DE8622129U1 - Composite racket frame - Google Patents

Description

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G 86 22 129.9 KUN NAN LO DEAC-34153.7 May 3, 1988

Composite racket frame

The invention relates to a racket frame made of composite material with a closed head carrying a string, with a substantially triangular neck section and with a shaft extending therefrom which has a handle section wherein an intermediate section with a cross section is provided on the shaft between the neck section and the handle section the dimension of which is reduced perpendicular to the plane of the stringing.

From DE-OS 27 23 628 a racket frame made of a fiber-reinforced material is known, in which a section with reduced thickness is provided between a neck part and a handle part, whereby the reduction in thickness can be provided perpendicular to the plane of the stringing or alternatively parallel to it. This alternative reduction in thickness is intended to achieve impact damping. The reduction in thickness is preferably carried out in the neck part, whereby the area of reduced thickness can also continue into the shaft part of the frame. The reduction in thickness is achieved by forming shallow depressions, which can have the shape of elongated grooves, which extend in the longitudinal direction of the frame and almost across the entire width.

With the known racket frame, a certain degree of impact and vibration damping can be achieved, but this comes at the expense of the impact efficiency.

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From GB-PS 482 164 it is also known _to taper the shaft of a racket frame in an intermediate cross-section to its smallest cross-section on all four sides evenly, whereby this taper can also be carried out in a large number of stages*

The object underlying the invention is to design the racket frame of the type mentioned at the beginning in such a way that, in addition to good flexibility and elasticity, a good impact effect can also be achieved.

This task is solved starting from the racket frame of the type mentioned above in that the transition from the cross-section of the shaft to the reduced cross-section of the intermediate section is formed by a section with two gradations.

The gradations of the section can have rounded edges.

With the racket according to the invention, flexibility and elasticity that are gentle on the arm can be achieved with sufficient impact efficiency.

The invention is explained in more detail using drawings. It shows:

Fig. 1 a racket frame made of composite material in side view,

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Fig. 2 the shaft of the racket frame in the side view,

Fig. 3 the shaft of the racket frame in section,

Fig. 4 schematically shows the transmission of vibration forces in the shaft and

Fig. 5 the effect of the racket when hitting a ball=

The racket frame 10 shown in Fig. 1 is made of a molded composite material and consists of a carbon fiber reinforced plastic shell 20 and a foamed core 30. The frame 10 has an oval racket head 11, a triangular neck portion 13 and a shaft 12 with a grip portion 14 provided around the shaft at its end and near the end of the shaft. At an intermediate portion of the shaft 12, which is located below the neck portion 13, the shaft 12 is narrowed to a smallest cross-section with respect to the other shaft parts. The dimension of the cross-section of the smallest cross-section portion 121

section decreases in a direction substantially perpendicular to the plane of the stringing (not shown) that the closed head 11 carries, as can be seen from Fig. 2. The width of the section 121 is thus reduced on two opposite sides of the shaft 12 facing a direction of impact of the ball and in another opposite direction. The width of the shaft 12 in the direction parallel to the stringing plane remains the same over the entire length. From the section 121 with the smallest cross section, two slightly stepped sections 122, increasing in width, extend on both sides to the neck section 13 and to the shaft end up to a certain distance until they are flush with the

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The remaining part of the shaft 12 are »graduated sections 122 have rounded step edges in order to reduce the stress concentration at these points to a minimum.

The dimension of the section 121 with the smallest cross-section is such that a predetermined strength is present. Due to the existing stepped sections 122, the fiber-reinforced

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ouiixujiL. aw luiu ucx «jcauiiouiubc ncui jv uco uunxayci,- frame 10 can be engaged more effectively during molding than in the known racket frames. This engagement of the foamed core 30 and the fiber reinforced layer 20 takes place at the shoulder portions 21 of the stepped portions 122. In addition, due to the portions 121 and 122, the elasticity and the bending characteristics of the shaft are improved, which also increases the shock absorption capacity of the racket frame.

Claims (2)

fl tr» Protection of Claims 1. Racket frame (10) made of composite material with a closed head (11) carrying a string, with a substantially triangular neck section (13) and with a shaft (12) extending therefrom, which has a handle section (14), wherein on the shaft (12) between the base section (13) and the handle section (14) an intermediate section (121) with a cross section is provided, the dimension of which is reduced perpendicular to the plane of the string, characterized in that the transition from the cross section of the shaft (12) to the reduced cross section of the intermediate section (121) is formed by a section (122) with two steps. 2. Racket frame according to claim 1, characterized in that the steps of the section (122) have rounded edges.