JP2017177307A - Cutting insert and cutting tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting insert capable of coping with deep grooving and easily preventing coming off from a holder, and a cutting tool using the same.SOLUTION: A nearly triangular (polygonal) plate 10 having three corners 20 is formed into a cutting insert 101 having a front cutting edge 21 the cutting edge ridge of which extends in a thickness direction of the plate 10 at the three corners 20. The front cutting edge 21 is so provided that the edge thickness in the thickness direction of the plate 10 may be larger than the thickness of the plate 10, and each end edge in the front cutting edge 21 may be located outside of each main face of the plate 10. Out of the outer peripheral face of the plate 10, the outer peripheral face part between adjacent front cutting edges 21 is provided with a recess groove 33 extending in a direction between the front cutting edges 21. A cutting tool 201 uses a holder 200 fitted with this recess groove 33 to have a seating part 230 or the like narrower than the edge width of the front edge 21 and is based on a clamp seated on and fitted with the same.SELECTED DRAWING: Figure 4

Description

  The present invention is a cutting insert used for grooving, parting off, etc. in turning, and particularly a cutting insert suitable for deep grooving, and a cutting formed by clamping this to the tip of a holder. Related to tools.

  A representative cutting insert for grooving (also referred to as a bite insert or a throw-away insert) in which a groove of a predetermined width is provided in turning is a rectangular rod-like or thin plate-like cutting insert, and the cutting insert body There is a so-called one-corner (one-cutting edge) type having a front cutting edge with a predetermined cutting edge width at one end (see Patent Document 1). In this case, the upper surface (the surface opposite to the rake surface) forms a pressed part parallel to the front cutting edge and is separated from the lower surface (bottom surface opposite to the rake surface) that forms a straight line in the front and rear direction. As it goes to the base end side (opposite to the front cutting edge), it has a guide portion that approaches its lower surface. The tip mounting seat at the tip of the holder to which such a cutting insert (hereinafter also referred to as an insert) is attached is formed as a seating portion that extends linearly in the front-rear direction and is opposed to the lower surface of the insert. Of the clamping surface, the portion closer to the front cutting edge of the insert is a pressing portion parallel to the upper surface, and is formed so as to approach the seating portion following the guide portion as it goes to the proximal end side. Such a cutting insert is clamped by pressing it into the mounting seat from the front and seating the bottom surface (lower surface) of the cutting insert on the seating portion. That is, by seating in this manner, the portion close to the front cutting edge on the opposite side (rake face side) can be moderately deformed by the pressing portion of the clamp portion integrally provided on the holder. It is used as a clamp by a so-called self-restraining type that is tightened between the upper and lower sides. In addition to such a one-corner type, a so-called two-corner type cutting insert, which is a rectangular rod-shaped or thin-plate-shaped cutting insert, and has a front cutting edge at each end of the main body, respectively. In some cases, the cutting tool is fixed to the chip mounting seat of the holder by a self-constraining clamp.

  When a cutting tool using the above-mentioned cutting insert is attached to a tool post such as a lathe or a machining center and grooving is performed, the wear of the cutting edge (corner) and the like progresses after a large number of machining steps. As a result, the sharpness is lowered, and the insert or corner (cutting edge) is replaced with the end of its life. Even with multi-corner inserts, when the cutting edges of all the corners are exhausted, they are discarded (slow away), replaced with new cutting inserts, and the machining can be continued.

  By the way, in such processing, when deep grooving processing (deep grooving processing) with a narrow groove width is performed, the groove width, that is, a plate thickness equal to or less than the blade width of the front cutting edge, the grooving depth. The cutting insert which has the length dimension from the front cutting edge corresponding to this will be used. On the other hand, such a cutting insert employs a clamping means of the above-described self-restraining type between the chip mounting seat of the holder and the pressing portion provided integrally therewith, so that a set screw (for clamping) is used. Since there is no interference due to screws, etc., the tip mounting seat and the pressing part are theoretically narrower than the cutting edge width of the front cutting edge. Yes.

  On the other hand, if the cutting tool adopts the clamping means of the self-restraining type as described above, and has a high cutting resistance such as grooving into a high-strength material, or if high processing accuracy is required, There is a demand for a clamping strength that can sufficiently resist not only the main component force but also the cutting resistance acting in the lateral direction (blade width direction). In order to resist such cutting force and force applied in the lateral direction, on the rake face and the lower face (bottom face) on the opposite side of the cutting insert, which is the part to be clamped to the holder (clamped part) Some have a recess (groove) extending forward and backward from the front cutting edge (Patent Document 1). In this case, the clamp part (sitting part, pressing part) of the holder is provided with a convex part (protrusion) corresponding to the concave part (concave groove) of the cutting insert, so that both of them (unevenness) are attached at the time of attachment. As a result, the lateral movement is structurally stopped. As a result, the request can be met. And if it is such a fitting structure, it can respond also to the setting which positions the end surface with the horizontal cutting edge of a cutting insert by the automatic lathe provided with the automatic feed mechanism of material.

JP-A-8-71812

  By the way, in the 1 or 2 corner type cutting insert as described above, the number of workpieces that can be processed naturally is limited to the number corresponding to the number of front cutting edges, and the disposable frequency is, for example, 3 corner types. Compared to the cutting insert (so-called triangular tip), the tool unit price per corner (blade) becomes high. As a result, the grooving cost is generally increased. On the other hand, for example, a triangular corner type insert having three cutting edges in a corner (hereinafter, also referred to as a triangular tip or simply a tip) is fixed to a holder in a three-corner type. A screw hole provided on the wall surface of the holder's chip mounting seat, with a set screw (clamp screw) passed through a clamp hole (through hole) drilled in the thickness (blade width of the front cutting edge) direction in the center of the plate It was screwed in and clamped by pressing an insert (hereinafter also referred to as a chip) (screw clamp type). For this reason, in the conventional triangular tip, the depth that can be cut in the grooving (groove depth) is within a range that does not interfere with the set screw when viewed from one corner of the triangle toward the center. Limited to depth. That is, deep grooving that exceeds the dimension from the front cutting edge to the center of the triangular tip is impossible.

  On the other hand, even if the above-mentioned 1 or 2 corner type cutting insert is used, and this is clamped by a self-restraining type, as described above, a concave groove is provided on the outer peripheral surface, and the chip mounting seat is fitted to this. In this case, it is possible to obtain a clamp strength that can sufficiently resist the lateral force during cutting. However, with such a self-restraining clamp type cutting tool, for example, when deep grooving is performed on a high-strength material, when the turret is returned after grooving, or chip disposal in the grooving process, etc. In the case where the tool post is repeatedly reciprocated (longitudinal feed) for this reason, it is rare, but due to friction between both ends of the front cutting edge (side cutting edge side) and the wall surface (side surface) of the groove being processed, The cutting insert may come off (separate) from the chip mounting seat. This is because, in the above-mentioned self-restraining type clamp, the proof strength in the direction in which the tip is pulled out from the tip mounting seat depends on the spring property of the pressing portion (pressing force by elastic deformation), and the lateral direction. This is because there is no structural fitting (engagement) that can resist this. Such a problem is easily manifested as the width of the front cutting edge is narrowed, so that the pressure contact surface is reduced, and hence the pressing force is likely to be reduced.

  The present invention has been made in view of the above-mentioned problems in grooving, has at least three front cutting edges, can cope with deep grooving, and is easily prevented from coming out of the holder. It is an object of the present invention to provide a cutting insert that can be realized and a cutting tool using the same.

The present invention according to claim 1 for solving the above-mentioned problems is a polygonal plate having at least three corners, and at least the three corners are provided with a front cutting edge whose cutting edge ridge extends in the thickness direction of the plate. A cutting insert having
The front cutting edge is provided such that the blade width in the thickness direction of the plate is larger than the thickness of the plate, and each edge of the front cutting edge is located outward from each main surface of the plate. And
Of the outer peripheral surface of the plate, each outer peripheral surface portion between adjacent front cutting edges is provided with a concave groove or ridge extending in the direction between the front cutting edges.
According to a second aspect of the present invention, the polygon forms at least three rotationally symmetric polygons in its contour, and the front cutting edge has the number of rotational symmetries at the corner of the polygon. The cutting insert according to claim 1, wherein the cutting insert is provided.

The present invention described in claim 3 is a cutting tool in which the cutting insert according to claim 2 is clamped to a holder,
The holder includes a clamp portion for clamping the cutting insert at a tip portion thereof, and the clamp portion includes the concave groove or the two of the outer peripheral surface portions of the cutting insert. The seat has two seating portions that can be fitted in the front and rear positions, and the two seating portions are arranged in front so that the longitudinal movement of the cutting insert in the clamp portion can be restricted. Is inclined to the rear and the rear one is inclined to the front,
Separately from the holder, in the fitting state of the concave groove or the ridge in the two outer peripheral surface portions to the two seating portions, the concave groove or the ridge in the other outer peripheral surface portion. And a pressing tool with a pressing portion configured to press and clamp the cutting insert toward the two seating portions in the fitted state. And
The cutting insert has the two seating portions fitted with the concave grooves or the ridges in the two outer peripheral surface portions of the cutting insert, and the pressing portion of the presser is the other one. Are fitted in the concave grooves or the ridges in the two outer peripheral surface portions, and in the fitted state, the presser clamps and clamps the cutting insert toward the two seating portions. It is characterized by being.

  Since the cutting insert of the present invention has three cutting edges (corners) based on the above configuration, the cutting edge cost is generally reduced as compared with those having only two cutting edges. On top of that, each outer peripheral surface portion is provided with a groove or ridge, so that it fits into the seating portion to which it fits and other grooves on the outer peripheral surface portion located on the upper surface, for example. By using a holder provided with a presser that can hold the insert and clamping it, it is possible to perform clamping not only in the lateral direction but also without moving forward. Moreover, since it is not fixed by the clamp screw, deep grooving can be performed without interference by the clamp screw by making the width of the seating portion or the like in the clamp portion smaller than the blade width of the front cutting edge.

  The number of corners in the cutting insert of the present invention is preferably 3, but may be 4 or more. On the other hand, it is preferable that the polygon forms at least three rotationally symmetric polygons in its outline, and the front cutting edge has the number of rotational symmetries at the corner of the polygon. . This is because the cutting blade can be easily replaced in one holder. Here, the “rotationally symmetric polygon” means not only a rotationally symmetric polygon in a graphic or physical sense, but in addition, the cutting insert is clamped to one holder. In the case of using as a cutting tool, after unclamping, to replace the front cutting edge (corner) and re-clamp, before and after the clamping, a certain angle (for example, if the rotational symmetry is 3 times, It means that the polygon can be exchanged (clamped) every rotation of 120 degrees. Therefore, as long as the front cutting edge (corner) can be replaced by rotating at a certain angle, for example, each corner on the outer peripheral surface of the polygonal plate or the main surface of the plate (polygonal plate). (Before cutting edge) or in the vicinity thereof, “cuts” etc. are provided for identifying each corner, so it cannot be said that it is strictly a “rotationally symmetric polygon” in terms of graphics or physics. This is also referred to as a “rotationally symmetric polygon” in the present application. In other words, in the present application, the “rotationally symmetric polygon” means, as described above, in addition to a polygon that can exchange (clamp) the front cutting edge (corner) for every rotation of a certain angle. A cutting insert having three or more cutting edge corners, which is recognized as a rotationally symmetric polygon.

  As apparent from the effect of the cutting insert of the present invention described above, the cutting tool (bite) of the present invention using this insert is expected to reduce the grooving cost. Moreover, in the state where the insert is clamped to the holder, the structural fitting can be secured against the force in the lateral direction and the pulling direction, so that it can be sufficiently resisted. In addition, when the cutting insert is clamped by the holder to be a cutting tool, the seat portion and the presser are within the range of the width of the front cutting edge so that the holder does not interfere with the work material. By doing so, a deep cut can be made without a limit by a screw at the center of a polygonal plate as in the prior art.

The perspective view of the embodiment which actualized the cutting insert which concerns on this invention, and its partial enlarged view. It is a figure explaining the whole shape of the cutting insert of FIG. 1, Comprising: A is a side view (figure seen from the side relief surface side), B is a left side view of A (from the front relief surface side in one front cutting edge) C is a plan view of A (viewed from the rake face side of one front cutting edge), and D is a cross-sectional view taken along the line S1-S1 in A (cross-sectional view of the groove). The enlarged view of the part containing the front cutting edge part in each figure of A of FIG. 2, B, and C, and the enlarged view of the part of D figure. The perspective view which abbreviate | omitted a part of cutting insert and a shank explaining the holder which clamps the cutting insert of FIG. 1, and the cutting tool formed by clamping. 4A is a side view of the cutting tool of FIG. 4 as viewed from the arrow A1, and FIG. 5A is an S2-S2 cross section of FIG. 5, B is an S3-S3 cross section of FIG. 5, and C is an enlarged cross sectional view of the S4-S4 cross section of FIG. The figure which looked at the cutting tool of FIG. 4 from the front-end | tip of a holder, and the elements on larger scale. The left view of FIG. The perspective view for description of the Example which replaced the ditch | groove of the outer peripheral surface part in the cutting insert of FIG. 1 with the protruding item | line. The perspective view which shows the embodiment which actualized as a pentagonal (with five corners) cutting insert. The side view explaining the cutting tool formed by clamping the cutting insert of FIG.

  The embodiment which actualized the cutting insert of this invention is described in detail based on FIGS. 1-3. The cutting insert 101 of this example is based on a plate (flat plate) 10 having a substantially triangular shape (regular triangle) and having a constant thickness, and a cutting edge that extends in the thickness direction of the plate 10 at each of the three corners 20. It is configured as a triangular tip having a blade 21. In this example, the front cutting edge 21 and the side cutting edge 22 provided in each corner 20 have the same shape and structure. That is, when the cutting insert 101 of this example looks at its one main surface (surface of the plate) 11 as a triangular plate 10 (see FIG. 2-A), it is at an equal angular interval of 120 degrees around its center O. Since it has the front cutting edge 21 and has a shape having rotational symmetry three times, the one front cutting edge 21 (the left front cutting edge 21 in FIG. 1, FIG. 2- A description will be given centering on the upper left front cutting edge of A).

  The shape and structure of the cutting insert (triangular tip) 101 of this example is based on a regular triangular base material (flat plate) having a certain thickness, and is based on a triangular outer peripheral surface (thickness surface on three sides around the triangular plate). Each of the corners 20 is sandwiched so that both sides near the corner 20 are formed in a notch shape or a cut shape to form a rake face 23 and a front flank face 25, respectively. Of these, the rake face 23 gives an appropriate positive rake angle (for example, 25 degrees) to the upper lateral side (outer peripheral face) 31 in the figure of the triangular outer peripheral face shown in FIG. In addition, a flat surface that becomes lower as the distance from the front cutting edge 21 increases. And it connects with the upper surface (the outer peripheral surface which is one side of a triangle (thickness surface of the board 10)) which is the upper horizontal side 31 in the same figure via the circular arc-shaped inclined wall surface 27 which becomes concave at the rear end of the plane. It is formed as follows. On the other hand, the front flank 25 has a shape that is linearly cut at the corner 20 of an equilateral triangle so that an appropriate front flank angle (for example, 2 degrees to 20 degrees) is provided.

  In this example, the width of the front cutting edge 21 (the length of the front cutting edge 21 (cutting edge) when viewed from the rake face 23 side or the front flank 25 side) H1 is the central portion of the triangular plate 10. (See FIG. 3-B). Moreover, when the front cutting edge 21 is viewed from the side of the rake face 23, the side cutting edge 22 has a back so that the width of the rake face 23 decreases from the left and right edges 21 b of the front cutting edge 21 toward the rear. Extends with a rake angle. And the part near the front cutting edge 21 including this horizontal cutting edge 22 is provided so as to exist (protrude) outward from each main surface (both sides) 11 of the plate 10. That is, when the rake face 23 including the front cutting edge 21 is viewed from above the rake face 23, the portions including the side cutting edges 22 located on both sides of the rake face 23 together with both ends 21 b of the front cutting edge 21 are formed on the substrate 10. The surface (main surface) 11 on the front and back sides of the surface of the front surface 11 is present in a small amount but on the outside, and is formed so as to form a thicker portion than the others.

  However, the thick portion existing outside in this way is a portion (lateral clearance surface 29) where the rear end 22b of the horizontal cutting edge 22 and the lower end 25b in the height range of the front clearance surface 25 are connected by a straight line L1. Is a triangular region near the front cutting edge 21 when viewed in a linear direction parallel to the front cutting edge 21, and this portion protrudes on each surface (main surface) 11 of the front and back of the plate 10. Has been. Note that, on both sides 11 of the plate 10, the flank (lateral flank 29) of the side cutting edge 22 has an appropriate side flank angle. Thus, in the grooving process in which the front cutting edge 21 of one corner 20 is longitudinally fed in the direction along the surface 11 of the plate 10 toward the outer peripheral surface of the work material, the insert 101 is theoretically used. As for itself, even if the groove depth exceeds the center O of the triangular plate 10 from the front cutting edge 21, the setting is such that cutting can be performed.

  Of the outer peripheral surface 31 of the plate 10 (triangular plate) constituting the cutting insert 101 of this example, the outer peripheral surface portion between the adjacent front cutting edges 21 is arranged in the thickness T1 direction (front) of the plate 10. A concave groove 33 extending in the direction between the front cutting edges 21 is provided at the center of the cutting edge width H1) so as to form a clamped portion in the clamp to the holder. However, in this example, the concave groove 33 is substantially V-shaped in which the cross section is symmetrical, and extends in the direction between the front cutting edges 21 along each side of the triangular tip with the same cross section. It is provided in a form extending continuously and linearly so as to penetrate through the inclined wall surface 27 on the rake face 23 of the cutting edge 21 and the front relief surface 25 of another adjacent front cutting edge 21. The concave groove 33 has a V-shaped groove with an opening width close to the thickness T1 of the plate 10, and the V-shaped groove angle is set to about 90 degrees, for example. Earl is attached.

  According to such a cutting insert 101 of this example, since it has three corner cutting edges, the number of cutting edges is larger than that of one corner or two corner cutting edges. Since many processes can be performed with the cutting insert 101, a reduction in tool (cutting edge unit price) cost and processing cost is expected. Moreover, although it is a triangular chip | tip, the screw hole for clamping (screwing) is not provided in the center of the triangular board 10. FIG. That is, unlike the conventional triangular tip, it is not a cutting tool that is clamped to a holder through a set screw in a screw hole provided in the center of the tip. The above-described concave groove (clamped portion) 33 is provided in the outer peripheral surface portion between the cutting edges 21. For this reason, as will be described in detail below, the clamp portion (sitting portion) at the tip of the holder, and the pressing portion in the presser are made to have a convex shape into which the concave groove 33 can be fitted. By setting the width of the convex portion to a thickness of the insert 101 of this example, more precisely, a dimension narrower than the blade width H1 of the front cutting edge 21, and by clamping the cutting insert 101 to such a holder to make a cutting tool, It is possible to cope with deep grooving that extends from the front cutting edge 21 to the center O of the triangular tip. In such a clamp, the triangular tip can be stably fixed both in the lateral direction and in the front-rear direction based on the fitting state. Hereinafter, an example of the cutting tool 201 formed by clamping the cutting insert 101 will be described in detail with reference to FIGS.

  First, the holder 200 constituting the cutting tool 201 will be described. The holder 200 of this example has a shank (partially omitted) 210 having a substantially square cross section and a rod shape, and a tip (head) 215 that protrudes in a rectangular shape toward the lower surface 213 in the width of the shank 210 at the tip. ing. In this example, a substantially ¼ arc-shaped pocket (concave portion) 221 is provided at the tip portion 215 along the one side surface (lateral wall) 217 of the shank 210 and cut toward the upper surface 219 as will be described later. However, a seat for restraining two outer peripheral surface portions (clamped portions) on two sides sandwiching one corner 20 of the triangular tip 101 along the side surface (lateral wall) 223 opposite to the pocket 221. A portion (clamp portion) 230 is provided. These two seating parts (hereinafter also referred to as clamp parts) 230 are formed in a symmetrical V-shape that opens left and right (front and back of the holder 200) at an opening angle of 60 degrees in a side view. Of the two seating portions 230, 230, the tip end side inclined toward the rear of the holder 200 has the upper end relatively lower than the rear end tilted toward the front, and the tip end surface 216 of the holder 200. And is formed so as to rise from the bottom (lower part) of a pocket (concave part) 221 having a substantially arc shape. Further, a recess (relief) 225 is provided in a notch shape so that the upper end of the rear seating portion 230 is lower than the upper surface 219 of the holder 200.

  On the other hand, when the two front and rear seating portions 230, 230 are seated through the two outer peripheral surface portions sandwiching the corner 20 with one corner 20 (front cutting edge 21) of the triangular tip facing down, A front cutting edge in which an outer peripheral surface portion (an upper horizontal side 31 extending sideways) that is one side facing the corner 20 is located slightly above the upper surface 219 of the holder 200 and protrudes from the front end surface 216 of the holder 200 Each part of the front flank 25 of the (front cutting edge 21 responsible for cutting) and the rake face 23 of the front cutting edge 21 located behind is set to be positioned above the upper end of the seating portion 230. Further, the lower ends of the two seating portions 230 (intersections of the two V-shaped seating portions 230) are cut into a semicircular shape so that the other front cutting edge 21 positioned below does not interfere with each other. (Escape) 227. These seats 230 extend along V-shaped sides (corresponding to two sides of the triangular chip) with a width equal to or smaller than the thickness T1 of the plate 10 forming the insert 101. However, the seating portion 230 has a trapezoidal mountain shape that fits into a concave groove (clamped portion) 33 in the outer peripheral surface portion of the cutting insert 101 in a cross section, and forms a clamp portion.

  In addition, along the side surface (lateral wall) 217 opposite to the seating portion (clamp portion) 230 in the tip portion 215 of the holder 200, as described above, the quarter arc-shaped pocket (recessed portion) ) 221 is notched. That is, when the holder 200 is viewed from the front end surface 216 on the side opposite to the clamp portion in the front end portion 215 of the holder 200, the lower portion of the front end surface 216 is left, and approximately ¼ rearward and toward the upper surface 219. A pocket (¼ arc-shaped concave portion) 221 cut out in a circular arc shape is formed. The pocket 221 is a part that enables deep cutting without causing the work material to interfere with the tool in grooving of the work material. However, this 1/4 arc-shaped cut is formed so as to leave the wall 229 at the rear seating portion 230 side, the lower portion of the front seating portion 230, and the intersection (semicircular relief). ing.

  And, on the upper surface 219 of the tip portion 215 in such a holder 200, a presser 250 for pressing an outer peripheral surface portion (concave groove 33) which is an upper clamped portion of the insert 101 to be clamped is a screw member (for example, The hexagon socket head bolt 290 is mounted by screwing it into a screw hole (not shown) provided in the upper surface 219 behind the quarter arc-shaped pocket (recess) 221 in the holder 200. However, the presser 250 has a substantially L-shape in a top view (see FIG. 5B), a base portion 251 having a screw member insertion hole, and a clamp portion 255 elongated in the front-rear direction in the top view. A pressing portion 260 that presses an outer peripheral surface portion (concave groove 33) that is a clamped portion above the insert 101 is provided at the lower portion of the tip of 255 (see FIG. 5-A). Then, by screwing the screw member 290, in the present embodiment, among the outer peripheral surface portion (concave groove 33) positioned above the insert 101 at the pressing portion 260, in this example, the front cut positioned at both front and rear ends of the outer peripheral surface portion. It is set to press the position closer to the rear than the middle between the blades 21 and 21.

  In addition, the press part (lower surface) 260 is exhibiting the trapezoid mountain shape fitted to the ditch | groove 33 in the outer peripheral surface part of the cutting insert 101 in the cross section similarly to the above-mentioned seating part 230. However, the dimension (width dimension) in the thickness direction of the insert 101 of the pressing part 260 is made smaller than the thickness T1 of the plate 10 of the insert 101 including the upper part and the rear part (clamp part 255). At the time of pressing, the pressing portion 260 is set so as not to protrude outward from both main surfaces of the plate 10 in the outer peripheral surface portion located above the insert 101. Therefore, in the grooving process to the work material, the seat part 230 that stands up and is formed so that the clamp part 255 including the press part 260 in the presser 250 does not interfere with the work material. ing.

  In this example, two corners (front cutting edge 21) 20 of the triangular tip 101 are sandwiched between two seating portions (trapezoidal peaks) 230 that form a V-shape of the clamp portion of the holder 200 in a side view. The outer peripheral surface portion (concave groove 33) is fitted, and in this state, the upper outer peripheral surface portion (concave groove 33) is fitted with the pressing portion (lower trapezoidal mountain) 260 in the clamp portion 255 of the presser 250. Then, the screw member 290 of the presser 250 is screwed. Thus, when the cutting tool 201 for grooving is used, for example, when the outer peripheral surface of the work material is grooved (or cut-off) by turning, the following effects are obtained. It is done.

  That is, in the grooving process to the work material W by the cutting tool 201 as described above, since the cutting insert 101 has three corner cutting edges as described above, one corner or two corners. Since the number of cutting blades is larger than that of the cutting blade, a large amount of machining can be performed with this one cutting insert 101, so that reduction of the cutting blade unit cost and machining cost is also expected. After the life of the front cutting edge 21 of one corner 20, in this example, since it has a rotationally symmetric shape, the clamp is loosened and the triangular tip (insert 101) is moved around the center O of the plate 10. In addition, it can be rotated 120 degrees and re-clamped, and further processing can be performed with the front cutting edge 21 of another corner 20, so that the setup of the update can be easily performed. The cutting insert 101 of the present example is a triangular tip as clearly shown in FIG. 2-A (FIG. 5-A) or the like, and is a polygon having a rotational symmetry of three times in its substantially triangular outline. In addition, as described above, for example, in the three portions of the three front cutting edges 21 of the insert 101 of this example, different shapes or sizes of cuts are provided for identification, and there are partial shape differences. Even if there is a certain one, it is still possible to change (clamp) the front cutting edge (corner) at a fixed angle (120 degrees in this example) in one holder. Can also be said to have three-fold rotational symmetry.

  Moreover, although it is a triangular tip in this example, it is not the clamp structure which clamps to a holder using the screw hole provided in the center of a triangular plate like the conventional triangular tip. As described above, the seating portion 230 and the pressing portion 260 that rise in the front are clamped so as to be within the range of the blade width H1 of the front cutting edge 21. For this reason, even if it exceeds the center O of the triangular tip from the front cutting edge 21 actually responsible for grooving, it is until immediately before the work material W interferes with the arc surface of the quarter arc-shaped pocket (recess) 221. A cut can be made (see FIGS. 5-B and 8). As described above, according to the cutting tool 201 of the present example, since a deep grooving process which is not possible in the past can be performed, the effect is remarkable such as being suitable for parting off a thick round bar.

  In addition, the cutting insert 101 of the above example has a clamp structure by fitting the seating portion 230 on the holder 200 side and the trapezoidal mountain of the pressing portion 260 with the outer peripheral surface portion (concave groove 33) as a clamped portion. Yes. For this reason, even if an external force acts in the lateral direction (the direction of the arrow A5 in FIG. 5-B, that is, the direction of the rotation axis G (one-dot chain line) of the work material W in FIG. 5-B), This can be resisted by the fitting structure in the outer peripheral surface portion (concave groove 33). As a result, even when grooving a high-strength material, there is no side swaying, so highly accurate grooving can be performed. Further, even when a material is fed out after processing and positioning is performed on the lateral surface of the insert 101 (main surface of the plate 10) like a lathe with an automatic feeding device, the insert moves with the lateral load at that time. Can also be prevented. Further, in the cutting tool 201 of the above example, the two front and rear seating portions 230 are inclined toward the rear or the front, respectively, so that the triangular tip moves not only backward but also forward. Has been prevented. Therefore, when the cutting tool 201 is returned from the longitudinal feed after grooving or the front cutting edge 21 is moved back and forth, the insert 101 is held in the holder 200 no matter how much friction with the groove wall surface increases. It can be surely prevented from falling out and falling off.

  In the above example, as a means against the external force in the lateral direction, the front cutting edge is formed on the outer peripheral surface portion between the adjacent front cutting edges 21 of the outer peripheral surface of the polygonal plate 10 forming the cutting insert 101. In the present invention, the concave grooves 33 extending in the direction between the two are described. However, in the present invention, instead of the concave grooves 33, as shown in FIG. Good. The cross section of the ridge 35 may be, for example, a trapezoidal mountain shape of the seating portion 230 and the pressing portion 260 of the presser in the above example. And in such a case, the cross-sectional shape of the lower part of the seating part 230 in the holder 200 which is a mating counterpart, or the pressing part 260 of the presser tool, conversely, the concave groove that fits into the ridge 35. Just keep it as. In addition, what is necessary is just to make the cross section of these ditch | grooves or a protruding item | line into the thing of appropriate cross-sectional shapes, such as V shape and trapezoid.

  In the above example, the case of a triangular chip has been described. However, the polygon in the present invention is not limited to this, and can be embodied as a polygon having more than four corners. . FIG. 10 and FIG. 11 show an example thereof, which is a pentagonal cutting insert 501. This cutting insert 501 is formed by forming a front cutting edge 21 at its five corners 20 on the basis of a regular pentagonal plate 10. FIG. 11 is embodied as a cutting tool 601 formed by clamping the holder 200. In this case, since the number of corners 20 is large, further cost reduction is expected. In addition, in the thing of FIG. 11, the ditch | groove 33 extended in the direction between the front cutting edges 21 in the outer peripheral surface part between adjacent front cutting edges 21 among the outer peripheral surfaces of the polygonal board which makes the cutting insert 501. FIG. However, it may be a ridge instead. In this case, since there are five cutting edges, the inclination angle of the seating surface 230 of the holder 200 that is positioned forward and inclined rearward is smaller than that of the triangular tip. Still, the same effect as in the above example can be obtained, such that the cutting insert 501 is structurally prevented from slipping forward due to the inclination angle. That is, this is different in the number of corners and the difference as described above based on the difference, but there is no difference from the above example, so the same or the same in the corresponding part Only the reference numerals are given, and other explanations are omitted.

  The cutting insert and further the cutting tool in the present invention are not limited to those in each of the above-described examples, and can be appropriately changed and embodied without departing from the gist thereof. That is, the cutting insert and the cutting tool can be embodied as having an appropriate size, shape, and structure according to the width of the groove to be processed, the grooving depth, and the like. Further, in the above example, the case of grooving on the outer peripheral surface has been described, but it can also be applied to grooving on the end face. It is obvious that the cutting insert can be embodied as a known material.

DESCRIPTION OF SYMBOLS 10 Polygonal plate 11 Main surface 20 of plate 20 Corner 21 Front cutting edge 21b Edge 31 in front cutting edge Peripheral surface part 33 Groove 35 Projection 101,501 Cutting insert (triangular tip)
T1 Plate thickness H1 Blade width 200 Holder 201, 601 Cutting tool 215 Holder tip 230 Seating section 250 Presser 260 Pressing section

Claims (3)

A polygonal plate having at least three corners, the cutting insert having a front cutting edge extending at at least the three corners in which the cutting edge ridge extends in the thickness direction of the plate,
The front cutting edge is provided such that the blade width in the thickness direction of the plate is larger than the thickness of the plate, and each edge of the front cutting edge is located outward from each main surface of the plate. And
A cutting insert characterized in that a concave groove or a ridge extending in a direction between the front cutting edges is provided in each outer peripheral surface portion between adjacent front cutting edges in the outer peripheral surface of the plate.   The polygon has at least three rotationally symmetric polygons in its contour, and has the front cutting edge at the corner of the polygon for the number of rotational symmetry. The cutting insert according to 1. A cutting tool in which the cutting insert according to claim 2 is clamped to a holder,
The holder includes a clamp portion for clamping the cutting insert at a tip portion thereof, and the clamp portion includes the concave groove or the two of the outer peripheral surface portions of the cutting insert. The seat has two seating portions that can be fitted in the front and rear positions, and the two seating portions are arranged in front so that the longitudinal movement of the cutting insert in the clamp portion can be restricted. Is inclined to the rear and the rear one is inclined to the front,
Separately from the holder, in the fitting state of the concave groove or the ridge in the two outer peripheral surface portions to the two seating portions, the concave groove or the ridge in the other outer peripheral surface portion. And a pressing tool with a pressing portion configured to press and clamp the cutting insert toward the two seating portions in the fitted state. And
The cutting insert has the two seating portions fitted with the concave grooves or the ridges in the two outer peripheral surface portions of the cutting insert, and the pressing portion of the presser is the other one. Are fitted in the concave grooves or the ridges in the two outer peripheral surface portions, and in the fitted state, the presser clamps and clamps the cutting insert toward the two seating portions. A cutting tool characterized by

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