CN87213828U

CN87213828U - Tennis racket

Info

Publication number: CN87213828U
Application number: CN198787213828U
Authority: CN
Inventors: 马克·L·卡拉塞克
Original assignee: Wilson Sporting Goods Co
Current assignee: Wilson Sporting Goods Co
Priority date: 1987-08-04
Filing date: 1987-09-29
Publication date: 1988-08-24
Also published as: FI874269L; ZA878042B; ES2008281A6; KR890003419A; KR910009207B1; EP0317711A2; JP2507397Y2; AU608254B2; ATE83163T1; AU8012587A; CA1318696C; JPS6437967A; DK169163B1; IN170468B; GB2208356B; DE3876605T2; EP0317711A3; FI874269A0; EP0317711B1; ES2037158T3

Abstract

The utility model relates to a tennis racket, and adjusts the rigidity of the tennis racket to make a first bending vibration mode of a bad racket range from 170 hertz to 250 hertz under the constraint condition of free-free. A better condition is that the first bending vibration mode ranges from 200 hertz to 210 hertz. A second bending mode ranges from 215 hertz to 315 hertz under the constraint condition of fixation to free, and a better condition is that the second bending mode ranges from 230 hertz to 265 hertz.

Description

Tennis racket

The present invention is about the racket that moves altogether with a chou with finite elasticity generally speaking, for example, and tennis racket.

In traditional tennis racket, the rigidity of frame and handle portion is such, when a ball impacts on the face that is stretched by line, forces a frame portion to leave the longitudinal axis of bat, and this distortion influences the flight path of rebound conversely.

Any object adds the vibration that all will produce some complexity behind the load.This complex deformation of object can be simplified as the superposition with the countless single vibration modes that change amplitude and change frequency.The particular frequencies relevant with vibrating body, pattern and amplitude depend on and many factors.Rigidity and distribution of weight that interior of articles is wherein promptly arranged have the degree that is tied of object again.Rigidity and distribution of weight can be controlled with two kinds of methods.A kind of method is to use special reinforcement material on some part of object, and these materials have greater strength weight ratio and stiffness/weight ratio.The method of another kind of control rigidity and distribution of weight is the geometry that changes the object cross section, says so with having more and uses the material of fixed qty in the cross section, changes the regional moment of inertia in cross section simultaneously, has so just changed the ratio of rigidity and weight.Improve rigidity and just improved vibration frequency, but reduced the dynamic deformation amplitude simultaneously.The growth of weight has reduced vibration frequency and dynamic deformation amplitude.

Be interested in two kinds of special constraintss are discussed at this.A kind of extreme case is a freedom-free constraints, shows as an object and vibrates in the space unfetteredly.This can be in laboratory be suspended on object the space with elastic webbing and lets alone free vibration and is similar to realization.Under freedom-free constraints the diaphragm shape of a crooked Dan Shu preceding two kinds can be referring to Figure 10.

Another extreme case is fixing-free constraints, and with this understanding, an end of object tightly is fixed on the supporting fixed device, and the other end can free vibration.First three diaphragm shape of first three kind crooked Dan Shu under fixing-free constraints can be referring to Figure 11.It should be noted that 1 among Figure 10 and 2 respectively with Figure 11 in mould 2 and 3 similar shapes is arranged.The additional rigidity of curved object under freedom-free condition is located the excitation (pattern 1 among Figure 11) that will produce an additional low-frequency vibration mould.

Frequency (pattern 2 and 3, the difference respectively) of the relevant pattern under pattern 1 under the freedom-free constraints and 2 frequency and " fixing-freedom " constraints.The frequency of a mould shape under a kind of therein constraints can be by the approximate frequency that obtains the mould shape under another kind of constraints of following relationship formula.

Freqcf=Freqff * (Lff/Lcf) ²(formula 1)

Lcf＝Lff－Lcc

Herein

The frequency of Freqcf=pattern under " fixing-freedom " condition

Freqff=is in the frequency of " freedom-freedom " condition counterdie shape

The bundle of Lff=under " freedom-freedom " condition is long

The bundle that Lcc=is fixed on the anchor clamps is long

The equivalent bundle of Lcf under " fixing-freedom " condition is long

Because ball and bat percussion in the motion, the vibration characteristics that tennis racket showed is similar with the vibration characteristic of relevant Dan Shu described above.In laboratory, various rackets are all done overtesting.Result of the test shows that under " freedom-freedom " constraints for traditional tennis racket, first kind of beam mode is 100 hertz to 170 hertz scopes.Under " fixing-freedom " constraints, the frequency range of the one the second beam modes of traditional racket is respectively at 25 to 50 hertz and 125 to 210 hertz.Be to state that the resonant frequency of racket under " fixing-freedom " constraints is 70 to 200 hertz in 4,664,380 the U.S. patent documents (German publication number is OE-OS3434898) in the patent No..

Result of study shows, in the vibration of tennis racket under " freedom-freedom " condition than the vibration of the racket under " fixing-freedom " condition more similar in appearance to the vibration of at the volley tennis racket.If there is " fixing-freedom " constraints in the test, formula 1 just must be used for revising frequency values, makes second beam mode under " fixing-freedom " condition similar to the first mode frequency value under " freedom-freedom " condition.

The collision time scope of known traditional tennis and racket is at 2 to 7 milliseconds, 2 to 3 milliseconds of average out to.During this period of time, the strength from spheroid makes racket stem deflection backward.In traditional tennis racket, spheroid is that racket begins distortion at ball and racket rum point, has just arrived to racket and has left the bat line sometime between the maximum distortion point.As a result, the flight path of ball is affected (seeing Figure 12), and energy incur loss, because at this moment racket does not also return to deformation-free original shape.In original shape, the bounce angle of racket is 0, and racket stem speed is maximum.

If ball still rests on the ball line and does not leave during the racket deflection, return to deformation-free original state up to racket, then the flight path of ball is unaffected, and can improve the accuracy of shooting.In addition, the at this moment residing seat of racket makes the racket stem reach maximal rate, so it is just bigger to send the strength of ball to, produces more strong shooting.The deformation time that changes tennis is not the desired solution of dealing with problems.Therefore, design the time make the racket that causes at the volley the principal oscillation mould frequency and be complementary the time of contact of tennis and racket, racket just can reach best user mode.Furtherly, tennis racket should equate with the time of staying that tennis is being clapped on the line in the half period of first beam mode under " freedom-freedom " constraints.Why select first beam mode under " freedom-freedom " constraints, because it is the principal oscillation pattern that evokes in the motion.

Since the collision time of tennis and racket is generally 2 to 3 milliseconds, best tennis racket just should have at first beam mode under " freedom-freedom " constraints between 170 to 250 hertz.Consider 27 English inch rackets that held up by a rigid support at handle 3 English inch places, use formula 1, the frequency range of second beam mode will be at 215 to 315 hertz under " fixing-freedom " condition.A special concrete racket example, the frequency range of first beam mode is 200 to 210 hertz under " freedom-freedom " constraints, the frequency range of second beam mode is 230 to 265 hertz under " fixing-freedom " condition.

Illustrated embodiment below in conjunction with shown in the accompanying drawing makes an explanation to the present invention:

The tennis racket plane that Fig. 1 is according to the present invention to be done.

Fig. 2 is the side diagrammatic sketch of racket among Fig. 1.

Fig. 3 is provided with the racket frame plane of clapping line and handle covering.

Fig. 4 is a frame side diagrammatic sketch among Fig. 3.

Fig. 5 is the sectional view of getting along Fig. 3 center line 5-5.

Fig. 6 is the sectional view of getting along Fig. 3 center line 6-6.

Fig. 7 is the sectional view of getting along Fig. 3 center line 7-7.

Fig. 8 is the sectional view of getting along Fig. 3 center line 8-8.

Fig. 9 is a frame fragmentary, perspective view, has shown the multilayer graphite fibre.

Figure 10 is the first and second beam mode figure of tennis racket under " freedom-freedom " constraints.

Figure 11 is first, second and the 3rd beam mode figure of tennis racket under " fixing-freedom " constraints.

Figure 12 has shown that the racket after conventional tennis clashes into returns when rebounding the deformation situation of original traditional tennis racket.

Figure 13 has shown when conventional tennis bump back and has returned when rebounding from racket, adopts the deformation situation of tennis racket of the present invention.

As previously mentioned, the rigidity of adjusting racket is the Perfected process of dealing with problems, and it can make racket after being subjected to conventional tennis bump, and ball recovers undeformed original state before leaving and clapping line.Under this condition, the flight path of tennis is with unaffected before and after ball and the racket bump, and the accuracy of shooting also will be improved, and see accompanying drawing 13.And then, return marble and obtain bigger energy, produce more strong fire effect.

Adjust the rigidity of racket and wish, so that make racket that first pattern in the bending under " freedom-freedom " constraints between 170 to 250 hertz be arranged.Such racket will have second pattern in the bending under " fixing-freedom " constraints between 215 to 315 hertz.Fig. 1-9 shows a specific embodiments of the tennis racket 15 of this frequency.

See figures.1.and.2, racket 15 comprises a frame frame 17, and frame 17 has 18, one throats 19 of a handle portion and a stem 20.Throat 19 comprises that a pair of

parts

21 and 22,21 separate from handle portion 18 with 22, and 20 places close up in stem.A yoke 23 extends between

throat

21 and 22, form to clap first bottom, and its shape generally ringwise or oval.

Racket also comprises many vertical bat lines 24 and laterally

claps line

25,24 and 25 traditional ducts of stretching in stem 20 and the yoke portion 23.Plastics backplate 26 extends on racket stem top, to prevent to clap first wearing and tearing.Backplate is firstly fixed by clapping line clapping, and it is used for preventing to clap the friction between line and the frame duct simultaneously.Plastic spacer 27 extends between the end of backplate 26 and throat 19.Clap first bat line in order to protection than lower part.

Racket also comprises the end cap 29 of a traditional handle covering 28 and handle portion 18.The handle covering can be formed by the leather band that spirality is twined.

Fig. 3 and Fig. 4 show the frame 17 of not clapping line and handle covering.

With reference to Fig. 5 to 8, each part 18～23 of frame all is to be made of the tubular frame parts, and its wall thickness is greatly about 0,045 to 0.050 English inch.The tubular frame parts are formed by being entangled in resin-cast graphite (graphite) fibrage on the inflatable bladder, and the people who understands technology knows that after frame was put mould into, air bag was filled gas, forces the graphite fibre layer to withstand mould, up to hardening of resin.

Fig. 9 shows resin-cast graphite fibre layer 31～42, and it is used for constituting tubular frame parts in the preferred embodiment.31～42 every layer all comprise the one-way graphite fibre, determine its direction by the

section hachure.Layer

31,32 and 35～42 comprises the graphite fibre with about 33,000,000 elastic

modelling quantity.Layer

33 and 34 comprises the graphite fibre with about 45,000,000 elastic modelling quantity.Be used in the graphite fibre on the frame, nearly percent 10 to 20 have bigger elastic modelling quantity, and nearly percent 80 to 90 have less elastic modelling quantity.Use the rigidity that under the situation that does not increase frame weight, just can increase racket than the graphite fibre of big modulus.The skin 43 of frame is an enamelled coating, sees Fig. 9.

Get back to Fig. 3～6, be provided with a groove 45, be provided with line hole 46 in the groove at the superficies of clapping head.45 whiles of groove are as the lay down location (see figure 2) of backplate 25 and plastic spacer 26.

According to Fig. 4, can determine the height of frame, and the perpendicular racket size of midplane MP of measuring and passing the longitudinal centre line CL of handle portion 18.The longitudinal axis of racket in the longitudinal centre line CL pie graph 3.Clap line and be positioned on the midplane MP, the bending of the racket among Figure 10 and 11 occurs in the plane perpendicular to midplane.The thickness of frame increases continuously to frame throat dimension B from frame stem tip size A among Fig. 4.The size C of the thickness of frame end of 18 from size B to handle reduces continuously.The thickness of handle portion increases from size C to yardstick D, and handle bottom then remains unchanged.

The maximum ga(u)ge B of frame appears at

throat

21 and 22 and the zone converged of stem 20.Contrast Fig. 3 and Fig. 4, full-size B is general relative with the center of yoke 23, and yoke intersects with longitudinal centre line CL herein.The thickness of contrast Fig. 6 and Fig. 7 yoke 23 is less than the thickness of

throat

21 and 22 and the thickness of the stem 20 in this maximum ga(u)ge B zone.

In the specific embodiments of a racket with large-scale stem, the interior longitudinal size E of stem is 13.7647 English inch, and the interior lateral dimension F of stem is 10.1563 English inch, and length overall L is 26.960 English inch.The thickness A on stem top is 1.090 English inch, and maximum ga(u)ge B is 1.500 English inch, and thickness C is 1.000 English inch, and according to traditional grip size decision grip size, thickness D decides according to the handle size of traditional grip size.With reference to Fig. 5, the stem overall width G on racket stem top is 0.380 English inch.With reference to Fig. 7, the thickness H of yoke 23 is 1.080 English inch, and width I is 0.400 English inch.The ratio of stem maximum ga(u)ge B and maximum ga(u)ge A is 1.5/1.09 or 1.376.

The racket zone moment of inertia of the frame of maximum cross-section thickness point is a 0.33(English inch) ⁴The frequency of first beam mode under " freedom-freedom " constraints is 204 hertz, and the second beam mode frequency under " fixing-freedom " constraints is 230 hertz.

In the specific embodiment of the tennis racket of a medium size, the interior longitudinal size E of stem is 12.520 English inch, and interior lateral dimension F is 9.330 English inch, and length L is 26.938 English inch.Stem tip thickness A is 0.920 English inch, and maximum ga(u)ge B is 1.250 English inch, and thickness C is 1.000 English inch, and thickness D decides according to grip size.The stem width G on stem top is 0.405 English inch.The thickness H of yoke 23 is 0.905 English inch, and width I is 0.4497 English inch.Stem maximum ga(u)ge B is 1.25 to 0.92 or 1.3587 with the ratio of minimum thickness A.

The first beam mode frequency under " freedom-freedom " condition is 208 hertz, and the second beam mode frequency under " fixing-freedom " condition is 230 hertz.

Obtain moment of inertia from the shape and size of the racket frame shown in the illustration 3～9 about midplane MP.The rigidity of such racket will be than traditional racket height, and the ideal frequency of first beam mode is 170 to 250 hertz under " freedom-freedom " constraints, and the ideal frequency of second beam mode is 215 to 315 hertz under " fixing-freedom " condition.Maximum ga(u)ge B is approximately 1.35 to 1.38 with the ratio of minimum thickness A.

Use the graphite fibre of relative high-modulus can make frame weight saving at

layer

33 and 34, be enough to hold backplate 26, and simultaneously the gross weight of frame is remained in the normal range (NR).Frame uses about 270 gram graphite fibre and resins, and resin can be conventional resin.

Large-scale stem racket and medium-sized stem racket with special shape and size described above can both obtain desirable rigidity and frequency.Yet need to prove,, use other shape and size also to be fine as long as the rigidity that produces can guarantee desirable frequency.The frequency that its main purpose will obtain at first beam mode under " freedom-freedom " constraints is between 170 to 250 hertz, or the frequency of second beam mode is between 215 to 315 hertz under " fixing-freedom " constraints.

For the present invention is described, the front has exemplified specific embodiments of the present invention in detail, but it may be noted that those skilled in the art under the situation that does not deviate from spirit and scope of the invention, can carry out bigger modification to many details of the present invention.

Claims

1, a kind of tennis racket has the one handle part, an annular stem, a throat that is connected with stem with handle portion, racket have that a longitudinal axis that overlaps with the handle center line and one passes the longitudinal axis with the parallel plane midplane of annular stem; Described racket is characterised in that the first beam mode frequency in 170 to 250 hertz frequency scopes, under " freedom-freedom " constraints, vibration be with the vertically extending plane of midplane on.

2, said racket in the claim 1 is characterized in that wherein said frequency range is 200 hertz to 210 hertz.

3, said racket in the claim 1 is characterized in that having a frequency range 215 to 315 hertz the second beam mode frequency under " fixing-freedom " constraints, vibration be with the vertically extending plane of midplane on.

4, said racket in the claim 3, the frequency range that it is characterized in that wherein said second beam mode under " fixing-freedom " constraints is at 230 hertz to 265 hertz.

5, said racket in the claim 1 is characterized in that it is to be made by the pipe that multi-layer resinous cast graphite fibre constitutes, and the elastic modelling quantity that fiber has in some layer is 33 approximately, 000,000, the elastic modelling quantity of the fiber of another layer approximately is 45,000,000.

6, said racket in the claim 5 is characterized in that wherein the elastic modelling quantity of 10 to 20 fiber approximately is 45,000, and the elastic modelling quantity of 000, percent eight ten to 90 fiber approximately is 33,000,000.

7, said racket in the claim 1 is characterized in that it is to be formed by the pipe that 12 layers of resin-cast graphite fibre constitute, and wherein the elastic modelling quantity of two-layer fiber approximately is 45,000,000, and the elastic modelling quantity of the fiber of other layer approximately is 33,000,000.

8, said racket in the claim 1, it is characterized in that wherein throat comprises the pair of frames part, they separate at handle portion, close up in stem, racket also comprises a yoke, and it extends between the frame part that separates, and forms the bottom of racket annular stem, frame thickness is vertical with midplane, partly locates to have maximum at yoke with the split-frame in the frame part rendezvous area of separating.

9, said racket in the claim 8, the maximum ga(u)ge that it is characterized in that said racket wherein is 1.35 to 1.38 with the ratio of the thickness of clapping the stem top.

10, said racket in the claim 8 is characterized in that wherein the thickness of racket is to successively decrease continuously from described maximum ga(u)ge to the stem top, and also is to successively decrease continuously from described maximum ga(u)ge to the handle portion top.

11, a kind of tennis racket, a handle portion is arranged, an annular stem, a throat that is connected with stem with handle portion, racket has a longitudinal axis that overlaps with the handle center line, has one to extend through the longitudinal axis and the parallel plane midplane of annular stem, and described racket is characterised in that it has on the plane vertical with said midplane, the first beam mode frequency under " fixing-freedom " constraints, its scope is greatly about 215 to 315 hertz.

12, it has the frequency of second beam mode under " fixing-freedom " constraints in the pass for said racket in the claim 11, its feature, and its scope is at 230 to 265 hertz.