JPS5847259B2 - Rhizokuchiyuzoyoukanagatanoseizouhohou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a continuous casting mold, and in particular, when a strong wear resistance is required on the inner wall surface of the continuous casting mold, a hard chromium plating layer is applied. This invention relates to an improvement in the manufacturing method of continuous casting molds manufactured by the same method.

The applicant has already published a patent application for this type of mold in 1982-2825 with the aim of providing a mold that has good thermal conductivity, can withstand thermal stress and mechanical wear, and has excellent cooling performance and durability.
We have just proposed the invention related to No. 5.

The gist of this method is to form a copper mold body and then apply nickel plating to the inner surface of the hollow part of the casting mold. For the purpose of obtaining strong wear resistance, hard chromium plating with an HV hardness of about 900 to 1000 is sometimes applied to a thickness of about 50 microns on this nickel plating layer.

However, when manufacturing such molds, due to the general phenomenon of electroplating, the length direction or cross section of the casting hollow part,
For example, in the case of a polygonal item, there is a deviation in film thickness at the corners and sides, and in order to obtain dimensional accuracy of the mold, the hard chrome plating is electrodeposited in advance to about 60 μm, and this is polished to achieve dimensional accuracy. I always try to finish it at 50μ.

Therefore, this polishing operation requires a skilled polishing technique and a lot of time, and has the disadvantage of poor workability and cost.

Therefore, the inventors of the present invention have succeeded in solving the above-mentioned drawbacks by manufacturing this type of mold by applying electroforming technology to the conventional manufacturing technology.

In other words, by applying hard chrome plating to the surface of the mother mold, the dimensional accuracy of the casting hollow part of the copper mold body formed in the subsequent stage can be improved depending on the molding accuracy of the mother mold. This method is possible, and can solve the reason why the dimensional accuracy cannot be improved by electrodeposition of the chromium plating layer in the method described above.

In addition, if it is necessary to control the thickness of the chrome plating layer according to the wear resistance required for the mold, it is difficult to achieve thick plating using the above method. However, according to the present invention, it is possible to control the thickness of the film by controlling the deviation in film thickness when applying chrome plating to the mold body. Since it has no bearing on the internal dimensional accuracy of the plate, thick plating is possible, and the film thickness can be freely selected as required.

Moreover, since the mold body manufactured according to the present invention has excellent internal dimensional accuracy, the friction caused by oscillation when pulling out the slab from the casting hollow part during continuous casting work is reduced, and the life of the mold is extended. can do.

Furthermore, in the method of the present invention, nickel flashing plating is performed prior to electrodeposition of the nickel plating layer on the chromium plating layer, and copper-plating is performed prior to electrodeposition of the copper plating layer on the nickel plating layer. By applying a nickel plating layer and subjecting it to heat treatment, it is possible to promote the formation of a diffusion layer between the nickel plating layer and the copper plating layer, and to make the adhesion between each electrodeposition layer firm. I can do it,
It is possible to further lengthen the casting metal of the momentum mold.

In particular, by interposing a copper-nickel plating layer between the nickel plating layer and the copper plating layer, the manufacturing time can be greatly shortened compared to the case where the same layer is not interposed. This has been discovered through examples.

In other words, if copper is simply plated on a nickel plating layer, only a 100μ diffusion layer can be obtained by heat treatment at 700°C for 4 to 6 hours. When a nickel-plated alloy layer is used as an intervening layer, a diffusion layer of 600 μm can be obtained in 30 to 60 minutes at 700° C., and it is clear that the desired objective can be achieved in a very short time.

Experimental Example 1 After applying 1.5 mm of nickel plating scrap to the surface of the mother mold using the following plating bath and conditions, and applying a layer of 4.5 to 6.5 mm of copper plating (see Figure 1), By heat treating this at 700 DEG C. for 4 to 6 hours, a 100 micron diffusion layer could be formed between the nickel plating scraps and the copper plating layer (see FIG. 2).

Nickel plating plating bath Nickel sulfur amino acid 450 g/l Boric acid 30 g/l Sodium lauryl sulfate 0.1 g/l Plating conditions Cathode current density 4 Mdrr? bath
Temperature 60°CPH0.4 Stirring Cathode rocker Copper plating bath with air stirring Copper sulfate 200,! 9/l! Sulfuric acid 50 g/i! Plating conditions Cathode current density 5 A/drr? Bath temperature 20-23°C Stirring Cathode rocker with air stirring Experimental example 2 Nickel plating waste was electrodeposited on the surface of the mother mold under the same conditions as in Practical Example 1 above, and the following was applied on the nickel plating waste. Depending on the plating bath and conditions, a copper/nickel alloy plating layer of 50-60 μm (synthetic composition is nickel-48-8
After electrodepositing 6% copper (copper-14 to 52), a copper plating layer was electrodeposited on this copper-nickel alloy plating layer 2 under the same conditions as in Experimental Example 2 (see Figure 3). Thereafter, by heat treating this at 700 DEG C. for 30 to 60 minutes, a 600 micron diffusion layer was formed between the nickel plating scraps and the copper plating layer (see FIG. 4).

Copper/nickel plating plating bath Copper sulfate 0.79/1 Nickel sulfate 10g/l citric acid
50fl//1 cyanide soda
L5g/11 Ammonia Small amount Plating conditions Current density 0.5-2.5A/d? ? Z2 bath warm
40-80℃ PH alkaline example The matrix is a stainless steel square bar (width: 8011L, height: 801L)
1!7I! , length 800ii) with taper angle O11°
Use boxwood with a mirror-polished surface.

Then, as shown in FIG. 5, the mother mold 1 was suspended and set in a plating bath 2 having the following plating bath composition, and chrome plating was applied under the following plating conditions to coat the surface of the mother mold 1 with a thickness of 50 μm. A chromium plating layer 10 is electrodeposited.

After electrodeposition of this chrome plating layer 10, necessary treatment is performed,
In the future, after performing nickel flashing plating under the following plating bath composition and plating conditions (not shown), nickel plating with 1.5 peaks will be applied on the same electrodeposited layer under the plating bath composition and plating conditions of Experimental Example 1. At the same time, 50 to 60 micron copper-nickel plating was applied on this nickel plating layer 11 under the plating bath composition and plating conditions of Experimental Example 2 above, and further, on this copper-nickel plating layer 12, the plating of Experimental Example 1 was applied. One layer of copper plating is applied under the bath composition and plating conditions.

Further, after the copper plating layer 13 is electrodeposited, the copper plating layer 13 is
After forming a diffusion layer between the nickel plating layer 11 and the copper plating layer 13 by heat treatment for ~60 minutes, the outer mold dimensions required for the continuous casting mold to be manufactured in advance are determined as shown in FIG. and installed in a mold 15 formed in the shape,
By casting molten steel or brass between the mold 15 and the copper plating layer 13, a cast copper or brass layer 14 can be formed on the outer surface of the copper plating layer 13.

Therefore, after cooling, the mother mold 1 can be taken out from the mold 15 and the continuous casting mold A in the state shown in FIG. 7 can be manufactured. After machining, etc.), a mold for continuous casting can be manufactured by pulling out the mother mold 1 by an appropriate means.

However, prior to the nickel flashing plating after the chromium plating, there is a thin oxide film on the chromium plating layer 10, which will cause poor adhesion of the nickel flashing plating, so anodic electrolysis is performed. It is desirable to perform this after removing the thin oxide film on the chrome plating layer 10.

In addition, when drawing out the mother mold 1, it is also possible to melt the mother mold chemically. In this case, an aluminum pipe is used instead of the stainless steel square rod, and each of the above After forming the plating layer and the casting layer, it is also possible to dissolve the aluminum matrix in a caustic soda solution and further dissolve the zinc-substituted film in hydrochloric acid.

In the figure, 3 represents a plating bath, 6 represents an anode, and 7 represents a DC power source.

[Brief explanation of the drawing]

Figure 1 is an enlarged photograph of the nickel plating layer and copper plating layer in Experimental Example 1, Figure 2 is an enlarged photograph of the same heat treatment, and Figure 3 is an enlarged photograph of the nickel plating layer and copper-nickel plating in Experimental Example 2. Figure 4 is an enlarged photograph of the copper plating layer and the copper plating layer, Figure 4 is an enlarged photograph of the same heat treatment, Figure 5 is an explanatory diagram showing the state of electrodeposition of each electrodeposited layer on the matrix, and Figure 6 is an enlarged photograph of the electrodeposition of each electrodeposited layer. Figure 7 is a cross-sectional view showing the state in which the mold is set in the mold and copper or brass is cast into it, and Figure 7 is a perspective view showing the manufactured product after the mold is removed from the mold. be.

Claims (1)

[Claims] 1. In the method of manufacturing continuous casting molds that requires a hard chrome plating layer on the inner wall surface of the continuous casting mold, hard chrome plating is applied to the surface of the mother mold to the required thickness, and this hard chrome plating is After applying nickel flashing plating on the layer, nickel plating is applied, and then copper/nickel alloy plating is applied on this nickel plating layer.
By applying copper plating on the nickel alloy plating layer, heat treating it, placing it in a mold, casting molten steel or brass on the outer surface of the steel plating layer, and removing the mother mold after cooling. 1. A method for manufacturing a continuous casting mold.