JP2002219594A - Joining method in atmosphere - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a joining method capable of simply and effectively joining members even in the atmosphere. SOLUTION: In a method of brazing-joining between members 1 by interposing an insert metal 2 between the members to be joined, after covering the joining part of the members with a heat resisting sheet 3 coated with brazing flux 4 on the inner face, the brazing-joining is conducted by heating the joining part in the atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of joining pipes such as steel pipes by joining the ends of the pipes, in order to connect the pipes to each other, for example, pipes.

[0002]

2. Description of the Related Art Conventionally, a liquid phase diffusion bonding method and a pressure welding method have been known as a method of joining ends of members such as steel pipes with each other.

In the liquid phase diffusion bonding method, as shown in FIG. 2, an insert metal 2 of a metal foil having a melting point lower than that of a base material (a material to be bonded) is inserted between members 1 to be bonded. These members are pressurized and heated to a temperature equal to or higher than the melting point of the insert metal 2 to melt the insert metal 2 and diffuse the melting point lowering element (B, Si, etc.) in the insert metal 2.
This is a method of joining by isothermal solidification. In this method, since bonding is performed by diffusion, a large pressing force is not required at the time of bonding. In this joining method, it is necessary to shield the joint from the atmosphere using argon gas or nitrogen gas in order to prevent oxidation of the joint.

As a prior document, Japanese Patent Application Laid-Open No. 63-5889
JP, JP-A-62-97784 and JP-A-11-19784.
No. 309586.

[0005] The pressure welding method is a method of joining steel pipes by joining pipes to be joined, heating the joint to about 1300 ° C by gas or the like, applying a large pressing force to partially plastically process the pipes, and so on. . In the gas pressure welding, by using the reducing action of the reducing flame, it is possible to prevent the oxidization of the joint even if the joining is performed in the air. As prior documents, there are JP-A-55-57390 and JP-A-55-94787.

[0006]

The high-frequency heating does not produce the reducing flame employed for gas pressure welding. For this reason, when pressing a steel pipe or the like using the high-frequency heating method, it is necessary to shut off the atmosphere of the joint from the atmosphere using a shielding gas in order to prevent oxidation of the joint. That is,
The temperature at which the insert metal melts is about 1000 ° C. or higher. However, if the steel material is heated to this temperature in the atmosphere, an oxide scale is generated on the joint surface, so that the joint strength is reduced. Therefore, a shielding gas is used. Argon gas or nitrogen gas is suitable as the shielding gas.

In order to provide a shield gas atmosphere around the joint, a shield box (equipment) is provided around the joint,
It is necessary to replace the atmosphere in the box before heating. In this case, there is a problem that a special device called a shield box is required, and that the gas cylinder must be transported to the work site. Further, it takes a long time to replace the atmosphere in the shield box, and even if the pressure welding itself can be performed in a short time, there is a problem that the time required to manufacture one joint is long due to the replacement process.

Therefore, the present invention provides a joining method that can easily and efficiently join members even in the air.

[0009]

According to the present invention, in order to solve the above-mentioned problems, in a method of brazing an insert metal between members to be joined and brazing the members together, the brazing flux has an inner surface. After the joint of the members is covered with a heat-resistant sheet applied to the substrate, the joint is heated in the air to perform brazing.

[0010] According to the present invention, since the joining portion is completely blocked by the flux, the members can be simply and efficiently joined without using special equipment.

According to the present invention, in the method of joining and joining hollow materials or solid materials, a joint portion of the hollow material or the solid material is covered with a heat-resistant sheet having a brazing flux applied on an inner surface thereof. Thereafter, the joint is heated and pressurized so as to be brought into pressure contact with the atmosphere.

According to the present invention, members are reliably joined to each other by applying pressure.

Further, in the present invention, an insert metal having a melting point lower than that of a hollow material to be joined is sandwiched between the hollow materials, and a joint portion of the hollow material is heated by high-frequency induction heating means to melt the insert metal. In the joining method of joining the hollow material, after the heat-resistant sheet having the brazing flux applied to the inner surface thereof is wound around the outer peripheral surface of the joining portion without any gap, by heating with the high-frequency induction heating means, the air Press in with.

By using high-frequency induction heating means as the heating means, even if a heating coil is arranged on the outer peripheral side of the hollow material, the inner surface of the hollow material is heated first, and the heat-resistant sheet does not contact the high-temperature portion, Breakage of the heat-resistant sheet can be prevented. For this reason, the flux surely covers the outer peripheral surface of the joint.

Further, according to the present invention, an insert metal made of a low melting point metal of a component system of Fe-Si-B or Ni-Si-B is sandwiched between members to be joined, and the joint of the members is subjected to high-frequency induction heating. In a joining method of joining the members by heating the insert metal to melt the insert metal, after the heat-resistant sheet having a brazing flux applied to the inner surface thereof is wound around the outer peripheral surface of the joining portion, the high-frequency It is brought into pressure contact in the atmosphere by heating with induction heating main means.

According to the present invention, Fe--Si--B or Ni
Since the insert metal made of the low melting point metal of the component system of —Si—B has good wettability, it can be more effectively joined.

Further, according to the present invention, an insert metal made of a low melting point metal of the component system of Fe-Si-B or Ni-Si-B is sandwiched between hollow members, and the joint of the hollow members is sandwiched by high-frequency induction heating means. In the joining method of joining the hollow material by heating and melting the insert metal, a concave block made of an inorganic material coated with a brazing flux on an inner surface is closely attached to a periphery of a joint of the hollow material. After that, it is brought into pressure contact with the air by heating with the high frequency induction heating means.

According to the present invention, the concave block made of an inorganic material to which the brazing flux is applied on the inner surface reliably forms the flux film on the outer peripheral surface of the joining portion, without using special equipment. The members can be easily joined even in the air.

[0019]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a method according to an embodiment of the present invention, in which high-frequency induction heating and a heat-resistant sheet 3 are used together to join steel pipes 1 and 1 as members to be joined. The axial ends of the steel pipes 1 and 1 to be joined are abutted with each other in the atmosphere via an insert metal 2, and a brazing flux 4 is applied to the outer peripheral surface of the joint of the steel pipes 1 and 1. The applied heat-resistant sheet 3 is wound without any gap. A high-frequency heating coil 5 connected to a high-frequency induction heating device (not shown) is disposed outside the heat-resistant sheet 3, and the joint is heated by the heating coil 5.

The procedure of the joining method of the present invention will be described. First, the insert metal 2 is sandwiched between the steel pipes 1 and 1 to be joined, and the axial ends of the steel pipes 1 and 1 are butted together. At this time, pressure is applied in the axial direction between the two steel pipes 1 and 1. The insert metal 2 is made of Fe-S
It is composed of a low melting point metal based on i-B or Ni-Si-B.

After butting the steel pipes 1, 1, a heat-resistant sheet 3 in which a brazing flux 4 is uniformly applied to the inner surface from the joint surface to the outer peripheral surface of the joint having a predetermined width is wound without gaps. In this manner, the heat-resistant sheet 3 is wound without gaps, and the molten flux is prevented from dripping downward when heated later, so that a layer of the molten flux is uniformly formed on the entire joint. In addition, as a material of the heat-resistant sheet 3,
A ceramic fiber sheet, a glass fiber sheet or a polyethylene sheet is suitable, and its thickness is suitably from 0.3 mm to 2.0 mm. Also, as an alternative to the heat-resistant sheet 3, even if a mold or a concave block made of a heat-resistant inorganic material is used, good joining can be achieved.

On the other hand, as a component of the brazing flux 4, a material for silver brazing is suitable, and a paste-like material is suitable for application. The thickness applied to the heat-resistant sheet 3 is preferably from 0.3 mm to 2.0 mm.

After winding the heat-resistant sheet 3 around the joint, the high-frequency heating coil 5 is arranged outside the heat-resistant sheet 3 to heat the joint. The heating coil 5 is outside the heat-resistant sheet 3, but the heating is generated from the steel pipes 1, 1 inside. Also,
A brazing flux 4 exists between the heat-resistant sheet 3 and the heated steel pipes 1, 1. For this reason, steel pipes 1, 1
Even if the temperature is raised to 1000 ° C. or higher, the heat-resistant sheet 3 is not easily exposed to a high temperature, and the heat-resistant sheet 3 is hardly broken.
On the other hand, when heated by a gas flame, the outer heat-resistant sheet 3 is directly heated by the gas, so that there is a problem that the heat-resistant sheet 3 is easily damaged.

Note that the melting start temperature of the insert metal 2 is about 1000 ° C., whereas the flux is in a molten state at about 700 ° C.
In the temperature range of 000 ° C., the molten flux permeates the inner surfaces of the steel pipes 1 and 1 through the gaps at the joining interface. For this reason,
Even if the inner surfaces of the steel pipes 1 and 1 are not specially treated, if the heat-resistant sheet 3 coated with the brazing flux 4 is attached to the outer peripheral surface of the joint, the flux penetrates into the inner surfaces of the steel pipes 1 and 1 during heating. It is possible to satisfactorily join the steel pipes 1 and 1 to each other.

However, if the heat-resistant sheet coated with the flux is adhered also to the inner surface side of the steel pipes 1, 1, the oxidation of the joint on the inner surface side can be further reduced, so that a high bonding strength can be obtained.

When the steel pipes 1 and 1 are joined as described above, the inside of the steel pipes 1 and 1 is heated first by high-frequency induction heating, so that the heat-resistant sheet 3 is not damaged and the brazing flux 4 is removed. It can be welded to the entire periphery of the joint.
By covering the entire periphery of the bonding interface with the molten flux 4, the heated bonding portion is cut off from the atmosphere, and since the flux 4 has a reducing action, the bonding can be performed in the atmosphere.

Although a hollow steel pipe has been described as an example of the member to be joined, the same effect can be obtained by applying the joining method to a solid material. In addition, the method of using a high-frequency induction heating means as a heating means, and a method of arranging and joining a heating coil on the outer peripheral side of a steel pipe to be joined has been described.In addition to this method, a method of heating from an inner steel pipe,
For example, the connection can be made in the same manner by a direct energization method or a flash welding method.

[0029]

Example 1 A test was conducted using a steel pipe SGP50A. The outer diameter of the used SGP50A is 60.7 mm and the wall thickness is 3.8 mm. The chemical composition is shown as R1 in Table 1. The insert metal used is symbol M1 in Table 2.

[0030]

[Table 1]

[0031]

[Table 2]

As a material of the heat-resistant sheet, a material shown in Table 3 such as a ceramic fiber sheet was employed, and a flux for silver brazing was applied to one surface thereof. Thereafter, a heat-resistant sheet was wound around the outer surface of the steel pipe joint without any gap. Also,
For the reference materials W4 and W5, the flux was directly applied to the outer surface of the steel pipe without using a heat-resistant sheet.
Joining was performed.

The joints of all the test materials were heated by high-frequency induction heating. As heating conditions,
Bonding was performed at 1250 ° C. × retention time of 40 seconds and pressure of 5 MPa in the air.

After joining, a joint tensile test was performed. Table 3 shows the results.

[0035]

[Table 3]

In the materials W5 and W6, since there was no heat-resistant sheet, the entire joint was not covered with the flux layer. For this reason, oxide scale was partially generated at the bonding interface. Due to this scale, the joining strength is
It was considered that the value was lower than 290 MPa, which is the standard value of 0A. On the other hand, in the symbols W1 to W4, the entire joint portion was covered with the flux layer due to the presence of the heat-resistant sheet or the heat-resistant block, and the bonding strength was high.

[0037]

Example 2 A test was conducted using a steel pipe SGP100A. The used SGP100A has an outer diameter of 114.1 mm and a thickness of 4.6 mm. The chemical composition is represented by the symbol R2 in Table 1.
Shown in The insert metal used is symbol M2 in Table 2. As the material of the heat-resistant sheet, a material shown in Table 4 such as a ceramic fiber sheet was adopted, and a flux for silver brazing was applied to one surface thereof. Thereafter, a heat-resistant sheet was wound around the outer surface of the steel pipe joint without any gap. Further, for the reference materials W14 and W15, the flux was directly applied to the outer surface of the steel pipe without using the heat-resistant sheet, and then the joining was performed.

In each of the test materials, the joint was heated by high-frequency induction heating. The heating conditions were as follows: 1250 ° C. × retention time 60 seconds, pressure 6MPa,
The bonding was performed in the atmosphere.

After joining, a joint tensile test was performed. Table 4 shows the results.

[0040]

[Table 4]

In the materials W15 and W16, since there was no heat-resistant sheet, the entire joint was not covered with the flux layer. For this reason, oxide scale was partially generated at the bonding interface. It is considered that the joining strength was lower than 290 MPa, which is the standard value of the base material SGP100A, due to this scale. On the other hand, symbols W11 to W1
In No. 4, due to the presence of the heat-resistant sheet and the heat-resistant block, the entire joint was covered with the flux layer, and the joint strength was high.

[0042]

As described above, according to the present invention, even in the air, the joint is securely covered with the flux, so that oxidation of the joint can be prevented, and a high joining force can be obtained. Since no special equipment is required, the members can be simply and efficiently joined.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a state in which steel pipes are joined by a joining method according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing a conventional ordinary joining method.

[Explanation of symbols]

 Reference Signs List 1 steel pipe 2 insert metal 3 heat-resistant sheet 4 brazing flux 5 high-frequency heating coil

Continuing on the front page (72) Inventor Yasuhiro Ueno 88, Onocho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Inside Japan Steel Pipe Works Co., Ltd. (72) Inventor Kiyoshi Kanayama 88, Onocho, Tsurumi-ku, Yokohama-shi, Kanagawa Japan Japan Steel Pipe Works Co., Ltd (72) Inventor Haruo Someya 735 Rokumi Goka, Matsudo City, Chiba Prefecture (72) Inventor Toshiaki Shida 2-17-39 Higashikashigaya, Ebina City, Kanagawa Prefecture (72) Inventor Koji Oishibashi 33-33, Tatenocho, Nerima-ku, Tokyo 4 (72) Inventor Akio Kobayashi 440-6, Nagabocho, Hachioji-shi, Tokyo (72) Inventor Satoo Satori 4-36-7, Hakusan, Midori-ku, Yokohama, Kanagawa Prefecture 1-14-11 (72) Inventor Takashi Hojo 2-4-701 Sakuradai, Usui-cho, Inba-gun, Chiba Prefecture (72) Inventor Shigeki Miyaguchi 486-1, Ooka, Numazu City, Shizuoka Prefecture (72) Inventor Shigeaki Miyata Yao City, Osaka Prefecture Kyuhoen 3-chome 122 (72) Inventor Seiji Yamamoto 6-5-6 Ishikawa, Fujisawa City, Kanagawa Prefecture

Claims (5)

[Claims] 1. A method for brazing and joining insert members to each other by sandwiching an insert metal between members to be joined, wherein a joining portion of the members is covered with a heat-resistant sheet having a brazing flux applied to an inner surface thereof. After that, the joining method is characterized in that the joining portion is heated in the atmosphere to perform brazing. 2. The method of joining hollow and solid materials by butt-joining, wherein the joining portion of the hollow or solid materials is covered with a heat-resistant sheet having a brazing flux applied to an inner surface thereof. By heating and pressurizing the part,
A joining method characterized by pressure contact in the atmosphere. 3. An insert metal having a melting point lower than that of a hollow material to be joined is sandwiched between the hollow materials, and a joint of the hollow materials is heated by a high-frequency induction heating means to melt the insert metal. In the joining method of joining, after winding the heat-resistant sheet coated with the brazing flux on the inner surface without gaps around the outer peripheral surface of the joining portion,
A bonding method characterized in that the heating is performed by the high-frequency induction heating means so that the high-frequency induction heating means is brought into pressure contact with the atmosphere. 4. An insert metal made of Fe-Si-B or Ni-Si-B component-based low-melting metal is sandwiched between members to be joined, and the joined portion of the members is heated by high-frequency induction heating means. In the joining method of joining the members by melting the insert metal, a heat-resistant sheet having a brazing flux applied to the inner surface thereof is wound around the outer peripheral surface of the joining portion. A bonding method characterized by being brought into pressure contact with the atmosphere by heating. 5. An insert metal comprising a low melting point metal of a component system of Fe—Si—B or Ni—Si—B is sandwiched between hollow members, and a joint of the hollow members is heated by a high-frequency induction heating means. In the joining method for joining the hollow material by melting the insert metal, after the concave block made of an inorganic material coated with a brazing flux on the inner surface is brought into close contact with the periphery of the joining portion of the hollow material, the high-frequency A bonding method characterized in that the members are pressed in the atmosphere by heating with an induction heating means.