Tool body and cutting edge replaceable rotary cutting tool

Abstract

Provided is a cutting edge replaceable rotary cutting tool that rotates around a rotary axis (O). The tool has a modular head having a cutting edge, and a tool body. The tool body is provided with a gripping part, a tapered part, and a connection part. The tapered part has a first region and a second region. In the rotary axis (O) direction, the distance (L1) between a point (P1) and a point (P2) is longer than the distance (L2) between a point (Q1) and a point (Q2), and an inclination angle (θ2) is greater than an inclination angle (θ1).

Description

Tool body, indexable rotary cutting tool

[0001] This application claims priority to Japanese Patent Application No. 2024-064987, filed on April 12, 2024, the contents of which are incorporated herein by reference.

[0002] Conventionally, modular head type indexable rotary cutting tools that can handle machining conditions with large tool overhangs are known (see Patent Document 1). Also, as a shank for such indexable rotary cutting tools, a tapered shank that tapers toward the tip is known (see Non-Patent Document 1). Meanwhile, solid-type end mills that can cut deep areas are also known (see Non-Patent Document 2).

[0003] JP 2012-157966 A

[0004] PRODUCT NEWS, Daijet Industrial Co., Ltd., No. 418 Revised, p. 49 Cutting Tool Product Catalog 2023-2024, MOLDINO Co., Ltd., p. A88

[0005] FIG. 6 is an explanatory diagram comparing an indexable rotary cutting tool with a solid tool. In the modular-head indexable rotary cutting tool 100 shown in FIG. 6 , a modular head 103 is attached to the tip of a tapered shank 101, and a cutting insert 104 is further attached to the tip of the modular head 103. In this case, the axial distance L between the tapered portion 102 of the shank 101 and the cutting edge 105 is increased by the amount of the modular head 103. Therefore, the taper angle α of the tapered portion 102 of the shank 101 is larger than the taper angle β of the tapered portion 202 of the shank 201 of a solid tool 200 having an equivalent configuration. As a result, as shown in FIG. 6 , the tapered portion 102 is thinner than the tapered portion 202 of the solid tool 200, which poses a problem of reduced tool rigidity. Furthermore, in the solid tool 200, the taper angle β is approximately the same as the wall angle of the die to be machined, whereas in the indexable rotary cutting tool 100, the taper angle α of the shank 101 is larger than the wall angle of the die to be machined. Therefore, when adjusting the position of the indexable rotary cutting tool by bringing it close to the wall surface of the workpiece, the wall angle of the workpiece and the taper angle α of the shank 101 are different, which may lead to the operator mistakingly determining that the indexable cutting tool 100 and the wall of the workpiece W are interfering with each other, resulting in the problem of unnecessary confirmation work.

[0006] An object of the present invention is to provide an indexable rotary cutting tool that ensures tool rigidity, prevents misunderstandings by the operator, and reduces unnecessary confirmation work.

[0007] According to one aspect of the present invention, there is provided a tool body for use in an indexable rotary cutting tool that rotates about a rotation axis O, the tool body being held by a tool holder at its rear end and connected to a modular head having a cutting edge at its front end, the tool body comprising: a columnar gripping portion; a tapered portion connected to the front end of the gripping portion and having a diameter that narrows toward the front end; and a connection portion located at the front end of the tapered portion and to which the modular head is connected. The tapered portion has a first region extending from a connection position with the gripping portion toward the front end, and a second region located further toward the front end than the first region. In a side view, when the connection point between the first region and the gripping portion is defined as point P1, the front end end of the first region is defined as point P2, the rear end end of the second region is defined as point Q1, and the front end end of the second region is defined as point Q2, a distance L1 between points P1 and P2 in the direction of the rotation axis O is longer than a distance L2 between points Q1 and Q2. When the inclination angle θ1 of the first region is the angle between the rotation axis O and the tangent N1 of the first region at point P2, and the inclination angle θ2 of the second region is the angle between the rotation axis O and the tangent N2 of the second region at point Q2, the inclination angle θ2 is greater than the inclination angle θ1.

[0008] The distance L1 and the distance L0 between the point P1 and the point Q2 in the direction of the rotation axis O may satisfy the relationship 0.98≧L1 / L0≧0.50.

[0009] According to the above configuration, by providing a multi-stage tapered portion of the tool body, the inclination angle of the rear end portion of the tapered portion can be reduced, while the outer diameter of the front end portion of the tapered portion can be adjusted to match the modular head. In the tapered portion of the tool body, the axial length of the first region (distance L1) is greater than the axial length of the second region (distance L2), and the inclination angle θ2 of the second region is greater than the inclination angle θ1 of the first region. This ensures a sufficient length and connection diameter for deep cutting when the modular head is connected to the shank, thereby ensuring rigidity. At the same time, the inclination angle θ1 of the first region located at the rear end portion of the tapered portion can be set to the same inclination angle as the tapered portion of a solid tool. This allows the inclination angle θ1 of the first region to approach the wall angle of the cutting target. As a result, when aligning an indexable rotary cutting tool equipped with this tool body with the wall of the workpiece, the user is less likely to mistakenly believe that the tapered portion and the wall of the workpiece interfere with each other. This reduces unnecessary confirmation work caused by mistaken recognition.

[0010] The inclination angle θ1 may be in the range of 6.0°≧θ1≧0.3°, and the inclination angle θ2 may be in the range of 60°≧θ2≧1.5°.

[0011] In a side view seen from a direction perpendicular to the rotation axis O, the first region and the second region may both have a linear outer peripheral surface.

[0012] In a side view seen from a direction perpendicular to the rotation axis O, the first region and the second region may both have outer peripheral surfaces that are convexly curved and protrude radially outward.

[0013] The tapered portion may have one or more tapered intermediate regions between the first region and the second region, the tapered intermediate region having an inclination angle θn different from those of the first region and the second region, the distance Ln between the rear end point of the intermediate region and the tip end point in the direction of the rotation axis O being L1 > Ln, the inclination angle θn of the intermediate region being the angle between the rotation axis O and a tangent Nn to the tip end point of the intermediate region, and the relationship θ2 > θn > θ1 may be satisfied.

[0014] According to one aspect of the present invention, there is provided an indexable rotary cutting tool that rotates about a rotation axis O, the indexable rotary cutting tool comprising: a modular head having a cutting edge; and a tool body that is held by a tool holder at its rear end and connected to the modular head at its front end. The tool body has a columnar gripping portion, a tapered portion that is connected to the front end of the gripping portion and has a diameter that narrows toward the front end, and a connection portion that is located at the front end of the tapered portion and to which the modular head is connected. The tapered portion has a first region that extends from the connection position with the gripping portion toward the front end, and a second region that is located further toward the front end than the first region. In a side view, when the connection point between the first region and the grip portion is defined as point P1, the tip end point of the first region is defined as point P2, the rear end point of the second region is defined as point Q1, and the tip end point of the second region is defined as point Q2, a distance L1 between points P1 and P2 in the direction of the rotation axis O is longer than a distance L2 between points Q1 and Q2. When an inclination angle θ1 of the first region is defined as the angle between the rotation axis O and a tangent N1 to the first region at point P2, and an inclination angle θ2 of the second region is defined as the angle between the rotation axis O and a tangent N2 to the second region at point Q2, the inclination angle θ2 is greater than the inclination angle θ1.

[0015] According to the present invention, there are provided an indexable rotary cutting tool and its tool body that ensure tool rigidity, prevent operator misunderstandings, and reduce unnecessary checking work.

[0016] FIG. 1 is a side view of an indexable rotary cutting tool according to an embodiment. FIG. 2 is an exploded view of the indexable rotary cutting tool shown in FIG. 1. FIG. 3 is a side view of a first modified example of an indexable rotary cutting tool. FIG. 4 is a side view of a second modified example of an indexable rotary cutting tool. FIG. 5 is a schematic diagram illustrating the positioning of the indexable rotary cutting tool shown in FIG. 1 when it is brought close to the wall surface of a workpiece W. FIG. 6 is an explanatory diagram comparing an indexable rotary cutting tool with a solid tool. FIG. 7 is a diagram showing the results of a rough machining region cutting evaluation. FIG. 8 is a diagram showing the results of a finish dimensional accuracy evaluation.

[0017] Fig. 1 is a side view of the indexable rotary cutting tool of this embodiment. Fig. 2 is an exploded view of the indexable rotary cutting tool shown in Fig. 1. In Fig. 2, a shank 2, which is the tool body, is shown in a vertical cross section.

[0018] The indexable rotary cutting tool 1 of this embodiment is a rotary cutting tool that rotates around a rotation axis O. The indexable rotary cutting tool 1 includes a modular head 4 that holds a cutting insert 3, and a shank 2 (tool body) to which the modular head 4 is attached. The shank 2 is a cylindrical member that extends along the rotation axis O. The shank 2 is made of, for example, cemented carbide, steel, or the like. The modular head 4 is made of, for example, steel, and is attached by being screwed onto the tip of the shank 2, as shown in FIG. 2 .

[0019] In the following description, the direction from the shank 2 to the modular head 4 along the axial direction of the rotation axis O of the indexable rotary cutting tool 1 will be referred to as the tip side, and the direction from the modular head 4 to the shank 2 will be referred to as the rear side. Furthermore, the direction perpendicular to the rotation axis O of the indexable rotary cutting tool 1 will be referred to as the radial direction, and the direction going around the rotation axis O will be referred to as the circumferential direction.

[0020] The indexable rotary cutting tool 1 of this embodiment is an indexable ball end mill. The indexable rotary cutting tool 1 is rotatable around a rotation axis O. The rotation axis O of the indexable rotary cutting tool 1 coincides with the central axis of the indexable rotary cutting tool 1.

[0021] The indexable rotary cutting tool 1 has a cutting insert 3 attached to a modular head 4, and the rear end of the shank 2 is held by a spindle (tool holder) of a machine tool. The indexable rotary cutting tool 1 is rotated around a rotation axis O in a tool rotation direction T, and is fed in a direction intersecting the rotation axis O, whereby cutting is performed on a workpiece W by a cutting edge 31 provided on the cutting insert 3.

[0022] The workpiece W to be cut by the indexable rotary cutting tool 1 of this embodiment is the wall surface of a shaped portion with a draft angle, such as a plastic mold or a die-cast mold. As shown in Figure 5, the indexable rotary cutting tool 1 is assumed to be extended along the wall surface of the workpiece W to cut deep portions or grooves. The wall angle γ is the inclination angle with respect to the depth direction of the workpiece W and is equal to the inclination angle with respect to the tool rotation axis O. The wall angle γ is in the range of 10° ≥ γ > 0°.

[0023] The cutting insert 3 is made of, for example, cemented carbide. In this embodiment, the cutting insert 3 is plate-shaped with an arcuate contour and is provided with an arcuate cutting edge 31 on the outermost ridge. In this embodiment, the cutting edge 31 is a ball blade whose rotation trajectory around the rotation axis O is hemispherical. Two cutting edges 31 are arranged at positions 180° rotationally symmetrical about the rotation axis O. The cutting insert 3 is provided with a through hole that penetrates the cutting insert 3 in the plate thickness direction. A fixing screw 12 is passed through the through hole of the cutting insert 3 when fixing the cutting insert 3 to the modular head 4.

[0024] A mounting seat 8 to which the cutting insert 3 can be attached is provided at the tip of the modular head 4. The cutting insert 3 is placed on the mounting seat 8 with its central axis (insert central axis) aligned with the central axis of the modular head 4. In other words, the central axis of the modular head 4 and the central axis of the cutting insert 3 are arranged coaxially with each other. The central axis of the cutting insert 3 and the central axis of the modular head 4 also coincide with the rotation axis O of the indexable rotary cutting tool 1.

[0025] The modular head 4 is made of steel. The modular head 4 is preferably formed of steel having a hardness of 35 HRC or higher. As shown in Fig. 2, the modular head 4 has a generally cylindrical head body 41 and a mounting screw 42 extending from the rear end surface of the head body 41 toward the rear end. A mounting seat 8 consisting of a groove into which the cutting insert 3 is inserted is provided at the tip of the head body 41 of the modular head 4.

[0026] The groove-shaped mounting seat 8 is formed to divide the tip of the head body 41 into two gripping portions. The two gripping portions each extend in the axial direction at the tip of the head body 41. The two gripping portions are provided with a through hole and a threaded hole into which a fixing screw 12 for fixing the cutting insert 3 is fastened.

[0027] The mounting screw 42 is located at the rear end of the modular head 4. The mounting screw 42 has a male thread portion that is centered on the rotation axis O and extends along the rotation axis O. The male thread portion of the mounting screw 42 is fitted into a female thread portion 25a of a connection portion 25 of the shank 2, which will be described later.

[0028] The shank 2 has a cylindrical shape extending along the rotation axis O. The shank 2 includes a cylindrical gripping portion 20, a tapered portion 24 extending from the gripping portion 20 toward the tip end in a tapered shape, and a connecting portion 25 located at the tip end of the tapered portion 24 and consisting of a recess to which the modular head 4 is connected.

[0029] The tapered portion 24 has a first region 21 extending from the connection position with the grip portion 20 toward the tip side, and a second region 22 located closer to the tip side than the first region 21. In the case of this embodiment, the outer circumferential surface of the first region 21 and the outer circumferential surface of the second region 22 are both tapered surfaces having a uniform inclination angle with respect to the direction of the rotation axis O.

[0030] The shank 2 has no step between the grip portion 20 and the first region 21. The tip of the cylindrical outer peripheral surface of the grip portion 20 and the rear end of the tapered outer peripheral surface of the first region 21 are connected to each other via an obtuse corner or a smooth curved surface. With this shape, when the tool body is brought close to the wall surface of the workpiece and its position is adjusted, interference with the wall surface can be suppressed because the tool has no step.

[0031] In a side view seen from a direction perpendicular to the rotation axis O, both the first region 21 and the second region 22 have a linear outer peripheral surface. In other words, in a side view seen from a direction perpendicular to the rotation axis O, the outer edges of the outer peripheral surfaces are linear between points Q1 and Q2 and between points P1 and P2. This shape also makes it easy to manufacture the shank.

[0032] As shown in FIG. 1 , in a side view, the connection point between the first region 21 and the grip portion 20 is designated as point P1, and the tip end point of the first region 21 is designated as point P2. The rear end point of the second region 22 is designated as point Q1, and the tip end point of the second region is designated as point Q2. The length of the first region 21 in the direction of the rotation axis O is defined as the distance L1 between points P1 and P2 in the direction of the rotation axis O. The length of the second region 22 in the direction of the rotation axis O is defined as the distance L2 between points Q1 and Q2 in the direction of the rotation axis O. In the shank 2, the distance L1 is greater than the distance L2. That is, the first region 21 located in the rear end portion of the tapered portion 24 is longer in the axial direction than the second region 22 located in the tip end portion of the tapered portion 24.

[0033] The points P2 and Q2 or the areas in the vicinity thereof may be chamfered, preferably within a range of 1.0 mm to 0.2 mm in the direction of the rotation axis O.

[0034] The inclination angle θ1 of the first region 21 is defined as the angle between the rotation axis O and a tangent N1 to the first region 21 at point P2. The inclination angle θ2 of the second region 22 is defined as the angle between the rotation axis O and a tangent N2 to the second region 22 at point Q2. In the shank 2, the inclination angle θ2 of the second region 22 is larger than the inclination angle θ1 of the first region 21. Preferably, the inclination angle θ2 is larger than the inclination angle θ1 by 5.0° or more.

[0035] The connecting portion 25 is a recess that opens at the tip surface of the shank 2 and recesses toward the rear end. The connecting portion 25 has a female thread portion 25a. A mounting screw 42 of the modular head 4 is screwed into the female thread portion 25a. A through hole 26 that passes through the shank 2 in the axial direction is formed from the bottom surface of the connecting portion 25. The through hole 26 has a circular cross section that is coaxial with the shank 2. The diameter of the through hole 26 is smaller than the diameter of the connecting portion 25.

[0036] In this embodiment, the length of the connecting portion 25 in the direction of the rotation axis O is greater than the length (distance L2) of the second region 22 of the tapered portion 24 in the direction of the rotation axis O. The female thread portion 25a of the connecting portion 25 extends from the middle portion of the second region 22 in the direction of the rotation axis O, passing through point Q2 which is the rear end point of the second region 22, and into the first region 21.

[0037] In the indexable rotary cutting tool 1 of the present embodiment described above, by making the tapered portion 24 of the shank 2 multi-stage, it is possible to reduce the inclination angle of the rear end portion of the tapered portion 24, while making the tip end portion of the tapered portion 24 have an outer diameter that matches the modular head 4. Furthermore, in the tapered portion 24 of the shank 2, the axial length (distance L1) of the first region 21 is greater than the axial length (distance L2) of the second region 22, and the inclination angle θ2 of the second region 22 is greater than the inclination angle θ1 of the first region 21. This ensures that, when the modular head 4 is connected to the shank 2, the length and diameter of the connection portion that enable deep cutting can be secured, and rigidity can be ensured.

[0038] 6 , the taper angle β of the solid tool 200 is approximately the same as the wall angle γ of the workpiece W, so the operator does not feel any risk of interference when adjusting the position of the solid tool 200 by bringing it close to the wall surface of the workpiece W. On the other hand, when adjusting the position of a conventional indexable rotary cutting tool 100, the angle Δ of the line d2 connecting the axial base end point 106 of the tapered portion 102 and the radially outermost point 107 of the cutting insert 104 is approximately the same as the taper angle β (the wall angle γ of the workpiece W). Therefore, there is no risk of interference in terms of design, but the apparent taper angle α of the shank 101 is larger than the taper angle β (the wall angle γ of the workpiece W). As a result, because the wall angle γ of the workpiece W and the taper angle α of the shank 101 are different, the operator may mistakenly believe that the indexable cutting tool 100 and the wall of the workpiece W are interfering with each other, resulting in unnecessary confirmation work.

[0039] In the indexable rotary cutting tool 1 of this embodiment, the inclination angle θ1 of the first region 21 located at the rear end portion of the tapered portion 24 can be set to the same inclination angle as the tapered portion 202 of the solid tool 200 shown in FIG. 6. That is, as shown in FIG. 5, the inclination angle θ1 of the first region 21 can be made closer to the wall angle γ of the workpiece W. As a result, when aligning the indexable rotary cutting tool 1 with the wall of the workpiece, the user is less likely to mistakenly believe that the tapered portion 24 and the wall of the workpiece W are interfering with each other. This reduces unnecessary confirmation work that may result from such a mistaken recognition.

[0040] In the shank 2 of this embodiment, the length of the tapered portion 24 is defined as the distance L0 between points P1 and Q2 shown in FIG. 1 . In this embodiment, the ratio L1 / L0 of the distance L1 to the distance L0 preferably satisfies the relationship 0.98 ≧ L1 / L0 ≧ 0.50. Furthermore, L1 / L0 may be 0.6 or greater, 0.7 or greater, or 0.8 or greater. When the ratio L1 / L0 is within the above range, the first region 21, which has a relatively large outer diameter, occupies more than half of the entire tapered portion 24. This ensures the rigidity of the shank 2. Furthermore, because a large proportion of the first region 21 has an angle close to the angle of the wall formed in the workpiece, the user is less likely to mistakenly recognize interference.

[0041] It is preferable that the difference between the inclination angle θ1 of the first region 21 and the wall angle γ of the workpiece W is 0.5° or less. By making the inclination angle θ1 approximately equal to the wall angle γ, the user is less likely to mistakenly recognize interference when adjusting the position of the indexable rotary cutting tool 1 by bringing it close to the wall surface of the workpiece W.

[0042] In the shank 2 of this embodiment, the inclination angle θ1 of the first region 21 is preferably in the range of 6.0° ≧ θ1 ≧ 0.3°. This range allows for suitable cutting of wall angles in this range while ensuring rigidity. Furthermore, increasing θ1 allows for a correspondingly thicker shank diameter, enabling a design with higher rigidity. Taking into account the wall angle γ, it is preferable to set θ1 ≧ 0.5°.

[0043] The inclination angle θ2 of the second region 22 is preferably in the range of 60° ≧ θ2 ≧ 1.5°, and more preferably in the range of 60° ≧ θ2 ≧ 5.0°. Within this range, the shank can be easily manufactured while ensuring appropriate rigidity. Furthermore, if L2 becomes too small due to a tradeoff between θ1 and the shank diameter, reducing θ2 makes it easier to manage the shank processing, so it is preferable to set θ2 to 30° ≧ θ2.

[0044] Therefore, by setting the inclination angles θ1 and θ2 within the above ranges, the rigidity of the tapered portion 24 can be ensured while preventing the user from mistakenly recognizing that the tapered portion 24 is interfering with the wall of the workpiece, thereby reducing unnecessary confirmation work.

[0045] 3 is a side view of an indexable rotary cutting tool of a first modified example. The indexable rotary cutting tool 1 of the first modified example includes a shank 2A ​​and a modular head 4. In the following description, components common to the above embodiment are designated by the same reference numerals as in the above embodiment, and detailed description thereof will be omitted.

[0046] The shank 2A ​​includes a grip portion 20 and a tapered portion 24. The tapered portion 24 has a first region 21A extending from the tip of the grip portion 20 toward the tip side, and a second region 22A extending from the tip of the first region 21 toward the tip side. In a side view seen from a direction perpendicular to the rotation axis O, the first region 21A and the second region 22A both have outer peripheral surfaces that are convexly curved and protrude radially outward.

[0047] In the shank 2A ​​of the first modified example, the inclination angle θ1 of the first region 21A is also defined as the angle between the rotation axis O and the tangent N1 to the first region 21 at point P2. The inclination angle θ2 of the second region 22A is also defined as the angle between the rotation axis O and the tangent N2 to the second region 22 at point Q2. The inclination angle θ2 of the second region 22A is greater than the inclination angle θ1 of the first region 21A.

[0048] Even if the outer surfaces of the first region 21A and the second region 22A are convexly curved in side view, as in the shank 2A ​​of the first modified example, the effect of ensuring the rigidity of the tapered portion 24 while making it less likely for the user to mistakenly recognize interference with the wall of the workpiece can be obtained, as in the previous embodiment.

[0049] The outer peripheral surface of the first region 21A and the outer peripheral surface of the second region 22A may have a convex arc shape that protrudes radially outward in a side view seen from a direction perpendicular to the rotation axis O.

[0050] 4 is a side view of an indexable rotary cutting tool of a second modified example. The indexable rotary cutting tool 1 of the second modified example includes a shank 2B and a modular head 4. In the following description, components common to the above embodiment are designated by the same reference numerals as in the above embodiment, and detailed description thereof will be omitted.

[0051] The shank 2B includes a grip portion 20 and a tapered portion 24. The tapered portion 24 has a first region 21 extending from the tip of the grip portion 20 toward the tip side, a second region 22 extending from the tip of the first region 21 toward the tip side, and a tapered intermediate region 23 located between the first region 21 and the second region 22 and having an inclination angle θn different from those of the first region 21 and the second region 22.

[0052] As shown in Figure 4, in a side view, the rear end point of the intermediate region 23 is defined as point R1, and the front end point of the intermediate region 23 is defined as point R2. In this modified example, point R1 is the connection point between the intermediate region 23 and the first region 21, and point R2 is the connection point between the intermediate region 23 and the second region 22. The length of the intermediate region 23 in the direction of the rotation axis O is defined as the distance Ln between points R1 and R2 in the direction of the rotation axis O. In the shank 2B of the second modified example, the inclination angle θn of the intermediate region 23 is defined as the angle between the rotation axis O and a tangent Nn to the intermediate region 23 at point R2.

[0053] The point R2 or the area around it may be chamfered, preferably within a range of 1.0 mm to 0.2 mm in the direction of the rotation axis O.

[0054] In the shank 2B of the second modification, the distance Ln between the rear end point (point R1) and the tip end point (point R2) of the intermediate region 23 in the direction of the rotation axis O satisfies the relationship L1 > Ln with respect to the length (distance L1) of the first region 21. The inclination angle θn of the intermediate region 23 is the angle between the rotation axis O and a tangent Nn to the tip end point (point R2) of the intermediate region 23, and satisfies the relationship θ2 > θn > θ1 with respect to the inclination angle θ1 of the first region 21 and the inclination angle θ2 of the second region 22.

[0055] Even in a configuration that includes an intermediate region 23, like the shank 2B of the second modified example, the effect of ensuring the rigidity of the tapered portion 24 while making it less likely for the user to mistakenly recognize interference with the wall of the workpiece can be obtained, as in the previous embodiment.

[0056] Although the second modified example is configured with only one intermediate region 23, multiple intermediate regions 23 may be provided. Even when multiple intermediate regions 23 are provided, the inclination angle θn of each intermediate region 23 is an angle between θ1 and θ2. Furthermore, when multiple intermediate regions 23 are provided, the inclination angle θn of each intermediate region 23 is set to be larger the closer the intermediate region 23 is to the tip end of the shank 2B.

[0057] In the shank 2B of the second modified example, the first region 21, the second region 22, and the intermediate region 23 may have an outer peripheral surface that is convexly curved in a side view perpendicular to the rotation axis O.

[0058] In each of the above embodiments, the modular head 4 is configured such that the cutting insert 3 is held in the head body 41, but the modular head 4 may also be a solid-type modular head whose entire body is made of cemented carbide or the like.

[0059] In each of the above embodiments, the cutting insert 3 has two blades, but it may have one blade or three or more blades. A configuration in which multiple cutting inserts are attached to the modular head 4 may also be used. The indexable rotary cutting tool 1 may be a radius end mill or a square end mill.

[0060] <Rigidity Evaluation> Rigidity was evaluated in a simulation environment for the indexable rotary cutting tools of Examples 1 and 2 and Comparative Examples 1 to 3 shown in Table 1. Examples 1 and 2 are indexable rotary cutting tools having the configuration of the embodiment shown in Figures 1 and 2. Example 1 has a ratio L1 / L0 = 0.9, and Example 2 has a ratio L1 / L0 = 0.98. Comparative Example 1 is a conventional indexable rotary cutting tool with a uniformly tapered tapered portion. Comparative Example 2 is an indexable rotary cutting tool having the configuration of the embodiment, but with the second region longer than the first region (L1 < L2). Comparative Example 3 is a tool with a smaller shank diameter than Comparative Example 1, thereby reducing the inclination angle of the tapered portion.

[0061] Test method: Using the analysis function of NX Simcenter (analysis software manufactured by Siemens), the amount of tool deflection was evaluated when a force of 500 N was applied to the tool end face in the shear direction under the condition that the shank end face was fully restrained.

[0062] The test results are shown in Table 2. It was confirmed that the indexable rotary cutting tools of Examples 1 and 2, in which the tapered portion comprises a first region and a second region, the axial length of the first region (distance L1) is greater than the axial length of the second region (distance L2), and the inclination angle θ1 of the first region is smaller than the inclination angle θ2 of the second region, have smaller deflection and higher rigidity than the indexable rotary cutting tool of Comparative Example 1, which is a conventional example.

[0063] On the other hand, the indexable rotary cutting tool of Comparative Example 2, in which the tapered portion is two-staged but the second region at the front end is longer than the first region at the rear end, has a smaller amount of deflection than the indexable rotary cutting tool of Comparative Example 1, but the difference is small and the improvement in rigidity is insufficient.

[0064] It was confirmed that the indexable rotary cutting tool of Comparative Example 3, in which the inclination angle of the tapered portion was reduced by supplementing the shank itself, had a significantly increased amount of deflection and a significantly decreased rigidity compared to Comparative Example 1.

[0065]

[0066]

[0067] <Rough Cutting Region Cutting Evaluation> Cutting evaluation was performed in the rough cutting region using the indexable cutting tools of Example 3, Example 4, and Comparative Example 4. In the rough cutting evaluation, the axial depth of cut and the feed rate per blade were changed to evaluate the region in which stable cutting was possible. Examples 3 and 4 are indexable rotary cutting tools having the configuration of the embodiment shown in Figures 1 and 2, and have the following geometric dimensions. Example 3: θ1: 2.9°, θ2: 10°, L1: 93.7 mm, L2: 11.3 mm, Φ32 mm Example 4: θ1: 0.9°, θ2: 10°, L1: 144.5 mm, L2: 5.5 mm, Φ25 mm Comparative Example 4 is a conventional indexable rotary cutting tool (Comparative Example 1) with a uniformly tapered portion (straight under-neck shape, Φ20 mm).

[0068] The cutting conditions were as follows: Machine: HSK100 spindle machine, Workpiece: SKD61 equivalent (45HRC), Machining method: Contour machining including vertical wall with corner R of 11 mm (vertical wall angle 90°), Tool: Indexable tool for rough machining, Cutting conditions: Vc = 80 m / min, ae = 14 mm, air blow, Overhang 218 mm (L / D = 10.9)

[0069] The results are shown in Figure 7. With the indexable cutting tool of Comparative Example 4, chattering occurred when the axial depth of cut or the feed rate per blade was increased, making stable machining impossible and narrowing the region in which stable machining was possible. The indexable cutting tools of Examples 3 and 4 were provided with a tapered portion having a first region and a second region, and therefore had higher rigidity than the indexable cutting tool of Comparative Example 4, and were able to perform stable machining even when the axial depth of cut and the feed rate per blade were increased, widening the region in which stable machining was possible.

[0070] <Evaluation of Finishing Dimensional Accuracy> Cutting evaluation was performed using the indexable cutting tools of Example 5, Example 6, and Comparative Examples 5 and 6, and the finishing dimensional accuracy was evaluated. In the finishing evaluation, the axial cutting depth and the feed rate per blade were constant. Examples 5 and 6 are indexable rotary cutting tools having the configuration of the embodiment shown in Figures 1 and 2, and have the following geometric dimensions. Example 5 θ1: 2.9°, θ2: 10°, L1: 93.7 mm, L2: 11.3 mm (protrusion amount L / D = 11) Example 6 θ1: 0.9°, θ2: 10°, L1: 144.5 mm, L2: 5.5 mm (protrusion amount L / D = 11)

[0071] Comparative Examples 5 and 6 are conventional indexable rotary cutting tools in which the tapered portion has a uniform tapered shape (straight under-neck shape). In Comparative Example 5, the protrusion amount L / D was set to 8.5, and in Comparative Example 6, the protrusion amount L / D was set to 10.

[0072] The cutting conditions were as follows: Machine: HSK100 spindle machine, Workpiece: SKD61 equivalent (45HRC), Machining method: Contour vertical wall finishing (vertical wall angle 90°), Tool: Indexable cutting tool for finishing, Cutting conditions: Vc = 150 m / min, fz = 0.08 mm / t, ap = 1.0 mm, ae = 0.2 mm, Air blow

[0073] The results are shown in Figure 8. The indexable cutting tools of Examples 5 and 6 have a tapered portion having a first region and a second region, and therefore have higher rigidity than the indexable cutting tools of Comparative Examples 5 and 6, and can suppress the amount of deflection even when machining deep vertical walls. Therefore, even though the L / D ratio is larger than that of the comparative examples, the amount of uncut material can be reduced.

[0074] As the results of each example show, by providing a tapered section having a first region and a second region, this example allows the shank diameter to be increased, increasing rigidity and suppressing the amount of deflection when machining deep vertical walls. Furthermore, since the inclination angle θ1 can be set according to the vertical wall angle, even with an indexable rotary cutting tool, the wall angle of the workpiece and the taper angle of the shank can be made closer, making it less likely that the user will mistakenly recognize interference with the wall of the workpiece.

[0075] 1... indexable rotary cutting tool, 4... modular head, 20... gripping portion, 21, 21A... first region, 22, 22A... second region, 23... intermediate region, 24... tapered portion, 25... connecting portion, 31... cutting edge, L0, L1, L2, Ln... distance, N1, N2, Nn... tangent, O... rotation axis, P1, P2, Q1, Q2, R1, R2... points, θ1, θ2, θn... tilt angle

Claims

1. A tool body used in an indexable rotary cutting tool that rotates around a rotation axis O, the tool body being held by a tool holder at its rear end and connected to a modular head having a cutting edge at its front end, the tool body comprising: a columnar gripping portion; a tapered portion connected to the front end of the gripping portion and having a diameter that narrows toward the front end; and a connection portion located at the front end of the tapered portion and to which the modular head is connected; the tapered portion has a first region extending from the connection position with the gripping portion toward the front end, and a second region located closer to the front end than the first region; and when, in a side view, the connection point between the first region and the gripping portion is defined as point P1, the front end side end point of the first region is defined as point P2, the rear end side end point of the second region is defined as point Q1, and the front end side end point of the second region is defined as point Q2, the distance L1 between point P1 and point P2 in the direction of the rotation axis O is longer than the distance L2 between point Q1 and point Q2; A tool body in which, when the inclination angle θ1 of the first region is the angle between the rotation axis O and the tangent N1 of the first region at point P2, and the inclination angle θ2 of the second region is the angle between the rotation axis O and the tangent N2 of the second region at point Q2, the inclination angle θ2 is greater than the inclination angle θ1.

2. The tool body according to claim 1, wherein the distance L1 and the distance L0 between the point P1 and the point Q2 in the direction of the rotation axis O satisfy the relationship 0.98≧L1 / L0≧0.

50.

3. The tool body according to claim 1, wherein the inclination angle θ1 is in the range of 6.0° ≥ θ1 ≥ 0.3°, and the inclination angle θ2 is in the range of 60° ≥ θ2 ≥ 1.5°.

4. A tool body according to claim 1, wherein, in a side view seen from a direction perpendicular to the rotation axis O, the first region and the second region both have linear outer peripheral surfaces.

5. A tool body as described in claim 1, wherein, in a side view seen from a direction perpendicular to the rotation axis O, the first region and the second region both have a convex curved outer peripheral surface that protrudes radially outward.

6. A tool body according to claim 1, wherein the tapered portion has one or more tapered intermediate regions between the first region and the second region, the tapered intermediate region having an inclination angle θn different from those of the first region and the second region, the distance Ln between the rear end point of the intermediate region and the tip end point in the direction of the rotation axis O is L1 > Ln, and the inclination angle θn of the intermediate region is the angle between the rotation axis O and a tangent Nn to the tip end point of the intermediate region, and satisfies the relationship θ2 > θn > θ1.

7. An indexable rotary cutting tool that rotates around a rotation axis O, comprising: a modular head having a cutting edge; and a tool body that is held by a tool holder at its rear end and connected to the modular head at its front end; wherein the tool body has a columnar gripping portion, a tapered portion that is connected to the front end of the gripping portion and has a diameter that narrows toward the front end, and a connection portion that is located at the front end of the tapered portion and to which the modular head is connected; wherein the tapered portion has a first region that extends from the connection position with the gripping portion toward the front end, and a second region that is located closer to the front end than the first region; and when, in a side view, the connection point between the first region and the gripping portion is point P1, the front end side end point of the first region is point P2, the rear end side end point of the second region is point Q1, and the front end side end point of the second region is point Q2, the distance L1 between point P1 and point P2 in the direction of the rotation axis O is longer than the distance L2 between point Q1 and point Q2; An indexable rotary cutting tool, wherein an inclination angle θ1 of the first region is defined as an angle between a rotation axis O and a tangent N1 of the first region at a point P2, and an inclination angle θ2 of the second region is defined as an angle between the rotation axis O and a tangent N2 of the second region at a point Q2, and the inclination angle θ2 is greater than the inclination angle θ1.

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