Cutting insert

Abstract

The present application provides a cutting insert which is easy to fragment chips and has excellent durability. At least a blade portion of a cutting insert 1 is formed of a sintered body 10. The sintered body 10 has a chip breaker portion 14 which is a recess formed by recessing a part of an upper surface 13 of the blade portion downward. The chip breaker portion 14 has a sunk slope 41, a raised slope 42, a protruding portion 40 protruding along a first axis X1 passing a distal end of a cutting edge 12, and a step surface 43 adjoining the protruding portion 40 from a Y-axis direction orthogonal to the first axis X1. An upper end 40U of the protruding portion 40 is formed at an upper layer height H3. The step surface 43 is formed at a middle layer height H2 at a portion thereof closest to the first axis X1.

Description

Technical Field

[0001] This invention relates to cutting blades. Background Technology

[0002] Sintered bodies with cubic boron nitride or polycrystalline diamond as the main component are suitable as cutting tool materials due to their excellent hardness and thermal conductivity. General-purpose cutting tools have a small sheet-like sintered body with cubic boron nitride or polycrystalline diamond as the main component joined to the end of the body formed of cemented carbide or the like.

[0003] Cubic boron nitride sintered bodies or polycrystalline diamond sintered bodies are difficult to machine. Although it is difficult to create a chip-breaking section with the same shape as cemented carbide, for example, if a laser is used, the surface of the cubic boron nitride sintered body or polycrystalline diamond sintered body can be locally evaporated, thereby creating a chip-breaking section formed by the surface depression (for example, see Patent Document 1).

[0004] Existing technical documents Patent documents Patent Document 1: WO2005068117A1 Technical issues Thin flakes like chips won't break even if bent directly. However, if bent like a trough, even a slight bend can break them. The chip-breaking section disclosed in Patent Document 1 causes the chip to collide with a protrusion, bending it like a trough.

[0005] However, if cutting from a large depth of cut, the chip width becomes larger. As in Patent Document 1... Figure 2 In the disclosed chip-breaking section, the chip can be processed only by the front end of the protrusion. However, when the chip widens and contacts not only the front end of the protrusion but also the area around it, the chip-breaking section's chip-bending effect is weakened. In, as in Patent Document 1... Figure 5 In the disclosed chip-breaking section, even if the chip widens, the contact area with the protrusion remains small, which can stably bend the chip, but the front end of the protrusion is easily worn.

[0006] Therefore, the object of the present invention is to provide a cutting blade that easily breaks down chips and has excellent durability. Summary of the Invention

[0007] The cutting insert provided by one aspect of the present invention has at least its cutting edge formed from a sintered body. The cutting insert has an upper surface and a lower surface located opposite the upper surface. The direction from the upper surface to the lower surface is defined as downward, and the direction from the lower surface to the upper surface is defined as upward. In this case, the sintered body has an upper cutting edge, a cutting edge, and a chip-breaking portion. The upper cutting edge faces upward, the cutting edge is formed at the outer edge of the upper cutting edge, and the chip-breaking portion is formed by a portion of the upper cutting edge being recessed downward. The center of gravity axis is an axis passing through the center of gravity of the upper and lower surfaces of the insert. The first axis is a straight line orthogonal to the center of gravity axis and passes through the far end of the cutting edge furthest from the center of gravity axis. The direction parallel to the first axis is defined as the X-axis direction, and the direction intersecting both the X-axis direction and the vertical direction is defined as the Y-axis direction. The chip-breaking section has a sinking ramp, a rising ramp, a protrusion, and a step surface. The sinking ramp descends to a lower layer height in the X-axis direction as it moves away from the cutting edge, and the rising ramp rises from the lower layer height in the X-axis direction as it moves away from the cutting edge. The protrusion protrudes along the first axis from the center of gravity axis toward the cutting edge, and the protruding end of the protrusion faces the sinking ramp. The step surface is adjacent to the protrusion from at least one side in the Y-axis direction. The upper end of the protrusion is formed at an upper layer height higher than the lower layer height. The step surface faces upward, and at its closest point to the first axis, the step surface is formed at a middle layer height lower than the upper layer height and higher than the lower layer height.

[0008] According to this method, since a step surface is formed adjacent to the protrusion and lower in height than the protrusion, the width of the protrusion in the Y-axis direction becomes narrower compared to the case where no step surface is formed. Because the contact area with the chip at the upper height is smaller, the chip is more easily bent like a rain trough, thus fragmenting the chip. On the other hand, since the step surface is located higher than the bottom of the sinker, there is a rising slope between the step surface and the bottom of the sinker. When a large depth of cut is used to widen the chip, the chip can be dispersed not only at the protruding end of the protrusion but also on the rising slope, thus reducing wear on the protrusion. This provides a cutting tool with excellent durability.

[0009] In the above method, the step surface can be tilted so that it rises from the middle layer height in the Y-axis direction as it moves away from the first axis.

[0010] According to this method, because the height of the step surface is lower near the protrusion, the contact area with the chip is smaller, making the chip more prone to bending. In areas farther from the protrusion, the area of ​​the upward-sloping surface is larger, making it easier to distribute the load.

[0011] In the above method, the protruding end can be formed as a conical surface.

[0012] According to this method, since the protruding end is a conical surface that makes surface contact with the chip, it is less prone to wear compared to a sharp protruding end that makes line contact with the chip. This results in cutting inserts with excellent durability.

[0013] In the above method, the cutting edge may include an angular cutting edge and a finishing edge. The angular cutting edge is formed in an arc shape, and the finishing edge is formed in an arc shape with a radius of curvature larger than that of the angular cutting edge and is connected to one end of the angular cutting edge.

[0014] While the presence of a finishing edge can improve the quality of the finished surface, it can also easily generate wider chips. This method, however, effectively breaks down even wider chips, making it suitable for cutting inserts with a finishing edge. In the above methods, the sintered body can be mainly composed of cubic boron nitride or polycrystalline diamond.

[0015] According to this method, even sintered bodies with cubic boron nitride or polycrystalline diamond as the main components, which are difficult to process, can be provided with a chip-breaking section that easily breaks up the chips and has excellent durability.

[0016] According to the present invention, it is possible to provide a cutting blade that easily breaks down chips and has excellent durability. Attached Figure Description

[0017] Figure 1 This is a perspective view of a cutting blade according to one embodiment of the present invention.

[0018] Figure 2 for Figure 1 The image shown is a magnified three-dimensional view of the sintered body.

[0019] Figure 3 To view from the Y-axis direction Figure 1 Side view of the sintered body shown.

[0020] Figure 4 To observe from the X-axis direction Figure 1 The front view of the sintered body shown.

[0021] Figure 5 To view from the Z-axis direction Figure 1 Top view of the sintered body shown.

[0022] Figure 6 For along Figure 5 Sectional view of VI-VI.

[0023] Figure 7 For along Figure 5 Sectional view of VII-VII.

[0024] Figure 8 For along Figure 5Sectional view of VIII-VIII.

[0025] Figure 9 For along Figure 5 A cross-sectional view of IX-IX.

[0026] Figure 10 To show Figure 1 A perspective view of an example of deformation of the cutting blade shown.

[0027] Explanation of main component symbols Detailed Implementation

[0028] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Furthermore, in the drawings, structures labeled with the same symbols are identical or similar structures. Each structure will now be described in detail with reference to the accompanying drawings. Figure 1 This is a perspective view of a cutting blade 1 according to one embodiment of the present invention. At least the cutting edge of the cutting blade 1 is formed of a sintered body.

[0029] In the illustrated example, the cutting insert 1 is a rhomboid cutting insert mounted on the retainer to form a turning tool, and small sheet-like sintered bodies 10, harder than the body 2, are bonded to each acute vertices of the body 2. The body 2 is formed of a material such as cemented carbide. The sintered body 10 is formed of, for example, a sintered body containing cubic boron nitride or polycrystalline diamond.

[0030] Polycrystalline diamond sintered bodies, with polycrystalline diamond as the main component, are formed by sintering diamond powder under high pressure and high temperature using metal, ceramic, or other binders. Compared with cemented carbide, they have superior hardness and thermal conductivity, making them suitable for use as cutting tools. Cubic boron nitride sintered bodies, with cubic boron nitride as the main component, are formed by sintering cubic boron nitride powder under high pressure and high temperature using metal, ceramic, or other binders. They possess hardness slightly lower than polycrystalline diamond sintered bodies, high thermal conductivity, and are less reactive with iron, making them suitable for use as cutting tools.

[0031] The cutting insert 1 has a polygonal upper surface 3, a lower surface 4 located opposite to the upper surface 3, a peripheral surface 5 connecting the upper surface 3 and the lower surface 4, and a mounting hole 6 penetrating the upper surface 3 and the lower surface 4. In the illustrated example, the body 2 has the upper surface 3, the lower surface 4, the peripheral surface 5, and the mounting hole 6. The cutting edge of the cutting insert 1 is located at the top, including the vertex of the polygonal upper surface 3 and its vicinity.

[0032] In the illustrated example, the upper surface 3 of the blade is a regular polygon, and the center of the upper surface 3 is the same as the center of gravity. The central axis of the mounting hole 6 is the same as the center of gravity axis O, which will be described later. The shape of the cutting blade 1 is not limited to the illustrated example and can be other shapes. For example, the sintered body 10 extending from the upper surface 3 of the blade of the body 2 to the lower surface 4 of the blade can be joined to the cutting edge of the body 2, thereby enabling the use of the cutting edges on both the upper surface 3 and the lower surface 4 of the blade. For example, it can also be entirely composed of a sintered body instead of being part of the cutting blade 1. As shown in the figure, the part of the cutting blade 1 other than the cutting edge is composed of the body 2, which reduces the use of expensive sintered bodies compared to the case where the entire piece is composed of a sintered body.

[0033] In the following description, the direction from the upper surface 3 of the blade towards the lower surface 4 of the blade is defined as downward, and the direction from the lower surface 4 of the blade towards the upper surface 3 of the blade is defined as upward. Figure 1 In this diagram, the Z-axis represents the vertical direction, and the symbol O represents the centroidal axis passing through the center of gravity of the upper surface 3 and the center of gravity of the lower surface 4 of the cutting tool. A straight line orthogonal to the centroidal axis O and passing through the distal end of the cutting edge 12 of the sintered body 10 is defined as the first axis X1. The direction parallel to the first axis X1 is defined as the X-axis direction, and the direction intersecting both the X-axis and the vertical direction is defined as the Y-axis direction. Figure 1 In this diagram, the X-axis represents the X-axis direction, and the Y-axis represents the Y-axis direction. The X-axis direction can also be called the front-back direction, and the Y-axis direction can also be called the left-right direction.

[0034] Figure 2 for Figure 1 The enlarged three-dimensional view of the sintered body 10 shown. Figure 3 To view from the Y-axis direction Figure 1 Side view of the sintered body 10 shown. Figure 4 To observe from the X-axis direction Figure 1 The front view of the sintered body 10 shown. Figures 2 to 4 As shown, the sintered body 10 has an upper cutting edge surface 13, a cutting edge 12, a flank face 11, and a chip-breaking portion 14. The upper cutting edge surface 13 faces upward, the cutting edge 12 is formed on the outer edge of the upper cutting edge surface 13, the flank face 11 is adjacent to the cutting edge 12 from the opposite side of the upper cutting edge surface 13, and the chip-breaking portion 14 is a recess formed by a portion of the upper cutting edge surface 13 facing downward. The outer edge of the upper cutting edge surface 13 is the ridge line (first intersection line) R1 where the upper cutting edge surface 13 intersects the flank face 11.

[0035] In the illustrated example, a cutting edge with a negative cutting edge angle (negative cutting edge) is provided on the upper surface 3 of the cutting insert 1 and the upper surface 13 of the cutting edge. The upper surface 13 of the cutting edge includes the cutting edge 13A and the upper end face 13B. The cutting edge 13A, together with the downward slope 41 formed in the chip breaker 14, functions as the rake face of the cutting edge 12. The cutting edge of the cutting insert 1 is composed of the cutting edge 12 and the flank face 11 and the rake face adjacent to the cutting edge 12.

[0036] The cutting edge 13A can be referred to as the first rake face 13A, and the downward slope 41 as the second rake face 41. Although not shown in the figure, the cutting edge 13A and the upper end face 13B can also be formed as the same surface. In this case, the first rake face 13A is formed as a cutting edge with a cutting edge angle of zero (flat cutting edge).

[0037] The chip-breaking section 14 has a downward slope 41, a rising slope 42, a protrusion 40, a step surface 43, and a wall surface 45. The downward slope 41 is formed adjacent to the cutting edge 13A and is inclined, decreasing in the X-axis direction from the height of the cutting edge 13A to a lower layer height H1 (see reference) as it moves away from the cutting edge 12. Figure 7 ).

[0038] The lower layer height H1 is the height of the bottom of the chip breaker section 14, and it is the lowest in the chip breaker section 14. The rising slope 42 is formed in the X-axis direction at a position farther away from the cutting edge 12 than the sinking slope 41, and is inclined. In the X-axis direction, it rises from the bottom of the chip breaker section 14, i.e., the lower layer height H1, as it moves away from the cutting edge 12.

[0039] The protrusion 40 protrudes along the first axis X1 in a direction from the center of gravity O toward the cutting edge 12. The upper end 40U of the protrusion 40 is formed at the upper layer height H3 (refer to...). Figure 7 In the illustrated example, the upper layer height H3 is the same as the height of the upper end face 13B of the upper surface 13 of the cutting edge 14, i.e., the upper end face 13B. Although not illustrated, the upper layer height H3 may also be lower than the upper end face 13B. The protruding end 44 of the protrusion 40 is formed as a conical surface, which is opposite to the downward slope 41 that constitutes the rake face.

[0040] The step surface 43 is adjacent to the protrusion 40 from at least one side in the Y-axis direction. In the illustrated example, a step surface 43 is formed that is symmetrically positioned to sandwich the protrusion 40 in the middle, and the step surface 43 is adjacent to the protrusion 40 from both the left and right sides in the Y-axis direction. In other words, the step surface 43 is divided into two parts by the protrusion 40 in the Y-axis direction. The step surface 43 is formed at the intermediate layer height H2 described later (refer to...). Figure 7 The wall surface 45 connects the step surface 43 to the upper end surface 13B of the upper surface 13 of the cutting edge. The slope of the wall surface 45 is greater than the slope of the rising slope 42.

[0041] Figure 5To view from the Z-axis direction Figure 1 A top view of the sintered body 10 shown. Figure 5 As shown, the first intersection line R1 is defined as the ridge line where the cutting edge 13A of the upper surface 13 of the cutting edge intersects with the back face 11; the second intersection line R2 is defined as the ridge line where the step surface 43 intersects with the rising slope 42; and the third intersection line R3 is defined as the valley line where the step surface 43 intersects with the protrusion 40. The third intersection line R3 is further away from the first intersection line R1 compared to the second intersection line R2.

[0042] Figures 6 to 9 They are along Figure 5 The sectional views of VI-VI, VII-VII, VIII-VIII, and IX-IX. For example... Figure 6 As shown, the protruding end 44 is opposite to the downward slope 41 that forms the rake face, and the chips discharged from the downward slope 41 collide with the protruding end 44. Figure 7 As shown, the step surface 43 faces upward, and at its part 43L closest to the first axis X1, a middle layer height H2 is formed that is lower than the upper layer height H3 and higher than the lower layer height H1.

[0043] One feature of the cutting insert 1 of the present invention is that, since the lower end 43L of the step surface 43 is formed at a middle layer height H2 that is higher than the bottom of the chip breaking portion 14, therefore... Figure 7 and Figure 8 As shown, a rising ramp 42 exists between the bottom of the chip-breaking section 14 and the step surface 43. Figure 9 As shown, the step surface 43 is inclined, and in the Y-axis direction, it moves away from the first axis X1 from the middle layer height H2 to the upper layer height H3. Therefore, at a position away from the protrusion 40, the upward slope 42 increases in dimension Z in the vertical direction.

[0044] Compared to the case without the step surface 43, the cutting insert 1 of this embodiment, configured as described above, has a narrower width of the protrusion 40 in the Y-axis direction, which makes it easier for the chips to bend like rain gutters and break into smaller pieces. Furthermore, since the step surface 43 is at a mid-level height H2 and there is a rising ramp 42 between the step surface 43 and the bottom of the chip-breaking portion 14, when the chips widen during deep cutting, the load acting on the protruding end 44 of the protrusion 40 can be distributed to the rising ramp 42. The protruding end 44 of the protrusion 40 is less prone to wear and exhibits excellent durability.

[0045] Figure 10 To show Figure 1 A perspective view of an example of deformation of the cutting insert shown. (See image below.) Figure 10As shown, the cutting edge 12 may include an angular cutting edge 21 and a finishing edge 22. The angular cutting edge 21 is formed in an arc shape, and the finishing edge 22 is formed in an arc shape with a radius of curvature larger than that of the angular cutting edge 21, and is connected to one end of the angular cutting edge 21. If the finishing edge 22 is present, it is easy to generate chips with a large width. Based on the present invention, even if chips with a large width are generated, they can be effectively fragmented, and therefore it is suitable for cutting inserts 1 with a finishing edge 22.

[0046] The embodiments described above are for ease of understanding of the present invention and are not intended to limit or explain the present invention. The elements, their configurations, materials, conditions, shapes, and dimensions in the embodiments are not limited to those illustrated and can be appropriately varied. Furthermore, the various structures shown can be partially substituted or combined in different embodiments. For example, although the figures show a non-distinguishing left and right cutting insert 1, wherein the upper surface 3 of the insert is mirror-symmetrical with respect to the XZ plane passing through the first axis X1, the cutting insert 1 of the present invention can also be a left-side or right-side non-mirror-symmetrical cutting insert. In this case, the step surface 43 can also be formed only in the Y-axis direction on either the left or right side of the protrusion 40.

Claims

1. A cutting blade, wherein at least the cutting edge is formed of a sintered body; The cutting blade has an upper blade surface and a lower blade surface located on the opposite side of the upper blade surface; The direction from the upper surface of the blade toward the lower surface of the blade is set downward, and the direction from the lower surface of the blade toward the upper surface of the blade is set upward. At this time, the sintered body has an upper surface of the cutting edge, a cutting edge, and a chip-breaking portion. The upper surface of the cutting edge faces upward, the cutting edge is formed on the outer edge of the upper surface of the cutting edge, and the chip-breaking portion is formed by recessing a part of the upper surface of the cutting edge downward. The center of gravity axis is an axis passing through the center of gravity of the upper surface of the blade and the center of gravity of the lower surface of the blade. The first axis is a straight line orthogonal to the center of gravity axis and passes through the far end of the cutting edge furthest from the center of gravity axis. The direction parallel to the first axis is defined as the X-axis direction, and the direction intersecting both the X-axis direction and the vertical direction is defined as the Y-axis direction. At this time, the chip breaking part has a sinking slope, a rising slope, a protrusion, and a step surface. The sinking slope descends to a lower layer height in the X-axis direction as it moves away from the cutting edge. The rising slope rises from the lower layer height in the X-axis direction as it moves away from the cutting edge. The protrusion protrudes along the first axis in the direction from the center of gravity axis toward the cutting edge. The protruding end of the protrusion is opposite to the sinking slope. The step surface is adjacent to the protrusion from at least one side in the Y-axis direction. The upper end of the protrusion is formed at a height that is higher than the height of the lower layer; The step surface faces upward, and at its closest point to the first axis, the step surface is formed at a middle layer height that is lower than the upper layer height and higher than the lower layer height; The step surface is inclined in such a way that it rises from the middle layer height in the Y-axis direction as it moves away from the first axis.

2. The cutting insert according to claim 1, wherein, The protruding end is formed into a conical surface.

3. The cutting insert according to claim 1, wherein, The cutting edge includes an angular cutting edge and a finishing edge. The angular cutting edge is formed in an arc shape, and the finishing edge is formed in an arc shape with a radius of curvature larger than that of the angular cutting edge and is connected to one end of the angular cutting edge.

4. The cutting insert according to any one of claims 1 to 3, wherein, The sintered body is mainly composed of cubic boron nitride or polycrystalline diamond.

Images