JPH0449985A - Racket frame - Google Patents

Abstract

PURPOSE:To reduce pneumatic resistance acting on a frame in a swing for increasing the swing speed by inclining the longitudinal center axis in the sectional shape of the frame to the direction perpendicular to a ball hitting surface to change an angle of the frame. CONSTITUTION:The longitudinal center axis M in the section B of a frame is inclined within a range of 5 deg.-45 deg. to the Z axial direction perpendicular to a ball hitting surface 5. Thus, in swinging a racket, the angle of the frame is allowed to come near the angle of air flow, so that the air flow in the swing is little hindered by the side width of the frame to reduce the turbulence of air flow near the rear side of the frame and improve the swing speed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a racket frame that reduces air resistance exerted on the frame when the racket is swung.

(Prior art) Conventionally, racket frames (hereinafter referred to as frames) have been used.
Usually consists of a ball hitting part, a shaft part, and a grip part. Materials for molding include wood, metal, and fiber-reinforced plastic.

Furthermore, the width of these frames in the direction of ball hitting, that is, the side width, was approximately constant.

However, recently, by bringing the natural frequency of the frame closer to the frequency of the ball, the frame's vibration can be used to accelerate the ball when the ball is hit on the hitting surface. There are rackets with side walls that are partially or entirely wider than conventional rackets, which are called thick-walled rackets.

Furthermore, these rackets are also called mid-size, large-size, etc., and have a ball hitting surface area of about 30
There is a wide range of 80%.

As described above, by increasing the area of the ball hitting surface, the sweet spot can be enlarged, making it easier to hit the ball.

Furthermore, by increasing the side width of the frame in whole or in part, the frequency of the ball and the natural frequency of the racket become closer, thereby improving the repulsion characteristics of the ball. However, on the other hand, by increasing the area of the ball hitting surface and widening the side width of the frame, the drawbacks of increasing air resistance and reducing swing speed were eliminated.

(Problems to be solved by the invention) When hitting a ball with a racket, the frame performs rotational motion, and there are also issues such as the height of a tennis court net, the gravity on the ball, and operations to impart spin to the ball. Yes, the trajectory of the frame has some angle with respect to the ground. However, the air flow relative to the frame during a swing is not always perpendicular to the ball hitting surface.

In other words, the air flow during the swing is at some angle to the central longitudinal axis of the frame cross section. Especially in soft tennis,
This is often the case.

Therefore, during a swing, turbulence occurs in the air flow near the rear side of the side width of the frame in the ball hitting direction, resulting in air resistance.

The larger the side width of the frame, the more likely it is that turbulence will occur in the air flow near the rear of the frame, and the wider the area of the ball hitting surface and the longer the frame, the greater the air resistance. increase

(Means for Solving the Problems) Therefore, the present invention reduces the air resistance that the frame receives during swing by changing the angle of the frame, increases the swing speed, makes it easier to swing, and reduces the movement of the racket relative to the ball. This provides an accelerated frame.

In order to achieve the above object, the present invention has the following configuration.

That is, the racket frame is characterized in that the longitudinal center axis M in the cross-sectional shape of the frame taken in a direction perpendicular to the ball-hitting surface is inclined with respect to the direction perpendicular to the ball-hitting surface.

Preferably, the inclination angle of the central axis M is within the range of 5 degrees to 45 degrees.

Furthermore, as a method of inclining the central axis, a plane perpendicular to the ball hitting surface passing through the central axis Y in the front longitudinal direction of the racket,
The extensions of the central axis M are set to intersect at an angle.

Although the above configuration can be implemented over the entire frame, it is preferably implemented at least on the frame of the ball hitting section.

(Function) When swinging a racket, the airflow is always at an angle to the ball hitting surface. In other words, it can be said that the ball is not swung in a direction perpendicular to the ball-striking surface, but is being swung at an angle to the ball-striking surface.

This is closely related to the air resistance that is applied to the frame when swinging the racket.

In the present invention, by configuring the central axis M in the cross-sectional shape of the frame to be inclined with respect to the axis Z direction perpendicular to the ball-hitting surface in the cross-sectional shape, the angle of the frame is adjusted to reflect the air flow when the racket is swung. The angle was close to that of .

Therefore, when swinging, the air flow is less likely to be obstructed by the side width of the frame, reducing turbulence in the air flow near the rear side of the frame, and improving swing speed.

(Example) An example in which the present invention is implemented in a ball hitting portion that is a part of a frame will be described.

FIG. 1 shows a frame consisting of a ball hitting part 2, a shaft part 3, and a grip part 4.

FIG. 2 is an aS cut end view of the ball-striking part in FIG. Slanted in range.

As shown in the cross-sectional view of FIG. 6, the ball-hitting section of a conventional frame has a ball-hitting surface 5 and a central axis M that are always perpendicular (in the Z direction).When swinging a racket with such a frame, As shown in FIG. 7, the central axis M is inclined with respect to the direction of the air flow X. Therefore, turbulence occurs in the air flow behind the frame. The larger the width, the greater the turbulence and the greater the air resistance.

Therefore, if the extension of the center axis M is configured to pass through the center axis Y in the longitudinal direction of the front of the racket and intersect with a plane perpendicular to the ball hitting surface as shown in FIG. The angle of the central axis M is approximately parallel to the air flow X, and turbulence in the air flow that occurs on the rear side of the frame can be reduced.

A racket with such a configuration is highly effective when there are many forehand strokes.

In addition, a configuration as shown in FIG. 5 can also be used.

In either case, air resistance can be reduced by changing the outer shape of the frame in cross section B to a shape that is less susceptible to air resistance, and by roughening the frame surface.

Note that although the drawings are omitted, the present invention can be implemented in shaft parts and grip parts other than the ball-hitting part.

(Effects) As described above, in the present invention, the central axis wAM in the longitudinal direction in the cross section of the frame cut in the direction perpendicular to the ball-hitting surface,
By changing the angle of inclination with respect to the direction perpendicular to the ball hitting surface as shown in FIG. 3, air resistance during a forehand stroke can be significantly reduced.

Further, by changing the inclination angle of the central axis 11M as shown in FIG. 4, it is possible to reduce the air resistance during the swing in both directions of the forehand stroke and the backhand stroke.

In addition, by roughening the entire surface of the frame made of these structures, or at least the tip portion in the width direction of the side surface of the frame, the rough surface of the leading edge in the direction of movement prevents separation of air flow when the racket frame swings. This reduces turbulence in the air flow near the rear end of the frame.
Air resistance can be further reduced.

Thus, the frame of the present invention increases swing speed,
It is useful because it is easy to swing and the movement of the racket relative to the ball can be accelerated.

[Brief explanation of the drawing]

The drawings show an example in which the present invention is implemented in a ball hitting section. Fig. 1 is a plan view, Fig. 2 is a cutaway end view of the main part of the ball hitting part in Fig. 1, and Figs. 3 to 5 show an extension of the central axis M passing through Y and perpendicular to the ball hitting surface. 6 and 7 are explanatory diagrams of a conventional racket frame. 1: racket frame, 2: ball hitting section, 3: shaft section,
4 Nigelip part, 5: Ball hitting surface, 6: Gut insertion hole, B:
Cross section, M: longitudinal central axis in the cross section of the frame ball-hitting section, X: air flow, Y: longitudinal central axis of the front of the racket, Z: axis perpendicular to the ball-hitting surface. Figure 1 Procedural Amendment July 20, 1990

Claims (1)

[Claims] 1. Center axis M in the longitudinal direction of the cross-sectional shape of the frame
A racket frame characterized in that the frame is inclined with respect to the direction perpendicular to the ball hitting surface. 2. The racket frame according to claim 1, wherein the inclination angle of the central axis M is 5 degrees to 45 degrees. 3. The racket frame according to claim 1 or 2, wherein an extension of the central axis M intersects at an angle with a plane perpendicular to a ball hitting surface passing through the central axis Y in the front longitudinal direction of the racket. 4. The racket frame according to claim 1, 2, or 3, wherein at least a tip portion of the surface of the frame in the side width direction is roughened.