JP2846138B2 - Method and apparatus for manufacturing powder-filled tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for manufacturing a powder-filled tube in which a metal tube made of carbon steel, stainless steel, copper alloy, aluminum alloy or the like is filled with powder. Here, the granular material refers to a powder such as a welding flux or an oxide superconductor, a granular material, or a mixture of the powder and the granular material. INDUSTRIAL APPLICABILITY The present invention is used for manufacturing a flux-cored wire for welding, a wire containing an oxide superconductor, and other powder-filled tubes.

[0002]

2. Description of the Related Art As one of powder-filled tubes, there is a flux-cored wire for welding. In the production of this wire, a cold-rolled steel strip is slit to a required width, and the steel strip after slitting is gradually formed from a U-shape to an O-shape by a forming roll.
During this forming, a metal powder such as iron powder and a flux having desired components such as a deoxidizing agent and an arc stabilizer are supplied to the steel strip valley through a feeder through an opening along the longitudinal direction of the U-shaped steel strip. Next, at the same time as the O-shape is formed, the opposite edge surfaces of the opening are joined by welding, and subsequently the diameter is reduced. Further, after annealing as required, the tube filled with the flux is drawn to a desired diameter and wound up to obtain a product.

A high frequency induction welding method has been widely used as a welding method in the production of the above-mentioned powder-filled tube. In this welding method, when formed into a substantially O-shape, the edge surface of the opening is heated to a melting temperature by induction heating using a high-frequency current flowing through an induction heating coil (work coil), and the opposed edge surfaces are pressed by a pair of squeeze rolls. I do.

[0004]

By the way, in the production of the above-mentioned powder-filled pipe, the pipe passing through the work coil includes:-magnetic powder such as iron powder in dust generated when flux is supplied;-steel strip forming. Magnetic powder, such as magnetic powder such as abrasion powder and shaving powder generated during the process, is attached. When the tube to which the magnetic powder has adhered passes through the work coil, a magnetic field generated by a high-frequency current flowing through the work coil causes the magnetic powder to separate from the tube and be adsorbed to the work coil. When the magnetic powder adsorbed on the work coil accumulates to a certain degree or more, discharge occurs between the tube and the work coil. This discharge breaks the water-cooled copper pipe of the work coil, and the cooling water scatters around. In such a case, the operation of the apparatus has to be temporarily stopped to replace the work coil, take out the unwelded pipe, etc., and restart the operation of the apparatus, and the operation rate and the yield have been significantly impaired.

Accordingly, the present invention makes it difficult for magnetic powder to be adsorbed to the work coil, thereby avoiding a discharge phenomenon due to the accumulation of the magnetic powder, thereby preventing damage to the work coil and thereby greatly extending the life of the work coil. It is an object of the present invention to provide a method and apparatus for manufacturing a powder-filled tube that can be used.

[0006]

SUMMARY OF THE INVENTION A method of manufacturing a powder-filled tube according to the present invention is characterized in that a metal strip is fed in a longitudinal direction of the pipe and a gap is left along the pipe at least up to a welding point. The metal strip is formed into a tube while supplying the powdery material to the tube, and the induction heating coil which goes around the tube by forming a gap between the tube and the opposite edge surface of the opening extending along the longitudinal direction of the tube. High frequency induction welding. In the above manufacturing process, a gas flow is caused to flow through a gap between the induction heating coil and the tube to remove magnetic powder from the gap.

[0007] The gas flow is carried out by:-injecting a gas such as air or an inert gas into the gap;-sucking the air in the gap. The gas flow is made to flow constantly or intermittently. It is desirable that the gas injection and suction be performed at an injection position / direction, a suction position / direction, an injection force, a suction force, and the like that do not affect the flux in the pipe.

Further, the apparatus for manufacturing a powder-filled tube according to the present invention is an apparatus for forming a metal strip into a tubular shape while feeding the strip in the longitudinal direction thereof, so that a gap is left along the pipe at least up to a welding point. And an induction heating coil that circulates around the pipe by forming a gap between the pipe and a pipe for joining opposing edge surfaces of an opening extending along the longitudinal direction of the pipe. High frequency induction welding equipment.

[0009] An insulating shielding member for shielding between the induction heating coil and the tube, and a gas flow generator for flowing a gas flow into a gap between the shielding member and the tube are provided. Since the position of the induction heating coil is exposed to welding heat, the insulating shielding member is desirably made of a heat-resistant material such as quartz glass, ceramics, alumina or woven fabric of asbestos, ceramics fiber, or glass fiber. There are two types of gas flow generators: a blow-out system and a suction system.The blow-out system is equipped with a compressor and a blow-out tube. Flow. The suction system includes a suction pump and a suction pipe, and suctions the air in the gap to generate a flow of air.

As the suction pump, a vacuum pump of a positive displacement type, a centrifugal type, an ejector type or the like is used. The outlet pipe,
Since the tip of the suction tube is exposed to welding heat, alumina,
It is desirable to use a heat-resistant material such as silicon carbide or silicon nitride.

[0011]

The gas flow is formed in the gap between the induction heating coil (work coil) and the tube. The flow of gas suppresses the adsorption of the magnetic powder from the tube passing through the work coil to the work coil. Further, even if the magnetic powder is adsorbed on the work coil and is to be accumulated, the magnetic powder is blown off by the gas flow, so that the discharge phenomenon due to the accumulation of the magnetic powder is avoided. Furthermore, when the work coil and the pipe are shielded by an insulating shielding member, the magnetic powder adheres to the shielding member and the distance of the work coil from the water-cooled copper pipe increases. The attraction force is weakened, and the magnetic powder can be easily separated from the work coil even with a weak gas flow. Therefore, a discharge phenomenon between the tube and the work coil due to the magnetic powder being adsorbed and accumulated on the work coil can be avoided, and good welding can be maintained.

[0012]

EXAMPLES The production of a flux cored wire for welding will be described below as an example.

FIG. 1 is a configuration diagram of a main part of a wire manufacturing apparatus. As shown in FIG. 1, a forming roll group 2, a side roll 9, a fin pass roll 5, a seam guide 6, a high-frequency induction welding device 8, and a bead cutter 12 are sequentially arranged along the feeding direction of the pipe 1. The flux supply device 4 is arranged between the side rolls 9. The high-frequency induction welding device 8 includes a work coil 7 and a squeeze roll 10. The work coil 7 is provided so as to form a gap between the work coil 7 and the tube 1 to make several turns around the tube 1. A high frequency welding current of 400 to 600 kHz is supplied to the work coil 7 from a power supply 15. These devices are all existing ones. According to the present invention, such a wire manufacturing apparatus further includes means for flowing a gas flow through the gap 14 between the work coil 7 and the tube 1 and removing the magnetic powder from the gap 14 by putting the magnetic powder on the gas flow. The magnetic powder adsorbed on the work coil 7 or the magnetic powder to be adsorbed on the work coil 7 from the pipe 1 is blown off by a gas flow or removed by suction from the gap 14 so that the magnetic powder does not accumulate on the work coil. ing. Explaining with reference to FIGS. 1 and 2 (a sectional view taken along line II-II in FIG. 1), the blow-out pipe 1 connected to an air compressor (not shown) immediately before the work coil 7.
1 is provided. In this example, the blowout pipe 11 has a ring shape arranged concentrically with the work coil 7, and is provided with a gas injection nozzle 16 facing the gap 14 at regular intervals. As shown in FIG. 2, the water-cooled copper pipe 1 of the work coil 7
7 circulates twice around the tube 1, both ends of which are connected to a high-frequency power supply 15. The water-cooled copper pipe 17 is protected by coating a primary coat 18a with a heat-resistant material, in this example, glass fiber, and further a secondary coat 18b with glass fiber. An insulating shielding member, in this example, a ceramic shielding pipe 19 is provided on the inner peripheral side of the work coil 7.
Is formed concentrically with the work coil 7 and the pipe 1 to form a gap 14. The blowing pipe 11 side of the shielding pipe 19 is open in a trumpet shape so that the air injected from the gas injection nozzle 16 can be easily received in the gap 14. The magnetic powder adsorbed on the shielding pipe is immediately removed from the gap 14 by the injection of the compressed air from the gas injection nozzle (indicated by an arrow), and the accumulation of the magnetic powder is avoided. Air pressure is 0.
It is about 1 to 5 kgf / cm ² .

Here, when manufacturing a flux-cored wire for welding, a steel strip having a width of about 50 to 100 mm and a thickness of about 1.5 to 2.5 mm is used and formed into an open pipe having an outer diameter of about 16 to 33 mm. High frequency induction welding of the opening of the open pipe. The outer diameter of the water-cooled copper pipe of the work coil at that time is 4 to 8 mm
And the heat input supplied by this copper pipe (EpI
p) is about 80 to 250 kVA. In this case, the outer diameter of the water-cooled copper pipe 17 is d, the interval between the outer peripheral surface of the water-cooled copper pipe 17 and the shielding pipe 17 and the inner peripheral surface (that is, the coat thickness) is t ₁ , and the inner peripheral surface of the shielding pipe 19 is Assuming that the interval from the outer peripheral surface (that is, the interval of the gap 14) is t ₂ , t ₁ ≧ 0.2d in order to weaken the attraction force of the magnetic powder to the work coil side.
And t ₁ + t for the purpose of increasing the efficiency of the work coil.
_It is preferable that ₂ ≦ d and t ₂ ≧ 1 mm so that the magnetic powder can be easily removed from the gap 14.

FIG. 3 shows another embodiment of the present invention.
In this embodiment, the water-cooled copper pipe 17 is made of glass fiber 1
2 in that the secondary coat 18a and the secondary coat 18b are coated and protected, and that the gas jet nozzle 16 is provided.
2 except that the entire work coil 7 is coated with a shielding coat 20 made of ceramics instead of the shielding pipe 19 of FIG. In this case, the coat thickness t ₁ is the distance between the outer peripheral surface of the water-cooled copper pipe 17 and the surface of the shielding coat 20. Also in this case, similarly to the example of FIG. 2, compressed air from a compressor (not shown) is injected from the gas injection nozzle 16 as shown by an arrow. The magnetic powder adsorbed on the shielding coat 20 by this air injection is immediately removed from the gap 14, and accumulation of the magnetic powder is avoided. In each of the embodiments shown in FIGS. 2 and 3, the gas flow generator employs a blowing method in which gas is injected from a gas injection nozzle into the gap 14. Instead, the suction pipe sucks air in the gap 14. A suction method may be adopted. In the case of the suction method, the magnetic powder in the gap 14 is drawn into the suction tube together with air and collected in the collection tank. Further, the surface of the shielding member such as the shielding pipe 19 and the shielding coat 20 is desirably as smooth as possible so that the magnetic powder is hardly attached to the surface, and is desirably detached when adhered.

Here, the results of manufacturing the flux cored wire for welding manufactured by the apparatus shown in FIGS. 1 and 2 configured as described above will be described. Width 62.9mm, thickness 2.2
mm steel strip (SPHC steel strip) with an outer diameter of 22 mm and an inner diameter of 17 mm
The opening was welded and joined by high frequency induction welding. During the molding, the flux was filled at a filling rate of 12%.
The welded pipe was reduced in outer diameter to 12.5 mm by a reduced diameter roll group 2 and wound around a coil. Then, in a separate drawing step, the wire was drawn to an outer diameter of 1.2 mm at a final drawing speed of 1000 m / min by using 33 dies. Welding heat input EpIp =
12.4 (kV) x 11.8 (A) = 146.3 kVA, and the welding speed (tube speed) was 30 m / min. Water-cooled copper pipe diameter d = 5 mm in FIG. 2, the distance between the water-cooled copper pipe and tube t ₁ + t ₂
= 4 mm, the life of the work coil was investigated by changing the coat thickness t ₁ as shown in Table 1. Table 1 shows the results of the investigation. The air pressure of the air injected from the gas injection nozzle is 1 kgf / cm ² .

[0017]

[Table 1]

As is evident from Table 1, when no gas flow is caused to flow through the gap between the work coil and the tube, and only the glass fiber is used, the magnetic powder is adsorbed on the work coil, and the magnetic powder is accumulated and is accumulated. Electric discharge occurred in a short period of time, and the water-cooled copper pipe of the work coil was damaged. On the other hand, in the examples of the present invention shown in FIGS. 2 and 3 in which the gas flow is applied, the magnetic powder is removed from the gap between the work coil and the pipe by the gas flow, so that no accumulation occurs and no discharge phenomenon occurs. As a result, no change was observed in the work coil in the experiment for about 100 hours.

[0019]

According to the present invention, since the gas flow flows in the gap between the work coil and the pipe, the magnetic powder attached to the pipe is less likely to be adsorbed to the work coil. In addition, even if an attempt is made to adsorb and accumulate, the gas is blown off by the gas flow and is discharged out of the gap. Therefore, since a discharge phenomenon does not occur due to the magnetic powder interposed in the gap between the work coil and the tube, it is possible to prevent the work coil from being damaged by the discharge. As a result, it is possible to improve the operation rate and the yield in the production of the powder-filled tube.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, and is a configuration diagram of a main part of an apparatus for manufacturing a flux cored wire for welding.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view showing another example of a work coil portion of the wire manufacturing apparatus.

[Explanation of symbols]

 Reference Signs List 1 tube 2 forming roll group 3 flux 4 flux supply device 5 fin pass roll 6 seam guide 7 induction heating coil (work coil) 8 high frequency induction welding device 9 side roll 10 squeeze roll 11 blow-out tube 13 welding point 14 work coil and pipe Gap 16 Gas injection nozzle 17 Water-cooled copper pipe 18a, 18b Primary coat, secondary coat 19 Shielding pipe 20 Shielding coat

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Seiji Hashimoto 3-5-4 Tsukiji, Chuo-ku, Tokyo Nippon Steel Welding Industry Co., Ltd. (56) References JP-A-3-294098 (JP, A) Kaihei 4-55088 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) B23K 35/40 B23K 13/00

Claims (2)

(57) [Claims] The metal strip is formed into a tube while feeding the metal strip into the pipe so as to feed the metal strip in the longitudinal direction thereof and leave a gap along the pipe at least up to a welding point. A method for producing a powder-filled tube by high-frequency induction welding with an induction heating coil that forms a gap between the tube and the opposite edge surface of the opening extending along the tube longitudinal direction and forms a gap between the tube and the tube, A method for manufacturing a powder-filled tube, characterized in that a gas flow is passed through a gap between the induction heating coil and the pipe to remove magnetic powder from the gap. 2. An apparatus for forming a metal strip into a tube while feeding the metal strip in the longitudinal direction thereof, an apparatus for supplying a granular material into the pipe so as to leave a gap along the pipe at least up to a welding point, and An apparatus comprising: a high-frequency induction welding device including an induction heating coil that forms a gap between a pipe for joining opposing edge surfaces of an opening extending along a pipe longitudinal direction and circulates the pipe; Manufacture of a powder-filled tube, comprising: an insulating shielding member for shielding between a heating coil and a tube; and a gas flow generator for generating a gas flow in a gap between the shielding member and the tube. apparatus.