Rotary Cutting Tools

Abstract

To provide a rotary cutting tool with high processing quality.SOLUTION: A rotary cutting tool comprises a base metal, and a tip provided on an outer peripheral side of the base metal. An outer peripheral cutting edge is provided at a boundary between a rake face and an outer peripheral flank surface of the tip, a margin is provided on a rear side in a rotation direction of the outer peripheral cutting edge, a groove having a depth of 0.005 mm or more and 0.5 mm or less is provided in the margin, the groove is provided parallel to or at an angle to the outer peripheral cutting edge, and a toll tip side of the groove is provided on a rear side in the rotation direction with respect to a ridge line of the outer peripheral cutting edge.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to rotary cutting tools. [Background technology]

[0002] A conventional rotary cutting tool is disclosed in, for example, Japanese Patent Application Laid-Open No. 2014-87856 (Prior Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-87856 A Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional rotary cutting tools have the problem of low machining quality. [Means for solving the problem]

[0005] The rotary cutting tool includes a base metal and a tip provided on the outer periphery of the base metal. An outer cutting edge is provided at the boundary between the rake face and the outer flank of the tip. A margin is provided on the rear side of the outer cutting edge in the direction of rotation. A groove having a depth of 0.005 mm to 0.5 mm is provided in the margin. The groove is provided parallel to or at an angle to the outer cutting edge. The tool tip side of the groove is provided rearward in the direction of rotation from the ridge of the outer cutting edge.

[0006] The present disclosure relates to a PCD (Polycrystalline Diamond) rotary cutting tool that can perform high-precision machining for hole finishing of core aluminum components for automobiles (cylinder heads / blocks / steering / hydraulic control valves), sintered metals, etc., and can improve the surface roughness of workpiece holes and perform machining on thin-walled parts where diameter shrinkage is an issue.

[0007] Conventionally, carbide reamers or PCD reamers are used for the internal diameter finishing cutting of aluminum parts. In general, the internal diameter after drilling shrinks due to elastic recovery, or expands due to runout of the reamer, making it very difficult to set the reamer diameter that determines the internal diameter.

[0008] Generally, the reamer diameter is set to be 1 to 3 μm smaller than the upper limit of the inner diameter tolerance, and the cutting edge diameter tolerance is set to be around 5 μm.

[0009] When using a reamer tool with the above tolerance, the hole diameter is 2 to 3 μm smaller than the reamer diameter, so the cutting starts at a value 3 to 6 μm smaller than the cutting edge diameter. In other words, the cutting diameter shrinkage is 2 to 3 μm, and the cutting edge diameter setting range is 1 to 3 μm.

[0010] As a specific example, in the case of φ18H7 (+0.018 / 0) (H7 is the dimensional tolerance of the hole used for fitting: JIS B 0401-1, -2 (1998)), if the cutting edge diameter is φ18.016+0 / -0.005 and the shrinkage amount is 3 μm, it will start from below the median of the allowable tolerance, which is φ18.008 to 18.013.

[0011] Furthermore, with continued use, the sharpness of the tool decreases and the inner diameter also becomes smaller, so the tool must be replaced 1 to 2 μm before the lower tolerance limit. Therefore, controlling the amount of shrinkage can be said to affect the tool life.

[0012] As a result, by setting the tool diameter toward the upper limit of the tolerance, the tool life can be extended, so there is a need to suppress the shrinkage of the inner diameter.

[0013] In order to meet these needs, we determine the reamer diameter and margin width, etc., based on experience and previous examples of changes in the inner diameter due to the inner diameter size or the thickness of the processed area.

[0014] Aluminum parts are increasingly being designed with complex shapes and reduced weight to improve functionality and fuel efficiency. Furthermore, to improve productivity, efforts are being made to shorten production times by increasing tool feed speeds and consolidating two processes into one.

[0015] Due to the complex shape and weight reduction, the workpiece tends to be thin-walled, and thin-walled workpieces are machined at high feed rates. As a result, the cutting resistance increases and the cutting point temperature rises, and the amount of elastic deformation increases, resulting in a large change in diameter. In addition, in continuous machining, the cutting resistance increases due to wear at the cutting edge of the reamer, making it difficult to ensure quality.

[0016] Although coolant is used to cool the cutting edge and workpiece and to prevent shrinkage, (1) it is not supplied to the desired position, (2) the coolant supply position shifts due to re-grinding, and (3) coolant does not reach the interface between the outer periphery of the cutting edge (margin) and the inner diameter, which causes shrinkage due to temperature changes caused by frictional heat generated at the margin, and tiny cutting chips get caught in the gap between the inner surface of the machined hole and the margin, causing scratches, and thus deteriorating the quality of the inner diameter.

[0017] To improve quality such as the inner diameter and roundness, we devised a structure that supplies coolant to the boundary between the outer circumference (margin) of the cutting edge, which determines the inner diameter, and the inner diameter, and creates a groove in the margin to suppress cutting heat during processing.

[0018] The PCD rotary cutting tool of the present disclosure has the following configuration.

[0019] A) It comprises a base metal and a chip provided on the outer periphery of the base metal.

[0020] B) A peripheral cutting edge is provided at the boundary between the cutting face and the peripheral flank of the insert.

[0021] C) A margin is provided on the rear side of the peripheral cutting edge in the direction of rotation.

[0022] D) A groove 0.005 to 0.5 mm deep is provided in the margin.

[0023] E) The grooves are provided parallel to or at an angle to the peripheral cutting edge.

[0024] F) The tip side of the groove is provided behind the ridge of the peripheral cutting edge in the direction of rotation.

[0025] A rotary cutting tool constructed in this manner can achieve high machining quality.

[0026] Preferably, the device has the following configuration.

[0027] G) The groove width shall be 0.03 to 0.15 mm.

[0028] H) The portion of the groove at the tip of the tool is closest to the ridge of the peripheral cutting edge, and the portion toward the rear end of the tool is farther away from the ridge of the peripheral cutting edge.

[0029] I) The pitch of the groove may be at least equal to or less than the feed amount per revolution of the tool.

[0030] J) The cross-sectional shape of the groove shall be trapezoidal or circular.

[0031] By forming a groove in the margin, coolant is supplied to the boundary between the outer circumference of the cutting edge (margin), which determines the inner diameter, and the inner diameter of the machined hole, which suppresses cutting heat during processing, reduces changes in the inner diameter, and stabilizes the quality of the inner diameter.

[0032] In addition, since there is no groove in the immediate vicinity of the rear side of the ridge of the outer cutting edge in the direction of rotation, a small margin acts over the entire outer cutting edge, allowing for a stable burnishing action.

[0033] Furthermore, even when resharpening, the cutting edge can be restored to the same performance as when it was new, extending the tool life and reducing running costs.

[0034] As a specific means for providing the grooves, thermal processing (laser) can be used.

[0035] In the case of WEDM (Wire Electric Discharge Machining), when the blade pitch is narrow (small diameter + multiple blades), wire interference occurs between the front and rear cutting edges, and it is difficult to provide an inclination to the rake face, which is undesirable as it limits groove formation.

[0036] The diameter contraction of the machined hole is thought to depend on the frictional heat and pressing force during cutting.

[0037] By providing grooves in the margin, coolant is supplied to the cutting edge and margin, and it is also easier to supply coolant closer to the machining point, which promotes chip removal.

[0038] In addition, the margin area is divided, the contact pressure is increased, and the burnishing action is more effective.

[0039] If the groove depth of the margin is less than 0.005 mm, the coolant does not easily enter the groove, and the coolant is not easily supplied to the gap between the margin surface and the inner surface of the machined hole. Also, if the groove depth exceeds 0.5 mm, the coolant and minute chips tend to enter the gap between the margin surface and the inner surface of the machined hole, which tends to cause a decrease in surface quality. For this reason, the groove depth is set to 0.005 mm or more and 0.5 mm or less. This allows the coolant to be efficiently supplied to the gap between the margin surface and the inner surface of the machined hole, improving the cooling effect of the workpiece and the effect of discharging minute chips. As a result, the shrinkage of the inner diameter of the machined hole is suppressed, and the surface roughness of the inner surface of the hole is improved, improving the roundness and cylindricity.

[0040] The width of the groove is preferably 0.03 mm or more and 0.15 mm or less. The groove is preferably formed by laser processing, and since the minimum diameter of the laser beam is 0.03 mm, the width of the groove is 0.03 mm or more. Also, the maximum feed amount of one blade is 0.15 mm, so the width is set to 0.15 mm or less to prevent a decrease in the burnishing effect. This improves the roundness and cylindricity of the processed hole.

[0041] By slanting the tip of the groove close to the ridge of the peripheral cutting edge and away from the ridge toward the rear end, the coolant supplied near the cutting edge is easily discharged by rotation and feed, and even tiny chips are less likely to accumulate. Also, since there is no groove in the margin immediately after the ridge of the peripheral cutting edge, the margin comes into stable contact with the inner surface of the drilled hole, preventing roughness of the inner surface of the drilled hole.

[0042] The groove pitch may be less than the feed rate per tool revolution. If the pitch is greater than the feed rate, the number of grooves will be small, making it difficult for coolant to be supplied to the entire gap between the margin surface and the inner surface of the machined hole, which may reduce the cooling effect. This may lead to a deterioration in the surface roughness of the inner surface of the machined hole and a decrease in roundness and cylindricity, so the groove pitch may be less than the feed rate per tool revolution. Note that "may" means that there is a slight possibility that this will happen, and does not mean that there is a high probability that this will happen.

[0043] The cross-sectional shape of the groove is made trapezoidal or circular so that coolant can easily enter and exit even in very small grooves. This shape helps prevent hole diameter shrinkage and improves the surface roughness of the hole inner surface.

[0044] In Patent Document 1, a margin is provided along the peripheral cutting edge, and the margin is provided with unevenness along the extension direction of the peripheral cutting edge. In the example described in Patent Document 1, the concave and convex parts of this unevenness are formed to be parallel to the circumferential direction (rotation direction). This unevenness prevents clogging during machining and allows the surface roughness of the inner surface of the hole to be machined to be moderate.

[0045] In contrast, the present disclosure has the effect of reducing the surface roughness of the inner surface of the hole to be machined to produce a high-precision surface, while preventing burns and other problems from occurring on the inner surface of the hole, and therefore differs from Patent Document 1. [Brief description of the drawings]

[0046] [Figure 1] FIG. 1 is a perspective view of a rotary cutting tool 1 according to a first embodiment. [Diagram 2] FIG. 2 is a side view of the rotary cutting tool 1 according to the first embodiment. [Diagram 3] FIG. 3 is an enlarged view of the part enclosed by III in FIG. [Figure 4]FIG. 4 is a perspective view of the tip 10 attached to the rotary cutting tool 1 of the first embodiment. [Diagram 5] FIG. 5 is a side view of tip 10 attached to rotary cutting tool 1 of the first embodiment. [Figure 6] FIG. 6 is a cross-sectional view of the margin 120 and the groove 130 taken along line VI-VI in FIG. [Figure 7] FIG. 7 is a perspective view of a tip 10 attached to the rotary cutting tool 1 of the second embodiment. [Figure 8] FIG. 8 is a side view of a tip 10 attached to a rotary cutting tool 1 according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0047] [Description of the embodiments of the present disclosure] First, the embodiments of the present disclosure will be listed and described.

[0048] (Embodiment 1) Fig. 1 is a perspective view of a rotary cutting tool 1 according to a first embodiment. As shown in Fig. 1, the rotary cutting tool 1 has a base metal 2. A flute 3 is provided so as to extend along the longitudinal direction of the base metal 2. The base metal 2 is made of, for example, a cemented carbide alloy.

[0049] A tip 10 is provided at the tip of the flute 3. The tip 10 is made of polycrystalline diamond. The tip 10 may also be made of single crystal diamond or cubic boron nitride.

[0050] A coolant outlet hole 4 for supplying coolant to the tip 10 is provided in the base metal 2. The coolant is supplied from the coolant outlet hole 4 during cutting, and the coolant is supplied to the tip 10 that comes into contact with the workpiece. This reduces the cutting resistance.

[0051] Four tips 10 are provided at the tip of the base metal 2. The number of tips 10 may be more or less than four.

[0052] Fig. 2 is a side view of the rotary cutting tool 1 according to the embodiment 1. As shown in Fig. 2, a base metal 2 extends in the longitudinal direction. A coolant trunk hole 5 is provided in the base metal 2 so as to extend in the longitudinal direction. The tip of the coolant trunk hole 5 branches out and is connected to the coolant discharge hole 4.

[0053] Fig. 3 is an enlarged view of a portion surrounded by III in Fig. 2. Fig. 4 is a perspective view of a tip 10 attached to the rotary cutting tool 1 of the embodiment 1. As shown in Figs. 3 and 4, the tip 10 is provided with a rake face 140.

[0054] The rake face 140 is surrounded by the peripheral cutting edge 110, the oblique cutting edge 111, and the leading cutting edge 112. In this embodiment, the peripheral cutting edge 110, the oblique cutting edge 111, and the leading cutting edge 112 are linear. However, at least one of the peripheral cutting edge 110, the oblique cutting edge 111, and the leading cutting edge 112 may be curved. The oblique cutting edge 111 does not have to be provided.

[0055] A margin 120 is provided on the rear side of the peripheral cutting edge 110 in the rotational direction. A peripheral flank surface 150 is provided on the rear side of the margin 120 in the rotational direction. The margin 120 is a portion that comes into contact with the workpiece during rotary cutting, and the peripheral flank surface 150 is a portion that does not come into contact with the workpiece during rotary cutting. The margin 120 has a curved shape. The margin 120 exerts a burnishing effect by coming into contact with the workpiece.

[0056] A plurality of grooves 130 are provided in the margin 120. The plurality of grooves 130 are provided at intervals from one another and so as not to reach the peripheral cutting edge 110. The grooves 130 are parallel to the longitudinal direction (feed direction) indicated by the arrow 20 or at an angle to the direction indicated by the arrow 20. This allows the coolant to easily flow through the grooves 130. As a result, clogging of the grooves 130 with cutting chips, or so-called clogging, can be prevented.

[0057] The tip 10 is provided with an oblique cutting edge 111 and an oblique cutting edge flank 151 that is continuous therewith. The tip 10 is provided with a leading cutting edge 112 and an leading cutting edge flank 152 that is continuous therewith.

[0058] Fig. 5 is a side view of the tip 10 attached to the rotary cutting tool 1 of the first embodiment. Fig. 6 is a cross-sectional view of the margin 120 and the groove 130 taken along the line VI-VI in Fig. 5. As shown in Figs. 5 and 6, the cross section of the groove 130 is semicircular. The cross section of the groove 130 may be rectangular. The cross section of the groove 130 may be trapezoidal.

[0059] The depth D of the groove 130 is 0.005 mm or more and 0.5 mm or less. If the depth of the groove 130 is less than 0.005 mm, it is difficult for the coolant to enter the groove 130. As a result, it is difficult for the coolant to be supplied to the gap between the surface of the margin 120 and the inner surface of the machined hole.

[0060] If the depth D of the groove 130 exceeds 0.5 mm, minute chips, together with the coolant, tend to enter the gap between the surface of the margin 120 and the inner surface of the machined hole via the groove 130. As a result, the surface quality tends to deteriorate.

[0061] The depth and width of the groove 130 are measured by a digital microscope or a non-contact three-dimensional measuring machine. The depth of the groove 130 is the depth at the deepest part of the groove 130. The width W of the groove 130 is not limited. The width W of the groove 130 is preferably 0.03 mm or more and 0.15 mm or less. The width W of the groove 130 is measured at the part of the groove 130 closest to the peripheral cutting edge 110 along a direction perpendicular to the extension direction of the groove 130. The pitch P of the groove 130 is preferably equal to or less than the feed amount per rotation of the rotary cutting tool 1. The pitch of the groove 130 is measured based on the part of each groove 130 closest to the front cutting edge 112.

[0062] (Embodiment 2) 7 is a perspective view of the tip 10 attached to the rotary cutting tool 1 of the embodiment 2. In the tip 10 according to the embodiment 2, the distances from the peripheral cutting edge 110 are different among the multiple grooves 130. The distance L1 from one groove 130a to the peripheral cutting edge 110 is shorter than the distance L2 from another groove 130b located on the rear end side to the other peripheral cutting edge 110.

[0063] That is, in the second embodiment, the groove 130 on the leading cutting edge 112 side is arranged close to the peripheral cutting edge 110. This allows a large amount of coolant to be supplied to the leading cutting edge 112 side where the cutting conditions are severe. On the other hand, on the trailing end side, the burnishing effect in the margin 120 can be improved by increasing the distance between the groove 130 and the peripheral cutting edge 110.

[0064] (Embodiment 3) Fig. 8 is a side view of tip 10 attached to rotary cutting tool 1 of embodiment 3. Tip 10 according to embodiment 3 differs from the tip of embodiment 1 in that the multiple grooves 130 are inclined in the opposite direction to that in Fig. 5.

[0065] [Details of the embodiment of the present disclosure] (Example) An experiment was conducted using a φ12-4NT (margin width 0.2) x single-stage reamer (blade diameter 12 mm, 4-blade single-stage reamer) to machine a pilot hole of φ11 mm and depth 30 mm in aluminum alloy (ADC12) to a hole diameter of 12 mm.

[0066] (Pre-hole creation) A pilot hole with an inner diameter of 11 mm and a depth of 30 mm was formed in an aluminum alloy. The conditions for forming the pilot hole were: cutting speed V of 100 m / min, rotation speed S of 2895 / min, feed f of 0.25 mm / rev, and feed F of 724 mm / rev.

[0067] (Reamer manufacturing) A variety of reamers were manufactured, as shown in Table 1.

[0068] [Table 1]

[0069] In the column of "Whether groove penetrates cutting face" in Table 1, "no groove" means that groove 130 as shown in Figures 3 to 7 is not provided. "Groove penetrates" means that groove 130 as shown in Figures 3 to 8 is provided, but groove 130 reaches peripheral cutting edge 110, so groove 130 penetrates cutting face 140. "Groove non-penetrating" means that groove 130 is provided as shown in Figures 3 to 8 and does not penetrate cutting face 140. In the column of "Groove angle", a positive angle means the inclination in Figure 5, and a negative angle means the inclination in Figure 8.

[0070] In all samples, the four tips 10 are made of polycrystalline diamond. The average grain size of the polycrystalline diamond is 8 (6 to 10) μm. The dimensions of the four tips 10 are: the length of the peripheral cutting edge 110 is 5 mm, the length of the oblique cutting edge 111 is 1.41 mm, the length of the front cutting edge 112 is 2 mm, and the length of the margin in the rotational direction is 0.2 mm.

[0071] To measure the average grain size of diamond particles, a polycrystalline diamond is photographed at three random locations within an area of ​​5 μm x 5 μm using a scanning electron microscope. From the photographed image, individual diamond grains are extracted, and the extracted diamond grains are binarized to calculate the area of ​​each diamond grain. Then, a circle with the same area as each diamond grain is assumed, and the diameter of this circle is taken as the grain size of the diamond grain. The arithmetic mean value of each diamond grain diameter (diameter of the circle) is taken as the average grain size.

[0072] Using these reamers, a through hole with a diameter of 11 mm was machined to a diameter of 12 mm. Specifically, the pilot hole diameter (φ) was 11 mm, the cutting edge diameter (φ) was 12 mm, the cutting speed V was 200 m / min, the spindle speed S was 5308 ( / min), the feed f was 0.4 (mm / rev), the feed speed F was 2123 (mm / min), the feed per tooth fz was 0.10 (mm / tooth), and the coolant was JISW Class 1 8% diluted solution.

[0073] The circularity, cylindricity, surface roughness, inner diameter and radial cutting force of the holes after machining were measured, and the results are shown in Table 2.

[0074] [Table 2]

[0075] The roundness and cylindricity of the hole were measured using a roundness and cylindricity measuring instrument (such as Roncom 65A manufactured by Tokyo Seimitsu Co., Ltd.) in accordance with the specifications of JIS B0621 (1984). The measurement data was measured using the MZC minimum area center method.

[0076] The evaluation criteria are as follows: circularity: AA: less than 3 μm, A: 3 μm to less than 4 μm, B: 4 μm or more, with B being unacceptable. Cylindricity: AA: less than 4 μm, A: 4 μm to less than 6 μm, B: 6 μm or more, with B being unacceptable.

[0077] "Surface roughness Rz" is defined as the average value of the surface roughness from the hole entrance to a depth of 4 mm and the surface roughness from the hole exit to a depth of 4 mm, in accordance with JIS B 0601-2001. If the surface roughness Rz was 3.2 μmRz or less, it was considered a good product, and if it exceeded 3.2 μmRz, it was considered a defective product.

[0078] The "inner diameter" is the difference between the inner diameter and the blade diameter, i.e., the value of inner diameter - blade diameter. Regarding the pass / fail line for the inner diameter quality, if the "inner diameter" exceeds ±3 μm, it is a defective product, if the "inner diameter" is in the range of ±1 to 2 μm, it is a good product, and if the "inner diameter" is in the range of ±0 to 1 μm, it is the best product.

[0079] The cutting resistance in the radial direction was measured using a three-component dynamometer during hole drilling, and is expressed as an index of cutting resistance when the cutting resistance of the conventional product without grooves (sample number 101) is set to 100. For example, "98%" for sample number 102 indicates that the value of the cutting resistance of sample number 102 / the cutting resistance of sample number 101 is 98%.

[0080] In the case of sample number 101 without grooves, the coolant is not easily supplied to the machining surface. As a result, the inner diameter shrinks due to the processing heat, and the resistance due to the shrinkage increases.

[0081] In sample number 102, the surface roughness is controlled by the feed setting value and the groove pitch. The groove penetrates to the ridge where the rake face and the outer margin meet, and the chips may get into the unevenness formed on the ridge due to the penetration, resulting in a decrease in quality. The roundness, surface roughness, and inner diameter of the tool with this specification deteriorate.

[0082] In sample No. 1, the change in inner diameter and resistance were suppressed, and the surface roughness and roundness / cylindricity were improved due to the cooling and cleaning effects of the processing point.

[0083] Sample No. 2 exhibits similar performance to Sample No. 1.

[0084] Sample No. 3 has a smaller effect of reducing resistance than sample No. 1.

[0085] Sample number 4 is similar to sample number 1.

[0086] Sample No. 103 showed the same trend as sample No. 101.

[0087] For sample No. 104, when the groove depth was increased, the grooves extended beyond the PCD layer into the carbide substrate, causing chipping due to a decrease in chip strength, resulting in a worsening of surface roughness.

[0088] In sample numbers 11 and 12, the surface roughness is slightly worse than in sample numbers 1 and 2, and furthermore, the drag reduction effect is smaller.

[0089] In sample No. 13, the burnishing effect was weaker than in samples Nos. 1 and 2, and the surface roughness was slightly worse.

[0090] In sample No. 14, the groove width was made larger than in sample Nos. 1 to 4, so the burnishing effect was reduced, the difference in inner diameter was increased, and the quality was reduced. Furthermore, resistance variations occurred.

[0091] Sample No. 21 was similar to sample No. 2, but the groove direction was reversed, which resulted in a worsening of the surface roughness and a worsening of the resistance value.

[0092] Sample number 31 gave similar results to sample number 2.

[0093] In sample numbers 32 to 34, the pitch was greater than or equal to the feed amount per rotation of the tool, resulting in a low cooling effect, a weakened function of suppressing inner diameter shrinkage, and a slight deterioration in surface roughness.

[0094] Sample No. 41 gave similar results to sample No. 1.

[0095] In sample number 42, the groove shape was rectangular, which made it difficult for the coolant to flow in and out, resulting in a slight deterioration in surface roughness.

[0096] (Appendix 1) A base metal and a tip provided on an outer periphery of the base metal, A peripheral cutting edge is provided at the boundary between the rake face and the peripheral flank of the tip, A margin is provided on the rear side of the outer peripheral cutting edge in the rotation direction, A groove having a depth of 0.005 mm or more and 0.5 mm or less is provided in the margin, The groove is provided parallel to or at an angle to the peripheral cutting edge, A rotary cutting tool in which the tool tip side of the groove is provided rearward in the direction of rotation from the ridge line of the outer peripheral cutting edge.

[0097] (Appendix 2) 2. The rotary cutting tool according to claim 1, wherein the groove has a width of 0.03 mm to 0.15 mm.

[0098] (Appendix 3) A rotary cutting tool as described in Appendix 1 or 2, wherein the portion of the groove at the tip end of the tool is closest to the ridge of the peripheral cutting edge and is arranged so as to move away from the ridge of the peripheral cutting edge toward the rear end of the tool.

[0099] (Appendix 4) 4. The rotary cutting tool of claim 1, wherein the pitch of the grooves is at least equal to or less than the feed rate per revolution of the tool.

[0100] (Appendix 5) 5. The rotary cutting tool of claim 1, wherein the cross-sectional shape of the groove is trapezoidal or circular.

[0101] The embodiments and examples disclosed herein are illustrative in all respects and should not be considered as limiting. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0102] 1 rotating cutting tool, 2 base metal, 3 flute, 4 coolant outlet hole, 5 coolant trunk hole, 10 tip, 20 arrow, 110 peripheral cutting edge, 111 oblique cutting edge (corner edge), 112 front cutting edge (bottom edge), 120 margin, 130, 130a, 130b groove, 140 rake face, 150 peripheral flank face, 151 oblique cutting edge flank face, 152 front cutting edge flank face.

Claims

1. A base metal and a tip provided on an outer periphery of the base metal, A peripheral cutting edge is provided at the boundary between the rake face and the peripheral flank of the tip, A margin is provided on the rear side of the outer peripheral cutting edge in the rotation direction, A plurality of grooves having a depth of 0.005 mm or more and 0.5 mm or less are provided in the margin, The plurality of grooves are provided at an angle to the peripheral cutting edge, The tool tip side of the plurality of grooves is provided rearward in the rotation direction from the ridge line of the outer peripheral cutting edge, The width of the grooves is between 0.03 mm and 0.15 mm; A rotary cutting tool, wherein the cutting face is surrounded by the peripheral cutting edge, the oblique cutting edge and the front cutting edge, and the peripheral cutting edge has a straight shape.

2. The rotary cutting tool according to claim 1 , wherein the portions of the plurality of grooves at the tip end of the tool are closest to the ridgeline of the outer cutting edge, and are arranged so as to move away from the ridgeline of the outer cutting edge toward the rear end of the tool.

3. 3. The rotary cutting tool according to claim 1, wherein the pitch of the plurality of grooves is at least equal to or less than the feed amount per revolution of the tool.

4. The rotary cutting tool according to claim 1 or 2, wherein a cross-sectional shape of the plurality of grooves is trapezoidal or circular.

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