JPS63109015A - Molding die - Google Patents

Abstract

PURPOSE:To stabilize mechanically and chemically the face of a molding die, and protect it with good durability, by forming the molding die with titanium or a titanism alloy and forming a titanium nitride layer on the die surface where a molding material contacts with. CONSTITUTION:A molding die 1 is formed of titanium as a pair of a top force 11 and a bottom force 12. In the molding die 1 prepared of titanium, the dimen sion and shape of the die prepared with a high accuracy is kept by the high mechanical strength of titanium material, and titanium nitride layers 41 and 51 formed on the die surface 4 and the die mating face 5 have high corrosion resistance against corrosive gas and so on, and no adherence of rubber 3 occurs on the surfaces to make the die releasing of the rubber smooth. As a result, molding processability is highly improved and corrosion and damage of the die surface 4 and the die face 5 are prevented. It is thereby possible to prepare a molding die having excellent durability and good productivity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a molding die made of titanium or a titanium alloy.

[Conventional technology]

Mold molding can produce large quantities of molded products of the same shape, and can also mold various molding materials such as ceramic powder, rubber, and synthetic resin into complex shapes with high dimensional accuracy.
Recently, it has come to be widely used in the production of various small precision parts.

As the mold material, steel such as SK material or SKD material has been commonly used after surface treatment.

However, when molding materials such as rubber, synthetic resin, or ceramic powder containing them as a binder are molded, these molding materials generate corrosive gases and compounds. For example, synthetic rubber costs 150 to 200 yen.
It is common to mold the material by heating it to a certain temperature, but this process generates chlorine gas and chlorides.

For this reason, conventional steel molds are corroded early by these corrosive gases and compounds, causing play in the mold as the mold wears, especially for small precision parts with complex shapes. In molding, there was a problem in that steel molds lacked durability.

Furthermore, since these molding materials generally have strong adhesive properties, they tend to stick to the mold and remain on the mold, so after each molding, the molding surface must be carefully cleaned, the mold release agent must be reapplied, and the mold must be removed frequently. It is necessary to disassemble the product and thoroughly clean the molding and mating surfaces. However, in order to improve the cleaning effect, it is common to wash the mold by immersing it in a 20 to 30% caustic soda solution for about 24 hours, which prevents the entire mold from alkaline corrosion. You will receive it. Moreover, if the mold is not disassembled and cleaned sufficiently, molding workability will be impaired, and on the other hand, if the mold is washed frequently, the life of the mold will be shortened, which is a contradictory problem.

In response to this, recently, attempts have been made to coat the molding surface with a titanium nitride thin film or the like as a surface treatment for steel molds. PVD by ion blating in a vacuum chamber (
These methods include the physical vapor deposition (physical vapor deposition) method, and the CVD (chemical diluent) method in which a titanium nitride thin film is deposited at a high temperature of 800 to 1200°C. The main purpose of these thin film coatings is to increase the surface hardness of the mold and improve its wear resistance, and within that range they produce certain effects.

However, the thin films deposited and formed by these coating treatments commonly have pinholes and minute defects.
Alternatively, the thickness of the coated film becomes partially non-uniform. In particular, in molds with intricately shaped molding surfaces, the influence of mold effects is large, resulting in uneven coating film thickness and, in some cases, uncoated parts of the mold. is.

Furthermore, molding materials such as rubber and synthetic resin may still remain on the coated molding surface, so it must be cleaned frequently as in the case of steel molds. As a result, the cleaning solution that penetrates through pinholes etc. erodes the steel that is the mold material, and the thin film of titanium nitride or titanium carbide that is coated on the molding surface is easily peeled off. there were.

[Problem that the invention seeks to solve]

In such conventional technology, by providing the molding die with sufficient corrosion resistance, even when molding rubber, synthetic resin, or a molding material containing these materials, it will not be corroded by corrosive gases or compounds generated from the molding material. Furthermore, by providing sufficient mold releasability on the surface of the molding die that comes into contact with the molding material, the molding material does not stick to the molding die and remains, ensuring high precision and even when molding products with complex shapes. The concept of molding with maximum productivity has not been introduced, and as a result, mold corrosion due to corrosive gases and compounds generated when molding these molding materials, and mold surface damage. Due to the corrosion that accompanies cleaning of the molding material that remains on the mold, it was generally assumed that the durability of molds would be short. As the mold erodes, the expensive mold must be remade frequently, which not only increases the cost of the molded product, but also reduces molding workability due to clogging due to mold play, resulting in reduced productivity. The problem was that it was not possible to increase the

[Means for solving problems]

Therefore, in view of the above-mentioned problem caused by corrosion of the mold when molding rubber, synthetic resin, or a molding material containing these in the prior art, the present invention provides a method in which the mold is made of titanium or a titanium alloy. However, the above-mentioned problem is attempted to be solved by forming a titanium nitride layer on at least the molding surface of the molding die that is in contact with the molding material.

[Effect]

The groove forming method of this invention is that the titanium or titanium alloy that forms the molding die has high mechanical strength and hardness as well as the ability to withstand chemical corrosion. It is processed with high precision without deformation due to physical stress, etc., and without being corroded by corrosive gas or its compounds generated from the molding material, or by the cleaning liquid used in cleaning the mold. The titanium nitride layer formed on at least the molding surface in contact with the molding material has ultra-high hardness and is chemically stable. It also has properties that prevent molding materials from adhering to it, so it not only does not cause abrasion or damage to the molding surface, nor is it subject to chemical corrosion, but it also prevents the molding material from adhering to the metal. Since the mold release from the mold is smooth and no molding material is left attached to the mold, the molding surface of the highly precisely formed mold is stable and durable both mechanically and chemically. It has a good protective effect.

〔Example〕

Next, an embodiment of the present invention will be described with reference to the drawings of FIGS. 1 and 2.

FIG. 1 is a sectional view showing the configuration of the first embodiment. The molding die 1 is formed of titanium as a pair of an upper die 11 and a lower die 1 and 2. A titanium nitride layer 41 is formed on the molding surface 4 of the molding die for molding the rubber coated with the molding material 3, and furthermore, in this embodiment, when the molding die of the upper mold 11 and the lower mold 12 is combined 5 Also, a titanium nitride layer 51 is formed.

According to the above embodiment, the rubber 3 filled in the cavity 2 recessed in the lower mold 12 is compressed by the upper mold 11 and is formed by the molding surface 4 of the upper mold 11 and the molding surface 4 of the lower mold 12. At the same time, the excess rubber 3 flows out of the molding die 1 from the cavity 2 through the mating surface 5. During molding, the molding pressure is applied to the mold 1 ('1
1.12) is added to the molding surface 4, but the mold 1 (11,1
2> is made of titanium, which has high mechanical strength, so that no mechanical deformation occurs in the mold. In addition, the rubber 3 plastically flows during molding and applies severe compressive force and frictional force to the molding surface 4 and the mating surface 5, but these surfaces 4,
5 is protected by the titanium nitride layer 41, 51 having ultra-high hardness, so that the rubber 3 is molded with high precision without mechanical deformation or wear.

When molding the rubber 3, the rubber 3 is usually heated to about 150 to 200°C to impart moldability and then molded. Therefore, the rubber 3 containing various compounding agents such as vulcanizing agents, accelerators, and anti-aging agents generates corrosive substances such as chlorine gas and chlorides. Against these corrosive gases and compounds, titanium nitride layers 41 and 51 are formed on the molding surface 4 and mating surface 5 of the mold 1 (11, 12) according to the present invention, and the titanium nitride layer Since 41.51 has sufficient corrosion resistance, mold 1 (11, 12) will not be corroded.

Furthermore, the titanium nitride layer 41.51 according to the present invention does not adhere to the rubber 3 that flows during molding and comes into contact with the molding surface 4 or the mating surface 5, and leaves the rubber 3 on the molding surface 4 or the mating surface 5. It also has a special effect of releasing it from the shape.

According to this embodiment, the molding die 1 is made of titanium.
(In 11, 12>, the dimensions and shape of the highly precisely machined mold are maintained by the high mechanical strength of the titanium material, and the titanium nitride layer 41° 51 formed on the molding surface 4 and mating surface 5. has high corrosion resistance against corrosive gases, etc., and does not allow the rubber 3 to adhere, making it easier to release the molded rubber.As a result, the workability of molding is greatly improved, and the molding surface 4 Corrosion and damage to the mating surface 5 are prevented, and a mold with excellent durability and good mass productivity can be provided.

Specific examples related to the embodiment shown in FIG. 1 are detailed below)2!
Do S. The mold 1 (11, 12) according to this example is:
It is formed using JIS Class 3 titanium.

Note that it is desirable to use a titanium material with high hardness, and even better mechanical strength can be obtained by using ASTM grade 4 or a titanium alloy.

Mold 1 (11, 1) is machined into a predetermined shape.
2), the molding surface 4 and the mating surface 5 are polished and mirror finished, degreased by dipping in trichlorethylene and vapor phase cleaning, thoroughly dried, and then vapor phase nitriding is performed. has been done. In vapor phase nitriding, the mold is first placed in a vacuum chamber, then the vacuum chamber is evacuated and nitrogen gas is introduced alternately to complete the gas barge, and then nitrogen gas is flowed under atmospheric pressure. went. The nitrogen gas used was a high purity nitrogen gas containing 0.01% or less of water and 0.1% or less of oxygen, and the flow rate in the vacuum chamber was 201/min. The heating temperature increase rate was 50° C./min, and after holding at a high temperature of 850° C. for 24 hours, cooling was performed at 550° C./min. Note that the heat treatment during heating and cooling was performed with nitrogen gas flowing.

According to the above vapor phase nitriding, the depth of the generated titanium nitride layer reached approximately 30 μm from the surface of the molding surface or mating surface. Note that the depth of the titanium nitride layer has a close relationship with the heating temperature and high temperature holding time, and when heat treatment is performed at 800°C for 24 hours, it will break off at a depth of 15 μm and 90°C.
When heat treated for 48 hours at 0℃, the depth is 40μ.
It was m.

In addition, no pinholes were observed in the titanium nitride layer produced in the above-mentioned example, and the molding surface of the mold, the mating surface, and the corners (ridges and depressions) in the order of radius 0.5 that these surfaces have. A titanium nitride layer was also formed at an even depth. In particular, a titanium nitride layer with a depth of about 10 μm was evenly formed at the bottom corner located at the deepest part of the cavity formed in the lower mold 12 with an inner diameter of 10 # and a depth of 30 mm. Note that the formation depth of these titanium nitride layers was measured by a cutting surface hardness measuring method.

Next, a comparison will be made between the case of a conventional steel mold and the case of the above-mentioned specific example in terms of corrosion of the mold and adhesion of molding material to the molding surface of the mold, and will be described below.

The molding material is a rubber material whose main component is imprene.
Alternatively, epichlorhydrin rubber, chlorosulfone polyethylene or nitrile butadiene was used. Also,
The molding temperature of the rubber was 150 to 200°C.

The conventional steel mold used as a comparative example is made of 5KD61 alloy tool steel for hot working, and the molding surface is polished. According to the [j mold, a pit-like corrosion film was observed on the molding surface after only 10 moldings were performed at a molding pressure of 3 Ky/crA.

On the other hand, according to a specific example of the present invention, the molding pressure is 3/9/
Even after molding was performed 100 times at cM, no corrosion occurred on the molded surface or the mating surface, and an extremely clean surface condition was maintained.

Next, according to the conventional W4 mold, every time rubber is molded, rubber with a thickness of about 10 μm remains on the molding surface and mating surface of the mold, and due to the viscoelasticity of the rubber, , even if you try to wipe it off with a rag, it cannot be removed easily. Therefore, we immersed it in a 30% strength soda solution for 24 hours, then scraped off the remaining rubber with a wire brush, polished the molded surface with 1000 mesh emery paper, and then mirror-polished it with Kinku polishing agent. provided. As a result, the molding surface of the mold was polished by about 20 to 30 microns by the - times of cleaning operations.

On the other hand, according to the specific example of the present invention, no rubber adhered or remained on the molding surface of the mold.

As a result, it is unnecessary to apply a mold release accelerator, which was required for each molding in conventional EL molds, or it is sufficient to apply it every several moldings.

Next, as a comparative example, a conventional steel mold is coated with a titanium nitride thin film deposited by ion plating.

In addition, the cavity 2 in the above example has a diameter of 10 αm and a depth of 30 m, and conventional ion brating is affected by the shape effect, and generally a uniform film is not formed on the inner surface of such a hole-like cavity. It is not possible to apply a thick coating.

For example, 20A in a nitrogen gas atmosphere of 5X10'Pa
The titanium nitride R film deposited by coating treatment with an ion current for 1 hour has a thickness of about 3 μm on the upper end surface of the cavity 2, but a thickness of 1 μm on the inner surface of the central portion in the depth direction of the cavity 2.
4) In some cases, the thin film may not be deposited, especially at the bottom corners.

As a result, the coating was not effective and lacked mold releasability, and the coating film partially peeled off after 400 moldings. As a result, during cleaning, the underlying steel mold is corroded by the cleaning solution, which also causes the thin coating film to peel off.

In the above specific example, the titanium nitride layer is formed on the molding surface by vapor phase nitriding, but other electrochemical formation methods or nitrogen diffusion methods that do not involve hydrogen may also be used. Therefore, vapor phase nitriding is optimal because a homogeneous nitrided layer can be uniformly generated over the entire mold surface.

In addition, the nitriding heat treatment temperature of the molding mold was set to 800 to 900''.
The reason for selecting C is that within this range, a hard titanium nitride layer with a hardness of 15001-IV and no pinholes can be produced, but below 800°C, the rate of diffusion and formation of the layer is slow and unsuitable. Moreover, if the temperature is 900° C. or higher, thermal distortion of the mold itself becomes large, making it unsuitable for precision molding. In addition, the adhesion of rubber to the molding surface is 8.
If it is nitrided at a temperature of 00°C or higher, it exhibits suitable mold releasability.

In addition, the thickness of the titanium nitride layer is set in the range of about 10 to 30 μm because if it is less than 10 μm, sufficient hardness cannot be achieved, and if it is more than 30 μm, it will take a long time to heat-treat the mold for nitriding. This results in not only a decrease in processing efficiency but also the formation of inherent cracks on the surface of the titanium nitride layer, conversely resulting in poor durability and poor mold releasability.

Next, another embodiment of the present invention will be described with reference to FIG.

FIG. 2 is a cross-sectional view showing the configuration of an embodiment using the transformer 71 method, in which the molding die 1 consists of a plunger 13, a pot die 14, an upper die 15, a middle die 16, and a lower die 17 made of titanium alloy. There is. And plunger 13
The mold surface 6 includes the inner surface of the pot 18 where the and pot mold 14 contact the molding material, the plunger 13 and the pot mold 14
A titanium nitride layer 51.61 is formed on the mating surface 5 of the molding surface 4 of the upper mold 15, the middle mold 16, the lower mold 17, and the inner surface 7 of the sprue 19 formed by the pot mold 14 and the upper mold 15. , a titanium nitride layer 71 is similarly produced.

According to the configuration of the above embodiment, the acrylic resin 3, which is the molding material filled in the pot 18, is heated to 100 to 120°C, pressurized to 3 K9/crA by the plunger 13, and then passed through the sprue 19 into the cavity. 20 and molded. Mold made of titanium alloy 13. '14,1
5.16 and 17 withstand molding pressure and maintain the shape of highly precisely processed molds, and the titanium nitride @51, 61.71 produced in these molds is the molding of acrylic resin 3. The acrylic resin is not corroded by the cyan gas or its compounds that are sometimes generated, and also prevents corrosion of the mold itself, thereby molding the acrylic resin with good durability. Furthermore, the acrylic resin 3 filled in the pot 18 is smoothly pumped into the cavity 20, but at the same time, the acrylic resin does not adhere to and remain on the titanium nitride layers 51, 61, 71. 19 and the replacement of molding materials are extremely easy, and contamination between different types of molding materials does not occur. Furthermore, the acrylic resin molded within the cavity 20 can be easily released from the mold, allowing for rapid production of a large amount of molded products, thereby improving workability.

According to the above embodiment, the flow of the acrylic resin 3 that is filled from the pot 18 to the cavity 20 via the sprue 19 and press-molded is improved, and the flow of the acrylic resin 3 that is molded with intricate precision is improved. It has the effect of significantly prolonging life.

In addition, in the above embodiment, the mold was 13°, 14°, 15°.
16 and 17 are titanium alloy (90%T16%AfJ4
%V or β alloy) was used. According to the titanium alloy mentioned above,
It has better mechanical strength than titanium, has good workability, and is low grade, so it can be used to form molds economically.

Further, the titanium nitride layers 51, 61.71 formed on the inner surfaces 4, 6.7 and the mating surfaces 5 of these molds are formed by heat-treating the mold 1 in nitrogen gas, as in the first embodiment. It was generated by

Note that the high temperature holding temperature and holding time in nitriding titanium alloy are not limited to the heat treatment conditions for nitriding titanium in the first embodiment, which are 800 to 900°C for 24 hours, but may be 850°C for 24 hours. Or 900℃, 2
It is possible to obtain a nitrided layer with a thickness of 30 μm in the former case, and a nitride layer with a thickness of 40 μm in the latter case.

In addition, in the explanation of the above example, it was explained that a titanium nitride layer is generated by vapor phase nitriding on the molding surface and mating surface of the mold, but it is not limited to only the molding surface and mating surface, but is applied to the entire exposed surface of the mold. It is also possible to produce a titanium nitride layer, which increases the durability of the -layer mold.

In addition, although the molding material has been explained using rubber and acrylic resin as examples, it is also possible to use other plastics that generate corrosive gases or compounds during molding, or granular materials containing binders such as polymer resins. It is also possible to produce highly effective molding using these molding materials.

According to the present invention, since titanium or a titanium alloy is used as the mold material, the same effect can be achieved by depositing and coating a titanium nitride film or a titanium carbide film on the surface of a mold made of titanium or a titanium alloy. be able to.

〔Effect of the invention〕

As described above, according to the present invention, a titanium nitride layer is formed on at least the molding surface in contact with the molding material of a molding mold made of titanium or a titanium alloy to form a molding mold. The mold is not corroded by corrosive gases or compounds generated from the molding material 1, and can easily be coated with a thin film deposited, as in the case of coating steel molds with a thin film of titanium nitride in the conventional technology. It will not peel off and cause further erosion. In addition, since no molding material remains on the molding surface of the molding die, there is no need to clean the mold after each molding process, resulting in excellent workability and durability. It has the excellent effect of being able to provide a molding die and mass-produce rubber, synthetic resin, or a molding material containing them into highly precise and complex shapes.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of a first embodiment of the invention, and FIG. 2 is a sectional view showing the structure of another embodiment. DESCRIPTION OF SYMBOLS 1... Molding die, 2... Cavity, 3... Molding material, 4... Molding surface, 5... Matching surface, 41, 51
, 61° 71...Titanium nitride layer.

Claims (1)

[Claims] 1. A molding mold made of titanium or a titanium alloy, characterized in that a titanium nitride layer is formed on at least the molding surface in contact with the molding material. 2. The molding die according to claim 1, wherein the molding material is rubber, synthetic resin, or a molding material containing the same. 3. The molding according to claim 1, wherein the titanium nitride layer is a titanium nitride layer produced by vapor phase nitriding at least the molding surface of the molding die formed of the titanium or titanium alloy. Mold. 4. The molding mold according to claim 3, wherein the molding mold is a molding mold in which a titanium nitride layer is formed not only on the molding surface of the mold but also on the mating surface.