JP2001050103A - Diffusion bonding structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high bonding strength in a diffusion bonding structure in which an attaching member is pressed against a member to be attached in a condition of heating both members, by increasing a slip speed and a volume of a plastically flowing substance between both members during diffusion bonding. SOLUTION: An attaching member 25 has a part which is bonded to a member 13 to be attached, and the external surface of which has, before bonding, such a shape that it is composed of a curved surface 29 which is located at the position of the distal end of the attaching member 25, the distal end being adapted to make at first contact with the member to be attached when the attaching member 25 is pressed against the member 13 to be attached, and which is convex toward the member 13 to be attached, and other curved surfaces 30, 31 which are convex toward the member 13 to be attached, with a radius of curvature which is larger than that of the curved surface 29, and which are continuous to the curved surface 29.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diffusion bonding structure in which a mounting member is pressed against a mounting member while the mounting member and the mounting member are heated.

[0002]

2. Description of the Related Art Such a diffusion bonding structure is disclosed in, for example, JP-A-7-103070 and JP-A-7-189628.
In this publication, a valve seat as a mounting member made of a material different from that of the cylinder head is diffused into a cylinder head as a member to be mounted. A structure to be joined is disclosed.

[0003]

However, in the conventional diffusion bonding structure, the outer surface of the portion of the mounting member, which is to be bonded to the member to be mounted, before bonding has a cross-sectional shape composed of a combination of straight lines. Therefore, since sufficient plastic flow does not occur in the linear portion, sufficient joining strength cannot be obtained. This is because, when the mounting member is pressed against the mounting member side, the tip portion that first comes into contact with the mounting member is formed at an acute angle, so that sufficient plastic flow occurs in this portion and the diffusion bonding layer is sufficiently formed. Although it is formed, in the portion having a linear cross-sectional shape and continuing to the tip, the sliding speed of the plastic fluid and the amount of the plastic fluid are clearly reduced as compared with the tip, and it is sufficient. This is considered to be because no diffusion bonding layer is formed.

The present invention has been made in view of such circumstances, and aims at increasing the sliding speed of a plastic fluid generated between a mounting member and a member to be mounted during diffusion bonding and the amount of the plastic fluid, thereby achieving sufficient bonding. An object of the present invention is to provide a diffusion bonding structure capable of obtaining strength.

[0005]

In order to achieve the above object, the present invention relates to a diffusion bonding structure in which a mounting member is pressed against a mounting member while the mounting member and the mounting member are heated. The outer shape of the portion of the mounting member, which is to be bonded to the mounted member, before joining is located at the tip position where the mounting member first contacts the mounted member when the mounting member is pressed against the mounted member, and And a curved surface bulging toward the member to be mounted with a larger radius of curvature than the curved surface and continuing to the curved surface.

According to such a configuration, the sliding speed of the plastic fluid generated between the mounting member and the member to be mounted and the amount of the plastic fluid are increased, and sufficient bonding strength can be obtained by good diffusion bonding. . That is, the outer surface of the portion of the mounting member, which is to be bonded to the mounted member, having a curved outer surface before joining can increase the sliding speed of the plastic fluid with respect to the stroke as compared with a flat surface. Since the curved surface that first comes into contact with the mounted member when the mounting member is pressed against the mounted member is formed with a relatively small radius of curvature, the curved surface on the distal end side of the curved surface is attached to the mounted member. The amount of the plastic fluid generated by the immersion can be increased, and the portion connected to the curved surface on the front end side is also formed as a curved surface, so that the plastic fluid is positively increased by increasing the sliding speed of the plastic fluid. Can be discharged. Therefore, it is possible to satisfactorily diffuse the attachment member to the attachment member to obtain a sufficient joining strength.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on one embodiment of the present invention shown in the attached drawings.

1 to 5 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a main part of a four-cycle engine, and FIG. 2 is a state immediately before diffusion bonding of a valve seat material to a cylinder head. FIG. 3 is an enlarged view of a main part of FIG. 2, FIG. 4 is a cross-sectional view corresponding to FIG. 3 in a diffusion bonding process, and FIG. 5 is a diagram for explaining a sliding speed of a plastic fluid. .

First, in FIG. 1, a piston (not shown) slidably fitted in a cylinder hole 12 provided in a cylinder block 11 of a four-cycle engine, and an attached member coupled to the cylinder block 11 A combustion chamber 14 is formed between the cylinder head 13 and the cylinder head 13. The cylinder head 13 is provided with an intake port 15 and an exhaust port 16 that can communicate with the combustion chamber 14.

Valve seats 17 and 18 are joined to the cylinder head 13 at the opening ends of the intake port 15 and the exhaust port 16 to the combustion chamber 14, and a seat portion 19 a which can be seated on the valve seats 17 and 18. , 20a of the intake valve 19 and the stem portion 19b of the exhaust valve 20 are slidably fitted to guide cylinders 21 and 22 provided on the cylinder head 13, respectively. Moreover, each of the stem portions 19b, 20b is provided with a guide cylinder 21,
2, each stem portion 19b,
Between the upper end of the cylinder head 20b and the cylinder head 13, the intake valve 19 and the exhaust valve 20 are urged upward, that is, the seat portions 19a and 20a are seated on the valve seats 17 and 18 to close the intake port 15 and the exhaust port 16. Springs 23 and 24 are provided. Also each stem part 1
A valve train (not shown) is connected to the upper ends of 9b and 20b, and the valve train drives the intake valve 19 and the exhaust valve 20 to open and close.

The valve seats 17 and 18 are generally assembled to the cylinder head 13 by press-fitting. In recent engine layouts, an intake valve 19 and an exhaust valve 20 are arranged close to each other.
In the conventional press-fit type, there is little freedom in changing the layout around the combustion chamber 14 in order to increase the valve diameter or increase the compression ratio. Therefore, when the valve seats 17 and 18 are directly joined to the cylinder head 13 instead of the press-fit type, the degree of freedom of the layout can be greatly improved by reducing the thickness of the valve seats 17 and 18 or the valve seats 17 and 18 can be used. As a result, the temperatures of the intake and exhaust valves 19, 20, the valve seats 17, 18, and the combustion chamber 14 can be reduced, and a significant improvement in engine performance can be expected. . At this time, even if the valve seats 17 and 18 are made of a metal different from that of the cylinder head 13, it is possible to obtain a sufficient bonding strength by performing diffusion bonding.

In FIG. 2, a cylinder head 13 has
The valve seat material 25 as an attachment member is diffusion-bonded, and the valve seat material 25 after joining is subjected to machining to form the valve seats 17 and 18.

The cylinder head 13 is made of an aluminum alloy casting, which is a lightweight metal having excellent heat conductivity, and the valve seat material 25 is made of, for example, an iron-based sintered alloy having excellent wear resistance. Alternatively, a Cu-Be alloy or the like having excellent cooling and heat conductivity is used.

At the opening ends of the intake and exhaust ports 15 and 16 of the cylinder head 13 on the combustion chamber 14 side, a mounting surface 26 having a smaller diameter is formed as the distance from the combustion chamber 14 increases in the axial direction. On the other hand, valve seat material 2
5 is formed in a ring shape having an opposite end surface 27 at one end in the axial direction for facing the outer peripheral portion to the attached surface 25 and an outer surface 28 having a circular cross section.

The valve seat material 25 is pressed against the mounting surface 26 of the cylinder head 43 in a state where the valve seat material 25 and the cylinder head 13 are heated.
It is diffusion bonded to the mounting surface 26. The heating state is achieved by applying a large current to the valve seat material 25 and the cylinder head 13 in a short time while bringing the valve seat material 25 into contact with the mounting surface 26 of the cylinder head 13. Cylinder head 13
Is generated by the Joule heat generated by the contact surface.

In FIG. 3, the valve seat material 25 is
When the valve seat material 25 is pressed against the cylinder head 13 side, the continuous portion of the opposed end surface 27 and the outer surface 28 is brought into contact with the cylinder head 13 first, and the outer peripheral portion of the opposed end surface 27 and the The portion of the side surface 28 on the side of the facing end surface 27 and the continuous portion are diffusion-bonded to the cylinder head 13.

The outer shape of the portion of the valve seat material 25 to be joined to the cylinder head 13 before joining is as follows:
A portion at the tip position where the valve seat material 25 first contacts the cylinder head 13 when the valve seat material 25 is pressed against the cylinder head 13 side (a continuous portion of the opposed end surface 27 and the outer surface 28) and has a radius of curvature toward the cylinder head 13 side. A curved surface 29 bulged at R1 and radii of curvature R2, R3 larger than the curved surface 29;
And the other curved surfaces 30 and 31 bulging toward the cylinder head 13 side and continuing to the curved surface 29. The curved surface 30 forms an outer peripheral portion of the opposed end surface 27, and the curved surface 31 is an outer surface 28.
Is formed on the side of the opposing end surface 27.

An annular concave portion 32 is formed radially inward of a portion (curved surface 30) of the opposed end surface 27 which is joined to the cylinder head 13, and the concave portion 32 has
As shown in FIG. 4, the mounting surface 26 and the facing end surface 27
It is possible to receive the plastic fluid 33 discharged from the bonding interface.

Next, the operation of this embodiment will be described.
When the cylinder head 13 is pressurized while the cylinder head 13 is heated, a sliding deformation occurs on the contact surface between the valve seat material 25 and the cylinder head 13, and an oxide film, foreign matter, The intermetallic compound is discharged from the bonding interface as a plastic fluid 33 as shown in FIG.
Fine irregularities and interatomic vacancies at the bonding interface disappear, and a very clean and gas-free contact surface is formed. Moreover, free electrons in the metal are activated by the contact between the clean surfaces in the heated state, and intra-granular / grain-boundary diffusion of atoms between the valve seat material 25 and the cylinder head 13 occurs. It is diffusion bonded to the head 13.

The part of the valve seat material 25 which is to be joined to the cylinder head 13 and whose outer surface shape is formed by curved surfaces 29, 30, and 31 before pressurization is compared with a flat surface. It is possible to increase the sliding speed of the plastic fluid 33 with respect to the stroke. That is, the sliding distance L1 when the plastic fluid 33 slides on the curved surface shown in FIG. 5A is equal to the sliding distance L2 when sliding on the flat surface shown in FIG. Is larger (L1> L2), and the valve seat material 2
Of the parts 5, those having a curved surface 29, 30, 31 whose outer surface shape before joining of a portion joined to the cylinder head 13 has a higher sliding speed than a flat surface.

However, when the valve seat material 25 is pressed against the cylinder head 13 side, the curved surface 29 that first comes into contact with the cylinder head 13 is formed with a relatively small radius of curvature R1, so that the curved surface on the distal end side is formed. The amount of the plastic fluid 33 generated by the immersion of the plastic fluid 29 into the cylinder head 13 can be increased, and the portion connected to the curved surface 29 on the front end side is also formed on the curved surfaces 30 and 31. , The plastic fluid 33 can be positively discharged by increasing the sliding speed. Therefore, it is possible to satisfactorily diffuse the valve seat material 25 to the cylinder head 13 and obtain a sufficient bonding strength.

The joining depth of the valve seat material 25 to the cylinder head 13 is determined by a resistance value corresponding to the amount of the plastic fluid 33 generated by the valve seat material 25 immersing into the cylinder head 13 and the plastic flow discharged. The resistance is determined by the balance between the sum of the resistance values generated when the animal 33 bites between the attachment surface 26 and the facing end surface 27 and the pressing force. It is difficult to control the junction depth with high accuracy while keeping the variation.

However, an annular concave portion 32 is formed radially inward of a portion of the opposed end surface 27 which is joined to the cylinder head 13, and the plastic fluid 3 is formed in the concave portion 32.
3 is possible. Therefore, the plastic fluid 33 discharged inward from the space between the opposing end surface 27 and the mounting surface 26 can escape into the concave portion 32, and the discharged plastic fluid 33 can flow between the mounting surface 26 and the opposing end surface 27. This minimizes the variation in the pressure resistance value caused by biting into the joint, and allows the joining depth to be controlled more accurately.

Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the appended claims. It is possible to do.

For example, the present invention relates to a valve seat material 25.
The present invention is not limited to the structure of diffusion bonding to the cylinder head 13 but is widely applicable to the structure of diffusion bonding of the mounting member to the member to be mounted.

[0026]

As described above, according to the present invention, the slip speed of the plastic fluid generated between the mounting member and the member to be mounted and the amount of the plastic fluid are increased, and sufficient bonding strength is obtained by good diffusion bonding. Obtainable.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part of a four-cycle engine.

FIG. 2 is a longitudinal sectional view showing a state immediately before diffusion bonding of a valve seat material to a cylinder head.

FIG. 3 is an enlarged view of a main part of FIG. 2;

FIG. 4 is a cross-sectional view corresponding to FIG. 3 in a diffusion bonding process.

FIG. 5 is a diagram for explaining a sliding speed of a plastic fluid.

[Explanation of symbols]

 13: Cylinder head as attachment member 25: Valve seat material as attachment member 29, 30, 31 ... Curved surface

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kiyonobu Mizogami 1-4-1 Chuo, Wako, Saitama Prefecture Inside Honda R & D Co., Ltd. (72) Koji Ueda 1-4-1 Chuo, Wako, Saitama Inside Honda R & D Co., Ltd. (72) Inventor Masakatsu Sato 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (reference) 3G024 AA14 AA15 DA03 DA04 DA08 EA01 GA25 HA01 HA07 4E067 BA00 EB00

Claims (1)

[Claims] In a diffusion bonding structure in which a mounting member (25) is pressed against the mounting member (13) in a state where the mounting member (25) and the mounting member (13) are heated, the mounting member (25) is provided. 25) Attached member (13)
The outer shape of the part to be joined to the mounting member (25) is at the tip end position where the mounting member (25) first contacts the mounting member (13) when the mounting member (25) is pressed against the mounting member (13), and (13) a curved surface (29) bulging to the side, and a member to be mounted (13) having a larger radius of curvature than the curved surface (29);
The other curved surface (3) bulging to the side and continuing to the curved surface (29)
0, 31).