JPH11333591A - Flux cored wire for welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flux cored wire in which grooves where lots of lubricants are remained are narrow, the thickness of a joint part is uniform, the localization and straightness of an arc are excellent and defects such as a blow hole, the rolling of slag and the meandering of a bead don't generate. SOLUTION: The shape and dimension of cross-section of a joint part of a flux cored wire for welding satisfy the following relations: 5 deg.<=α<=70 deg., 0.85<=t1 /t2 <=1.15 and 0.1t2 <=ω<=1.4t2 , where; α: an angle formed between a jointing line on the cross section of the joint part and a tangent of the wire surface, t1 : the maximum thickness of the cross section of the joint part, t2 : the minimum thickness of the cross section other than the joint part and ω: the length of an inclined jointing line on the section of the jointing part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welded flux-cored wire among welding wires.

[0002]

2. Description of the Related Art Conventionally, as a flux-cored wire having a seam for welding, as shown in FIG. to fill a one that the product W _a finishing after molding the tubular ends are butted to the (a) hoop (band steel), and wire drawing by drawing die on the wire form, (B) hoop (strip after molding the tubular is Orikomin both edges in the tube side of the steel), which was wire drawing by drawing dies and product W _B finished wire-like, circumferential both ends each other (C) hoop (band steel) that the product W _C finishing wire drawing by molding KoShinsen die into a tube in superimposed in a direction to the wire shape (e.g. Kokoku 5-71359 discloses), are known like, both wire lengthwise There are seams in the direction.

[0003]

[Problems that the Invention is to Solve In this case, since the V-shaped groove remains in the seam portion, as shown in g _A after molding in the process of (A), lubricant in the V-shaped groove in the initial drawing intrusion And product W
_{In A} , a fine V-groove remains as shown in g _{A ′} ,
There was a problem that a blow hole was generated during welding, resulting in poor welding.

In the step (B), g is added to the joint after molding.
_Since the grooves _{B and} g _{B ′} remain and the lubricant remains, the same adverse effect as in the case of the step (A) occurs. Further, in the step of (B), the wire thickness of the portion of g B _'is thicker than the welding time arc is polarized, arc stability is deteriorated, slag inclusion is likely to occur. If the thickness of the wire is locally different, the straightness of the wire is also deteriorated, and the meandering phenomenon of the bead is observed.

[0005] In the step (C), no groove for trapping the lubricant is formed, but after the hoop molding, the thickness of the molded pipe becomes considerably thicker partially as shown by t _C, and after the wire drawing, it becomes slightly uniform. However, the wall thickness is increased as shown by t _{C ′} .
Therefore, there is a disadvantage that the arc stability and the arc stability are deteriorated, and the slag is involved and the beads meander.

As described above, in the conventional flux-cored wire for seam welding, dry and wet wire drawing lubricants remain in the seam of the wire cross section due to the manufacturing process, and blowholes are generated. Causes poor bead appearance. The thickness of the seam of the wire cross section becomes thick, the arc deviation and the wire straightness deteriorate, and slag entrainment and welding defects such as bead meandering occur. The two disadvantages were inherent. The present invention has been made in view of the above points, and has a narrow groove in which a large amount of lubricant remains, a uniform wall thickness of a joint portion, good arc straightness and good wire straightness, and welding. It is an object of the present invention to provide a flux cored wire for welding that does not sometimes cause defects such as blow holes, slag entrainment, and meandering of beads.

[0007]

In order to achieve the above-mentioned object, the present inventors have conducted intensive studies and as a result, have found that a flux-cored wire for welding has a built-in flux in a hollow portion formed by a shell made of steel strip. As the shape and dimensions of the joint between both ends of the outer skin in a cross section perpendicular to the longitudinal direction of the wire, if the conditions of the following formula are satisfied, the change in the thickness of the joint is reduced, and the straightness of the wire is improved. Further, the present inventors have found that since dry and wet wire drawing lubricants that cause welding defects in the seam grooves are suppressed, welding without bead meandering, slag winding, and blow holes can be performed.
That is, in the shape and dimension of the joint between both ends of the outer skin in a cross section perpendicular to the longitudinal direction of the wire 1 in which the blacks F are built in the hollow portion formed by the outer sheath 2 made of the strip steel (see FIG. 1), α: The angle between the joining line in the section and the tangent to the surface of the outer skin t ₁ : Maximum thickness of the outer skin in the section of the seam t ₂ : Minimum thickness of the outer skin in the section other than the seam ω: Slant in the cross section of the seam (1) 5 ° ≦ α ≦ 70 ° (2) 0.85 ≦ t ₁ / t ₂ ≦ 1.15 (3) 0.1t ₂ ≦ ω ≦ 1.4t ₂

Next, the reasons for setting the conditions of the above equations will be described below. (1) 5 ° ≦ α ≦ 70 ° If α is too small, the end of the seam portion indicated by 2a in FIG. 1 becomes thin, and during wire drawing, only the end of the seam portion 3 becomes thin as shown in FIG. The groove shown by appears, and a lot of lubricant remains,
Increase the occurrence of blowholes. Therefore, it was found that α = 5 ° or less was not preferable. Further, if α = 70 ° or more, the tightness of the gap of the groove of the joint portion 3 shown by 3b in FIG. 3 becomes loose, the gap becomes large, and a large amount of lubricant remains, and blow holes are generated. Therefore, “5 ° ≦ α ≦ 70 °” was set as a condition without blowhole defects.

(2) 0.85 ≦ t ₁ / t ₂ ≦ 1.15 The joint is a portion where the thickness tends to fluctuate in the wire manufacturing process. It becomes thin when the joint is loose, and becomes thick when both ends of the hoop overlap. If the thickness of the seam is not strictly controlled with respect to the minimum thickness of the portion other than the seam, the straightness of the wire is deteriorated and the bead meanders. Further, when the thickness ratio is large, the arc at the time of welding tends to cause slag entrainment rather than deviation. Therefore, if the thickness is controlled to “0.85 ≦ t ₁ / t ₂ ≦ 1.15” and the wall thickness is made uniform over the entire circumference of the wire, a condition free of welding defects can be obtained, so this condition was set.

[0010] (3) Features of 0.1t ₂ ≦ ω ≦ 1.4t ₂ present invention, FIG. 6 (A), unlike the conventional manufacturing process (B), the joint line of the portion near the surface of the seam portion Is inclined. As described under condition (1), when the inclination angle α is large and rises perpendicularly to the surface, the adhesion of the seam is loosened, the gap becomes large, residual lubricant increases, and welding defects appear. become. However, setting the inclination angle alone is not enough to reduce the residual lubricant to prevent welding defects, and the length ω of the inclined joining line needs to be longer than a certain length. As a result of various studies, it was found that at least 0.1 t ₂ or more was necessary. In addition, although the same effect is exhibited even if the length is longer than this, in the case of the present invention, after forming the hoop end and the pipe in each of the manufacturing steps (A), (B), (C), and (D) in FIG. As shown in each cross-sectional shape after drawing, the above (1),
In order to control condition (2), it is necessary to process both ends of the hoop (steel strip) before forming it into a pipe. Therefore, ω is 0.
If the effect is the same at 1t ₂ or more, the longer ω means that the sloped portion at both ends of the hoop becomes larger, processing becomes difficult, and the end surface inclined at an acute angle is easily scratched, and both ends when formed into a pipe shape Since the degree of adhesion deteriorates and the joint cannot be finished as designed, a maximum of ω of 1.4t ₂ is sufficient. That it is set to the conditions of 0.1t ₂ ≦ ω ≦ 1.4t _2. Therefore, in the case of the present invention, it is not necessary that the inclined joint line of the joint portion is inclined over the entire length from the surface to the inner surface of the pipe, and the joint may be vertically joined in the middle. Of course, the entire length may be inclined up to the inner surface.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a flux cored wire for welding according to the present invention will be described based on a material of the present invention and a comparative material. A low carbon steel strip (hoop) of 0.012% C is used for the outer skin made of strip steel, and the end parts shown in FIG. 6C are overlapped with each other using various kinds of 0.9 mm thick and 14 to 20 mm wide. A pipe was formed by the method, and a wire was manufactured in which t ₁ (the maximum thickness of the seam cross section) in FIG. 1 was changed by varying the amount of the overlapping portion t _c at both ends. Also, as shown in steps (A) to (D) of FIG. 4, both ends of the hoop are processed into various shapes, drawn after forming a pipe, and α and ω shown in the sectional view of the wire in FIG. Then, the welding characteristics were examined.

After forming the pipe, the outer diameter is 3 mm, the number of drawing times is 12, and the drawing speed is 640 m / min. Of the twelve drawing operations, the first nine were dry drawing, and the remaining three were wet drawing using a water-soluble lubricant to obtain a final 1.2 mmφ flux-cored wire. The reason for combining with wet drawing is that if there is a large amount of water-soluble lubricant as a residual lubricant at the joint, the occurrence of blowholes at the time of welding becomes remarkable and the effect of the present invention can be clearly proved. is there.

[0013] The flux components incorporated in the pipe are as follows. Ferrosilicon: 6 to 8% Rutile: 30 to 35% Ferromanganese: 20 to 23% Feldspar: 9 to 10% Alumina: 1 to 2% Iron: Residue The flux rate of the included flux was 17%.

The welding conditions were a voltage of 33 V, a current of 260 A,
In a shielded atmosphere of CO ₂ gas 20l / min, 60cm on steel plate
The weld was examined for defects when the bead was placed in a horizontal position. Welding is automatic welding. Since the straightness of the wire affects the meandering phenomenon of the bead, the straightness was examined. This was determined by projecting the wire 170 mm from the tip of the tip of the welding machine, and at this time, how eccentric the tip of the wire was from the center axis of the tip. Table 1 shows the overall results of the present invention and comparative materials. In Table 1, No.1, No.2, No.7
~ No.11, No.16 ~ No.20, No.28 ~ No.30 are comparative materials,
No. 3 to No. 6, No. 12 to No. 15, and No. 21 to No. 27 indicate the materials of the present invention.

[0015]

[Table 1] In each of the columns * 1, * 2, and * 3 in Table 1, those satisfying the conditions of the present invention are marked with ○, and those other than those of the present invention are marked with x. * 4
In the column of, a wire with a large runout is indicated by x, a medium wire is indicated by △, and a small wire deflection is indicated by ○. The wormhole is a connection of blowholes.

FIG. 5 shows an example of a wire cross section of the material of the present invention (a photograph taken at a magnification of 48.3). The wire 1
Is a wire of No. 5 in Table 1, in which a hollow portion of a pipe-shaped outer cover 2 is wrapped with a flux powder F, and the outer diameter of the wire is 1.21.
mmφ, α = 40 °, ω = 0.12 mm, t ₁ / t ₂ ≦ 1.04, ω vs. t ₂
The case where the ratio = 0.39 is shown.

As is clear from Table 1, No. 1 to No. 9
The joint angle α (see FIG. 1) of the seam portion of the wire changes, and the ratio of t ₁ / t _{2 and the} ratio of ω to t ₂ are constant values within the conditions of the present invention, but 5 ° ≦ α Only the wire satisfying the condition of ≦ 70 ° does not show all welding defects. No.10 ～Nanba18 wire changes the t ₁ / t ₂ ratio,
α and ω are constant and within the invention conditions, but clearly 0.85 ≦ t ₁
Only the wire that satisfies the condition of / t ₂ ≦ 1.15 has a healthy weld. The wires No. 19 to No. 30 are wires in which t ₁ / t ₂ and α are constant and satisfy the conditions of the present invention, and only the ratio of ω to t ₂ is changed. As for the wire having a short ω, that is, a wire having a small ratio to t _{2, the} tip of the seam portion falls off as described above (see FIG. 2).
Grooves are formed during wire drawing, a large amount of lubricant remains, and wormholes and blowholes are generated. However, when ω is 0.1 or more with respect to t ₂ , sound beads are formed. However, as for ω, as described above, the ratio of ω to t ₂ is limited to 1.4 or less due to the degree of manufacturing difficulty.

[0018]

According to the flux-cored wire for welding according to the first aspect of the present invention, the straightness of the wire is improved by specifying the shape and size of the joint between both ends of the outer skin in the wire cross section within the above range. Improve and eliminate arc deflection, produce a small amount of wire drawing lubricant remaining at the seam, and as a result, manufacture sound welded joints without bead meandering, slag entrapment, blowholes and wormholes Becomes possible.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a flux cored wire for welding showing a basic configuration of the present invention.

FIG. 2 is a partial cross-sectional view of a welding flux-cored wire in a state where a joint end is dropped off.

FIG. 3 is a partial cross-sectional view of the flux cored wire for welding in a state where a gap of a groove of a joint portion is large.

FIG. 4 is a view showing each cross-sectional shape of a hoop end, a pipe after forming, and after drawing in a manufacturing process of various wires according to the present invention.

FIG. 5 is a sectional view showing an example of a wire according to the present invention.

FIG. 6 is a schematic view showing a conventional process of manufacturing a flux-cored wire.

[Explanation of symbols]

1 ... wire, 2 ... outer skin, 2a ... end of seam joint,
3 ... seam, 3a, 3b ... groove at seam, F ... flux.

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[Procedure amendment]

[Submission date] March 16, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 1

[Correction method] Change

[Correction contents]

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kang Han-Kye 58-2, Seongdong-dong, Gyeongnam, Gyeongnam, Koryo Welding Rod Co., Ltd. (72) Inventor Yukio Yamaoka 1-3-3 Kitahorie, Nishi-ku, Osaka-shi Welding rod Japan Co., Ltd.

Claims (1)

[Claims] 1. A shape of a joint portion between both ends of an outer skin in a cross section perpendicular to a longitudinal direction of a welding flux-cored wire having a built-in flux in a hollow portion formed by an outer sheath made of a steel strip. A flux-cored wire for welding, characterized in that its dimensions satisfy the following equation. 5 ° ≦ α ≦ 70 ° (1) 0.85 ≦ t ₁ / t ₂ ≦ 1.15 (2) 0.1t ₂ ≦ ω ≦ 1.4t ₂ (3) where α: the tangent to the joint line at the seam section and the tangent to the outer skin surface Angle t ₁ : Maximum thickness of outer skin at seam cross section t ₂ : Minimum thickness of outer skin at cross section other than seam ω: Length of inclined joining line at seam cross section