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EP-4741086-A1 - CUTTING TOOL

EP4741086A1EP 4741086 A1EP4741086 A1EP 4741086A1EP-4741086-A1

Abstract

In order to easily disposed a projection by accurately inspecting and measuring (correcting) a position of the projection relative to the cutting edge, and to improve the chip control regardless the insert shape by optimizing the disposition of the projection, the present invention provides a cutting tool including: an upper surface; a lower surface; a side surface; a cutting edge including a pair of major cutting edges and a corner cutting edge; a first upper surface; a second upper surface; an inclined surface; a groove disposed in the second upper surface; and a first projection and a second projection which are formed to be projected from the inclined surface. The first projection extends on the groove along the extended line, and the second projection is disposed to be linearly symmetric with respect to the extended line. At an intersection between the corner cutting edge and the bisector in a top view, L1 < L2 is established, where L1 is a distance from a virtual line intersecting perpendicularly to the bisector to a leading end of the first projection, and L2 is a distance from the virtual line to a leading end of the second projection.

Inventors

  • Fujita, Kento
  • SASAKI, YASUTAKE

Assignees

  • Tungaloy Corporation

Dates

Publication Date
20260513
Application Date
20251111

Claims (14)

  1. A cutting tool comprising: an upper surface; a lower surface that is disposed to face the upper surface; a side surface that connects the upper surface and the lower surface; a cutting edge that includes a pair of major cutting edges and a corner cutting edge having a projected curve shape which connects the pair of major cutting edges, the cutting edge being formed at a part of an intersecting edge of the upper surface and the side surface; a first upper surface and a second upper surface formed on the upper surface, with the second upper surface being more distant from the lower surface than the first upper surface; an inclined surface that connects the first upper surface and the second upper surface; one groove disposed on the second upper surface to extend on a bisector of an angle formed by the pair of major cutting edges, or two or more grooves disposed on the second upper surface to extend linearly symmetric with respect to the bisector; and a first projection and a second projection which are formed to be projected from the inclined surface, wherein the first projection extends on an extended line of the groove, or along a line parallel with the extended line, wherein the second projection is disposed to be linearly symmetric with respect to the bisector of the angle formed by the pair of major cutting edges, and extends to be gradually closer to the extended line of the groove as gradually approaching the corner cutting edge, at an intersection between the corner cutting edge and the bisector of the angle formed by the pair of major cutting edges in a top view, L1 < L2 is established, where L1 is a distance from a virtual line intersecting perpendicularly to the bisector of the angle formed by the major cutting edges to a leading end of the first projection, and L2 is a distance from the virtual line to a leading end of the second projection, and in a side view from a direction that is perpendicular to the bisector of the angle formed by the major cutting edges and that is parallel with the upper surface, h1 < h2 < h3 is established, where h1 is a distance from the first upper surface to a top of the first projection, h2 is a distance from the first upper surface to a top of the second projection, and h3 is a distance from the first upper surface to the second upper surface respectively, in a direction perpendicular to the upper surface.
  2. The cutting tool according to claim 1, wherein θ 1 < θ < θ2 is established, where θ1, θ and θ2 are rising angles of the inclined surface, the first projection and the second projection, the respective angles being formed with the first upper surface in the side view.
  3. The cutting tool according to claim 2, wherein in a case where any of the inclined surface, the first projection and the second projection is a curved line in the side view, θ1, θ or θ2 is a value determined by interpolating an angle of an upper end and an angle of a lower end of each of the inclined surface, the first projection or the second projection.
  4. The cutting tool according to any one of claims 1 to 3, wherein the groove has a shape which includes a pair of side walls.
  5. The cutting tool according to claim 4, wherein at least a pair of groove edges existing between the side wall and the second upper surface, are at least partially parallel.
  6. The cutting tool according to claim 5, wherein at least a part of the groove edge has an edge shape.
  7. The cutting tool according to any one of claims 1 to 6, wherein the groove has a shape in which one end thereof has a constant groove width, and the groove width of the other end thereof gradually increases as the other end gradually approaches the cutting edge.
  8. The cutting tool according to any one of claims 1 to 6, wherein the groove has a shape in which one end thereof has a constant groove width, and the groove width of the other end thereof gradually decreases as the other end gradually approaches the cutting edge.
  9. The cutting tool according to any one of claims 1 to 8, wherein the groove is disposed at a plurality of positions.
  10. The cutting tool according to any one of claims 1 to 9, wherein the groove is disposed to be linearly symmetric with respect to the bisector of the angle formed by the pair of major cutting edges.
  11. The cutting tool according to any one of claims 1 to 10, wherein the groove is used as a coolant supply groove, one end of which intersects with the inclined surface, to supply coolant to the cutting edge.
  12. The cutting tool according to any one of claims 1 to 11, wherein the a number of the second projections is an odd number.
  13. The cutting tool according to any one of claims 1 to 12, wherein the second projection is disposed to be linearly symmetric with respect to the bisector of the angle formed by the pair of major cutting edges.
  14. The cutting tool according to any one of claims 1 to 13, comprising a structure in which a sintered body containing cBN is bonded to a cemented carbide member.

Description

Background Field The present invention relates to a cutting tool. Description of Related Art To meet a demand for decreasing a corner R in a recess machining of a work using a hardened steel, a cutting tool (turning tool) for finish machining that have a small radius of curvature of a corner R, is demanded (see Japanese Patent No. 5380746, Japanese Patent No. 6861269, US Patent No. 7934891 Specification and US Patent No. 9302326 Specification). For example, in Japanese Patent No. 5380746, chip control in the finishing machining is improved by disposing a projection constituted of a major wall and a minor wall of a breaker and arranging the major wall of the breaker so as to satisfy predetermined conditions. In the case of such a cutting tool having a small corner R, deviation of the projection that functions as a breaker during the finish machining relative to the cutting edge more easily influences the performance, hence it is necessary to accurately inspect and measure (correct) the position of the projection relative to the cutting edge in the manufacturing process of the cutting tool. Summary However it is difficult in practical terms to perform accurate inspection and measurement (correction), and implement disposition of the projection suitably by measuring the projection itself, which functions as a breaker, as mentioned above. This is especially true of a cutting tool, which has a relatively small radius of curvature of the corner cutting edge, a sharp included angle, and a small rake surface area around the corner cutting edge, such as a corner R of which radius of curvature R of the corner cutting edge is 0.2 mm or less. In terms of improving chip control of the finish machining of a cutting tool having a small corner R regardless the insert shape, the structure and disposition of the projection still needs to be improved. With the foregoing in view, it is an object of the present invention to provide a cutting tool to dispose the projection suitably by accurately inspecting and measuring (correcting) a position of the projection relative to the cutting edge, and to improve the chip control of the finish machining regardless the insert shape by innovating the disposition of the projection. To solve this problem, the present inventors studied various means. For example, various breakers to improve the chip control have been considered, as disclosed in Japanese Patent No. 5380746 and Japanese Patent No. 6861269, but applying these breakers to a cutting tool of which rake surface area around the corner cutting edge is small is difficult in some cases. In other words, it may be difficult to apply these breakers when the radius of curvature of the corner cutting edge is relatively small and the included angle is designed to be sharp, because the area of the rake surface around the corner cutting edge is small. Even if applicable, acquiring contour lines that are effective for inspection and measurement is difficult, because the projection has a complicated shape and intersects with various composing elements, such as other projections and rake surfaces. That is, it is difficult to perform accurate inspection and measurement by measuring the projection itself, therefore it is difficult to manufacture a product in which the position of the breaker does not deviate relative to the cutting edge. An aspect of the present invention is a cutting tool that was conceived based on the knowledge obtained through the above examination, and the cutting tool includes: an upper surface; a lower surface that is disposed to face the upper surface; a side surface that connects the upper surface and the lower surface; a cutting edge that includes a pair of major cutting edges and a corner cutting edge having a projected curve shape which connects the pair of major cutting edges, the cutting edge being formed at a part of an intersecting edge of the upper surface and the side surface,; a first upper surface and a second upper surface formed on the upper surface, with the second surface being more distant from the lower surface than the first upper surface; an inclined surface that connects the first upper surface and the second upper surface; one groove disposed on the second upper surface to extend on a bisector of an angle formed by the pair of major cutting edges, or two or more grooves disposed on the second upper surface to extend linearly symmetric with respect to the bisector; and a first projection and a second projection which are formed to be projected from the inclined surface. The first projection extends on an extended line of the groove or along a line parallel with the extended line. The second projection is disposed to be linearly symmetric with respect to the bisector of the angle formed by the pair of major cutting edges, and extends to be gradually closer to the extended line of the groove as gradually approaching the corner cutting edge. At an intersection between the corner cutting edge and the bisect