JP2838267B2 - Dissimilar material joining structure and method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a large impact load during operation, such as a rotary cutting blade in a mower, a tilling blade in a cultivator, a cutting blade in a harvester such as a combine or a binder, and a blade of a hedge trimmer. The present invention relates to a joining structure of dissimilar materials applied to a joining of a base material and a tip of various kinds of blades used under the conditions of receiving the same, and a method therefor.

[0002]

2. Description of the Related Art Taking the above-mentioned cutting tool as an example, conventionally, generally, a steel material such as stainless steel or aluminum is used as a base material, and silicon carbide (S) is used as a tip material.
iC), tungsten carbide (WC), steel (S
K), a super hard material such as a ceramic such as stainless steel or alumina was used, and both were joined by brazing.
However, with such conventional general products, not only does the weight of the entire blade increase, but also the joint strength between the base material and the chip material is low, and the brazing point is damaged by a crack when subjected to an impact load. There is a problem that the chip material may be peeled off inside, and furthermore, the mechanical strength of the base material itself is small and cracks or deformation damages are likely to occur.

[0003] In recent years, as a means for solving the above-mentioned difficulties, titanium or a titanium alloy which is excellent in mechanical strength and corrosion resistance and which is lightweight is used as a base material. A method of joining such a chip made of a hard material by brazing has been widely adopted.

[0004]

However, when a cemented carbide material is joined to a titanium material or a titanium alloy material by brazing, for example, Ticusil or Chikuni (T
It is necessary to use very expensive titanium brazing material consisting of a mixture of titanium, gold and cobalt and a special flux compatible with it, such as icuni). In order to prevent titanium oxide (TiO ₂ ) from being generated with heating at the time, brazing cannot be performed in the air and brazing must be performed in a reducing atmosphere or under vacuum. There was a problem that the cost increased.

The present inventor has conducted intensive studies to elucidate the causes of the above-mentioned problems, and as a result, it has become difficult to directly braze a super-hard material completely different from titanium materials or titanium alloy materials. Of the cause of the occurrence of, and based on this knowledge, coating the nickel or nickel alloy material on the required portion of the titanium material or titanium alloy material by plating, etc. We have come up with a joining method for dissimilar materials to be joined by brazing hard materials. According to such a joining method, it is possible to use a general-purpose brazing material such as a silver braze and a general-purpose flux, and also possible to perform a brazing operation in the air, thereby reducing costs and solving the above-described problems. be able to.

However, as a result of continuing various experimental studies on the blades joined by the above-described joining method of dissimilar materials, when a large impact load is applied in use, cracking does not occur at the brazing portion. It has been found that there is a new problem that a nickel material or a nickel alloy material obtained by coating a titanium material or a titanium alloy material by plating or the like is easily peeled off from the titanium material or the titanium alloy material.

In view of the above circumstances, the present invention has been made in view of the above-mentioned circumstances, and a titanium material or a titanium alloy material and nickel or a nickel alloy laminated thereon are provided. It is an object of the present invention to provide a joining structure of dissimilar materials that can be strongly bonded to a material without using a special interfacial agent or the like so as not to be separated at all even when a large impact load is applied, and a method thereof. .

The invention according to claims 3 and 4 is characterized in that a superhard material is used for a nickel material or a nickel alloy material without using the above-mentioned strong bonding strength, using a general-purpose brazing material and a general-purpose flux, and An object of the present invention is to provide a joining structure of dissimilar materials that can be joined with high strength by brazing in the atmosphere and a method thereof.

[0009]

In order to achieve the above-mentioned object, according to the first aspect of the present invention, there is provided a joint structure for dissimilar materials comprising a titanium material or a titanium alloy material and a nickel material or a nickel alloy material. The method for bonding dissimilar materials according to the invention according to claim 2 is characterized in that the bonding is performed via nitinol which is an intermetallic compound formed between the interfaces of the materials. Or, in a state where a titanium alloy material and a nickel material or a nickel alloy material are laminated,
By heating to a temperature range of 250 to 600 ° C. and maintaining the heating temperature uniformly over a predetermined time,
Nitinol, which is an intermetallic compound, is formed between the interfaces of the two materials, and the two materials are bonded via the nitinol.

According to the first aspect of the present invention, a titanium material or a titanium alloy material and a nickel material or a nickel alloy material are formed by an intermetallic compound formed between an interface between the two materials by heat treatment. Since the two materials are bonded via a certain nitinol, it is possible to bond the two materials to a strong bonding state that does not peel off even by the action of a large impact load without using a special interfacial agent or the like. Also,
According to the second aspect of the present invention, the titanium material or the titanium alloy material and the nickel material or the nickel alloy material are heated to a temperature range of 250 to 600 ° C. in a laminated state, and the heating temperature is set to a predetermined time. The eutectic reaction that occurs at the interface between the two materials, that is, a mechanical eutectic mixture of the crystals of both materials, reliably forms Nitinol, an intermetallic compound, by simply performing a simple heat treatment such as maintaining the uniformity over the entire material. Let me
Through the nitinol, the two materials can be joined to each other in a strong bonding state without using a special interfacial agent or the like so that no delamination occurs even when a large impact load is applied.

Further, in the joint structure of dissimilar materials according to the third aspect of the present invention, a titanium material or a titanium alloy material and a nickel material or a nickel alloy material having a thickness of 5 μm or more coated on the surface thereof can be used. It is characterized in that it is bonded via Nitinol, which is an intermetallic compound formed between the interfaces of the materials, and a member made of a super hard material is joined to the nickel material or Nickel alloy material via a brazing material. The method for joining dissimilar materials according to the invention according to claim 4, wherein the surface of the titanium material or the titanium alloy material is coated with a nickel material or a nickel alloy material having a thickness of 5 μm or more. Then, while heating to a temperature range of 250 to 600 ° C. and maintaining the heating temperature uniformly for a predetermined time, nitinol, which is an intermetallic compound, is formed between the interfaces of both materials. Then, the two materials are bonded via the nitinol, and thereafter, a member made of a super hard material is joined to the surface of the nickel material or the nickel alloy material via a brazing material.

According to the third aspect of the present invention, the titanium material or the titanium alloy material and the nickel material or the nickel alloy material coated on the surface thereof are formed between the interfaces of the two materials as described above. By joining via Nitinol, which is an intermetallic compound to be applied, it is possible to join in a strong joint state so that the two materials are not separated at all even if a large impact load is applied. By using a nickel alloy material having a thickness of 5 μm or more, the above-mentioned intermetallic compound is affected by the joining heating temperature when joining a cemented carbide member to the nickel material or the nickel alloy material using a brazing material. Nitinol is prevented from being destroyed, thereby maintaining a strong bonding strength between the titanium material or the titanium alloy material and the nickel material or the nickel alloy material. Using a general-purpose brazing material such as silver brazing and a general-purpose flux, it is possible to join a cemented carbide material to a titanium material or a titanium alloy material inexpensively and without crack damage. According to the fourth aspect of the present invention, in a state of being coated with a nickel material or a nickel alloy material, heating is performed in a temperature range of 250 to 600 ° C., and the heating temperature is uniformly maintained for a predetermined time. By simply applying a simple heat treatment, such as to make a strong joint between the titanium material or titanium alloy material and the coated nickel material or the nickel alloy material, as well as to use a general-purpose brazing material such as silver braze and a general-purpose flux while maintaining the bonding strength. It is possible to firmly join a member made of a super hard material to a titanium material or a titanium alloy material by using the same.

Here, the brazing material used for joining the cemented carbide material has a solidus temperature of about 605 ° C. to about 780 ° C.
The most preferred are silver brazes having 17 types of BAg-1 to BAg-24 included in the range, but other than these, copper, brass brass and phosphorous brass may be used. Further, the heating and uniform holding temperature of the nickel material or the nickel alloy material is in the range of 250 to 600 ° C.
Is most practically held at 550 ° C. for 30 minutes.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view of a main part of a joining structure of dissimilar materials according to the present invention applied to a rotary cutting blade of a mower. In FIG. The plate is fixed to the drive shaft 3 at the center thereof and is made of titanium or a titanium alloy. Tip mounting recesses 4 are formed at equal intervals in the circumferential direction on the outer peripheral portion of the titanium or titanium alloy rotating disk 2, and each of the recesses 4 is cut at a position just before the rotating direction. Recess 5 for scraping objects
Are formed.

Reference numeral 6 denotes a chip, which is made of a superhard material such as ceramics such as SiC, WC, SK, stainless steel, and alumina, and has a tip edge 6a protruding outward from the outer peripheral surface of the rotating disk 2. As described above, the base end portion is fitted into the recess 4 so that the titanium or titanium alloy rotating disc 2
Are joined by a joining method described later.

FIG. 2 is an enlarged sectional view of an essential part for explaining a joining structure of the cemented carbide tip 6 and the titanium or titanium alloy rotary disk 2, and in FIG. 2 is a nickel (nickel material) or nickel alloy layer (nickel alloy material) coated on the surface of the chip mounting recess 4 by plating to a thickness of 5 μm or more. This nickel or nickel alloy layer 7 is
By heating to a temperature range of 600 ° C. and maintaining the heating temperature uniformly over a predetermined time, specifically, heating to 300 ° C. and maintaining the temperature uniformly over 1 hour. Alternatively, by heating to 550 ° C. and maintaining the temperature uniformly for 30 minutes,
A eutectic reaction occurs at the interface between the rotating disk 2 and the nickel or nickel alloy layer 7 to form an intermetallic compound, Nitinol (TiNi) 8, between the interface and the rotating disk 2 and nickel through the Nitinol 8. Alternatively, it is bonded to the nickel alloy layer 7.

Thereafter, the cemented carbide chip 6
Is fitted in the concave portion 4 coated with the nickel or nickel alloy layer 7 and joined to the nickel or nickel alloy layer 7 of the rotating disk 2 via the silver solder 9.

The rotary cutting blade 1 of the mowing machine constructed as described above has excellent mechanical strength and corrosion resistance because the rotating disk 2 as its base material is made of titanium or a titanium alloy. In addition, since the required portion of the base material for brazing and joining the cemented carbide chip 6 is coated with a nickel or nickel alloy layer 7, the expensive titanium brazing and special It is possible to firmly join using inexpensive general-purpose brazing material such as silver brazing material 9 and general-purpose flux without using a simple flux, and brazing bonding in the air is possible, reducing the cost of joining work. Can also be achieved.

In addition, the nickel or nickel alloy layer 7 coated on the surface of the chip mounting concave portion 4 of the titanium or titanium alloy rotating disk 2 is interposed between the mother metal via the nitinol 8 which is an intermetallic compound formed between the interfaces. Even if a strong impact load is applied to the nickel or nickel alloy layer 7 via the tip 6 during a predetermined mowing operation, the nickel or nickel alloy layer 7 is not peeled off, Since the nickel or nickel alloy layer 7 is coated with a thickness of 5 μm or more, even if the temperature is raised to 650 ° C. or more during brazing, the above-mentioned intermetallic compound nitinol (TiN
i) This nitinol (T
iNi) 8 rotating disk made of titanium or titanium alloy
It is possible to secure a strong bonding state between the metal and the nickel or nickel alloy layer 7. Therefore, the tip 6 can be very strongly joined to the rotary disk 2 to significantly improve the durability of the entire rotary cutting blade.

Incidentally, when an impact load was applied to the chip 6 along the direction of the rotation axis of the rotary cutting blade of the mowing machine as an experimental object, the chip 6 was detached from the rotary disk 2 up to 35 kg / mm ^2. I never did. This value is sufficient for this type of rotary cutting blade where a load bearing capacity of up to 20 kg / mm ² is desired.

In the above embodiment, the case where the present invention is applied to the joining of the tip to the rotary disk of the rotary cutting blade in a mowing machine has been described. Plating or spraying nickel or nickel alloy material film on alloy material base material,
The present invention is also applicable to a technique of simply performing a coating process by means such as evaporation.

[0022]

As described above, according to the first aspect of the present invention, a titanium material or a titanium alloy material and a nickel material or a nickel alloy material can be combined with each other without using a special interfacial agent or the like. Even if a large impact load acts via Nitinol, which is an intermetallic compound formed by the eutectic reaction generated at the interface, it can be joined to a very strong bonding state without causing delamination, According to the second aspect of the present invention, it is only necessary to perform a simple heat treatment such that the two layers are heated in a temperature range of 250 to 600 ° C. and the heating temperature is uniformly maintained for a predetermined time. ,
There is an effect that the bonding structure in the very strong bonding state as described above can be reliably obtained.

According to the third aspect of the present invention, the titanium material or the titanium alloy material and the nickel material or the nickel alloy material coated on the surface thereof are formed between the interfaces between the two materials as described above. In addition to being able to join in a strong bonding state via Nitinol, which is an intermetallic compound, by using a nickel material or nickel alloy material having a thickness of 5 μm or more, the nickel material or nickel alloy material can be used. Nitinol can be prevented from being destroyed by the influence of the joining heating temperature when joining a member made of a super hard material using a brazing material, and therefore, the titanium material or the titanium alloy material and the nickel material or the nickel alloy material While maintaining strong bond strength, the cemented carbide material is made of a general-purpose brazing material such as silver braze and a general-purpose flux, at a low cost, One such crack-free damage can be very firmly bonded to the titanium material or titanium alloy,
Further, according to the invention of claim 4, in a state where the surface of the titanium material or the titanium alloy material is coated with the nickel material or the nickel alloy material, the material is heated to a temperature range of 250 to 600 ° C., and the heating temperature is reduced. By simply performing a simple heat treatment such as maintaining the material uniformly over a predetermined period of time, it is possible to reliably form Nitinol, which exhibits a strong bonding state between the two materials, and to have a strong bonding strength. The effect that the member made of a super hard material can be very easily and firmly joined to the surface of a nickel material or a nickel alloy material using a general-purpose brazing material such as silver brazing and a general-purpose flux without lowering .

[Brief description of the drawings]

FIG. 1 is a plan view of a main part showing a state in which a joining structure of dissimilar materials and a method according to the present invention are applied to a rotary cutting blade in a mower.

FIG. 2 is an enlarged sectional view of a main part.

[Explanation of symbols]

 2 Rotating disk made of titanium or titanium alloy 6 Tip made of cemented carbide material 7 Nickel or nickel alloy layer 8 Nitinol 9 Silver solder

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B23K 1/19 C22C 14/00

Claims (4)

(57) [Claims] 1. A heterogeneous material comprising a titanium material or a titanium alloy material and a nickel material or a nickel alloy material bonded together via an intermetallic compound, nitinol, formed between the two materials. Joint structure. 2. A laminate comprising a titanium material or a titanium alloy material and a nickel material or a nickel alloy material,
By heating to a temperature range of 600 ° C. and maintaining the heating temperature uniformly for a predetermined time, nitinol, which is an intermetallic compound, is formed between the interfaces of the two materials, and the two materials are interposed via the nitinol. A method for joining dissimilar materials, characterized in that: 3. A titanium material or a titanium alloy material and a nickel material or a nickel alloy material having a thickness of 5 μm or more coated on the surface of the titanium material or the titanium alloy material via a nitinol which is an intermetallic compound formed between an interface between the two materials. Together with
A joining structure of dissimilar materials, wherein a cemented carbide material is joined to the nickel material or nickel alloy material via a brazing material. 4. The surface of a titanium material or a titanium alloy material,
In a state where a nickel material or a nickel alloy material having a thickness of 5 μm or more is coated, the material is heated to a temperature range of 250 to 600 ° C., and the heating temperature is uniformly maintained for a predetermined time, so that an interface between the two materials is obtained. An intermetallic compound, nitinol, is formed between the two materials, and the two materials are bonded via the nitinol. Thereafter, a cemented carbide member is joined to the surface of the nickel material or nickel alloy material via a brazing material. A method for joining dissimilar materials, characterized in that: