JP2000140980A - Production of metal member with through hole and metal member with through hole - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of a metal member with a through hole of a small and long size capable of securing a precision for a formed position and straightness of the through hole well. SOLUTION: A through hole 21 is formed beforehand by drilling or backward extrusion and blanking for a metal stock having a low aspect ratio before forging. When an aspect ratio of the metal stock 20 is small, a forming precision of the through hole 21 is relatively easily secured. Reducing forging is conducted while inserting a mandrel 55 in the through hole 21. The stock 20, while being reduced in an axial cross section outer diameter and through hole inner diameter by a die hole 57 of a forging die 56, is formed to a non round shape in its outer shape corresponding to a die hole inner face. On the other hand, a through hole 21 inner face is restricted by the mandrel 55 and is formed so as to have a corresponding inner diameter. At this time, the mandrel 55 is pressed into a die hole 57 roughly in isotropy in the peripheral direction through the stock 20 not to cause deflection. As a result, a forming precision of the through hole 2 finally formed for an obtained metal member 1 is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a metal member having a through hole and a metal member having a through hole, and more particularly to a non-circular shape such as a small-sized one having a large aspect ratio of a through-hole and having a square cross-sectional outer shape. The present invention relates to a method for manufacturing a metal member with a through hole and a metal member with a through hole.

[0002]

2. Description of the Related Art A metal member having a through hole as described above, for example, having a square cross section, has conventionally been manufactured as follows. First, as shown in FIG. 9 (a), a round bar-shaped material 100 as shown in FIG.
By performing a drawing process using 02, a square bar-shaped material 101 corresponding to the product outer shape is obtained. Next, FIG.
As shown in (d), the square rod-shaped material 101 is cut into a square material 103, and a drill 104 is used to drill a hole in the center of the cross section in the axial direction, thereby forming a through hole 105 as shown in (d). Is obtained.

[0003]

However, in the above method, in the case of a long member having a small cross-sectional dimension, a drill having a large diameter must be formed with a small-diameter drill. There are easy problems. Therefore, as shown in FIG. 10A, the precision of the formation position of the through-hole 105 is impaired, or as shown in FIG. Become. For example, when it is attempted to form a through hole having an inner diameter of about 7 mm in a square material having a cross section of about 10 × 15 mm and a length of about 60 mm by the above method, the straightness of the through hole 105 is the maximum. It may worsen to about 38/100.

An object of the present invention is to provide a method for manufacturing a small and long metal member with a through hole, which can ensure the formation position of a through hole and the accuracy of straightness, and a metal member with a through hole that can be manufactured by the method. To provide.

[0005]

Means for Solving the Problems and Functions / Effects In order to solve the above-mentioned problems, a first method of manufacturing a metal member having a through hole according to the present invention is as follows. For a metal material having a length of 10 to 30 mm and an axial length L ′ of 15 to 36 mm, the inner diameter d ′ is 5 to 8 m at the center of the axial cross section.
m, wherein L ′ / d ′ is 3 to 4.5 in the axial direction by drilling a drilled hole to produce a metal material with a through hole, and a hole inner diameter after the processing. Forging with a surface reduction rate of 40 to 70% or less by passing a metal material with a through hole in the axial direction through a non-circular die hole formed in a forging die while inserting a mandrel defining the Is performed, whereby the outer shape of the shaft cross section becomes a non-circular shape corresponding to the die hole, and the outer diameter of the shaft cross section of the processed member is D, and the inner diameter and the length of the through hole are d and L, respectively, and L / d Is 5 to 10, D is 7 to 18 mm, d
And a drawing forging step of obtaining a metal member with a through hole of 5 to 8 mm.

[0006] Similarly, the second is that a metal material is extruded backward to form a circular shaft cross section, whose outer diameter D 'is 10 to 30 mm and whose axial length L' is 15 to 3 mm.
Extrusion step of producing a metal material with a bottomed hole of 6 mm, having an axial bottomed hole with an inner diameter d ′ of 5 to 8 mm in the center of the cross section, and punching the bottom of the metal material with the bottomed hole A punching step of making the bottomed hole into a through hole having a L '/ d' of 3 to 4.5 to produce a metal material with a through hole, and inserting a mandrel defining the inner diameter of the hole after processing into the through hole. While the holed metal material is passed through the non-circular die hole formed in the forging die in the axial direction, a drawing forging process with a reduction in area of 70% or less is performed. L / d is 5 to 10 and D is 7 to 18 m, where D is the outer diameter of the cross section of the member after processing, and d and L are the inner diameter and length of the through hole, respectively.
a forging step of obtaining a metal member with through holes having m and d of 5 to 8 mm.

In the present invention, "the outer shape of the shaft cross section is a non-circular shape" means that, as shown in FIG. 7, the outer shape T of the shaft cross section (a cross section formed by a plane orthogonal to the axis) is represented by a geometrical shape. When an inscribed circle IC and a circumscribed circle OC centered on the center of gravity G are drawn, and a virtual reference circle SC located between the inscribed circle IC and the circumscribed circle OC is drawn, the cross-sectional outline A shape in which a part of T is located inside the reference circle SC and another part is located outside the reference circle SC. For example, a polygonal shape such as a triangular shape and a quadrangular shape (square, rectangular, etc.) and an elliptical shape can be exemplified. FIG. 7A shows an example in which the cross-sectional outline T is square, and FIG. 7B shows an example in the case of an elliptical shape. Further, the shaft cross-sectional diameter D of the processed member having a non-circular shape is defined as the diameter of a circle having the same area as the shaft cross-section.

According to the method of the present invention, the inner diameter d of the through hole is
The ratio L / d of the length L to the length L is as large as 5 to 10, and D is 7
In a small metal member having a diameter of about 18 mm and L of about 40 to 100 mm, the formation position of a through hole and the accuracy of straightness (hereinafter, collectively referred to as "formation accuracy") are compared with those of the conventional method. It can be dramatically increased.

In the above method, a through hole is previously formed in a material having a relatively small aspect ratio before forging by drill cutting or backward extrusion + punching. This is because if the aspect ratio of the material is small, the accuracy of forming the through holes is relatively easy to secure. Then, drawing forging is performed by a forging die while inserting a mandrel into the through hole. The material is formed into a non-circular shape whose outer shape corresponds to the inner surface of the die hole while the cross section is reduced by the die hole of the forging die. On the other hand, the inner surface of the through hole is formed so as to have a corresponding inner diameter while being constrained by the mandrel. At this time, since the mandrel is pressed substantially isotropically in the circumferential direction through the material in the die hole, a radius is unlikely to be generated. As a result, it is considered that the formation accuracy of the through-hole finally formed in the obtained metal member is improved.

More specifically, by the method of the present invention, the center axis of the through hole is O and the center axis of the metal member with the through hole is C, and the coaxiality of O to C is assured with high accuracy of φ0.15 mm or less. Will be able to Further, the straightness of the through hole can ensure an accuracy of 20/100 or less. For example, regarding straightness, 38 /
What has deteriorated to about 100 can be reduced to about half or less by the method of the present invention. In the present invention, the coaxiality is JISB002
The straightness defined in 11.1 of 1 is adopted, and the straightness defined in 1.2 of JIS B0021 is similarly adopted.

In order for the precision of the through-hole formation position and straightness to be within the above ranges in the member after drawing forging, it is necessary to ensure the precision of formation of the through-hole formed in the material before forging. is important. As long as the value of L '/ d' of the through-hole of the material is 4.5 or less, any of the drilling or backward extrusion employed in the first and second methods of the present invention may be used. Necessary and sufficient accuracy of forming the through hole can be secured. In this case, in order to set the coaxiality and the straightness of the through hole of the processed member to the above-described range, the coaxiality of the through hole of the material before the processing is φ0.10 mm or less, and the straightness is 3/100 or less. It is desirable that

The value of L / d of the obtained metal member is 5
If it is less than 1, a member having a high precision of forming a through-hole may be obtained by a conventional method, so that it is meaningless to apply the present invention. On the other hand, when L / d exceeds 10, it becomes impossible to secure the formation accuracy of the through hole. L / d is preferably 5 to 10
It is good to set to.

Further, if the axial cross-sectional outer shape D of the member is less than 10 mm or the inner diameter d of the through hole is less than 3 mm, the precision of forming the through hole cannot be ensured. On the other hand, the inner diameter d is 8m
A through-hole exceeding m can be sufficiently achieved by a known method such as drill cutting or lathe cutting, so that it is meaningless to apply the present invention. On the other hand, when the axial cross-sectional shape D exceeds 30 mm, the thickness of the member to be manufactured becomes too large because the inner diameter d of the through-hole is 3 to 8 mm, and it becomes difficult to manufacture by drawing forging. D is desirably 10 to 30 mm
And d is desirably 5 to 8 mm. When L is out of the range of 15 to 36 mm, d
Is set in the above range, L / d is set to 5 to 10
In the range of

The reason for reducing the surface reduction rate of the material at the time of drawing forging to 70% or less is that if it exceeds 70%, it is not possible to ensure the precision of forming through holes in the processed member. On the other hand, if the area reduction rate is not 50% or more, L ′ / d ′ is 4.
It becomes impossible to manufacture a member having an L / d of 5 or more using a material of 5 or less.

On the other hand, if the material before processing has an outer diameter D ′ of less than 10 mm in the axial cross section, it becomes difficult to form a through hole having required accuracy by drilling or backward extrusion. On the other hand, if D ′ exceeds 30 mm, it becomes impossible to obtain a member having an outer diameter D of 18 mm or less under the condition of a surface reduction rate of 70% or less. When the inner diameter d 'of the through hole of the material is less than 5 mm, it is difficult to form the through hole with necessary forming accuracy by drilling or backward extrusion. On the other hand, d 'is 8
If it exceeds mm, it becomes impossible to reduce the inner diameter d of the through-hole of the processed member to 3 mm or less under the condition of a surface reduction rate of 70% or less. Note that D ′ is desirably 15 to 25 mm, and d ′ is desirably 6 to 8 mm.

On the other hand, when L '/ d' is less than 3, it becomes impossible to make L / d of the processed member 5 or more under the condition of a surface reduction rate of 70% or less. L ′ / d ′ is 4.
If it exceeds 5, it is not possible to sufficiently secure the formation accuracy of the through hole formed in the material. L '/ d' is desirably 3 to 4
It is good to do. When L ′ is out of the range of 15 to 36 mm, d ′ is set to the above range,
It is impossible to make L ′ / d ′ in the range of 3 to 4.5.

In the first and second aspects of the method of the present invention,
The formation of through-holes in the material is formed by drill cutting or backward extrusion, respectively. The first method of the present invention that employs drill cutting has a higher precision in forming the through-holes in the material and, consequently, the through-holes of the obtained members. It is possible to further improve the formation accuracy of the. In this case, the through-hole of the material has a coaxiality of φ0.20 mm or less, a straightness of 20/100 or less,
The coaxiality of the through hole of the member is φ0.10 m.
m or less, or a straightness of 10/100 or less, it is possible to achieve even better values.

Next, the metal member with a through-hole according to the present invention has a non-circular cross-sectional outer shape, an axial through-hole formed at the center of the axial cross-section, and has an outer diameter of the axial cross-section D, and an inner diameter of the through-hole. L / d is 5 to 10, D is 7 to 18 mm, and d is 5 to 8 mm, where d and L are the lengths, respectively.
A cutting mark in the circumferential direction and a forging mark in the axial direction are formed, and the center axis of the through hole is O, the center axis of the member itself is C, and the coaxiality of O to C is φ0.15 m.
m or less, and the straightness of the through hole is 20/100 or less.

The above-mentioned metal member with a through hole can be manufactured by the first of the manufacturing method of the present invention, and by adopting the manufacturing method, the through hole has a coaxiality of φ0.15 mm or less, and With a straightness of 20/100 or less, it has excellent forming accuracy which cannot be achieved by the conventional manufacturing method. In this case, the coaxiality can be φ0.10 mm or less, and the straightness can be 10/100 or less.

On the other hand, circumferential cutting marks and forging marks in the axial direction are formed on the inner surface of the through hole. This means that the inner surface of the through hole is a composite machined surface forged with a mandrel after drilling. That is, if the inner surface is forged with a mandrel after the formation of a hole by drilling, the cut marks do not disappear within the reduction ratio range employed in the manufacturing method of the present invention, and the forged marks with the mandrel overlap with the mandrel. Is formed. In the case of performing drill cutting after forging (or drawing) as in the prior art, even if a drilling mark is formed on the inner surface of the through hole, no forging mark is formed.

In the through hole, the cutting marks are deep and relatively rough in the state of the drilling surface, but the cutting marks are crushed and the inner surface is smoothed by repeatedly performing forging. Accordingly, various effects can be obtained, for example, when sliding the inner surface of the member through another member, the slidability is improved, or the wire is hardly caught when the wire is inserted. That is, by the configuration of the metal member with a through-hole according to the present invention, as a whole, the precision of the formation of the through-hole is high, the smoothness of the inner surface of the through-hole formed is excellent, and the combination of cutting and forging is easy. The three effects of being able to be manufactured at the same time are achieved at the same time.

[0022]

Embodiments of the present invention will be described below with reference to embodiments shown in the drawings. 1 to 4 show steps of manufacturing a metal member with a through hole based on the method of the present invention. First, as shown in FIG. 1, a metal bar B having a circular cross section obtained as a rolled wire or the like is cut into a predetermined length to produce a columnar metal material 10. As shown in FIG. 2A, the metal material 10 has a circular axial cross section and an outer diameter D ′ of the axial cross section of 10 to 30 mm (preferably 15 to 25 m).
m), and the axial length L ′ is 15 to 36 mm (preferably 2
0 to 30 mm), and L ′ / D ′ is 3 to 4.5 (preferably 3 to 3.5).

The material of the metal material is not particularly limited. In this embodiment, stainless steel, for example, martensitic stainless steel such as SUS410 (in an annealed state) is used.

Next, as shown in FIG. 2, a through hole 21 having a circular cross section having an inner diameter d 'of 5 to 8 mm is formed in the center of the axial cross section of the metal material 10 by using a drill 50 by drilling. The metal material 20 with through holes is formed by drilling in the axial direction. At this time, a cutting mark (drill mark) DM in the circumferential direction is formed on the inner surface of the through hole 21 as shown in FIG. L '/ d' is 3 to
4.5 (preferably 3 to 3.5). By adopting the drill cutting, it becomes possible to secure the coaxiality of the through hole 21 to φ0.20 mm or less and the straightness K to 20/100 or less. In addition, as shown in FIG.
When the through-hole 201 of the cylindrical inner surface is formed at the center of 00, the coaxiality J of the through-hole 201 of the smallest one completely including the through-hole 201 among the straight cylinders centered on the central axis C of the cylindrical member 200 is determined. Defined by diameter. In addition, straightness K
Draws a straight line O ′ parallel to C through a point on O where the distance from C is the largest in a plane including the central axis C of the columnar member 200 and the central axis O of the through hole 201. Then, the distance between C and O ′ is defined as W, and the length of the portion of the C existing in the columnar member 200 is defined as L / W / L.

FIG. 3 shows an example of another method of forming the metal material 20 with through holes. in this way,
As shown in (a), the metal material 10 is put into a cavity 51b of a container 51 having an extrusion port 51a, and a perforated ram 52 is pressed into the material 21 in the cavity 51b from the extrusion port in the axial direction. Thereby, the material 21
The metal material 20 ′ with a bottomed hole having the bottomed hole 21 ′ is extruded from the space between the perforated ram 52 and the extrusion port 51 a in a direction opposite to the press-fit direction of the ram 52. Then, as shown in (b), by punching out the bottom portion 20a by a punching process, the bottomed hole 21 'becomes the through hole 21 and the metal material 20 with a through hole is obtained. In this method, the coaxiality of the through hole 21 is φ0.15 mm or less, and the straightness K is set to 3/1.
00 or less.

As shown in FIG. 4, the thus obtained metal material 20 with through-holes is subjected to a deep drawing forging process to form a final metal member 1 with through-holes. As shown in (a),
A mandrel 55 having a diameter slightly smaller than this and integrated with a forging punch 54 that pushes the rear end face of the material 20 toward the rear side is inserted into the through hole 21 of the material 20. This mandrel 55
Is set to a dimension corresponding to the inner diameter of the through hole 2 of the final member 1. Then, the material 20 is pressed into the die hole 57 of the forging die 56 by the forging punch 54 together with the mandrel 55. The die hole 57 is formed in a non-circular shape having a smaller sectional area than the material 20, that is, in a square shape in this embodiment, and a tapered guide for guiding the material 20 having a circular cross section while reducing its diameter at the entrance side. A portion 57a is formed. The raw material 20 is forged into a non-circular shape (in this case, a square shape) in which the outer surface side corresponds to the inner surface of the die hole while the outer diameter of the axial cross section and the inner diameter of the through hole are reduced in the die hole 57. On the other hand, the inner surface of the through hole 21 is formed so as to have a corresponding inner diameter while being restrained by the mandrel 55.

As shown in FIG. 4 (b), assuming that the axial cross-sectional area of the blank 20 before drawing and forging is S0 and the axial cross-sectional area of the forged member 1 is S1, the area reduction ratio RA (= ｛( S0-S1)
/ S0｝ × 100 (%)) is 40 to 70%, preferably 40 to 50%. Further, since the material is extruded from the die hole 57 at a speed higher than the pushing speed of the mandrel 55, the inner surface of the through hole 21 is rubbed by the outer surface of the mandrel 55. As a result, as shown in FIG. 3C, a forging mark FM due to the rubbing is formed in the inner surface of the through hole 2 of the obtained member 1 in the axial direction so as to overlap the above-mentioned cutting mark DM. Is done. Here, as shown in (d), the cutting surface DM is deep and relatively rough on the inner surface of the through hole 21 before forging. The typical through hole 2 has a smooth inner surface.

FIG. 5 is a plan view and a longitudinal sectional view of the metal member 1 with a through hole manufactured as described above. The member 1 has a square cross-sectional shape obtained by the above-described drawing forging process, and the shaft cross-sectional outer diameter when converted into a circle is D, and the inner diameter and the length of the through hole 2 are d and L, respectively, and L / d Is 5-10
(Preferably 5 to 7), D is 10 to 30 mm (preferably 15 to 25 mm), d is 5 to 8 mm (preferably 5 to 5 mm).
6 mm). When the material 20 is made by backward extrusion as shown in FIG. 3, the central axis of the through hole 2 is O and the central axis of the member 1 is C, and the coaxiality J of O to C (see FIG. 3). 6) can be maintained at φ0.15 mm or less, and the straightness K (FIG. 6) can be maintained at 20/100 or less.
On the other hand, as shown in FIG. 2, when drill cutting is employed, J is further improved to φ0.10 mm or less and K is improved to 10/100 or less. In the present embodiment, the material of the member 1 is martensitic stainless steel, and after that, it is further quenched (tempered if necessary), and is used for applications such as sliding parts of a compressor of an air conditioner. You.

In FIG. 4, by changing the shape of the die hole 57 of the forging die 56, the outer diameter of the axial cross section of the member 1 is, for example, triangular as shown in FIG. Various shapes such as a hexagonal shape as shown in b) and an elliptical shape as shown in FIG.

The following experiment was conducted to confirm the effects of the present invention. That is, the round bar member B (FIG. 1) of SUS410 (annealed material) was cut, and L ′ = 36 mm,
A metal material 10 with D '= 18 mm was produced. Then, as shown in FIG. 2, the inner diameter d ′ was changed to 8 using a drill.
By piercing the through-holes 21 of 10 mm, ten materials 20 with through-holes were produced for convenience. The average value of the coaxiality J of the through hole 21 is φ0.20 mm (standard deviation: 0.05 m).
m), and the straightness K is 2/100 (standard deviation: 0.0).
04) (hereinafter referred to as Example 1).

On the other hand, the same metal material 10 was used to produce ten through-hole materials 20 having the same dimensions as in Example 1 by backward extrusion and punching as shown in FIG. The average value of the coaxiality J of the through hole 21 is φ0.30 mm.
(Standard deviation: 0.08 mm), and the straightness K is 4/1.
00 (standard deviation: (0.009) (hereinafter referred to as Example 2)).

Each of the through-hole materials 20 of Example 1 and Example 2 was subjected to drawing forging as shown in FIG. 4, so that the shaft cross-sectional dimension was 11 mm × 13 mm (circular shaft cross-sectional diameter D = 15). .5 mm), length L is 36 mm,
The through-hole 2 had an inner diameter d of 7.5 mm and an L / d of 4.3 mm.

As a comparative example, as shown in FIG.
The round bar member 100 is drawn to form a square bar member 101 having an axial cross-sectional dimension of 11 mm × 3 mm, which is cut to a fixed length of L = 70 mm, and having an inner diameter d ′ of 7. For convenience, ten through-hole materials having 5 mm through holes 105 were also produced.

When the coaxiality J and straightness K of the through-holes of each of the obtained members were measured, J of the comparative example was 0.19 mm (standard deviation: 0.04 mm), and K was 6 / In contrast to the large value of 100 (standard deviation: 0.010), the member manufactured by the method of the present invention using the material with through holes 20 of Example 1 had a J of φ0.10 mm.
(Standard deviation: 0.02 mm) and K is 5/100 (standard deviation: (0.008). Similarly, in the case of using the through-hole material 20 of Example 2, J is φ0.15 mm.
(Standard deviation: 0.03 mm) and K were 2/100 (standard deviation: 0.004), all of which were good.

[Brief description of the drawings]

FIG. 1 is a process explanatory view of a method for manufacturing a metal member with through holes according to the present invention.

FIG. 2 is an explanatory view following FIG. 1;

FIG. 3 is another explanatory view following FIG. 1;

FIG. 4 is an explanatory view following FIG. 2 or FIG. 3;

FIG. 5 is a plan view and a longitudinal sectional view showing an example of a metal member having a through hole according to the present invention.

FIG. 6 is a diagram illustrating the concept of coaxiality and straightness of a through hole.

FIG. 7 is a diagram for explaining the definition of a non-circular cross-sectional shape;

FIG. 8 is a view showing some modified examples of the axial cross-sectional shape of the metal member with through holes according to the present invention.

FIG. 9 is an explanatory view showing a method for manufacturing a conventional metal member with through holes.

FIG. 10 is an explanatory diagram of the problem.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal member with a through hole 2 Through hole 10 Metal material 20 Metal material with a through hole 21 Through hole 50 Drill 55 Mandrel 56 Forging die 57 Die hole DM Cutting mark FM Forging mark

Continued on front page F term (reference) 4E029 GA02 4E087 AA08 AA10 BA15 BA20 CA17 CA21 CA22 CA24 CA28 CB11 CB12 DB01 DB03 DB05 DB06 DB22 DB24 EC11 EC17 EC18 EC37 EC38 EC39 EC46 HA00

Claims (9)

[Claims] 1. An axial cross section is circular, the outer diameter D 'of the axial cross section is 10 to 30 mm, and the length L' in the axial direction is 15 to 36 m.
m, the inner diameter d 'is 5
A drilling step of producing a metal material with a through-hole by drilling a through-hole in the axial direction having an L ′ / d ′ of 3 to 4.5 mm, and a hole after processing; By passing the metal material with the through hole in the axial direction through the non-circular die hole formed in the forging die while inserting the mandrel for defining the inner diameter into the through hole, the area reduction rate is 40 to 70% or less. Drawing forging is performed, whereby the cross-sectional outer shape becomes a non-circular shape corresponding to the die hole, and the processed cross-sectional outer diameter of the member is D, and the inner diameter and length of the through hole are d and L, respectively. , L / d is 5 to 10, D is 7 to 18 mm, and d is 5 to 8 mm. A drawing forging step is performed to obtain a metal member with a through hole. 2. The metal material is extruded rearward so that the shaft cross section is circular, and the shaft cross section has an outer diameter D 'of 10 to 10.
An extrusion process of producing a metal material with a bottomed hole having an axial length L ′ of 30 mm, an axial length L ′ of 15 to 36 mm, and an inner diameter d ′ of 5 to 8 mm at the center of the cross section; A punching step of punching the bottom of the metal material with a bottomed hole to make the bottomed hole a through-hole having an L '/ d' of 3 to 4.5 to produce a metal material with a through-hole; By drawing a metal material with a hole in the axial direction through a non-circular die hole formed in a forging die while inserting a mandrel defining a hole inner diameter into the through hole, drawing and forging with a surface reduction rate of 70% or less. Processing is performed, whereby the axial cross-sectional outer shape becomes a non-circular shape corresponding to the die hole, and the axial cross-sectional outer diameter of the processed member is D, and the internal diameter and length of the through-hole are d and L, respectively. / D is 5 to 10,
A forging step of obtaining a metal member with a through hole having D of 7 to 18 mm and d of 5 to 8 mm. 3. The through hole according to claim 1, wherein the central axis of the through hole is O and the central axis of the metal member with the through hole is C, and the coaxiality of O to C is φ0.15 mm or less. A method for manufacturing an attached metal member. 4. The metal member with a through hole according to claim 1, wherein the central axis of the through hole is O and the central axis of the metal member with the through hole is C, and the coaxiality of O with respect to C is φ0.10 mm or less. Manufacturing method. 5. The method for manufacturing a metal member with a through hole according to claim 1, wherein the straightness of the through hole is 20/100 or less. 6. The method according to claim 1, wherein the straightness of the through hole is not more than 10/100. 7. The method for manufacturing a metal member with a through hole according to claim 1, wherein the metal member with a through hole has a quadrangular cross-sectional outer shape. 8. A non-circular cross-sectional outer shape, a through-hole in the axial direction formed in the center of the cross-section of the shaft, and the outer diameter of the cross-section of the shaft is D, and the inner diameter and the length of the through-hole are d and L, respectively. / D is 5 to 10, D is 7 to 18 mm, d is 5 to 8 mm
On the inner surface of the through-hole, a cutting mark in the circumferential direction and a forging mark in the axial direction are formed, and the center axis of the through-hole is O, and the center axis of the member itself is C, and A metal member with a through-hole, wherein the coaxiality with respect to C is φ0.15 mm or less, and the straightness of the through-hole is 20/100 or less. 9. The coaxiality of O to C is φ0.1, where O is the central axis of the through hole and C is the central axis of the member itself.
0 mm or less, and the straightness of the through hole is 10 mm or less.
The metal member with a through hole according to claim 8, wherein the ratio is not more than / 100.