JP2792802B2 - Manufacturing method of 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 for producing 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 term "granules" refers to powders such as welding fluxes, oxide superconductors, additives for molten steel, and the like.

[0003]

2. Description of the Related Art As one of powder-filled tubes, there is a flux-cored seamless wire for welding. In the production of this seamless wire, the strip is slit to the required width,
The strip after the slit is gradually formed from a U-shape to an O-shape by a forming roll. During this forming, the flux is supplied to the strip valley portion from the opening along the longitudinal direction of the U-shaped strip by a feeder. 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, if necessary, after annealing, the tube filled with the flux is drawn and wound into a desired diameter to obtain a product.

[0004] High frequency welding such as high frequency induction welding and high frequency resistance welding is widely used as a welding method in the production of the above-mentioned powder-filled tube. In any of these welding methods, when formed into a substantially O-shape, the edge surface of the opening is heated to the melting temperature by Joule heat generated by a high-frequency current, and the opposing edge surfaces are pressed against each other by a pair of squeeze rolls.

Various kinds of raw material powders are supplied to the opening of the tubular body in accordance with the purpose of use of the powder-filled tube, and are used as they are or granulated. For example, flux cored wires for welding include rutile sand and magnesia clinker as slag forming agents, sodium silicate and potassium titanate as arc stabilizers, and low C-Fe-Si, Fe-Si-Mn, as deoxidizing agents and alloying agents. Al
-Mg or the like is used, and a ferromagnetic component such as iron powder or iron oxide may be blended for improving the welding speed, adjusting the flux filling rate, and improving the welding workability. In any case, the flux to be filled contains at least 5% or more as a total Fe component, and its particle size distribution is 32%.
Mesh (0.5 mm) to at least 5 particles of Dust
Usually, it contains 0% or more. In the case of granulation, the ferromagnetic component Fe is contained in all the flux particles, and in the case of non-granulation, in the particles of the raw material powder such as iron alloy, iron powder and iron oxide.
Minutes are included. In addition, iron, iron oxide, and the like may be inevitably mixed into the raw material powder at the time of raw material refining or pulverization.

[0006] When the diameter of a welded pipe filled with a flux is reduced by rolling, drawing, or the like, a crack may be generated in the outer jacket of the pipe. And as a cause of this crack,
It is thought that: At the time of welding, a part of the flux such as an oxide or a silicate is adsorbed on the opening edge surface of the tubular body. That is, at the welding position, the opening edge of the tubular body becomes a magnetic pole due to the magnetic field generated by the welding current. Not only when ferromagnetic components such as iron powder and iron oxide are positively blended into the filling flux, but also when the flux is composed only of a so-called weak magnetic component, the flux particles are formed on the poled opening edge surface. There is a significant risk of adsorption. In particular, fine particles less than the equilibrium particle size, in which the attractive force acting on the particles and the gravity against them are balanced, are directly subject to the attractive force. In addition to this, a certain degree of component segregation is inevitable in the granulated flux, and when the segregation of Fe is concentrated on the fine particles, the equilibrium particle size is raised. /
It is extremely dangerous because the [gravity] ratio increases. Therefore, the ferromagnetic component of the flux is attracted to the opening edge by the magnetic force. At this time, the non-magnetic component also adsorbs to the opening edge along with the ferromagnetic component. The flux adsorbed on these opening edges becomes inclusions in the welded joint and causes welding defects. Then, cracks occur at the time of diameter reduction due to this welding defect. Cracks at the time of diameter reduction are directly carried into a product, that is, a flux-cored wire for welding, and deteriorate welding workability.

As one of the techniques for solving such a problem, there is a "composite wire for welding" disclosed in Japanese Patent Application Laid-Open No. 60-234794, in which a powder material having a non-magnetic permeability of 1.10 or less is substantially used. 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
No. 97, there is a "method of manufacturing a composite pipe",
When the powder is supplied, fine powder finer than 48 mesh is removed to prevent the fine powder from adhering to the opening edge. As another technique, there is a "method of manufacturing a tube filled with powder" disclosed in JP-A-54-109040. In this technique, the powder is supplied so as not to fill the entire tubular body, a gap or distance is provided between the joint welding portion and the surface of the supplied powder layer, and the powder rises and the opening edge portion is formed. Not to reach.

[0008]

However, even if the prior art is used to improve the weld joint, the above-mentioned cracks still occur when the pipe is reduced in diameter, resulting in a reduction in product yield. Once cracks occur, even small cracks initially extend in the longitudinal direction of the pipe as the reduced diameter of the pipe decreases, and become a length that can no longer be ignored in the product size.

Accordingly, an object of the present invention is to provide a powder-filled tube in which the outer shell of the tube is not cracked by obtaining a sound joint weld.

[0010]

Means for Solving the Problems The inventors have re-examined that cracks at the time of pipe diameter reduction are welding defects due to magnetic particles magnetically adhering powder particles to the opening edge of the tubular body during welding. Recognize and prevent this by supplying only substantially non-magnetic raw material powder, or only by vague measures such as providing a gap or distance between the joint weld and the supplied powder layer surface It was also confirmed that the effect was poor, that is, there was a limit to eliminating the magnetic adhesion of the powder particles to the opening edge surface of the tubular body. Therefore, from the viewpoint that this magnetic adhesion is inevitable, the inventor diligently studied means for removing the magnetically-adhered powder particles from the welded joint to obtain a clean state without inclusions.

As a result, it has been found that if the powdery particles magnetically adhered to the opening edge surface are brought into a molten state and the tubular body is pressed against the squeeze roll, the powdery particles can be almost completely squeezed out of the tube. . However, it has been found that it is difficult to instantly melt the powder particles by an indirect heating method using a high-frequency current. That is, for example, Fe powder as a component is
In addition, various components, namely, Ti, Si, Zr, Mn,
Mg, Al, etc. are contained. Instantly (within about 0.5 seconds) on the edge surface near the V convergence point (within about 60 mm) of both edges where the magnetic particles are magnetically attached, that is, with Ti, Si,
It is difficult to melt Zr, Mn, Mg, Al, and the like by an indirect heating method using heat conduction from an opening edge surface of a tubular body heated and melted by Joule heat generated by a high-frequency current. The reason is considered to be based on differences in melting point, specific heat, heat of fusion, thermal conductivity, and the like between these components and steel as the material of the tube. For example, Ti (melting point: 1675 ° C.), Zr
(Melting point: 1852 ° C.), the melting point of the steel is
(35 ° C.), so it is difficult to melt. Therefore, it has been found that it is necessary to add a new heating means.

The present invention has been made based on these findings. In the method for manufacturing a powder-filled tube according to the present invention, the powder is supplied to the tubular body while the metal strip is being formed into the tubular body, and both edge surfaces of the tubular body are joined by high-frequency welding. In the method for producing a powder-filled tube for reducing the diameter of a welded tube filled with a powder, the edge surface near the upstream side of the V convergence point of the both edge surfaces is heated with a laser beam, and the powder particles adhered to the edge surface are heated. The body particles are discharged from the edge surface.

[0013] In the present invention, the edge surface near the upstream side of the V convergence point of both edge surfaces includes the V convergence point and is located upstream of the V convergence point. An edge surface that has the possibility of magnetically attracting particles.

The ratio of the calorific value of the laser beam to the total caloric value (heat input) required for the joint welding of both edge surfaces depends on the type of powder, the welding current, the welding speed, the size of the tubular body, and the like. Decide. The above ratio is for example 10
It is about 90%. The welding current can be reduced by this ratio as compared with the joining of the edges using 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 not less than the amount of heat that does not cause cold junction cracking, and is desirably the amount of heat that does not generate spatter.

[0015] At the upstream side of the V convergence point of the two edge surfaces, the particle particles adhering to the edge surface are detected, and the laser beam is applied to the detected particle particles and the edge surface in the vicinity thereof. Is also good. In this case, the edge surfaces are joined by at least the welding current alone.

[0016]

The laser beam is applied to the edge surface near 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, thereby producing a large amount. Is instantaneously and locally supplied. As a result, the powder particles magnetically adhered to the edge surface are promoted to be melted by beam absorption, and the fluidity is improved. Therefore, the powder particles are discharged from the joint welding surface together with the molten metal by the electromagnetic force of a high-frequency current or the pressing force of a squeeze roll. You. Further, the welding current can be reduced by the amount of heating by the laser beam. Accordingly, the magnetic field in the tube is reduced, and the influence on the powder in the pipe becomes light, so that the number of the powder particles magnetically attached to the opening edge surface is reduced.

[0017]

EXAMPLES The production of a flux cored wire for welding will be described below as an example. FIG. 6 is a configuration diagram of a main part of a flux cored wire manufacturing apparatus for welding. 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.
Is arranged. A preforming roll (not shown) is provided upstream of the forming roll 2. The flux 20 is supplied from the space 5 between the side rolls 3 to the open pipe 1 being formed. 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.
0 is provided. A high frequency welding current is supplied from a power supply 12 to the work coil 9. In the welded pipe 11, the extra bead 14 on the outer surface side is cut by the cutting tool 13,
It is rolled by a rolling roll group 16 and further reduced in diameter to a product size of 1.0 to 2.0 mm in outer diameter by a rolling device and a wire drawing device (both not shown) while further annealing.
The extra bead 15 on the inner surface remains as it is to the product size.

With such high frequency induction welding, the width w = 3.
A steel strip having a thickness of _{0 to} 150 mm and a thickness of about 1.0 to 5.0 mm is formed into a pipe having an outer diameter D0 of about 10 to 50 mm. As the welding conditions at this time, the frequency of the high-frequency current f = 300 to 800 kHz
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
The pipe is formed 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 added to the high-frequency induction welding apparatus 8 in the wire manufacturing apparatus shown in FIG. That is, FIG. 1 shows a configuration diagram of a welding apparatus used in the present invention, and a laser beam irradiation means 1
Reference numeral 7 denotes a laser oscillator 18 for a YAG laser and an incident lens 1
9. It is composed of 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, which is the target position, or the edge surface near the upstream side. . The condensing 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. The smaller the irradiation angle θ, the more V
The area where the laser beam 24 directed to the convergence point 25 irradiates the edge surface 23 near the V convergence point 25 increases, so that the energy efficiency is improved. Therefore, it is desirable that the irradiation angle θ is small, for example, θ ≦ 30 °. The beam shape can be circular or rectangular.

FIG. 2 is a sectional view taken along the line II-II of FIG. 1 and shows a state of irradiation of the laser beam 24 onto the edge surface 23. Magnetic particles 26 existing on the surface of flux 20
Is attracted to the magnetized edge surface 23 to rise and magnetize. At this time, when the laser beam 24 irradiates the edge surface 23 near the V convergence point 25, the magnetic particles 26 magnetized on the edge surface are rapidly heated and melted instantaneously. That is, since the edge surface 23 is already heated by Joule heat by the high-frequency current and is in a semi-molten to molten state or in a state immediately before that, the magnetic particles 26 are irradiated with the laser beam 24 in addition to the heating by the heat conduction from the edge surface 23. As it receives it, it absorbs its energy and instantly reaches the melting temperature. Since the irradiation of the laser beam 24 is intended to melt the magnetically adhered particles on the edge surface 23 in addition to the heating by the Joule heat as described above, the laser beam 24 is so high that the edge surface is melted by the laser beam alone. No power is required, and it is not preferable because there is a risk that the edge surface is overheated and excavated, and that spatter is frequently caused. But,
Irradiation with a moderately low-power laser beam not only promotes the melting of the magnetic particles magnetically attached to the edge surface as described above, but also contributes to a rise in the temperature of the edge surface, so that the heat input of high-frequency welding (electric energy P) This has the ripple effect of reducing the burden.

FIG. 3 is a structural 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. FIG. 3 is a plan view showing a state of irradiation of a laser beam to the laser beam. The laser beam irradiation means 37 includes a laser oscillator 38 for CO ₂ laser, an optical system 39 for adjusting the beam shape, and a reflecting mirror 40. The laser beam output from the laser oscillator 38 is adjusted by an optical system 39 according to the opening edge surface for irradiating the cross-sectional shape, width (diameter), and the like of the beam. At an irradiation angle θ = 0 °. Laser beam 41
Is a rectangular shape having a cross section of L × 2L (L = edge thickness), for example. When the laser beam 41 advances straight through the gap along the opening edge surface and approaches the edge surface near the upstream side of the V convergence point 25, that is, the magnetic adhesion zone, and when both beam end portions 41e reach the edge surface, the beam converges from that position. The entire edge surface up to the point 25 is irradiated. In this case, as shown in the figure, the laser beam 41 repeatedly enters and reflects at each point on both edge surfaces, and eventually converges to the V convergence point 25. In other words, 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. Therefore, this embodiment can be said to be an embodiment suitable for the case where a CO ₂ laser having a high reflectance is used due to its wavelength characteristics (10.6 μm). In order to prevent a decrease in energy efficiency due to the reflection of the beam outside the sphere of the edge surface, it is desirable to make the groove shape of the edge surface as I-shaped (the edge surface is parallel) as possible.

After detecting magnetically attached particles on the edge surface by the search sensor, the edge surface near the upstream side of the V convergence point may be irradiated with a laser beam. An optical sensor such as a laser beam or an image sensor is used as the exploration sensor. FIG. 4 shows He- as an exploration sensor.
An example using a Ne laser beam will be described. The laser beam irradiation means 27 includes a laser oscillator 29,
Mirror 34 that totally reflects the laser beam from the laser beam and irradiates it along the edge surface 23,
It comprises 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 travels straight along the edge surface, and catches the magnetic particles 26 magnetically attached on the edge surface on the way, and reflects there.
A part of the reflected light goes backward, enters the semi-transmissive mirror 31, and after being reflected, enters the light receiver 32. The signal of “the presence of the magnetic particles 26” that is incident on the light receiver 32 and amplified is signal-processed by the controller 33 to operate the heating laser beam irradiation unit 17. Laser beam 2 output from laser oscillator 18
4 irradiates the edge surface 23 near the V convergence point 25 to melt the magnetic particles 26 captured by the laser beam 30.
The beam shape can be circular or rectangular. The installation position of the exploration laser beam irradiation device 27, that is, the irradiation position of the laser beam, the number and position of the light receiver, should be determined according to the shape of the magnetic particles magnetized on the edge surface and the frequency of the magnetism. Specifically, an experiment is repeatedly performed, and the determination is made based on the data.

FIG. 5 is a cross-sectional view of a tube showing still another example in which a search sensor is used, and detection of magnetically attached particles on an edge surface is performed for each edge surface.
In the drawing, the detection of the magnetically attached particles 26 on the right edge surface 23r is performed by an optical sensor 44 comprising a light projector 42r and a light receiver 43r.
The detection of the magnetized particles 26 on the left edge surface 23l is performed by an optical sensor 44l comprising a light emitter 42l and a light receiver 43l. Each optical sensor 44r, 44
The light projectors and light receivers of l are arranged inclined or perpendicular to the longitudinal direction of the tubular body 1 and the respective optical sensors 44r, 44r
The beams 45r and 45l from l are arranged so as not to interfere with each other. Each optical sensor 44r, 4
A pair of 4l may be provided, but if a plurality of pairs are provided in a staggered manner, it is effective to prevent detection leakage of magnetically attached particles.

Next, the results of cracking of the flux cored wire for welding manufactured by the above apparatus will be described.
Steel strip 2.2mm thick, 65.5mm wide (SPHC, C =
(0.05%) into a tube having an outer diameter of 22.4 mm and an inner diameter of 18.0 mm. During the molding, the flux was supplied at a filling rate of 15%, and the open tubes were continuously butt-joined. At this time, the frequency of the high-frequency current supplied to the work coil was 510 kHz.
z, welding speed V was 30 m / min, the distance from the work coil to the welding point was 25 mm, and the apex angle was 6 °. The tube after welding was annealed once by a rolling roll group to reduce the outer diameter to 3.2 mm, annealed, plated, and wound around a coil. Then, wire drawing was performed, and the diameter of the product wire was reduced to a product size of 1.2 mm in outer diameter and 0.6 mm in inner diameter, and the state of occurrence of cracks in the product wire was examined.

The welding speed V is 30 m / min and the tube thickness t is 2.
Assuming that the edge face is joined and welded only by the welding current, the 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 no large-sized spatters that cause disconnection are generated in the final finishing wire drawing process.

If high-frequency induction welding is performed with heat input within the appropriate heat input range, good welding can be performed as long as the edge surfaces of the butted tubular bodies 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 soar up and easily adhere to the edge surface, so that the state is not always clean. In the present invention, the edge surface near the upstream side of the V convergence point which is heated by the Joule heat of the high-frequency current and in a high temperature state is further heated by irradiating a laser beam. As a result, the powder particles magnetically adhered to the edge surface are instantaneously melted, and as a result, the fluidity is improved. As a result, the molten metal is well discharged from the weld joint surface by the electromagnetic force of the high-frequency current or the pressing force of the squeeze roll. 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 when the exploration sensor shown in FIG. 4 is used 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) Irradiation angle: 25 ° Irradiation time … 0.2 s (only when using a search laser beam) (search sensor) Type… He-Ne laser Wavelength… 0.633 μm Oscillation waveform… Continuous oscillation Beam diameter… 2.0 mmφ (parallel light beam) 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, no cold cracking will occur. In addition, heat input by welding current is reduced by 14
If it is 1 kVA or less, no spatter will occur.

In this embodiment, butt welding was performed at a heat input P of 110 kVA when the heating laser beam was used alone and at a heat input P of 135 kVA when the detection sensor was used together.

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

[Table 1]

Table 2 shows the results of crack generation. The evaluation of the cracks was carried out by conducting an eddy current flaw detection test of 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 wound spool x 37) after drawing to confirm the presence and position of the cracks.
When a crack signal was generated, the portion was observed with a magnifying glass to confirm the presence of a crack in the longitudinal direction of the wire.
When the presence of cracks could not be confirmed at all, this was regarded as good. In addition, when cracks are found in even one place, cracking tends to deteriorate the quality of the product due to the penetration of the treatment liquid into the wire during surface treatment or wire drawing from the opening of the crack. Made this a bad one.

[Table 2]

In Table 2, Experiment 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 in which is used in combination. In any of these experimental examples, no cracks were found in the tube sheath in any case, and the quality of the product wire was good. When welding was performed using the flux cored wire for welding, good welding workability was realized. .

On the other hand, Experiment Nos. 5 and 6 are comparative examples, in which the heating laser beam irradiation means was not used. Cracks were observed in the outer tube of each of Test Nos. 5 and 6, but cracks were remarkably observed in Test No. 6 using flux F2 containing iron powder and having a large amount of total Fe. . Eventually, in these comparative examples, the magnetic particles existing in the surface layer of the flux fluttered by the magnetic field and magnetically adhered to the edge of the tubular body. As a result, cracks occurred and the product yield was reduced.

[0033]

According to the present invention, the granular material is supplied to the tubular body in the course of forming the metal strip into the tubular body, and both edge surfaces of the tubular body are joined by high frequency welding to fill the granular body. In the method for manufacturing a powder-filled tube for reducing the diameter of a welded tube,
Since the laser beam is applied to the edge surface near the upstream side of the convergence point, the melting of the powder particles magnetically attached to the edge surface is promoted, and the fluidity is improved. As a result, the molten metal is well discharged from the joint welding surface by the electromagnetic force of the high-frequency current or the pressing force of the squeeze roll. Therefore, cracking of the tube due to the magnetic particles adhering to the edge surface of the open tube is substantially eliminated. In addition, the heat input burden due to the high-frequency current is reduced, and the heat input (electric power 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 magnetically attached to the opening edge surface is reduced. From these facts, it is possible to improve the product yield, and it is possible to obtain a high quality powder-filled tube.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an example of an apparatus for manufacturing a powder-filled tube according to the present invention.

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

FIG. 3 is a configuration diagram showing another example of an apparatus for manufacturing the powder-filled tube of the present invention.

FIG. 4 is an explanatory diagram showing a use state of a search sensor.

FIG. 5 is an explanatory diagram showing another usage state of the search 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]

 DESCRIPTION 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 irradiation means 18 laser oscillator 19 incident lens 20 flux 21 optical fiber cable 22 condenser lens 23 edge surface 24 laser beam 25 V convergence point 26 magnetic particles 27 laser beam irradiation means (sensor) for search 29 laser oscillator 30 laser Beam 31 Semi-transmissive mirror 32 Light receiver 33 Controller 34 Reflector 37 Heating laser beam irradiation means 38 Laser oscillator 39 Optical system 40 Reflector 41 Laser beam 42r, 42l Projector 43r, 43l Receiver 44r, 44l Optical sensor 5r, 45l light beam

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Nobuo Mizuhashi 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Corporation Technology Development Division (56) References JP-A-4-335309 (JP, A) Kaihei 6-238486 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B23K 35/40 C21C 7/04 H01B 13/00 H01B 12/04

Claims (2)

(57) [Claims] In the course of forming a metal strip into a tubular body, a granular material is supplied to the tubular body, both edges 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 tube having a large diameter, the edge surface near the upstream side of the V convergence point of the both edge surfaces is heated by a laser beam, and the powder particles attached to the edge surface are discharged from the edge surface. A method for producing a powder-filled tube characterized by the above-mentioned. 2. The method according to claim 1, further comprising the step of: detecting powder particles attached to the edge surface on the upstream side of the V convergence point of the both edge surfaces, and irradiating the laser beam to the detected powder particle particles and an edge surface in the vicinity thereof. Item 3. The method for producing a powder-filled tube according to Item 1.