JP3086353B2 - Method and apparatus for measuring bending condition of golf club shaft - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring the bending condition of a golf club shaft.

[0002]

2. Description of the Related Art A bend value is conventionally known as a parameter expressing the deflection of a golf club shaft. The bend value is the maximum displacement on the tip side when a fixed weight is hung on the tip (head) side while the butt (grip) side of the club shaft is fixed. The harder the material, the less the deformation, and the hardness can be represented by the magnitude of the bend value. However, depending on the bend value, it is not possible to know the overall bending condition (the bending condition) of the club shaft.

Another quantity that expresses the bending tone is the concept of a kick point. This indicates whether the most deformable part of the club shaft is on the tip side or butt side. The butt side and tip side in the above-described bend value measurement are interchanged, and a load is applied to the butt side to apply a bend value. (Bat side bend value) is measured in the same manner. The kick point is determined by the ratio of the bend value to the above-described bend value (chip-side bend value) (butt-side bend value / chip-side bend value). For example, a ratio of about 2.3 is referred to as a medium tone, a ratio larger than the ratio (eg, 3.0) is referred to as a first tone, and a ratio smaller than that (eg, 1.8) is referred to as an original tone. However, since this kick point is a dimensionless quantity and does not represent a length (distance), it is difficult to intuitively grasp the kick point.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and an apparatus for measuring the bending condition which can intuitively grasp the bending condition of a club shaft.

[0005]

SUMMARY OF THE INVENTION The present invention is based on the idea of using the deflection angle at or near the load point to measure the bending condition (deflection characteristics) of a club shaft as an amount that can be more intuitively grasped. It is. According to the present invention, a golf club shaft is arranged in a substantially horizontal x-axis direction, its grip side is fixed, and a load is applied to its free end side to deflect the club shaft. The intersection point between the load point of the curve or a tangent at a point near the grip side from the load point and the x-axis is determined, and the distance λ from the specific point on the fixed end side or free end side of the club shaft to this intersection point is determined. It is characterized in that this distance λ is used as a bending tone expression quantity (parameter).
Since the amount of expression of the bending tone has a dimension of distance (length), it is possible to intuitively grasp a portion where the club shaft is likely to bend.

[0006] According to one aspect of the device of the present invention,
Means for arranging the club shaft in a substantially horizontal x-axis direction, fixing the grip side of the club shaft, and applying a constant load to a portion separated from the free end by a predetermined distance; a neutral shaft of the club shaft in an unloaded state Means for determining the displacement amount of the applied point and the free end, respectively; and the two displacement amounts, the distance S ₀ -Z from the fixed end to the applied point, and the distance Z from the free end to the applied point. Means for approximating the λ / S ₀ ratio using: λ is the tangent at the load point of the deflection curve of the club shaft from the fixed end when the above load is applied to the club shaft. It means the distance to the intersection that crosses the axis.

According to another aspect of the device of the present invention, a golf club shaft is arranged in a substantially horizontal x-axis direction, the grip side of the club shaft is fixed, and a constant load is applied to a free end thereof. Means for determining: at least two measurement points separated by a distance d on the grip side from the point of application of the load, means for determining the amount of displacement from the x-axis to the two measurement points in the loaded state; and the two displacements Means for approximating the λ / P ratio using the quantity, the distance P from the fixed end to the intermediate point of the two measurement points, and the distance d / 2 from the intermediate point to the two measurement points. Where λ means the distance from the fixed end to the intersection point where the tangent of the deflection curve of the shaft at the intermediate point intersects the x-axis when the load is applied to the club shaft. According to the above apparatus, the λ / S ₀ ratio, λ / P ratio, and λ
Can be easily calculated and displayed.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 shows a conceptual diagram of a method for measuring the bending condition of a club shaft according to the present invention. According to the method of the present invention, first, the club shaft 11 is held in the substantially horizontal x-axis direction, and the grip G side thereof is fixed to form a cantilever.
A constant load W is applied to the free end T of the shaft to flex the club shaft 11 (displacement amount δ). Although the amount of deflection is exaggerated in the drawing, the amount of deflection during actual measurement is small, and the deflection is assumed to occur in a direction perpendicular to the x-axis.

In this bending state, a tangent line V at a load point T of the bending curve D of the club shaft 11
An intersection R with the x-axis is obtained (deflection angle θ). Then, the distance λ from the fixed end G of the intersection R is used as the bending tone expression amount. Alternatively, the length (total length) from the fixed end G to the free end T of the club shaft 11 is S ₀ , and the ratio λ
/ S ₀ is another expression amount of the bending tone. Therefore, the larger the distance λ and the ratio λ / S ₀ , the more the tone (the easy-to-bend is closer to the free end T). Then, according to the distance λ and the ratio λ / S _0, it is possible to intuitively know the bending condition of the club shaft 11 depending on the magnitude.

According to the method of the present invention, as shown by a chain line in FIG. 1, a deflection curve D ′ different from the free end portion (adhesion point) T on the grip G side due to the difference in the bending rigidity distribution of the club shaft 11. Even if it is obtained, there is an advantage that as long as the deflection angle θ and the displacement amount δ are the same, the same bending condition can be evaluated. That is, since the actual club shaft has a different bending stiffness distribution in the longitudinal direction, even if the same deflection angle θ and the same amount of displacement δ are shown, different deflection curves may be obtained. However, according to the bending tone expression amount λ of the present invention, even if the deflection curves are sufficiently different from the applied point T on the grip G side, the club shafts exhibiting the same deflection angle θ and the deflection amount δ have the same bending tone. Can be evaluated as

The distance λ can be obtained by calculation from the deflection amount δ, the deflection angle θ, and the total length S _{0 in} a small range of θ which is θ (radian) ≒ tan θ. That is, tan θ = δ / (S ₀ −λ) ≒ θ S ₀ −λ = δ / θ λ = S ₀ −δ / θ λ / S ₀ = 1−δ / S ₀ θ

[0012] full-length S _0, in this formula, is a distance from the fixed end G to the load point T, S in the ratio lambda / S ₀
The value of ₀ does not need to be exactly this distance, and the entire length of the club shaft 11 or a length in the vicinity thereof can be used.

In the above description, the tangent at the load point S has been discussed. However, in a range where the load W (displacement amount δ) is small, the club shaft 11 can be regarded as a straight line near the load point. Therefore, the grip G is more than the load point T.
A tangent at a specific point on the side may be discussed, and a position (distance λ) at which the tangent intersects the x-axis may be used as an expression amount of the bending tone.

Further, in the above embodiment, the fixed end G is a specific point for measuring the distance λ. However, the specific point is, for example, a free end T, and a distance (length) from the free end to the intersection R. May be used as the amount of expression of the bending tone.

FIG. 2 shows a first embodiment of a measuring apparatus for easily obtaining the λ / S ₀ ratio. This device applies a load W to a point T ₁ that is separated from the free end T of the club shaft 11 by a distance Z, and calculates the displacement points δ ₁ and δ ₂ from the x-axis at the applied point T ₁ and the free end T. This is measured by the displacement sensors 12 and 13. The displacement amounts δ ₁ and δ ₂ detected by the displacement sensors 12 and 13 are input to an arithmetic unit 14, where λ or (and) λ / is calculated using the known distances Z and S _0.
S ₀ is calculated and displayed on the display 15. λ = S ₀ −δ ₁ · Z / (δ ₂ −δ ₁ ) λ / S ₀ = 1− {δ ₁ · Z / (δ ₂ −δ ₁ ) · S ₀ }

FIG. 3 is a principle diagram of another measuring apparatus. This device applies a load W to a load point T at a free end of the club shaft 11. In the range where the deflection is small, a fixed short distance from the load point T to the grip G can be regarded as a straight line. Grip G that can be regarded as a straight line
From a point T ₂ of length P to a measurement point T at a distance d / 2 before and after
₃ and T ₄ , x at the measurement points T ₃ and T ₄
Assuming that the displacements from the axes are δ ₃ and δ ₄ , the expression quantities λ and λ / P of the bending tone can be obtained by the following equations.

Λ = P− {2 (δ ₃ + δ ₄ ) d} / (δ ₄ −δ ₃ ) λ / P = 1− {2 (δ ₃ + δ ₄ ) d} / (δ ₄ −δ ₃ ) P Specific measurement of δ ₃ and δ ₄ can be performed according to the apparatus of FIG.

[0018]

As described above, according to the method of the present invention, the bending condition of the club shaft can be measured intuitively. Further, according to the apparatus of the present invention, the bending tone can be easily obtained by an approximate calculation.

[Brief description of the drawings]

FIG. 1 is an explanatory view illustrating a principle of a method of measuring a bending condition of a golf club shaft according to the present invention in a skeleton.

FIG. 2 is an explanatory view illustrating a specific example of a measuring device of the bending condition of a club shaft according to the present invention in a skeleton.

FIG. 3 is an explanatory view illustrating another specific example of a method and an apparatus for measuring a bending condition of a golf club shaft according to the present invention in a skeleton.

[Explanation of symbols]

11 Club shaft S ₀ Overall length λ Distance (Bending tone expression amount) D Deflection curve V Tangent line R Intersection point W Constant load 12 13 Displacement sensor 14 Computing unit 15 Display

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01B 21/00-21/32 A63B 53/00

Claims (5)

(57) [Claims] 1. A golf club shaft is arranged in a substantially horizontal x-axis direction, its grip side is fixed, and a load is applied to its free end to bend the club shaft. The intersection of the x-axis and the tangent at the load point of the deflection curve or at a point near the grip side from the load point is determined, and the distance from the specific point on the fixed end side or free end side of the club shaft to this intersection point A method for measuring the bending condition of a golf club shaft, wherein λ is obtained, and the distance λ is used as an expression amount of the bending condition. 2. The method according to claim 1, wherein the total length of the club shaft is S ₀ , the distance from the grip-side fixed point to the intersection is λ, and λ / S ₀ is another expression of the bending tone. A method for measuring the bending condition of a golf club shaft. 3. A step of disposing a golf club shaft in a substantially horizontal x-axis direction, fixing a grip side of the golf club shaft, and applying a load to a free end side of the golf club shaft; Determining an intersection between the load point or a tangent at a point closer to the grip side than the load point and the x-axis; and determining a distance from a specific point on the fixed end side or free end side of the club shaft to this intersection point. Determining the bending condition of the golf club shaft. 4. A means for arranging a golf club shaft in a substantially horizontal x-axis direction, fixing a grip side of the club shaft, and applying a constant load to a portion separated from a free end thereof by a predetermined distance; Means for determining the displacement of the applied point and the free end from the neutral axis of the club shaft in the state; and the two displacements and the distance S ₀ − from the fixed end to the applied point.
Using Z and the distance Z from the free end to the point of application, λ / S
Means for approximating the ₀ ratio; where λ is the distance from the fixed end to the intersection of the tangent at the load point of the deflection curve of the shaft with the x-axis when the load is applied to the club shaft; An apparatus for measuring the bending condition of a club shaft, characterized in that: 5. A means for arranging a golf club shaft in a substantially horizontal x-axis direction, fixing a grip side of the club shaft, and applying a constant load to a free end thereof; Means for determining at least two measurement points separated by a distance d from the x-axis to two displacement points from the x-axis to two load-measurement points; and Means for approximating the λ / P ratio using the distance P to the intermediate point and the distance d / 2 from the intermediate point to the two measurement points;
When the above load is applied to the club shaft,
The tangent to the shaft deflection curve at the midpoint is x
An apparatus for measuring a bending condition of a club shaft, comprising: a distance to an intersection point intersecting with an axis;