JP2008265251A - Mold device and molded product molded by the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold device preventing increase in frictional resistance and preventing a gripping part from buckling at its middle part when the gripping part is released from the core pin to cause a crush, lap or the like. <P>SOLUTION: The mold device comprises at least a cavity to form the external shape of a molded product and a core pin to form the internal shape of it. The surface of the outer circumference of the core pin is provided with an embossing processing, and the fine roughness by the embossing processing is formed in the range of 435 nm (nanometer) to 560 nm (namometer) in terms of the arithmetical mean roughness Ra. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a mold apparatus including at least a cavity that forms an outer shape portion of a molded product and a core pin that forms an inner shape portion of the molded product.

As an example, synthetic rubber, which is softer than hard resin, is characterized by a high frictional resistance, and is therefore an effective means for use that requires a non-slip effect. Synthetic rubbers are also used as gripping members for writing instruments and golf club grips because cushioning properties increase as the hardness decreases. These gripping members and grips are formed in a cylindrical shape by a mold apparatus in injection molding or the like, and the grip portion and grip formed in the cylindrical shape are attached to the writing instrument and the golf club.
JP 2002-337495. Utility Model Registration Gazette No. 2552183

  However, the synthetic rubber is soft, and the inner surface of the cylindrical handle is also difficult to slip. Therefore, on the surface of the core pin that forms the inner surface of the handle portion, a textured surface that is fine irregularities is formed by means such as blasting or electric discharge machining. With the textured surface, the frictional resistance between the inner surface of the handle portion and the surface of the core pin is minimized. However, depending on the shape and roughness of the textured surface, there is a risk of increasing the frictional resistance. It was buckled and crushed and drowned.

  Also, when the holding force between the gripping part and the core pin is large, the gripping part is not detached from the core pin, the gripping part is lost, or the mold is damaged. .

  The present invention is a mold apparatus comprising at least a cavity that forms an outer shape portion of a molded product and a core pin that forms an inner shape portion of the molded product, and performs surface processing on the surface of the outer peripheral portion of the core pin. The gist is that fine roughness by graining is formed in the range of arithmetic average roughness Ra435 nm (nanometer) to arithmetic average roughness Ra560 nm (nanometer).

  The present invention is a mold apparatus comprising at least a cavity that forms an outer shape portion of a molded product and a core pin that forms an inner shape portion of the molded product, and performs surface processing on the surface of the outer peripheral portion of the core pin. Since the fine roughness by the texture processing is formed in the range of arithmetic average roughness Ra 435 nm (nanometer) to arithmetic average roughness Ra 560 nm (nanometer), by keeping the distance of the molded product from the core pin optimal, This is a mold apparatus that can provide a molded product that is free from damage and prevent damage to the mold.

This example is composed of eight core pins, eight split mold cavities, and the like. First, the first core pin 6 and split mold cavity 4 will be basically described.
The mold apparatus according to the present invention is a mold 2 for molding a cylindrical rubber grip 1. An outer diameter side 3 of the rubber grip 1 is formed by a split mold cavity 4, and an inner diameter side 5 of the rubber grip 1 is formed by a first core pin 6.
The cavity side end surface 8a of the stripper bush 8 abuts against the movable inner surface step 4a of the split cavity 4 to form a space 7 for forming the rubber grip 1. (See FIG. 1). The rubber grip 1 has a shape in which the inner diameter side 5 is 8 mm in diameter (hereinafter referred to as φ), the outer diameter side 3 is φ10.6 mm, and the length of the shaft in the longitudinal direction is 45 mm. It is not limited to the dimensions.
Therefore, the outer diameter 9 of the first core pin 6 of this embodiment is formed to have a diameter of 8.13 mm obtained by multiplying the diameter 8 mm on the inner diameter side 5 of the rubber grip 1 by the amount of molding shrinkage.
The mold 2 can mold eight rubber grips 1 at the same time. That is, the mold is an eight-piece mold, and the split cavity 4, the core pin 6, and the stripper bushes 8 are arranged in a vertical row, and are arranged at equal intervals. In the present embodiment, the cavity 4 that forms the outer diameter side 3 of the rubber grip 1 is formed of a split mold, but the outer diameter side 3 of the rubber grip 1 is formed as a mold structure that does not use a split mold. A hole to be formed may be formed in the cavity block, and the first core pin may be inserted into the hole of the cavity block.

Next, the operation will be described. The rubber grip 1 is molded by filling the space 7 for molding the rubber grip 1 of the mold 2 with a styrene elastomer, which is a kind of synthetic rubber (see FIG. 2), but is limited to the styrene elastomer. For example, as an elastic resin, acrylic resin, silicone resin, fluororesin, vinyl chloride, urethane resin, polyurethane resin, polyethylene resin, elastomer gel, polyethylene gel, dimethyl silicone, methyl vinyl silicone, methyl phenyl Vinyl silicone, methyl fluoroalkyl silicone (fluorosilicone), fluoro-dimethyl copolymer silicone, urethane rubber, ethylene acrylic rubber, epichlorohydrin rubber, acrylic rubber, ethylene propylene rubber, chloroprene rubber, natural rubber, isoprene Rubber, chlorinated polyethylene, nitrile rubber, natural rubber, but like, not particularly limited as long as the shape can be maintained. These resins and / or elastic resins may be one kind or a mixture of two or more kinds, but synthetic rubbers such as silicone rubber, styrene elastomer, olefin elastomer, polyurethane elastomer, and polyester elastomer with good moldability. Is preferred.
Thereafter, the split mold cavity 4 is divided by expanding the mold 2. At this time, the outer diameter side 3 of the rubber grip 1 and the inner surface of the split mold cavity 4 are separated from each other. The rubber grip 1 is held by a core pin 6 that is in close contact with the inner diameter side 5 of the rubber grip 1 (see FIG. 3).
Further, when the mold 2 is expanded in the direction of the movable side 10, the rubber grip 1 held by the first core pin 6 is separated from the core pin 6 by the stripper bush 8 (see FIG. 4). 1 is completed (see FIG. 2).

  Before the rubber grip 1 is separated from the first core pin 6 by the stripper bush 8, the inner surface of the rubber grip 1 is in close contact with the outer diameter surface 11 of the first core pin 6. In order to reduce the adhesion force and the sliding resistance force between the rubber grip 1 and the first core pin 6, the outer diameter surface 11 of the first core pin 6 is subjected to embossing by means such as blasting. (Textured surface 12). In addition, the textured surface 12 has a fine concavo-convex shape, and the concavo-convex shape is formed by triangular peaks 12a and valleys 12b (see FIG. 5). The second core pin to the eighth core pin, which will be described later, are similarly textured, and triangular peaks 12a and valleys 12b are also formed.

Hereinafter, the fine roughness by the embossing of the core pin will be specifically described. The outer diameter surface 11 of the first core pin 6 is subjected to graining by blasting, and the fine roughness of the graining surface 12 is an arithmetic average height Ra 945 nm (nanometer). Hereinafter, the fine roughness of the textured surface 30 of the second core pin 14 is the arithmetic average height Ra 617 nm (nanometer), and the fine roughness of the textured surface 31 of the third core pin 15 is the arithmetic average. The height Ra of 560 nm (nanometer) and the fine roughness of the textured surface 32 of the fourth core pin 16 are the arithmetic average height Ra498 nm (nanometer) and the texture of the textured surface 33 of the fifth core pin 17 are Arithmetic average height Ra 435 nm (nanometer), fine roughness of the textured surface 34 of the sixth core pin 18, arithmetic average height Ra 302 nm (nanometer), fine roughness of the textured surface 35 of the seventh core pin 19 Is the arithmetic average height Ra 155 nm (nanometer), and the fine roughness of the textured surface 36 of the eighth core pin 20 is the arithmetic average height Ra 146 nm (nanometer). There.
These fine roughnesses were measured with an SPI 3800N type manufactured by SII Nano Technology, Inc., a scanning probe microscope.

  Next, an example in which the rubber grip 1 is molded with each core pin will be described. The test was performed by changing the Shore A hardness of the material used for the rubber grip 1 in various ways. Hereinafter, eight types of core pins configured by the first to eighth core pins are referred to as a core pin group 37.

First, a synthetic rubber having a Shore A hardness of 80 degrees was molded 10 times under the same conditions using a mold equipped with the core pin group 37.
At this time, the separated state of the rubber grip 45 from the rubber grip 1 and the rubber grip 39 in the core pin group 37 was confirmed.
Next, a synthetic rubber having a Shore A hardness of 70 degrees was molded 10 times under the same conditions using a mold equipped with the core pin group 37.
At this time, the separated state of the rubber grip 45a from the rubber grip 1a and the rubber grip 39a in the core pin group 37 was confirmed.
Next, a synthetic rubber of Shower A 50 degrees was molded 10 times under the same conditions, and the state of separation of the rubber grip 45b from the rubber grip 1b and the rubber grip 39b in the core pin group 37 at that time was confirmed.
Next, synthetic rubber having a Shore A hardness of 35 degrees was molded 10 times under the same conditions, and the state of separation of the rubber grip 45c from the rubber grip 1c and the rubber grip 39c in the core pin group 37 was confirmed.
Next, synthetic rubber having a Shore A hardness of 25 degrees was molded 10 times under the same conditions, and the state of separation of the rubber grip 45d from the rubber grip 1d and the rubber grip 39d in the core pin group 37 was confirmed.
Next, synthetic rubber having a Shore A hardness of 15 degrees was molded 10 times under the same conditions, and the state of separation of the rubber grip 45e from the rubber grip 1e and the rubber grip 39e in the core pin group 37 at that time was confirmed.

Next, the various test results will be described.
A state in which the rubber grip 45 is separated from the rubber grip 1 and the rubber grip 39 having a Shore A hardness of 80 degrees formed by the core pin group 37 and a Shore A hardness of 70 degrees will be described. In the rubber grip 1 and the rubber grip 39 to the rubber grip 45 molded with the Shore A hardness of 70 degrees, problems such as buckling and crushing in the separation from the eight types of core pin groups 37 did not occur.
Next, the separation state of the rubber grip 45a from the core pin group 37, the rubber grip 1a having a Shore A hardness of 50 degrees, and the rubber grip 39a will be described. The rubber grip 40, rubber grip 41, and rubber grip 42 having a Shore A hardness of 50 degrees formed by the third core pin 15, the fourth core pin 16, and the fifth core pin 17 do not have a problem of buckling or crushing due to separation. It was.
Next, the separated state of the core pin group 37, the rubber grip 1b having a Shore A hardness of 35 degrees, and the rubber grip 39b to the rubber grip 45b will be described. There was no problem of buckling or crushing due to the separation of the rubber grip 41b and the rubber grip 42b having a Shore A hardness of 35 degrees formed by the fourth core pin 16 and the fifth core pin 17.
Next, the separated state of the core pin group 37, the rubber grip 1c having a Shore A hardness of 25 degrees, and the rubber grips 39c to 45c will be described. There was no problem of buckling or crushing due to the separation between the fifth core pin 17 and the rubber grip 42c having a Shore A hardness of 25 degrees.
Next, the separated state of the core pin group 37, the rubber grip 1d having a Shore A hardness of 15 degrees, and the rubber grip 39d to the rubber grip 45d will be described. No buckling or crushing occurred due to the separation of the first core pin 9, the second core pin 14 to the eighth core pin 20, the rubber grip 1d having a Shore A hardness of 15 degrees, and the rubber grip 39d to the rubber grip 45d. .
The test results are shown in Table 1.

From the above test results, when the rubber grip 1 is molded with a Shower A hardness of 80 degrees to a Shower A hardness of 50 degrees, the outer diameter surface 11 of the first core pin 6 has an arithmetic average height Ra of 560 nm (nanometer) to an arithmetic average height. By forming the textured surface 12 with Ra 435 nm (nanometer), the frictional resistance, which is a characteristic of the synthetic rubber, is reduced, and the effect of not being in close contact with the first core pin 6 is obtained.
Further, when the rubber grip 1 is molded with a Shower A hardness of 50 degrees to a Shower A hardness of 35 degrees, the outer diameter surface 11 of the first core pin 6 has an arithmetic average height Ra of 498 nm (nanometer) to an arithmetic average height Ra of 435 nm (nano By forming the textured surface 12 with a meter), it is possible to reduce the frictional resistance, which is a characteristic of synthetic rubber, and to prevent the first core pin 6 from being in close contact.
Further, when the rubber grip 1 is molded with a Shower A hardness of 35 degrees to a Shower A hardness of 25 degrees, the outer diameter surface 11 of the first core pin 6 is formed with a textured surface 12 with an arithmetic average height Ra435 nm (nanometer). As a result, the frictional resistance, which is a characteristic of the synthetic rubber, is reduced, and the effect of preventing the first rubber core 6 from coming into close contact with the first core pin 6 can be obtained.

  Therefore, when the rubber grip has a Shore A hardness of 70 degrees to a Shore A hardness of 25 degrees, the outer surface of the core pin is subjected to an arithmetic average height Ra of 435 nm (nanometer) in order to separate the rubber grip from the core pin. It will be the best form.

Outline mold structure diagram for molding rubber grip Schematic diagram of a rubber grip molded with the mold shown in FIG. Schematic mold opening after rubber grip is molded with the mold shown in Fig. 1. Schematic diagram of completed rubber grip molding with the mold shown in FIG. Schematic view of the textured surface magnified with a scanning probe microscope Schematic of the AA cross section of FIG. Schematic of the BB cross section of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rubber grip 2 Mold 3 Outer diameter side 4 Split mold cavity 4a Inner surface step part 5 Inner diameter side 6 1st core pin 7 Space 8 Stripper bush 8a Cavity side end surface 9 Outer diameter 10 Movable side 11 Outer diameter surface 12 Wrinkled surface 12a peak part 12b trough part 14 2nd core pin 15 3rd core pin 16 4th core pin 17 5th core pin 18 6th core pin 19 7th core pin 20 8th core pin 30 Textured surface 31 Textured surface 32 Textured surface 33 Textured surface 33 34 Textured surface
35 Textured surface 36 Textured surface 37 Core pin group 39 Rubber grip 40 Rubber grip 41 Rubber grip 42 Rubber grip 43 Rubber grip 44 Rubber grip 45 Rubber grip

Claims (2)

A mold apparatus comprising at least a cavity that forms the outer shape portion of a molded product and a core pin that forms an inner shape portion of the molded product. A mold apparatus characterized in that a rough roughness is formed in the range of arithmetic average roughness Ra 435 nm (nanometer) to arithmetic average roughness Ra 560 nm (nanometer). The molded product molded by the mold apparatus according to claim 1 has a Shore A hardness of 35 degrees or more.

Images