JPS5911380B2 - Electroforming manufacturing method for continuous casting molds - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing electroforming molds for continuous casting, and in particular, in carrying out the method, copper or copper alloy is used as the base material and selenium dioxide is used as the mold release agent. The present invention relates to a case where a mold release film treatment is performed.

That is, the applicant has proposed the invention related to Japanese Patent Publication No. 48-28255 and the invention related to Japanese Patent Application No. 50-27439 as an improved invention of the invention regarding a method of manufacturing a mold for continuous casting.

Therefore, the gist of the invention related to the above-mentioned Japanese Patent Application No. 50-27439 is as follows, in place of the method related to the above-mentioned Japanese Patent Publication No. 48-28255.
The point is that this is manufactured by an electroforming manufacturing method.

Now, in carrying out the electroforming manufacturing method, in order to accomplish the purpose, the surface of the mother mold should be taken into consideration, especially since the inner wall surface of the mold manufactured by the surface of the mother mold can be obtained without polishing to a mirror surface. Care must be taken to finish the cast surface.

The surface roughness of the mother mold affects the surface roughness of the inner wall surface of the continuous casting mold in which it is manufactured, and also directly affects the wear resistance of the inner wall surface of the continuous casting mold, improving wear resistance. It is well known that a surface close to a mirror surface of 0.5S or less is required.

However, from the viewpoint of the durability of the matrix, stainless steel is preferable, but due to problems such as the difficulty of finishing the surface to a mirror finish and the difficulty of overlaying in certain cases, copper is recommended as a material for the matrix. Or, it is characterized by using a copper alloy.

That is, by manufacturing the master mold from copper or copper alloy, D,
The advantage is that it facilitates the machining work to produce a mirror surface of 0.5S or less, and it also facilitates overlaying when there is a small area.

Further, copper plating has the advantage that repairs can be easily carried out in the event that a difference in required dimensions occurs as the number of uses increases.

Next, in the electroforming manufacturing method, it is required to release the mother mold, and a release film treatment is performed on the mother mold before electroplating.

Therefore, the mold release film is required to fully exhibit its effectiveness and to be uniform in relation to dimensional accuracy.

That is, it is necessary not only to have a film that is superior in chemical resistance when copper plating is applied to the mother mold, but also to have an even and uniform mold release film that does not impair electrodepositivity.

In this regard, as a result of research, the inventor of the present invention found that the release film treatment using an aqueous selenium dioxide solution is optimal (the immersion time must be kept at 10 seconds or less).

When a mother mold made of copper or a copper alloy is immersed in an aqueous selenium dioxide solution, its surface is oxidized and an oxide film is formed.

Not only is the oxide film formed evenly and uniformly on the surface of the matrix, it is also extremely strong without being damaged by copper sulfate in the copper plating solution, and even though the particles are small, However, it was found that this did not impair the electrodepositability.

It has also been found that when forming an oxide film using the selenium dioxide aqueous solution, a thickness of 1000λ to 1μ is optimal.

In other words, if the thickness is less than 1000λ, the original mold release effect cannot be expected, and if it is more than 1μ, the particles on the film surface will become coarse and the mirror surface of the mother mold surface will be damaged. It is.

Therefore, it has been found that in order to satisfy these conditions, it is required to keep the immersion time to within 10 seconds.

That is, although some changes are seen depending on the concentration of the selenium dioxide aqueous solution, when immersed in the same aqueous solution for 10 seconds or more, the mirror surface of the mold surface does not become rough, and the wear resistance of the mold inner wall surface for the above-mentioned manufactured product is improved. It becomes impossible to satisfy the conditions of sexuality.

However, in view of the fact that it is difficult to maintain the immersion time within 10 seconds and has extremely poor workability, the inventor further conducted research on countermeasures for this problem.

In other words, as effective countermeasures against such conditions, firstly, the concentration of the selenium dioxide aqueous solution is lowered so that the time can be increased, and secondly, the method is to prevent the surface of the matrix from being attacked by the selenium dioxide aqueous solution. This method is carried out by electrodepositing a protective film that does not have a protective coating.

Therefore, in view of the effectiveness of the latter countermeasure method, which is not limited to concentration, has superior workability, and can provide reliable countermeasures, the gist of the present invention lies in adopting such a method.

Therefore, as mentioned above, the requirements for this protective film include chemical resistance to selenium dioxide aqueous solution, which is an essential requirement to achieve its original purpose, as well as the formation of a protective film by electrodeposition. Therefore, since the base material is copper or copper alloy, it must have good adhesion, and metal plating that does not impair electroforming performance is required. .

Therefore, as a protective film that can satisfy each of the above requirements, protective films made of nickel plating, nickel alloy plating, or hacobalt plating can be mentioned, but in the examples described later, examples using nickel plating will be described in detail. This is the place to do it.

Example 1 Mother mold shape: 80mm x 80HI Nickel plating with a thickness of 1 μm is applied to the surface under the following conditions.

Nickel plating bath composition Nickel sulfate 2 4 0? /1 Nickel chloride 4 5 ? /1 Boric acid 30 f/, /, Sodium lauryl sulfate 0. 1 f//l, sodium saccharinate 0.1 no/t Conditions Bath temperature 50°C Stirring Air stirring Current density 4A/dm2 3 Release film treatment The mother mold with the above nickel protective film was placed under the following conditions. A mold release film treatment is performed by immersing it in a selenium dioxide aqueous solution.

Selenium dioxide 0.5% aqueous solution Temperature: 30°C Immersion time: 3 0 sec 4 Manufacturing of mold for continuous casting After each of the above treatments, the surface of the mother mold was plated with 2 mm thick nickel under the following conditions, and then Copper plating was applied to four groups to complete the plating, then the outer surface of the steel plating was machined to adjust the outer dimensions of the casting mold, and then the mother mold was pulled out and a square-shaped mold was made as a prototype. .

Nickel plating bath Nickel sulfamic acid 450g/13 Kerboric acid 30g/1 Sodium lauryl sulfate 0.1g/1 Plating conditions Cathode current density 4A/dm2 Bath temperature 60℃ pl{4.0 Stirring Nickel with cathode locker air stirring In addition to plating, Nitskelurin, Nitskeru iron,
Alloy plating such as nickel-chromium, nickel-iron-chromium, etc. is possible and has good wear resistance. For example, when nickel-iron-chromium alloy plating is applied, a strong passive film is created on the surface. This will impair the adhesion between the iron-chromium alloy plating layer and the copper plating layer, so before applying copper plating, perform flushing treatment in a nickel chloride bath or ferrous chloride bath, and then apply a few μm of nickel or iron plating. , a product with good adhesion to copper plating was obtained.

Copper plating plating bath Copper sulfate 2 0 0 ? /1 sulfuric acid
50 f/, l, Plating conditions: Cathode current density: 5 A/dm2 Bath temperature: 20 to 23°C Stirring: Cathode rocker Air stirring was used for the copper plating on the nickel plating, which was obtained by directly plating with sulfuric acid.

However, for those which have been flushed with ferrous chloride, it is preferable to apply a thin layer of copper plating in a copper bronze bath or a pyrophosphoric acid bath, followed by copper sulfate plating.

Claims (1)

[Claims] 1 In the method of manufacturing continuous casting molds by electroforming,
A mother mold is manufactured from copper or a copper alloy, and after finishing the surface of this mother mold to a mirror finish, a protective film of nickel plating, nickel alloy plating, or cobalt plating is electrodeposited on the surface of this mother mold, and then After this matrix is immersed in a selenium dioxide aqueous solution and treated with a release film, the surface of this matrix is coated with nickel plating, nickel-phosphorus, nickel-iron, nickel-chromium, or nickel-iron monochromium. 1. A method for manufacturing a continuous casting mold, which comprises: plating, electrodepositing copper plating on the plating, and then pulling out the mold and releasing the mold.