JPH06238486A - Production of powder and granular material filled pipe - Google Patents

Abstract

PURPOSE:To provide a manufacture for production of the powder and granular material filled pipe which is free from cracking in a pipe sheath by obtaining a defectless joined weld zone. CONSTITUTION:This manufacturing method for the powder and granular material filled pipe consists in supplying the powder and granular material into a tubular body in the process of molding a metallic strip to the tubular body and joining both edge surfaces of the tubular body by high-frequency welding and diametrally reducing the welded pipe filled with the powder and granular material. While the edge surfaces near the upstream side at a V converging point are irradiated with a laser beam, these edge surfaces are high-frequency welded at the heat input quantity over the permissible lower limit heat input quantity PELN which is the max. heat input quantity to generate cold crack and below the permissible upper limit heat input quantity PEUN which is the min. heat input quantity to generate spatters of grain sizes above the inside diameter of the final finished pipe.

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 granular material refers to a granular material such as a welding flux, an oxide superconducting material, and an additive for molten steel.

[0002]

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, flux is supplied from the opening along the longitudinal direction of the U-shaped strip steel to the valley portion of the strip steel 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 to obtain a product.

High frequency welding such as high frequency induction welding and high frequency resistance welding is widely used as a welding method in the manufacture of the above-mentioned powder-filled tube. 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.

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 opening edge of the tubular body becomes a magnetic pole due to the magnetic field generated by the welding current. 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.

[0006]

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.

[0007] 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.

[0008]

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. Recognizing this, we diligently studied measures to prevent this. As a result, if the strength of the magnetic field generated in the tubular body is reduced, it becomes possible to reduce or avoid the magnetic sticking of the granular particles to the edge part, and the magnetic particles stick to the edge surface. In this case, it was confirmed that it is possible to squeeze out into and out of the pipe almost completely when it is melted. It has been found that it is difficult to achieve this by the single heating method of heating the edge portion only with the high frequency current, and it is necessary to add new heating means. The present invention was 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 during the forming of the metal strip into the tubular body, and both edge surfaces of the tubular body are joined by high frequency welding, In a method for manufacturing a powder-filled tube for reducing the diameter of a welded tube filled with powder, the edge surface near the upstream side of the V convergence point is irradiated with a laser beam to heat the edge surface, cold welding cracking Is characterized by performing high-frequency welding with a heat input amount that exceeds the allowable lower limit heat input amount, which is the maximum heat input amount, and that is less than the allowable upper limit heat input amount, which is the minimum heat input amount that generates spatter with a particle size equal to or larger than the final finish tube inner diameter. .

Further, it is characterized in that high-frequency welding is performed with a heat input amount less than the minimum heat input amount at which sputtering is observed.

Further, the present invention is characterized in that high-frequency welding is performed with a heat input amount less than the welding heat input at which powder particles in the tubular body soar due to the magnetic field generated in the pipe by the high-frequency welding current.

In the present invention, the edge surface near the upstream side of the V convergence point includes an edge surface through which a high frequency current flows, and has a possibility of magnetically attracting the magnetic particles in the granular material by the magnetic field generated by the high frequency welding. The entire edge surface. The irradiation position and range of the laser beam in the edge plane are the positions and ranges where it is judged that the effects of the present invention are most exerted, and this is determined according to each case.

In the present invention, the heat input amount is the heat input amount P _E = EpIp (kVA) as the output of the high frequency welding machine. The allowable lower limit heat input amount, the allowable upper limit heat input amount, and the minimum heat input amount at which sputtering is observed can be experimentally obtained. As an example, in the case of forming a steel strip into a small-diameter steel pipe having an outer diameter of 10 to 50 mm and a wall thickness of about 1 to 5 mm by only high-frequency welding, the results of experimentally obtaining the heat input amounts will be described. The appropriate heat input amount changes depending on the welding speed V, the plate thickness t, and the like. FIG. 1 shows the range of appropriate heat input with the welding speed V (m / min) as a variable. In FIG. 1, a region I below the curve P _EL indicates a region where cold weld cracking occurs. Curve P _EL Approximately P _EL = 4.70 V ^0.6
Expressed as t ^1.6 . A region III above the line P _EU indicates a region where spatter having a diameter equal to or larger than the inner diameter of the final finishing tube is generated. In a range in which the welding speed V is equal to or lower than the limit welding speed V _o (the welding speed at the point O where the curve P _EL and the straight line P _EM intersect), the line P _EU is approximately P _EU = 4.70 V ^0.6 t ^1.6 (=
It is expressed as P _EL ) + 2.97V ^0.6 t ^0.6 . Further, in the range where the welding speed V exceeds the limit welding speed V _o , the line P _EU
Is approximately P _EU = 0.97Vt ² (= P _EM ) +0.61
It becomes a straight line represented by Vt. A region II sandwiched between the curve P _EL and the line P _EU is a region in which cold welding cracking and spatter having a diameter equal to or larger than the inner diameter of the final finished pipe, that is, so-called large-scale spatter that frequently causes disconnection during wire drawing do not occur. Also the straight line P _EM
Represents the minimum heat input for which sputtering is observed, and is approximately P _EM = 0.97 Vt ² . A region IIa sandwiched between the curve P _EL and the straight line P _EM is a spatterless region in which cold welding cracking and sputtering are not observed. It is preferable to weld in this spatterless region IIa. The limit welding speed V _o is the limit speed at which this region IIa disappears. The higher the welding speed, the higher the productivity, but it is limited by the supply speed of the granular material to the tubular body, the capacity of the pipe forming equipment and the subsequent rolling equipment, and the like. On the other hand, the smaller the amount of heat input is, the more energy is saved. However, it is desirable to select with a margin within the above appropriate range because of fluctuations in the power supply voltage and other pipe making conditions.

In the present invention, in addition to the heating of the edge portion by the high frequency current, the laser beam is irradiated toward the edge surface in the vicinity of the upstream side of the V convergence point. Therefore, the edge surface is also irradiated by the irradiation of the laser beam. As a result, the laser beam input P _L bears a part of the heat input P that is required when the high frequency welding is carried out independently. That is, P = P _E + f (P _L ) where P ... Required heat input for high-frequency welding P _E ... Heat input due to high-frequency current P _L ... Laser beam input f (P _L ) ... Laser beam input P _L Heat input When the heat input load due to high-frequency welding is reduced by f (P _L ), the magnetic field inside the tubular body decreases accordingly. The magnetic field in the tubular body generated by this high-frequency current causes powder particles to adhere to the edge surface, so the above-mentioned requirements are required as far as possible without impairing the advantage of high-frequency welding that high productivity is possible. It is preferable to replace the heat input amount P with the heat input amount f (P _L ) from the laser beam.
For example, it is desirable to reduce the heat input amount P _E due to the high-frequency current until the heat input amount is less than the minimum heat input amount P _{EF at} which the powder particles in the tubular body float up by this heat input replacement. The minimum heat input amount P _EF is determined by the magnetic susceptibility factors (susceptibility, content of ferromagnetic component, mass, particle size, etc.) of the granular material supplied into the tubular body, the gap distance between the edge surface and the granular material surface, Specifically, it is determined by experiment for each individual case.

[0015] limit line in FIG. 1 the proper region of the heat input P _E by the high-frequency current when a combination of laser beams P _EUN, P
_EMN, indicated by P _ELN (each limit line P _EU, P _EM, thin lines correspond to the P _EL), also indicating the point O O _N points, the limit welding speed V _O at V _ON. As is apparent from this, the O point (V _o , P _o ) moves diagonally to the lower left (origin direction) with the irradiation of the laser beam, and the O _N point (V _o −ΔV, P _o).
−ΔP). The movement amount of the point O, that is, the P-axis and V-axis direction components ΔP and ΔV of ((ΔP) ² + (ΔV) ² ) ^1/2 are appropriately obtained by experiments according to individual cases.

On the other hand, for the powder or granular material supplied to the opening of the tubular body, various raw material powders are selected according to the purpose of use of the powder or granular material filling tube, and used as they are or after being granulated. . For example, for flux-cored wires for welding, rutile sand, magnesia clinker, etc. as slag generator, sodium silicate, potassium titanate, etc. as arc stabilizer, low C-Fe-Si, Fe-Si-M as deoxidizer / alloying agent.
n, Al-Mg, etc. are used, and ferromagnetic components such as iron powder and iron oxide improve the welding speed, adjust the flux filling rate,
It may be added to improve welding workability. In any case, the total Fe is contained in the flux to be filled.
It is customary to contain at least 5% or more as a component, and to have a particle size distribution of at least 50% or more of a fine particle group of 32 mesh (0.5 mm) to Dust. In the case of granulating, all the flux particles contain Fe, and in the case of non-granulating, the Fe component of the ferromagnetic component is contained in the particles of the raw material powder such as iron alloy, iron powder and iron oxide. 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. Therefore, 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, the flux is formed on the opening edge surface of the magnetic pole. There is a full risk of particle adsorption. 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 is increased, which is extremely dangerous.

Up to now, various measures have been taken to prevent magnetic flux particles from being magnetically attached to the opening edge surface that has been made into a magnetic pole (Japanese Patent Laid-Open Publication No. Sho 6-62).
0-234794, JP-A-63-5897, JP-A-54.
However, the actual situation is that satisfactory results have not yet been obtained due to the characteristic of the flux itself that it is susceptible to the magnetic field as described above.

By the way, the flux particles magnetically attached to the opening edge surface contain various components such as Ti, Si, Zr, Mn, Mg and Al in addition to Fe as constituent components. Near the V convergence point where the flux particles are magnetically attached (about 6
Instantaneous (within 0.5 mm) within the edge surface of 0 mm)
Flux particles such as Ti, Si, Zr, Mn, M
It is difficult to melt g, 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 the melting point of these components and the steel that is the material of the pipe, the specific heat,
It is considered to be based on differences in heat of fusion, thermal conductivity, etc. For example, Ti (melting point: 1675 ° C.), Zr (melting point: 1852)
(.Degree. C.), the melting point is higher than that of steel (1535.degree. C.), so that it is difficult to melt.

In the present invention, since the laser beam is applied to the edge surface near the upstream side of the V convergence point, for example, in the high frequency induction welding, the edge surface before and after the V convergence point to the work coil is irradiated with the laser beam. In addition, the flux particles are melted and the fluidity is improved. As a result, the flux particles on the edge surface are satisfactorily discharged from the welded surface together with the molten metal due to the electromagnetic force of the high frequency current or the pressure contact force of the squeeze roll.

[0020]

When the high-frequency current flowing in the work coil is increased to increase the heat input P _E as the output of the high-frequency welding machine, the magnetic field is increased accordingly, so that the influence on the powder particles supplied to the pipe is also stronger. As a result, sputtering is likely to occur.

In the present invention, since the laser beam is applied to the edge surface near the upstream side of the V convergence point, the edge surface is heated. Due to this external heat input, the heat input load due to the high frequency current is reduced, and the heat input amount P _E can be reduced. As a result, the magnetic field in the tube decreases, the influence on the particles in the tube becomes light, and the number of particles of the particles that magnetically adhere to the opening edge surface decreases. Also, the minimum heat input amount P _{EF in which} powder particles in the tubular body are soared by the magnetic field generated in the pipe by the high-frequency welding current due to the heat exchange by the irradiation of the laser beam.
It is also possible to reduce the heat input amount P _E due to the high-frequency current until the heat input amount becomes less than less, and in this case, there is no powdery or granular particles magnetically attached to the opening edge surface.

According to the present invention, the edge surface near the upstream side of the V-converging point 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 is irradiated with the laser beam to instantly. Provides a large amount of heat locally. As a result, the powder particles that are magnetically adhered to the edge surface are melted by beam absorption and the flowability is improved. Will be.

In this way, in the present invention, the cracking of the tube due to the magnetic particles being magnetically attached to the edge surface of the tubular body is eliminated. Further, stable spatterless welding can be realized in a relatively low heat input (low power amount) region.

[0024]

EXAMPLES The manufacturing of flux-cored wires for welding will be described below as examples. FIG. 2 is a configuration diagram of a main part of the welding flux-cored wire manufacturing apparatus. As shown in FIG. 2, 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.

With 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 D0 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 _E = 50 to 500 KV
A Distance between work coil and welding point L = 10 to 100 mm Apex angle (V convergence angle) θ = 3 to 15 ° is adopted, welding speed (pipe forming 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. 3 is a block diagram of the welding apparatus used in the present invention, in which the laser beam irradiation means 1 is used.
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 at the target position or the edge surface near the upstream side thereof. . The condenser lens 22 is arranged above the opening edge surface 23 and irradiates the laser beam 24 toward the target position with 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. 4 is a sectional view taken along the line IV-IV in FIG. 3, showing the irradiation state of the laser beam 24 on the edge surface 23. The magnetic particles 26 existing on the surface layer of the flux 20 are attracted to the magnetized edge surface 23 and rise to be magnetized.
At this time, when the laser beam 24 irradiates the edge surface 23 near the V convergence point 25, the magnetic particles 2 magnetically attached to the edge surface
6 is heated rapidly and melts instantly. That is, the edge surface 23
Is already heated by Joule heat due to 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 being heated by heat conduction from the edge surface 23, and therefore the energy To reach the melting temperature instantly. As described above, the irradiation of the laser beam not only contributes to the heat input load of the high frequency welding, but also has a ripple effect of promoting melting of the magnetic particles magnetically attached to the edge surface.

FIG. 5 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.

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 (t) of 2.2 mm and a width (w) of 65.5 mm (SP
HC, C = 0.05%), outer diameter 22.4 mm, inner diameter 1
Mold into 8.0 mm tube. 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 was 510 kHz, the welding speed (V) was 30 m / min, the work coil-welding point distance was 25 mm, and the 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 appropriate heat input range of the high frequency welding at this time will be described separately for the case of the high frequency welding alone (conventional) and the case of using the laser beam irradiation means (the present invention). In case of high frequency welding alone (conventional) Since the limit welding speed V _o = 51.8 t ⁻¹ = 23.5 m / min (<V = 30 m / min), the position of point _O ... V _o = 23.5 m / min, P _O = 110 k
The lower and upper limits of VA proper heat input are: lower limit P _EL = 4.70 V ^0.6 t ^1.6 V = 128 kVA (point a in FIG. 1) upper limit P _EU = 0.97 Vt ² +0.61 Vt = 181 k
VA (point c in FIG. 1), that is, the appropriate heat input P _E is P _E = 128 to 181 kVA (β region in FIG. 1). Also, P _EM = 0.97Vt ² = 141kVA (point b in FIG. 1)
Therefore, in this case, cold weld cracking and sputtering were not observed in the heat input range (spatterless region: IIa width = 13 kVA) of P _{EL to} P _EM = 128 to 141 kVA (γ region in FIG. 1), and P _EM ~
Sputtering is observed in the heat input range of P _EU = 141 to 181 kVA (α region in FIG. 1), 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 within this proper heat input range, good welding can be carried out as long as the abutting edge surfaces 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 easily attach to the edge surface, so that it is not always in a clean state. Therefore, it is difficult to obtain a joint weld having no defects.

When Laser Beam Irradiating Means is Used in Combination (Invention) In this embodiment, the laser beam irradiating means shown in FIG. 3 was used. The irradiation conditions are as follows. (Laser beam irradiation conditions) Type: YAG laser wavelength: 1.06 μm Oscillation waveform: Pulse oscillation pulse width: 1 power (average): 0.8 kW Beam diameter: 2.2 mmφ (V convergence point position) Irradiation angle: 25 ° (Appropriate heat input range of high frequency welding) Inventive Example 1 As described above, the irradiation of this laser beam moves the point O shown in FIG. 1 to the point O _N. V axis in this case, P-axis direction of the moving weight component [Delta] V, [Delta] P is, ΔV = 2 m / min, ΔP = 30 kVA O position of _N points _{... V ON = 21.5 m / min} , P ON = 80 k
VA At this time, new limit lines P _ELN , P _EMN , and P _EUN are approximately expressed by the following equations, respectively. P _ELN = 3.61V ^0.6 t ^1.6 P _EMN = 0.77V t ² P _EUN = 3.61V ^0.6 t ^1.6 (= P _ELN ) ... (V <V _ON ) + 2.86V ^0.6 t ^0.6 P _EUN = 0.77Vt ² (= P _EMN ) +0.61 Vt (V ≧ V _ON ) Further, the limit welding speed V _ON is the limit welding speed V _ON = V _o −2 = 21.5 m / min (<V =
30 m / min), the lower and upper limits of the proper heat input when V = 30 m / min are the lower limit P _ELN = 98 kVA and the upper limit P _EUN = 152 kVA, that is, the proper heat input P _E is P _E = It becomes 98-152 kVA. Since P _EMN = 112 kVA, cold weld cracking and sputtering are not observed in the heat input range (sputterless region) of P _{ELN to} P _EMN = 98 to 112 kVA, and P _{EMN to} P _EUN = 112 to
In the heat input range of 152 kVA, spattering is observed, but large-scale spattering that causes wire breakage does not occur in the final finish drawing process. Comparing this with the case of high frequency welding alone, the allowable lower limit of heat input, which is the maximum heat input that causes cold welding cracking, is P _EL = 128 kVA to P _ELN = 9.
It can be seen that it has been reduced to 8 kVA.

As described above, according to 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 is in the high temperature state is irradiated with the laser beam for further heating. This enables high-frequency welding with a relatively low heat input, so that the magnetic field in the tube can be reduced, and as a result, the rising of magnetic particles is suppressed. When magnetic powder particles are magnetically adhered to the edge surface, the powder particles are instantly melted and as a result, the fluidity is improved, so the electromagnetic force of high frequency current or the pressure contact force of the squeeze roll together with the molten metal It will be discharged well from the welded surface.

When the leakage of the irradiation of the laser beam to the granular particles magnetically adhered to the edge surface is concerned, the magnetic field generated in the tube by the high-frequency welding current due to the heat input displacement by the irradiation of the laser beam causes the inside of the tubular body. It is also possible to lower the heat input amount P _E due to the high-frequency current until the heat input amount is less than the minimum heat input amount P _{EF at which the} powder particles are soared. As described above, this minimum heat input amount P _EF is the magnetic susceptibility factor (susceptibility, ferromagnetic component content, mass, particle size, etc.) of the powder particles supplied into the tubular body, and the gap between the edge surface and the powder particle surface. P _EF = 87 kVA as a result of an experiment in this example in which the above-mentioned tubular body is supplied and filled with the following flux depending on the distance and the like. The laser beam irradiation power (average) in this case is 1.6 kW, and the appropriate heat input range for high-frequency welding is as follows.

(Appropriate heat input range for high-frequency welding) Inventive Example 2 Point O shown in FIG. 1 moves to point O _N due to laser beam irradiation. In this case, the movement amount component ΔV in the V axis and P axis directions,
[Delta] P is, ΔV = 5 m / min, ΔP = 60 kVA O position of _N points _{... V ON = 18.6 m / min} , P ON = 50 k
VA At this time, new limit lines P _ELN , P _EMN and P _EUN (shown by thin lines in FIG. 1) are approximately represented by the following equations. P _ELN = 2.48V ^0.6 t ^1.6 P _EMN = 0.56V t ² P _EUN = 2.48V ^0.6 t ^1.6 (= P _ELN ) ... (V <V _ON ) + 2.69V ^0.6 t ^0.6 P _EUN = 0.56Vt ² (= P _EMN ) +0.61 Vt (V ≧ V _ON ) Further, the limit welding speed V _ON is the limit welding speed V _ON = V _o −5 = 18.6 m / min (<V =
30 m / min), the lower and upper limits of proper heat input when V = 30 m / min are: Lower limit P _ELN = 67 kVA (point a _{N in} FIG. 1) Upper limit P _EUN = 122 kVA (c in FIG. 1) _N point) That is, the proper heat input P _E is P _E = 67 to 122 kVA (β _N range in FIG. 1). Further, since P _EMN = 81 kVA (point b _{N in} FIG. 1), in this case P _{ELN to} P _EMN = 67 to 81 kVA (γ _N region in FIG. 1), the heat input range (spatterless region) causes cold welding cracking and No sputtering was observed, P _EMN ~ P _EUN = 81 ~ 1
Sputtering is observed in the heat input range of 22 kVA (α _N range in FIG. 1), but large-scale spattering that causes wire breakage does not occur in the final finish drawing process. Comparing this with the case of the above high frequency welding alone, the allowable lower limit heat input which is the maximum heat input causing cold welding cracks is P _EL = 128 kVA
It can be seen from the above that P _ELN = 67 kVA.

In this embodiment, the heat input amount P _E of high frequency welding is as follows: When high frequency welding is used alone (conventional example) Heat input amount P _E = 135 kVA When laser beam irradiation means is used together (example of the present invention) Irradiation power: 0. Butt welding was performed with a heat input P _E = 105 kVA at 8 kW and a heat input P _E = 75 kVA at 1.6 kW. Table 1 shows the composition of the supplied flux. After mixing the raw material powders, a binder (water glass) was added, granulated, and classified to prepare a flux.

[Table 1]

The results of cracking are shown in Table 2. The crack was evaluated by conducting an eddy current flaw detection test (ECT) on the wire sheath over the entire length of 100 km of the product wire having an outer diameter of 1.2 mmφ after wire drawing (20 kg winding spool × 37) to confirm the presence and position of the crack, 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, Experiment Nos. 1 and 2 are experimental examples of the present invention using the laser beam irradiating means. In these experimental examples, cracking of the tube outer skin was not confirmed, and the quality as a product wire was good. When welding was performed using this flux-cored wire for welding, good welding workability was realized.

On the other hand, Experiment No. 3 is a conventional example and does not use the laser beam irradiation means. In this conventional example, as a result of the magnetic particles existing in the flux surface layer rising up by the magnetic field and magnetically adhering to the edge portion of the tubular body, cracks occurred and the product yield was reduced.

[0040]

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
While irradiating the edge surface near the upstream side of the convergence point with the laser beam, the minimum heat input that exceeds the allowable lower limit heat input that is the maximum heat input that causes cold welding cracks and that spatter with a particle size that is equal to or larger than the final finish pipe inner diameter Since high-frequency welding is performed with a heat input amount that is less than the allowable upper limit heat input amount, which is the heat amount, the heat input load due to the high-frequency current is reduced, and the heat input amount (power amount) P _E can be reduced. As a result, the magnetic field in the tube is reduced, the influence on the powder in the tube is reduced, and the number of powder particles magnetically attached to the opening edge surface is reduced.

When magnetic powder particles are magnetically adhered to the edge surface, melting of the magnetic powder particles adhering 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.

As a result, the product yield can be improved and a powder-filled tube of good quality can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a range of an appropriate heat input amount (electric power amount) of high frequency welding with a welding speed as a variable.

FIG. 2 is a configuration diagram of a main part of an apparatus for manufacturing a flux-cored wire for welding.

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

FIG. 4 is a sectional view taken along line IV-IV in FIG. 3 showing a laser beam irradiation state on the edge surface.

FIG. 5 is a configuration diagram showing another example of a device for producing the powder-particles filling tube of the present invention.

[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 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 37 Laser beam irradiation means for heating 38 Laser oscillator 39 Optical system 40 Reflection Mirror 41 laser beam

Front Page Continuation (72) Inventor Nobuo Mizuhashi 20-1 Shintomi, Futtsu City, Chiba Nippon Steel Co., Ltd. Technology Development Division

Claims (3)

[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 a method of manufacturing a powder-filled granular tube having a diameter, while irradiating a laser beam to an edge surface near the upstream side of a V convergence point, a maximum heat input amount that causes cold welding cracking exceeds an allowable lower limit heat input amount and final finish A method of manufacturing a powder-filled tube, characterized in that high-frequency welding is performed with a heat input amount less than an allowable upper limit heat input amount, which is a minimum heat input amount for generating spatter having a particle size equal to or larger than a pipe inner diameter. 2. The method for producing a powder / granular filled tube according to claim 1, wherein the high frequency welding is performed with a heat input amount less than the minimum heat input amount at which sputtering is observed. 3. The method for producing a powder-granule-filled pipe according to claim 1, wherein the powder-granule-filled pipe is subjected to high-frequency welding with a heat input amount less than the minimum heat input amount at which powder particles in the tubular body are soared by a magnetic field generated in the pipe by the high-frequency welding current.