Cutting tools

Abstract

One aspect of this disclosure relates to a cutting tool comprising a shaft portion and two or more main cutting edges. The shaft portion extends along a central axis. The shaft portion has an outer peripheral surface. The outer peripheral surface surrounds the central axis. The two or more main cutting edges are arranged in a helical configuration on the outer peripheral surface. Each main cutting edge has a main cutting edge. The main cutting edge has a torsion angle. In the direction along the central axis, within ±30% of the cutting edge length of the region from the center of the region, the main cutting edge has at least one first slit portion and a second slit portion. The main cutting edge is formed in the region. The first slit portion and the second slit portion have torsion angles in opposite directions to the torsion angle. The relationship between the first slit portion and the second slit portion satisfies at least one of a first condition and a second condition. The first condition is that the width of the first slit portion is different from the width of the second slit portion. The second condition is that the depth of the first slit portion is different from the depth of the second slit portion.

Description

Technical Field

[0001] This disclosure relates to cutting tools. Background Technology

[0002] Cutting tools have long been known to have a rotatable body, a main cutting edge having a torsion angle on the outer periphery of the body, and slit-shaped cutting edges arranged at a reverse torsion angle relative to the torsion angle of the main cutting edge (for example, see Japanese Patent Application Publication No. 2011-20248).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2011-20248 Summary of the Invention

[0006] One aspect of this disclosure relates to a cutting tool comprising a shaft portion and at least two main cutting edges. The shaft portion extends along a central axis. The shaft portion has an outer peripheral surface. The outer peripheral surface surrounds the central axis. The two or more main cutting edges are arranged in a helical configuration on the outer peripheral surface. Each main cutting edge has a main cutting edge. The main cutting edge has a torsion angle. In the direction along the central axis, within ±30% of the cutting edge length of the region from the center of the region, the main cutting edge has at least one first slit portion and a second slit portion. The main cutting edge is formed in the region. The first slit portion and the second slit portion have torsion angles in opposite directions to the torsion angle. The relationship between the first slit portion and the second slit portion satisfies at least one of a first condition and a second condition. The first condition is that the width of the first slit portion is different from the width of the second slit portion. The second condition is that the depth of the first slit portion is different from the depth of the second slit portion. Attached Figure Description

[0007] Figure 1 This is a top view of the cutting tool according to the first embodiment.

[0008] Figure 2 yes Figure 1 A magnified top view of a portion of area II.

[0009] Figure 3 yes Figure 2 A cross-sectional view at line segment III-III.

[0010] Figure 4 yes Figure 2 A magnified cross-sectional view of region IV.

[0011] Figure 5 This is a partially enlarged top view showing a modified example 1 of the cutting tool according to the first embodiment.

[0012] Figure 6 yes Figure 5 A magnified cross-sectional view of a portion of region VI.

[0013] Figure 7 This is a partially enlarged top view showing a modified example 2 of the cutting tool according to the first embodiment.

[0014] Figure 8 yes Figure 7 A partially enlarged cross-sectional view of region VIII. Detailed Implementation

[0015] [The problem this disclosure aims to solve]

[0016] In existing cutting tools, by making the number of grooves on the kerf-shaped cutting edge different from the number of cutting edges on the main cutting edge, it is possible to suppress the vibration of the workpiece and obtain a workpiece with a good cutting surface. However, there are limits to the suppression of the vibration of the workpiece.

[0017] This disclosure was made to solve the problems mentioned above. More specifically, it provides a cutting tool capable of suppressing vibrations in the workpiece during cutting.

[0018] [The Effects of This Disclosure]

[0019] The cutting tool disclosed herein can suppress vibration of the workpiece during cutting.

[0020] [Summary of Implementation Methods]

[0021] The embodiments of this disclosure are first described by listing them.

[0022] (1) A cutting tool according to one aspect of this disclosure comprises a shaft portion and at least two main cutting edges. The shaft portion extends along a central axis. The shaft portion has an outer peripheral surface. The outer peripheral surface surrounds the central axis. The two or more main cutting edges are arranged in a helical configuration on the outer peripheral surface. The main cutting edges have main cutting edges. The main cutting edges have a twist angle. In the direction along the central axis, in a portion within ±30% of the cutting edge length of the region from the center of the region, the main cutting edges have at least one first slit portion and a second slit portion. The main cutting edges are formed in the region. The first slit portion and the second slit portion have twist angles in opposite directions to the twist angle. The relationship between the first slit portion and the second slit portion satisfies at least one of a first condition and a second condition. The first condition is that the width of the first slit portion is different from the width of the second slit portion. The second condition is that the depth of the first slit portion is different from the depth of the second slit portion.

[0023] (2) In the cutting tool described in (1) above, the first condition may be that the width of the first cut portion is more than twice and less than ten times the width of the second cut portion. The second condition may be that the depth of the first cut portion is more than twice and less than fifteen times the depth of the second cut portion.

[0024] (3) In the cutting tool described in (1) or (2) above, the cross-sectional area of ​​the first cut portion can be more than 5 times and less than 120 times the cross-sectional area of ​​the second cut portion.

[0025] (4) In any of the cutting tools described in (1) to (3) above, the number of main cutting edges may be greater than the number of first slits included in each of the main cutting edges.

[0026] (5) In any of the cutting tools described in (1) to (4) above, the torsion angle of the main cutting edge may be 30° or more and 50° or less. The torsion angles of the first cut and the second cut, which are in opposite directions to the torsion angle, may be 30° or more and 50° or less.

[0027] (6) In any of the cutting tools described in (1) to (5) above, the main cutting edge may include at least two or more first cutting portions. A second cutting portion may be positioned between the two first cutting portions.

[0028] (7) The cutting tool of any of (1) to (6) above may be coated with diamond.

[0029] [Details of the implementation method]

[0030] The embodiments of this disclosure will be described in detail with reference to the accompanying drawings. In the following drawings, the same or equivalent parts are labeled with the same reference numerals, and repeated descriptions are not used.

[0031] (First Implementation)

[0032] <Structure of Cutting Tool 1>

[0033] Figure 1 This is a top view of the cutting tool 1 involved in this embodiment. Figure 2 yes Figure 1 A magnified top view of a portion of area II. Figure 3 yes Figure 2 A cross-sectional view at line segment III-III. Figure 4 yes Figure 2 A magnified cross-sectional view of region IV.

[0034] like Figures 1 to 4As shown, one aspect of this disclosure relates to a cutting tool 1, for example, a tool for cutting FRP (Fiber Reinforced Plastic) materials such as carbon fiber reinforced plastic, which mainly comprises a shaft portion 30 and at least two main cutting edges 11. In this embodiment, the number of main cutting edges 11 is 5. The shaft portion 30 is generally cylindrical in shape. The shaft portion 30 extends along a central axis R. The shaft portion 30 has a front end face 2a, a rear end face 2b, and an outer peripheral face 2. The rear end face 2b is located on the side opposite to the front end face 2a. The outer peripheral face 2 is the face connecting the front end face 2a and the rear end face 2b. That is, the outer peripheral face 2 surrounds the central axis R. The shaft portion 30 is capable of rotating about the central axis R.

[0035] The shaft portion 30 also has a shank portion 20 and a cutting portion 10. The cutting portion 10 has a front end face 2a. The shank portion 20 has a rear end face 2b. That is, the cutting portion 10 is connected to the shank portion 20. Figure 1 In this design, if the direction in which the central axis R extends is defined as the first direction X, then the cutting length W of the cutting part 10 is the distance along the first direction X from the front end face 2a to the end of the main cutting edge 11 on the side of the rear end face 2b. The front end face 2a and the rear end face 2b are surfaces perpendicular to the central axis R. That is, the front end face 2a and the rear end face 2b are surfaces perpendicular to the outer peripheral surface 2. The cutting diameter is, for example, 10 mm. The cutting diameter can be, for example, 2 mm or more and 20 mm or less, or it can be 3 mm.

[0036] In the cutting section 10, five main cutting edges 11 are formed on the outer peripheral surface 2. The main cutting edges 11 are arranged in a spiral shape on the outer peripheral surface 2. Figure 3 As shown, the main cutting edge 11 has a main rake face 11b, a main flank face 11c, and a main cutting edge 11a. The main cutting edge 11a is disposed on the outer peripheral surface 2. The main rake face 11b is formed to extend from the main cutting edge 11a in a direction from the main cutting edge 11a toward the central axis R. When viewed from the main cutting edge 11a, the main flank face 11c is located on the side opposite to the main rake face 11b. The main rake face 11b is connected to the main flank face 11c via the main cutting edge 11a.

[0037] The main cutting edge 11a has a main twist angle θ1. For example... Figure 1 As shown, in the top view viewed from a direction perpendicular to the central axis R, the main torsion angle θ1 is the narrow angle among the angles formed by the tangent of the main cutting edge 11a at the point where the central axis R intersects with the main cutting edge 11a and the central axis R.

[0038] like Figure 2 as well as Figure 4As shown, the first cutting portion 13 has a first cutting rake face 13b, a first cutting opposite face 13c, a first cutting cutting edge 13a, and a first cutting connecting portion 13e. The first cutting rake face 13b and the first cutting opposite face 13c are connected to the main rake face 11b and the main flank face 11c, respectively. The first cutting rake face 13b is connected to the main flank face 11c via the first cutting cutting edge 13a. The first cutting opposite face 13c is connected to the main flank face 11c via the first cutting connecting portion 13e. The main cutting edge 11a intersects the first cutting cutting edge 13a at a first intersection point p1. The first cutting connecting portion 13e intersects the main cutting edge 11a at a third intersection point p3. That is, as shown... Figure 3 As shown, the first intersection point p1 is located on the outer peripheral surface 2. The third intersection point p3 is located on the outer peripheral surface 2.

[0039] Figure 2 Region IV shown is the cross-sectional area of ​​the main cutting edge 11 obtained by cutting the main cutting edge 11 in a direction perpendicular to the central axis R from the line segment along the main cutting edge 11a of the main cutting edge 11. That is, region IV is the cross-sectional area of ​​the main cutting edge 11 including the first intersection point p1, the second intersection point p2, the third intersection point p3, and the fourth intersection point p4. Figure 4 This is a partially enlarged cross-sectional schematic diagram of the main cutting edge 11 section in region IV. Figure 4 The schematic cross-sectional view shown represents the main cutting edge 11, which includes the first cut portion 13 and the second cut portion 14 (described later). The actual main cutting edge 11a is configured in a helical shape, thus becoming curved, but... Figure 4 For illustrative purposes, the main cutting edge 11a is represented as a straight line. Additionally, Figure 4 The vertical direction represents the radial direction centered on the central axis R of the cutting tool 1.

[0040] like Figure 4 As shown, the first slit rake face 13b and the first slit opposite face 13c are formed to extend from the main cutting edge 11a towards the central axis R. The first slit rake face 13b and the first slit opposite face 13c are connected via the first slit bottom 13d. The first slit bottom 13d is the part of the first slit portion 13 closest to the central axis R. That is, in the first slit portion 13, the first slit bottom 13d is the point furthest from the outer peripheral surface 2 in the direction of the central axis R. The distance from the outer peripheral surface 2 to the first slit bottom 13d is the depth h1. Figure 4 As shown, the width w1 of the first cut portion 13 is the length of the line segment connecting the first intersection point p1 and the third intersection point p3 of the first cut portion 13. Furthermore, the cross-sectional area A1 of the first cut portion 13 is determined by... Figure 4The area enclosed by the straight line connecting the first intersection point p1 and the third intersection point p3, the first cutting face 13b, and the area enclosed by the opposite side 13c of the first cutting. The width w1 of the first cutting portion 13 can be, for example, 0.35 mm or more and 4.2 mm or less. The depth h1 of the first cutting portion 13 can be, for example, 0.1 mm or more and 3.4 mm or less.

[0041] The first cutting edge 13a has a reverse twist angle θ2. For example... Figure 1 As shown, in the top view viewed from a direction perpendicular to the central axis R, the reverse twist angle θ2 is the narrow angle among the angles formed by the tangent of the first cutting edge 13a at the point where the central axis R intersects with the first cutting edge 13a and the central axis R. Figure 1 As shown, when viewed from above, the reverse torsion angle θ2 of the first cutting edge 13a is a torsion angle in the opposite direction to the main torsion angle θ1 of the main cutting edge 11a when viewed from the central axis R. Thus, the main cutting edge portion 11 has a first slit portion 13. By having such a first slit portion 13, vibration generation is suppressed and cutting resistance is reduced when cutting the workpiece material.

[0042] Here, as Figures 1 to 4 As shown, the cutting tool 1 according to this first embodiment is characterized in that the main cutting edge 11 has a second slit portion 14. Specifically, as Figure 1 As shown, in each main cutting edge 11, the second cutting edge 14 is arranged between the two first cutting edges 13 in the first direction X. The second cutting edge 14 may also be arranged, for example, at the midpoint between the two first cutting edges 13. As long as the strength of the cutting tool 1 can be ensured, the second cutting edge 14 may also be arranged at a position other than the midpoint between the two first cutting edges 13. For example, multiple (e.g., two) second cutting edges 14 may also be provided between the two first cutting edges 13.

[0043] like Figure 4 As shown, the shape of the second cut portion 14 is different from that of the first cut portion 13. Specifically, the relationship between the first cut portion 13 and the second cut portion 14 satisfies at least one of a first condition and a second condition. The first condition is that the width w1 of the first cut portion 13 is different from the width w2 of the second cut portion 14. The second condition is that the depth h1 of the first cut portion 13 is different from the depth h2 of the second cut portion 14. In this way, by providing the second cut portion 14, which has a different shape from the first cut portion 13, on the main cutting edge portion 11, vibrations generated during cutting can be significantly suppressed. As a result, the finishing quality of the machined surface of the workpiece material after being cut by this cutting tool 1 is improved.

[0044] like Figure 1As shown, the second cut portion 14 is disposed within the first region A. The first region A is the portion within ±30% of the cutting length W of region B, located at the center C of region B where the main cutting edge 11 is formed, in the first direction X. Specifically, region B, where the main cutting edge 11 is formed, extends from the front end face 2a of the cutting portion 10 to a position in the first direction X away from the cutting length W. The center C extends from the front end face 2a to a position half the length of the cutting length W in the first direction X. That is, if the direction in the first direction X, with the center C as a reference, where the front end face 2a is disposed, is set to positive, then the surface that extends a distance of +50% of the cutting length W of the cutting portion 10 along the first direction X from the center C is the front end face 2a. From a different perspective, the first region A is the region within ±30% of the cutting length W of the cutting portion 10, located at the center C in the first direction X. That is, the second cut portion 14 is disposed on the outer peripheral surface 2 of the cutting portion 10 in the first region A. The second cut 14 can also be formed in a region other than the first region A in the region B where the main cutting edge 11 is formed. However, due to manufacturing issues, it is sometimes more difficult to form the second cut 14 closer to the front end face 2a and the shank 20.

[0045] like Figure 2 as well as Figure 4 As shown, the second cutting portion 14 has a second cutting rake face 14b, a second cutting opposite face 14c, a second cutting edge 14a, and a second cutting connecting portion 14e. The second cutting rake face 14b and the second cutting opposite face 14c are connected to the main rake face 11b and the main flank face 11c, respectively. The second cutting rake face 14b is connected to the main flank face 11c via the second cutting edge 14a. The second cutting opposite face 14c is connected to the main flank face 11c via the second cutting connecting portion 14e. The main cutting edge 11a intersects the second cutting edge 14a at a second intersection point p2. The second cutting connecting portion 14e intersects the main cutting edge 11a at a fourth intersection point p4. That is, as shown... Figure 3 As shown, the second intersection point p2 is located on the outer peripheral surface 2. The fourth intersection point p4 is located on the outer peripheral surface 2.

[0046] like Figure 4 As shown, the second cutting rake face 14b and the second cutting opposite face 14c are formed to extend from the main cutting edge 11a towards the central axis R. The second cutting rake face 14b and the second cutting opposite face 14c are connected via the second cut bottom 14d. The second cut bottom 14d is the part of the second cut portion 14 closest to the central axis R. That is, in the second cut portion 14, the second cut bottom 14d is the point furthest from the outer peripheral surface 2 in the direction of the central axis R. The distance from the outer peripheral surface 2 to the second cut bottom 14d is the depth h2. Figure 4As shown, the width w2 of the second cut 14 is the length of the line segment connecting the second intersection point p2 and the fourth intersection point p4 of the second cut 14. Furthermore, the cross-sectional area A2 of the second cut 14 is determined by... Figure 4 The area enclosed by the straight line connecting the second intersection point p2 and the fourth intersection point p4, the second cutting face 14b, and the area enclosed by the opposite side of the second cutting face 14c.

[0047] Furthermore, the width w1 and depth h1 of the first cut portion 13, the width w2 and depth h2 of the second cut portion 14 are determined based on the contour shapes of the first cut portion 13 and the second cut portion 14. The contour shapes of the first cut portion 13 and the second cut portion 14 can also be measured using a non-contact three-dimensional measuring machine manufactured by Bruker Alicona. The cross-sectional area A1 of the first cut portion 13 and the cross-sectional area A2 of the second cut portion 14 can be calculated based on the aforementioned contour shapes of the first cut portion 13 and the second cut portion 14.

[0048] The second cutting edge 14a has a reverse twist angle θ3. For example... Figure 1 As shown, in the top view viewed from a direction perpendicular to the central axis R, the reverse twist angle θ3 is the narrow angle among the angles formed by the tangent of the second cutting edge 14a at the point where the central axis R intersects with the second cutting edge 14a and the central axis R. Figure 1 As shown, when viewed from above, the reverse twist angle θ3 of the second cutting edge 14a is a twist angle in the opposite direction to the main twist angle θ1 of the main cutting edge 11a when viewed from the central axis R. Thus, the main cutting edge portion 11 has a second cutting edge portion 14.

[0049] In each main cutting edge 11, the number of first slits 13 can be one or more, for example. The number of first slits 13 can be two or three. Furthermore, it is preferable that the number of first slits 13 included in each main cutting edge 11 is less than the number of main cutting edges 11 in the cutting tool 1. From another perspective, it is preferable that the number of main cutting edges 11 is greater than the number of first slits 13 included in each main cutting edge 11. In this way, if the number of main cutting edges 11 is different from the number of first slits 13, it is easy to configure the first slits 13 so that they do not overlap in the rotation direction of the cutting tool 1. Therefore, when cutting the workpiece, it is possible to prevent the formation of uncut areas on the cutting surface of the workpiece if the cutting tool 1 rotates one revolution.

[0050] The number of second slits 14 on each of the main cutting edges 11 can be one or more, for example. The number of second slits 14 on each of the main cutting edges 11 can be two or three. If the number of first slits 13 and second slits 14 on each of the main cutting edges 11 is large, the generation of vibration can be further suppressed and the cutting resistance can be further reduced when the cutting tool 1 is used to cut the material.

[0051] However, by providing the second kerf 14, the strength of the main cutting edge 11 and the tool life may be reduced. Therefore, the cutting tool 1 can also be coated with diamond. This can improve the strength and tool life of the cutting tool 1.

[0052] <Effects>

[0053] The cutting tool 1 according to this disclosure includes a shaft portion 30 and at least two main cutting edges 11. The shaft portion 30 extends along a central axis R. The shaft portion 30 has an outer peripheral surface 2. The outer peripheral surface 2 surrounds the central axis R. The two or more main cutting edges 11 are arranged in a helical manner on the outer peripheral surface 2. The main cutting edges 11 have main cutting edges 11a. The main cutting edges 11a have a twist angle θ1. In the direction along the central axis R, within ±30% of the cutting length W from the center C of region B to region B, the main cutting edges 11 have at least one first slit portion 13 and a second slit portion 14. The main cutting edges 11 are formed in region B. The first slit portion 13 and the second slit portion 14 have twist angles θ2 and θ3 in the opposite direction to the twist angle θ1. The relationship between the first slit portion 13 and the second slit portion 14 satisfies at least one of a first condition and a second condition. The first condition is that the width w1 of the first cut portion 13 is different from the width w2 of the second cut portion 14. The second condition is that the depth h1 of the first cut portion 13 is different from the depth h2 of the second cut portion 14.

[0054] This significantly suppresses vibrations generated during cutting. As a result, the finishing of the machined surface of the workpiece after cutting with this cutting tool 1 is greatly improved.

[0055] In the cutting tool 1 described above, the first condition may also be that the width w1 of the first cut portion 13 is more than twice and less than ten times the width w2 of the second cut portion 14. The second condition may also be that the depth h1 of the first cut portion 13 is more than twice and less than fifteen times the depth h2 of the second cut portion 14.

[0056] This significantly suppresses vibrations generated during cutting and ensures adequate chip removal. As a result, chips do not clog the second cut portion 14 during cutting, and the finishing quality of the machined surface of the material being cut is greatly improved.

[0057] In the cutting tool 1 described above, the cross-sectional area A1 of the first kerf portion 13 can be more than 5 times and less than 120 times the cross-sectional area A2 of the second kerf portion 14. This significantly suppresses vibrations generated during cutting and ensures adequate chip removal. As a result, chips do not clog the second kerf portion 14 during cutting, and the finishing quality of the machined surface of the workpiece is greatly improved.

[0058] In the cutting tool 1 described above, the number of main cutting edges 11 can be greater than the number of first slits 13 included in each main cutting edge 11. In this way, during cutting, when the cutting tool 1 rotates once, it is possible to suppress the generation of cutting residue on the workpiece.

[0059] In the cutting tool 1 described above, the torsion angle θ1 of the main cutting edge 11a can be 30° or more and 50° or less. The torsion angles θ2 and θ3 of the first slit portion 13 and the second slit portion 14, respectively, which are opposite to the torsion angle θ1, can also be 30° or more and 50° or less. Thus, as will be described later, vibration generation is suppressed during cutting, cutting resistance is reduced, and the finishing quality of the machined surface is improved.

[0060] In the cutting tool 1 described above, the main cutting edge 11 may also include at least two or more first slits 13. A second slit 14 may also be positioned between the two first slits 13. This minimizes the reduction in strength of the main cutting edge 11 caused by the provision of the second slit 14.

[0061] The cutting tool 1 can be coated with diamond. This improves the strength and lifespan of the cutting tool 1.

[0062] In order to verify the effect of the cutting tool 1 according to the first embodiment as described above, the following experiment was conducted.

[0063] (Experiment 1)

[0064] <Experimental Subjects>

[0065] In Experiment 1, the finishing of the cutting surface of the workpiece, chip removal, and tool life of the cutting tool 1 were evaluated based on the presence or absence of the second kerf 14. The test subjects were three types of cutting tools 1, samples 1 to 3. The cutting diameter of the cutting tools 1 involved in samples 1 to 3 was 10 mm, and the number of main cutting edges 11 was 5. The number of first kerfs 13 in one main cutting edge 11 was 6. In samples 1 and 2, the main cutting edge 11 had a first kerf 13 but no second kerf 14. On the other hand, in sample 3, the main cutting edge 11 had both a first kerf 13 and a second kerf 14. The number of second kerfs 14 in the first region A of one main cutting edge 11 in sample 3 was 6. The width w1 of the first kerf 13 of the cutting tool 1 involved in sample 2 was smaller than the width w1 of the first kerf 13 of the cutting tools 1 involved in samples 1 and 3. The width W1 of the first cut portion 13 in samples 1 and 3 is 2.0 mm, and the depth h1 is 1.5 mm. The width W1 of the first cut portion 13 in sample 2 is 1.0 mm, and the depth h1 is 0.6 mm. The width W2 of the second cut portion 14 in sample 3 is 0.5 mm, and the depth h2 is 0.3 mm. Therefore, the influence of the width w1 of the first cut portion 13 and the presence or absence of the second cut portion 14 was investigated.

[0066] <Experimental Conditions>

[0067] The symmetrical material to be cut is CFRP. The thickness of the CFRP is 6 mm. As for the cutting conditions, the rotational speed of the cutting tool 1 is set to 4000 rpm, and the machining speed is set to 400 mm / min.

[0068] <Results>

[0069] [Table 1]

[0070]

[0071] The test results are shown in Table 1. Table 1 lists, from left to right, the width w1 of the first cut portion 13 (as conditions), the presence or absence of the second cut portion 14, the finishing of the cutting surface of the workpiece, chip removal performance, and the tool life of the cutting tool 1 (as test results). Furthermore, in Table 1, A, B, and C represent the evaluation of each item in terms of cutting surface finishing, chip removal performance, and tool life of the cutting tool 1. B indicates better than C. A indicates better than B. That is, A represents the best evaluation result among A, B, and C. In particular, good chip removal performance indicates that clogging caused by chips can be suppressed.

[0072] As shown in Table 1, based on the test results of the cutting tool 1 involved in Samples 1 and 2, by reducing the width w1 of the first kerf, the cross-sectional area A1 of the first kerf 13 becomes smaller, and the chip removal performance deteriorates. Chips become stuck in the first kerf 13, thereby increasing the cutting resistance of the cutting tool 1, and consequently reducing the tool life of the cutting tool 1.

[0073] Based on the test results of the cutting tool 1 involved in Samples 1 and 3, by adding a second kerf 14 to the main cutting edge 11 in addition to the first kerf 13, the finishing of the cutting surface is improved. This is believed to be due to reduced vibration during cutting, resulting in improved finishing of the cutting surface. By providing the second kerf 14, the area for chip removal increases, thus improving chip removal performance. As a result, it is believed that by providing the second kerf 14, tool life remains good without decreasing.

[0074] (Experiment 2)

[0075] <Experimental Subjects>

[0076] In Experiment 2, the finishing of the cutting surface of the workpiece material based on the shape of the second notch 14, chip removal, and tool life of the cutting tool 1 were evaluated. Ten cutting tools 1, from Samples 4 to 13, were tested. In the cutting tool 1 of Sample 4, the main cutting edge 11 has a first notch 13 but not a second notch 14. On the other hand, in the cutting tools 1 of Samples 5 to 13, the main cutting edge 11 has both a first notch 13 and a second notch 14. Specifically, in the cutting tools 1 of Samples 5 to 13, the effects of changing the width ratio (w1 / w2), depth ratio (h1 / h2), and cross-sectional area ratio (A1 / A2) were mainly investigated. The width ratio is the value obtained by dividing the width w1 of the first notch 13 by the width w2 of the second notch 14. The depth ratio is the value obtained by dividing the depth h1 of the first notch 13 by the depth h2 of the second notch 14. The cross-sectional area ratio is the value obtained by dividing the cross-sectional area A1 of the first cut portion 13 by the cross-sectional area A2 of the second cut portion 14.

[0077] The cutting tool 1 involved in samples 4 to 10 and the cutting tool 1 involved in sample 13 have a cutting diameter of 10 mm. The cutting tool 1 involved in samples 11 and 12 has a cutting diameter of 3 mm. In the cutting tool 1 involved in samples 4 to 6, the principal torsion angle θ1 of the main cutting edge 11a is 45°. On the other hand, in the various cutting tools 1 involved in samples 7 to 10, the principal torsion angle θ1 of the main cutting edge 11a varies between 20° and 50°. In the cutting tool 1 involved in samples 4 to 12, the cutting tool 1 is coated with diamond. On the other hand, in the cutting tool 1 involved in sample 13, the cutting tool 1 is not coated with diamond. In addition, regarding the cutting tool 1 involved in samples 4 to 10 and the cutting tool 1 involved in sample 13 with a cutting diameter of 10 mm, the number of main cutting edges 11 is 5, and the number of first kerfs 13 and the number of second kerfs 14 in one main cutting edge 11 are 6 each. On the other hand, regarding the cutting tool 1 involved in the samples 11 and 12 with a cutting diameter of 3 mm, the number of main cutting edges 11 is 3, and the number of first slits 13 and second slits 14 in one main cutting edge 11 are 4 each.

[0078] <Experimental Conditions>

[0079] The symmetrical material to be cut is CFRP. The thickness of the CFRP is 6 mm. As for the cutting conditions, the rotational speed of the cutting tool 1 is set to 8000 rpm, and the machining speed is set to 1600 mm / min.

[0080] Results [Table 2]

[0081]

[0082] The test results are shown in Table 2. Table 2 lists, from left to right, the following conditions: width ratio, depth ratio, cross-sectional area ratio, principal torsion angle θ1, presence or absence of diamond coating, finishing of the cutting surface of the workpiece, chip removal performance, and tool life of the cutting tool 1. Furthermore, in Table 2, A, B, C, and D represent the evaluation of each item in terms of cutting surface finishing, chip removal performance, and tool life of the cutting tool 1. C indicates better than D. B indicates better than C. A indicates better than B. That is, A represents the best evaluation result among A, B, C, and D.

[0083] As shown in Table 2, the finishing of the cutting surface of the cutting tool 1 involved in Sample 4 is improved compared to that of Sample 5 to Sample 13. The chip removal performance of the cutting tool 1 involved in Sample 4 is also improved compared to that of Sample 5 to Sample 13. Therefore, by adding a second cutting portion 14 to the main cutting edge portion 11 based on the first cutting portion 13, both the finishing of the cutting surface and the chip removal performance can be improved. In this respect, Experiment 2 can be considered to have the same results as Experiment 1. In particular, according to the experimental results of the cutting tool 1 involved in Samples 5 and 6, when the width ratio and depth ratio increase, the cross-sectional area ratio increases, thus significantly improving not only the finishing of the cutting surface but also the chip removal performance.

[0084] The width ratio of the cutting tool 1 involved in samples 7 and 9 is 11 times. Therefore, the length of the main cutting edge 11a is insufficient, resulting in poor finishing of the cutting surface. Therefore, the width ratio is preferably 10 times or less. The cutting tool 1 involved in sample 8 has a weak helical design with a main twist angle θ1 of 30° for the main cutting edge, but the finishing of the cutting surface and chip removal are improved.

[0085] The cutting tool 1 involved in sample 10 has a depth ratio of 17. As a result, the cutting tool 1 has low rigidity. Therefore, the depth ratio is preferably 16 or less. Based on the above results, it is preferable that the width w1 of the first cut portion 13 is at least 2 times and less than 10 times the width w2 of the second cut portion 14. It is preferable that the depth h1 of the first cut portion 13 is at least 2 times and less than 15 times the depth h2 of the second cut portion 14. From another point of view, the cross-sectional area A1 of the first cut portion 13 is preferably at least 5 times and less than 120 times the cross-sectional area A2 of the second cut portion 14.

[0086] Based on the test results of the cutting tool 1 involved in the samples 11 and 12 with a cutting diameter of 3 mm, by providing a second cutting section 14 in the main cutting edge 11, the finishing of the cutting surface and the chip removal are improved in the same way as the cutting tool 1 with a cutting diameter of 10 mm.

[0087] However, by providing a second kerf 14 on the main cutting edge 11, there is a potential risk of reduced tool life for the cutting tool 1. Test results from samples 6 and 13 show that the tool life of the cutting tool 1 is significantly improved by applying diamond coating.

[0088] (First variation of the first embodiment)

[0089] <Structure of the variant>

[0090] Figure 5This is a partially enlarged top view showing a modified example 1 of the cutting tool 1 according to the first embodiment. Figure 5 Corresponding to Figure 2 . Figure 6 yes Figure 5 A magnified cross-sectional view of a portion of region VI. Figure 6 Corresponding to Figure 4 .

[0091] Figure 5 as well as Figure 6 The cutting tool 1 shown basically has the same characteristics as Figures 1 to 4 The cutting tool 1 shown has the same structure, but differs in that it has two second cuts 14 formed between the two first cuts 13. Specifically, as Figure 6 As shown, two second slits 14 are formed on the main cutting edge 11 in a manner that allows them to be held between two first slits 13. The number of second slits 14 is not limited to two. For example, three second slits 14 may also be formed on the main cutting edge 11 in a manner that allows them to be held between two first slits 13. In this way, by forming multiple second slits 14 between two first slits 13, vibrations generated during cutting can be further suppressed. As a result, the finishing quality of the machined surface of the workpiece after cutting with this cutting tool 1 is further improved.

[0092] (Second variation of the first embodiment)

[0093] <Structure of the variant>

[0094] Figure 7 This is a partially enlarged top view showing a modified example 2 of the cutting tool 1 according to the first embodiment. Figure 7 Corresponding to Figure 2 . Figure 8 yes Figure 7 A partially enlarged cross-sectional view of region VIII. Figure 8 Corresponding to Figure 4 .

[0095] Figure 7 as well as Figure 8 The cutting tool 1 shown basically has the same characteristics as Figures 1 to 4The cutting tool 1 shown has the same structure, but differs in that the width w2 of the second cut portion 14 is larger than the width w1 of the first cut portion 13. To ensure chip removal, the depth h1 of the first cut portion 13 should be greater than the depth h2 of the second cut portion 14. Alternatively, the width w1 of the first cut portion 13 should be greater than the width w2 of the second cut portion 14. Specifically, based on the results of the above-described experiment 2, the relationship between the first cut portion 13 and the second cut portion 14 satisfies at least one of the first and second conditions. The first condition is that the width w1 of the first cut portion 13 is more than twice and less than ten times the width w2 of the second cut portion 14. The second condition is that the depth h1 of the first cut portion 13 is more than twice and less than fifteen times the depth h2 of the second cut portion 14.

[0096] In this way, the cutting tool 1 can ensure chip removal and suppress vibrations generated during cutting.

[0097] The embodiments disclosed herein should be considered exemplary in all respects, not limiting. The basic scope of the invention is not defined by the above-described embodiments, but by the claims, and is intended to include all modifications equivalent to and within the scope of the claims.

[0098] Explanation of reference numerals in the attached figures

[0099] 1: Cutting tool; 2: Outer peripheral surface; 2a: Front end face; 2b: Rear end face; 10: Cutting section; 11: Main cutting edge; 11a: Main cutting edge; 11b: Main rake face; 11c: Main flank face; 13: First kerf section; 13a: First kerf cutting edge; 13b: First kerf rake face; 13c: Opposite side of the first kerf; 13d: Bottom of the first kerf; 13e: Connecting part of the first kerf; 14: Second kerf section; 14a: Second kerf cutting edge Cutting edge; 14b: Rake face of the second cut; 14c: Opposite to the second cut; 14d: Bottom of the second cut; 14e: Connecting part of the second cut; 20: Shank; 30: Shaft; A: First region; A1, A2: Cross-sectional area; B: Region; C: Center; R: Central axis; W: Cutting length; X: First direction; h1, h2: Depth; w1, w2: Width; p1: First intersection point; p2: Second intersection point; p3: Third intersection point; p4: Fourth intersection point.

Claims

1. A cutting tool, wherein, The cutting tool has the following features: A shaft portion, extending along a central axis, and having an outer peripheral surface surrounding the central axis; and At least two main cutting edges are arranged in a spiral pattern on the outer circumferential surface. The main cutting edge portion has a main cutting edge, which has a torsion angle, and therefore... Along the central axis, in a portion within ±30% of the blade length of the region where the main cutting edge is formed, the main cutting edge includes at least one first slit portion and a second slit portion having a torsion angle opposite to the torsion angle. When the first condition is that the width of the first incision is different from the width of the second incision, and the second condition is that the depth of the first incision is different from the depth of the second incision, the relationship between the first incision and the second incision satisfies at least one of the first and second conditions. The first condition is that the width of the first incision is more than twice and less than ten times the width of the second incision.

2. The cutting tool according to claim 1, wherein, The second condition is that the depth of the first incision is more than twice and less than 15 times the depth of the second incision.

3. The cutting tool according to claim 1 or 2, wherein, The cross-sectional area of ​​the first incision is more than 5 times and less than 120 times the cross-sectional area of ​​the second incision.

4. The cutting tool according to claim 1 or 2, wherein, The number of main cutting edges is greater than the number of first slits contained in each of the main cutting edges.

5. The cutting tool according to claim 1 or 2, wherein, The torsion angle in the main cutting edge is greater than 30° and less than 50°. The torsion angle of each of the first cut portion and the second cut portion, which is in the opposite direction to the torsion angle, is 30° or more and 50° or less.

6. The cutting tool according to claim 1 or 2, wherein, The main cutting edge includes at least two or more first cutting edges. The second cut is positioned between the two first cuts.

7. The cutting tool according to claim 1 or 2, wherein, The width of the first cut is 0.35 mm or more and 4.2 mm or less.

8. The cutting tool according to claim 1 or 2, wherein, The depth of the first incision is more than 0.1 mm and less than 3.4 mm.

9. The cutting tool according to claim 1 or 2, wherein, The second cut is formed in the region where the main cutting edge is formed, and in the region other than the portion within ±30% of the blade length of the region from the center of the region where the main cutting edge is formed.

10. The cutting tool according to claim 1 or 2, wherein, The cutting tool is coated with diamond.

Images