JP3694365B2 - Induction heating diffusion bonding method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, when metal pipes such as steel pipes or metal bars such as steel bars are butt-joined in the length direction, a part limited in the length direction, such as heating at the time of joining or heat treatment after joining, is induced. with heated diffusion bonding, after completion of heating are those concerning the rapid cooling possible way.
[0002]
[Prior art]
As means for butt-joining metal pipes such as steel pipes or metal bars such as steel bars in the length direction, welding such as MIG welding and TIG welding, pressure welding, diffusion bonding, and the like are known. In diffusion bonding, there is also a method in which an amorphous metal foil is interposed between both end faces, and the elements contained in the foil are diffused into both materials.
[0003]
In these joints, in the case of welding, heating for heat treatment after welding is necessary depending on the material. In the case of pressure welding or diffusion bonding, heating for bonding is required. As the heating means, induction heating is widely adopted, and an appropriate frequency is selected according to the required heating depth of the material to be heated.
[0004]
By the way, there is a problem that when the base material other than the joint is heated at the time of heating at the time of joining or heat treatment after joining, there is a problem that material deterioration such as strength reduction occurs. It is desirable to limit to a minimum narrow range. For this reason, it is possible to forcibly cool the part removed from the heating part by water jet or the like.
[0005]
As a method and apparatus for heat-treating a joint after pressure welding or welding a steel material, Japanese Patent Application Laid-Open No. 53-119243 discloses an induction heating device, a water jet cooling device, and a joint detector on a carriage that can be conveyed along the steel material. It is disclosed that heating and cooling are performed with accurate positioning without shifting from the position of the joint. However, the technique disclosed in this publication does not forcibly cool the periphery of the joint when it is heated, but cools the joint after the heating, and the heating part cannot be limited to a narrow range.
[0006]
[Problems to be solved by the invention]
In induction heating of a metal tube or metal rod, the part surrounded by the work coil is heated. To shorten this heating part, the work coil is wound tightly, or the number of turns is reduced to reduce the heating zone. It is necessary to make it narrow.
However, increasing the winding density of the work coil is limited in terms of maintaining insulation between the windings. In addition, when the number of turns is reduced, in order to flow an induced current necessary for heating the heating part to a predetermined temperature, it is necessary to flow a large current through the coil, and the power source must have a large capacity and a large size.
[0007]
In the present invention, when metal pipes such as steel pipes or metal bars such as steel bars are butt-joined in the length direction, a part limited in the length direction, such as heating at the time of joining or heat treatment after joining, is induced. a method for heating, and aims no problem in insulation maintenance work coil, and the capacity of the power supply, without the need also large, also after the completion of heating is to provide a possible rapid cooling method To do.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the method of the present invention is a method of induction heating diffusion bonding of a limited portion in the length direction of a metal tube or metal rod, wherein the heating portion is surrounded by a work coil, and the work coil A cooling medium spraying device is disposed between the work coil and a part of the enclosed part that is out of the heating part, and the metal tubes or metal bars are butted in the length direction, and an amorphous metal is interposed therebetween. Fitting between foils, pressurizing in the longitudinal direction, induction heating a limited part including the joint, diffusion bonding, and cooling the part removed from the heating part with the cooling medium injection device This is a characteristic induction heating diffusion bonding method.
[0009]
An apparatus for carrying out the above- described method of the present invention is an apparatus for inductively heating a limited portion in the length direction of a metal tube or a metal rod, having a work coil surrounding the heating portion, and the workpiece A cooling medium spraying device is disposed between the work coil and a part out of the heating part among the parts surrounded by the coil, and surrounds the material to be heated at the boundary between the heating part and the cooling medium spraying part. A partition plate is provided .
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The method of the present invention will be described by taking diffusion bonding of metal pipes as an example. FIG. 1 shows a cross section in a state where a metal tube 1 and a metal tube 2 are butt-joined. The end face of the metal tube 1 is processed into a convex taper, the end surface of the metal tube 2 is processed into a concave taper, both are fitted with an amorphous metal foil (not shown), and the joint 3 is included under pressure. The heating part 4 in the range is heated.
[0011]
The heating medium 4 is surrounded by the work coil 5, and the cooling medium injection device 6 is disposed between the work coil 5 and a part of the part surrounded by the work coil 5 that is out of the heating part 4. The cooling medium such as water is sprayed from a plurality of injection holes 7 provided in the circumferential direction of 2. The shape of the injection hole 7 can be a circle, an ellipse, a polygon, or the like. Moreover, you may use a spray as needed. A partition plate 8 is provided in a ring shape at the boundary between the heating part 4 and the cooling part so that the cooling medium is not applied to the heating part.
[0012]
Therefore, in this example, the heating part 4 in a range limited in the length direction including the joint portion 3 is selectively heated, and heating is suppressed in a part that is out of the heating part 4. By setting the heating part 4 as a range necessary for diffusion of the joint 3 and both sides thereof, only the minimum necessary range is heated to a required high temperature, and the high temperature of the base material at the part outside the heating part 4 is suppressed. Therefore, material deterioration such as a decrease in strength of the base material can be suppressed.
[0013]
Further, after the induction heating is completed, the cooling by the cooling medium ejecting device 6 can be continued to perform the rapid cooling after the heating. The rapid cooling after heating suppresses the material deterioration of the joint portion 3 and the base material, shortens the time until the heating portion 4 reaches room temperature, and leads to an improvement in the efficiency of the joining work.
[0014]
In the method of the present invention, the cooling medium ejection device 6 may be disposed on one side in addition to being disposed on both sides of the heating portion 4 as in the example of FIG. For example, when the metal tube 2 is short and joined to another member such as a flange, the work coil 5 is entirely offset toward the metal tube 1 side, and the coolant injection device 6 is disposed on the metal tube 2 side. It becomes impossible to set. In such a case, the flange etc. can suppress overheating of the metal pipe 2 removed from the heating part 4 by heat conduction or by cooling the flange etc. In the case where metal materials having different materials are joined together, when only one metal material may be deteriorated due to thermal influence, the coolant injection device 6 may be disposed only on the material side.
[0015]
In the diffusion bonding through the amorphous metal foil as in this example, the temperature of the heating part 4 is about 1200 ° C. in the case of a steel material, and the range only needs to be 1 mm or more on both sides from the bonding part 3, When a 45 ° taper is formed on the joint end faces of the metal pipes 1 and 2 as in the example of FIG. 1, the thickness may be set to 3 mm or more.
Since the heating part 4 becomes such high temperature, in order to protect the work coil 5, it is preferable to wind the heat insulating material 9 around the heating part 4. In addition, the arrangement | positioning position of the cooling-medium injection apparatus 6 can also be arrange | positioned in the position away from the heating site | part 4 according to heating conditions and the material of a to-be-heated material not only in this example.
[0016]
The method of the present invention can be applied to diffusion bonding between metal bars in addition to the above-described example of the metal tube. Further, the present invention can be applied not only to diffusion bonding but also to the case where the metal tube 1 and the metal tube 2 or the metal rods are pressed against each other, heat treatment after welding, or the like.
According to the method of the present invention, the winding density of the work coil is in a range where there is no problem in maintaining insulation, and it is not necessary to reduce the number of turns. The heated part can be heated to the required temperature for bonding. And in the site | part which remove | deviated from the heating site | part, material deterioration, such as a strength fall of a base material, can be suppressed.
[0017]
Diffusion bonding with an amorphous metal foil as shown in FIG. 1 can be performed cheaply and easily compared with other bonding means such as MIG welding, TIG welding, or pressure welding. Suitable for joining steel pipes and bars in various construction work sites. By adopting the method of the present invention, the heating that suppresses the material deterioration of the base material on both sides of the joint can be performed by induction heating using a small power source.
[0018]
Next, as shown in FIG. 1, the apparatus for carrying out the present invention has a work coil 5 surrounding the heating part 4, and a part out of the heating part 4 among the parts surrounded by the work coil 5. A cooling medium ejection device 6 is disposed between the work coil 5 and the work coil 5, and a partition plate 8 surrounding the material to be heated is provided at the boundary between the heating area 4 and the cooling medium ejection area. The work coil 5 is insulated by winding the winding wire 10 with glass wool, and further coated with a refractory material such as refractory mortar and refractory cement. Moreover, in order to raise heating efficiency, the heat insulating material is coat | covered. The partition plate 8 is made of a heat-resistant material and is preferably an elastic body such as heat-resistant rubber. Such an effect | action of this invention is as having explained in full detail in the said invention method.
[0019]
In the present invention, the material to be heated 1 is not limited to the circular shape as described above, but can be applied to various shapes such as a square. In that case, the shape of the winding 10 is assumed to match the shape of the material to be heated 1.
[0020]
【Example】
Example of the present invention: An apparatus as shown in FIG. 1 was used, and steel pipes were diffusion bonded by the method of the present invention. The steel pipe has STK400 defined in JIS G 3444, an outer diameter of 264.4 mm, an inner diameter of 228.8 mm, and a wall thickness of 17.8 mm. A convex taper and a concave taper having an inclination angle of 45 ° as shown in FIG. 1 were processed at the pipe ends of both steel pipes, fitted with sandwiching an amorphous metal foil, and heated with a load of about 900 kg. The amorphous metal foil has a composition of Fe-9 wt% Si-1.5 wt% B and has a thickness of 30 μm.
[0021]
The work coil 5 has an inner diameter of 350 mmφ, a length of 200 mm, and a number of turns of 10. The cooling medium injection device 6 has an inner diameter of 290 mmφ, an outer diameter of 320 mmφ, and a length of 400 mm, and the distance between both cooling medium injection devices 6 is 40 mm. The range of 40 mm was used as the heating part 4 and the joint 3 was positioned at the center of the heating part 4 as shown in FIG. Then, a ring-shaped partition plate 8 made of refractory rubber was attached as shown in FIG. 1, and a cylindrical ceramic fiber having an initial thickness of 15 mm was attached to the steel pipe as a heat insulating material 9 covering the heating portion 4.
[0022]
The power source connected to the work coil 5 is a small high-frequency power source with a maximum output of 50 kW and a frequency of 8 kHz. With this power source, the secondary power was induction-heated at 40 kW (700 V, 60 A, efficiency 95%), heated to 1200 ° C. at a rate of temperature increase of about 2 ° C./second, held for 5 minutes, then turned off and cooled. . Water was continuously injected at a water density of 100 liters / m ² · min from the injection holes 7 arranged in a staggered manner in the cooling medium injection device 6 during and after the heating.
[0023]
Comparative Example: In FIG. 1, the cooling medium injection device 6 was not used, and other conditions were the same as in Example 1 of the present invention, and the steel pipe was joined.
[0024]
About the said example of this invention and the comparative example, the tension test piece was extract | collected from the sample divided into 8 in the circumferential direction after joining, making the junction part 3 into the center part, respectively. As a result, the tensile strengths were all 400 MPa or more, and the joint strengths were all good and no difference was observed, but a difference was observed in 0.2% proof stress,
Example of the present invention: 310 to 330 MPa
Comparative example ... 230-260MPa
Met. Since the 0.2% proof stress of the base material not affected by heat is about 350 MPa, in the comparative example, the strength decrease of the base material due to the heat effect was large, whereas in the present invention example, the strength decrease can be suppressed. It was.
[0025]
【The invention's effect】
In the present invention, when metal pipes such as steel pipes or metal bars such as steel bars are butt-joined in the length direction, a part limited in the length direction, such as heating at the time of joining or heat treatment after joining, is induced. It is a method for heat diffusion bonding, and it is possible to selectively heat a narrow range of heating parts without narrowing the winding range of the work coil. Therefore, it is not necessary to reduce the capacity of the power supply. And the heating part of the limited narrow range can be heated to required temperature, and material deteriorations, such as a strength fall of a base material, can be suppressed in the part which removed the heating part.
[0026]
Moreover, rapid cooling after induction heating can be performed. The rapid cooling after heating suppresses the material deterioration of the joint and the base material, shortens the time until the heated portion reaches room temperature, and leads to an improvement in the efficiency of the joining work.
Therefore, it is suitable for on-site construction of oil well pipes or for joining and heat treatment of steel pipes and bars in various construction works.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of an apparatus for carrying out the method of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 2 ... Metal pipe 3 ... Joint part 4 ... Heating part 5 ... Work coil 6 ... Cooling medium injection device 7 ... Injection hole 8 ... Partition plate 9 ... Heat insulating material 10 ... Winding

Claims (1)

A method for induction heating diffusion bonding of a length-limited portion of a metal tube or a metal rod, wherein the heating portion is surrounded by a work coil, and the heating portion within the portion surrounded by the work coil is separated from the heating portion. A cooling medium spraying device is disposed between the work coil and the work coil , the metal tubes or the metal rods are butted in the length direction, an amorphous metal foil is sandwiched between them, and the work piece is added in the longitudinal direction. A method of induction heating diffusion bonding , characterized in that: a limited portion including a bonding portion is heated by induction heating and diffusion bonding is performed, and a portion removed from the heating portion is cooled by the cooling medium spraying device .

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