JPH01168407A - Molding die made of aluminum or aluminum alloy - Google Patents

Abstract

PURPOSE:To provide a molding die made of aluminum superior in surface hardness and smoothness, by a method wherein electroless Ni-P plated coating is formed through coating on the surface of a die body comprised of the aluminum coming into contact with at least a molding material. CONSTITUTION:An eletroless Ni-P plated coating 2 is formed through coating on the surface of a mold body 1 comprised of aluminum coming into contact with at least a molding material. 2000 series, 5000 series and 7000 series alloys are preferable as a kind of aluminum constituting the die body from a point of view where they are superior in strength. Above all it is most preferable to make use of the 7000 series alloy, that is, Al-Zn-Mg series alloy from a point of view where the same is especially superior in adhesion to the electroless Ni-P plated coating. Although the electroless Ni-P plated coating 2 is capable of realizing high hardness and high smoothness, when its film thickness is less than 2mum its effectiveness is low. On the contrary, even if the thickness exceeds 10mum, there is no particular increase in effect, treatment time becomes long on the contrary, productivity is deteriorated; therefore, it is preferable to make a film thickness 2-10mum.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a mold for molding plastics, rubber, etc., and particularly to a mold made of aluminum or aluminum alloy material.

In the following description, the term aluminum is used to include its alloys.

Conventional technology Steel, special steel, superalloy steel, etc. have traditionally been used as materials for molds for molding plastics, rubber, etc. However, these materials have poor machinability and are difficult to manufacture. ■Due to the heavy weight, it is cumbersome to store and remove the mold, and it takes a long time to work.

Therefore, as an alternative to the above, aluminum molds using aluminum as the material have recently come to be employed.

Problems to be Solved by the Invention However, such aluminum molds have low hardness, resulting in drawbacks such as poor wear resistance and poor durability. For this reason, in order to improve the hardness of the mold, it has been proposed to form a hard alumite film on the surface of the mold (for example,
No. 192608, Japanese Patent Publication No. 59-35770), but in this case, the surface of the alumite film is less smooth than the surface of the aluminum base, and as a result, a high degree of dimensional accuracy of the molded product cannot be obtained. This resulted in many disadvantages.

This invention was made in view of this technical background, and has excellent surface hardness and surface smoothness, and furthermore, has excellent durability and
The object of the present invention is to provide an aluminum molding die with excellent dimensional accuracy of molded products.

Means for Solving Interlayer Points The present invention has achieved the above object by coating at least the surface of the mold body in contact with the molding material with an electroless Ni-P plating film instead of the alumite film. It is something.

That is, this invention is characterized in that, as shown in FIG. 1, at least the surface of the mold body (1) made of aluminum that comes into contact with the molding material is coated with an electroless Ni-P plating film (2). The gist is an aluminum molding die.

The type of aluminum that makes up the mold body is not particularly limited, but aluminum 2000 series, which has excellent strength,
5000 series and 7000 series alloys are preferred, and among them, 7000 series alloys such as JISA 7075.7079 alloy, that is, AQ-Zn-Mg, have particularly excellent adhesion to the electroless Ni-P plating film formed on the surface at the tail point It is most preferable to use alloys of the same type.

The electroless Ni-P plating film (2) is formed by performing electroless Ni-P plating treatment. An example of the electroless Ni-P plating process is as follows. That is, first, the mold body (1) is sequentially subjected to the degreasing, etching, and desmatting steps, and then the first step is carried out.
A zincate treatment, a peeling treatment using an acid solution, and a second zincate treatment are performed. The first zincate treatment may include, for example, Z
nO: 10-30 g/(1, NaOH: 100-
Using a zincate bath containing 150'j/n and a bath temperature of about 1° to 30°C, the treatment time is about 10 to 60 seconds. The peeling treatment is performed, for example, by immersing the film in 50% nitric acid at room temperature for about 10 seconds. After the second zincate treatment, the mold body is then immersed in, for example, 30 to 50 g/ρ sodium bicarbonate at room temperature for about 10 to 15 seconds to carry out an adjustment process, and then the mold body is immersed in a plating bath to remove the metal. Apply electrolytic Ni-P plating. An example of the composition of the electroless Ni-P plating bath is Ni chloride 309/fl, sodium acetate 30 g/fl.
Examples include those consisting of a mixed solution containing g1 sodium hypophosphite 209/ρ. The bath temperature is preferably about 90 to 100°C.

In this invention, electroless Ni is applied to the surface of the mold body (1).
-P plating film (2) is formed by electroless Ni-P
This is because the plating film (2) has high hardness and excellent surface smoothness, and as a result, the mold can be made with excellent surface hardness and surface smoothness. The reason why the electroless Ni-P plating film has such high hardness is that the film itself has a dense structure. Also, the reason why the film surface is smooth is because the film gradually grows on the mold body (1), and if the surface of the mold body is smooth to some extent, the electroless Ni-P plating film (2) also tends to be smoothed to the same extent or even smoother than the surface of the mold body.

On the other hand, since the alumite film is formed as the dissolution reaction with the mold body (1) progresses, the surface of the alumite film tends to become rough. As described above, the electroless Nt-P plating film (2) can achieve high hardness and high smoothness, but if the film thickness is less than 2 μm, the above effects will be small;
Even if the thickness exceeds 100 μm, the effect will not be significantly increased, and the processing time will become longer and productivity will be lowered. Therefore, the thickness of the electroless Ni--P plating film is preferably 2 to 10 μm. Furthermore, the purpose of the present invention can be satisfactorily achieved by forming an electroless Ni-P plating film on at least the surface of the inner surface of the mold body that comes into contact with molding materials such as resin and rubber. In this regard, it is of course permissible to form a coating over a wide area including the entire surface of the mold body or the portion in contact with the molding material.

Effects of the Invention As described above, the aluminum molding die according to the present invention is characterized in that an electroless NL-P plating film is formed on at least the surface of the mold body made of aluminum that comes into contact with the molding material. Therefore, it is possible to have a mold surface with a hardness of 1 and excellent smoothness, which in turn makes it possible to create a mold with excellent durability and long life, and to obtain a molded product with excellent dimensional accuracy. become something that can be done. Furthermore, since the electroless Ni--P plating film has good coverage on the surface of the mold body, it is possible to provide a mold with little dimensional change. Since this mold is made of aluminum, it is lightweight and has excellent machinability, making it easy to store and remove the mold, as well as making it possible to manufacture the mold in a short time. has advantages.

Example [Example] An aluminum mold body made of A7079 alloy was prepared, and the body was sequentially subjected to degreasing, etching, and desmutting processes according to conventional methods, and then further subjected to a first zincate treatment and a peeling treatment. , second zincate treatment, adjustment treatment,
Electroless Nt-p plating was sequentially performed to coat the surface of the mold body with an electroless Ni-P plating film, thereby obtaining an aluminum mold according to the present invention. In addition, the first
, second zincate treatment, peeling treatment, adjustment treatment, and plating treatment were performed under the following conditions.

(First zincate treatment) Bath composition: Substar ZNI (manufactured by Okuno Pharmaceutical Co., Ltd.)
, 250d/R Bath temperature: 25°C Time: 50 seconds (peeling treatment) Bath composition = 50% nitric acid Bath temperature: Room temperature time = 10 seconds Immersion (second zincate treatment) Same as first zincate treatment conditions (adjustment treatment) Bath Composition: Sodium bicarbonate 30-50 g/Ω Bath temperature: Room temperature Time: 13 seconds immersion (electroless Ni-P plating treatment) Bath composition: BL-M (manufactured by Okuno Pharmaceutical Co., Ltd.), 100
d/ρ BL-1 (manufactured by Okuno Pharmaceutical Co., Ltd.), 60d/Q Bath temperature: 95°C Time: 30 minutes Immersion The film thickness of the electroless Ni-P plating film produced through the above process was 8 μm. Ta.

[Comparative Example 1] Using the same mold body as in the above example, the mold body was subjected to alumite treatment under the following conditions to give a film thickness of 1 on the surface of the mold body.
A 0 μm alumite film was formed to obtain a mold.

(Processing conditions) Bath composition: 15vt% H2SO4 Bath temperature: 5°C Current density: 1.2A/dm Electrolysis time = 30 minutes [Comparative example 2] With a mold body made of the same aluminum material as in the example (no film formed) It was made into a mold.

The surface hardness and surface roughness of the three types of aluminum molds obtained above were measured. The results are shown in Table 1 below.

[Margin below] From the results shown in Table 1, it was confirmed that the aluminum molding die according to the present invention had excellent surface hardness and surface smoothness.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view showing a part of an aluminum molding die according to the present invention. (1)...Mold body, (2)...Electroless Ni-P plating film. Figure 1 above

Claims (3)

[Claims] (1) Electroless Ni is applied to at least the surface in contact with the molding material of the mold body made of aluminum or aluminum alloy.
- An aluminum or aluminum alloy forming die characterized by being coated with a P plating film. (2) The aluminum or aluminum alloy forming mold according to claim 1, wherein the mold body is made of a 2000 series, 5000 series, or 7000 series aluminum alloy. (3) Thickness of electroless Ni-P plating film is 2 to 10 μm
An aluminum or aluminum alloy forming die according to claim 1 or 2.