JP3231440B2 - Manufacturing method of flux cored wire for welding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

This invention relates to carbon steel and stainless steel.
Welding flux- filled pipes filled with flux
The present invention relates to a method for manufacturing ears .

[0002]

2. Description of the Related Art Flux-cored seamless wires for welding
In the production of the steel strip, the strip is slit to a required width, and the strip after slitting 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.

[0003] High frequency welding such as high frequency induction welding and high frequency resistance welding has been widely used as a welding method in the production of flux cored wires for welding. 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.

[0004] When the diameter of a welded pipe filled with 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. Accordingly
Thus, the ferromagnetic component of the flux is attracted to the opening edge by the magnetic force. At this time, the weak 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.

One of the techniques for solving such a problem is a "composite wire for welding" disclosed in Japanese Patent Application Laid-Open No. 60-234794, in which a powder raw material having a non-magnetic permeability of 1.10. 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.

[0006]

However, even if the above-mentioned prior art is used to improve the weld joint, there is a limit in avoiding the adsorption of the flux particles to the opening edge surface. Cracks have occurred, which has led to 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.

[0007] Accordingly, the present invention provides a welding flux having no cracks in the tube shell by obtaining a sound joining weld.
It is intended to provide a wire .

[0008]

SUMMARY OF THE INVENTION A welding flash according to the present invention is provided.
The manufacturing method of the flux cored wire is to supply a flux to the tubular body in the course of forming the steel strip into a tubular body, join both edge surfaces of the tubular body by high frequency welding, and reduce the diameter of the welded pipe filled with the flux. In the method of manufacturing a flux-cored wire for welding, in the process of welding both edge surfaces after supplying the flux to the tubular body, disposing the flux near the opening of the tubular body.
Tube magnetized on the edge surface during high-frequency welding by the magnet
The method is characterized in that the powdery particles on the surface layer of the flux in the body are removed by magnetic attraction.

For high frequency welding, high frequency induction welding or high frequency resistance welding is used. A permanent magnet or an electromagnet is used for magnetically attracting the magnetically powdered particles.

In the present invention, the term "magnetic particles" refers to all particles having a possibility of magnetically adhering to the opening edge surface magnetized during high-frequency welding, and includes, of course, magnetic particles existing in the surface layer of the flux in the pipe. It also includes magnetic particles present on the inner wall surface of the tube and the opening edge surface. For example, the following are specifically mentioned. Due to the flux itself. For example, fine particles, Fe segregated particles, and coarse particles are powdered. Supply
Dissimilar particles (abrasion powder generated in the manufacturing process of a flux which is mixed in the flux, which heterologous powder or granular material or the like is mixed, the band
Strippings of steel strip generated during the steel forming process and dropped on the flux , and shavings and abrasion powder of forming rolls). Shavings on strip edges (generated during slitting or edge scarf). Generated in strip forming process, shavings of steel strip adhering to the strip surface. Wear powder from forming rolls (especially fin pass rolls and seam guide rolls). Magnetic particles soared by the oil smoke generated when a tubular body is heated during welding. Dust is deposited on forming rolls (especially fins of fin pass rolls) and magnetically adheres to the strip edge.

Flux supplied to the opening of the tubular body
Various raw material powders are selected according to the purpose of use, and are used as they are or granulated. For welding flux cored wire, rutile sand, magnesia clinker, etc. as slag generating agents, sodium silicate, potassium titanate, etc. as arc stabilizers, and low C as deoxidizing agents and alloying agents
-Fe-Si, Fe-Si-Mn, Al-Mg, etc. are used, and ferromagnetic components such as iron powder and iron oxide are used to improve the welding speed, adjust the flux filling rate, and improve the welding workability. May be blended. In any case, the flux to be charged contains at least 5 as a total Fe component.
% Or more and its particle size distribution is 32 mesh (0.
It usually contains at least 50% or more of fine particles of 5 mm) to Dust. In the case of granulation, in all flux particles, and in the case of non-granulation, iron alloy of raw material powder,
Particles such as iron powder and iron oxide contain Fe as a ferromagnetic component. 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. Therefore, not only when a ferromagnetic component such as iron powder or iron oxide is positively blended into the filling flux, but also when a flux is composed only of a so-called weak magnetic component, the flux is applied to the poled opening edge surface. There is a significant risk of particles being aspirated. 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 fine particles, the equilibrium particle size is raised. / Gravity] ratio is very dangerous.

Various measures have been taken to prevent flux particles from being adsorbed on the opening edge surface which has been poled so far.
0-234794, JP-A-63-5897, JP-A-Sho 54
-10940) has been proposed, but as described above, satisfactory results have not yet been obtained due to the characteristics of the flux itself, which is susceptible to magnetic fields.

According to the present invention, not only the flux in the tubular body, but also the above-mentioned magnetic particles present in the surface layer, as well as the shavings formed during the formation of the tubular body, the magnetic flux between the flux supply position and the welding position. The material is discharged out of the pipe by a drastic means of suction, and a clean open edge surface is supplied to the weld.

[0014]

The magnet is arranged at a predetermined distance from the surface of the flux layer in the tubular body. The pole face of the magnet is flat
When provided so as to face the flux layer surface, lines of magnetic force generated from the magnetic pole surface can easily penetrate the magnetic particles of the suction target, and the magnetic flux density on the flux layer surface is hardly attenuated, so that the magnetic particles can be efficiently magnetically attracted. . The strength of the magnet (surface magnetic flux density) and the gap distance between the pole face and the flux layer surface are determined by the magnetic flux density on the flux layer surface,
The [attraction force / gravity] ratio of magnetic particles determined by the magnetic susceptibility, particle mass, etc. of the particles exceeds 1, and the [attraction force / gravity] ratio of flux particles that does not magnetically adhere to the edge surface at the welding position is 1 or less. Is appropriately determined in accordance with the type of the supplied flux so as to have an appropriate value of.

[0015] Flack until fine particles present in the flux surface portion of the tubular body in this way, Fe content polarized析粒Ko, magnetic particles such as the dissimilar particles tubular body to reach the welding position
It is removed from the scan layer. Further, magnetic particles existing in the middle layer to the lower layer of the flux layer are shielded by the flux of the surface layer portion, so that there is no danger of magnetically attaching to the edge surface, and therefore there is no need to particularly consider it.

Further, shavings on the edge of the tubular body, which are inevitably generated during the roll forming process, are also removed in the same manner as the magnetic particles. Since shavings and the like attached to the edge surface may cause cracks in the weld and spatter,
It is better to remove it.

According to the present invention, it is possible to form a magnetic field on the edge surface at an appropriate position before the tubular body reaches the welding position by actively forming a magnetic field substantially equal to the magnetic field generated at the welding position. a certain magnetically attached powder granules of the tubular body was made based on the technical idea of removing in advance, thereby magnetically attracted powder or granular material of the tube due to magnetically attached to the edge surface of the tubular body No cracks.

[0018]

FIG . 1 is a structural view of a main part of a flux cored wire manufacturing apparatus for welding. As shown in FIG. 1, a forming roll group 2, side rolls 3, and a flux supply device 4 are arranged along a feed direction of an open pipe (tubular body) 1. 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. High frequency induction welding equipment 8
Has a work coil 9 and a squeeze roll 10. A high frequency welding current is supplied from a power supply 12 to the work coil 9. The welded pipe 11 has an extra bead 14 on the outer surface side cut by a cutting bit 13, is rolled by a roll roll group 16, and is further annealed by a rolling device and a wire drawing device (both not shown) while performing annealing. .0
Reduced to 2.0 mm product size. 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 diameter 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 welding conditions at this time, the frequency of the high-frequency current f = 300 to 800 kHz Heat input (electric energy) P = 50 to 400 KVA Distance between work coil and welding point l = 5 to 60 mm Apex angle (V convergence angle) θ = 3 to A welding speed (pipe-forming speed) of about 10 ° is used.
The pipe is formed at a speed of about 200 m / min.

The manufacturing apparatus for carrying out the method of the present invention is the same as the above-described wire manufacturing apparatus, except that the surface layer portion 21 of the flux 20 in the open pipe 1 is provided between the flux supply device 4 and the high-frequency induction welding device 8. A means for magnetically attracting existing magnetic particles or shavings attached to the edge surface 17 of the open tube 1 is provided.

This will be described with reference to FIGS. 1 and 2 (a sectional view taken along line II-II in FIG. 1) and FIG. 3 (a sectional view taken along line III-III in FIG. 1). The first magnetic suction means 18 is provided immediately after the flux supply device 4, and the second magnetic suction means 19 is provided between the fin pass roll 6 and the seam guide roll 7.

As shown in FIGS. 1 and 2, the first magnetic attraction means 18 includes a permanent magnet 30 and a support 31. The permanent magnet 30 has one magnetic pole surface 30f (N pole) directed vertically downward. The open tube 1 is inserted into the inside through the gap between the opening edge surfaces 17a and 17b, and is suspended by the support 31 with the other magnetic pole surface (S-pole) out of the tube. Pole faces 30f (N pole) are opposed at air gap distance l ₁ between the flux surface 20f. This gap distance l
₁ is set so that the magnetic flux density on the flux surface 20f becomes an appropriate size capable of attracting magnetic particles existing on the flux surface layer portion 21. The magnetic pole face 30f (N pole) and the magnetic pole face (S pole) are located slightly away from the opening edge faces 17a and 17b, and the support 31 is made of a non-magnetic material (such as brass) so that the edge face is not magnetized as much as possible. We are careful about. In this way, the magnetic lines of force generated from the magnetic pole surface 30f (N pole) cover the flux surface 20f in a short distance and efficiently attract the magnetic particles existing in the flux surface layer portion 21. The magnetically attracted magnetic particles 22 rise along the lines of magnetic force and accumulate (26) on the magnetic pole surface 30f (N pole).

As shown in FIGS. 1 and 3, the second magnetic attraction means 19 also comprises a permanent magnet 32 and a non-magnetic support 33, like the first magnetic attraction means 18. The permanent magnet 32 is outside the tube and has its pole face 32f (N
Towards the poles) vertically downward, it is opposed by opening the air gap distance l ₂ between the opening edge surface 17a, 17b. The gap distance l ₂ is set so that the magnetic flux density at the opening edge surface has an appropriate size to attract the magnetic particles 23, shavings, and the like at this position. The magnetically attracted magnetic particles 23 rise along the lines of magnetic force and deposit on the magnetic pole surface 32f (N pole) (27). The magnetic particles deposited (26, 27) on the pole faces 30f, 32f are removed intermittently or continuously. In this embodiment, the magnetic attraction means has the simplest form for supporting a rectangular permanent magnet, but the present invention is not limited to this. For example: A permanent magnet is formed in a circular shape, and the magnetically attracted particles and the removal from the magnetic pole surface are simultaneously performed while rotating the permanent magnet.・ A rotating belt made of a non-magnetic material is provided around the permanent magnet, or a rotating belt made of a magnet is used, and magnetically attached flux is magnetically attracted in the tube and removed from the rotating belt outside the tube. As shown by the dotted line in FIG. 2, iron plates 35 for magnetic shielding are attached to both sides of the permanent magnet 30, and the opening edge surface 17a,
The magnetization of 17b may be suppressed. -Use an electromagnet (attraction force can be easily adjusted). Various modifications are conceivable.

Further, the installation position of the magnetic attraction means is not limited to this embodiment, but can be appropriately changed according to the situation. For example, it may be installed before and after the work coil.
In this case, not only the outside possibly tubular body, Flack
A rod-shaped magnet may be inserted along the tubular body into the space between the layer and the tubular body opening. Further, hula magnetic attraction means
It may be provided on the upstream side of the box supply position. In this case, shavings during band forming are removed in advance.

Next, the results of cracking of the flux cored wire for welding manufactured by the above apparatus will be described.
Steel strip 2.2 mm thick and 65.5 mm wide (SPHC, C =
0.05%) was formed 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 filled at a filling rate of 12%, and the open tubes were continuously butt-joined. At this time, the frequency of the high-frequency current supplied to the work coil was 480 kHz.
z, heat input is 150KVA, welding speed V is 30m / min, work coil to welding point distance is 25mm, apex angle is 7 °
Met. The welded pipe having an outer diameter of 22.4 mm was subjected to annealing once on the way by a group of rolling rolls to reduce the outer diameter to 3.2 mm, subjected to annealing and plating, 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.

If high-frequency induction welding is performed under the above-mentioned welding conditions, good welding can be performed as long as the open edge surfaces of the butted open pipes are clean. However, in this welding, a strong magnetic field is generated at the welding position, so that the magnetic particles in the flux soar and easily adhere to the edge surface, and thus are not necessarily in a clean state. In the present invention, the magnetic particles in the flux which may be magnetically attached to the edge surface before the open pipe reaches the welding position are removed by magnetic attraction. In this embodiment, FIG.
This was performed by the magnetic attraction means shown in FIGS. The permanent magnets 30 and 32 used are the same and have a rectangular shape, a size of 40 × 25 × 10 mm, a pole face of 40 × 10 mm, and a surface magnetic flux density of 1500 Gauss. Permanent magnet 30 with a predetermined gap distance l ₁ between the pole face 30f of the flux surface of the tube, also the permanent magnet 32 is the pole face 32f is opened edge surface 17a, a predetermined gap distance l between 17a ₂ is suspended and supported.

Table 1 shows the supplied flux. After mixing the raw material powders, a fixing agent (water glass) was added, granulated, and classified to prepare fluxes F ₁ and F ₂ .

[0028]

[Table 1]

Table 2 shows the results of crack generation. For the evaluation of the cracks, the eddy current test (ECT) of the wire skin was performed over the entire length of 100 km of the product wire with 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.

[0030]

[Table 2]

In Table 2, Experiment No. Experiment Nos. 1 to 4 are experimental examples of the present invention. Experiment Nos. 1 and 2 are examples in which only the first magnetic attraction means was used. Reference numerals 3 and 4 denote examples using the first and second magnetic attraction means. In each case, no cracks were found in the tube sheath, and good results were obtained. Experiment No. 2 in which the second magnetic attraction means was not used. In Experiments Nos. 1 and 2, Experiment No. 2 using the second magnetic attraction means together. Slight spatter generation was observed as compared with Nos. 3 and 4. Experiment No. 3 and 4, second
Shavings attached to the edge by the magnetic attraction means
Sparks before both edges contact due to magnetic attraction
Did not occur. For this reason, no spatter was observed.
won. After all, in these experimental examples, flux particles,
As a result of the clean edge surface without shavings being used for welding, there is no cracking, the quality is good as a product wire, and welding was performed using this flux cored wire for welding. The nature was able to be realized.

On the other hand, in Experiment No. Reference numerals 5 and 6 are comparative examples in which the magnetic attraction means of the present invention is not used. Experiment No. Although cracks in the tube outer shell were confirmed in all of Examples 5 and 6, experiments using flux F ₂ containing iron powder
o. In No. 6, the occurrence of cracks in the outer skin was remarkably observed. Eventually, in these comparative examples, the magnetic particles on the surface layer of the flux soared up by the magnetic field and were adsorbed on the edge of the tubular body, and as a result, cracks occurred and the product yield was reduced.

[0033]

According to the present invention, in the process of supplying the flux to the tubular body as described above and welding the two edge surfaces, the magnetically attracted particles on the surface layer of the flux in the tubular body are magnetically attracted. Therefore, the tubular body having a clean edge surface can be always subjected to high frequency welding. Therefore, the magnetic
Cracking tubes wear powder or granular material is caused to magnetically attached to the edge surface of the tubular body substantially eliminated. As a result, it is possible to improve the product yield, and furthermore, it is possible to improve the quality of the welding flash.
A wire with a core can be obtained.

[Brief description of the drawings]

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

FIG. 2 shows a first magnetic attraction means, which is shown in FIG.
It is a line sectional view.

FIG. 3 shows a second magnetic attraction means.
FIG. 3 is a sectional view taken along line III.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Open pipe 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 tube 12 Power supply 16 Rolling roll group 17 Opening edge surface 18 First Magnetic attraction means 19 Second magnetic attraction means 20 Flux 20f Flux surface 21 Flux surface layer 30 Permanent magnet 31 Permanent magnet pole face 32 Permanent magnet 33 Permanent magnet pole face

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Seiji Hashimoto 3-5-4 Tsukiji, Chuo-ku, Tokyo Nippon Steel Welding Industry Co., Ltd. (56) References JP-A-5-305489 (JP, A) JP-A-60-234792 (JP, A) JP-A-4-55088 (JP, A) JP-A-60-234795 (JP, A) JP-A-60-39346 (JP, U) Int.Cl. ⁷ , DB name) B23K 35/40 B03C 1/02 B21C 37/06

Claims (2)

(57) [Claims] 1. A method of forming a steel strip into a tubular body while forming it into a tubular body.
A method for producing a flux-cored wire for welding in which a flux is supplied and both edge surfaces of a tubular body are joined by high-frequency welding to reduce the diameter of a welded tube filled with the flux , wherein both edges are supplied after the flux is supplied to the tubular body. Weld face
In the process , the magnet placed near the opening of the tubular body
Of the inside of the tubular body magnetically attached to the edge surface during high-frequency welding.
A method for producing a flux-cored wire for welding , characterized by magnetically attracting and removing powder particles on a surface layer portion of a flux . 2. The method according to claim 1, further comprising magnetically attracting and removing the magnetically attached particles at and near the edge surface of the tubular body .
Manufacturing method of flux cored wire for welding .