Cutting tool

Abstract

To improve coolant supply performance to a cutting edge, and to improve chip processing performance and durability performance.SOLUTION: The cutting tool includes a cutting edge 26 formed at an intersection between a rake face 22 and a flank 24, a breaker wall 28 formed inside the cutting edge 26 and protruding upward from the cutting tool, a boss portion 30 including a boss face 32 formed above the breaker wall 28, and a plurality of recesses 36 formed in the boss portion 30 and extending toward the cutting edge 26. A widthwise L1 of the breaker wall 28 in a direction in which the cutting edge 26 extends along an intersection line (including an imaginary intersection line or an imaginary extension line of the intersection line) W28 between the boss surface 32 and the breaker wall 28 is wider than a widthwise L1 of the groove 38 formed by the recessed portion 36 on the intersection line W38.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a cutting tool. [Background technology]

[0002] Cutting inserts with arc-shaped cutting edges made of cemented carbide are sometimes used as cutting tools for copy milling and finishing (see, for example, Patent Documents 1 to 3). For machining high-hardness materials, cutting inserts with cutting edges made of sintered bodies containing cBN (cubic boron nitride), which is even harder than cemented carbide, are sometimes used. When using such cutting inserts for finishing, for example, the depth of cut is typically around 0.2 mm, which is significantly lower than that of cemented carbide inserts. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5592954 [Patent Document 2] Patent No. 5262528 [Patent Document 3] U.S. Patent No. 9,579,727 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when performing finish machining using the above-described conventional cutting inserts, the supply of coolant to the cutting edge is sometimes insufficient.

[0005] Therefore, the present invention aims to provide a cutting tool that improves the coolant supply performance to the cutting edge, and also improves chip disposal performance and durability, particularly for cutting inserts used in copy machining and finishing machining. [Means for solving the problem]

[0006] The inventors conducted various studies to solve these problems. The cutting tools described above are composed of a flank, a honing (arc-shaped or chamfer-shaped), and a rake face. However, if the cutting tool does not have a breaker, chip control is not possible. In such cases, chips may become entangled in the workpiece, degrading the quality of the machined surface and resulting in a defective product. Furthermore, stopping the machine to remove chips entangled in the holder may reduce production efficiency. While attempts to address these issues include changing the machining conditions or the honing shape, these efforts may result in reduced machining efficiency or chatter on the machined surface, and may not solve the problem. Furthermore, in order to restrain chips while using cutting tools with breakers under such poor machining conditions, the width of the breaker must be narrowed. Furthermore, if a tool with an arc-shaped cutting edge is used in copy cutting, it is desirable for the cutting edge and the breaker width to be uniform. Therefore, when coolant is supplied from outside, the cutting oil may hit the boss surface and spread, preventing sufficient coolant from reaching the cutting edge through the narrow breaker width. Furthermore, chips are generated between the boss surface and the cutting edge during cutting, which can obstruct the flow of coolant and make it difficult to supply coolant to the cutting point where cutting heat is most generated. The inventors of the present invention conducted extensive research while focusing on these conventional methods, and have come up with a solution to this problem.

[0007] One aspect of the present invention, which has been conceived based on such findings, is a cutting tool, comprising: The scooping surface and The relief surface and A cutting edge formed at the intersection of a rake face and a flank face; a breaker wall formed inside the cutting edge and protruding upward from the cutting tool; a boss portion including a boss surface formed above the breaker wall; a plurality of recesses formed in the boss portion and extending toward the cutting edge; Equipped with This cutting tool has a width in the direction in which the cutting edge of the breaker wall extends along the intersection line or virtual intersection line between the boss surface and the breaker wall that is wider than the width of the groove formed by the recess on the virtual extension of the intersection line.

[0008] With the cutting tool of the above aspect, by providing a recessed portion on the boss surface that faces the cutting edge, the coolant that would otherwise be scattered on the boss surface passes through the recessed portion and is sent toward the cutting edge. Moreover, with the cutting tool of the above aspect, the area where the breaker wall is located becomes dominant relative to the cutting edge, so that the coolant can be supplied to the groove formed by the recessed portion while stable chip disposal can be achieved by the effect of the breaker wall.

[0009] In the cutting tool as described above, the width of the breaker wall may be at least twice the width of the groove formed by the recess.

[0010] In the cutting tool as described above, the cutting edge may be formed in an arc shape when viewed from above from the side where the rake face is located.

[0011] In the cutting tool as described above, the cutting edge may be arc-shaped with a central angle exceeding 180°.

[0012] In the cutting tool as described above, the recess may be formed as a groove that is linear in top view.

[0013] In the cutting tool as described above, the recess may be formed as a groove with a constant width.

[0014] In the cutting tool as described above, the height of the bottom surface of the recess may be lower than the height of the cutting edge when viewed from the front or side perpendicular to the top view.

[0015] In the cutting tool as described above, the distance between the breaker wall and the cutting edge may be uniform.

[0016] In the cutting tool described above, the distance between the breaker wall and the cutting edge may be non-uniform.

[0017] In the cutting tool as described above, an arc-shaped depression continuing to the recess may be formed near the center of the arc-shaped cutting edge.

[0018] In the cutting tool as described above, the cutting edge may be chamfered by honing.

[0019] In the cutting tool as described above, the recess may be formed in the shape of a hole. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a perspective view showing an example of a cutting tool according to an embodiment of the present invention. [Figure 2] FIG. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] FIG. 2 is an enlarged perspective view of a cutting edge member of the cutting tool. [Figure 6] FIG. 2 is an enlarged top view showing a part of a cutting edge member of the cutting tool. [Figure 7] FIG. 2 is an enlarged perspective side view of a cutting edge member of the cutting tool. [Figure 8] FIG. 4 is a schematic view showing the flow of coolant in the cutting edge member. [Figure 9] FIG. 4 is a diagram showing a cross-sectional shape of a cutting edge member. [Figure 10] FIG. 10 is an enlarged perspective view of a cutting edge member, showing another example of a cutting tool. [Figure 11] FIG. 10 is an enlarged perspective view of a cutting edge member, showing yet another example of a cutting tool. [Figure 12] FIG. 10 is a schematic perspective view for explaining, for reference, the flow of coolant in a cutting edge member in which a recess is not formed in a boss portion. [Figure 13]FIG. 10 is a schematic side view for explaining, for reference, the flow of coolant in a cutting edge member in which a recess is not formed in a boss portion. [Figure 14] 10 is a top view of a cutting edge member for explaining the central angle α of the cutting edge, the back taper, etc. DETAILED DESCRIPTION OF THE INVENTION

[0021] A preferred embodiment of the cutting tool according to the present invention will be described in detail below with reference to the drawings (see Figs. 1 to 9, etc.). In the following, a cutting insert 1 consisting of a base insert member 10 and a cutting edge member 20 will be described as an example of a preferred embodiment. In the following, the longitudinal direction of the base insert member 10 (the direction along the central axis X) will be referred to as the "front-rear direction," the left-right direction in Fig. 2 as the "width direction," and the upper side in Fig. 2 (the side on which a boss portion 30, which will be described later, is located) will be referred to as the "top," and the "bottom" in Fig. 2 will be described.

[0022] The base insert member 10 is a member that holds the brazed cutting edge member 20 (see FIGS. 1 to 4). The base insert member 10 in this embodiment is made of a superhard material and is formed in a shape that extends along the central axis 10X.

[0023] The cutting edge member 20 is a member formed of a sintered body containing cBN (cubic boron nitride), which is even harder than cemented carbide, and is brazed to the end of the base insert member 10 to form the cutting insert 1. The cutting edge member 20 of this embodiment has a rake face 22, a flank face 24, a cutting edge 26, a breaker wall 28, a boss portion 30, a boss face 32, a depression 34, a recess 36, a groove 38, etc. (see FIG. 1, etc.).

[0024] The cutting edge 26 is formed at the intersection of the rake face 22 and the clearance face 24. In this embodiment, the cutting edge 26 of the cutting edge member 20 is formed in a substantially semicircular arc shape when viewed from above from the side where the rake face 22 of the cutting edge member 20 is located (see FIG. 3, etc.). The central angle α of the substantially arc-shaped cutting edge 26 is slightly greater than 180°, for example, approximately 185°. When the central angle α is 185°, the left and right angles about the central axis 10X are α / 2, or 92.5° (see FIG. 14). The rear of the cutting edge 26, the relief portion near the base insert member 10, is called a back taper, which gradually decreases from the maximum width of the cutting edge 26 (indicated by the reference symbol 40 in FIG. 14). The relief angle β of the back taper 40 (the angle relative to a line parallel to the central axis 10X) is, for example, 2.5° (see FIG. 14). Incidentally, in a front view of the cutting insert 1 seen from the tip end side of the base insert member 10 along the central axis 10X, the back taper 40 is hidden and cannot be seen (see Figs. 2, 3, etc.). In Fig. 3, etc., the approximate center of the cutting edge 26, which is approximately arc-shaped as described above, is indicated by the reference symbol 22c. Although not shown in detail, the cutting edge 26 may be chamfered by honing.

[0025] The rake face 22 is formed on the upper surface side of the cutting edge member 20 along the substantially arc-shaped cutting edge 26. The flank face 24 is formed on the side surface of the cutting edge member 20 along the substantially arc-shaped cutting edge 26 as a positive surface that slopes toward the lower surface as it moves away from the cutting edge 26.

[0026] The breaker wall 28 is formed inside the cutting edge 26 so as to protrude above the cutting edge member 20. The breaker wall 28 in the cutting edge member 20 of this embodiment is generally arc-shaped overall, and is divided into multiple sections by multiple recesses 36, which will be described later (see FIGS. 1, 5, etc.). In the cutting edge member 20 of this embodiment, the distance between the breaker wall 28 and the cutting edge 26 (referred to as the breaker width, and indicated by the symbol Wb in FIG. 9) is uniform, and the surface of the breaker wall 28 has a shape similar to the peripheral surface of a truncated cone (see FIG. 7, etc.).

[0027] The boss portion 30 is formed as a top portion that protrudes above the breaker wall 28. A boss surface 32 is formed on the upper side of the boss portion 30 (see FIGS. 5, 6, etc.). The boss surface 32 may be chamfered (in FIG. 5, the chamfered portion is indicated by reference numeral 32c). The boss portion 30 of the cutting edge member 20 of this embodiment has an overall shape resembling a semicircular truncated cone with a small thickness (height). The boss surface 32, which is the upper surface of the boss portion 30, is divided into multiple portions by multiple recesses 36, which will be described later (see FIGS. 1, 5, etc.). The inside of an arc-shaped depression 34, which will be described later, forms a central boss portion (the portion of the boss portion 30 near the approximate center portion 22c) (see FIG. 5, etc.).

[0028] The recesses 36 are formed in the boss portion 30 so as to extend toward the cutting edge 26, improving the supply of coolant C to the cutting edge 26 (see FIG. 5, etc.). Compared to the flow of coolant C' in a cutting edge member 20' in which no recesses are formed in the boss portion 30' (see FIGS. 12 and 13), the amount of coolant C supplied to the cutting edge 26 can be increased by passing through the grooves 38 formed by the recesses 36 (see FIGS. 7 and 8). These recesses 36 are preferably formed to more efficiently supply coolant C to the cutting edge 26. In the cutting edge member 20 of this embodiment, the recesses 36 are formed radially from the central boss portion 30c. These recesses 36 are formed as linear grooves with a constant width when viewed from above (see FIGS. 3 and 6). Furthermore, in the cutting edge member 20 of this embodiment, the height of the bottom surface 36b of the recesses 36 is lower than the height of the cutting edge 26 when viewed from the front or side (see FIGS. 8 and 9). In this case, when chips are generated, the coolant gets into the gap between the chips and the rake face 22, making it easier to deliver the coolant to the cutting point.

[0029] Here, in the cutting edge member 20 of this embodiment, the width W of the breaker wall 28 28 The width W of the groove 38 formed by the recess 36 is 38 Larger shape (width W of breaker wall 28) 28 >Width W of the groove 38 formed by the recess 36 38) (see FIG. 5, etc.). In the case of such a shape, the area where the breaker wall 28 is located is more dominant than the area where the groove 38 is located with respect to the cutting edge 26, so that the coolant C can be supplied to the groove 38 formed by the recess 36, and stable chip disposal can be achieved by the effect of the breaker wall 28. 28 " and "The width W of the groove 38 formed by the recess 36 38 There are various ways to define "," but as an example, in this embodiment, it is defined as follows. That is, first, consider the intersection line L1 (which includes a virtual intersection line or a virtual extension of the intersection line; the same applies below) between the boss surface 32 and the breaker wall 28. In this embodiment, the chamfered portion 32c described above is considered to be included in part of the boss surface 32, and a virtual intersection line L1 between the boss surface (including the chamfered portion 32c) 32 and the breaker wall 28 is assumed (see FIG. 5). The width of the breaker wall 28 along the intersection line L1 and the width of the groove 38 formed by the recess 36 along the intersection line L1 are defined as the respective widths, and are denoted by the symbol W 28 ,W 38 The width W of the breaker wall 28 thus defined is expressed as 28 and the width W of the groove 38 formed by the recess 36 38 As mentioned above, the width W of the breaker wall 28 28 >Width W of the groove 38 formed by the recess 36 38 and in some cases, the width W of the breaker wall 28 28 The width W of the groove 38 formed by the recess 36 38 In the finishing process assumed to be used in this embodiment, the cutting depth and feed rate are small, so the width W of the breaker wall 28 28 The width W of the groove 38 formed by the recess 36 38 If the width is less than twice the width of the breaker wall 28, the breaker wall 28 may not function sufficiently, resulting in poor chip control.

[0030] The recess 34 is formed so as to be continuous with the recess 36. The recess 34 is formed in a substantially arc shape around the central boss portion 30c, which is the center of the cutting edge 26, so that the coolant C that has entered the recess 34 can flow out into the connected recess 36.

[0031] In the cutting insert 1 of this embodiment, in which the cutting edge member 20 is configured as described above, the boss portion 30 is formed with recesses 36 leading to the cutting edge 26, so that the coolant C that would otherwise be dispersed at the boss portion 30 or the boss surface 32 can pass through the recesses 36 (grooves 38) and sufficiently reach the cutting edge 26. Furthermore, by making the bottom surfaces 36b of the recesses 36 lower than the cutting edge 26, the coolant C can get between the chips and the rake face 22 even when chips are generated, making it easier for the coolant C to reach the cutting point (see FIG. 8, etc.). Furthermore, since the structure has breaker walls 28 and recesses 36 through which the coolant C passes alternately, it is easy to adapt to changes in the machining direction during copy cutting, and it is easy to achieve both chip control and a long tool life.

[0032] The above-described embodiment is a preferred example of the present invention, but is not limited thereto. Various modifications are possible without departing from the spirit and scope of the present invention. For example, in the above-described embodiment, the cutting edge member 20 is shown with a uniform distance (breaker width Wb) between the breaker wall 28 and the cutting edge 26 (see FIG. 7, etc.). However, the distance (breaker width Wb) between the breaker wall 28 and the cutting edge 26 may be non-uniform. A specific example of a cutting edge member 20 with a non-uniform breaker width Wb is one in which the breaker wall 28 is provided with two protrusions 28g (see FIG. 10). By providing such protrusions 28g and setting the optimal breaker width WB depending on the position of the cutting edge 26 to be used, better chip control is possible. Alternatively, the boss portion 30 may be provided with a small recess 37 in the shape of a notch, separate from the recess 36 (see FIG. 11). In this case, coolant C is also supplied from the small recess 37, allowing more coolant C to be supplied toward the cutting edge 26.

[0033] The specific form of the recess 36 formed in the boss portion 30 is also not limited to the above. Although not specifically illustrated here, for example, the recess 36 may be formed as a hole or tunnel. In such a case, the recess 36 has a structure in which the upper portion is not open, allowing the coolant C introduced into the recess 36 to be supplied to the cutting edge 26 without leaking to the outside. Alternatively, the recess 36 may not be a single groove but may have a branched shape. In such a case, the coolant C can be supplied so as to be evenly distributed throughout the entire cutting edge 26. Alternatively, the recess 36 may be shaped to be inclined with respect to the flat boss surface 32. In such a case, the coolant C can more easily penetrate between the cutting edge 26 and the chip. Furthermore, although the recess 36 in the above-described embodiment is formed perpendicular to (the tangent to) the cutting edge 26, the recess 36 may be formed in a shape that is not perpendicular to (the tangent to) the cutting edge 26. In this case, under cutting conditions in which a portion of the entire cutting edge 26 is used intensively, the coolant C can be supplied intensively to that portion from the plurality of recesses 36.

[0034] Furthermore, in the above-described embodiment, the present invention has been described as being applied to a cutting insert 1 having a cutting edge member 20 brazed to a base insert member 10, but this is merely a preferred example, and it goes without saying that the present invention can also be applied to cutting tools other than such cutting insert 1. [Industrial Applicability]

[0035] The present invention is suitable for application to cutting tools such as cutting inserts. [Explanation of symbols]

[0036] 1...Cutting insert (cutting tool) 10...Base insert member 10X…center axis 20...Cutting edge material 22...Scooping surface 22c…approximately central part 24...flank 26...(arcuate) cutting edge 28...Breaker Wall 28g…Protrusion 30...Boss section 30c...Central boss 32...Boss stage 32c...Beveled part 34...(arc-shaped) depression 36...(multiple) recesses 36b...Bottom of recess 37...Small recess 38... (recessed) groove 40...Back taper C...Coolant L1: Intersection line between the boss face and the breaker wall (including imaginary intersection line and imaginary extension line of the intersection line) W 28 …Width of breaker wall 28 along intersection line L1 W 38 ...width of the groove 38 formed by the recess 36 along the intersection line L1 Wb...breaker width (distance between breaker wall 28 and cutting edge 26) α...Cutting edge central angle β…Back taper relief angle

Claims

1. A cutting tool, The scooping surface and The relief surface and a cutting edge formed at an intersection line between the rake face and the flank; a breaker wall formed inside the cutting edge and protruding upward from the cutting tool; a boss portion including a boss surface formed above the breaker wall; a plurality of recesses formed in the boss portion and extending toward the cutting edge; Equipped with a width in a direction in which the cutting edge of the breaker wall extends along an intersection line or a virtual intersection line between the boss surface and the breaker wall is wider than a width of a groove formed by the recess on a virtual extension of the intersection line.

2. The cutting tool according to claim 1 , wherein the width of the breaker wall is at least twice the width of the groove formed by the recess.

3. The cutting tool according to claim 1 , wherein the cutting edge is formed in an arc shape when viewed from above from the side where the rake face is located.

4. The cutting tool according to claim 3 , wherein the cutting edge is arc-shaped with a central angle exceeding 180°.

5. The cutting tool according to claim 1 , wherein the recess is formed as a groove that is linear in top view.

6. The cutting tool according to claim 5 , wherein the recess is formed as a groove with a constant width.

7. The cutting tool according to claim 1 , wherein a height of a bottom surface of the recess is lower than a height of the cutting edge in a front view or a side view perpendicular to a top view.

8. The cutting tool according to claim 1 , wherein the spacing between the breaker wall and the cutting edge is uniform.

9. The cutting tool according to claim 1 , wherein the spacing between the breaker wall and the cutting edge is non-uniform.

10. The cutting tool according to claim 1 , wherein an arc-shaped depression continuous with the recess is formed near the center of the arc-shaped cutting edge.

11. The cutting tool according to claim 1 , wherein the cutting edge is chamfered by honing.

12. The cutting tool according to claim 1 , wherein the recess is formed in a hole shape.

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