, 20b and 20c separated from each other. The plurality of cutter members are provided, for example, on the outer peripheral surface <NUM> along the circumferential direction thereof. The number of cutter members is not particularly limited. The number of cutter members is preferably <NUM> or more, and more preferably <NUM> or more. When the number of cutter members is <NUM>, the cutter <NUM> includes the first cutter member to the sixth cutter member. Each of the first to sixth cutter members has a corresponding cutting edge portion. Each of the first to sixth cutter members is arranged inside a corresponding hole <NUM>. It is not necessary to arrange a cutter member in each of the holes <NUM>. In other words, the number of cutter members may be smaller than the number of holes <NUM>.

As illustrated in <FIG>, the cutter <NUM> includes the cutting edge <NUM> and the shank <NUM>. The shank <NUM> holds the cutting edge <NUM>. The shank <NUM> has a first side face <NUM>, a second side face <NUM>, and a third side face <NUM>. The first side face <NUM> and the third side face <NUM> are flat. The second side face <NUM> is curved. The second side face <NUM> is provided contiguous to the first side face <NUM>. The third side face <NUM> is provided contiguous to the first side face <NUM>. When viewed from the first direction A, the first side face <NUM> is linear. When viewed from the first direction A, the second side face <NUM> is arc-shaped. The third side face <NUM> is inclined with respect to the first side face <NUM>.

As illustrated in <FIG>, the cutting edge <NUM> has a first section <NUM> having a first angle θ1, a second section <NUM> having a second angle θ2, and a third section <NUM> having a third angle θ3. The second angle θ2 may be larger than the first angle θ1. The third angle θ3 may be larger than the second angle θ2. The first angle θ1 is, for example, <NUM>°. The second angle θ2 is, for example, <NUM>°. The third angle θ3 is, for example, <NUM>°. The first section <NUM> is contiguous to the second section <NUM>. The second section <NUM> is contiguous to the third section <NUM>. The first section <NUM> and the third section <NUM> are joined together by the second section <NUM>.

<FIG> illustrates a state in which the shank <NUM> is inserted into the hole <NUM>. As illustrated in <FIG>, the shank <NUM> is disposed in the hole <NUM>. In other words, the shank <NUM> is completely disposed inside the hole <NUM>. A part of the shank <NUM> may be exposed from the hole <NUM>. The cutting edge <NUM> is exposed from the hole <NUM>.

The fastening member <NUM> is configured to fix the shank <NUM> to the main body <NUM>. As illustrated in <FIG>, the fastening member <NUM> is disposed inside the hole <NUM> in communication with the hole <NUM>. The fastening member <NUM> is, for example, a bolt. The fastening member <NUM> is configured to contact the planar first side face <NUM>. When the fastening member <NUM> presses the first side face <NUM>, the second side face <NUM> opposite to the first side face <NUM> is pressed against the main body <NUM>. Thereby, the shank <NUM> is fixed to the main body <NUM>. The first side face <NUM> may be separated from the main body <NUM>.

The position adjusting member <NUM> is configured to adjust the position of the cutter <NUM> in the first direction A. As illustrated in <FIG>, the position adjusting member <NUM> is provided in the hole <NUM> communicating with the hole <NUM>. The position adjusting member <NUM> is, for example, a bolt. The third side face <NUM> included in the shank <NUM> is a flat surface inclined with respect to the first direction A, and is provided contiguous to the first side face <NUM>. The third side face <NUM> is inclined, for example, by <NUM>° with respect to the first side face <NUM>. The position adjusting member <NUM> is configured to contact the third side face <NUM>. In the first direction A, the hole <NUM> is provided between the hole <NUM> and the other end <NUM> (see <FIG>).

By adjusting the height of the position adjusting member <NUM> in the direction along which the hole <NUM> extends (i.e., the vertical direction in <FIG>), the position where the position adjusting member <NUM> contacts the third side face <NUM> is changed. Specifically, when the position adjusting member <NUM> is adjusted to move downward, the shank <NUM> is moved to the left side (the direction approaching one end). Conversely, when the position adjusting member <NUM> is adjusted to move upward, the shank <NUM> is moved to the right side (the direction approaching the other end). As illustrated in <FIG>, the shank <NUM> may have a head portion <NUM> configured to hold the cutting edge <NUM>, and a root portion <NUM> opposite to the head portion <NUM>. When viewed from the first direction A, the root portion <NUM> may be completely surrounded by the main body <NUM>.

Each of the plurality of cutter members 20a, 20b and 20c may have a cutting edge portion having a different angle and a shank portion having a different length. Specifically, as illustrated in <FIG>, the cutter <NUM> includes a first cutter member 20a, a second cutter member 20b, and a third cutter member 20c. As illustrated in <FIG> and <FIG>, the first cutter member 20a may have a first cutting edge portion 21a having a first angle θ1 and a first shank portion 22a configured to hold the first cutting edge portion 21a. The first angle θ1 is, for example, <NUM>°. The first shank portion 22a has a planar first side face 24a and a curved second side face 23a. The second side face 23a is provided contiguous to the first side face 24a. When viewed from the first direction A, the second side face 23a is arc-shaped.

As illustrated in <FIG>, the second cutter member 20b may have a second cutting edge portion 21b having a second angle θ2 and a second shank portion 22b configured to the second cutting edge portion 21b. The second angle θ2 is larger than the first angle θ1. The second angle θ2 is, for example, <NUM>°. The length L12 of the second shank portion 22b in the first direction A may be shorter than the length L11 of the first shank portion 22a. The length L22 of the second cutting edge portion 21b in the first direction A may be shorter than the length L21 of the first cutting edge portion 21a. The second shank portion 22b has a planar first side face 24b and a curved second side face 23b. The second side face 23b is provided contiguous to the first side face 24b. When viewed from the first direction A, the second side face 23b is arc-shaped.

As illustrated in <FIG> and <FIG>, the third cutter member 20c may have a third cutting edge portion 21c having a third angle θ3 and a third shank portion 22c configured to hold the third cutting edge portion 21c. The third angle θ3 is larger than the second angle θ2. The third angle θ3 is, for example, <NUM>°. The length L13 of the third shank portion 22c in the first direction A may be shorter than the length L12 of the second shank portion 22b. The length L23 of the third cutting edge portion 21c may be shorter than the length L22 of the second cutting edge portion 21b. The third shank portion 22c has a planar first side face 24c and a curved second side face 23c. The second side face 23c is provided contiguous to the first side face 24c. When viewed from the first direction A, the second side face 23c is arc-shaped.

As illustrated in <FIG>, the cutting tool <NUM> may further include a connection member <NUM>, a reamer holding member <NUM>, and a screw <NUM>. The main body <NUM> is provided with a protrusion <NUM> for positioning. The protrusion <NUM> is engaged into the hole <NUM> provided in the main body <NUM>. The main body <NUM> is fixed to the connection member <NUM> by using the screw <NUM>. The screw <NUM> passes through the through hole <NUM> provided in the main body <NUM> and is fastened in a screw hole <NUM> provided in the connection member <NUM>. Thereby, the main body <NUM> is fixed to the connection member <NUM>. The reamer holding member <NUM> is configured to penetrate the space surrounded by the inner peripheral surface <NUM> of the main body <NUM>. As described in the above, the main body <NUM> is configured to be detachable from the connection member <NUM>. As illustrated in <FIG>, a reamer <NUM> is provided on one end <NUM> side of the main body <NUM>. The reamer <NUM> is held by the reamer holding member <NUM>. The reamer <NUM> extends in the same direction as the axis line <NUM>.

Hereinafter, the structure of the cutting device <NUM> according to the present embodiment will be described.

As illustrated in <FIG>, the cutting device <NUM> mainly includes the cutting tool <NUM> described in the above and a driving unit <NUM>. The cutting tool <NUM> mainly includes a main body <NUM>, a cutter <NUM>, a connection member <NUM>, a reamer <NUM>, and a reamer holding member <NUM>. The main body <NUM> is configured to be rotatable around the axis line <NUM>. The driving unit <NUM> is, for example, a main shaft of an equipment. As the driving unit <NUM> rotates, the connection member <NUM> and the main body <NUM> are driven to rotate. In other words, the rotational force is transmitted from the driving unit <NUM> to the connection member <NUM>.

As the main body <NUM> rotates, the plurality of cutters <NUM> provided along the circumferential direction of the main body <NUM> are driven to rotate around the axis line <NUM>. As a result, the inner peripheral surface of the valve seat <NUM> is machined by the cutting edge <NUM> of each cutter <NUM>. Similarly, as the reamer <NUM> held by the reamer holding member <NUM> is driven to rotate, a hole is machined in the stem guide <NUM> provided in the cylinder head <NUM>. Since the reamer <NUM> and the main body <NUM> are driven to rotate about the same axis line <NUM>, the inner peripheral surface of the valve seat <NUM> and the hole of the stem guide <NUM> are machined simultaneously.

Hereinafter, the functions and effects of the cutting tool and the cutting device according to the present embodiment will be described.

According to the cutting tool <NUM> of the present embodiment, when viewed from the first direction A, the shape of the opening <NUM> of the hole <NUM> provided in the main body <NUM> is circular, and the hole <NUM> is provided inner than the outer peripheral surface <NUM>, which makes it possible to improve the strength of the main body <NUM>. As a result, a large number of cutters <NUM> can be attached to the main body <NUM>, which makes it possible to improve the durability of each cutter <NUM>.

According to the cutting tool <NUM> of the present embodiment, the cutter <NUM> includes the cutting edge <NUM> and the shank <NUM> configured to hold the cutting edge <NUM>. The shank <NUM> is disposed inside the hole <NUM>. The cutting edge <NUM> is exposed from the hole <NUM>. Thereby, it is possible to improve the durability of the cutting edge <NUM>.

Moreover, according to the cutting tool <NUM> of the present embodiment, when viewed from the first direction A, the shank <NUM> has a first side face <NUM> which is linear, and a second side face <NUM> which is arc-shaped and provided contiguous to the first face <NUM>. Since the arc-shaped second side face <NUM> contacts the inner peripheral surface of the hole <NUM>, it is possible to improve the positioning accuracy of the shank <NUM> in the radial direction, which contributes to the improvement of the cutting accuracy.

Moreover, according to the cutting tool <NUM> of the present embodiment, there is further provided a fastening member <NUM> configured to fix the shank <NUM> to the main body <NUM>. The fastening member <NUM> is in contact with the first side face <NUM>. As a result, it is possible to suppress the rotation of the shank <NUM>, which makes it possible to firmly fix the shank <NUM> to the main body <NUM>.

Moreover, according to the cutting tool <NUM> of the present embodiment, there is further provided a position adjusting member <NUM> configured to adjust the position of the cutter <NUM> in the first direction A. The shank <NUM> includes a third side face <NUM> which is a flat surface inclined with respect to the above direction and provided contiguous to the first side face <NUM>. The position adjusting member <NUM> is in contact with the third side face <NUM>. Thereby, it is possible to adjust the position of the cutter <NUM> in the above direction with high accuracy, which contributes to the improvement of the cutting accuracy.

Moreover, according to the cutting tool <NUM> of the present embodiment, the shank <NUM> has a head portion <NUM> configured to hold the cutting edge <NUM> and a root portion <NUM> opposite to the head portion <NUM>. When viewed from the first direction A, the root portion <NUM> is completely surrounded by the main body <NUM>. As a result, it is possible to suppress the inclination of the shank <NUM> with respect to the first direction A.

Moreover, according to the cutting tool <NUM> of the present embodiment, the cutting edge <NUM> contacts the main body <NUM>, which makes it possible to suppress the vibration of the cutting edge <NUM> during machining.

Moreover, according to the cutting tool <NUM> of the present embodiment, there is further provided a reamer <NUM> on one end side. As a result, it is possible to machine the inner peripheral surface of the valve seat with the cutter <NUM> while performing finish machining of a hole in the stem guide with the reamer, for example.

Furthermore, according to the cutting tool <NUM> of the present embodiment, the cutter <NUM> includes six or more cutter members separated from each other. As a result, the resistance to each cutter <NUM> is reduced, , which makes it possible to further improve the durability of the cutters <NUM>.

Moreover, according to the cutting tool <NUM> of the present embodiment, the cutter <NUM> includes a first cutter member 20a, a second cutter member 20b, and a third cutter member 20c. The first cutter member 20a includes a first cutting edge portion 21a having a first angle θ1, and a first shank portion 22a configured to hold the first cutting edge portion 21a. The second cutter member 20b includes a second cutting edge portion 21b having a second angleθ2 larger than the first angle θ1, and a second shank portion 22b which is configured to hold the second cutting edge portion 21b and is shorter than the first shank portion 22a. The third cutter member 20c includes a third cutting edge portion 21c having a third angle θ3 larger than the second angle θ2, and a third shank portion 22c which is configured to hold the third cutting edge portion 21c and is shorter than the second shank portion 22b. Thereby, it is possible to form an article having an inner peripheral surface whose angle changes along the first direction A.

Furthermore, according to the cutting tool <NUM> of the present embodiment, the cutter <NUM> includes a first cutter member 20a, a second cutter member 20b, and a third cutter member 20c. The first cutter member 20a, the second cutter member 20b and the third cutter member 20c each has a corresponding cutting edge portion 21a, 21b and 21c. Each cutting edge portion includes a first portion <NUM> having a first angle θ1, a second portion <NUM> having a second angle θ2 larger than the first angle θ1, and a third portion <NUM> having a third angle θ3 larger than the second angle θ2. Thereby, it is possible to form an article having an inner peripheral surface with different angles.

The cutting device <NUM> according to the present embodiment includes the cutting tool <NUM> and a driving unit <NUM> configured to rotate the cutting tool <NUM>. Thereby, it is possible to provide the cutting device <NUM> capable of improving the durability of the cutter <NUM>.

It should be understood that the embodiments disclosed herein have been presented for the purpose of illustration and description but not limited in all aspects. It is intended that the scope of the present disclosure is not limited to the description above but defined by the scope of the claims.

Claim 1:
A cutting tool (<NUM>) comprising:
a main body (<NUM>) having an outer peripheral surface (<NUM>) with one end (<NUM>) and the other end (<NUM>); and
a cutter (<NUM>) fixed to the main body (<NUM>),
the main body (<NUM>) being provided with a hole (<NUM>) extending in a direction from a region (<NUM>) surrounded by the one end (<NUM>) toward a region (<NUM>) surrounded by the other end (<NUM>),
when viewed from the above direction, the shape of the opening (<NUM>) of the hole (<NUM>) is circular, the hole (<NUM>) being provided inner than the outer peripheral surface (<NUM>),
the cutter (<NUM>) having a member disposed inside the hole (<NUM>),
the main body (<NUM>) being provided with a recess (<NUM>) in communication with the hole (<NUM>),
characterised in that, when viewed from a radial direction,
the main body (<NUM>) having a projection member (<NUM>) covering a part of the recess (<NUM>).