JP2001050104A - Diffusion bonding structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high bonding strength, restrain dispersion in a resistance value caused by biting of a plastically flowing substance, and precisely control the bonding depth of a diffusion bonding structure in which an attaching member having an opposing surface opposed at least in its outer peripheral part to an attaching surface of a member to be attached, and having a circular cross-sectional outer surface, is pressed against the member to be attached, in a condition of heating both members while a part connecting between the opposed end surface and the outer surface is at first made into contact with the attaching surface of the member to be attached. SOLUTION: Before bonding an attaching member 25 to a member 13 to be attached, a connecting part 29 is formed into a curved shape which is convex toward the member 13 to be attached, and an end surface and an outer surface have parts 27a, 28a which are to be bonded to the member 13 to be attached, and which are formed into a curved shape having a radius of diameter greater than that of the connecting part 29. An annular recess 32 is formed in the opposed end surface, radially inward of the part 27 to be bonded to the member 13 to be attached.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a mounting member having a mounting surface having a diameter decreasing toward one side in the axial direction, having at one end in the axial direction an opposing end surface at least an outer peripheral portion of which is opposed to the mounting surface. An attachment member having an outer surface having a circular cross-section is pressed toward the member to be attached while the members are heated while the connecting portion of the opposite end surface and the outer surface is first brought into contact with the surface to be attached. Related to the joint structure.

[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.

[0004] The joining depth of the mounting member to the member to be mounted is determined by a resistance value corresponding to the amount of plastic fluid generated by the mounting member immersing into the member to be mounted, and by the discharged plastic fluid to the surface to be mounted. It is determined by the balance between the sum of the resistance values generated by the biting between the opposed end faces and the pressing force, but the variation in the resistance value due to the biting is very large, and the joining depth is controlled with high precision. Was difficult.

The present invention has been made in view of the above 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. It is an object of the present invention to provide a diffusion bonding structure capable of obtaining strength and suppressing a variation in resistance value caused by entrapment of a plastic fluid so that a bonding depth can be accurately controlled.

[0006]

In order to achieve the above object, the invention according to the first aspect of the present invention is directed to a mounting member having a mounting surface having a diameter decreasing toward one side in the axial direction, at least including the mounting surface. A mounting member having an opposing end surface at the one end in the axial direction for opposing the outer peripheral portion and having an outer surface with a circular cross section is formed by first bringing the continuous portion of the opposing end surface and the outer surface into contact with the surface to be mounted. In a diffusion bonding structure in which a pressure is applied to the member to be attached in a heated state, the connecting portion is formed into a curved surface bulging toward the member to be attached before joining the member to the member to be attached. A portion of the opposed end surface and the outer surface that is joined to the member to be attached is formed in a curved shape having a larger radius of curvature than the continuous portion, and is joined to the member to be attached of the opposed end surface. Radially inward than the portion that is characterized in that an annular recess for receiving a plastic flow animal to be discharged from the bonding interfaces between the mounting surface and the facing end surface is formed.

According to the first aspect of the present invention, 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 diffusion bonding is achieved. The joining strength can be obtained. 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 connecting portion which first comes into contact with the mounting surface when the mounting member is pressed against the mounting member is formed on a curved surface having a relatively small radius of curvature, the connecting portion is provided. It is possible to increase the amount of plastic fluid generated by immersion in the attached member,
In addition, since portions of the opposing end surface and the outer surface that are joined to the member to be attached are formed in curved surfaces having a larger radius of curvature than the continuous portion, the sliding speed of the plastic fluid is increased to increase the plastic flow. The animals can be eliminated positively. In addition, since the annular concave portion is formed radially inward of a portion of the opposed end surface that is joined to the member to be attached, the plastic flow discharged from the opposed end surface and the attached surface to the radially inward side is formed. An animal can be allowed to escape into the concave portion, and the variation in the pressure resistance value caused by the discharged plastic fluid being caught between the mounting surface and the opposed end surface is minimized, and the joining depth is more accurately determined. You will have better control.

[0008] The invention according to claim 2 provides the above-mentioned claim 1.
In addition to the configuration of the invention described above, before the attachment member is joined to the attachment member, the attachment surface of the attachment member has an annular bottom surface facing the outer peripheral portion of the facing end surface, There is provided a joint recess formed by rising from the outer peripheral edge to the mounting member side and an inner surface facing the outer surface of the mounting member, wherein the bottom surface and the inner surface are provided on the mounting surface side of the mounting member. A first step in which the continuous portion contacts the outer peripheral portion of the bottom surface during pressurization, and a second step in which the opposed end surface sequentially contacts the bottom surface from the radially outer side.
And a third step of causing the outer side surface to sequentially contact the inner side surface from the inner side in the axial direction to raise the pressurization resistance value. .

According to the structure of the second aspect of the present invention, in the first step, the resistance value is increased in response to generation of a plastic fluid as the continuous portion of the mounting member is immersed in the mounted member. In the second step, the resistance value gradually increases as the opposed end face of the mounting member sequentially contacts the bottom surface of the joint concave portion from the radially outward side in the second step. Since the outer surface of the mounting member in addition to the portion and the opposed end surface is immersed in the inner surface of the joint recess,
The resistance value rises significantly. That is, when the mounting member is pressed against the member to be mounted, the resistance change characteristics are made different for each step, and the resistance value rises significantly at the end of bonding immediately before the target bonding depth. The timing at which the pressure is stopped can be determined with high accuracy, and the control accuracy of the junction depth can be further improved.

[0010]

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.

FIGS. 1 to 7 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a main part of a four-stroke 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 at the end of the diffusion bonding process, and FIG.
FIG. 6 is a sectional view for sequentially explaining the diffusion bonding process, FIG. 6 is a diagram for explaining the sliding speed of the plastic fluid, and FIG. 7 is a diagram showing a change in the resistance value during the diffusion bonding process.

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 19a which can be seated on the valve seats 17 and 18. , 20a of the intake valve 19 and the stem portion 19b, 20B of the exhaust valve 20 are slidably fitted to guide cylinders 21, 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, the 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 transfer properties. 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 open 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 diffused to the mounting surface 26 by applying a constant pressure to the mounting surface 26 of the cylinder head 43 while the valve seat material 25 and the cylinder head 13 are heated. Joined.
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. It is obtained by the fact that the contact surface of the cylinder head 13 generates Joule heat.

In FIG. 3, the valve seat material 25 is
When the valve seat material 25 is pressed to the cylinder head 13 side, the connecting portion 29 of the opposed end surface 27 and the outer surface 28 is formed.
Is brought into contact with the cylinder head 13 first,
Outer peripheral portion 27a and outer surface 28 of opposing end surface 27
The portion 28a on the side of the opposing end surface 27 and the connecting portion 29 are diffusion-bonded to the cylinder head 13.

Before the valve seat material 25 is joined to the cylinder head 13, the connecting portion 29 is formed in a curved surface bulging at the radius of curvature R 1 on the cylinder head 13 side. The outer peripheral side portion 27a has a radius of curvature R2 larger than that of the continuous
The portion 28a of the outer surface 28 on the side of the opposing end surface 27 is also formed into a curved surface bulging toward the cylinder head 13 with a radius of curvature R3 larger than the connecting portion 29.

An annular concave portion 32 is formed radially inward of a portion 27a of the opposed end surface 27 which is joined to the cylinder head 13, and the concave portion 32 is mounted in the concave portion 32 as shown in FIG. It is possible to receive a plastic fluid 33 discharged from the joint interface between the surface 26 and the facing end surface 27.

Referring to FIG. 3, before joining the valve seat material 25 to the cylinder head 13, the cylinder head 13
The mounting surface 26 has an annular bottom surface 34a facing the outer peripheral portion of the facing end surface 27 of the valve seat material 25,
A joint recess 34 is provided which rises from the outer peripheral edge of the bottom surface 34a to the valve seat material 25 side and includes an inner surface 34b facing the outer surface 28 of the valve seat material 25.

Moreover, the bottom surface 34a and the inner side surface 3
4b, a first step in which the connecting portion 29 contacts the outer peripheral portion of the bottom surface 34a when the valve seat material 25 is pressed against the mounting surface 26, as shown in FIG.
As shown in FIG. 5B, a second step in which the opposed end surface 27 sequentially contacts the bottom surface 34a from the radially outward side, and as shown in FIG. The third step of sequentially contacting the inner side surface 34b from the inner side in the axial direction to raise the pressure resistance value is performed so as to elapse in this order.

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 portion of the valve seat material 25 to be joined to the cylinder head 13 having a curved outer surface before joining is formed of a plastic fluid with respect to a pressing stroke, compared to a flat surface. It is possible to increase the sliding speed of 33. That is, the plastic fluid 33
Is the sliding distance L1 when sliding on the curved surface shown in FIG.
Is the sliding distance L2 when sliding on the flat surface shown in FIG.
On the other hand, the same pressure stroke S is large (L1> L
In the valve seat material 25, the portion of the valve seat material 25 to be joined to the cylinder head 13 having a curved outer surface shape before joining has a higher sliding speed than a flat surface. It becomes.

However, when the valve seat material 25 is pressed against the cylinder head 13 side, the connecting portion 29 that first comes into contact with the cylinder head 13 is formed with a relatively small radius of curvature R1. The amount of the plastic fluid 33 generated by the immersion of the connecting portion 29 into the cylinder head 13 can be increased, and the portions 27a and 28a connected to the connecting portion 29 are also formed in a curved shape. ,
It is possible to positively discharge the plastic fluid 33 by increasing the sliding speed of the plastic fluid 33. 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 blank 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 blank 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 the portion of the opposite 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.

Before joining the valve seat material 25 to the cylinder head 13, the mounting surface 26 of the cylinder head 13 has an annular bottom surface 34a and an inner surface rising from the outer peripheral edge of the bottom surface 34a to the valve seat material 25 side. Side 34b
Are formed, and the bottom surface 3
4a and the inner surface 34b are a first step in which the continuous portion 29 of the valve seat material 25 contacts the outer peripheral portion of the bottom surface 34a when the valve seat material 25 is pressed against the mounting surface 26 side; A second step in which the opposite end surface 27 of the material 25 sequentially contacts the bottom surface 34a from the radially outer side; and a second step in which the outer surface 28 of the valve seat material 25 sequentially contacts the inner surface 34b from the axially inner side. And 3 steps are formed in this order.
With such a joint concave portion 34, the timing of stopping the pressurization can be accurately determined, and the control accuracy of the joint depth can be further improved.

In FIG. 7, in the first step, the resistance increases sharply in response to the generation of the plastic fluid due to the continuous portion 29 of the valve seat material 25 being immersed in the cylinder head 13. In step, valve seat material 2
5 sequentially contacts the bottom surface 34a of the joint recess 34 from the radially outward side, whereby the resistance value gradually increases. Further, in the third step, in addition to the connection portion 29 and the opposed end surface 27, Outside surface 2 of valve seat material 25
Since 8 is immersed in the inner side surface 34b of the joint recess 34, the resistance value rises significantly. That is, when the valve seat material 25 is pressurized to the cylinder head 13 side with a constant pressing force, the change characteristic of the resistance value is made different in each step, and the valve seat material 25 is removed in the final third step in which the resistance value rises greatly. By balancing the constant pressing force and the resistance value (reaction force against pressing), the target joining depth can be obtained with high accuracy, and the joining depth control accuracy can be further improved.

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, in the present invention, the 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.

[0033]

As described above, according to the first aspect of the present invention, 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 satisfactory diffusion bonding is achieved. High joint strength, and minimizes variations in pressure resistance caused by the discharged plastic fluid getting caught between the surface to be mounted and the opposite end surface, allowing more precise control of the joint depth It is possible to do.

According to the second aspect of the present invention, when the mounting member is pressed against the member to be mounted, the resistance value rises greatly at the end of bonding immediately before the target bonding depth, so that the pressure is increased. It is possible to accurately determine the timing for stopping the welding, and it is possible to further improve the control accuracy of the junction depth.

[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 sectional view corresponding to FIG. 3 at the end of the diffusion bonding process.

FIG. 5 is a cross-sectional view for sequentially explaining a diffusion bonding process.

FIG. 6 is a diagram for explaining a sliding speed of a plastic fluid.

FIG. 7 is a diagram showing a change in resistance value during a diffusion bonding process.

[Explanation of symbols]

13: Cylinder head as a member to be mounted 25: Valve seat material as a mounting member 26: Surface to be mounted 27: Opposite end surface 27a: Joined to the member to be mounted among the opposing end surfaces Part 28 ... Outside surface 28a ... Part of the outside surface to be joined to the member to be attached 29 ... Contiguous portion 32 ... Recess 34 ... Before joining recess 34a ... Bottom surface 34b ...・ Inner 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 (2)

[Claims] An attached member (13) having an attached surface (26) whose diameter decreases toward one side in the axial direction,
A mounting member (25) having at one end in the axial direction an opposite end surface (27) for facing at least an outer peripheral portion of the mounting surface (26) and having an outer surface (28) having a circular cross section.
However, while the connecting portion (29) of the opposed end surface (27) and the outer surface (28) is first brought into contact with the mounting surface (26), the mounting member ( In the diffusion bonding structure in which the mounting member (25) is pressurized toward the mounting member (13), the connecting portion (29) expands toward the mounting member (13) before the mounting member (25) is bonded to the mounting member (13). It is formed in a curved shape, and the opposite end face (2
7) and the attached member (13) of the outer surface (28)
(27a, 28a) joined to the connecting portion (2)
9) Each of the opposed end faces (27) is formed in a curved shape having a larger radius of curvature than that of the attached member (1).
An annular concave portion (32) is formed radially inward of the portion (27a) to be joined to 3) to receive the plastic fluid discharged from the joining interface between the attachment surface (26) and the opposed end surface (27). A diffusion bonding structure characterized by being made. 2. An outer peripheral portion of said opposed end face (27) on a mounting surface (26) of said mounting member (13) before joining said mounting member (25) to said mounting member (13). An annular bottom surface (34a) facing the bottom surface;
A joint concave portion (34) is provided which rises from the outer peripheral edge toward the mounting member (25) and is formed of an inner side surface (34b) facing the outer side surface (28) of the mounting member (25). 34a) and said inner surface (34b)
Is the mounting surface (26) of the mounting member (25).
When pressurized to the side, the connecting portion (29) is connected to the bottom surface (34).
a) contacting the outer peripheral portion of a), a second step in which the opposed end surface (27) sequentially contacts the bottom surface (34a) from the radially outward side, and the outer surface (28) 3. The diffusion according to claim 1, wherein a third step of successively contacting the inner side surface (34b) from the inner side in the axial direction to raise the pressure resistance value is performed so as to elapse in this order. Joint structure.