JPS6122992B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a racket mainly used for tennis, especially a racket made of fiber reinforced plastics (hereinafter referred to as
This invention relates to an improvement of a racket equipped with a frame having an outer shell strength member structure made of FRP (abbreviated as "FRP").

As is well known, a racket has guts extending vertically and horizontally over almost the entire ball hitting surface of the frame. Therefore, the left and right shoulders on the leading end side and the shaft side of the frame have a gut tension structure in which the guts stretched in the vertical direction and the guts stretched in the horizontal direction are inserted into the same gut insertion hole. The diameter of the gut insertion hole through which the guts in both directions are inserted overlapping each other is increased in diameter.
For this reason, the stringing part of the frame where such thick string insertion holes are installed is more difficult to string than the part where the string insertion holes are installed, where the strings stretched in the vertical and horizontal directions are inserted independently. It is structurally weak and may break if subjected to severe impact, and the shoulder of the gut insertion hole that contacts the gut protection groove provided on the outer peripheral side of the gut insertion hole. Since the two guts overlap, if the tensile strength of the structural part is insufficient to support the tension of the gut in both the vertical and horizontal directions, the gut will dig into the outer circumferential surface of the frame in that part, causing the shoulder area around the opening to cave in. Problems such as not being able to properly hold the string and also causing the stringed part of the frame to partially break and break may occur. In particular, such problems are likely to occur with frames made of FRP outer shell strength member structures.

Furthermore, as mentioned above, since the guts are inserted into the same gut insertion hole from both the vertical and horizontal directions, there is a drawback that the overlapping guts are likely to be cut due to friction.

In addition, in rackets with a larger frame stringing section and a wider ball-hitting surface, the strings are stretched over almost the entire surface of the ball-striking surface, vertically and horizontally. Air resistance is large, which puts an extra burden on the player.In order to reduce the weight of the frame and air resistance, we have taken measures such as reducing the frame structure dimensions, especially the thickness of the outer shell material, and making the outer shell material slender. As a result, it is necessary to avoid concentration of load on local parts of the frame as much as possible.

Therefore, this invention solves the above-mentioned problems, has excellent strength, does not cause breakage of the frame, loosening of the struts, or breaking of the struts, has little air resistance due to the strung struts, and has a light, sharp drying effect. It is an object of the present invention to provide a racket that can be used for rackets, and for this purpose, the present invention has a frame having an outer shell strength member structure made of fiber-reinforced plastics, and a large number of gut insertion holes are formed in the stringing part of the frame in the circumferential direction. In a racket that is opened side by side in a line, the string insertion holes are arranged in a region of a group of holes preferably used for inserting vertical strings and a region of a group of holes preferably used for inserting horizontal strings. These two areas are separated from each other without overlapping each other, and gut protection grooves are recessed in the outer peripheral side of each area so as not to be continuous with other areas. The gist is that the gut insertion hole is provided only in the gut protection groove.

Next, the present invention will be explained in detail with reference to illustrated embodiments.

Frame 1 in the illustrated embodiment is GFRP
(glass fiber reinforced plastics) or CFRP
(carbon fiber reinforced plastics) with a rectangular or trapezoidal cross-section outer shell, preferably
The total width dimension is 210mm or more and the total length dimension is 300mm or more. The stringing part 11 of the frame 1 is provided with a number of string insertion holes, which are the same as those of the conventional structure, but these string insertion holes are preferably vertical string insertion holes through which only the strings 2 stretched in the vertical direction are inserted. It is provided in a state where it is divided into horizontal string insertion holes 3a, through which only the strings 3 extending laterally to the holes 2a are inserted.

The group opening area of each of these gut insertion holes 2a and 3a is located at both left and right shoulders 12 at the tip of the stringing section 11.
A, 12B and both left and right shoulders 14 on the shaft 13 side
These regions do not overlap with each other and are spaced apart from each other at a distance of five times, preferably three times or more, the distance between adjacent gut insertion holes in the region.

In the area where the string insertion holes 2a and 3a groups are provided, string protection grooves 4 each having a concave cross section are independently formed to prevent the string from coming into direct contact with the court surface and being damaged. , the strut protection grooves do not have an adverse effect on the strength of the frame in the parts where the struts are not stretched.

The distribution of the gut insertion holes 2a, 3a in the area where the aforementioned gut insertion hole group is installed is such that the number of guts 2 extending in the vertical direction is within 18 and the number of guts extending in the horizontal direction is within 20. Preferably, the effects of the present invention can be effectively obtained even if the individual gut insertion holes are installed at equal intervals, but for guts installed in the vertical direction, the narrowest part in the center of the group of gut insertion holes is approximately 11 mm. The pitch is approximately 14 mm at the widest point at both left and right ends, while for the horizontally installed gutts 3, the narrowest pitch is approximately 11 mm at the center of the gut insertion hole group 3a, and the widest at both the upper and lower ends. It is even more desirable to have a width of about 16 mm. Note that the above values are not necessarily limited, and various values can be adopted depending on the frame structure.

As mentioned above, if a structure is adopted in which the gut insertion holes in each gut insertion hole group are installed at irregular intervals, the guts 2 stretched in the vertical direction and the guts 3 stretched in the horizontal direction are arranged as shown in the figure. They cross tightly in the center of the ball-hitting surface, and as they move up and down, left and right, they cross in a relatively rough manner, and the sweet spot is tightly stretched, resulting in a large surface rigidity of the ball-hitting surface. This improves the batting speed, and increases the contact area between the ball and the gut during the spin-applied batting motion to impart rotational force to the ball when hitting the ball, making it extremely easy to apply spin, and also to increase the speed of the gut. The influence of bias is reduced, and the uniformity of surface rigidity results in the effect of enlarging the sweet spot.

In the above description, the present invention has been explained with respect to a tennis racket, but it should be understood that the invention can be widely applied to rackets for racquetball, squash, badminton, and the like.

As described above, according to the present invention, the string insertion holes provided in the stringing part of the frame are provided with a group of string insertion holes for strings stretched in the vertical direction, and a string insertion hole group for strings stretched in the horizontal direction. The hole group is divided into two regions, and these two regions do not overlap with each other, but are spaced apart from each other, so a large-diameter gut insertion hole for passing two guts stretched in both the vertical and horizontal directions is provided. There is no need to install a gutt, and along with this, there is no need to form a gutt protection groove in that part, and the large diameter gutt insertion hole and gutt protection groove, which were a factor in reducing the strength of the stringed part of the frame, no longer exist. It is possible to dramatically improve the strength and durability of the stringed part without changing the weight of the frame, without taking reinforcement measures that increase weight, such as adding structural reinforcement members to the frame. Since the guts are inserted into the gut insertion holes independently and separately, there is no tearing of the guts caused by overlapping or rubbing, and there is less stress on the shoulder openings of the gutting insertion holes. Deformation, partial destruction or breakage due to this will not occur, and the gut is stretched only at key points on the ball-hitting surface, preventing an increase in air resistance caused by stretching almost the entire surface, reducing the burden on the player, A racket with excellent durability and ball-hitting performance can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a tennis racket showing an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of the main part taken along the line shown in FIG. 1. 1...Frame, 11...String section, 12A, 1
2B...Shoulder of stringing section, 13...Shaft, 14
A, 14B... Shoulder of shaft, 2... Gut extended in the longitudinal direction, 2a... Gut insertion hole, 3... Gut extended in the horizontal direction, 3a... Gut insertion hole.

Claims (1)

[Scope of Claims] 1. In a racket in which a large number of stringing holes are provided in the stringing part of a frame having an outer shell strength member structure made of fiber-reinforced plastics, the stringing holes are arranged in a region of a group of vertical stringing holes. , and the horizontal gut insertion hole group area, and these two areas are separated from each other without giving importance to each other, and guts are provided only on the outer peripheral side of the frame in each area where the gut insertion holes are opened. A tennis racket characterized by a recessed protective groove. 2. Claim 1, characterized in that the opening positions of the gut insertion holes are such that the interval between the stretched guts is the narrowest at the center of the ball-hitting surface and widest at the ends of the ball-hitting surface. The tennis racket described.