JP6906091B1 - Grommet for racket and racket equipped with this - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a racket grommet having high durability and a racket to which the grommet is attached, which is not damaged even when repeatedly pulled up with a high tension. A racket grommet 40 for stretching a string on a racket, which is formed of a carbon fiber reinforcing resin containing 10 to 40% by mass of pitch-based carbon fibers and 60 to 90% by mass of a polyamide resin. There is. The racket of the present invention is a racket in which the racket grommets 40 are mounted in a plurality of string insertion holes. The polyamide resin is particularly preferably poly (metaxylylene adipamide). [Selection diagram] Fig. 1

Description

The present invention relates to a racket grommet used for badminton, hard tennis, soft tennis, squash, etc., and a racket to which the grommet is attached.

Grommets are required to stretch strings on rackets such as tennis, badminton, and squash. If the string is pulled up with a high tension, problems such as damage to the grommet and deformation or breakage of the racket frame may occur at the part where the load is applied. The conventional badminton racket grommet has a problem that the grommet is damaged or the racket frame is deformed by pulling up several times in the tensioned portion. In Patent Document 1, a string is inserted through a grommet and a threaded cylinder, and a concave inward head is screwed into an outer hole. This cylinder is screwed in after tension is applied to the string, which pushes the grommet forward into the central conical section, compressing the grommet on the inserted string and locking the grommet in place. Proposed. Patent Document 2 proposes to attach a vibration damping material to at least a part of the string hole or a portion of the head portion on which the string is stretched, which is in contact with the string. According to the applicant, the grommet head portion has an oval shape or a rectangular shape, the grommet leg portion has a through hole, and the upper surface of the grommet head portion has a position in the major axis direction and passes through the through hole. We have proposed a grommet for a badminton racket in which a groove is formed in the grommet (Patent Document 3).

Special Table 2015-503996 Japanese Unexamined Patent Publication No. 2002-065903 Japanese Unexamined Patent Publication No. 2013-226298

However, the conventional grommets for rackets are damaged when they are pulled up with high tension, and there is a problem in durability.

In order to solve the above-mentioned conventional problems, the present invention provides a racket grommet having high durability and a racket to which the grommet is attached, which is not damaged even when repeatedly stretched with a high tension.

The racket grommet of the present invention is a racket grommet for stretching a string on a racket, and the grommet is a carbon fiber containing 10 to 40% by mass of pitch-based carbon fiber and 60 to 90% by mass of polyamide resin. It is characterized in that it is molded with a reinforcing resin.

The racket of the present invention is a racket in which the above-mentioned racket grommets are mounted in a plurality of grommets insertion holes.

The racket grommet of the present invention is formed of a carbon fiber reinforcing resin containing 10 to 40% by mass of pitch-based carbon fibers and 60 to 90% by mass of polyamide resin, so that it will be damaged even if it is repeatedly stretched with high tension. Instead, it is possible to provide a highly durable racket grommet and a racket equipped with the grommet.

FIG. 1 is a perspective view of a grommet according to an embodiment of the present invention. 2A-F are cross-sectional views of the grommet. 3A and 3C are top views of the two-connected grommets, and FIGS. 3B and 3D are cross-sectional views of the same. FIG. 4A is a side view of the 6-connected grommet, and FIG. 4B is a sectional view of the same. FIG. 5 is a schematic explanatory front view in which the grommet is inserted into the grommet insertion hole of the badminton racket and the string is stretched. FIG. 6 is a front view in which a string is stretched on a badminton racket.

The racket grommet of the present invention is inserted into the grommet insertion hole of the racket frame and used to stretch the string. This grommet is formed of a carbon fiber reinforcing resin containing 10 to 40% by mass of pitch-based carbon fibers and 60 to 90% by mass of a polyamide resin. The ratio is preferably 20 to 40% by mass of the pitch-based carbon fiber and 60 to 80% by mass of the polyamide resin, and more preferably 25 to 35% by mass of the pitch-based carbon fiber and 65 to 75% by mass of the polyamide resin. As a result, a grommet with high durability can be obtained without being damaged even if it is repeatedly pulled up with high tension.

There are isotropic pitch type and mesophase pitch type as pitch type carbon fiber, and both can be used. Although PAN-based carbon fibers are useful as long fibers, a fiber length of 2 mm or less is preferable for injection molding, and it is difficult to make the fiber length 2 mm or less.

The fiber length of the pitch-based carbon fiber is preferably 0.1 to 2 mm, more preferably 0.1 to 1 mm. This makes it suitable for injection molding. The average diameter of the carbon fibers is preferably 7 to 10 μm. The average diameter is sufficient to reinforce the grommet.

The polyamide resin is preferably at least one resin selected from polyamide 6, polyamide 66, polyamide and poly (metaxylylene adipamide) (hereinafter, polyamide MXD6). These resins have high mechanical strength, elastic modulus, rigidity, tensile strength, etc., and can be durable without being damaged even if they are repeatedly pulled up with high tension.

The racket grommet is preferably molded by injection molding. Injection molding has a short molding cycle and can mold grommets with high accuracy.

The racket grommet is useful for rackets such as badminton, hard tennis, soft tennis, and squash. It is particularly preferable to apply it to grommets for badminton rackets. This is because the badminton racket is required to be pulled up with high tension.

The racket of the present invention is a racket in which the above-mentioned racket grommets are mounted in a plurality of grommets insertion holes. In the case of a badminton racket, there are 76 grommet insertion holes as an example, and it is preferable to insert the grommet of the present invention into a part or all of them.

The carbon fiber reinforcing resin in which pitch-based carbon fiber is mixed with the polyamide resin used in the present invention is, for example, manufactured by Mitsubishi Chemical Co., Ltd., trade name "pyrofil pellet" series, product number N66-C-10 (polyamide 66 with pitch-based carbon fiber). 10 parts by mass mixed), N66-C-20 (20 parts by mass of pitch carbon fiber mixed with polyamide 66), N66-C-30 (30 parts by mass of pitch carbon fiber mixed with polyamide 66), N66-C-40 (mixed by 30 parts by mass) Polyamide 66 mixed with 40 parts by mass of pitch carbon fiber), N66MR-C-40A (Polyamide 66 mixed with 40 parts by mass of pitch carbon fiber), NX-C-30 (Polyamide MXD6 mixed with 30 parts by mass of pitch carbon fiber) , NXMR-C40B (Polyamide MXD6 mixed with 40 parts by mass of pitch-based carbon fiber).

Next, it will be described with reference to the drawings. In the drawings below, the same reference numerals indicate the same thing. FIG. 1 is a perspective view of the grommet 40 according to an embodiment of the present invention. The grommet 40 has a head portion 41 and a leg portion 42 integrally connected to the lower side thereof, and a hollow portion 43 penetrating in the vertical direction. The string passes through the hollow portion 43 and is stretched on the racket. The weight of each grommet is, for example, 0.040 g to 0.100 g, preferably 0.050 g to 0.080 g.

2A-F are cross-sectional views of the grommet. The dimensions of an example of the grommet 40a-40d in FIGS. 2A-D are as shown in Table 1.

3A and 3C are top views of the two-connected grommets, and FIGS. 3B and 3D are cross-sectional views of the same. The dimensions of an example of the grommet 40e in FIGS. 3A and 3B are as shown in Table 2.

FIG. 4A is a side view of the 6-connected grommet and a cross-sectional view of FIG. 4B. This 6-connected grommet is for inserting into a total of 6 grommet insertion holes at symmetrical positions on the left side of the grommet insertion holes 1 to 3 shown in FIG. 5 as an example.

FIG. 5 is a schematic explanatory front view in which a grommet is inserted into a grommet insertion hole (not shown) of the badminton racket 44 and a string 45 is stretched. Here, Table 3 summarizes the positional relationship between the grommet insertion holes Nos. 1-38 (including their symmetrical positions) shown in FIG. 5 and the grommet to be inserted.

In Table 3, when inserting 6-connected grommets, the grommets are inserted into a total of 6 grommet insertion holes at symmetrical positions on the left side of the grommet insertion holes 1 to 3, and the grommet 40d is not used in the insertion holes.

FIG. 6 is a front view in which a string is stretched on a badminton racket.

Hereinafter, a specific description will be given with reference to Examples. The present invention is not limited to the following examples. In the following examples, the evaluation was performed by the following method.
(Example 1)
30 parts by mass of pitch-based carbon fiber was mixed with polyamide MXD6, and injection molding was performed using the product name "Pyrofil pellet" series and product number NX-C-40 manufactured by Mitsubishi Chemical Corporation to obtain the grommets shown in FIGS.

(Comparative Example 1)
A conventional grommet (product name: AC43, manufactured by Gosen Co., Ltd., injection molded product of N12 resin, no reinforcing fiber) was used.

(Evaluation method)
As a badminton racket, a racket manufactured by Gosen, trade name "GRAVITAS 7.0SR" (face area is 51.5 square inches, stringing pattern is 22 mains, cross is 21) was used. The racket is made of full carbon and weighs 83-85 g. A racket equipped with a conventional grommet (product name: AC45N, manufactured by Gosen Co., Ltd.) (comparative example) and a racket equipped with the grommet of the present invention (example) were prepared. The mounting positions of the grommet and the racket are as described in FIGS. 2, 3 and 5.
The stretched string is electric using a general badminton string (manufactured by Gosen, trade name "G-Tone Five") with a nylon multifilament structure with an actual gauge of 0.65 mm that is on the market. It was pulled up by a type stringing machine.
The usual recommended tension for tension is about M26 and C28 lbs for the main string (hereinafter M) and cross string (C), but since the purpose of this evaluation method is to check the strength of the grommet and racket, the tension is set as the tension. M26 lbs (11.8 kg), C28 lbs (12.7 kg) (high school student class), M30 lbs (13.6 kg), C32 lbs (14.5 kg) (Olympic athlete class), M34 lbs (15.4 kg), C36 lbs (16.3 kg), respectively. ) (Promotion test level). As a verification method, after the string was pulled up, two players with a competition calendar of 10 years or more performed a trial hit using a shuttle cock for 30 minutes for each racket, and after the string was stretched, the string was replaced. This process was repeated and the number of times until the grommet or frame was damaged and became unusable was counted. Table 4 summarizes the conditions and results of Examples and Comparative Examples.

As shown in Table 1, it was confirmed that the grommet of Example 1 was not damaged even when repeatedly stretched with high tension, and had high durability. Further, the grommet of Example 1 was the same as the weight of Comparative Example 1. Further, the racket equipped with the grommet of Example 1 showed almost no difference in both the shot feeling and the hitting sound from the racket of Comparative Example 1. Further, since the grommet of Example 1 is a single-hole type, it was confirmed that the grommet is highly versatile regardless of the part number and the manufacturer of the badminton racket.

The racket grommet of the present invention is useful for rackets such as badminton, hard tennis, soft tennis, and squash. It is particularly preferable to apply it to grommets for badminton rackets.

1-38 Grommet insertion hole number 40, 40a-40f Grommet 41 Head part 42 Leg part 43 Hollow part 44 Badminton racket 45 String

Claims (7)

A racket grommet for stretching strings on a racket.
The grommet is a grommet for a racket, which is formed of a carbon fiber reinforcing resin containing 10 to 40% by mass of pitch-based carbon fibers and 60 to 90% by mass of a polyamide resin. The racket grommet according to claim 1, wherein the pitch-based carbon fiber has a fiber length of 0.1 to 2 mm. The racket grommet according to claim 1 or 2, wherein the carbon fibers have an average diameter of 7 to 10 μm. The racket grommet according to any one of claims 1 to 3, wherein the polyamide resin is at least one resin selected from polyamide 6, polyamide 66, polyamide 12, and poly (methaxylylene adipamide). The racket grommet according to any one of claims 1 to 4, wherein the racket grommet is molded by injection molding. The racket grommet according to any one of claims 1 to 5, wherein the racket grommet is a badminton racket grommet. A racket in which the racket grommets according to any one of claims 1 to 6 are mounted in a plurality of grommets insertion holes.

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