JPH11156558A - Welding tube manufacturing impeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a welding tube manufacturing impeder which enables not only to improve productivity by obtaining a higher welding heat efficiency than the conventional one but also to be bearable for a long use. SOLUTION: This is referred to a welding tube manufacturing impeder wherein a powder magnetic core 8 is used as a core formed by an insulation treatment of magnetic metal powder 9 as the magnetic material, with resin 11. The powder magnetic core 8 is preferable to be the one formed by an inorganic system insulation coat 10 treated magnetic metal powder being insulation treated with resin. Furthermore, the magnetic metal powder 9 is preferable to be an iron powder and the inorganic system insulation coat 10 is to be a ferrite.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impeder for manufacturing a welded pipe, and more particularly, to forming a strip-shaped skeleton in a continuous shape such that a skeleton edge serving as a welded portion forms a straight or spiral shape, and forms the tube after forming. Heat the skeleton edge by high frequency induction welding or high frequency resistance welding.
The present invention relates to a welded pipe manufacturing impeder used for charging into a pipe in order to improve welding heat efficiency at the time of welding.

[0002]

2. Description of the Related Art In a welding pipe forming process, for example, a high-frequency induction welding pipe forming process, as shown in FIG. And welded at the V convergence point (weld point) formed by the opposing skeleton edges.

[0003] The impeller used by being inserted into a pipe for the purpose of improving the welding heat efficiency is composed of a case 4 of an insulating material and a core 5 of a magnetic material, and is connected to a mandrel 6. The core 5 is cooled by cooling water supplied from a mandrel 6 to maintain its performance during welding. The purpose of using the impeder is work coil 2
Is to excite the core 5 with a high-frequency current flowing through it to suppress the sneak of the induced current toward the inner surface of the tube, thereby concentrating the welding current at the welding point via the skelp edge to improve the welding heat efficiency.

Therefore, the core of the impeder is
First, it has high magnetic permeability and high saturation magnetic flux density. Second, in order to prevent heat generation during use, it can be processed into a shape having large specific resistance, small iron loss and easy to cool. It is required to have a performance in which the change in magnetic properties is small even if it rises and the Curie temperature is high. Conventionally, a ferrite core 5A which is an oxide magnetic material obtained by sintering a ferrite powder 50 as shown in FIG. In addition, 51 is a binder.

However, in the case of high-frequency welding, since the welding current is high, the cross-sectional area of the ferrite core also becomes smaller, especially when the pipe-forming dimension becomes smaller, and the magnetic flux density tends to reach saturation with a strong magnetic field, and the welding heat efficiency is reduced. Further, the ferrite core has a disadvantage that the saturation magnetic flux density is greatly reduced when heat is generated due to iron loss during use. In addition, there is also a drawback that it is hard and brittle, so that it is easily cracked during use.

[0006] Because of these drawbacks, the impeder using the ferrite core has a problem that the welding heat efficiency in pipe welding cannot be increased to a sufficient level and has a short life. To compensate for these drawbacks, a metal magnetic material such as silicon steel having a high saturation magnetic flux density is processed into a thin and narrow plate 71 as shown in FIG. As shown in FIG. 3B, a plurality of such metallic magnetic material laminates 7, each of which is housed in an insulating material case 4 as a core, are known.

[0007] Since the welding current is a high frequency high current, the metal magnetic material laminated core exposed to high frequency and high magnetic flux density has a problem of heat generation due to eddy current. In order to suppress the heat generation due to the eddy current, it is necessary to reduce the thickness and width of the metal magnetic material and to reduce the cross-sectional area per one laminate. However, when the thickness and width of the metal magnetic material laminate are reduced, the material tends to break or tear in the process from plate production to laminate production, making it difficult to handle. The size of the plate that can be manufactured is 25 μm or more in thickness and 2.0 mm or more in width. Due to this restriction, there is a limit in suppressing heat generation.

Further, since the ferromagnetic property of the metallic magnetic material disappears above the Curie point and loses its function as an impeder, in order to maintain the temperature below the Curie point by cooling with cooling water, the welding temperature is inevitably increased. However, there is a problem that the welding speed cannot be increased and productivity is reduced. In addition, the core of a metal magnetic material laminated body such as silicon steel is oxidized by using it in cooling water at a high temperature of several hundred degrees even though it is below the Curie point, and the performance of the insulating adhesive between layers deteriorates at high temperatures. Has a problem in that the characteristics of the device are deteriorated and the life as an impedance is short.

[0009]

SUMMARY OF THE INVENTION In view of the above problems of the prior art, the present invention provides an impeller for manufacturing a welded pipe capable of obtaining a higher welding heat efficiency, improving productivity, and enduring long-term use. The purpose is to provide.

[0010]

The present invention, which has been made to achieve the above object, is characterized in that, as a magnetic material, a dust core formed by insulating a magnetic metal powder with a resin is used as a core. Impeder for manufacturing welded pipes. In the present invention, it is preferable that the dust core is formed by subjecting a magnetic metal powder having been subjected to an inorganic insulating coating treatment to insulation treatment with a resin.

Further, in the present invention, the magnetic metal powder is preferably iron powder, and the inorganic insulating coating is preferably ferrite.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of intensive studies, the present inventors have insulated a magnetic metal powder 9 as shown in FIG. The use of the dust core 8 formed in this way makes it possible to improve welding heat efficiency, improve productivity, and have a long service life as compared with conventional ones using a ferrite core or a metal magnetic material laminated core. I found that I could get an impeder.

The dust core, which is the core of the welder for producing a welded pipe of the present invention, has a low magnetic permeability in a low-intensity magnetic field as compared with silicon steel or the like. , The amount of magnetic flux of the impedance can be increased, and the welding efficiency can be improved. Further, since the material is a powder, the electric resistivity is higher than that of the plate-shaped metal magnetic material laminate, and the heat generation due to the eddy current is remarkably small. Accordingly, the limitation of the welding current for keeping the core at a temperature equal to or lower than the Curie point of the material is relaxed, so that the welding speed can be increased and the productivity is improved. In addition, there is no problem of deterioration of the resin, which is an insulating material, as seen in the core of the metal magnetic material laminate, and shortening of the life due to burning. Further, the ferrite core is a sintered compact and has poor toughness, whereas the dust core according to the present invention, which is insulated with resin, has excellent toughness, so that there is no fear of breakage due to handling.

The material of the dust core is obtained by insulating a magnetic metal powder 9 such as iron powder (average particle size of about 1 μm) 9 with an inorganic coating 10 such as a phosphate compound (see FIG. 1B). ) Is preferable, and a ferrite coating is more preferable as the inorganic coating. Insulation treatment of magnetic metal powder such as iron powder with an inorganic coating such as a phosphate compound has a higher insulation resistance between particles than that of a single powder, so heat generated by eddy current can be reduced. it can. In addition, when the inorganic coating is a ferrite coating, the insulation resistance between particles is higher and the magnetic permeability is higher than that of a single powder, so that heat generated by eddy current can be reduced, and welding efficiency can be improved. It is possible.

As the metal of the magnetic metal powder, in addition to iron, nickel or cobalt alone or a ferromagnetic alloy containing two or more of iron, nickel and cobalt can be used. In addition to salt compounds and ferrite, chromate compounds, borate compounds and the like can be applied. As the method of insulating coating of the magnetic metal powder with an inorganic material, any method such as adhesion of inorganic insulating particles by mechanical operation, and synthetic adhesion of an inorganic insulating film by a thermal decomposition reaction of a metal organic substance can be applied.

The resin used for the insulation treatment is preferably an epoxy resin, a polyester resin, an acrylic resin, a urethane resin, a phenol resin, a chloroprene resin, a polyimide resin, or the like.

[0017]

EXAMPLE A skeleton made of 0.12% C steel and having a thickness of 3.5 mm was subjected to a high frequency induction welding method shown in FIG.
)), When forming a welded pipe with an outer diameter of 34.0 mm, as shown in FIG.
(B) A ferrite impedance containing a ferrite core (Comparative Example 1), and a silicon steel impedance containing a laminated core of oriented silicon steel sheet (3.0% Si) as a metallic magnetic material in FIG. Comparative Example 2), insulating case 4
Insulation treatment of iron powder inside with epoxy resin (Fig. 1 (a))
Powder magnetic core impeder containing a powder magnetic core molded and formed (Example 1), and iron powder whose surface is coated with a phosphate compound in the insulating case 4 is insulated with a polyimide resin (FIG. 1). (B)) A dust core impeder (Example 2) in which a dust core molded and stored is stored, and an iron powder whose surface is subjected to ferrite coating treatment in the insulating case 4 is insulated with a polyimide resin (FIG. 1). (B)) Five types of powder magnetic core impeders (Example 3) each containing a powder magnetic core molded and formed, and required when pipes are formed while flowing cooling water at 12.0 l / min through the insulating case 4. The power was compared and the life of the impedance was investigated. The filling rate defined by the ratio of the core cross-sectional area to the space cross-sectional area in the insulating case was set to 50% for all the impedances.

Table 1 shows the results. As is clear from Table 1, in the present invention (Examples 1 to 3), when compared at the same pipe-forming speed, the welding heat efficiency is much higher than that of Comparative Examples 1 and 2, and the life of the impeder is remarkably higher. Extended. Further, in the present invention, as shown in Example 3, even when the pipe forming speed was increased, the life of the impeder was longer than those of Comparative Examples 1 and 2, and as a result, the productivity was improved by 25%.

[0019]

[Table 1]

[0020]

As described above, according to the present invention, it is possible to produce a welded pipe with a higher welding heat efficiency than in the prior art, to improve the productivity, and to achieve an excellent effect of extending the life of the impeder.

[Brief description of the drawings]

FIG. 1 is a schematic view showing the structure of a dust core according to the present invention.

2A is a schematic view showing a high-frequency induction welding pipe forming process using an impeder, and FIG. 2B is an AA sectional view of FIG. 2A showing a ferrite core.

FIG. 3A is a schematic diagram showing a metal magnetic material laminate.
(B) of FIG. 1 (a) showing a metal magnetic material laminate core;
It is A sectional drawing.

[Explanation of symbols]

 Reference Signs List 1 skelp 2 work coil 3 welding roll 4 case (insulating case) 5 core 5A ferrite core 6 mandrel 7 metal magnetic material laminated body 8 dust core 9 magnetic metal powder 10 inorganic coating 11 resin 50 ferrite powder 51 binder 71 plate 72 insulation adhesive

Continued on the front page (72) Inventor Motoaki Itaya 1-1-1, Kawasaki-cho, Handa-shi, Aichi Prefecture Kawasaki Steel Corporation Chita Works (72) Inventor Nochika Okabe 1-1-1, Kawasaki-cho, Handa-shi, Aichi Prefecture Kawasaki-made (72) Inventor Masayoshi Ishida 1-chome, Mizushima-Kawasaki-dori, Kurashiki-shi, Okayama Pref. (Without address) Kawasaki Steel Corporation Mizushima Works, Inc. Address Kawasaki Steel Corporation Chita Works (72) Inventor Toshio Onishi 1-1-1, Kawasakicho, Handa-shi, Aichi Prefecture Kawasaki Steel Corporation Chita Works

Claims (4)

[Claims] 1. An impeder for manufacturing a welded pipe, wherein a dust core formed by subjecting a magnetic metal powder to insulation treatment with a resin is used as a magnetic material as a core. 2. The impeller for manufacturing a welded pipe according to claim 1, wherein the dust core is formed by subjecting a magnetic metal powder having been subjected to an inorganic insulating coating treatment to insulation treatment with a resin. 3. The impeder for producing a welded pipe according to claim 1, wherein the magnetic metal powder is iron powder. 4. The impeder for manufacturing a welded pipe according to claim 2, wherein the inorganic insulating coating is ferrite.