JP2006187813A - Cutting insert and cutting tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting insert of a negative type, which has a cutting edge formed of an ultra-high pressure sintered body layer or a cubic boron nitride sintered body layer containing cubic boron nitride as a main component, on both front and rear surfaces of a cutting insert main body, wherein the cutting insert can be stably secured onto a flat seat surface of a pocket formed in an ordinary holder without incurring degradation in the strength of the cutting insert main body. <P>SOLUTION: In formation of the cutting insert, a cutting edge combined body 21 which is obtained by sintering a two-layer structure consisting of a CBN layer 23 and a cemented carbide layer 22 in one body, is brazed to a seat surface 6 of a recess formed in each of the front and rear surfaces 4 of the cutting insert main body 3 by seating the CBN layer 23 on the seat surface 6. Then part of the cemented carbide layer 22 is removed by grinding out of each cutting edge combined body 21 such that the CBN layer 23 functions as a cutting edge 25 and the cemented carbide layer 22 functions as a breaker 26. Further an upper surface of the breaker 26 is formed so as to be flush with a cutting face 4 of the cutting insert main body 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is a negative type cutting insert having a plate shape and having cutting edges on both the front and back surfaces thereof, a cutting insert suitable for cutting a high-hardness work material, a cutting tool formed by fixing the cutting insert to a holder, and the like It relates to a cutting tool.

  The ultra high pressure sintered body has much superior wear resistance compared to conventional cutting tool materials made of cemented carbide, etc., so according to cutting inserts and tools with this cutting edge, The cut work material can also be cut with high efficiency and high efficiency. For this reason, an ultra-high pressure sintered body or cubic boron nitride sintered body containing cubic boron nitride as a main component is machined on cutting inserts and cutting edges of cutting tools used for cutting (working) hard materials. It is used depending on the material. Such an ultra-high pressure sintered body or cubic boron nitride sintered body (hereinafter, also referred to as an ultra-high pressure sintered body, a CBN sintered body, or simply CBN) mainly composed of cubic boron nitride is itself Because it is extremely expensive, cutting inserts (for example, throw-away inserts) and cutting tools are fixed to the cutting insert body (chip base material) or cutting tool holder (shank) as a composite for cutting edges integrated with cemented carbide. Then, it is used by forming a cutting edge in the ultra-high pressure sintered body. On the other hand, since the ultra-high pressure sintered body is a high-hardness material and an extremely difficult-to-cut material, it is extremely difficult to form a breaker in itself to improve the chip disposal. Under these circumstances, a composite with a sandwich structure (compact blank) in which a super-high-pressure sintered body layer is sandwiched between cemented carbide layers from both sides is used as a tool holder through the cemented carbide layer. After brazing, the surface cemented carbide layer is scraped to form a cutting edge with the ultra-high pressure sintered body layer, and the cemented carbide layer remaining on the surface is used as a breaker. Yes (Patent Document 1).

The bite described in Patent Document 1 has a sandwich type compact blank in which a cemented carbide layer is integrally provided on both sides of a sintered layer of diamond or CBN, fixed to a holder, and is cut out from the sandwich type compact blank. A cutting edge portion having a rake face and a flank surface formed in the sintered layer, and a chip breaker portion which is cut out from the cemented carbide layer on the rake face side and has a curved surface continuous to the rake face on the front face thereof; The sandwich type compact blank consisting of is used. Such a cutting edge structure of a cutting tool can also be applied to a cutting insert such as a throw-away tip. However, when this is applied as it is to a negative type cutting insert having a plate shape and having cutting edges on both front and back surfaces, there are the following problems.
Japanese Utility Model Publication No. 61-92502

  In the cutting tool of Patent Document 1, the compact blank (hereinafter referred to as a composite for cutting edge) is such that the upper surface of the cemented carbide layer on the rake face side forming the breaker is higher than the rake face of the holder that is the cutting tool body. It is formed so as to be (raised). Therefore, it is difficult to apply such a bite structure to a negative type cutting insert having cutting edges on both front and back surfaces. That is, in the throw-away type tool for fixing a normal negative type cutting insert to the holder, the seating surface (or shim seat) of the pocket for fixing the cutting insert in the holder is flat. If the surface is higher than the rake face (projects), the cemented carbide layer located on the back side to be seated on the seat surface of the holder pocket needs to project outward from the seat surface. However, the fixing of the cutting insert in such a form cannot obtain the stable fixing.

  However, it is also difficult to make the surface (upper surface) of the cemented carbide layer located on the rake face side in the cutting edge composite the same as or lower than the rake face of the cutting insert body. This is because in order to do this, the recess for fixing the cutting blade composite in the cutting insert body must be deepened, but in the negative type cutting insert in which the recess is provided on both the front and back sides of the main body, This is because the thickness of the portion sandwiched between the concave portions on both sides of the main body is reduced, leading to insufficient strength of the main body itself.

  The present invention has been made in view of these problems, and is a negative type cutting having a cutting edge made of an ultra-high pressure sintered body layer or a cubic boron nitride sintered body layer mainly composed of cubic boron nitride on both front and back surfaces. It is an object of the present invention to provide an insert that can be stably fixed to a flat seating surface of a pocket in a normal holder without causing a decrease in strength of a cutting insert body.

In order to achieve the above object, the present invention according to claim 1 is a negative type cutting insert having a plate shape and having cutting edges on both front and back surfaces thereof,
A cutting blade composite comprising an ultra-high pressure sintered body layer or a cubic boron nitride sintered body layer mainly composed of cubic boron nitride and a cemented carbide layer integrally fired in a two-layer structure, a cutting insert Brazing in such a manner that the ultra-high pressure sintered body layer mainly composed of cubic boron nitride or the cubic boron nitride sintered body layer side is seated on the seating surface of each recess formed on the front and back surfaces of the main body. And
Of the composites for each cutting edge, the ultra-high pressure sintered body layer or the cubic boron nitride sintered body layer mainly composed of cubic boron nitride has a cutting edge, and at least the cemented carbide layer has a breaker. So that at least a part of each of the composites for cutting edges is removed, and the upper surface of each breaker is formed to be the same as or lower than the rake face of the cutting insert body itself. It is the cutting insert characterized by being made.

The present invention according to claim 2 is a negative type cutting insert having a plate shape and having cutting edges on both front and back surfaces thereof,
A cutting blade composite comprising an ultra-high pressure sintered body layer or a cubic boron nitride sintered body layer mainly composed of cubic boron nitride and a cemented carbide layer integrally fired in a two-layer structure, a cutting insert Brazing in such a manner that the ultra-high pressure sintered body layer mainly composed of cubic boron nitride or the cubic boron nitride sintered body layer side is seated on the seating surface of each recess formed on the front and back surfaces of the main body. And
Of the composites for cutting edges, the ultra-high pressure sintered body layer or cubic boron nitride sintered body layer mainly composed of cubic boron nitride forms a cutting edge and the cemented carbide layer forms a breaker. Thus, at least a part of the cemented carbide layer is removed, and the upper surface of each breaker is formed to be the same as the rake face of the cutting insert body itself or lower than the rake face. It is the cutting insert characterized by this.

The present invention according to claim 3 is a negative type cutting insert having a plate shape and having cutting edges on both front and back surfaces thereof,
A cutting blade composite comprising an ultra-high pressure sintered body layer or a cubic boron nitride sintered body layer mainly composed of cubic boron nitride and a cemented carbide layer integrally fired in a two-layer structure, a cutting insert Brazing in such a manner that the ultra-high pressure sintered body layer mainly composed of cubic boron nitride or the cubic boron nitride sintered body layer side is seated on the seating surface of each recess formed on the front and back surfaces of the main body. And
Of the composites for each cutting edge, the ultra-high pressure sintered body layer or the cubic boron nitride sintered body layer mainly composed of cubic boron nitride forms a cutting edge, the cemented carbide layer, and the cubic The cemented carbide layer and the cubic boron nitride as the main component so that at least a part of each of the ultra-high pressure sintered body layer or the cubic boron nitride sintered body layer mainly composed of crystalline boron nitride forms a breaker And removing at least a part of each of the ultra-high pressure sintered body layer and the cubic boron nitride sintered body layer, and the upper surface of each breaker is the same as the rake face of the cutting insert body itself or from the rake face It is the cutting insert characterized by being formed so that it may be located in low level.

  The present invention described in claim 4 is the cutting insert according to any one of claims 1 to 3, wherein the cutting insert body is made of cemented carbide. And this invention of Claim 5 is a cutting insert of any one of Claims 1-4 by which the chamfer was attached | subjected to the said cutting blade. Furthermore, the present invention described in claim 6 is characterized in that a coating layer (coating layer) is formed on the surface of at least the exposed portion of the cemented carbide layer forming the composite for cutting edges. It is a cutting insert given in any 1 paragraph of 1-5. In the invention according to claim 7, the coating layer is made of any one of titanium nitride, titanium carbonitride, titanium nitride aluminum, titanium carbide, and aluminum oxide, or a combination thereof. The cutting insert according to claim 6. Moreover, this invention of Claim 8 fixes the cutting insert of any one of Claims 1-7 to the seat surface for cutting insert fixation in a holder directly or via a shim sheet. It is a cutting tool characterized by comprising.

  According to the first to fourth aspects of the present invention, since the upper surface of the breaker is formed to be the same as or lower than the rake face of the cutting insert body, the breaker is attached to the holder pocket as a cutting insert. When it is made into a bite, it can be stably fixed to the flat seating surface of the pocket without any problem. In addition, even in such a configuration, since each of the cutting edge composites has a two-layer structure, the thickness of each of the cutting edge composites can be made smaller than that of a three-layer structure. In the same corner, the reduction in the thickness of the cutting insert main body itself sandwiched between the recesses formed on both sides thereof can be reduced, so that the strength of the cutting insert can be prevented from lowering. The ultrahigh pressure sintered body (layer) in the present invention is an ultrahigh pressure sintered body (layer) or a cubic boron nitride sintered body (layer) mainly composed of cubic boron nitride.

  According to the fifth aspect of the present invention, since the chamfer (negative land) is attached to the cutting edge, the strength can be increased. That is, a cutting edge made of an ultra-high pressure sintered body has low toughness and is likely to be chipped, but by imparting chamfering in this way, chipping resistance or cutting edge strength can be increased. What is necessary is just to set the width | variety seen from the rake face side of this chamfering according to processing conditions. Incidentally, the width of such a chamfer is generally about 0.05 to 0.20 mm. However, when there is a demand for heavy cutting, this does not provide sufficient strength, so about 0.30 mm. It is good to secure. The angle formed with the chamfered rake face is usually about 15 to 35 degrees. And such chamfering improves cutting edge strength, so that the width | variety (width on the side of a rake face) and this chamfering angle are large. The chamfering may be formed by grinding or polishing (hereinafter also referred to as polishing). Then, as in the present invention according to claim 6 or 7, in the case where the coating layer is formed, the super high pressure sintered body layer or the cubic boron nitride sintered body layer mainly composed of cubic boron nitride is used. Since the wear resistance of the breaker formed by the cemented carbide layer having relatively low wear resistance can be improved, the life of the cutting insert can be extended.

  The embodiment which actualized the cutting insert which concerns on this invention is described in detail with reference to FIG. As shown in FIG. 1, the cutting insert 1 according to the present embodiment is a negative type cutting insert (square tip) having a flat plate shape with a certain thickness in a plan view, and having a hole 2 for clamping. . In such a cutting insert 1, in this example, the cutting blade composite 21 is fixed to the upper and lower surfaces 4 and 4 of each of the opposing corners C of the cemented carbide cutting insert body 3 (see FIG. 2). . In other words, the opposing corners C of the cutting insert body 3 are arcuate with a predetermined radius in plan view, and the upper and lower surfaces 4 and 4 of each of them have a notch-shaped recess that forms a substantially triangular shape in plan view. 5 is formed (see FIG. 4), and each of the recesses 5 has a cutting edge composite (hereinafter also simply referred to as a composite) having the same size and shape as the triangle in plan view (viewed from the side of each rake face). 21 is brazed. The cutting blade composite 21 is integrally sintered in two upper and lower layers of a cemented carbide layer 22 and a CBN sintered body layer 23, and then the cutting blade 25 is formed as described below. Is formed. The composite 21 has a surface on the CBN sintered body layer 23 side seated on the seating surface 6 of the recess 5 and a back surface 24 in contact with the wall surface 7 rising from the seating surface 6. It is brazed (fixed) by a Ti-based active row under an inert atmosphere such as Ar. When the wall surface 7 has an overhang at a slight inclination angle or is raised vertically from the seating surface 6, a broken line in the enlarged view of FIG. It is assumed that the escape radius 7a is formed as shown in FIG. Although not shown, in any case, the gap formed between the back surface 24 and the wall surface 7 is filled with brazing. In this embodiment, the composite 21 is brazed and fixed to each of the four recesses 5 in the main body 3, but since all of them have the same structure, only one part thereof will be described below.

  In the cutting insert 1 of the present embodiment, after the cutting blade composite 21 is brazed as described above, the CBN sintered body layer 23 which is an ultra-high pressure sintered body layer is included in the cutting blade composite 21. A portion of the cemented carbide layer 22 close to the cutting edge 25 is polished with a constant width and a constant cross-sectional shape so that the cemented carbide layer 22 forms a breaker 26 (or a sectional shape) (or Laser processing). That is, as shown in FIG. 4, the composite for cutting edge 21 has a constant thickness of two upper and lower layers of a cemented carbide layer 22 and a CBN sintered body layer 23 before brazing. After attaching, a part of the cemented carbide layer 22 is removed by polishing to form the cutting edge 25 and the breaker 26. The breaker 26 is finished so that the upper surface thereof is the same as the upper and lower surfaces 4 and 4 that are the rake surfaces of the cutting insert body 3 itself. The breaker 26 forms a curved inclined wall 26a that is concave in a cross-sectional view, and is continuous with a rake face 25a formed by the CBN sintered body layer 23 (see FIG. 2). In this embodiment, a curved surface that is concave along the outer peripheral edges (ridge lines between the rake face and the flank face) of the upper and lower surfaces 4 and 4 of the cutting insert body 3 including the cutting blade composite 21. The entire circumference of the cutting insert 1 is polished so as to form the inclined wall 26a.

  Thereby, in this embodiment, the rake face 25a composed of the CBN sintered body layer 23 is exposed in a predetermined minute width (for example, 0.30 mm) in a plan view, and the tip thereof forms the cutting edge 25. The alloy layer 22 forms a breaker 26. The width of the rake face 25a made of the CBN sintered body layer 23 may be set in consideration of processing conditions such as the hardness of the work material and the cutting feed amount. The front flank 28 of the cutting edge 25 and the left and right lateral flank 29 sandwiching the corner C are both polished and finished to be flush with the side surface 8 of the main body 3. Further, in this embodiment, an inclined chamfer (negative land) is formed with a very small width with respect to the cutting edge 25 formed by the cutting edge composite 21. In addition, the radius in the planar view of the corner C of the cutting insert 1 which makes the cutting edge 25 is set to about 0.40 mm to 1.20 mm.

  As described above, the cutting insert 1 of the present example is formed so that the upper surface of the breaker 26 is flush with the upper and lower surfaces 4 and 4 forming the rake face of the cutting insert body 3. 5-7, it is attached to the flat seating surface 103 of the pocket 102 of the holder 101 via a fixing means such as a clamp rod 108 of a fixing screw 107 via a shim sheet 105 of a certain thickness, for example. Byte 110. In this case, the cutting insert 1 is stably fixed to the pocket 102 of the holder 101 without any problem. 5-7, the case where it fixed to the pocket 102 of the holder 101 via the shim sheet 105 was demonstrated, However, The shim sheet 105 does not need to be.

  Since the cutting blade composite 21 on the upper and lower surfaces 4 and 4 has a two-layer structure, the cutting insert 1 described above can have a smaller thickness than that of a three-layer structure. For this reason, when providing the recessed part 5 in both surfaces in the same corner C of the cutting insert main body 3, and brazing the composite 21 for cutting edges, the thickness of the cutting insert main body 3 pinched | interposed into the both seating surfaces 6 of the recessed part 5 Since the reduction in the thickness of the cutting insert 1 can be reduced, the strength of the cutting insert 1 can be prevented from being reduced. In this embodiment, the case where the upper surface of the breaker 26 is formed so as to be flush with the rake face of the cutting insert main body 3 is illustrated, but the upper surface of the breaker 26 is positioned lower than the rake face of the cutting insert main body 3. It may be formed as follows.

  In this embodiment, the cutting edge 25 made of the CBN sintered body layer 23 is chamfered, so that the strength is increased. The chamfering may be R chamfering instead of inclined chamfering. Although not shown, for example, at least the surface of the cemented carbide layer 22 of the exposed portion of the cutting blade composite 21 is made of titanium nitride, titanium carbonitride, titanium nitride aluminum, titanium carbide, or aluminum oxide. It is preferable to form a coating layer made of either one because the wear resistance of the surface of the same part due to chips that collide with the breaker 26 made of the cemented carbide layer 22 is improved. However, a coating layer may be formed on the entire cutting insert 1. Such a coating layer may be formed by physical vapor deposition or the like.

  Now, another embodiment of the cutting insert according to the present invention will be described with reference to FIGS. However, in the cutting insert 31 of the present example, the above-described cutting insert 1 was formed by removing only the cemented carbide layer 22 in the composite 21 by polishing, and in addition to the removal, The only difference is that part of the CBN layer 23 is also removed by polishing and the rake face 25a of the CBN layer 23 is widened to increase the distance from the tip of the cutting edge 25 to the breaker 26. Since the points are the same as in the above embodiment, the same portions are denoted by the same reference numerals, and detailed description thereof is omitted. That is, this embodiment is suitable for processing conditions with a large feed amount.

  In the above, the composite body 21 made of cemented carbide and having a CBN layer on both rake faces 4 and 4 is provided at two opposing corners of a square plate-shaped cutting insert body 3 having a constant thickness. Although described, the present invention can be widely applied to negative type cutting inserts having cutting edges on both the front and back sides regardless of the number of corners or the shape of the cutting insert body 3. Further, the present invention can be similarly realized not only in a square cutting insert but also in a circular cutting insert.

  In the above description, the cutting insert body is made of cemented carbide. However, in the present invention, other than the above, there is no problem in the integration of the ultra-high pressure sintered body, such as high-speed steel, cermet, or ceramic. May be. Furthermore, in the above description, the present invention is embodied with a clamp hole (through hole). However, because of the so-called clamp-on method, the present invention can also be embodied in a cutting insert without such a hole 2.

The top view and principal part enlarged view of embodiment which actualized the cutting insert which concerns on this invention. The AA line expanded sectional view in FIG. 1, and its partial expanded view. The principal part perspective view of the cutting insert of FIG. 1, and its partial enlarged view. The perspective view of the principal part of a cutting insert main body, and the composite body for cutting blades before brazing. The side view of the cutting tool formed by fixing the cutting insert of FIG. 1 in the pocket of the holder. The figure which looked at FIG. 5 from the rake face side. FIG. 6 is a left side view of FIG. 5. The principal part enlarged plan view of another form which actualized the cutting insert which concerns on this invention. BB expanded sectional view in FIG. The principal part expansion perspective view of FIG.

Explanation of symbols

1,31 Cutting insert 3 Cutting insert body 4, 4 Surface of cutting insert body (both sides)
5 Cutting insert body recess 6 Recess seating surface 21 Cutting blade composite 22 Cemented carbide layer 23 Ultra high pressure sintered body layer or cubic boron nitride sintered body layer 25 mainly composed of cubic boron nitride Cutting edge 26 Breaker 101 Holder 110 Byte C Corner

Claims (8)

It is a negative type cutting insert that has a plate shape and has cutting edges on both front and back surfaces,
A cutting blade composite comprising an ultra-high pressure sintered body layer or a cubic boron nitride sintered body layer mainly composed of cubic boron nitride and a cemented carbide layer integrally fired in a two-layer structure, a cutting insert Brazing in such a manner that the ultra-high pressure sintered body layer mainly composed of cubic boron nitride or the cubic boron nitride sintered body layer side is seated on the seating surface of each recess formed on the front and back surfaces of the main body. And
Of the composites for each cutting edge, the ultra-high pressure sintered body layer or the cubic boron nitride sintered body layer mainly composed of cubic boron nitride has a cutting edge, and at least the cemented carbide layer has a breaker. So that at least a part of each of the composites for cutting edges is removed, and the upper surface of each breaker is formed to be the same as or lower than the rake face of the cutting insert body itself. Cutting insert characterized by being made. It is a negative type cutting insert that has a plate shape and has cutting edges on both front and back surfaces,
A cutting blade composite comprising an ultra-high pressure sintered body layer or a cubic boron nitride sintered body layer mainly composed of cubic boron nitride and a cemented carbide layer integrally fired in a two-layer structure, a cutting insert Brazing in such a manner that the ultra-high pressure sintered body layer mainly composed of cubic boron nitride or the cubic boron nitride sintered body layer side is seated on the seating surface of each recess formed on the front and back surfaces of the main body. And
Of the composites for cutting edges, the ultra-high pressure sintered body layer or cubic boron nitride sintered body layer mainly composed of cubic boron nitride forms a cutting edge and the cemented carbide layer forms a breaker. Thus, at least a part of the cemented carbide layer is removed, and the upper surface of each breaker is formed to be the same as the rake face of the cutting insert body itself or lower than the rake face. Cutting insert characterized by that. It is a negative type cutting insert that has a plate shape and has cutting edges on both front and back surfaces,
A cutting blade composite comprising an ultra-high pressure sintered body layer or a cubic boron nitride sintered body layer mainly composed of cubic boron nitride and a cemented carbide layer integrally fired in a two-layer structure, a cutting insert Brazing in such a manner that the ultra-high pressure sintered body layer mainly composed of cubic boron nitride or the cubic boron nitride sintered body layer side is seated on the seating surface of each recess formed on the front and back surfaces of the main body. And
Of the composites for each cutting edge, the ultra-high pressure sintered body layer or the cubic boron nitride sintered body layer mainly composed of cubic boron nitride forms a cutting edge, the cemented carbide layer, and the cubic The cemented carbide layer and the cubic boron nitride as the main component so that at least a part of each of the ultra-high pressure sintered body layer or the cubic boron nitride sintered body layer mainly composed of crystalline boron nitride forms a breaker And removing at least a part of each of the ultra-high pressure sintered body layer and the cubic boron nitride sintered body layer, and the upper surface of each breaker is the same as the rake face of the cutting insert body itself or from the rake face A cutting insert characterized by being formed to be positioned at a low level.   The cutting insert according to any one of claims 1 to 3, wherein the cutting insert body is made of cemented carbide.   The cutting insert according to claim 1, wherein the cutting edge is chamfered.   The cutting insert according to any one of claims 1 to 5, wherein a coating layer is formed on a surface of at least an exposed portion of the cemented carbide layer forming the composite for cutting edge.   The cutting insert according to claim 6, wherein the coating layer is made of any one of titanium nitride, titanium carbonitride, titanium nitride aluminum, titanium carbide, and aluminum oxide, or a combination thereof. .   A cutting tool comprising: the cutting insert according to any one of claims 1 to 7 fixed to a seating surface for fixing a cutting insert in a holder directly or via a shim sheet.

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