JPH10296488A - Method for drawing thin flux cored wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a drawing method for a thin flux cored wire by which the wire breakage is not generated even at the time of high-speed drawing, which is excellent in productivity and whose cost is lower by drawing the wire making the reduction of area of each hole die not more than a specified possible limit reduction of area. SOLUTION: In this method, drawing is executed taking the reduction of area of each hole die as not more than the possible limit reduction of area which is expressed by the formula R=33.7-0.13X-0.002X<2> (In the formula, X is the total reduction of area.). When the diameter of the element wire of the wire is over 5 mm, the total reduction of area till the wire is drawn into a desired product becomes higher, the outer cover is hardened by working and the wire breakage is apt to generate, so it is desirable that the diameter of the element wire is 2-5 mm. When an iron powder rate becomes more, a slag agent and deoxidizerare relatively less and weldability and performance of weld metal are not satisfied, so the iron powder rate of filling flux is taken as 10-60%. From the viewpoint of elevating weldability, the filling rate of the flux is taken as, by weight, 15-20%. In this way, the thin flux cored wire having higher flux filling rate and iron-powder rate is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a flux-cored wire for welding, and more particularly to a flux filling rate (weight ratio of flux to the total weight of the flux-cored wire) and an iron powder rate (weight of iron powder in the flux). (Ratio) with high ratio.

[0002]

2. Description of the Related Art In recent years, automation of welding and labor saving have been promoted. As a welding wire used for such welding, a flux-containing wire having features such as high efficiency welding, little spatter, and a beautiful bead shape is used. Wire is much better, and demand is increasing for semi-automatic and fully automatic welding.

[0003] The flux-cored wires used in these are usually flux components mainly composed of metal powder containing 10% or more of iron powder in order to increase the deposited metal, and the flux filling rate is usually 12% or more. is there. Further, the wire diameter is becoming as small as 0.8 to 1.6 mm.

[0004] There are two types of manufacturing methods for a flux-cored wire without seams. First, Tokiko Sho 45
No. -30937, a method of vibration-filling a steel pipe with a flux, or, as described in Japanese Patent Publication No. 4-72640, a steel strip is continuously formed from a U-shape to an O-shaped cross section. After supplying the flux to the U-shaped steel strip, there is a method of welding the opposing edge surfaces formed into an O-shape. In both cases, after the wire is filled with the flux, the wire is processed to a diameter of about 3 mm by primary drawing, then subjected to soft annealing and copper plating (sometimes omitted), and further to 0.8 to 0.8 mm by hole die drawing. A method of manufacturing by processing to a desired diameter of 1.6 mm is employed. The primary wire drawing is reduced by hole die wire drawing and wire drawing by a three-roll mill (hereinafter, referred to as three-roll wire drawing). Three-roll wire drawing is a method of driving three small-diameter rolls to reduce the diameter, and is more efficient than wire drawing with a hole die, but drawing to a small diameter is difficult.

[0005] The secondary drawing of a flux-cored wire is reduced in diameter by hole die drawing. However, as the diameter becomes smaller, the thickness of the outer shell material becomes thinner. When the ratio decreases, the processing force of the flux and the frictional force with the hole die all act as a pulling force on the outer shell material, and when the iron powder rate further increases, the fluidity of the flux at the time of drawing the hole die deteriorates, The iron powder is lumped and hardly enters the outer skin, which greatly reduces the ductility of the outer skin and makes it easier to disconnect.

When the wire is broken, the higher the drawing speed, the greater the number of hole dies coming out of the broken wire. Therefore, the number of times that the wire needs to be passed through the hole dies increases.
In order to pass through the hole dies, it is necessary to make the wire tip thinner for each of the hole dies, which requires a long time for the processing and lowers the production efficiency.

It is empirically known that the higher the drawing speed, the more easily the wire breaks. For the above reasons, the wire drawing speed must be reduced by 20 to 70% of the normal drawing speed.

[0008] Tokuho 1-2 as a wire drawing method without breaking
No. 9638 discloses a wire drawing method using a roller die. 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 elliptical hole-shaped roller, it is considered that there is an effect of crushing the flux and an effect of preventing the iron powder from being formed into a lump. With the above effects, disconnection can be prevented.

However, in the roller die, 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, so that the sealing of the bearing is insufficient. is there. Further, as disclosed in Japanese Utility Model Publication No. 58-38314, the bearing portion 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. This is 80 mm in wire dies drawn with a wire where disconnection is not a problem.
The drawing speed is slower than drawing at a speed of 0 mpm or more. In addition, wire drawing using a roller die has drawbacks such as a high cost of the roller die, a high cost of equipment because a capstan is required for each die, and a large space.

[0010] As described above, in order to draw a small-diameter flux-cored wire having a high flux filling rate and a high iron powder rate, efficiency is sacrificed or equipment cost is high.
Manufacturing costs were high.

[0011]

DISCLOSURE OF THE INVENTION The present invention relates to a method for drawing a fine-diameter flux-cored wire having a high flux filling rate and a high iron powder ratio in the filling flux without breaking even at a high speed. An object of the present invention is to provide a method of drawing a fine-diameter flux-cored wire having good properties and low manufacturing cost.

[0012]

Means for Solving the Problems The present inventors oscillate a YFW-C500X flux cored wire specified in JIS Z3313 with a flux filling rate of 20% and an iron powder rate of 60% into a steel pipe (JIS G3445 STKM11A). After filling, the wire was primarily drawn to an outer diameter of 3.2 mm by three-roll wire drawing, and annealed and plated wires were used to investigate various causes of disconnection in secondary drawing by a hole die.

As a result, as shown in FIG. 1, under the condition of the area reduction rate for each hole die, which is usually carried out for wire drawing,
When the elongation of the flux-cored wire passing through each hole die when the wire is drawn to a product diameter of 1.2 mm is examined, as shown in FIG. 2, the elongation of the wire decreases with the diameter reduction of the drawn wire. That is, in accordance with the increase in the total area reduction rate, the wire skin is work-hardened and the elongation of the wire is reduced.
When it exceeds 0%, it has been found that the elongation of the wire is remarkably reduced to cause disconnection. In addition, we investigated the flux filling rate and the wire drawing of the flux-cored wire with a high iron powder rate, which tended to cause breakage during wire drawing. As in the case of the wire drawing by the die, it was found that there was a possible limit area reduction rate in which the disconnection did not occur and the disconnection shown in FIG. 1 did not occur.

The present invention has been completed based on this finding, and the gist of the invention is as follows.

(1) In a method of continuously drawing a fine-diameter flux-cored wire using a plurality of hole dies, the area reduction rate of each hole die is determined by the following formula. A wire drawing method for a small-diameter flux-cored wire, which is performed by the following method.

Possible limit reduction (R) = 33.7-0.1
3X−0.002X ^{2 where} X in the above equation means the total area reduction rate.

(2) The wire diameter of the flux-cored wire before drawing is 2 to 5 mm, the flux filling rate is 12 to 25%, and the iron flux rate of the filling flux is 10 to 60%. ).

[0018]

FIG. 3 is a diagram showing the relationship between the total area reduction rate (X) and the possible limit area reduction rate (R) of each hole die.
As shown in FIG. 3, when a flux-cored wire is drawn using a plurality of hole dies, the surface reduction rate of each hole die is made smaller than a possible limit area reduction (R), thereby drawing at a high speed. It was confirmed by experiments that no disconnection occurred even if the wire was cut. This possible limit area reduction (R) could be defined by the following equation.

R = 33.7-0.13X-0.002X ² (where X represents the total area reduction rate) FIGS. 4 and 5 show various changes in the area reduction rate of each hole die. FIG. 5 is a view showing that no breakage occurs when the reduction rate of each hole die is equal to or less than a possible limit reduction rate when a flux-cored wire is drawn.

FIG. 4 shows an example in which wire drawing is performed with a reduction rate of a gradually decreasing type condition in which the reduction rate of each hole die at the time of wire drawing is gradually reduced. If it was less than the critical area reduction rate, no disconnection occurred during wire drawing. In FIG. 5,
Initially, the soybean area reduction rate at the time of wire drawing is set to a large area reduction rate,
Thereafter, when the total area reduction rate is 70% or less, wire drawing is performed at a constant area reduction rate, and when the total area reduction rate is 70% or more, wire drawing is performed at the area reduction rate under conditions that gradually reduce the area reduction rate. If the area reduction rate was less than the possible limit area reduction rate, no disconnection occurred during wire drawing.

From the experimental results shown in FIGS. 4 and 5, although the conventional total reduction in area was particularly 70% or more, wire breakage was likely to occur during the drawing of a small-diameter flux-cored wire. It was found that no breakage occurs during wire drawing when the area reduction rate is less than the critical area reduction rate.

By finding this possible limit area reduction rate, it is possible to perform wire drawing at a high total area reduction rate exceeding 70% or 80%, for example, without disconnection. Was. As a result, disconnection tends to occur particularly during wire drawing.
Even when a thin flux-cored wire having a diameter of 6 mm or less is drawn, the area reduction rate of each hole die can be easily set under the condition that disconnection does not occur.

In the present invention, the diameter of the flux-cored wire before drawing is suitably 2 to 5 mm. That is, when the wire diameter of the flux-cored wire is less than 2 mm, three-roll drawing of the primary drawing cannot be performed. The wire diameter of the flux-cored wire is 5 m.
If it exceeds m, the total area reduction rate until the wire is drawn to a desired product diameter increases, the work hardens, and the wire is easily broken, so the wire strand diameter is preferably 2 to 5 mm.

In the present invention, in order to improve the welding efficiency by increasing the amount of the deposited metal, it is necessary that the iron powder ratio of the filling flux be 10% or more. However, when the iron powder ratio increases, the slag agent and the deoxidizing agent relatively decrease, and workability and weld metal performance are not satisfied during welding. Therefore, the iron powder ratio of the filling flux is set to 10 to 60%.

The filling of the flux is necessary for increasing the amount of the deposited metal and improving the welding workability. The flux filling rate of the present invention is from 15 to 25% by weight from the viewpoint of the welding workability. did.

[0026]

[Example] Outer diameter 12-18mm, wall thickness 1.5-2.0m
A steel pipe (JIS G3445STKM11A) is granulated with water glass using fluxes having different iron powder rates, dried and sized, vibration-filled to a target filling rate, primary-drawn by three-roll drawing, and copper plated after annealing. Wire. After that, the outer diameter is 3.
An element wire of 2 to 5.2 mm was continuously drawn to a product diameter of 1.2 to 1.6 mm with a cone type wet drawing machine using 13 to 18 hole dies.

The drawing speed was 1000 in the final hole die.
mpm, and an emulsion type lubricant containing an ester, a fatty acid, a metal soap and an anionic activator as main components was used as a lubricant.

In each test, the wire reduction rate of each hole die was variously changed, and in each test, the wire was drawn by 5 tons for each wire, and the presence or absence of breakage was examined.
They are summarized in Tables 1 and 2.

[0029]

[Table 1]

[0030]

[Table 2] In Tables 1 and 2, No. 1 to No. No. 3 is an example of the present invention;
4-No. 8 is a comparative example.

No. 1 of the present invention. 1 to No. 3 is that the reduction rate of each hole die is smaller than the possible limit reduction rate (R), and the flux filling rate and the iron powder rate are also appropriate.
There was no disconnection during wire drawing.

In the comparative examples, No. 4 is the total area reduction rate of 74.7
%, The area reduction rate of each hole die exceeded the possible limit area reduction rate (R).

No. In No. 5, the area reduction rate of each hole die was set to a gradual reduction type. However, since the total area reduction rate was 80.9%, the area reduction rate of each hole die exceeded the possible limit area reduction rate (R). Disconnection occurred when the wire was drawn for 3 tons.

No. No. 6 has a high flux filling rate. In No. 7, since the ratio of iron powder in the filling flux was high, the wire was broken when approximately 4 tons were drawn.

No. In No. 8, since the wire diameter exceeds 5 mm, the total area reduction rate at the final diameter is high, and the area reduction rate of each hole die is 72% to 80.4% when the total area reduction rate is 72% to 80.4%. However, since the maximum area reduction rate (R) was exceeded, the wire was broken when approximately 3 tons were drawn.

In the above embodiment, a cone-type wet continuous wire drawing machine was used. However, similar results were obtained in other wire drawing machines, for example, a storage-type arrow tandem wire drawing machine. Further, the present invention can be similarly applied to a non-plated wire not subjected to copper plating or a flux-cored wire for stainless steel.

[0037]

According to the present invention, it is possible to eliminate breakage at the time of wire drawing without lowering the wire drawing speed when manufacturing a fine flux cored wire having a high flux filling rate and a high iron powder rate of the filled flux. it can. Therefore, the productivity of the flux-cored wire can be improved.

[Brief description of the drawings]

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a view showing conditions of a reduction in area for each hole die generally performed in wire drawing.

FIG. 2 is a diagram showing a relationship between a wire total area reduction rate and a wire elongation rate during wire drawing.

FIG. 3 is a diagram showing a relationship between a total area reduction rate (X) and a possible limit area reduction rate (R) of each hole die.

FIG. 4 is a diagram showing the relationship between the reduction rate of each hole die and the possible limit reduction rate in a drawing example in which the reduction rate of each hole die is gradually reduced.

FIG. 5 is a diagram showing the relationship between the reduction rate of each hole die and the possible limit reduction rate in a drawing example in which the reduction area of each hole die is a combination of a fixed type and a gradually decreasing type.

Claims (2)

[Claims] In a method for continuously drawing a thin flux-cored wire using a plurality of hole dies, the area reduction rate of each hole die is determined by the following formula.
A wire drawing method for a small-diameter flux-cored wire, which is performed by the following method. Possible limit reduction (R) = 33.7-0.13X-0.0
02X ² X in the above formula means the total area reduction rate. 2. The method according to claim 1, wherein a wire diameter of the flux-cored wire before drawing is 2 to 5 mm, a flux filling rate is 12 to 25%, and an iron powder rate of the filling flux is 10 to 60%. A wire drawing method for the fine-diameter flux-cored wire described above.