JPH06218579A - Production of powdery particle filling tube - Google Patents

Abstract

PURPOSE:To provide production method of a powdery particle filling tube having no crack on tube outer skin by obtaining a sound joining weld part. CONSTITUTION:In the production method of a powdery particle filling tube, in which in the course of forming a metal strip to a tubular body l, a powdery particle 20 is supplied, both edge faces 23 of the tubular body 1 are joined by high frequency welding and a welded tube 11 filled with the powdery particle 20 has its diameter reduced, the edge face 23 at the neighborhood of upstream side of V converging point of both edge faces is heated by a laser beam 24, the powdery particle 26 sticked to the edge face 23 is discharged from the edge face 23. The powdery particle 26 magnetically sticked on the edge face 23 is promoted to fuse by beam absorption, increasing its fluidity, it is discharged from the joining weld face with a molten metal by the electromagnetic force of high frequency current or the pressing force of squeeze roll.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a powder / granule-filled tube in which carbon steel, stainless steel, copper alloy, aluminum alloy or other metal tube is filled with the powder / granular material.

Here, the powder or granules mean powder or granules such as welding flux, oxide superconducting material, and additive for molten steel.

[0003]

2. Description of the Related Art A flux-cored seamless wire for welding is one type of powder-filled tube. In the production of this seamless wire, the strip steel is slit to the required width,
The strip steel after slitting is gradually formed from a U-shape to an O-shape by a forming roll. During this forming, the flux is supplied from the opening along the longitudinal direction of the U-shaped strip steel to the strip steel valley portion by the feeder. Then, while forming into an O-shape, the opposite edge surfaces of the opening are joined by welding, and the diameter is subsequently reduced. Further, after annealing if necessary, the tube filled with the flux is drawn into a desired diameter and wound up to obtain a product.

As a welding method in the production of the powder-filled tube, high-frequency welding such as high-frequency induction welding method and high-frequency resistance welding method is widely used. In all of these welding methods, when formed into a substantially O shape, the Joule heat generated by the high frequency current heats the edge surface of the opening to the melting temperature and presses the opposing edge surfaces with a pair of squeeze rolls.

Various raw material powders are selected for the powder or granular material supplied to the opening of the tubular body according to the purpose of use of the powder or granular material filling tube, and they are used as they are or after being granulated. For example, in a flux-cored wire for welding, rutile sand, magnesia clinker, etc. as a slag generator, sodium silicate, potassium titanate, etc. as an arc stabilizer, low C-Fe-Si, Fe-Si-Mn as a deoxidizer / alloying agent, Al
-Mg or the like is used, and a ferromagnetic component such as iron powder or iron oxide may be blended for improving the deposition rate, adjusting the flux filling rate, and improving the welding workability. In any case, the flux to be filled contains at least 5% or more of the total Fe component and has a particle size distribution of 32.
At least 5 fine particles from mesh (0.5mm) to Dust
It is customary to include 0% or more. In the case of granulating, all of the flux particles, and in the case of non-granulating, in the particles of raw material iron alloy, iron powder, iron oxide, etc., the ferromagnetic component Fe
Minutes included. Further, iron content, iron oxide, etc. may be unavoidably mixed in the raw material powder during the purification of the raw material or during the pulverization.

By the way, when a pipe filled with flux and welded is reduced in diameter by rolling, wire drawing, or the like, cracks may occur in the outer skin of the pipe. And as the cause of this crack,
It is considered as follows. During welding, part of the flux such as oxides and silicates is adsorbed on the opening edge surface of the tubular body. That is, at the welding position, the magnetic field generated by the welding current makes the opening edge of the tubular body a magnetic pole. Not only when the ferromagnetic components such as iron powder and iron oxide are positively mixed in the filled flux, but also when the flux is composed only of so-called weak magnetic components, flux particles are formed on the opening edge surface of the magnetic pole. There is a full risk of adsorbing. In particular, fine particles that are less than the equilibrium particle size in which the suction force acting on the particles and the gravity against it are balanced are directly subject to the suction force. In addition to this, a certain degree of component segregation is unavoidable in the granulation flux, and if the segregation of Fe is concentrated in the fine particles, the above equilibrium particle size is raised, and as a result, the number of fine particles subject to suction force increases and /
Gravity] ratio increases, which is extremely dangerous. Therefore, the ferromagnetic component of the flux is attracted to the opening edge portion by the magnetic force. At this time, the non-magnetic component is also attracted to the opening edge portion along with the ferromagnetic component. The flux adsorbed on the edge portions of the openings becomes inclusions in the welded joint, resulting in welding defects. Then, due to this welding defect, cracking occurs when the diameter is reduced. The cracks when the diameter is reduced are directly introduced into the product, that is, the flux-cored wire for welding, and deteriorate the welding workability.

One of the techniques for solving such a problem is "composite wire for welding" disclosed in Japanese Patent Laid-Open No. 60-234794, which is a powder raw material having a non-permeability of 1.10 or less. Is filled with a non-magnetic powder to prevent the powder from being attracted to the opening edge by magnetic force. JP-A-63-58
There is a "composite pipe manufacturing method" disclosed in Japanese Patent Publication No. 97,
Fine powder finer than 48 mesh is removed when the powder is supplied to prevent the fine powder from adhering to the opening edge portion. Further, as another technique, there is a "method for producing a tube filled with powder" disclosed in JP-A-54-109040. This technique supplies powder so that it does not fill the tubular body, and creates a gap or distance between the joint weld and the surface of the powder layer that has been supplied. I try not to reach.

[0008]

However, even if the joint welding portion is improved by the above-mentioned conventional technique, the cracks as described above still occur when the diameter of the pipe is reduced, and the product yield is lowered. Once the cracks occur, even if the cracks are minute at first, the cracks extend in the longitudinal direction of the pipe as the reduced diameter size of the pipe becomes smaller, and the length becomes a length that cannot be ignored in the product size.

[0009] Therefore, an object of the present invention is to provide a powder-and-granule-filled pipe having no cracks on the outer shell of the pipe by obtaining a sound joint weld.

[0010]

The inventors have reiterated that cracks when the pipe diameter is reduced are welding defects due to magnetic particles magnetically adhering to the opening edge portion of the tubular body during welding. In addition to recognizing this, in order to prevent this, it is necessary to supply only substantially non-magnetic raw material powder, or to provide a gap or distance between the welded joint and the supplied powder layer surface. It was also confirmed that the effect is poor, that is, there is a limit to eliminating the magnetic sticking of the powder particles to the opening edge surface of the tubular body. Therefore, from the viewpoint that this magnetic sticking is unavoidable, the inventors have diligently studied a means for removing the magnetic sticking powdery particles from the welded joint to obtain a clean state without inclusions.

As a result, it was found that the powder particles can be squeezed out into and out of the tube almost completely if the powder particles magnetically attached to the opening edge surface are melted and the tubular body is pressure-contacted with a squeeze roll. . However, it has been found that it is difficult to instantaneously melt the powder particles by an indirect heating method using a high frequency current. That is, the powdery particles that are magnetically attached to the edge surface of the opening may have Fe as a constituent component.
In addition to various components, namely Ti, Si, Zr, Mn,
Mg, Al, etc. are included. Granular particles such as Ti, Si, are instantaneously (within approximately 0.5 seconds) on the edge surfaces near the V convergence point (within approximately 60 mm) of both edges where the granular particles are magnetically attached.
It is difficult to melt Zr, Mn, Mg, Al, etc. by an indirect heating method by heat conduction from the opening edge surface of the tubular body heated and melted by Joule heat generated by a high frequency current. The reason is considered to be due to the differences in melting point, specific heat, heat of fusion, thermal conductivity, etc. between these components and the steel that is the material of the tube. For example, Ti (melting point: 1675 ° C), Zr
(Melting point: 1852 ° C.), the melting point is that of steel (15
Since it is higher than 35 ° C, it is difficult to melt. Therefore, they have found that it is necessary to add new heating means.

The present invention was made based on these findings. The method for manufacturing a powder-filled tube according to the present invention, the powder is supplied to the tubular body in the course of forming the metal strip into a tubular body, both edge surfaces of the tubular body are joined by high frequency welding, In a method for manufacturing a powder-filled body filling tube for reducing the diameter of a welded tube filled with, the edge surfaces in the vicinity of the upstream side of the V convergence point of the both edge surfaces are heated by a laser beam, and the powder particles attached to the edge surface Eject body particles from the edge surface.

In the present invention, the edge surface in the vicinity of the upstream side of the V converging point of both edge surfaces is the magnetic field in the granular material due to the magnetic field generated by the high frequency welding current on the upstream side including the V converging point. An edge surface having the possibility of magnetically attracting particles.

The ratio of the amount of heat of the laser beam to the total amount of heat (heat input) required for joining and welding both edge surfaces depends on the type of powder and granules, the welding current, the welding speed, the size of the tubular body, etc. Decide The above ratio is, for example, 10
It is about 90%. The welding current can be reduced by this proportion as compared with the joining of the edges by only the welding current. Further, the amount of heat applied to the edge portion by the welding current and the laser beam needs to be equal to or more than the amount of heat that does not cause cold welding cracks, and it is desirable that the amount of heat that does not cause spatter.

Particles and particles adhering to the edge surfaces are detected on the upstream side of the V-converging point of both the edge surfaces, and the laser beam is irradiated to the detected particle and particle particles and the edge surfaces in the vicinity thereof. Good. In this case, at least the welding current is used to join the edge surfaces.

[0016]

By applying the laser beam to the edge surface in the vicinity of the upstream side of the V convergence point of both edge surfaces in the semi-molten to molten state or in the state immediately before being heated by the Joule heat generated by the high frequency current, a large amount can be obtained. The heat is instantly and locally supplied. As a result, the powder particles that are magnetically attached to the edge surface are melted by the beam absorption and the flowability is improved, so that the particles are discharged from the welded surface together with the molten metal by the electromagnetic force of the high frequency current or the pressure contact force of the squeeze roll. It Further, the welding current can be reduced by the amount of heating by the laser beam. Therefore, since the magnetic field in the tube is reduced and the influence on the powder particles in the tube is reduced, the number of powder particles magnetically attached to the opening edge surface is reduced.

[0017]

EXAMPLES The manufacturing of flux-cored wires for welding will be described below as examples. FIG. 6 is a configuration diagram of a main part of the welding flux-cored wire manufacturing apparatus. As shown in FIG. 6, the forming roll group 2, the side rolls 3, and the flux supply device 4 are arranged along the feeding direction of the open pipe (tubular body) 1.
Are arranged. A preforming roll (not shown) is provided on the upstream side of the forming roll 2. The flux 20 is supplied from the space 5 between the side rolls 3 to the open tube 1 in the middle of molding. The open pipe 1 supplied with the flux 20 passes through the fin pass roll 6 and the seam guide roll 7 and enters the welding zone. The high frequency induction welding device 8 includes a work coil 9 and a squeeze roll 1.
It has 0. A high frequency welding current is supplied to the work coil 9 from a power source 12. The welded pipe 11 has an extra bead 14 cut on the outer surface side by a cutting tool 13,
The product is rolled by a group of rolling rolls 16 and further annealed to reduce the product size to an outer diameter of 1.0 to 2.0 mm by a rolling device and a wire drawing device (neither is shown).
The extra bead 15 on the inner surface side remains as it is up to the product size.

By such high frequency induction welding, the width w = 3
A steel strip having a thickness of 0 to 150 mm and a thickness t of about 1.0 to 5.0 mm is formed into a pipe having an outer diameter D _{0 of} about 10 to 50 mm. As welding conditions at this time, the frequency of the high frequency current f = 300 to 800 kH
z Heat input (electric energy) P = 50 to 500 KVA Distance between work coil and welding point L = 10 to 100 mm Apex angle (V convergence angle) θ = 3 to 15 ° Speed) V = 10
Pipe forming is performed at a speed of about 200 m / min.

The manufacturing apparatus for carrying out the method of the present invention has a structure in which a laser beam irradiation means is additionally provided to the high frequency induction welding apparatus 8 in the wire manufacturing apparatus shown in FIG. That is, FIG. 1 is a block diagram of a welding apparatus used in the present invention, in which the laser beam irradiation means 1
Reference numeral 7 is a laser oscillator 18 for YAG laser, and an incident lens 1
9, an optical fiber cable 21 for beam transmission and a condenser lens 22. The laser beam output from the laser oscillator 18 passes through the incident lens 19, the optical fiber cable 21, and the condenser lens 22 and is applied to the V convergence point 25 of the opening edge surface 23 that is the target position or the edge surface near the upstream side. . The condenser lens 22 is arranged above the opening edge surface 23 so that the laser beam 24 directed to the target position is irradiated at a predetermined irradiation angle θ. As this irradiation angle θ becomes smaller, V
The laser beam 24 heading for the convergence point 25 irradiates the edge surface 23 in the vicinity of the V convergence point 25 with an increased area, so that the energy efficiency is improved. Therefore, it is desirable that the irradiation angle θ is small, and for example, θ ≦ 30 ° is set. The beam shape can be circular or rectangular.

FIG. 2 is a sectional view taken along the line II-II in FIG. 1, showing the irradiation state of the laser beam 24 on the edge surface 23. Magnetic particles 26 existing on the surface layer of the flux 20
Is attracted to the magnetized edge surface 23 and rises to be magnetized. At this time, when the laser beam 24 irradiates the edge surface 23 in the vicinity of the V convergence point 25, the magnetic particles 26 magnetically attached to the edge surface are rapidly heated and instantly melted. That is, since the edge surface 23 is already heated by Joule heat by a high frequency current and is in a semi-molten to molten state or a state immediately before that, the magnetic particles 26 are irradiated with the laser beam 24 in addition to the heating by heat conduction from the edge surface 23. As it receives it, it absorbs the energy and instantly reaches the melting temperature. Since the irradiation of the laser beam 24 is for the purpose of melting the magnetic particles on the edge surface 23 in addition to the heating by the Joule heat as described above, it is high enough to melt the edge surface by the laser beam alone. Power is not required, and rather there is a risk that the edge surface is excessively heated and scooped out, and it causes frequent occurrence of spatter, which is not preferable. But,
Irradiation of a moderately low-power laser beam not only promotes melting of magnetic particles magnetically attached to the edge surface as described above, but also contributes to a rise in temperature of the edge surface and contributes to heat input of high-frequency welding (power amount P). It has a ripple effect of reducing the burden.

FIG. 3 is a constitutional view showing another example of the heating laser beam irradiating means. The left side of the discontinuous line is a longitudinal sectional view of the tube showing the arrangement state of the laser beam irradiating means, and the right side is the opening edge surface 23. It is a top view showing the irradiation state of the laser beam to the. The laser beam irradiation means 37 includes a laser oscillator 38 for CO ₂ laser, an optical system 39 for beam shape adjustment, and a reflecting mirror 40. The laser beam output from the laser oscillator 38 is adjusted by the optical system 39 in accordance with the cross-sectional shape, width (diameter), and the like of the opening edge surface, and enters / reflects at the reflecting mirror 40 and then along the edge surface. And go straight at the irradiation angle θ = 0 °. Laser beam 41
Is, for example, a rectangular shape with a cross section L × 2L (L = edge thickness). When the laser beam 41 goes straight through the gap along the edge surface of the aperture and approaches the edge surface near the upstream side of the V convergence point 25, that is, the magnetic attachment zone, and when both ends 41e of the beam reach the edge surface, the V beam converges from that position. The entire edge surface up to the point 25 is irradiated. In this case, as shown in the drawing, the laser beam 41 repeatedly enters and reflects at each point on both edge surfaces, and eventually converges to the V convergence point 25. That is, when the beam hits one edge surface, a part is absorbed and reflected, and when the beam hits the other edge surface, a part is absorbed and reflected there, which is a so-called multiple reflection mode. Therefore, this example can be said to be an example suitable for the case where a CO ₂ laser having a high reflectance is used because of its wavelength characteristic (10.6 μm). In order to prevent a decrease in energy efficiency due to the reflection of the beam out of the edge surface area, it is desirable that the groove shape of the edge surface is I-shaped (the edge surfaces are parallel) as much as possible.

It is also possible to irradiate the laser beam onto the edge surface in the vicinity of the upstream side of the V convergence point after detecting magnetic particles on the edge surface with the exploration sensor. An optical sensor such as a laser beam or an image sensor is used as the exploration sensor. In Fig. 4, He-
An example using a Ne laser beam will be shown. The laser beam irradiation means 27 includes a laser oscillator 29 and the laser oscillator 29.
A reflection mirror 34 that totally reflects the laser beam from the laser beam and irradiates it along the edge surface 23;
It is composed of a semi-transmissive mirror 31 and a light receiver 32 arranged at an angle of 5 °. The laser beam 30 totally reflected by the reflecting mirror 34 goes straight along the edge surface, and when the magnetic particles 26 magnetically attracted to the edge surface are caught in the middle, they are reflected there.
A part of the reflected light goes backward and enters the semi-transmissive mirror 31, is reflected, and then enters the light receiver 32. The signal of “with magnetic particles 26” that is incident on the light receiver 32 and amplified is processed by the controller 33 to operate the laser beam irradiation means 17 for heating. Laser beam 2 output from laser oscillator 18
4 irradiates the edge surface 23 near the V convergence point 25, and melts the magnetic particles 26 captured by the laser beam 30.
The beam shape can be circular or rectangular. The installation position of the laser beam irradiation device 27 for exploration, that is, the irradiation position of the laser beam, the number and position of the light receivers should be determined according to the shape of the magnetic particles magnetically attached to the edge surface and the frequency of magnetic attachment. Therefore, concretely, it is decided based on the data by repeating the experiment.

FIG. 5 is a cross-sectional view of a tube showing still another example in the case of using an exploration sensor, in which magnetic particles on the edge surface are detected for each edge surface.
In the figure, the magnetic particles 26 on the edge surface 23r on the right side are detected by an optical sensor 44 composed of a light projector 42r and a light receiver 43r.
The detection of the magnetic particles 26 on the left edge surface 23l is carried out by the optical sensor 44l consisting of the projector 42l and the light receiver 43l. Each optical sensor 44r, 44
The light emitter and the light receiver of l are arranged to be inclined or perpendicular to the longitudinal direction of the tubular body 1, and each of the optical sensors 44r, 44
The beams 45r and 45l from l are arranged so as not to interfere with each other. Each optical sensor 44r, 4
Although 4l may be a pair, staggered formation of a plurality of pairs is effective in preventing detection leakage of magnetic particles.

Next, the result of cracking of the flux-cored wire for welding manufactured by the above apparatus will be described.
Steel strip with a plate thickness of 2.2 mm and a width of 65.5 mm (SPHC, C =
0.05%) is molded into a tube having an outer diameter of 22.4 mm and an inner diameter of 18.0 mm. Flux was supplied at a filling rate of 15% during molding, and open pipes were continuously butt-joined. At this time, the frequency of the high frequency current supplied to the work coil is 510 kHz.
z, welding speed V was 30 m / min, work coil to welding point distance was 25 mm, and apex angle was 6 °. The tube after welding was annealed once with a group of rolling rolls to reduce the outer diameter to 3.2 mm, annealed and plated, and wound into a coil. Then, finish drawing and reducing the diameter to a product size of 1.2 mm in outer diameter and 0.6 mm in inner diameter were examined for crack occurrence in the product wire.

The welding speed V is 30 m / min and the pipe thickness t is 2.
When the edge surface is joined and welded only by the welding current with a thickness of 2 mm, cold welding cracking and sputtering are not observed in the heat input range of 128 to 141 kVA. Also, 141-
In the heat input range of 181 kVA, spattering is observed, but large-scale spattering that causes wire breakage does not occur in the final finish drawing process.

If high-frequency induction welding is carried out with heat input in this proper heat input range, good welding can be carried out as long as the edge surfaces of the tubular bodies to be abutted are clean. However, as described above, in this welding, a strong magnetic field is generated at the welding position, and the magnetic particles in the flux float up and are easily magnetically attached to the edge surface, so that it is not always in a clean state. In the present invention, heating is further performed by irradiating the edge surface near the upstream side of the V convergence point, which is heated by Joule heat of the high frequency current and is in a high temperature state, with a laser beam. As a result, the granular particles magnetically attached to the edge surface are instantly melted, and as a result, the fluidity is improved, so that the molten metal is discharged well from the welded surface by the electromagnetic force of the high frequency current or the pressure contact force of the squeeze roll. It will be.

In this embodiment, the laser beam irradiation means shown in FIG. 1 was used. The irradiation conditions are as follows. In addition, conditions for using the exploration sensor shown in FIG. 4 are also shown. (Laser beam for heating) Type: YAG laser wavelength: 1.06 μm Oscillation waveform: Pulse oscillation pulse width: 1 power: 1 kW (average) Beam diameter: 2.2 mmφ (V convergence point position) Irradiation angle: 25 ° Irradiation time ... 0.2s (only when used in combination with the laser beam for exploration) (Probing sensor) Type ... He-Ne laser wavelength ... 0.633 µm oscillation waveform ... Continuous oscillation beam diameter ... 2.0 mmφ (parallel light flux) irradiation angle ... 0 ° (Parallel to the edge surface) When the edge surface is heated by this laser beam irradiation,
If the heat input by the welding current is at least 93 kVA, cold weld cracking does not occur. In addition, heat input due to welding current is 14
If it is 1 kVA or less, spatter will not occur.

In this embodiment, butt welding was performed with a heating laser beam alone, with a heat input P = 110 kVA, and with an exploration sensor together, with a heat input P = 135 kVA.

The composition of the supplied flux is shown in Table 1.
After mixing the raw material powders, a fixing agent (water glass) was added, and the mixture was granulated and classified to prepare fluxes F1 and F2.

[Table 1]

Table 2 shows the results of crack generation. The cracks were evaluated by conducting an eddy current flaw detection test on the wire sheath over the entire length of 100 km of the product wire having an outer diameter of 1.2 mmφ (wire 20 kg spool x 37) after wire drawing to confirm the presence and position of cracks,
It was carried out by observing the corresponding portion with a magnifying glass when a cracking signal was output and confirming the presence of cracks in the longitudinal direction of the wire.
When the presence of cracks could not be confirmed at all, this was regarded as good. Also, if there is a crack, the treatment liquid tends to infiltrate into the wire during surface treatment or wire drawing from the opening of the crack and deteriorate the quality of the product. I made this a defect.

[Table 2]

In Table 2, Experiments Nos. 1 to 4 are experimental examples of the present invention, Nos. 1 and 2 are examples in which the heating laser beam irradiation means is used alone, and Nos. 3 and 4 are exploration sensors. This is an example of using together. In any of these experimental examples, cracks in the pipe outer shell were not confirmed, the quality of the product wire was good, and when welding was performed using this flux-cored wire for welding, good welding workability was realized. .

On the other hand, Experiment Nos. 5 and 6 are comparative examples, and the heating laser beam irradiation means was not used. In each of Experiments Nos. 5 and 6, cracks were confirmed in the tube skin, but in Experiment No. 6 using the flux F2 containing iron powder and having a large amount of total Fe, the occurrence of cracks was remarkably observed. . Eventually, in these comparative examples, the magnetic particles existing in the flux surface layer were soared by the magnetic field and magnetically adhered to the edge of the tubular body, and as a result, cracking occurred and the product yield was lowered.

[0033]

According to the present invention, powder particles are supplied to the tubular body while the metal strip is formed into the tubular body, both edge surfaces of the tubular body are joined by high frequency welding, and the powder particles are filled. In a method for producing a powder-filled tube for reducing the diameter of a welded pipe
Since the laser beam is irradiated to the edge surface near the upstream side of the convergence point, the melting of the granular particles magnetically attached to the edge surface is promoted and the fluidity is improved. As a result, the molten metal is satisfactorily discharged from the welding surface by the electromagnetic force of the high frequency current or the pressure contact force of the squeeze roll. Therefore, the cracking of the tube due to the magnetic particles being magnetically attached to the edge surface of the open tube is substantially eliminated. Further, the heat input burden due to the high frequency current is reduced, and the heat input amount (power amount P) can be reduced. As a result, the magnetic field in the tube is reduced, the influence on the particles in the tube is reduced, and the number of particles of the particles that are magnetically attached to the opening edge surface is reduced. For these reasons, the product yield can be improved, and a powder-filled tube with good quality can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an example of an apparatus for producing a powder / particle filling tube of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG. 1 showing a laser beam irradiation state on the edge surface.

FIG. 3 is a constitutional view showing another example of the apparatus for producing the powder / granule-filled tube of the present invention.

FIG. 4 is an explanatory diagram showing a usage state of the exploration sensor.

FIG. 5 is an explanatory diagram showing another usage state of the exploration sensor.

FIG. 6 is a configuration diagram of a main part of an apparatus for manufacturing a flux-cored wire for welding.

[Explanation of symbols]

 1 Open Pipe (Tubular Body) 2 Forming Roll Group 3 Side Roll 4 Flux Supply Device 6 Fin Pass Roll 7 Seam Guide Roll 8 High Frequency Welding Device 9 Work Coil 10 Squeeze Roll 11 Welded Pipe 12 Power Supply 16 Rolling Roll Group 17 For Heating Laser beam irradiating means 18 Laser oscillator 19 Incident lens 20 Flux 21 Optical fiber cable 22 Condensing lens 23 Edge surface 24 Laser beam 25 V Converging point 26 Magnetic particle 27 Laser beam irradiating means (sensor) 29 Laser oscillator 30 Laser for exploration Beam 31 Semi-transparent mirror 32 Receiver 33 Controller 34 Reflector 37 Laser beam irradiation means for heating 38 Laser oscillator 39 Optical system 40 Reflector 41 Laser beam 42r, 42l Projector 43r, 43l Photoreceptor 44r, 44l Optical sensor 5r, 45l light beam

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuo Mizuhashi 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Corporation Corporate Technology Development Division

Claims (2)

[Claims] 1. A powdery or granular material is supplied to the tubular body in the course of forming a metal strip into a tubular body, both edge surfaces of the tubular body are joined by high frequency welding, and a welded tube filled with the granular material is compressed. In the method for manufacturing a powder-filled granular tube, the edge surfaces near the upstream side of the V convergence point of both the edge surfaces are heated by a laser beam, and the powder particles attached to the edge surfaces are discharged from the edge surfaces. A method for manufacturing a powder-filled tube, which is characterized by the above. 2. A powdery or granular material particle adhering to the edge surface is detected on the upstream side of the V convergence point of the both edge surfaces, and the detected powdery or granular material particle and the edge surface in the vicinity thereof are irradiated with the laser beam. Item 2. A method for producing a powder-filled tube according to Item 1.