Patent Description:
As a cutting insert used when a workpiece, such as metal, is subjected to a milling process, an indexable insert in accordance with the preamble of claim <NUM> is described in <CIT> (Patent Document <NUM>). The indexable insert described in Patent Document <NUM> is made up of an indexable insert body (body member) composed of a sintered body, such as cemented carbide or ceramics, and a diamond insert (cutting edge member). A recessed part is disposed at an intersecting portion of a side flank surface and a front flank surface on a rake surface of the indexable insert body, and an insert is brazed to the recessed part.

The diamond insert is provided with an outer side cutting edge and a bottom cutting edge, namely, the outer side cutting edge and the bottom cutting edge are made of diamond, thereby enhancing the strength of a cutting edge. A through hole extends from a rake surface located at the front in a rotation direction to a surface located at the rear in the rotation direction in the indexable insert. The indexable insert is configured to be attached to a rotary cutting tool body (holder) by inserting a clamp screw member into the through hole.

In the configuration that the cutting edge member is connected to the recessed part in the body member as is the case with the cutting insert described in Patent Document <NUM>, a region with a small thickness is formed between the recessed part and the through hole. Durability can become insufficient in the region with the small thickness, for example, when the cutting insert is miniaturized. <CIT> describes a milling cutter having a cutter body including one or more steps extending along the outer peripheral edge of the cutter body, wherein cartridges are detachably mounted on the step, and wherein each of the cartridges have a plurality of equally spaced cutting edges. Preferably, the cutter body has a radially outer step and a radially inner step close thereto, and the cartridges with roughly cutting edges are mounted on the radially outer step.

Furthermore, <CIT> describes a tip and cutting tools including the same, <CIT> describes a cutting blade member, <CIT> describes a mechanical engraver including a rotating plate, a first cutting tool, and a second cutting tool, and <CIT> describes a cutting tool having an annular cutter carrier.

The present embodiments are intended to provide a cutting insert having good durability when the cutting insert is made up of a body member and a cutting edge member.

The invention provides a cutting insert according to claim <NUM>, a cutting tool according to claim <NUM>, and a method of manufacturing a machined product according to claim <NUM>. Preferred embodiments are provided in the dependent claims.

A cutting insert and a cutting tool according to an embodiment are described in detail below with reference to the drawings. For convenience of description, the drawings referred to in the following show, in simplified form, only major components among components of the embodiments. Therefore, the cutting insert and the cutting tool of the present invention may include any optional component not shown in the drawings referred to in the present description. Sizes of the components in the drawings are not faithful to sizes of actual components and to size ratios of these individual components.

In the present embodiment shown in <FIG>, the cutting tool <NUM> of the present embodiment includes a holder <NUM>, a plurality of cutting inserts <NUM> (hereinafter also referred to as "inserts <NUM>"), and a screw <NUM>.

The holder <NUM> has a rotation axis O1. A side where the inserts <NUM> are located is referred to as a front end side, and the opposite of the front end side is referred to as a rear end side, the holder <NUM> is a columnar body member extending along the rotation axis O1 from the front end side toward the rear end side. The holder <NUM> rotates in a rotation direction X1 around the rotation axis O1 about the rotation axis O1 during a cutting process of a workpiece for manufacturing a machined product. In the present embodiment, a central axis of the holder <NUM> that is the columnar body and the rotation axis O1 of the holder <NUM> coincide with each other.

Hereinafter, a side close to the rotation axis O1 is referred to as an inner peripheral side, and a side away from the rotation axis O1 is referred to as an outer peripheral side. A direction from the rear end side of the holder <NUM> toward the front end side thereof is referred to as a front end direction, and a direction from the front end side of the holder <NUM> to the rear end side thereof is referred to as a rear end direction.

For example, steel, cast iron, or aluminum alloy is usable for the holder <NUM>. In the present embodiment, steel having high toughness among these materials is used for the cutting tool <NUM>. The size of the holder <NUM> is suitably settable according to the size of a workpiece. For example, a length in the direction along the rotation axis O1 is settable to approximately <NUM>-<NUM>. A width (diameter) in a direction orthogonal to the rotation axis O1 is settable to approximately <NUM>-<NUM>.

A plurality of insert pockets <NUM> (hereinafter also referred to as "pockets <NUM>") are located along an outer peripheral side on the front end side of the holder <NUM>. The pockets <NUM>, to which the inserts <NUM> are respectively attached, open into the outer peripheral side on the front end side of the holder <NUM> before the attachment of the inserts <NUM>. The pockets <NUM> may be disposed at equal intervals or unequal intervals so as to have rotational symmetry around the rotation axis O1. The pockets <NUM> are preferably disposed at equal intervals in order to reduce variations in load applied to the inserts <NUM> attached to the pockets <NUM>.

The pockets <NUM> are located on the holder <NUM>, and therefore the holder <NUM> is not a strict columnar body. Each of the inserts <NUM> attached to the pockets <NUM> is fixed to the holder <NUM> by the screw <NUM>.

In the present embodiment illustrated in <FIG>, exemplary eight pockets <NUM> are disposed on the holder <NUM> and the inserts <NUM> are respectively located at these eight pockets <NUM>. The number of the pockets <NUM>, and the number of the inserts <NUM> attached to the holder <NUM> are not limited to eight. Therefore, both numbers may be, for example, two, three, four, five, six, or ten or more.

In the present embodiment illustrated in <FIG>, each of the inserts <NUM> is made up of the body member <NUM> and the cutting member <NUM>, and has a columnar body as a whole. In the instant embodiment, the body member <NUM> is a columnar body, and the body member <NUM> is a quadrangular columnar body. The body member <NUM> includes an upper surface <NUM>, a lower surface <NUM>, and an outer side surface <NUM>. The outer side surface <NUM> is located between the upper surface <NUM> and the lower surface <NUM>.

The cutting member <NUM> is located at a corner part of the outer side surface <NUM> of the body member <NUM>. In other words, the cutting member <NUM> is located at a recessed part <NUM> included in the corner part of the outer side surface <NUM> of the body member <NUM>. In the present embodiment, each of the inserts <NUM> are therefore the columnar body as a whole.

The cutting member <NUM> is fixed to the body member <NUM>. The cutting member <NUM> is connected to the body member <NUM> by using a brazing filler metal or the like in the present embodiment. In order to facilitate visual understanding, hatching made up of diagonal lines is applied to the cutting member <NUM> in <FIG>.

The cutting member <NUM> is a part of the insert <NUM> and includes a cutting edge <NUM> for cutting a workpiece. Also, the cutting member <NUM> has high hardness to ensure the high strength cutting edge <NUM> in the insert <NUM>. Thus, the cutting edge <NUM> is not located on the body member <NUM> but located on the cutting member <NUM> in the present embodiment. The body member <NUM> is a base part in the insert <NUM> and need not have hardness equal to or higher than that of the cutting member <NUM>. Manufacturing costs for the inserts <NUM> are reducible while enhancing the strength of the cutting edges <NUM> because the inserts <NUM> are thus respectively made up of the body member <NUM> and the cutting member <NUM>.

For example, cemented carbide or cermet is usable as a material of a member constituting the body member <NUM>. Examples of compositions of the cemented carbide include WC-Co, WC-TiC-Co, and WC-TiC-TaC-Co. WC-Co is producible by adding cobalt (Co) powder to tungsten carbide (WC), followed by sintering. For WC-TiC-Co, titanium carbide (TiC) is added to WC-Co. For WC-TiC-TaC-Co, tantalum carbide (TaC) is added to WC-TiC-Co.

The cermet is a sintered composite material obtainable by compositing the metal with a ceramic ingredient. Specific examples of the cermet include those containing a titanium compound as a main component such as titanium carbide (TiC) or titanium nitride (TiN).

The cutting member <NUM> is made of a material having a higher hardness than a material constituting the body member <NUM>. Specifically, examples of the material of the cutting member <NUM> include polycrystalline diamond and monocrystalline diamond. The hardness of the body member <NUM> and the cutting member <NUM> is evaluable by measuring Vickers hardness of their respective parts.

For Vickers hardness measurement, a well-known test method can be used. In the method, for example, a pyramid-shaped indenter made of a square pyramid diamond is pressed against the surface of a material, and then measured is an indent that remains after removing a load. When the indenter is pressed against the body member <NUM>, an indent is formed on the body member <NUM> because the material of the body member <NUM> is made of the material having a lower hardness than the indenter as illustrated above. When the material of the cutting member <NUM> is monocrystalline diamond, little or no indent is formed.

In the present embodiment, the upper surface <NUM> and the lower surface <NUM> of the body member <NUM> have a tetragonal shape. The upper surface <NUM> is a surface that comes into contact with a seating surface of the pocket <NUM> of the holder <NUM> when the insert <NUM> is attached to the holder <NUM>. The lower surface <NUM> is a surface being exposed to the front end side of the holder <NUM> when the insert <NUM> is attached to the holder <NUM>.

The outer side surface <NUM> of the body member <NUM> includes four surface regions of a front side surface <NUM>, a rear side surface <NUM>, an outer side surface <NUM>, and an inner side surface <NUM>. The side surfaces <NUM>, <NUM>, <NUM> and <NUM> are respectively correspond to sides of the upper surface <NUM> and the lower surface <NUM> each having the tetragonal shape (where the side surfaces are named not only from <FIG> but also from a positional relationship under a situation of the base member <NUM> attached to the holder <NUM>). These surface regions have an approximately tetragonal shape in their respective front views.

The front side surface <NUM> is a surface region located at the front in the rotation direction X1 when the insert <NUM> is attached to the holder <NUM>. In the front view of the front side surface <NUM>, its width in a direction orthogonal to the rotation axis O1 is larger than its height in a direction along the rotation axis O1. The rear side surface <NUM> is another surface region located at the rear in the rotation direction X1 when the insert <NUM> is attached to the holder <NUM>. The rear side surface <NUM> is located opposite to the front side surface <NUM>, and comes into contact with the pocket <NUM> when the insert <NUM> is attached to the holder <NUM>.

The outer side surface <NUM> is another surface region of the outer side surface <NUM> which is located closest to the outer peripheral side when the insert <NUM> is attached to the holder <NUM>. The outer side surface <NUM> protrudes from the holder <NUM> in an outer side direction. Although the entirety of the outer side surface <NUM> protrudes from the holder <NUM> in the present embodiment, there is no intention to limit to this configuration. For example, a part of the outer side surface <NUM> which is close to the front side surface <NUM> may partially protrude from the holder <NUM> in the outer side direction.

The inner side surface <NUM> is another surface region located close to the inner peripheral side when the insert <NUM> is attached to the holder <NUM>, and comes into contact with the pocket <NUM> when the insert <NUM> is attached to the holder <NUM>.

The description that the upper surface <NUM>, the lower surface <NUM>, the front side surface <NUM>, the rear side surface <NUM>, the outer side surface <NUM>, and the inner side surface <NUM> have the tetragonal shape denotes that these surfaces need to have an approximately tetragonal shape but need not to have a strict tetragonal shape. Corners of the surface regions may have a round shape in their respective front views. Also, sides located so as to connect adjacent corners need not to have a strict straight line, but may be partially made into a shape having concave and convex.

The size of the body member <NUM> is not particularly limited. In the present embodiment, for example, a maximum value of a width between the front side surface <NUM> and the rear side surface <NUM> can be set to approximately <NUM>-<NUM> in a top view (in a front view of the upper surface <NUM>). A maximum value of a width between the inner side surface <NUM> and the outer side surface <NUM> can be set to approximately <NUM>-<NUM> in the top view. A maximum value of a thickness between the upper surface <NUM> and the lower surface <NUM> is <NUM>-<NUM>.

In the present embodiment, the body member <NUM> includes the recessed part <NUM>. The recessed part <NUM> is located at a part thereof which corresponds to a region of the front side surface <NUM> on the outer side surface <NUM> which is close to the outer side surface <NUM>, corresponds to a region of the outer side surface <NUM> which is close to the front side surface <NUM>, and corresponds to a corner of the lower surface <NUM>. It can also be said that the recessed part <NUM> in the present embodiment is located at a part of a corner of the upper surface <NUM> and a part of the corner of the lower surface <NUM>, besides on the outer side surface <NUM>.

The cutting member <NUM> is located at the recessed part <NUM> of the body member <NUM>. The cutting members includes at least three surfaces that are exposed. In the present embodiment, the cutting member <NUM> has a tetragonal plate shape, and includes a first surface <NUM> located close to the front side surface <NUM> of the body member <NUM> that is exposed. The cutting member <NUM> also include a second surface <NUM> located close to the outer side surface <NUM> of the body member <NUM>, and a third surface <NUM> located close to the lower surface <NUM> of the body member <NUM> that are exposed.

The cutting member <NUM> includes the cutting edge <NUM> on an intersecting portion where two of the exposed surfaces intersect each other. The cutting edge <NUM> includes a first cutting edge 15A and a second cutting edge 15B in the present embodiment. The first cutting edge 15A is located at an intersecting portion of the cutting member <NUM> where the first surface <NUM> and the second surface <NUM> intersect each other. Accordingly, the first cutting edge 15A extends in a direction from the upper surface <NUM> toward the lower surface <NUM> of the body member <NUM> in the present embodiment.

In the present embodiment, the cutting tool <NUM> is a tool for use in a so-called milling process for cutting a workpiece by causing the holder <NUM> to move in the direction approximately orthogonal to the rotation axis O1 while the holder <NUM> is rotating around the rotation axis O1. The first cutting edge 15A therefore functions as a so-called outer side cutting edge configured to mainly cut the workpiece.

The first cutting edge 15A is located over the entirety of the intersecting portion of the first surface <NUM> and the second surface <NUM> in the present embodiment. Although the first cutting edge 15A may be located at least on a part of the intersecting portion of the first surface <NUM> and the second surface <NUM>. The first cutting edge 15A is disposed over the entirety of the intersecting portion of the first surface <NUM> and the second surface <NUM> in order to ensure a large height of cut in the present embodiment. The length of the first cutting edge 15A can be set to, for example, approximately <NUM>-<NUM>.

The first cutting edge 15A protrudes outward from the outer side surface <NUM> of the holder <NUM> when the insert <NUM> is attached to the holder <NUM>. The first cutting edge 15A has such a straight line form that is inclined so as to approach the rear side surface <NUM> as going from an end portion of the first cutting edge 15A which is close to the lower surface <NUM> toward an end portion of the first cutting edge 15A which is close to the upper surface <NUM>. An axial rake θ of the first cutting edge 15A can be set to, for example, approximately <NUM>-<NUM>° when the insert <NUM> is attached to the holder <NUM>, a.

When the first cutting edge 15A is so located, it is possible to decrease the likelihood that the body member <NUM> can come into contact with a workpiece during a cutting process of the workpiece.

The second cutting edge 15B is located on an intersecting portion of the first surface <NUM> and the third surface <NUM> in the cutting member <NUM>. Therefore, the second cutting edge 15B in the present embodiment extends in a direction along the lower surface <NUM> of the body member <NUM>.

In the present embodiment, the second cutting edge 15B functions as a "flat cutting edge" to decrease unevenness on a machined surface of the workpiece. Hence, the second cutting edge 15B need not necessarily be disposed over the entirety of the intersecting portion of the first surface <NUM> and the third surface <NUM>, but is preferably disposed so as to include a part of the second cutting edge 15B which is located close to the outer periphery in a state of being attached to the holder <NUM> (which is namely a right side of the second cutting edge 15B in <FIG>). The length of the second cutting edge 15B can be set to, for example, approximately <NUM>-<NUM>.

The second cutting edge 15B protrudes toward the front end side of the holder <NUM> when the insert <NUM> is attached to the holder <NUM>. The second cutting edge 15B has a downwardly convex shape when viewed from the front in the rotation direction X1 (for example, in <FIG>). When the second cutting edge 15B is so located, it is possible to minimize the likelihood that the body member <NUM> can come into contact with the workpiece during the cutting process of the workpiece.

The second cutting edge 15B includes a straight line portion. In the present embodiment, the straight line portion extends from the outer peripheral side in the state of being attached to the holder <NUM> (i.e., the right side of the second cutting edge 15B in <FIG>) toward an inner peripheral side. With the second cutting edge 15B that includes the straight line portion, the second cutting edge 15B can function well as the flat cutting edge. A radial rake of the second cutting edge 15B can be set to, for example, approximately <NUM>-<NUM>° when the insert <NUM> is attached to the holder <NUM>.

If the second cutting edge 15B protrudes as describe above, it is possible to avoid that the body member <NUM> comes into contact with the workpiece without inclining the holder <NUM> more than necessary.

In the present embodiment, the body member <NUM> of the insert <NUM> includes a through hole <NUM>. The through hole <NUM> is a portion through which the insert <NUM> is screwed to the holder <NUM>. Specifically, the screw <NUM> is inserted into the through hole <NUM> of the insert <NUM>, a front end of the screw <NUM> is inserted into a screw hole (not shown) that is formed in the pocket <NUM> and therefore the screw <NUM> is fixed to the screw hole. Accordingly, the insert <NUM> is attached to the holder <NUM>.

The through hole <NUM> penetrates through the upper surface <NUM> and the lower surface <NUM> of the main body <NUM>. In other words, the through hole <NUM> is located from the upper surface <NUM> to the lower surface <NUM> of the body member <NUM>, and opens into the upper surface <NUM> and the lower surface <NUM>. Therefore, the through hole <NUM> does not open into the outer side surface <NUM> of the main body <NUM>. In the present embodiment, a penetrating direction of the through hole <NUM> extends along the rotation axis O1.

If the through hole <NUM> penetrates through the front side surface <NUM> and the rear side surface <NUM>, or if the through hole <NUM> penetrates through the outer side surface <NUM> and the inner side surface <NUM>, provided that the through hole <NUM> is identical in size, a small thickness region is formed between the recessed part <NUM> and the through hole <NUM> of the body member <NUM>. If the small thickness region exists, the small thickness region can be damaged due to a load applied to the insert <NUM> during the cutting process.

However, in the present embodiment, because the through hole <NUM> penetrates through the lower surface <NUM> and the upper surface <NUM>, the recessed part <NUM> and the through hole <NUM> are located away from each other. In other words, the first cutting edge 15A subjected to a large cutting resistance and the through hole <NUM> are located away from each other. Therefore, a formation of the small thickness region between the recessed part <NUM> and the through hole <NUM> can be avoided. This leads to the insert <NUM> having good durability.

If the through hole <NUM> is formed from the front side surface <NUM> to the rear side surface <NUM>, it follows that the head of the screw <NUM> is located ahead of a chip flow, and hence the head of the screw <NUM> can be damaged. In contrast, in the present embodiment, the through hole <NUM> opens into the upper surface <NUM> and the lower surface <NUM> in the present embodiment, and therefore, the likelihood of damage to the head of the screw <NUM> can be reduced.

The first surface <NUM> of the cutting member <NUM> is located at the front in the rotation direction X1. Therefore, the first surface <NUM> in the cutting member <NUM> functions as "a rake surface" along which chips flow during the cutting process. Hereinafter, the first surface <NUM> is therefore also referred to as the rake surface. The second surface <NUM> and the third surface <NUM> in the cutting member <NUM> function as "a flank surface" during the cutting process.

In the present embodiment shown in <FIG>, the entirety of the second cutting edge 15B is located closer to the outer peripheral side than the through hole <NUM>. Specifically, the entirety of the second cutting edge 15B is located closer to the outer peripheral side than a middle part of the through hole <NUM> whose inner diameter is constant. A load due to a principal force is applied from the second cutting edge 15B toward the rear in the rotation direction X1 during the cutting process.

However, because the second cutting edge 15B is located closer to the outer peripheral side than the through hole <NUM>, direct transmit of the load from the second cutting edge 15B toward the through hole <NUM> can be avoided. As a result, the durability of the insert <NUM> is further enhanced. The phrase "being located closer to the outer peripheral side" denotes being located away from the rotation axis O1 of the holder <NUM>.

In the present invention, as shown in <FIG>, a vertical thickness of the body member <NUM> in the corner part where the cutting member <NUM> is located is larger than a vertical thickness thereof in a part other than the corner part. Hence, when attached to the holder <NUM>, a part of the body member <NUM> which is located on the outer peripheral side protrudes toward the front end side. In other words, the inner peripheral side of the body member <NUM> has a partially indented shape in <FIG>.

This ensures that the length of the first cutting edge 15A is made longer. It is preferably possible to stably reduce the likelihood that the body member <NUM> and the holder <NUM> come into contact with the workpiece during a ramping process in which the holder <NUM> moves in a direction slightly inclined toward the front end side from the direction approximately orthogonal to the rotation axis O1 while rotating around the rotation axis O1.

A ridge line where the outer side surface <NUM> and the lower surface <NUM> intersect each other is inclined so as to be located closer to the front end side as going toward the front in the rotation direction X1, and he second cutting edge 15B protrudes most toward the front end direction, when the insert <NUM> is viewed from the side as shown in <FIG>. This makes it possible to reduce the likelihood that the lower surface <NUM> comes into contact with the workpiece.

It is also possible to reduce the likelihood that the lower surface <NUM> comes into contact with the workpiece even when the outer side surface <NUM> in the body member <NUM> has the following configuration. That is, a part of the outer side surface <NUM> which is located close to the front in the rotation direction X1 protrudes toward the front end side when attached to the holder <NUM>. In other words, in the present embodiment, a part of the ridge line where the outer side surface <NUM> and the lower surface <NUM> intersect each other, which is located close to the front in the rotation direction X1 protrudes toward the front end side.

In the present embodiment, the insert <NUM> has a parallelogram shape in which an angle formed by the front side surface <NUM> and the outer side surface <NUM> is an acute angle when the insert <NUM> is viewed from above. This ensures a large distance between the first cutting edge 15A and the through hole <NUM>, thereby making it easier to ensure a large thickness between a concave shaped portion to which the cutting member <NUM> in the body member <NUM> is connected, and the through hole <NUM>. It is therefore possible to further enhance the durability of the insert <NUM>.

In the present embodiment, the entirety of the cutting edge <NUM> is located at the front in the rotation direction relative to the through hole <NUM>. A load is also applied from the cutting edge <NUM> toward the rotation axis O1 during the cutting process. However, when the entirety of the cutting edge <NUM> is located at the front in the rotation direction relative to the through hole <NUM>, it is possible to avoid that the load is directly transmitted from the cutting edge <NUM> toward the through hole <NUM>. Consequently, the insert <NUM> can have enhanced durability.

While the cutting tool <NUM> and the insert <NUM> according to the embodiment have been described in detail with reference to the drawings, the cutting tool and the cutting insert according to the present invention are not limited to the configurations in the above embodiment.

A method of manufacturing a machined product according to an embodiment is described below with reference to the drawings.

The machined product is manufacturable by subjecting a workpiece <NUM> to a cutting process. The method of manufacturing the machined product in the present embodiment includes the following steps:.

More specifically, firstly, the cutting tool <NUM> is relatively brought near the workpiece <NUM> by rotating the cutting tool <NUM> around the rotation axis O1 and moving the cutting tool <NUM> in X2 direction as shown in <FIG>. Subsequently, the workpiece <NUM> is cut by bringing the cutting edge <NUM> in the cutting tool <NUM> into contact with the workpiece <NUM>. As the cutting edge <NUM>, the first cutting edge and the second cutting edge are brought into contact with the workpiece <NUM> in the present embodiment as shown in <FIG>. Thereafter, the cutting tool <NUM> is relatively separated from the workpiece <NUM> by further moving the cutting tool <NUM> in the X2 direction as shown in <FIG>.

In the present embodiment, the cutting tool <NUM> is brought near the workpiece <NUM> in a state in which the workpiece <NUM> is fixed and the cutting tool <NUM> is rotated around the rotation axis O1. In <FIG>, the workpiece <NUM> is cut by bringing the first cutting edge and the second cutting edge of the insert <NUM> being rotated into contact with the workpiece <NUM>. In <FIG>, the cutting tool <NUM> being rotated is separated from the workpiece <NUM>.

In the present embodiment, during the cutting process with the manufacturing method, the cutting tool <NUM> is brought into contact with the workpiece <NUM>, or the cutting tool <NUM> is separated from the workpiece <NUM> by moving the cutting tool <NUM> in each of the above steps. Nevertheless, there is no intention to limit to such embodiments.

For example, in the step (<NUM>), the workpiece <NUM> may be brought near the cutting tool <NUM>. Similarly, in the step (<NUM>), the workpiece <NUM> may be separated from the cutting tool <NUM>. When the cutting process is continued, it is necessary to repeat the step of bringing the cutting edge <NUM> in the insert <NUM> into contact with different portions of the workpiece <NUM> while keeping the cutting tool <NUM> rotated.

Claim 1:
A cutting insert (<NUM>), comprising a cutting member (<NUM>) fixed to a body member (<NUM>), the body member (<NUM>) having a columnar shape, and comprising:
an upper surface (<NUM>);
a lower surface (<NUM>) opposed to the upper surface (<NUM>);
an outer side surface (<NUM>) between the upper surface (<NUM>) and the lower surface (<NUM>), including a front side surface (<NUM>) region, a rear side surface (<NUM>) region, an outer side surface (<NUM>) region, and an inner side surface (<NUM>) region; and
a through hole (<NUM>) penetrating through the upper surface (<NUM>) and the lower surface (<NUM>); and the cutting member (<NUM>) being located at a corner part of the outer side surface (<NUM>) of the body member (<NUM>), and comprising:
a first surface (<NUM>) located close to the front side surface (<NUM>) region, a second surface (<NUM>) located close to the outer side surface (<NUM>) region, and a third surface (<NUM>) located close to the lower surface (<NUM>); and
a cutting edge (<NUM>);
characterised in that the body member (<NUM>) has a larger thickness between the upper surface (<NUM>) and the lower surface (<NUM>) in the corner part where the cutting member (<NUM>) is located than in a part other than the corner part;
wherein the cutting edge (<NUM>) comprises:
a first cutting edge (15A) located at an intersecting portion of the cutting member (<NUM>), where the first surface (<NUM>) and the second surface (<NUM>) intersect each other; and
a second cutting edge (15B) located at an intersecting portion of the cutting member (<NUM>), where the first surface (<NUM>) and the third surface (<NUM>) intersect each other.