JPH0793954B2 - 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 reduces the air resistance due to the laminar flow separation of the laminar boundary layer of the air flow that flows along the ball striking the upper and lower surfaces of the head during swing, and stabilizes the head speed and swing trajectory. This is what was planned.

(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.

However, in such a conventional wood club head, 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 1 is made to have a corner. Since the ridge lines a and b are formed at an acute angle, as shown in FIG. 6, the flow of the air flow generated around the head body 1 during the swing in the ball striking direction X (indicated by the solid line arrow in FIG. 6). (Shown) is greatly disturbed immediately after the upper and lower edge corners 2a and 2b of the face surface 2, causing laminar flow separation in the laminar boundary layer, and the turbulent flow from the laminar flow is induced by the turbulence due to the laminar flow separation. Back to the back surface 4 of the head body 1.
A peeling area is generated on the side, and thereby a pressure difference is generated across the face surface 2 of the head body 1.

By the way, an object placed in a flow receives a force from a fluid. Of these, a component acting in a direction perpendicular to the main stream is usually called a lift force, and a component acting in a direction parallel to the main flow is usually called a drag force. The drag force is divided into a pressure drag force obtained by integrating the pressure distribution acting on the object, that is, the head main body 1, and a friction drag force obtained by integrating the shear stress, and there is no separation of the laminar flow environmental layer. In the flow, the frictional drag is large, and in the flow accompanied by separation, the pressure drag is large.

In particular, the pressure drag generated by the pressure difference as described above is
Due to the negative pressure action of the separation area formed behind the separation point of the laminar boundary layer, the head speed during swing is reduced,
It is known that not only reduces the flight distance of the ball but also causes the swing trajectory to become unstable.

Therefore, as disclosed in Japanese Patent Publication No. 53-31417, a groove called a trip step is formed at the upper edge corner of the face surface of the head body, or in Japanese Patent Laid-Open No. 62-
As disclosed in Japanese Patent No. 176469, by forming a large number of fine grooves in the shape of a shark skin over almost the entire crown surface and sole surface of the head body, a turbulent boundary layer is generated on the head surface during swinging. Some are configured to do so.

(Problems to be Solved by the Invention) However, according to the configuration of the wood club head according to the invention described in the above-mentioned conventional publication, a boundary layer of an air flow is generated by generating a turbulent boundary layer on the head surface during swinging. Although the peeling area of the head is delayed to reduce the pressure resistance, a groove called a trip step is simply formed at the upper edge corner of the face surface of the head main body, or the head main body It is impossible to achieve the intended action and effect only by forming a large number of fine grooves in the shape of a shark skin over almost the entire surface of the crown surface and the sole surface and applying the surface treatment.

That is, as shown in FIG. 6, the conventional wood club head has the upper and lower edge corners of the face surface 2 of the head body 1.
Since the ridgelines a and b are formed at an acute angle with an angle at the boundary portion between the crown surface 3 and the sole surface 5 that are connected to 2a and 2b, the so-called "inherently delimited area is determined" in fluid mechanics. In addition, the laminar flow separation of the laminar boundary layer has already occurred immediately after the upper and lower end edge corners 2a and 2b of the head body face surface 2, so that the desired turbulent boundary layer is formed around the head. There was a problem that was not done.

The present invention has been made under the above circumstances, and its purpose is to reattach the laminar boundary layer of the airflow generated on the head face surface during swinging around the head after laminar flow separation. Another object of the present invention is to provide a wood club head for golf in which it is possible to prevent the re-peel by promoting it to near the rear of the head bag surface side.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides a head body having a crown surface and a sole surface each having a spherical shape with a predetermined curvature radius rounded in all directions. Convex surfaces are formed to have almost the same shape and are almost symmetrical in the vertical direction, and the boundaries between the crown surface, the back surface, the sole surface, and the toe / heel side surfaces except for the ridgeline at the boundary with the face surface In addition to eliminating the ridgeline of the portion, the depth dimension of the head body in the ball striking direction is made the same as the lateral width dimension of the face surface.

In this case, the radii of curvature of the crown surface and the sole surface of the head body are preferably set to a range of 0.2 m or more and 0.5 m or less.

Further, by setting the radius of curvature of the ridge portion at that time to 5 mm or less, the effect of preventing separation of the air flow, which is the effect of the present invention, can be obtained, and when it exceeds 5 mm, separation of the air flow easily occurs. .

Further, it is desirable that the depth dimension L of the head body in the ball striking direction is the same as the width dimension W of the face surface within 8 mm, preferably within 5 mm, but the depth dimension L is 90 mm of the width dimension W.
Even if it fluctuates to%, the effect of the present invention occurs.

(Operation) That is, according to the present invention, the crown surface and the sole surface of the head main body are formed in substantially the same shape as the spherical convex surface having a predetermined radius of curvature rounded in all directions and are formed substantially symmetrically in the vertical direction. The head face at the time of swinging because the other ridge lines of the crown surface, the back surface, the sole surface, and the side surface of the toe / heel side other than the ridge line of the boundary portion with the surface are eliminated. If the laminar boundary layer of the air flow generated on the surface is separated laminarly at the ridges of the boundary between the crown surface and the sole surface at both the upper and lower corner edges of the head face surface, then the head behind the back surface side Re-adhesion to the surroundings, and this re-adhesion state is promoted to near the rear on both sides of the headback to prevent re-peeling, so that the pressure resistance can be reduced.

[Examples] The present invention will be described below with reference to the examples shown in Figs. 1 to 4. In the illustrated embodiment according to the present invention, portions having the same structures as those of the conventional structure shown in FIGS. 5 and 6 will be described using the same reference numerals.

As shown in FIG. 1 to FIG. 3, the head main body 1 of the golf wood club according to the present invention has a crown surface 3 and a sole surface 5 as spherical convex surfaces having a predetermined radius of curvature R rounded in all directions. The crown surface 3, the back surface 4, the sole surface 5, and the toe / heel side surface, which are formed in substantially the same shape and are substantially symmetrical in the vertical direction, except the ridgelines a and b at the boundary with the face surface 2. It has a configuration in which the ridge lines at the boundary portions between 6 and 7 are smoothed and eliminated.

Thus, according to the above-described structure of the golf wood club head according to the present invention, the crown surface 3 of the head body 1 is
And the sole surface 5 is rounded in all directions 0.2 m or more,
Since the spherical convex surface having a radius of curvature R of 5 m or less is formed to have substantially the same shape and substantially symmetrically with respect to each other, as shown in FIG. 3, the laminar flow of the air flow generated on the face surface 2 during swinging. The boundary layers are the upper and lower end portions 2a of the face surface 2,
2b, a ridgeline a at the boundary between the crown surface 3 and the sole surface 5,
Even if they are once peeled off on both sides of b, they are attached again on the back side of the back surface 4. Moreover, the ridge line a at the boundary of the face surface 2,
Except for b, the crown surface 3, the back surface 4, the sole surface 5, and the toe / heel side surface 6, 7 are provided with no ridge lines at the boundary portions thereof, and the entire surface exhibits an oval smooth curved surface. Since it is formed as described above, it becomes possible to delay the reattached laminar boundary layer as close as possible to the rear end of the back surface 4.

Further, the crown surface 3 and the sole surface 5 of the head body 1
The radius of curvature Rc, Rs of the spherical convex surface that forms
If it is 2 m or more and 0.5 m or less [0.2 m <(Rc, Rs) <0.5 m], it is preferable to set it, and if it is 0.2 m or less, the reattached laminar boundary layer is delayed to near the rear end of the back surface 4. If the thickness is 0.5 m or more, it is impossible to reattach the laminar boundary layer as in the conventional structure.

FIG. 4 shows a wood club head (a) according to the present invention and a plurality of types (e.g., eight types) of known conventional wood club heads (b) (c) (d) shown in the table below.
(E) (g) (h) (i) (j) drag coefficient of the (Cd); Cd = F / [(1/2) · v 2 · ρ · A] However, F: 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 during swing, and each bar graph was compared and displayed.
In the figure, the diagonal line on the upper right is 30 m / sec, and the dotted line is 40 m / s.
ec, the diagonal line to the upper left indicates the case of 50 m / sec, and as is clear from this result, the wood club head (a) of the present invention has a higher drag force than other conventionally known ones (b) to (n). It was found that the coefficient was the smallest.

[Effects of the Invention] As is apparent from the above description, according to the present invention, the crown surface and the sole surface of the head body are formed into substantially the same shape as a spherical convex surface having a predetermined curvature radius rounded in all directions. Form almost symmetrically in the vertical direction, and eliminate the ridgelines at the boundary between the crown surface, the back surface, the sole surface and the toe / heel side side surface, except for the ridgeline at the boundary with the face surface. Therefore, the laminar boundary layer of the air flow generated on the head face surface during swinging is separated once at the ridgeline of the boundary between the crown surface and the sole surface at the upper and lower corner edges of the head face surface. Can then be redeposited around the back head on both sides of the back.

Moreover, since the ridgelines at the boundary between the crown surface, the back surface, the sole surface, and the toe / heel side side surface other than the ridgeline at the boundary with the head face surface are eliminated, the laminar flow boundary is eliminated. Since the redeposition state of the layer can be promoted to near the rear of the head back surface side to prevent re-peeling, it is possible to reduce the pressure drag force, thereby reducing the air resistance as much as possible, It is possible to prevent a decrease in head speed and stabilize the swing trajectory.

[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 showing the relationship between the head depth dimension and the face surface lateral width dimension in a plane, and FIG. Similarly, an explanatory view schematically showing a laminar flow separation state and a reattachment state of the laminar boundary layer of the air flow during swinging. FIG. 4 is a prototype of a golf wood club head according to the present invention and a conventional golf wood. FIG. 5 is an explanatory view showing a bar graph comparing the stepwise measurement results of the drag coefficient with the club head for each head speed, FIG. 5 is an external view of a conventional golf club head for gorevs, and FIG. 6 is the same during conventional swing. FIG. 6 is an explanatory view schematically showing a laminar flow separation state of a laminar boundary layer of an air flow in FIG. 1 ... Head main 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 ... boundary line ridge, Rs ... sole surface radius of curvature, Rc ... crown surface radius of curvature, X ... ball striking direction.

Claims (2)

[Claims] 1. A crown surface and a sole surface of a head main body,
It is formed as a spherical convex surface with a predetermined radius of curvature that is rounded in all directions, and has almost the same shape and is substantially symmetrical in the vertical direction, and other crown surfaces, back surfaces, sole surfaces other than the ridgeline at the boundary with the face surface, A wood club head for golf, in which a ridgeline at the boundary between the toe and heel side side surfaces is eliminated, and the depth dimension of the head body in the ball striking direction is substantially the same as the lateral width dimension of the face surface. 2. The wood club head for golf according to claim 1, wherein the radius of curvature of the crown surface and the sole surface of the head body is set in a range of 0.2 m or more and 0.5 m or less.