JP2008212340A - Shaft of golf club - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shaft which can increase a carry because a striking angle is large even in a golfer with a comparatively slow head speed. <P>SOLUTION: The shaft for a golf club having a shaft length of 1,100 mm or more has a difference in the flexural rigidity value of 5 kg m<SP>2</SP>or higher between the 150 mm position of a leading edge and that of a 950 mm position from the leading edge and a flexural rigidity value of 2 kg m<SP>2</SP>or lower at the 150 mm position of the leading edge. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a golf club shaft, and more particularly to a shaft having a length of 1100 mm or more.

  Conventional shafts for golf clubs are designed to be rigid for each head speed so that an appropriate amount of deformation corresponding to the golfer's head speed can be obtained. If a golfer with high head speed uses a shaft with low rigidity, the amount of deformation of the shaft becomes too large, the timing is difficult to take, the direction of the flying ball varies, the ball blows up, and the feeling surface is also unreliable You will feel it.

  On the other hand, if a golfer with a slow head speed uses a shaft with high rigidity, the amount of deformation of the shaft cannot be obtained sufficiently, so that the flight distance is lost and the feel at impact is hard, which makes it difficult.

  For golfers having a head speed of about 35 m / s to 40 m / s or 38 m / s to 43 m / s, the shaft hardness is generally indicated by “R” (regular), and is intended for general amateur golfers. The hardness of the shaft when it exceeds 43 m / s is generally indicated by “S” and “X”, and when it is less than 35 to 38 / s, it is generally indicated by “L”.

In order to obtain the optimum shaft corresponding to the head speed, a shaft with an optimal bending stiffness distribution was developed. The length of the shaft is 1100 mm or more and 1220 mm or less, and a region M having a length of 200 mm to 500 mm is provided within a range of 400 mm to 900 mm from the grip side end of the shaft, and 0 mm from the grip side end of the shaft. A region H having a length of 100 mm to 450 mm is provided in a region of ˜450 mm, and the region M and the region H do not overlap each other, and within the respective ranges of the region M and the region H, from the head side to the grip side. The bending stiffness is increased toward the surface, and the value X of (bending stiffness change rate in the region H / bending stiffness change rate in the region M) is set to 1.0 ≦ X ≦ 5.0 (see Patent Document 1). ). By setting this "X" value small, it can be designed for a less powerful golfer with a relatively slow head speed, and conversely, by designing a large "X" value, it corresponds to a golfer with a fast head speed. It can be done.
Japanese Patent Laid-Open No. 2002-177423 (page 3, FIGS. 1 and 3)

The prior art disclosed in Patent Document 1 also basically uses a hard shaft at hand for a golfer with a fast head speed, and conversely uses a soft shaft at hand for a golfer with a slow head speed. Even if it is a shaft for a general amateur golfer indicated as “R”, the tip is hard even if the hand is soft (in the case of Patent Document 1, as shown in FIG. 3, at the tip of the shaft 1000 mm from the grip end. Since the bending stiffness value is over 2 kg · m ² ), the ball does not rise.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a golf club shaft that can easily raise a ball and increase a flight distance even with a general amateur golfer having a relatively slow head speed.

In order to achieve the above-mentioned object, according to the present invention, in a golf club shaft having a shaft length of 1100 mm or more, the difference between the bending rigidity value at the position of 150 mm from the tip and the bending rigidity value at the position of 950 mm from the tip is 5 kg · m. is ² or more, and the bending rigidity of the position of the tip 150mm has a 2 kg · ^{m 2} or less.

According to the present invention, in the golf club shaft having a shaft length of 1100 mm or more, the difference between the bending rigidity value at the position of 150 mm and the bending rigidity value at the position of 950 mm from the tip is 5 kg · m ² or more. Since the bending rigidity value at the position of 150 mm is 2 kg · m ² or less, increasing the difference in rigidity value (EI value) increases the shaft deflection immediately before impact, resulting in a high launch angle, It leads to increase. The fact that the EI value at the tip is also 2 kg · m ² or less works effectively in obtaining the effect of a high launch angle.

  Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a golf club called a so-called driver. The total length (shaft length) of the shaft 1 is 1100 mm or more, and the tip of the shaft 1 is inserted into and fixed to the head 2. A grip 3 is attached to the base end of the shaft 1, and positions of 150 mm, 200 mm, 250 mm, 850 mm, 900 mm, and 950 mm from the tip of the shaft 1 are displayed in the drawing. And the bending rigidity value (EI value) in each position of these shafts 1 sets each average value of each position EI value of 150 mm, 200 mm, and 250 mm to 1.8 kg · m ² or less, and each of 850 mm, 900 mm, and 950 mm. The average value of the EI values of the positions was set to 6.5 kg · m ² or more. The difference between the EI value at the position 150 mm from the shaft tip and the EI value at the position 950 mm is set to 5 kg · m ² or more, and the EI value at the position 150 mm from the shaft tip is set to 2 kg · m ² or less. .

  The shaft 1 is preferably made of a fiber reinforced resin and formed of a laminate of fiber reinforced prepregs. With such a shaft 1, it is possible to easily reinforce partially and to change the rigidity easily. In order to change the rigidity of the shaft 1, it is only necessary to change the elastic modulus of the reinforcing fiber, such as the length and shape of the prepreg, the arrangement position, and the like.

  As described above, in the present invention, the EI value at the position of the tip 150 mm of the shaft 1 and the EI value at the position 950 mm are measured at the position of 150 mm as the position at which the tip can be measured most by the three-point bending test method. This is because. In the measurement of the EI value by three-point bending, if the span is narrowed, the measurement error increases. Therefore, about 300 mm is considered appropriate for a golf shaft. The reason why it is 950 mm is that the shaft for wood, particularly the shaft used for the driver, is as long as 1100 mm or more. In recent years, metal heads with a shaft that does not extend to the end of the sole have become the mainstream, and even women's clubs have club lengths of 43.5 inches or more and 45 inches or less, and men's use is 44.5 inches or more. This is because the length of 46 inches or less is the mainstream.

The shaft 1 is a shaft of a regular size that is a general-purpose shaft, so-called “R”, and the EI value at the position of the tip 150 mm is 2 kg · m ² or less. It is in the range of ˜2 kg · m ² . The difference in EI value between a position of 150 mm and a position of 950 mm of a conventional general shaft is 3.2 to 4.8 kg · m ² . By making it larger than the conventional difference in rigidity, the deflection of the shaft increases immediately before impact, and as a result, the launch angle of the ball increases and the flight distance can be increased. In particular, the tip portion of the shaft 1 should be long and have low rigidity, and the hand portion should have a certain length (shorter than the length of the tip portion) to be highly rigid.

As described above, the tip 150mm of the shaft 1, 200 mm, the average value of the rigidity values of 250mm is 1.8 kg · ^{m 2} or less, preferably a 1.6~1.8kg · ^{m 2,} and 850mm from the tip, 900 mm, the average value of the rigidity values of the position of 950mm is 6.5 kg · ^{m 2} or more, or preferably, if it is 6.5~7.0kg · ^{m 2.} Furthermore, it is preferable to lengthen the low-rigidity region at the tip because the ball direction is stabilized. Specifically, the tip 150mm, 200mm, 300mm, 350mm, 400mm, 450mm, the average value of the rigidity values of 500mm is 2.0 kg · ^{m 2} or less, preferably 1.8~2.0kg · ^{m 2.}

If the rigidity value of the shaft tip is too low, it will be too soft and the ball will not be stable. If it is too high, it will be difficult to raise the sphere. If the rigidity value at the hand is too low, the difference in rigidity from the tip is reduced, so that it is difficult to raise the sphere. If it is too high, the swing timing will be difficult. The peak of the rigidity change rate is at the tip of a general shaft, and the length at which the hand becomes harder is lengthened. The rigidity change rate changes greatly from the high rigidity area on the hand side to the low rigidity area on the tip side (stiffness change rate). The shaft tip side bending can now be used successfully. In the case of a normal shaft, 800 mm to 850 mm from the tip is common, but it is set to be between 750 mm and 800 mm from the tip. The peak value of the rigidity change rate is preferably 1.6 × 10 ⁻² kg · mm ^{7 to} 2.2 × 10 ⁻² kg · mm ⁷ . If the rigidity is extremely increased, stress is concentrated on a part of the shaft, which is not preferable in terms of strength. If the rate of change in rigidity is too low, the shaft will bend during the swing, and the launch angle will be low, making it difficult for the golfer with a slow head speed to fly.

The rigidity change rate is 1 × 10 ⁻² kg · mm ⁷ or more, preferably 1.3 × 10 ⁻² kg · mm ⁷ at three points of 700 mm to 750 mm, 750 mm to 800 mm, and 800 mm to 850 mm. As described above, 2.2 × 10 ⁻² kg · mm ⁷ or less is preferable. And other stiffness change rate is less than 1 × 10 ⁻² kg · mm ⁷ , preferably 0.9 × 10 ⁻² kg · mm ⁷ or less, 0.07 × 10 ⁻² kg · mm ⁷ or more, and from the tip By increasing the rigidity from 700 mm to 850 mm, the area of the length from the tip to less than 700 mm is made a low rigidity area, the shaft is easily bent, and the 850 mm area is made a high rigidity area, even in a golfer with a slow head speed. The launch angle is increased, and the effect of increasing the flying of the ball can be obtained.

  By making the part with a higher rigidity value on the hand side longer than the normal golf shaft, conversely softening the tip part and providing a difference in rigidity value, the tip including the shaft tip part during the swing is more concentrated Therefore, the entire tip of the shaft 1 is easily bent, the ball direction is stabilized, and the flight distance of the ball is increased. On the other hand, the softening to the hand (bat) side makes the shaft easier to bend as a whole, so the ball is stable, but since the rate of change in the stiffness value is small, the force is dispersed throughout the ball, making it difficult for the ball to rise. Not suitable for powerless golfers. Therefore, on the bat side, a fiber layer is arranged in the length direction of the shaft 1, which is called a straight layer, and a large amount of highly elastic carbon fiber fiber reinforced resin (elastic modulus 40 tons) is laminated. The rigidity value is increased. On the other hand, in order to provide a uniform diameter at the tip of the straight portion of the tip for attaching to the metal head to about 8.5 to 9.5φ and a length of 30 to 100 mm, carbon fiber having a modulus of elasticity of 10 tons is attached to the shaft. The fiber reinforced resin of high elasticity carbon fiber in which the direction of the fiber is arranged in the length direction is arranged in the length direction of the shaft so that the diameter of the diameter is uniform. Although the glass fiber itself has a low rigidity value, the glass fiber reinforced resin has a large fiber diameter, which increases the thickness. For this reason, an increase in the rigidity value of the tip is minimized.

The measuring method of the bending stiffness value is a distance L300mm between fulcrums, a cylindrical pressure support is provided at the center, that is, a position 150mm from both sides, and a deflection amount δ when a load W of 20 kg is applied is measured to obtain an EI value.
(Formula) ... EI = 1/48 x (WL ³ / δ) [kg · m ² ]
However, when measuring the position of the tip 150 mm, the distance L between the fulcrums was 290 mm, and measurement was performed by setting a cylindrical pressure support at a position 145 mm from both sides. Thereby, the EI value at the measurement position of the shaft can be obtained. The EI value was measured from a position 150 mm from the tip of the shaft up to 950 mm with a measurement interval M of 50 mm. The shaft of the test body is a shaft for a driver made of carbon fiber reinforced resin and is 1100 mm or more. The rigidity change rate is obtained by calculating the difference in EI value at each adjacent measurement position and dividing by 50 mm which is the distance between each measurement. That is, for example, when the EI value at the measurement position of 150 mm is E15 and the EI value at the measurement position of 200 mm is E20, the measurement interval M is 50 mm, so it is obtained as follows. In order to align the units of the EI value, m (meter) is changed to mm (mm) and the stiffness change rate is displayed.
(Formula) ... (E20-E15) / 50 [kg · mm ⁷ ]

  As an example of the present invention, a shaft 1 having two characteristics as shown in Table 1 was manufactured (Examples 1 and 2). Four types of commercially available “R” -displayed driver shafts were prepared, and these were used as Comparative Examples 1 to 4 to measure the bending stiffness values at each position. This is shown in Table 1.

  Table 2 shows the rigidity values at the positions of 150 mm and 950 mm in Examples 1 and 2 and Comparative Examples 1 to 4 shown in Table 1, and the difference between these rigidity values.

  Next, Table 3 shows the average value of the stiffness values at the tips 150 mm, 200 mm, and 250 mm and the average value of the stiffness values at positions 850 mm, 900 mm, and 950 mm from the tip.

  Further, Table 4 shows the average of the rigidity values from the position of the tip 150 mm to the position of 500 mm in units of 50 mm.

The rigidity change rate described above preferably has a peak between 750 mm and 800 mm from the tip. The position of 750mm stiffness change rate from 700 mm, the position of 800mm from ^{750mm, 1 × 10 -2 kg ·} mm 7 or from 800mm at three points position of 850 mm, and other rigid change rate is 1 × 10 ^- It is preferably less than ² kg · mm ⁷ . Such rigidity change rate was also measured for each of Examples 1 and 2 and Comparative Examples 1 to 4, and the results are shown in Table 5.

  Based on the structure of the commercially available carbon shaft of Comparative Example 1 above, the grip side rigidity value is increased, and the reinforcing layer prepreg of the straight layer on the hand side is arranged 10 mm longer than usual to reinforce from the tip to around 700 mm. went. As a result, it can be within the scope of the present invention.

  Table 6 (35 m / s) shows the evaluation of actual hits made by the golfers having the head speeds of 35 m / s and 38 m / s with the drivers equipped with the shafts of Examples 1 and 2 and Comparative Examples 1 to 4 described above. 7 (38 m / s).

  FIG. 2 is a graph showing the rigidity distribution of the shafts of Examples 1 and 2 and Comparative Examples 1 to 4 shown in Table 1.

  FIG. 3 is a graph of the measured stiffness change rate shown in Table 5.

The front view which shows a golf club. The graph which shows the rigidity distribution of each shaft. The graph which shows the rigidity change rate of each shaft.

Explanation of symbols

1 Shaft 2 Head 3 Grip

Claims (4)

In a golf club shaft having a shaft length of 1100 mm or more,
The difference between the bending stiffness value at the position of the tip 150 mm and the bending stiffness value at the position 950 mm from the tip is 5 kg · m ² or more,
A golf club shaft having a bending rigidity value of 2 kg · m ² or less at a position at a tip of 150 mm. The average bending stiffness value at the tip 150 mm, 200 mm, 250 mm is 1.8 kg · m ² or less, and the average bending stiffness value at positions 850 mm, 900 mm, 950 mm from the tip is 6.5 kg · m ² or more. The golf club shaft according to claim 1, wherein the golf club shaft is provided.   3. The golf club shaft according to claim 1, wherein the peak of the rate of change in rigidity is between 750 mm and 800 mm from the tip of the shaft. The rigidity change rate is 1 × 10 ⁻² kg · mm ⁷ or more at three points of 700 to 750 mm from the shaft tip, 750 to 800 mm, and 800 to 850 mm, and other stiffness change is 1 × 10 ^The shaft for a golf club according to any one of claims 1 to 3, wherein the shaft is less than ^-2 kg · mm ⁷ .

Images