JPH106083A - Manufacturing method of flux cored wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the breaking of a wire during wire drawing and to improve productivity by controlling the degree of diameter reduction in wire drawing using a die at the last stage in the case of repeating wire drawing for an tube stock for the wire filled a flux having a high filling factor and high iron powder ratio to obtain a desired thin diameter. SOLUTION: In case of manufacturing the wire, first, the flux containing, by wt., 10-80% iron powder is filled inside a sheath steel tube with, by wt., 12-26% filling factor to obtain starting wire. Next, primary wire drawing is applied to the starting wire using three rolls and annealing is applied. Next, wire drawing using a roller die is applied succeeding wire drawing using a roller die to obtain a desired thin diameter. However, in the case of wire drawing using the hole die, wire drawing (diameter reduction) is stopped within the range wherein the density of flux does not increase. By this way, the dispersion of the variation of the sheath wall thickness per the wire length is restrained within a given value or less, whereby the breaking of the wire during wire drawing using the hole die is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a flux-cored wire for welding, in which a flux filling rate (weight ratio of flux to the entire wire) and an iron powder rate (weight ratio of iron powder in the flux) are particularly high. The present invention relates to a method for producing a small-diameter, seamless metal wire.

[0002]

2. Description of the Related Art As disclosed in Japanese Patent Publication No. 45-30937, a method of manufacturing a seamless wire containing a flux is to fill a steel pipe having an outer diameter of about 13 mm with a vibration and fill it to about 3 mm by primary drawing. After processing, it is common to apply softening annealing and copper plating, and to wire-draw to a predetermined small diameter of about 1 mm by wire drawing using a hole die (hereinafter referred to as die drawing). The primary drawing is a die drawing and 3
Wire drawing by a roll mill (hereinafter referred to as three-roll wire drawing) is used. Three-roll wire drawing is a method of rolling by driving three small-diameter rolls, and is more efficient than die wire drawing, but it is difficult to draw a wire with a relatively small diameter.

[0003] Copper plating is applied for the purpose of preventing rust and improving the weldability of the wire, and is not always necessary depending on the application.

However, as the filling rate of the flux increases, the ratio of the outer shell material to the wire cross section decreases, and the ratio of the force required for wire drawing of the die increases as compared with the tensile strength of the wire after passing through the die. In addition, when the ratio of iron powder in the flux (hereinafter, referred to as iron powder ratio by weight ratio) increases, the fluidity of the flux in the outer skin at the time of wire drawing of the dies deteriorates, and the iron powder becomes clumpy (hereinafter referred to as cluster). ), Penetrates the outer skin, greatly reduces the ductility of the outer skin,
Facilitates breakage during wire drawing.

[0005] When the wire is broken, the higher the wire drawing speed, the greater the number of dies that have been cut off from the broken wire. In order to pass through the dies, it is necessary to make the tip of the wire thinner for each die, which takes a long time. It is also empirically known that the higher the drawing speed, the more easily the wire breaks. For the reasons described above, wire drawing of a wire that is easily broken is performed at a wire drawing speed of a normal 20 to 70.
% Is forced to slow down.

[0006] After the primary drawing, annealing is performed for the purpose of softening and dehydrogenation of the outer cover. However, if the temperature is increased and the annealing conditions are shortened for a short time, the outer cover material becomes too soft, so that the flux during the wire drawing of the die is hardened. Gaps are likely to be generated, which leads to disconnection. Therefore, since the annealing temperature of the wire which is easily broken is as low as about 550 ° C. and the outer skin is not so softened, it takes about 8 hours for dehydrogenation.

[0007] As described above, the flux-cored wire having a high filling rate and a high iron powder rate is liable to be broken when the diameter is small, and has significantly impaired the productivity.

In recent welding, automation has been advanced, and in welding such as shipbuilding and tank construction, a narrow-groove, high-speed welding machine has been developed, and the welding efficiency has been significantly improved. As a welding wire used for these weldings, a flux-cored wire having characteristics such as high-efficiency welding, less spatter, and a beautiful bead shape is remarkably excellent.

[0009] These flux-cored wires become flux components mainly composed of metal powder containing 10% or more of iron powder in order to increase the deposited metal, and a flux filling rate of 12% or more in order to increase the welding speed. Becomes Also,
The outer diameter of the wire used is becoming as small as 0.8 to 1.6 mm.

As described above, the demand for a fine-diameter flux-cored wire having a high flux filling rate and a high iron powder rate tends to increase. Therefore, in order to supply a large amount of high-quality wire, prevention of disconnection during wire drawing is a major issue. .

[0011] Therefore, as a wire drawing method without wire breakage, Tokuho 1
No. 29638 discloses a wire drawing method using a roller die (hereinafter referred to as a roller die drawing). When a roller die is used, rolling friction occurs to reduce external friction, and no excessive force acts on the wire strand. Further, since the processing is performed while changing the cross-sectional shape by the oval-shaped roller, it is considered that there is an effect of crushing the flux and an effect of preventing generation of clusters. With the above effects, disconnection can be prevented.

However, in the roller die, since the distance between the unit rollers is remarkably reduced by using a small-diameter hole-shaped roller and a small-diameter needle bearing in order to prevent the wire from being twisted, the sealing of the bearing is insufficient. is there. Also, as disclosed in Japanese Utility Model Publication No. 58-38314, the bearing can only be cooled by air, and when the speed is increased, grease flows out and the bearing is seized.
At most, it can only draw about 400 mpm. On the other hand, in the wire drawing of a wire where disconnection is not a problem, 80
The wire is drawn at a speed of 0 mpm or more. In addition, the roller die wire drawing has a drawback that the roller die cost is high, the capstan is required for each die, the equipment cost is high, and the space is large.

[0013] As described above, the efficiency of drawing a small-diameter flux-cored wire having a high flux filling rate and a high iron powder rate is sacrificed, and a high-cost equipment is used, thereby increasing the manufacturing cost. .

[0014]

SUMMARY OF THE INVENTION The present invention relates to a method for drawing a seamless wire with a high flux filling ratio and a high iron powder ratio, particularly a small-diameter flux-filled seamless wire, in which a wire breakage occurs in a die drawing and productivity is extremely poor. Roller dies that can prevent wire breakage solve the drawback of slow wire drawing speed and high equipment cost, and manufacture flux-cored wires that can prevent wire breakage, are more efficient than roller die wire drawing, and are economical in equipment cost. The aim is to provide a method.

[0015]

SUMMARY OF THE INVENTION The gist of the present invention is to provide a method of manufacturing a flux-cored wire, in which a flux containing 10 to 80% by weight of iron powder is contained in a steel pipe at a weight ratio of 12 to 25%. % Drawn wire strands are sequentially subjected to primary drawing, annealing, roller die drawing, and die drawing.
Wire is drawn to a desired small diameter.

[0016] Another object of the present invention is to draw a wire drawn by a roller die to an outer diameter at which the flux density does not increase by the wire drawing.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

FIG. 1 shows a steel pipe filled with a flux of 60% of iron powder at a filling rate of 15% by three-roll wire drawing and an outer diameter of 3.2 m.
This is an investigation of the flux density when the wire was drawn to a wire diameter of 1.2 mm in outer diameter by die drawing and roller die drawing after annealing at 550 ° C. for 8 hours. When the wire is drawn to 3.2 mm in outer diameter by three-roll wire drawing, the flux density increases to about 5 g / cc. The flux density of the die drawing decreases to about 4 g / cc until the outer diameter becomes 2.0 mm. However, when the wire is drawn to a smaller diameter, the flux density starts to increase, and when the outer diameter is 1.2 mm, the flux density becomes almost close to the density at the start of the wire drawing.

The reason for this is that annealing is performed after wire drawing of three rolls, so that the outer shell material is softened and easily stretched.
Further, as shown in FIG. 2, the void density is generated in a portion where the fluidity of the flux 2 is poor, so that the flux density decreases in the initial die drawing. Thereafter, when the die is further drawn, as shown in FIG. 3, the thickness of the outer skin material 1 increases in the space 3, and the thickness of the outer skin material decreases in the high flux density portion. Further, when the dies are drawn, the outer shell material is work-hardened and the flux is rolled, so that the flux density increases.

On the other hand, the flux density of the roller die drawing does not change up to the outer diameter of 1.8 mm, and the outer diameter is 1.8 m.
When it exceeds m, it slightly increases.

FIG. 4 shows the thickness distribution of the L section of the wire in which the flux 2 is filled in the outer cover material 1. Such a thickness distribution can be obtained by L-section polishing or X-ray photography.
A maximum thickness and a minimum thickness within a predetermined L section length are measured, and a value obtained by dividing the maximum thickness by the minimum thickness is defined as a P value. If the P value exceeds 1.5, disconnection tends to occur.

As shown in FIG. 5, the P value within the cross-sectional length of 100 mm in the L direction at the time of wire drawing by the above-described die and roller die wire drawing rapidly increases when the outer diameter becomes 2.4 mm or less in the wire drawing. , Roller die wire drawing 1.6 outer diameter
It became slightly larger below mm.

Further, it is considered that the reason why disconnection is likely to occur when the P value increases is that processing strain is locally concentrated on the minimum thickness portion and ductility is reduced. It should be noted here that the outer diameter at which the P value of the die drawing in FIG. 5 rapidly increases is 1.8 m.
m, which corresponds to the outer diameter at which the flux density of the die drawing in FIG. 1 increases. Therefore,
It can be seen that an increase in the P value is associated with an increase after the flux density has once decreased.

In the roller die drawing, the increase of the P value is small. In the case of a roller die, it can be considered that the drawing is performed by repeating an elliptical shape using a hole-shaped roller, and the drawing force is small due to rolling friction.

Therefore, in order to prevent the P value from increasing in the wire drawing of the die from the above mechanism, it is necessary not to increase the flux density by further drawing after the flux density is reduced.

[0026] Therefore, after the annealing, the wire is drawn by a roller die in which the flux density does not decrease, and thereafter, the outer diameter at which the flux density does not increase after the flux density is reduced by the wire drawing with a higher wire drawing speed than the roller die drawing. If the wire is drawn within the range, the P value is not increased, and thus wire drawing with good production efficiency can be performed without disconnection.

Further, the roller die wire drawing is performed by P
If the wire is drawn within a range up to the outer diameter at which the value stays at 1.5 or less, the wire can be drawn without breaking.

Next, a steel pipe filled with a flux having a filling rate of 15% and an iron powder rate of 60% was drawn by three rolls to an outer diameter of 3.2 mm, and after annealing, a roller die was drawn to an outer diameter of 2.1 mm. Next, FIG. 6 shows the result of investigating the flux density at each diameter when the wire was drawn to a wire diameter of 1.2 mm by die drawing, and FIG. 7 shows the change of the P value. If the roller dies are drawn to an outer diameter of 2.1 mm, the subsequent dies can be drawn to an outer diameter of 1.2 mm within the range from the flux density decreasing to increasing, and the increase in the P value can be suppressed. And disconnection can be prevented.

Therefore, according to the method of the present invention for drawing by combining roller die drawing and die drawing, the roller die drawing is used up to an outer diameter of 2.1 mm or less and a final outer diameter of 1.6 mm or less. Die wire drawing speed is 800-1000
Since the roller die drawing speed at mpm may be 400 mpm or less, there is no reduction in efficiency with the current roller die drawing technology. Also, it is possible to reduce the number of expensive roller die wire drawing machines.

Furthermore, since the increase in the P value is small in the roller die drawing, it is possible to perform the dehydrogenation treatment by increasing the annealing temperature after shortening the three rolls and shortening the annealing time. Since the time for manufacturing the wire can be greatly reduced, the production can be performed more efficiently.

In the present invention, as shown in FIG. 8, if the roller die drawing device and the die drawing device are connected continuously, labor can be saved and the productivity is good. That is, the wire strand 4 having an outer diameter of 3.2 mm is supplied from the supply reel 14 and pulled by the capstan 6 while reducing the diameter by the roller die 5. Here, an example of four stands of roller dies of 5, 7, 9, 11 and capstans of 6, 8, 10, and 12 is shown. However, the number of stands is such that the reduction rate of roller dies per stand is 3
As many as necessary to obtain a predetermined outer diameter so as to be 5% or less. Here, the area reduction rate is represented by (wire cross-sectional area before wire drawing-wire cross-sectional area after wire drawing) / wire cross-sectional area before wire drawing. Thereafter, the wire is drawn to a predetermined outer diameter by a die drawing device 13 and wound on a take-up reel 15. The die wire drawing device 13 is a commercially available wet wire drawing device.

In the present invention, it is necessary that the flux contains at least 10% by weight of iron powder in order to improve the welding efficiency by increasing the amount of the deposited metal. However, if the amount of iron powder is too large, the effect as a flux cannot be sufficiently exhibited, so the maximum weight ratio is set to 80%.

The flux filling rate must be at least 12% by weight to increase the efficiency of the welding workability by increasing the amount of the deposited metal, but if it exceeds 25%, the wire breaks during wire drawing. Since the production becomes difficult, the maximum weight ratio was set to 25%. From the viewpoint of welding workability, the weight ratio is preferably 15 to 25%.

[0034]

[Example] Outer diameter 12-18mm, wall thickness 1.5-2.0m
m steel pipe (JIS G3445 STKM11A)
Various fluxes with different iron powder rates are granulated with water glass,
Drying, sizing, vibration filling to the target filling rate, primary drawing to an outer diameter of 3.2 mm by 3 roll drawing, annealing under various conditions,
Copper plated. Thereafter, using a device shown in FIG. 8, the wire was drawn with a roller die, the wire was continuously drawn to the final diameter by the wire drawing at each wire drawing speed, and was wound on a take-up reel. The roller die drawing speed in this case was 400 mpm or less.

Incidentally, in the case of the final outer diameter of the die drawing of 1.2 mm, the example of the die configuration of the roller die drawing and the area reduction rate are as follows.
2mm → 2.8mm (23%) → 2.45mm (23
%) → 2.1 mm (27%) → 1.8 mm (27%). The number of stands is four. Here, the die configuration of the roller dies and the number of stands were changed according to the final die outer diameter of the roller die drawing.

The number of dies until the final outer diameter of the dies after the roller dies was drawn was 8 to 10 dies, and the reduction in area was 6 to 13% per die.

In each test, the trial production amount was 5 tons, and the presence or absence of breakage during wire drawing and the P value after the completion of die drawing were measured. The results are summarized in Table 1.

In Table 1, No. 1 to No. 6 is an example of the present invention, N
o. 7-No. 12 is a comparative example.

In the example of the present invention, no. 1 to No. In No. 6, since the die drawing was performed after drawing the roller die to the outer diameter (1.6 to 2.1 mm) at which the flux density did not increase by the die drawing, the P value was 1.5 or less. Even if the final drawing speed was set to 800 to 1000 mpm, and even if the annealing temperature was set to a high temperature for a short period of time, the results were extremely satisfactory without disconnection.

The wire N manufactured according to the present invention
o. 1 to No. As a result of welding using No. 6, the wire feedability, welding workability, and welding quality were all good.

In the comparative examples, No. 7-No. No. 10 is an example in which after the annealing, the wire was drawn to the final outer diameter by only the wire drawing without the roller die drawing. These wires were drawn with the final die drawing speed reduced, but the P value was higher as the iron powder ratio, the filling ratio and the annealing temperature were higher, and all of them exceeded 1.5 and were broken.

Test No. 11 and No. In No. 12, since the final outer diameter of the roller die drawing was too large, the final drawing speed of the die was reduced, and the wire was drawn. did.

In the above embodiment, an example of copper plating has been described. However, the present invention can be similarly applied to a non-plated wire without copper plating. Also, the finished outer diameter of the primary wire drawing is 3.
Although it is 2 mm, even if the diameter is different due to the facilities and the like, there is no problem of disconnection if the roller die is drawn to an outer diameter where the flux density is not increased after the flux density is reduced after the wire drawing.

[0044]

[Table 1]

[0045]

According to the present invention, 10 to 80% by weight
Flux containing iron powder of 12 to
When manufacturing a flux-cored wire for filling a wire by 25% and drawing the wire into a small diameter, it is possible to eliminate disconnection at the time of drawing without lowering the drawing speed. In addition, since it is not necessary to perform long-time annealing and reduction of the drawing speed for suppressing disconnection, energy saving and high efficiency can be achieved. Also,
Since the ratio of the wire drawing of the roller die in the manufacturing process can be reduced, the equipment cost is economical.

[Brief description of the drawings]

FIG. 1 is a diagram showing a change in flux density during wire drawing by die drawing and roller die drawing.

FIG. 2 is a view showing a behavior of a flux in a cross section of a wire L when a flux density is lowered by wire drawing of a die.

FIG. 3 is a diagram showing a change in the thickness of a cross section of the wire L when the wire of FIG. 4 is further drawn and the flux density increases.

FIG. 4 is a diagram showing an L sectional view of a wire.

FIG. 5 is a diagram showing a change in a P value during wire drawing by die wire drawing and roller die wire drawing.

FIG. 6 is a diagram showing a change in flux density during a manufacturing process according to an example of the present invention.

FIG. 7 is a diagram showing a change in a P value during a manufacturing process according to an example of the present invention.

FIG. 8 is a diagram showing an example of a wire drawing device used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer shell material 2 Flux 3 Air gap 4 Wire strand 5, 7, 9, 11 Cassette roller die 6, 8, 10, 12 Capstan 13 Die wire drawing device 14 Supply reel 15 Take-up reel

Claims (2)

[Claims] 1. A method for producing a flux-cored wire, comprising: sequentially drawing a wire element in which a flux containing iron powder in a weight ratio of 10 to 80% is filled into a steel pipe in a weight ratio of 12 to 25% inside a steel pipe; A method for producing a flux-cored wire, comprising annealing, roller die drawing, and die drawing to draw a desired small diameter. 2. The method for producing a flux-cored wire according to claim 1, wherein the wire drawn by the roller die is drawn to an outer diameter at which the flux density does not increase by the wire drawing.