JP2002263858A - Method for assembling and welding mechanical component by liquid phase diffusion welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a metal precision mechanical component by liquid phase diffusion welding in assembling the mechanical component internally having complicated and precise pipe lines for carrying liquid and lightening weight. SOLUTION: In the method for assembling and welding the mechanical component by the liquid phase diffusion welding, when the mechanical component having surfaces which are divided into at least two or more is welded and assembled by the liquid phase diffusion welding, the component is heated at a temperature not lower than that of a solidus line of a welding metal foil which is inserted between the welding surfaces within sixty seconds, stress not lower than 2 MPa is loaded on the welding surfaces at 1,000-1,300 deg.C for sixty seconds or more, thereafter the loaded stress is decreased and the component is kept in the state of low stress or no-load for one minute or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various types of mechanical parts manufactured by using a diffusion bonding technique, and more particularly, to machining such as cutting, shaving, punching, and die cutting from a material, or casting directly from a molten metal. The present invention relates to a machine component manufactured by liquid phase diffusion bonding instead of machining of a machine component having an annular or hollow shape by forging or the like.

[0002]

2. Description of the Related Art Conventionally, it has an annular or hollow shape,
In particular, mechanical parts that require various properties such as wear resistance, corrosion resistance, and fatigue resistance individually or simultaneously, and for a long time, such as bearings for rotating parts, bearings, and sliding pipes for cylinders, are required quality. For example, in a bearing steel represented by JIS-SUJ, which has a relatively high alloy ratio, in addition to C: 1% and Cr: 1%, Mn,
Although a steel material containing Mo is used, it is often difficult to assemble parts by welding or the like. For this purpose, machine parts with complex shapes are cut out of massive steel ingots, or roughly formed by hot forging or drilling, and after finishing, spheroidizing and carburizing according to required specifications. And manufacturing. Therefore, the cost of various processing steps in the manufacturing process occupies most of the product price rather than the price of the raw material ingot. On the other hand, precision mechanical parts such as automobiles, which require reliability, are required to have long-term durability at the same time, and are aimed at reducing the specification cost over a long period of time. Therefore, even if expensive, these precision machine parts manufactured from the bulk metal by the conventional manufacturing method are frequently used, which causes a rise in the price of many parts and eventually the price of the final product.

[0003] Of the methods for processing a metal material into an arbitrary shape, hot rolling and press molding are generally employed as methods having the highest mass productivity and low cost. It has a simple shape, often a simple shape such as a plate, and is suitable for mass production.However, it is not possible to directly manufacture hollow machine parts and annular parts with high yield by the above-mentioned rolling and press molding. It is difficult due to its shape, and it is currently not industrialized at all. Therefore, there is no industrially established technology for efficiently mass-producing complicated precision machine parts having an annular or hollow shape. On the other hand, from the viewpoint of cost reduction, the development of a completely different manufacturing process from the past has been awaited. Have been.

On the other hand, recently, the technique of liquid phase diffusion bonding has been spotlighted. In this liquid phase diffusion bonding technique, an alloy having a lower melting point than a material to be bonded, for example, 50% or more of the crystal structure is substantially amorphous, at a bonding surface of a material to be bonded, that is, between grooves. Element which is capable of forming a joint through a diffusion-controlled isothermal solidification process, such as B, P, Ni, Fe, etc. This is a technique in which a joint is formed by heating and holding and isothermal solidification process.

The liquid-phase diffusion bonding technique has features that, unlike ordinary welding techniques, there is almost no welding residual stress, or a smooth and precise joint can be formed without generating excess welding like welding. ing. Moreover, since this technology is surface bonding, the bonding time is constant regardless of the area of the bonding surface,
It has the advantage that the joining is completed in a relatively short time, and is a joining technique completely different from conventional welding. Therefore, if the bonding portion can be maintained at a temperature equal to or higher than the low melting point metal for a predetermined time, bonding between the surfaces can be realized regardless of the groove shape. On the other hand, with respect to the conventional liquid phase diffusion bonding that can be realized only in a non-oxidizing atmosphere, an alloy foil for liquid phase diffusion bonding that can be applied even in an oxidizing atmosphere is known. (Patent No. 1891618
Nos. 1891619 and 1837572). However, at present, this liquid phase diffusion bonding technique is applied only to bonding of members having a relatively large bonding surface area, and is not used for bonding of precision machine parts and the like.

[0006]

SUMMARY OF THE INVENTION The present invention provides a complex precision machine part having an annular or hollow shape and simultaneously satisfying various characteristics of wear resistance, corrosion resistance and fatigue resistance at high efficiency and at low cost. It is an object of the present invention to provide a mass-produced diffusion bonding machine part.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the gist of the present invention is to provide a mechanical part having at least two or more divided surfaces by liquid phase diffusion bonding. At the time of joining and assembling, the temperature of the part is heated to a temperature equal to or higher than the solidus line of the joining metal foil to be inserted between the joining surfaces within 60 seconds, and at a temperature of 1000 to 1300 ° C for 60 seconds or more, preferably 90 to 90 ° C. A method for assembling and joining liquid phase diffusion joining machine parts, wherein a stress of 2 MPa or more is applied to the joining surface for 120 seconds, and thereafter, the applied stress is reduced and held for 1 minute or more in a low stress or no load state. The present invention also relates to a joining metal for inserting a mechanical part having at least two or more divided surfaces into a joining surface by joining the parts by a liquid phase diffusion bonding within 60 seconds. Foil To a temperature above the solidus of
A stress of 2 MPa or more is applied to the joining surface at a temperature of 00 to 1300 ° C. for 60 seconds or more, and then the applied stress is reduced to maintain a low stress or no load state for 1 minute or more. Liquid phase diffusion bonding machine characterized by quenching at a cooling rate of 5 ° C / sec or more to a temperature not lower than the transformation start temperature, allowing it to cool to the end of bainite transformation, and cooling to room temperature at a cooling rate of 1 ° C / sec or more. A method of assembling and joining parts.

Further, the liquid phase diffusion bonding in the present invention is preferably performed in an oxidizing atmosphere.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In carrying out the present invention, the material of a target mechanical part is not particularly limited. The technique of the present invention can be applied to all metal materials that are considered to be capable of liquid phase diffusion bonding. For example, liquid phase diffusion bonding can realize a joining joint even with a material to which normal welding is difficult to apply, such as normal carbon steel, high carbon steel, and low carbon steel. Also,
Stainless steel containing Cr or Ni in various proportions,
Liquid phase diffusion bonding of highly corrosion-resistant alloy steel, Ni-based alloys and other alloys based on Ni, and non-ferrous materials such as Al, Ti, Zn, and other practical metals, all using suitable joining alloys Becomes possible. Further, there is no particular limitation on the amorphous alloy composition for realizing liquid phase diffusion bonding, and the alloys described in U.S. Pat. No. 4,144,058 and those described in JP-A-49-91014 are disclosed. Of P,
Liquid phase diffusion bonding alloys containing B, C, etc. as diffusion atoms can be used.

In the present invention, using the above-mentioned material to be joined and the alloy for liquid phase diffusion bonding, a pipe having a purpose for fluid conveyance, weight reduction, passage of sliding parts, and the like is provided inside. Equipped with precision machine parts originally manufactured by integral molding, each part is first divided into multiple parts on the plane including the pipeline, for example, press molding or rolling, grinding, polishing, etc. It is necessary to carry out a manufacturing process through an inexpensive manufacturing process for a combination of processing, assemble them via a liquid phase diffusion bonding alloy, and integrate them by liquid phase diffusion bonding.

At this time, it is necessary that the parts to be divided be divided by a surface passing through a pipe existing inside in comparison with the final shape. And it can be manufactured by a simple method. Also, this division can be made as many as two or more,
As a result of simplification of the production and complicated or large number of the production steps, it may be appropriately selected within a range where the production steps are not expensive. Further, the division surface may be a flat surface, a curved surface, a continuous or discontinuous multi-surface or a curved surface, and the shape thereof may be appropriately selected so as to facilitate production of each part by dividing. In addition, the conduit inside the component of the final shape may be a single continuous path or a plurality of independent paths, the shape of the conduit itself is free, and the surfaces to be joined at the time of assembly only need to correspond, particularly No restrictions. The conduit can be assembled with or without an opening to the outer surface. In addition, the characteristics of the joint vary variously depending on the combination of the material to be joined and the alloy for liquid phase diffusion joining.

In the present invention, precision machine parts divided into a plurality of parts having a pipe inside as described above, for example,
As shown in FIG. 1, P, B, and P are divided into two parts by a plane parallel to a pipe of an automobile fuel injection valve made of high carbon steel containing 1.0% of Cr and 0.5% of Mo. The above components are assembled by butt-joining each other via a 30 μm-thick liquid-phase diffusion bonding alloy made of a Ni-based or Fe-based amorphous metal containing a small amount of an element such as C, and a holding jig is used from the outer surface of each component. Tighten and fix, and perform liquid phase diffusion treatment.

Further, in the present invention, when the liquid phase diffusion treatment is performed, the temperature is equal to or higher than the solidus temperature of the alloy for liquid phase diffusion bonding, that is, 1000 to 130 when liquid phase diffusion is started.
At a temperature of 0, a stress of 2 MPa or more, preferably 4 MPa or more is continuously applied to the joint surface for 90 to 120 seconds from the start of heating, and thereafter, the applied stress is reduced to maintain a low stress or no load for 1 minute or more. It is. By continuing to apply stress even during the diffusion bonding, the diffusion of the element can be further promoted by applying a considerable stress in a temperature range where the diffusion between the element in the bonding metal and the metal element contained in the bonding part reaches a peak. In order to obtain a strong joint surface. From the time when the liquid phase diffusion bonding is completed, the applied stress is reduced or the stress is released so that the applied state is unloaded, and the state is maintained for 5 minutes or more in order to homogenize the joint structure. By performing the liquid phase diffusion process described above, a required amount of a bonding layer of the metal element contained in the alloy for liquid phase diffusion bonding and the metal element contained in the joined component is formed on the joint surface.

When performing liquid phase diffusion bonding, N ₂ or Ar is blown onto the inner and outer surfaces of the material to be bonded in an oxidizing atmosphere containing 0.01% by mass or more of oxygen, preferably in the air. Preferably, a joining operation is performed. Further, in the present invention, the structure of the material to be joined obtained by the liquid phase diffusion bonding described above is classified as a low-temperature transformation generation structure, is martensite or bainite, and the joining metal and the material to be joined are contained in the joining metal. If a structure having the same low-temperature transformation generation structure in part or all of the same material as the material to be bonded is obtained by alloying generated by fusion with the metal, a stronger bonding surface will be obtained. For this purpose, the structure of the material to be joined is rapidly cooled at a cooling rate of 5 ° C./sec or more in order to prevent sintering cracking to a temperature higher than the bainite transformation start temperature, and then allowed to cool until the transformation is completed. By maintaining the cooling and then rapidly cooling to room temperature at a cooling rate of 1 ° C./sec or more, a desired bonding structure and bonding strength can be obtained.

The quenching condition from the joining temperature needs to be 5 ° C./sec or more in order to suppress the formation of ferrite. However, when rapidly cooled below the non-diffusion transformation point, a martensitic structure is formed, and quenching cracks occur near the joint. Therefore, rapid cooling is stopped above the transformation point and allowed to cool. If the temperature is further lowered below the transformation end temperature, precipitation of the embrittlement phase occurs. Therefore, it is necessary to cool down again at 1 ° C./sec or more after the transformation is completed.

Further, in the present invention, the characteristics of the joint surface can be freely changed depending on the specifications of the machine parts to be applied, and the characteristics as the joint are not particularly limited. The joint efficiency does not need to be 1, nor does it have to be completely homogenized organizationally. Of course, it is preferable that the joint efficiency is 1 and the body is completely homogenous in view of the characteristics of the mechanical part, but it can be determined according to the manufacturing cost of the part. In addition, after the assembly is completed, it is possible to perform various heat treatments, chemical conversion treatments, and processes on the mechanical components.For example, in the case of a steel material, quenching, tempering, normalizing, annealing, and the like are performed alone. Alternatively, a composite and repeated application in some cases is effective for improving the characteristics as a component, and does not hinder the effects of the present invention at all. In addition, carburizing treatment, nitriding treatment, plating, or painting, spraying of powder or the like, and surface processing such as shot blasting are also effective.

[0017]

<Embodiment 1> In the present invention, the manufacture of an automobile fuel injection valve having a fuel supply pipe inside will be described. This automotive fuel injector has a Cr:
B, having a thickness of 30 μm, is formed between divided surfaces 1 and 2 of a half part, which is divided into two parts by a forging made of a high carbon steel containing 1.0% and Mo: 0.5%. A liquid-phase diffusion bonding alloy made of a Ni-based amorphous alloy containing a small amount of P is sandwiched, the parts are butted together, and the parts are pressed from outside upper and lower surfaces by pressing jigs. In a high-frequency induction heating furnace (not shown) having an atmosphere controllable, first, the temperature of the component is heated to a temperature equal to or higher than the solidus of the bonding alloy foil inserted between the bonding surfaces within 60 seconds. The preheating of the parts and the melting of the joining alloy foil were attempted to increase the mutual wettability so that liquid phase diffusion joining was facilitated.

Next, the part is subjected to a liquid phase diffusion bonding temperature: 11
Temperature range from 00 ° C. to the point where diffusion reaches a peak from the start of heating: 90 ° C. to promote diffusion until reaching 1150 ° C.
For ~ 120 seconds, a load stress of 3 to 5 MPa was continuously applied to the joining surface by a holding jig to perform sufficient diffusion joining. After that, when the diffusion was completed, the applied stress was reduced and kept at low stress or no load for 5 minutes, and the structure of the joint was made uniform.

Further, in this embodiment, in order to make the structure of the material to be joined a structure such as martensitic transformation or bainite transformation, 10 ° C./sec. After rapidly cooling at a cooling rate of, followed by cooling and maintaining this cooling until the transformation was completed, the mixture was rapidly cooled to room temperature at a cooling rate of 10 ° C / sec. By performing such a treatment, a martensite or bainite structure, in which the structure of the material to be joined is classified as a low-temperature transformation generation structure, could be formed. In addition, a part of the joint metal, which is diffusion-bonded by fusion of the joint metal and the material to be joined, partially or entirely has the same low-temperature transformation generation structure as that of the material to be joined. The strength of the diffusion bonding surface thus obtained was equal to or higher than the strength of the material to be bonded. After that, it was finished to the final outer shape to produce a product of a fuel injection valve for an automobile. When this was incorporated and used as an actual automobile part, the same performance as that of a conventional machined automobile fuel injection valve was obtained, and the high-temperature oxidation resistance, abrasion resistance, and the joint surface strength against fluid pressure were not improved. A comparable value was obtained.

[0020]

As described above, the present invention makes it easy to manufacture precision mechanical parts such as automobile fuel injection valves having a complicated and precise pipe inside, which are originally manufactured by integral molding. By adopting a process of bonding the divided parts that can be manufactured by liquid phase diffusion bonding technology,
It is possible to manufacture inexpensively and efficiently metal precision machine parts.

[Brief description of the drawings]

FIG. 1 is a view showing a divided part shape in a case where a mechanical part manufactured by integral molding is divided by a surface passing through a pipeline provided therein, and particularly showing an example of a fluid injection valve.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasushi Hasegawa 5-3 Tokaicho, Tokai City, Aichi Prefecture Inside Nagoya Works, Nippon Steel Corporation (72) Inventor Yutaka Takagi 4005 Nishioguma, Ogumamachi, Hashima City, Gifu Prefecture Address Fukuju Kogyo Co., Ltd. F term (reference) 4E067 AD02 BA05 DA13 DA17 DB05 DC03 DC06 DC07 EB00

Claims (4)

[Claims] When joining a mechanical part having at least two or more divided surfaces by liquid phase diffusion bonding and assembling the same, the temperature of the part is set within 60 seconds within a bonding metal foil. Heat to a temperature above the phase line, 1000-
At a temperature of 1300 ° C., for more than 60 seconds, 2MPa
A method for assembling and joining liquid phase diffusion joining machine parts, wherein the above stress is applied, and thereafter, the applied stress is reduced and maintained in a low stress or no load state for 1 minute or more. 2. The method according to claim 1, wherein the stress load time is 90 hours from the start of heating.
2. The method for assembling and joining liquid phase diffusion bonding machine parts according to claim 1, wherein the time is from 120 to 120 seconds. 3. When joining a mechanical part having at least two or more divided surfaces by liquid phase diffusion bonding and assembling the same, the temperature of the part is set within 60 seconds within a bonding metal foil. Heat to a temperature above the phase line, 1000-
At a temperature of 1300 ° C., for more than 60 seconds, 2MPa
The above-mentioned stress is applied, and then the applied stress is reduced and maintained in a low stress or no-load state for 1 minute or more.
A method for assembling and joining liquid phase diffusion bonding machine parts, comprising: quenching at a cooling rate of at least ° C / sec, allowing to cool to the end of bainite transformation, and cooling to room temperature at a cooling rate of at least 1 ° C / sec. 4. A method for assembling and joining liquid phase diffusion bonding machine parts, wherein the liquid phase diffusion bonding according to claim 1 is performed in an oxidizing atmosphere.