JP2009095601A - Golf club shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a golf club shaft capable of providing excellence in a sense of hitting and stability in a hit-ball direction while the shaft being made lightweight. <P>SOLUTION: The metal core shaft 2 consisting of a damping alloy with a loss coefficient not less than 0.1 and not greater than 0.5 damps vibrations generated at a hit of a golf ball. Interweaving backing fibers 4 to cross them upward and downward makes length per shaft unit length larger, propagating and diffusing the vibrations at a plurality of crosses to damp them to soften a sense of hitting. Forming the metal core shaft 2 and a fiber-reinforced resin 3 into a composite body prevents anisotropy of the shaft 1. The resin 3 reinforces the shaft 2 consisting of the damping alloy with relatively low strength. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a golf club shaft, and more particularly, to a golf club shaft capable of obtaining a good hit feeling and a stable hitting direction while reducing weight.

  Golf club shafts are roughly classified into non-metallic shafts made of a metal shaft and FRP (fiber reinforced resin). Non-metallic shafts have the advantage that they can be made lighter than metallic shafts. For example, they are manufactured by a sheet winding method in which an FRP sheet is wound around a mandrel and heat-cured. Anisotropy is greater than For this reason, it has been difficult for a non-metallic shaft to obtain a stable hitting direction as compared with a metallic shaft.

  Further, there is a hit feeling as a performance required for a golf club. When the same soft feeling is obtained both before and after the golf ball hits the head, it is generally evaluated that the hit feeling is good. Regarding the hit feeling, the metal shaft is more difficult to obtain a good hit feeling because the vibration generated in the head at the time of hitting is more easily transmitted to the hand than the non-metallic shaft.

  In recent years, for example, a manganese-based damping alloy has been proposed as a damping alloy having excellent vibration damping properties (see Patent Document 1). If a metal shaft is formed using such a vibration-damping alloy, it is possible to obtain a stable hitting direction and good hitting feeling, but metals with excellent vibration damping properties are generally low in strength, so they are durable. It is necessary to increase the thickness of the shaft in order to ensure the properties. For this reason, the vibration-damping alloy shaft is heavier than a general metal shaft, and there is a problem that the weight cannot be reduced.

As described above, it has been difficult to obtain a shaft that realizes all of the weight reduction, the hit feeling, and the improvement of the hitting direction.
Patent Publication No. 2800000

  An object of the present invention is to provide a golf club shaft capable of obtaining a good hit feeling and a stable hitting directionality while achieving weight reduction.

  In order to achieve the above object, a golf club shaft according to the present invention is a golf club shaft formed by integrating a metal core shaft and a fiber reinforced resin covering the metal core shaft, wherein the metal core shaft has a loss factor of 0. A base material made of a damping alloy of 1 or more and 0.5 or less and braided on the outer peripheral surface of the metal core shaft with the fiber reinforced resin wound thereon is cured with a resin material impregnated in the base fiber. It is characterized by being formed.

  Here, the damping alloy is, for example, a manganese-based damping alloy or a magnesium-based damping alloy. The number of filaments in the fiber bundle of the base fiber is, for example, 6000 or more and 24000 or less, and the mass of the shaft is, for example, 75 g or less.

  According to the present invention, in a golf club shaft configured integrally with a metal core shaft and a fiber reinforced resin covering the metal core shaft, the metal core shaft is made of a damping alloy having a loss coefficient of 0.1 to 0.5. Since it is formed, the damping with respect to the vibration generated when the golf ball is hit increases, and a soft and good hit feeling can be obtained. Here, since the base fiber constituting the fiber reinforced resin is braided and crosses up and down, the base fiber length per unit length of the shaft becomes longer, and vibration propagates and diffuses at a number of crossing points. By doing so, it becomes possible to further attenuate the vibration.

  In addition, since the base fiber is a composite with a fiber reinforced resin braided on the outer peripheral surface of the metal core shaft, the shaft hardly undergoes anisotropy, and a stable hitting direction can be obtained. .

  Furthermore, since the damping alloy with relatively low strength is reinforced by covering and integrating with a fiber reinforced resin, the increase in the thickness or outer diameter of the metal core shaft can be suppressed. It becomes possible to make it lighter than the shaft.

  The golf club shaft of the present invention will be described based on the embodiment shown in the drawings.

  As illustrated in FIGS. 1 to 3, the golf club shaft 1 of the present invention (hereinafter referred to as the shaft 1) is formed in a taper shape whose diameter is increased from one end side to the other end side in the longitudinal direction of the shaft. Has been. The taper gradient of the shaft 1 is about 8/1000 to 10/1000, and the length of the shaft 1 is about 30 inches to 48 inches, for example. A head is fixed to one end of the shaft on the small diameter side, and a grip member is attached to the other end side of the shaft on the large diameter side.

  The shaft 1 is a composite body in which a cylindrical metal core shaft 2 and a cylindrical fiber reinforced resin 3 covering the metal core shaft 2 are integrated. For example, about five layers of fiber reinforced resin 3 are laminated. The material of the metal core shaft 2 is a damping alloy having a loss coefficient of 0.1 or more and 0.5 or less so that vibration generated in the shaft 1 can be damped without excess or deficiency.

This loss factor is obtained when one end of a rod-shaped measurement sample of a predetermined length is fixed by a fixing jig, an acceleration pickup is attached to a predetermined position on the other end (free end) side, and the free end side is vibrated. Calculate based on the data. The calculation formula is the following formula (1).
Loss coefficient η = D / (27.3 · f) (1)
D: Attenuation per second (dB / sec)
f: Primary resonance frequency (Hz)

  Examples of the damping alloy used for the metal core shaft 2 include a manganese-based damping alloy and a magnesium-based damping alloy. As a manganese-based damping alloy, for example, M2052 damping alloy containing about 20 wt% copper (Cu), about 5 wt% nickel (Ni), and about 2 wt% iron (Fe) based on manganese (Mn) Can be used. As the magnesium-based damping alloy, an AZ91 damping alloy containing about 9 wt% aluminum (Al) and about 1 wt% zinc (Zn) based on magnesium (Mg) can be used.

  The fiber reinforced resin 3 is formed by heat-curing the resin material 5 impregnated in the base fiber 4 with the base fiber 4 braided and wound around the outer peripheral surface of the metal core shaft 2. When the resin material 5 is cured, the fiber reinforced resin 3 and the metal core shaft 2 are closely bonded and integrated. The fiber reinforced resin 3 and the metal shaft 2 can also be integrated by joining with a thermosetting adhesive.

  As the base fiber 4, carbon fiber can be used. In addition, aramid fiber, PBO fiber, Tyranno fiber, etc., or a combination of these plural types of base fibers 4 can also be used. As the resin material 5, for example, a thermosetting resin such as an epoxy resin, an unsaturated polyester resin, or a phenol resin is used.

  As described above, since the metal core shaft 2 constituting the shaft 1 is formed of a damping alloy having a loss coefficient of 0.1 or more and 0.5 or less, damping against vibration generated when a golf ball is hit is increased. Therefore, the vibration transmitted to the hand holding the shaft 1 is reduced, and a soft and good feel can be obtained.

  Here, since the braided base fibers 4 cross each other vertically, the length of the base fibers 4 per unit length of the shaft 1 is increased, and the vibration damping effect by the base fibers 4 is increased. It has an advantageous structure. Further, the vibration propagates at a large number of intersections between the base fibers 4 and spreads over a wide range of the fiber reinforced resin 3 and the metal core shaft 2, so that the vibration can be further attenuated.

  In this way, the same soft feeling can be obtained both before and after the golf ball hits the head.

  In addition, the fiber reinforced resin 3 is formed by winding the base fiber 4 around the outer peripheral surface of the metal shaft 2 in a spiral manner using the filament winding method, and curing the resin material 5 impregnated in the base fiber 4 with heat. In this case, the base fibers 4 do not cross each other up and down, and the fiber reinforced resin 3 is simply laminated on the metal core shaft 2. Therefore, the excellent vibration damping effect by the base fiber 4 as described above cannot be obtained, and it becomes difficult to obtain a good feel at the same level as the present invention.

  Furthermore, the shaft 1 is a composite of a metal core shaft 2 and a fiber reinforced resin 3 made of braided base fibers 4, so that the shape of the shaft 1 is different from that of a conventional non-metallic shaft by a sheet winding method. There is no directionality, and a stable hitting directionality equivalent to that of a conventional metal shaft can be obtained.

  Since the damping alloy has a relatively low strength, it is necessary to increase the thickness or diameter of the metal core shaft 2 to ensure a certain durability. In the present invention, however, the fiber reinforced resin that covers the outer peripheral surface is used. Since the reinforcement is performed by integrating the three, the increase in the thickness or outer diameter of the metal core shaft 2 can be suppressed. Therefore, it can be made lighter than a conventional metal shaft made of a damping alloy. For example, in order to make it easy to swing, the mass of the shaft 1 is preferably 75 g or less.

  Thus, in the shaft 1 of the present invention, it is possible to reduce the weight and improve the hit feeling and the hitting directionality.

  The number of filaments of the fiber bundle constituting one base fiber 4 is preferably 6000 or more and 24000 or less, for example. This is because if the number of filaments is less than 6,000, it is difficult to obtain a vibration damping effect, and if it exceeds 24,000, the strength of the base fiber 4 may be reduced.

  The braiding angle A of the base fiber 4 (orientation angle formed by the base fiber 4 and the shaft axis direction) is, for example, about 10 ° to 60 °. A line segment CL in FIG. 2 indicates the axis center of the shaft 1. A constant braid angle A may be set in the longitudinal direction of the shaft 1 or may be changed in the middle of the longitudinal direction. In the manufacturing process, the braid angle A can be easily adjusted, so that the fiber reinforced resin 3 can be coated so as to follow the change in the taper angle in the axial direction of the outer peripheral surface of the metal core shaft 2. Therefore, even if the outer peripheral surface of the metal core shaft 2 is formed in a concavo-convex shape in the axial direction, the fiber reinforced resin 3 can be adhered and covered without causing wrinkles or the like.

  As shown in Table 1, nine types of shaft test samples with different specifications (Examples 1 and 2, Conventional Examples 1 to 4, and Comparative Examples 1 to 3) were produced, and shaft performance (hitting feeling, hitting direction) Evaluated. The length and outer diameter of each test sample were the same, and the shaft thickness was set so as to have strength that could withstand practical use. "Metal + FRP" of the basic structure in the table is a composite shaft in which the outer peripheral surface of a cylindrical metal core shaft is coated with fiber reinforced resin, "Metal" is a cylindrical metal shaft, and "FRP" is a cylindrical shape A non-metallic shaft made of FRP is shown.

  Metal type M2052 is a manganese-based damping alloy, AZ91 is a magnesium-based damping alloy, and SAE8655 is steel. Regarding FRP, all the base fibers were carbon fibers (IM-600) having the same specifications, and the resin material (epoxy resin) was the same, and only the winding method of the carbon fibers was different. In the table, BD indicates braiding, SW indicates sheet winding, and FW indicates filament winding, which means that a fiber reinforced resin is formed by winding carbon fibers around a metal core shaft or mandrel. In the table, the loss coefficient η of the core shaft and the loss coefficient η1 of the completed shaft are shown. The loss coefficients η and η1 are numerical values obtained by the measurement method described above.

  The evaluation was performed by a total of 50 amateur golfers and professional golfers with a head speed in the range of 34 to 50 m / s. Each evaluator made a test shot of 10 balls using a golf club using the shaft of each test sample.

[Hit feeling]
Each evaluator scored the quality of the hit feeling at the time of trial hitting with each golf club, and indicated the average value of the evaluation scores. It is indicated by an index with the conventional example 1 as a reference (100). The larger the value, the softer and better the feel is.

[Hit direction]
It is a result of evaluating how much the respective evaluators have varied with respect to the target when they try to hit each golf club, and is a relative evaluation. A score was given as to how much the hit balls varied, and the average value of the evaluation scores was shown. It is indicated by an index with the conventional example 1 as a reference (100). The larger the numerical value, the smaller the variation in the hit ball direction, indicating that the hit ball direction is more stable.

  From the results shown in Table 1, by curing a metal core shaft made of a damping alloy having a loss factor of 0.1 to 0.5 and a resin material impregnated with a base fiber braided and wound around the metal core shaft The shafts of Examples 1 and 2 formed into a composite with the formed fiber reinforced resin are lighter than the conventional metal shaft (Conventional Example 1) and have equivalent stable hitting directionality. It could be confirmed. Moreover, it has confirmed that Examples 1 and 2 were able to obtain a favorable hit feeling compared with the conventional nonmetallic shaft (conventional examples 2-4).

It is a side view which illustrates the shaft for golf clubs of this invention. It is a partially expanded side view of the shaft of FIG. 1 which cuts and shows a fiber reinforced resin. It is a cross-sectional view of the shaft of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Golf club shaft 2 Metal core shaft 3 Fiber reinforced resin 4 Base fiber 5 Resin material

Claims (4)

  In a golf club shaft configured by integrating a metal core shaft and a fiber reinforced resin covering the metal core shaft, the metal core shaft is made of a damping alloy having a loss factor of 0.1 to 0.5, A golf club shaft, which is formed by curing a resin material impregnated in a base fiber in which a fiber reinforced resin is braided and wound around the outer peripheral surface of the metal core shaft.   The golf club shaft according to claim 1, wherein the damping alloy is a manganese-based damping alloy or a magnesium-based damping alloy.   The golf club shaft according to claim 1 or 2, wherein the number of filaments in the fiber bundle of the base fiber is 6000 or more and 24000 or less.   The golf club shaft according to claim 1, having a mass of 75 g or less.