Cutting tool

Abstract

Provided is a cutting tool having a flat top surface and excellent chip handling performance. The cutting tool includes: a peripheral side surface; a flat top surface that forms a part of the upper surface, and the part of the upper surface other than the top surface is recessed; a cutting edge that is formed at least in a ridge line where the peripheral side surface intersects with the top surface, and is a ridge line connecting two linear ridge lines at a corner (R); and a fan-shaped rake face having alternately arranged ridge portions and groove portions, and the ridge portions and the groove portions are recessed and inclined together from a corner (R) side where the intersection line with the top surface is wavy toward a fan axis portion that is a radiation center.

Description

Technical Field

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

[0002] There is known a cutting tool having a cutting edge made of a superhigh-pressure sintered body using diamond or the like as a raw material (for example, see Patent Document 1).

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: WO 2016 / 035490 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] In a cutting tool having a cutting edge made of a superhigh-pressure sintered body, the cutting edge is generally formed by grinding the upper surface. Therefore, it is difficult to provide a bulge higher than the flat top surface serving as the grinding surface, and it is difficult to form a chip-breaking groove with excellent chip disposal performance.

[0008] The present invention aims to solve the above problems and provides a cutting tool having a flat top surface and excellent chip disposal performance.

[0009] Solution to the Problem

[0010] A cutting tool according to an embodiment of the present invention includes: a peripheral side surface; a flat top surface constituting a part of the upper surface, with the other part of the upper surface being recessed; a cutting edge formed at least in a ridge line where the peripheral side surface intersects the top surface, the ridge line connecting two linear ridge lines at a corner R; and a fan-shaped rake face having alternately arranged ridge portions and groove portions, the ridge portions and the groove portions being recessed and inclined together from the corner R side where the intersection line with the top surface is wavy toward the fan axis portion serving as the radiation center.

[0011] Advantages of the Invention

[0012] According to the present invention, it is possible to provide a cutting tool having a flat top surface and excellent chip disposal performance. Brief Description of the Drawings

[0013] Figure 1 is an overall perspective view of a cutting tool equipped with a cutting insert of the present embodiment;

[0014] Figure 2 is an overall perspective view of the cutting insert;

[0015] Figure 3 is a partially enlarged view of the cutting insert;

[0016] Figure 4It is a partial enlarged view of the vicinity of the corner R of the blade member as observed obliquely;

[0017] Figure 5 It is a partial enlarged view of the vicinity of the corner R of the blade member as observed from above;

[0018] Figure 6 It is a cross-sectional view of the blade member taken along C-C;

[0019] Figure 7 It is a cross-sectional view of the blade member taken along D-D;

[0020] Figure 8 It is an enlarged schematic view of the corner R;

[0021] Figure 9 It is a partial enlarged view of the cutting blade in another embodiment;

[0022] Figure 10 It is a partial enlarged view of the vicinity of the corner R of the blade member in another embodiment as observed obliquely.

[0023] Explanation of reference numerals

[0024] 100, 100’: Cutting blade;

[0025] 110, 110’: Blade member;

[0026] 120: Sintered body;

[0027] 121, 121’: Flank face;

[0028] 122: Peripheral side face;

[0029] 123: First ridge line;

[0030] 124: Second ridge line;

[0031] 125, 125’: Corner R;

[0032] 126, 126’: Second rake face;

[0033] 127, 127’: Protrusion;

[0034] 128: Chip breaker wall surface;

[0035] 131, 131’: Fan shaft part;

[0036] 132, 132’: First rake face;

[0037] 133, 133’: Ridge part;

[0038] 134, 134’: Groove part;

[0039] 140: Base;

[0040] 190, 190': Base

[0041] 191: Mounting hole

[0042] 200: Cutting tool

[0043] 210: Main body part

[0044] 220: Mounting base

[0045] 310: Mounting screw

[0046] 320: Spacer Detailed implementation mode

[0047] With reference to the attached drawings, the implementation modes of the present invention will be described. Additionally, in each figure, components marked with the same reference numerals have the same or similar structures. Furthermore, in each figure, in the case where there are multiple structures with the same or similar structures, to avoid complication, sometimes only a part is marked with reference numerals, and the same reference numerals are omitted for the other parts. Moreover, not all the structures described in the implementation modes are necessary as solutions to solve the problems.

[0048] Figure 1 Fig. is an overall three-dimensional view of the cutting tool 200 with the cutting blade 100 of this implementation mode installed. The cutting tool 200 in this implementation mode is a cutting tool for a lathe. The main body part 210 has a mounting base 220 for mounting the cutting blade 100. Additionally, in this implementation mode, the case where the cutting blade 100 is replaceably mounted on the main body part 210 and the whole functions as a cutting tool 200 is described. However, from the aspect of the function of the cutting blade 100 for cutting a workpiece, the cutting blade 100 itself can also be regarded as a cutting tool. Moreover, not limited to replaceable cutting blades, in the case of adopting a form in which a cutting edge component equivalent to the cutting blade 100 described below is fixedly mounted on the main body part, the whole can also be regarded as a cutting tool.

[0049] The mounting base 220 is a mounting surface for the cutting blade 100 provided near the front end of the main body part 210. The mounting base 220 is provided with an internal threaded hole. When mounting the cutting blade 100, the internal threaded hole is substantially coaxial with the mounting hole 191 provided at the approximate center of the cutting blade 100. The cutting blade 100 is fixed on the mounting base 220 by a mounting screw 310 screwed through the mounting hole 191 and the internal threaded hole. Additionally, in the illustrated implementation mode, in order to extend the tool life, a spacer 320 with a certain thickness is clamped between the mounting base 220 and the cutting blade 100.

[0050] Figure 2This is an overall perspective view of the cutting insert 100. The overall shape of the cutting insert 100 is formed as a columnar shape with a substantially rhombic upper surface and bottom surface. The cutting insert 100 is composed of a base 190 and a cutting edge member 110. The base 190 is provided with a mounting hole 191 through which a mounting screw 310 is inserted at a substantially central portion. The base 190 is made of, for example, steel or cemented carbide as a raw material. In the base 190, a stepped portion is provided at one of the acute-angle corners forming the upper surface, and the cutting edge member 110 is fixed to this stepped portion by brazing or the like.

[0051] Figure 3 This is a partially enlarged view of the cutting insert 100, specifically Figure 2 an enlarged view of part A shown in the figure. As shown in the figure, the cutting edge member 110 in the present embodiment has a double-layer structure of a sintered body 120 and a base 140. The sintered body 120 and the base 140 are each in a substantially triangular prism shape with the same overall size, and are stacked one on top of the other. The sintered body 120 contains diamond accounting for more than 80% of its volume. Diamond has excellent strength and wear resistance, and if it is used for the cutting edge, it can be expected to extend the service life of the cutting insert 100. In the present embodiment, the sintered body 120 is set as a diamond sintered body obtained by sintering diamond powder, but single-crystal diamond synthesized by a vapor synthesis method can also be used to form the same shape. The base 140 is made of, for example, cemented carbide as a raw material. The cutting edge member 110 in the present embodiment adopts a double-layer structure of a sintered body 120 and a base 140, but for example, the whole can also be formed as a diamond sintered body.

[0052] The sintered body 120 has a top surface 121 that constitutes a part of the upper surface of the substantially triangular prism shape and a peripheral side surface 122 that constitutes the side surface. The top surface 121 is a polished flat surface, and for example, the surface roughness is adjusted within a range of 0.05 μm or more and less than 0.2 μm. The top surface 121 is formed as a part of the triangle of the upper surface that is continuous with the peripheral portion and the raised portion 127. The ridge lines where the top surface 121 intersects the peripheral side surface 122 include: a linear first ridge line 123 that constitutes one side of the triangle, a linear second ridge line 124 that also constitutes another side of the triangle, and an arc-shaped corner R125 that connects the first ridge line 123 and the second ridge line 124. In the present embodiment, the corner R125 functions as a cutting edge. In addition, the cutting edge can also be formed continuously with the first ridge line 123 and the second ridge line 124. The area near the cutting edge on the top surface 121 functions as a land surface.

[0053] The portion of the upper surface of the sintered body 120 other than the above-mentioned top surface 121 is recessed. This recess is mainly composed of a first rake face 132, a second rake face 126, and a chip breaker wall surface 128. The first rake face 132 is fan-shaped and inclined with the corner R125 side as an arc. The specific structure of the first rake face 132 will be described in detail below.

[0054] The second rake part 126 is provided in a continuous manner with the first rake part 132. In addition, it is an inclined surface provided in such a way that the deeper it is from the first ridge line 123 and the second ridge line 124 and towards the inside of the triangle, the deeper the depth from the top surface 121. The second rake part 126 and the first rake part 132 together function as a rake face. The chip breaker wall surface 128 is formed as the two side surfaces of a raised part 127 provided in a way that bulges from the second rake part 126. The raised part 127 is connected along the bisector that bisects the included angle formed by the first ridge line 123 and the second ridge line 124 through the intersection point where the first ridge line 123 and the second ridge line 124 extend and intersect respectively. Therefore, overall, it can be said that the depression on the upper surface of the sintered body 120 is composed of: a first recess surrounded by the second rake part 126 and the chip breaker wall surface 128 on the first ridge line 123 side; and a second recess surrounded by the second rake part 126 and the chip breaker wall surface 128 on the second ridge line 124 side.

[0055] Figure 4 It is a partial enlarged view of the vicinity of the corner R125 of the cutting edge member 110 when observed obliquely. Specifically, it is Figure 3 an enlarged view of part B shown in the figure. As described above, the first rake part 132 is fan-shaped inclined with the corner R125 side as an arc and has alternately arranged ridge parts 133 and groove parts 134, and the ridge parts 133 and the groove parts 134 are recessed and inclined together from the top surface 121 towards the fan shaft part 131 which is the radiation center of this fan shape.

[0056] The fan shaft part 131 is, for example, the part corresponding to the hub in a wheel, and the ridge part 133 is the part corresponding to the spoke. The ridge part 133 is formed in a way that bulges convexly towards the upper surface direction which is the top surface 121, and the groove part 134 is formed in a way that excavates convexly towards the direction opposite to the upper surface. As shown in the figure, the first rake part 132 in this embodiment has five ridge parts 133 and four groove parts 134. The ridge parts 133 are respectively connected to the fan shaft part 131, and the groove parts 134 are provided between two adjacent ridge parts 133.

[0057] The ridge lines of each ridge part 133 and the valley lines of each groove part 134 are adjusted to be inclined within the range of 10° to 30° with respect to the top surface 121. Therefore, the first rake part 132 as a whole functions as a rake face with a rake angle of 10° to 30°. In addition, a second rake part 126 is provided as an inclined surface continuous with the first rake part 132. Moreover, a raised part 127 is provided in a way that bulges from the second rake part 126. However, since the top surface 121 is formed by grinding the upper surface of the sintered body 120, the height of the ridge line of the raised part 127 is below the height of the top surface 121.

[0058] The cutting edge member 110 having such a shape, and even the cutting blade 100, have excellent chip handling performance for the chips discharged from the workpiece. Specifically, the chips cut by the cutting edge formed on the corner R125 are bent and squeezed more and more toward the fan shaft portion 131 while sliding along the ridge portion 133 and the groove portion 134. The chips thus squeezed are already easily broken. Further, the chips slide on the second rake face 126 and are constrained by the raised portion 127, and while curling, they collide with the peripheral side face 122 or the workpiece, making it even easier to break. Or, the squeezed chips are easily broken due to their own weight and their own swinging. That is, even if there is no convex portion higher than the cutting edge in the cutting blade 100 of the present embodiment, the binding force for capturing the chips can be ensured, and the constrained chips can be broken more efficiently.

[0059] Figure 5 FIG. is a partially enlarged view of the vicinity of the corner R125 of the cutting edge member 110 as viewed from above. As shown in the figure, the fan shaft portion 131 at the fan shaft position of the sector-shaped first rake face 132 is the intersection point where the center lines of the respective ridge portions 133 intersect. In the present embodiment, the fan shaft portion 131 is set to coincide with the center of curvature of the corner R125 (the center of the circle indicated by the double-dot chain line in the figure). It has been confirmed that when the fan shaft portion 131 is set to coincide with the center of curvature of the corner R125 or is located on the opposite side of the corner R125 with respect to the center of curvature (the side away from the corner R125), the chip breakability and chip dischargeability are improved.

[0060] In addition, in the present embodiment, five ridge portions 133 are provided, and the number of ridge portions 133 can be determined according to the radius of curvature of the corner R125. Specifically, when the radius of curvature of the corner R is r (mm), it can be confirmed that the number L of ridge portions only needs to be an integer satisfying 4r + 1 ≤ L ≤ 10r + 2. In the illustrated example, the radius of curvature is 0.4 mm, but since the radius of curvature r of the corner R required according to the material of the workpiece, the cutting purpose, etc. is different, the number L of ridge portions is determined according to each situation. In particular, if the number L of ridge portions is odd, the center line connected to the vertex of the corner R is a ridge portion, and it can be confirmed that the breakability is improved compared with the case where it is a groove portion. That is, it can be said that L is preferably set to an odd number among the L values satisfying the above relational expression.

[0061] Figure 6 is Figure 5 The C-C sectional view of the cutting edge member 110 shown in FIG. As shown in the figure, the ridge portions 133 and the groove portions 134 are alternately arranged and are integrally recessed with respect to the top faces 121 at both ends. In addition, in the present embodiment, the angle between the top face 121 and the peripheral side face 122 is an acute angle.

[0062] Figure 7 is Figure 5The D-D sectional view of the blade member 110 shown. D-D is a plane along the above-mentioned bisector. As shown in the figure, the intersection line of the upper surface and the section descends from the boundary between the top surface 121 and the central ridge 133 to reach the fan shaft portion 131, and then depresses as the second rake face 126 to the lowest point. After that, it rises as the raised portion 127 to reach the top surface 121 on the opposite side of the corner R125.

[0063] Figure 8 An enlarged schematic view of the corner R125. Specifically, it is Figure 5 The enlarged view of the portion E shown. As described above, the ridge 133 and the groove 134 are formed from the top surface 121 to the fan shaft portion 131. However, since the top surface 121 is a ground plane, the intersection line L between the top surface 121 and the ridge 133 and the groove 134 appears wavy.

[0064] The intersection line L becomes a convex curve protruding in the direction opposite to the corner R125 at the portion corresponding to the ridge 133, and becomes a convex curve protruding in the direction of the corner R125 at the portion corresponding to the groove 134. The connection point of the two is set as the inflection point P1. Among two adjacent P1s, the distance d1 between the two P1s (in the example of the figure, the two P1s sandwiching the curve of the central ridge 133a) that are the curves sandwiching the ridge 133 is taken as the width of the ridge 133 at the boundary with the top surface 121. In addition, among two adjacent P1s, the distance d2 between the two P1s (in the example of the figure, the two P1s sandwiching the curve of the groove 134a adjacent to the central ridge 133a) that are the curves sandwiching the groove 134 is taken as the width of the groove 134 at the boundary with the top surface 121. At this time, it is preferable that d2 > d1. That is, at the boundary with the top surface 121, the width of the groove 134 is preferably larger than the width of the ridge 133. When such a relationship is satisfied, it is confirmed that the chips are smoothly guided to the first rake face 132. In addition, the definition of the width is not limited to this, as long as it is possible to distinguish the portion of the convex curve protruding in the direction opposite to the corner R125 at the portion corresponding to the ridge 133 and the portion of the convex curve protruding in the direction of the corner R125 at the portion corresponding to the groove 134. For example, even if there is a straight portion between the two curves, as long as it can be distinguished.

[0065] In addition, the ridge portion 133 has a constant width from the arc of the corner R125 toward the sector shaft portion 131. Specifically, for example, on the intersection line L, two points where a straight line equidistant from two straight lines, one being the straight line connecting two P1s that sandwich the ridge portion 133 and the other being the straight line parallel to this straight line and passing through the vertex P0 of the curve of the ridge portion 133, intersect the intersection line L are respectively set as the intermediate points P3. The width d3 when the ridge portion 133 is cut by a plane passing through these two intermediate points P3 and parallel to the rake angle of the rake face is defined as the width of the ridge portion 133. This width d3 is constant toward the sector shaft portion 131. For example, d3 is preferably 0.01 mm or more and 0.3 mm or less. If the width of the ridge portion 133 is made constant, the groove portion 134 is provided in such a manner that its width gradually decreases from the arc of the corner R125 toward the sector shaft portion 131. When the relationship between the width of the ridge portion 133 and the width of the groove portion 134 is satisfied, it is confirmed that the chip is smoothly extruded toward the sector shaft portion 131. In addition, in the above description, the width of the ridge portion 133 is defined as being constant by using the width d3, but the definition of the width is not limited to this. Furthermore, it is confirmed that even when the width varies somewhat, the same effect can be obtained when the convex curve of the ridge portion 133 maintains the curvature radius of the top extending toward the sector shaft portion 131. As the curvature radius of the top, when viewed from above, it is preferably 0.01 mm or more and 0.1 mm or less.

[0066] Next, as another embodiment, the cutting blade 100' will be described. The cutting blade 100' has a different structure of the rake portion compared to the cutting blade 100. The structures and functions of other elements are the same as those of the corresponding elements of the cutting blade 100, so the description thereof is omitted, and the different structures and functions will be described.

[0067] Figure 9 FIG. 7 is a partially enlarged view of the cutting blade 100' in another embodiment. It is assumed that the curvature radius of the corner R125' in the cutting edge member 110' of the cutting blade 100' is 0.8 mm larger than the curvature radius of the corner R125 in the cutting edge member 110 of the cutting blade 100. Accordingly, the corner of the base 190' is also formed as a curve.

[0068] The first rake portion 132' is the same as the first rake portion 132 of the cutting blade 100 in that it is fan-shaped and inclined with the corner R125' side as an arc, but it becomes a larger fan shape to match the size of the corner R125'.

[0069] Figure 10 FIG. 14 is a partially enlarged view of the vicinity of the corner R125' of the cutting edge member 110' observed obliquely, specifically as Figure 9An enlarged view of part F as shown. The first rake part 132’ has ridges 133’ and grooves 134’ arranged alternately, and the ridges 133’ and grooves 134’ are recessed and inclined together from the top surface 121 toward the sector axis part 131’ which is the radiation center of the sector. However, on the cutting edge member 110’, the raised part 127’ protrudes toward the corner R125’, and the sector axis part 131’ is covered by the raised part 127’. Therefore, each ridge 133’ and groove 134’ do not reach the sector axis part 131’ and are set to a length of about half of the top surface 121’ to the sector axis part 131’.

[0070] The cutting blade 100’ using the cutting edge member 110’ configured in this way can make the chips quickly collide with the raised part 127’ after being pressed by the first rake part 132 and guide them to the peripheral side surface 122 of the left and right second rake parts 126 or the workpiece. Depending on the material of the workpiece, the cutting purpose, etc., there are also cases where such chip processing is preferred, and the cutting blade 100’ is suitable for such cases.

[0071] In the above-described embodiment, the case where the cutting blades 100, 100’ are rhombic columns has been described, but the overall shape is not limited to this. In addition, the mounting method of mounting the cutting blade to the main body part 210 is not limited to the case of using the mounting screw 310. In addition, the cutting edge member fixed to the cutting blade is not limited to one, and may also be multiple. If a cutting blade has multiple cutting edge members, by changing the mounting orientation when mounting to the main body part 210, one cutting blade can be used for a long time.

Claims

1. A cutting tool, characterized in that, Comprising: The circumferential side surface; A flat top surface forming part of the upper surface, with the part of the upper surface other than the top surface being recessed; A cutting edge formed at least in the ridge line where the circumferential side surface intersects with the top surface, and in the ridge line connecting the corners (R) of two linear ridge lines; And A sector-shaped rake face having alternately arranged ridge portions and groove portions, with the ridge portions and the groove portions being recessed and inclined together from the corner (R) side where the intersection line with the top surface is wavy towards the sector axis portion as the radiation center.

2. The cutting tool according to claim 1, characterized in that, At the boundary with the top surface, the width of the groove portion is wider than the width of the ridge portion.

3. The cutting tool according to claim 1 or 2, characterized in that, The width of the ridge portion is set constantly from the boundary with the top surface where the intersection line appears towards the sector axis portion, and the groove portion is set in such a way that its width gradually decreases from the boundary with the top surface where the intersection line appears towards the sector axis portion.

4. The cutting tool according to claim 1 or 2, characterized in that, The number L of the ridge portions is an integer satisfying 4r + 1 ≤ L ≤ 10r + 2 when the radius of curvature of the corner (R) is set to r (mm).

5. The cutting tool according to claim 4, characterized in that, The number L is an odd number.

6. The cutting tool according to claim 1, characterized in that, The sector axis portion is set in a manner that coincides with the center of curvature of the corner (R), or is located on the opposite side of the corner (R) with respect to the center of curvature.

7. The cutting tool according to claim 1, characterized in that, Comprising: An inclined surface provided in a continuous manner with the rake face; And A raised portion connected along the bisector of the two linear ridge lines and provided in a manner that rises from the inclined surface.

8. The cutting tool according to claim 1, characterized in that, The rake face is formed of a sintered body containing 80% or more by volume of diamond.

9. The cutting tool according to claim 1, characterized in that, The rake face is a sector with an arc-shaped corner (R).

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