JPH06106384A - Production of powder and granular material packed pipe - Google Patents

Abstract

PURPOSE:To prevent the soaring up of powder and granular materials by supply ing the powder and granular materials apart a specified space distance between the surface of the upper layer of the powder and granular material and a joined weld zone at the time of joining and welding a powder and granular material packed pipe. CONSTITUTION:The influential power of the magnetic field generated by a heat input quantity P is decreased to a substantially negligible level by regulating the magnetization rate Xg of the powder and granular materials to Xg<=(2.00+246<-0.89>).10<-4> [emu/g] in correspondence to the heat input P [kva] of high-frequency welding at the time of forming a small-diameter pipe of 10-50mm outside diameter and 1 to 5mm thickness by high-frequency welding. Further, the particle mass m of the powder and granular materials is unified to the range expressed by m>=1.8X10<-5>.P<1.8> [mg] with the heat input P as a variable. Further, the crack of the pipe occurring in the adsorption of the powder and granular materials on the edge part of the pipe is substantially eliminated by setting the space distance L between the surface in the upper layer of the powder and granular materials and the joined weld zone 5 of the pipe at L>=5 [mm].

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, 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 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 they are formed into a substantially O shape, the edge surfaces of the openings are heated to a melting temperature by a high frequency current, and the opposing edge surfaces are pressed against each other by 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, a part of the flux such as oxide or silicate adheres to 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. Therefore, the ferromagnetic component of the flux is attracted to the opening edge portion by the magnetic force. At this time, the nonmagnetic component is also attached to the opening edge portion along with the ferromagnetic component. The flux adhering to these opening edge portions serves as inclusions in the joint welding portion and causes 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.

As one of the techniques for solving such a problem, there is a "method for producing a filler wire" in Japanese Patent Laid-Open No. 60-234792, in which a non-magnetic material is layered on an upper layer and a magnetic material or a ferrite material is layered on a lower layer. To prevent the ferromagnetic material or the ferrite-based material from being adsorbed to the opening edge portion by the upper non-magnetic material layer. JP-A-60-234
There is a "composite wire for welding" disclosed in Japanese Patent No. 794, which is filled with substantially non-magnetic powder of a powder raw material having a non-permeability of 1.10 or less, and the powder is attracted to the opening edge portion by magnetic force. Prevent from doing. Also, there is a "composite pipe manufacturing method" disclosed in Japanese Patent Laid-Open No. 63-5897, in which fine powder finer than 48 mesh is removed at the time of powder feeding, and fine powder is prevented from adhering to the opening edge portion. To prevent. Furthermore, in the "method for producing a powder-containing wire" disclosed in Japanese Patent Laid-Open No. 3-207598, a substantially non-magnetic raw material powder is granulated to prevent it from soaring to an opening edge portion due to a ferromagnetic component. To do. Another technique is disclosed in Japanese Patent Laid-Open No. 54-109.
There is a "method for manufacturing a tube filled with powder" disclosed in Japanese Patent Laid-Open No. 040. 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 method for producing a powder-filled tube having no cracks on the tube shell by obtaining a sound welded joint.

[0008]

DISCLOSURE OF THE INVENTION The inventors reconfirmed that the cracks when the diameter of the pipe is reduced are welding defects caused by the magnetic attraction of powder particles at the opening edge of the open pipe during welding. . In order to prevent the adsorption of the powder or granules, it was clarified that the vague treatment such as simply granulating the powder to increase the size or supplying only the substantially non-magnetic raw material powder was ineffective. . Going one step further, paying attention to the magnetic characteristics and particle mass of the granular material, especially the upper layer granular material facing the opening edge of the tube, and if these are regulated granular materials, move to the edge of the granular material. It was found that the soaring of the fish was suppressed. The present invention was made based on these findings.

According to the method of manufacturing a powder-filled tube of the present invention, the powder is supplied to the tubular body while the metal plate is being formed into a tubular body, both edges of the tubular body are joined by high frequency welding, and In a method of manufacturing a powder-filled tube for reducing the diameter of a welded tube filled with a body, magnetic attraction to the tubular body edge surface of the powder is prevented,
The magnetic susceptibility and particle mass of the granular material are obtained based on the heat input for welding, and the upper layer of the granular material to be supplied into the tubular body is formed by the determined granular material, and the upper layer surface of the granular material is welded to the weld. The powder and granules are supplied with a predetermined gap distance between them.

In addition, in the method for manufacturing a powder-filled tube, it is desirable that the magnetic susceptibility χ _g , the particle mass m, and the void distance L are set to values within the following ranges. χ _g ≤ (2.00 + 246P ^-0.89 ) ・ 10 ^-4 [emu /
g] P: welding heat input [kVA], m ≧ 1.8 × 10 ⁻⁵ · P ^1.8 [mg], L ≧ 5 [mm] That is, in the present invention, joining of the powder particles to the pipe is joined. the magnetic susceptibility chi _g of the overlying granular material facing the weld corresponding to heat input P of a high-frequency welding (i.e. E _P I _P [kVA]) kept at a low level as described above, the the particle mass As described above, a predetermined level or more is provided, and a predetermined gap distance is provided between the surface of the granular material layer and the welded joint. As a result, the effect of the magnetic field generated by the heat input P on the powder particles becomes substantially negligible.

In the present invention, the magnetic susceptibility χ _g is the magnetic susceptibility per unit mass of the granular material, the mass of the granular material is a [g], the magnetic moment is μ [G · cm ³ ] and the external magnetic field is H [Oe (=
G)], the magnetic susceptibility χ _g is

[Equation 1] It is represented by. Here, [cm ³ · g ⁻¹ ] is expressed as [emu / g] according to the convention.

In the present invention, the heat input amount P is the heat input amount E _P I _P (kVA) as the output of the welding machine, and the appropriate heat input amount varies depending on the welding speed V, the plate thickness t and the like. FIG. 3 shows the range of the appropriate heat input amount with the welding speed V (m / min) as a variable. In FIG. 3, a region I below the curve P _L indicates a region where cold weld cracking occurs. The curve P _L is approximately P
_It is expressed as _L = 4.70 V ^0.6 t ^1.6 . A region III above the line P _U shows a region where spatter having a diameter equal to or larger than the inner diameter of the final finishing tube is generated. In the range where the welding speed V is equal to or lower than the limit welding speed V ₀ (the welding speed at the point O where the curve P _L and the straight line P _M intersect), the line P _U is approximately P _U = 4.7.
It represented as _{^{0t 1.6 V 0.6 (= P L}} ) + 2.97t 0.6 V 0.6. In the range where the welding speed V exceeds the limit welding speed V ₀ , the line P _U is approximately P _U = 0.97t ² V (=
It becomes a straight line represented by P _M ) +0.75 tV. Curve P _L
The region II sandwiched by the line P _U and the line P _U is a region in which cold welding cracks and spatter having a diameter equal to or larger than the inner diameter of the final finishing tube, that is, so-called large-scale spatter that frequently causes disconnection during wire drawing do not occur. Further, the straight line P _M represents the minimum heat input amount at which sputtering is observed, and approximately P _M = 0.97t ² V
Is. A region IIa sandwiched between the curve P _L and the straight line P _M is a region where cold welding cracking and sputtering are not observed. The limit welding speed V ₀ is the limit speed at which this region IIa disappears.

The higher the welding speed is, the higher the productivity is, but it is limited by the feed rate of the powder or granular material to the tubular body, the capacity of the pipe forming equipment and the following rolling equipment, and the like. on the other hand,
The smaller the amount of heat input, the more energy can be saved. However, it is desirable to select with a margin within the appropriate range because of fluctuations in power supply voltage and other pipe making conditions.

On the other hand, as the powder or granular material supplied to the opening of the open tube, various raw material powders are selected according to the purpose of use of the powder or granular material filling tube, and are used as they are or after being granulated. . For example, for flux-cored wires for welding, rutile sand, magnesia clinker, etc. as slag generators, sodium silicate, potassium titanate, etc. as arc stabilizers, low C-Fe-Si, Fe-S as deoxidizers / alloying agents.
Weak magnetic components such as i-Mn and Al-Mg are used. In addition, a ferromagnetic component such as iron powder or iron oxide may be blended to improve the welding speed, adjust the flux filling rate, and improve the welding workability. As described above, at the welding position of the open pipe, the opening edge portion of the open pipe becomes a magnetic pole due to the magnetic field generated by the welding current. Therefore, the ferromagnetic component may be attracted to the opening edge portion by the magnetic force.
Therefore, in the past, it has been attempted to select only a substantially non-magnetic raw material, excluding ferromagnetic components such as iron powder and iron oxide, and supply it as it is or after granulating it to an open tube ( JP-A-60-234794, JP-A-3-20
7598). However, although these treatments are effective in preventing cracks to some extent, they have not been completely solved, and still satisfactory results have not been obtained. The reason is that the magnetic field generated by the heat input P (P _L <P <P _U ) of the high-frequency welding is a stronger magnetic field than expected, and is less than what is called non-magnetic, that is, with respect to the granular material having a relative magnetic permeability of 1.10 or less. However, there is a risk of exerting influence and leading to the opening edge portion.

In the present invention, the magnetic susceptibility χ _g and the particle mass m of the powder or granular material which prevent the powder or granular material from being magnetically attached to the edge surface of the tubular body are determined based on the welding heat input P. That is, the magnetic susceptibility of the granular material χ _g
Is regulated below a predetermined level determined by the welding heat input P,
In addition, the particle mass m is regulated to a predetermined level or higher, which is also determined by the welding heat input P, and the powder and granular material layer is provided with a predetermined gap distance from the joint welding portion of the tubular body. To form the upper layer. As a result, soaring of the granular material to the edge surface of the tubular body is suppressed. It should be noted that an appropriate range based on the welding heat input P of the above-mentioned physical properties (susceptibility χ _g , particle mass m) of the granular material, which prevents magnetic attraction of the granular material to the edge surface of the tubular body, is actually manufactured. It is determined according to the diameter of the powder-filled pipe (the diameter of the pipe at the time of welding and joining).

Hereinafter, as a preferable example, the above-mentioned proper range in the case of producing a small diameter pipe having an outer diameter of 10 to 50 mm and a wall thickness of 1 to 5 mm by high frequency welding will be described. In this case, the present inventors associate the magnetic susceptibility χ _g of the granular material with the heat input P [kVA] of high-frequency welding to obtain χ _g ≤ (2.00 + 246P ^-0.89 ) · 10 ^-4 [emu /
g], the heat input amount P (P _L <P <in combination with the later-described mass regulation of powder particles and regulation of the void distance.
The experimental results have revealed that the influence of the magnetic field generated by P _U ) can be substantially ignored. The magnetic susceptibility of the granular material is VS
It was determined by the M (vibrating sample magnetometer) method as follows.

First, the saturation magnetic moment μ _s = 1.
A small piece of Ni foil of 198 [G · cm ³ ] is used as a reference sample, and this is measured at ± 10 kOe and calibrated. Next, with an external magnetic field H = ± 100 [Oe], the sample (mass a
Measure the magnetic moment of [g]) and average the absolute values. This magnetic moment is μ [G · cm ³ ]. Magnetization σ per unit mass is σ = μ / a [G · cm ³ · g
⁻¹ ], and the desired magnetic susceptibility χ _g = σ / H [cm ³ · g ^-1 ]
(= [Emu / g]) is obtained.

FIG. 1 shows the range of the allowable magnetic susceptibility with the heat input P as a variable. In the figure, the safety area upper region represents a danger area where the cracks adversely affect the quality produced and the region of lower substantially crack does not occur in the curve chi _{g ma x} (upper limit of the allowable magnetic susceptibility) Shows. As is clear from the figure, the higher the heat input P, the lower the upper limit χ _{g max} of the allowable magnetic susceptibility. This is because the higher the heat input P, the more the current that flows in the tube skin and the opening edge, and the stronger the magnetic field generated in the tube. As a result, the powder in the tube is easily magnetized,
This is because it is necessary to reduce the magnetic susceptibility of the granular material to counter this.

The lower the lower limit of the magnetic susceptibility χ _g is, the more desirable it is.
There is no particular limitation. However, it goes without saying that since the raw material powder used has the magnetic susceptibility unique to that powder, | χ _g |> 0.

Limiting the magnetic susceptibility χ _g of the granular material in accordance with the heat input P in this way is a very effective means for cracking the tube, but the mass of the granular material is further It has been confirmed that it is more effective against the occurrence of cracks in combination with the suppression of the magnetic susceptibility by increasing the value so as to counteract the influence from the outside. Specifically, the particle mass m of the powdery or granular material is set to a range represented by m ≧ 1.8 × 10 ⁻⁵ · P ^1.8 [mg] with the heat input P as a variable. At this time, the content of the powder or granular material in the region of m <1.8 × 10 ⁻⁵ · P ^{1.8 which} is unavoidably mixed is set to 5 wt% or less. Fig. 2 shows the lower mass curve m
_min = 1.8 × 10 ⁻⁵ · P ^1.8 is shown. This curve m _min
The region on the upper side of is a zero defect region in which no cracking is observed. As can be seen, the lower limit mass m _{mi n} is heat input P
The higher is the larger. This shows that it is effective to increase the particle mass by the amount corresponding to the strengthening of the magnetic field as the heat input P increases.

As a means for obtaining a powder or granular material having a desired particle mass range, for example, a method of granulating a raw material powder and classifying it is adopted. The raw material powder may be granulated by a known method such as a tumbling granulation method, an extrusion granulation method, and a compression granulation method, and classification may be performed by a known method such as a sieving method. For example, a raw material powder is metered and mixed at a predetermined mixing ratio, an aqueous solution of sodium silicate or potassium silicate as a fixing agent is added alone or as a mixture, and the mixture is wet mixed. It is granulated, dried, and classified by a sieving method to obtain one having a predetermined particle size range, that is, a mass range.

The upper limit of the particle mass m of the granular material is not particularly limited. However, the particle size d is d ≦ 10D ₁ final finish tube inner diameter of the (product wire) to the D _1, preferably d ≦ 5D ₁
It is good to say The reason for this is that due to the large size of the particles, uneven filling occurs in the lengthwise direction of the pipe when the diameter of the pipe is reduced, and at the stage of finishing wire drawing (diameter reduction), an uneven thickness phenomenon occurs in the pipe outer skin, which causes wire breakage. Is. Therefore, it is desirable to set the mass corresponding to the upper limit of the particle size d as the upper limit of the particle mass m.

Further, in the present invention, the granular material forming the upper layer of the granular material layer in which the physical characteristics of the particles (magnetic susceptibility χ _g , particle mass m) are regulated as described above serves as a magnetic pole, and the opening of the tube becomes the magnetic pole. Set a safety area so that it will not stick to the edge. That is, for the granular material in which the magnetic susceptibility χ _g and the particle mass m of the granular material are regulated as described above, the gap distance L between the upper surface of the granular material and the pipe-welded portion is L ≧ 5. By setting the distance expressed in [mm], it is possible to place the upper granular material in the magnetically safe area.

[0024]

When the high-frequency current flowing in the work coil is increased to increase the heat input P as the output of the welding machine, the magnetic field is increased accordingly, and the influence on the powder particles supplied to the pipe is also stronger. Become.

In the present invention, in consideration of the heat input P, the upper limit of the magnetic susceptibility χ _g of the granular material is further limited in the so-called weak magnetic region, and the mass of the particles is increased, so that the mass effect of the particles is positively influenced. To use. When the upper layer of the granular material layer is formed with a predetermined gap distance L between the pipe and the welded portion by the granular material having such physical properties, the weak magnetic susceptibility, the mass effect of the particles, and the magnetic field due to the distance. As a result of the synergistic effect of the three damping effects, the particles in the upper layer of the particle layer facing the opening edge of the tube move out of the range of influence of the magnetic field, and as a result, they do not move up. Further, as a result of the powder particles in the lower layer overlapping with the powder particles in the upper layer, it is possible to withstand the influence of the magnetic field and not move up. Therefore, the granular material forming the lower layer is not particularly limited, and granulated / non-granulated or magnetic / non-magnetic granular material can be appropriately used.

The thickness of the upper layer required to exert such an effect is sufficient as long as it covers the entire surface of the granular layer with the granular material satisfying the conditions specified by the present invention. Is.

As described above, according to the present invention, the cracking of the pipe caused by the adsorption of the powder or granular material on the edge portion of the pipe is substantially eliminated.

[0028]

EXAMPLES The manufacturing of flux-cored wires for welding will be described below as examples. FIG. 4 is a configuration diagram of a main part of the welding flux-cored wire manufacturing apparatus.

As shown in FIG. 4, the forming roll group 2, the side rolls 3 and the flux supply devices 41 and 42 are arranged along the feeding direction of the open pipe 1. A preforming roll (not shown) is provided on the upstream side of the forming roll 2. First, the flux F _U forming the lower layer is supplied from the flux supply device 41 into the open pipe 1 in the course of molding, and subsequently the flux F _O forming the upper layer is supplied from the flux supply device 42. The open pipe 1 supplied with the fluxes F _U and F _O 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 10. A high frequency welding current is supplied to the work coil 9 from a power source 12. The welded pipe 11 is cut by a cutting tool 13 to form an extra bead 1 on the outer surface side.
4 is cut, rolled by a group of rolling rolls 15, and further annealed while being reduced to a product size of 1.0 to 2.0 mm in outer diameter by a rolling device and a wire drawing device (neither is shown).

FIG. 5 is a cross-sectional view showing the inside of the pipe 1 between the work coil 9 and the squeeze roll 10. A predetermined gap distance L is provided between the surface 16 of the upper layer flux F _O and the pipe joint weld 5. ing.

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 Distance between work coil and welding point 1 = 5 to 60 mm Apex angle (V convergence angle) θ = 3 to 10 °, welding speed (pipe forming speed) V = 10
Pipe forming is performed at a speed of about 200 m / min.

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%) was molded into a tube having an outer diameter of 22.4 mm and an inner diameter of 18.0 mm. Filling rate of flux is 10 to 15 during molding
% (Void distance L> 5.0 mm at this time), and open tubes were continuously butt-joined. At this time, the frequency of the high frequency current supplied to the work coil was 540 kHz, the welding speed V was 30 m / min, and the work coil-welding point distance was 2
It was 5 mm and the apex angle was 7 °. Welded outer diameter 2
A 2.4 mm tube was annealed once with a group of rolling rolls to reduce its outer diameter to 3.2 mm, annealed, plated, and wound into a coil. Next, finish wire drawing and pipe outer diameter 1.2
mm, the inner diameter was reduced to 0.6 mm, and the occurrence of cracks in the product wire was examined.

When the range of the appropriate heat input in this case is calculated, V =
Assuming 30 m / min and t = 2.2 mm, the limit welding speed V ₀ = 51.8 t ⁻¹ = 23.5 m / min (<V = 30 m / min). Therefore, the lower limit of proper heat input P _L = 4.70 t ^1.6 V ^0.6 = 128 kVA (point a in FIG. 3) Upper limit P _U = 0.97 t ² V + 0.61 tV = 181 kVA (point c in FIG. 3) That is, the proper heat input is P = 128 to 181 kVA (β region in FIG. 3) ). Further, P _M = 0.97t ² V = 141 kVA (see FIG.
Therefore, in this case, cold welding cracking and sputtering are not observed in the heat input range of P _{L to} P _M = 128 to 141 kVA. Further, P _{M to} P _U = 141 to 181 kVA (Fig. 3
Sputtering is observed in the heat input range of (α region), 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 by heat input within 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 mentioned above, a strong magnetic field is generated in this welding, and the magnetic powder and fine powder in the powder supplied to the tubular body easily rise up due to the turbulence of the air in the pipe, etc. The edge surface of the tubular body to be treated is not necessarily in a clean state because it may be contaminated from the stage of the raw steel strip or during forming, so when pressing the edge surface in a molten state heated by the work coil with a squeeze roll. , It is necessary to discharge this dirt to the inside and outside of the pipe (squeeze out). In this case, the higher the heating temperature of the edge surface, the more easily the dirt adhering to the edge surface tends to be discharged. Therefore, the heat input P is P _M or more, that is, P = P _{M to} P _U = 141 to 181 kVA ( (Α region in FIG. 3) is desirable. In this embodiment, the butt welding was performed with the heat input P = 160 kVA.

Magnetic susceptibility χ _{g of the} used flux raw material powder
Is shown in Table 1. Granulated by mixing raw material powders of Table 1, or mixed with non-granulated remains the prepared various flux F ₁ to F ₁₂ as shown in Table 2. For granulation, a stock solution of 3 mol sodium silicate and 3 mol potassium silicate diluted and mixed with water is used as a sticking agent. The granulated product was granulated with a granulator, and the dried product was classified by a sieving method to obtain a product having a predetermined mass.

Here, the allowable magnetic susceptibility χ _g of the flux when the welding heat input P = 160 kVA is χ _g ≦ (2.00 + 246P ^−0.89 ) · 10 ⁻⁴ = 4.6
It is 9 × 10 ⁻⁴ [emu / g]. To adjust the magnetic susceptibility χ _g of the granulation flux, χ _g >
4.69 × 10 ^-4 cm by increasing or decreasing the proportion of f ₇ ferromanganese and f ₁₀ iron powder which is a raw material powder of [emu / g], or were performed by the no-containing. As for the magnetic susceptibility χ _g of the non-granulated flux, the maximum magnetic susceptibility of each raw material powder was taken as the magnetic susceptibility of the flux.

The allowable range of the particle mass m in this case is m ≧ 1.8 × 10 ⁻⁵ · P ^1.8 = 0.17 [mg].

[0038]

[Table 1]

[0039]

[Table 2]

The various fluxes F _{1 to} F ₁₂ shown in Table 2 were combined and supplied into the pipe to produce a flux-cored wire for welding. The experimental results are shown in Table 3.

[0041]

[Table 3]

The cracks were 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 determine the presence and position of cracks. It was carried out by observing and checking the presence of cracks in the wire longitudinal direction by observing the relevant part with a magnifying glass when a cracking signal was output. 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.

In Table 3, Experiment Nos. 1 to 8 are experimental examples of the present invention, and the magnetic susceptibility χ _{g of the} flux forming the upper layer is
Is 4.69 × 10 ⁻⁴ emu / g or less, and the particle mass m is 0.17.
Satisfies the condition of more than mg. Experiment No. 1 (F ₃ + F ₁ ) ... Granulation flux F ₃ (χ
Both _g and m are in the proper range), and the lower layer is granulation flux F
₁ (χ _g : improper range, m: proper range) was supplied. In the single layer of flux F _1, F ₁ particles having a high magnetic susceptibility χ _g containing iron powder f ₁₀ of 5.5% are soared by the magnetic field. In this case, the upper layer flux F ₃ shields and suppresses this. Although the flux F ₃ also contains the ferromagnetic iron powder f ₁₀ , it is a small amount of 1.3%, and since it is granulated, the magnetic susceptibility χ _g is low and the particle mass m is large.
As a result, both the magnetic susceptibility χ _g and the particle mass m are in proper ranges. Experiment No. 2 (F ₃ + F ₂ ) ... Granulation flux F ₃ (χ
Both _g and m are in the proper range), and the lower layer is granulation flux F
₂ (χ _g : proper range, m: partial proper range) were supplied.
In the flux F ₂ single layer, the particle mass m is small and
F ₂ particles soar up due to the magnetic field. In this case, the upper layer flux F ₂ shields and suppresses this. Experiment No. 3 (F ₃ + F ₈ ) ... Granulation flux F ₃ (χ
Both _g and m are in the proper range), and the lower layer is a non-granulating flux F ₈
(Χ _g : proper range, m: improper range) were supplied. The flux F ₈ single layer has a small particle mass m and is a light fine particle (dust) layer, so the F ₈ particles are soared by the magnetic field. In this case, the upper layer flux F ₃ shields and suppresses this. Experiment No. 4 (F ₄ + F ₄ ) ... Magnetic susceptibility χ _{g for} both upper and lower layers,
Granulation flux F in which all of particle mass m are within the proper range
Supplied ₄ . Therefore, the stacking state of the flux is not affected by the magnetic field. In this case, since the fluxes forming the upper layer and the lower layer are the same, the layer is substantially a single layer. Experiment No. 5 (F ₄ + F ₅ ) ... Granulation flux F ₄ (χ
_g, m are both appropriate range), granulated flux F ₄ and a small granulated flux F ₅ particle mass m in the same component composition in the lower layer
(Χ _g : proper range, m: improper range) were supplied. In the flux F ₅ single layer, light F ₅ particles are soared by the magnetic field. In this case, the upper layer flux F ₄ shields and suppresses this. Experiment No. 6 (F ₄ + F ₉ ), No. 7 (F ₆ + F ₁₀ ) ... Granulation flux F ₄ and F ₆ (appropriate range for both χ _g and m) in the upper layer, non-granulation flux F in the lower layer ₉ , F ₁₀ (χ _g : Partially inappropriate range,
m: improper range) was supplied. Non-granulated flux F ₉ , F
_{In 10} monolayers, ferromanganese f ₇ and iron powder f ₁₀ with high magnetic susceptibility χ _{g in} the flux are soared by the magnetic field. In this case, the upper fluxes F ₄ and F ₆ shield and suppress this. Experiment No.8 (F ₁₁ + F ₁₂ ) ... Non-granulating flux F in the upper layer
₁₁ (χ _g , m: proper range), and non-granulated flux F ₁₂ (χ _g : partially unsuitable range, m: unsuitable range) was supplied to the lower layer. In the non-granulated flux F ₁₂ single layer, ferro-manganese powder f ₇ and iron powder f ₁₀ in the flux rise up by the magnetic field. In this case, the upper flux F _11, that is, the rutile particle layer, shields and suppresses this.

As is clear from these experimental examples, the flux for forming the upper layer is not limited to the granulated flux, but the raw material powder or granular material may be used as it is. In other words, granulation is a means of increasing the mass by increasing the grain size, averaging the magnetic susceptibility, etc., so if it is a raw material powder having an appropriate magnetic susceptibility and particle mass, this can be used as the upper layer flux. Is. In addition, in these experimental examples, there was no occurrence of cracks due to flux particles flying up and adsorbing to the pipe edge portion, and the quality as a product wire was good. When welding was performed using this welding flux-cored wire, good welding workability was realized.

On the other hand, Experiment Nos. 9 to 15 are comparative examples, and none of the upper layer fluxes satisfy the conditions specified by the present invention. Experiment No. 9 (F ₅ + F ₄ ), No. 10 (F ₁ + F ₆ ), No. 12 (F ₂
+ F ₃ )… Supply granulation fluxes F ₅ , F ₁ , and F ₂ whose magnetic susceptibility χ _g or particle mass m is in an unsuitable range to the upper layer, and have appropriate magnetic susceptibility χ _g and particle mass m to the lower layer. Granulation fluxes in the range F ₄ , F ₆ , F _{3 were} supplied. In this case, the upper flux F ₅ , F ₁ , F ₂ particles are soared by the magnetic field. Experiment No. 11 (F ₇ + F ₁ ) ... The granulation flux F ₇ (χ _g : proper range, m: improper range) with a small particle mass m was supplied to the upper layer, and the lower layer had a high magnetic susceptibility χ _g . Grain flux F
₁ (χ _g : improper range, m: proper range) was supplied. In this case, since the flux F ₇ particles in the upper layer are light, the F ₁ particles having a high magnetic susceptibility χ _g containing 5.5% of the iron powder f ₁₀ in the lower layer are shielded from being soared by the magnetic field and suppressed. I can't. Experiment No. 13 (F ₅ + F ₅ ), No. 14 (F ₈ + F ₈ ), No. 15 (F ₁₀
+ F ₁₀ ) ... Granulated flux F ₅ , non-granulated fluxes F ₈ and F ₁₀ having inappropriate magnetic susceptibility χ _g or particle mass m were supplied to both upper and lower layers. The fluxes forming the upper layer and the lower layer are the same. In this case, the upper layer flux
Ferrosilicon powder f ₆ , ferromanganese powder f ₇ , and iron powder f _{10 in} F ₅ particles or non-granulated fluxes F ₈ and F ₁₀ rise up by the magnetic field.

In these comparative examples, the flux soaked up by the magnetic field and was adsorbed to the edge portion of the tubular body, and as a result, cracking occurred and the product yield was lowered.

[0047]

According to the present invention, the magnetic susceptibility of the granular material forming the upper layer portion of the granular material supplied into the pipe as described above is limited to a predetermined value determined by the welding heat input P or less, and the particle mass is reduced. Is also limited to a predetermined value or more determined by the welding heat input P, and a predetermined gap distance is set between the upper layer surface and the welded joint, so that the powder particles are substantially unaffected by the magnetic field generated by the high frequency welding. The body can be fed into the tube. Therefore, the cracking of the tube due to the magnetic particles magnetically adhering to the edge surface of the open tube is substantially eliminated. Further, if the particle mass of the granular material is limited to a predetermined value determined by welding heat input or more, it becomes possible to contain about several percent of ferromagnetic powder in the raw material powder. Of course, such component particles that are easily affected by the magnetic field may be supplied into the pipe as a constituent element of the lower layer of the granular material as it is, so that the range of component design of the granular material is wide, which is advantageous. . As a result, 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 diagram showing an allowable range of a magnetic susceptibility of a granular material with welding heat input as a variable.

FIG. 2 is a diagram showing an allowable range of particle mass of a powder or granular material with welding heat input as a variable.

FIG. 3 is a diagram showing a range of an appropriate heat input amount with a welding speed as a variable.

FIG. 4 is a diagram showing an example of an apparatus for producing the powder / particle filling tube of the present invention, and is a configuration diagram of a main part of an apparatus for producing a flux-cored wire for welding.

5 is an enlarged cross-sectional view showing the inside of the pipe between the work coil and the squeeze roll in the apparatus shown in FIG.

[Explanation of symbols]

1 Open Pipe 9 Work Coil 2 Forming Roll Group 10 Squeeze Roll 3 Side Roll 11 Welded Pipe 41, 42 Flux Supply Device 12 Power Supply 5 Joined Welding Part 15 Rolling Roll Group 6 Fin Pass Roll 16 Flux Upper Layer Surface 7 Seam Guide Roll F _U Lower layer flux 8 High frequency welding equipment F _O Upper layer flux

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] May 20, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

In the present invention, the heat input amount P is the heat input amount E _P I _P (kVA) as the output of the welding machine, and the appropriate heat input amount varies depending on the welding speed V, the plate thickness t and the like. FIG. 3 shows the range of the appropriate heat input amount with the welding speed V (m / min) as a variable. In FIG. 3, a region I below the curve P _L indicates a region where cold weld cracking occurs. The curve P _L is approximately P
_It is expressed as _L = 4.70 V ^0.6 t ^1.6 . A region III above the line P _U shows a region where spatter having a diameter equal to or larger than the inner diameter of the final finishing tube is generated. In the range where the welding speed V is equal to or lower than the limit welding speed V ₀ (the welding speed at the point O where the curve P _L and the straight line P _M intersect), the line P _U is approximately P _U = 4.7.
It represented as _{^{0t 1.6 V 0.6 (= P L}} ) + 2.97t 0.6 V 0.6. In the range where the welding speed V exceeds the limit welding speed V ₀ , the line P _U is approximately P _U = 0.97t ² V (=
It becomes a straight line represented by P _M ) +0.61 tV . Curve P _L
The region II sandwiched by the line P _U and the line P _U is a region in which cold welding cracks and spatter having a diameter equal to or larger than the inner diameter of the final finishing tube, that is, so-called large-scale spatter that frequently causes disconnection during wire drawing do not occur. Further, the straight line P _M represents the minimum heat input amount at which sputtering is observed, and approximately P _M = 0.97t ² V
Is. A region IIa sandwiched between the curve P _L and the straight line P _M is a region where cold welding cracking and sputtering are not observed. The limit welding speed V ₀ is the limit speed at which this region IIa disappears.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0036

[Correction method] Change

[Correction content]

Here, the allowable magnetic susceptibility χ _g of the flux when the welding heat input P = 160 kVA is χ _g ≦ (2.00 + 246P ^−0.89 ) · 10 ⁻⁴ = 4.6
It is 9 × 10 ⁻⁴ [emu / g]. To adjust the magnetic susceptibility χ _g of the granulation flux, χ _g >
The test was performed by increasing or decreasing the content ratio of 4.69 × 10 ⁻⁴ [emu / g] of raw material powder, f ₇ ferromanganese and f ₁₀ iron powder, or by not containing them. As for the magnetic susceptibility χ _g of the non-granulated flux, the maximum magnetic susceptibility of each raw material powder was taken as the magnetic susceptibility of the flux.

Continued Front Page (72) Haruji Hashimoto, Inventor 3-5-4 Tsukiji, Chuo-ku, Tokyo Nittetsu Welding Industry Co., Ltd.

Claims (2)

[Claims] 1. A powdery or granular material is supplied to the tubular body during the forming of a metal plate into a tubular body, both edges of the tubular body are joined by high frequency welding, and the diameter of the welded pipe filled with the granular material is reduced. In the method of manufacturing a powder-filled tube, to prevent magnetic sticking to the tubular body edge surface of the powder, the magnetic susceptibility and particle mass of the powder is determined based on the welding heat input, by the powder obtained Powder particles that form an upper layer of the powder particles to be supplied into the tubular body, and that supply the powder particles with a predetermined gap distance between the upper layer surface of the powder particles and the joining weld portion. Body filling tube manufacturing method. 2. The magnetic susceptibility χ _g is such that χ _g ≦ (2.00 + 246P ^−0.89 ) · 10 ⁻⁴ [emu /
g] P: welding heat input [kVA], the particle mass m is m ≧ 1.8 × 10 ⁻⁵ · P ^1.8 [mg], and the void distance L is L ≧ 5 [mm]. For manufacturing a powder-filled tube of the above.