JP2018183854A - Rotary Cutting Tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high performance rotary cutting tool.SOLUTION: A reamer 90 comprises a first cutting edge group 10 arranged in a first position in the axial direction and a second cutting edge group 20 arranged in a second position on the root side in the axial direction relative to the first position. The first cutting edge group 10 comprises five or more first cutting edges arranged with a first rotation diameter D1, and the second cutting edge group 20 comprises four or more second cutting edges arranged with a second rotation diameter D2 larger than the first rotation diameter D1. The first cutting edge and the second cutting edge have linear shapes and are parallel to a rotary shaft, and are made of a super-rigid material. The five or more first cutting edges of the first cutting edge group 10 are arranged in the circumferential direction in a first arrangement pattern, and the four or more second cutting edges of the second cutting edge group 20 are arranged in the circumferential direction in a second arrangement pattern different from the first arrangement patten. Two or more kinds of angle exist between the first cutting edges neighboring in the first arrangement pattern, and two or more kinds of angle exist between the second cutting edges neighboring in the second arrangement pattern.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a rotary cutting tool.

  Conventionally, rotary cutting tools are disclosed in, for example, Patent Document 1 (Japanese Patent Laid-Open No. 2011-62790), Patent Document 2 (Japanese Patent Laid-Open No. 2001-113413), and Patent Document 3 (Japanese Utility Model Laid-Open No. 6-31919). ing.

JP 2011-62790 A JP 2001-113413 A Japanese Utility Model Publication No. 6-31919

  In conventional rotary cutting tools, the requirements for roundness and cylindricity have become strict, and it has been difficult to satisfy the required values.

  Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a rotary cutting tool that can satisfy the required values of roundness and cylindricity.

  A rotary cutting tool according to the present invention includes a first cutting edge group disposed at a first position in the axial direction, and a second cutting position disposed at a second position on the axial base side relative to the first position. A blade group. The first blade group has five or more first blades arranged at the first rotation diameter, and the second cutting blade group is arranged at the second rotation diameter larger than the first rotation diameter. It has four or more second cutting edges. The first and second blades are linear and parallel to the rotation axis, and are made of a super hard material. Five or more first blades in the first blade group are arranged circumferentially in a first arrangement pattern, and four or more second cutting blades in the second cutting blade group are different from the first arrangement pattern. There are two or more angles between the adjacent first blades in the first array pattern, arranged in the circumferential direction in the second array pattern, and the angle between the adjacent second cutting blades in the second array pattern There are two or more types.

1 is a front view of a reamer according to a first embodiment. It is sectional drawing along the II-II line | wire in FIG. It is sectional drawing along the III-III line in FIG. It is sectional drawing of the workpiece | work in which the pilot hole was formed. It is a figure which shows arrangement | positioning of the 1st blade which comprises the 1st blade group in the reamer of Example 1. FIG. It is a figure which shows arrangement | positioning of the 2nd cutting blade which comprises the 2nd cutting blade group in the reamer of Example 1. FIG. It is sectional drawing of the workpiece | work processed with the reamer. It is a figure which shows arrangement | positioning of the 1st blade which comprises the 1st blade group in the reamer of Example 2. FIG. It is a figure which shows arrangement | positioning of the 2nd cutting blade which comprises the 2nd cutting blade group in the reamer of Example 2. FIG. It is a figure which shows arrangement | positioning of the 1st blade which comprises the 1st blade group in the reamer of the comparative example 1. FIG. It is a figure which shows arrangement | positioning of the 2nd cutting blade which comprises the 2nd cutting blade group in the reamer of the comparative example 1. FIG. It is a figure which shows arrangement | positioning of the 1st blade which comprises the 1st blade group in the reamer of the comparative example 2. FIG. It is a figure which shows arrangement | positioning of the 2nd cutting blade which comprises the 2nd cutting blade group in the reamer of the comparative example 2. FIG.

[Description of Embodiment of the Present Invention]
(1) Configuration The rotary cutting tool includes a first cutting blade group disposed at a first position in the axial direction and a second cutting blade disposed at a second position on the axial base side relative to the first position. With a group. The first blade group has five or more first blades arranged at the first rotation diameter, and the second cutting blade group is arranged at the second rotation diameter larger than the first rotation diameter. It has four or more second cutting edges. The first and second blades are linear and parallel to the rotation axis, and are made of a super hard material. Five or more first blades in the first blade group are arranged circumferentially in a first arrangement pattern, and four or more second cutting blades in the second cutting blade group are different from the first arrangement pattern. There are two or more angles between the adjacent first blades in the first array pattern, arranged in the circumferential direction in the second array pattern, and the angle between the adjacent second cutting blades in the second array pattern There are two or more types.

  In the rotary cutting tool configured in this way, since the arrangement pattern of the first blade group and the second cutting blade group is different, the vibration generated in the first blade group and the vibration generated in the second cutting blade group Does not resonate. As a result, the required values for roundness and cylindricity can be satisfied.

  Preferably, the apparatus further includes a plurality of chips provided with a second cutting edge, and the plurality of chips includes a front cutting edge extending in a plane substantially perpendicular to the rotation axis and continuing to the second cutting edge. In this case, machining different from the second cutting edge can be performed on the front cutting edge.

  Preferably, the angle between adjacent front cutting edges is not less than 50 ° and not more than 95 °. When the front cutting edge comes into contact with the thrust surface of the workpiece, the front cutting blade receives an axial force from the thrust surface of the workpiece. When a plurality of front cutting edges of the second cutting edge group having a large diameter come into contact with the workpiece, if the angle between adjacent front cutting edges is 50 ° or more and 95 ° or less, the second cutting blade group is removed from the thrust surface. Can receive force almost evenly. As a result, roundness and cylindricity are not deteriorated. More preferably, the angle between adjacent front cutting edges is in the range of 85 ° to 95 °.

  Preferably, the angle between the adjacent first blades and the angle between the adjacent second cutting blades are not less than 50 ° and not more than 95 °. If the angle is less than 50 °, the angle between adjacent cutting edges may be reduced, and the resistance may be increased. If the angle exceeds 95 °, the angle becomes too large and the positioning accuracy of the rotary cutting tool may be lowered. Note that “probable” indicates that there is a slight possibility that this will occur, and it does not mean that it will occur with a high probability.

  Preferably, the angle between the adjacent first blades and the angle between the adjacent second cutting edges are not less than 60 ° and not more than 95 °.

  Preferably, the angle between a plurality of adjacent second cutting edges is not less than 85 ° and not more than 95 °. Since the angle between the second cutting edges on the base side is 85 ° or more and 95 ° or less, the variation in angle between the second cutting edges on the base side is reduced. As a result, the second cutting blade is held almost evenly by the workpiece, so that the rotation shaft can be prevented from shaking.

  Preferably, the first and second cutting edges are made of diamond. When the first cutting edge and the second cutting edge are composed of diamond, the performance particularly preferable for cutting a work other than the ferrous metal is exhibited.

  Preferably, the diamond is a kind selected from the group consisting of single crystal diamond, polycrystalline diamond, and binderless polycrystalline diamond.

(2) Actions and effects PCD (polycrystalline diamond) rotary cutting tools represented by tools for hole finishing, for example, key parts (cylinder head / block / steering / hydraulic control valve) made of aluminum alloy for automobiles and firing Used for hole finishing of sintered metal. High-precision machining can be performed even when the workpiece is provided with a keyway or the like for intermittent cutting or when the wall thickness is thin.

  Conventionally, the cutting tool diameter of a PCD rotary tool for hole finishing machining (rotating diameter of the cutting edge) is set by setting a tolerance range based on the manufacturing limit and required value, with the upper limit being a diameter that is several μm smaller than the upper limit value of the workpiece diameter tolerance. Things are common. This is because the workpiece shrinks after machining and the hole diameter changes.

  In addition, since the amount of shrinkage varies depending on the thickness of the workpiece and the processing diameter, it is customary to change the setting value of the blade diameter for each application.

  In particular, when the cutting is performed intermittently with a keyway or the like, and when the workpiece is thin, the roundness is significantly poor.

  As countermeasures, (1) change elements other than the cutting tool, such as pilot hole diameter and machining conditions, and (2) reduce cutting resistance to prevent the cutting edge from biting into the workpiece and preventing deterioration of geometric accuracy. (3) In the case of four blades, the angle between two opposing blades is 180 °, and the spacing between adjacent blades is set to be unequal (pseudo unequal distribution), etc. This is supported by the device design.

  Recent workpiece shapes have become complex shapes due to higher functionality, and the thickness may be thin due to weight reduction. The amount of elastic recovery is larger, and the above-mentioned pseudo uneven blade design cannot satisfy not only the inner diameter but also the geometric accuracy such as roundness and cylindricity. One blade may be selected as one means of blade design that suppresses hole diameter change due to elastic recovery.

  In this case, although the change in the hole diameter can be suppressed, since the number of cutting edges is one, the feed rate of the tool cannot be increased and the speed cannot be increased. The feed speed f is 0.08 to 0.15 mm / rev.

  In addition, since the parts other than the cutting edge have a carbide guide pad structure, welding of aluminum or the like is likely to occur at the tip of the guide pad, resulting in problems such as a large hole diameter after machining and a clouded machining surface. Cheap.

  As another means, it is conceivable to increase the number of blades. However, as the number of blades increases, there is a size restriction and the cost increases.

  Under such circumstances, a tool with five blades and uneven cutting edge spacing is reasonable, but if the workpiece shape is a multi-stage hole and the tool feed rate is high, self-excited vibration (battery of the tool itself) ) (See below (A) (B)) remained as a problem.

(A) A chatter mark or cloudiness on the processed surface is caused.
(B) Since the thickness of the workpiece is thin or the hole in which the key groove is formed is easily contracted in the radial direction and the roundness is likely to be lost, there are many restrictions on the measures for tools for processing these workpieces.

  In particular, when the machining depth is extremely shallow at only 3 mm or less, the geometric accuracy such as roundness and cylindricity may not be satisfied due to vibration.

  The inventor has a first cutting blade group in which the rotary cutting tool is disposed at the first position in the axial direction, and a second cutting position in which the rotary cutting tool is disposed at the second position on the axial base side relative to the first position. A blade group, the first blade group has five or more first blades arranged at a first rotational diameter, and the second cutting blade group is a second larger than the first rotational diameter. It has four or more second cutting edges arranged at a rotating diameter, the first cutting edge and the second cutting edge are linear and parallel to the rotation axis, and are made of a super-hard material. Five or more first blades in the cutting blade group are arranged in a circumferential direction in a first arrangement pattern, and four or more second cutting blades in the second cutting blade group are different from the first arrangement pattern. There are two or more angles between the first blades adjacent in the first array pattern, and the second cutting blades adjacent in the second array pattern. Angle by adopting a configuration in which there are two or more types, and can solve the above problems.

  That is, the first-stage leading blade is 5 blades or more, and the second-stage cutting blade is 4 blades or more. There are two or more types of angles between the first adjacent blades in the first arrangement pattern, and there are two or more types of angles between the second second cutting blades adjacent in the second arrangement pattern. Is unequal.

  Moreover, since the four or more second cutting blades in the second cutting blade group are arranged in the circumferential direction in a second arrangement pattern different from the first arrangement pattern, the second cutting edge of the second cutting blade group Of these, the position of at least one or more cutting blades in the circumferential direction is shifted from the position of the first blade group in the circumferential direction of the first blade.

  Suppresses the shrinkage of the hole diameter of the workpiece after machining and improves the accuracy of roundness and cylindricity. Compared to the conventional multi-blade design, the tool cost can be reduced, and the size is limited and the tool can be applied in a wide range.

  Since the first blade group has five or more first blades as the leading blade, it is considered that high-efficiency machining can be performed by increasing the feed rate of the tool.

  Since the cutting edge intervals are unevenly distributed, it is considered that the occurrence of vibrations can be suppressed when contacting the workpiece, thereby improving the roundness. In addition, when the cutting edge of the first cutting edge group advances and the cutting edge of the second cutting edge group starts processing the workpiece, the position of the cutting edge is shifted in the circumferential direction. Since it is hard to receive the vibration at the time of cutting in a processing hole at the same position, and chatter is not easily generated, the processing hole diameter is stabilized, and roundness and cylindricity can be improved.

  Regarding welding reduction, since the number of cutting edges is large, it is possible to suppress the occurrence of vibration without providing a large guide pad, so that chip welding is less likely to occur, and the surface roughness of the workpiece processing surface is improved. It is considered that the chips are also reduced and the discharge property is improved.

(3) Difference from the prior art In the tool of Patent Document 1 (Japanese Patent Application Laid-Open No. 2011-62790), the cutting blade position of each step is the same, and the arrangement pattern of cutting blades is arranged differently in each step. Is not disclosed. There are portions where the front end side arrangement pattern and the rear end side arrangement pattern are the same. The arrangement patterns in FIGS. 3, 6 and 8 are the same. However, in the arrangement pattern of FIGS. 3, 6 and 8, only two cutting edges are provided, not a multi-blade arrangement pattern. Like the above-described single blade, the two-blade cannot cope with high-speed feeding and does not sufficiently affect the processing in high-speed feeding. All of the five-blade arrangement patterns in FIGS. 2, 4, 5, and 7 are the same arrangement pattern. Therefore, vibrations with the same period are generated on the front end side and the rear end side of the reamer. Since this vibration vibrates the rotation axis of the reamer, the cylindricity and roundness do not satisfy the required values.

  Patent Document 2 (Japanese Patent Laid-Open No. 2001-113413) discloses a tool whose finishing blade is a single blade, but does not disclose a first and second cutting blade group having a plurality of cutting blades. There is a problem that it is not possible to cope with the above-mentioned high-speed feeding because it is a single blade.

  In Patent Document 3 (Japanese Utility Model Laid-Open No. 6-31919), a plurality of roughing blades are provided at the front end, a plurality of finishing blades are provided near the rear end, and the finishing blades are unequally divided into left-handed twisting blades. Since it is a left-handed blade, chips are discharged in the direction of the tip, making it ideal for finishing through-holes, but it is difficult to discharge chips when machining stepped holes or blind holes. Become. Furthermore, since it is a continuous left twist blade, the direction in which the chips actually flow is opposite to the direction in which the chips try to flow during cutting (the right twist direction). For this reason, the resistance of the chips increases in the torsion groove, and vibrations are likely to occur, and chips enter between the workpiece and the reamer. This deteriorates the cylindricity and surface roughness and impairs the processing quality. In addition, a twisted blade made of ultra-hard material such as diamond cannot be easily manufactured.

  In the twisted blade, the blade angle (angle formed by the rake face and the flank face) is reduced in order to reduce the cutting resistance. For this reason, the strength of the blade edge becomes weak and is easily chipped, and the surface roughness of the processed hole is deteriorated. In addition, since the core thickness (outer diameter−groove depth = core thickness) becomes small and the strength becomes weak in the twisted blade, vibration is likely to occur, and the roundness and cylindricity deteriorate as the core thickness decreases. On the other hand, if the blade angle is increased, the core thickness can be increased and the strength can be increased, but the cutting resistance increases. As a result, high speed cutting becomes difficult.

(4) Specific Example FIG. 1 is a front view of a reamer according to the embodiment. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 3 is a cross-sectional view taken along line III-III in FIG.

  As shown in FIGS. 1 to 3, a reamer 90 as a rotary cutting tool according to the embodiment includes a base metal 80, a first blade group 10 provided at the tip of the base metal 80, and a first And a second cutting blade group 20 provided on the root side in the direction of the rotation axis 82 with respect to the blade group 10. The first blade group 10 is composed of five first blades 11-15. The second cutting blade group 20 is composed of four second cutting blades 21-24. The rotary cutting tool may be a drill. The direction of rotation is indicated by arrow 70.

  The base metal 80 is made of a cemented carbide. The first cutting edge 11-15 and the second cutting edge 21-24 are one side of the first tip 19 and the second tip 29 made of a super hard material. The first blade 11-15 and the second cutting blade 21-24 are discontinuously arranged with a distance from each other. The first chip 19 and the second chip 29 are made of diamond or cubic boron nitride (CBN). Diamond may be either polycrystalline or single crystal.

  Both the first blade 11-15 and the second cutting blade 21-24 are linear. The first blades 11-15 and the second cutting blades 21-24 are arranged in parallel to the rotation shaft 82. The base metal 80 is provided with a hole 81 so that the lubricant can be supplied in the vicinity of the first blade 11-15 and the second cutting blade 21-24.

  In the first blade 11-15 constituting the first blade group 10, the angle between the cutting blades is 60 ° or 90 ° as shown in FIG.

  In the 2nd cutting blade 21-24 which comprises the 2nd cutting blade group 20, the angle between each cutting blade is 85 degrees or 95 degrees, as shown in FIG.

  The first rotation diameter of the first blade group 10 is D1. The second rotation diameter of the second cutting blade group 20 is D2. The distance along the rotation axis 82 between the first blade group 10 and the second blade group 20 is L.

  Each first tip 19 is provided with a first front cutting edge. In FIG. 1, only the first front cutting edges 111 and 141 are shown. Each second tip 29 is provided with a second front cutting edge. In FIG. 1, only the second front cutting edges 211 and 231 are shown. The front cutting edge is used to cut a thrust surface of a workpiece (a surface positioned substantially perpendicular to the rotation axis). The first front cutting edge and the second front cutting edge extend in a plane located substantially perpendicular to the rotation axis.

  The front cutting edge contacts the thrust surface of the workpiece and receives an axial force from the workpiece. When the plurality of front cutting edges of the large-diameter second cutting blade group 20 come into contact with the workpiece, it is preferable that the plurality of front cutting blades contact the workpiece evenly. However, when the front cutting edges are arranged on the circumference at equal angles (for example, when four chips are located on the circumference at intervals of 90 °), the problem of resonance of the reamer 90 occurs. Therefore, the angle between adjacent chips is preferably 50 ° or more and 95 ° or less, and most preferably in the range of 85 ° or more and 95 ° or less.

  The plurality of second tips 29 includes a second front cutting edge extending in a plane substantially perpendicular to the rotation shaft 82 and continuing to the second cutting edge. The angle between adjacent second front cutting edges is the same as the angle between adjacent second cutting edges.

  The reamer 90 includes a base metal 80 and a first chip 19 and a second chip 29 provided on the outer peripheral surface of the base metal 80. The reamer 90 rotates around a predetermined rotation shaft 82. The reamer 90 has an asymmetrical outer peripheral surface, and a second tip 29 near the rear end in the axial direction of the base metal 80 and the astigmatic shape of the portion where the first chip 19 at the tip of the base metal 80 is provided. The astigmatic shapes of the portions thus formed are different shapes. The first tip 19 at the front end of the base metal 80 and the second tip 29 near the rear end in the axial direction of the base metal 80 have different rotation diameters, and the first tip 19 at the front end of the base 80 is 5 or more. At the same time, the number of second chips 29 near the rear end in the axial direction of the base metal 80 is four or more. The reamer 90 is a multistage rotary cutting tool capable of machining a plurality of holes having different inner diameters.

  The positions of the first chip 19 and the second chip 29 are arranged at unequal intervals on the same circumference. The numbers of the first chip 19 and the second chip 29 are different.

  Two first tips 19 of the first tips 19 are provided at positions facing each other with the rotary shaft 82 of the tool interposed therebetween. That is, the interval between the two first chips 19 is 180 °, and another first chip 19 is provided between the two first chips 19.

  The number of the first tips 19 is an odd number, and the tips provided between the two first tips 19 provided at positions facing each other across the rotation shaft 82 of the tool are equally spaced between the two first tips 19. Is provided.

  The number of the second chips 29 is an even number, and of these, two second chips 29 are provided at positions facing each other with the rotation axis 82 of the tool interposed therebetween, and 2 provided at positions facing each other with the rotation axis 82 of the tool interposed therebetween. The second chips 29 provided between the two second chips 29 are provided at unequal intervals.

  Five or more first blades 11-15 in the first blade group 10 are arranged in the circumferential direction in a first arrangement pattern, and four or more second cutting blades 21-24 in the second cutting blade group are arranged in the circumferential direction. They are arranged in the circumferential direction with a second arrangement pattern different from the first arrangement pattern. There are two or more angles between adjacent first blades 11-15 in the first array pattern, and there are two or more angles between adjacent second cutting blades 21-24 in the second array pattern.

  Preferably, there are four or more angles between the adjacent first blades 11-15 and the adjacent second cutting blades 21-24. In this case, since there are four or more types of time from cutting the peripheral portion of the groove provided on the inner peripheral side with one cutting blade until cutting with the adjacent cutting blade, the reamer 90 has a specific cycle. Vibrating can be suppressed.

  An arrangement pattern means the arrangement angle (phase) of cutting edges on the circumference. If the number of cutting blades is different in the first blade group 10 and the second cutting blade group 20, or the arrangement angle of at least one cutting blade in the first blade group 10 and the second cutting blade group 20 is different, It can be said that the arrangement patterns of the cutting blades in the first blade group 10 and the second cutting blade group 20 are different.

[Details of the embodiment of the present invention]
Example 1
FIG. 4 is a cross-sectional view of a workpiece in which a pilot hole is formed. Pilot holes are formed in the guide portion 61, the sheet portion 63, and the intermediate portion 62 of the workpiece 60. The dimensions of each part are shown in FIG. A stem guide is press-fitted into the guide portion 61. A valve seat is press-fitted into the seat portion 63. The work 60 is made of a high silicon aluminum alloy (ADC12).

  FIG. 5 is a diagram illustrating the arrangement of the first blades constituting the first blade group in the reamer according to the first embodiment. FIG. 6 is a diagram illustrating an arrangement of second cutting blades constituting the second cutting blade group in the reamer according to the first embodiment. As shown in FIGS. 5 and 6, the first blade group 10 and the second blade group 20 according to the first embodiment are arranged in the same manner as the rotary cutting tool of the embodiment shown in FIGS. 1 to 3. . Table 1 shows the angle between the cutting edges.

  The first rotation diameter D1 of the reamer was 10 mm, the second rotation diameter D2 was 36 mm, and the distance L between the cutting edges was 54 mm.

  Using such a reamer, the workpiece shown in FIG. 4 was processed under the following conditions.

  FIG. 7 is a cross-sectional view of a workpiece machined with a reamer. As a result of cutting, a workpiece having the shape shown in FIG. 7 was obtained. Such processing was performed on eight holes having the shape shown in FIG.

  The roundness and cylindricity of the sheet part 63 and the guide part 61 were measured. Roundness and cylindricity were measured using a roundness and cylindricity measuring instrument according to the contents defined in JIS B0621 (1984). The measurement data is a numerical value measured by the MZC minimum region center method. The results are shown in Tables 3 and 4.

  From Tables 3 and 4, it can be said that both the sheet part 63 and the guide part 61 satisfy the required values (5 μm) of roundness and cylindricity.

(Example 2)
FIG. 8 is a diagram illustrating the arrangement of the first blades constituting the first blade group in the reamer according to the second embodiment. FIG. 9 is a diagram illustrating the arrangement of the second cutting blades constituting the second cutting blade group in the reamer of the second embodiment. Table 5 shows the angle between the cutting edges.

  The first rotation diameter D1 of the reamer was 10 mm, the second rotation diameter D2 was 36 mm, and the distance L between the cutting edges was 54 mm.

Using such a reamer, the workpiece shown in FIG.
As a result of cutting, a workpiece having the shape shown in FIG. 7 was obtained. Such processing was performed on eight holes having the shape shown in FIG.

  The roundness and cylindricity of the sheet part 63 and the guide part 61 were measured. The results are shown in Tables 6 and 7.

  From Tables 6 and 7, it can be said that any of the sheet portion 63 and the guide portion 61 satisfies the required values (5 μm) of roundness and cylindricity.

(Comparative Example 1)
FIG. 10 is a view showing the arrangement of the first blades constituting the first blade group in the reamer of Comparative Example 1. FIG. 11 is a diagram illustrating the arrangement of the second cutting blades constituting the second cutting blade group in the reamer of Comparative Example 1. Table 8 shows the angle between the cutting edges.

  The first rotation diameter D1 of the reamer was 10 mm, the second rotation diameter D2 was 36 mm, and the distance L between the cutting edges was 54 mm.

Using such a reamer, the workpiece shown in FIG.
As a result of cutting, a workpiece having the shape shown in FIG. 7 was obtained. Such processing was performed on eight holes having the shape shown in FIG.

  The roundness and cylindricity of the sheet part 63 and the guide part 61 were measured. The results are shown in Table 9 and Table 10.

  From Table 9 and Table 10, it was found that some of the sheet portion 63 and the guide portion 61 did not satisfy the required values (5 μm) of roundness and cylindricity.

(Comparative Example 2)
FIG. 12 is a view showing the arrangement of the first blades constituting the first blade group in the reamer of Comparative Example 2. FIG. 13 is a diagram illustrating the arrangement of the second cutting blades constituting the second cutting blade group in the reamer of Comparative Example 2. Table 11 shows the angle between the cutting edges.

  The first rotation diameter D1 of the reamer was 10 mm, the second rotation diameter D2 was 36 mm, and the distance L between the cutting edges was 54 mm.

Using such a reamer, the workpiece shown in FIG.
As a result of cutting, a workpiece having the shape shown in FIG. 7 was obtained. Such processing was performed on eight holes having the shape shown in FIG.

  The roundness and cylindricity of the sheet part 63 and the guide part 61 were measured. The results are shown in Table 12 and Table 13.

  From Tables 12 and 13, it was found that neither the sheet part 63 nor the guide part 61 satisfied the required values (5 μm) for roundness and cylindricity.

  The embodiments and examples disclosed herein are illustrative in all respects and should not be construed as being restrictive. The scope of the present invention is shown not by the embodiments and examples described above but by the scope of claims, and is intended to include meanings equivalent to the scope of claims and all modifications within the scope.

  10 First blade group, 11-15 First blade, 19 First tip, 20 Second cutting blade group, 21-25 Second cutting blade, 29 Second tip, 60 Workpiece, 61 Guide portion, 63 Sheet portion 80 base metal, 81 holes, 82 rotating shaft, 90 reamer, 111, 141 first front cutting edge, 211, 231 second front cutting edge.

Claims (8)

A first blade group disposed at a first position in the axial direction, and a second cutting blade group disposed at a second position closer to the axial base than the first position,
The first blade group has five or more first blades arranged at a first rotation diameter, and the second cutting blade group has a second rotation diameter larger than the first rotation diameter. Having four or more second cutting edges arranged;
The first blade and the second cutting blade are linear and parallel to the rotation axis, and are made of a super-hard material,
The five or more first blades in the first blade group are arranged in a circumferential direction in a first arrangement pattern, and the four or more second blades in the second cutting blade group are arranged in the first direction. Are arranged in the circumferential direction with a second arrangement pattern different from the arrangement pattern of
There are two or more angles between the first blades adjacent in the first arrangement pattern,
A rotary cutting tool in which there are two or more types of angles between the second cutting edges adjacent in the second arrangement pattern.   The plurality of tips further provided with the second cutting edge, wherein the plurality of tips include a front cutting edge extending in a plane substantially perpendicular to the rotation axis and continuing to the second cutting edge. The rotary cutting tool according to 1.   The rotary cutting tool according to claim 2, wherein an angle between the adjacent front cutting edges is 50 ° or more and 95 ° or less.   The rotary cutting tool according to claim 3, wherein an angle between adjacent front cutting edges is not less than 85 ° and not more than 95 °.   5. The rotary cutting tool according to claim 1, wherein an angle between the adjacent first cutting edges and an angle between the adjacent second cutting edges are 50 ° or more and 95 ° or less.   The rotary cutting tool according to claim 5, wherein an angle between the adjacent first blades and an angle between the adjacent second cutting blades are 60 ° or more and 95 ° or less.   The rotary cutting tool according to any one of claims 1 to 6, wherein the first blade and the second cutting blade are made of diamond.   The rotary cutting tool according to claim 7, wherein the diamond is one type selected from the group consisting of single crystal diamond, polycrystalline diamond, and binderless polycrystalline diamond.

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