Boring tool and method for manufacturing machined product

Abstract

This boring tool includes: a shaft member; and a first cutter, a third cutter, and a second cutter that are fixed to the shaft member. The interval between the first cutter and the third cutter is greater than the interval between the second cutter and the third cutter. The second cutter includes: a second distal end surface; a second blade located on the outer circumferential side; and a second pocket. The third cutter includes: a third distal end surface; a third blade located on the outer circumferential side; and a third pocket. The second pocket is connected to the second distal end surface at a right angle, and the third pocket is connected to the third distal end surface at an obtuse angle.

Description

[Technical Field]

[0001] The present disclosure relates to a boring tool and a method for manufacturing a cutting. [Background technology]

[0002] Generally, boring tools are used for inner diameter machining (boring or boring) to enlarge the inner diameter of, for example, a cylindrical workpiece by cutting the inner peripheral surface. For example, Patent Documents 1 to 3 describe boring tools having a cylindrical shaft member and a cutting blade fixed so that the cutting edge protrudes outward beyond the outer peripheral surface of the shaft member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2014-069286 [Patent Document 2] International Publication No. 2015 / 170390 [Patent Document 3] International Publication No. 2020 / 208069 Summary of the Invention

[0004] A non-limiting example of a boring tool according to the present disclosure includes a shaft member extending along a rotation axis from a tip end to a rear end, a first cutter located near the tip end and fixed to the shaft member, a second cutter located near the rear end and fixed to the shaft member, and a third cutter located between the first and second cutters and fixed to the shaft member. The distance between the first and third cutters is greater than the distance between the second and third cutters. The second cutter has a flat second tip surface located near the tip end, a second cutting edge located on the outer periphery, and a second pocket located forward of the second cutting edge in the rotation direction of the rotation axis and connected to the second tip surface. The third cutter has a flat third tip surface located near the tip end, a third cutting edge located on the outer periphery, and a third pocket located forward of the third cutting edge in the rotation direction and connected to the third tip surface. The second pocket is connected to the second end surface at a right angle, and the third pocket is connected to the third end surface at an obtuse angle. [Brief explanation of the drawings]

[0005] [Figure 1] FIG. 1 is a perspective view of a boring tool according to a non-limiting embodiment of the present disclosure. [Figure 2] FIG. 2 is a perspective view of the boring tool shown in FIG. 1, seen from a different angle. [Figure 3] FIG. 3 is a front view of the boring tool shown in FIG. 2 as viewed from the tip side. [Figure 4] 4 is a side view of the boring tool shown in FIG. 1 as viewed from the A1 direction shown in FIG. 3. [Figure 5] 4 is a side view of the boring tool shown in FIG. 1 as viewed from the A2 direction shown in FIG. 3. [Figure 6] FIG. 6 is a cross-sectional view taken along the line VI-VI in FIG. 4. [Figure 7] FIG. 7 is a cross-sectional view taken along the line VII-VII in FIG. 4. [Figure 8] FIG. 8 is a cross-sectional view taken along the line VIII-VIII in FIG. 5. [Figure 9]FIG. 9 is a cross-sectional view taken along the line IX-IX in FIG. 4. [Figure 10] FIG. 6 is a cross-sectional view taken along the line XX in FIG. 5. [Figure 11] FIG. 2 is a schematic diagram illustrating a step in a method for manufacturing a machined product in a non-limiting embodiment of the present disclosure. [Figure 12] FIG. 2 is a schematic diagram illustrating a step in a method for manufacturing a machined product in a non-limiting embodiment of the present disclosure. [Figure 13] FIG. 2 is a schematic diagram illustrating a step in a method for manufacturing a machined product in a non-limiting embodiment of the present disclosure. [Figure 14] FIG. 2 is a schematic diagram illustrating a step in a method for manufacturing a machined product in a non-limiting embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0006] Hereinafter, a boring tool and a method for manufacturing a machined product according to an embodiment of the present disclosure will be described in detail with reference to the drawings. However, for the sake of convenience, the drawings referred to below show only the main components necessary for explaining the embodiment in a simplified form. Therefore, the rotary tool may include optional components not shown in the drawings. Furthermore, the dimensions of the components in the drawings do not faithfully represent the actual dimensions of the components, the dimensional ratios of the components, etc.

[0007] <Outline of boring tool configuration> The schematic configuration of the boring tool 1 according to this embodiment will be described with reference to Figures 1 to 3. Figure 1 is a perspective view showing the boring tool 1 according to this embodiment. Figure 2 is a perspective view of the boring tool 1 as viewed from a different angle. Figure 3 is a front view of the boring tool 1 shown in Figure 2 as viewed from the tip side. Figure 2 shows the boring tool 1 as viewed from a different angle than in Figure 1, with the direction of extension of the rotation axis L being different, and is a perspective view of the boring tool 1 rotated 90° about the rotation axis L from the state shown in Figure 1. The rotation axis L refers to the rotation center of the boring tool 1.

[0008] The boring tool 1 in this embodiment includes a plurality of cutters. The plurality of cutters may have different machining diameters. The boring tool 1 is used for inner diameter machining, for example, to enlarge the inner diameter of a cylindrical workpiece WP (see FIG. 11, etc.) by cutting the inner peripheral surface.

[0009] The boring tool 1 may be used, for example, for machining the inner diameter of an electric motor housing (case), and in this case, multiple machining regions with different inner diameters can be formed on the inner peripheral surface of the workpiece WP corresponding to the machining diameters of each of the multiple cutters. The boring tool 1 may be used for rough boring or fine boring. The boring tool 1 may also be used to enlarge a pilot hole in the workpiece WP. The pilot hole may be a through hole or a blind hole.

[0010] As shown in the example in FIGS. 1 to 3, the boring tool 1 includes a shaft member 2 extending from a front end (first end) 2a to a rear end (second end) 2b along a rotation axis L. The boring tool 1 has a connection part 3 that can be attached to, for example, a spindle (not shown) of a machine tool. The boring tool 1 is attached to, for example, the spindle and is rotatable around the rotation axis L. The connection part 3 may be a part of the shaft member 2, or may be a separate member attached to the shaft member 2.

[0011] In the boring tool 1 of this embodiment, the side where the connecting portion 3 is located is the rear end 2b side, and the side opposite the rear end 2b and in the feed direction (machining direction for the workpiece WP) of the boring tool 1 is the front end 2a side. In Figure 1 etc., the rotation direction of the boring tool 1 is indicated by arrow T, and the feed direction (machining direction) of the boring tool 1 during boring is indicated by arrow S.

[0012] Hereinafter, in this specification, in a cross section including the rotation axis L, the direction perpendicular to the rotation axis L will be referred to as the radial direction, the direction away from the rotation axis L will be referred to as the outer periphery side (radially outer side), and the direction approaching the rotation axis L will be referred to as the axial center side (radially inner side). Also, the direction of rotation centered on the rotation axis L will be referred to as the circumferential direction.

[0013] Here, each part of the boring tool 1 may have rotational symmetry around the rotation axis L. Therefore, in the drawings, for clarity of illustration, the same reference symbol may be omitted from assigning the same reference symbol to each of multiple members having similar shapes and functions, and a reference symbol may be assigned to only one of such multiple members.

[0014] (Shaft member) The shaft member 2 may have a ring-shaped rear fixed portion 5 located closer to the tip 2a than the connecting portion 3, a flat front fixed portion 6 located closer to the tip 2a than the rear fixed portion 5, and a base portion 4 located between the rear fixed portion 5 and the front fixed portion 6.

[0015] The rear fixing part 5 may be a part of the shaft member 2, or may be a separate member from the shaft member 2 that is attached to the outer surface of the shaft member 2. The rear fixing part 5 may have a size that is radially larger than the base part 4. The rear fixing part 5 may have an external shape that is formed by processing a circular ring to form flat surfaces on four radial directions. The rear fixing part 5 may have, on its outer peripheral surface, four flat surfaces 5a positioned on each of the four radial directions, and four curved surfaces 5b that are convex toward the outer periphery and positioned between the four flat surfaces 5a.

[0016] The tip fixing part 6 may be a part of the shaft member 2, or may be a separate member from the shaft member 2 that is attached to the tip 2a side of the shaft member 2. The tip fixing part 6 may have a size that is radially larger than the base part 4. The tip fixing part 6 may have an external shape formed by rounding the four corners of a rectangular flat plate. The tip fixing part 6 may have, on its outer peripheral surface, four flat surfaces 6a located on all four sides in the radial direction, and four curved surfaces 6b that are convex toward the outer periphery and located between the four flat surfaces 6a.

[0017] A plurality of cutters C are attached to the base unit 4. The plurality of cutters C may be fixed at different positions on the base unit 4 in the direction in which the rotation axis L extends (the longitudinal direction of the base unit 4). The base unit 4 may have an external shape formed by rounding the four corners of a rectangular parallelepiped, for example. The base unit 4 may have four flat surfaces 4a located on all four sides in the radial direction, and four curved surfaces 4b that are convex toward the outer periphery and located between the four flat surfaces 4a.

[0018] A coolant flow path may be formed inside the base 4, and this flow path may be connected to a coolant flow path formed inside each of the multiple cutters C attached to the base 4. The coolant may be, for example, air or a liquid. Examples of liquid coolants include water-insoluble oils and water-soluble oils such as emulsion-type, soluble-type, and solution-type cutting oils.

[0019] In this embodiment, in terms of the circumferential positional relationship, the position of the flat surface 5a of the rear fixing part 5 may correspond to the position of the curved surface 4b of the base part 4, and the position of the curved surface 5b of the rear fixing part 5 may correspond to the position of the flat surface 4a of the base part 4. Also, in this embodiment, the position of the flat surface 6a of the front fixing part 6 may correspond to the position of the flat surface 4a of the base part 4, and the position of the curved surface 6b of the front fixing part 6 may correspond to the position of the curved surface 4b of the base part 4.

[0020] (cutter) The boring tool 1 may include a first cutter C10, a second cutter C20, and a third cutter C30 as the plurality of cutters C. In this specification, the first to third cutters C10 to C30 may be collectively referred to as cutter C when no distinction is made between them.

[0021] (1st cutter) The first cutter C10 is located on the side of the tip 2a and fixed to the shaft member 2. The first cutter C10 may include a first cutter body 11 and a first cartridge 13 as a cutting blade (first cutting blade) located on the outer periphery. The first cutter body 11 may have a plate-shaped tip plate portion 15 and a plurality of first protrusions 17 formed to rise from the tip plate portion 15 toward the rear end 2b and protruding in the radial direction. The first protrusions 17 may have a first base portion 19 at the end on the outer periphery to which the first cartridge 13 is attached.

[0022] The first cutter body 11 has a central hole through which the base portion 4 can be inserted. The first cutter body 11 may be, for example, plate-shaped. Specifically, the first cutter body 11 may have a three-dimensional shape in which the tip plate portion 15 and the multiple first protrusions 17 are formed by carving out and removing a part of a disk-shaped object that has a circular shape in a cross-sectional view when cut in a direction perpendicular to the rotation axis L.

[0023] In this embodiment, the first cutter body 11 may have six first protrusions 17 that protrude in six radial directions. The tip plate portion 15 and the first protrusions 17 of the first cutter body 11 may be integrally formed so as to be continuous with each other. In this embodiment, the first cutter body 11 may have a shape that is two-fold symmetric about the rotation axis L because the central hole of the first cutter body 11 corresponds to the shape of the base portion 4 (a substantially octagonal shape in a cross section when cut in a direction perpendicular to the rotation axis L).

[0024] The tip plate portion 15 may have a front plate surface 15a on the tip 2a side and a back plate surface 15b on the rear end 2b side. The first cutter body 11 may have a recessed portion 16 between two adjacent first protrusions 17, which is a space partially surrounded by the side surfaces of the two first protrusions 17 and the back plate surface 15b. The recessed portion 16 is isolated from the tip 2a side by the tip plate portion 15 located on the tip 2a side. As a result, when boring a workpiece WP with the boring tool 1, the tip plate portion 15 may block the space between the tip 2a side and the rear end 2b side of the hole to be machined.

[0025] Chips flow together with the coolant from the front end 2a to the rear end 2b in the boring tool 1. The recess 16 may be a chip pocket through which some of the chips generated by the cutting blade of the first cartridge 13 pass.

[0026] The first protrusion 17 may have a first outer peripheral surface 17c on its outer periphery. The first outer peripheral surface 17c may be located forward of the first pedestal portion 19 in the rotational direction T and may be located alongside the first pedestal portion 19. The first outer peripheral surface 17c may be located radially inward of the first pedestal portion 19 and may be a surface formed at a lower position than the first pedestal portion 19 in the radial direction. Coolant ejection holes H11 may be formed in the first outer peripheral surface 17c. Note that the coolant ejection holes H11 may be formed in the recessed portion 16 in addition to the first outer peripheral surface 17c.

[0027] The nozzle holes H11 may be located closer to the rear end 2b than the first seat portion 19. Alternatively, a coolant nozzle hole H12 may be formed on the front plate surface 15a at a position near the first outer peripheral surface 17c. The coolant ejected from the nozzle hole H12 passes through the first outer peripheral surface 17c, comes into contact with the cutting edge of the first cartridge 13, and flows toward the rear end 2b. The coolant ejected from the nozzle hole H11 flows toward the rear end 2b together with the coolant ejected from the nozzle hole H12.

[0028] The first cutter C10 is only required to have a cutting blade (first cutting blade) whose cutting edge protrudes from the outer peripheral surface of the first cutter body 11, and the specific form of the cutting blade located on the outer peripheral side is not particularly limited. In this embodiment, one first cartridge 13 may be attached to the first base portion 19 of each of the six first protrusions 17 by a clamp screw or the like. A known first cartridge 13 can be used, and the specific form of the first cartridge 13 is not particularly limited.

[0029] A first insert (first cutting blade) 13a may be attached to the first cartridge 13 by a screw or the like. The first insert 13a is a so-called cutting insert. The specific form of the first insert 13a is not particularly limited. At least one of the first cartridge 13 and the first insert 13a may be radially position adjustable. This allows the machining diameter of the first cutter C10 to be adjusted.

[0030] The surface of the first cutter body 11 on the rear end 2b side is referred to as the first rear side surface 11b. The first rear side surface 11b may be the surface of the first protrusion 17 on the rear end 2b side. The first cutter C10 may be fixed to the shaft member 2 as follows. That is, the first rear side surface 11b and the flat surface 4a of the base portion 4 may be screwed together using a first fastener 18, thereby fixing the first cutter C10 to the shaft member 2. In other words, the first cutter C10 may be fixed to the shaft member 2 by the first fastener 18 located closer to the rear end 2b than the first cutter body 11. A portion of the front plate surface 15a of the tip plate portion 15 of the first cutter C10 may abut against the front fixing portion 6.

[0031] The first cutter body 11 may be lightened to reduce weight, and may have multiple recesses 15c formed in the front plate surface 15a of the tip plate portion 15. The recesses 15c may have a rounded triangular shape when viewed from the direction along the rotation axis L. The recesses 15c may be formed at positions corresponding to the tip 2a side of the first protrusion 17 when viewed from the tip 2a side toward the rear end 2b side. The first cutter body 11 may also have multiple recesses 11c formed in the first rear side surface 11b. The recesses 11c may have a rounded triangular shape when viewed from the direction along the rotation axis L. The recesses 11c are formed to avoid the area of ​​the first rear side surface 11b where the first fastener 18 is screwed.

[0032] (Second cutter) The second cutter C20 is located on the rear end 2b side and fixed to the shaft member 2. The second cutter C20 may include a second cutter body 21 and a second cartridge 23 as a cutting blade (second cutting blade) located on the outer periphery side. The second cutter body 21 may have a second protruding portion 27 that protrudes in the radial direction. The second protruding portion 27 may have a second base portion 29 at its outer periphery end to which the second cartridge 23 is attached. The second cutter C20 has a second front end surface 27a that is a surface of the second cutter body 21 located on the front end 2a side, and a second rear end surface 27b that is a surface located on the rear end 2b side. The second front end surface 27a and the second rear end surface 27b may each be a flat surface.

[0033] In this specification, the term "flat surface" or "plane" is intended to mean a surface that is not curved at a visibly noticeable level or that does not have any visible irregularities, and does not require a surface to be strictly flat. A "flat surface" or "plane" may allow for some unavoidable irregularities that may occur during the manufacturing process, and specifically may have irregularities with a surface roughness of about 50 μm.

[0034] The second cutter C20 is located forward of the second cartridge 23 as a second cutting blade in the rotation direction T of the rotation axis L and may have a second pocket 26 connected to the second front end surface 27a. The second pocket 26 may also be connected to the second rear end surface 27b. The second pocket 26 is located along the second cartridge 23 and has a second groove 40 extending from the front end 2a to the rear end 2b.

[0035] The second groove 40 may be a surface extending from the front end 2a toward the rear end 2b so as to connect the second front end surface 27a and the second rear end surface 27b. The second groove 40 may be a surface corresponding to a side surface (surface on the outer circumferential side) of the second cutter body 21, in other words, a surface corresponding to a side surface on the circumferential side of the second protrusion 27. The second pocket 26 may be a space partially surrounded by the second groove 40.

[0036] The second grooves 40 are located along the second insert (second cutting edge) 23a and can be used as chip discharge grooves. When the second grooves 40 are located along the second cutting edge, chips generated by the second cutting edge can be stably discharged to the outside.

[0037] The second cutter body 21 has a central hole through which the base portion 4 can be inserted. The second cutter body 21 may be, for example, plate-shaped. Specifically, the second cutter body 21 may have a three-dimensional shape in which multiple second protrusions 27 are formed by removing parts of a disk-shaped object that has an annular shape in a cross-sectional view when cut in a direction perpendicular to the rotation axis L. In this embodiment, the second cutter body 21 may have six second protrusions 27 that protrude in six directions when viewed from the direction along the rotation axis L. The second cutter body 21 may have a shape that is two-fold symmetric about the rotation axis L.

[0038] The second pocket 26 is provided as a space penetrating from the leading edge 2a to the rear edge 2b between two adjacent second protrusions 27. The second pocket 26 is a chip pocket through which chips and coolant flowing from the leading edge 2a to the rear edge 2b pass. In this embodiment, the second cutter C20 may have six second pockets 26. The second cutter C20 does not necessarily need to have a coolant ejection hole formed in the second cutter body 21.

[0039] The second cutter C20 is only required to have a cutting blade (second cutting blade) whose cutting edge protrudes from the outer circumferential surface of the second cutter body 21, and the specific form of the cutting blade located on the outer circumferential side is not particularly limited. In this embodiment, one second cartridge 23 may be attached to the second seat portion 29 of each of the six second protrusions 27 by a clamp screw or the like. A known second cartridge 23 can be used, and the specific form of the second cartridge 23 is not particularly limited.

[0040] A second insert (second cutting blade) 23a may be attached to the second cartridge 23 by a screw or the like. The second insert 23a is a so-called cutting insert. The specific form of the second insert 23a is not particularly limited. At least one of the second cartridge 23 and the second insert 23a may be radially position adjustable. This allows the machining diameter by the second cutter C20 to be adjusted.

[0041] The second cutter C20 may be fixed to the shaft member 2 as follows. That is, the second rear end surface 27b and the flat surface 5a of the rear fixing part 5 are screwed together using the second fixing device 28, thereby fixing the second cutter C20 to the shaft member 2. In other words, the second cutter C20 may be fixed to the shaft member 2 by the second fixing device 28 located closer to the rear end 2b than the second cutter body 21. A portion of the second rear end surface 27b of the second cutter C20 may abut against the rear fixing part 5.

[0042] The second cutter body 21 may be lightened to reduce weight, and may have a plurality of recesses 27c formed in the second front end surface 27a. The second cutter body 21 may also have a plurality of recesses 27d formed in the second rear end surface 27b. The recesses 27c and 27d may have a rounded triangular shape when viewed from the direction along the rotation axis L. The recesses 27c and 27d may be formed at positions corresponding to the front end 2a and rear end 2b of the second protrusion 27, respectively, when viewed from the front end 2a toward the rear end 2b. The recesses 27d are formed to avoid the area of ​​the second rear end surface 27b where the second fastener 28 is screwed.

[0043] (Third cutter) The third cutter C30 is located between the first cutter C10 and the second cutter C20 and fixed to the shaft member 2. The third cutter C30 may include a third cutter body 31 and a third cartridge 33 as a cutting blade (third cutting blade) located on the outer periphery. The third cutter body 31 may have a third protruding portion 37 that protrudes radially. The third protruding portion 37 may have a third base portion 39 at its outer periphery end to which the third cartridge 33 is attached. The third cutter C30 has a third front end surface 37a that is a surface of the third cutter body 31 located on the front end 2a side and a third rear end surface 37b that is a surface located on the rear end 2b side. The third front end surface 37a and the third rear end surface 37b may each be a flat surface.

[0044] The third cutter C30 is located forward of the third cartridge 33 as a third cutting blade in the rotation direction T of the rotation axis L, and may have a third pocket 36 connected to the third front end surface 37a. The third pocket 36 may also be connected to the third rear end surface 37b. The third pocket 36 is located along the third cartridge 33 and has a third groove 60 extending from the front end 2a to the rear end 2b.

[0045] The third groove 60 may be a surface extending from the front end 2a toward the rear end 2b so as to connect the third front end surface 37a and the third rear end surface 37b. The third groove 60 may be a surface corresponding to a side surface (an outer peripheral surface) of the third cutter body 31, in other words, a surface corresponding to a side surface on the circumferential side of the third protrusion 37. The third pocket 36 may be a space partially surrounded by the third groove 60.

[0046] The third grooves 60 are located along the third insert (third cutting edge) 33a and can be used as chip discharge grooves. When the third grooves 60 are located along the third cutting edge, chips generated by the third cutting edge can be stably discharged to the outside.

[0047] The third cutter body 31 has a central hole through which the base portion 4 can be inserted. The third cutter body 31 may be, for example, plate-shaped. Specifically, the third cutter body 31 may have a three-dimensional shape in which a plurality of third protrusions 37 are formed by removing a portion of a disk-shaped object that has a circular ring shape in a cross section when cut in a direction perpendicular to the rotation axis L. In this embodiment, the third cutter body 31 may have six third protrusions 37 that protrude in six directions when viewed from the direction along the rotation axis L. The third cutter body 31 may have a shape that is two-fold symmetric about the rotation axis L.

[0048] The third pocket 36 is provided as a space penetrating from the leading edge 2a to the rear edge 2b between two adjacent third protrusions 37. The third pocket 36 is a chip pocket through which chips and coolant flowing from the leading edge 2a to the rear edge 2b pass. In this embodiment, the third cutter C30 may have six third pockets 36.

[0049] The third cutter C30 is only required to have a cutting blade (third cutting blade) whose cutting edge protrudes from the outer circumferential surface of the third cutter body 31, and the specific form of the cutting blade located on the outer circumferential side is not particularly limited. In this embodiment, one third cartridge 33 may be attached to the third seat portion 39 of each of the six third protrusions 37 by a clamp screw or the like. A known third cartridge 33 can be used, and the specific form of the third cartridge 33 is not particularly limited.

[0050] A third insert (third cutting blade) 33a may be attached to the third cartridge 33 by a screw or the like. The third insert 33a is a so-called cutting insert. The specific form of the third insert 33a is not particularly limited. At least one of the third cartridge 33 and the third insert 33a may be radially position adjustable. This allows the machining diameter of the third cutter C30 to be adjusted.

[0051] The third protrusion 37 may have a third outer peripheral surface 37c that is located rearward of the third seat portion 39 in the rotational direction T and is aligned with the third seat portion 39. The third outer peripheral surface 37c may be located radially outward of the third seat portion 39 and may be a surface formed at a higher position in the radial direction than the third seat portion 39. Coolant ejection holes H31 may be formed in the third outer peripheral surface 37c. The ejection holes H31 may be located closer to the rear end 2b than the third insert 33a.

[0052] The third protrusion 37 may have a third seating surface 37d that is located forward of the third seating portion 39 in the rotational direction T and that is aligned with the third seating portion 39. The third seating surface 37d may be a surface that is formed at the same height as the third seating portion 39 in the radial direction. A coolant ejection hole H32 may be formed in the third seating surface 37d. The ejection hole H32 may be located forward of the third insert 33a of the third cartridge 33 in the rotational direction T and adjacent to the third insert 33a.

[0053] The third protrusion 37 may have a coolant ejection hole H33 formed in a position near the third outer circumferential surface 37c on the third rear end surface 37b. The coolant ejected from the ejection holes H31 to H33 flows toward the rear end 2b.

[0054] The third cutter C30 may further have a coolant ejection hole H33 formed in the third rear end surface 37b of the third cutter body 31. The ejection hole H33 may be formed in a position in the third rear end surface 37b near the third outer circumferential surface 37c. The ejection hole H33 may be formed in a position such that the coolant ejected from the ejection hole H33 flows toward the second cartridge 23 of the second cutter C20. The coolant ejected from the ejection holes H31 to H33 flows toward the rear end 2b.

[0055] The third cutter C30 may be fixed to the shaft member 2 as follows. That is, the third tip surface 37a and the flat surface 4a of the base portion 4 are screwed together using a third fastener 38, thereby fixing the third cutter C30 to the shaft member 2. In other words, the third cutter C30 may be fixed to the shaft member 2 by the third fastener 38 located closer to the tip 2a than the third cutter body 31.

[0056] The third cutter body 31 may be hollowed out to reduce weight, and may have a plurality of recesses 37e formed in the third tip surface 37a. The recesses 37e may have a rounded triangular shape when viewed from the direction along the rotation axis L. The recesses 37e may be formed at positions corresponding to the tip 2a side of the third protrusion 37 when viewed from the tip 2a side toward the rear end 2b side in a planar perspective view. The recesses 37e are formed to avoid the area of ​​the third tip surface 37a where the third fastener 38 is screwed.

[0057] <Details of each part> The boring tool 1 of this embodiment will be described in more detail below with reference to Figs. 4 to 10. Fig. 4 is a side view of the boring tool 1 shown in Fig. 1 as viewed from the A1 direction shown in Fig. 3. Fig. 5 is a side view of the boring tool 1 shown in Fig. 1 as viewed from the A2 direction shown in Fig. 3. Fig. 6 is a cross-sectional view taken along line VI-VI in Fig. 4. Fig. 7 is a cross-sectional view taken along line VII-VII in Fig. 4. Fig. 8 is a cross-sectional view taken along line VIII-VIII in Fig. 5. Fig. 9 is a cross-sectional view taken along line IX-IX in Fig. 4. Fig. 10 is a cross-sectional view taken along line XX in Fig. 5. In the following description, Figs. 1 to 3 may also be referred to as appropriate.

[0058] 4 to 10, in the boring tool 1 of this embodiment, the distance D1 between the first cutter C10 and the third cutter C30 is larger than the distance D2 between the second cutter C20 and the third cutter C30. Such an arrangement of the cutters C may be required depending on the application of the boring tool 1. It is also envisioned that the space between the first cutter C10 and the third cutter C30 may be used as a coolant reservoir.

[0059] As described above, in the boring tool 1, chips generated by the first cutter C10 on the front end 2a side flow toward the rear end 2b side, pass through the third cutter C30 and the second cutter C20, and are discharged to the outside.

[0060] Generally, boring tools with multiple cutters can increase machining efficiency. However, when the cutters are spaced apart, chips do not flow smoothly into the pockets of the rear cutters, which can result in damage to the rear cutters or the workpiece.

[0061] Therefore, in the boring tool 1 of this embodiment, the second pocket 26 may be connected to the second tip surface 27a at a right angle, and the third pocket 36 may be connected to the third tip surface 37a at an obtuse angle. Note that the "right angle" in the above description is not limited to 90° in the strict sense, but may be in the range of ±5°. Also, since the right angle is in the range of 90±5°, the "obtuse angle" is intended to be greater than 95°.

[0062] According to the above configuration, the coolant and chips generated by the first cutter C10 can easily flow from the space 90 between the first cutter C10 and the third cutter C30 to the third pocket 36, and can also easily flow from the third pocket 36 to the second pocket 26. Therefore, even though the boring tool 1 has multiple cutters C, it is possible to effectively improve the dischargeability of chips.

[0063] Furthermore, in the boring tool 1 of this embodiment, the third groove 60, which partially surrounds the third pocket 36 and extends from the front end 2a to the rear end 2b, may have a third front region 61 located on the front end 2a side and connected to the third front end face 37a, and a third rear region 62 located closer to the rear end 2b than the third front region 61. The inclination angle θ1 of the third front region 61 with respect to the third front end face 37a may be larger than the inclination angle θ2 of the third rear region 62 with respect to the third front end face 37a (see FIG. 9).

[0064] The inclination angle θ1 is the angle at which the third forward region 61 is inclined with respect to the third tip face 37a in a cross section (e.g., the cross section shown in FIG. 9 ) of the boring tool 1 cut in a direction parallel to the rotation axis L and perpendicular to the protruding direction of one third protrusion 37 (the normal direction to the plane 4a). The inclination angle θ1 is an obtuse angle and may be an angle between 120° and 160°. The inclination angle θ2 is the angle at which the third rearward region 62 is inclined with respect to the third tip face 37a in the cross section (e.g., the cross section shown in FIG. 9 ). The inclination angle θ2 may be a right angle and may be in the range of 90±5°.

[0065] According to the above configuration, chips generated by the first cutter C10 are more likely to be drawn into the third pocket 36. Furthermore, when the inclination angle θ1 of the third front region 61 is larger than the inclination angle θ2 of the third rear region 62, chip discharge performance can be improved while ensuring the strength of the third protrusion 37 of the third cutter C30.

[0066] In the boring tool 1, a width W of a portion of the third forward region 61 that is located forward of the bottom 63 of the third groove 60 in the rotation direction T may become narrower toward the front in the rotation direction T (see FIG. 4). The bottom of the third groove 60 is a portion of the third groove 60 that is located closest to the axis (inner in the radial direction). The width W is defined as the distance in a direction parallel to the rotation axis L from a ridge R1 where the third tip face 37a and the third forward region 61 intersect to a boundary B1 between the third forward region 61 and the third rearward region 62 in a side view of the boring tool 1 (see FIGS. 4, 6, and 7).

[0067] According to the above configuration, the third groove 60 has a third forward region 61 formed as a cutout portion closer to the axis than the third rear region 62, and the width W of the third forward region 61 decreases as it approaches the third pedestal portion 39. Therefore, the third protruding portion 37 of the third cutter C30 can easily ensure a volume in a portion rearward of the third pedestal portion 39 in the rotation direction T. As a result, the strength of the third protruding portion 37 can easily be ensured.

[0068] Furthermore, in this embodiment, the second groove 40 of the second cutter C20, which extends from the front end 2a to the rear end 2b while partially surrounding the second pocket 26, may have a first partial groove 41 and a second partial groove 42.

[0069] The first partial groove 41 is located along the second cartridge 23 (second cutting blade) and is a portion extending from the leading end 2a toward the rear end 2b, while the second partial groove 42 is located forward of the first partial groove 41 in the rotational direction T and may extend from the leading end 2a toward the rear end 2b. The first partial groove 41 and the second partial groove 42 may each be a curved surface having a shape recessed toward the second protrusion 27 in a cross section taken in a direction perpendicular to the rotation axis L.

[0070] The second groove 40 is an intersection of the first partial groove 41 and the second partial groove 42, and may have a ridge portion 43 extending from the front end 2a toward the rear end 2b (see FIGS. 4, 5, 6, and 8). The ridge portion 43 may be a ridge line or a ridge portion having some width. In the boring tool 1, when the second cutter C20 and the third cutter C30 are seen from the front end 2a, the first partial groove 41 may be located rearward of the third cartridge 33 (third cutting blade) of the third cutter C30 in the rotational direction T (see FIG. 6).

[0071] According to the above configuration, chips generated by the second cutter C20 can easily flow through the portion of the second pocket 26 where the first partial groove 41 is located, in other words, the portion of the second pocket 26 located on the rear end 2b side of the third protrusion 37 when viewed from above in plan view.

[0072] In this embodiment, when the second cutter C20 and the third cutter C30 are seen from the tip 2a side, the second partial groove 42 may at least partially overlap with the third groove 60 (see FIGS. 6 and 7).

[0073] According to the above configuration, the coolant and chips generated by the third cutter C30 can be made to flow easily from the third pocket 36 through the portion of the second pocket 26 where the second partial groove 42 is located toward the rear end 2b. As such, according to the boring tool 1 of this embodiment, it is possible to provide a portion in the second pocket 26 through which chips generated by the second cutter C20 preferentially pass and a portion through which chips generated by the third cutter C30 preferentially pass. This makes it easier for chips to flow from the front end 2a toward the rear end 2b. As a result, chip discharge can be effectively improved.

[0074] For example, the third cutter C30 may have its third tip surface 37a attached to the flat surface 4a of the base portion 4 using a third fixture 38, and the second cutter C20 may have its second rear end surface 27b attached to the flat surface 5a of the rear fixing portion 5 using a second fixture 28. The flat surfaces 4a and 5a may be offset from each other by 45° in the circumferential direction, thereby allowing the third cutter C30 and the second cutter C20 to be fixed to the base portion 4 with the third protrusion 37 and the second protrusion 27 offset from each other in the circumferential direction. This allows for a configuration in which the above-described chip flow can occur in the second pocket 26. Furthermore, the arrangement of the coolant ejection holes H31-33 in the second cutter body 21 of the second cutter C20 can further facilitate the above-described chip flow.

[0075] In this embodiment, the second groove 40 may have a second forward region 44 located on the front end 2a side and a second rearward region 45 located on the rear end 2b side. When viewed from the side, the inclination angle of the second forward region 44 with respect to the rotation axis L is defined as a first inclination angle θ3, and the inclination angle of the second rearward region 45 with respect to the rotation axis L is defined as a second inclination angle θ4. In the boring tool 1, the second inclination angle θ4 may be larger than the first inclination angle θ3 (see FIGS. 4, 5, and 10). The first inclination angle θ3 may be close to 0. The second inclination angle θ4 may be an angle between 10° and 20°.

[0076] According to the above configuration, the second pocket 26 has the second rear region 45, so that the area of ​​the second pocket 26 can be made to increase toward the rear end 2b (the outlet side in the chip flow direction). Therefore, chips that have flowed into the second pocket 26 can flow toward the rear end 2b from the second pocket 26 and be easily discharged to the outside. As a result, the chip discharge performance can be further improved.

[0077] Furthermore, the second groove 40 may have a first inclination angle θ3 of 0°, and the second front region 44 may extend parallel to the rotation axis L. This allows chips to easily flow from the third pocket 36 to the second pocket 26.

[0078] (Material etc.) Examples of materials for the various parts of the boring tool 1 include steel such as stainless steel, cast iron, and aluminum alloy. In particular, when steel is used among these materials, the toughness of the shaft member 2 is high. Examples of materials for the cutting edges of the first insert 13a to the third insert 33a, etc. include cemented carbide and cermet, etc.

[0079] Examples of cemented carbide compositions include WC-Co, WC-TiC-Co, and WC-TiC-TaC-Co. Here, WC, TiC, and TaC may be hard particles, and Co may be a binder phase. The cermet may be a sintered composite material in which a ceramic component is combined with a metal. An example of a cermet is a titanium compound mainly composed of titanium carbide (TiC) or titanium nitride (TiN). The cutting edge used in the boring tool 1 is not limited to the above materials.

[0080] There is no particular limitation on the size of the shaft member 2. For example, the length in the direction along the rotation axis L can be set to about 150 mm to 300 mm. The diameter of the shaft member 2, which corresponds to the thickness of the base portion 4, can be set to about 50 mm to 120 mm.

[0081] The cutting diameters of the first cutter C10, the second cutter C20, and the third cutter C30 are not particularly limited. The cutting diameter of the cutter C is defined by the diameter of the cutting circle of the cutting edge of the cutter C. The cutting diameter of the first cutter C10 may be smaller than the cutting diameters of the second cutter C20 and the third cutter C30. The cutting diameter of the third cutter C30 may be larger than the cutting diameter of the first cutter C10 and smaller than the cutting diameter of the second cutter C20. For example, the cutting diameter of the first cutter C10 can be set to approximately 60 mm to 280 mm. For example, the cutting diameter of the second cutter C20 can be set to approximately 160 mm to 280 mm. For example, the cutting diameter of the third cutter C30 can be set to approximately 140 mm to 280 mm.

[0082] The distance D1 between the first cutter C10 and the third cutter C30 may be about 60 mm to 150 mm, and the distance D2 between the second cutter C20 and the third cutter C30 may be about 10 mm to 80 mm.

[0083] <Modification> Without being limited to the example of this embodiment, the boring tool 1 may have four or more cutters C. For example, a fourth cutter may be provided between the first cutter C10 and the third cutter C30.

[0084] Without being limited to the example of this embodiment, the first cutter C10, the second cutter C20, and the third cutter C30 may each be formed integrally with the shaft member 2 so as to be continuous with the shaft member 2.

[0085] The cutting edges of the first cutter C10, the second cutter C20, and the third cutter C30 may be formed integrally with the first cutter body 11, the second cutter body 21, and the third cutter body 31, respectively.

[0086] Without being limited to the example of this embodiment, the first cutter C10 and the third cutter C30 may each be screwed to the curved surface 4b of the base part 4. The second cutter C20 may be screwed to the curved surface 5b of the rear fixing part 5. The specific means by which the first cutter C10, the second cutter C20, and the third cutter C30 are fixed to the shaft member 2 are not particularly limited, and the specific shape of the shaft member 2 is not particularly limited.

[0087] <Method of manufacturing machined products> Next, a non-limiting method for manufacturing a machined product according to the present disclosure will be described with reference to Figures 11 to 14. Figures 11 to 14 are schematic diagrams showing a step in the method for manufacturing a machined product. For clarity of illustration, a cross section of the workpiece WP is shown, while the boring tool 1 is shown as seen from the side.

[0088] The machined product is produced by cutting a workpiece WP. The manufacturing method of the machined product in the embodiment includes the following steps: (1) rotating the boring tool 1; (2) bringing the boring tool 1 into contact with the workpiece WP; (3) a step of separating the boring tool 1 from the workpiece WP; It has the following.

[0089] More specifically, first, as shown in Fig. 11, the boring tool 1 may be rotated around the rotation axis L and brought relatively close to the cylindrical workpiece WP. For example, the boring tool 1 is rotated by connecting the connection part 3 of the boring tool 1 to a spindle or the like.

[0090] 12, the cutting edge of the first cutter C10 of the boring tool 1 is brought into contact with the inner peripheral surface of the workpiece WP to cut the inner peripheral surface 100 of the workpiece WP, thereby performing inner diameter machining to expand the inner diameter of the workpiece WP. This makes it possible to form a first machining region 101 machined by the first cutter C10 that has an inner diameter wider than the inner peripheral surface 100 of the workpiece WP.

[0091] 12 and 13, the boring tool 1 is advanced further into the workpiece WP. This brings the cutting edge of the third cutter C30 into contact with the first machining region 101, forming a third machining region 102 machined by the third cutter C30 and having a wider inner diameter than the first machining region 101. Then, the cutting edge of the second cutter C20 is brought into contact with the third machining region 102, forming a second machining region 103 machined by the second cutter C20 and having a wider inner diameter than the third machining region 102.

[0092] Thereafter, as shown in FIG. 14, the boring tool 1 may be moved relatively away from the workpiece WP.

[0093] 11 to 13, the workpiece WP is fixed, and the boring tool 1 is moved while rotating around the rotation axis L, thereby moving the boring tool 1 closer to the workpiece WP. Also, in the examples of FIGS. 11 to 13, the cutting edge of the rotating boring tool 1 is brought into contact with the fixed workpiece WP, thereby cutting the workpiece WP. Also, in FIG. 14, the boring tool 1 is moved away from the fixed workpiece WP.

[0094] In the manufacturing method of this embodiment, in each step, the boring tool 1 is moved so that the boring tool 1 comes into contact with the workpiece WP or moves away from the workpiece WP. However, it is needless to say that the method is not limited to this.

[0095] For example, in step (1), the workpiece WP may be brought closer to the boring tool 1. Similarly, in step (3), the workpiece WP may be moved away from the boring tool 1. Furthermore, the present invention is not necessarily limited to the above example, and the workpiece WP may be rotated. By rotating the boring tool 1 relative to the workpiece WP, the workpiece WP can be machined.

[0096] Typical examples of the material of the workpiece WP include hardened steel, carbon steel, alloy steel, stainless steel, cast iron, and non-ferrous metals.

[0097] [Additional notes] The invention according to the present disclosure has been described above based on the drawings and embodiments. However, the invention according to the present disclosure is not limited to the above-described embodiments. In other words, the invention according to the present disclosure can be modified in various ways within the scope of the present disclosure, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the invention according to the present disclosure. In other words, it should be noted that a person skilled in the art could easily make various modifications or corrections based on the present disclosure. It should also be noted that these modifications or corrections are included in the scope of the present disclosure. [Explanation of symbols]

[0098] 1 Boring tool 2 Shaft member 2a tip 2b rear end 21 Second cutter body 23 Second Cartridge 23a 2nd insert (2nd cutting edge) 26 Second Pocket 27 Second protrusion 27a 2nd tip surface 27b Second rear end surface 31 Third cutter body 33 Third Cartridge 33a 3rd insert (3rd cutting edge) 36 Third Pocket 37 Third protrusion 37a 3rd tip surface 37b Third rear end surface C10 1st cutter C20 2nd cutter C30 3rd cutter D1, D2 interval L rotation axis T Rotation direction

Claims

1. a shaft member extending from the front end to the rear end along the rotation axis; a first cutter located on the tip side and fixed to the shaft member; a second cutter located on the rear end side and fixed to the shaft member; a third cutter located between the first cutter and the second cutter and fixed to the shaft member, a distance between the first cutter and the third cutter is greater than a distance between the second cutter and the third cutter; The second cutter is a flat second tip surface located on the tip side; a second cutting edge located on the outer periphery side; a second pocket located forward of the second cutting edge in the rotation direction of the rotation shaft and connected to the second tip surface, The third cutter is a flat third tip surface located on the tip side; a third cutting edge located on the outer periphery side; a third pocket located forward of the third cutting edge in the rotation direction and connected to the third tip surface, the second pocket is connected to the second tip surface at a right angle, and the third pocket is connected to the third tip surface at an obtuse angle; the third pocket has a third groove located along the third cutting edge and extending from the leading end side toward the rear end side, The third groove is a third distal region located on the distal end side and connected to the third distal end surface; a third rear region located closer to the rear end than the third front region, an inclination angle of the third forward region with respect to the third forward end surface is larger than an inclination angle of the third rearward region with respect to the third forward end surface; a width of a portion of the third forward region that is located further forward in the rotation direction than a bottom of the third groove narrows toward the front in the rotation direction.

2. the second pocket has a second groove located along the second cutting edge and extending from the leading end side toward the trailing end side, The second groove is a first partial groove located along the second cutting edge and extending from the leading end side toward the trailing end side; a second partial groove located forward of the first partial groove in the rotational direction and extending from the front end side toward the rear end side; a ridge portion at an intersection of the first partial groove and the second partial groove, the ridge portion extending from the front end side toward the rear end side, 2. The boring tool according to claim 1, wherein when the second cutter and the third cutter are viewed from the tip side in a plan view, the first partial groove is located rearward of the third cutting edge in the rotational direction.

3. The boring tool according to claim 2 , wherein the second partial groove overlaps with the third groove when the second cutter and the third cutter are seen through from above from the tip side.

4. A shaft member extending along a rotation axis from a front end to a rear end; a first cutter located on the tip side and fixed to the shaft member; a second cutter located on the rear end side and fixed to the shaft member; a third cutter located between the first cutter and the second cutter and fixed to the shaft member, a distance between the first cutter and the third cutter is greater than a distance between the second cutter and the third cutter; The second cutter is a flat second tip surface located on the tip side; a second cutting edge located on the outer periphery side; a second pocket located forward of the second cutting edge in the rotation direction of the rotation shaft and connected to the second tip surface, The third cutter is a flat third tip surface located on the tip side; a third cutting edge located on the outer periphery side; a third pocket located forward of the third cutting edge in the rotation direction and connected to the third tip surface, the second pocket is connected to the second tip surface at a right angle, and the third pocket is connected to the third tip surface at an obtuse angle; the second pocket has a second groove located along the second cutting edge and extending from the leading end side toward the trailing end side, the third pocket has a third groove located along the third cutting edge and extending from the leading end side toward the rear end side, The second groove is a first partial groove located along the second cutting edge and extending from the leading end side toward the trailing end side; a second partial groove located forward of the first partial groove in the rotational direction and extending from the front end side toward the rear end side; a ridge portion at an intersection of the first partial groove and the second partial groove, the ridge portion extending from the front end side toward the rear end side, A boring tool, wherein when the second cutter and the third cutter are viewed in plan view from the tip side, the first partial groove is located rearward of the third cutting edge in the rotational direction.

5. The boring tool according to claim 4 , wherein the second partial groove overlaps with the third groove when the second cutter and the third cutter are seen through from above from the tip side.

6. the second pocket has a second groove located along the second cutting edge and extending from the leading end side toward the trailing end side, The second groove is a second distal region located on the distal end side; a second rear region located on the rear end side, When viewed from the side, an inclination angle of the second front region with respect to the rotation axis is a first inclination angle, and an inclination angle of the second rear region with respect to the rotation axis is a second inclination angle, The boring tool of claim 1 , wherein the second tilt angle is greater than the first tilt angle.

7. 7. The boring tool of claim 6, wherein the first inclination angle is 0° and the second forward region extends parallel to the axis of rotation.

8. A step of rotating the boring tool according to any one of claims 1 to 7; contacting the boring tool with a workpiece; and a step of separating the boring tool from the workpiece.

Images