WO2017188240A1

WO2017188240A1 - Tip for cutting tool and manufacturing method therefor

Info

Publication number: WO2017188240A1
Application number: PCT/JP2017/016357
Authority: WO
Inventors: 寛久石
Original assignee: 京セラ株式会社
Priority date: 2016-04-27
Filing date: 2017-04-25
Publication date: 2017-11-02
Also published as: JP6755119B2; JP2017196697A

Abstract

In the case of this tip, a first inner surface of a first member and a second inner surface of a second member face each other. The first inner surface and the second inner surface have a frame-like convex part and a concave part, respectively, which are fitted together, thereby forming an opening serving as a mounting hole. The convex part has a first inclined surface, the concave part has a second inclined surface, and the surfaces face each other.

Description

Cutting tool tip and manufacturing method thereof

This aspect relates to a chip constituting a blade part of a cutting tool and a manufacturing method thereof.

A so-called insert (throw away tip) is known which is mounted on an insert type (blade tip exchange type) cutting tool to constitute a blade part. Such a cutting tool tip is generally formed by pressing a mixture of a raw material powder made of a relatively hard material and a raw material powder serving as a binder phase component of the hard raw material powder with a mold, and thereafter It is formed by firing.

Further, as described in JP-A-5-285708 (Patent Document 1), JP-A-2014-121770 (Patent Document 2) and US Patent Application Publication No. 2013/0195569 (Patent Document 3). In addition, there is also known a method of manufacturing a chip by bonding two molded members together instead of integrally molding the entire chip. Patent Documents 1 to 3 disclose that a convex portion and a concave portion that are fitted to each other are formed on surfaces of two members to be bonded to each other, thereby aligning the two members.

The cutting tool tip according to one aspect includes a first member having a first outer surface, a first inner surface on the back surface, and a first hole penetrating from the first outer surface to the first inner surface. A second outer surface, a second inner surface on the back surface thereof, and a second member having a second hole penetrating from the second outer surface to the second inner surface. The first inner surface and the second inner surface are opposed to each other so that one hole and the second hole constitute one through hole, and the first inner surface has the first hole as an opening. A convex portion having a frame shape, and the convex portion has a first inclined surface so that the width becomes narrower as the distance from the first outer surface becomes larger, and the second inner surface has the second inner surface. It has a frame-like recess having an opening as a hole, and the recess has a second inclined surface so that the width becomes narrower as it approaches the second outer surface, Serial first inclined surface and the second inclined surface are opposed to each other.

The perspective view which shows the insert type cutting tool which concerns on 1st Embodiment. The perspective view which shows the chip | tip for cutting tools of the cutting tool of FIG. Sectional drawing in the III-III line of FIG. The disassembled perspective view which shows typically the structure of the chip | tip for cutting tools of FIG. The flowchart which shows the procedure of the manufacturing method of the chip | tip for cutting tools. 6 (a), 6 (b), 6 (c), 6 (d), 6 (e) and 6 (f) are schematic diagrams for explaining the outline of each step in FIG. . The flowchart which shows the modification of the procedure of the manufacturing method of the chip | tip for cutting tools. The typical exploded perspective view showing the composition of the tip for cutting tools concerning a 2nd embodiment. The typical exploded perspective view showing the composition of the tip for cutting tools concerning a 3rd embodiment.

(How to use terms)
Some terms relating to cutting tools are customarily ambiguous. In the following description of the embodiments, such terms are basically used as follows.

In the present embodiment, the blade portion is used as a term indicating a relatively small portion (for example, a part of an insert) including a rake face, a flank face, and a cutting edge.

The cutting edge is used as a term indicating the ridge line between the rake face and the flank face. However, the actual cutting blade is not a line microscopically as the term “cutting blade roundness” exists, and the cutting blade has an area or a volume as long as it is.

The rake face and flank face mainly refer to the rake face and flank face closest to the cutting edge. Note that the flank may or may not include a so-called margin.

<First Embodiment>
(Configuration of cutting tool)
FIG. 1 is a perspective view showing an insert-type cutting tool 1 according to the first embodiment.

The cutting tool 1 is a substantially shaft-shaped member that is attached to and detached from a holder 3 (shank) attached to a machine tool and a tip end side (left side of the paper) of the holder 3 and actually contacts a work piece. And one or more (three in the example of FIG. 1) chips 5 for cutting the work. In the example shown in the drawing, the cutting tool 1 is an end mill, and is capable of cutting a workpiece on the tip surface and the outer peripheral surface of the tip by being rotated about an axis.

The mounting of the chip 5 to the holder 3 is performed, for example, by screwing the screw 7 inserted through the chip 5 into a female screw portion (not shown) hidden in the chip 5. The holder 3 is formed with, for example, a recess 3r composed of a plurality of surfaces with which a plurality of surfaces (for example, one main surface and two side surfaces) of the chip 5 abut. The chip 5 is positioned by contacting the surface of the recess 3r.

(Chip configuration)
FIG. 2 is a perspective view showing the chip 5. 3 is a cross-sectional view taken along line III-III in FIG.

In FIG. 2 and FIG. 3, etc., an orthogonal coordinate system xyz defined fixedly with respect to the chip 5 is attached. In the following description, directions may be described with reference to this coordinate system. Any direction of the chip 5 may be a vertical direction or a horizontal direction, and the dimension in the z-axis direction may be relatively large. However, the z-axis direction is referred to as a vertical direction or a thickness direction. is there. Further, when the chip 5 is simply referred to as a plan view, it refers to viewing in the z-axis direction.

The chip 5 is formed in, for example, a substantially rectangular parallelepiped shape, and includes the first main surface 9A and the second main surface 9B (hereinafter, simply referred to as “main surface 9”, which may not be distinguished from each other). It has four side surfaces 11 located between the pair of main surfaces 9 and connecting the pair of main surfaces 9. In addition, all the side surfaces 11 whole may be called the outer peripheral side surface 12. The dimensions of the chip 5 may be set as appropriate.

(Blade configuration)
The tip 5 has, for example, a long-side blade portion 13L and a short-side blade portion 13S (hereinafter simply referred to as “blade portion 13”, which are not distinguished from each other) that are directly involved in the cutting of the work material. ing. These blade portions 13 are located at corners (that is, intersecting ridge lines) between the main surface 9 and the side surface 11. The long edge part 13L and the short edge part 13S are connected with corners 21 (nose) at the corners of the long side and the short side in plan view.

The combination of the long side blade portion 13L and the short side blade portion 13S is provided, for example, on each of the pair of main surfaces 9 and on each of the main surfaces 9 at two corner portions located on one diagonal line. Yes.

Each blade portion 13 includes a rake face 15 that is a main body for cutting, a flank face 17 that is escaped to avoid unnecessary contact with the finished cutting surface, and a rake face 15 that is a portion where the rake face 15 is connected to the flank face 17. And a blade 19.

The blade portion 13 is formed, for example, so as to protrude in the thickness direction (z-axis direction) with respect to the main surface 9 (the central region). Specifically, for example, the rake face 15 is continuous to the center side of the main surface 9 and is formed to rise in the thickness direction from the center side of the main surface 9.

As described above, in the present embodiment, since the blade portion 13 protrudes from the main surface 9, the tip 5 includes the base portion 23 having the main surface 9 and the side surface 11, and the blade portion 13 protruding from the base portion 23. May be perceived as having Further, since the blade portion 13 protrudes from the main surface 9, in the present embodiment, it may be considered that the cutting blade 19 is formed on at least one of the upper end portion and the lower end portion of the outer peripheral surface 412.

(Configuration of mounting holes)
The chip 5 has a through hole. The through hole is an attachment hole 25 through which, for example, the screw 7 is inserted. As shown in FIG. 3, the mounting hole 25 accommodates the screw head 7b of the screw 7 and is engaged with the first receiving portion 27A and the second receiving portion 27B (hereinafter simply referred to as “receiving portion 27”). And there is a case where the two are not distinguished from each other.) And an insertion portion 29 through which the male screw portion 7a of the screw 7 is inserted. The receiving portion 27 is provided on both main surface sides, and the insertion portion 29 is provided therebetween.

The width of the insertion portion 29 in the direction orthogonal to the penetration direction is constant in the cross section along the penetration direction. The receiving portion 27 extends from the insertion portion 29 to the outside of the mounting hole 25 while increasing the area of the transverse section (xy section).

(Chip bonding structure)
FIG. 4 is an exploded perspective view schematically showing the configuration of the chip 5.

As shown in FIGS. 3 and 4, the chip 5 is configured by bonding a first member 31A and a second member 31B.

In the following description, “first” and “A” are attached to the components related to the first member 31A, and “second” and “B” are attached to the components related to the second member 31B. In addition, “first” and “A” and “second” and “B” may be omitted to distinguish the two.

1st member 31A and 2nd member 31B are comprised so that the chip | tip 5 may be divided | segmented into the penetration direction of the attachment hole 25. FIG. That is, the first member 31A has a first outer surface (hereinafter also referred to as a first outer surface 9A) that becomes the first main surface 9A, a first inner surface 33A on the back surface, and a first outer surface 9A. To the first inner side surface 33 A and a first hole 35 A constituting the attachment hole 25. Further, the second member 31B has a second outer surface (hereinafter also referred to as a second outer surface 9B) that becomes the second main surface 9B, a second inner surface 33B on the back surface, and a second outer surface 9B. To the second inner side surface 33 B and a second hole 35 B that constitutes the attachment hole 25. The first inner side surface 33A and the second inner side surface 33B are joined to face each other so that the first hole 35A and the second hole 35B are connected to form one through hole (mounting hole 25). Yes.

Further, the first member 31A has four first divided side surfaces 37A that connect the first outer side surface 9A and the first inner side surface 33A (the whole is referred to as a first divided outer peripheral surface 38A). The second member 31B has four second divided side surfaces 37B (the whole is referred to as a second divided outer peripheral surface 38B) that connects the second outer side surface 9B and the second inner side surface 33B. The side surface 11 is constituted by the first divided side surface 37A and the second divided side surface 37B (the outer circumferential side surface 12 is constituted by the first divided outer circumferential surface 38A and the second divided outer circumferential surface 38B).

The first inner side surface 33A and the second inner side surface 33B may be bonded to each other by an adhesive (adhesive layer) interposed therebetween, or both may be in direct contact and bonded. Good. Further, when determining whether or not the manufacturing method according to the present embodiment to be described later is performed, in the completed chip 5, the boundary (inner side surface 33) between the first member 31A and the second member 31B is clear. It does not have to be. That is, the completed chip 5 may appear to be integrally formed.

(Positioning structure for bonding)
When the first member 31 A and the second member 31 B are bonded to each other, the first member 31 A and the second member 31 B cross each other (specifically orthogonal) in the bonding direction (through direction of the mounting hole 25, z-axis direction). In order to be positioned, it has the following configuration.

The first member 31A has a first fitting portion 39A including at least one of a convex portion and a concave portion (one convex portion in the illustrated example) on the first inner side surface 33A. The second member 31B has a second fitting portion 39B formed of at least the other of the convex portion and the concave portion (one concave portion in the illustrated example) on the second inner side surface 33B. When the first member 31A and the second member 31B are bonded, the first fitting portion 39A and the second fitting portion 39B are fitted. Thereby, the first member 31A and the second member 31B are positioned with respect to each other in the xy direction.

In the inner surface 33, the region (outer peripheral region) other than the region where the fitting portion 39 is formed is, for example, a planar shape orthogonal to the through direction of the mounting hole 25. In the following, although there is no particular reference, this planar region may be referred to as the reference surface of the inner surface 33.

The positioning of the first member 31A and the second member 31B in the bonding direction is performed when the reference surfaces of the pair of inner side surfaces 33 directly or indirectly contact each other with an adhesive. However, the fitting part 39 may also contribute to positioning in the bonding direction.

The shape of the two fitting portions 39 is not limited as long as both fitting portions 39 are not movable relative to each other in at least one direction on the xy plane. In the example shown in the drawing, both shapes are substantially the same except that the concave or convex shapes are opposite to each other. However, as is clear from the fact that, for example, a convex portion having a circular shape in plan view that fits into a concave portion having a triangular shape in plan view cannot be moved in the planar direction, they do not necessarily have the same shape.

The fitting part 39 is annularly positioned around the hole 35 in plan view. That is, the fitting portion 39 has a frame shape with the hole 35 as an opening. In the present embodiment, the convex portion has a frame shape having the first hole 35A as an opening. The recess has a frame shape with the second hole 35B as an opening. In addition, in the plan view, the shape of the outer edge of the fitting portion 39 may be set as appropriate. For example, the shape is a similar shape in which the hole 35 and the center (graphic gravity center) coincide with each other. It is a concentric circle.

The width from the inner edge to the outer edge of the fitting portion 39 may be set as appropriate. For example, the width of the fitting portion 39 may be reduced to the extent that the minimum strength required for alignment is ensured in the convex first fitting portion 39A, or to the processing limit. Conversely, the width of the fitting portion 39 may be increased until part or all of the outer edge of the fitting portion 39 matches the outer edge of the inner side surface 33. In the case where the inner edge and the outer edge are similar as described above, the width is constant over the entire circumference of the fitting portion 39.

In the illustrated example, the outer edge of the fitting portion 39 is smaller than the outer edge of the inner side surface 33, and the reference surface of the inner side surface 33 is formed in an annular shape surrounding the fitting portion 39 on the outer side of the fitting portion 39. . In the illustrated example, the outer edge of the fitting portion 39 is larger than the outer edge (outer edge of the maximum diameter) of the outer surface 9 of the receiving portion 27 (FIG. 3). Of course, the outer edge of the fitting part 39 may be smaller than the outer edge of the outer surface 9 of the receiving part 27.

The three-dimensional shape of the first fitting portion 39A is, for example, a frustum (conical frustum in the illustrated example) in which the central axis of the first hole 35A coincides with the central axis. That is, the first fitting portion 39A has a first inclined surface 41A that is a side surface (conical surface) of the frustum and a top surface surrounding the first hole 35A. The top surface in the present embodiment is a first orthogonal surface 43 A that is the upper surface of the frustum and is orthogonal to the penetrating direction (center axis) of the mounting hole 25. The first inclined surface 41A has a width that decreases with distance from the first outer surface 9A.

On the other hand, the 2nd fitting part 39B is formed in the concave shape of the shape corresponding to a frustum, for example. That is, the 2nd fitting part 39B has the 2nd inclined surface 41B which is the inner peripheral surface which the recessed part inclined, and the bottom face surrounding the 2nd hole 35B. The bottom surface in the present embodiment is a second orthogonal surface 43 B that is orthogonal to the penetrating direction (central axis) of the mounting hole 25. The second inclined surface 41B becomes narrower as it approaches the second outer surface 9B.

The inclined surface 41 is a surface inclined with respect to the penetrating direction (z-axis direction) of the mounting hole 25. As described above, the inclined surface 41 is the cone surface or the inner peripheral surface of the concave portion corresponding thereto, so that the convex first fitting portion 39A becomes thinner toward the tip side or the concave second fitting. The joint portion 39B is inclined so as to become thinner toward the back side. From another viewpoint, the inclined surface 41 is located on the one side in the penetration direction of the mounting hole 25 (in the present embodiment, on the positive side in the z-axis direction) toward the radially outer side with the mounting hole 25 as the center.

The inclination angle with respect to the penetration direction of the inclined surface 41 may be set as appropriate, and is, for example, 20 ° or more and 70 ° or less. As can be understood from FIG. 3, the inclination angle of the inclined surface 41 with respect to the penetration direction may be, for example, greater than or equal to the inclination angle of the first receiving portion 27 A with respect to the penetration direction. In this case, for example, the first fitting portion 39A having a convex shape can be thickened on the base side to ensure the strength of the first fitting portion 39A. For example, the inclination angle is constant over the entire circumference of the inclined surface 41. The inclined surface 41 may be linear in the cross section parallel to the z-axis direction (example shown in the figure) or may be curved.

The outer edge of the inclined surface 41 is the outer edge of the fitting part 39, and is a concentric circle of the mounting hole 25 in this embodiment as described above. The inner edge of the inclined surface 41 (outer edge of the orthogonal surface 43) is, for example, a similar shape in which the inner edge matches the center (graphic gravity center), and is circular in this embodiment. Therefore, in this embodiment, the inclined surface 41 has a circular ring shape in plan view, and its width is constant over the entire circumference. A specific value of the width of the inclined surface 41 may be set as appropriate.

The orthogonal surface 43 is a plane orthogonal to the direction of penetration of the mounting hole 25. The shape of the outer edge of the orthogonal surface 43 is the shape of the inner edge of the inclined surface 41 described above, and is a concentric circle of the inner edge of the orthogonal surface 43 in this embodiment. Therefore, in the present embodiment, the orthogonal surface 43 is a circular ring, and the width thereof is constant over the entire circumference. A specific value of the width of the orthogonal plane 43 may be set as appropriate.

The first inclined surface 41A and the second inclined surface 41B have, for example, substantially the same shape over the entire surface and are bonded to each other over the entire surface. For example, the first orthogonal surface 43A and the second orthogonal surface 43B have substantially the same shape over the entire surface, and are bonded together over the entire surface. The chip 5 of the present embodiment has the first inclined surface 41A and the second inclined surface 41B. Therefore, it is possible to reduce the influence of the bonding during the formation of the chip 5 on the accuracy of the through hole. That is, the accuracy of the through hole is increased in the chip 5 formed by bonding.

(Chip division position)
As shown in FIG. 3, the seam (that is, the inner edge of the two orthogonal surfaces 43) of the two inner side surfaces 33 (more specifically, two orthogonal surfaces 43) exposed to the mounting holes 25 is Of these, the insertion portion 29 is located. The seam may be at any position in the insertion portion 29. For example, the seam may be located at the center of the insertion portion 29 in the penetration direction, or may be located on the first member 31A side (convex portion side) relative to the center, or the second member. It may be located on the 31B side (concave side) (example shown in the figure). In addition, when the joint line is located on the second member 31B side, for example, the thickness (strength) of the convex first fitting portion 39A can be ensured.

Further, the seam may be located at the boundary between the insertion portion 29 and the receiving portion 27. In the description of the present embodiment, this boundary is assumed to be a part of the insertion portion 29. That is, when the seam is located at the insertion portion 29, a mode in which the seam is located at the boundary between the insertion portion 29 and the receiving portion 27 is included.

The seams exposed on the outer peripheral side surface 12 of the two inner side surfaces 33 (more specifically, the reference surface on the outer peripheral side) may be at appropriate positions in the thickness direction. In another aspect, when the thicknesses of the first member 31A and the second member 31B are defined by the distance in the z-axis direction between the reference surface on the outer peripheral side of the inner side surface 33 and the outer side surface 9 (plane region on the center side), The thickness of the first member 31A and the second member 31B may be the same or different from each other. In the case where the first fitting portion 39A is composed only of a convex portion and the second fitting portion 39B is composed only of a concave portion as in the present embodiment, for example, the second member 31B is thicker than the first member 31A. In this case, for example, when the thickness including the fitting portion 39 is taken into consideration, it is easy to secure the thickness in both the first member 31A and the second member 31B, and it is easy to secure the strength of both.

(Notch on outer peripheral surface)
In at least one of the first member 31A and the second member 31B (both in the present embodiment), a chamfered shape 45 (first chamfered shape 45A and second chamfered shape 45B) is formed at the corner between the inner surface 33 and the divided outer peripheral surface 38. ) Is provided.

Note that the chamfered shape 45 uses the word chamfered for convenience of explanation, but the formation method is not limited to cutting the corners. For example, the chamfered shape 45 may be formed at the time of being molded by a mold. In another aspect, the term chamfered shape is not a term that refers to a manufacturing process.

The chamfered shape 45 is provided over the entire outer edge of the inner side surface 33, for example. The chamfered shape 45 may be a flat surface (for example, C surface) or a curved surface (for example, R surface). The width, inclination angle, and / or curvature of the chamfered shape 45 may be set as appropriate.

Since the chamfered shape 45 is provided on the outer edge of the inner side surface 33, a notch 47 is formed on the outer peripheral side surface 12 of the chip 5, as shown in FIG. Since the notch 47 is constituted by the chamfered shape 45, the notch 47 has a shape that becomes wider toward the outside. Further, as can be understood from the description of the chamfered shape 45, the notch 47 extends over the entire circumference of the chip 5, for example, and the size, inclination angle and / or curvature, etc. are appropriately set. Good.

(Chip manufacturing method)
FIG. 5 is a flowchart showing the procedure of the manufacturing method of the chip 5. 6 (a) to 6 (f) are schematic diagrams for explaining the outline of each step of the manufacturing method of the chip 5. FIG. The manufacturing method proceeds in order from FIG. 6 (a) to FIG. 6 (f). In the following, even if the shape or material of the member changes as the manufacturing process proceeds, the same reference numeral may be used for convenience.

First, in step ST1 of FIG. 5, the first molded body 55A (FIG. 6C) to be the first member 31A is molded. Specifically, for example, as shown in FIGS. 6A and 6B. As described above, the raw material 51 is pressed by the first divided mold 53A to the fourth divided mold 53D (hereinafter simply referred to as “divided mold 53”, which may not be distinguished from each other).

The number, arrangement, division position, role (movement), etc. of the plurality of division molds 53 may be set as appropriate. In the illustrated example, a first split mold 53A that forms the first outer surface 9A of the first member 31A and a second split mold 53B that forms the first inner surface 33A of the first member 31A are the first member 31A. The raw material 51 is pressed by approaching between the third split mold 53C that forms half of the outer peripheral side surface 12 and the fourth split mold 53D that forms the remaining half of the outer peripheral side surface 12.

The inner peripheral surface of the first hole 35A is formed by, for example, at least one inner surface of the first split mold 53A and the second split mold 53B that are close to each other (in the illustrated example, the inner surface of the first split mold 53A). The first hole 35A is not formed at the time of molding, but may be formed by stamping, cutting and / or cutting after the molding.

Although not particularly shown, the molding may be performed by injection molding in which the raw material 51 is injected into a clamped mold instead of a press.

The raw material 51 is obtained, for example, by mixing a relatively hard raw material powder as a main component, a raw material powder as a binder phase component of the hard raw material powder, and an organic substance such as a binder.

Taking the case where the chip 5 is made of cemented carbide as an example, the raw material powder includes tungsten carbide as a main component, cobalt as a binder component, tantalum carbide and titanium carbide. Examples of the binder or a role similar to the binder include paraffin or an appropriate type of resin. Note that the tip 5 is not limited to a cemented carbide, and is, for example, a diamond sintered body, a CBN (Cubic Boron Nitride) sintered body, a high-speed tool steel formed by ceramic, cermet, or powder metallurgy in a narrow sense. Powder high speed).

In step ST2 of FIG. 5, the first molded body 55A is deburred. Specifically, for example, as shown in FIG. However, flash removal is not limited to sandblasting.

Burr is generated at the joint of the plurality of split molds 53. In the example shown in the figure, it occurs at the corner (blade portion 13) between the first outer side surface 9A and the first divided outer peripheral surface 38A and at the corner portion between the first inner side surface 33A and the first divided outer peripheral surface 38A.

FIG. 6 (c) schematically shows the deburring of the corners between the first inner side surface 33A and the first divided outer peripheral surface 38A. In this deburring, for example, by setting the working time sufficiently long, the first chamfered shape 45A shown in FIG.

In steps ST3 and ST4 in FIG. 5, the work performed on the first member 31A is performed on the second member 31B in parallel with steps ST1 and ST2. This operation is the same as the molding of the first member 31A except for a specific shape. The above description of steps ST1 and ST2 can be applied to steps ST3 and ST4 by replacing "first" and "A" with "second" and "B" for the components related to the first member 31A. . FIG. 6D schematically shows that the corners of the second inner side surface 33B and the second divided outer peripheral surface 38B are chamfered in the second molded body 55B serving as the second member 31B. Has been.

In step ST5 of FIG. 5, as shown in FIG. 6 (e), the first molded body 55A and the second molded body 55B are bonded together. For example, the first molded body 55A and the second molded body 55B are brought into direct contact (without an adhesive therebetween). Since the molded body 55 is still in a state before sintering, it can be directly bonded in this way.

Note that the two molded bodies 55 may be bonded by an adhesive interposed therebetween. In this case, for example, the adhesive is applied to the entire surface (including the fitting portion 39) of one of the first inner side surface 33A and the second inner side surface 33B. Application | coating may be made by screen printing, for example. The material of the adhesive may be any appropriate material, for example, an inorganic adhesive such as a ceramic adhesive.

During the bonding, the first molded part 55A and the second molded body 55B are aligned by fitting the first fitting part 39A and the second fitting part 39B.

The two molded bodies 55 may be positioned in the xy direction by pins 57 (shown by dotted lines in FIG. 6E) inserted through the first holes 35A and the second holes 35B. In this case, the two inclined surfaces 41 may contribute to positioning with higher accuracy than the pin 57 by, for example, the positioning action by mutual contact described above. Conversely, the play between the pin 57 and the hole 35 may be increased.

In step ST6 of FIG. 5, as shown in FIG. 6 (f), the bonded two molded bodies 55 are fired (a heat treatment step is performed). Thereby, the sintered compact used as the chip | tip 5 is formed. At this time, when the molded body 55 contains a binder, the binder is evaporated or burned and removed from the sintered body.

Thereafter, although not particularly illustrated, the cutting edge of the sintered body may be ground or polished (honed) to adjust the roundness of the cutting edge. Thereby, the chip 5 is obtained.

Note that the above description of the procedure is only an outline of an example, and may be modified as appropriate. For example, when the molded body 55 includes a binder, a process (such as calcination) for removing a part of the binder from the molded body may be performed at an appropriate time before firing. For example, a hard film may be formed after honing.

(Modification of manufacturing method)
FIG. 7 is a flowchart showing the procedure of the manufacturing method according to the modification.

In the flowchart shown in FIG. 5, the two molded bodies 55 were bonded together and fired. On the other hand, in the flowchart shown in FIG. 7, after the two molded bodies 55 are fired, the sintered bodies are bonded to each other. Specifically, it is as follows.

In FIG. 7, steps ST1 to ST4 are the same as steps ST1 to ST4 in FIG.

In step ST11, the first molded body 55A is fired, and in step ST12, the second molded body 55B is fired. These steps are the same as step ST6 in FIG. 5 except that the two molded bodies 55 are not bonded together. Note that the firing of the first molded body 55A and the firing of the second molded body 55B may be performed separately or together.

In step ST13, the sintered body to be the first member 31A and the sintered body to be the second member 31B are bonded together. Note that this bonding requires that an adhesive be interposed between the first inner side surface 33A and the second inner side surface 33B, unlike step ST5 of FIG. The method of applying the adhesive and the like are as described in the explanation of step ST5 in FIG. However, unlike step ST5 of FIG. 5, since the baking is not performed after step ST13, the adhesive may be an organic adhesive.

Since deburring in steps ST2 and ST4 may be performed before bonding, it may be performed after firing (steps ST11 and ST12). Further, honing for finally adjusting the blade portion 13 may be performed after baking, and thus may be performed before bonding.

Other than that, the process for removing the binder from the molded body (such as calcination) may be performed at an appropriate time before firing, as in FIG.

As described above, in the present embodiment, the chip 5 includes the first member 31A and the second member 31B. Each of the first member 31 A and the second member 31 B has an outer surface 9, an inner surface 33 on the back surface thereof, and a hole 35 penetrating from the outer surface 9 to the inner surface. The first inner side surface 33A and the second inner side surface 33B are bonded together so that the first hole 35A and the second hole 35B constitute one through hole (mounting hole 25) (they are joined to face each other). )

In the present embodiment, each of the first inner side surface 33A and the second inner side surface 33B has a frame-like fitting portion 39 having at least one of the convex portion and the concave portion or the other and having the hole 35 as an opening. The first fitting portion 39A and the second fitting portion 39B are fitted.

Therefore, for example, the first member 31A and the second member 31B are aligned by the two fitting portions 39 in the vicinity of the hole 35 and over the entire circumference of the hole 35. As a result, the first hole 35A and the second hole 35B are aligned with high accuracy, and the accuracy of the mounting hole 25 constituted by the two holes 35 is improved. Further, the accuracy of the mounting hole 25 is improved, so that the positioning accuracy of the chip 5 with respect to the holder 3 is improved, and consequently the cutting accuracy by the cutting tool 1 is improved.

Furthermore, in this embodiment, the seam exposed to the attachment hole 25 of the two inner side surfaces 33 (two fitting portions 39) is located in the insertion portion 29.

Therefore, for example, alignment can be performed stably. Further, for example, since the two inner side surfaces 33 are not exposed on the inner surface of the receiving portion 27, there is a very low possibility that the seam affects the accuracy of the inner surface of the receiving portion 27. For example, there is no possibility that a minute level difference in the seam is generated on the inner surface of the receiving portion 27. As a result, the accuracy of contact of the screw head 7b with the inner surface of the receiving portion 27 is improved, and the positioning accuracy of the chip 5 with respect to the holder 3 by the screw 7 is improved. As a result, the cutting accuracy by the cutting tool 1 is improved.

In the present embodiment, the first inclined surface 41A and the second inclined surface 41B are bonded to each other (joined to face each other).

Therefore, the first member 31A and the second member 31B can be positioned with high accuracy. For example, unlike the present embodiment, it is assumed that the outer peripheral surface of the convex portion (first inclined surface 41A) and the inner peripheral surface of the concave portion (second inclined surface 41B) are parallel to the penetration direction of the mounting hole 25. In this case, in order to fit the convex portion into the concave portion, a gap (so-called play) is required between the outer peripheral surface of the convex portion and the inner peripheral surface of the concave portion. As a result, the positioning accuracy decreases by the amount of play. However, in this embodiment, since the convex portion can be inserted into the concave portion without such play, positioning accuracy is improved.

In the present embodiment, each of the two fitting portions 39 has an orthogonal surface 43 that is orthogonal to the direction of penetration of the mounting hole 25. The two orthogonal surfaces 43 are bonded to each other (joined to face each other).

Therefore, for example, positioning accuracy is improved. Specifically, for example, in the inclined surface 41, the force in the penetration direction of the mounting hole 25 generated when the first member 31A and the second member 31B are brought close to each other is the component force in the direction orthogonal to the inclined surface 41. Although it acts on the inclined surface 41 as a component force in the direction along the inclined surface 41, in the orthogonal surface 43, the force in the penetrating direction of the mounting hole 25 is orthogonal as the force in the direction orthogonal to the orthogonal surface 43. Act on 43. In other words, the two orthogonal surfaces 43 facing each other reliably react with each other. As a result, positioning of the mounting hole 25 in the penetrating direction can be performed stably.

In the present embodiment, at least one of the intersecting ridge portion between the first inner side surface 33A and the first divided outer peripheral surface 38A and the intersecting ridge portion between the second inner side surface 33B and the second divided outer peripheral surface 38B (the present embodiment). The chamfered shape 45 is located on both sides, so that a notch 47 is formed on the outer peripheral side surface 12 of the chip 5.

Therefore, for example, in an embodiment in which an adhesive is interposed between the first inner side surface 33A and the second inner side surface 33B, when excess adhesive overflows to the outer peripheral side surface 12 side, the adhesive protrudes onto the outer peripheral side surface 12. Is less likely to form. Further, even when no adhesive is present, for example, the possibility that the seam becomes a protrusion is reduced. As a result, for example, the possibility that the positioning accuracy of the outer peripheral side surface 12 with respect to the recess 3r of the holder 3 is lowered due to the protrusion is reduced. As a result, the possibility of a reduction in cutting accuracy by the cutting tool 1 is reduced.

Second Embodiment
In the second and subsequent embodiments, the same or similar configurations as those already described may be denoted by the same reference numerals as those already described, and description thereof may be omitted. Even when the configuration corresponding to (similar to) the configuration already described is given a reference different from the reference given to the configuration already described, the matters not particularly mentioned are the same as those already described. It is.

FIG. 8 is an exploded perspective view corresponding to FIG. 4 schematically showing the configuration of the cutting tool tip 205 according to the second embodiment.

The chip 205 is configured by bonding the first inner side surface 233A of the first member 231A and the second inner side surface 233B of the second member 231B in the same manner as the chip 5 of the first embodiment. However, the shapes of the first fitting portion 239A and the second fitting portion 239B are different from the shapes of the first fitting portion 39A and the second fitting portion 39B of the first embodiment. Others are the same as in the first embodiment.

The first fitting portion 239A has a frustum shape, for example, similarly to the first fitting portion 39A of the first embodiment. However, unlike the first embodiment, the shape of the bottom surface (bottom side surface) of the frustum is non-circular, for example, elliptical. Note that the top surface of the frustum is circular, as in the first embodiment. From another viewpoint, the outer peripheral surface (first inclined surface 241A) of the first fitting portion 239A is a first region in which distances (for example, L1, L2) from the central axis of the first hole 35A (mounting hole 25) are different from each other. 242A-1 and second region 242A-2 (a plurality of regions) are provided at different positions in the circumferential direction.

The second fitting portion 239B has a concave shape corresponding to the frustum, for example, similarly to the second fitting portion 39B of the first embodiment. In another aspect, the inner peripheral surface (second inclined surface 241B) of the second fitting portion 239B has a plurality of distances (for example, L1, L2) that are different from the central axis of the second hole 35B (mounting hole 25). The third region 242B-1 and the fourth region 242B-2 are provided at different positions in the circumferential direction.

The first region 242A-1 and the third region 242B-1 are bonded from the inner edge to the outer edge. Similarly, the second region 242A-2 and the fourth region 242B-2 are bonded from the inner edge to the outer edge. Therefore, the first fitting portion 239A and the second fitting portion 239B are positioned so as not to rotate relative to each other around the center axis of the mounting hole 25.

In the description of this embodiment, the term “ellipse” does not require a mathematically accurate ellipse. For example, an ellipse may include an ellipse in which both ends of two semicircles are connected by a straight line (sometimes called an ellipse).

Further, since the distances L1 and L2 are distances from the central axis of the mounting hole 25, they are orthogonal to the central axis (not inclined with respect to the xy plane). When the distances from the central axis are different, the distances L1 and L2 compared with each other are assumed to be at the same position in the z-axis direction.

Further, from the viewpoint of regulating the relative rotation around the central axis, it is only necessary to realize a configuration in which the non-circular shapes are fitted to each other at any position in the z-axis direction. Therefore, the first region 242A-1 and the second region 242A-2 (or the third region 242B-1 and the fourth region 242B-2) have different distances from the central axis of the mounting hole 25 over the entire surface. It may be defined as a region (in this embodiment, a region that does not include the boundary with the orthogonal surface 43 of the inclined surface 241), and a part of which the distance from the central axis of the mounting hole 25 is different from each other It may be grasped as an area to include. In the description of the present embodiment, the former is basically assumed.

In the first region 242A-1 and the second region 242A-2, the inclination angles with respect to the penetration direction of the mounting hole 25 are different from each other. The same applies to the third region 242B-1 and the fourth region 242B-2.

Specifically, the first region 242A-1 and the third region 242B-1, which have a relatively long distance (L1) from the central axis of the mounting hole 25, have a distance (L2) from the central axis of the mounting hole 25. The inclination angle with respect to the penetration direction of the mounting hole 25 is larger than that of the relatively short second region 242A-2 and fourth region 242B-2.

Therefore, for example, when the first fitting portion 239A is inserted into the second fitting portion 239B as in the present embodiment, the longer the distance from the central axis, the xy direction due to the sliding of the inclined surface 241. The amount of movement can be increased and positioning can be performed suitably. Further, if the change in the inclination angle is made continuously in the circumferential direction, when the first fitting portion 239A is inserted into the second fitting portion 239B, the inclined surface 241 slides in the rotational direction. It is also expected that positioning in the rotational direction of both is performed.

If the tilt angle is not constant depending on the position in the z-axis direction, the tilt angle may be compared at the same position in the z-axis direction. Further, in this case, the above-described magnitude relationship between the tilt angles is established only in a part of the first region 242A-1 and the second region 242A-2 (or the third region 242B-1 and the fourth region 242B-2). It may be established on the entire surface.

The outer edge (outer peripheral side surface 12) in a plan view of the chip 5 is a first side surface (rectangular short side in the present embodiment) and a second side surface (main book) having a shorter distance from the central axis of the mounting hole 25 than the first side surface. In the embodiment, it has a rectangular long side). The first region 242A-1 and the third region 242B-1 are located between the mounting hole 25 and the first side surface, and the second region 242B-1 and the fourth region 242B-2 are connected to the mounting hole 25. It is located between the second side surface.

Therefore, for example, contrary to the above, the longitudinal direction of the fitting part 239 is compared with the aspect in which the longitudinal direction of the fitting part 239 is the short direction of the chip 5 (this aspect is also included in the present invention). It is easy to lengthen the length. When the length in the longitudinal direction (r) of the fitting portion 239 is increased, the relative rotation angle (θ (rad)) between the first fitting portion 239A and the second fitting portion 239B around the attachment hole 25 is set. ) Relative to the outer edges of the two fitting parts 239 (r × θ). As a result, positioning accuracy in the rotational direction is improved by positioning the two fitting portions 239 on the outer edge side.

Further, for example, it is advantageous for securing the strength of the first member 231A and the second member 231B as compared with the aspect in which the longitudinal direction of the fitting portion 239 is the short direction of the chip 5. Specifically, for example, in the first member 231A, the convex first fitting portion 239A functions as a rib for increasing the moment of inertia in the longitudinal direction in which bending deformation is likely to occur. On the other hand, in the second member 231B, for example, the probability that the concave first fitting portion 239A forms a deep recess in the z-axis direction over the entire width (the entire y direction) of the second member 231B is reduced. As a result, the possibility that a yz cross section having an extremely small cross sectional second moment is formed in a part of the longitudinal direction (x direction) where bending deformation is likely to occur is reduced.

As described above, in the present embodiment, like the first embodiment, the fitting portion 39 has a frame shape with the hole 35 as an opening, and the inner surface 233 bonded to each other is exposed to the mounting hole 25. The eye is located in the insertion part 29 (FIG. 3), and the fitting part 239 has the feature of having the inclined surface 241. Therefore, the same effect as the first embodiment is achieved. For example, the influence of bonding on the mounting hole 25 can be reduced.

Further, in the present embodiment, the convex portion of the first fitting portion 239A and the concave portion of the second fitting portion 239B are perpendicular to the penetrating direction of the mounting hole 25, and the first region 242A-1 to the fourth region 242B-2. The shape of the cross section (xy cross section) that crosses is elliptical.

Therefore, for example, compared with an aspect in which the outer edge shape of the fitting portion 239 is a polygon (this aspect is also included in the technology according to the present disclosure), it is not necessary to form a minute corner portion shape, Is easy. In addition, such a corner portion is deformed by stress concentration, and the risk of inconvenience that the deformation accuracy is lowered due to the deformation is low. Furthermore, as described above, since the change in the inclination angle of the inclined surface 241 in the circumferential direction becomes continuous, the positional deviation in the rotational direction can be easily eliminated by the sliding of the inclined surface 241.

<Third Embodiment>
FIG. 9 is an exploded perspective view corresponding to FIG. 4 and schematically showing the configuration of the cutting tool tip 305 according to the third embodiment.

The chip 305 is configured by bonding the first inner side surface 333A of the first member 331A and the second inner side surface 233B of the second member 331B in the same manner as the chip 5 of the first embodiment. However, the shapes of the first fitting portion 339A and the second fitting portion 339B are different from the shapes of the first fitting portion 39A and the second fitting portion 39B of the first embodiment. Others are basically the same as those in the first embodiment.

The fitting part 339 is formed in a frame shape including at least a convex part or a concave part and having the hole 35 as an opening, like the fitting part 39 of the first embodiment. Further, like the fitting portion 239 of the second embodiment, it is non-circular in plan view, and is provided so that the longitudinal direction thereof substantially coincides with the longitudinal direction of the chip 305. However, the fitting part 339 is polygonal, and a part of the outer edge coincides with a part of the chip 305. Specifically, it is as follows.

The first fitting portion 339A is formed of a convex portion and is rectangular in plan view. In a plan view, the long side of the first fitting portion 339A is, for example, parallel to the long side of the chip 5 (the long side of the outer edge of the first inner side surface 333A). The first fitting portion 339A reaches the outer edge of the first inner side surface 333A in the longitudinal direction, and the short side of the first fitting portion 339A is a part of the short side of the first inner side surface 333A. . That is, the first fitting portion 339A is smaller than the first inner side surface 333A in the short side direction and extends over the first inner side surface 333A in the long side direction.

2nd fitting part 339B consists of a recessed part, and is made into the rectangle in planar view. In a plan view, the long side of the second fitting portion 339B is parallel to, for example, the long side of the chip 5 (the long side of the outer edge of the second inner side surface 333B). The second fitting portion 339B reaches the outer edge of the second inner side surface 333B in the longitudinal direction, and the short side of the second fitting portion 339B is a part of the short side of the second inner side surface 333B. . That is, the second fitting portion 339B is smaller than the second inner side surface 333B in the short side direction and extends over the second inner side surface 333B in the longitudinal direction.

And the 1st fitting part 339A and the 2nd fitting part 339B fit, and the 1st member 331A and the 2nd member 331B are positioned mutually. Specifically, the positioning by the fitting portion 339 is performed in the short direction (y direction) and the rotation direction. The positioning in the longitudinal direction (x direction) may be performed by, for example, the pin 57 shown in FIG.

Therefore, for example, the fitting portion 339 can be made as long as possible in its longitudinal direction. As a result, the effect of relatively increasing the amount of movement (r × θ) with respect to the relative rotation angle (θ) described in the second embodiment is increased, and the positioning accuracy in the rotation direction is improved.

Since the fitting portion 339 is non-circular in plan view, the outer peripheral surface or the inner peripheral surface has a plurality of regions whose distances from the central axis of the mounting hole 25 are different from each other as in the second embodiment. Can be seen as. For example, the outer peripheral surface of the first fitting portion 339A (convex portion) has a first region 342A-1 and a second region 342A-2 that are different from each other in distance (for example, L11, L12) from the central axis of the mounting hole 25. is doing. The inner peripheral surface of the second fitting portion 339B (concave portion) has a third region 442B-1 and a fourth region 442B-2 that are different in distance (for example, L11, L12) from the central axis of the mounting hole 25. Yes. The first region 342A-1 and the third region 342B-1 are bonded together, and the second region 342A-2 and the fourth region 342B-2 are bonded together.

In addition, the 1st fitting part 339A has the 1st inclined surface 341A and the 1st orthogonal surface 343A similarly to other embodiment. Similarly, the 2nd fitting part 339B has the 2nd inclined surface 341B and the 2nd perpendicular surface 343B like other embodiments. Then, the first inclined surface 341A and the second inclined surface 341B are bonded together, and the first orthogonal surface 343A and the second orthogonal surface 343B are bonded together. Further, although not shown in FIG. 9, the chamfered shape may be located at the corners of the inner side surface 333 and the divided outer side surface (reference numeral omitted) as in the other embodiments.

As described above, in the present embodiment, like the first embodiment, the fitting portion 339 has a frame shape having the hole 35 as an opening, and the inner surface 333 bonded to each other is exposed to the mounting hole 25. The eyes are located in the insertion portion 29 (FIG. 3), and the fitting portion 339 has a feature such as having an inclined surface 341. Therefore, the same effect as the first embodiment is achieved. For example, the influence of bonding on the mounting hole 25 can be reduced. Further, in the present embodiment, similarly to the second embodiment, the first fitting portion 339A (convex portion) and the second fitting portion 339B (concave portion) are non-circular, so that positioning in the rotational direction is also highly accurate. To be made.

In the first to third embodiments described above, the mounting hole 25 is an example of a through hole, the first hole 35A is an example of a hole part, and the second hole 35B is an example of a hole part. The

fitting portions

39A, 239A, and 339A are examples of convex portions, the second

fitting portions

39B, 239B, and 339B are examples of concave portions, and the side surface 11 that forms the short side of the chip 5 is the first side surface. It is an example, and the side surface 11 constituting the long side of the chip 5 is an example of the second side surface.

The technology according to the present disclosure is not limited to the above embodiment, and may be implemented in various modes.

The method of attaching / detaching the chip to / from the holder is not limited to using a screw, and may be a clamp or a combination of a screw and a clamp. Further, the chip may be fixed to the holder without using the through-hole, such as being fixed to the holder by brazing, while the through-hole through which the screw can be inserted is formed.

Tip is not limited to the end mill. For example, the tip may be for a cutting tool or a drill, or may be for a milling machine other than the end mill. Moreover, a chip | tip is not limited to what has a blade part in the corner | angular part of an outer surface (main surface) and an outer peripheral surface (side surface), You may have a blade part in an outer peripheral surface.

The through holes are not limited to those having receiving portions on both sides of the insertion portion, and may have receiving portions only on one side of the insertion portion.

The first fitting portion is not limited to a single convex portion, and similarly, the second fitting portion is not limited to a single concave portion. For example, each of the first fitting portion and the second fitting portion may alternately have one or more convex portions and one or more concave portions in the circumferential direction of the through hole, or center the through hole. And having one or more convex portions and one or more concave portions alternately. Further, there may be a break in a part of the frame shape (for example, a range of less than 30 ° in the central angle).

The shape of the fitting part is not limited to a circle, an ellipse and a rectangle. For example, it may be a polygon other than a rectangle, or may be a shape in which curves and straight lines are appropriately combined. Further, for example, in the third embodiment, the long sides of the fitting portion 339 may not be parallel to each other, and the planar shape of the fitting portion 339 may be a trapezoid or a hexagon. In this case, even if the fitting part 339 extends over the entire longitudinal direction of the inner side surface 333 (even if part of the edge part of the fitting part 339 coincides with part of the edge part of the inner side surface 333), the x direction Can be positioned. Further, for example, the diameter of the circular shape of the first embodiment or the elliptical shape of the second embodiment may be increased, and a part of the outer edge of the fitting portion may be a part of the outer edge of the inner surface. Moreover, the fitting part may be comprised only from the inclined surface, without having an orthogonal surface. For example, the first and second fitting portions may be configured by a cone-shaped convex portion and a concave portion having a shape corresponding thereto.

DESCRIPTION OF SYMBOLS 1 ... Cutting tool, 5 ... Cutting tool tip, 9A ... 1st outer side surface, 9B ... 2nd outer side surface, 25 ... Mounting hole (through-hole), 27 ... Receiving part, 29 ... Insertion part, 31A ... 1st member , 31B ... second member, 33A ... first inner surface, 33B ... second inner surface, 35A ... first hole, 35B ... second hole, 39A ... first fitting part (convex part), 39B ... second fitting Joint part (concave part), 41A ... 1st inclined surface, 41B ... 2nd inclined surface.

Claims

A first member having a first outer surface, a first inner surface on the back surface thereof, and a first hole penetrating from the first outer surface to the first inner surface;
A second outer surface, a second inner surface on the back surface thereof, and a second member having a second hole penetrating from the second outer surface to the second inner surface;
Have
The first inner surface and the second inner surface are opposed to each other such that the first hole and the second hole constitute one through hole;
The first inner surface has a frame-shaped convex portion having the first hole as an opening, and the convex portion has a first inclined surface so that the width becomes narrower as the distance from the first outer surface is increased. Have
The second inner surface has a frame-shaped recess having the second hole as an opening, and the recess has a second inclined surface so that the width becomes narrower as it approaches the second outer surface. And
The cutting tool tip in which the first inclined surface and the second inclined surface are opposed to each other.
The convex portion has a top surface surrounding the first hole,
The recess has a bottom surface surrounding the second hole;
The cutting tool tip according to claim 1, wherein the top surface and the bottom surface face each other.
The first inclined surface has a first region and a second region having a shorter inclined surface length than the first region at different positions in the circumferential direction.
The second inclined surface has a third region and a fourth region having a shorter inclined surface length than the third region at different positions in the circumferential direction.
The first region and the third region are opposed to each other;
The cutting tool tip according to claim 1, wherein the second region and the fourth region are opposed to each other.
The cutting tool tip according to claim 3, wherein the first region and the third region have an inclination angle with respect to the central axis larger than that of the second region and the fourth region.
The first inner surface and the second inner surface have a shape having a longitudinal direction and a short direction perpendicular to the longitudinal direction in plan view,
The convex portion is smaller than the first inner surface in the short direction and extends over the entire first inner surface in the longitudinal direction.
5. The cutting tool tip according to claim 3, wherein the recess is smaller than the second inner surface in the short direction and extends over the entire second inner surface in the longitudinal direction.
The outer peripheral side surface has a first side surface and a second side surface whose distance from the through hole is shorter than the first side surface,
The first region and the third region are located between the through hole and the first side surface,
The cutting tool tip according to any one of claims 3 to 5, wherein the second region and the fourth region are located between the through hole and the second side surface.
The cutting tool tip according to any one of claims 1 to 6, wherein the through hole at a position where the convex portion and the concave portion oppose each other has an elliptical cross-sectional shape perpendicular to the central axis.
The cutting tool according to any one of claims 1 to 7, wherein at least one of the first inner surface and the second inner surface is provided with a notch at an intersection ridge with the adjacent outer peripheral side surface in each of the first inner surface and the second inner surface. Chip.
In the cross section along the penetration direction, the through hole,
An insertion portion having a constant width in a direction perpendicular to the penetration direction;
A receiving portion having a width in a direction perpendicular to the penetrating direction from the insertion portion to the outside of the through hole;
The cutting tool tip according to any one of claims 1 to 8, wherein a joint between the convex portion and the concave portion is located in the insertion portion.
Forming a first member having a first outer surface, a first inner surface on the back surface thereof, and a first hole penetrating from the first outer surface to the first inner surface;
Forming a second member having a second outer surface, a second inner surface on the back surface thereof, and a second hole penetrating from the second outer surface to the second inner surface;
Joining the first inner surface and the second inner surface to face each other so that the first hole and the second hole constitute one through hole;
Have
In the step of forming the first member, a frame-like convex portion having the first hole as an opening is formed on the first inner side surface, and the convex portion has a width as it is separated from the first outer side surface. The first inclined surface is formed so as to be narrow,
In the step of forming the second member, a frame-shaped recess having the second hole as an opening is formed on the second inner surface, and the width of the recess becomes narrower as the second outer surface is approached. A second inclined surface is formed,
In the joining step, the projection and the recess are fitted with the first inclined surface and the second inclined surface facing each other.