GB2316623A - A racket frame string hole system - Google Patents

Abstract

A sporting racket frame has string mounting holes in the frame head which are shaped so that their diameter in the outboard side is constructed so that the string (plus grommet) is a reasonably tight fit and the diameter on the inboard side is considerably greater so that the string will not touch the edge of the hole in normal use.

Description

Patent Application A Racket Frame Stringing System.

This invention relates especially to a stringing method on a racket frame head used in Tennis, Squash, Badminton or Racquetball but is not limited to such.

It is generally accepted that the introduction of oversize racket frames in all the racket sports has proved to be a large improvement over the traditional size rackets. The larger surface area within which to strike the ball making the game more playable for the novice and recreational player and as a result more rewarding. The degree of precision required in hitting the ball with power and control is reduced in an oversize frame, due mainly to the increased hitting area and in particular the larger centre of percussion or 'sweet-spot'.

Allowing a greater margin of error. Although these oversize frames have been popular in the past, there has been a growing trend to reduce the racket head size to a mid - oversize frame being a more maneuverable racket, yet endeavor to retain the characteristics of the larger oversize frames. It has been a desired feature to have the advantages of the oversize frames string bed reaction area and 'sweetspot' size, but in a racket of smaller proportions.

With this in mind, the present invention seeks to provide a means by which the performance characteristics of an oversize racket frame can can be duplicated in a racket frame of lesser head dimensions and surface area.

The present invention is directed at a racket frame whereby the bending point of the strings is from the outside frame periphery, through the string entry hole and not from the inside frame hole which is the present state of the art.

The strings are laced through holes in the inner and outer frame walls via a plastic grommet strip designed to protect the strings from frictional breakage. The grommets are held in position by interference fit and are normally a snug fit in the outer and inner frame holes. The present invention provides for an outer frame hole through which the grommet passes which is a tight interference fit the inner hole is larger in diameter, normally twice the diameter of the grommet diameter or more as to allow the the grommet and string to pass through the inner hole and move through at least a 30 degree arc in all directions without touching the inner frame wall when the ball is impacted, thus the inner grommet and string float in the centre of the location hole. It has been found that the minimum diameter to achieve the minimum 30 degree movement should be twice the diameter of the grommet outside measurement. ,The effect of this is to effectively increase the bending point of the string on impact from the inside frame on a conventional racket to the outside frame on the present invention giving the effect of a bigger frame and string bed by a least the frame thickness times two.

The increase can be measured at between 10% to 15% string area without actually increasing the frame size.

In a tennis racket for example the increase in effective string area can be upto 15 sq.'s, thus making a normal mid-oversize racket of 100 sq.'s have the same string area as an oversize racket of 110 sq.'s.

Another advantage that has been noted during testing of the present invention that by moving the string bending point to the outside frame, the normal amount of frame impact vibration is decreased. This is due the fact that whereas a normal frame with the grommet strip touching the frame inside wall will transmit the impact vibration from hitting the ball directly into the frame and then down the handle which can cause arm injuries in the player such as tendentious or tennis elbow, the present invention cushions this impact vibration as the string is never in direct contact with the frame, rather there is the plastic grommet strip shrouding the string around the interlaced outer frame holes. In tests, a reduction in vibration of upto 40% can be achieved with the present invention over a conventional racket.

Parts of a racket made in accordance with the present invention are illustrated in the accompanying drawings, in which: Figure 1 shows a inside view of a conventionally strung racket, the frame 2 has holes drilled through 3, through which the grommet 4 passes being a tight frictional fit. The string 5 is then laced through the hole to form the string bed.

Figure 2 shows a section through a racket frame inner and outer walls 2, the holes 3 through which the plastic grommet 4 passes outside to inside, the string 5 is then passes through the centre hollow tube of the grommets 4 to be interlaced in order to form the string bed which is the know present method of the art.

Figure 3 , shows a front view of a typical racket whereby the frame 2, has holes 3 drilled through the outer and inner walls to form the locators for the grommets 4 which pass from the outside to the inside and form the string pattern. 'A' indicates the minimum number of strings on the crosses in which the present invention is used (4 strings), 'B' indicates the minimum number of strings on the vertical strings.

Figure IV shows a side view of a racket frame incorporating the present invention, 2 being the racket frame, the grommets 4 pass through the inside frame holes 3 which is of a greater diameter than the outside diameter of the grommet and do not touch the inside walls. The string 5 is then threaded through the grommet to form the string bed.

Figure V shows a cross-section through the frame 2whereby the grommet 4 passes through the outside frame hole 6 which is a tight interference fit. The inner frame hole is a minimum twice the diameter of the grommet allowing the grommet to move a minimum of 30 degrees in any direction without touching the inside frame wall. 7 shows the extent the grommet can travel without touching the frame inner walls when the strings 5 are at rest and then impacting a ball.

Figure VI shows the racket frame 2 periphery elevation of a conventionally strung frame. The arrowed dimensions 8 show the string length and bending point of the string which is from the inside frame holes.

Figure VII shows a racket frame 2 periphery elevation of a racket the same size as Figure Vl, but the bending point of the strings 8 is from the outside frame holes, thus increasing the effective strung area by a minimum 15% dependent on the frame thickness, over a racket of the same proportions.

Figure VIII shows a cross section of a racket frame 2 of a conventionally strung racket whereby the grommet holes 3 in the inner and outer frame are of the same diameter. The grommet 4 is inserted through the hole and is a tight friction fit with the frame walls. The string 5 is threaded through the grommet from the outside frame 10 inwards and interlaced to form the string bed.

Figure IX shows a similar cross section to Fig.VIII but the inner frame hole for the grommet 3 is of a larger diameter than the grommet outside diameter and does not touch the inside walls of the racket frame.

Numerous further variations and modifications to the illustrated construction will occur to a reader who is skilled in the art without putting the resulting stringing method outside the scope of this invention.

Claims (1)

1. What I claim is:

   1/ A racket frame whereby the strings and or grommets in the inner frame do not touch the inside racket frame at rest or at impact whilst striking a ball.

   2/ A racket frame as in 1 where the inner frame grommet or string hole is a minimum of twice the diameter of the grommet or string.

   3/ A racket as in 1 whereby the string can bend through a minimum of 30 degrees on impact with a ball without touching the inner frame wall.

   4/ A racket frame as in 1 whereby the invention is used for a minimum of 4 long strings and 4 cross strings.