JPS61202796A - Production of flux-cored wire - Google Patents

Abstract

PURPOSE:To obtain a wire which is uniformly filled with a flux and prevents moisture absorption by projecting the edge of a steel strip positioned on top in the stage of forming an outside flux filling body and bending the projecting part toward the inside in the stage of incorporating an inside flux therein. CONSTITUTION:The steel strip 1 is bent to a U trough shape and the outside flux 4 is supplied to the inside thereof. Both ends of the strip 1 are bent to the inside to form the outside flux filling body 21. The edge end 31 on the front layer side is made longer than the peripheral length on the inside circle of the wire to be formed. The body 21 is bent to the U trough shape and the inside flux 5 is supplied to the inside thereof. The edge part 31 projected to the front surface side is bent to the inside and the U trough-shaped body 22 is tightened and formed to a circular section, by which the flux-cored wire of a double-layer type is obtd. The moisture absorption of the filled flux is prevented by the above-mentioned method.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an improved method of manufacturing double flux-cored wire.

[Conventional technology]

Various flux-cored wires have been proposed so far, and the cross-sectional shape of the wire is shown in FIG.

Figure 5 (a) shows a wire with no joints, and the filling flux 2 has excellent moisture absorption resistance, but there are restrictions on the length of the pipe into which the flux can be inserted, and flux filling is done in a batch manner. In order to make the flux filling in the pipe more uniform and increase its density, it is necessary to pre-treat the flux before insertion to prevent the blended flux from separating and segregating due to the vibrations applied to the pipe. In order to draw wire to a finished diameter of 2 mmφ or less, an annealing process is required during the wire drawing, which reduces production costs, and the raw material that thermally decomposes at this annealing temperature is used as flux. For this reason, there are limits to the welding methods to which the wire (a) can be applied.

On the other hand, flux-cored wires other than (a) in Fig. 5 (b)
-(j) are formed by rolling a flux 2,4.5 into a band-shaped mild steel material 1, and are generally also called crimped wires. These winding wires are manufactured using the above-mentioned method (a).
) It is advantageous because there are no restrictions like wires.

The various types of crimp wires shown in (b) to (j) each have their own characteristics and are used depending on the situation, but according to a recent detailed study by the present inventors, the cross-sectional A double type flux-cored wire (Japanese Patent Publication No. 44-2336) having an outer flux 4 and an inner flux 5 as shown in shape (j) has the best properties during welding and of the weld metal. In particular, it is recognized that flux-cored wires are advantageous for use in so-called unencapsulated arc welding, which allows welding in the atmosphere without the need for an external supply of arc encapsulating gas or solvent during welding. It has been reached.

However, when manufacturing a wire having the cross-sectional shape of (j) and using a product, the following points are raised as problems.

(1) Since the embedded flux 5 has an opening 6 that communicates with the outside air, the embedded flux 5 absorbs moisture, and as a result, pores such as cracks, pits, or blowholes caused by diffusible hydrogen occur in the weld metal. There is a risk that

Until now, many technical proposals have been made to lower the initial moisture value of flux raw materials or products, but these proposals have not been effective in preventing moisture absorption from the openings 6 that exist in the joints of the crimp wires. To this day, there is no decisive factor. A similar problem existed with dual flux-cored wire.

(2) During manufacturing, there is no problem with the outer flux 4, but if the inner flux 5 twists in the wire at the initial stage of wire drawing immediately after forming, the wire with the cross-sectional shape shown in Fig. 6 will have an opening as shown in Fig. 7. 6 spreads, the embedded flux 5 moves, and the flux 5 spills out of the wire, causing the distribution of the internal filling flux 5 of the wire to become uneven, and in extreme cases, there are places where there is almost no flux filling, This may cause welding to become impossible or the performance of the weld metal to deteriorate.

Alternatively, in areas where the flux was biased and excessive, there was a tendency for the wire to break easily during wire drawing.

The following attempts were made to solve problems (1) and (2) above, but they were unsuccessful due to the following problems.

First, the forming process of this wire is schematically shown in FIG.

The double flux-cored wire with the cross section shown in Fig. 5 (j) is the fifth
Figures (b), (c), and (f). A steel strip material with a thinner plate thickness than the wire in (h) is used.

The finished diameter of the wire can be used differently, but the finished diameter is 2mm.
For wires with a diameter of ~1.6 mm, the plate thickness is generally 0 or 15 mm.
mm-0.25 mm is used.

The strip is formed into a flux-filled generatrix using forming rolls and then drawn through a die. There are two types of forming rolls: the drive roll type, which drives the roll itself, and the idle roll type, which does not drive the roll and applies tension drive to the steel strip using a tension machine to form it. However, the drive roll type uses a drive roll to control the rolling elongation of the wire that occurs during forming. Since delicate speed control is difficult and the equipment is very expensive, recently idle roll type forming machines are used even for double type flux-cored wire, and there is a need to make them usable again. There is.

Here, a case where an idle roll type molding machine is used will be briefly described.

:As shown in Figure FfJ9, the steel strip is tensile 4! ! 102, and passes through a series of idle forming rolls of the forming machine 101 to be formed.

The forming process will be explained in detail with reference to Figures 8 (a) to (s). The first step...The steel strip is supplied in the state shown in (a).
After passing through (b), both sides of the steel strip are formed into a U-shaped gutter shape as shown in ()\), and the outer flux 4 is transferred to the hopper 1 in the U-shaped machine.
It is introduced from 1, and then (d).

As shown in (e), both edge portions of a U-shaped machine steel strip are bent inward to form an outer flux filling body 21 having a rectangular cross section.

Second step...The outer flux filling body 21 with a rectangular cross section is further formed into a U-shaped machine shape as shown in (F) and (G), and the inner flux 5 is filled in the U-shaped groove. It is fed from the hopper 12.

Third step...Then, the U-shaped gutter-shaped filling body 22 is tightened as shown in (H) and (S), and the circular filling body 23.24
The inner flux 4 is built into the center.

As mentioned above, the filling body 24 formed from this U-shaped trough-like filling body 22 encloses flux, and unless a considerable reduction is applied, the enclosed flux 5 will remain in a state where it can be easily moved. There is a problem in that the distribution of flux within the wire is uneven.

[Problem that the invention seeks to solve]

In order to prevent such a problem, the movement of the embedded flux can be stopped by increasing the number of roll reduction blades during forming in the third step, or by increasing the number of forming rolls to strengthen squeezing. However, this U-shaped gutter-like packing body 22,
When a large rolling blade is applied to the circular filling bodies 23 and 24, an excessive load is generated, and a large tensile torque is required to pull the steel strip.
A large tensile force is generated between the two, and as a result, the black wire busbar breaks.

Furthermore, if too large a reduction blade is applied, scratches are likely to occur on the thin steel strip that forms the skin of the wire, which also becomes a cause of wire breakage.

An object of the present invention is to provide a method for manufacturing a double flag-cored wire that can solve problems (1) and (2) above without causing such new problems.

[Means for solving problems]

The present invention consists of new technical means that improve the conventional method of manufacturing double black-cored wire, which consists of the following three steps: &), b), and c).

a) Using a device that continuously forms the steel strip, first bend it into a U-shaped trough shape, supply outer flux to the inside of the U shape of the U-shaped trough-shaped steel strip, and form the edges of the U-shaped trough-shaped steel strip on both sides. The first step is to form an outer flux filling body with a flat rectangular cross section that envelops the outer flux by folding them inward and stacking them on top of each other.

b) Bend this outer flux filling body into a U-shaped gutter shape, and
A second step of supplying embedded flux to the U-shaped inside of the trough-shaped packing body.

C) A third step in which the U-shaped trough-like filling body is then tightened and formed into a circular cross section, and the encapsulated flux is built into the center.

In the above conventional continuous forming process of double type flux-cored welding wire, A) In the first step, the width of the plate on the surface side of the overlapping part of the steel strip is changed to the inner side of the double type flux-cored wire which is formed into a circular cross section. Make it longer than the circumference of the circle.

B) In the third step, first bend the free end in the width direction of the surface plate to the inside of the U-shape, and then bend the U-shaped trough-like filling body into a circle.

technical measures were adopted.

FIGS. 1(a) to 1(f) are cross-sectional shapes of the wire during the forming process, showing steps corresponding to (E) to (S) of the conventional forming process shown in FIG. 8 above.

The main difference between the present invention and the prior art lies in the cross-sectional shape of the outer envelope flux filler 21 having a rectangular cross section in the first step. Compared to the conventional technology, the edge portion of the steel strip bent from the outside in the T-plane protrudes outward from the outer flux filling body 21, or when the outer flux filling body 21 is bent into a U-shaped gutter shape, the edge of the steel strip In other words, the width of the plate 31 on the surface side of the folded steel strip edge portion should be longer than the circumference of the inner circle of the wire formed into a circular cross section. This is the first feature of the present invention.

In order to obtain this shape, the width of the bent portions of the left and right edge portions of the steel band in the first step may be adjusted.

The adjustment method will be explained below.

Conventionally, as shown in Fig. 8, both edges of the steel strip were U-shaped.
In the third step of forming the shape from a gutter shape to a circular shape, it is folded into a rectangular shape so as not to protrude laterally.

This is because if the plate width of both folded edges of the outer envelope flux filling body 21 is made large, the inner edge portion folded in during 0-shape forming will buckle in a complicated manner internally as shown in FIG. Differences in flux distribution tend to occur, making wire breakage more likely to occur during wire drawing.

On the other hand, the folded surface edge part protrudes during the second step of U-forming as shown in FIG. 11, and during the third step of circular tightening forming and wire drawing, the die becomes rough and abnormal wear of the roller die occurs. This is because wire breakage is more likely to occur.

As described above, when forming the plate-shaped outer envelope flux filling body 21 with a rectangular cross section, the plate width of the folded steel band edge portion located on the upper surface of the surface layer is adjusted to the circumference of the inner circle of the wire to be formed into a circular cross section. It is made longer than the length so that it protrudes when the outer envelope flux filling body 21 is formed into a U-shaped gutter shape. In the present invention, this protrusion is folded into the U-shaped trough-like interior in the next third step, so there is no problem such as the roughness of the die.

The plate convergence of the surface side folded edge portion 31 during molding of the plate-shaped outer envelope flux filler 21 having a rectangular cross section is determined as follows.

As shown in FIGS. 2(a) and 2(b), the plate-shaped flux filler 21 with a rectangular cross section has a thickness W, and when forming into a U-shaped trough, the inner diameter r of the U-shaped trough is naturally larger than the outer diameter R. will also become smaller.

The length of the outer periphery of the U-shaped trough is expressed by the formula 0, and πR+2H=L... ■On the other hand, the total length of the inner periphery of the U-shaped trough is expressed by the formula 0.

πr + 2 H+ X = L ・・・・・・■■
, ■From the formula, X=π(R-r) =π(r+W)...■.

Here, in order to obtain the desired protrusion length X during zero-shape molding, it can be expressed by the following formula.

X = Also - (πr + 2H) ... @ Therefore, if the rectangular shaped shape from the steel strip, W, and the inner diameter r of the 0-shaped molding are determined, H can be found from the 0 formula, and the desired protrusion length X can be determined. The sentence is found from the formula.

= πr + 2H + In addition, it is preferable to set the length to cover the entire upper surface of the fuller and box inside the U-shape.If it is too long, it will be difficult to fold it into the U-shape.

After the plate-shaped flux filling body with a rectangular cross section obtained in this way is formed into a U-shaped gutter shape, the flux hopper 12
It is the same as in the conventional method that the filling flux 5 for inclusion is injected into the inside of the 0 character.

Tightening the flux is a process, and in the conventional method, the tightening was performed at the same time by forming the U-shaped gutter shape itself under pressure, but according to the present invention, as shown in FIG. 1(C), (
As shown in d) and (e), before tightening the entire U-shaped gutter-shaped plate-shaped flux filling rod, only the protruding edge portion 31 of the steel strip is folded inward, and the embedded flux 5 is
The lid is pressed down so that it can be turned over.

According to this method, the protruding steel band edge portion 31 is easily deformed by a slight rolling force, and it becomes possible to reliably tighten the filling flux for inclusion. This is the second feature of the present invention.

After completing the tightening of the included flux in this way,
The cross-section of the wire obtained by tightening the entire flux filling body and final forming it into a circular shape is shown below.
FIG.

〔Example〕

By the method of the present invention, a double flux-cored wire (Example) having the cross-sectional shape shown in FIG. 3 was manufactured. For comparison, a double flux-cored wire (comparative example) having the cross-sectional shape shown in FIG. 6 was manufactured. Its manufacturing specifications are as follows.

Example Comparative example Plate thickness of steel strip 0.15 mm 0.18 mm Width of steel strip 22 mm 20 mm Shape of outer flux filling body (see Figure 2) L 8 mm 8 mm WO98
mm 0.8mm W IO, 7mm m 0.8mm m view
7.5 mm 5.2 m mr
1.35mm x 2. Om m wire shape
Figure 3 Figure 6 Finished wire diameter 1.8
m mφ 1.8 mmφ Franks inclusion ratio External flux 15% 15% Inner flux io% 10% The above examples and comparative examples were subjected to a moisture absorption acceleration test in an atmosphere of 30°C and 80% humidity, and then tested in accordance with J I SZ3113. Figure 4 shows the results of measuring the amount of diffusible hydrogen.

Welding conditions were as follows.

Welding atmosphere = 15℃ x humidity 68% Welding current: 250Amp Welding voltage: 23vol Welding speed: 25cm/min Wire extension: 25mm Polarity: DC-RP As is clear from Figure 4, in the comparative example, the standing time was At the same time, the amount of diffusible hydrogen increased, and the following welding defects occurred at points A-F in FIG.

A... Avatar generated on the bead surface during welding BCDE
F...A herringbone is generated on the bead surface during welding.CDEF...A blowhole is generated inside the weld metal as a result of an X-ray test.F...A pit is generated in the weld bead.In comparison, in the example, the amount of diffusible hydrogen due to the standing time There was no change in the welding temperature, and all beads during welding were defect-free.

Reference example No. 3 in Figure 8 above is an example that is expected to have the same effect as this magazine.
One possible method is to selectively fold only the edges of the steel strip that have already been folded onto the outer upper surface in the process to cover the flux, but as a result of research, we have found that in the forming process to obtain a generatrix of 4 mmφ or less, the edges of the steel strip are In order to selectively process only certain parts, the precision of the line would have to be dramatically improved, and rollers would have to be extremely expensive, making it impractical.

〔Effect of the invention〕

According to the method for producing a flux-cored wire of the present invention, 1) As described above, since the embedded flux is sufficiently tightened and fixed in the steel strip even with a small rolling blade, it is necessary to use the subsequent forming rolls in order to obtain a forming generatrix. It was decided that the reduction blade could simply be made circular.

Therefore, the tensile torque of the steel strip was small, no excessive tension was generated in the forming machine and during the tensile process, and breakage was avoided.

2) 3'5! As is clear from the cross-sectional shape of J, the filling flux for the inner encapsulation is completely blocked from the opening by the above-mentioned protruding edge of the steel band, so twisting occurs in the wire at the initial stage of the wire drawing process after forming. In addition, the filling flux does not spill out, and the distribution of the included flux folded inside is also prevented from becoming dense.

3) Since the internal flux is completely blocked from the opening, the outside air and the filling flux are blocked.
It was confirmed that moisture absorption of the filling flux could be almost completely prevented.

As detailed above, according to the method of the present invention, fuller.

This method allows stable production of flux-filled wire without the uniform hygroscopicity of flux, and has extremely high industrial value.

The present invention is applied to the production of wire for self-shielded arc welding, but it can also be used for gas encapsulation welding, in which the welded part is encapsulated in an inert gas such as carbon dioxide or argon, or in which the welded part is covered with a solvent. Needless to say, the same effect can be exerted on flux-cored wire for automatic submerged arc welding.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a formed body showing the steps of the method of the present invention, FIG. 2 is an explanatory diagram showing the dimensional relationship of the steel strip of the present invention, and FIG. Figure 4 is a graph showing the effect of the example, 5th rl! J is a cross-sectional view of the wire used to insert conventional flags. Figures 6 and 7 are cross-sectional views of a conventional double-type flux wire, Figure 8 is a manufacturing process diagram of a conventional double-type flux wire, and Figure 9 is a layout diagram of the manufacturing line. 10
FIG. 11 is a diagram showing an unfavorable cross-sectional shape in the manufacturing process of a double type flux-cored wire. ■...Strip steel 2.4.5...Flux 6...Opening 11.12...Hopper 21...Outer envelope flux filling body 22...U-shaped mechanical filling body 23.24.・Circular filling body

Claims (1)

[Claims] 1. Continuously bending a steel strip into a U-shaped trough shape, supplying outer flux to the inside of the U shape of the U-shaped trough-shaped steel strip, and bending both edges of the U-shaped trough-shaped steel strip. A first step of folding inward and overlapping to form an outer flux filling body with a rectangular cross section, bending the outer flux filling body into a U-shaped gutter shape, and supplying the inner flux to the U-shaped inside of the U-shaped gutter-shaped filling body. Second step: Next, the U-shaped gutter-like filling body is tightened and formed into a circular cross section,
A method for continuously forming a double flux-cored welding wire, which comprises: a third step of incorporating embedded flux in the center; The length is made longer than the circumference of the inner circle of the heavy-duty flux-cored wire, and in the third step, the free end in the width direction of the plate on the surface side of the edge portion is first bent inside the U-shape, and then the U-shape is A method for producing a double flux-cored wire, which comprises tightening and forming a trough-like filling body into a circular cross section.