GB2114451A

GB2114451A - Racket frame

Info

Publication number: GB2114451A
Application number: GB08202762A
Authority: GB
Inventors: Lo Kun-Nan
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-02-01
Filing date: 1982-02-01
Publication date: 1983-08-24
Also published as: GB2114451B

Abstract

A racket frame including an O-shaped head portion 21 made of an alloy tube is characterized in that the lower portion 23 of the head, within a distance of one third of the vertical axis measured from the lowest point of the periphery of the head portion 21, has a wall thickness greater than that of the other portion 22 of the head, thereby increasing the strength of the frame. <IMAGE>

Description

SPECIFICATION Racket frame This invention relates to a racket frame and particularly to a structure of the racket frame.

In designing a racket frame, beside the consideration of the strength requirement, it is also necessay to keep the weight and size thereof into an appropriate limitation. Especially for a head portion of the frame that holds a web of racket strings which must be subjected to frequent impact caused during strokes of a ball, it is important to match the configuration, size, thickness and strength of the frame into a proper design. If the frame is principally designed for strength and configuration, the head portion of the frame should be considerably thick to achieve a desired condition, and consequently the resulted increase in weight makes the user easily suffer from fatigue. In case the weight, size and configuration of the frame are intended to be important requirements in designing, the frame can not possess a satisfactory strength.Presently, in the hope of obtaining a well selling market, the manufacturers usually stress on the requirement of light weight and configuration rather than the consideration of the strength requirement. Figure 1 shows a head portionn 10 of a racket frame, made of an alloy tube, substantially in O-shaped ring with an appropriate peripheral length. The curved portion beyond one third of the vertical centerline measured from the lowest point of the periphery, is provided with a longitudinal groove 11 along therewith for receiving and guiding the attaching racket strings. The crosssections of the frame taken along the lines Ill-Ill' and ll-ll' of Figure 1 are illustrated in Figures 3 and 2 respectively and the wall thickness Tthereof is about 2mm.The frame itself has a weight of 97.5 g, a longitudinal length of 65cm, and the O-shaped portion 10 has 24.5cm in length (L) along the vertical axis and 19.8cm in width W. Although the weight and configuration thereof give a satisfaction to the user, the strength thereof is found unfavourably low when subjected to a test or during application. After some time of use, it is observed that breakage is generally caused at the curve portion extending laterally from the lowest point of the O-shaped head up to a distance of one third of the vertical axis.

Therefore further improvement is still to be attempted.

A racket frame according to the invention comprises an O-shaped head portion made of an alloy tube, a throat portion and a handle portion, and is characterized in that a lower portion of the head portion within a distance of one third of the vertical axis measured from the lowest point of the periphery of the head has a wall thickness greater than that of other portion of the head portion, thereby increasing the strength of the lower portion and also maintaining an appropriate weight of the frame.

Preferably, the wall thickness of the lower portion is twice that of the other portion.

An object of the invention is to provide a racket frame not only having favourable configuration and weight but also possessing a satisfactory strength.

This and other objects, features and advantages of the present invention will be more apparent in the following description of a preferred embodiment with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a racket frame in the prior art; Figure 2 is a sectional view of the frame taken along the ll-ll' of Figure 1; Figure 3 is a sectional view of the frame taken along the line Ill-Ill' of Figure 1; Figure 4 is a perspective view of a racket frame embodying the present invention; Figure 5 is a view illustrating a difference in wall thickness of the frame in two specific portions; Figure 6 is a sectional view taken along the line VI-VI' of Figure 4; and Figure 7 is a sectional view taken along the line VII-VII' of Figure 4 As shown in Figure 4, a racket frame 20 according to the invention comprises ahead portion 21 which is made of an alloy tube with a thickness of about 2.6mm. The portion 22, beyond a distance of one third the vertical axis of the head 21 measured from the lowest point of the periphery of the head 21, is provided with a longitudinal groove 221. By proper chemical treatments, e.g. immersed in sulfuric acid, the wall thickness of the portion 22 is reduced to about 1 .3mm-1 .5mm. Figure 5 illustrates the wall thickness of the frame greater in the portion 23 and smaller in the portion 22. The wall thickness of the portion 22 is reduced about 1/3 when comparing with that of the conventional one as shown by a dotted line of Figure 6.And the wall thickness of the portion 23 has a thickness about 1/3 greater than that of the conventional one, as shown by the dotted line of Figure 7. As the wall thickness of the portion 23 is increased about 1/3 when comparing with the conventional one the strength thereof is increased and the frame can bear greater torsion and more strokes.

Furthermore, as the wall thickness of the portion 22 is reduced about 1/3 the thickness of the conventional frame the weight of the whole frame can be decreased.

With the invention thus explained, it is apparent that obvious modifications and variations can be made without departing from the scope of the invention. It is therefore intended that the invention be limited only as indicated in the appended claims.

1. A racket frame which has an O-shaped head portion made of an alloy tube, a throat portion and a handle portion, characterized in that a lower portion of said head portion within a distance of one third of the vertical axis measured from the lowest point of the periphery of said head has a wall thickness greater than that of other portion of said head portion, thereby increasing the strength of said portion and also maintaining an appropriate weight of the frame.

2. A racket frame as claimed in Claim 1, wherein the wall thickness oi said lower portion is twice that of said other portion.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Racket frame This invention relates to a racket frame and particularly to a structure of the racket frame. In designing a racket frame, beside the consideration of the strength requirement, it is also necessay to keep the weight and size thereof into an appropriate limitation. Especially for a head portion of the frame that holds a web of racket strings which must be subjected to frequent impact caused during strokes of a ball, it is important to match the configuration, size, thickness and strength of the frame into a proper design. If the frame is principally designed for strength and configuration, the head portion of the frame should be considerably thick to achieve a desired condition, and consequently the resulted increase in weight makes the user easily suffer from fatigue. In case the weight, size and configuration of the frame are intended to be important requirements in designing, the frame can not possess a satisfactory strength.Presently, in the hope of obtaining a well selling market, the manufacturers usually stress on the requirement of light weight and configuration rather than the consideration of the strength requirement. Figure 1 shows a head portionn 10 of a racket frame, made of an alloy tube, substantially in O-shaped ring with an appropriate peripheral length. The curved portion beyond one third of the vertical centerline measured from the lowest point of the periphery, is provided with a longitudinal groove 11 along therewith for receiving and guiding the attaching racket strings. The crosssections of the frame taken along the lines Ill-Ill' and ll-ll' of Figure 1 are illustrated in Figures 3 and 2 respectively and the wall thickness Tthereof is about 2mm.The frame itself has a weight of 97.5 g, a longitudinal length of 65cm, and the O-shaped portion 10 has 24.5cm in length (L) along the vertical axis and 19.8cm in width W. Although the weight and configuration thereof give a satisfaction to the user, the strength thereof is found unfavourably low when subjected to a test or during application. After some time of use, it is observed that breakage is generally caused at the curve portion extending laterally from the lowest point of the O-shaped head up to a distance of one third of the vertical axis. Therefore further improvement is still to be attempted. A racket frame according to the invention comprises an O-shaped head portion made of an alloy tube, a throat portion and a handle portion, and is characterized in that a lower portion of the head portion within a distance of one third of the vertical axis measured from the lowest point of the periphery of the head has a wall thickness greater than that of other portion of the head portion, thereby increasing the strength of the lower portion and also maintaining an appropriate weight of the frame. Preferably, the wall thickness of the lower portion is twice that of the other portion. An object of the invention is to provide a racket frame not only having favourable configuration and weight but also possessing a satisfactory strength. This and other objects, features and advantages of the present invention will be more apparent in the following description of a preferred embodiment with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a racket frame in the prior art; Figure 2 is a sectional view of the frame taken along the ll-ll' of Figure 1; Figure 3 is a sectional view of the frame taken along the line Ill-Ill' of Figure 1; Figure 4 is a perspective view of a racket frame embodying the present invention; Figure 5 is a view illustrating a difference in wall thickness of the frame in two specific portions; Figure 6 is a sectional view taken along the line VI-VI' of Figure 4; and Figure 7 is a sectional view taken along the line VII-VII' of Figure 4 As shown in Figure 4, a racket frame 20 according to the invention comprises ahead portion 21 which is made of an alloy tube with a thickness of about 2.6mm. The portion 22, beyond a distance of one third the vertical axis of the head 21 measured from the lowest point of the periphery of the head 21, is provided with a longitudinal groove 221. By proper chemical treatments, e.g. immersed in sulfuric acid, the wall thickness of the portion 22 is reduced to about 1 .3mm-1 .5mm. Figure 5 illustrates the wall thickness of the frame greater in the portion 23 and smaller in the portion 22. The wall thickness of the portion 22 is reduced about 1/3 when comparing with that of the conventional one as shown by a dotted line of Figure 6.And the wall thickness of the portion 23 has a thickness about 1/3 greater than that of the conventional one, as shown by the dotted line of Figure 7. As the wall thickness of the portion 23 is increased about 1/3 when comparing with the conventional one the strength thereof is increased and the frame can bear greater torsion and more strokes. Furthermore, as the wall thickness of the portion 22 is reduced about 1/3 the thickness of the conventional frame the weight of the whole frame can be decreased. With the invention thus explained, it is apparent that obvious modifications and variations can be made without departing from the scope of the invention. It is therefore intended that the invention be limited only as indicated in the appended claims. CLAIMS

3. A racket frame substantially as hereinbefore described with reference to Figures 4 to 7 of the accompanying drawings.

3. A racket frame substantially as hereinbefore described with reference to the accompanying drawings.

New claims or amendments to claims filed on 28/3/83 Superseded claims 1-3 New or amended claims:-

1. A racket frame comprising an O-shaped head made of alloy tube, a throat and a handle portion, a porttion of the head within a distance of one third of the longitudinal axis measured from the throat being greater in wall thickness than the remainder of the head, said wall thickness being gradually decreased from said portion of the head to the remainder of the head near and at said one-third distance from the throat.

2. A racket frame as claimed in claim 1, wherein the wall thickness of said portion of the head is twice that of the remainder of the head.