JPS6217160A - Hot dipping method - Google Patents

Abstract

PURPOSE:To produce a molten metal plated wire having a thick plating layer by activating the surface of a core material such as copper wire with a flux then forming the 1st molten metal plating layer thereon, cooling the plated wire with a non-oxidizing refrigerant and forming the 2nd molten metal plating layer. CONSTITUTION:The core material 1 consisting of Cu, etc. is passed through a flux treating vessel 2 to clean up and activate the surface of the material 1 and thereafter the core material is passed through the inside of the 1st molten metal bath 3 consisting of molten Sn, etc. to form the thin hot dipping layer of Sn on the surface of the material 1. The non-oxidizing cooling medium of an extremely low temp. generated from liquid nitrogen, etc. is passed through a cooling pipe 4 into which the medium is fed through an inlet 9 and from which the medium is discharged from an outlet 10 to non-oxidizingly cool the core material to the temp. lower by >=200 deg.C than the temp. of the 2nd molten metal both 5 (melt of Sn or other metal). The core material is passed through the inside of the 2nd molten metal bath 5, by which the plating film consisting of the molten metal having the larger thickness and uniform quality is formed thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for manufacturing composite materials, in which a core material is immersed in a molten metal bath and a sheath metal is coated around the core material. This invention relates to a hot-dip plating method that allows metal coating.

<Prior art> As a method of obtaining a composite material with a thick coating by hot-dip plating, the residence time of the core material in the molten metal bath is shortened, and the molten metal is solidified and attached around the core material and removed from the bath. There is a way to raise it.

In this case, it is necessary to pull out the coated solidified metal adhering to the core material from the molten metal bath before it melts again. For this purpose, it is necessary that the temperature of the core material be low, the linear velocity of the core material be high, and the distance of the core material in the molten metal be short.

However, it is quite difficult to obtain good adhesion between the core material and the solidified metal during such short immersion times. For this reason, a method is used to pre-treat the core material to ensure good adhesion between the core material and solidified metal, and generally wet pre-treatment (pickling, fluxing) is performed.

However, when the core material that has been subjected to such wet fluxing is placed in a molten metal bath, the flux adhering to the surface of the core material causes bubbling, and as the core material is pulled up from the molten metal, it forms on the surface of the molten metal. This has the disadvantage that it disturbs the meniscus and makes the plated surface of the core material uneven.

In order to prevent such flux bubbling from occurring at the meniscus portion of the molten metal surface, it is possible to increase the immersion distance of the core material in the molten metal, but this increases the temperature of the core material, Thick metal coatings are not possible.

<Problems to be Solved by the Invention> An object of the present invention is to provide a hot-dip plating method that eliminates the drawbacks of the prior art described above and can produce a composite wire rod having a thick metal coating with good surface condition. It's about doing.

Means for Solving the Problems> The present invention provides a hot-dip plating method in which a core material is passed through a molten metal bath and a sheath metal is coated around the core material to produce a composite material. After passing the core material through a liquid flux bath to be oxidized, the core material is passed through a first molten metal bath to produce a wire coated with molten metal, and this wire is then passed in a non-oxidizing atmosphere. , is a hot-dip plating method characterized by performing hot-dip plating through a second molten metal bath after cooling to a temperature 200° C. or more lower than the bath temperature of the second molten metal bath.

Here, it is preferable that the cooling step is performed using a liquefied non-oxidizing gas.

Further, it is preferable that the core material is a copper wire and that both of the molten metal baths are molten tin baths.

The present invention will now be described in detail with reference to preferred embodiments shown in the drawings.

FIG. 1 shows a process chart for manufacturing a composite material using the hot-dip plating method of the present invention.

The core material 1 is fed out by a feeding device 7, wound up by a winding device 8, and plated by passing through a plating line at a desired line speed. A flux treatment tank 2, a first molten metal bath 3, a cooling pipe 4, and a second molten metal bath 5 are arranged in this order in the plating line.

The core material 1 used in the method of the present invention may be any metal filament made of a composite raw material, but Fe material,
Wires, strips, etc. of Cu materials and alloys thereof are used.

Before entering the plating process, the core material 1 is subjected to known general pretreatments such as annealing, degreasing, pickling, and water washing, as necessary.

The flux treatment in the flux treatment bath 2 is to keep the surface of the core material clean and to activate it, thereby facilitating the reaction between the core material 1 and the molten metal in the molten metal bath 3.

For this purpose, an appropriate flux is used depending on the material of the core material and the metal to be plated.

Flux treatment NI! If necessary, a preheating tank or the like may be provided between the core material 1 and the first molten metal bath 3 to heat the core material 1.

For the first molten metal bath 3 and the second molten metal bath 5, ordinary hot-dip plating baths are used, and appropriate plating baths are selected depending on the type of hot-dip metal, the amount of treatment, pulling method, heating method, etc. A dipping roll 11 is provided in the hot-dip plating tank, and the dipping roll 11 preferably has a groove so that the core materials 1 do not come into contact with each other, and is configured to rotate smoothly to feed the core material 1 in the plating tank. .

Conventionally, when core material l that has been subjected to wet flux treatment is placed in a molten metal bath, the flux adhering to the surface of the core material causes bubbling, and is formed on the surface of the molten metal when the core material is pulled up from the molten metal bath. This disturbs the meniscus and makes the plating surface of the core material uneven. In order to prevent this flux bubbling from occurring at the meniscus on the molten metal surface, it is possible to increase the immersion distance of the core material in the molten metal, but this increases the temperature of the core material and causes thick metal plating. It was impossible.

In order to overcome the drawbacks of the conventional method, in the present invention, the core material 1 is subjected to flux treatment in a flux bath 2 as a preliminary treatment, and then the core material 1 is coated with a thin layer of the intended coating metal in a first molten metal bath 3. After forming the coated core material to which the layer is attached, the coated core material 1 is immediately cooled in a non-oxidizing atmosphere to a temperature lower than the bath temperature of the second molten metal bath 5 by 200°C or more, and then in the second molten metal bath. This method involves immersion for a short period of time.

The cooling step in a non-oxidizing atmosphere between the first molten metal bath 3 and the second molten metal bath 5 is preferably performed using a cooling pipe 4 shown in FIG. The cooling pipe 4 has a population of coated core material 1 in a first molten metal bath 3 and a population of coated core material 1 in a second molten metal bath 5.
It is a tube having an outlet and a cavity therein through which the coated core material 1 passes, and has a feed roll 12 inside, so that the core material 1 can be fed at an appropriate speed. The cooling pipe 4 is also provided with a coolant outlet 10 at an appropriate distance from the surface of the first molten metal bath 3;
In the second molten metal bath S, a cooling medium 9 was provided near the outlet of the coated core material 1, and the temperature was increased in the first molten metal bath 3 by flowing the coolant in the passing direction of the coated core material 1 and in the self-current direction. It is preferable that the temperature of the coated core material 1 is 200° C. or more lower than the bath temperature of the second molten metal bath 5. Coolant type, flow path direction, flow velocity, population 9. The position of the outlet 10 and the length of the cooling pipe are appropriately selected depending on the type of molten metal, the type of core material, and the core material feed rate.

The coolant is preferably a non-oxidizing gas, and it is particularly preferable to use a liquefied non-oxidizing gas. If a non-oxidizing liquefied gas is used, the temperature of the core material 1 will be 200° lower than the temperature of the second molten metal bath 5 before entering the second molten metal bath 5.
This is because it becomes possible to lower the temperature by more than 0.degree. C. in a short time. A typical example thereof is liquefied nitrogen gas.

The reason why the temperature of the coated core material 1 entering the second molten metal bath 5 needs to be lowered to 200°C or more lower than the temperature of the molten metal bath is because if the temperature of the coated core material 1 is higher than this temperature, the temperature around the coated core material 1 This is because the thickness of the metal layer that solidifies becomes thinner.

In addition, the reason why the coated core material 1 leaving the first molten metal bath 3 is cooled in a non-oxidizing gas is that when the surface of the coated core material 1 is oxidized, it can be immersed for a short time in the second molten metal bath 5. This is because the adhesion between the core material and the molten metal is poor, and the adhesion between the core material and the coating metal is poor.

The metals in the first molten metal bath 3 and the second molten metal bath 5 may be the same or different, but when producing a composite material with a thick metal coating and a good surface condition, The first molten metal bath 3 and the second molten metal bath 5 are the same metal bath, the metal plating layer in the first molten metal bath 3 is a thin plating layer, and this coated core material is properly coated without exposing it to an oxidizing atmosphere such as air. and then the second molten metal bath 5 for as short a time as possible.
It is preferable to thicken it by dipping it in water.

By doing this, the meniscus formed when the coating core l is pulled up on the surface of the second molten metal bath 5 is not disturbed by flux bubbling, and a thick composite material 6 with a good surface condition can be manufactured. .

When the first molten metal bath 3 and the second molten metal bath 5 are dissimilar metal baths, for example, a solder metal bath with steel as the core material or a composite material with tin metal can be used, and these can also be manufactured in the same manner as above. can do.

A known aperture or cooling device (not shown) is provided near the molten metal surface of the second molten metal bath 5 to manufacture the composite material 6.

The manufactured composite material 6 is wound up by a winding device 8.

Practical example Hereinafter, the present invention will be specifically explained with reference to Examples.

Example (1) A 2 mmφ Cu wire was used as the core material, pretreated with hydrochloric acid flux, and then placed in the first molten tin bath 3 at 250°C.
It was cooled in a non-oxidizing gas N2 atmosphere, then put into the second molten tin bath 5 at 250° C. again and pulled up. Figure 1 shows an outline of the line. Tables 1, 2, and 3 show the coating thickness, adhesion, and surface condition of the composite materials produced using the apparatus shown in FIG.

The coating thickness was determined by measuring the cross section using a microscope with a magnification of 100 times, and the adhesion was determined by performing a bending test using a mandrel with a radius of 4 mm to determine the number of times it took for the coating layer to crack. The surface condition was investigated using a stereomicroscope with a magnification of 20 times.

Table 1 shows the cooling between the first molten metal bath and the second molten metal bath.
The test results of the composite material are shown when the test was performed using two gases, when the test was performed using air, and when the test was performed using liquid N2. In both cases, the temperature of the core material was 25° C. in the second molten metal bath. When cooled with air, the surface condition and adhesion are significantly poor.

Table 1 shows that it is necessary to lower the cooling temperature sufficiently and to use a non-oxidizing gas as the coolant.

Table 2 shows the results when the first molten metal bath was not passed and when it was passed. If it is not passed through the first molten metal bath, bubbling will occur even if the core material whose temperature has been sufficiently lowered is placed in the molten metal bath after flux treatment. Adhesion and surface condition are very poor.

Table 3 shows the test results when the temperature of the facing core material entering the second molten metal bath was varied. The temperature of the coated core material was varied by controlling the temperature of the liquefied N2 liquid in the cooling tube 4.

The temperature of the coated core was measured with an adhesive thermometer. When the temperature of the coated core material reaches 50° C. or higher, the coating thickness becomes thinner.

Table 1 Table 2 Table 3 <Effects of the invention> When a composite material is manufactured by the hot-dip plating method of the present invention,
It is possible to obtain a thick coating layer with a good surface condition that could not be obtained with conventional plating methods, and it is now possible to manufacture composite materials with greatly improved corrosion resistance and conductivity at high speed and with relatively simple equipment, increasing productivity. This greatly contributes to the improvement of

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the hot-dip plating method of the present invention. Explanation of symbols

Claims (3)

[Claims] (1) In a hot-dip plating method in which a composite material is produced by passing the core material through a molten metal bath and covering the core material with an outer metal, the core material is placed in a liquid flux bath that cleans and activates the surface of the core material. After passing the core material through a first molten metal bath to produce a wire coated with molten metal, the wire is then heated in a non-oxidizing atmosphere to a bath temperature of a second molten metal bath. A hot-dip plating method characterized in that after cooling to a temperature 200° C. or more lower than the above temperature, hot-dip plating is performed through a second molten metal bath. (2) The hot-dip plating method according to claim 1, wherein the cooling step is performed using a liquefied non-oxidizing gas. (3) The hot-dip plating method according to claim 1 or 2, wherein the core material is a copper wire, and both of the molten metal baths are molten tin baths.