JPH0550473A - Injection mold - Google Patents

Abstract

PURPOSE:To improve the abrasion resistance of an air vent part and to extend the life of an injection mold by laminating and applying at least two kinds of ceramics materials to the surface of the air vent part in the injection mold for molding an insulating plastic material in a gradient compounding state to form a composite film layer thereto. CONSTITUTION:In the air vent part 4 of a injection mold 1 for molding a product 3, an extremely thin Ti layer 12 is applied to a mold matrix 1 to enhance the close adhesiveness of a ceramics film and, next, for example, a TiN layer 13, a TiCN layer 14 composed of a mixture of TiN and TiC and the outermost TiC layer 15 are successively laminated to the Ti layer 12. The TiCN layer 14 is formed in a gradient compounding state so that an initial TiN mixing ratio is high and a TiC mixing ratio is gradually increased and a TiC ratio becomes about 100% finally. By this film formation, the surface hard TiC layer 15 is reduced in abrasion and also increased in toughness by the TiCN layer 14 and TiN layer 13 thereunder and, in cooperation with the close adhesiveness of the films due to the Ti layer 12, the problems such as abrasion, breakage, release or the like on the surface of the mold are solved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting mold in which a ceramic thin film is formed on the surface of the casting mold.

[0002]

2. Description of the Related Art Conventionally, in order to improve wear resistance and corrosion resistance of a casting mold for casting a plastic material, the hardness of the mold material itself is increased or the surface of the mold is hard coated. Processing is performed.

As a method for improving the hardness, there is a method for improving the hardness by quenching, or there is a hard material, for example, an ultra-hard carbide, but both are hard-to-machine materials.
Defects such as cracks are likely to occur due to temperature changes during casting. Further, as a method for coating a hard material, there are hard chrome plating, nitriding method, ion nitriding method, etc., but the plastic material for electrical insulation is filled with glass fiber or silica particles for the purpose of preventing cracks. For this reason, the air vent has been particularly scraped off by the casting material, and it has not yet reached sufficient wear resistance such as expansion. In particular, the expansion of the air vent forms an unnecessary portion, and when the unnecessary molding material is removed from the molded product, the molded product may be chipped. In addition, it takes time to repair this.

In the case of a plastic injection mold for electric insulation having a complicated shape, various molds are divided, and even if the mold is thin, it is possible to inject the plastic material into the thin mold without excess or deficiency. Casting molded parts is essential.

[0005]

The inner surface of the casting mold forming the air vent portion is such that when the casting material is injected, the gas inside the die is released and at the same time, the partially molten casting material flows out at a high speed. Despite the hard mold surface, the inner surface may be scraped off, and the wear may be expanded as the number of times of use increases.
Therefore, as the number of castings increases, the amount of casting material that solidifies in the air bend increases and the yield deteriorates.When removing these unnecessary parts from the molded product, not only the number of man-hours but generally the chipping Is likely to occur, and it takes time to repair it. As a measure against this,
As described above, although the wear resistance has been improved by hard metal plating, quenching, etc., the current situation is that the wear resistance has not been sufficiently improved.

The present invention has been made in consideration of the above points, and in the air bend portion in the mold, the surface of the mold is coated with a ceramic film having a multi-layered structure which has excellent adhesion and is stable. Thus, the object is to provide a casting mold having excellent wear resistance and long life.

[0007]

Means and Actions for Solving the Problems At least two or more functionally graded composite film layers are provided in a portion of a casting mold for injection-molding an insulating plastic material in contact with the casting material of a gas venting air bend portion. To improve pitting corrosion prevention and wear resistance of the air bend part.

[0008]

Embodiments of the present invention will be described with reference to the drawings.

In a mold for casting a plastic material for electrical insulation, as shown in FIG. 1, the wear resistance of the mold surface of the air bend portion 4 is particularly improved. In FIG. 2, a Ti metal 12 is formed extremely thinly on the surface of a base material 11 of a mold, titanium nitride (TiN) 13 is coated on the surface, and TiN and carbon nitride (TiC) are further coated on the surface. Moreover, sequential TiC
The TiC layer is formed on the final surface by forming a film so that the concentration is increased in the graded compound material.

Here, the gradient composition means, for example, A component and B component.
In blending materials having components, as the concentration of the A component decreases, the concentration of the B component increases in inverse proportion to the decrease of the concentration of the A component so that the components can be changed substantially linearly from A to B. Say.

When the surface of the die is coated with Ti very thinly and the surface of the die is coated with ceramics, the adhesion of the film is increased. (Normally 10 to 20% improvement) In addition, the relationship between wear resistance and adhesion of the ceramics film is that TiN is superior to TiC in terms of adhesion and TiC is superior to TiN in terms of wear resistance. There is. Moreover, TiN is Ti
The toughness in the film is higher than that of C. Under these conditions, generally, SiO ₂ powder or the like is added to shot blast and sprayed on a ceramics thin film to perform a wear resistance test. As a result, the TiC film is superior in wear resistance to TiN, but the pitting corrosion resistance Wear is scattered and becomes a factor of subsequent wear. On the other hand, TiN has a
Although the amount of wear is slightly larger than that of the C film, the pitting corrosion property is reduced and a relatively stable wear resistant form is formed. Further details will be described with reference to the drawings.

FIG. 1 shows an air vent portion of a plastic material casting die, wherein 1 is a casting die, 2 is a sprue, 3 is a casting product, and 4 is an air vent portion. FIG. 2 shows the air bend portion 4 coated with a ceramic thin film. That is, an extremely thin (0.05 to 0.2 μm) Ti film is formed on the surface of the mold base material 11.
Layer 12 is coated with TiN 13 having a thickness of 1-2 μm, and TiN + TiC mixed TiCN layer 14 is coated with 2-4.
The TiC layer 15 is coated on the outermost surface in a thickness of 2 to 3 μm. The TiCN layer is formed so that the initial TiN mixing ratio is high, the TiC mixing ratio is successively increased, and the TiC ratio is finally about 100%.

By the above-mentioned film formation, the surface of the air bend portion that requires the most wear is covered with a hard TiC layer, so that the surface is rich in resistance, the amount of wear is small, and the underlying Ti layer is Ti.
The CN layer and TiN layer increase the wear resistance of the film as well as the toughness, and together with the Ti layer, which improves the adhesion of the film, solve the problems such as wear, chipping and peeling of the mold surface. However, it has a great effect of extending the life of the mold. In this example, the ceramics film was formed by PVD ion plating, but other methods such as CV are used.
The same can be done with D or sputtering.

[0014]

According to the present invention, the wear resistance and the long life of the air bend portion of the casting mold can be achieved.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a mold in which a ceramic thin film according to the present invention is formed on a mold for injection-molding a plastic material.

FIG. 2 is an enlarged sectional view showing details of each ceramic layer formed according to the present invention.

[Explanation of symbols]

 1 ... Casting mold, 2 ... Gate, 3 ... Casting product, 4 ... Air bend.

Claims (1)

[Claims] 1. A composite film layer in which at least two or more portions of the degassing air bend portion of a casting mold for injection-molding an insulating plastic material, which come into contact with the casting material, are formed in a gradient composition. Characteristic casting mold.