JPH0947525A - Metal mold for molding golf ball - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve mold releasing property, wear resistance, and corrosion resistance of a metal mold for molding a golf ball to be used for molding a golf ball or a core of golf ball. SOLUTION: A coating film 4 consisting of an amorphous carbon hard film, i.e., amorphous diamond-like carbon is formed on a cavity surface of a metal mold body 2 for molding a golf ball. The coating film 4 consisting of the amorphous carbon hard film is of high hardness and excellent in surface smoothness, wear resistance, and chemical stability, and in addition, a low friction coefficient and has a lubricating effect. Consequently, by forming such amorphous carbon hard coating film 4 on the cavity surface, excellent mold releasing property, wear resistance and corrosion resistance can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for molding a golf ball used for molding a golf ball or a core for a golf ball. More specifically, the cavity surface has mold release property, wear resistance and corrosion resistance. The present invention relates to a golf ball molding die on which a film for improvement is formed.

[0002]

2. Description of the Related Art Conventionally, in molding a golf ball or a core for a golf ball by compression molding or injection molding, a resin having a poor mold release property is used. Therefore, the molded golf ball or core is easily removed from the mold. Since it cannot be molded, the following method is adopted for the purpose of imparting demoldability to the mold or the molded product itself. (1) A method of spraying a mold release agent such as silicone oil onto the cavity surface of the mold. (2) A method of dipping a mold release agent on a preformed product of a golf ball and then subjecting it to molding by a mold. (3) A method in which a mold release agent is kneaded into a resin for molding a golf ball or a core and is used for molding.

[0003]

However, each of the above methods has the following problems. That is,
In the method of (1), (a) the mold release agent may be caught in the resin of the molded product during molding, resulting in defective products. (B) The mold release agent adhered to the surface of the molded product after molding. Has the drawbacks that (3) the mold must be sprayed with a release agent every time molding is performed, and the molding operation is complicated. In the method of (2), the pre-molding steps such as a step of manufacturing a pre-molded article before molding and a step of dipping a release agent on the pre-molded article are increased. It is necessary to wash and remove the release agent attached to the surface, which complicates the manufacturing process. In the method of (3),
Sufficient releasability cannot be obtained only by kneading the release agent into the resin, and other means for imparting releasability such as spraying the release agent onto the mold must be taken.

On the other hand, for the purpose of improving demoldability,
It has been proposed to form various coatings on the surface of the mold cavity. Specific examples thereof are shown below. A Ti compound layer such as TiN or TiC is formed on the surface of the cavity (Japanese Patent Laid-Open No. 59-17931). A chrome oxide film is formed on the surface of the cavity, and a fluororesin is coated on the film (JP-A-5-234).
03). A nickel plating layer is formed by depositing fluorine-based polymer particles on the surface of the cavity (Japanese Patent Laid-Open No. 5-22024).
No. 1). A chrome-plated layer is formed on the surface of the cavity, and the cracks on the surface of the chrome-plated layer are impregnated with fluorine-based polymer particles (Japanese Patent Laid-Open No. 5-228227).
issue). However, none of the above-mentioned molds sufficiently satisfies the demolding property, the wear resistance and the corrosion resistance at the same time.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a mold for molding a golf ball which is excellent in demolding property, abrasion resistance and corrosion resistance.

[0006]

In order to achieve the above object, the present invention is characterized in that a film composed of an amorphous carbon hard film is formed on the cavity surface of a golf ball molding die body. A mold for molding a golf ball is provided.

The film made of an amorphous carbon hard film has high hardness, excellent surface smoothness, abrasion resistance, and chemical stability, has a small friction coefficient, and has a lubricating effect. Therefore, the mold of the present invention in which such a hard film of amorphous carbon is formed on the surface of the cavity exhibits excellent demolding property, wear resistance and corrosion resistance.

The golf ball molding die of the present invention is shown in FIG.
As shown in FIG. 5, the mold body 2 has a cavity surface formed with a film 4 made of an amorphous carbon hard film. Reference numeral 6 in the drawing denotes a dimple-forming convex portion formed in the cavity of the mold.

The mold body 2 is made of iron, copper alloy, or the like formed by electroforming, high-precision molding, casting, or the like.
Any of stainless steel, nickel, zinc die cast, etc. can be used. Further, in order to favorably form the coating film 4 made of the amorphous carbon hard film on the surface of the cavity of the mold body 2, any pretreatment, base formation, etc. can be performed.

In the present invention, the amorphous carbon hard film means diamond-like carbon (hereinafter referred to as DL
(Hereinafter abbreviated as C). The diamond film is a crystalline hard carbon film, whereas the DLC film is a non-crystalline amorphous hard carbon film. The DLC film is inferior to the diamond film in hardness, but is superior to the diamond film in smoothness and lubricity. The DLC film may have only an amorphous structure, or may have an amorphous structure and a diamond structure. The DLC film usually forms an alloy with hydrogen in terms of composition, and the hydrogen concentration is about 0 to 40 at.%. As for the electronic structure, carbon in the DLC film is mainly bonded by sp ³ .

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, an amorphous carbon hard film (DLC film) formed on the surface of a cavity
Examples of the material include those having the following characteristics. Crystal structure: Amorphous Bonding form: Mainly sp ³ Density: 3 or less (g / cm ³ ) Micro Vickers hardness (load 10 gf): 2000-5
000 (kgf / mm ² ) Containing hydrogen concentration: 0-40at.% Morphology: Very smooth

The amorphous carbon hard film is formed on the surface of the cavity by using hydrocarbon, alcohol, acetone,
Plasma CVD method using glow discharge, ion plating method or sputtering method, vapor deposition method using ion beam, using carbon-containing gas such as carbon monoxide or carbon dioxide, or solid graphite as a main raw material. Alternatively, a dry process such as a sputtering method, a CVD method using a laser, or an evaporation method can be used.

For example, in plasma CVD, the introduced reaction gas is brought into a plasma state to generate active radicals and ions, and a chemical reaction is performed in an active environment to form a thin film on a substrate (mold) at low temperature. Method, pressure is 1 to 1
It is about 00 Pa. In this case, the plasma used for plasma CVD can be generated by direct current (DC), radio frequency (RF) or microwave discharge.

When an amorphous carbon hard film is formed on the surface of the cavity, the film is formed while controlling various parameters that affect the properties of the film. For example, in high-frequency plasma CVD, parameters that affect the film properties include RF power, substrate bias, gas supply amount, pumping speed, gas pressure, ion energy, substrate temperature, etc., and these parameters are controlled. By forming the film while forming it, an amorphous carbon hard film having desired properties can be obtained.

The thickness of the amorphous carbon hard film formed on the cavity surface is not particularly limited, but 0.001
It is suitable to be -20 μm, especially 1-5 μm.
If the thickness is less than 0.001 μm, the demolding property (releasing property) may be deteriorated and the hard film may lack durability. 20 μm
If it is thicker, cracks are more likely to occur due to the internal stress of the hard film.

The mold for molding a golf ball of the present invention is used to manufacture a golf ball or a core for a golf ball, that is, a cover for a two-piece ball or a wound ball, a core for a two-piece ball or a one-piece ball, a solid core for a wound ball. Used in the manufacture of
It can be used for both compression molding and injection molding.

[0017]

Next, the present invention will be specifically described by way of examples, but the present invention is not limited to the following examples.

A nickel golf ball molding die body is manufactured by electroforming, and an amorphous carbon hard film (DL) is formed on the cavity surface of the die body by a CVD method.
C film) was formed to obtain a mold for molding a golf ball of the present invention. The contents of CVD and the properties and characteristics of the obtained amorphous carbon hard film are shown below.

Film formation was performed by a CVD method using a mixed gas of CVD methane and hydrogen as a source gas. The substrate (mold) temperature was 200 ° C.

Properties and characteristics of amorphous carbon hard film Crystal structure: Amorphous film thickness: 3 μm Density: Approx. 2.0 (g / cm ³ ) Dynamic friction coefficient μ _k (load 20 gf): 0.03 Dynamic friction coefficient μ _k ( Load 100 gf): 0.14 Static friction coefficient μ _s (Load 20 gf): 0.12 Static friction coefficient μ _s (Load 100 gf): 0.31 Micro Vickers hardness (Load 10 gf): 1800 (kg
f / mm ² ) Abrasion resistance: SiC # 600 as abrasive paper, load 800
As a result of a suga wear test with gf, the amount of wear of the amorphous carbon hard film is about 16% of SUS304, Ni-
It was about 23% of Cr plating and about 56% of TiN. Morphology: Very smooth Chemical resistance: Insoluble in acids, alkalis and organic solvents Color: Black

The following molding was carried out using the golf ball molding die of the present invention manufactured as described above. (a) A two-piece ball was manufactured by covering the core by compression molding with a cover containing an ionomer resin as a main component. (b) A two-piece ball was manufactured by coating the core mainly made of an ionomer resin by injection molding. (c) A wound ball was manufactured by coating the core with a cover containing balata as a main component by compression molding. (d) A two-piece ball core containing polybutadiene rubber as a main component was manufactured by injection molding. (e) A solid core of a wound ball containing polybutadiene rubber as a main component was manufactured by injection molding.

As a result, in all cases, good demolding property was exhibited. After repeating molding 100 times, the state of the amorphous carbon hard film on the surface of the cavity was examined, and no abrasion or corrosion occurred. The amorphous carbon hard film had good wear resistance and corrosion resistance. Was confirmed.

[0023]

As described above, the golf ball molding die of the present invention is excellent in demolding property, abrasion resistance and corrosion resistance. Therefore, according to the mold of the present invention,
There is no need to spray a mold release agent or knead an internal mold release agent into the molding resin each time molding is performed, and it is not necessary to wash the golf ball after molding to remove the mold release agent. Further, since the cavity surface has excellent wear resistance and corrosion resistance, the mold can be used without maintenance for a long period of time.

[Brief description of drawings]

FIG. 1 is a partially enlarged sectional view showing an embodiment of a golf ball molding die according to the present invention.

[Explanation of symbols]

 2 Die body 4 Film composed of amorphous carbon hard film 6 Dimple forming protrusion

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuyuki Kataoka 20 Onohara, Chichibu City, Saitama Prefecture, within Bridgestone Sports Co., Ltd. (72) Inventor Takehiko Yamaguchi 20 Onohara, Chichibu City, Saitama Prefecture, within Bridgestone Sports Co., Ltd. (72) Inventor Hiroki Kumagai 20 Onohara, Chichibu City, Saitama Prefecture Bridgestone Sports Co., Ltd.

Claims (1)

[Claims] 1. A golf ball molding die, wherein a film made of an amorphous carbon hard film is formed on a cavity surface of a golf ball molding die body.