Tool holders, replaceable tip cutting tools

Abstract

To provide a tool holder that can reduce a risk that a defective product is determined to be a non-defective product by mistake and is formed in consideration of operation ability of an operator.SOLUTION: A tool holder has a pocket part having a mounting seat formed at a tip portion thereof and comprises a columnar part formed closer to a rear end than the pocket part. When a virtual cylindrical surface including a circular surface constituting a side surface of the columnar part is defined in the columnar part, a first circular surface closest to the pocket part and a second cylindrical surface furthest away from the first cylindrical surface are arranged on the virtual cylindrical surface. A recessed part recessed toward inside in a radial direction more than the virtual cylindrical surface is arranged between the first cylindrical surface and the second cylindrical surface. A maximum width tmax in a direction of a rotation central shaft of a tool, of the recessed part is above or equal to 1.0 mm, and the first cylindrical surface and the second cylindrical surface are cylindrical grinding surfaces formed coaxially with the rotation central shaft of the tool.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a tool holder and an insert-exchangeable cutting tool.

Background Art

[0002] An insert-exchangeable cutting tool is composed of a cutting insert, a tool holder, and a fastening member such as a screw for attaching the cutting insert to the tool holder. It has been found that the shape accuracy of each member affects the surface quality and dimensional accuracy of the machined surface. In recent years, there has been a tendency to improve not only the shape accuracy of the cutting insert but also the shape accuracy of the tool holder. For example, on page 2 of Non-Patent Document 1, it is disclosed that a high-precision tool is provided by a high-precision chip and a tool holder. Furthermore, in Non-Patent Document 2, an improvement effect on the balance due to the high-precision of the tool holder is boasted.

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] Typically, tool holders are manufactured by machining the desired contour shape and reference surface using a lathe or cylindrical grinding process, and then machining the pocket portion for fastening the insert using a machining center. For measuring the shape of the tool holder, such as the cutting diameter, the tool holder is removed after machining and attached to a jig appropriate for the measuring machine. While the dimensional accuracy of the jig is controlled by high fit precision during manufacturing, there is a slight dimensional difference between the jig used during manufacturing and the jig used during measurement. This results in differences in the reference surface and reference axis between manufacturing and measurement, causing misalignment. This misalignment affects the measurement results of the tool cutting diameter and runout, leading to errors between the measured dimensions and the actual shape. While this error is small and not a problem for tool holders of normal precision, it becomes a significant disturbance in the manufacturing of high-precision tool holders.

[0005] In recent years, shape measuring machines (tool presetters) used for measuring and evaluating the shape of tool holders have been equipped with a function called axis correction. This axis correction function can detect the central axis as a straight line connecting the arc centers of two coaxially machined cylindrical surfaces located at different positions. It is known that by using this axis correction function, disturbances caused by changing measuring machines or jigs can be eliminated, and the tool's central axis can be detected. As a result, even if there is a dimensional difference between the jig used during manufacturing and the jig used during measurement, the measurement results are not affected, and the dimensional accuracy of the tool holder itself can be evaluated.

[0006] According to the inventors' research, when detecting the tool's central axis using this axis correction function, a problem arises in that the positional relationship between two precisely machined cylindrical surfaces affects the accuracy of tool central axis detection. For example, if there is variation in how the two cylindrical surfaces are machined by different workers manufacturing the tool holder, the accuracy of tool central axis detection will decrease. If the shape of the tool holder is measured based on a tool central axis with low detection accuracy, even if the tool holder itself is measured, a tool holder that is finished with good accuracy may be judged as defective, or a tool holder that is outside the tolerance may be judged as good, which can lead to serious quality control problems.

[0007] Furthermore, the inclusion of two precisely machined cylindrical surfaces in the tool holder presents new challenges. While the tool holder is carried by its cylindrical outer circumference, if the cylindrical surfaces are ground to achieve precision, these ground surfaces are more precisely machined than the lathe-machined surfaces, resulting in a slippery surface texture when held. Therefore, more careful handling is required when attaching or detaching cutting tools from the machine tool spindle.

[0008] Therefore, in view of the above-mentioned problems, one of the objectives of the present invention is to provide a tool holder that has a shape that can stably improve the detection accuracy of the central axis of the axis correction function by a shape measuring machine (tool presetter), thereby reducing the risk of defective products being mistakenly identified as good products, enabling the stable manufacture of high-precision tool holders, and also having a shape that takes into consideration the operability of the operator. [Means for solving the problem]

[0009] (1) A substantially cylindrical tool holder having a tool rotation axis, the tip of the tool holder having a pocket portion equipped with a mounting seat for attaching a cutting insert, and a cylindrical portion located at the rear end of the pocket portion. When a virtual cylindrical surface is defined in the cylindrical portion, including the cylindrical surface constituting the side surface of the cylindrical portion, with respect to the tool rotation axis, the virtual cylindrical surface has a first cylindrical surface closest to the pocket portion in the direction of the tool rotation axis, and a second cylindrical surface having a diameter substantially equal to that of the first cylindrical surface and furthest from the first cylindrical surface in the direction of the tool rotation axis. A recess is provided between the first cylindrical surface and the second cylindrical surface, recessed radially inward from the virtual cylindrical surface. The maximum width tmax of the recess in the direction of the tool rotation axis is 1.0 mm or more. The first cylindrical surface and the second cylindrical surface are cylindrical grinding surfaces formed coaxially with the tool rotation axis.

[0010] (2) In (1), the maximum height roughness Rz of the first cylindrical surface and the second cylindrical surface may be configured to satisfy 0.4 μm ≤ Rz ≤ 6.3 μm.

[0011] (3) In (1) or (2), the recess may be formed in a range of at least 50% of the circumference of the virtual cylindrical surface.

[0012] (4) In any one of (1) to (3), the maximum distance of the pocket portion in the direction of the tool rotation center axis is L, and the maximum distance between the leading end of the first cylindrical surface and the rear end of the second cylindrical surface is H, such that 0.5 ≤ H / L ≤ 2.0.

[0013] (5) In any one of (1) to (4), when the minimum width of the first cylindrical surface in the direction of the tool rotation center axis is h1 and the minimum width of the second cylindrical surface is h2, both h1 and h2 are 0.5 mm or more, and the relationship 0.5 ≤ h1 / h2 ≤ 2.0 may be satisfied.

[0014] (6) In any one of (1) to (5), the tool holder may have a portion that has been subjected to one or more surface treatments from plating, blackening, PVD coating, and CVD coating.

[0015] (7) In any one of (1) to (6), the tool holder may be configured without any surface treatment among plating, blackening, PVD coating, or CVD coating.

[0016] (8) The replaceable cutting tool of the present invention comprises a tool holder according to any one of (1) to (7) and a cutting insert mounted on the mounting seat.

[0017] In (9)(8), a configuration that satisfies the following conditions may be used: the front runout and radial runout are 50 μm or less, and the blade diameter accuracy is 90 μm or less. [Effects of the Invention]

[0018] According to one aspect of the present invention, by adopting a shape that can stably improve the detection accuracy of the central axis of the axis correction function by a shape measuring machine (tool presetter), the risk of misjudging defective products as non-defective products is reduced, high-precision tool holders can be stably manufactured, and a tool holder is provided that has a shape considering the operability of the operator.

Brief Description of the Drawings

[0019] [Figure 1] FIG. 1 is a perspective view of a tool holder according to the first embodiment. [Figure 2] FIG. 2 is a side view of a tool holder according to the first embodiment. [Figure 3] FIG. 3 is a front view of a tool holder according to the first embodiment. [Figure 4] FIG. 4 is a perspective view of an insert-exchangeable cutting tool with a cutting insert mounted on a tool holder according to the first embodiment. [Figure 5] FIG. 5 is a perspective view of a tool holder according to the second embodiment. [Figure 6] FIG. 6 is a side view of a tool holder according to the second embodiment. [Figure 7] FIG. 7 is a front view of a tool holder according to the second embodiment. [Figure 8] FIG. 8 is a perspective view of an insert-exchangeable cutting tool with a cutting insert mounted on a tool holder according to the second embodiment.

Modes for Carrying Out the Invention

[0020] (First Embodiment) FIG. 1 is a perspective view of a tool holder according to the first embodiment. FIG. 2 is a side view of a tool holder according to the first embodiment. FIG. 3 is a front view of a tool holder according to the first embodiment. FIG. 4 is a perspective view of an insert-exchangeable cutting tool with a cutting insert mounted on a tool holder according to the first embodiment. The tool holder in this embodiment is a high-precision machined tool holder, and the indexable cutting tool in this embodiment using this tool holder is also a high-precision cutting tool. The indexable cutting tool in this embodiment satisfies, for example, a front runout and radial runout of 50 μm or less, and a cutting edge diameter accuracy of 90 μm or less.

[0021] As shown in Figures 1 to 3, the tool holder 10 of this embodiment is a substantially cylindrical tool holder having a tool rotation axis J0. The tool holder 10 has a tip portion 30 aligned along the tool rotation axis J0, a cylindrical portion 20, and a shank connection portion 40.

[0022] In the following explanation, the direction from the shank connection portion 40 toward the tip portion 30 along the axial direction of the tool rotation center axis J0 of the tool holder 10 is referred to as the tip side, and the direction from the tip portion 30 toward the shank connection portion 40 is referred to as the rear end side. The direction parallel to the tool rotation center axis J0 is sometimes simply referred to as the axial direction. The direction perpendicular to the tool rotation center axis J0 of the tool holder 10 is referred to as the radial direction, and the direction that revolves around the tool rotation center axis J0 is referred to as the circumferential direction.

[0023] The tool holder 10 has a pocket portion 35 at its tip portion 30, which is equipped with a mounting seat 33 for attaching a cutting insert 1 (see Figure 4). The cylindrical portion 20 extends from the rear end of the tip portion 30 toward the rear end. The shank connection portion 40 extends from the rear end of the cylindrical portion 20 toward the rear end.

[0024] The shank connection portion 40 is the part that connects the tool holder 10 to a shank (not shown). The shank connection portion 40 extends from the rear end face of the cylindrical portion 20 toward the rear end. The shank connection portion 40 is substantially cylindrical with respect to the tool rotation axis J0. The shank connection portion 40 has a smaller diameter than the cylindrical portion 20. The shank connection portion 40 has cylindrical surfaces 42 and a fitting portion 41 arranged in order from the side of the cylindrical portion 20.

[0025] The fitting portion 41 has a surface with a male thread portion on a cylinder centered on the tool rotation axis J0. The fitting portion 41 fits into the fitting portion (female thread portion) of the shank (not shown). The cylindrical surface 42 is located between the fitting portion 41 and the cylindrical portion 20. The cylindrical surface 42 is a cylindrical surface coaxial with the tool rotation axis J0. The cylindrical surface 42 fits into jigs used during manufacturing or measurement (not shown) to position each jig and the tool holder 10 relative to each other.

[0026] In this embodiment, six mounting seats 33 and pockets 35 are provided on the tip portion 30. The number of mounting seats 33 and pockets 35 can be increased or decreased depending on the tool diameter of the replaceable-tip rotary cutting tool 11 shown in Figure 4, the required performance, etc. For example, if the tool diameter is small, there may be five or fewer mounting seats 33 and pockets 35, and if the tool diameter is large, there may be seven or more mounting seats 33 and pockets.

[0027] As shown in Figure 3, the pocket portion 35 is a recess that extends radially inward from the outer peripheral surface 31 of the tip portion 30. A mounting seat 33 is formed on the inner wall surface of each pocket portion 35 that faces forward in the tool rotation direction TD. In this embodiment, the six mounting seats 33 are arranged at equal intervals of 60° in the circumferential direction of the tool holder 10. Alternatively, the six mounting seats 33 may be arranged at unequal intervals in an unequal division configuration.

[0028] The mounting seat 33 has a mounting seat bottom surface 33a and a pair of mounting seat wall surfaces 33b. The mounting seat bottom surface 33a is rectangular in shape with an area approximately equal to that of the seating surface 3 of the cutting insert 1. The mounting seat bottom surface 33a faces the tool rotation direction TD of the tool holder 10. The pair of mounting seat wall surfaces 33b are surfaces that extend from two sides of the mounting seat bottom surface 33a toward the tool rotation direction TD.

[0029] The mounting base surface 33a is the surface that supports the bottom surface of the cutting insert 1. Of the pair of mounting base wall surfaces 33b, the mounting base wall surface 33b that extends along the axial direction supports the side surface of the cutting insert 1 along the long side. Of the pair of mounting base wall surfaces 33b, the mounting base wall surface 33b that extends along the radial direction supports the side surface of the cutting insert 1 along the short side. The pair of mounting base wall surfaces 33b support the relief surface of the cutting insert 1.

[0030] A screw hole 33c is formed approximately in the center of the mounting base surface 33a. The screw hole 33c is a hole that can communicate with a mounting hole 7 formed in the center of the cutting insert 1. A mounting screw (not shown) is inserted into the screw hole 33c when attaching the cutting insert 1. The cutting insert 1 is attached to the tool holder 10 by tightening the mounting screw, which is inserted into the mounting hole 7 formed in the center of the cutting insert 1, into the screw hole 33c formed in the center of the mounting base surface 33a of the tool holder 10.

[0031] The tool holder 10 includes a cylindrical portion 20 located at the rear end of the multiple pocket portions 35. The side surface of the cylindrical portion 20 includes a cylindrical grinding surface centered on the tool rotation axis J0. Here, as shown in Figure 2, a virtual cylindrical surface 20v is defined, which includes the cylindrical surface of the side of the cylindrical portion 20. On the virtual cylindrical surface 20v, at least a first cylindrical surface 21 is located closest to the pocket portion 35 in the direction of the tool rotation center axis, and a second cylindrical surface 22 is located in the direction of the tool rotation center axis, with a diameter approximately equal to that of the first cylindrical surface 21 and furthest from the first cylindrical surface 21. Between the first cylindrical surface 21 and the second cylindrical surface 22, a recess 23 is located, which is recessed radially inward from the first cylindrical surface 21 and the second cylindrical surface 22.

[0032] In other words, the cylindrical portion 20 has a region on its side surface consisting of a cylindrical grinding surface centered on the tool rotation axis J0, and this cylindrical grinding surface is divided into a first cylindrical surface 21 and a second cylindrical surface 22 by a recess 23 in the direction of the tool rotation axis.

[0033] In this embodiment, the recess 23 includes a groove 23a extending in the circumferential direction and a rectangular D-cut portion 23b in side view. The groove 23a extends in the circumferential direction in a plane perpendicular to the tool rotation center axis J0. Both ends of the groove 23a are connected to the circumferential edges of the D-cut portion 23b, respectively. The recess 23 extends around the entire circumference of the cylindrical portion 20. The number of grooves 23a can be increased depending on the size of the tool holder, etc. For example, if the tool diameter is large, there may be two or more grooves 23a.

[0034] The recess 23 has a maximum width tmax of 1.0 mm or more in the direction of the tool rotation center axis. In this embodiment, the maximum width tmax is the maximum width of the D-cut portion 23b in the direction of the tool center axis, as shown in Figure 2. The recess 23 may consist only of the groove portion 23a, in which case the maximum width tmax is the width of the groove portion 23a. By having a maximum width tmax of 1.0 mm or more, the first cylindrical surface 21 and the second cylindrical surface 22 can be easily separated by visibility, and the recess functions sufficiently as an anti-slip surface when handling the tool holder 10. More preferably, the radial depth D of the recess 23 is 0.3 mm or more, and by providing a recess of a certain depth or more in directions other than the direction of the tool rotation center axis, visibility and anti-slip effect during handling are improved.

[0035] The first cylindrical surface 21 is a cylindrical grinding surface located towards the tip of the recess 23. In this embodiment, a portion of the first cylindrical surface 21 is located towards the tip of the D-cut portion 23b. The first cylindrical surface 21 narrows in width at a position adjacent to the D-cut portion 23b in the axial direction, but extends around the entire circumference of the cylindrical portion 20. Even when there are multiple grooves 23a in the recess 23, the cylindrical grinding surface located towards the tip of the outermost recess 23 is considered the first cylindrical surface 21. Therefore, when there are multiple grooves 23a, the cylindrical surface sandwiched between each groove 23a is not the first cylindrical surface 21.

[0036] The second cylindrical surface 22 is a cylindrical grinding surface located further back than the recess 23. In this embodiment, a portion of the second cylindrical surface 22 is located on the rear end side of the D-cut portion 23b. The second cylindrical surface 22 narrows in width at a position adjacent to the D-cut portion 23b in the axial direction, but extends around the entire circumference of the cylindrical portion 20. Even when there are multiple grooves 23a in the recess 23, the cylindrical grinding surface located further back than the rearmost recess 23 is considered the second cylindrical surface 22. Therefore, when there are multiple grooves 23a, the cylindrical surface sandwiched between each groove 23a is not the second cylindrical surface 22.

[0037] Preferably, the first cylindrical surface 21 and the second cylindrical surface 22 are manufactured by first forming a single cylindrical surface that is elongated in the axial direction of the tool holder, and then providing a recess 23 in this cylindrical surface. Since the diameters of the first cylindrical surface 21 and the second cylindrical surface 22 are approximately equal, the coaxiality is more stable compared to the case where the diameters of the first cylindrical surface 21 and the second cylindrical surface 22 are different, and the accuracy of tool center axis detection by the axis correction function can be stably improved.

[0038] According to the tool holder 10 of this embodiment, which has the above configuration, the cylindrical portion 20 has a first cylindrical surface 21 and a second cylindrical surface 22 that are axially partitioned by a recess 23. As a result, the central axis can be detected by the axis correction function of a shape measuring machine (tool presetter) using the first cylindrical surface 21 and the second cylindrical surface 22, respectively. This makes it possible to eliminate disturbances caused by changing measuring machines and jigs and to evaluate the dimensional accuracy of the tool holder 10 alone. As a result of enabling high-precision measurement, it becomes possible to manufacture a high-precision tool holder 10.

[0039] In the tool holder 10 of this embodiment, a recess 23 is positioned between the first cylindrical surface 21 and the second cylindrical surface 22, allowing the operator of the shape measuring machine (tool presetter) to easily recognize the cylindrical grinding surface to be measured. If the operator of the shape measuring machine (tool presetter) mistakenly measures the first cylindrical surface 21 twice, the central axis detection will be performed based on the measurement results of positions close together in the axial direction, resulting in low detection accuracy of the tool's central axis. If shape measurement is performed based on a tool's central axis with low detection accuracy, a tool holder that has been completed with good accuracy may be judged as defective, or a tool holder that is outside the tolerance may be judged as good. In contrast, in this embodiment, the operator can be reliably identified by the recesses as the first cylindrical surface 21 and the second cylindrical surface 22 to be measured. By measuring the first cylindrical surface 21 and the second cylindrical surface 22, which are spaced apart from each other in the direction of the tool rotation center axis J0, the accuracy of center axis detection is improved. This makes it possible to stabilize the accuracy judgment of the tool holder 10.

[0040] Furthermore, when attaching and detaching the tool holder 10, the user primarily grips the cylindrical portion 20. The first cylindrical surface 21 and the second cylindrical surface 22, which are cylindrical grinding surfaces, are smooth curved surfaces and therefore tend to slip when held in the hand. This slipperiness is especially pronounced when cutting oil is present on the cylindrical portion 20. In contrast, the tool holder 10 of this embodiment is provided with a recess 23, which allows the user to hook their fingers into the recess 23 when holding the tool holder 10. This enables the user to operate the tool holder 10 safely and smoothly.

[0041] As described above, according to this embodiment, by providing a shape that can stably improve the detection accuracy of the central axis of the axis correction function by the shape measuring machine (tool presetter), the risk of defective products being mistakenly identified as good products is reduced, and a tool holder 10 that can be manufactured with high precision stably is provided, while also having a shape that takes into consideration the operability of the operator.

[0042] In this embodiment, it is preferable that the maximum height roughness Rz of the first cylindrical surface 21 and the second cylindrical surface 22 satisfy the condition 0.4 μm ≤ Rz ≤ 6.3 μm. By setting the maximum height roughness Rz within the above range, high-precision central axis detection can be performed by the shape measuring machine (tool presetter). If the maximum height roughness Rz is less than 0.4 μm, the grinding time of the cylindrical portion 20 will be longer, reducing manufacturing efficiency and increasing manufacturing costs. If the maximum height roughness Rz exceeds 6.3 μm, the circumference is more likely to be misrecognized due to surface roughness when using the axis correction function of the shape measuring machine (tool presetter). As a result, the accuracy of central axis detection may decrease.

[0043] In this embodiment, in the direction of the tool rotation center axis J0, as shown in Figure 2, when L is the maximum distance which is the axial length of the pocket portion 35 and H is the maximum distance between the leading end of the first cylindrical surface 21 and the rear end of the second cylindrical surface 22, it is preferable that the relationship 0.5 ≤ H / L ≤ 2.0 is satisfied. With this configuration, the axial length of the cylindrical portion 20 relative to the entire tool holder 10 can be secured. This makes it easier to secure a large distance between the first cylindrical surface 21 and the second cylindrical surface 22 in the direction of the tool rotation center axis J0. The accuracy of center axis detection by the axis correction function of the shape measuring machine (tool presetter) is improved.

[0044] In this embodiment, when the minimum width of the first cylindrical surface 21 in the direction of the tool rotation axis J0 is h1 and the minimum width of the second cylindrical surface 22 is h2, it is preferable that both h1 and h2 are 0.5 mm or more and that the relationship 0.5 ≤ h1 / h2 ≤ 2.0 is satisfied. In this embodiment, the first cylindrical surface 21 and the second cylindrical surface 22 have their minimum width at positions adjacent to the D-cut portion 23b in the axial direction. Preferably, the minimum widths h1 and h2 at these positions are 0.5 mm or more, and the ratio of the minimum widths h1 and h2 is within the range of 0.5 to 2.0. With this configuration, a sufficient measurement area can be secured for the shape measuring machine (tool presetter) on both the first cylindrical surface 21 and the second cylindrical surface 22, enabling efficient and stable detection of the central axis.

[0045] The first cylindrical surface 21 and the second cylindrical surface 22 do not need to extend over the entire circumference of the cylindrical portion 20, as long as the accuracy of central axis detection by the shape measuring machine (tool presetter) can be ensured. For example, the first cylindrical surface 21 or the second cylindrical surface 22 may be interrupted by the D-cut portion 23b. For example, if the cylindrical grinding surface is 70% or more of the circumferential length of the cylindrical portion 20, central axis detection by the shape measuring machine (tool presetter) is possible. The required circumferential length of the cylindrical grinding surface may vary depending on the model of the shape measuring machine (tool presetter).

[0046] In this embodiment, the recess 23 extends around the entire circumference of the cylindrical portion 20, but the recess 23 may be interrupted in the circumferential direction of the cylindrical portion 20. Alternatively, the recess 23 may be divided into two or more parts in the circumferential direction. If the recess 23 is formed only on a part of the circumferential direction of the cylindrical portion 20, it is preferable that the total circumferential length of the recess 23 is 50% or more of the circumferential length of the virtual cylindrical surface 20v. This allows the user of the tool holder 10 to see at least a part of the recess 23 from any direction, and makes it easier for the user to touch the recess 23 when holding the tool holder 10. This provides both the function of axially dividing the first cylindrical surface 21 and the second cylindrical surface 22, and the function of preventing slippage when handling the tool holder 10.

[0047] The tool holder 10 in this embodiment may be a tool holder that has undergone surface treatment. That is, the tool holder 10 may have a configuration in which one or more of the following surface treatments have been applied: plating, blackening, PVD coating, and CVD coating. Furthermore, the tool holder 10 in this embodiment may be a tool holder that has not undergone any surface treatment. That is, the tool holder 10 may be configured without any surface treatment among plating, blackening, PVD coating, or CVD coating.

[0048] (Second Embodiment) Figure 5 is a perspective view of the tool holder of the second embodiment. Figure 6 is a side view of the tool holder of the second embodiment. Figure 7 is a front view of the tool holder of the second embodiment. Figure 8 is a perspective view of an indexable cutting tool with a cutting insert mounted on the tool holder of the second embodiment. The tool holder in this embodiment is a high-precision machined tool holder, and the indexable cutting tool in this embodiment using this tool holder is also a high-precision cutting tool. The indexable cutting tool in this embodiment satisfies, for example, a front runout and radial runout of 50 μm or less, and a cutting edge diameter accuracy of 90 μm or less.

[0049] As shown in Figures 5 to 7, the tool holder 10A of this embodiment is a substantially cylindrical tool holder having a tool rotation axis J0. The tool holder 10A has a tip portion 30 and a cylindrical portion 20 that are aligned along the tool rotation axis J0.

[0050] In the second embodiment, parts equivalent to those in the first embodiment are denoted by the same reference numerals as in the first embodiment, and detailed descriptions may be omitted. In the second embodiment, the direction from the cylindrical portion 20 toward the tip portion 30 along the axial direction of the tool rotation center axis J0 of the tool holder 10A is referred to as the tip side, and the direction from the tip portion 30 toward the cylindrical portion 20 is referred to as the rear end side.

[0051] The tool holder 10A has a pocket portion 35 at its tip portion 30, which is equipped with a mounting seat 33 for attaching a cutting insert 1 (see Figure 8). The cylindrical portion 20 extends from the rear end to the rear end of the tip portion 30.

[0052] In this embodiment, seven mounting seats 33 and pockets 35 are provided on the tip portion 30. The number of mounting seats 33 and pockets 35 can be increased or decreased. The pockets 35 are recesses that extend radially inward from the outer peripheral surface 31 of the tip portion 30. A mounting seat 33 is formed on the inner wall surface of each pocket 35 that faces forward in the tool rotation direction TD. In this embodiment, the seven mounting seats 33 are arranged at angular intervals of 51° to 52° in the circumferential direction of the tool holder 10A.

[0053] The mounting base 33 has a mounting base bottom surface 33a and a pair of mounting base wall surfaces 33b. A screw hole 33c is formed approximately in the center of the mounting base bottom surface 33a. As shown in Figure 8, the cutting insert 1 is attached to the tool holder 10A by tightening a mounting screw (not shown) inserted into a mounting hole 7 formed in the center of the cutting insert 1 into the screw hole 33c formed in the center of the mounting base bottom surface 33a of the tool holder 10A.

[0054] The tool holder 10A has a cylindrical portion 20 located at the rear end of the multiple pocket portions 35. The side surface of the cylindrical portion 20 includes a cylindrical grinding surface centered on the tool rotation axis J0. In this embodiment, a keyway 25 is formed at the rear end of the cylindrical portion 20, recessed from the rear end surface of the tool holder 10A toward the front end. The keyway 25 extends diametrically on the rear end surface of the tool holder 10A. The key of the spindle is fitted into the keyway 25 when the tool holder 10A is attached to the spindle of the machining center.

[0055] Here, as shown in Figure 6, a virtual cylindrical surface 20v is defined, which includes the cylindrical surface of the side of the cylindrical portion 20. On the virtual cylindrical surface 20v, at least a first cylindrical surface 21 is located closest to the pocket portion 35 in the direction of the tool rotation center axis, and a second cylindrical surface 22 is located in the direction of the tool rotation center axis, with a diameter approximately equal to that of the first cylindrical surface 21 and furthest from the first cylindrical surface 21. Between the first cylindrical surface 21 and the second cylindrical surface 22, a recess 23 is located, which is recessed radially inward from the first cylindrical surface 21 and the second cylindrical surface 22.

[0056] In this embodiment, the recess 23 consists of a groove extending in the circumferential direction. The recess 23, consisting of the groove, extends in the circumferential direction in a plane perpendicular to the tool rotation axis J0. The recess 23 has a maximum width tmax of 1.0 mm or more in the direction of the tool rotation axis. In this embodiment, the maximum width tmax is the width of the groove. The maximum width tmax of 1.0 mm or more allows the first cylindrical surface 21 and the second cylindrical surface 22 to be easily visible and the recess functions sufficiently as an anti-slip surface when handling the tool holder 10A. More preferably, the radial depth D of the recess 23 is 0.3 mm or more, and by providing a certain level of recess in directions other than the direction of the tool rotation axis, visibility and anti-slip effect during handling are improved.

[0057] The first cylindrical surface 21 is a cylindrical grinding surface located towards the tip of the recess 23. In this embodiment, the first cylindrical surface 21 extends with a constant width around the entire circumference of the cylindrical portion 20. The second cylindrical surface 22 is a cylindrical grinding surface located on the rear end side of the recess 23. In this embodiment, the second cylindrical surface 22 narrows in width at a position adjacent to the keyway 25 in the axial direction, but extends around the entire circumference of the cylindrical portion 20.

[0058] The number of recesses 23 can be increased depending on the size of the tool holder, etc. For example, if the tool diameter is large, there may be two or more recesses 23. Even when there are multiple recesses 23, the cylindrical grinding surface located closer to the tip than the furthest tip recess 23 is defined as the first cylindrical surface 21. Therefore, when there are multiple recesses 23, the cylindrical surface sandwiched between each recess 23 is not the first cylindrical surface 21. Even when there are multiple recesses 23, the cylindrical grinding surface located further to the rear than the rearmost recess 23 is defined as the second cylindrical surface 22. Therefore, when there are multiple recesses 23, the cylindrical surface sandwiched between each recess 23 is not the second cylindrical surface 22.

[0059] Preferably, the first cylindrical surface 21 and the second cylindrical surface 22 are manufactured by first forming a single cylindrical surface that is elongated in the axial direction of the tool holder, and then providing a recess 23 in this cylindrical surface. Since the diameters of the first cylindrical surface 21 and the second cylindrical surface 22 are approximately equal, the coaxiality is more stable compared to the case where the diameters of the first cylindrical surface 21 and the second cylindrical surface 22 are different, and the accuracy of tool center axis detection by the axis correction function can be stably improved.

[0060] According to the tool holder 10A of this embodiment, which has the above configuration, the cylindrical portion 20 has a first cylindrical surface 21 and a second cylindrical surface 22 that are axially partitioned by a recess 23. As a result, the central axis can be detected by the axis correction function of a shape measuring machine (tool presetter) using the first cylindrical surface 21 and the second cylindrical surface 22, respectively. This makes it possible to exclude disturbances caused by changing measuring machines and jigs and to evaluate the dimensional accuracy of the tool holder 10A itself. As a result of enabling high-precision measurement, it becomes possible to manufacture a high-precision tool holder 10A.

[0061] In the tool holder 10A, a recess 23 is positioned between the first cylindrical surface 21 and the second cylindrical surface 22, allowing the operator of the shape measuring machine (tool presetter) to easily recognize the cylindrical grinding surface to be measured. By measuring the first cylindrical surface 21 and the second cylindrical surface 22, which are positioned apart from each other in the direction of the tool rotation center axis J0, the accuracy of center axis detection is improved. This stabilizes the accuracy judgment of the tool holder 10A.

[0062] The first cylindrical surface 21 and the second cylindrical surface 22, which are cylindrical grinding surfaces, are smooth curved surfaces and therefore tend to slip when held in the hand. In the tool holder 10A of this embodiment, a recess 23 is provided in the cylindrical portion 20, so that the user can hook their fingers into the recess 23 when holding the tool holder 10A in their hand. This allows the user to operate the tool holder 10A safely and smoothly.

[0063] As described above, according to this embodiment, the shape is designed to stably improve the detection accuracy of the central axis of the axis correction function by the shape measuring machine (tool presetter), thereby reducing the risk of defective products being mistakenly identified as good products, and providing a tool holder 10A with a shape that takes into consideration the operability of the operator.

[0064] In this embodiment, it is preferable that the maximum height roughness Rz of the first cylindrical surface 21 and the second cylindrical surface 22 satisfy the condition 0.4 μm ≤ Rz ≤ 6.3 μm. By setting the maximum height roughness Rz within the above range, the central axis can be detected with high accuracy by a shape measuring machine (tool presetter).

[0065] In this embodiment, in the direction of the tool rotation center axis J0, as shown in Figure 6, when L is the maximum distance which is the axial length of the pocket portion 35 and H is the maximum distance between the leading end of the first cylindrical surface 21 and the rear end of the second cylindrical surface 22, it is preferable that the relationship 0.5 ≤ H / L ≤ 2.0 is satisfied. With this configuration, the axial length of the cylindrical portion 20 relative to the entire tool holder 10A can be secured. This makes it easier to secure a large distance between the first cylindrical surface 21 and the second cylindrical surface 22 in the direction of the tool rotation center axis J0. The accuracy of center axis detection by the axis correction function of the shape measuring machine (tool presetter) is improved.

[0066] In this embodiment, when the minimum width of the first cylindrical surface 21 in the direction of the tool rotation axis J0 is h1 and the minimum width of the second cylindrical surface 22 is h2, it is preferable that both h1 and h2 are 0.5 mm or more and that the relationship 0.5 ≤ h1 / h2 ≤ 2.0 is satisfied. In this embodiment, the first cylindrical surface 21 has a constant width, while the second cylindrical surface 22 has its minimum width at a position adjacent to the keyway 25 in the axial direction. It is preferable that the minimum widths h1 and h2 at these positions are 0.5 mm or more, and that the ratio of the minimum widths h1 and h2 is within the range of 0.5 to 2.0. With this configuration, a sufficient measurement area can be secured for the shape measuring machine (tool presetter) on both the first cylindrical surface 21 and the second cylindrical surface 22, enabling efficient and stable detection of the central axis.

[0067] In this embodiment as well, the first cylindrical surface 21 and the second cylindrical surface 22 do not need to extend around the entire circumference of the cylindrical portion 20, as long as the accuracy of central axis detection by the shape measuring machine (tool presetter) can be ensured.

[0068] In this embodiment as well, the recess 23 may be interrupted in the circumferential direction of the cylindrical portion 20. Alternatively, the recess 23 may be divided into two or more parts in the circumferential direction. If the recess 23 is formed only on a part of the circumferential direction of the cylindrical portion 20, it is preferable that the total circumferential length of the recess 23 is 50% or more of the circumferential length of the virtual cylindrical surface 20v. This allows the user of the tool holder 10A to see at least a part of the recess 23 from any direction, and makes it easier for the user to touch the recess 23 when holding the tool holder 10A. This provides both the function of axially dividing the first cylindrical surface 21 and the second cylindrical surface 22, and the function of preventing slippage when handling the tool holder 10A.

[0069] The tool holder 10A in this embodiment may be a tool holder that has undergone surface treatment. That is, the tool holder 10A may have a configuration in which one or more of the following surface treatments have been applied: plating, blackening, PVD coating, and CVD coating. Furthermore, the tool holder 10A in this embodiment may be a tool holder that has not undergone any surface treatment. That is, the tool holder 10A may be configured without any surface treatment among plating, blackening, PVD coating, or CVD coating. [Explanation of Symbols]

[0070] 1…Cutting insert, 10,10A…Tool holder, 20…Cylindrical part, 20v…Virtual cylindrical surface, 21…First cylindrical surface, 22…Second cylindrical surface, 23…Recess, 30…Tip, 33…Mounting seat, 35…Pocket, h1,h2…Minimum width, J0…Tool rotation axis, Rz…Roughness, tmax…Maximum width

Claims

1. A substantially cylindrical tool holder having a central axis of rotation for the tool, The tip of the tool holder has a pocket portion equipped with a mounting seat for attaching a cutting insert. The cylindrical portion is provided on the rear end side of the aforementioned pocket portion. In the cylindrical portion, when a virtual cylindrical surface is defined that includes the cylindrical surface constituting the side surface of the cylindrical portion and is centered on the tool rotation axis, On the aforementioned virtual cylindrical surface, In the axial direction of the tool rotation center, the first cylindrical surface closest to the pocket portion, In the axial direction of the tool rotation center, the second cylindrical surface has a diameter approximately equal to that of the first cylindrical surface and is furthest from the first cylindrical surface, It was placed, Between the first cylindrical surface and the second cylindrical surface, a recess is provided that is recessed radially inward from the virtual cylindrical surface. The recess has a maximum width tmax in the axial direction of the tool rotation center of the recess of 1.0 mm or more. The first cylindrical surface and the second cylindrical surface are cylindrical grinding surfaces formed coaxially with the tool rotation center axis, A tool holder in which, when the minimum width of the first cylindrical surface in the axial direction of the tool rotation center is h1 and the minimum width of the second cylindrical surface is h2, both h1 and h2 are 0.5 mm or more, and the relationship 0.5 ≤ h1 / h2 ≤ 2.0 is satisfied.

2. The maximum height roughness Rz of the first cylindrical surface and the second cylindrical surface is 0.4μm≦Rz≦6.3μm Satisfying The tool holder according to claim 1.

3. The recess is formed in an area of ​​at least 50% or more of the circumference of the virtual cylindrical surface. The tool holder according to claim 1 or 2.

4. In the axial direction of the tool rotation center, When the maximum distance of the pocket portion is L, and the maximum distance between the leading end of the first cylindrical surface and the rear end of the second cylindrical surface is H, 0.5 ≤ H / L ≤ 2.0 The tool holder according to claim 1 or 2.

5. The tool holder has a portion that has been subjected to one or more surface treatments, including plating, blackening, PVD coating, and CVD coating. The tool holder according to claim 1 or 2.

6. The tool holder is not subjected to any of the following surface treatments: plating, blackening, PVD coating, or CVD coating. The tool holder according to claim 1 or 2.

7. An indexable cutting tool comprising a tool holder as described in claim 1 and a cutting insert mounted on the mounting seat.

8. The replaceable tip cutting tool according to claim 7, wherein the frontal runout and radial runout of the cutting edge fitted with the cutting insert are 50 μm or less, and the cutting edge diameter accuracy is 90 μm or less.

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