JP2000263242A - Metal welding method and metal joining structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a metal welding method capable of preventing an iron-based first metallic member from hardening and deforming and satisfactorily joining metallic members different in melting point to each other, and to provide a metal joining structure. SOLUTION: When joining a sheet and a head by electric resistance welding, since the heat capacity of the sheet consisting of a Fe stock is remarkably small, the temperature rising caused by heat generation by resistance at the time of energizing the sheet is violent. Therefore, after the metallurgical joining of both members has been completed by the energization by a first current pulse, the plural numbers of times of pulse shaped energization are repeated so that the sheet is gradually cooled. During this operation, for pressure forces applied to both members, prescribed pressure forces are held to prevent the joined sheets from being deformed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal welding method and a metal joining structure, for example, a metal welding method and a metal joining structure for joining different kinds of metals by electric resistance welding for applying heat and pressure. .

[0002]

2. Description of the Related Art Conventionally, a technique of joining two kinds of metal members having different melting points by applying heat and pressure has been widely used. One example of such a metal joining technique is an electric resistance welding technique. There is. This welding technology
This is a technique in which different kinds of metals are brought into contact with each other and energization and pressurization are performed in the contact state, so that both metal members are joined by utilizing heat generated by electric resistance on the contact surface. .

Japanese Patent Application Laid-Open No. Hei 8-296416 proposes a technique in which such an electric resistance welding technique is applied to the joining between a cylinder head and a valve seat. When the cylinder head and the valve seat are joined by electric resistance welding, the material thickness of the valve seat can be reduced as compared with the conventional press-fitting method, and the opening diameter of the supply / exhaust port of the cylinder head can be increased. This is a technology that greatly improves the degree of freedom in engine design.

[0004]

However, in the above conventional example, since the heat capacity of the valve seat is considerably smaller than the heat capacity of the cylinder head, even if the seat is excessively heated and the two members are joined together. It is expected that the sheet will be quenched due to a rapid temperature drop after the joining is completed. In this case, in the completed engine, since the hardness of the valve seat is too high, abrasion of the valve that repeats contact with the valve seat becomes a problem.

Accordingly, an object of the present invention is to provide a metal welding method and a metal joining structure for preventing quenching and deformation of an iron-based first metal member and for satisfactorily joining metal members having different melting points.

[0006]

To achieve the above object, a metal welding method according to the present invention has the following features.

[0007] That is, a metal welding method for welding a first metal member made of iron and a second metal member made of light alloy, wherein a heat treatment and a pressure treatment are applied to the first and second metal members. , The metal members are metallurgically welded, the pressurizing process is continued even after the first and second metal members are welded, and the heat treatment on the first metal member is performed for a predetermined time. It is characterized by continuing.

[0008] Further, there is provided a metal welding method for welding an iron-based first metal member and a light alloy-based second metal member by an energizing process and a pressing process in electric resistance welding. 1 A metal member is pre-coated with a eutectic alloy,
In welding the first iron-based metal member coated with the eutectic alloy and the second metal member of the light alloy system, the metallurgical fusion bonding of the metal members is performed first to the two metal members. Completed within a predetermined energization period, and after the completion of the fusion bonding, while continuing the pressurizing process on both metal members,
The power supply process during the power supply period is intermittently continued or gradually regulated.

Further, in order to achieve the above object, a metal bonding structure according to the present invention has the following configuration.

That is, even after the iron-based first metal member and the light alloy-based second metal member are metallurgically welded by heat treatment and pressure treatment, the pressure treatment on these metal members is continued. And a metal bonding structure formed by continuing the heat treatment for the first metal member for a predetermined time.

[0011] Further, a metal joining structure in which an iron-based first metal member and a light alloy-based second metal member are fusion-bonded by an energizing process and a pressing process in electric resistance welding,
An iron-based first metal member coated with a eutectic alloy;
The light alloy-based second metal member is metallurgically melt-bonded within the first predetermined energization period to the metal members, and after the completion of the melt-bonding, the pressure treatment on both metal members is not performed. It is characterized by being formed by being continued and energization processing during the energization period being intermittently continued or gradually regulated.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings by applying the present invention to a case where a valve seat is welded to an opening of an air supply / exhaust port provided in an engine cylinder head as an example. I do. In each embodiment described below, so-called electric resistance welding is employed as specific means of the heat treatment and the pressure treatment when performing welding.

First Embodiment <Method of Joining Metal Members> First, a method of joining metal members (welding method) in the first embodiment will be described.

FIG. 1 is a cross-sectional view of a main part of a portion to be joined in the first embodiment of the present invention, showing an opening peripheral portion of an intake / exhaust port of a cylinder head 2.

As shown in FIG. 1, an opening edge of an intake / exhaust port 2b of a cylinder head (hereinafter, head) 2, which is a member to be welded (second metal member), that is, a valve (not shown) when the engine is completed. The ring-shaped valve seat (hereinafter, seat) 3, which is the first metal member, is joined to the contact position at the joining surface 2a (the outer peripheral surfaces 3a and 3b of the seat 3) by a method described later. . A plurality of intake / exhaust ports 2b as shown in FIG. 1 are provided in the head 2 in a substantially square shape when viewed from the lower side of the head. They are joined as shown in FIG.

The inner peripheral surface of the seat 3 is formed in a tapered shape whose diameter decreases upward in FIG. 1 in accordance with the shape of the upper surface of the valve (not shown).

In this embodiment, the head 2 is a metal member made of an Al-based material which is a light alloy material. Also,
The sheet 3 is a metal member (sintered material) made of an Fe-based material, and a Cu-based material as a high electrical conductivity material is infiltrated therein.

FIG. 2 is an enlarged sectional view showing the structure of the joint surface between the cylinder head and the valve seat according to the first embodiment of the present invention. The head 2 and the seat 3 are made of Zn, It is metallurgically bonded by a three-element bonding layer (bonding layer 10) of about 0.3 μm mainly containing Al and Fe.

Hereinafter, a method of joining the head 2 and the sheet 3 for realizing the above-described joining structure will be described in detail.
In the manufacturing process described below, the head 2
The operation is performed in a state where the top and bottom of the sheet 3 are opposite to the state shown in FIG.

FIG. 3 is a cross-sectional view showing the shape of the valve seat according to the first embodiment of the present invention before joining. The outer peripheral surfaces 3a and 3b of the sheet 3 are formed in a tapered shape as shown in the figure, and the outer peripheral surface 3a has an angle of θ1 with respect to the vertical direction, and the outer peripheral surface 3b has an angle of θ2 with respect to the horizontal direction. These outer peripheral surfaces 3a and 3b are connected to the head 2 at the time of joining.
Abuts on the opening peripheral portion 2a. Here, the reason why the inner peripheral surface 3c of the sheet 3 is different from the completed shape shown in FIG. 1 is to facilitate gripping / releasing and pressing of the sheet in a manufacturing process described later. Is obtained by general cutting and polishing in a post-process (finishing process).

Prior to joining with the head 2, a brazing material layer (brazing material layer 7) not shown in FIG. 3 is welded to the outer peripheral surfaces 3a and 3b of the sheet 3. This brazing material layer may be formed by immersing the sheet 3 in a molten brazing material and applying general ultrasonic plating to the sheet 3 in that state. Here, the brazing material as the third metal member is a eutectic alloy containing about 95% by weight of Zn and about 5% by weight of a light alloy-based member (in this embodiment, aluminum), or Cu and aluminum. And the melting point of the brazing material layer 7 is lower than that of the sheet 3 and the head 2.

In the present embodiment, the brazing material is welded only to the sheet 3, but the present invention is not limited to this, and the brazing material may be welded to both the head 2 and the sheet 3.

Next, a process of joining the sheet 3 coated with the brazing material layer to the opening peripheral portion 2a of the head 2 by electric resistance welding will be described.

FIG. 4 is a view for explaining a joining process between the cylinder head and the valve seat according to the first embodiment of the present invention.

In this embodiment, heat diffusion generated between the peripheral edge portion 2a of the head 2 and the outer peripheral surface of the sheet 3 when pressing and energization are started is applied to the peripheral edge portion 2a of the head 2 between the two members. A taper is provided in advance so as to perform as evenly as possible on the contact surface, that is, to prevent a local heat spot from being generated on the head 2 side due to a temperature rise due to energization. In the joining step, first, a sheet 3 previously coated with a brazing material layer is brought into contact with the tapered opening peripheral portion 2a as shown in FIG.

Next, a sheet 3 is formed by a welding electrode (not shown).
Is pressed as shown in FIG. 4B, and power is supplied to the welding electrode. Opening edge 2a and outer peripheral surface 3 of sheet 3
There is an electrical resistance on the contact surface (contact surface) with a and 3b. For this reason, the contact surface is in a heated state by continuing the energized state, and by continuing the heated state and the pressurized state, the sheet 3 becomes as shown in FIG.
Is welded to the head 2 in a state of being buried up to the state shown in FIG.

In a manufacturing process to be described later, the above-described bonding process shown in FIG. 4 is executed in water or near a bonding portion while water is injected in order to perform better bonding between the head 2 and the sheet 3 (details). Will be described later).

Next, the head 2 to be joined as shown in FIG.
FIG. 5 shows the state transition at the joint surface between the sheet 3 and the sheet 3.
This will be described with reference to FIG.

FIG. 5 is a diagram showing a state transition of the joint surface between the cylinder head and the valve seat according to the first embodiment of the present invention. FIG. 6 is a diagram schematically showing the composition of the joint surface between the cylinder head and the valve seat according to the first embodiment of the present invention.

FIG. 5A shows a structure of a portion to be joined (corresponding to the outer peripheral surfaces 3a and 3b) of the sheet 3 covered with the eutectic alloy brazing material layer 7, and the brazing material layer 7 Thickness 1
It is welded to the sheet 3 via a molten reaction layer 5 of μm or less. FIG. 6A shows the composition of the sheet 3 covered with the brazing material layer 7, and the molten reaction layer 5 is composed of Fe and the brazing material layer 7.
A diffusion layer composed of a brazing filler metal component diffused from the metal is formed. In other words, the molten reaction layer 5 is formed by diffusing the Zn component of the brazing filler metal layer 7 to the valve seat 3 side.
This is a diffusion layer made of Zn.

Next, when the sheet 3 covered with the brazing material layer 7 and the head 2 are brought into contact with each other and the energization and pressurization by the welding electrode not shown in FIG. As shown in (b), the brazing filler metal layer 7 and the joining target portion (opening peripheral portion 2a) of the head 2 are joined via the melting reaction layer 6, whereby the sheet 3 and the head 2 are caused to undergo a melting reaction. Bonding (liquid phase diffusion bonding) is achieved via the layers 5 and 6 and the brazing material layer 7 sandwiched between the molten reaction layers. At this time, the total thickness of the molten reaction layer 5, the brazing material layer 7, and the molten reaction layer 6 is preferably about 0.3 to 1.0 μm.

FIG. 6 (b) shows the composition of the joining portion between the sheet 3 and the head 2 in the state shown in FIG. 5 (b), and shows the lower side of the brazing material layer 7 welded to the sheet 3. In
By joining the head 2, the Al and brazing material layer 7 are formed.
Further, a diffusion layer (melt reaction layer 6) composed of a brazing material component diffused from the above is further formed. That is, the molten reaction layer 6 is an Al-Zn diffusion layer formed by liquid-phase diffusion of the Zn component of the brazing material layer 7 toward the cylinder head 2 in a molten state. The melting point of the brazing material layer 7 is lower than those of the sheet 3 and the head 2.

Here, the diffusion reaction in the state shown in FIGS. 5B and 6B will be described in more detail. In this embodiment, the brazing material layer 7 has a thickness of about 95 as described above.
It consists of a eutectic composition of about 5% by weight of a Zn component and about 5% by weight of an Al component. Therefore, the melting point of the brazing material layer 7 is about 380 ° C.
, It melts all at once shortly after the start of energization. Then, as the energization and the pressurization are continued, the contact surface between the sheet 3 and the head 2 also starts melting.
As shown in FIG. 2B, the corner between the joining surface 3a and the joining surface 3b of the sheet 3 has a fitting surface with the head 2 (opening edge 2).
The sheet 3 is buried in the head 2 while plasticizing a). Thus, even if an oxide film is formed on the joint surface 2a of the head 2, the oxide film can be broken by the plastic flow. At this time, the Zn component of the molten brazing material is liquid-phase diffused toward the head 2 to form a molten reaction layer 6 made of Al-Zn.
Due to this diffusion reaction, the ratio of the Zn component of the brazing filler metal layer 7 at the joint site side with the head 2 is reduced (the ratio of the Al component is increased), so that the melting point of the molten reaction layer 6 is as high as about 500 ° C. or more. It has a melting point and solidifies as a result.

Next, from the state shown in FIGS. 5 (b) and 6 (b) where the above-mentioned molten reaction layer 6 is formed, the energization and pressurization are further continued, so that the brazing material layer 7 is still molten. As shown in FIG. 5C, the brazing material in the state, that is, the unreacted brazing material at the time of forming the molten reaction layer 6, is disposed between the joining surfaces of the sheet 3 and the head 2 (the molten reaction layers 5 and 6). During the period, the oxide film is discharged together with the components and stains of the oxide film peeled from the head 2 by the plastic flow. FIG. 6 (c)
The composition of the joining portion between the sheet 3 and the head 2 in this state is shown.

Next, from the state shown in FIG. 5 (c) and FIG. 6 (c) where the brazing material layer 7 has been discharged, the energization and pressurization are further continued, so that the molten reaction layer on the sheet 3 side is obtained. Reaction layer 5 (diffusion layer) with the molten reaction layer 6 on the head 2 side
A diffusion reaction occurs between the two, and as a result, a bonding layer 10 shown in FIG. 5D is formed. FIG. 6D shows a state in which the bonding layer 10 is formed, and between the sheet 3 and the head 2, F has formed molten reaction layers 5 and 6.
A three-element alloy layer of e, Al, and Zn is formed.

FIG. 7 is a view showing the composition of the joint surface between the valve seat and the cylinder head according to the first embodiment of the present invention. The horizontal axis represents the position in the direction perpendicular to the joint surface, and the vertical axis represents the position. Represents the component ratio of each metal material (however,
It is not a graph showing the relationship between the actual content ratios of the respective metal materials on the bonding surface).

As shown in the figure, a bonding layer 10 is formed between the sheet 3 and the head 2, and a three-element alloy layer of Fe, Al and Zn is formed in the bonding layer and in the vicinity thereof. Are formed. Here, Cu was included to infiltrate the pores inside the sheet 3 as a sintered material.

As described above, according to the bonding method according to the present embodiment described above, the sheet 3 and the head 2 are connected to the brazing material layer 7.
Is metallurgically welded by the bonding layer 10 without passing through.
Thereby, Fe-A is applied to the joint surface between the sheet 3 and the head 2.
1 can be prevented from being formed, and the bonding strength between the sheet 3 and the head 2 can be significantly increased by the bonding layer 10 which is a three-element alloy layer of Fe-Al-Zn. be able to.

Ultrasonic plating was performed so that the thickness of the brazing material layer 7 and the molten reaction layer 5 welded to the sheet 3 was 1 μm or less. Thereby, when the molten reaction layer 5 is formed, the Fe component on the sheet 3 excessively diffuses to the brazing material layer 7 side, and as a result, the amount of the brazing material component contained in the formed molten reaction layer 5 is increased. The composition can be prevented from largely deviating from the original eutectic composition of the brazing material layer 7 or the composition in the vicinity thereof, and a large amount of the brazing material component deviating from the eutectic composition or the composition in the vicinity thereof is contained in the molten reaction layer 5 in a large amount. Can be prevented. Generally, the melting point of the Al-based head 2 is lower than the melting point of the Fe-based sheet 3. For this reason, in order to weld the sheet 3 without breaking the shape of the head 2, it is necessary to perform welding in the shortest possible time. However, as described above, in the present embodiment, the welding between the sheet 3 and the brazing material layer 7 is performed. Even after the molten reaction layer 5 is formed therebetween, the composition of the brazing filler metal component contained in the reaction layer can be maintained at the original eutectic composition or a composition in the vicinity thereof. When the sheets 3 are joined together, the amount of heat input for melting the brazing material layer 7 can be minimized, and the joining of both members can be performed in a short time. Softening can be suppressed, and the effect of destroying the oxide film and the effect of discharging the brazing material can be effectively enhanced.

When the sheet 3 and the head 2 are joined, the brazing filler metal component of the brazing filler metal layer 7 diffuses toward the head 2 to form a molten reaction layer 6, so that the melting point of the reaction layer is about 500 ° C. Since it has been increased to the above, after the joining is completed, it has heat resistance higher than the melting point of the brazing material used.

Further, since the Cu-based material having high electric conductivity is infiltrated into the sheet 3, the pores inside the sheet 3, which is a sintered material, are filled with the Cu-based material. For this reason, it is possible to prevent the holes from being crushed by the pressing force at the time of joining, to add flow of the joining surface 2 a of the head 2, to suppress heat generation inside the sheet 3 due to energization, and to form the brazing material layer 7. Melting and discharging can be performed efficiently.

Further, in the present embodiment, the sheet 3 and the head 2 are joined in a state where the sheet 3 and the head 2 are submerged as described later or while water is injected (sprayed) near the joining target portion. Of these joining methods, when joining while pouring water,
Bubbles are generated when the water injected into the portion to be welded is brought into a boiled state with energization of the welding electrode, but the brazing material layer 7 is previously formed on the surface of the sheet 3 as described above. Therefore, the bubbles can be extruded together with the molten brazing material. Thereby, it is possible to easily prevent the formation of blow holes (bubbles) inside the bonding layer 10 after the solidification.

(Cooling of the part to be welded)
The effect of cooling at the time of joining the head and the head 2 will be described.

In the present embodiment, when the sheet 3 and the head 2 are joined by the above-described joining method, the vicinity of the joining surface is cooled in water as shown in FIG. Alternatively, cooling is performed by injecting water near the joining target portion. Thus, sheet 3
By joining while cooling the head 2, and the welding electrode 24, the following specific effects can be obtained.

That is, at least the head 2 is cooled by the cooling water.
By cooling the water, the water in contact with the head 2
Since it directly functions as a coolant for controlling the temperature of the head 2, it is possible to prevent an excessive rise in the temperature of the head 2, as compared with a case where the joining is performed in air where it is difficult to control the temperature of the joining surface. The surface bonding process can be easily controlled to an optimum state. That is, unnecessary plastic deformation of the head 2 having a lower melting temperature (melting point) than that of the sheet 3 can be prevented, and the sheet 3 and the head 2 can be joined with optimal strength. Variations in the quality of the parts can be suppressed.

Further, by cooling the sheet 3 at the time of joining, the sheet 3 having a considerably small volume and a small heat capacity with respect to the head 2 becomes excessively and rapidly before being joined to the joining surface 2a of the head 2. In this case, it is possible to prevent the sheet from being brought into a high temperature state, and to prevent the deformation of the sheet and the quenching caused by the temperature drop after the completion of the energization.

Also, by cooling the welding electrode 24 at the time of joining, a large temperature change of the electrode itself due to joining, which is a main factor of deterioration of the electrode, can be reduced by the cooling water. It is possible to suppress wear of the electrode caused by alloying the burr generated at the joint portion with the head 2 and the welding electrode 24 made of Cu. Therefore, one welding electrode can be used for a long time in a mass production process. In addition, since the cooling water is present between the welding electrode 24 and the head 2, the aluminum on the bonding surface 2 a, which is melted by energization, is also prevented from scattering from the bonding portion. Welding near the end can be prevented.

Furthermore, by joining the sheet 3 and the head 2 in a state of being submerged, there is no need to provide a water passage in the electrode for cooling the welding electrode. This allows
As described below, a mechanism for holding the sheet 3 inside the electrode 24 can be provided, and mass productivity can be improved.

<Metal Joining Apparatus> Next, a metal joining apparatus (ring member welding apparatus) for joining the sheet 3 and the head 2 as described above will be described. In the following description, the overall configuration of the metal joining apparatus, operation control processing during welding, a method of applying and applying pressure during welding, and a gripping mechanism that grips the sheet 3 will be sequentially described.

(Overall Configuration of Metal Bonding Apparatus) FIG. 10 is a diagram showing a system configuration of the metal bonding apparatus according to the first embodiment of the present invention.

The metal bonding apparatus shown in the figure is roughly divided into an electric resistance welding unit 21, an XY stage 26, a cooling water temperature control / circulation control unit 31, and a control unit 10
0, and each of these components is
The operation is controlled by the control unit 100. In addition, a general method is used for position detection and operation control itself associated with the movement of each component, and the following description focuses on operation control of the entire system.

The electric resistance welding unit 21 includes a platen 2
The welding electrode 24 attached via 3 can be moved in the Z direction shown in FIG. 10 by the pressurizing cylinder 22, and can be rotated by an arm (not shown). Also,
The welding electrode 24 includes a mechanism for holding and releasing the sheet 3 (details will be described later).

As a specific operation, when the welding process is started, the electric resistance welding unit 21 moves the welding electrode 24 to a sheet supply position (not shown) and holds the sheet 3 at that position. Then, the electric resistance welding unit 21 sets the welding position of the target head 2 (opening edge 2a).
Next, the welding electrode 24 is moved while the sheet 3 is held, and electric resistance welding of the sheet 3 to the position is performed.

The XY stage 26 can move a water tank 28 filled with cooling water in the X and Y directions shown in FIG. As a specific operation, prior to the start of the welding process, the XY stage 26 moves the water tank 28 to a predetermined position (container supply / discharge position) indicated by a broken line in FIG. When the container 27 on which is set is transferred by the transfer device (not shown) into the water tank 28, the water tank 28 is moved to a predetermined welding start position (HP). The container 27 is provided with a metal member (not shown) for conducting electricity that is paired with the welding electrode 24.

When the welding process is started, each time the welding of one sheet 3 by the electric resistance welding unit 21 is completed, the XY stage 26 moves to the next welding position of the target head 2 (opening edge). The operation of moving the water tank 28 so that the portion 2a) is located immediately below the welding electrode 24 is repeatedly performed, and the sheet 3 is attached to all the heads 2 in the container 27.
Are joined, the XY stage 26 moves the water tank 28 again to the predetermined position indicated by the broken line in FIG.

The cooling water temperature control / circulation control unit 31
-The cooling water in the container 27 on the Y stage 26 is circulated through the expandable and contractible cooling water circulation pipe 30, and the temperature is adjusted to maintain the predetermined temperature.

(Operation Control Process at the Time of Welding) Here, the operation control by the control unit 100 will be described. As the control unit 100, a computer, a PLC (programmable controller) or the like may be employed, and a CPU (not shown) of the control device may execute software for realizing the control processing shown in FIGS. .

FIG. 11 is a flowchart showing an operation control process of the metal bonding apparatus according to the first embodiment of the present invention. Here, the control unit 100 includes the welding electrode 24.
H. P and the sheet supply position, and the H.P. P, container supply / discharge position, and opening peripheral portion 2a of each of a plurality of heads 2 in the container
Is stored in advance in order to dispose immediately below the welding electrode 24. Note that these pieces of information may be stored in the electric resistance welding unit 21 and the XY stage 26.

In the figure, steps S1 and S
2: The water tank 28 on which the container 27 is placed, which is located at the container supply / discharge position indicated by the broken line in FIG.
H. set in advance The XY stage 26 is controlled to return to P (step S1), and the welding electrode 24
Grasps the sheet 3 at the sheet supply position and sets a preset H.G. The electric resistance welding unit 21 is controlled to return to P (Step S)
2).

Step S3: Whether or not preparation for welding is completed, that is, the water tank 28 on which the container 27 is placed and the welding electrode 24 are It is determined whether or not it has returned to P.

Step S4: YE is determined in step S3.
In the case of S (when the preparation is completed), a welding process described later with reference to FIG. 12 is performed.

Step S5: It is determined whether or not the welding of the sheet 3 has been completed for each of the opening peripheral portions 2a of all the heads 2 in the container 27. If YES (all has been completed), the process proceeds to step S8, and NO When there is an unprocessed opening peripheral portion 2a, steps S6 and S7 are performed.
Proceed to.

Step S6, Step S7: Step S
If the determination in step 5 is NO, the X-ray tank 28 is moved so as to move the water tank 28 to the opening peripheral portion 2a to be welded next to the head 2 in the container 27 in accordance with the position information stored in advance.
In addition to controlling the Y stage 26 (step S6), the welding electrode 24 grips the sheet 3 at the sheet supply position, and sets the welding electrode 24 to the H.S. P
The electric resistance welding unit 21 is controlled so as to return to (Step S7). When the processing in steps S6 and S7 is completed, the process returns to step S3.

Step S8: YE is determined in step S5.
In the case of S, it indicates that the sheets 3 have been joined to all the heads 2 in the container 27, so that the water tank 28 is moved to the container supply / discharge position by XY.
Controls the stage 26 and returns.

After that, the container 27 where the welding process is completed
1 is discharged from the water tank 28 by a transfer mechanism (not shown), and a general cutting process is performed on an inner peripheral surface portion, an upper surface portion, and the like of the sheet 3 in a finishing process, and thus is illustrated in FIG. Get the finished shape.

FIG. 12 is a flowchart showing details of the welding (electric resistance welding) processing included in the operation control processing according to the first embodiment of the present invention.
Equivalent to 4.

In the figure, step S41: sheet 3
Pressurizing cylinder 22 of electric resistance welding unit 21 so as to lower welding electrode 24 in a state where
Control.

Step S42: When the sheet 3 comes into contact with the opening peripheral portion 2a to be welded this time by the lowering of the welding electrode 24, the electric resistance welding unit 21 starts the energizing operation and the pressing operation.

Steps S43 and S44: When a predetermined time has elapsed after the energizing operation and the pressurizing operation have been started (step S43), an intermittent energizing process described later or energizing is performed while the pressurizing operation is continued. The electric resistance welding unit 21 is controlled to perform the regulation process (step S44).
Control. Here, the predetermined time is set between the sheet 3 and the head 2
Is the time required to complete the metallurgical fusion bonding as described above, and is set in advance.

Step S45: After the intermittent energization processing or the energization restriction processing has been performed for a predetermined period, the electric resistance welding unit 21 is controlled so as to raise the welding electrode 24 so as to end the energization and pressurization. At this time, the method of releasing the sheet 3 held by the welding electrode 24 is as follows.
There is a first method in which the sheet 3 is lifted after releasing the sheet 3 from the welding electrode 24, and as another method, since the sheet 3 is joined to the head 2, the ejection force is smaller than the strength due to the joining. There is a second method in which the sheet 3 is gripped in advance by the welding electrode 24 so that the sheet 3 is released, and the gripped sheet is dynamically released as the electrode 3 is lifted. . Which method is adopted may be determined according to the mechanism of the welding electrode 24 described later. However, in a mass production process in which one step must be completed in as short a time as possible, it is preferable to use the second method in which the release operation of the sheet 3 does not need to be performed.

As described above, in the present embodiment, since the welding electrode 24 has the gripping mechanism for the sheet 3 and the electrode itself can rotate together with the arm (not shown), the welding electrode 24 is newly moved to the sheet supply position. You can go to get a good sheet 3. Further, the XY stage 26 can sequentially move the welding target portions of the plurality of heads 2 to a predetermined welding position (immediately below the HP of the welding electrode 24). For this reason, the electric resistance welding unit 21 and the X-
Only by operating the Y stage 26 in cooperation, the sheet 3 and the head 2 can be joined with high accuracy, and mass productivity can be ensured.

(Method of Energizing and Pressing During Welding) Next, a method of energizing and pressing during welding will be described.

FIG. 13 is a diagram showing the energizing and pressing patterns during electric resistance welding according to the first embodiment of the present invention. FIG. 14 is a diagram illustrating a temperature change of the cylinder head when the energization pattern at the time of the electric resistance welding according to the first embodiment of the present invention is executed.

In the present embodiment, the energizing operation for the sheet 3 and the head 2 is performed in a pulsed manner as shown in FIGS. 13 and 14 (approximately 70 kA is applied during the energizing ON period, and 0 A is applied during the OFF period). Intermittently). The reason why the current is applied to the welding electrode 24 in such a procedure is that the temperature of the sheet 3 after the welding is completed is gradually lowered, and the temperature of the sheet 3 is rapidly lowered, so that the sheet is excessively hardened ( So-called quenching)
This is to prevent

The energizing and pressing patterns will be described more specifically. In the present embodiment, the welding electrode 24 holding the sheet 3 is brought into contact with the head 2, and energization is started while being pressed by the pressing cylinder 22. At this time, a predetermined current flows from the sheet 3 to the head 2. The pressing force is
It is desirable to be about 29420 N (3000 kgf). Then, as shown in FIG. 13, while maintaining this pressing force,
By starting energization about 1.5 seconds after the start of pressurization, the brazing material layer 7 is melted. The current value at this time is
About 70 kA is desirable. The energization time during the ON period is 0.25 to 1 second, and the OFF period is about 0.1 to 0.5 second. The number of pulses during energization is preferably 3 to 9 (4 in FIGS. 13 and 14). The time from the start of pressurization to the start of energization of the first current pulse and the time from the stop of energization of the last pulse to stop of pressurization were 1.5 seconds.

FIG. 14 shows a temperature change of the sheet 3 when such an intermittent energization is performed. Since the heat capacity of the sheet 3 made of Fe element material is considerably small, the temperature rise due to the resistance heat generated when the sheet 3 is energized is large. It is difficult to dissipate heat compared to the upper and lower ends where heat is easy to dissipate, and during the ON period of the first current pulse, the contact resistance between the sheet 3 and the head 2 is higher than after the joining is completed. Is also big. Therefore, sheet 3
The temperature at the center in the up-down direction is equal to or higher than the transformation point A1 when the first current pulse is stopped.

At this stage, the sheet 3
4 is almost completely buried (see FIG. 4).
(Refer to (c)). Therefore, it is possible to completely stop the energization. In this case, the sheet 3 is rapidly cooled from the temperature of the transformation point A1 or higher. Will burn and the hardness will increase.

Therefore, in the present embodiment, a second current pulse is applied when the temperature drops slightly. At this time, the metallurgical joining between the sheet 3 and the head 2 has been completed, and the contact resistance between the sheet 3 and the head 2 is reduced unlike when the first current pulse is applied. Therefore, the amount of heat generated by the resistance decreases in accordance with the decrease in the contact resistance, and heat is radiated from both members. For this reason, even if the second current pulse has the same current value as the first current pulse, a large temperature rise does not occur. The sheet 3 can be gradually cooled by repeatedly performing the same intermittent energization after the third time, so that the hardness of the sheet 3 hardly increases. By performing such intermittent energization, in the present embodiment, quenching of the sheet 3 can be prevented,
It is possible to prevent the workability from deteriorating when cutting is performed in the finishing step, which is a subsequent step. Further, the wear of the valve due to the valve contact surface of the cut sheet 3 being too hard can be effectively suppressed.

In the present embodiment, when the above-described intermittent energization is performed, the pressurized state is continued with the same pressing force from the start of the first press. This is to maintain the same pressing force until the molten reaction layer 6 is completely solidified and cooled, thereby preventing separation and cracking of the two members at the joint surface due to the difference in the coefficient of thermal expansion between the sheet 3 and the head 2. That's why.

In the above-described intermittent energization shown in FIGS. 13 and 14, a method in which a current pulse of the same pattern is energized a plurality of times is not limited thereto. If the metallurgical joining with the head 2 can be completed, a method of gradually restricting the energization mode after the joining may be adopted. More specifically,
In the pattern shown in FIG. 15A, the sheet 3 and the head 2
After the metallurgical joining with the metal is completed, the current flowing is continuously reduced. In the pattern shown in FIG. 15B, the energization is temporarily stopped after the metallurgical joining between the sheet 3 and the head 2 is completed, and thereafter, the energized current is continuously reduced. In the pattern shown in FIG. 15C, the sheet 3 and the head 2 are driven by the first current pulse.
After completing the metallurgical joining with the current pulse, a current pulse having a smaller current value than the first current pulse is supplied a plurality of times. In each of the patterns shown in FIGS. 15A to 15C, a predetermined pressure is applied as in the case of FIG.

(Sheet gripping mechanism) Next, the sheet gripping mechanism of the welding electrode 24 will be described. In the present embodiment, the welding electrode 24 includes a holding mechanism that can hold the sheet 3 near the front end. For the specific mechanism,
There are three types of mechanisms described below.

FIGS. 16 and 17 are views for explaining the structure of the welding electrode as the first embodiment of the present invention, and show a case where a collet chuck is provided near the tip of the electrode.

Referring to FIG. 16 and FIG.
16A, a piston 24A-2 that operates in accordance with control air supplied and exhausted from the air supply / exhaust hole 24A-1, and a collet chuck 24A-3 that can move up and down in FIG. Is provided. When the piston 24A-2 is located at the top dead center, the collet chuck 24A-3 is in an expanded state at the positions H1 and H2, and can hold the sheet 3 on its inner peripheral surface. 16 and 17 when the piston 24A-2 is located at the bottom dead center.
As shown by the broken line, the leading end portion is in a state of being narrowed, and the sheet 3 can be released or set.

FIGS. 18 and 19 show the first embodiment of the present invention.
FIG. 4 is a view for explaining the structure of a welding electrode as an embodiment of the present invention, and shows a case where a sheet 3 is held by air released from the vicinity of the tip of the electrode.

In FIG. 18 and FIG.
B, a cooling water passage 24B-1 and a vent hole 24B for discharging air from the air discharging hole 24B-3.
-2 is provided. The welding electrode 24B can hold the sheet 3 at the positions H1 and H2 by discharging air from the air discharging holes 24B-3 under the control of the electric resistance welding unit 21, and when the sheet is released or set, What is necessary is just to stop the discharge of air from the air discharge hole 24B-3.

The water passage 24B-1 can be omitted when the welding electrode 24B is immersed in the cooling water during welding.

FIGS. 20 and 21 show the first embodiment of the present invention.
FIG. 4 is a view for explaining the structure of a welding electrode as an embodiment of the present invention, and shows a case where a sheet 3 is held by air released from the vicinity of the tip of the electrode.

In FIG. 20 and FIG.
A suspension ring 24C-2 is provided at the leading end of C, and by applying tension to the inner peripheral surface of the seat 3 by the restoring force of the suspension ring, the seat can be gripped at the positions H1 and H2. it can. In this case, no special control operation for releasing and setting the gripped sheet 3 is required.

Further, a cooling water passage 24C-1 is provided inside the welding electrode 24C.
The value of -1 can be omitted when the welding electrode 24C is also submerged in the cooling water during welding.

The welding electrode 24 according to the present embodiment includes
Any type of the welding electrodes 24A to 24C may be employed. However, step S4 of the welding process of FIG.
When the electrode is raised at 5, the welding electrode 24
In the case of A, the sheet 3 needs to be released. In the case of the welding electrode 24B, the sheet 3 may be released by stopping the supply of air to the ventilation holes 24B-2, but at this time, the sheet 3 is joined to the head 2. Therefore, the release operation of the sheet 3 prior to the elevation of the welding electrode 24B may be omitted by supplying air that holds the sheet 3 at a strength lower than the strength due to the joining. In the case of the welding electrode 24C,
By adopting the suspension ring 24C-2 having a gripping force weaker than the strength of the joint between the sheet 3 and the head 2, the gripped sheet may be released mechanically with the raising operation of the electrode.

As described above, according to this embodiment, the sheet 3 and the head 2 can be welded in a short time and with high joining strength, and the welding method can be easily realized in a mass production process. A metal joining device is realized. This makes it possible to significantly reduce the size and thickness of the seat as compared with a general method of press-fitting the valve seat into the cylinder head. A structure in which the diameter of the throat is reduced and the diameter of the throat is increased can be adopted, and the performance, reliability, and design freedom of the engine can be improved.

In the first embodiment, two types of tapers 3a and 3b are provided on the outer peripheral surface of the sheet 3. However, the present invention is not limited to this. In order to make the heat diffusion generated between the head 2 and the taper surface easier, the taper surface provided on the opening peripheral portion 2a of the head 2 and the taper surface provided on the outer peripheral surface of the sheet 3 should be in contact with the whole. Is also good.

In the present embodiment, the sheet 3 is manufactured by sintering and the Cu-based material is infiltrated therein. However, if the density inside the sheet 3 is secured to some extent, the Cu-based material is not necessarily required. There is no need to infiltrate the material. Also,
By forming the sheet 3 as a sintered forged material obtained by forging after sintering, pores inside the sheet 3 may be eliminated.

Further, in this embodiment, the brazing material layer 7 is heated to a temperature equal to or higher than the melting point of the brazing material component in the brazing material layer 7 due to the heat generated by energization between the sheet 3 and the head 2. However, the present invention is not limited to this, and the brazing material layer 7 may be melted by local heating such as high-frequency heating.

In this embodiment, the material of the brazing material is
Although a Zn-Al eutectic alloy containing 95% by weight of Zn is used, a eutectic composition or a composition near the eutectic composition (for example, a Zn-Al-based alloy containing 92 to 98% by weight of Zn.
The melting point of the brazing material layer 7 can be set to 400 ° C. or less, the deformation of the sheet 3 and the melting or softening of the head 2 can be more reliably prevented, and the bonding strength between the sheet 3 and the head 2 can be effectively improved. be able to.

[Second Embodiment] In the above-described first embodiment, the joining surface 2a of the head 2 is tapered in advance. However, in the present embodiment, the joining portion of the head 2 with the sheet 3 is tapered. A case will be described in which a state in which the air supply / exhaust port is formed in the head 2 and which has a substantially right-angled edge is not used. The other configuration is the same as that of the first embodiment, and the description is omitted.

FIG. 22 is a view for explaining the joining process between the cylinder head and the valve seat according to the second embodiment of the present invention. In this figure, as in FIG. Expressions are omitted.

In the present embodiment, as shown in FIG. 22 (a), the joint portion of the head 2 with the sheet 3 remains in a state having a substantially right-angled edge.
Then, the sheet 3 is brought into contact, and the above-described energizing operation and pressurizing operation are performed (see FIG. 22B). At this time, the sheet 3 is embedded in the head 2 while the head 2 is caused to flow plastically by the joint surface 3a and the joint surface 3b of the sheet 3. When the fitting is completed, the sheet 3 is completely embedded in the head 2 as shown in FIG. 22C, and the metallurgical joining is completed.

As described above, if the head 2 is not provided with a taper at the joint portion with the sheet 3 and the head 2 has a substantially right-angled edge formed when the air supply / exhaust port is formed in the head 2, the joint becomes In this case, when the sheet is brought into contact, a heat spot appears at the right angle portion, so that the sheet is easily melted locally. However, in this embodiment, as shown in FIG. 22C, the amount of plastic deformation of the head 2 at the time of joining is larger than that of the head 2 described in the first embodiment, so that an oxide film Even if is adhered, the oxide film can be more efficiently removed by the plastic deformation of the joining portion, and the adverse effect of the oxide film can be prevented. As shown in FIG. 22 (c), the amount of Al protruding into the intake / exhaust port 2b due to plastic deformation at the time of joining increases as compared with the first embodiment. Even in the finishing step performed in the first embodiment, it can be cut off, and a new finishing step for cutting off the projecting portion does not occur. Therefore, according to the present embodiment, the sheet 3 and the head 2 can be welded in a short time and with high joining strength as in the first embodiment, and further compared with the case of the first embodiment. Thus, productivity can be improved by omitting the step of providing the head 2 with a taper.

In each of the above embodiments, the welding electrode 2
Although the system configuration 4 is to pick up the sheet 3 at a predetermined position, the system may be configured such that the electrode moves only in the Z direction and the sheet 3 is supplied to the electrode from the outside.

The refrigerant is not limited to water.
For example, if alkaline ionized water is used, there is obtained an effect that an oxide film can be prevented from adhering to the joint surface (joining portion) of the Al head without adversely affecting the Fe sheet. In particular, if the alkaline ionized water having such characteristics is used as a coolant for the tapered head 2 described in the first embodiment, the sheet 3
It is possible to almost completely prevent the oxide film from adhering to the joining surface with the head 2. Therefore, even if the amount of plastic deformation at the time of joining is smaller than that of the head 2 described in the second embodiment, the amount of the oxide film can be reduced. This is a particularly effective refrigerant in that adverse effects can be prevented.

[0102]

As described above, according to the present invention,
It is possible to provide a metal welding method and a metal bonding structure that prevent quenching and deformation of an iron-based first metal member, and satisfactorily bond metal members having different melting points.

That is, according to the first and seventh aspects and the thirteenth and fourteenth aspects of the present invention, the pressurizing process is continued even after the metallurgical welding is completed, so that the first metal member Deformation is prevented, and the heat treatment is continued for a predetermined time, so that it is possible to prevent a rapid decrease in temperature of the first metal member and prevent quenching of the member. In particular, according to the seventh and fourteenth aspects of the present invention, the temperature of the first metal member can be gradually reduced, so that quenching of the member can be reliably prevented.

Further, claim 3, claim 4, and claim 9
According to the invention, since a bonding layer having good compatibility with the first and second metal members is formed on the bonding surface of the first and second metal members, the bonding strength can be increased as compared with a case where the two members are directly bonded. .

According to the invention of claim 8, when the first and second metal members are joined, the plastic deformation of the second metal member is large, so that an oxide film and dirt can be efficiently removed.

According to the eleventh aspect, unnecessary melting of the second metal member having a lower melting point than that of the first metal member can be prevented, and the first metal member is excessively heated. This can prevent quenching beforehand.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a portion to be joined according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a structure of a joint surface between a cylinder head and a valve seat according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a shape of a valve seat before joining according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating a joining process of the cylinder head and the valve seat according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a state transition of a joint surface between a cylinder head and a valve seat according to the first embodiment of the present invention.

FIG. 6 is a diagram schematically illustrating a composition of a joint surface between a cylinder head and a valve seat according to the first embodiment of the present invention.

FIG. 7 is a diagram showing a composition of a joint surface between a valve seat and a cylinder head according to the first embodiment of the present invention.

FIG. 8 is a diagram showing a state of cooling (joining in water) at the time of joining the valve seat and the cylinder head according to the first embodiment of the present invention.

FIG. 9 is a diagram showing a state of cooling at the time of joining the valve seat and the cylinder head according to the first embodiment of the present invention (in a case where water is injected into a joining target portion).

FIG. 10 is a diagram illustrating a system configuration of a metal bonding apparatus according to the first embodiment of the present invention.

FIG. 11 is a flowchart illustrating an operation control process of the metal bonding apparatus according to the first embodiment of the present invention.

FIG. 12 is a flowchart showing details of a welding process included in the operation control process according to the first embodiment of the present invention.

FIG. 13 is a diagram showing an energization and pressurization pattern during electric resistance welding according to the first embodiment of the present invention.

FIG. 14 is a diagram showing a temperature change of a cylinder head when an energization pattern during electric resistance welding is executed in the first embodiment of the present invention.

FIG. 15 is a diagram showing a modification of the energization and pressurization pattern during electric resistance welding according to the first embodiment of the present invention.

FIG. 16 is a view for explaining the structure of a welding electrode as the first embodiment of the present invention (in the case of a collet chuck).

FIG. 17 is a diagram illustrating a structure of a welding electrode as a first embodiment of the present invention (in the case of a collet chuck).

FIG. 18 is a view for explaining the structure of a welding electrode according to the first embodiment of the present invention (when air is discharged).

FIG. 19 is a view for explaining the structure of a welding electrode according to the first embodiment of the present invention (when air is discharged).

FIG. 20 is a view for explaining the structure of a welding electrode as the first embodiment of the present invention (in the case of a suspension ring).

FIG. 21 is a view for explaining the structure of a welding electrode as the first embodiment of the present invention (in the case of a suspension ring).

FIG. 22 is a diagram illustrating a joining process between a cylinder head and a valve seat according to the second embodiment of the present invention.

[Explanation of symbols]

 2: Cylinder head, 2a: joining surface, 2b: supply / exhaust port, 3: valve seat, 5, 6: molten reaction layer, 7: brazing material layer, 10: joining layer, 21: electric resistance welding unit, 22: heating Pressure cylinder, 23: platen, 24, 24A, 24B, 24C: welding electrode, 24A-1: supply / exhaust hole, 24A-2: piston, 24A-3: collet chuck, 24B-1, 24C-1: water passage, 24B-2: vent hole, 24B-3: air discharge hole, 24C-2: suspension ring, 25: water injection nozzle, 26: XY stage, 27: container, 28: water tank, 30: cooling water circulation pipe, 31: Cooling water temperature control / circulation control unit,

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B23K 31/00 B23K 31/00 H 33/00 33/00 Z F01L 3/04 F01L 3/04 3/22 3/22 B 3/24 3/24 E F02F 1/24 F02F 1/24 S // B23K 103: 20 (72) Inventor Yukihiro Sugimoto 3-1, Fuchu-cho Shinchi, Aki-gun, Hiroshima Prefecture Mazda Corporation (72 ) Inventor Yukio Yamamoto 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima F-term (reference) 3G024 AA14 AA15 DA06 FA00 FA04 FA06 FA14 GA18 GA32 HA04 HA06 4E067 AA02 AA05 AB01 AB03 AB04 AB06 BA00 BB02 DB07 EB00

Claims (14)

[Claims] An iron-based first metal member and a light alloy-based second metal member.
A metal welding method for welding a metal member, wherein the first and second metal members are subjected to a heat treatment and a pressure treatment to thereby metallurgically weld the metal members, A metal welding method, wherein the pressure treatment is continued even after the second metal member is welded, and the heat treatment is continued on the first metal member for a predetermined time. 2. The metal welding method according to claim 1, wherein the pressure in the heat treatment for welding the first and second metal members is the same as the pressure in the heat treatment after the welding. . 3. The metal welding according to claim 1, wherein a eutectic alloy layer is formed on a surface of the first metal member before welding the first and second metal members. Method. 4. The first and second metal members comprise a first diffusion layer formed on the first metal member by forming the eutectic alloy layer, and the eutectic alloy in the heat treatment and the pressure treatment. Metallurgy by forming a three-element bonding layer including the first and second metal members and the eutectic alloy with a second diffusion layer formed on the second metal member in contact with a layer; The metal welding method according to claim 3, wherein the metal is welded. 5. The metal welding method according to claim 4, wherein the eutectic alloy layer includes zinc or copper and a light alloy-based member. 6. The heat treatment and the pressure treatment are performed by electric resistance welding.
The metal welding method according to any one of the above. 7. An iron-based first metal member and a light alloy-based second metal member.
A metal welding method for welding a metal member with a current applying process and a pressure process in electric resistance welding, wherein the iron-based first metal member is pre-coated with a eutectic alloy, and the iron is coated with the eutectic alloy. When welding the first metal member of the system and the second metal member of the light alloy system, the metallurgical fusion bonding of the metal members is completed within the first predetermined energization period to both metal members, After the completion of the fusion bonding, while continuing the pressure treatment on the two metal members,
A metal welding method characterized by intermittently continuing or gradually restricting the energizing process during the energizing period. 8. The metal welding method according to claim 7, wherein a joining portion of the second metal member with the first metal member has an edge shape. 9. The first and second metal members include a first diffusion layer formed on the first metal member coated with the eutectic alloy, and a first diffusion layer contacted with the eutectic alloy during welding. The second diffusion layer formed on the second metal member is metallurgically welded by forming the first and second metal members and the three-element joining layer including the eutectic alloy. The metal welding method according to claim 7, wherein: 10. The metal welding method according to claim 7, wherein the eutectic alloy includes zinc or copper and a light alloy-based member. 11. The method according to claim 1, wherein, when the first and second metal members are welded, the vicinity of a joint surface between the metal members is cooled by a coolant from outside. The described metal welding method. 12. The metal welding method according to claim 11, wherein water is used as the refrigerant. 13. Even after metallurgical welding of the first iron-based metal member and the second light-alloy metal member by heat treatment and pressure treatment, the pressure treatment on the metal members is continued. And a heat treatment for the first metal member is continued for a predetermined time. 14. A metal joint structure in which an iron-based first metal member and a light-alloy-based second metal member are fusion-bonded by an energizing process and a pressurizing process in electric resistance welding. A coated iron-based first metal member;
The light alloy-based second metal member is metallurgically melt-bonded within the first predetermined energization period to the metal members, and after the completion of the melt-bonding, the pressure treatment on both metal members is not performed. A metal bonding structure formed by being continued and energization processing during the energization period being intermittently continued or gradually regulated.