JP5754331B2 - Replaceable cutting tool - Google Patents

Description

  The present invention relates to a cutting edge exchangeable cutting tool for milling, in which a circular insert is detachably mounted on an insert mounting seat formed on a tool body, and the bottom surface of the circular insert is used as a seating surface of the insert mounting seat for cutting. The present invention relates to a cutting edge-exchangeable cutting tool provided with means for mounting the cutting edge of the circular insert at the correct position on the seating surface when fixed to the cutting edge.

  A circular (or circular piece) insert (hereinafter referred to as a “circular insert”) has an upper surface that forms a rake face, a bottom surface facing the upper surface, and an outer periphery that forms a clearance surface between the upper surface and the bottom surface. And a cutting edge is formed over the entire circumference of the ridge line portion where the upper surface and the outer peripheral side surface cross each other, and the shape thereof is flat and circular. A circular insert is manufactured through a process of forming a molded body of cemented carbide powder by press molding using a die, etc., and heating (sintering) this molded body to an appropriate temperature for sintering. Is done.

  In addition, in a cutting edge-exchangeable cutting tool equipped with a circular insert, when the workpiece is cut for a predetermined cumulative machining time or a predetermined cumulative cutting length, for example, the circular insert is inserted into the insert mounting seat. The circular insert is manually rotated by a predetermined angle so that the unused cutting edge portion of the circular insert can be used for the next cutting process. The operation of reattaching the bottom surface of the seat to the seating surface with a screw member (remounting) is performed. Thereby, one circular insert is provided with the advantage that the area | region of the cutting edge can be effectively utilized for cutting. Usually, about one circular insert, the frequency | count (remounting frequency | count) of re-mounting to an insert mounting seat is made into about 4-8 times.

  As described above, in the cutting edge-replaceable cutting tool in which the circular insert is detachably attached (or “attached” or “fixed”) to the insert mounting seat of the tool body using the screw member, the following problems have conventionally been encountered. 1 and 2 occur.

(Problem 1): Prevention of rotation of the insert Even if the circular insert is firmly fixed to the seating surface of the insert mounting seat by the screw member, the cutting load during cutting acts as a force to loosen the tightening by the screw member of the circular insert. In some cases, the circular insert may turn. For this reason, there exists a subject that it becomes impossible to perform a highly accurate process for a long time, and it becomes necessary to provide the means (rotation prevention means) which prevents rotation of a circular insert.

(Problem 2): Accurate indexing of the cutting edge when the insert is mounted In the cutting edge-replaceable cutting tool mounted with the circular insert, for example, as described above, for example, a predetermined total machining time or a predetermined total When the cutting length is machined, the circular insert is released from the fastening of the threaded member to the seating surface of the insert mounting seat, and the unused cutting edge of this circular insert is used for the next cutting. The circular insert is manually fixed again at the correct position on the seating surface, that is, the cutting edge of the circular insert is accurately indexed, and this circular insert is used on the seating surface with a screw member (set screw) Re-mounting operation is performed again. Thereby, one circular insert is provided with the advantage that the area | region of the cutting edge can be used effectively for cutting in order. Normally, for one circular insert, the number of times of remounting (insertion number of times) to the insert mounting seat is set to about 4 to 8 times in consideration of the amount of cut.

  In the above-described operation of remounting the circular insert, there may be a problem that the circular insert is not mounted at the correct position on the seating surface due to an “inadvertent mistake” by the operator. For example, there may be a mounting error in which the circular insert is mounted so that a part of the already used cutting edge is included in the next cutting edge. In order to prevent this “inadvertent mistake”, in general, in the vicinity of the cutting edge on the upper surface of the circular insert, every equal angle from the center axis of the insert, for example, every 45 ° when the number of remounts is “8”. In addition, an index mark having a minute convex or concave shape is formed in advance, and on the other hand, a mark for visually locating the index mark on the tool axis side in the outer direction of the seating surface of the insert mounting seat. A means for forming one alignment mark is adopted.

In the means using the index mark and the alignment mark, when the circular insert is remounted, the index mark and the alignment mark are visually aligned, that is, the bottom surface of the circular insert is placed on the seating surface. In the state, after confirming the position of the circular insert where the distance between both marks is the smallest, the circular insert is remounted on the seating surface with a screw member. Even in such a cutting edge indexing means, the accurate determination of the indexing position relies on the operator's visual observation, so the above-mentioned “inadvertent mistake” may occur. For example, even if the alignment of the index position mark and the alignment mark is not accurate, it is possible to fix the circular insert to the seating surface with the screw member. There is a possibility that a problem of being used for cutting may occur.
Therefore, in a blade-tip-exchangeable cutting tool to which a circular insert is mounted, it is extremely important to provide a means (indexing means) for indexing the cutting edge accurately when the circular insert is remounted.

  As means for solving the above-described problems 1, 2 or both in a cutting edge exchange type cutting tool using a circular insert, for example, the inventions described in the following Patent Documents 1 to 7 have been proposed.

  In the invention described in Patent Document 1 (Japanese Patent Publication No. 11-508192), in a cutting tool for milling to which a cutting insert having a circular shape is attached, as means for preventing rotation of the cutting insert, The conical surface that is the outer peripheral surface of the circular insert is brought into contact with the receiving surface of the tool body and fixed, and the bottom surface of the circular insert is formed into a polygonal shape, and the polygonal bottom surface is brought into contact with the tool body. Thus, it has been proposed to use in combination with means for preventing rotation of the circular insert. Further, when the circular insert is mounted on the seating surface, the bottom surface of the circular insert is formed into a polygonal shape, and one side of the polygon is brought into contact with the lower portion 37 standing on the periphery of the seating surface (pocket). Positioning (indexing) means.

  The invention described in Patent Document 2 (Japanese Patent Publication No. 2006-523541) includes an anti-rotation tool holder and a cutting tip tool using a circular insert (circular cutting tip), and at least one tip in the tool holder. An anti-rotation means having an anti-rotation stopper including at least one anti-rotation stopper corresponding to the chip pocket and a substantially flat surface has been proposed. Further, the circular cutting tip described in Patent Document 2 is provided with a large number of recesses around its side wall so as to reach the bottom surface (see FIG. 2), and an anti-rotation stopper provided on the tool holder is brought into contact with the recesses. The circular cutting tip is prevented from rotating. Furthermore, it is also disclosed that arcuate side walls are provided on both sides of the rotation prevention stopper (see FIG. 2).

In the invention described in Patent Document 3 (Japanese Patent Application Laid-Open No. 2007-2110090), a circular insert having a nick groove formed on the peripheral surface can be rotated by a predetermined angle and reattached to a mounting seat without erroneous mounting. A round piece insert detachable cutting tool has been proposed. In this cutting tool, a plurality of notch surfaces and a nick groove are formed at equal intervals on the circumferential surface of the circular insert, and some of the notch surfaces in the circumferential direction are spaced apart from each other in the circumferential direction. A part of the nick groove extends to the same position as a restraint surface to the insert mounting seat of the tool body. Further, the insert mounting seat has a mounting seat wall surface against which the restraining surface abuts, and these mounting seat wall surfaces. And a protrusion that is accommodated in a nick groove that is part of the constraining surface.
In this cutting tool, since the constraining surface of the circular insert is attached so as to abut against the mounting seat wall surface of the tool body, the circular insert is caused by the contact between the constraining surface of the circular insert and the mounting seat wall surface of the tool body. It is possible to promote stable machining by holding the insert and rotating it accurately by a predetermined angle and remounting without shifting, dropping, or mismounting. Further, FIG. 5 of Patent Document 3 also shows that the nick groove is configured to reach the upper surface of the circular insert.

In the invention described in Patent Document 4 (Japanese Patent Application Laid-Open No. 2010-247322), the circular insert can be accurately attached to the tool body without preventing the rotation of the circular insert and reducing the strength of the insert. A cutting edge exchangeable cutting tool has been proposed. This blade-tip-exchange-type cutting tool discloses a configuration of an insert fixing portion for fixing a circular insert provided with a concave portion serving as a rotation preventing surface on a conical outer peripheral surface to the tool body. The configuration of the part is composed of a seating surface that receives the bottom surface of the circular insert, two receiving surfaces that receive the outer peripheral surface of the insert, and means for incorporating a rotation preventing member in the center of the two receiving surfaces. Yes. The rotation preventing surface (concave portion) of the insert and the rotation preventing member are brought into contact with each other so as to prevent the circular insert from rotating.
Furthermore, in the cutting edge replacement type cutting tool described in Patent Document 4, in order to prevent the strength of the insert including the cutting edge strength from being lowered, when the thickness of the circular insert is h, the upper end of the rotation preventing surface is the insert. It is disclosed that it is below the position of (2/3) h from the bottom surface, and the lower end of the rotation preventing surface is above the position of (1/10) h from the bottom surface of the insert.

Patent Document 5 (Patent No. 3777043) is equipped with a circular insert that can accurately perform the operation of indexing the cutting edge of the circular insert and has a function of preventing rotation of the circular insert due to a cutting resistance load. Inventions related to cutting tools have been proposed.
The cutting tool described in the same document includes an insert mounting seat for mounting a circular insert, and a configuration in which the flank of the circular insert mounted on the insert mounting seat is restrained by an insert restraint wall formed upright with respect to the insert mounting seat. In the cutting tool, the engagement gear is formed on the bottom surface side of the circular insert to be mounted on the insert mounting seat by repeatedly forming smooth curved irregularities with respect to the axial center of the insert (see FIG. 1B). And a stepped portion (see FIG. 2) having a peripheral edge shape that fits into the engagement gear is formed between the insert mounting seat and the insert restraint wall. In the cutting tool having such a configuration, the engagement gear and the stepped-up portion can be fitted when the circular insert is remounted, so that the cutting edge is positioned at a predetermined accurate position ( It is possible to determine). Further, this document describes that the insert restraint wall is provided so as to stand up with respect to the insert mounting seat via the stepped-up portion.

Patent Document 6 (Japanese Patent Application Laid-Open No. 64-40205) more reliably prevents rotation of the circular insert during cutting and provides a number of index positions for the circular insert to be mounted on the insert mounting seat. An invention relating to a cutting tool for the purpose has been proposed.
In the cutting tool described in the same document, a cavity wall that is engaged with the outer peripheral side surface of the circular insert mounted on the insert mounting seat is provided upright from the periphery of the insert mounting seat, and the seating surface of the insert mounting seat is provided on the seating surface of the insert mounting seat. A fixing pin having a circular cross section is fitted and protruded on the seating surface. In addition, the circular insert has a configuration in which a circular recess concentric with the insert hole is provided on the bottom surface, and an outer peripheral wall of the circular recess is formed by connecting a number of arc-shaped side walls (circular recesses). (See FIG. 4 to FIG. 6). When the circular insert is mounted on the insert mounting seat, the fixing pin is engaged with one of the arc-shaped side walls formed on the bottom surface of the circular insert, so that a large number of index positions can be provided. is there. Further, this document describes that the arc-shaped side wall has a radius equal to the radius of the fixing pin (the specification, page 2, lower left column, lines 13 to 15).

In Patent Document 7 (US2011 / 0103905A1), in a cutting edge-exchangeable cutting tool in which a circular insert is mounted, prevention of rotation of the circular insert during cutting and cutting when the circular insert is mounted on an insert mounting seat are disclosed. There has been proposed an invention relating to a circular insert capable of indexing the position of a cutting edge used for processing.
The circular insert described in this document is provided with a plurality of projections concentrically and equiangularly from the center axis of the insert on the top and bottom surfaces of the circular insert, and seating of an insert mounting seat on which the circular insert is mounted. By providing a recess (dimple) that engages with the protrusion provided on the circular insert on the surface, the position of the cutting edge can be reliably determined when the circular insert is mounted on the seating surface of the insert mounting seat. It is what I did.

On the other hand, in the cutting edge exchange type cutting tool in which the circular insert is detachably attached, as described above, the circular insert is made of cemented carbide. In general, the following means is adopted for manufacturing a circular insert made of cemented carbide.
A fine powdered cemented carbide is formed into a circular insert press-molded body (green molded body) having a predetermined size by, for example, die molding, and then the press-formed body is heated to a predetermined temperature. And calcined to obtain a press-molded body having high hardness and high strength. Next, a circular insert is manufactured by subjecting this fired press-molded body to a finishing process at a predetermined location as necessary. In addition, in order to improve the wear resistance of the circular insert, a surface of the circular insert is also coated with a hard film.

  In the manufacture of the circular insert described above, the press-formed body of the circular insert is formed as a formed body having a predetermined dimension in consideration of shrinkage during firing. Since individual press-molded bodies after firing vary in shrinkage during firing due to the thickness of each part, etc., there are minute variations (dimensions) in the dimensions of each part for each circular insert. For this reason, for example, in the case of a circular insert with an inscribed circle diameter specification of 12.0 mm, the tolerance of the dimensions of each part is “± 0.05 mm”, etc., and inserts outside this tolerance are used as nonstandard It is made not to be done.

However, as described above, even if strict tolerances are provided for the dimensions of each part of the circular insert, there is a small dimensional difference within the tolerance range for each circular insert to be mounted on the seating surface of the tool body insert. Yes. Therefore, in a cutting edge-exchangeable cutting tool to which a circular insert is mounted, even if there is such a small dimensional difference within the tolerance range, each circular insert is stably and highly mounted on the insert mounting seat including the seating surface of the tool body. Providing attachment means with high accuracy makes it possible to more reliably prevent the circular insert described above from rotating, thereby improving the processing quality and accuracy of the processed surface.
This highly accurate mounting means is a cutting edge exchangeable cutting method in which a cemented carbide circular insert is mounted and the position of the cutting edge must be accurately determined each time the mounting angle to the seating surface is remounted. This is extremely important for tools in order to improve the machining accuracy of the work surface of the work material.

Japanese National Patent Publication No. 11-508192 JP 2006-523541 A JP 2007-210902 A JP 2010-247322 A Japanese Patent No. 3777043 (FIGS. 1 and 2) JP-A 64-40205 (FIG. 4) US2011 / 0103905 A1 Gazette

  Although the cutting tool for milling described in Patent Document 1 includes a rotation prevention means and an indexing means for the circular insert, the indexing means makes the bottom surface of the circular insert a polygonal shape, and one side of this polygon is formed. It is set as the structure contact | abutted with the lower part (37) standingly arranged in the peripheral part of the seating surface (pocket). However, when the bottom surface of the circular insert is made polygonal, the strength of the bottom surface is reduced and the contact with the seating surface is reduced when the circular insert is mounted on the seating surface by screw means, compared to the case where the bottom surface is made circular. Since the area is reduced, the adhesion between the two is reduced, and the circular insert may be rotated during the cutting process.

  In the rotation prevention holder described in Patent Document 2, a large number of recesses are provided around the side wall of the circular cutting tip so as to reach the bottom surface, and an anti-rotation stopper provided on the tool holder is brought into contact with the recess. The structure of the rotation preventing means for preventing the rotation of the circular cutting tip is disclosed, but the indexing means for indexing and mounting the circular cutting tip at an accurate position of the seating surface (pocket) is disclosed. Absent. Moreover, since many recessed parts are provided around the side wall of the cutting tip so as to reach the bottom surface, the strength of the bottom surface may be lowered.

In the circular piece insert detachable cutting tool described in Patent Document 3, some notch surfaces in the circumferential direction of the notch surfaces have some nick grooves extending at equal positions in the circumferential direction. The tool body is used as a constraining surface to the insert mounting seat, and further, the insert mounting seat has a mounting seat wall surface against which the constraining surface abuts, and protrudes from the mounting seat wall surface into a part of the nick groove of the constraining surface. By adopting a configuration in which the projections to be received are formed, the circular insert is held by the abutment between the constraining surface of the circular insert and the mounting seat wall surface of the tool body, so that the circular insert does not move, fall off, or misinstall. It is a cutting tool provided with means for accurately rotating and remounting by a predetermined angle, that is, a rotation preventing means and an indexing means.
However, in the circular insert to be mounted on this round piece insert detachable cutting tool, since a large number of notch surfaces and nick grooves are provided on the side surface, it becomes insufficient to ensure the strength of the circular insert, Since some of the nick grooves are formed so as to reach the rake face of the circular insert, there is a problem that man-hours are required for finishing the cutting edge.

  The cutting edge-exchangeable cutting tool described in Patent Document 4 includes two receiving surfaces that receive the outer peripheral surface of the insert, and means for incorporating a rotation preventing member at the center of the two receiving surfaces. Although the rotation prevention means which made the formed rotation prevention surface (concave part) contact with this rotation prevention member is disclosed, the indexing means of the circular insert is not disclosed.

The cutting tool described in Patent Document 5 is fitted with a stepped portion formed between an insert mounting seat and an insert constraining wall with an engagement gear formed by repeatedly forming a smooth curved irregularity on the bottom surface side of a circular insert. By providing the indexing means for indexing the cutting edge to a predetermined accurate position, the engaging gear is configured to protrude from the bottom surface of the circular insert.
However, if the engagement gear is configured to protrude from the bottom surface side with respect to the axial center of the circular insert, this circular insert is produced from the molding process to the firing process of the press-formed body during the manufacture of the cemented carbide circular insert. Special measures are required for handling of the press-formed body. This is because, for example, it is necessary to devise a method for arranging the circular insert molded bodies on the baking tray in order to prevent the engagement gear from being damaged or to eliminate baking unevenness. Accordingly, there is a possibility that the cost of the firing process is increased from the molding process of the press molded body.

  The cutting tool described in Patent Document 6 is provided with a circular recess concentric with the insert hole on the bottom surface of the circular insert, and the outer peripheral wall of the circular recess is formed by connecting a number of arc-shaped side walls (circular recesses). When the circular insert is mounted on the insert mounting seat, a number of indexing positions can be obtained by engaging a fixing pin fixed to the mounting seat with one of the arc-shaped side walls formed on the bottom surface of the circular insert. At the same time, the circular insert is prevented from rotating, but has the following problems.

(1) When the fixing pin fixed to the mounting seat is engaged with one of the arc-shaped side walls formed on the bottom surface of the circular insert, a sufficient prevention force to prevent the circular insert from rotating during cutting is obtained. Is impossible. This is because it is impossible to obtain a sufficient prevention force for preventing the circular insert from rotating only by engagement between the arcuate outer peripheral surface of the fixing pin and the arcuate side wall.
(2) FIG. As shown in FIG. 4, when 20 arcuate side walls, that is, 20 indexing positions are set, the length of the cutting edge used for the cutting process becomes extremely short, so that the cutting depth is small. The cutting tool can be used only for cutting. That is, the application of cutting is limited. There is also a problem that the strength of the bottom surface of the circular insert cannot be sufficiently ensured.

  The rotation prevention means for the circular insert described in Patent Document 7 is provided with projections that form a concentric shape from the center axis of the insert on the upper surface and the bottom surface of the circular insert and are substantially circular in a plurality of plan views at an equal angle. When the circular insert is mounted on the seating surface of the insert mounting seat by providing a recess (dimple) that engages a plurality of protrusions provided on the circular insert on the seating surface of the insert mounting seat on which the circular insert is mounted. Although the position of the cutting edge can be reliably determined, there are the following problems.

  (1) The number of protrusions provided on the circular insert and the number of recesses provided on the seating surface are the same, for example, six. However, considering the versatility of the tool body, the number of recesses formed on the seating surface of the tool body is preferably one. The reason for this is that even when the number of protrusions provided on the circular insert is set to eight or four, if the number of recesses formed on the seating surface is set to one, the versatility of this tool body is demonstrated, and the user This is because it can contribute to the cost reduction of the cutting tool.

  (2) As described above, when the circular insert is made of cemented carbide, dimensional variation due to firing occurs. High-precision formation of a plurality of recesses at equal intervals on the seating surface of the insert mounting seat is possible by using an NC-controlled processing machine, but it is inevitable that a plurality of protrusions are formed on the upper surface (bottom surface) of the circular insert. This causes variations in the dimensions. For this reason, the finishing process for correcting this dimensional variation is required, which causes a problem of increasing the manufacturing cost of the circular insert.

  Therefore, an object of the present invention is to perform cutting when a circular insert is mounted on an insert mounting seat in a cutting edge exchangeable cutting tool in which a cemented carbide circular insert is detachably mounted on an insert mounting seat of a tool body. The cutting edge to be used can be mounted at an accurate indexing position, and the circular insert mounted on the insert mounting seat is prevented from rotating due to the cutting load during cutting, and the circular insert is inserted. An object of the present invention is to provide a cutting edge-exchangeable cutting tool that can be mounted on a mounting seat with high positional accuracy.

A blade-tip-exchangeable cutting tool according to claim 1 of the present invention includes a top surface serving as a rake surface, a bottom surface formed opposite to the top surface, and a relief connecting the top surface and the bottom surface to an insert mounting seat of a tool body. A circular insert provided with an outer peripheral side surface serving as a surface, a cutting edge formed at a ridge line portion where the rake surface and the flank intersect, and a screw insertion hole penetrating from the upper surface to the bottom surface, Two arcuate wall surfaces that are detachably mounted using a screw member in a screw hole formed on the seating surface, and the outer peripheral side surface of the circular insert mounted on the seating surface is erected from the insert mounting seat One of a plurality of outer peripheral rotation prevention surfaces formed at predetermined intervals in the circumferential direction of the outer peripheral side surface of the circular insert, and is set up from the insert mounting seat to have a predetermined lateral width. In the first indexable cutting tool is brought into contact with the rotation preventing portion having a restraining surface that,
The circular insert has a mounting index portion that is a recess with respect to the bottom surface on the bottom surface,
The mounting indexing portion forms a smooth convex curved shape in a direction away from the central axis of the screw insertion hole along the circumferential direction of the concentric circle of the central axis of the screw insertion hole at the boundary with the bottom surface. A plurality of first side walls and a stepped side wall portion in which a plurality of second side walls forming a smooth convex curved shape in a direction approaching the central axis of the screw insertion hole are alternately arranged,
The seating surface of the insert mounting seat is a second rotation preventing portion that can be inserted into the recess of the concave portion adjacent to the curved first side wall in the mounting index portion of the circular insert. With
When the circular insert is attached to the seating surface and the cutting edge of the circular insert is indexed,
The second rotation preventing portion is inserted into the hollow portion of the circular insert, and the restraining surface of the first rotation preventing portion can come into contact with the outer peripheral rotation preventing surface of the circular insert. It is characterized by.

The invention according to claim 2 relates to the cutting edge-exchangeable cutting tool according to claim 1, wherein the stepped side wall portion of the circular insert includes a plurality of the first side wall and the second side wall forming the curved shape. Are connected in sequence,
The length from the opening end portion of the screw insertion hole to the farthest portion in the first side wall having the curved shape is the farthest portion from the opening end portion of the screw insertion hole in the second side wall having the curved shape. It is said that it is larger than the length until
The length of the second rotation preventing portion provided in the seating surface, the length in the direction passing through the central axis of the screw hole is the farthest portion in the first side wall having the curved shape And the length of the second side wall having the curved shape is larger than the length to the farthest portion.

A third aspect of the present invention relates to the cutting edge-exchangeable cutting tool according to the first or second aspect, and the restraint surface provided in the first rotation preventing portion in a plan view of the insert mounting seat. The end of the horizontal width of the line is defined as a point R and a point Q, and a straight line passing through the midpoint of the line RQ connecting the point R and the point Q and the central axis of the screw hole formed in the seating surface is defined as a straight line S2. sometimes,
The second rotation preventing part is formed along the straight line S2,
The circular insert attached to the insert mounting seat is a plan view of the upper surface or the bottom surface of the circular insert.
The first side wall having the curved shape formed on the bottom surface and the outer peripheral rotation prevention surface formed on the outer peripheral side surface are formed so as to face each other, and
The second side wall having the curved shape and the outer peripheral side surface between the adjacent outer peripheral rotation prevention surfaces are formed so as to face each other.

A fourth aspect of the present invention relates to the cutting edge replaceable cutting tool according to the first or second aspect, wherein the restraint surface provided in the first rotation preventing portion in a plan view of the insert mounting seat. The horizontal width end of each of the two is defined as a point R and a point Q, and a straight line passing through the midpoint of the line RQ connecting the point R and the point Q and the central axis of the screw hole formed in the seating surface is defined as a straight line S2. When a straight line that intersects the straight line S2 in the clockwise rotation direction or the counterclockwise rotation direction at a predetermined angle α1 or α2 is defined as a straight line S3 and a straight line S4,
The angle α1 or α2 is set in a range of 2 ° to 10 °,
The circular insert attached to the insert mounting seat is a plan view of the upper surface or the bottom surface of the circular insert.
The first side wall having the curved shape formed on the bottom surface and the outer peripheral rotation prevention surface formed on the outer peripheral side surface are formed so as to face each other, and
The second side wall having the curved shape and the outer peripheral side surface between the adjacent outer peripheral rotation prevention surfaces are formed so as to face each other.

A fifth aspect of the present invention relates to the cutting edge replaceable cutting tool according to the first or second aspect, wherein the restraint surface provided in the first rotation preventing portion in a plan view of the insert mounting seat. The horizontal width end of each of the two is defined as a point R and a point Q, and a straight line passing through the midpoint of the line RQ connecting the point R and the point Q and the central axis of the screw hole formed in the seating surface is defined as a straight line S2. When a straight line that intersects the straight line S2 and forms a predetermined angle α with the straight line S2 in the clockwise or counterclockwise direction is defined as a straight line D1 or a straight line D2,
The second rotation preventing portion is formed along the straight line D1 or the straight line D2.
The angle α is set to α = 360 ° / (2 × n), where n is the number of first side walls having the curved shape provided in the mounting index portion of the circular insert,
The circular insert attached to the insert mounting seat is a plan view of the upper surface or the bottom surface of the circular insert.
The second side wall having the curved shape formed on the bottom surface and the outer peripheral rotation prevention surface formed on the outer peripheral side surface are formed so as to face each other, and
The first side wall having the curved shape and the outer peripheral side surface between the adjacent outer peripheral rotation prevention surfaces are formed so as to face each other.

The invention according to claim 6 relates to the cutting edge-exchangeable cutting tool according to claim 1 or 2, wherein, in the plan view of the insert mounting seat, the restraint surface of the first rotation preventing portion is provided. The end of the width is defined as point R and point Q, a straight line passing through the midpoint of the line RQ connecting the point R and point Q and the central axis of the screw hole formed in the seating surface is defined as a straight line S2. A straight line that intersects the straight line S2 and forms a predetermined angle α with the straight line S2 in the counterclockwise direction is defined as a straight line D2, and further intersects with the straight line D2 and is angled with the straight line D2 in the clockwise or counterclockwise direction. When the straight line forming α1 is the straight line S5 or S6,
The second rotation preventing portion is formed along the straight line S5 or the straight line S6.
The angle α is set to α = 360 ° / (2 × n), where n is the number of first side walls having the curved shape provided in the mounting index portion of the circular insert. The angle α1 is set in a range of 2 ° to 10 °,
The circular insert attached to the insert mounting seat is a plan view of the upper surface or the bottom surface of the circular insert.
The second side wall having the curved shape formed on the bottom surface and the outer peripheral rotation prevention surface formed on the outer peripheral side surface are formed so as to face each other, and
The first side wall having the curved shape and the outer peripheral side surface between the adjacent outer peripheral rotation prevention surfaces are formed so as to face each other.

The invention according to claim 7 relates to the cutting edge-exchangeable cutting tool according to claim 1 or 2, wherein the restraint surface provided in the first rotation preventing portion in a plan view of the insert mounting seat. The horizontal width end of each of the two is defined as a point R and a point Q, and a straight line passing through the midpoint of the line RQ connecting the point R and the point Q and the central axis of the screw hole formed in the seating surface is defined as a straight line S2. A straight line that intersects the straight line S2 and forms a predetermined angle α with the straight line S2 in the clockwise direction is a straight line D1, and further intersects the straight line D1 and has an angle with the straight line D1 in the clockwise or counterclockwise direction. When the straight line forming α2 is the straight line S7 or S8,
The second rotation preventing portion is formed along the straight line S7 or the straight line S8,
The angle α is set to α = 360 ° / (2 × n), where n is the number of first side walls having the curved shape provided in the mounting index portion of the circular insert. The angle α2 is set in a range of 2 ° to 10 °,
The circular insert attached to the insert mounting seat is a plan view of the upper surface or the bottom surface of the circular insert.
The second side wall having the curved shape formed on the bottom surface and the outer peripheral rotation prevention surface formed on the outer peripheral side surface are formed so as to face each other, and
The first side wall having the curved shape and the outer peripheral side surface between the adjacent outer peripheral rotation prevention surfaces are formed so as to face each other.

  According to an eighth aspect of the present invention, there is provided the cutting edge replacement type cutting tool according to the third or fourth aspect, wherein the circular insert has the most protruding end portion of the first side wall having the curved shape, the outer peripheral rotation. The first side wall having the curved shape and the outer peripheral rotation prevention surface are arranged so as to face the central portion of the movement prevention surface.

  A ninth aspect of the present invention relates to the cutting edge-exchangeable cutting tool according to any of the fifth to seventh aspects, wherein the most recessed end portion of the second side wall having the curved shape is the outer peripheral rotation prevention. The second side wall having the curved shape and the outer peripheral rotation prevention surface are arranged so as to face the central portion of the surface.

A tenth aspect of the present invention relates to the cutting edge-exchangeable cutting tool according to any one of the first to ninth aspects, wherein the first side wall having the curved shape constituting the step side wall portion of the circular insert is , Forming an arc shape with a radius (r1) protruding outward with respect to the central axis of the screw insertion hole,
The distal end portion of the second rotation preventing portion formed on the seating surface has an arc shape with a radius (r2) protruding outward with respect to the central axis of the screw hole,
The radius (r1) is larger than the radius (r2).

The invention according to claim 11 relates to the cutting edge-exchangeable cutting tool according to any one of claims 1 to 10, wherein the circular insert has a thickness h1, and the outer peripheral rotation preventing surface from the bottom surface. When the height to the upper end is h2, and the height from the bottom surface to the lower end of the outer peripheral rotation prevention surface is h3,
The h2 satisfies the following formula:
(1/2) h1 ≦ h2 ≦ (2/3) h1
The h3 satisfies the following expression.
(1/10) h1 ≦ h3 ≦ (1/3) h1

A twelfth aspect of the present invention relates to the cutting edge-exchangeable cutting tool according to the first aspect, wherein one of the two arcuate wall surfaces is located on one end side of the first rotation preventing portion. The other of the arcuate wall surfaces is erected on the other end side of the first rotation preventing portion,
One of the arc-shaped wall surfaces is composed of a wall surface obtained by integrating two first side wall surfaces and second side wall surfaces having different arc-shaped diameters,
The other of the arc-shaped wall surfaces is constituted by a wall surface obtained by integrating a third side wall surface and a fourth side wall surface having different arc-shaped diameters.

A thirteenth aspect of the present invention relates to the cutting edge replaceable cutting tool according to the twelfth aspect of the present invention, wherein the first side wall surface is disposed on one end side of the first rotation preventing portion, and the first The third side wall surface is disposed on the other end side of the rotation preventing portion,
The diameter of the circular arc shape of the first side wall surface and the third side wall surface is set to the same diameter d1, and the diameter d1 is set to the diameter d0 of the inscribed circle of the circular insert attached to the insert mounting seat. Set,
The diameter of the circular arc shape of the second side wall surface and the fourth side wall surface is set to the same diameter d2, and the diameter d2 is set to be larger than the diameter d1.

A fourteenth aspect of the present invention relates to the cutting edge-exchangeable cutting tool according to any one of the first, twelfth, and thirteenth aspects, wherein the two arcuate wall surfaces or the first to the first ones. The fourth side wall surface is erected with an inclination angle β1 in the tool axis direction of the tool body with respect to a line segment orthogonal to the seating surface,
When the inclination angle of the outer peripheral side surface of the circular insert attached to the seating surface is θ1, (θ1−β1) satisfies the following expression.
0 ≦ θ1-β1 ≦ 1.0

  A fifteenth aspect of the present invention relates to the cutting edge-exchangeable cutting tool according to any one of the first, twelfth to fourteenth aspects, wherein the two arcuate wall surfaces or the first to fourth side wall surfaces are It is characterized by having a plurality of machining streaks in the vertical direction.

  A sixteenth aspect of the present invention relates to the blade-tip-exchangeable cutting tool according to any one of the first, second, and seventh to fifteenth aspects, wherein the seating surface, the arc-shaped wall surface, and the first One or more elements selected from the elements of Periodic Tables 4a, 5a, and 6a group metals, Al, Si, and B are included in at least one of the first to fourth side wall surfaces and the first rotation prevention unit. It is characterized in that a hard film made of any one of nitride, carbonitride, and oxynitride containing is coated.

  According to the cutting edge replaceable cutting tool of the present invention, when the circular insert is mounted on the seating surface of the insert mounting seat, the second rotation preventing portion formed on the seating surface is formed on the bottom surface of the circular insert. The bottom surface of the circular insert and the seating surface are in close contact with each other. Thereby, it becomes possible to mount the circular insert at an accurate indexing position with respect to the seating surface of the insert mounting seat, and it is possible to prevent the occurrence of “inadvertent mistakes” when the circular insert is mounted.

  Further, when the circular insert is mounted at an accurate indexing position with respect to the seating surface of the insert mounting seat, the second anti-rotation portion formed on the seating surface is the mounting indexing portion formed on the bottom surface of the circular insert. During the cutting process, the outer peripheral rotation prevention surface formed on the outer peripheral side surface of the circular insert during cutting is in contact with the first rotation prevention part erected on the insert mounting seat. It is possible to prevent the circular insert from rotating.

  Furthermore, since the two side walls forming an arc shape standing on the insert mounting seat have a configuration in which at least two side wall surfaces having different diameters are connected to each other, the inscribed circle of the circular insert made of cemented carbide is used. Even if there is a dimensional variation within the tolerance range, the outer peripheral side surface of each circular insert fixed to the seating surface by the screw means can be constrained by these two side wall surfaces. As a result, the circular insert can be mounted on the insert mounting seat with high positional accuracy and in a stable state, and as a result, the processing accuracy of the processing surface can be improved.

It is a perspective view which shows an example of the blade-tip-exchange-type cutting tool of this invention, Comprising: It is a perspective view which shows the state which is not mounting | wearing with the insert mounting seat of the tool main body. It is a perspective view which shows a state when a circular insert is mounted | worn with the tool main body of the blade-tip-exchange-type cutting tool shown in FIG. It is a figure which shows the structure of the insert mounting seat containing a seating surface about the blade-tip-exchange-type cutting tool shown in FIG. It is a side view of the circular insert shown in FIG. It is the perspective view which looked at the circular insert shown in FIG. 4 from the bottom face direction. It is a figure which shows the horizontal cross section of A direction about the circular insert shown in FIG. It is the top view which looked at the circular insert shown in FIG. 5 from the bottom face direction. It is a figure which shows other embodiment about the circular insert shown in FIG. 1, Comprising: (a) is the top view seen from the bottom face direction, (b) is a perspective view when it sees from diagonally upward of a bottom face. It is a top view which shows the structure of the insert mounting seat of the tool main body shown in FIG. It is a schematic diagram for demonstrating a state when a circular insert is mounted | worn with the insert mounting seat shown in FIG. It is sectional drawing in the BB line shown in FIG. It is sectional drawing in the CC line shown in FIG. It is sectional drawing in the DD line shown in FIG. It is a figure for demonstrating the 2nd Embodiment of this invention, Comprising: It is a top view which shows a state when a circular insert is mounted | worn to the seating surface of an insert mounting seat. It is a figure for demonstrating the 3rd Embodiment of this invention, Comprising: It is a top view which shows typically a state when a circular insert is mounted | worn to the seating surface of an insert mounting seat. It is a figure for demonstrating the 4th Embodiment of this invention, Comprising: It is a top view which shows typically a state when a circular insert is mounted | worn to the seating surface of an insert mounting seat. It is a figure for demonstrating the 5th and 6th embodiment of this invention, Comprising: It is a top view which shows a state when a circular insert is mounted | worn to the seating surface of an insert mounting seat. It is a top view which shows the structure of an insert mounting seat, in order to demonstrate the 7th Embodiment of this invention. It is a schematic diagram for demonstrating a state when a circular insert is mounted | worn with the insert mounting seat shown in FIG. FIG. 19 is a schematic diagram for explaining the state when the circular insert is mounted on the insert mounting seat shown in FIG. 18 in more detail, and (a) is a case where the tolerance of the inscribed circle of the mounted circular insert is a lower limit value. (B) shows the case where the tolerance of the inscribed circle is the median value, and (c) shows the case where the tolerance of the inscribed circle is the upper limit value.

[First Embodiment]
First, the basic configuration of the first embodiment of the cutting edge-exchangeable cutting tool of the present invention will be described with reference to FIGS. 1 is a perspective view showing a configuration example of a tool body before mounting a circular insert, FIG. 2 is a perspective view showing a state when the circular insert is mounted on the tool body shown in FIG. 1, and FIG. 3 is shown in FIG. It is a perspective view which shows the structure of an insert mounting seat.

(Tool body configuration)
As shown in FIGS. 1 to 3, the blade-tip-exchange-type cutting tool 1 according to the first embodiment has a plurality of insert mounting seats 3 formed at one tip portion of the tool body 2. FIG. 1 shows an example in which three insert mounting seats 3 are provided on the tool body 2. The insert mounting seat 3 rises upward from the seating surface 4 from the side of the tool axis O (rotation center axis) of the seating surface 4 and the seating surface 4 having a substantially circular flat shape. It is provided with two side walls 5 and 6 formed in a circular arc shape with a surface facing the seating surface 4 direction, and an insert rotation preventing portion 7 (hereinafter referred to as “first rotation preventing portion 7”). The first rotation prevention unit 7 is disposed between the side wall 5 and the side wall 6, and a restraining surface 7 a is formed on the surface of the first rotation prevention unit 7 facing the seating surface 4.

  On the seating surface 4, one second rotation preventing portion 10 is formed so as to protrude from the seating surface 4. The second anti-rotation part 10 is provided so that the part of the cutting edge used for the cutting process is arranged at an accurate indexing position when the circular insert 8 is mounted on the insert mounting seat 3. Therefore, it is formed by cutting integrally with the seating surface 4 and has a characteristic (important) configuration for the cutting edge-exchangeable cutting tool 1 of the present invention.

  The second rotation preventing portion 10 described above is formed so as to protrude from the seating surface 4 by a predetermined height and to have a predetermined length and width in a linear direction passing through the center line (O2) of the screw hole 4a. Yes. The second anti-rotation portion 10 is secured by providing the tool body 2 integrally with the seating surface 4 when the tool body 2 is manufactured by cutting using a small-diameter end mill or the like. I can do it. The specific configuration and operation of the second rotation prevention unit 10 will be described later.

  A screw hole 4a is formed in the central portion of the seat surface 4 which is substantially circular and flat. The screw hole 4 a is a screw hole for firmly fixing the circular insert 8 to the seating surface 4 using a set screw 9 as a screw member when the circular insert 8 is attached to the insert mounting seat 3.

  FIG. 2 shows a state when the circular insert 8 is mounted on the seating surface 4 of the insert mounting seat 3 of the tool body 2 shown in FIG. At this time, the set screw 9 is inserted into the screw insertion hole 15 of the circular insert 8, and acts to firmly attach the bottom surface 12 of the circular insert 8 to the seating surface 4. A plurality of types of tool bodies 2 are manufactured in advance so that the rake angle in the axial direction of the circular insert 8 attached to the seating surface 4 is a predetermined positive angle (positive) or negative angle (negative).

  As shown in FIG. 3, the side facing the seating surface 4 of the side wall 5 and the side wall 6 erected from the rear side of the seating surface 4, that is, the tool axis O side of the seating surface 4 is mounted on the insert mounting seat 3. Two wall surfaces 5a and 5b having an arc shape for restraining the outer peripheral side surface 13 serving as a flank surface of the circular insert 8 (hereinafter referred to as "arc-shaped wall surface 5a" and "arc-shaped wall surface 5b") It has. In the first embodiment of the present invention, each of the arc-shaped wall surfaces 5a and 5b is formed of a wall having a single arc shape along the outer peripheral side surface 13 of the circular insert 8 in a top view.

  The restraining surface 7a of the first rotation preventing portion 7 has a predetermined lateral length K (see FIG. 19A) in the seating surface 4 direction. When the circular insert 8 is mounted on the insert mounting seat 3, the restraining surface 7 a can be brought into contact with the outer peripheral rotation prevention surface 16 provided on the flank of the circular insert 8 described later, and the circular insert 8 is cut during machining. This is provided for the purpose of preventing the rotation. The outer peripheral rotation preventing surface 16 and the first rotation preventing portion 7 provided on the clearance surface of the circular insert 8 constitute a rotation preventing means for preventing the circular insert 8 from rotating during the cutting process.

Reference numeral 19 shown in FIGS. 1 to 3 indicates that when the circular insert 8 is mounted on the insert mounting seat 3, the circular insert 8 is positioned at the correct position of the seating surface 4, that is, the cutting edge 14 is positioned at the correct indexing position. It is a mark which becomes a protrusion for visual confirmation or a groove shape having a concave shape (hereinafter referred to as “positioning protrusion”). When the operator attaches the new circular insert 8 to the insert mounting seat 3 or because the cutting edge 14 portion of the circular insert 8 used in the previous cutting process is worn, the circular insert 8 is used in the next cutting process. When the circular insert 8 is rotated by a predetermined angle and reattached by loosening the set screw 9 to use the unused cutting edge 14 portion of the circular insert 8, the circular insert 8 is checked while visually confirming this alignment projection 19. Is fixed to the seating surface 3 with a set screw 9.
Note that minute projections or recesses for visual alignment with the alignment protrusions 19 are also formed on the upper surface 11 of the circular insert 8 at predetermined angles from the center line of the screw insertion hole 15.

(Configuration of circular insert)
Then, the basic structural example of the circular insert 8 with which the cutting-blade exchange type cutting tool 1 of this invention is mounted | worn is demonstrated based on FIGS. 4 is a side view of the circular insert 8, FIG. 5 is a perspective view when the circular insert 8 is viewed from the bottom 12 direction, and FIG. 6 is an arrow A direction parallel to the bottom 12 of the circular insert 8 shown in FIG. The horizontal sectional view in is shown. FIG. 7 shows a plan view when the circular insert 8 is viewed from the bottom surface 12 direction. The circular insert 8 shown in FIGS. 4 to 7 shows an example in which eight outer peripheral rotation prevention surfaces 16 are provided on the outer peripheral side surface 13 serving as a clearance surface of the circular insert 8.

  As shown in FIGS. 4 and 5, the circular insert 8 has a flat plate shape, and is circular in a top view from the upper surface 11 (bottom surface 12) direction, and the material thereof is made of a WC-Co based cemented carbide. . As described above, the cemented carbide circular insert 8 is formed by pressing a powder containing a fine powdered cemented carbide into a circular insert press-molded body having a predetermined size by, for example, die molding. Subsequently, this press-molded body is heated (fired) to a predetermined temperature for a predetermined time to form a circular insert having high hardness and high strength, and then finish processing is performed on necessary portions such as the cutting edge 14 and the bottom surface 12. It is manufactured by.

  As shown in FIG. 4, the circular insert 8 having a thickness h1 includes a top surface 11 which is a rake face and is circular in plan view, a bottom surface 12 which is circular in plan view at a position facing the top surface 11, and an upper surface. 11 is formed between the bottom surface 12 and the bottom surface 12 to form a conical shape, and the outer peripheral side surface 13 serving as a flank, and the entire circumference of the ridge line portion serving as a boundary between the upper surface (rake surface) 11 and the outer peripheral side surface (flank surface) 13. The formed cutting edge 14 and a screw insertion hole 15 (see FIG. 5) penetrating from the central portion of the upper surface 11 to the central portion of the bottom surface 12 are provided. The screw insertion hole 15 is a hole for fixing the circular insert 8 to the seating surface 4 with the set screw 9.

  Further, the outer peripheral side surface 13 serving as a flank surface of the circular insert 8 is provided with at least one outer peripheral rotation prevention surface 16, and further, as shown in FIG. On the other hand, a mounting index portion 17 having a concave shape (concave portion) is formed.

The outer peripheral rotation preventing surface 16 formed in the circumferential direction of the outer peripheral side surface 13 is a restraint of the first rotation preventing portion 7 provided on the insert mounting seat 3 when the circular insert 8 is mounted on the insert mounting seat 3. The circular insert 8 is provided so as to be able to come into contact with the surface 7a and prevent the circular insert 8 from rotating during cutting.
As shown in FIG. 4, the upper end surface portion 16b of the outer peripheral rotation prevention surface 16 is formed at a height h2 from the bottom surface 12, and the space between the upper end surface portion 16b and the upper surface 11 (between the height h4) is the outer peripheral side surface 13. Is to exist. The vicinity of the upper end surface portion 16b of the outer peripheral rotation prevention surface 16 has an arc shape. Further, the lower end surface portion 16 a of the outer peripheral rotation prevention surface 16 is formed so as to exist at a height h3 from the bottom surface 12, and the outer peripheral side surface 13 is interposed between the lower end surface portion 16 a and the bottom surface 12. And as for the outer periphery rotation prevention surface 16, from the circular arc-shaped part of the vicinity of the upper end surface part 16b to the lower end surface part 16a is formed in planar shape (flat surface).
In addition, the shape of the outer periphery rotation prevention surface 16 is good also as a concave shape which makes a gentle circular arc shape, as shown in the horizontal cross section of the arrow A direction shown in FIG.

  At least one outer peripheral rotation prevention surface 16 may be provided on the outer peripheral side surface 13, but a plurality of (four to eight multiple surfaces) are equally spaced along the circumferential direction of the outer peripheral side surface 13 having a conical shape. It is desirable to provide. The reason for this is that one circular insert 8 can determine the position of the cutting edge 14 as many as the number of outer peripheral rotation prevention surfaces 16 formed on the outer peripheral side surface 13 and can be reattached to the seating surface 4. This is because the region of the cutting edge 14 formed in the two circular inserts 8 can be used effectively for cutting.

  The circular insert 8 shown in FIGS. 6 and 7 shows an example in which eight outer peripheral rotation prevention surfaces 16 are formed at equal intervals in the circumferential direction of the outer peripheral side surface 13. Even in the case where the outer peripheral side face 13 is provided, the outer peripheral side face 13 having the width L1 is interposed in the circumferential direction of the outer peripheral side face 13, and the outer peripheral rotation preventing surface 16 having the width L2 in the circumferential direction of the outer peripheral side face 13 is arranged at equal intervals. Like that. Because of the presence of the outer peripheral side surface 13 having the width L1, even if eight outer peripheral rotation prevention surfaces 16 are provided, the outer peripheral side surface 13 exists between the adjacent outer peripheral rotation prevention surfaces 16, so that the strength of the circular insert 8 is increased. As a result, it is effective to ensure the security.

  As described above, the lower end surface portion 16a of all the outer peripheral rotation prevention surfaces 16 does not reach the bottom surface 12 of the circular insert 8. Similarly, the upper end surface portions 16b of all the outer peripheral rotation prevention surfaces 16 are also circular inserts 8. Is formed on the outer peripheral side surface 13 so as not to reach the upper surface 11, that is, the cutting edge 14. Thereby, the shape of the upper surface 11 and the bottom surface 12 of the circular insert 8 is ensured as a circular shape, and between the lower end surface portion 16a and the bottom surface 12 of the outer periphery rotation prevention surface 16 and between the outer periphery rotation prevention surface 16. Since the outer peripheral side surface 13 is interposed between the upper end surface portion 16b and the upper surface 11, it is possible to secure the strength of the circular insert 8, particularly the strength in the vicinity of the cutting edge 14 on the outer peripheral side surface 13 and the vicinity of the bottom surface 12 on the outer peripheral side surface 13. It becomes possible.

  Next, the configuration of the mounting index portion 17 formed on the bottom surface 12 of the circular insert 8 will be described. The mounting indexing portion 17, together with the second rotation preventing portion 10 provided on the seating surface 4, indexes the cutting edge 14 formed on the circular insert 8 to a predetermined accurate position so that the circular insert 8 is seated on the seating surface. 4 constitutes an indexing means for attaching to 4, which is characteristic for the present invention.

  As shown in FIG. 5 or FIG. 7, the mounting indexing portion 17 is formed so as to form a concentric concave portion with respect to the bottom surface 12 of the circular insert 8 around the central axis O1 of the screw insertion hole 15. The screw insertion hole 15 is located at the center of the recess. The depth (step) f1 of the recess with respect to the bottom surface 12 is about 5 to 20%, preferably about 15%, for example, 0.75 mm, of the thickness (height) h1 of the circular insert 8. If the level difference f1 exceeds 20% of h1, the strength of the circular insert 8 is insufficiently secured, and if it becomes smaller than 5%, there is a possibility that the cutting edge 14 cannot be indexed to a predetermined exact position.

As shown in FIG. 7, a boundary portion where the mounting indexing portion 17 having a concave shape with respect to the bottom surface 12 forms a bottom surface 12, that is, a stepped portion 18 (hereinafter referred to as “stepped side wall portion 18”) is formed in the screw insertion hole 15. A side wall 18a having a smooth convex curved shape in a direction away from the central axis O1 (hereinafter referred to as a “first side wall 18a having a curved shape”) and a direction smooth toward the central axis O1 of the screw insertion hole 15 are also smooth. It is comprised from the side wall 18b which makes a convex curve shape (henceforth "the 2nd side wall 18b which makes a curve shape"). The stepped side wall portion 18 of the mounting indexing portion 17 has a plurality of first side walls 18a and second side walls 18b that are curved in a plan view, and the central axis O1 of the screw insertion hole 15 is arranged in this order. As a center , it is comprised from the side wall smoothly connected.

  Note that the first side wall 18a and the second side wall 18b having the curved shape described above are formed in an arc shape, a smooth convex shape, or a smooth convex curved surface shape in a plan view. In addition, the upper end portions of the first side wall 18a and the second side wall 18b having the curved shapes, that is, the portions in contact with the bottom surface 12 are R-shaped in consideration of die-cutting during the press molding of the circular insert 8, that is, It is desirable to form this R-shaped portion as a downward inclined surface. In addition, the lower end portions of the first side wall 18a and the second side wall 18b having a curved shape, that is, the portion in contact with the bottom portion of the mounting indexing portion 17 is also formed in the above-described R shape in consideration of die cutting during press molding or the like. It is desirable to provide a configuration in which an appropriate inclined surface is provided with the bottom portion of the mounting index portion 17 or the mounting index portion 17 to connect to the R-shaped portion.

  When the boundary portion with the bottom surface 12 which is the upper end portion of the first side wall 18a having a curved shape is a side wall having an arc shape, the radius of the arc shape has r1 as shown in FIG. To do.

The circular insert 8 attached to the cutting edge-exchangeable cutting tool 1 of the present invention has the same number of the first side walls 18a having the curved shape as the number of the outer peripheral rotation prevention surfaces 16 provided on the outer peripheral side surface. 4 to 8 are provided. And if the diameter of the inscribed circle of the circular insert 8 is the same, the shape and dimension of the 1st side wall 18a which makes a curved shape will be the same or substantially the same specification.
When four first side walls 18a having a curved shape are provided, the most protruding end portion 18c of the first side wall 18a having a curved shape is spaced from the central axis O1 of the circular insert 8 by 90 ° (see FIG. 7) is arranged. Similarly, when eight first side walls 18a having a curved shape are provided, the most projecting end portions 18c of the first side wall 18a having a curved shape are spaced at 45 ° from the central axis O1 of the circular insert 8. The second side wall 18b having the curved shape is formed between the adjacent first side walls 18a having the curved shape.
The number of the first side walls 18a having the curved shape described above is the number of times that the unused cutting edge 8 can be indexed with respect to one circular insert 8, that is, it can be remounted with respect to one circular insert 8. Indicates the number of times.

  The circular insert 8 shown in FIG. 7 has an arrangement of the mounting index portion 17 on the bottom surface 12 of the circular insert 8, that is, a first side wall 18 a and a second side wall 18 b constituting the mounting index portion 17, and an outer peripheral rotation. The first embodiment of the circular insert 8 will be described with respect to the positional relationship of the arrangement with the prevention surface 16.

In a plan view showing the first embodiment of the circular insert 8 shown in FIG. 7, the first side wall having a curved shape constituting the mounting index portion 17 on the straight line S <b> 1 passing through the central axis O <b> 1 of the screw insertion hole 15. The most projecting end portion 18c of 18a (or the vicinity of the most projecting end portion 18c) and the central portion (or the vicinity of the central portion) of the outer peripheral rotation prevention surface 16 in the direction of the outer peripheral side surface 13 are disposed. It is shown that the first side wall 18a and the outer peripheral rotation prevention surface 16 having a shape are formed and arranged so as to be opposed to (opposed to) each other.
In FIG. 7, an example in which the most protruding end portion 18 c of the first side wall 18 a and the center portion of the outer peripheral rotation prevention surface 16 in the direction of the outer peripheral side surface 13 are present on the straight line S <b> 1 in plan view. Although shown, in consideration of the ease of manufacturing the circular insert 8, the most projecting end portion 18c or the like does not necessarily have to exist on the straight line S1, and may be in a position slightly away from the straight line S1.

Furthermore, as shown in FIG. 7, when another straight line passing through the central axis O1 of the screw insertion hole 15 is defined as a straight line S1a in a plan view, an arcuate shape constituting the mounting indexing portion 17 is formed on the straight line S1a. The central portion (or the vicinity of the central portion) of the outer peripheral side surface 13 between the most recessed end portion 18d (or the vicinity of the most recessed end portion 18d) of the second side wall 18b having a curved shape and the adjacent outer peripheral rotation prevention surface 16 is formed. The second side wall 18b having a curved shape and the central portion of the outer peripheral side surface 13 between the adjacent outer peripheral rotation prevention surfaces 16 are positioned so as to face each other. , Indicates that it is arranged.
In the first embodiment of the circular insert shown in FIG. 7, the central portion of the outer peripheral side surface 13 between the most recessed end portion 18d of the second side wall 18b and the adjacent outer peripheral rotation prevention surface 16 is a straight line S1a. Although the example which exists above is shown, when the ease of manufacture of the circular insert 8 is considered, the center part of the outermost side surface 13 which exists between the most recessed end part 18d and the adjacent outer periphery rotation prevention surface 16 is shown. Is not necessarily present on the straight line S1a, and may be a position in the vicinity of the straight line S1a.

FIG. 8A is a plan view of a circular insert 8a according to the second embodiment of the circular insert, and FIG. 18B is a perspective view of the circular insert 8a viewed from the bottom surface 12 in the same manner.
Compared with the circular insert 8 according to the first embodiment, the circular insert 8a has a curved shape constituting the mounting index portion 17 on a straight line S1 passing through the central axis O1 of the screw insertion hole 15 in plan view. The most recessed end portion 18d (or the vicinity of the most recessed end portion 18d) of the second side wall 18b formed and the central portion (or the vicinity of the central portion) of the outer peripheral rotation prevention surface 16 in the direction of the outer peripheral side surface 13 are disposed. The arrangement state indicates that the second side wall 18b and the outer peripheral rotation prevention surface 16 are formed and arranged so as to face each other.
8A shows an example in which the most recessed end portion 18d of the second side wall 18b and the central portion of the outer peripheral rotation prevention surface 16 in the direction of the outer peripheral side surface 13 exist on the straight line S1. Considering the ease of manufacturing the circular insert 8, the most recessed end portion 18d or the like does not necessarily have to exist on the straight line S1, and may be in a position slightly away from the straight line S1.

  Further, as shown in FIG. 8A, when another straight line passing through the central axis O1 of the screw insertion hole 15 is a straight line S1b, a curved shape constituting the mounting indexing portion 17 is formed on the straight line S1b. The center part (or the vicinity of the center part) of the outer peripheral side surface 13 between the most projecting end part 18c (or the vicinity of the most projecting end part 18c) of the first side wall 18a formed and the adjacent outer periphery rotation prevention surface 16 is disposed, In this arrangement state, the curved first side wall 18a and the central portion (or the vicinity of the central portion) of the outer peripheral side surface 13 between the adjacent outer peripheral rotation prevention surfaces 16 are positioned to face each other. Formed and arranged.

  In the second embodiment of the circular insert shown in FIG. 8A, the central portion of the outer peripheral side surface 13 between the most protruding end portion 18c of the first side wall 18a and the adjacent outer peripheral rotation prevention surface 16 is provided. Although the example which exists on the straight line S1b is shown, when the ease of manufacture of the circular insert 8 is considered, the center of the outer peripheral side surface 13 between the most projecting end part 18c and the adjacent outer periphery rotation prevention surface 16 is shown. The portion does not necessarily have to exist on the straight line S1b, and may be a position slightly away from the straight line S1b.

  In the circular insert 8 according to the first embodiment shown in FIG. 7, for example, the thickness from the most protruding end portion 18 c of the first side wall 18 a having an arcuate curved shape to the outer peripheral rotation prevention surface 16 is t 1. In the circular insert 8a according to the second embodiment shown in FIG. 8, the thickness from the most recessed end portion 18d of the second side wall 18b having an arc-shaped curved shape to the outer peripheral side surface 13 is t2, and the arc-shaped curve is formed. The thickness from the most recessed end portion 18d of the second side wall 18b having the shape to the outer peripheral rotation prevention surface 16 is t3, and the outermost side surface 13 from the most protruding end portion 18a of the first side wall 18a having an arcuate curved shape. (T2−t1)> (t3−t4) where the thickness up to t4 is t4.

  The above-mentioned "(t2-t1)> (t3-t4)" indicates that the circular insert 8a according to the second embodiment is more uneven than the circular insert 8 according to the first embodiment. It shows that the variation in thickness (thickness) from the stepped side wall portion 18 to the outer peripheral side surface 13 is small. This small variation in thickness means that the circular insert 8a according to the second embodiment has a smaller variation in the thickness (thickness) of the circular insert, which means that the circular insert It shows that 8a is more effective than the circular insert 8 for securing the strength of the circular insert.

  Note that “L3” shown in FIGS. 7 and 8A is the distance from the opening end 15a of the screw insertion hole 15 to the most protruding end 18c of the first side wall 18a having a curved shape, and “L4” is The distance from the opening end portion 15a of the screw insertion hole 15 to the most recessed end portion 18d of the second side wall 18b having a curved shape is shown, and naturally “L3> L4” is satisfied.

(Configuration of second rotation prevention unit)
Next, a configuration example of the second rotation prevention unit 10 formed on the seating surface 4 of the insert mounting seat 3 will be described with reference to FIGS. 3, 9, and 10.

  The second rotation prevention unit 10 shown in FIGS. 9 and 10 has a central axis O2 of the screw hole 4a from the opening end 4b on the seating surface 4 of the screw hole 4a formed at the center of the seating surface 4. On the seating surface 4 along a straight line S2 that is a perpendicular bisector of the line segment RQ connecting the points R and Q at both ends of the restraint surface 7a of the first rotation prevention unit 7 in plan view. Is formed so as to form a convex shape having a predetermined length L5, a width (lateral width) W, and a predetermined height from the seating surface 4 toward the outer side of the seating surface 4 (the outer side of the tool body 2). Has been.

  When the diameter of the inscribed circle of the circular insert 8 attached to the insert mounting seat 3 of the tool body 2 is the same, the number of first side walls 18a having a curved shape provided in the circular insert 8 is different. Even so, the dimensional specifications of the convex shape of the second rotation preventing unit 10 are the same or substantially the same. Thereby, even if the number of the first side walls 18a having a curved shape is different for one tool body 2, when the circular insert 8 having the same inscribed circle is mounted on the insert mounting seat 3, Since the cutting edge 14 can be accurately indexed, versatility in use of the tool body 2 occurs.

In the present invention, when the operator performs an operation of mounting the circular insert 8 on the seating surface 4, the outer peripheral rotation prevention surface 16 of the circular insert 8 is made to face the restraint surface 7 a of the first rotation prevention portion 7. In this state, any one of the plurality of curved first walls 18a provided in the mounting indexing portion 17 of the circular insert 8 is adjacent to the side wall 18a and the screw insertion hole 15. The second rotation preventing portion 10 is inserted into and engaged with the recess portion 17a (see FIG. 10) existing between the seating surface 4 and the bottom surface 12 of the circular insert 8 to thereby form a circular shape. The precise position of the cutting edge 14 with respect to the seating surface 4 of the insert 8 can be determined.
In the present invention, the second rotation preventing part 10 and the indexing part 17 for attaching the circular insert 8 are means for attaching the part of the cutting edge 14 of the circular insert 8 used for cutting to an accurate indexing position. Is provided.

  FIG. 10 shows a state in which the second anti-rotation portion 10 is inserted into and engaged with the recess portion 17a of the mounting index portion 17 provided in the circular insert 8 which is the first embodiment of the circular insert. Is shown. In FIG. 10, the hatched area indicates one depression 17a, and the mounting indexing portion 17 shown in FIG. 10 has eight depressions 17a. Installation is possible.

  In this way, the second rotation preventing portion 10 and the indexing portion 17 for mounting the circular insert 8 constitute indexing means for mounting the circular insert 8, and further, the rotation of the circular insert 8 during the cutting process. The function of the rotation prevention means for preventing a movement is also provided. The reason for this is that when the diameter of the inscribed circle of the circular insert 8 is 12 mm, the second rotation preventing unit 10 has the predetermined length L5 of about 1 to 3 mm, for example, and the predetermined width W of 1 to 3 mm, for example. When the circular insert 8 is mounted on the seating surface 4 and the exact position of the cutting edge 14 is determined by setting the height and the height to, for example, about 0.4 to 1.5 mm, the dimensional specifications described above are used. The second anti-rotation part 10 is inserted into the recessed part 17 a of the circular insert 8. Thereby, even during the cutting process, the second rotation prevention unit 10 is inserted into the recess 17a of the circular insert 8 and the both are in an engaged state, and thus the rotation of the circular insert 8 is further prevented. This is because the effect is exhibited.

The details of the configuration example of the second rotation preventing unit 10 and the state when the cutting blade 14 is indexed by mounting the circular insert 8 serving as the first embodiment of the circular insert are shown in FIGS. Will be described with reference to FIG.
As shown in FIG. 9, the second rotation preventing portion 10 is formed from the opening end portion 4 b on the seating surface 4 of the screw hole 4 a toward the outer side of the seating surface 4. Specifically, it is formed from the opening end 4b of the screw hole 4a to the point P on the seating surface 4 on the side away from the first rotation prevention unit 7 and facing the tool axis O. This point P is a vertical 2 of a line segment RQ connecting the points R and Q at both ends of the surface where the restraint surface 7a of the first rotation preventing portion 7 faces the seating surface 4 in a plan view of the insert mounting seat 3. It is formed so as to be located on a straight line S2 passing through the central axis O2 of the screw hole 4a. Further, the point P is located at the farthest portion which is the farthest distance from the central axis O2 of the screw hole 4a.

  Thus, in the plan view of the insert mounting seat 3, the second rotation preventing portion 10 is formed along the straight line S <b> 2, thereby forming a circular shape serving as the first embodiment of the circular insert having the above-described configuration. The insert 8 can be attached to the insert mounting seat 3. The reason for this is that, as described above, the circular insert 8 is formed so that the curved first side wall 18a and the outer peripheral rotation prevention surface 16 are in positions facing (opposite) each other. When the insert 8 is mounted on the insert mounting seat 3, one of the outer peripheral rotation prevention surfaces 16 provided in the circular insert 8 is brought into contact with the restraining surface 7 a of the first rotation prevention portion 7. This is because the second rotation preventing unit 10 can be inserted into the recess 17a adjacent to the first side wall 18a of the mounting indexing unit 17.

  The second rotation prevention unit 10 is formed such that the length in the direction of the straight line S2 has L5 from the opening end 4b of the screw hole 4a, and the point P is the second rotation prevention unit 10. Point P indicating the farthest distance from the central axis O2 of the screw hole 4a (hereinafter sometimes referred to as the "tip part 10a of the second rotation preventing part 10") and The vicinity is formed so as to form an arc shape having a radius r2 in plan view.

The position where the second rotation prevention unit 10 is provided on the seating surface 4 is preferably on the outer side of the seating surface 4, that is, on the side far from the first rotation prevention unit 7. The reason for this is that the formation of the seating surface 4 and the second anti-rotation portion 10 is performed by NC control using a cutting tool such as a small-diameter ball end mill, but considering the ease of this cutting, the first It is because it is desirable to form in the side far from the rotation prevention part 7.
Similarly, considering the ease of cutting, it is desirable to form the second rotation preventing portion 10 along the straight line S2 from the opening end portion 4b of the screw hole 4a.

  In the present invention, the radius r2 of the tip portion 10a forming the arc shape of the second rotation preventing portion 10 is the first arc shape of the mounting index portion 17 formed on the bottom surface 12 of the circular insert 8 described above. It is made smaller than the radius r1 of one side wall 18a. Further, the upper surface portion 10b of the second rotation preventing portion 10 is formed in a flat shape, and the space between the base portion (the portion in contact with the seating surface 4) of the second rotation preventing portion 10 and the upper surface portion 10b is gentle. It is desirable to form it so as to have an inclined surface that is inclined upward.

  FIG. 10 shows the engagement between the mounting indexing portion 17 of the circular insert 8 and the second anti-rotation portion 10 when the circular insert 8 is indexed and mounted at the correct position on the seating surface 4 for cutting. It is the figure which showed the relationship typically. In FIG. 10, the stepped side wall portion 18 of the mounting index portion 17 is indicated by a dotted line.

  As shown in FIG. 10, when the circular insert 8 is indexed and mounted at an accurate position on the seating surface 4, that is, adjacent to the first side wall 18 a having a curved shape formed in the mounting index portion 17. When the second rotation preventing portion 10 is inserted into the recess portion 17 a, one of the outer peripheral rotation preventing surfaces 16 provided in the circular insert 8 abuts on the restraining surface 7 a of the first rotation preventing portion 7. It is possible. Furthermore, in this state, between the front end portion 10a of the second rotation preventing portion 10 and the most protruding end portion 18c of the first side wall 18a of the mounting index portion 17 of the circular insert 8, the CL1 A gap is created. In addition, the radius r1 of the arc-shaped first side wall 18a is larger than the radius r2 of the arc-shaped tip portion 10a of the second rotation preventing portion 10, so that the first side wall having a curved shape is formed. A gap that is the same as or slightly larger than the clearance (CL1) is formed in the peripheral portion of 18a and the distal end portion 10a of the second rotation preventing portion 10 as well.

  In the present invention, when the circular insert 8 is indexed and mounted at the correct position on the seating surface 4, the first side wall 18 a forming the curved shape of the circular insert 8 and the second rotation preventing portion 10 of the seating surface 4 are provided. Since the above-described clearance (gap) is generated between them, the circular insert 8 can be reliably attached to the correct position of the seating surface 4 and the cutting edge 14 can be indexed. In addition, due to this clearance, even if there is a dimensional difference within a slight tolerance range in the arc shape of the curved first side wall 18a, the circular insert 8 is securely mounted at the correct position on the seating surface 4 14 can be determined.

  Further, L3, that is, the distance from the peripheral surface of the screw insertion hole 15 to the most protruding end portion 18c of the curved first side wall 18a is L3, and L4, that is, from the peripheral surface of the screw insertion hole 15 When the distance from the curved wall to the most recessed end portion 18d of the second side wall 18b is L4, naturally, “L3> L4” and L3> L5 (the second rotation preventing portion 10) Length) and L4 <L5, when the circular insert 8 is not correctly indexed to the seating surface 4, the second anti-rotation portion 10 is, for example, a curved first 2 cannot be inserted into the recess adjacent to the side wall 18b. As a result, a gap is formed between the seating surface 4 and the bottom surface 12 of the circular insert 8, and normal tightening with the set screw 9 is also possible. Disappear. As a result, it is possible to prevent the occurrence of the “inadvertent mistake” that occurs when the circular insert 8 is attached to the seating surface 4.

  FIG. 11 shows a cross-sectional view taken along the line BB in the insert mounting seat 3 shown in FIG. As shown in FIG. 11, the side wall 6 is erected so as to incline in a direction away from the seating surface 4 with an inclination angle β1 with respect to a vertical direction of the seating surface 4 forming a plane, and the standing height is T1. Has been. The height T1 is slightly smaller than the thickness h1 of the circular insert 8 to be mounted on the seating surface 4. The surface on the side of the seating surface 4 of the side wall 6 is an arcuate wall surface 6a having an arc shape in plan view as described above. Further, the other side wall 5 also has a standing height T1, the inclination angle thereof is β1 similarly to the side wall 6, and the surface on the seating surface 4 side is an arcuate wall surface 5a having an arc shape. .

The relationship between the inclination angle β1 of the side walls 5 and 6 and the inclination angle θ1 (see FIG. 4) of the outer peripheral side surface 13 of the circular insert 8 attached to the seating surface 4 also accurately positions the circular insert 8 on the seating surface 4. And become important for wearing. It is desirable to set the inclination angle β1 and the inclination angle θ1 so as to satisfy the following expression (1).
0 ≦ θ1-β1 ≦ 1.0 Equation (1)

The reason why it is desirable to set the inclination angles β1 and θ1 so as to satisfy the above formula (1) is as follows.
By setting the difference between the inclination angle θ1 of the outer peripheral side surface 13 of the circular insert 8 and the inclination angle β1 of the side walls 5 and 6 to “0 °” or “1 °” or less, both of the inclination angles are extremely close, When the circular insert 8 is mounted on the seating surface 4, it is possible to increase the length and area where the arcuate wall surfaces 5 a, 6 a of the side walls 5, 6 abut the outer peripheral side surface 13 of the circular insert 8. This is because the arcuate wall surfaces 5a and 6a can position the circular insert 8 on the seating surface 3 with high accuracy and can be mounted in a stable state. Furthermore, this makes it possible to prevent the positional displacement and rotation of the circular insert 8 during the cutting process. The inclination angles θ1 and β1 may be set to about 15 °.

  Note that the arcuate wall surfaces 5a and 6a of the side walls 5 and 6 provided at the rear end of the seating surface 4 are set by setting the inclination angle β1 value to a value smaller than the inclination angle θ1 value under the condition satisfying the above expression (1). Is in contact with the upper part of the outer peripheral side surface 13 of the circular insert 8 close to the ridgeline of the cutting edge 14, and it is further effective to prevent the positional displacement and rotation of the circular insert 8. However, when the β1 value becomes larger than the θ1 value, the arcuate wall surfaces 5a and 6a of the side walls 5 and 6 provided on the seating surface 4 come into contact with the lower part of the outer peripheral side surface 13 of the circular insert 8, and the circular insert Therefore, as described above, it is desirable to satisfy “inclination angle β1 value <inclination angle θ1”.

12 is a cross-sectional view taken along line CC (straight line S2) shown in FIG. In addition, (beta) 2 shown in FIG. 12 has shown the inclination angle which the restraint surface 7a of the 1st rotation prevention part 7 inclines with respect to the line (or surface) orthogonal to the seating surface 4. FIG.
In the state shown in FIG. 12, the second rotation preventing portion 10 formed on the seating surface 4 is inserted into the mounting indexing portion 17, and the bottom surface 12 of the circular insert 8 and the seating surface 4 are in close contact with each other. ing. In addition, a clearance (clearance) CL2 within a predetermined range value is generated between the outer peripheral rotation prevention surface 16 formed on the outer peripheral side surface 13 of the circular insert 8 and the restraint surface 7a of the first rotation prevention unit 7. Thus, the position of the restraint part 7a of the 1st rotation prevention part 7 is set. The reason why the clearance (CL2) within the predetermined value is produced when the circular insert 8 is mounted on the seating surface 4 is as follows.

  FIG. 13 is a cross-sectional view taken along the line DD shown in FIG. 10 and shows a state when the circular insert 8 is mounted on the seating surface 4 of the insert mounting seat 3 and the cutting edge 14 is indexed (set screw). 9 shows a state before tightening. In the state shown in FIG. 13, when the circular insert 8 is tightened with the set screw 9, the circular insert 8 moves a little distance (about 0.1 to 0.2 mm) in the direction of the first rotation prevention unit 7, The outer peripheral side surface 13 of the insert 8 is in close contact with the arc-shaped wall surfaces 5a and 6a of the side walls 5 and 6 having an arc shape, thereby firmly restraining the outer peripheral side surface 13 of the circular insert 8.

As described above, the circular insert 8 attached to the seating surface 4 has a small dimensional difference for each circular insert. For example, in a circular insert in which the diameter of the inscribed circle is 12.000 mm, the allowable tolerance is set to “± 0.050” (12.000 ± 0.050), and the first rotation prevention unit 7 is restrained. When the position of the surface 7a is formed based on the median value of this tolerance (12.000 mm), the CL2 value is designed to be 0.100 mm. At this time, the dimensional tolerance of the diameter of the outer peripheral side surface of the circular insert is also considered to be “± 0.050”, which is the same as the diameter tolerance of the inscribed circle.
In this case, the circular insert has an angle of about + 3.4 ° (+ indicates the clockwise direction) by tightening when the set screw at the time of mounting is a right-hand screw, and the rotation in the tightening direction is possible. Although it may occur, the influence on the mounting (mounting) accuracy when the circular insert is mounted is small.

Therefore, the position where the restraint surface 7a of the first rotation preventing portion 7 is provided on the insert mounting seat 3 is determined by taking into account the tolerance of the circular insert 8 to be mounted, and the value of the clearance (CL2) is “(upper limit). The position may be within a value of “value) − (lower limit value)”. For example, when the inscribed circle is set to “12.000 ± 0.050”, by providing the constraining surface 7a so that the clearance (CL2) has a maximum value of 0.130 mm, The rotation of the circular insert in the tightening direction can be suppressed to a maximum of 4 degrees or less.
On the other hand, for example, when the clearance (CL2) value is 0.150 mm, the rotation of the circular insert in the tightening direction is about 5 degrees, and the circular insert is mounted on the seating surface 4 in this state. When cutting is performed, the accuracy of the cutting process cannot be obtained due to the rotation of the circular insert. Therefore, the position where the restraint surface 7a of the first rotation prevention unit 7 is provided may be a position where the value of the clearance (CL2) is within the tolerance “(upper limit value) − (lower limit value)”.

The diameter of the inscribed circle of the circular insert and the value of the clearance (CL2) will be described as an example as follows.
When the 11.950 mm circular insert 8 whose inscribed circle is the lower limit of tolerance is mounted on the seating surface 4, the clearance (CL2) is 0.091 mm, and the inscribed circle is 12.000 mm circular whose tolerance is the median. When the insert 8 is mounted, the clearance (CL2) is 0.100 mm, and when the circular insert 8 having the inscribed circle of 12.050 mm, which is the upper limit of tolerance, is mounted, the clearance (CL2) is about 0.123 mm. Become.

  Even if the circular insert 8 is mounted on the seating surface 4 and the clearance (CL2) of, for example, about 0.123 mm is generated before processing, the circular insert 8 is connected to the set screw 9 in the present invention. Since it is restrained by the arc-shaped wall surfaces 5a, 6a of the side walls 5, 6, it is mounted on the seating surface 4 in a stable state and with high positional accuracy. Thereby, rotation of the circular insert 8 can be prevented during cutting. Furthermore, as described above, the second rotation prevention unit 10 can prevent the circular insert 8 from rotating, so that the circular insert 8 can be more reliably prevented from rotating during the cutting process. It becomes like this.

(Characteristics of circular insert shape)
Then, about the circular insert 8 (8a), the feature on shapes, such as the arrangement position of the outer periphery rotation prevention surface 16 currently formed in the outer peripheral side surface 13, is demonstrated. In this description, the circular insert 8 which is the first embodiment of the circular insert will be described as an example, but the same applies to the circular insert 8a which is the second embodiment.

The outer peripheral rotation prevention surface 16 formed on the outer peripheral side surface 13 of the circular insert 8 has, for example, a planar shape recessed with respect to the outer peripheral side surface 13 as shown in FIG. Can be formed at the time of forming the circular insert 8 with cemented carbide powder.
In FIG. 7, eight outer peripheral rotation prevention surfaces 16 are formed at equal intervals in the circumferential direction of the outer peripheral side surface 13 of the circular insert 8 through a portion of the outer peripheral side surface 13 having a predetermined length L1. An example is shown. As described above, when a plurality of outer peripheral rotation prevention surfaces 16 are provided in the circumferential direction of the outer peripheral side surface 13 of the circular insert 8, the adjacent outer peripheral rotation prevention surfaces 16 do not intersect with each other and the outer periphery has a length L <b> 1. It is desirable to form the rotation preventing surfaces 16 at regular intervals through the side surface 13.

  Further, the position of the outer peripheral rotation prevention surface 16 formed on the outer peripheral side surface 13 of the circular insert 8 is such that the lower end portion 16a of the outer peripheral rotation prevention surface 16 has a height h3 from the bottom surface 12 of the circular insert 8 as shown in FIG. Further, the upper end portion 16b of the outer peripheral rotation preventing surface 16 is disposed below the upper surface 11 of the circular insert 8 at a distance of a height h4. That is, all the outer peripheral rotation prevention surfaces 16 have their lower end portions 16 a not reaching the bottom surface 12 of the circular insert 8, and similarly, the upper end portions 16 b of all the outer peripheral rotation prevention surfaces 16 are also the upper surface 11 of the circular insert 8. That is, the outer peripheral side surface 13 is formed so as not to reach the cutting edge 14. Thereby, since the shape of the upper surface 11 and the bottom surface 12 of the circular insert 8 is ensured to be a circular shape, the strength is not lowered, and the strength of the outer peripheral side surface 13 in the vicinity of the upper surface 11 and the bottom surface 12 is also ensured. become.

Here, as shown in FIG. 4, the thickness of the circular insert 8 is h1 (mm), the height from the bottom surface 12 to the upper end portion 16b of the outer peripheral rotation prevention surface 16 is h2 (mm), and the bottom surface 12 is the outer periphery. When the height to the lower end portion 16a of the rotation preventing surface 16 is set to h3 (mm), the circular insert 8 attached to the cutting edge-exchangeable cutting tool of the present invention has the following formula (2) for h1 and h2. It is desirable to form the outer peripheral rotation prevention surface 16 on the outer peripheral side surface 13 so as to satisfy the above.
(1/2) h1 ≦ h2 ≦ (2/3) h1 Expression (2)

In the above formula (2), by defining the height h2 so as to satisfy “h2 ≦ (2/3) h1”, the upper surface 11 of the circular insert 8 reaches the upper end portion 16b of the outer peripheral rotation prevention surface 16. Since the height h4 up to (1/3) h1 can be ensured, the cutting edge strength of the cutting edge 14 can be sufficiently maintained.
Further, by defining the height h2 so as to satisfy “(1/2) h1 ≦ h2”, the height of the outer peripheral rotation preventing surface 16, that is, the length of the circular insert 8 in the thickness h1 direction is sufficient. Therefore, it is possible to ensure a sufficient length for abutting the restraining surface 7a of the first rotation preventing portion 7 provided on the tool body 2 to the outer peripheral rotation preventing surface 16 of the circular insert 8 during the cutting process. Thus, the effect of preventing the circular insert 8 from rotating can be obtained.

Further, in the circular insert 8, the height h3 from the bottom surface 12 to the lower end portion 16a of the outer peripheral rotation prevention surface 16 satisfies the following expression (3), so that the lower end portion 16a of the outer peripheral rotation prevention surface 16 is satisfied. It is desirable to form the position on the outer peripheral side surface 13.
(1/10) h1 ≦ h3 ≦ (1/3) h1 (1)

In the above formula (3), by defining the height h3 to satisfy “(1/10) h1 ≦ h3”, the h3 value is not less than (1/10) h1 from the bottom surface 12 of the circular insert 8. Therefore, it is necessary to secure sufficient strength of the bottom surface 12 forming a circular shape as a fixing surface for attaching the circular insert 4 to the seating surface 4 of the insert mounting seat 3 and the outer peripheral side surface 13 in the vicinity of the bottom surface 12. Can do.
Further, when the bottom surface 12 is seated on the seating surface 3, a sufficient contact area (fixed area) can be secured, which is effective in preventing the circular insert 8 from rotating. Further, by defining the height h3 to satisfy “h3 ≦ (1/3) h1”, the height from the bottom surface 12 to the lower end portion 16a of the outer peripheral rotation prevention surface 16 is limited, and the outer peripheral rotation is prevented. The restraint surface 7a of the first rotation preventing portion 7 described above is used as the outer peripheral rotation preventing surface of the circular insert 8 while suppressing a decrease in the height of the surface 16, that is, the length of the circular insert 8 in the thickness h1 direction. A sufficient length to be brought into contact with 16 can be secured.

  Further, in the cutting edge-exchangeable cutting tool of the present invention, as shown in FIG. 4, the inclination angle of the outer peripheral side surface 13 is θ1, that is, the angle formed by the line segment perpendicular to the upper surface 11 of the circular insert 8 and the outer peripheral side surface 13. Assuming that θ1 is θ2, the inclination angle of the outer peripheral rotation prevention surface 16 is θ2, that is, the angle formed by the line segment perpendicular to the upper surface 11 of the circular insert 8 and the outer peripheral rotation prevention surface 16 is θ2, the h3 value is ( 1/10) As h1 ≦ h3, it is preferable to satisfy 0 <θ2 <θ1 in order to sufficiently secure the thickness from the bottom surface 12 to the lower end portion 16a of the rotation preventing surface 16.

  Thus, as described above, the circular insert 8 used in the cutting edge-exchangeable cutting tool of the present invention has the outer peripheral rotation prevention surface 16 provided on the outer peripheral side surface 13 of the circular insert 8, and the lower end portion 16 a is positioned at the bottom surface 12. (1/10) h1 or more, and the position of the upper end portion 16b is within the range of (2/3) h1 or less from the bottom surface 12, and further, the position of the lower end portion 16b of the outer peripheral rotation prevention surface 16 Is set to be (1/3) h1 or less from the bottom surface 12, and the position of the upper end portion 16b is provided to be within a range of (2/3) h1 or less from the bottom surface 12.

  In addition, the value of the width L2 (see FIG. 7) formed in the circumferential direction of the outer peripheral side surface 13 by the outer peripheral rotation prevention surface 16 provided on the outer peripheral side surface 13 of the circular insert 8 is determined by attaching the circular insert 8 to the insert mounting seat 3. In order to obtain an effective anti-rotation effect of the circular insert 8 by bringing the constraining surface 7a of the first anti-rotation portion 7 provided on the tool body 2 into contact with each other when cutting is performed. In consideration of the strength of the anti-rotation portion 8 according to the size of 8 (the size of the inscribed circle), its thickness h1, and the number of the outer peripheral anti-rotation surfaces 16 (the number of anti-rotation surfaces), Try to set it properly.

The number of outer peripheral rotation prevention surfaces 16 provided on the outer peripheral side surface 13 of the circular insert 8 (8a) is preferably about 4 to 8 according to the size of the inscribed circle of the circular insert 8. Further, the same number of the first side walls 18a and the second side walls 18b having the above-described curved shape are provided as the number of the outer peripheral rotation prevention surfaces 16.
In this way, by providing a plurality of outer peripheral rotation prevention surfaces 16, for example, when the cumulative time of cutting reaches a predetermined time value, the set screw 9 is loosened so that the circular insert 8 is attached to the seating surface 4. The circular insert 8 is again mounted on the seating surface 4 with the set screw 9 and the unused cutting edge 14 can be used for the next cutting. At this time, the constraining surface 7a of the first rotation preventing portion 7 of the tool body 2 can come into contact with the outer periphery rotation preventing surface 16 corresponding to the cutting edge 14 portion used this time during the cutting process. The effect which prevents rotation of the circular insert 8 in inside is exhibited.

[Second Embodiment]
Then, 2nd Embodiment of the blade-tip-exchange-type cutting tool of this invention is described with reference to FIG. In the tip-replaceable cutting tool according to the first embodiment described above, the circular insert 8 serving as the first embodiment of the circular insert shown in FIG. It is configured so that it can be attached to the camera. The circular insert 8 according to the first embodiment is formed so that the curved first side wall 18a and the outer peripheral rotation prevention surface 16 face each other (opposite). When the circular insert 8 is mounted on the insert mounting seat 3, one of the outer peripheral side surfaces 13 formed on the circular insert 8 faces toward the restraint surface a of the first rotation preventing portion 7, and the seating surface 4 had to be fixed with a set screw 9. For this reason, as shown in FIG. 9 (FIG. 10), the second rotation preventing unit 10 is perpendicular to the line segment RQ connecting the points R and Q at both ends of the surface where the constraining surface 7 a faces the seating surface 4. The bisector is provided along a straight line S2 passing through the central axis O1 of the screw insertion hole 15.

  On the other hand, in order to allow the circular insert 8a, which is the second embodiment of the circular insert shown in FIG. 8 (a), to be mounted on the insert mounting seat 3, the cutting edge portion can be accurately positioned. As shown in FIG. 14, the second rotation preventing portion 10 formed on the seating surface 4 has a clockwise rotation direction R1 or a counterclockwise rotation direction R2 with respect to the straight line S2 in a plan view of the seating surface 4. Must be formed at a position rotated by an angle α.

  The reason for this is that, as shown in FIG. 8 (a), the circular insert 8a is formed so that the second side wall 18b and the outer peripheral rotation prevention surface 16 are positioned opposite each other. Therefore, when the circular insert 8a is mounted on the insert mounting seat 3, as described above, one of the outer peripheral side surfaces 13 formed on the circular insert 8a is set in the direction of the restraint surface a of the first rotation preventing portion 7. In this state, the first side wall 18a having a curved shape formed in the mounting index portion 17 on the bottom surface of the circular insert 8a is on a straight line S2 as shown in FIG. Is not present, and is present at a position rotated from the straight line S2 by the angle α in the clockwise rotation direction R1 or the counterclockwise rotation direction R2. For this reason, it is necessary to make the position which provides the 2nd rotation prevention part 10 on the seating surface 4 differ from the position shown in FIG.

In the example shown in FIG. 14, the second rotation prevention unit 10 is formed along a straight line D2 that intersects the straight line S2 and forms an angle α in the counterclockwise rotation direction R2 in the plan view of the seating surface 4. . When the circular insert 8a is mounted on the insert mounting seat 3, the second rotation preventing portion 10 is inserted into the recessed portion 17a adjacent to the first side wall 18a forming the curved shape of the circular insert 8a. 2 shows a case where a clearance is generated between the rotation preventing portion 10 and the recess portion 17a. The straight line D2 is preferably a straight line passing through the central axis O2 of the screw hole 4a.
Further, in the second embodiment, as shown in FIG. 14, in the plan view of the seating surface 4, the second rotation preventing unit 10 intersects the straight line S2 and forms an angle α in the clockwise rotation direction R1. It is formed along the straight line D1. When the circular insert 8a is mounted on the insert mounting seat 3, the second rotation prevention is provided in the recessed portion 17a adjacent to the first side wall 18a forming the curved shape of the circular insert 8a located along the straight line D1. The part 10 may be inserted. The straight line D1 is also preferably a straight line passing through the central axis O2 of the screw hole 4a.

In the second embodiment described above, the angle (intersection angle) α at which the straight line S2 intersects the straight line D1 or the straight line D2 is the first side wall 18a (outer peripheral rotation prevention surface 16) having a curved shape provided in the circular insert 8a. ), For example, 8, 6, 5, and 4.
When the number of first side walls 18a having a curved shape provided in the circular insert 8a is “n”, the intersection angle α can be set to a value satisfying the following expression.
α = 360 ° / (2 × n), where n is an integer of 4 ≦ n ≦ 8 From the above formula, for example, when n is 4, the crossing angle α is 45 °, and when n is 8 Set the intersection angle α to 22.5 °.

In cutting edge-exchangeable cutting tools equipped with circular inserts, the rake angle in the axial direction of the circular insert with respect to the tool body is “positive” or “negative” depending on the cutting application. A tool main body to be mounted on is prepared. When the circular insert is mounted on the insert mounting seat of the tool body so that the axial rake angle is “positive”, the cutting resistance generated during the cutting process is a plan view with respect to the upper surface 11 of the circular insert. A force is generated to rotate the circular insert in the counterclockwise direction.
On the other hand, when a circular insert is mounted on the insert mounting seat so that the rake angle in the axial direction is “negative”, the cutting resistance generated during the cutting process is the same in the clockwise direction in plan view. A force is generated to rotate the lens.

  On the other hand, as described above, the circular insert 8 (8a) made of cemented carbide has a variation in the amount of shrinkage that occurs when the molded body of this circular insert is fired. Therefore, when the circular insert 8 or the like is mounted on the insert mounting seat 3, the clearance (CL2) formed by the first rotation preventing portion 7 provided on the insert mounting seat 3 and the outer circumferential rotation preventing surface 16 of the circular insert 8 is formed. In consideration of the clearance (CL1) formed between the second rotation preventing portion 10 formed on the seating surface 4 and the arcuate side wall 18a of the mounting index portion 18 provided on the bottom surface 12 of the circular insert 8 when the insert is mounted. When the arrangement position of the second anti-rotation portion 10 formed on the seating surface 4 is also appropriate, the above-described anti-rotation function of the circular insert and the cutting edge 14 formed on the circular insert can be accurately determined. Thus, it is possible to more reliably realize the indexing function for indexing to a proper position and mounting the circular insert.

[Third Embodiment]
Then, 3rd Embodiment of the blade-tip-exchange-type cutting tool of this invention is described based on FIG. In the third embodiment, the second rotation preventing portion 10 formed on the seating surface 4 intersects the straight line S2 in the plan view of the seating surface 4 with respect to the first embodiment shown in FIG. In the example shown, the line is formed along a straight line S3 that forms an angle α1 with the straight line S2 in the counterclockwise direction (R2). Further, a point P that is the farthest portion of the second rotation preventing unit 10 is provided on the straight line S3.
A straight line S2 shown in FIG. 15 is a straight line S2 that is a perpendicular bisector of the line segment RQ shown in FIG. 9 (FIG. 10) described in the first embodiment, and the reference numeral “18” shown by a dotted line is A stepped side wall portion 18 in the mounting index portion 17 formed on the bottom surface 12 of the circular insert 8, and the top surface 11 of the circular insert 8 is not shown. The straight line S3 is preferably a straight line passing through the central axis O2 of the screw hole 4a.

In the example shown in FIG. 15, the outer peripheral side surface 14 of the circular insert 8 is the side surface 5 of the insert mounting seat 3 in the initial state where the circular insert 8 is indexed and mounted on the insert mounting seat 3. , 6 are brought into contact with and restrained by the arcuate wall surfaces 5a and 6b, and one of the outer peripheral rotation prevention surfaces 16 can be brought into contact with the restriction surface 7a of the first rotation prevention portion 7 in the vicinity thereof. It is in a state. Further, the second rotation preventing portion 10 formed on the seating surface 4 is inserted into any one of the recessed portions 17 a formed on the bottom surface 12 of the circular insert 8. At this time, the second rotation preventing unit 10 is formed along the straight line S3 rotated in the counterclockwise rotation direction (R1) by an angle α1 with respect to the straight line S2 from the central axis O2 of the screw hole 4a. Therefore, the clearance formed by the end portion on the R1 direction side of the second rotation preventing portion 10 with the curved first side wall 18a is smaller than the clearance shown in FIG.
Thereby, in 3rd Embodiment, when an operator remounts the circular insert 8, about the operation which inserts the 2nd rotation prevention part 10 in the hollow part 17a of the circular insert 8, an above-described clearance is set. Due to the small size, there is an effect of urging the operator to avoid the “inadvertent mistake” at the time of wearing.

[Fourth Embodiment]
Then, 4th Embodiment of the blade-tip-exchange-type cutting tool of this invention is described based on FIG. In the fourth embodiment, the second rotation preventing portion 10 formed on the seating surface 4 intersects the straight line S2 with respect to the third embodiment shown in FIG. When viewed, an example is shown that is formed along a straight line S4 that forms an angle α2 with the straight line S2 in the clockwise direction (R1). Further, a point P that is the farthest portion of the second rotation preventing unit 10 is provided on the straight line S4.
A straight line S2 shown in FIG. 16 indicates a straight line S2 that is a perpendicular bisector of the line segment RQ shown in FIG. 9 (FIG. 10) described in the first embodiment, and the reference numeral “18” indicated by a dotted line is A stepped side wall portion 18 in the mounting index portion 17 formed on the bottom surface 12 of the circular insert 8, and the top surface 11 of the circular insert 8 is not shown. The straight line S3 is preferably a straight line passing through the central axis O2 of the screw hole 4a.

  In the fourth embodiment shown in FIG. 16, in the initial state where the cutting edge 14 of the circular insert 8 is indexed and mounted on the insert mounting seat 3, the outer peripheral side surface 14 of the circular insert 8 is the side surface 5 of the insert mounting seat 3. , 6 in contact with the arcuate wall surfaces 5a, 6a, the second anti-rotation portion 10 of the seating surface 4 is inserted into one of the recessed portions 17a formed on the bottom surface 12 of the circular insert 8. ing. At this time, the second rotation preventing unit 10 is on a straight line that intersects the straight line S2 and passes through the central axis O2 of the screw hole 4a, and rotates in the clockwise direction (R1) by the straight line S2 and the angle α2. It is formed along the straight line S4.

In the fourth embodiment shown in FIG. 16, the second rotation preventing unit 10 is rotated in the clockwise direction (R1) by the angle α2 from the central axis O2 of the screw hole 4a with respect to the straight line S2. Since the end portion on the (R1) direction side of the second rotation prevention unit 10 is formed along the upper side, the clearance formed with the curved first side wall 18a is smaller than the clearance shown in FIG. .
Thereby, when an operator remounts the circular insert 8, the operation of inserting the second rotation prevention unit 10 into the recess 17a of the circular insert 8 is the same as in the third embodiment described above. There is an effect of urging the worker not to make an "inadvertent mistake".

  In the third and fourth embodiments described above, the values of the angle α1 and the angle α2 are desirably set to 2 ° to 10 °. The reason for this is as follows.

  The first reason is that the clearances (CL1) value formed by the second rotation prevention unit 10 shown in FIG. 10 and the curved first side wall 18a by setting the angles α1 and α2 to 10 ° or less, etc. This is because it is possible to avoid setting the value larger than necessary. If the value of the clearance (CL1) or the like is set larger than necessary, the size of the second rotation prevention unit 10 is reduced, which causes a problem that it is difficult to ensure the strength of the second rotation prevention unit 10. End up. On the other hand, by setting the clearance (CL1) value to be moderately small, the size of the second rotation preventing unit 10 can be designed to be large, which is advantageous for securing the strength.

  The second reason is that when the cutting edge 14 of the circular insert 8 (8a) is indexed by setting it to 2 ° or more, the first side wall 18a having a curved shape with the second rotation preventing portion 10 is provided. Therefore, it is possible to appropriately secure a dimensional margin of clearance (to make the clearance as small as possible). This prevents an “inadvertent mistake” from occurring in the operation of inserting the second rotation prevention unit 10 into the recessed portion 17a of the circular insert 8 when the operator performs an indexing operation for remounting the circular insert 8. This has the effect of calling attention.

[Fifth and sixth embodiments]
Next, fifth and sixth embodiments of the present invention will be described with reference to FIG. These 5th and 6th embodiment is the blade-tip-exchange-type cutting tool which improved further about 2nd Embodiment shown in FIG.

In the fifth embodiment, the second rotation preventing portion 10 formed on the seating surface 4 intersects the straight line D2 shown in FIG. 17 (the straight line D2 shown in FIG. 14) in the plan view of the seating surface 4, and An example is shown in which it is formed along a straight line S6 that forms an angle α1 with the straight line D2 in the clockwise direction (R2). Further, a point P that is the farthest portion of the second rotation preventing unit 10 is provided on the straight line S6.
Note that the straight line D1 and the straight line D2 shown in FIG. 17 are the same as the straight line D1 and the straight line D2 shown in FIG. 14, intersect the straight line S2, and have an angle with the clockwise direction (R1) or the counterclockwise direction (R2). It is a straight line forming α. Further, the angle α is set by “α = 360 ° / (2 × n)” when the number of the first side walls 18a having the curved shape provided in the circular insert 8a as described above is “n”. Value.

  In the fifth embodiment, in the initial state in which the cutting edge 14 of the circular insert 8 a is indexed and attached to the insert mounting seat 3, the outer peripheral side surface 14 of the circular insert 8 a is the side surface 5, 6 of the insert mounting seat 3. The arcuate wall surfaces 5a and 6b are in contact with and restrained, and one of the outer peripheral rotation prevention surfaces 16 is in contact with the restraint surface 7a of the first rotation prevention unit 7 and is in contact with the arcuate wall surfaces 5a and 6b. ing. Further, the second rotation preventing portion 10 formed on the seating surface 4 is inserted into any one of the recessed portions 17a formed on the bottom surface 12 of the circular insert 8a. At this time, the second rotation preventing unit 10 is formed along a straight line S6 rotated in the counterclockwise direction (R1) by an angle α1 with respect to the straight line D2 from the central axis O2 of the screw hole 4a. Therefore, the clearance that the counterclockwise rotation direction (R1) side of the second rotation prevention unit 10 forms with the curved first side wall 18a is smaller than the clearance shown in FIG.

  Thereby, in 5th Embodiment, when an operator remounts the circular insert 8a, about the operation which inserts the 2nd rotation prevention part 10 in the hollow part 17a of the circular insert 8a, it is 2nd mentioned above. By reducing the clearance between the rotation preventing portion 10 and the curved first side wall 18a, an effect of urging the operator to avoid the “inadvertent mistake” at the time of mounting described above can be obtained. Arise.

In the fifth embodiment, the second rotation preventing portion 10 formed on the seating surface 4 intersects the straight line D2 shown in FIG. 17 in a plan view of the seating surface 4, and the clockwise rotation direction (R1 ) May be formed along a straight line S5 that forms an angle α1 with the straight line D2. Further, a point P that is the farthest portion of the second rotation preventing unit 10 is provided on the straight line S5. Also in this embodiment, the clearance between the second rotation preventing portion 10 described above and the end portion on the clockwise direction (R1) side of the curved first side wall 18a is reduced. On the other hand, there is an effect that attention can be urged so that an “inadvertent mistake” at the time of wearing does not occur.
The angle α1 described above is set in the range of 2 ° to 10 °, similarly to the angle α1 shown in FIG.

In the sixth embodiment, as shown in FIG. 17, the second rotation preventing portion 10 formed on the seating surface 4 intersects the straight line D1 (straight line D1 shown in FIG. 14) in the plan view of the seating surface 4. And formed along the straight line S7 that forms an angle α2 with the straight line D1 in the clockwise direction (R1). Note that FIG. 17 does not show the second rotation prevention unit 10 formed along the straight line S7. In this embodiment, the second rotation preventing unit 10 may be formed along a straight line S8 that intersects the straight line D1 and forms an angle α2 with the straight line D1 in the counterclockwise rotation direction (R2).
Also in the sixth embodiment, since the clearance between the second rotation preventing portion 10 and the curved first side wall 18a is reduced, an “inadvertent mistake” at the time of mounting on the operator. As a result, it is possible to call attention so as not to occur.
The angle α2 described above is set in the range of 2 ° to 10 °, similarly to the angle α2 shown in FIG.

[Seventh Embodiment]
Next, a seventh embodiment of the present invention will be described based on FIGS. In the seventh embodiment, when the circular insert 8 is mounted on the insert mounting seat 3, seating of the side walls 5, 6 provided standing on the insert mounting seat 3 in order to restrain the outer peripheral side surface 13 of the circular insert 8. The configuration of the arcuate wall surfaces 5a and 6b formed on the surface facing the surface 4 is improved.

  FIG. 18 is a perspective view showing a configuration according to the seventh embodiment of the present invention. This seventh embodiment is the same as the insert mounting seat 3 provided in the first embodiment shown in FIG. In addition, each of the side wall 5 and the side wall 6 is provided with a side wall 5 on one end side of the first rotation prevention unit 7 and a side wall 6 on the other end side. The side wall 5 is composed of two arc-shaped first and second side wall surfaces 5a1 and 5a2, and the side wall 6 is also composed of two arc-shaped third and fourth side wall surfaces 6a1 and 6a2. Side walls close to the first rotation preventing unit 7 are defined as a first side wall surface 5a1 and a third side wall surface 6a1.

  Further, the first to fourth side wall surfaces 5a1, 5a2, 6a1, and 6a2 are also made to satisfy the conditions defined by the above-described formula (1). That is, the first to fourth side wall surfaces 5 a 1, 5 a 2, 6 a 1, 6 a 2 are erected with an inclination angle β 1 in the direction of the tool axis O with respect to a line segment orthogonal to the seating surface 4, and are attached to the seating surface 4. When the inclination angle of the outer peripheral side surface 13 of the circular insert 8 is θ1, (θ1−β1) satisfies the above formula (1).

  The insert mounting seat 3 shown in FIG. 18 is an example in which the second rotation preventing portion 10 formed on the seating surface 3 is formed in a direction inclined with respect to the straight line S2 shown in FIG. Although the seating surface 3 on which the circular insert 8a according to the second embodiment described above is mounted is shown, the direct seating surface 3 may be configured to mount the circular insert 8 according to the first embodiment. In the following description, the case where the circular insert 8 is mounted on the insert mounting seat 3 will be described as an example.

  FIG. 19A is a diagram schematically showing an insert mounting seat and a state when the circular insert 8 is mounted on the insert mounting seat, and FIG. 19B shows the seventh embodiment. ) Is a partially enlarged view.

  As shown in FIGS. 18 and 19, the side wall 5 has a first side wall surface 5a1 having an arc shape and a second side wall surface 5a2 having the same arc shape on the side of the seating surface 4 (see FIG. 19A). The structure is integrated through a step portion 5b shown in FIG. Similarly, the side wall 6 has a step portion 6b indicated by a circle mark (see FIG. 19A) on the seating surface 4 side of the third side wall surface 6a1 having an arc shape and the fourth side wall surface 6a2 having the same arc shape. It is set as the structure integrated via. In FIG. 19A, the diameter of the first side wall surface 5a1 having an arc shape is d1, the diameter of the second side wall surface 5a2 having an arc shape is d2, and the diameter of the third side wall surface 6a1 having an arc shape is The diameter of d4 and the fourth side wall surface 6a4 having an arc shape is shown as d2. The stepped portion 5b is provided at an intermediate position of the side wall 5 when viewed from above, that is, at an intermediate position between the first and second side wall surfaces 5a1 and 5a2. The position of the step portion 6b is also provided at an intermediate position between the third side wall surface 6a1 and the fourth side wall surface 6a2.

  As described above, the surfaces of the side wall 5 and the side wall 6 facing the seating surface 3 are formed by integrating the side walls 5a1 and 5a2 and 6a1 and 6a2 having two different diameters in plan view through the step portions 5b and 6b. The inner wall surface having a circular arc shape is provided.

  In FIG. 19B, the stepped portions 5b and 6b are shown as being linearly formed in the center direction of the circular insert 8, but may be a stepped portion having a gentle R shape. Further, the stepped portions 5b and 6b may not be configured with steps, but may have a concave shape, for example, a groove having a fine U shape or an arc shape, but the first to fourth side wall surfaces 5a1, 5a2, 6a1, and 6a2 are configured independently through stepped portions 5b and 6b.

  In the seventh embodiment, the diameters d1 and d2 of the arc shapes of the first to fourth side wall surfaces 5a1, 5a2, 6a1, and 6a2 are set as described in (Feature 1) and (Feature 2) below. It is characterized by doing.

(Feature 1)
The diameter of the arc shape of the first side wall surface 51a and the diameter of the arc shape of the third side wall surface 6a1 are set to the same diameter d1, and this diameter d1 is the diameter d0 of the circular insert 8, that is, the diameter of the upper surface 10 ( It is set to be the same as the diameter of the inscribed circle and the median tolerance.

(Feature 2)
The diameter of the arc shape of the second side wall surface 5a2 and the diameter of the arc shape of the fourth side wall surface 6a2 are set to the same diameter d2, and the diameter d2 is larger than the diameter d1 (d0). It is set. The (d2-d1) value is the same as or close to the value of the diameter of the inscribed circle of the circular insert to be attached ((tolerance upper limit value)-(median value of tolerance)).

  As described in (Feature 1) and (Feature 2), the arc-shaped diameters d1 and d2 of the first to fourth side wall surfaces 5a1, 5a2, 6a1, and 6a2 are set to appropriate values as described above. Even if there is a dimensional difference (dimension variation) within a minute tolerance range in the diameter of the inscribed circle inevitably generated in the circular insert 8 mounted on the insert mounting seat 3 or the circumferential diameter of the outer peripheral side surface 13. Each insert 8 can be attached to the insert mounting seat 3 of the tool body 2 in a stable state with high accuracy.

  In the seventh embodiment, an operation of attaching the circular insert 8 to the insert mounting seat 3 with the side wall 5 and the side wall 6 in a stable and highly accurate manner will be described with reference to FIG. In this description, the specification of the diameter of the inscribed circle (upper surface 11) of the circular insert 8 is 12.000 mm, and the tolerance of the dimension of the inscribed circle is set to “± 0.050 mm” as an example. I will explain.

  (1) For example, when the circular insert 8 (the diameter of the inscribed circle is 11.950 mm) whose tolerance of the inscribed circle is the lower limit value is attached to the seating surface 4, the second side wall surface 5a2 having an arc shape and Since the diameter d2 of the fourth side wall surface 6a2 is larger than the diameter of the mounted circular insert 8, the outer peripheral side surface 13 of the circular insert 8 is formed on the first side wall surface 5a1 and the third side as shown in FIG. In a state of contact in the vicinity of the point P1 of the wall surface 6a1, the positioning is performed on the seating surface 4 with high accuracy. In this state, the circular insert 8 is fixed on the seating surface 4 by a set screw 9. This contact at the point P1 will be referred to as an “internal hit state”. In this inner contact state, although there is a concern about a slight positional deviation when the circular insert 8 is positioned on the seating surface 4, the circular insert 8 has a first position when the circular insert 8 is fixed by tightening with the set screw 9. Although a pressing force in the direction of the rotation preventing portion 7 acts, the outer peripheral side surface 13 of the circular insert 8 does not deform the first side wall surface 5a1 and the third side wall surface 6a1.

  (2) For example, when a circular insert 8 having a median tolerance of an inscribed circle (the diameter of the inscribed circle is 12.000 mm) is attached to the seating surface 4, the second side wall surface 5a2 and the fourth Since the diameter d2 of the side wall surface 6a is larger than the diameter of the mounted circular insert 8, the outer peripheral side surface 13 of the circular insert 8 has a diameter equal to the inscribed circle of the circular insert 8 as shown in FIG. The first side wall surface 5a1 and the third side wall surface 6a1 having a contact with each other in the range of P2 are accurately positioned on the seating surface 4, and the circular insert 8 is fixed by the set screw 9 in this state. become. This state is the most preferable wearing state.

  (3) For example, when the circular insert 8 (the diameter of the inscribed circle is 12.050 mm) whose tolerance of the inscribed circle is the upper limit is attached to the seating surface 4, the first side wall surface 5a1 and the third Since the diameter d1 of the side wall surface 6a1 is larger than the diameter of the mounted circular insert 8, the outer peripheral side surface 13 of the circular insert 8 is the same at two points P3 and P4, respectively, as shown in FIG. 20 (c). In the contacted state, it is accurately positioned on the seating surface 4, and in this state, the circular insert 8 is fixed by the set screw 9.

  The point P3 is the first side wall surface 5a1 (third side) than the step portion 5b (6b) between the first side wall surface 5a1 (third side wall surface 6a1) and the second side wall surface 5a2 (fourth side wall surface 6a2). It is located on the side of the wall surface 6a1) and is at the end of the first side wall surface 5a1 (third side wall surface 6a1) (on the second side wall surface 5a2 side or the fourth side wall surface 6a2 side) or in the vicinity of this end portion. The point P4 is at or near the ends of the second side wall surface 5a2 and the fourth side wall surface 6a2. This contact at P4 will be referred to as an “outside contact state”. In this outer contact state, when the circular insert 8 is positioned on the seating surface 4, the effect of preventing rotation effectively works. However, when the circular insert 8 is fastened and fixed by the set screw 9, the second side wall surface 5a2 and the fourth side wall surface 6a2 may be slightly deformed by pressing the circular insert 8 toward the first rotation prevention portion 7. There is.

  Thus, in the seventh embodiment of the present invention, the diameter d1 of the first side wall surface 5a1 and the third side wall surface 6a1 is set to the specification of the inscribed circle of the circular insert 8 to be mounted, that is, the median value of tolerance d0. And the diameter d2 of the second side wall surface 5a2 and the fourth side wall surface 6a2 is larger than the median value (d0) of the inscribed circle tolerance of the circular insert to be mounted and within the upper limit value of the tolerance. By setting the value close to the upper limit value, for example, in the above example, to a value “about 0.050 mm larger than the median tolerance (d0)”, the circular insert 8 can be mounted and fixed to the seating surface 4 with high accuracy. become able to.

  In the cutting edge exchangeable cutting tool according to the first to seventh embodiments of the present invention described above, the seating surface 4 including the second rotation preventing portion 10 of the tool body 2 and the side walls 5 and 6 are provided. At least one of the arcuate wall surfaces 5a, 6a, the first to fourth side wall surfaces 5a1, 5a2, 6a1, 6a2, and the first rotation preventing portion 7 (restraining surface 7a), preferably all of them are It is preferable that a hard film is coated. This hard film is any one of a nitride, a carbonitride, and an oxynitride containing one or more elements selected from Group 4a, 5a, 6a group metals, Al, Si, and B elements. It is preferable. The reason for this is that by covering the hard film, it is possible to suppress wear and wear of the contact portion caused by repeated attachment / detachment of the circular insert 8 or 8a to / from the tool body 2, and the receiving surface of the tool body 2 The accuracy of the seating surface 4, the arcuate wall surfaces 5 a and 6 a of the side walls 5 and 6, the restraining surface 7 a of the rotation preventing portion 7, etc. is avoided, and the circular insert 8 is securely attached with high accuracy and cutting is in progress. This is because the circular insert 8 can be prevented from rotating.

  In the above-described cutting tool of the first to seventh embodiments of the present invention, the tool body 2 is preferably made of alloy tool steel (hardware equivalent to SKD61) having a hardness of HRC44-50. . In addition, the processing of the seating surface 4, the side walls 5 and 6, the first rotation prevention unit 7, the second rotation prevention unit 10, the chip discharge groove and the like on the tool body 2 is performed by using the alloy tool steel material 3 It can be performed using a cutting tool such as a small-diameter ball end mill or a radius end mill under the control of an axial NC machine.

In addition, arc-shaped machining of the side walls 5, 6 on the arcuate wall surfaces 5 a, 6 a and the first to fourth side wall surfaces 5 a 1, 5 a 2, 6 a 1, 6 a 2 is performed in the longitudinal direction (vertical direction) with respect to the seating surface 4. A tool, for example, a ball end mill with a small diameter is controlled by movement. At this time, in the arc-shaped machining, a minute machining streak (small irregularities in the arc-shaped surface is perpendicular to the seating surface 4. It is advisable to create a processing trace).
In this way, fine machining streaks in the vertical direction remain on the arc-shaped wall surfaces 5a, 6a of the side walls 5, 6 or the first side wall surface 5a1, the second side wall surface 5a2, the third side wall surface 6a1, and the fourth side wall surface 6a2. When the circular insert 8 is mounted on the insert mounting seat 3 and the outer peripheral side surface 13 of the circular insert 8 is constrained by being brought into contact with the arcuate wall surfaces 5a, 6a, etc., the circular insert 8 is caused by the machining stripes. The binding force against increases. Thereby, it becomes possible to further exhibit the effect of preventing the circular insert 8 from rotating during the cutting process.

  In addition, in a cutting edge-exchangeable cutting tool equipped with a circular insert, when the circular insert 8 is mounted on the tool body 2 so that the axial rake angle is “negative”, the cutting load during cutting is circular. It acts on the insert in the clockwise direction (R1). On the other hand, when the circular insert 8 is mounted on the tool body 2 so that the axial rake angle is “positive”, the cutting load during cutting is counterclockwise with respect to the circular insert ( Act on R2).

Therefore, when the circular insert is mounted on the tool body 2 so that the axial rake angle is “positive”, if the circular insert is fixed to the seating surface 4 using a left-hand screw as the set screw 9, the circular insert is cut during the cutting process. The direction of the rotational force for rotating the insert is the counterclockwise rotation direction (R2). The rotating force acting in the counterclockwise rotation direction (R2) acts in the direction in which the set screw 9 is tightened, so that the set screw 9 can be prevented from loosening.
On the other hand, when a circular insert is mounted on the tool body 2 so that the axial rake angle is “negative”, if the circular insert is fixed to the seating surface 4 using a right-hand screw as the set screw 9, a circular shape is obtained during the cutting process. The direction of the rotational force for rotating the insert is the clockwise direction (R1). Since the rotational force acting in the clockwise direction (R1) acts in the direction in which the set screw 9 is tightened, loosening of the set screw 9 can be prevented.

  Thus, also in the cutting edge-exchangeable cutting tool of the present invention, according to the “positive / negative” of the axial rake angle formed by the circular insert 8 attached to the tool body 2, the screw specifications of the set screw 9, that is, the right screw, By adopting a configuration in which the left screw can be used appropriately, it is possible to further obtain the effect of preventing the circular insert from rotating during cutting.

1: Cutting edge exchangeable cutting tool 2: Tool body 3: Insert mounting seat 4: Seating surface, 4a: Screw hole, 4b: Open end of screw hole 5: Side wall, 5a: Arc-shaped wall surface
5a1: first side wall surface, 5a2: second side wall surface 6: side wall, 6a: arc-shaped wall surface
6a1: 3rd side wall surface, 6a2: 4th side wall surface 7: 1st rotation prevention part (insert rotation prevention part), 7a: Restraint surface 8: Circular insert, 8a: Circular insert 9: Set screw 10: 1st 2 rotation prevention part, 10a: tip part of rotation prevention part 11: upper surface (rake face)
12: Bottom surface 13: Peripheral side surface (flank)
14: Cutting edge 15: Screw insertion hole, 15a: Open end of screw insertion hole 16: Outer peripheral rotation prevention surface, 16a: Lower end surface portion, 16b: Upper end surface portion 17: Indexing portion for mounting, 17a: Recessed portion 18: Step Side wall (boundary),
18a: a first side wall having a curved shape, 18b: a second side wall having a curved shape,
18c: the most protruding end, 18d: the most recessed end h1: thickness (height) of the circular insert
h2: Height from the upper end of the rotation prevention surface of the circular insert to the bottom surface of the circular insert h3: Height from the lower end of the rotation prevention surface of the circular insert to the bottom surface of the circular insert h4: The rotation prevention surface of the circular insert Height from the upper end to the upper surface of the circular insert L1: Width between adjacent rotation prevention surfaces provided on the outer peripheral surface of the circular insert L2: Width of the rotation prevention surface in the circumferential direction L3: From the opening end of the screw insertion hole Distance from the most protruding end of the first side wall having the curved shape L4: Distance from the opening end of the screw insertion hole to the most recessed end of the second side wall having the curved shape O: Tool axis (rotation center axis) )
O1: Center axis of the screw insertion hole O2: Center axis of the screw hole P: Farthest part that is the farthest distance from the center axis of the screw hole of the second rotation preventing part r1: First side wall 18a having a curved shape The radius of the circular arc of r2: The radius of the circular arc of the tip of the first rotation preventing portion β1: The inclination of the arcuate wall surface of the side wall, the first side wall surface to the fourth side wall surface θ1: The outer peripheral surface of the circular insert Inclination angle θ2: Inclination angle of rotation prevention surface of circular insert

Claims (16)

On the insert mounting seat of the tool body, an upper surface serving as a rake surface, a bottom surface formed opposite to the upper surface, an outer peripheral side surface serving as a flank surface connecting the upper surface and the bottom surface, the rake surface and the flank surface A circular insert having a cutting edge formed at a ridge line portion intersecting with each other and a screw insertion hole penetrating from the upper surface to the bottom surface, and using a screw member for a screw hole formed in a seating surface of the insert mounting seat The outer peripheral side surface of the circular insert mounted on the seating surface is constrained by two arc-shaped wall surfaces erected from the insert mounting seat, and is attached in the circumferential direction of the outer peripheral side surface of the circular insert. Any one of a plurality of outer peripheral rotation prevention surfaces formed at a predetermined interval is brought into contact with a first rotation prevention unit provided with a restraining surface standing from the insert mounting seat and having a predetermined lateral width. In indexable cutting tool that,
The circular insert has a mounting index portion that is a recess with respect to the bottom surface on the bottom surface,
The mounting indexing portion forms a smooth convex curved shape in a direction away from the central axis of the screw insertion hole along the circumferential direction of the concentric circle of the central axis of the screw insertion hole at the boundary with the bottom surface. A plurality of first side walls and a stepped side wall portion in which a plurality of second side walls forming a smooth convex curved shape in a direction approaching the central axis of the screw insertion hole are alternately arranged,
The seating surface of the insert mounting seat is a second rotation preventing portion that can be inserted into the recess of the concave portion adjacent to the curved first side wall in the mounting index portion of the circular insert. With
When the circular insert is attached to the seating surface and the cutting edge of the circular insert is indexed,
The second rotation preventing portion is inserted into the hollow portion of the circular insert, and the restraining surface of the first rotation preventing portion can come into contact with the outer peripheral rotation preventing surface of the circular insert. The cutting edge exchangeable cutting tool. The step side wall portion of the circular insert has a configuration in which a plurality of the first side wall and the second side wall forming the curved shape are sequentially connected,
The length from the opening end portion of the screw insertion hole to the farthest portion in the first side wall having the curved shape is the farthest portion from the opening end portion of the screw insertion hole in the second side wall having the curved shape. It is said that it is larger than the length until
The length of the second rotation preventing portion provided in the seating surface, the length in the direction passing through the central axis of the screw hole is the farthest portion in the first side wall having the curved shape 2. The cutting edge-replaceable cutting tool according to claim 1, wherein the cutting edge is replaceable with a cutting edge and is larger than a length up to the farthest portion of the second side wall having the curved shape. In a plan view of the insert mounting seat, the lateral width ends of the constraining surface provided in the first rotation preventing portion are point R and point Q, and a line segment RQ connecting the point R and point Q When a straight line passing through the center point and the central axis of the screw hole formed in the seating surface is a straight line S2,
The second rotation preventing part is formed along the straight line S2,
The circular insert attached to the insert mounting seat is a plan view of the upper surface or the bottom surface of the circular insert.
The first side wall having the curved shape formed on the bottom surface and the outer peripheral rotation prevention surface formed on the outer peripheral side surface are formed so as to face each other, and
The second side wall having the curved shape and the outer peripheral side surface between the adjacent outer peripheral rotation prevention surfaces are formed so as to face each other.
The cutting edge exchangeable cutting tool according to claim 1 or 2, wherein the cutting tool is replaceable. In a plan view of the insert mounting seat, the lateral width ends of the constraining surface provided in the first rotation preventing portion are point R and point Q, and a line segment RQ connecting the point R and point Q A straight line passing through the midpoint and the central axis of the screw hole formed in the seating surface is defined as a straight line S2, and a straight line intersecting the straight line S2 in the clockwise or counterclockwise direction at a predetermined angle α1 or α2. When a straight line S3 and a straight line S4 are used,
The angle α1 or α2 is set in a range of 2 ° to 10 °,
The circular insert attached to the insert mounting seat is a plan view of the upper surface or the bottom surface of the circular insert.
The first side wall having the curved shape formed on the bottom surface and the outer peripheral rotation prevention surface formed on the outer peripheral side surface are formed so as to face each other, and
The second side wall having the curved shape and the outer peripheral side surface between the adjacent outer peripheral rotation prevention surfaces are formed so as to face each other.
The cutting edge exchangeable cutting tool according to claim 1 or 2, wherein the cutting tool is replaceable. In a plan view of the insert mounting seat, the lateral width ends of the constraining surface provided in the first rotation preventing portion are point R and point Q, and a line segment RQ connecting the point R and point Q A straight line passing through the midpoint and the central axis of the screw hole formed on the seating surface is defined as a straight line S2, intersects the straight line S2, and has a predetermined angle α in the clockwise or counterclockwise direction with the straight line S2. When the straight line formed is the straight line D1 or the straight line D2,
The second rotation preventing portion is formed along the straight line D1 or the straight line D2.
The angle α is set to α = 360 ° / (2 × n), where n is the number of first side walls having the curved shape provided in the mounting index portion of the circular insert,
The circular insert attached to the insert mounting seat is a plan view of the upper surface or the bottom surface of the circular insert.
The second side wall having the curved shape formed on the bottom surface and the outer peripheral rotation prevention surface formed on the outer peripheral side surface are formed so as to face each other, and
The first side wall having the curved shape and the outer peripheral side surface between the adjacent outer peripheral rotation prevention surfaces are formed so as to face each other.
The cutting edge exchangeable cutting tool according to claim 1 or 2, wherein the cutting tool is replaceable. In a plan view of the insert mounting seat, the lateral width ends of the constraining surface provided in the first rotation preventing portion are point R and point Q, and a line segment RQ connecting the point R and point Q A straight line passing through the midpoint and the central axis of the screw hole formed in the seating surface is defined as a straight line S2, and a straight line that intersects the straight line S2 and forms a predetermined angle α with the straight line S2 in the counterclockwise direction is a straight line D2. Furthermore, when a straight line that intersects the straight line D2 and forms an angle α1 with the straight line D2 in the clockwise or counterclockwise direction is defined as a straight line S5 or a straight line S6,
The second rotation preventing portion is formed along the straight line S5 or the straight line S6.
The angle α is set to α = 360 ° / (2 × n), where n is the number of first side walls having the curved shape provided in the mounting index portion of the circular insert. The angle α1 is set in a range of 2 ° to 10 °,
The circular insert attached to the insert mounting seat is a plan view of the upper surface or the bottom surface of the circular insert.
The second side wall having the curved shape formed on the bottom surface and the outer peripheral rotation prevention surface formed on the outer peripheral side surface are formed so as to face each other, and
The first side wall having the curved shape and the outer peripheral side surface between the adjacent outer peripheral rotation prevention surfaces are formed so as to face each other.
The cutting edge exchangeable cutting tool according to claim 1 or 2, wherein the cutting tool is replaceable. In a plan view of the insert mounting seat, the lateral width ends of the constraining surface provided in the first rotation preventing portion are point R and point Q, and a line segment RQ connecting the point R and point Q A straight line passing through the midpoint and the central axis of the screw hole formed in the seating surface is a straight line S2, and a straight line that intersects the straight line S2 and forms a predetermined angle α in the clockwise direction with the straight line S2 is a straight line D1. Furthermore, when a straight line that intersects the straight line D1 and forms an angle α2 with the straight line D1 in the clockwise or counterclockwise direction is defined as a straight line S7 or S8,
The second rotation preventing portion is formed along the straight line S7 or the straight line S8,
The angle α is set to α = 360 ° / (2 × n), where n is the number of first side walls having the curved shape provided in the mounting index portion of the circular insert. The angle α2 is set in a range of 2 ° to 10 °,
The circular insert attached to the insert mounting seat is a plan view of the upper surface or the bottom surface of the circular insert.
The second side wall having the curved shape formed on the bottom surface and the outer peripheral rotation prevention surface formed on the outer peripheral side surface are formed so as to face each other, and
The first side wall having the curved shape and the outer peripheral side surface between the adjacent outer peripheral rotation prevention surfaces are formed so as to face each other.
The cutting edge exchangeable cutting tool according to claim 1 or 2, wherein the cutting tool is replaceable. The circular insert according to claim 3 or claim 4,
The first side wall having the curved shape and the outer peripheral rotation prevention surface are arranged so that the most projecting end portion of the first side wall having the curved shape is opposed to the central portion of the outer peripheral rotation prevention surface. A cutting edge exchangeable cutting tool characterized by the above. The circular insert according to any one of claims 5 to 7,
The second side wall having the curved shape and the outer peripheral rotation prevention surface are arranged so that the most recessed end portion of the second side wall having the curved shape is opposed to the central portion of the outer peripheral rotation prevention surface. A cutting edge exchangeable cutting tool characterized by the above. The first side wall having the curved shape constituting the step side wall portion of the circular insert has an arc shape with a radius (r1) protruding outward with respect to the central axis of the screw insertion hole,
The distal end portion of the second rotation preventing portion formed on the seating surface has an arc shape with a radius (r2) protruding outward with respect to the central axis of the screw hole,
The blade tip exchangeable cutting tool according to any one of claims 1 to 9, wherein the radius (r1) is larger than the radius (r2). The circular insert has a thickness h1, a height from the bottom surface to the upper end of the outer periphery rotation prevention surface h2, and a height from the bottom surface to the lower end of the outer periphery rotation prevention surface h3. ,
The h2 satisfies the following formula:
(1/2) h1 ≦ h2 ≦ (2/3) h1
The blade tip replaceable cutting tool according to any one of claims 1 to 10, wherein the h3 satisfies the following expression.
(1/10) h1 ≦ h3 ≦ (1/3) h1 One of the two arcuate wall surfaces stands on one end side of the first rotation prevention unit, and the other of the two arcuate wall surfaces stands on the other end side of the first rotation prevention unit. Has been established,
One of the arc-shaped wall surfaces is composed of a wall surface obtained by integrating two first side wall surfaces and second side wall surfaces having different arc-shaped diameters,
2. The cutting edge-replaceable cutting according to claim 1, wherein the other of the arc-shaped wall surfaces is constituted by a wall surface integrating a third side wall surface and a fourth side wall surface having different arc-shaped diameters. tool. The first side wall surface is disposed on one end side of the first rotation prevention unit, and the third side wall surface is disposed on the other end side of the first rotation prevention unit,
The diameter of the circular arc shape of the first side wall surface and the third side wall surface is set to the same diameter d1, and the diameter d1 is set to the diameter d0 of the inscribed circle of the circular insert attached to the insert mounting seat. Set,
The diameter of the circular arc shape of the second side wall surface and the fourth side wall surface is set to the same diameter d2, and the diameter d2 is set to be larger than the diameter d1. Item 13. The cutting edge exchangeable cutting tool according to Item 12. The two arcuate wall surfaces, or the first to fourth side wall surfaces are erected with an inclination angle β1 in the tool axis direction of the tool body with respect to a line segment orthogonal to the seating surface,
When the inclination angle of the outer peripheral side surface of the circular insert attached to the seating surface is θ1, (θ1−β1) satisfies the following expression. The cutting edge exchange type cutting tool according to any one of 13.
0 ≦ θ1-β1 ≦ 1.0   The two arcuate wall surfaces or the first to fourth side wall surfaces have a plurality of machining streaks in the vertical direction. The cutting edge exchangeable cutting tool as described.   At least one of the seating surface, the arc-shaped wall surface, the first to fourth side wall surfaces, and the first rotation preventing portion includes a periodic table 4a, 5a, 6a group metal, Al, Si. A hard film made of any one of nitride, carbonitride, and oxynitride containing at least one element selected from the elements B and B is coated. The blade-tip-exchange-type cutting tool according to any one of claims 12 to 15.

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