JP5612382B2 - Cutting insert - Google Patents

Description

  The present invention relates to a cutting insert, and more particularly to a cutting insert that exhibits good performance for milling.

  Conventionally, in a cutting insert for milling, from the viewpoint of suppressing damage to the cutting edge, between the main cutting edge for cutting the work material and the wiping edge for smoothing the surface of the work material generated by the cutting. In addition, a secondary cutting edge having a larger outer cutting edge angle than the main cutting edge is formed. For example, in Patent Document 1, in a negative type cutting insert, the angle formed between the main cutting edge and the wiping edge is 45 °, and the outer cutting edge angle between the main cutting edge and the wiping edge is larger than that of the main cutting edge. A cutting insert in which an intermediate cutting edge 11 (sub cutting edge) is formed is disclosed.

JP 2008-6579 A

  However, in such a cutting insert, the back component force at the time of cutting at the secondary cutting edge is increased, so that vibration (chatter phenomenon) is likely to occur at the time of cutting, and the quality of the finished surface may be deteriorated. Further, in the conventional cutting insert, there is a case where thermal cracks are generated in the cutting edge depending on the cutting form and chipping occurs, which is particularly remarkable in high-speed cutting of gray cast iron.

  One of the objects of the present invention is to provide a cutting insert capable of forming a good finished surface. Another object of the present invention is to provide a cutting insert that can be suitably used for, for example, high-speed cutting conditions of gray cast iron.

The cutting insert according to the present invention is a negative type in which a coating layer is formed on the surface of a cemented carbide substrate, the coating layer has a total thickness of 9 to 25 μm, and a TiCN layer, an Al ₂ O ₃ layer, and a surface layer from the substrate side. Ti (C _x N _y O _z ) _a (x + y + z = 1, 0 ≦ x ≦ 0.6, 0 ≦ y ≦ 0.6, 0.2 ≦ z ≦ 0.8, 1.0 ≦ a ≦ 1. 7) are provided with, is the cutting edge formed at the intersection ridgeline portion between the upper surface and the side surface, the main cutting edge, an outer peripheral cutting edge angle than the outer peripheral cutting edge angle of the main cutting edge is large minor cutting edge, the A plurality of sets of wiping blades that are inclined upward (opposite to the seating surface side) as they approach the sub-cutting blade are formed as one set, and a land portion is formed at a position following the cutting blade on the rake face. The secondary cutting edge land part following the secondary cutting edge approaches the lower surface as it goes toward the center of the upper surface. Inclined.

  Here, it is desirable that the cutting blade is formed with a honing of 0.05 to 0.09 mm when viewed on the rake face side.

  In addition, the main cutting edge land portion is inclined so as to approach the lower surface toward the center portion of the upper surface, and the inclination angle of the sub cutting blade land portion is a main cutting edge corresponding to the main cutting edge. It is desirable that the angle is larger than the angle of the blade land portion.

  Furthermore, it is desirable that an angle difference between the inclination angle of the main cutting edge land portion and the inclination angle of the sub cutting edge land portion is 3 to 10 °.

  Further, it is preferable that the wiping blade is formed so as to protrude above the main cutting edge, and the sub cutting edge is inclined so as to approach the lower surface from the wiping edge toward the main cutting edge.

  Furthermore, a curved first corner cutting edge is provided between the main cutting edge and the sub cutting edge, and a curved second corner cutting edge is provided between the sub cutting edge and the wiping edge. It is desirable to have.

  Moreover, it is desirable that the curvature radius of the first corner cutting edge is larger than the curvature radius of the second corner cutting edge in a top view.

  According to the cutting insert of the present invention, it is possible to reduce the back component force at the time of cutting by inclining the sub cutting edge land portion corresponding to the sub cutting edge having a large outer peripheral cutting edge angle downward. Therefore, vibration during cutting is suppressed, and a cut product having a good finished surface can be obtained. And even if the secondary cutting edge is sharp and thermal cracks are generated in this secondary cutting edge, it is easy to chip, so the generation and progression of thermal cracks is slow. Since the chipping resistance and wear resistance of the coating layer are good, the cutting tool has a long life.

  According to the cutting insert which concerns on other embodiment of this invention, the width | variety in the edge part by the side of the main cutting edge is enlarged among the sub cutting edge land parts, and an inclination angle is made small, and the main cutting edge among sub cutting edges. Increase the strength of the side. Moreover, the width | variety in the edge part by the side of a wiping edge is reduced and the inclination angle is enlarged among the secondary cutting edge lands, and the sharpness by the side of the wiping edge among the auxiliary cutting edges is improved. In this way, the secondary cutting edge has a good balance between the strength required for the main cutting edge and the sharpness required for the wiping edge, so when using general purpose cutting, the secondary cutting edge is used in addition to the main cutting edge. The finished surface can be smoothed by cutting with a wiping blade. On the other hand, at the time of high feed (at the time of high-speed feed cutting), it is possible to cut with only the main cutting edge and smooth the finished surface with the sub cutting edge instead of the wiping edge.

1 is an overall perspective view showing a cutting insert according to a preferred embodiment of the present invention. (A) is a top view of the cutting insert shown in FIG. 1, (b) is the side view. It is the elements on larger scale of the cutting insert shown to Fig.2 (a). (A) is an AA line schematic sectional drawing of FIG. 3, (b) is a BB schematic sectional drawing of FIG. It is a side view which shows the cutting tool which mounted | wore the holder with the cutting insert of FIGS. It is the elements on larger scale of the cutting tool shown in FIG.

  Hereinafter, a first embodiment of a cutting insert according to the present invention (hereinafter abbreviated as “insert”) will be described in detail with reference to FIGS. As shown in FIG. 1, the insert 1 includes a substantially polygonal plate-like main body. The shape of the main body is not particularly limited as long as it is a shape normally used by those skilled in the art such as a triangle, a quadrangle, a pentagon, a hexagon, an octagon, and the like in a top view. As the number of cutting blades that can be used increases, the contact area of the seating surface increases, and the binding force of the insert 1 improves. On the other hand, as the number of corners increases, the length of one side becomes shorter, and a small-diameter insert cannot handle a large depth of cut, so the balance needs to be adjusted. In the present embodiment, a substantially pentagonal shape having five long sides is used.

  The main body also has an upper surface 2 that functions as a rake surface, a lower surface 3 that functions as a seating surface, and a side surface 4 that is continuous with the upper surface 2 and the lower surface 3 and functions as a flank. The insert 1 is a negative type insert that can use both the upper surface 2 and the lower surface 3 as rake surfaces. Specifically, the side surface 4 is connected perpendicularly to the upper surface 2 and the lower surface 3. That is, the insert 1 is an insert with 10 corners. In the insert of the present invention, the side surface 4 may have a clearance angle, and the side surface 4 may have a concave curved surface.

  A cutting edge 5 is formed at the intersection of the upper surface 2 and the side surface 4. Further, on the upper surface 2 corresponding to the rake face, a mounting screw contact portion 8 penetrating the main body portion from the upper surface 2 toward the lower surface 3 is formed. The attachment screw contact portion 8 is formed at the center of the upper surface 2.

  The cutting blade 5 formed at the intersection of the upper surface 2 and the side surface 4 includes a main cutting blade 51, a wiping blade 52, and a sub cutting blade 53 disposed between the main cutting blade 51 and the wiping blade 52. Have Further, in the present embodiment, as shown in FIG. 2A, a first corner cutting edge 54 is formed between the main cutting edge 51 and the auxiliary cutting edge 53, and the auxiliary cutting edge 53 and the wiping edge 52. A second corner cutting edge 55 is formed between the two.

  The main cutting edge 51 is a blade that plays a main role in generating chips in the cutting action. The main cutting edge 51 is configured to be the longest of the cutting edges 5 (51 to 55). The shape of the main cutting edge 51 is not particularly limited. The main cutting edge 51 may be linear or curved (arc-shaped) when viewed from above. From the viewpoint that the main cutting edge 51 easily has an axial rake with respect to the central axis of rotation of the holder when the holder is mounted, the main cutting edge 51 is formed as shown in FIG. It is preferable to incline toward the seating surface as the distance from the blade 53 increases.

  In the present embodiment, the main cutting edge 51 is linear in a top view shown in FIGS. 1 and 2 (a). Further, the main cutting edge 51 is concave toward the lower surface 3 in a side view shown in FIG. 2 (b), and when the straight line connecting the both ends is drawn, the sweeping edge 52 from the side in contact with the auxiliary cutting edge 53. The straight line is inclined toward the lower surface 3 side toward the end side in contact with. A nick (groove) that divides the main cutting edge 51 may be provided in the middle of the main cutting edge 51 from the viewpoint of reducing cutting resistance.

  The wiping blade 52 is formed for the purpose of improving the finished surface roughness of the work material. The wiping blade 52 is linear in the top view shown in FIGS. 1 and 2 (a), and as it approaches the auxiliary cutting edge 53 in the side view shown in FIG. 2 (b), it moves upward (opposite to the seating surface side). ).

  The secondary cutting edge 53 is a cutting edge having a larger outer peripheral cutting edge angle than the main cutting edge 51. For example, the main cutting edge 51 reduces cutting resistance of the main cutting edge 51 or suppresses damage to the main cutting edge 51. It is arranged for the purpose of assisting the cutting with the blade 51. In the present specification, the “outer peripheral cutting edge angle” refers to the inclination angle of the cutting edge with respect to the rotation center axis S of the holder 90 when the insert 1 is attached to the holder 90. For example, as shown in FIG. 2A, the outer peripheral cutting edge angle of the main cutting edge 51 is an angle α formed between the line L parallel to the rotation center axis of the holder 90 and the main cutting edge 51 in the top view. Can be represented. Further, the outer peripheral cutting edge angle of the auxiliary cutting edge 53 can be represented by an angle β formed by the line L and the auxiliary cutting edge 53.

  For example, the outer peripheral cutting edge angle α of the main cutting edge 51 is set at about 0 ° to 60 °, and the outer peripheral cutting edge angle β of the auxiliary cutting edge 53 is set at about 60 ° to 80 °. In consideration of damage / deletion of the cutting edge 5, the outer peripheral cutting edge angle β of the auxiliary cutting edge 53 may be set to a size exceeding twice the outer peripheral cutting edge angle α of the main cutting edge 51. preferable. In addition, the sub cutting blade 53 should just be located between the main cutting blade 51 and the wiping blade 52, and may have a some sub cutting blade between both, for example.

  As shown in FIG. 2B, the secondary cutting edge 53 is preferably inclined downward as it goes from the wiping edge 52 to the main cutting edge 51 in a side view. In particular, the auxiliary cutting edge 53 preferably has an inclination angle such that it has a positive axial rake in a state where the insert 1 is attached to the holder.

  Here, as long as the main cutting edge 51 is configured to be the longest of the cutting edges 5, the lengths of the main cutting edge 51, the wiping edge 52, and the auxiliary cutting edge 53 are not particularly limited. For example, the ratio of the length of the main cutting edge 51 and the sub cutting edge 53 is set to be 2: 1 to 10: 1, preferably 2: 1 to 6: 1. Moreover, the ratio of the length of the wiping blade 52 and the sub-cutting blade 53 is set to be 1: 1 to 6: 1. Normally, when designing a negative type insert, the ratio of the length of the wiper blade and the auxiliary cutting blade is set to 1: 1.

  The first corner cutting edge 54 and the second corner cutting edge 55 are both curved when viewed from above, and the curvature radius of the first corner cutting edge 54 is larger than the curvature radius of the second corner cutting edge 55. It is formed to become. Thereby, the big fluctuation | variation of the thickness between the chips each generated from the main cutting edge 51 and the sub-cutting edge 53 is suppressed, and the shape of the chips can be controlled. The first corner cutting edge 54 and the second corner cutting edge 55 may be linear.

  As shown in FIGS. 1 and 2A, a land portion 6 is formed on the upper surface 2 along the cutting edge 5. That is, as shown in FIG. 3, land portions 61 to 65 are formed corresponding to the respective cutting edges 51 to 55. Specifically, the land portion 6 is a narrow band-shaped surface formed between the cutting edge 5 and the rake face, and the angle with respect to a line passing through the cutting edge 5 and perpendicular to the center axis of the insert is raked. A surface that is smaller than a surface. The land portion 6 is formed in order to strengthen the cutting edge strength of the cutting blade 5. In the present specification, the land portion that corresponds to the main cutting edge 51 is the main cutting blade land portion 61, the land portion that corresponds to the cleaning blade 52 is the cleaning blade land portion 62, and the secondary cutting edge. The land portion corresponding to the blade 53 is referred to as a sub-cut blade land portion 63. The land portion corresponding to the first corner cutting edge 54 is a first corner cutting edge land portion 64, and the land portion corresponding to the second corner cutting edge 55 is a second corner cutting edge land portion 65. That's it. In the insert 1, the cutting edge 5 is formed on the entire periphery of the edge portion when viewed from above, and the land portion 6 is formed on the inside thereof.

  What is necessary is just to set suitably about each width | variety of each land part 61-65 according to the cutting-edge intensity | strength of each cutting blade 51-55, and the cutting resistance applied at the time of cutting. At the time of cutting, from the viewpoint of controlling the size (thickness) of chips generated from each of the cutting edges 51 to 55, the ratio between the width of the main cutting edge land portion 61 and the width of the auxiliary cutting edge land portion 63 is 1: It is preferable to set it to be 0.7 to 1: 1.3. The ratio between the width of the main cutting edge land portion 61 and the width of the sub cutting edge land portion 63 may be substantially the same (about 1: 1).

  Here, the width of the land portion 6 refers to a distance in a direction perpendicular to the ridgeline of the cutting edge 5 in a top view. The width of the land portion 6 is the largest of the corresponding land portions. In the present embodiment, as shown in FIG. 4, the width W61 of the main cutting edge land portion 61 and the width W63 of the sub cutting edge land portion 63 have a relationship of W61 = W63. More preferably, the width of each of the land portions 61 to 65 is substantially constant.

  In this embodiment, as shown in FIG.4 (b), the sub-cutting blade land part 63 inclines below as it goes to the center part of the upper surface 2 shown by the arrow a direction. Thereby, the cutting resistance at the time of cutting can be reduced, and the back component force at the time of cutting can be reduced. Therefore, vibration during cutting is suppressed, and a good finished surface can be obtained. In the present embodiment, as will be described later, the secondary cutting edge land portion 63 is formed with an inclination angle θ1.

  The land portions 61, 62, 64, and 65 other than the secondary cutting edge land portion 63 may be flat, or may be inclined in a downward direction or an upward direction. .

  As shown in FIG. 4A, the main cutting edge land portion 61 is preferably inclined downwardly toward the central portion of the upper surface 2 from the viewpoint of reducing cutting resistance. The angle θ2 is preferably as large as possible. Thereby, a better finished surface can be obtained. On the other hand, it is preferable that the main cutting edge land portion 61 has a small inclination angle from the viewpoint of reinforcement of the main cutting edge 51.

  The sub cutting edge land portion 63 is preferably formed so that the inclination angle is larger than that of the main cutting edge land portion 61. In the case of an insert having two types of cutting blades having different outer peripheral cutting edge angles, such as the main cutting edge 51 and the sub cutting edge 53, the balance of the cutting force in each cutting edge is different from each other. According to the present embodiment, by having the configuration as described above, it is possible to maintain a good balance of the cutting force between the main cutting edge 51 and the sub cutting edge 53, and vibration (chatter phenomenon) occurs during cutting. Can be suppressed.

  More specifically, as shown in FIG. 4, the inclination angle of the secondary cutting edge land 63 with reference to a line L1 passing through the secondary cutting edge 53 and orthogonal to the central axis (not shown) of the insert 1 is θ1, When the inclination angle of the main cutting edge land portion 61 with reference to a line L2 that passes through the cutting edge 51 and is orthogonal to the center axis of the insert 1 is θ2, θ1 and θ2 have a relationship of θ1> θ2. The difference between θ1 and θ2 is preferably at least 3 °, more preferably 3 ° to 10 °.

  The main cutting edge land portion 61 and the auxiliary cutting edge land portion 63 are connected by the first corner cutting edge land portion 64 as described above. The inclination angle of the first corner cutting edge land portion 64 with reference to a line L3 (not shown) passing through the first corner cutting edge 54 and orthogonal to the center axis of the insert 1 is determined from the sub cutting edge land portion 63 to the main cutting edge land. It is formed so as to become smaller toward the portion 61. As a result, the chips are discharged stably without being irregularly deformed or divided. Specifically, the first corner cutting edge land portion 64 is formed to rise from the sub cutting edge land portion 63 toward the main cutting edge land portion 61 in a cross-sectional view.

  On the other hand, as shown in FIG. 1 and the like, a breaker groove 7 positioned corresponding to the main cutting edge 51 is formed on the upper surface 2. The breaker groove 7 is formed for the purpose of making it easier to curl chips generated from the main cutting edge 51. In FIG. 1, the breaker groove 7 has a concave shape.

Here, the material constituting the above-mentioned insert consists of a structure in which a coating layer is formed on the surface of the cemented carbide substrate. The coating layer has a total thickness of 9 to 25 μm, and the TiCN layer, Al ₂ O ₃ from the substrate side. Layer and surface layer Ti (C _x N _y O _z ) _a (x + y + z = 1, 0 ≦ x ≦ 0.6, 0 ≦ y ≦ 0.6, 0.2 ≦ z ≦ 0.8, 1.0 ≦ a ≦ 1.7). Desirable thickness of each layer is 5.0-12.0 μm for the TiCN layer, 3.0-12.0 μm for the Al ₂ O ₃ layer, surface layer Ti (C _x N _y O _z ) _a layer The desirable range is 0.01 to 0.2 μm. As a result, even in high-speed milling of gray cast iron that is susceptible to chipping due to thermal cracks occurring on the cutting edge, the generation and progression of thermal cracks are slow in the cutting insert of the present invention, and the chipping resistance and wear resistance of the coating layer are slow. Since the property is good, the cutting tool has a long life. In addition, the surface layer Ti (C _x N _y O _z ) _a layer generates a belag in the machining of gray cast iron, and therefore has good welding resistance on the surface of the coating layer and exhibits particularly excellent cutting performance. The Al ₂ O ₃ layer is preferably composed of α-type crystals.

Next, an embodiment in which the insert is mounted on a holder will be described in detail with reference to FIGS. As shown in FIG. 5, the cutting tool 90 (rolling tool) of the present embodiment includes a plurality of inserts 1 and a holder 91 on which the plurality of inserts 1 are mounted.

  Here, a plurality of insert pockets 92 are formed at the outer peripheral tip of the holder 91, and the insert 1 is attached to each outer peripheral position in each insert pocket 92. Specifically, the insert 1 is mounted such that the main cutting edge 51 is positioned on the outermost periphery with the upper surface (rake surface) 2 facing the front side in the rotation direction.

  For mounting, for example, the mounting screw 94 is inserted into the mounting screw contact portion 8 (screw hole) of the insert 1 and the mounting screw 94 is screwed into a female screw formed on the mounting surface 93 of the holder 91, or The mounting screw 94 is passed through the formed through hole, and tightened with a nut from the opposite side.

  Further, as shown in FIG. 6, the insert 1 that is a negative insert has a negative axial rake γ in a side view and is attached to the holder 91. As the axial rake γ, about 6 ° is appropriate. In the case of this embodiment, as shown in FIG. 2B, the main cutting edge 51 and the auxiliary cutting edge 53 are inclined downward as they move away from the wiping edge 52. Therefore, as shown in FIG. 6, the main cutting edge 51 and the sub cutting edge 53 have a positive axial rake with respect to the rotation center axis S of the holder 91. The main cutting edge 51 and the sub cutting edge 53 may have a negative axial rake with respect to the rotation center axis S of the holder 91. The cutting tool 90 is cut by the main cutting edge 51, the auxiliary cutting edge 53 and the wiping edge 52 by rotating the holder 91.

  The main component is tungsten carbide (WC) powder having an average particle diameter of 1.0 μm, 8.5% by mass of metallic cobalt (Co) powder having an average particle diameter of 1.2 μm, and tantalum carbide (TaC) having an average particle diameter of 1.1 μm. Insert the niobium carbide (NbC) powder having a mass of 0.8% by mass and an average particle size of 1.0 μm at a rate of 0.1% by mass and mixing, and press-molding the insert shape shown in FIGS. : PNMU1205ANER-GM), followed by binder removal treatment and firing in a 0.01 Pa vacuum at 1450 ° C. for 1 hour to produce a cemented carbide. Further, the rake face surface of each sample was polished by blasting, brushing or the like. Furthermore, the cutting edge processing (honing) of the magnitude | size shown in Table 1 was given to the produced cemented carbide alloy by brush processing. As a measuring method of honing, measurement was performed on a rake face with a projector.

  Next, various coating layers were formed on the cemented carbide by the CVD method under the film forming conditions shown in Table 1 and the layer configuration shown in Table 2. Then, the surface of the coating layer was brushed for 30 seconds from the rake face side, and sample No. 1 to 8 surface-coated cutting tools were produced. In addition, as a comparative example, the sample No. The sample on which the coating layer of No. 1 was formed was designated as Sample No. 9 to the insert having the basic shape of FIGS. 1 to 4 and the land being parallel to the seating surface. The sample on which the coating layer of No. 1 was formed was designated as Sample No. 10 was similarly evaluated.

  The obtained tool was observed with a scanning electron microscope, and the shape, average particle diameter (or average crystal width), and thickness of the crystals constituting each layer were estimated. The results are shown in Table 2.

そして、この切削工具を用いて下記の条件により、断続切削試験を行い、耐欠損性を評価した。結果は表３に示した。
評価方法：表面フライス切削加工
被削材： ＦＣ２５０（４穴）
切削速度： ３００ｍ／ｍｉｎ
切込み： １．５ｍｍ
送り： ０．３ｍｍ／ｔｏｏｔｈ
切削状態 ： 乾式

And the intermittent cutting test was done on condition of the following using this cutting tool, and fracture resistance was evaluated. The results are shown in Table 3.
Evaluation method: Surface milling work material: FC250 (4 holes)
Cutting speed: 300 m / min
Cutting depth: 1.5mm
Feeding: 0.3mm / tooth
Cutting state: Dry

表１〜３に示される結果から、最表層がＴｉＮ層からなる試料Ｎｏ．５では最表層が早期にチッピングが発生し、被覆層の総厚みが９μｍよりも薄い試料Ｎｏ．６では熱クラックが発生して欠損が発生し、最表層がＡｌ_２Ｏ_３層の試料Ｎｏ．７でも溶着が激しくて工具寿命が短く、最表層がＴｉ（Ｃ_ｘＮ_ｙＯ_ｚ）_ａ層のａが１よりも小さい試料Ｎｏ．８では最表層が早期にフレーキングが発生してベラーグの生成効果があまり見られなかった。また、インサート形状が本発明の範囲外の試料Ｎｏ．９ではチッピングが発生して寿命が短く、試料Ｎｏ．１０では早期に摩耗した。

From the results shown in Tables 1 to 3, sample No. 1 in which the outermost layer is a TiN layer is used. In sample No. 5, chipping occurred early in the outermost layer, and the total thickness of the coating layer was less than 9 μm. In No. 6, thermal cracks occurred and defects occurred, and the outermost surface layer of sample No. ₃ was an Al ₂ O ₃ layer. No. 7 has a severe welding, the tool life is short, the outermost layer is Ti (C _x N _y O _z ) _a layer a is smaller than 1, sample No. In No. 8, flaking occurred on the outermost layer at an early stage, and the effect of forming a bellage was not so much seen. In addition, Sample No. whose insert shape is outside the scope of the present invention. In No. 9, chipping occurred and the life was short. No. 10 was worn early.

  On the other hand, sample No. which is within the scope of the present invention. In Nos. 1 to 4, the wear resistance of the coating layer was high, and the wear resistance tended to be further improved by the effect of forming a belag.

DESCRIPTION OF SYMBOLS 1 Insert 2 Upper surface which functions as a rake surface 3 Lower surface which functions as a seating surface 4 Side surface which functions as a flank 5 Cutting blade 51 Main cutting blade 52 Saw blade 53 Secondary cutting blade 54 First corner cutting blade 55 Second corner cutting blade α Peripheral cutting edge angle of the main cutting edge 51 β Outer peripheral cutting edge angle of the sub cutting edge 53 6 Land part 61 Main cutting edge land part 62 Fraying blade land part 63 Sub cutting edge land part 64 First corner cutting edge land part 65 Second Corner cutting edge land L1 Line passing through the secondary cutting edge 53 and orthogonal to the central axis of the insert 1 L2 Line passing through the main cutting edge 51 and orthogonal to the central axis of the insert 1 θ1 Inclination angle of the secondary cutting edge land section 63 θ2 Main cutting Inclination angle 7 of the blade land portion 61 Breaker groove 8 Mounting screw contact portion 90 Cutting tool (rolling tool)
91 Holder 92 Insert pocket 93 Mounting surface 94 Mounting screw

Claims (7)

A negative mold with a coating layer formed on the surface of a cemented carbide substrate.
The coating layer has a total thickness of 9 to 25 μm, and the TiCN layer, the Al ₂ O ₃ layer, and the surface layer Ti (C _x N _y O _z ) _a (x + y + z = 1, 0 ≦ x ≦ 0.6) from the substrate side. 0 ≦ y ≦ 0.6, 0.2 ≦ z ≦ 0.8, 1.0 ≦ a ≦ 1.7),
The cutting edge formed at the intersection ridge line between the upper surface and the side surface is a main cutting edge, a secondary cutting edge whose outer peripheral cutting edge angle is larger than the outer peripheral cutting edge angle of the main cutting edge, and upward as it approaches the auxiliary cutting edge. A plurality of sets are formed as a set of wiping blades inclined to the (opposite side of the seating surface side), and a land portion is formed at a position following the cutting blade of the rake face,
A cutting insert in which a secondary cutting edge land portion following the secondary cutting blade is inclined so as to approach the lower surface toward the central portion of the upper surface.   The cutting insert according to claim 1, wherein a honing of 0.05 to 0.09 mm is formed on the cutting edge when viewed on the rake face side.   The main cutting edge land portion is inclined so as to approach the lower surface toward the center portion of the upper surface, and the inclination angle of the sub cutting edge land portion is a main cutting edge land corresponding to the main cutting edge. The cutting insert according to claim 1, wherein the cutting insert is larger than an angle of the portion.   The cutting insert according to claim 3, wherein an angle difference between the inclination angle of the main cutting edge land portion and the inclination angle of the sub cutting edge land portion is 3 to 10 °.   5. The device according to claim 1, wherein the wiping blade is formed so as to protrude from the main cutting blade, and the auxiliary cutting blade is inclined so as to approach the lower surface from the wiping blade toward the main cutting blade. Cutting insert as described in.   A curved first corner cutting edge is provided between the main cutting edge and the auxiliary cutting edge, and a curved second corner cutting edge is provided between the auxiliary cutting edge and the wiping edge. Item 6. The cutting insert according to any one of Items 1 to 5.   The cutting insert according to claim 6, wherein a curvature radius of the first corner cutting edge is larger than a curvature radius of the second corner cutting edge in a top view.

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