JPH0793953B2 - Wood club head for golf - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention relates to a golf wood club head having an improved head shape, and the entire surface of the head body other than the face surface is egg-shaped. The smooth curved surface prevents the generation of extra lift due to the air flow flowing along the ball striking direction on the head surface during the swing and stabilizes the swing trajectory.

(Prior Art) Generally, when swinging a wood club from a take-back to an impact, the flow of an air flow generated around the club head has a great influence on the head speed and the stability of the swing trajectory.

Conventionally, in this type of golf wood club head, as shown in FIG.
Has a predetermined loft angle according to the count, and its upper surface (crown surface) 3 is a streamlined spherical surface with the back surface 4 side in the ball striking direction X, and the lower surface (sole surface) 5 is the ball striking direction. X is formed into a substantially flat surface which is straight toward the back surface 4 side, and these face surface 2, crown surface 3,
The back surface 4, the sole surface 5, and the toe-heel side surface 6, 7 are separated by ridge lines a, b, c, d, e, f, g with corners at their respective boundaries. It has a unique shape.

In this case, the definition of the ridgeline of the boundary part is that the radius of curvature of the boundary part where one surface and another surface are in contact with each other is 5 mm or less.

With such a conventional wood club head,
Since the ridgelines a and b are formed at acute angles with corners at the boundary between the crown surface 3 and the sole surface 5 that are connected to the upper and lower edge corners 2a and 2b of the face surface 2 of the head body 1, As shown in FIG. 5, when swinging in the ball striking direction X, the flow of the air flow generated around the head body 1 (indicated by the solid line arrow in FIG. 5) causes the upper and lower edge corners 2 of the face surface 2 to move.
Immediately after a and 2b, turbulence is greatly disturbed, and laminar flow separation occurs in the laminar boundary layer. The turbulence due to this laminar flow separation causes the transition from laminar flow to turbulent flow. A peeling area is generated in the front surface of the head body 1, and a pressure difference is generated between the front surface 2 of the head body 1 and the front surface 2.

By the way, in fluid mechanics, an object placed in a flow receives a force from a fluid, of which a component acting in a direction perpendicular to the main flow is called a lift force, and a component acting in a direction parallel to the main flow is called a drag force. Then, this drag is an object, that is, the head body 1
It is divided into a pressure drag obtained by integrating the pressure distribution acting on and a friction drag obtained by integrating the shear stress. In a flow with no separation of the laminar environment layer, the friction drag is large and accompanied by separation. In the flow, the pressure drag is large.

(Problems to be Solved by the Invention) However, in the above-described wood club head having the conventional structure, due to the pressure resistance generated by the pressure difference at the time of swing,
Due to the negative pressure action of the separation area formed behind the separation point of the laminar flow environment layer, not only the head speed is decreased and the flight distance of the ball is reduced, but also the negative lift force F ₀ due to the loft formation of the face surface 2 Is smaller than the positive lift force F ₁ due to the unique airfoil shape formed by the crown surface 3 and the sole surface 5 (F ₀ <F ₁ ), the positive lift force F ₁ influences too much, There was a problem of making the swing trajectory unstable.

The present invention has been made under the above circumstances, and an object thereof is to cancel a negative lift force and a positive lift force at the time of swing to stabilize a swing trajectory. To provide a wood club head for golf.

[Configuration of the Invention] (Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention forms the sole surface of the head body into a spherical convex surface having a predetermined radius of curvature rounded in all directions. In addition, the ridgelines at the boundaries between the crown surface, the back surface, the sole surface, and the toe / heel side side surfaces other than the ridgelines at the boundaries with the face surface are eliminated. In this case, it is preferable that the sole surface of the head body is formed into a spherical convex surface having a radius of curvature of 0.2 m or more and 0.5 m or less.

(Working) That is, according to the present invention, the sole surface of the head body is formed into a spherical convex surface having a radius of curvature of 0.2 m or more and a radius of curvature of 0.5 m or less, which is rounded in all directions. The negative lift due to the loft formation of the surface and the positive lift due to the crown surface and the sole surface are offset, and the swing trajectory is accurately maintained.

Also, except for the ridgelines at the boundary with the face surface, the ridgelines at the boundaries between the crown surface, the back surface, the sole surface, and the toe / heel side side surfaces are eliminated, and the entire surface is an egg-shaped smooth curved surface. In addition, since the boundary between the back surface and the sole surface is eliminated, the laminar boundary layer of the air flow generated on the face surface during swinging is the boundary between the face surface and the sole surface. Even if it is once peeled off, it is redeposited on the rear side of the back surface side, the pressure resistance can be reduced, and the air resistance is reduced, whereby the reduction in head speed is prevented.

[Examples] The present invention will be described below with reference to the examples shown in FIGS. 1 to 3. In the illustrated embodiment according to the present invention, portions having the same structures as those of the conventional structure shown in FIGS. 4 and 5 will be described using the same reference numerals.

As shown in FIGS. 1 and 2, the head body 1 of the golf wood club according to the present invention has a sole surface 5 formed into a spherical convex surface having a predetermined curvature radius Rs rounded in all directions. At the same time, the ridgelines of the boundary portions between the crown surface 3, the back surface 4, the sole surface 5, and the toe / heel side side surfaces 6 and 7 other than the ridgelines a and b of the boundary portion with the face surface 2 are defined. It has a structure that is smoothed and eliminated.

In this case, the radius of curvature Rs of the spherical convex surface forming the sole surface 5 of the head body 1 is 0.2 m or more and 0.5 m or less (0.2 m
<Rs <0.5m) is preferable. Below 0.2m, the crown surface 3 and the sole surface 5 at the time of swinging.
The positive lift force F _{1 due} to becomes too small and is susceptible to the negative lift force F ₀ due to the loft formation of the face surface 2, and
If it is 0.5 m or more, the positive lift F ₁ due to the crown surface 3 and the sole surface 5 becomes too large, which causes the same problem as in the conventional structure.

Thus, according to the above-described structure of the golf wood club head according to the present invention, the sole surface 5 of the head body 1 is
Is a spherical convex surface having a radius of curvature Rs of 0.2 m or more and 0.5 m or less that is rounded in all directions, and the face surface 2
Of the crown surface 3, the back surface 4, the sole surface 5, and the toe / heel side side surfaces 6 and 7 other than the ridgelines a and b of the boundary of the Since it is formed to have a smooth curved surface of the mold, the second
As shown in the figure, the negative lift F ₀ due to the loft formation of the face surface 2 at the time of swinging and the positive lift F ₁ due to the crown surface 3 and the sole surface 5 cancel each other (F ₀ = F ₁ ).

Further, since the boundary between the back surface 4 and the sole surface 5 of the head body 1 is eliminated, the laminar boundary layer of the airflow generated on the face surface 2 during swinging is the lower edge corner portion 2b of the face surface 2. Even if it peels off once at the boundary with the sole surface 5,
Redeposition occurs on the back side of the back surface 4 side to reduce the pressure resistance and reduce the air resistance.

FIG. 3 shows, for example, a prototype of a wood club head according to the invention having a sole surface curvature radius Rs of 0.3 m (a), a wood club head having a sole surface curvature radius Rs of 0.16 m (b), and a sole surface curvature radius. Lift coefficient (C) between a wood club head with Rs of 0.14 m (c) and a wood club head with a radius of curvature Rs of 0.8 m (d); C = F / [(1/2) ・ v ²・ ρ・ A] However, F: Lifting force v: Head speed ρ: Air density A: The projected area in the ball striking direction (traveling direction) was measured for each of three head speeds when swinging, and compared with three bar graphs. In the figure, the left upper right diagonal display of the three bar graphs is 30 m / sec, the middle dot display is 40 m / sec, the right upper left diagonal display is 50 m / sec. , As is clear from this result, the prototype (a) of the present invention is B) (c) (lift coefficient than two) it is the smallest was found.

[Effects of the Invention] As is apparent from the above description, according to the present invention, the sole surface of the head body is formed into a spherical convex surface having a predetermined curvature radius rounded in all directions. The negative lift force due to the loft formation of the face surface at this time and the positive lift force due to the crown surface and the sole surface can be offset, and thus the swing trajectory can be stabilized.

In addition, since the ridgelines at the boundary portions between the crown surface, the back surface, the sole surface, and the toe / heel side side surface other than the ridgelines at the boundary portion with the face surface are eliminated, the back surface is particularly Since there is no boundary between the sole surface and the sole surface, even if the laminar boundary layer of the airflow generated on the face surface during swing is separated at the boundary portion between the face surface and the sole surface, it does not re-appear at the rear of the back surface side. Adhesion may occur and the pressure resistance may be reduced to reduce the air resistance, which may prevent the head speed from being reduced.

[Brief description of drawings]

FIG. 1 is an external view showing an embodiment of a golf wood club head according to the present invention, FIG. 2 is an explanatory view schematically showing the state of lift generated by an air flow during a swing, and FIG. FIG. 4 is an explanatory view showing bar graphs comparing the measurement results of the lift coefficient for each head speed in stages of the prototype of the golf wood club head according to the invention and the other three golf wood club heads. FIG. 5 is an external view of a conventional golf wood club head, and FIG. 5 is an explanatory view schematically showing the state of lift generated by an air flow during conventional swing. 1 ... Head body, 2 ... Face surface, 2a, 2b ... Upper and lower edge corners, 3 ... Crown surface, 4 ... Back surface, 5 ... Sole surface, 6 ... Toe side surface, 7 …… Heel side surface, a, b …… ridgeline of boundary, Rs …… radius of sole surface, F ₀ …… negative lift force, F ₁ …… positive lift force, X …… ball striking direction.

Claims (2)

[Claims] 1. A crown surface formed on the sole surface of the head body into a spherical convex surface having a predetermined radius of curvature rounded in all directions, and other than the ridge line at the boundary with the face surface,
A wood club head for golf in which the ridge lines at the boundaries between the back surface, the sole surface, and the toe / heel side surfaces are eliminated. 2. The golf club head for golf according to claim 1, wherein the radius of curvature of the sole surface of the head main body is set in a range of 0.2 m or more and 0.5 m or less.