JPH06116751A - Method for manufacturing cast copper alloy products - Google Patents

Abstract

(57) [Abstract] [Purpose] A marble-like mosaic pattern part having excellent durability is formed on the surface of a copper alloy casting product partially or entirely in a bare metal color to further enhance the sense of quality. [Structure] Copper alloy casting 10 potentially having a polycrystalline structure in which individual crystal grains are coarsened to the extent that they can be visually identified.
To cast. The copper alloy casting 10 is mirror-finished, degreased and masked, and then immersed in an aqueous solution of ammonium persulfate under predetermined conditions to expose the mosaic pattern portion 12 on the surface of the copper alloy casting 10. The mosaic pattern portion 12 and the mirror surface portion 1 after which the masking material is removed
In combination with 1, forms a metal-colored character or figure. Then, chromate treatment is performed to further clarify the color tone of the surface, and a protective film made of transparent synthetic resin is applied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various highly decorative copper alloy casting products, such as tabletop accessories, stands, lighting equipment, switch plates, building metal fittings, door pulls and pedestals, desks and drawers for drawers. The present invention relates to a method for producing a copper alloy casting product in which a marble-like mosaic pattern is formed on a pull tab or the like.

[0002]

2. Description of the Related Art Heretofore, articles made of brass, among copper alloys, have practically sufficient strength and corrosion resistance, and exhibit a high-grade golden color. Used in the place. For example, brass cast articles used for door pulls and room license plates,
The surface is mirror-polished and partially satin (rough surface)
Alternatively, there were those in which character symbols and patterns were formed by applying coloring processing. In addition, there is also one in which an article formed of a synthetic resin or the like is subjected to a plating treatment to form a character symbol, a pattern, or the like in a golden color.

[0003]

In the conventional brass articles, since the character symbols and patterns are formed by the matte surface (rough surface) or the colored portion and the mirror surface portion, the variety of decoration is poor. , I had a hard time not taking advantage of the noble golden color. Also, in the case of synthetic resin articles that have been plated, although letters and symbols can be freely formed,
There was a concern that the texture would be different and that the letters and symbols would be worn away, impairing the high-class feel, and rather giving an image of cheap goods.

Therefore, the present invention has been made based on the above-mentioned circumstances, and a mosaic pattern like marble is formed on the surface of a copper alloy casting product, and the mosaic pattern is the background color of the copper alloy casting product. It is an object of the present invention to provide a method for producing a copper alloy casting product which has the same bare metal color, excellent durability, and produces a more luxurious feeling.

[0005]

The method for producing a copper alloy casting product according to the present invention for achieving the above-mentioned object comprises a coarse polycrystal in which most of the crystal grains of the surface portion can be individually visually confirmed. After using a copper alloy casting having a structure and degreasing the copper alloy casting, the concentration is 10 to 200 g.
A transparent protective coating made of synthetic resin after immersing the copper alloy casting in an aqueous solution of ammonium persulfate at room temperature to 50 ° C./liter for several minutes to 30 minutes depending on its concentration and temperature, and rinsing with water and hot water. To be attached.

Further, in addition to the above-mentioned constitution, the method of the present invention is such that the casting is mirror-polished before the degreasing treatment, and after the degreasing treatment, before the surface of the copper alloy casting is immersed in the ammonium persulfate aqueous solution. The masking treatment is applied to appropriate places, and the masking material is removed after washing with water and hot water and before applying a transparent protective film made of synthetic resin.

Further, in the method of the present invention, a chromate treatment may be carried out instead of the treatment step of depositing the transparent protective film made of synthetic resin.

In the method of the present invention, chromate treatment may be carried out before applying the transparent protective coating made of synthetic resin.

[0009]

[Function] By injecting the molten copper alloy at a temperature much higher than the melting point and slowly cooling it, the copper alloy casting is made to have a size from the surface to the inside, where individual crystal grains can be visually recognized. It is potentially formed as a coarse-grained polycrystalline structure. Here, the coarsening of crystal grains is remarkable when the composition of the molten metal is 65 to 85 wt% of copper Cu and the balance is zinc Zn, and particularly when the content of copper Cu is 70 wt% and the balance is zinc Zn. It is up to several mm.

When the copper alloy casting is degreased and then immersed in an aqueous solution of ammonium persulfate, the copper alloy casting is corroded by the aqueous solution of ammonium persulfate, and a coarse polycrystalline structure on the surface is visibly raised to reveal the copper alloy. With a vivid color according to the type, it becomes a mosaic pattern similar to marble.
For example, brass is golden, copper is reddish brown, bronze is reddish brown, and white copper is silvery white.

Further, by chromate treatment,
A strong oxide film is formed on the surface to make pinholes and cavities inconspicuous, and the treated surface of the copper alloy casting that has been immersed in only an aqueous solution of ammonium persulfate has a slightly dull color, while it is bright, vivid and glossy. Change to a certain color.

Since the transparent protective film made of synthetic resin adheres to the rough surface of the copper alloy casting corroded by the aqueous solution of ammonium persulfate, it has practically sufficient adhesion strength, excellent durability, and gloss. Also increases.

[0013]

EXAMPLES Examples of the method for producing a copper alloy casting product according to the present invention will be specifically described below with reference to the drawings. The method of the embodiment according to the present invention is a casting step of casting a brass casting potentially forming a polycrystalline structure in which individual crystal grains are coarsened to a visible size, and an appropriate portion of the surface of the brass casting. Alternatively, a coarse polycrystal structure is clearly raised on the entire surface to make it visible, a mosaic pattern portion like marble is formed, and a protective coating made of synthetic resin is applied to the surface treatment step. 3 is an example of a brass product manufactured by the method of the present invention, which is a brass plate in which the letters "Sugimoto" are formed on the ground of the mosaic pattern portion 12 on the mirror surface portion 11.

The casting process is almost the same as the conventional green casting method. That is, a wooden or metal lower frame 2 is placed on a surface plate 1, sand 3 is put into the lower frame 2 and hardened, and flattened by a hanging plate, and a product shape is formed on the sand 3 in the lower frame 2. A wooden or metal prototype (metal mold, wooden mold, etc.) 4 is filled with sand up to the center of the upper and lower parting lines. Wooden or metal upper frame 5 of the same size on the lower frame 2
Put the sand 3 in the upper frame 5 to harden it and flatten it with a hanging plate. The lower frame 2 and the upper frame 5 are separated, and the prototype 4 left inside
Take out and attach the sprue 6 to the upper frame 5 side. Upper frame 5 and lower frame 2
A raw mold (mold) 7 is made by combining and as before.

Molten brass 9 is poured from the sprue 6 into the cavity 8 of the green mold 7 thus formed. Wait for the molten metal 9 to solidify (about 30 minutes in this example),
The sand 3 of the upper and lower frames 2 and 5 is disassembled, the brass casting 10 inside is taken out, and processed for commercialization such as deburring and cutting of the sprue part.

The above casting step differs from the conventional green casting method in that it uses sand which has a moisture content of 2.5 to 3.0% and which is dryer than before, and the casting temperature is about 1050 ° C. in the conventional case. While the temperature is slightly higher than the melting point, it is about 11
The point is that the temperature is 50 ° C., which is about 100 ° C. higher than usual.
The composition of the molten brass is 65 to 85 wt% of copper Cu, and the balance is zinc Zn and other trace elements (iron, etc.). still,
In this embodiment, copper Cu is 70 wt%.

The water content of the sand 3 used for the green mold 7 is 2.5 to 3.0.
% Is because if the green mold 7 is well dried, the molten metal 9 can be cooled and solidified slowly, and the crystal grains can be coarsened, and the sand dried more than 2.5% is difficult to form. This is because.

The casting temperature is set to be much higher than the conventional temperature (at least several tens of degrees Celsius, preferably about 100 degrees Celsius) because the molten metal 9 is gradually cooled and solidified in the green mold 7.
This is for coarsening the crystal grains of the brass casting 10. By the way, when casting is performed at a temperature slightly higher than the melting point as in the conventional case, the molten metal 9 in the portion which becomes the surface of the brass casting 10, that is, the portion in contact with the inner surface of the green mold 7 is rapidly cooled and solidified, and the crystal grains are refined. Even after the subsequent surface treatment step, a mosaic pattern composed of a polycrystalline structure in which individual crystal grains are coarse enough to be visually confirmed cannot be obtained.

Even if the brass casting 10 is not produced by the above-mentioned casting method, most of the crystal grains on the surface are visually recognizable, that is, the grain size is a coarse grained maximum of 15 to 20 mm. The brass casting 10 that it has may be manufactured by another casting method, for example, a baking casting method, a twin casting method, a wax casting method, a lost wax casting method, or the like. For example, according to the lost wax casting method, it normally takes about 120
By casting the molten metal at 0 ° C. and gradually cooling and solidifying, a brass casting potentially having a coarsened polycrystalline structure can be obtained. Incidentally, the polycrystalline structure of the surface may of course have variations in grain size or may be partially refined.

Needless to say, the method of the present invention can be applied not only to brass but also to other copper alloys, that is, copper alloy castings such as copper, bronze, and white copper.

Next, in the surface treatment step, first, a polishing treatment is performed to mask desired portions of the brass casting 10 produced in the casting step, for example, satin polishing of 180 to 250 mesh (casting cast by the lost wax method). About 400 to 600 mesh for intermediate finishing), and 6
000-7000 mesh is used to polish to a mirror surface. Then, degreasing treatment is performed and masking treatment is performed. Then, an aqueous solution of ammonium persulfate having a predetermined concentration is used as a corrosive liquid, and the brass casting 10 is dipped in the corrosive liquid at a predetermined temperature for a predetermined time so that a polycrystalline structure having a mosaic pattern appears clearly on the surface. Then, washing with water and washing with hot water is performed to remove (peeling) the masking material, chromate treatment is performed, and finally a transparent protective film made of synthetic resin is applied, that is, a so-called top clear coat is applied to finish.

The masking treatment is carried out by applying a masking material on a mirror-finished surface of the brass casting 10 in a desired shape such as letters, symbols or patterns, or by excluding a portion to be letters, symbols or patterns. In this embodiment, a commercially available acid-resistant paint or masking tape, for example, is used as the masking material, and the letters "Sugimoto" are used for the deposition.

The concentration of the corrosive liquid is 10 to 200 g.
Per liter, the immersion time of the brass casting 10 is several minutes to 30 minutes, and the temperature of the corrosive liquid is room temperature (several ten degrees) to 50 ° C. Here, the higher the concentration of the corrosive liquid and the higher the temperature of the corrosive liquid, the shorter the immersion time will be. However, if the concentration of the corrosive liquid is too high or the temperature is too high, the brass casting 10 may be deeply eroded to form pinholes even if the immersion time is short, and the concentration of the corrosive liquid is too thin. If the temperature is too low, the immersion time will be long and work efficiency will be poor. Therefore, as a result of repeated studies, when the immersion treatment is performed under the above-mentioned conditions, a mosaic-like polycrystalline structure in which individual crystals are coarse enough to be visually recognized on the surface of the brass casting 10 appears clearly and efficiently. Can be, in particular,
The best results were obtained when the concentration of the corrosive liquid was 50 to 80 g / liter, the temperature of the corrosive liquid was 20 to 30 ° C., and the immersion time was 10 to 20 minutes.

When the masking material is removed after the immersion treatment is completed and washing with water and hot water is performed, the portion where the masking material has been deposited until now, in this embodiment, the character portion of "Sugimoto" is a mirror surface. To become a golden mirror surface portion 11, and the other portion, that is, a background portion in this embodiment, becomes a golden mosaic pattern portion 12 made of a polycrystalline structure. In the case where the golden mosaic pattern portion 12 is formed on the entire surface of the product, it is needless to say that the above-described polishing process, masking process, and masking material removing process are not required.

In the chromate treatment (chromic acid treatment), the brass casting 10 is immersed in an aqueous solution of chromic anhydride for a few seconds, and the surface of the brass casting 10 and the masking material after the immersion treatment with the corrosive solution are removed. An oxide film is formed on the surface of the cast iron to prevent the pinholes and cavities from becoming conspicuous by the immersion treatment in the corrosive liquid, and enhance the weather resistance of the brass casting 10. Further, by this chromate treatment, the treated surface becomes a slightly dull golden color only with the corrosive liquid, while it exhibits a bright and bright golden color with gloss.

Adhesion of a transparent protective film made of synthetic resin (so-called top clear coat) is to form a protective film by spraying a transparent acrylic resin paint on the surface of a brass casting 10 that has been subjected to corrosion treatment and chromate treatment. Is. Here, since the surface of the brass casting 10 is roughened due to the corrosion treatment, the protective coating has sufficient adhesion strength and excellent durability. Moreover, since the brass casting 10 has an increased surface luster due to this protective coating, it becomes a brass product with a higher quality.

Regarding the chromate treatment and the transparent protective film deposition treatment with the synthetic resin, both treatments may be carried out in sequence, or only one of them may be carried out.

[0028]

As described above, according to the method for manufacturing a copper alloy casting product according to the present invention, most of the crystal grains in the surface portion are coarsened to a size that can be individually visually identified, and have a polycrystalline structure. Immersing the alloy casting in an ammonium persulfate aqueous solution under predetermined conditions to clearly reveal the above-mentioned polycrystalline structure on the surface and reveal it, and a marble-like mosaic pattern composed of the polycrystalline structure on the surface of the copper alloy casting. In combination with the fact that it can be formed in a bare metal color, for example, the brass casting itself exhibits a golden color (red copper for red copper, reddish brown for bronze casting, silver white for white copper casting), further enhancing the sense of quality. A brewed copper alloy casting product can be provided.

Further, according to the method of the present invention, since the transparent protective coating made of synthetic resin is applied to the rough surface of the copper alloy casting which has been corroded by being immersed in the aqueous solution of ammonium persulfate, the protective coating has a high adhesion strength and is durable. Excellent in performance. In addition, the protective coating increases the luster of the surface of the copper alloy casting and can provide a higher quality copper alloy casting product.

In addition, according to the method of the present invention as set forth in claim 2, the surface of the copper alloy casting is subjected to a combination of the polishing process and the masking process so that the surface of the copper alloy casting is a metallic surface of a metallic color such as golden or silver white and a golden color. We can provide various characters, figures, symbols, patterns, etc. by arbitrarily arranging with a mosaic pattern part of ingot color such as silver white, providing a copper alloy casting product with a solid and high-class feel that is not available in conventional products it can.

Further, according to the method of the present invention as set forth in claims 3 and 4, by further subjecting the copper alloy casting soaked with the aqueous solution of ammonium persulfate to chromate treatment, the occurrence of pinholes and cavities peculiar to the casting is prevented. As well as
Since the surface exhibits a brighter and brighter golden color such as golden or silver-white metal, it is possible to provide a copper alloy casting product having an even higher quality.

[Brief description of drawings]

FIG. 1 is a process diagram showing an outline of a surface treatment process of a brass cast product in a method for manufacturing a brass cast product according to an embodiment of the present invention.

FIG. 2 is a process diagram schematically showing a green casting process of a brass cast product in a method for manufacturing a brass cast product according to an embodiment of the present invention.

FIG. 3 is a perspective view showing an example brass product manufactured by the method of the present invention.

[Explanation of symbols]

 7 Raw type 9 Molten metal 10 Brass casting (copper alloy casting) 11 Mirror surface part 12 Mosaic pattern part

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C23C 22/00 Z C23F 1/18 8414-4K

Claims (4)

[Claims] 1. A copper alloy casting (10) having a coarse polycrystalline structure in which most of the crystal grains on the surface are individually visible to the naked eye is used, and the copper alloy casting (10) is degreased. After being applied, the copper alloy casting (1) is added to an aqueous solution of ammonium persulfate having a concentration of 10 to 200 g / liter at room temperature to 50 ° C. for several minutes to 30 minutes depending on the concentration and temperature.
0) is dipped, and after washing with water and hot water, a transparent protective coating made of synthetic resin is applied, and a method for producing a copper alloy casting product. 2. The method for producing a copper alloy casting product according to claim 1, wherein the casting is mirror-polished before degreasing treatment,
After the degreasing treatment, before the immersion in the ammonium persulfate aqueous solution, the masking treatment is applied, and after the washing with water and hot water, the masking material is removed before the transparent protective film made of synthetic resin is applied. Copper alloy casting product manufacturing method. 3. The method for producing a copper alloy casting product according to claim 1, wherein a chromate treatment is carried out in place of the synthetic resin transparent protective film deposition treatment. Production method. 4. The method for producing a copper alloy casting product according to claim 1 or 2, wherein chromate treatment is performed before the transparent protective coating made of synthetic resin is applied. Method.