JPH02258157A - Dip forming method - Google Patents

Abstract

PURPOSE:To execute a stable long time operation by forming a core wire inserting hole of a ceramic-made nozzle and making space for inserting the core wire to inert gas atmosphere of the specific pressure after cleaning the surface thereof at the time of sticking and solidifying after dipping the core wire into molten metal in a crucible. CONSTITUTION:The core wire inserting hole 2 is formed of the ceramic-made nozzle, and the cleaning means for cleaning the core wire with a peeling die 6 is provided. The atmosphere in the space from this cleaning means to the ceramic-made nozzle for core wire inserting hole 2 in the crucible 1, is made to the inert gas or reducing gas atmosphere having >=5mmH2O and <=100mmH2O gage pressure. By this method, the molten metal 9 in the crucible is effectively prevented from being involved at between the inner face of the core wire inserting hole and the core wire, and the core wire inserting hole is not broken, and the core wire is not cut, and stable operation can be operated. Further, the defect of blow hole, etc., in combined wire rod as the product is not developed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to the tip-forming method applied to the production of composite wire rods such as copper-coated steel wire rods. BACKGROUND ART A dip coating formation method known as a dip forming method has been put into practical use for manufacturing composite wires having a coating layer made of an alloy formed thereon. In this tip forming method, a seed wire is dipped into a molten metal such as copper, and the immersed seed wire is pulled up from the molten metal, thereby causing the molten metal to adhere and solidify around the seed wire. An example of an improved forming method is proposed in Japanese Patent Application No. 58-235262. An example of an apparatus used in this improved dip forming method is shown in FIG.

In FIG. 1, a seed wire insertion port 2 is formed at the bottom of a crucible 1 made of a refractory material such as graphite, and a seed wire insertion port 2 is provided with a seed wire 3 whose surface has been cleaned from below. are inserted continuously. That is, after the surface of the seed wire 3 such as a steel wire is cleaned by surface cleaning means such as a peeling die 4, the seed wire 3 is continuously inserted into the seed wire insertion port 2 via the capstan 5 and the preheater 6. Moreover, the seed wire 3 between the peeling die 4 and the seed wire insertion port 2 is surrounded by a housing 7, and the inside of this housing 7 is connected to an external exhaust gas (not shown) through an exhaust port 8. Means is used to evacuate and maintain a substantially vacuum. On the other hand, the crucible 1 includes a holding furnace 10 that holds a molten metal 9 for coating such as pure copper or molten copper alloy, and a transfer pipe 11.
A cooling tower 12 is provided above the crucible 1.

In such a deep forming device, a seed wire 3 such as a steel wire is peeled by a peeling die 4 to have its surface cleaned, and then fed into the housing 7 where it is oxidized in a vacuum atmosphere. While being prevented, it is preheated by the preheater 6 via the capstan 5, continuously inserted into the crucible 1 from the seed wire insertion port 2, and further pulled upward and passed through the cooling tower 12. On the other hand, molten metal 9 such as pure copper or molten copper alloy is continuously supplied into the melt 1 from a holding furnace 10 via a transfer pipe 11 . Therefore, the seed wire 3 inserted into the crucible 1 is continuously immersed in the molten metal 9 and then continuously pulled up from the molten metal, and at this time, the molten metal 9 adheres around the seed wire 3, The molten metal around the seed wire solidifies in the cooling tower 12, thereby obtaining a composite wire 14 in which a coating layer made of copper or a copper alloy is formed around the seed wire.

In addition, in the dip forming device as described above,
Generally, a molybdenum-based alloy is often used for the seed wire insertion port 2 because heat resistance and wear resistance are required for the seed wire insertion port 2 of the metal wire 1.

Problems to be Solved by the Invention When manufacturing copper-coated steel wire using the conventional tip forming apparatus as described above, there are the following problems. In other words, in this case, a steel wire is used as the seed wire, but if a molybdenum-based alloy is used for the seed wire insertion port of the crucible, the affinity between Fe and Mo is high, so the seed wire is used as the seed wire insertion port. Seizing occurs gradually as the wire passes through, and eventually it becomes impossible to pass at the specified line speed, and the seed wire buckles before the seed wire insertion port, resulting in a situation where further operations are impossible. Sometimes.

As a method to avoid the occurrence of such a situation, it has already been proposed in Japanese Patent Application No. 110126/1983 that the material of the seed wire insertion hole should be made of silicon nitride (Si3), which has excellent seizure resistance and thermal shock resistance.
It has been proposed to change to N4) based ceramics. If silicon nitride-based ceramic is used for the seed wire insertion port in this way, the risk of seizure occurring even when using a steel seed wire is significantly reduced, but in that case, another problem will arise. It turns out that it does.

That is, the seed wire insertion port of the crucible is generally formed by a nozzle 21 forming the seed wire insertion port 2, as shown in an enlarged view in FIG.
is attached to the bottom of the crucible body 1A, and the nozzle hole of the nozzle 21 has a lower part on the seed line insertion side that is connected to the seed line 3.
Normally, a tapered part 21A is used to guide the diameter, and the upper part is made an equal diameter part 21B. Here, nozzle 2
When No. 1 is made of silicon nitride ceramic as mentioned above, its thermal conductivity is much lower than that of MO-based alloy, so the molten metal inside No. 6 is formed between the outer peripheral surface of the seed wire and the inner surface of the nozzle. Easy to insert. In other words, if the nozzle has a high thermal conductivity such as an MO-based alloy, the molten metal inserted into the gap between the inner surface of the nozzle and the outer peripheral surface of the seed wire will immediately solidify due to the heat dissipation and cooling effects of the nozzle, and the solidified metal will become the seed wire. As the metal adheres to the wire, it returns to the crucible as it travels above the wire and is remelted, so there is no chance of molten metal penetrating into the taper at the bottom of the nozzle. . However, when a material with low thermal conductivity such as silicon nitride ceramic is used for the nozzle, the heat dissipation and cooling effect in the nozzle is poor, so the molten metal inserted between the area around the seed wire and the inner surface of the nozzle may reach a part of the taper. If the molten metal solidifies in a part of the taper, the solidified part becomes a mock test along the inner surface of the taper part, so the horizontal solidified part adheres to the periphery of the seed line and runs on the seed line. If the ceramic nozzle is pulled upwards, the nozzle may be destroyed or the seed wire may be broken, making it impossible to continue the operation.

This defense was made against the background of the above circumstances.When the seed wire insertion port in Rutsuho is formed with a ceramic nozzle, the inner surface of the nozzle, that is, between the inner surface of the seed wire insertion port and the seed wire. 4. Prevent the molten metal in the crucible from entering the gap to prevent damage to the nozzle or breakage of the seed wire.
The purpose of this invention is to provide a dip forming method that avoids

Means for Solving the Problems In order to solve the above-mentioned problems, in the dip forming method of the present invention, the material is removed from the outside of the seed wire insertion opening of the crucible (the side where the seed wire is inserted). A predetermined pressure was applied using active gas or reducing gas.

Specifically, the present invention continuously cleans the surface of the seed wire by a surface cleaning means, and continuously inserts the cleaned seed wire into the crucible from the seed wire insertion opening of the crucible. In the dip forming method in which the molten metal is immersed in molten metal in a crucible to adhere and solidify around the seed wire, the seed wire insertion opening is formed by a ceramic nozzle, and the seed wire is inserted from the surface cleaning means. The atmosphere in the space leading up to the mouth must be maintained at a gauge pressure of 51 mH2O or more 10
(It is characterized by an inert gas or reducing gas atmosphere with a pressure of 1 mInH20 or less.

Operation In the conventional dip forming method, the inside of the housing 7 shown in FIG. The total pressure of the pressure corresponding to the depth of the molten metal in the crucible and the external pressure (1 atmosphere) was applied to the space. In other words, since there is usually 800rntn in the crucible, in the case of pure copper molten metal, about 0.7 atm is added due to the height of the melt, and when compared to vacuum, about 1.7 atm is added. It means that you are joining. In this way, in the conventional method, a large pressure of approximately 1.7 atmospheres was applied from the molten metal in the crucible to the vacuum atmosphere outside the seed wire insertion port, and as mentioned above, the inner surface of the seed wire insertion port The depth at which the molten metal was inserted into the gap between the outer circumferential surface of the seed wire and the outer circumferential surface of the seed wire was increased.

Therefore, in manufacturing copper-coated steel wire, the present inventors installed an apparatus (not shown in FIG. As a result of investigating the relationship between the above, it was found that when the pressure inside the housing 7 was less than 5 sH20 (gauge pressure), molten metal was inserted into the seed wire insertion port, leading to a shutdown of the operation.

It was also found that by setting the gauge pressure to 5111#1H20 or higher, insertion of molten metal into the seed wire insertion port did not substantially occur.

On the other hand, when the pressure inside the housing 7 was further increased,
It has been found that if the gauge pressure exceeds 10011111H20, a crater-like defect called a blowhole will occur in the copper coated layer of the produced copper coated fI4 wire. The mechanism of this blowhole is that gas trapped in minute irregularities on the surface of the steel wire (for example, irregularities caused by the wires rubbing against each other in a capstan, impressions from pinch rolls, etc.) blows the molten copper. As the wire passes through, it acts as an insulator and delays the solidification of the copper that adheres to it, and even when the wire emerges from the hot water surface in the crucible, it does not solidify, and the pressure of the trapped gas pushes off the unsolidified copper, causing an eruption. This is thought to result in a mouth-like defect. As mentioned above, if the gas pressure on the housing 7 side exceeds the gauge pressure 100111#IH20, f! It is thought that gas entrainment due to minute irregularities on the surface of the A-line becomes more likely to occur, and as a result, blowholes are less likely to occur.

From the above, the pressure outside the seed wire insertion port is 5r in gauge pressure.
By setting Rm within the range of 120 to 100 H20, it is possible to prevent blowhole defects from occurring and to prevent molten metal from being inserted into the gap between the inner surface of the seed wire insertion port and the outer surface of the seed wire. This makes it possible to effectively prevent the nozzle of the insertion port from being destroyed or disconnected due to solidification of the inserted molten metal within the insertion port.

Note that the type of atmosphere gas outside the seed wire insertion port is arbitrary if only the problem of insertion is considered, but from the viewpoint of preventing oxidation of the seed wire, it is necessary to use an inert gas or reducing gas atmosphere. In addition, this oxidation prevention must be carried out after the seed wire has been cleaned by peeling, etc. Therefore, in the present invention, the atmosphere between the cleaning means and the seed wire insertion port is maintained at a predetermined pressure as described above. An inert gas or reducing gas atmosphere is used.

EXAMPLE An example in which a copper-coated steel wire was manufactured according to the method of the present invention using an apparatus as shown in FIG. 1 will be shown below.

Note that silicon nitride ceramic was used for the nozzle of the seed wire insertion port.

[Example 11 A 0.08% C 7mmφ steel wire is used as a seed wire, the inside of the housing 7 is filled with N2 gas, and the pressure is set to 20sH20 by gauge pressure, and the hot water length in the crucible 1 is 800mm. An operation was carried out to manufacture a copper-coated steel wire in which copper was deposited and solidified on the surface of an 8Ilil wire by continuously running the steel wire while supplying pure copper molten metal. As a result, it was confirmed that stable operation could be carried out for a long period of time exceeding 10 hours, and that there were virtually no defects such as blowholes in the copper-coated steel wire of the product.

[Example 2] N2 gas + 4% CO gas + 1% inside the housing 7! ”
Fill with a mixture of two gases and set the pressure to a gauge pressure of 20s.
When the operation was carried out under the same conditions as in Example 1, the operation was carried out under the same conditions as in Example 1. As in Example 1, the operation was stable for a long time exceeding 10 hours, and there were no blowholes etc. in the product. TIfl found that virtually no defects occurred.

Although copper was used as the seed wire in the above examples, the same effect can be obtained by using Fe-Ni alloy or Fe-Cr alloy as the seed wire, or by using a copper alloy as the molten metal. Of course. Furthermore, although silicon nitride ceramic is used as the nozzle material for the seed wire insertion port in the above-described embodiment, other ceramics may also be used.

Effects of the Invention According to the dip forming method of the present invention, the atmosphere in the space between the cleaning means for cleaning the seed wire by peeling etc. and the ceramic nostle that forms the seed wire insertion opening of the crucible is reduced. , with a gauge pressure of 5 mm H2O or more 10
Since the atmosphere is an inert gas or reducing gas at a pressure below 0 mm H20 Jul, the molten metal in the crucible is effectively prevented from being inserted between the inner surface of the seed wire insertion port and the seed wire, and therefore the seed wire is not inserted. Stable operation can be carried out for long periods of time without causing situations such as the wedge-shaped metal solidified at the opening causing damage to the seed wire insertion port or breakage of the seed wire as the seed wire runs. .

In addition, the tip-forming method of the present invention does not cause defects such as blowholes in the composite wire of the product.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view schematically showing an example of an apparatus used in the dip forming method, and Fig. 2 is a longitudinal cross-sectional view showing an example of the situation near the seed line insertion port in the conventional dip forming method. be. 1... Crucible, 2... Seed line insertion port, 21...
Nozzle, 3... seed line, 4... peeling die as a surface cleaning means, 7... housing, 9...
molten metal.

Claims (1)

[Scope of Claims] The surface of the seed wire is continuously cleaned by a surface cleaning means, and the cleaned seed wire is continuously inserted into the crucible from the seed wire insertion opening of the crucible. In the dip forming method in which the molten metal is immersed in molten metal to adhere and solidify around the seed wire, the seed wire insertion opening is formed with a ceramic nozzle,
And the atmosphere in the space between the surface cleaning means and the seed wire insertion port is maintained at a gauge pressure of 5 mmH_2O or more 10
A dip forming method characterized by using an inert gas or reducing gas atmosphere at a pressure of 0 mmH_2O or less.