JP2009136527A - Racket with hitting central position matched with position of node of two-node bending vibration - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a hitting point with no impact and no vibration and prevent adverse effect on the human body by matching a hitting central position with a node position of two-node bending vibration in the string face or a racket where the hitting central position is not matched with the node position of a two-node bending vibration and either an impact or a vibration is generated in hitting, thereby producing uncomfortable ball hitting feeling by the impact and vibration and affecting the adverse effect on the body. <P>SOLUTION: A specific amount of weight is disposed at a grip end lower end portion or a racket head tip potion to move the hitting central position and the node position of the two-node bending vibration on the string face of the racket and match them at the same position, thus achieving the hitting point without impact or without vibration. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a racket having a string surface that is axisymmetric with respect to an axis line connecting the tip end portion of the racket head and the lower end portion of the grip end, and the center of an impactless hit at different positions on the axis line of the string surface. This is a racket that moves the position of the vibration-free two-node bending vibration node to match the same location on the axis and achieves a shock-free vibration-free striking point. A racket is a tennis racket or soft tennis. A racket, a bound tennis racket, a squash racket, a badminton racket, or any other racket having a string surface. It should be noted that the weighting material and the weight or weight, the position of the impact center and the non-impact position, the position of the two-node bending vibration node and the non-vibrating position are used interchangeably.

As for rackets, especially tennis rackets, in order to produce rackets that have been easy to swing, the weight of the racket body and balance adjustment (weight distribution) for moving the center of gravity of the racket are applied. No. is known. There has also been a proposal to reduce or reduce (attenuate) impact vibration at the time of hitting a ball to reduce discomfort such as a load on the body or numbness. For example, Japanese Patent No. 2853926 and Japanese Patent Laid-Open No. 4-263876 are known to have taken this kind of means for the grip end. Here, it has been proposed to load load (weight) as a vibrator through an impact vibration absorbing member.

Under these circumstances, the present inventor provided a balance adjustment weight necessary for solving the above-mentioned problem in Japanese Patent Application No. 2000-65171, moved the center of gravity position from the grip portion, and performed a snap operation around the wrist joint. A “balance adjustment weight in a ball striking tool” has been proposed that can improve the characteristics of the ball striking tool by easily increasing the head speed and absorbing the impact impact.

Also, when overviewing balance adjusting means (including stabilizers) mainly for damping or absorbing shock vibration, Japanese Patent Application Laid-Open No. 5-177003 proposes to change the vibration mode by attaching a weight to the racket tip, There is also a type in which a vibration damping material is provided in the middle part of the frame shaft. In the above conventional example, the balance adjustment (weight distribution) enables the movement of the center position of the hit on the string surface of the racket and the two-node bending vibration. There is no description about the movement of the position of the section.

Furthermore, in recent years, lightweight top heavy balance has become mainstream in tennis rackets, and in view of the fact that the position of the node on the grip at the time of hitting is far from 90 mm to 180 mm from the lower end of the grip end, the present inventor No. 3826313 proposed a grip end bottom weight and a grip end bottom weight structure, described the movement of the node on the grip by the bottom weight, and standardized the two-node bending vibration node on the grip when hitting the ball. It has been proposed that the feel at impact is improved by moving to a grip fulcrum (70 mm from the grip end), which is the gripping part, and gripping the position of a no-vibration node.

Here, there is a common point in the part where the weighted weight is provided at the lower end of the grip end and the position of the node of the two-node bending vibration is proposed, but the body can be obtained by grasping the node of the two-node bending vibration on the grip. The proposal is to avoid the vibration propagating to the string surface. With respect to the striking point on the string surface, the center position of the striking and the position of the node of the two-node bending vibration are not moved, and no impact or vibration is generated when the ball is hit. No proposals have been made for the realization of impactless vibration strike points. In order to deal with the problem of not generating shock or vibration when hitting the ball, the proposal of moving the knot on the grip cannot be dealt with, and the problem cannot be solved without focusing on the striking point on the string surface of the racket. So there was room for modification.

The present invention has been made in view of such circumstances, and in a racket having a string surface that is axially symmetric with respect to an axis connecting the racket head tip and the grip end lower end, the racket head tip or grip By placing a specific weight on the lower end of the end, the position of the center of the impactless striking and the position of the no-vibration 2-node bending vibration node at different positions on the axis of the string surface is moved, It matches with the same place on the line and realizes impactless and vibration-free striking point.
In addition, when the position of the center of the impactless hit and the position of the center of the hitless vibration are considered to indicate the approximate characteristic area, the center point of the approximate characteristic area is considered as the position. .

There are two types of impacts that humans feel: “impact” and “vibration”.
The impact force at the time of hitting is transmitted to the hand as an impact reaction force. In addition, the vibration generated in the frame shaft varies from a higher order mode to a lower order mode, but due to the influence of friction, the higher order mode attenuates faster. In particular, a representative vibration that is considered to be the cause of the occurrence of a disorder such as tendonitis or tennis elbow in the human body or that has the greatest influence on an unpleasant feel at impact is a two-node bending vibration that is referred to as a fundamental vibration inherent to the frame shaft.

The present invention pays attention to the two-node bending vibration and considers the node as a vibration-free hitting point. It is known that there are two-node bending vibration nodes on the string surface of the racket, and when the ball is hit at the position of this node, the two-node bending vibration hardly appears on the frame shaft. In addition, there is a hitting center on the string surface of the racket, and hitting the ball at the hitting center position cancels the translational and rotational movements of the grip part, the displacement is 0, the impact is also 0, and the hand is impacted. Is known not to occur.

The center of hitting on the string surface of the racket is the hitting point at which the translation and rotation of the grip portion are canceled and the displacement becomes zero. The two-node bending vibration node is a phenomenon that appears in the continuous reciprocation of the frame shaft. Thus, the position of the center of the impact and the position of the node of the two-node bending vibration are completely different. If the position of the hitting center and the position of the node of the two-node bending vibration coincide with the same place on the string surface of the racket, the hitting point has no impact and no vibration.
However, in the verification of the existing tennis racket, the position of the hitting center and the position of the node of the two-node bending vibration are not in the same place on the string surface of the racket, and a distance of 15 mm to 63 mm is confirmed depending on the model. As a result, it is not preferable that the vibration is generated even when there is no impact when hit at the center of the impact, or the impact occurs even when there is no vibration when hit at the position of the node of the 2-node bending vibration. It is in a state. At the same time, the vibration of the frame shaft results in energy loss, the coefficient of restitution decreases, and causes a decrease in repulsive force.

The position of the center of hitting on the string surface of the racket where the hand does not feel an impact varies depending on whether the grip is long or short.
The present invention considers the position of the center of hitting on the string surface of the racket corresponding to the grip fulcrum 70 mm from the lower end of the grip end, which is said to be a standard gripping place.
Actual Kaihei 7-028578 Japanese Patent No. 2853926 JP-A-4-263876 Japanese Patent Laid-Open No. 5-177013 Japanese Patent Application No. 2000-65171 Japanese Patent No. 3826313

The present invention produces an unpleasant shot feeling due to impact and vibration at the time of hitting the ball, and at the same time, is propagated from the hitting point through the frame shaft portion to the human body and transmitted to the human body, and the body is adversely affected by tendonitis or tennis elbow. And the occurrence of vibration of the frame shaft causes loss of energy, resulting in a decrease in the coefficient of restitution and a cause of a decrease in the repulsive force. The center position of the hit on the axis connecting the two and the position of the node of the two-node bending vibration are moved to match on the axis, realizing a hitting point where neither impact nor vibration occurs, and the human body with a comfortable shot feeling The aim is to develop and provide a ball hitting tool that is safe and repulsive.

According to a first aspect of the present invention, when a weight material made of a high specific gravity material is embedded inside and outside the grip end component including the end cap at the lower end of the grip end, the string surface of the racket is embedded, enclosed, joined or combined. Above, the position of the center of the non-impact hitting located closer to the grip end than the position of the node of the two-node bending vibration moves toward the tip of the racket head. At the same time, the position of the no-vibration two-node bending vibration node located closer to the racket head tip than the center of the impact moves in the grip end direction. In this way, by using the physical characteristics approaching each other and arranging a specific weight, the center position of the hit and the two-node bend on the axis connecting the tip of the racket head and the bottom end of the grip end The position of the vibration node is moved to coincide with the same place on the axis, and the impact point with no impact and no vibration is realized.

According to a second aspect of the present invention, there is provided a racket string in which a weighting material made of a high specific gravity material is embedded inside and outside a racket head tip constituent material including a grommet at the tip of the racket head, and is embedded, enclosed, joined or combined. On the surface, the position of the center of impactless impact moves toward the tip of the racket head. At the same time, the position of the no-vibration two-node bending vibration node is also moved toward the racket head tip.
At that time, since the moving speed of the center position of the hit existing near the grip is faster than the moving speed of the position of the two-node bending vibration node near the tip of the racket head, the two-node bending vibration node position is reached. By using the physical property that the center position of the hitting is approaching and arranging a specific weight, the center position of the hitting is on the axis connecting the tip of the racket head and the lower end of the grip end. The position of the node of the two-node bending vibration is moved so as to coincide with the same place on the axis, thereby realizing an impact-free vibration-free striking point.

3rd invention is the tennis racket which realized the impact point without impact and vibration by making the position of the center of the hit and the position of the node of the two-node bending vibration coincide on the axis line connecting the racket tip and the grip end lower end. In the straight line group extending at right angles to the axis connecting the racket head tip and the grip end lower end, the portion formed by the straight line passing through the impact-free vibration-free striking point is the most on the string surface of the racket. It is a racket characterized by the frame shape of the string surface which is large or lengthy.
The striking point with no impact and no vibration is located at the longest string part both vertically and horizontally, so that a strong repulsive force of the string can be obtained. At the same time, since the frame part of the string surface formed by the straight line passing through the impactless and vibration-free striking point has the maximum width or length, it can be rotated around the axis connecting the racket head tip and the grip end bottom. The moment of inertia to resist increases, and the stability of the string surface of the racket can be improved. Further, in order to increase the moment of inertia, a weighting material is disposed on the frame portion constituting the string surface having the maximum width or length.

On the string surface of the tennis racket, the position of the center of impactless striking and the position of the no-vibration two-node bending vibration node on the axis connecting the racket tip and the grip end lower end are based on the verification of the existing racket. Although there is a difference depending on the model, a gap of about 15 mm to 63 mm has been confirmed.
Since the position of the center of the impactless hit and the position of the no-vibration 2-node bending vibration node are separated from each other, the ball is hit at the center of the hit and there is no impact, but vibration is generated. The ball is hit at the node position of the two-node bending vibration, and there is no vibration, but an impact is generated.
In the present invention, by placing a specific weight on the inside or outside of the racket head tip or the grip end lower end, an impact on the string surface of the racket on the axis connecting the racket head tip and the grip end lower end can be obtained. The center position and the position of the node of the two-node bending vibration are moved to coincide with the same place on the axis, thereby realizing an impact-free vibration-free striking point.

It is possible to provide a safer racket by preventing a tenonitis and tennis elbow due to impact and vibration transmitted to the human body as well as obtaining a comfortable shot feeling when hitting at a hit point with no impact and no vibration it can. Further, if the hitting point is no impact and no vibration, the frame shaft vibration is suppressed and the generation of energy loss is also suppressed, so that the coefficient of restitution is improved and the repulsive force of the racket is also improved.

Furthermore, when considering the shape of the string surface of the tennis racket that achieves an impact-free vibration-free striking point, the string is among the straight lines extending perpendicular to the axis connecting the racket head tip and the grip end bottom. If the frame that forms the surface is configured so that the straight line that passes through the impact-free vibration-free striking point has the maximum width on the string surface, the shock-free vibration-free striking point is both vertical and horizontal. Because it is located at the longest string part, it can acquire strong repulsive force of the string.
At the same time, since the frame part of the string surface formed by the straight line passing through the impactless and vibration-free striking point has the maximum width or length, it can be rotated around the axis connecting the racket head tip and the grip end bottom. The moment of inertia to resist increases, and the stability of the string surface of the racket can be improved. Further, in order to increase the moment of inertia, it is preferable to place a weighting material on the frame portion having the maximum width or length.

In order to describe the present invention in more detail, it will be described below with reference to the accompanying drawings.
FIG. 1 shows a standard tennis racket.
In the figure, node position 1 of 2-bend bending vibration, position 3 of hitting center, frame shaft 5, grip part 6, grip fulcrum 7 (70 mm from grip end lower end 8 at standard grip position), grip end lower end 8, a racket head tip 9, a racket string surface 10, and an axis 11 connecting the racket head tip 9 and the grip end lower end 8. The position 1 of the node of the two-node bending vibration and the position 3 of the hitting center are on the axis 11 connecting the racket head tip 9 and the grip end lower end 8.
The position 1 of the node of the two-node bending vibration and the position 3 of the hitting center are located at different locations on the string surface 10 of the racket.

FIG. 2 shows a tennis racket in which the weight member 4 is arranged at the grip end lower end portion 8. In the figure, the position 1 of the node of the two-node bending vibration, the position 2 of the impact point where there is no impact and no vibration, the position 3 of the center of the impact, the weighting material 4, the frame shaft 5, the grip portion 6, the grip fulcrum 7, the lower end of the grip end 8, a racket head tip 9, a racket string surface 10, and an axis 11 connecting the racket head tip 9 and the grip end lower end 8. The node position 1 of the two-node bending vibration, the position 2 of the impact point without impact and vibration, and the position 3 of the center of the impact are on the axis 11 connecting the racket head tip 9 and the grip end lower end 8. The weight member 4 is disposed on the inner and outer portions of the grip end lower end portion 8 that is partitioned by a straight line perpendicular to the axis connecting the racket head front end portion 9 and the grip end lower end portion 8. By attaching the weight member 4 to the grip end lower end portion 8, the node position 1 of the two-node bending vibration moves in the direction of the grip end lower end portion 8. At the same time, the center position 3 of the impact moves in the direction of the racket head tip 9. As a result, the node position 1 of the two-node bending vibration and the position 3 of the hitting center are close to each other and coincide with each other at the hitting point 2 where there is no impact and no vibration when a specific weight is placed. When a ball is hit at the position 2 of the impact point where there is no impact and no vibration, no impact is generated in the hand and almost no two-node bending vibration is generated in the frame shaft 5.
If neither impact nor vibration occurs, not only a comfortable shot feeling is realized, but also adverse effects such as tendonitis on the body and tennis elbow due to the impact vibration are improved. Moreover, by suppressing the vibration of the frame shaft 5, energy loss is suppressed, the coefficient of restitution is improved, and the repulsive force is also improved.

FIG. 3 shows a tennis racket in which the weight member 4 is arranged at the tip 9 of the racket head. In the figure, the position 1 of the node of the two-node bending vibration, the position 2 of the impact point where there is no impact and no vibration, the position 3 of the center of the impact, the weighting material 4, the frame shaft 5, the grip portion 6, the grip fulcrum 7, the lower end of the grip end A portion 8, a racket head tip 9, a string surface 10, and an axis 11 connecting the racket head tip 9 and the grip end lower end 8.
The node position 1 of the two-node bending vibration, the position 2 of the impact point without impact and vibration, and the position 3 of the center of the impact are on the axis 11 connecting the racket head tip 9 and the grip end lower end 8. The weight member 4 is disposed at the inner and outer portions of the racket head tip portion 9 that is partitioned by a straight line perpendicular to the axis connecting the racket head tip portion 9 and the grip end lower end portion 8. By attaching the weighting material 4 to the racket head tip 9, the node position 1 of the two-node bending vibration moves in the direction of the racket head tip 9.
At the same time, the center position 3 of the impact moves in the direction of the head tip 9. At this time, the moving speed at the position 3 at the center of the impact is faster than the moving speed at the position 1 of the node of the two-node bending vibration. Is the impact point position 2 where there is no impact and no vibration. When a ball is hit at the position 2 of the impact point where there is no impact and no vibration, no impact is generated in the hand and almost no two-node bending vibration is generated in the frame shaft 5.
If neither impact nor vibration occurs, not only a comfortable shot feeling is realized, but also adverse effects such as tendonitis on the body and tennis elbow due to the impact vibration are improved. Moreover, by suppressing the vibration of the frame shaft 5, energy loss is suppressed, the coefficient of restitution is improved, and the repulsive force is also improved.

Verify based on experimental facts.
FIG. 4 (a) shows a front view of a position 1 and a position 3 at the center of the impact of the two-node bending vibration of the super decalake-conventional balance racket. (B) shows the amplitude of the racket vibration viewed from the side. This racket is a model called super decal, and the area of the string surface 10 is 120 square inches, the weight is 349 g (including the string), and the center of gravity is 323 mm from the lower end 8 of the grip end. The white / black boundary line shown in (a) is the position of the “node” of the two-node bending vibration, and the position is changed near the frame and the center of the string surface 10.
In (b), the portion where the amplitudes intersect is a “node”, and the portion away from the node is called an antinode, and the amplitude of the frame shaft 5 increases.

When measured on the string surface 10 of the racket, the position of the node of the two-node bending vibration near the frame is 575 mm from the lower end portion 8 of the grip end. The position 1 of the joint of the two-node bending vibration on the axis 11 connecting the racket head tip 9 and the grip end lower end 8 is 534 mm from the grip end lower end 8, and the center 3 of the hit is the grip end lower end. 8 to 504 mm (see FIG. 6). When comparing the position 1 of the node of the two-node bending vibration and the position 3 of the center of the hit, the distance is 30 mm apart.

FIG. 5 is a view of the position of the node of the two-node bending vibration and the position of the center of hitting of the ultra-decaraquet-ultra-light top heavy balance racket as viewed from the front.
Although the area of the string surface 10 is the same as that of the above-mentioned ultra-decaraquet-conventional balance racket, the weight is reduced to 292 g (including string), the center of gravity is 363 mm from the grip end lower end 8, and the racket head end 9 is The top heavy balance has been moved. When measuring on the string surface 10 of the racket, the position of the node of the two-node bending vibration near the frame is 582 mm from the lower end portion 8 of the grip end. The position 1 of the node of the two-node bending vibration on the axis 11 connecting the racket head tip 9 and the grip end lower end 8 is 541 mm. The center position 3 of the hit is 526 mm from the lower end 8 of the grip end (see FIG. 6). When comparing the position 1 of the node of the two-node bending vibration and the position 3 of the center of the impact, the distance is 15 mm apart.
<Quoted from racket science published in the January 1994 issue of the monthly tennis journal>

FIG. 6 shows the position 3 of the hitting center where the hand does not feel an impact and the grip position of the grip corresponding to the six types of rackets. The center position 3 of the hit on the string surface 10 of the racket changes corresponding to the grip position of the grip. Among them, experimental data are verified by taking up three types: (a) super-dekarake-conventional balance racket, (b) super-dekarake-superlight top heavy balance racket, and (c) normal-conventional balance racket. Note that “normal” means a racket having a standard string surface size, which is 93 square inches, a weight of 360 g (including a string), and a center of gravity position of 308 mm (a distance from the grip end lower end portion 8). Since the standard grip position is the grip fulcrum 7 of 70 mm from the lower end 8 of the grip end, the position 3 of the hitting center corresponding to the grip fulcrum 7 will be considered.

(A) Super dekarake-In the conventional balance racket, the hitting center position 3 corresponding to the grip fulcrum 7 is 504 mm from the grip end lower end 8.
(B) In the ultra-decaraking-ultra-light top heavy balance racket, the hitting center position 3 corresponding to the grip fulcrum 7 is 526 mm from the grip end lower end 8.
(C) In the normal-conventional balance racket, the center position 3 corresponding to the grip fulcrum 7 is 460 mm from the lower end 8 of the grip end.
<Quoted from the science of racket published in the monthly issue of the tennis journal 1993-December>

FIG. 7 shows how the center position 3 of the batting corresponding to the grip fulcrum 7 moves when the weight 4 is installed on the (c) normal-conventional balance racket.
When a weight 4 of 30 g is attached to the grip end lower end 8, the hitting center position 3 moves in the direction of the 40 mm racket head tip 9 as compared to the case without the weight 4.
When a 30 g weight 4 is attached to the racket head tip 9, the hitting center position 3 moves in the direction of the 50 mm racket head tip 9 as compared to the case without the weight 4.
In this way, the position 3 at the center of the impact moves in the direction of the racket head tip 9 regardless of whether the racket head tip 9 is weighted or the grip end lower end 8 is weighted.

When the weight 4 of 30 g is attached to the grip end lower end portion 8 described above, the hitting center position 3 is moved by 40 mm, and therefore the moving distance of the hitting center position 3 for each weight of 1 g is 40 (mm). ÷ 30 (g) = 1.3 (mm) <rounded to the second decimal place, the same shall apply hereinafter>, and moves at a rate of 1.3 mm. When the weight 4 of 30 g is attached to the tip 9 of the racket head, the hitting center moves 50 mm, so the moving distance of the hitting center position 3 for each weight of 1 g is 50 (mm) ÷ 30 (g) = 1.7 (mm), and it is moving at a rate of 1.7 mm.
<Quoted from the science of racket published in the monthly issue of the tennis journal 1991-November>

FIG. 8 shows the movement of the node position 1 of the two-node bending vibration when the weight 4 is attached to the (c) normal-conventional balance racket.
(A) is a front view, and the black and white boundary line indicates the position 1 of the node of the two-node bending vibration. (B) is a horizontal view showing the shape of the amplitude and the position 1 of the node of the two-node bending vibration.
Comparing the case where the weight 4 of 30 g is attached to the tip 9 of the racket head and the case where the weight 4 is not provided, as shown in (b), the two-node bending vibration node near the frame on the string surface 10 of the racket is shown. The position has moved from a position of 0.80 × L (full length) of L (full length) = 680 mm to a position of 0.84 × L (full length).
Since the moving distance is 0.04 × L (full length = 680 mm) of L (full length), the movement distance is 27 mm.

When the weight 4 is not provided, the position 1 of the two-node bending vibration node on the axis 11 connecting the racket head tip 9 and the grip end lower end 8 is measured to be 523 mm from the grip end lower end 8, and the racket head tip When a 30 g weight 4 is attached to 9, the position 1 of the node of the two-node bending vibration is 550 mm, which is similarly moved 27 mm.

When the weight 4 of 30 g is attached, the position 1 of the node of the two-node bending vibration has moved 27 mm, so the moving distance per weight 1 g is 27 (mm) ÷ 30 (g) = 0.9 (mm). , Moving at a rate of 0.9 mm.
The position of the node of the two-node bending vibration moves in the direction of the racket head tip 9 when it is applied to the racket head tip 9, and moves in the direction of the grip end bottom 8 if it is applied to the grip end bottom 8 so that the grip end When the lower end 8 is weighted, it is considered that the weight moves at a rate of 0.9 mm for every 1 g of weight.
<Quoted from the science of racket published in the monthly issue of the tennis journal 1991-November>

In this way, when considering the physical characteristics of the moving direction and moving speed of the center position 3 of the impact and the position 1 of the 2-node bending vibration node, on the axis connecting the racket head tip 9 and the grip end bottom 8 In order to move the position 3 of the hitting center on the axis and the position 1 of the two-node bending vibration node so as to coincide with each other on the axis and realize the hitting point 2 with no impact and no vibration, the weight 4 is gripped. It can be seen that there are a method of arranging at the end lower end portion 8 and a method of arranging at the end portion 9 of the racket head.

As shown in FIG. 2, in the method of attaching the weight 4 to the lower end portion 8 of the grip end of the racket, according to the above formula, the position 1 of the node of the 2-node bending vibration is a ratio of 0.9 mm per 1 g load. To move toward the grip end lower end 8. At the same time, the center position 3 of the impact moves in the direction of the opposite racket head tip 9 at a rate of 1.3 mm per 1 g load. In this case, they approach each other, and 0.9 (mm) +1.3 (mm) = 2.2 (mm) per 1 g load, and both approach at a rate of 2.2 mm.

As shown in FIG. 3, in the method of attaching the weight 4 to the tip 9 of the racket head, according to the above formula, the position 1 of the node of the two-node bending vibration is the racket at a rate of 0.9 mm per 1 g load. It moves in the head tip 9 direction. At the same time, the center position 3 of the hit also moves in the same direction toward the racket head tip 9 at a rate of 1.7 mm per 1 g load. Since the center 3 of the hit is near the grip end lower end 8, it becomes 1.7 (mm) −0.9 (mm) = 0.8 (mm) per 1 g load, and follows at a rate of 0.8 mm. It will approach.

A shock vibration accelerometer is attached to the grip fulcrum 7 of the tennis racket, and when the impact point on the racket string surface 10 is examined with an impulse hammer, the position 3 of the impactless hitting center and the position of the no-vibration 2-node bending vibration node One place can be measured.

Further, when the position 3 at the center of impactless hitting is roughly checked by an easy method, the grip fulcrum 7 of the tennis racket is perpendicular to the grip 6 and parallel to the string surface 10 of the racket. A string is tied, the string is stretched and fixed to the left and right, and the racket head tip 9 is suspended downward. Measure the striking point at which the translational and rotational movements of the grip fulcrum 7 are canceled and the displacement is zero, and the string stretched on the left and right does not move when it is moved in order on the string surface 10 of the racket suspended from the string. Can do. The hit point is the center position 3 of the hit.

When checking the position 1 of the no-vibration two-node bending vibration node, the grip portion 6 is lightly gripped, and the sound quality is confirmed by hitting the string surface 10 of the racket in order while keeping the grip portion 6 close to the ear. When two-node bending vibration is occurring, the sound quality is low because it is a low-order mode vibration. No two-bend bending vibration is generated even if a two-node bending vibration node is struck, so there is a two-node bending vibration node at the highest sound quality.

Considering the identification of the weight to realize the impact point 2 without impact and vibration, suppose that the distance between the center position 3 of the hit on the string surface 10 of the racket and the position 1 of the node 1 of the two-node bending vibration is 20 mm. If it is found that they are separated from each other, if the above-described weighting method for the grip end lower end portion 8 is selected, it approaches 2.2 mm per 1 g weighting, so 20 (mm) ÷ 2.2 (mm) = 9 When the weight 4 of 9.1 g is mounted, the center position 3 of the hit and the position 1 of the node of the two-node bending vibration coincide with each other at the hit point 2 where there is no impact and no vibration.

Further, when the weighting method for the racket head tip 9 is selected, it approaches by 0.8 mm per 1 g weighting, so 20 (mm) ÷ 0.8 (mm) = 25 (g), and the weight 4 of 25 g When the is attached, the position 3 of the center of the hit and the position 1 of the node of the two-node bending vibration coincide with each other at the position of the impact point 2 where there is no impact and no vibration.

If the weight 4 is attached to the racket head tip portion 9, the top heavy balance is achieved. If attached to the grip end lower end portion 8, the top light balance is obtained.
An object of the present invention is to realize a non-impact and vibration-free striking point 2 by moving the position 3 of the impact-free hit center and the vibration-free two-node bending vibration node 1 to coincide with each other.
The balance of the racket is a preference of the user, and which method should be selected within a practical range should be selected according to the play style and preference.

In the super decalake-conventional balance racket of FIG. 4, as described above, the center position 3 of the hit on the string surface 10 of the racket and the position 1 of the node of the two-node bending vibration are separated by 30 mm. In order to realize the impact point 2 with no vibration and no impact by weighting the part 8, 30 (mm) ÷ 2.2 (mm) = 13.6 (g), and if a weight 4 of 13.6 g is attached, Good.

On the contrary, in order to realize the impact point 2 with no impact and no vibration by applying weight to the tip 9 of the racket head, 30 (mm) ÷ 0.8 (mm) = 37.5 (g). A weight 4 may be attached. However, practically, it is predicted that attaching 37.5 g to the racket head tip 9 will make the racket operability considerably difficult. In this case, the weighting method to the grip end lower end 8 is Think appropriate.

As shown in FIG. 5, the super decalake-lightweight top heavy balance racket in FIG. 5 is gripped because the position 3 of the hitting center on the string surface 10 of the racket and the position 1 of the 2-node bending vibration node are 15 mm apart. In order to realize the impact point 2 with no vibration and no impact by applying weight to the lower end 8 of the end, 15 (mm) ÷ 2.2 (mm) = 6.8 (g), and a weight 4 of 6.8 g is mounted. do it. On the contrary, in order to realize the impact point 2 with no impact and no vibration by applying weight to the tip 9 of the racket head, 15 (mm) ÷ 0.8 (mm) = 18.8 (g), and 18.8 g A weight 4 may be attached.

In the normal-conventional balance racket of FIG. 6, the center position 3 of the hit is 460 mm from the lower end 8 of the grip end.
As described above with reference to FIG. 8, the position 1 of the two-node bending vibration is 523 mm from the lower end portion 8 of the grip end. 523 (mm) -460 (mm) = 63 (mm), which is 63 mm apart.

In order to realize the impact point 2 with no vibration and no impact by applying weight to the lower end 8 of the grip end, 63 (mm) ÷ 2.2 (mm) = 28.6 (g). Just install it. On the other hand, in order to load the racket head tip 9 and achieve the impact-free vibration hitting point 2, 63 (mm) ÷ 0.8 (mm) = 78.8 (g), and 78.8 g A weight 4 may be attached.
Also in this case, since it is predicted that it is practically difficult to attach the 78.8 g weight 4 to the tip 9 of the racket, the operability of the racket is expected to be extremely difficult. Is appropriate.

In the present invention, a specific amount of weight 4 is arranged inside or outside the racket head tip 9 or the grip end lower end 8, and on the axis connecting the racket head tip 9 and the grip end lower end 8, the string surface 10 of the racket. It has been proposed that the position 3 of the upper hitting center and the position 1 of the two-node bending vibration node are moved so as to coincide with each other on the axis to realize the position of the impact point 2 with no impact and no vibration. In order to effectively move the position 3 of the center of impact and the position 1 of the node of the two-node bending vibration, it is preferable to concentrate the weight on the inside and outside of the racket head tip 9 or the grip end bottom 8.
In addition, it is preferable to use a high specific gravity material having a specific gravity of 7 or more for the weight material (weight) 4 in order to prevent intensive load and increase in volume of the weighted portion.
The weight member (weight) 4 is disposed in a region within a range delimited by a straight line perpendicular to the axis connecting the racket head tip 9 and the grip end lower end 8, and the weight of the racket head tip 9 or the grip end lower end 8 is It arrange | positions in the site | part of the range within 20 mm within the inside and outside, Preferably it is within 10 mm.

In addition, the standard grip position is the grip fulcrum 7 which is 70 mm from the lower end 8 of the grip end, but there are preferences such as the size of the user's hand and the grip 6 being held short or long. Therefore, the position of the grip fulcrum 7 is appropriately set to a position in the range of 50 mm to 90 mm from the lower end portion 8 of the grip end, preferably in the range of 60 mm to 80 mm. Of course, it is conceivable that the grip fulcrum 7 is assumed to be other than 70 mm from the grip end lower end 8 but it is included that the center position 3 of the hitting corresponding to the string surface 10 of the racket changes depending on the assumed position. In addition, it is necessary to specify the weight to realize the impact point 2 that is shockless and vibration free.

The effects and merits of realizing the position of the impact point 2 without impact and vibration on the string surface 10 of the racket have already been described. Next, a frame shape constituting the string surface 10 of the racket for more effectively utilizing the position of the impact point 2 without impact and vibration will be considered.

The impact-free vibrationless striking point 2 realized on the racket string surface 10 shown in FIG. 9 is on the axis 11 connecting the racket head tip 9 and the grip end lower end 8. There are two places where the straight line 12 that passes through the impact-free vibration-free striking point 2 and is perpendicular to the axis 11 intersects the frame 13 constituting the string surface 10 of the racket 14 and 15.

When considering another group of straight lines constituting the string surface 10 of the racket parallel to the straight line 12 perpendicular to the axis 11, the frame portions 14 and 15 on the straight line 12 passing through the impact-free vibration-free striking point 2. The distance is preferably a shape having a maximum width or length as compared with other parts constituting the string surface 10 of the racket.
As a result, the impact-free vibration-free striking point 2 uses the longest part of the string surface 10 of the racket for both the vertically stretched string and the horizontally stretched string. You can gain rebound.

Further, in this racket shape, the distance between the frame portions 14 and 15 on the straight line 12 passing through the impact point 2 without impact and vibration is the maximum width or length in the string surface 10 of the racket. The moment of inertia resisting rotation about the axis 11 connecting the portion 9 and the grip end lower end portion 8 is also increased, and the stability of the hitting surface is improved.

Furthermore, when the above-described moment of inertia is increased for the purpose of surface stability, the weight member 4 is disposed in the frame portions 14 and 15.
When a person actually hits the ball, considering the fact that there is an error range of the hitting point on the string surface 10, the weight 4 is arranged so that the straight line 12 passing through the hit point 2, which has no impact and no vibration, passes the string surface. Centering on the part 14 or 15 that intersects the frame 13 to be formed, 50 mm in the direction of the racket head tip 9 and 50 mm in the direction of the grip end lower end 8, inside and outside of the frame component including the grommet of the frame part within 100 mm in total length The weight material 4 made of a high specific gravity material is preferably incorporated, embedded, enclosed, joined, or combined.

As described above, according to the present invention, based on the data measured in advance by the impulse hammer and the impact vibration accelerometer in the racket design / manufacturing process, a specific amount of the component material of the racket head tip 9 or the grip end lower end 8 is obtained. The weight member 4 is arranged, and on the axis connecting the racket head tip 9 and the grip end lower end 8, the position 3 of the center of the impactless impact and the position 1 of the node of the vibrationless two-node bending vibration are moved, It is possible to realize the impact point 2 that is matched on the axis 11 and has no impact and no vibration.
At the same time, in the frame 13 constituting the string surface 10 of the racket, positions 3 and 2 of the hitting centers in the straight line group extending at right angles to the axis 11 connecting the racket head tip 9 and the grip end lower end 8. By making the portion of the straight line 12 passing through the impact-free vibration-free striking point 2 where the node positions 1 of the node bending vibrations coincide with each other into a frame shape having the maximum width or length on the string surface 10, there is no effect. The impact-free striking point 2 is located at the longest string part both vertically and horizontally, and a strong repulsive force of the string can be acquired. Further, in this racket shape, the distance between the frame portions 14 and 15 on the straight line 12 passing through the impact point 2 without impact and vibration is the maximum width or length in the string surface 10 of the racket. The moment of inertia that resists rotation about the axis 11 connecting the portion 9 and the grip end lower end portion 8 is also increased, preventing surface blurring and improving the stability of the hitting surface.
In this way, it is possible to provide a racket that provides a comfortable feel at the time of hitting, is free of impact vibration, is safe to the body, and has good repulsive force and surface stability.

For the existing racket, measure the distance between the center position 3 of the hitting on the string surface 10 of the racket and the position 1 of the nodal position of the two-node bending vibration, and tune up to the racket realizing the impact point 2 with no impact and no vibration. Can do.
The measurement method is best to use an impulse hammer and an impact vibration accelerometer. However, as a simple but rough method, the grip fulcrum 7 is made by hitting the string surface 10 of the racket and changing the sound quality or hanging the racket. As described above, there is a method for examining the displacement of the above.

As described above, the physical characteristics of the position 3 of the hitting center and the position 1 of the node of the two-node bending vibration moving in a specific direction by the weighting effect on the racket head tip 9 or the grip end lower end 8 are tested as described above. Has been verified. According to the user's preference of the racket, if the top heavy balance is preferred, the racket head tip 9 is weighted, and if the top light balance is preferred, there is no impact by adjusting the weight on the lower end 8 of the grip end. A vibration-free hitting point 2 can be realized.

In the existing racket tune-up, when specifying the weight to achieve the impact point 2 without impact and vibration, depending on the racket model, the thickness of the frame shaft 5 and the hardness of the material can be considered. It is desirable to make fine adjustment so that the position 3 of the center of impact and the position 1 of the node of the two-node bending vibration coincide with each other while checking with an impulse hammer and an impact vibration accelerometer.

Racket users are concerned about the occurrence of injury such as tendonitis and tennis elbow due to the accumulation of shock and vibration over the years. A striking point 2 with no impact and no vibration is realized on the string surface 10 of the racket. By adopting the frame shape of the string surface 10 that can effectively utilize the impact point 2 without impact and no vibration, a comfortable shot feeling and repulsion are achieved. The power can be improved and a safe racket can be provided to the human body.

FIG. 3 is an explanatory view showing a configuration of a standard tennis racket. These are explanatory drawings which show the tennis racket which installed the weight in the grip end lower end part. FIG. 3 is an explanatory view showing a tennis racket in which a weight is installed at the tip of the racket head. Figure 2 shows the position of the node of the two-node bending vibration and the position of the center of the impact of the super dekarake-conventional balance racket (a) Front view, and shows the amplitude shape and the position of the node (b) Side view . Is an explanatory view of the front view of the position of the node of the two-node bending vibration and the position of the center of hitting of the ultra-decaraque-ultra-light top heavy balance racket. Is an explanatory diagram of the position of the center of hitting on the string surface and grip fulcrum on the 6 types of rackets where the hand does not feel an impact. FIG. 4 is an explanatory view of the movement of the center of the hit and the grip fulcrum when a weight is attached. (A) Front view showing movement of node position of two-node bending vibration when weight is attached. (B) Explanatory drawing of lateral view showing amplitude shape and node position. FIG. 3 is an explanatory view showing the best racket shape at a hit point with no impact and no vibration.

Explanation of symbols

1 Position of node of 2-node bending vibration 2 Position of impact point without impact and vibration 3 Position of center of impact 4 Weight material or weight 5 Frame shaft 6 Grip part 7 Grip fulcrum 8 Grip end lower end part 9 Racket head tip part 10 String surface of racket 11 Axis line connecting tip of racket head and lower end of grip end 12 Straight line perpendicular to axis connecting tip of racket head and lower end of grip end 13 Frame constituting string surface of racket 14 Racket head end and grip A straight line perpendicular to the axis connecting the lower end of the end passes through the impact-free vibration-free striking point and intersects the frame that forms the racket surface. 15 Right-angled to the axis connecting the tip of the racket head and the lower end of the grip end. The straight line passes through the impact-free vibration-free striking point and intersects the frame that forms the racket surface. Rumo one site of

Claims (4)

In a racket having a string surface that is axially symmetric with respect to the axis connecting the tip of the racket head and the lower end of the grip end, a weighting material is incorporated inside and outside the grip end component including the end cap at the lower end of the grip end. By placing a specific weight on the string surface, it is possible to move the position of the center of the striking and the position of the node of the two-node bending vibration on the axis of the string surface by placing a specific weight. A racket characterized by matching to the place of.
In a racket having a string surface that is axially symmetric with respect to the axis connecting the racket head tip and the grip end lower end, a weighting material is incorporated inside and outside the head tip component including the grommet at the racket head tip. By placing a specific weight on the string surface, it is possible to move the position of the center of the striking and the position of the node of the two-node bending vibration on the axis of the string surface by placing a specific weight. A racket characterized by matching to the place of. In the frame that forms the string surface of the racket, the position of the center of striking and the position of the node of the two-node bending vibration are the same in a group of straight lines extending perpendicular to the axis connecting the tip of the racket head and the lower end of the grip end. The racket according to any one of claims 1 and 2, characterized in that a portion of a straight line passing through the place formed has a frame shape having a maximum width or length on the string surface. In the frame constituting the string surface of the racket, the weight material is embedded, embedded, enclosed, joined, or combined inside and outside the frame component material including the grommet of the portion having the maximum width or length. The racket according to claim 3, wherein the racket is characterized.

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