JP7484355B2 - Cutting Insert - Google Patents

Description

The present invention relates to a cutting insert in which the polygonal surface of the polygonal plate-shaped insert body is the rake surface, and the side surface of the insert body arranged around this rake surface is the relief surface, and cutting edges extending from corner edges formed at the corners of the rake surface are formed at the intersection ridges between these rake surfaces and relief surfaces.

For example, Patent Document 1 describes such a cutting insert, which includes a cutting insert having a rake face, an end face formed with a breaker wall surface formed to protrude from the rake face, a clearance face, an arc-shaped corner cutting edge formed at the junction between the end face and the clearance face and having a first radius of curvature in end view from the direction facing the end face, and a wiper cutting edge formed at the junction between the end face and the clearance face, connected to one end of the corner cutting edge, and having a second radius of curvature larger than the first radius of curvature in end view, or consisting of a straight line.

Here, the breaker wall surface has a concave portion recessed away from the corner cutting edge and a convex portion connected to the concave portion and rising toward the corner cutting edge, the concave portion is formed so as to intersect with a first imaginary plane passing through the end surface so as to bisect the corner cutting edge, and the convex portion is formed so as to be spaced apart from the first imaginary plane.

The breaker wall is formed so that the first distance is the minimum distance, in an end view, between the intersection line between the breaker wall and a second imaginary plane perpendicular to the first imaginary plane and the corner cutting edge, and the second distance is the minimum distance, in an end view, between the intersection line and the wiper cutting edge, and the second distance is smaller than the first distance.

In the cutting insert described in Patent Document 1, the distance between the wiper cutting edge and the intersection line in an end view is greater than the second distance at one end of the wiper cutting edge that connects to the corner cutting edge, and a round honing is formed on the wiper cutting edge, and a chamfer honing is formed on the corner cutting edge.

Patent No. 6512499

In the cutting insert described in Patent Document 1, when chips with a width of, for example, about 1 mm are generated, the chips are collided with the breaker wall, causing them to curl so that they collide with the flank. However, the breaker wall of the cutting insert described in Patent Document 1 is a single inclined plane that gradually protrudes toward the inside of the rake face, except for the concave and convex portions adjacent to the corner cutting edge.

Therefore, with the cutting insert described in Patent Document 1, it is difficult to break up the chips with this inclined plane, and the chips that flow out along the inclined plane and curl as they hit the flank tend to elongate, which can lead to them becoming entangled in the holder of the tool to which the cutting insert is attached or in the workpiece.

The present invention was made against this background, and aims to provide a cutting insert that can improve chip breaking by breaking up chips that collide with the breaker wall surface using the breaker wall surface.

In order to solve the above problems and achieve the above object, the present invention provides a cutting insert having a rake face formed on the polygonal surface of a polygonal plate-shaped insert body, a flank formed on the side surface of the insert body arranged around the rake face, and a cutting edge extending from a corner edge formed at a corner portion of the rake face formed at an intersection ridge between the rake face and the flank face, wherein the rake face is formed with a chip breaker having a breaker wall surface extending along the direction in which the cutting edge extends with a gap inward from the cutting edge, and the breaker wall surface of the chip breaker has a step surface protruding toward the cutting edge side and facing the rake face. When viewed from the direction opposite to the cutting face, the corner edge is formed away from the bisector of the corner portion, and the two cutting edges extend from both ends of the corner edge, and on the breaker wall surface, a lower end of an intersecting ridge line between the first step surface and the breaker wall surface on the one cutting edge side is formed at a position within a range of 0.60 mm to 1.50 mm from one of the cutting edges along which the breaker wall surface extends and the other cutting edge that intersects with the corner edge via the corner edge, in a direction perpendicular to the other cutting edge, and a lower end of an intersecting ridge line between the second step surface and the breaker wall surface on the one cutting edge side is formed at a position within a range of 1.20 mm to 1.70 mm.

In a cutting insert configured in this manner, a step surface that protrudes toward the cutting edge is formed on the breaker wall of the chip breaker, which extends in the direction in which the cutting edge extends with a gap in between the cutting edge and the inside of the rake face, away from the bisector of the corner portion when viewed from the direction facing the rake face. As a result, chips that collide with the breaker wall are curled and broken by resistance as they scrape against this step surface.

Therefore, with the cutting insert of the above configuration, it is possible to improve chip breaking properties and prevent the chips from becoming elongated before hitting the flank, and thus prevent the elongated chips from becoming entangled in the holder of the tool to which the cutting insert is attached or in the workpiece. This makes it possible to perform smooth and stable cutting over a long period of time.

Here, the step surface may be one step, but it is preferable that the step surface be multiple steps in order to improve chip breaking properties. In this case, when the two cutting edges extend from both ends of the corner edge, it is preferable that the breaker wall surface has a lower end of an intersecting ridgeline between the first step surface and the breaker wall surface on the cutting edge side at a position within a range of 0.60 mm to 1.50 mm in a direction perpendicular to one of the cutting edges along which the breaker wall surface extends and the other cutting edge that intersects via the corner edge, as viewed from the direction facing the rake face, and that the lower end of an intersecting ridgeline between the second step surface and the breaker wall surface on the cutting edge side at a position within a range of 1.20 mm to 1.70 mm.

By forming at least two such first and second step surfaces, even if chips with a width of 0.6 mm or more are generated, the chips can be curled and broken reliably by providing resistance through the first and second step surfaces. Note that three or more step surfaces, including the first and second step surfaces, may be formed on the breaker wall of the chip breaker.

It is also desirable that the amount of protrusion of each step surface, when viewed from the direction facing the rake face, is within the range of 0.01 mm to 0.25 mm. If the amount of protrusion of this step surface falls below this range, the resistance applied to the chips may be too small, making it difficult to curl and break them reliably. On the other hand, conversely, if the amount of protrusion of this step surface exceeds this range, the resistance applied to the chips may be too large, and the cutting resistance may also increase.

As explained above, according to the present invention, the step surface formed on the breaker wall provides resistance to chips colliding with the breaker wall, allowing the chips to curl and be broken up. This improves chip breaking properties and prevents the chips from becoming elongated. This prevents elongated chips from becoming entangled in the holder or workpiece, making it possible to perform smooth and stable cutting over a long period of time.

FIG. 1 is a perspective view showing one embodiment of the present invention. FIG. 2 is a plan view of the embodiment shown in FIG. 1 as viewed from a direction opposite to the rake face in the insert center line direction. FIG. 2 is an enlarged perspective view of a cutting edge portion of the embodiment shown in FIG. 1 . FIG. 2 is an enlarged plan view of a cutting edge portion of the embodiment shown in FIG. 1 . 5 is a cross-sectional view of FIG. 4 .

Figures 1 to 5 show one embodiment of the present invention. In this embodiment, the insert body 1 is formed in a polygonal plate shape, and in particular, as shown in Figures 1 and 2, is formed in a diamond-shaped flat plate shape. In the center of the diamond-shaped surface (polygonal surface) of this insert body 1, there is an attachment hole 2 that penetrates the insert body 1 and has a circular cross section centered on the insert center line C that passes through the centers of the front and back diamond-shaped surfaces.

The insert body 1 of the cutting insert of this embodiment includes a base metal portion 1A made of a hard material such as cemented carbide, and a cutting blade tip 1B made of a CBN sintered body or diamond sintered body, which is harder than the base metal portion 1A. At two acute corners of one diamond surface of the base metal portion 1A, which is formed in a roughly diamond-shaped flat plate shape, a recess 1C is formed by cutting out the acute corners in an L-shape, and the above-mentioned triangular plate-shaped cutting blade tip 1B is attached to the recess 1C by being joined by brazing or the like.

A cutting edge tip 1B of such an insert body 1 has a rake face 3 formed on the diamond-shaped surface side, and a clearance face 4 formed on the side surface arranged around the diamond-shaped surface. At the intersection ridge of the rake face 3 and the clearance face 4, a corner blade 5 is formed at the corner of the rake face 3 located at the acute angle of the diamond-shaped surface, and cutting edges 6 are formed on the two edge portions of the diamond-shaped surface connected to this corner portion.

As shown in Figures 2 and 4, when viewed from the direction opposite the rake face 3 in the direction of the insert center line C, the corner edge 5 is formed in a convex curve such as a convex arc, and the cutting edge 6 is formed in a straight line tangent to the convex curve formed by the corner edge 5 at both ends of the corner edge 5. Note that the cutting insert of this embodiment is a negative type cutting insert in which the side of the insert body 1 extends parallel to the insert center line C.

As shown in FIG. 5, the rake face 3 is a positive rake face that recedes toward the insert center line C at a constant inclination angle toward the inside of the rake face 3. The corner edge 5 and cutting edge 6 are formed with a land portion 7 that intersects with the rake face 3, which is a positive rake face, and the relief face 4 at an obtuse angle.

Furthermore, on the inside of the rake face 3, a chip breaker 8 is formed so as to protrude from the rake face 3, which is a positive rake face, in the direction of the insert center line C. The tip surface 8A of this chip breaker 8 is a plane perpendicular to the insert center line C, protrudes further in the direction of the insert center line C than the corner edge 5 and the cutting edge 6, and is flush with the diamond-shaped surface of the base metal portion 1A of the insert body 1.

The insert body 1, including the chip breaker 8, is formed symmetrically with respect to a plane P that includes a diagonal line connecting the acute corners of the diamond-shaped surface and the insert center line C when viewed from the direction facing the rake face 3 in the direction of the insert center line C, and the cutting insert of this embodiment is a cutting insert with no handedness.

The breaker wall surface 9 facing the corner edge 5 and cutting edge 6 of the chip breaker 8 is spaced apart from the corner edge 5 and cutting edge 6, and extends in the direction in which the cutting edge 6 extends from the tip 8B of the chip breaker 8 located inside the corner edge 5. The breaker wall surface 9 is formed as an inclined surface that protrudes toward the insert center line C at a constant inclination angle as it moves toward the inside of the rake face 3.

The breaker wall surface 9 at the tip 8B of the chip breaker 8 is formed in the shape of an isosceles triangle with a ridgeline on the plane P. The breaker wall surface 9 extending from the tip 8B along the cutting edge 6 has step surfaces 9A, 9B protruding toward the cutting edge 6, which are formed away from the plane P located on the bisector of the corner portion when viewed from the direction facing the rake face 3.

In this embodiment, the breaker wall surface 9 has two step surfaces, 9A and 9B, formed for each cutting edge 6. The first step surface 9A, which is closer to the corner edge 5, is formed at a position within a range of 0.60 mm to 1.50 mm in terms of the distance L1 in the perpendicular direction from one cutting edge 6 (cutting edge 6A on the left side in FIG. 4) along which the breaker wall surface 9 extends and the other cutting edge 6 (cutting edge 6B on the right side in FIG. 4) that intersects with the corner edge 5, as shown in FIG. 4, when viewed from the direction facing the rake face 3. ...

The second step surface 9B, which is farther from the corner edge 5 than the first step surface 9A, is formed at a position within the range of 1.20 mm to 1.70 mm as shown in FIG. 4 when viewed from the direction facing the rake face 3, such that the distance L2 in the perpendicular direction from one cutting edge 6A along which the breaker wall surface 9 extends and the other cutting edge 6B that intersects with the corner edge 5 is the distance L1 between the second step surface 9B and the lower end of the intersection ridge 9B1 on the rake face 3 side of the second step surface 9B and the breaker wall surface 9 located on the side of the one cutting edge 6A of the second step surface 9B.

In this embodiment, as shown in FIG. 4, the first and second step surfaces 9A, 9B are formed with a width in a direction perpendicular to the other cutting edge 6B. However, the chips extending along the rake face 3 scrape against the lower end of the intersecting ridges 9A1, 9B1 on the rake face 3 side of the intersecting ridges between the first and second step surfaces 9A, 9B and the breaker wall surface 9 on the one cutting edge 6A side. Therefore, it is sufficient that the lower end of the intersecting ridges 9A1, 9B1 on the rake face 3 side of the one cutting edge 6A side is formed in a position within the above range.

Furthermore, as shown in FIG. 4, when viewed from the direction opposite the rake face 3, the protrusion amount M of the first and second step faces 9A and 9B from the breaker wall face 9 is within the range of 0.01 mm to 0.25 mm, and in this embodiment, the protrusion amount M of the first step face 9A is greater than the protrusion amount M of the second step face 9B. Note that the first and second step faces 9A and 9B extend in a direction perpendicular to the plane P and are inclined so as to protrude in the direction of the insert center line C as they move inward from the rake face 3.

Furthermore, the breaker wall surface 9 up to the first step surface 9A at the tip 8B of the chip breaker 8, the breaker wall surface 9 between the first and second step surfaces 9A and 9B, and the breaker wall surface 9 extending on the opposite side of the corner blade 5 from the second step surface 9B are formed parallel to each other and, in this embodiment, are also formed parallel to the cutting edge 6.

However, because the breaker wall surface 9 protrudes toward the cutting edge 6 due to the first and second step surfaces 9A and 9B, as shown in FIG. 4, the breaker wall surface 9 protrudes toward the cutting edge 6 in stages, in the order of the breaker wall surface 9 at the tip 8B of the chip breaker 8, the breaker wall surface 9 between the first and second step surfaces 9A and 9B, and the breaker wall surface 9 extending beyond the second step surface 9B to the side opposite the corner edge 5. Note that a flat surface 3A perpendicular to the insert center line C may be formed between the chip breaker 8 and the rake face 3.

In a cutting insert configured in this manner, step surfaces 9A and 9B protruding toward the cutting edge 6 are formed on the breaker wall surface 9 of the chip breaker 8, which extends from the cutting edge 6 to the inside of the rake face 3 at a distance from the cutting edge 6 along the direction in which the cutting edge 6 extends, away from the plane P that is the bisector of the corner portion when viewed from the direction facing the rake face 3. When chips are generated by the corner edge 5 and the cutting edge 6 and flow out to the inside of the rake face 3 after colliding with the breaker wall surface 9, they are scraped against the step surfaces 9A and 9B, particularly the intersecting ridges 9A1 and 9B1.

The chips scraped against the step surfaces 9A and 9B are then curled and broken by resistance. Therefore, with the cutting insert of the above configuration, it is possible to improve chip breaking properties and prevent the chips from becoming elongated before hitting the flank surface 4. This makes it possible to prevent the elongated chips from becoming entangled in the holder of the tool to which the cutting insert is attached or in the workpiece, allowing smooth and stable cutting to be performed for a long period of time.

Here, when the cutting depth is small and chips with a small width are generated, the step surface may be a single step, the first step surface 9A close to the corner edge 5, but in this embodiment, the breaker wall surface 9 has first and second multiple (two) step surfaces 9A, 9B formed at intervals in the direction in which the cutting edge 6 extends. Therefore, as described above, not only when the cutting depth is small, but also when a cutting depth is greater and chips with a larger width are generated, the chip breakability can be improved.

In addition, in this embodiment, when viewed from the direction facing the rake face 3, the first step surface 9A is formed at a position within the range of 0.60 mm to 1.50 mm in the direction perpendicular to the cutting edge 6 (one cutting edge 6A) along which the breaker wall surface 9 extends and the cutting edge 6 (the other cutting edge 6B) that intersects with the corner edge 5, and the lower end of the rake face 3 side of the intersection ridge 9A1 between the first step surface 9A and the breaker wall surface 9 located on the one cutting edge 6A side of the first step surface 9A is formed at a position within the range of 1.20 mm to 1.70 mm, and the lower end of the rake face 3 side of the intersection ridge 9B1 between the second step surface 9B and the breaker wall surface 9 located on the one cutting edge 6A side of the second step surface 9B is formed.

Therefore, by forming the first and second step surfaces 9A and 9B, according to this embodiment, even if chips having a width of, for example, 0.6 mm or more are generated, the resistance provided by the first and second step surfaces 9A and 9B makes it possible to reliably curl and break the chips.

Here, if the lower ends of the intersection ridges 9A1, 9B1 on the rake face 3 side between the first and second step faces 9A, 9B and the breaker wall surface 9 located on the cutting edge 6A side of the first and second step faces 9A, 9B are located closer to the corner blade 5 than the above range, there is a risk that it will not be possible to provide sufficient resistance and separate wide chips when they are generated. Conversely, if the lower ends of the intersection ridges 9A1, 9B1 on the rake face 3 side between the first and second step faces 9A, 9B and the breaker wall surface 9 located on the cutting edge 6A side of the first and second step faces 9A, 9B are located closer to the corner blade 5 than the above range, there is a risk that it will not be possible to reliably separate narrow chips when narrow chips are generated, as the narrow chips will not scrape against the first step face 9A or the second step face 9B.

In this embodiment, the first and second step surfaces 9A and 9B are formed as described above, but for example, if the cutting insert is used only when the cutting depth is small, the step surface may be only the first step surface 9A. Also, when performing cutting processing with a larger cutting depth, three or more step surfaces including the first and second step surfaces 9A and 9B may be formed on the breaker wall surface 9 of the chip breaker 8.

In addition, in this embodiment, the first and second individual step surfaces 9A, 9B have a protrusion amount M from the breaker wall surface 9 that is within the range of 0.01 mm to 0.25 mm when viewed from the direction facing the rake face 3, which also ensures that the chips are curled and broken while preventing the cutting resistance from increasing more than necessary.

In other words, if the protruding amount M of the step surfaces 9A, 9B falls below the above range, the resistance applied when the chips scrape against the step surfaces 9A, 9B may be too small, making it difficult to reliably curl and break the chips. On the other hand, if the protruding amount M of the step surfaces 9A, 9B exceeds the above range, the resistance applied to the chips during deterioration may be too large, resulting in increased cutting resistance.

1 Insert body 1A Base metal portion 1B Cutting edge tip 2 Mounting hole 3 Rake face 4 Relief face 5 Corner edge 6 (6A, 6B) Cutting edge 8 Chip breaker 8B Tip of chip breaker 8 9 Breaker wall surface 9A First step surface 9B Second step surface C Insert center line P Plane located on the bisector of the corner portion where the corner edge 5 is formed when viewed from the direction opposite to the rake face 3 L1 Distance of the first step surface 9A in the vertical direction from the other cutting edge 6B L2 Distance of the second step surface 9B in the vertical direction from the other cutting edge 6B M Amount of protrusion of the step surfaces 9A and 9B

Claims (2)

A cutting insert having a rake face formed on a polygonal surface of a polygonal plate-shaped insert body, a relief face formed on a side surface of the insert body arranged around the rake face, and a cutting edge extending from a corner edge formed at a corner portion of the rake face formed at an intersection ridge between the rake face and the relief face,
A chip breaker having a breaker wall surface extending along the direction in which the cutting edge extends, with a gap between the chip breaker wall and the cutting edge, is formed on the rake face,
A step surface protruding toward the cutting edge is formed on the breaker wall surface of the chip breaker, the step surface being spaced apart from the bisector of the corner portion when viewed from a direction facing the rake face,
The corner edge has two cutting edges extending from opposite ends of the corner edge,
The breaker wall surface has a lower end of an intersecting ridge line between the first step surface and the breaker wall surface on the one cutting edge side at a position within a range of 0.60 mm to 1.50 mm from the other cutting edge that intersects with the one cutting edge along which the breaker wall surface extends via the corner edge, in a direction perpendicular to the other cutting edge, and a lower end of an intersecting ridge line between the second step surface and the breaker wall surface on the one cutting edge side at a position within a range of 1.20 mm to 1.70 mm from the other cutting edge that intersects with the one cutting edge along which the breaker wall surface extends via the corner edge, when viewed from a direction facing the cutting face. 2. The cutting insert according to claim 1 , wherein the step surface has a protruding amount within a range of 0.01 mm to 0.25 mm when viewed from a direction facing the rake face.

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